Won Jae Lee

Korea Electrotechnology Research Institute-KERI, Tsau-liang-hai, Busan, South Korea

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Publications (263)472.1 Total impact

  • Nam-il Tak, Min-Hwan Kim, Won Jae Lee
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    ABSTRACT: The complex geometry of the hexagonal fuel blocks of the prismatic fuel assembly in a very high temperature reactor (VHTR) hinders accurate evaluations of the temperature profile within the fuel assembly without elaborate numerical calculations. Therefore, simplified models such as a unit cell model have been widely applied for the analyses and designs of prismatic VHTRs since they have been considered as effective approaches reducing the computational efforts. In a prismatic VHTR, however, the simplified models cannot consider a heat transfer within a fuel assembly as well as a coolant flow through a bypass gap between the fuel assemblies, which may significantly affect the maximum fuel temperature. In this paper, a three-dimensional computational fluid dynamics (CFD) analysis has been carried out on a typical fuel assembly of a prismatic VHTR. Thermal behaviours and heat transfer within the fuel assembly are intensively investigated using the CFD solutions. In addition, the accuracy of the unit cell approach is assessed against the CFD solutions. Two example situations are illustrated to demonstrate the deficiency of the unit cell model caused by neglecting the effects of the bypass gap flow and the radial power distribution within the fuel assembly.
    Annals of Nuclear Energy 10/2008; 35(10):1892-1899. · 0.80 Impact Factor
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    ABSTRACT: The purpose of this study was to evaluate the change in contrast enhancement of HCC on 1-month follow-up CT after local radiotherapy (RT) as an early predictor of final treatment response. Fifty patients who underwent local RT for HCCs had both pre-RT and post-RT CT scans including 1-month follow-up CT. We assessed the final treatment response by using the change in maximal tumor size on 6-12-month follow-up CT scan after RT. We also evaluated the change in tumor enhancement between pre-RT and 1-month follow-up CT scans. A final treatment response was achieved in 27 (54%) of 50 patients, who showed either a complete response (n=11) or a partial response (n=16). Compared with non-responsive patients (n=23), responsive patients showed a significant decrease in tumor enhancement on 1-month follow-up CT after RT in both objective and subjective analyses (each P<0.001). The change in contrast enhancement of HCC seen on the 1-month follow-up CT in patients after local RT may be used as an early predictor of final treatment response.
    European journal of radiology 10/2008; 72(3):440-6. · 2.65 Impact Factor
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    ABSTRACT: One of the key issues in the development of the very high temperature gas-cooled reactor (VHTR) is an undesirably high temperature of the nuclear fuels. An increased reactor coolant outlet temperature directly drives an increase of the nuclear fuel temperature. Therefore, a special measure has to be taken to overcome the issue of a fuel temperature in the VHTR. In this paper, a double-side-cooled annular fuel concept for a prismatic type reactor is proposed to solve the fuel temperature issue. A detailed thermo-fluid analysis using a computational fluid dynamics (CFD) code was carried out to investigate the thermo-fluid performances of the proposed fuel design. The CFD results show that the proposed design has superior thermo-fluid characteristics to the existing prismatic fuel assembly designs.
    Nuclear Engineering and Design 10/2008; 238(10):2821-2827. · 0.81 Impact Factor
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    ABSTRACT: Radiofrequency ablation has been accepted as the most popular local ablative therapy for unresectable malignant hepatic tumors. For 9 years from April 1999, we performed 3000 radiofrequency ablation procedures for hepatic tumors in our institution. Our results on the safety (mortality, 0.15%/patient) and therapeutic efficacy (5-year survival rate, 58%) are similar to those of previous studies reported, supporting the growing evidence of a clear survival benefit, excellent results for local tumor control and improved quality of life. The most important lesson learned from our 3000 procedures is that the best planning, safe ablation and complete ablation are key factors for patient outcome. Furthermore, multimodality treatment is the best strategy for recurrent hepatocellular carcinoma encountered after any kind of first-line treatment.
