Joo Young Jang

University of Ulsan, Ulsan, Ulsan, South Korea

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Publications (15)25.82 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Crohn's disease (CD) is an intractable inflammatory bowel disease (IBD) of unknown cause. Recent meta-analysis of the genome-wide association studies (GWAS) and Immunochip data identified 163 susceptibility loci to IBD in Caucasians, however there are limited studies in other populations. We performed a GWAS and two validation studies in the Korean population comprising a total of 2311 patients with CD and 2442 controls. We confirmed four previously reported loci: TNFSF15, IL23R, the major histocompatibility complex region, and the RNASET2-FGFR1OP-CCR6 region. We identified three new susceptibility loci at genome-wide significance: rs6856616 at 4p14 (OR=1.43, combined p=3.60×10(-14)), rs11195128 at 10q25 (OR=1.42, combined p=1.55×10(-10)) and rs11235667 at 11q13 (OR=1.46, combined p=7.15×10(-9)), implicating ATG16L2 and/or FCHSD2 as novel susceptibility genes for CD. Further analysis of the 11q13 locus revealed a non-synonymous single nucleotide polymorphism (SNP) (R220W/rs11235604) in the evolutionarily conserved region of ATG16L2 with stronger association (OR=1.61, combined p=2.44×10(-12)) than rs11235667, suggesting ATG16L2 as a novel susceptibility gene for CD and rs11235604 to be a potential causal variant of the association. Two of the three SNPs (rs6856616 (p=0.00024) and rs11195128 (p=5.32×10(-5))) showed consistent patterns of association in the International IBD Genetics Consortium dataset. Together, the novel and replicated loci accounted for 5.31% of the total genetic variance for CD risk in Koreans. Our study provides new biological insight to CD and supports the complementary value of genetic studies in different populations.
    Gut 07/2013; · 10.73 Impact Factor
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    ABSTRACT: This paper presents a dual-band CMOS power amplifier (PA) using class-E topology for Wideband Code Division Multiple Access (WCDMA) at 1.9 GHz and Worldwide Interoperability for Microwave Access (WiMAX) at 2.6 GHz applications. The fully integrated PA consists of an input balun, a driver stage, a power stage, and two output transformers. To operate the dual-band PA, common-gate amplifiers having on-off apparatuses in power stage and matched transformers for 1.9/2.6 GHz are employed. The PA is designed and fabricated in a 0.18-μm CMOS technology and has a chip size of 1.5 × 1.85 mm2 including all pads. When driven by continuous wave (CW) signals, the output power and the efficiency reach 28.1/27.4 dBm and 37.8/31.6% at 1.9 GHz and 2.6 GHz, respectively. The average output powers of the hybrid-EER based TX system 21 dBm for 3.84 MHz WCDMA and 12 dBm for 5 MHz WiMAX, while also meeting stringent linearity specifications without using any linearization methods.
    VLSI Design and 2013 12th International Conference on Embedded Systems (VLSID), 2013 26th International Conference on; 01/2013
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    ABSTRACT: This letter presents a fully integrated triple-band CMOS class-E power amplifier (PA) for the 0.8/1.9/2.4 GHz frequencies. The operating frequency band is tuned by a power cell resizing technique and by changing the supply bias position with a multi-tap transformer for the required capacitance and inductance values for optimum class-E operation. The PA achieves output powers of 28/29.6/26.5 dBm and power-added efficiency of 40/45/37% at each frequency band. The PA is implemented in a 0.18 μm CMOS process without multiple transformers or input/output matching networks. The total chip size is 1.5 × 1.5 mm2.
    IEEE Microwave and Wireless Components Letters 01/2013; 23(12):659-661. · 1.78 Impact Factor
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    ABSTRACT: This paper presents a new type of the hybrid envelope amplifier (HEA) using a switching-controlled structure for reconfigurable transmitters. The dual switching stage, controlled by an appropriate voltage with respects to the selected mode, is employed to obtain high efficiency. For verification, the proposed HEA has been fabricated using 0.35-µm CMOS technology within an area of 2.3 × 1.1 mm2 including all of the pads. The maximum efficiency of 85%, 84% and 79%, which are approximately 9%, 6% and 5% higher than those of the conventional HEA, are achieved for EDGE, WCDMA, and LTE modes, respectively.
