Seung Ho Choi

Korea University, Sŏul, Seoul, South Korea

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Publications (102)243.24 Total impact

  • Seung Ho Choi, Yun Chan Kang
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    ABSTRACT: MoS2 -amorphous carbon (MoS2 -AC) composite microspheres with macroporous structure were fabricated by one-pot spray pyrolysis. Single- or few-layered MoS2 were uniformly dispersed and oriented in random directions in the amorphous carbon microsphere with macropores sizes between 50 and 90 nm. The macroporous microspheres having a high contact area with liquid electrolyte exhibited overall superior Li- and Na-ion storage properties compared with those of the dense microspheres. After 250 charge/discharge cycles at a current density of 1.5 A g(-1) , the discharge capacities of the MoS2 -AC microspheres with dense and macroporous structures for Li-ion storage were 694 and 896 mAh g(-1) , respectively. In the case of Na-ion storage, discharge capacities of 336 and 425 mAh g(-1) were achieved for the dense and macroporous microspheres, respectively, after 100 cycles at 0.3 A g(-1) . © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    ChemSusChem 06/2015; DOI:10.1002/cssc.201500063 · 7.12 Impact Factor
  • Seung Ho Choi, Yun Chan Kang
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    ABSTRACT: SnS-C composite powders were prepared through one-pot spray pyrolysis for use as anode materials for Na-ion batteries. C microspheres with uniformly attached cubic-like SnS nanocrystals, which have an amorphous C coating layer, were formed at a preparation temperature of 900 °C. The initial discharge capacities of the bare SnS and SnS-C composite powders at a current density of 500 mA·g−1 were 695 and 740 mA·h·g−1, respectively. The discharge capacities after 50 cycles and the capacity retentions measured from the second cycle of the bare SnS and SnS-C composite powders were 25 and 433 mA·h·g−1 and 5 and 89%, respectively. The prepared SnS-C composite powders with high reversible capacities and good cycle performance can be used as Na-ion battery anode materials.
    Nano Research 05/2015; 8(5). DOI:10.1007/s12274-014-0648-z · 6.96 Impact Factor
  • Seung Ho Choi, Yun Chan Kang
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    ABSTRACT: The electrochemical properties of binary transition metal sulfide-reduced graphene oxide (RGO) composite powders, relevant for their performance as anode materials in sodium ion batteries, are firstly studied. (Ni,Co)O-RGO composite powders prepared by spray pyrolysis are transformed into Ni3Co6S8-RGO composite powders by a simple sulfidation process. Plate-shape nanocrystals of nickel-cobalt sulfide (Ni3Co6S8) are uniformly distributed over the crumpled RGO structure. The discharge capacities of the Ni3Co6S8-RGO composite powders for 2nd and 100th cycles at a current density of 0.5 A g-1 are 504 and 498 mA h g-1, respectively. However, the discharge capacities of the bare Ni3Co6S8 powders for 2nd and 100th cycles are 522 and 125 mA h g-1, respectively. The NiO-Co3O4 and (Ni,Co)O-RGO composite powders prepared by spray pyrolysis also show low discharge capacities of 122 and 119 mA h g-1, respectively, after 100 cycles. The high structural stability of the Ni3Co6S8-RGO composite powders during repeated sodium ion intercalation/deintercalation processes results in excellent cycling and rate performances for Na+ storage.
    Nanoscale 03/2015; 7(14). DOI:10.1039/C5NR00012B · 6.74 Impact Factor
  • Seung Ho Choi, Yun Chan Kang
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    ABSTRACT: Layered WS2 nanosheet-decorated three-dimensional reduced graphene oxide (3D-RGO) microspheres are prepared as anode materials for sodium ion batteries. WO3 nanocluster-decorated 3D RGO microspheres are transformed into multi-layered WS2-3D RGO microspheres by a simple sulfidation process. The WS2-3D RGO microspheres show Na(+) storage properties superior to those of the WO3-3D RGO microspheres.