    Journal of Gastroenterology and Hepatology 09/2008; 23(10):1492-500. · 3.33 Impact Factor
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    ABSTRACT: The purpose of this study was to evaluate with serial follow-up CT examinations the growth rate of new hepatocellular carcinoma (HCC) developing after percutaneous radiofrequency ablation and to determine an appropriate follow-up interval for imaging. Sixty-two new HCCs appearing after percutaneous radiofrequency ablation in 59 patients who underwent follow-up multiphase CT were retrospectively identified. The volume of the new HCCs at follow-up CT was measured on a PACS monitor with an area measuring tool and summation-of-areas technique. We calculated tumor volume doubling time and tumor diameter doubling time. The growth rate was represented by tumor volume doubling time. We also used stepwise multiple linear regression analysis to evaluate the relation between clinical variables and tumor volume doubling time. Mean baseline and follow-up tumor volumes were 580 mm(3) (range, 85-13,861 mm(3)) and 2,072 mm(3) (range, 535-35,937 mm(3)). Mean baseline and follow-up tumor diameters were 9.9 mm (range, 5.5-29.8 mm) and 15.0 mm (range, 10.1-40.9 mm). Mean tumor volume and tumor diameter doubling times were 75 days (range, 21-209 days) and 219 days (range, 57-897 days). Volume doubling times of baseline tumors with a diameter of 1 cm or less were significantly shorter than those of the larger baseline tumors (mean, 55 vs 88 days; p = 0.024). The growth rate of new HCCs after percutaneous radiofrequency ablation was higher than that reported in natural outcome studies of untreated HCCs. The results of our study suggest that a shorter follow-up interval for imaging, 2.5 months (75 days), is appropriate.
    American Journal of Roentgenology 08/2008; 191(1):215-20. · 2.90 Impact Factor
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    ABSTRACT: Intraoperative radiofrequency (RF) ablation with or without surgical resection currently plays one of important roles in modern hepatocellular carcinoma (HCC) therapy. We evaluated long-term follow-up results including prognostic factors of intraoperative RF ablation for HCC that was difficult to treat percutaneously. A total of 133 patients (male, 22 female, mean age 55.8 years) underwent intraoperative RF ablations for 200 HCCs (follow-up period 3.0-79.7 months, median 22.3 months). Hepatic resection was also performed in 29 patients. Reasons for the intraoperative procedure included no safe electrode path (n = 59), excessive tumor burden (n = 41), nonvisualization of the HCC on ultrasonography (n = 20), and risk of collateral thermal damage to adjacent organs (n = 13). We evaluated the technique effectiveness rate at 1 month computed tomography (CT), cumulative local tumor progression rate, cumulative disease-free and overall survival rates, and complications. We also sought significant prognostic factors for overall survival. The technique effectiveness at 1 month was 94.7% (126/133). The cumulative local tumor progression rates at 1 and 3 years were 4.9% and 8.8%, respectively. The cumulative disease-free and overall survival rates at 1, 3 and 5 years were 51.8%, 21.3%, and 16.0% and 92.3%, 72.6%, and 46.5%, respectively. Major complications occurred in nine patients (6.8%). Procedure-related mortality was 1.5% (2/133). The patients treated for recurrent HCC (P = 0.003) or with high serum alpha-fetoprotein levels (P = 0.009) had poor survival by multivariate analysis. The results of this study showed that intraoperative radiofrequency ablation with or without hepatic resection is a safe and effective treatment for hepatocellular carcinoma in patients who are not candidates for the percutaneous approach.