    Microwave Symposium Digest (MTT), 2012 IEEE MTT-S International; 01/2012
  • Renal Failure 01/2011; 33(6):639-40. · 0.94 Impact Factor
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    ABSTRACT: There have only been a few studies on the long-term outcomes and prognostic factors after pediatric LDLT. We conducted a retrospective, single-center assessment of the outcomes as well as the demographic and clinical factors that influenced the poor outcomes in 113 children aged <16 (median age 21 months; 6 months-15.5 yr) who underwent 115 LDLTs, predominantly for biliary atresia (60.9%) and FHF (14.8%), between 1994 and 2006 at Asan Medical Center. Left lateral segment or left lobe grafts were implanted into most of these children (86.9%) according to routine procedures. The overall rates of graft survival at one, five, and 10 yr were 89.6%, 83.0%, and 81.5%, respectively, and the overall rates of patient survival were 92.9%, 86.3%, and 84.8%, respectively. Virus-related disease (41.2%) and chronic rejection (29.4%) were the major causes of mortality. On multivariate analysis, UNOS status 1a and 1b and chronic rejection were significant risk factors for both graft and patient loss, whereas the PELD score >25 was a significant risk factor for graft loss. Patient and graft survival may be related not only to post-operative complications, but also to the patient's preoperative clinical condition.
    Pediatric Transplantation 11/2010; 14(7):870-8. · 1.50 Impact Factor
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    ABSTRACT: This paper describes a receiver composed of a wideband LNA, mixers, and a frequency generator toward multifunction and multistandard mobile terminals. The proposed frequency generator can cover the frequency range from 750 MHz to 6.75 GHz by following the frequency planning which consists of a VCO, two mixers, and four divide-by-2 dividers. Firstly, to achieve better phase noise, a low-phase noise wideband LC VCO is proposed. The power consumption of the VCO is 7.8 mW and its phase noise is -126 dBc/Hz at 1 MHz offset frequency. The LO generator is controlled for the targeted frequency range by turning on and off the mixer and divider input and output buffers. The total power consumption of the LO generator is 27.3~60.6 mW under 1.8 V supply. The phase noise at 1 MHz offset for each frequency band varies from -122 dBc/Hz to -136 dBc/Hz. A 2-stage wideband low noise amplifier has bandwidth of 6.6 GHz (0.2-6.8 GHz), power gain of 13.3 dB including 6 dB loss from buffers, and minimum noise figure of 3.7 dB.
    RF Front-ends for Software Defined and Cognitive Radio Solutions (IMWS), 2010 IEEE International Microwave Workshop Series on; 03/2010
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    Hee Jin Jang, Joo Young Jang, Kyung Mo Kim
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    ABSTRACT: Appendiceal orifice inflammation (AOI) may occur as a skipped lesion in ulcerative colitis (UC). Cases of ulcerative colitis complicated by Wilson's disease have also been reported. We report herein a case of AOI that occurred as a missed lesion in an 8-year-old girl with UC complicating Wilson's disease, which is rare in children.