    Nanoscale 02/2015; 7(9). DOI:10.1039/c4nr06880g · 6.74 Impact Factor
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    ABSTRACT: Background To investigate the role of lymph node density (LND) as an independent prognostic factor in high-grade salivary gland cancers.Methods All 87 patients with high-grade salivary gland cancers underwent curative surgery combined with neck dissection and most of them received postoperative radiotherapy or chemoradiotherapy. LND was calculated as the ratio of positive lymph nodes to total lymph nodes harvested. Clinicopathologic variables associated with cancer-specific survival (CSS) and overall survival (OS) were identified by univariate and multivariate analyses using the Cox-proportional hazards model.ResultsSalivary duct carcinoma was the most common tumor (54%), followed by carcinoma ex pleomorphic adenoma (22%), and others. The 5-year CSS and OS were 50.9% and 49.6%, respectively, during a median follow-up of 61 months. In univariate analysis, tumor site, pathologic nodal stage, overall tumor-node-metastasis (TNM) stage, primary tumor size >3 cm, lymphovascular invasion, perineural invasion, extranodal extension, number of metastatic lymph nodes, and LND >4.0 were significant prognostic factors for CSS and OS (P < 0.05 each). Tumor site, perineural invasion, and LND were independent prognostic factors for both CSS and OS in multivariate analysis (P < 0.01).Conclusion Our findings support the prognostic value of LND for high-grade salivary gland cancers. J. Surg. Oncol. © 2015 Wiley Periodicals, Inc.
    Journal of Surgical Oncology 01/2015; 111(6). DOI:10.1002/jso.23874 · 2.84 Impact Factor
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    ABSTRACT: BACKGROUND The prognostic role of swallowing-related, pretreatment subjective and objective findings has not been investigated in detail. The authors evaluated the association between pretreatment MD Anderson Dysphagia Inventory (MDADI) or videofluorographic swallowing study (VFSS) results and standard outcomes, including early recurrence and survival, in patients with treatment-naïve head and neck squamous cell carcinoma (HNSCC).METHODS Patients with HNSCC (n = 191) who received treatment at the authors' institution and were examined by self-administered MDADI questionnaires and VFSS were prospectively enrolled. MDADI and VFSS findings were analyzed in correlation with clinicopathologic variables, and factors that predicted 2-year disease-free survival (DFS) and overall survival (OS) were identified using a Cox proportional-hazards regression model.RESULTSThe 2-year OS and DFS rates were 80.1% and 77.5%, respectively. Clinical tumor (T) and lymph node (N) classifications, overall TNM stage, sex, tumor site, and educational level were significantly associated with specific MDADI subdomains, whereas Karnofsky performance score was significantly associated with all MDADI subdomains. After controlling for clinical factors, total scores, global assessment scores, and emotional and physical MDADI subscores were significantly predictive of 2-year OS and DFS (P < .05 for each). VFSS findings were not significantly associated with survival (P > .05).CONCLUSIONS The current results provide evidence of the prognostic role of the MDADI in predicting early survival outcomes in patients with HNSCC. The MDADI may be a practical and noninvasive method for the identification of patients at risk who would benefit from close follow-up. Cancer 2015. © 2015 American Cancer Society.
    Cancer 01/2015; 121(10). DOI:10.1002/cncr.29245 · 4.90 Impact Factor
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    ABSTRACT: Tonal signals are shown as spectral peaks in the frequency domain. When the number of spectral peaks is small and the spectral signal is sparse, Compressive Sensing (CS) can be adopted to locate the peaks with a low-cost sensing system. In the CS scheme, a time domain signal is modelled as $\boldsymbol{y}=\bPhi F^{-1}\boldsymbol{s}$, where y and s are signal vectors in the time and frequency domains. In addition, F-1 and $\bPhi$ are an inverse DFT matrix and a random-sampling matrix, respectively. For a given y and $\bPhi$, the CS method attempts to estimate s with l0 or l1 optimization. To generate the peak candidates, we adopt the frequency-domain information of $\resmile{\boldsymbol{s}}$ = $\boldsymbol{F}\resmile{\boldsymbol{y}}$, where $\resmile{y}$ is the extended version of y and $\resmile{\boldsymbol{y}}\left(\boldsymbol{n}\right)$ is zero when n is not elements of CS time instances. In this paper, we develop Gaussian statistics of $\resmile{\boldsymbol{s}}$. That is, the variance and the mean values of $\resmile{\boldsymbol{s}}\left(\boldsymbol{k}\right)$ are examined.