    Annals of Surgical Oncology 08/2008; 15(7):1862-70. · 4.12 Impact Factor
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    ABSTRACT: In order to assess the diagnostic performance of Positron emission tomography/Computed tomography (PET/CT) for detecting recurrence in gastric cancer patients with clinical or radiologic suspicion of recurrence after surgical resection. Over a 4-year period, 105 post-operative patients with gastric cancer, who underwent PET/CT due to clinical or radiologic suspicion of recurrence during follow-up, were collected after confirming their PET/CT findings. The number and site of positive FDG uptake were retrospectively analyzed, and were correlated with the final diagnosis, by calculating the diagnostic values and assessing the causes of misdiagnosis. Of all 105 patients, 75 patients were confirmed to have true recurrence with 108 recurrence sites. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy for diagnosing true recurrence on a per-person basis were 75%, 77%, 89%, 55%, and 75%, respectively. On a per-lesion basis, 75 (69%) of 108 true recurrences showed positive FDG uptake, while 75 (89%) of 84 positive FDG uptake was confirmed to have true recurrence. PET/CT was relatively accurate in detecting recurrence in post-operative patients with gastric cancer. Moreover, PET/CT might be helpful in confirming the presence of recurrence particularly in patients who were highly suspicious of recurrence, because of its high positive predictability.
    Abdominal Imaging 07/2008; 34(4):441-7. · 1.91 Impact Factor
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    ABSTRACT: OBJECTIVE: The purpose of our study was to assess the morphologic pattern and exact site of local tumor progression with relation to various risk factors after radiofrequency ablation of liver tumors. CONCLUSION: Local tumor progression after radiofrequency ablation shows mostly the peripheral nodular type. The site of local tumor progression shows a higher concordance rate with insufficient ablative margin than contiguous vessel and subcapsular location.
    American Journal of Roentgenology 07/2008; 190(6):1544-51. · 2.90 Impact Factor
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    ABSTRACT: The objective of our study was to evaluate the feasibility rate and the reasons for infeasibility of percutaneous radiofrequency ablation of hepatocellular carcinomas (HCCs) at planning sonography. We retrospectively evaluated 248 patients who had been referred for planning sonography at our department between October 2005 and February 2006. We reviewed the radiologic reports of 256 planning sonography examinations in terms of the rate of feasible cases and the reasons for infeasibility. The reasons for infeasibility were classified in six categories: an inconspicuous tumor, an inadequate electrode path, an organ vulnerable to collateral thermal damage, a tumor that was too large or too many tumors, and a high risk of the heat sink effect. In addition, we assessed the treatment modality for the patients who were determined to have HCCs for which percutaneous radiofrequency ablation was not feasible. In 141 (55%) of the 256 planning sonography examinations, percutaneous radiofrequency ablation was feasible. The remaining 115 (45%) planning sonography examinations revealed that radiofrequency ablation was not a feasible procedure. The reasons for infeasibility included an inconspicuous tumor in 77 patients (55.8%), an inadequate electrode path in 33 patients (23.9%), an organ vulnerable to collateral thermal damage in 14 patients (10.1%), a tumor that was too large or too many tumors in eight patients (5.8%), a high risk of the heat sink effect in five patients (3.6%), and a portal vein thrombosis in one patient (0.7%). One reason for infeasibility was found in 96 patients, two reasons in 19 patients, and four reasons in one patient. Seventy (61.9%) of 113 patients for whom radiofrequency ablation was not feasible underwent transcatheter arterial chemoembolization as an alternative treatment. In approximately half of the patients for whom percutaneous radiofrequency ablation of HCC is requested, the procedure is not feasible, mainly due to inconspicuous tumors, at planning sonography. Additional objective criteria for assessing the feasibility of radiofrequency ablation and therapeutic strategies according to the reasons for infeasibility should be investigated further.
