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Design and Application for PV Generation System Using a Soft-Switching Boost Converter With SARC
Sang-Hoon Park,Gil-Ro Cha,Yong-Chae Jung,Chung-Yuen Won IEEE 2010 IEEE transactions on industrial electronics Vol.57 No.2
<P>In order to improve the efficiency of energy conversion for a photovoltaic (PV) system, a soft-switching boost converter using a simple auxiliary resonant circuit, which is composed of an auxiliary switch, a diode, a resonant inductor, and a resonant capacitor, is adopted in this paper. The conventional boost converter decreases the efficiency because of hard switching, which generates losses when the switches are turned on/off. During this interval, all switches in the adopted circuit perform zero-current switching by the resonant inductor at turn-on, and zero-voltage switching by the resonant capacitor at turn-off. This switching pattern can reduce the switching losses, voltage and current stress of the switching device. Moreover, it is very easy to control. In this paper, we have analyzed the operational principles of the adopted soft-switching boost converter, and it is designed for PV generation system. Simulation and experimental results are presented to confirm the theoretical analysis.</P>
( Sang Hyoung Park ),( Seung Kyu Jeong ),( Ji Hyun Lee ),( Kyoung Hoon Rhee ),( Young-Ho Kim ),( Sung Noh Hong ),( Kyung Ho Kim ),( Seung In Seo ),( Jae Myung Cha ),( Sun Yong Park ),( Hyunju Park ),( 대한소화기기능성질환·운동학회 2021 Gut and Liver Vol.15 No.5
Background/Aims: We aimed to evaluate the clinical characteristics and long-term prognosis of elderly-onset ulcerative colitis (EOUC) in Korean patients over a 30-year period using a wellestablished population-based cohort in the Songpa-Kangdong district of Seoul, Korea. Methods: Clinical characteristics and prognosis were compared between two groups: EOUC, defined as UC diagnosed in individuals aged ≥60 years and non-EOUC (N-EOUC), defined as UC diagnosed in individuals aged 18 to 59 years. Results: We identified 99 patients with EOUC (10.3%) and 866 patients with N-EOUC (89.7%) between 1986 and 2015. During the median follow-up of 104.5 months, the overall exposure to medications was comparable between patients with EOUC and N-EOUC (p=0.091 for corticosteroids, p=0.794 for thiopurines, and p=0.095 for anti-tumor necrosis factor agents). The cumulative risks of disease outcomes were also comparable between patients with EOUC and N-EOUC (22.4% vs 30.4% for proximal disease extension [p=0.351], 11.9% vs 18.1% for hospitalization [p=0.240], and 2.3% vs 1.8% for colectomy [p=0.977]) at 10 years after diagnosis. Multivariate Cox regression analysis revealed that corticosteroid use at diagnosis was an independent predictor of proximal disease extension (hazard ratio [HR], 6.216; 95% confidence interval [CI], 1.314 to 28.826) and hospitalization (HR, 11.241; 95% CI, 3.027 to 41.742) in patients with EOUC. Conclusions: In this population-based study from Korea, the pattern of medication use seemed comparable between the EOUC and N-EOUC groups. Moreover, patients with EOUC and those with N-EOUC have a similar disease course in terms of proximal disease extension, hospitalization, and colectomy. (Gut Liver 2021;15:742-751)
( Sang Hyeok Im ),( Dong Hwan Kim ),( Young Hoon La ),( Nam Jin Kim ),( Cha Won Hwang ),( Jae Min Cha ),( Bong Ki Ryu ) 대한금속재료학회 ( 구 대한금속학회 ) 2010 재료마당 Vol.23 No.3
This study looks at crystallization and sintering behavior in B2O3 containing Li2O-Al2O3-SiO2 glass powder. The sintered sample was produced with glass powders measuring 44 μm. The relative density and transmittance of the sintered samples showed the highest value at the temperature of 650°C. At temperatures higher than 650°C, crystal growth occurred to decrease the densification of B2O3-Li2O-Al2O3-SiO2 (BLAS) glass powder. The main crystalline phase in the glass powder was a-spodumene. From non-isothermal differential thermal analysis, the crystallization of particles (Φ=44 μm) was observed at 640°C to 684°C with respect to the heating rate. The activation energy of crystallization (E(C)) and the Avrami constant (n) calculated by Kissinger and Ozawa equations indicated that the surface and the bulk crystallization occurred simultaneously in the glass. The optimum sintering temperature of this glass powder was 650°C without crystal growth of β-spodumene, although nucleation or nano-crystal growth occurred.