    IEICE Transactions on Fundamentals of Electronics Communications and Computer Sciences 01/2015; E98.A(5):1122-1125. DOI:10.1587/transfun.E98.A.1122 · 0.23 Impact Factor
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    ABSTRACT: Maintenance of a remifentanil infusion during anesthetic emergence has been reported to decrease the incidence of coughing and thereby help to ensure a smooth emergence. It may, however, cause respiratory depression and possibly delay emergence. The purpose of this study was to investigate the effect of a single dose of dexmedetomidine combined with a low-dose remifentanil infusion on cough suppression during emergence from general anesthesia. American Society of Anesthesiologists physical status I-II adults undergoing elective thyroidectomy under sevoflurane anesthesia were recruited and randomly allocated to receive either dexmedetomidine 0.5 μg·kg(-1) iv (Group D, n = 70) or saline (Group S, n = 71), each combined with a low-dose remifentanil infusion ten minutes before the end of surgery. Coughing was assessed using a four-point scale. The respiratory rate (RR), heart rate (HR), and mean arterial pressure were also recorded. The incidence of coughing was lower in Group D than in Group S (64% vs 91%, respectively; mean difference 27%; 95% confidence interval [CI] 13 to 41; P < 0.001). The median cough grade at extubation was also lower in Group D. Mean arterial pressure and HR were elevated in Group S during tracheal extubation but were similar to baseline values in Group D. There was no difference in RR between the two groups throughout the study. A small delay in extubation was observed in Group D (3 minutes longer than Group S; 95% CI 2 to 4; P < 0.001). Compared with an infusion of low-dose remifentanil alone, the addition of a single dose (0.5 μg·kg(-1)) of dexmedetomidine during emergence from sevoflurane-remifentanil anesthesia was effective in attenuating coughing and hemodynamic changes and did not exacerbate respiratory depression after thyroid surgery. This trial was registered at Clinicaltrial.gov, identifier: NCT01774305.
    Canadian Journal of Anaesthesia 12/2014; 62(4). DOI:10.1007/s12630-014-0295-6 · 2.50 Impact Factor
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    ABSTRACT: It is difficult to precisely detect the lateral margin during endoscopic submucosal dissection (ESD) for signet ring cell carcinoma (SRC) because SRC often expands to lateral direction through the lamina propria. Thus, the aim of this study was to classify the intramucosal spreading patterns of SRC and to analyze the patients' clinicopathological findings according to the spreading patterns. The intramucosal spreading patterns of SRC were classified as expansive or infiltrative types. A total of 100 surgical and 42 ESD specimens were reviewed. In the surgical specimens, the proportions of expansive and infiltrative types were 44% and 56%, respectively. The infiltrative type was more commonly associated with old age, atrophy, and intestinal metaplasia in surrounding mucosa and the absence of Helicobacter pylori compared with the expansive type. In ESD specimens, the proportions of expansive and infiltrative types were each 50%. When lateral margin-positive lesions were compared with -negative lesions, larger size, residual lesion, and the lack of a neutrophil infiltration were more significantly associated with lateral margin-positive lesions. All cases with residual tumors in lateral margin-positive lesions were classified as the infiltrative type. SRC surrounded with atrophy and/or intestinal metaplasia often spreads subepithelially in the margin. This finding may suggest that a larger safety margin is necessary in this type during ESD. (Gut Liver, Published online December 5, 2014).
    Gut and liver 12/2014; DOI:10.5009/gnl14203 · 1.49 Impact Factor
  • Min-Soo Kim, Seung Ho Choi
    Journal of endourology / Endourological Society 12/2014; 29(1). DOI:10.1089/end.2015.0156 · 2.10 Impact Factor
  • Minsu Kwon, Seung‐Ho Choi
    The Laryngoscope 12/2014; 125(5). DOI:10.1002/lary.25096 · 2.03 Impact Factor
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    ABSTRACT: Background To evaluate the usefulness of metabolic tumor volume (MTV) and total lesion glycolysis (TLG) measured by pretreatment fluorine 18-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT) as predictors of clinical outcome in hypopharyngeal squamous cell carcinoma (HPSCC).Methods Seventy-eight patients with HPSCC treated with definitive radiotherapy with or without chemotherapy underwent 18F-FDG PET/CT. Maximum standardized uptake value (SUVmax), MTV, and TLG were measured. For calculation of MTV, 3-D regions of interest were drawn and a SUV threshold of 2.5 was used for defining region. Univariate and multivariate analyses identified variables associated with disease-free survival (DFS) and overall survival (OS).ResultsMedian SUVmax, MTV, and TLG were 9.0 (range, 1.7–24.5), 20.5 (0.3–339.9) ml, and 98.9 (0.8–1877.1) g, respectively. The four-year DFS and OS were 56.1% and 52.6%, respectively. On univariate and multivariate analyses, MTV (P = 0.014) and TLG (P = 0.029) were independent prognostic factors for DFS, and MTV (P = 0.002) and TLG (P = 0.002) were independent prognostic factors for OS.ConclusionMTV and TLG measured by pretreatment 18F-FDG PET/CT may be useful in predicting the clinical outcomes of HPSCC patients undergoing radiotherapy. J. Surg. Oncol. © 2014 Wiley Periodicals, Inc.