    American Journal of Roentgenology 06/2008; 190(5):1324-30. · 2.90 Impact Factor
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    ABSTRACT: The purpose of this study was to evaluate the effect of artificial ascites on thermal injury to the diaphragm and stomach in a porcine model of radiofrequency ablation of the liver. We performed this study using eight pigs in experimental and control groups of four pigs each. Artificial ascites was produced before radiofrequency ablation to separate the liver from the diaphragm and the stomach in the experimental group. Using a 1-cm exposed internally cooled radiofrequency electrode for 5 minutes, we performed 74 hepatic ablations abutting the diaphragm and stomach. CT was performed on the day of the procedure and 7 days after ablation. The pigs were sacrificed, and necropsy was performed. We performed pathologic and CT examinations to compare the frequency and extent of thermal injury to the two organs. The mean number of radiofrequency ablations in each pig was 9.3 (range, 6-12). The mean number of ablation zones adjoining the diaphragm was 5.5 (range, 3-8) and of zones contiguous with the stomach was 3.8 (range, 3-4). Thermal injury to the adjacent organs occurred more frequently in the control group than in the experimental group (p < 0.05). The major complications of diaphragmatic hernia and gastric perforation occurred only in the control group. No major complications were identified in the experimental group at necropsy. The sizes of the radiofrequency ablation zone of the liver did not differ between the two groups (p > 0.05). The mean diameters of the diaphragmatic and gastric lesions did differ (p < 0.05). Histopathologic examination revealed a significant difference in the depths of thermal injury in the two groups (p < 0.05). Artificial ascites may be a simple and useful technique for reducing the frequency and severity of collateral thermal injury to the diaphragm and stomach during radiofrequency ablation of subcapsular hepatic tumors.
    American Journal of Roentgenology 06/2008; 190(6):1659-64. · 2.90 Impact Factor
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    ABSTRACT: To assess useful CT features for differentiating benign from premalignant and malignant macrocystic pancreatic lesions. Seventy-four patients with pathologically proven macrocystic pancreatic lesions were enrolled: 17 benign cysts (macrocystic serous cystadenoma, n=12; congenital cyst; n=5) and 57 premalignant and malignant cysts (mucinous cystic neoplasm, n=28; intraductal papillary mucinous neoplasm of branch duct type, n=20; tumor with cystic change, n=9). Size, location, shape (lobulated, round or oval, or complex cystic with tubular cyst), wall thickness (thin, < or =1mm; thick, >1mm), internal surface (smooth or irregular), and other findings were analyzed with multiphasic CT with thin-section (2.5-3mm) images. CT features between two groups were compared using univariate and multivariate stepwise logistic regression analyses. On univariate analysis, the differences for the shape (p=0.007), wall thickness (p=0.011), and internal surface (p=0.012) between benign and premalignant and malignant cysts were significant. A lobulated shape, a thin wall and a smooth internal surface were more frequent in benign cysts, whereas a round or oval shape or a complex cystic shape with tubular cyst, a thick wall and an irregular internal surface were more frequent in premalignant and malignant cysts. On multivariate analysis, the shape (p=0.002) and wall thickness (p=0.025) were significant CT features for differentiating benign from premalignant and malignant cysts. Shape and wall thickness are the main CT features for differentiating benign from premalignant and malignant macrocystic pancreatic lesions.
    European journal of radiology 05/2008; 71(1):122-8. · 2.65 Impact Factor
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    ABSTRACT: The objective of the study was to investigate the effects of rosiglitazone (RSG), a thiazolidinedione derivative, on body fat distribution and insulin sensitivity in Korean subjects with type 2 diabetes mellitus. This study was a phase IV, multicenter, single-blind, positive-controlled parallel group study. Eighty-nine patients with type 2 diabetes mellitus, aged 30 to 75 years, were enrolled in this study. Their fasting plasma glucose levels ranged from 126 to 270 mg/dL, and subjects had hemoglobin A1c levels of greater than 7.0%. We compared the effect of the treatment with glibenclamide plus RSG 4 mg/d (increased to 8 mg/d after 6 months) with glibenclamide plus placebo on body fat distributions, which were determined by computed tomography scanning and glycemic and insulinemic responses to oral glucose load. During the 12-month treatment period, the difference between the changes in the ratio of the intraabdominal adipose tissue (IAAT) to abdominal subcutaneous adipose tissue areas (SAT) between treatment groups was significant (from 1.13 +/- 0.53 to 1.00 +/- 0.40 in the RSG group and from 0.92 +/- 0.54 to 0.96 +/- 0.62 in the placebo group, P = .0351). The glycemic responses to oral glucose load (area under the curve, millimoles per liter per hour) were improved in the RSG group with 12 months of treatment (from 4.88 +/- 1.10 to 4.38 +/- 1.35 in 1 hour and from 13.78 +/- 2.83 to 12.16 +/- 2.52 in 2 hours), and the difference between the changes of the glycemic response showed statistical significance between groups (RSG group vs placebo group: -0.53 +/- 1.42 vs 0.38 +/- 1.31, difference in 1 hour; -0.76 +/- 2.98 vs 1.43 +/- 2.58, difference in 2 hours). However, there was no difference between insulin responses from baseline to follow-up and no differences in the change in insulin response between groups. In Korean subjects with type 2 diabetes mellitus, 12 months of treatment with RSG may increase SAT, but may have a neutral effect on IAAT, resulting in a decrease in the IAAT:SAT ratio. The RSG treatment improved the glucose control in type 2 diabetes mellitus. However, it is important to determine whether the glucose-lowering effect of RSG occurs mainly through direct enhancement of insulin sensitivity.