Changes in Cytokine Expression after Electroacupuncture in Neuropathic Rats
Cha, Myeoung Hoon,Nam, Taick Sang,Kwak, Yongho,Lee, Hyejung,Lee, Bae Hwan Hindawi Publishing Corporation 2012 Evidence-based Complementary and Alternative Medic Vol.2012 No.-
<P>The production of proinflammatory cytokines including interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor-<I><I>α</I></I> (TNF-<I><I>α</I></I>) plays a key role in chronic pain such as neuropathic pain. We investigated changes in cytokine expression in injured peripheral nerves and dorsal root ganglia (DRG) following electroacupuncture (EA) treatment. Neuropathic pain was induced by peripheral nerve injury to the left hind limb of Sprague-Dawley rats under pentobarbital anesthesia. Two weeks later, the nerve-injured rats were treated by EA for 10 minutes. The expression levels of IL-1<I><I>β</I></I>, IL-6, and TNF-<I><I>α</I></I> in peripheral nerves and DRG of neuropathic rats were significantly increased in nerve-injured rats. However, after EA, the cytokine expression levels were noticeably decreased in peripheral nerves and DRG. These results suggest that EA stimulation can reduce the levels of proinflamtory cytokines elevated after nerve injury.</P>
Hoon Cho,최두복,Yu Lan Piao,Sun-Jong Yu,Yeon-Woong Lee,Dong-Hoon Lim,Young Cheol Chang,SANG-SHIN PARK,Myung Koo LEE,WOL-SUK CHA,Don-Sang You 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.6
We investigated the antihyperglycemic and antioxidant activities of polysaccharides produced from Pleurotus ferulae mutant in streptozotocin-induced diabetic rats. Blood glucose level in the STZ-induced diabetic rat administered the extract polysaccharides, 250mg/kg b·w/d (EPSG) was 196.97mg/dL, approximately 54.12% less compared to that of the STZ-induced diabetic rats administered 0.9% NaCl solution (NCG). The insulin level in the EPSG was approximately 1.64-fold higher than that in the NCG. HDL and LDL cholesterol levels in the EPSG were 29.15mg/L and 20.35mg/dL, respectively, representing an approximate increase of 69.18% and decrease of 38.52%, respectively. The activities of aspartate aminotransferase (AST) and alanine transferase (ALT) in the EPSG decreased approximately by 49.27 and 50.43%, respectively, while the alkaline phosphatase (ALP) activity decreased by 34.25%, relative to the NCG. Antioxidant activities in the NCG decreased relative to the normal group. In contrast, for EPSG, these values increased relative to the NCG. The malondialdehyde level in the EPSG was 12.95mmol/mg protein, which was approximately 70.64% of that in the NCG. These results suggest that the polysaccharides of Pleurotus ferulae mutant could be developed as potential antidiabetic agents or functional foods for people with a high risk of diabetes mellitus.
Cha, Hoon-Suk,Bae, Eun-Kyung,Ahn, Joong-Kyong,Lee, Jae-Joon,Ahn, Kwang-Sung,Koh, Eun-Mi Korean Society for Biochemistry and Molecular Bion 2010 Experimental and molecular medicine Vol.42 No.6
Inadequate apoptosis contributes to synovial hyperplasia in rheumatoid arthritis (RA). Recent study shows that low expression of Puma might be partially responsible for the decreased apoptosis of fibroblast-like synoviocytes (FLS). Slug, a highly conserved zinc finger transcriptional repressor, is known to antagonize apoptosis of hematopoietic progenitor cells by repressing Puma transactivation. In this study, we examined the expression and function of Slug in RA FLS. Slug mRNA expression was measured in the synovial tissue (ST) and FLS obtained from RA and osteoarthritis patients. Slug and Puma mRNA expression in FLS by apoptotic stimuli were measured by real-time PCR analysis. FLS were transfected with control siRNA or Slug siRNA. Apoptosis was quantified by trypan blue exclusion, DNA fragmentation and caspase-3 assay. RA ST expressed higher level of Slug mRNA compared with osteoarthritis ST. Slug was significantly induced by hydrogen peroxide ($H_2O_2$) but not by exogenous p53 in RA FLS. Puma induction by $H_2O_2$ stimulation was significantly higher in Slug siRNA-transfected FLS compared with control siRNA-transfected FLS. After $H_2O_2$ stimulation, viable cell number was significantly lower in Slug siRNA-transfected FLS compared with control siRNA-transfected FLS. Apoptosis enhancing effect of Slug siRNA was further confirmed by ELISA that detects cytoplasmic histone-associated DNA fragments and caspase-3 assay. These data demonstrate that Slug is overexpressed in RA ST and that suppression of Slug gene facilitates apoptosis of FLS by increasing Puma transactivation. Slug may therefore represent a potential therapeutic target in RA.
