Corrosion Behavior of Inconel X-750 for Carbon Anode Oxide Reduction Application

Jeon, Min Ku,Kim, Sung-Wook,Lee, Sang-Kwon,Choi, Eun-Young Korean Radioactive Waste Society 2020 방사성폐기물학회지 Vol.18 No.3

The corrosion behavior of the Inconel X-750 alloy was investigated for its potential application under a Cl₂-O₂ mixed gas flow in an Ar atmosphere. The corrosion rate was found to be negligible at temperatures up to 400℃ under a flow rate of 30 mL·min^-1 Cl₂ + 170 mL·min^-1 Ar, whereas an exponential increase was observed in the corrosion rate at temperatures greater than 500℃. The suppression of the corrosion reaction due to the presence of O₂ was verified experimentally at flow rates of 30 mL·min^-1 Cl₂ (4.96 g·m^-2·h^-1), 20 mL·min^-1 Cl₂ + 10 mL·min^-1 O₂ (2.02 g·m^-2 ·h^-1), and 10 mL·min^-1 Cl₂ + 20 mL·min^-1 O₂ (1.34 g·m^-2·h^-1) under a constant Ar flow rate of 170 mL·min^-1 at 600℃ for 8 h. The surface morphology analysis results revealed that porous surfaces with tunnel-type holes were produced under the Cl₂-O₂ mixed-gas condition. Furthermore, the effects of the Cl₂ flow rate on the corrosion rate were investigated, indicating that its impact was negligible within the range of 5-30 mL·min^-1 Cl₂ at 600℃.

실험적 급성 허혈성 신부전에서 Verapamil 이 혈중 Polyamine 동태에 미치는 영향

원동준(Dong Jun Won),권현민(Hyun Min Kwon),김용섭(Yong Seop Kim),구자룡(Ja Ryong Gu),권영주(Young Ju Kwon),조원용(Won Yong Cho),김형규(Hyung Kyu Kim) 대한내과학회 1991 대한내과학회지 Vol.40 No.6

N/A It has been proposd that calcium entry from an external medium increases intracellular free calcium to toxic levels during ischemic acute renal failure, and verapamil (ARF) has been suggested as the agentblocking calicium entry into renal cells and protecting renal function during ischemic injury. Polyamines, anorganic cations that play various roles in normal cellular proliferation and differentiation, accumulate in renal failare. Alsa it has been suggested tht the synthesis and metabolism of polyamine are influence by acute changes of the general condition, such as acute renal failure, and are mediated by a calcium influx into the cells. The study was designed to study the protective effects of systemic verapamil pretreatment on renal function and the influence on polyamine metabolism in experimental ischemic ARF in cats. For these purpose, the experimental animals were divided into 2 groups. While Group I (n=5) was an ischemic ARF model by renal artery clamping for 60 minutes, Group II (n=5) was ischemic ARF with systemic verapamil (5 ml/min/kg) pretreatment. The creatinine clearance and plasma and urinary polyamine were measured in each group before and after the renal artery clamp. The results were as follows: 1) Creatinine clearance before and after the renal artery clamp were 10.64±7.18 ml/min/kg and 2.09±1. 70 ml/min/kg in Group I, 4.47±3.38 ml min/kg and 0.60±0.79ml/min/kg in Group II, respectively, So creatinine clearance decreased more significantly in Group II campared with Group I. 2) Plasma polyamine increased after ischemia in Group I. In group I, plasma levels of putrescine, spermidine, and spermine before ischemia were 4.75±0.40 nmol/ml, 0.69±0.09 nmol/ml, and 0.83±0.63 nmol/ml, were elevated to 7.17±2.91 nmol/ml, 9.83±1.46 nmol/ ml, and 2.64±1.14nmol/ml after ischemia. But in Group II, the plasma level of polyamine was not changed, and especially, spermine decreased significantly from 0.83±0.27 before ischemia to 0.49±0.23 nmol/ml after ischenmine (p=0.033). 3) Urine polyamine excretion decreased after ischemia in Group I and Group II. In Group II, urinary excretion of spermidine and spermine before ischemia, 0.13±0.10 nmol/min and 0.17±0.13nmol/min, decreased after ischemia to 0.01±0.01nmol/min (p=0.019) and 0.032±0.26 nmol/min (p=0.0257). 4) In renal tissue, spermine content vas highest. In Group II, preischemic spermine were 397.20 nmol/g and increased to 646.66nmol/g after ischema, But there were no significant changes in the polyamine contents in Group II. From these data, it was suggested that systemic verapamil pretreatment exerts no protective effect on ischemic ARF. Plasma polyamines are elevated in ischemic ARF, and verapamil may protect these elevations.