    Metabolism 05/2008; 57(4):479-87. · 3.10 Impact Factor
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    Won Jae Lee
    The Korean Journal of Hepatology 04/2008; 14(1):113-5.
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    ABSTRACT: For providing high quality multimedia streaming services over high speed network, various solutions such as performance improvement of computer system, efficient cluster management and request dispatching into back-end nodes, good load balancing scheme, global infrastructure management and efficient contents distribution mechanism are required. In this paper, we will describe the global request dispatching scheme in design and implementation aspects for supporting high quality multimedia streaming services in high speed network environments. With this scheme, we can get good performance and correctness in dispatching service requests.
    Advanced Communication Technology, 2008. ICACT 2008. 10th International Conference on; 03/2008
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    ABSTRACT: The aims of this study are to evaluate and compare the accuracies of isotropic multi-detector row CT (MDCT) including multiplanar reconstruction (MPR) images for preoperative staging of endoscopically diagnosed early gastric cancer (eEGC) and advanced gastric cancer (eAGC). One hundred and five patients with endoscopically proven gastric cancer underwent isotropic MDCT. Three independent radiologists evaluated T and N staging both on transverse images only and on three orthogonal MPR images. The staging of each tumor was surgico-pathologically confirmed. The receiver operating characteristic (ROC) analysis and the Wilcoxon signed ranked test were used for statistical analyses. In 30 eAGCs, the accuracies for T and N staging with MPR imaging were better than those with transverse imaging (each P < 0.05). In 34 eEGCs, however, only the accuracy of T2 or higher with MPR imaging was higher than that with transverse imaging (P < 0.05). Isotropic MDCT with MPR images including coronal or sagittal reconstructions can improve the accuracies of preoperative T and N staging of eAGC, while having little impact on the accuracy for eEGC.
    Abdominal Imaging 03/2008; 34(1):26-34. · 1.91 Impact Factor
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    ABSTRACT: The purpose of our study was to evaluate the histopathologic changes of gallbladder wall surrounding radiofrequency ablation zones in pig livers and to assess the risk factors for thermal injury of gallbladder wall in terms of distance of the electrode, electrode direction in relation to the gallbladder wall, and time of sacrifice of the animal. The study was performed in 15 pigs using an internally cooled single electrode with a 1-cm electrically active tip under sonographic guidance. Twenty-three hepatic ablation zones abutting the gallbladder were analyzed in three phases on the basis of the distance of the electrode (group A, 0.5 cm; group B, 1.0 cm), electrode direction (perpendicular or parallel), and time of sacrifice (immediate or delayed [7 days after radiofrequency ablation]). We evaluated the gross changes, the depth of thermal injury, and the grade of abnormal microscopic changes in the gallbladder wall. Data analysis was performed on the basis of the Fisher's exact test. Discoloration and perforation were more frequent in group A (60%, 6/10, and 20%, 2/10, respectively) than in group B (25%, 2/8, and 0%, respectively, p > 0.05). Perforation was more frequent in the parallel direction and delayed phase (33.3%, 1/3, and 40%, 2/5, respectively) compared with the perpendicular direction and immediate phase (14.3%, 1/7, and 0%, respectively, p > 0.05). Depth of thermal injury showed a significant difference between group A and group B for full-thickness involvement (53.8%, 7/13, versus 0%, respectively, p < 0.05). Abnormal microscopic changes showed that parallel direction and immediate phase were more frequent with full-thickness involvement (71.4%, 5/7, and 71.4%, 5/7, respectively) compared with perpendicular direction and delayed phase (33.3%, 2/6, and 33.3%, 2/6, respectively, p > 0.05). Hepatic radiofrequency ablation abutting the gallbladder can produce substantial thermal injury of the gallbladder wall, including perforation, especially when performed without a safe distance.