    Journal of Surgical Oncology 12/2014; 110(7). DOI:10.1002/jso.23729 · 2.84 Impact Factor
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    ABSTRACT: BACKGROUND This study was aimed at investigating the change in the prevalence of human papillomavirus (HPV) genotypes in tonsillar squamous cell carcinoma (TSCC) and the association of the HPV genotype with the prognosis.METHODS This multicenter study included 175 patients with TSCC from 3 general hospitals between 1991 and 2009. HPV DNA was detected in paraffin-embedded tissues with genotyping chips. A survival analysis that considered clinicopathological factors, the HPV genotype, and the expression of p53, retinoblastoma protein, p16, and epidermal growth factor receptor (assessed with immunohistochemistry) was performed with Cox regression analysis.RESULTSHigh-risk HPV types were found in 23.4% of the cases. The prevalence of HPV-18 (10.3%) was as high as that of HPV-16 (10.3%). The proportion of high-risk HPV-positive tumors increased from 5.9% in 1991 to 31.6% in 2009. HPV-16 positivity was associated with an advanced stage and lymph node metastasis, whereas HPV-18 positivity was associated with old age and an advanced T stage. The survival analysis showed that old age and T classification were poor prognostic factors, whereas the expressions of various biomarkers were not associated with prognosis. HPV-18–positive cases had a poorer prognosis than HPV-16–positive cases and non–HPV-related TSCC cases. A multivariate analysis revealed that HPV-18 positivity, old age, and an advanced T stage were independent prognostic factors for predicting poor outcomes for patients with TSCC.CONCLUSIONS The proportion of HPV-positive tonsillar cancer cases has increased during the last 20 years in the Republic of Korea. The presence of HPV-18 may serve as a biomarker for a poor prognosis. Cancer 2014. © 2014 American Cancer Society.
    Cancer 10/2014; 121(4). DOI:10.1002/cncr.29086 · 4.90 Impact Factor
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    Woo Shik Jeong, Jong Woo Choi, Seung Ho Choi
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    ABSTRACT: In the present study, a fibular osteotomy guide based on a computer simulation was applied to a patient who had undergone mandibular segmental ostectomy due to oncological complications. This patient was a 68-year-old woman who presented to our department with a biopsy-proven squamous cell carcinoma on her left gingival area. This lesion had destroyed the cortical bony structure, and the patient showed attenuation of her soft tissue along the inferior alveolar nerve, indicating perineural spread of the tumor. Prior to surgery, a three-dimensional computed tomography scan of the facial and fibular bones was performed. We then created a virtual computer simulation of the mandibular segmental defect through which we segmented the fibular to reconstruct the proper angulation in the original mandible. Approximately 2-cm segments were created on the basis of this simulation and applied to the virtually simulated mandibular segmental defect. Thus, we obtained a virtual model of the ideal mandibular reconstruction for this patient with a fibular free flap. We could then use this computer simulation for the subsequent surgery and minimize the bony gaps between the multiple fibular bony segments.
    09/2014; 41(5):584-587. DOI:10.5999/aps.2014.41.5.584
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    ABSTRACT: Background Aspiration cytologic findings of mammary analogue secretory carcinoma (MASC), a newly established salivary gland neoplasm defined by a t(12;15)(p13;q25) ETV6-NTRK3 translocation, are not fully characterized to date. We report cytologic descriptions of nine cases of molecularly confirmed MASC, including two with unusual findings.Methods Aspiration smears from nine MASCs of the salivary glands were retrospectively reviewed and analyzed according to the cellular and structural features of the corresponding surgical specimens.ResultsAspiration smears of MASC generally reflected the histologic diversity of the tumors. Among usual histologic findings, a micropapillary pattern was associated with a predominance of vacuolated individual cells on aspiration smears, a papillary-cystic pattern with a predominance of thin branching papillary structures, and a microcystic pattern with a predominance of irregular sheets of eosinophilic cells. There were two unusual cases, one with three-dimensional groups of high-grade atypical cells, and one with epithelial clusters floating in a notably mucinous background. These cases represented MASC with high-grade transformation and MASC with cystadenocarcinoma-like features, respectively. The secretory activity of MASC was not prominent in the aspiration specimens.Conclusions Although unusual cases were present, most MASC cases showed characteristic cytologic findings, which could aid the cytologic diagnosis of MASC. And knowledge of the histologic spectrum of MASC, including high-grade transformation, could be valuable for cytological differential diagnoses of salivary gland tumors, and the management of patients with MASC. Diagn. Cytopathol. 2014. © 2014 Wiley Periodicals, Inc.