Conversion to Veno-arteriovenous Extracorporeal Membrane Oxygenation for Differential Hypoxia
Cha Ho Jeong,Kim Jong Woo,Kang Dong Hoon,Moon Seong Ho,Kim Sung Hwan,Jung Jae Jun,Yang Jun Ho,Byun Joung Hun 대한심장혈관흉부외과학회 2023 Journal of Chest Surgery (J Chest Surg) Vol.56 No.4
Background: Patients who require initial venoarterial extracorporeal membrane oxygenation (VA ECMO) support may need to undergo veno-arteriovenous ECMO (VAV ECMO) conversion. However, there are no definitive criteria for conversion to VAV ECMO. We report 9 cases of VAV ECMO at Gyeongsang National University Changwon Hospital, Gyeongsang National University College of Medicine. Methods: Of 158 patients who received ECMO support between January 2017 and June 2019, 82 were supported by initial VA ECMO. We retrospectively reviewed the medical records of 9 patients (7 men and 2 women; age, 53.1±19.4 years) who had differential hypoxia and required VAV ECMO support. Percutaneous transaortic catheter venting was used to detect the differential hypoxia. Results: Among the 82 patients who received VA ECMO support, 9 (10.9%) had differential hypoxia and required conversion to VAV ECMO support. The mean time from VA ECMO support to VAV ECMO support and the mean duration of the VAV support were 2.1±2.2 days and 1.9±1.5 days, respectively. The average peak inspiratory pressure before and after VAV ECMO application was 23.89±3.95 cmH2O and 20.67±5.72 cmH2O, respectively, decreasing by an average of 3.2±3.5 cmH2O (p=0.040). The PaO2/FiO2 ratio was kept below 100 mm Hg in survivors and non-survivors for 116±65.4 and 250±124.9 minutes, respectively (p=0.016). Six patients underwent extracorporeal cardiopulmonary resuscitation, of whom 4 survived (67%). The overall survival rate of patients who underwent conversion from VA ECMO to VAV ECMO was approximately 56%. Conclusion: Rapid detection of differential hypoxia is required when VA ECMO is applied, and efficient conversion to VAV ECMO may be critical for patient survival.
Cha, Ji-Yun,Jeon, Yong-Deok,Xin, Mingjie,Kim, Do-Kuk,Lee, Hoon-Yeon,Kim, Bo-Ram,Hwang, Sung-Woo,Kim, Dae-Ki,Jin, Jong-Sik,Lee, Young-Mi Informa UK (TaylorFrancis) 2017 Bioscience, Biotechnology, and Biochemistry Vol.81 No.11
<P>The aim of this study is to examine the anti-inflammatory effect of Euphorbia supina (ES) ethanol extract in dextran sulfate sodium (DSS)-induced experimental colitis model. ES was per orally administered at different doses of 4 or 20 mg/kg body weight with 5% DSS in drinking water for 7 days. Twenty mg/kg of ES administration regulated body weight decrease, recovered colon length shortening, and increased disease activity index score and myeloperoxidase level in DSS-induced colitis. Histological features showed that 20 mg/kg of ES administration suppressed edema, mucosal damage, and the loss of crypts induced by DSS. Furthermore, ES suppressed the expressions of COX-2, iNOS, NF-kB, IkBa, pIkBa in colon tissue. These findings demonstrated a possible effect of amelioration of ulcerative colitis and could be clinically applied.</P>