    Gut and liver 03/2010; 4(1):126-8. · 1.31 Impact Factor
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    Joo Young Jang, Chong Hyun Yoon, Kyung Mo Kim
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    ABSTRACT: To assess the indications, findings, therapeutic procedures, safety, and complications of endoscopic retrograde cholangiopancreatography (ERCP) performed in Korean children. The demographic characteristics, indications for ERCP, findings, therapeutic procedures, and complications of 122 pediatric patients who underwent 245 ERCPs in the Asan Medical Center between June 1994 and March 2008 were investigated. The mean age of the 122 patients was 8.0 +/- 4.2 years. Indications were biliary pathology in 78 (64.0%), pancreatic pathology in 43 (35.2%), and chronic abdominal pain in one. Biliary indications included choledochal cysts in 40, choledocholithiasis in 24, suspected sclerosing cholangitis in 8, trauma in 2, and other conditions in 4. Pancreatic indications included acute pancreatitis in 7, acute recurrent pancreatitis in 11, chronic pancreatitis in 20, trauma in 3, and pancreatic mass in 2. Of the 245 ERCPs, success rate was 98.4% and 190 (77.6%) were for therapeutic purposes, including endoscopic nasal drainage (51.8%), biliary sphincterotomy (38.0%), pancreatic sphincterotomy (23.3%), stent insertion (15.1%), stone extraction (18.8%), and balloon dilatation (11.0%). Complications were post-ERCP pancreatitis in 16 (6.5%), ileus in 23 (9.4%), hemorrhage in 2 (0.8%), perforation in 2 (0.8%), sepsis in 1 (0.4%), and impacted basket in 1 (0.4%). There were no procedure-related deaths, and most complications improved under supportive care. This study showed that there is a high incidence of choledochal cyst and diagnostic and therapeutic ERCP for the management of various biliary and pancreatic diseases was safe and effective in Korean children.
    World Journal of Gastroenterology 01/2010; 16(4):490-5. · 2.55 Impact Factor
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    ABSTRACT: BackgroundInflammatory bowel disease (IBD) is rare in Asian children and few reports on pediatric IBD have appeared. AimsWe, therefore, investigated the incidence trends and clinical characteristics of pediatric IBD in Korea. MethodsWe enrolled 48 children with Crohn’s disease (CD) and 14 children with ulcerative colitis (UC) from 1996 to 2007. Trends in annual enrollment and clinical characteristics were retrospectively evaluated by medical record review. ResultsDuring the 12years of observation, the number of new enrollments gradually increased. CD showed male predominance (33 boys, 15 girls), but more females presented with UC (4 boys, 10 girls). A relevant family history was observed in 3 (4.9%) of the 61 unrelated families. The most common presenting symptom was abdominal pain (67%) in CD and hematochezia (93%) in UC. Growth delay was observed in 10% of CD patients, but not in any of the UC patients. In CD, colonic involvement occurred in 87% of patients, ileal involvement in 87%, and both the small bowel and colon were affected in 75%. With UC, pancolitis occurred in 43% of patients, left-sided colitis in 36%, and proctitis in 21%, including all three patients with appendiceal orifice inflammation. The most frequent disease behavior was inflammatory in 85% of patients, but perianal fistula was noted in 50% of CD patients. ConclusionThis study showed that the incidence of pediatric IBD has been rapidly increasing in Korea in recent years. Relevant family history is less prevalent and phenotypic expression differs from what is seen in Western countries. KeywordsInflammatory bowel disease-Crohn’s disease-Ulcerative colitis-Child-Adolescent
    Digestive Diseases and Sciences 01/2010; 55(7):1989-1995. · 2.26 Impact Factor
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    ABSTRACT: ARC (arthrogryposis, renal dysfunction, and cholestasis) syndrome is a rare, fatal cause of neonatal intrahepatic cholestasis without known treatment modalities and has recently been ascribed to a mutation in the VPS33B gene. We assessed the clinical characteristics and investigated the VPS33B mutations in Korean patients with ARC syndrome. We reviewed the medical records of 6 patients with ARC syndrome among 90 patients with neonatal cholestasis from 2000 to 2005 and assessed the relative incidence rate ratio, clinical symptoms, laboratory findings, and pathological findings. DNA samples from 5 patients, 4 parents, and 2 fetuses were analyzed for VPS33B mutations. The relative incidence rate ratio was 1/7 that of biliary atresia (95% CI 0.33-0.06). All 6 patients presented with ichthyosis and recurrent infection, and failed to thrive with the 3 main symptoms. All of the patients died within the age of 12 months. They had various severities of cholestasis, metabolic acidosis, nephrogenic diabetes insipidus, chronic diarrhea, platelet abnormalities, and central nervous system anomalies. We identified 1 novel c.403+2T>A splice-site mutation, 2 frame-shift mutations (c.1509_1510insG, c.790_791del), 1 nonsense mutation (c.661C>A), and 1 known nonsense mutation (c.1518C>T) in the VPS33B gene. Prenatal diagnosis was performed in 2 different families. This study indicates that the incidence of ARC syndrome is not as rare as has been thought. We found 4 novel and 1 known mutations in ARC syndrome patients and performed prenatal diagnosis in 2 families, which will facilitate genetic diagnosis and counseling for affected families.