Effects of hydrogen plasma treatment on SnO2:F substrates for amorphous Si thin film solar cells

Min-Seung Choi,Young-Ju Lee,Jung-Dae Kwon,Yongsoo Jeong,Ju-Yun Park,강용철,Pung Keun Song,Dong-Ho Kim 한국물리학회 2013 Current Applied Physics Vol.13 No.8

We investigated the effects of hydrogen plasma treatment on the physical and electrical properties of fluorine-doped tin oxide (FTO) films used for amorphous silicon (a-Si) thin film solar cells. A slight increase in carrier concentration by the hydrogen doping effect was observed for the FTO film exposed to the hydrogen plasma for 5 min. For further exposure to the plasma, the chemical reduction became prominent and resulted in deterioration of the electrical and optical properties of the film. XPS analysis revealed that the chemical reduction of SnO2 to Sn metallic state occurs on the surface region. It was found that the defects formed by hydrogen plasma act as recombination centers at the interface between FTO electrode and p-layer of a-Si solar cells. This phenomenon resulted in the deterioration of the cell performance. The averaged conversion efficiency (6.82%) of the cells on pristine FTO hydrogen substrate was decreased to 5.81% for the cells on FTO treated for 5 min, which is mainly attributed to the decrease in short-circuit current density.

Decoding the Modern Fantasy of `White People, Korean` : An Analysis of Images from `the King Young-jo & Jung-jo` to `the open port era`

Min, Soo hong,Kwon, Young Gull 한국색채학회 2006 한국색채학회 학술대회 Vol.2006 No.1

Polystyrene composites containing crosslinked polystyrene-multiwalled carbon nanotube balls

Kwon, Soon-Min,Kim, Hun-Sik,Kim, Don-Young,Yun, Young Soo,Jin, Hyoung-Joon Wiley Subscription Services, Inc., A Wiley Company 2008 Journal of applied polymer science Vol.110 No.6

<P>Crosslinked polystyrene-multiwalled carbon nanotube (PS-MWCNT) balls, which act as conductive microfillers, were prepared by the in situ suspension polymerization of styrene with MWCNTs and divinyl benzene (DVB) as a crosslinking agent. The diameters of the synthesized crosslinked PS-MWCNT balls ranged from 10 to 100 μm and their electrical conductivity was about 7.7 × 10<SUP>−3</SUP> S/cm. The morphology of the crosslinked PS-MWCNT balls was observed by scanning electron microscopy and transmission electron microscopy. The change in the chemical structure of the MWCNTs was confirmed by Raman spectroscopy and Fourier transform infrared spectroscopy. The mechanical and electrical properties of the PS/crosslinked PS-MWCNT ball composites were investigated. It was found that the tensile strength, ultimate strain, Young's modulus, and impact strength of the PS matrix were enhanced by the incorporation of the crosslinked PS-MWCNT balls. In addition, the mechanical properties of the PS/crosslinked PS-MWCNT ball composites were better than those of the PS/pristine MWCNT composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008</P>

The Effect of Mobile Neurofeedback Training in Children with Attention Deficit Hyperactivity Disorder: A Randomized Controlled Trial

Seo Young Kwon,Gyujin Seo,Mirae Jang,Hanbyul Shin,Wooseok Choi,You Bin Lim,Min-Sup Shin,Bung-Nyun Kim 대한정신약물학회 2024 CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE Vol.22 No.1