    American Journal of Roentgenology 03/2008; 190(2):418-25. · 2.90 Impact Factor
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    ABSTRACT: The authors describe the continuance of the growth of the distracted cranium after the reshaping of the cranium by distraction osteogenesis (DO) in children with simple symmetric and asymmetric craniosynostosis. From 2000 until 2002, 9 children with simple craniosynostosis underwent cranial reshaping by gradual distraction using an external distraction device. Four patients have symmetric deformities caused by bicoronal and sagittal craniosynostosis, and 5 patients have asymmetric deformities caused by unicoronal and unilambdoidal craniosynostosis. The distraction device was developed and applied by the author. Preoperative simulation surgery was done on the three-dimensional rapid prototyped model and on the three-dimensional computerized tomography scan to determine the favorable osteotomy line. The distraction rate was from 1 to 1.5 mm/d, and the latency period was from 1 to 5 days. The extent of distraction was determined on the basis of the results of simulation surgery and the change of external appearance. Evaluation of the growth of reshaped cranium was processed from the data of the reconstructed three-dimensional computerized tomography scans before operation, immediate end of distraction, and the last follow-up time. The anteroposterior length and bitemporal width were measured in symmetric synostosis cases, and the distance from supratrochlear notch to occiput was measured in asymmetric synostosis cases. The results showed that the immediate morphologic changes of cranium after DO were maintained in both symmetric and asymmetric synostosis up to the last follow-up without evidence of relapse. Cases of asymmetric deformity also showed that the affected side and the unaffected side had grown with the maintenance of the symmetry that was corrected at the immediate end of the distraction. The cranium modified by the DO was well maintained with the children's growth without any signs of recurrent restricted growth of the original disease. The corrected symmetry of asymmetric deformity was well maintained during a long-term follow-up period as well.
    Journal of Craniofacial Surgery 02/2008; 19(1):45-55. · 0.69 Impact Factor
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    ABSTRACT: In an effort to discover sulfur-oxidizing microorganisms, a new bacterium was screened from barnyard manure. This strain was identified as Enterobacter hormaechei JH by its morphological, physiological, and biochemical properties, as well as by 16S rRNA gene sequence analysis. E. hormaechei JH are Gram-negative rod, non-spore-forming, and aerobic. The pH range for E. hormaechei JH growth was 2.0–9.0, and the optimal pH was determined as pH 7.0. The optimal temperature for growth was 30°C. We compared the growth of this strain with Thiobacillus delicates KCTC2851, which is a well known thiosulfate oxidizing microorganism. E. hormaechei JH presented greater growth than T. delicates KCTC2851. Thus, the above results indicate this strain is a candidate for improving the removal efficiency of biological deodorizing systems.
