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Search Results: 1 - 10 of 4773 matches for " Sung-Il Baik "
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Deformation behavior of duplex austenite and ε-martensite high-Mn steel
Ki Hyuk Kwon, Byeong-Chan Suh, Sung-Il Baik, Young-Woon Kim, Jong-Kyo Choi and Nack J Kim
Science and Technology of Advanced Materials , 2013,
Abstract: Deformation and work hardening behavior of Fe–17Mn–0.02C steel containing ε-martensite within the austenite matrix have been investigated by means of in situ microstructural observations and x-ray diffraction analysis. During deformation, the steel shows the deformation-induced transformation of austenite → ε-martensite → α'-martensite as well as the direct transformation of austenite → α'-martensite. Based on the calculation of changes in the fraction of each constituent phase, we found that the phase transformation of austenite → ε-martensite is more effective in work hardening than that of ε-martensite → α'-martensite. Moreover, reverse transformation of ε-martensite → austenite has also been observed during deformation. It originates from the formation of stacking faults within the deformed ε-martensite, resulting in the formation of 6H-long periodic ordered structure.
RPS3a Over-Expressed in HBV-Associated Hepatocellular Carcinoma Enhances the HBx-Induced NF-κB Signaling via Its Novel Chaperoning Function
Keo-Heun Lim, Kyun-Hwan Kim, Seong Il Choi, Eun-Sook Park, Seung Hwa Park, Kisun Ryu, Yong Kwang Park, So Young Kwon, Sung-Il Yang, Han Chu Lee, In-Kyung Sung, Baik L. Seong
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0022258
Abstract: Hepatitis B virus (HBV) infection is one of the major causes of hepatocellular carcinoma (HCC) development. Hepatitis B virus X protein (HBx) is known to play a key role in the development of hepatocellular carcinoma (HCC). Several cellular proteins have been reported to be over-expressed in HBV-associated HCC tissues, but their role in the HBV-mediated oncogenesis remains largely unknown. Here, we explored the effect of the over-expressed cellular protein, a ribosomal protein S3a (RPS3a), on the HBx-induced NF-κB signaling as a critical step for HCC development. The enhancement of HBx-induced NF-κB signaling by RPS3a was investigated by its ability to translocate NF-κB (p65) into the nucleus and the knock-down analysis of RPS3a. Notably, further study revealed that the enhancement of NF-κB by RPS3a is mediated by its novel chaperoning activity toward physiological HBx. The over-expression of RPS3a significantly increased the solubility of highly aggregation-prone HBx. This chaperoning function of RPS3a for HBx is closely correlated with the enhanced NF-κB activity by RPS3a. In addition, the mutational study of RPS3a showed that its N-terminal domain (1–50 amino acids) is important for the chaperoning function and interaction with HBx. The results suggest that RPS3a, via extra-ribosomal chaperoning function for HBx, contributes to virally induced oncogenesis by enhancing HBx-induced NF-κB signaling pathway.
Epidemiological Characteristics of Novel Influenza A (H1N1) in Antiviral Drug Users in Korea
Kyunghi Choi, Sung-il Cho, Masahiro Hashizume, Ho Kim
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0047634
Abstract: Soon after the first novel influenza A (H1N1) death was documented in Korea on August 15, 2009, prompt treatment with antiviral drugs was recommended when an infection was suspected. Free antiviral drugs were distributed to patients who met the case definition in the treatment guidelines, and patients prescribed the antiviral drugs were included in the Antiviral Drug Surveillance System (ADSS). A total of 2,825,821 patients were reported to the ADSS from September 1 to December 31, 2009. Odds ratios were calculated to compare the risks of severe diseases, as indicated by general hospital admissions or intensive care unit (ICU) admissions according to demographic characteristics, underlying medical conditions, and behavioral factors. Approximately 6% of the total population received antiviral drugs during the study period. Of these, 2,709,611 (95.9%) were outpatients, 114,840 (4.06%) were hospitalized, and 1,370 (0.05%) were admitted to the ICU. Children aged 0–9 yr accounted for 33.94% of all reported cases, whereas only 3.89% of the patients were ≥ 60 yr. The estimated incidence of novel influenza A (H1N1) during the pandemic was 5.68/100 of all reported cases. Mortality due to influenza A (H1N1) during the pandemic was 0.33/100,000, with the highest mortality of 1.31/100,000 for patients aged ≥ 60 years. Severe pandemic H1N1 influenza was associated with the presence of one or more underlying medical conditions in elderly aged ≥ 60 years and with lower economic status. Moreover, influenza A (H1N1) appeared to be age-specific in terms of mortality. Although the incidence and admission rates of influenza A (H1N1) were higher in younger age groups, fatal cases were much more likely to occur in the elderly (≥60 years). In contrast to earlier influenza A (H1N1) reports, the risks of a severe outcome were elevated among those who were underweight (body mass index < 18.5 kg/m2).