    Diagnostic Cytopathology 08/2014; 43(4). DOI:10.1002/dc.23208 · 1.52 Impact Factor
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    ABSTRACT: Purpose Epidural analgesia has been the preferred analgesic technique after major abdominal surgery. On the other hand, the combined use of intrathecal morphine (ITM) and intravenous patient controlled analgesia (IVPCA) has been shown to be a viable alternative approach for analgesia. We hypothesized that ITM combined with IVPCA is as effective as patient controlled thoracic epidural analgesia (PCTEA) with respect to postoperative pain control after conventional open gastrectomy. Materials and Methods Sixty-four patients undergoing conventional open gastrectomy due to gastric cancer were randomly allocated into the intrathecal morphine combined with intravenous patient-controlled analgesia (IT) group or patient-controlled thoracic epidural analgesia (EP) group. The IT group received preoperative 0.3 mg of ITM, followed by postoperative IVPCA. The EP group preoperatively underwent epidural catheterization, followed by postoperative PCTEA. Visual analog scale (VAS) scores were assessed until 48 hrs after surgery. Adverse effects related to analgesia, profiles associated with recovery from surgery, and postoperative complications within 30 days after surgery were also evaluated. Results This study failed to demonstrate the non-inferiority of ITM-IVPCA (n=29) to PCTEA (n=30) with respect to VAS 24 hrs after surgery. Furthermore, the IT group consumed more fentanyl than the EP group did (1247.2±263.7 µg vs. 1048.9±71.7 µg, p<0.001). The IT group took a longer time to ambulate than the EP group (p=0.021) and had higher incidences of postoperative ileus (p=0.012) and pulmonary complications (p=0.05) compared with the EP group. Conclusion ITM-IVPCA is not as effective as PCTEA in patients undergoing gastrectomy, with respect to pain control, ambulation, postoperative ileus and pulmonary complications.
    Yonsei Medical Journal 07/2014; 55(4):1106-14. DOI:10.3349/ymj.2014.55.4.1106 · 1.26 Impact Factor
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    Seung Yong Moon, Seung Ho Choi
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    ABSTRACT: Two pennellids of the genus Peniculus von Nordmann, 1832 (Copepoda: Siphonostomatoida: Pennellidae), including a new species, are described based on adult post-metamorphosis female specimens collected from commercially important fishes off Chuja Island, Korea. Peniculus quadratus n. sp. was collected from the surface of the mouth palate of the surfperch Neoditrema ransonnetii Steindachner (Perciformes: Embiotocidae). The new species can be differentiated from its congeners by a combination of the following features: the shape of the cephalothorax is relatively quadrangular, the fourth pedigerous somite is incorporated into the anterior end of trunk, and the trunk is bottle-shaped, narrowing slightly towards anterior extremity. Peniculus fistula von Nordmann, 1832 was collected from the dorsal fin and body surface of the pearl-spot chromis Chromis notata (Temminck & Schlegel) (Perciformes: Embiotocidae). A close comparison of the specimens of P. fistula collected from Korea with the original description revealed some differences in the shape of the cephalothorax and the length/width ratio of the trunk. These discrepancies are considered to represent intraspecific variation or observational errors. The finding of P. fistula represents not only a new record from the Northwest Pacific but also from a new host.