    Korean Journal of Chemical Engineering 01/2008; 25(5):1131-1135. · 1.06 Impact Factor
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    ABSTRACT: Image-guided radiofrequency (RF) ablation has been used to treat both resectable and nonresectable hepatic tumors. A precise imaging assessment of the therapeutic response and of any complications is mandatory after ablation. Contrast material-enhanced ultrasonography, computed tomography (CT), and magnetic resonance imaging all may be useful for this assessment. At most institutions, a three-phase contrast-enhanced CT examination is performed immediately or within 1 month after RF ablation to assess the technical success of treatment. If ablation was technically successful, three-phase CT may be repeated at 3-month intervals for evaluation of tumor recurrence. The typical CT finding in the zone subjected to RF ablation is an area of low attenuation that encompasses the tumor and an ablative margin. However, the appearance of the ablative zone may vary greatly, depending on the success of treatment and the time elapsed after the procedure. Ringlike enhancement representing benign reactive hyperemia around the ablation zone, central high-attenuation areas representing greater cellular disruption, and tiny air bubbles frequently are seen at immediate follow-up CT but usually have disappeared by the first or second follow-up examination. The successfully ablated zone gradually involutes. The appearance of the zone differs when residual tumor tissue or local tumor progression is present. Immediate or delayed complications also may be seen at follow-up CT. Radiologists must be familiar with both typical and atypical CT findings and their clinical significance. (c) RSNA, 2008.
    Radiographics 01/2008; 28(2):379-90; discussion 390-2. · 2.79 Impact Factor
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    ABSTRACT: Spray coated multi-wall carbon nanotube (CNT) film on fluorine-doped tin oxide glass substrate has been investigated as a counter electrode for tri-iodide reduction in dye-sensitized solar cells. The photovoltaic parameters, in particular, the fill factor shows a strong dependency on the spraying time of multi-wall CNTs. Under one sun illumination (100 mW cm−2, AM 1.5 G), the device shows a maximum energy conversion efficiency of 7.59%. Electrochemical impedance spectroscopy analysis reveals a decrease in the charge transfer resistance of multi-wall CNT counter electrode with increase of spraying time; leads to an improvement in the photovoltaic parameters.
    Electrochemistry Communications. 01/2008;

Publication Stats

2k Citations
472.10 Total Impact Points

Institutions

  • 2002–2014
    • Korea Electrotechnology Research Institute-KERI
      • Battery Research Center
      Tsau-liang-hai, Busan, South Korea
    • Sungkyunkwan University
      • • Samsung Medical Center
      • • Department of Radiology
      Sŏul, Seoul, South Korea
  • 1998–2014
    • Gachon University
      • Department of Electronic Engineering
      Sŏngnam, Gyeonggi Province, South Korea
  • 2013
    • University of Yamanashi
      • Department of Radiology
      Kōhu, Yamanashi, Japan
  • 2008–2013
    • Korea Atomic Energy Research Institute (KAERI)
      Daiden, Daejeon, South Korea
    • Pukyong National University
      • Department of Microbiology
      Tsau-liang-hai, Busan, South Korea
  • 2010
    • Kangbuk Samsung Hospital
      Sŏul, Seoul, South Korea
    • Yeungnam University
      • Division of Internal Medicine
      Onyang, South Chungcheong, South Korea
  • 2009–2010
    • Dong-Eui University
      • • Department of Materials and Components Engineering
      • • Department of Visual Information Engineering
      Tsau-liang-hai, Busan, South Korea
    • Hallym University Medical Center
      • Department of Pathology
      Seoul, Seoul, South Korea
  • 2002–2005
    • University of Leeds
      • Department of Colour Science
      Leeds, England, United Kingdom
  • 2004
    • Yonsei University
      • College of Medicine
      Seoul, Seoul, South Korea
  • 1999–2004
    • Seoul National University
      • • School of Computer Science and Engineering
      • • Department of Materials Science and Engineering
      • • School of Electrical Engineering and Computer Sciences
      • • Department of Electrical and Computer Engineering
      Seoul, Seoul, South Korea
  • 2003
    • Hyundai Heavy Industries
      Urusan, Ulsan, South Korea
  • 1996–2001
    • Korea Advanced Institute of Science and Technology
      • • Department of Mechanical Engineering
      • • Department of Materials Science and Engineering
      Seoul, Seoul, South Korea
  • 1998–1999
    • Pusan National University
      Tsau-liang-hai, Busan, South Korea
  • 1995
    • Tokyo Institute of Technology
      • Department of Physical Electronics
      Edo, Tōkyō, Japan