A closer look at the increase in suicide rates in South Korea from 1986–2005
Jin-Won Kwon, Heeran Chun, Sung-il Cho
BMC Public Health , 2009, DOI: 10.1186/1471-2458-9-72
Abstract: We used data on total mortality and suicide rates from 1986 to 2005 published online by the Korean National Statistical Office (NSO) and extracted data for individuals under 80 years old. The analyses of the trends for 1) the sex-age-specific total mortality rate, 2) the sex-age-specific suicide rate, and 3) the sex-age-specific proportional suicide rate in 1986–2005 were conducted. To demonstrate the birth cohort effect on the proportional suicide rate, the synthetic birth cohort from 1924 to 1978 from the successive cross-sectional data was constructed.Age standardized suicide rates in South Korea increased by 98% in men (from 15.3 to 30.3 per 100,000) and by 124% in women (from 5.8 to 13.0 per 100,000). In both genders, the proportional increase in suicide rates was more prominent among the younger group aged under 45, despite the absolute increase being attributed to the older group. There were distinct cohort effects underlying increasing suicide rates particularly among younger age groups.Increasing suicide rates in Korea was composed of a greater absolute increase in the older group and a greater proportional increase in the younger group.Suicide is a dramatic example of individual behaviour influenced by social integration or regulation, as originally noted by Durkheim [1]. Therefore, not only individual factors but also socioeconomic changes should be considered to explain suicide patterns in a society. According to World Health Organisation (WHO) statistics from 1965 to 1999, suicide rates had a variation and showed mixed trends between countries and age-groups. While total suicide mortality rates in all ages have been decreasing or in a steady status in most developed countries after 1990s, it has been increasing in some countries especially which have suffered huge economic turmoil such as Russia. There are some reports on suicide rates by age group. In a few countries including New Zealand and Australia, there were rising trends in young people [2,3]. I
Cellular stress-induced up-regulation of FMRP promotes cell survival by modulating PI3K-Akt phosphorylation cascades
Se Jeon, Jung Seo, Sung-Il Yang, Ji Choi, David Wells, Chan Shin, Kwang Ko
Journal of Biomedical Science , 2011, DOI: 10.1186/1423-0127-18-17
Abstract: Apoptotic cell death was induced by etoposide treatment on Hela cells. After we transiently modulated FMRP expression (silencing or enhancing) by using molecular biotechnological methods such as small hairpin RNA virus-induced knock down and overexpression using transfection with FMRP expression vectors, cellular viability was measured using propidium iodide staining, TUNEL staining, and FACS analysis along with the level of activation of PI3K-Akt pathway by Western blot. Expression level of FMRP and apoptotic regulator BcL-xL was analyzed by Western blot, RT-PCR and immunocytochemistry.An increased FMRP expression was measured in etoposide-treated HeLa cells, which was induced by PI3K-Akt activation. Without FMRP expression, cellular defence mechanism via PI3K-Akt-Bcl-xL was weakened and resulted in an augmented cell death by etoposide. In addition, FMRP over-expression lead to the activation of PI3K-Akt signalling pathway as well as increased FMRP and BcL-xL expression, which culminates with the increased cell survival in etoposide-treated HeLa cells.Taken together, these results suggest that FMRP expression is an essential part of cellular survival mechanisms through the modulation of PI3K, Akt, and Bcl-xL signal pathways.Fragile X syndrome (FXS) is a well known neurodevelopmental disorder caused by loss of fragile X linked mental retardation protein (FMRP) which is encoded by Fmr1 gene [1]. FXS patients typically show a wide spectrum of cognitive and behavioral problems such as attention deficit, anxiety and mood disorder, increased risk of seizures, autistic spectrum behaviors, and mental retardation [1]. FMRP is expressed in many tissues including testis, placenta, and brain [2,3] and in a variety of cell types including HeLa [4].FMRP is a RNA binding protein, which regulates translation of target mRNAs. A wide range of potential target mRNAs have been suggested, most of which have been correlated to the regulation of synaptic function as well as neuronal deve
Laparoscopic resection of an adrenal pseudocyst mimicking a retroperitoneal mucinous cystic neoplasm
Bum-Soo Kim, Sun-Hyung Joo, Sung-Il Choi, Jeong-Yoon Song
World Journal of Gastroenterology , 2009,
Abstract: Adrenal pseudocysts are rare cystic masses that arise within the adrenal gland and are usually non-functional and asymptomatic. Adrenal pseudocysts consist of a fibrous wall without a cellular lining. We report a patient with a 9 cm, left-sided suprarenal cystic mass who presented with abdominal discomfort of 2 years’ duration. A 38-year-old woman was referred to our service for evaluation of abdominal discomfort and gastrointestinal symptoms. Routine laboratory tests were within normal limits. An abdominal computed tomography scan showed a 9 cm × 8 cm × 8 cm well-defined cystic lesion displacing the left kidney. Magnetic resonance imaging showed a cystic lesion with low signal intensity on the T1-weighted image and high signal intensity on the T2-weighted image. A laparoscopic left adrenalectomy was performed to diagnose the lesion. The final pathology showed an adrenal pseudocyst without a cellular lining. The patient had no postoperative complications and she was discharged four days after surgery.