Objective: To examine the effect of mobile neurofeedback training on the clinical symptoms, attention abilities, and execution functions of children with attention deficit hyperactivity disorder (ADHD). Methods: The participants were 74 children with ADHD aged 8−15 years who visited the Department of Child and Adolescent Psychiatry at Seoul National University Children’s Hospital. The participants were randomly assigned to the mobile neurofeedback (n = 35) or control (sham; n = 39) group. Neurofeedback training was administered using a mobile app (equipped with a headset with a 2-channel electroencephalogram [EEG] sensor) for 30 min/day, 3 days/week, for 3 months. Children with ADHD were individually administered various neuropsychological tests, including the continuous performance test, Children’s Color Trails Test-1 and 2, and Stroop Color and Word Tests. The effects of mobile neurofeedback were evaluated at baseline and at 3 and 6 months after treatment initiation. Results: Following treatment, both mobile neurofeedback-only and sham-only groups showed significant improvements in attention and response inhibition. In the visual continuous performance test, omission errors decreased to the normal range in the mobile neurofeedback-only group after training, suggesting that mobile neurofeedback effectively reduced inattention in children with ADHD. In the advanced test of attention, auditory response times decreased in the mobile neurofeedback + medication group after training, but increased in the sham+medication group. Overall, there were no significant between-group differences in other performance outcomes. Conclusion: Mobile neurofeedback may have potential as an additional therapeutic option alongside medication for children with ADHD.

기계적 자극을 이용한 인체 중간엽줄기세포로부터 유사-섬유모세포로의 분화 유도

최경민 ( Kyung Min Choi ),서영권 ( Young Kwon Seo ),윤희훈 ( Hee Hoon Yoon ),권순용 ( Soon Yong Kwon ),이화성 ( Hwa Sung Lee ),박용순 ( Yong Soon Park ),손영숙 ( Young Sook Son ),송계용 ( Kye Yong Song ),김영진 ( Young Jin Kim 한국조직공학과 재생의학회 2006 조직공학과 재생의학 Vol.3 No.4

Recently, in vitro reconstruction of anterior cruciate ligament(ACL) has been tried using tissue engineering technique, especially mesenchymal stem cell(MSC) is considered as a good cell source. In this study, we tried to find the effect of mechanical stimulus on the differentiation of bone marrow-derived MSC into ACL fibroblastlike cell using a cell training bioreactor imposing cyclic mechanical tension whose parameters were 120 min/day, 1 Hz, and 5% strain. After 2 weeks of culture, MSCs under cyclic tension showed more regularly oriented alignment and lower expression of CD73 and CD105 than control by microscopy and FACS analysis. In transcriptional level, type I collagen, type II collagen, fibronectin, elastin, α-smooth muscle actin mRNA expressions of MSCs under cyclic tension were higher than control and similar to native ACL. In conclusion, it is thought that mechanical cyclic tension induced the loss of stemness of MSC, therefore improved the differentiation into ACL fibroblast-like cell.

Feasibility of Calibrating Smartphone to Access Physical Activity

이정민(Jung Min Lee),김영원(Young Won Kim),권이석(Yi Suk Kwon),Timothy R. Derrick,Gregory J. Welk 한국체육측정평가학회 2015 한국체육측정평가학회지 Vol.17 No.3

대부분의 신체활동측정을 위해 연구들은 가속도계를 이용하여 측정되어져 왔다. 하지만, 스마트폰이 대중화 되면서스마트폰에 내장된 가속도계를 이용하여 신체활동을 측정 할 수 있는 에플리케이션들이 빈도 높게 늘어나고 있다. 따라서 이 연구에서는 스마트폰에 내장되어 있는 가속도계를 이용하여 에너지 소비량을 구하는 공식을 만들고 그 공식을 현재 연구중심으로 많이 사용되는 가속계와 비교하고 교차분석을 통하여 정확성과 실용성을 검증하는 것이다. 이러한 목적을 달성하기 위하여 건강한 성인 44명을 편의추출 하여 가속계와 스마트폰을 착용시켜 69분 동안 다양한 일상생활 활동을 시켰으며 신체활동 측정의 준거검사인 간접열량계(Oxycon Mobile)가 사용되었다. 회귀분석을 통하여 만들어진 연산은 교차 타탕도 분석을 통하여 정확도를 검증하였고 검사도구의 정확성은 절대오차율(%)을 계산하고 검사도구간 상관계수 (r), Bland-Altman plot 과 equivalence testing 사용하여 검증하였다. 연구결과에 의하면 스마트폰을 통해 얻어진 절대오차율은 (42.4%)를 보였고 Freedson`s 기준치와 비교했을 때는 (38.2%)를 보였다. 그러나 스마트폰을 통해 만들어진 연산은 걷기 와 달리기의 에너지 소비량은 측정하는데 유의하다는 결과가 나왔다. 추후, 스마트폰만을 이용한 신체활동 측정이 다양하게 필요하고 그 정확성을 검증하는 연구들도 필수적으로 요구된다. The purpose of the study was to develop algorithms to predict energy expenditure (EE) and to evaluate their utility compared to existing accelerometer technology. Forty-four participants wore an Actigraph GT3X (AG3X) and the Samsung Galaxy S2 Smartphone (SP) over a 69 min period. Oxygen consumption (VO<sub>2</sub>) was simultaneously measured by a portable indirect calorimetry system. EE prediction equations for the SP were developed from the walking and running activities using standard regression methods. The equation was then cross-validated on a separate holdout sample (n=22) using equivalence testing to evaluate accuracy. The overall mean absolute percentage errors were large for both the SP algorithm (42.4%) and the Freedson`s AG3X algorithm (38.2%). However, the estimated METs from the SP was statistically equivalent to the measured METs for the two activities used in calibration: walking (90% CI: 2.85, 3.50 kcal·min-1) and running (90% CI: 7.64, 8.25 kcal·min-1). Other activities were not accurately assessed with the SP but none of the estimates from the AG3X met the statistical criteria for equivalency. The study demonstrates that data from SP can be easily calibrated to estimate EE and that accuracy is comparable to the common research-grade monitors.