    Systematic Parasitology 06/2014; 88(2):185-93. DOI:10.1007/s11230-014-9493-4 · 1.04 Impact Factor
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    Kwang Myung Jeon, Seung Ho Choi
    05/2014; 9(5):107-120. DOI:10.14257/ijmue.2014.9.5.10
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    ABSTRACT: Objectives: This study evaluated the efficacy of commonly used treatment modalities and determined predictors of treatment outcome for contact granuloma Study Design: Retrospective study Methods: Twenty otolaryngologists from 18 university hospitals reviewed the medical records of their own contact granuloma patients for the most recent 4 years. To be enrolled as a valid case, each treatment had to continue for at least 3 months. After excluding intubation granuloma, 590 cases of contact granuloma were analyzed. Treatment outcomes were assessed as complete response (CR), marked response (MR), partial response (PR) and no response. The chi-square test was used to compare the efficacy of each treatment modality and logistic regression to determine the predictors of treatment outcome Results: The long-term outcomes of good response (GR) (sum of CR and MR) rates after each treatment were 20.5% for observation, 31.6% for steroid inhaler, 44.0% for PPI, 44.3% for voice therapy, 60.0% for surgical removal, and 74.2% for botulinum toxin injection. Voice therapy, PPI, and botulinum toxin had more good responses than simple observation for the long term outcome (P < 0.05). Surgical removal had a significantly higher recurrence rate (37.1%) than simple observation (10.3%) (P < 0.05) Conclusions: Voice therapy or PPI are recommended as first-line treatments. Surgical removal should be reserved for selected patients because of the high chance of recurrence. Botulinum toxin injection can be used not only for primary cases but also for refractory cases with an expected high response rate.
    The Laryngoscope 05/2014; 124(5). DOI:10.1002/lary.24470 · 2.03 Impact Factor
  • Ji Hun Park, Seung Ho Choi
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    ABSTRACT: In this paper, an interaural time difference (ITD) estimation method is proposed for binaural speech separation in reverberant environments. First, the auditory signals are represented in the time-frequency (T-F) domain, and the ITD for each T-F bin is then estimated using generalized cross-correlation (GCC) with a maximum likelihood (ML) weighting function. In particular, the ML weighting function is designed to reduce the reverberation effect. Then, a mask is estimated by comparing the estimated ITD with the ITD corresponding to the location of the pre-defined target speech source. Finally, the target speech is separated by applying the mask to the auditory signals. It is shown that the proposed ITD estimation method outperforms a conventional cross-correlation-based ITD estimation method under reverberant conditions in terms of the signal-to-noise ratio (SNR) and signal-to-distortion ratio (SDR) of the separated speech signals.
    04/2014; 9(4):43-50. DOI:10.14257/ijmue.2014.9.4.05

Publication Stats

1k Citations
243.24 Total Impact Points

Institutions

  • 2015
    • Korea University
      • Department of Materials Science and Engineering
      Sŏul, Seoul, South Korea
  • 2014–2015
    • University of Ulsan
      Urusan, Ulsan, South Korea
    • Gwangju OK Hospital
      Gwangju, Gwangju, South Korea
    • Asan Medical Center
      Sŏul, Seoul, South Korea
    • Yonsei University
      Sŏul, Seoul, South Korea
  • 2013–2014
    • Ulsan University Hospital
      Urusan, Ulsan, South Korea
    • Konkuk University
      • Department of Chemical Engineering
      Sŏul, Seoul, South Korea
  • 2009–2013
    • Seoul National University
      • Department of Internal Medicine
      Sŏul, Seoul, South Korea
  • 2003–2013
    • Seoul National University of Technology
      • • Department of Electronic IT Media Engineering
      • • Department of Electric Information System Engineering
      Sŏul, Seoul, South Korea
  • 2011
    • Sungkyunkwan University
      • Department of Surgery
      Sŏul, Seoul, South Korea
    • Catholic University of Korea
      Sŏul, Seoul, South Korea
  • 2010–2011
    • Purdue University
      • Weldon School of Biomedical Engineering
      ウェストラファイエット, Indiana, United States
  • 2007–2010
    • Seoul National University Hospital
      • • Department of Neurology
      • • Department of Internal Medicine
      Sŏul, Seoul, South Korea
    • University of Canterbury
      • Department of Electrical and Computer Engineering
      Christchurch, Canterbury, New Zealand
    • Seoul National University Bundang Hospital
      Sŏul, Seoul, South Korea
    • Gwangju Institute of Science and Technology
      Gwangju, Gwangju, South Korea
  • 2002–2010
    • Dongshin University
      South Korea
  • 2008
    • Yonsei University Hospital
      • Department of Internal Medicine
      Sŏul, Seoul, South Korea
  • 1998–2008
    • Korea Advanced Institute of Science and Technology
      • • Department of Biological Sciences
      • • Department of Electrical Engineering
      Sŏul, Seoul, South Korea
  • 2000
    • AT&T Labs
      Austin, Texas, United States
  • 1999–2000
    • Samsung Advanced Institute of Technology
      Usan-ri, Gyeonggi Province, South Korea
    • SK Telecom
      Sŏul, Seoul, South Korea