    Journal of pediatric gastroenterology and nutrition 03/2009; 48(3):348-54. · 2.18 Impact Factor
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    ABSTRACT: Glycogen storage disease type IV (GSD-IV) is an autosomal recessive disease caused by a deficient glycogen branching enzyme (GBE), encoded by the GBE1 gene, resulting in the accumulation of abnormal glycogen deposits in the liver and other tissues. We treated a 20-month-old girl who presented with progressive liver cirrhosis and was diagnosed with GSD-IV, as confirmed by GBE1 gene mutation analysis, and underwent living related heterozygous donor liver transplantation. Direct sequencing of the GBE1 gene revealed that the patient was compound heterozygous for a known c.1571G>A (p.Gly264Glu) mutation a novel c.791G>A (Arg524Gln) mutation. This is the first report of a Korean patient with GSD-IV confirmed by mutation analysis, who was treated successfully by liver transplantation.
    Gut and liver 03/2009; 3(1):60-3. · 1.31 Impact Factor
  • Korean Journal of Pathology - KOREAN J PATHOL. 01/2009; 43(1).
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    ABSTRACT: pH monitoring of the esophagus has been considered as the gold standard for the measurement of acid reflux. However, it has several limitations related to its inability to detect nonacid reflux. We conducted this study to characterize the proportion of acid and non-acid reflux events in children using pH-multichannel intraluminal impedance (MII) monitoring and to determine the correlation of the symptom index with non-acid and acid reflux events. Seventy-five children, aged from 9 days to 12 years, underwent 24 hour pH-MII monitoring at Asan Medical Center from March 2006 to June 2007. We investigated the underlying disease and main problems related to gastroesophageal reflux (GER) of the patients, the number of acid and nonacid reflux, symptom index, symptom sensitivity index in pH monitoring only and pH-MII monitoring. While 2,247 reflux events were detected by MII, and only 967 reflux events were detected by pH probe alone. The percentage of acid reflux was 43% (967) and that of non-acid was 57% (1,280). The non-acid reflux increased at postprandial time (p<0.001). The symptom index increased when measured by pH-MII (31.1%) compared with those by pH probe alone (8.2%) (p=0.003). This study suggests that significant number of GER include non-acid reflux which cannot be detected by pH probe alone, therefore combining pH with MII monitoring is a valuable diagnostic tool for diagnosing GER in children.
    The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi 07/2008; 52(1):9-15.
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    ABSTRACT: Triple therapy with bismuth subsalicylate, amoxicillin, metronidazole (BAM) or with omeprazole, amoxicillin, clarithromycin (OAC) has been commonly used for the eradication of Helicobacter pylori infection. We compared the efficacy of these triple therapies in children with H. pylori infection. We retrospectively analyzed results in 233 children with H. pylori infection and treated with OAC (n=141) or BAM (n=92). Overall eradication rates of triple therapy with OAC and BAM were 74% and 85%, respectively, which showed no statistical difference. Our study showed that the triple therapy with BAM was more effective for the first-line eradication of H. pylori infection in Korean children, but has no statistical difference with OAC regimen.
    Journal of Korean Medical Science 01/2007; 21(6):1037-40. · 1.25 Impact Factor

Publication Stats

54 Citations
25.82 Total Impact Points


  • 2010
    • University of Ulsan
      • Department of Pediatrics
      Ulsan, Ulsan, South Korea
    • Korea Advanced Institute of Science and Technology
      • Department of Electrical Engineering
      Seoul, Seoul, South Korea
  • 2007–2010
    • Ulsan University Hospital
      Urusan, Ulsan, South Korea