젊은 성인에서 흡연에 의한 상완동맥 내피기능의 부전에 관한 연구

이상철,권영주,방덕원,이선해,이보영,김지욱,김영훈,온영근,현민수,김성구 순천향의학연구소 2002 Journal of Soonchunhyang Medical Science Vol.8 No.1

Background and Objectives : Cigarette smoking is a major factor and the most modifiable risk factor for atherosclerosis. Endothelial dysfunction is an early event in atherosclerosis, before the structural change of the systemic arteries. We hypothesized that endothelial dysfunction might be present in the systemic arteries of young adult smokers and that this might be dose-dependent phenomenon. Therefore, we try to certify that smoking is associated with endothelial dysfunction in healthy young adults without other risk factor of atherosclerosis. Subjects and Methods : we studied noninvasively 29 subjects aged 3 to 4 decades without other risk factor of atherosclerosis, they were composed of the two groups, current smokers(n=15) and nonsmokers(n=14). Smoking history varied from 3 to 20 pack years. Using high-resolution ultrasound, vessel diameter and mean flow rate were measured at rest, during reactive hyperemia(with flow-mediated endothelium-dependent dilation), and after sublingual nitroglycerin(NG-induced endothelium-independent vasodilation). Result : Flow mediated endothelium dependent dilation was observed in the control subjects (9.4±3.44%) but was impaired in the smokers(5.8±2.51%)(p=0.004). NG-induced endothelium independent dilation is no difference in all subjects. Conclusion : Cigarette smoking is associated with endothelial dysfunction in healthy young adults.

A study on the removal of sulfate and nitrate from the wet scrubber wastewater using electrocoagulation

Jo, Eun-young,Park, Seung-Min,Yeo, In-seol,Cha, Jae-doo,Lee, Ju Yeol,Kim, Young-Hee,Lee, Tae-Kwon,Park, Chan-gyu Informa UK (Taylor Francis) 2016 Desalination and Water Treatment Vol.57 No.17

<P>Wet scrubber is widely used to remove pollutants from a furnace flue gas or from other gas streams. However, high cost for the treatment or exchange of contaminated washed water is one of the problems. Electrocoagulation (EC) is an electrochemical method for treating polluted water, whereby sacrificial anodes dissolve to produce active coagulant precursors in the solution. This technology can be used for the removal of color, anionic contaminants, and colloidal particles. The goal of the present study was evaluation of EC process for treatment of wet scrubber wastewater and optimization of the process. In this study, the influence of electrode material and electrode distance on removal efficiency (%) of nitrate, sulfate, and total suspended solids (TSS) was investigated with synthetic wastewater. Using an Al electrode, 60.6% of nitrate, 50.0% of sulfate, and 96.8% of TSS were removed by EC treatment within 30 min. In case of Fe electrode, 69.7% of nitrate, 75.0% of sulfate, and 98.8% of TSS were removed. The treatment efficiency for real wet scrubber wastewater was evaluated with Fe electrode. After 180 min of EC treatment, 50% of color, 40% of nitrate, 40% of sulfate, and 95% of TSS were removed, respectively. All these results give clear evidence that EC process can effectively reduce the TSS, nitrate, and sulfate ions from wet scrubber wastewater.</P>