Social class, job insecurity and job strain in Korea
Sung-Il Cho,Ki-Do Eum,BongKyoo Choi,Domyung Paek
SJWEH Supplements , 2008,
Abstract: OBJECTIVES: This study explored the associations between social class, job insecurity, and job strain among Korean workers. METHODS: Data on 6143 participants (253 health care workers, 5113 subway workers, and 777 petrochemical refinery workers) from three Korean job-stress studies were used. Job strain and job insecurity were measured with the job content questionnaire. Job strain was defined as a continuous variable according to the demand-to-control ratio and as a binary variable as the highest quartile of this ratio. Social class was defined by indicators of socioeconomic status. The combined effects of job insecurity and socioeconomic status were examined with generalized linear models and logistic regression models. RESULTS: Job insecurity was relatively higher than in other countries (scale mean 5.8). Higher job insecurity was associated with lower social class, and it appeared to partially mediate the effect of socioeconomic status on job strain. Job insecurity and low social class independently elevated job strain. Job strain was the highest among those with a low social class and job insecurity for each socioeconomic indicator. According to the logistic regression models, the odds ratio for high strain was 2.0 (P<0.05) for low job security and low education, 2.4 (P<0.05) for low job security and low income, and 2.4 (P<0.05) for low job security and low occupational class, when compared with the baseline values. CONCLUSIONS: Low social class is associated with higher job strain. Job insecurity is higher among persons in a lower social class, the highest job strain occurring among workers with both factors. Job insecurity appears to intensify the overall effect of social class on job strain.
SNS Superconducting Cavity Modeling -Iterative Learning Control
Sung-il Kwon,Yi-Ming Wang,Amy Regan,Tony Rohlev,Mark Prokop,Dave Thomson
Physics , 2000,
Abstract: The SNS SRF system is operated with a pulsed beam. For the SRF system to track the repetitive reference trajectory, a feedback and a feedforward controllers has been proposed. The feedback controller is to guarantee the closed loop system stability and the feedforward controller is to improve the tracking performance for the repetitive reference trajectory and to suppress the repetitive disturbance. As the iteration number increases, the error decreases.
Akt regulates the expression of MafK, synaptotagmin I, and syntenin-1, which play roles in neuronal function
Young-Tae Ro, Bo-Kwang Jang, Chan Shin, Eui U Park, Chul Kim, Sung-Il Yang
Journal of Biomedical Science , 2010, DOI: 10.1186/1423-0127-17-18
Abstract: We performed suppression subtractive hybridization on two previously established PC12 sublines, one of which overexpresses the wild-type (WT) form and the other, the dominant-negative (DN) form of Akt. These sublines respond differently to NGF's neuronal differentiation effect.A variety of genes was identified and could be classified into several functional groups, one of which was developmental processes. Two genes involved in neuronal differentiation and function were found in this group. v-Maf musculoaponeurotic fibrosarcoma oncogene homolog K (MafK) induces the neuronal differentiation of PC12 cells and immature telencephalon neurons, and synaptotagmin I (SytI) is essential for neurotransmitter release. Another gene, syntenin-1 (Syn-1) was also recognized in the same functional group into which MafK and SytI were classified. Syn-1 has been reported to promote the formation of membrane varicosities in neurons. Quantitative reverse transcription polymerase chain reaction analyses show that the transcript levels of these three genes were lower in PC12 (WT-Akt) cells than in parental PC12 and PC12 (DN-Akt) cells. Furthermore, treatment of PC12 (WT-Akt) cells with an Akt inhibitor resulted in the increase of the expression of these genes and the improvement of neurite outgrowth. These results indicate that dominant-negative or pharmacological inhibition of Akt increases the expression of MafK, SytI, and Syn-1 genes. Using lentiviral shRNA to knock down endogenous Syn-1 expression, we demonstrated that Syn-1 promotes an increase in the numbers of neurites and branches.Taken together, these results indicate that Akt negatively regulates the expression of MafK, SytI, and Syn-1 genes that all participate in regulating neuronal integrity in some way or another.Akt (also termed "protein kinase B') mediates a variety of biological responses to insulin, cytokines, and numerous growth factors. As such, Akt has been well recognized as an important regulator for multiple biolog
Design of the SNS Normal Conducting Linac RF Control System
Amy Regan,Sung-il Kwon,Tony S. Rohlev,Yi-Ming Wang,Mark S. Prokop,David W. Thomson
Physics , 2000,
Abstract: The Spallation Neutron Source (SNS) is being designed for operation in 2004. The SNS is a 1 GeV machine consisting of a combination normal-conducting and super-conducting linac as well as a ring and target area. The linac front end is a 402.5 MHz RFQ being developed by Lawrence Berkeley Lab. The DTL (at 402.5 MHz) and the CCL (at 805 MHz) stages are being developed by Los Alamos National Laboratory. The expected output energy of the DTL is 87 MeV and that of the CCL is 185 MeV. The RF control system under development for the linac is based on the Low Energy Demonstration Accelerator (LEDA) control system with some new features. This paper will discuss the new design approach and its benefits. Block diagrams and circuit specifics will be addressed. The normal conducting RF control system will be described in detail with references to the super-conducting control system where appropriate.
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