Analysis and Evaluation of Capillary Passive Valves in Microfluidic Systems Using a Centrifugal Force

Cho, Han-Sang,Kim, Ho-Young,Kang, Ji-Yoon,Kwak, Seung-Min,Kim, Tae-Song The Korean Institute of Electrical Engineers 2004 KIEE International Transactions on Electrophysics Vol.4C No.4

This work reports the theoretical and experimental investigations of capillary bust valves to regulate liquid flow in microchannels. The theoretical analysis uses the Young-Laplace equation and geometrical considerations to predict the pressure at the edge of the valve opening. Numerical simulations are employed to calculate the meniscus shape evolution while the interface is pinned at the valve edge. Microchannels and valves are fabricated using soft lithography. A wafer-rotating system, which can adjust the driving pressure by rotational speed, induces a liquid flow. Experimentally measured valve-bursting pressure agrees with theoretical predictions.

The Influence of AH-26 and Zinc Oxide-Eugenol Root Canal Sealer on the Shear Bond Strength of Composite Resin to Dentin

Cho, Ju-Yeon,Jin, Myoung-Uk,Kim, Young-Kyung,Kim, Sung Kyo 大韓齒科保存學會 2006 Restorative Dentistry & Endodontics Vol.31 No.3

AH-26 근관실러가 상아질에 대한 복합레진의 전단결합강도에 미치는 영향을 평가하기 위하여 144개의 발거된 대구치를 실린더형의 몰드에 매식한 다음 치관부의 상아질 표면을 노출시킨 후 편평하게 연마하고 AH-26을 도포한 군, ZOE paste를 도포한 군 및 실러를 도포하지 않은 대조군으로 나누어 One-step 상아질 접착제를 처리한 후에 Charisma (Heraeus Kulzer, Germany) 복합레진을 적용하고 광중합시켰다. 시편을 분리하여 37℃ 항온조에 24시간 보관후 Instron test machine (Model 4202, Instron Corp., USA)을 이용하여 시편의 전단 결합 강도를 측정하고 one-way ANOVA 및 Tukey's studentized rank test로 통계 분석하였다. AH-26 근관실러로 처리한 군과 대조군은 ZOE 근관실러 처리군에 비해 유의하게 놓은 접착강도를 나타내었다 (p<0.05). AH-26 근관실러 처리군과 아무 처리하지 않은 대조군 사이에는 결합강도에 있어 유의한 차이를 나타내지 않았다 (p>0.05). 본 연구의 조건에서는 ZOE 근관실러는 상아질에 대한 복합레진의 전단결합강도를 저하시키는 반면 AH-26 근관실러는 유의한 영향을 미치지는 않는 것으로 보인다. 따라서 임상에서 근관실러로 AH-26을 사용한 근관충전 후에는 즉시 복합레진 코어를 해 주어도 결합력에 저해가 없을 것으로 여겨진다. The purpose of this study was to evaluate the influence of the AH-26 root canal sealer on the shear bond strength of composite resin to dentin. One hundred and forty four (144) extracted, sound human molars were used. After embedding in a cylindrical mold, the occlusal part of the anatomical crown was cut away and trimmed in order to create a flat dentin surface. The teeth were randomly divided into three groups; the AH-26 sealer was applied to the AH-26 group, and zinc-oxide eugenol (ZOE) paste was applied to the ZOE group. The dentin surface of the control group did not receive any sealer. A mount jig was placed against the surface of the teeth and the One-step dentin bonding agent was applied after acid etching. Charisma composite resin was packed into the mold and light cured. After polymerization, the alignment tube and mold were removed and the specimens were placed in distilled water at 37℃ for twenty four hours. The shear bond strength was measured by an Instron testing machine. The data for each group were subjected to one-way ANOVA and Tukey's studentized rank test so as to make comparisons between the groups. The AH-26 group and the control group showed significantly higher shear bond strength than the ZOE group (p<0.05). There were no significant differences between the AH-26 group and the control one (p>0.05). Under the conditions of this study, the AH-26 root canal sealer did not seem to affect the shear bond strength of the composite resin to dentin while the ZOE sealer did. Therefore, there may be no decrease in bond strength when the composite resin core is built up immediately after a canal filling with AH-26 as a root canal sealer.

How Do Retail Regulations Influence a Retail Sector? A Comparative Study of Korea and Other Countries

Cho,Young-Sang,Kwak,Young-Arm 한국유통과학회 2019 KODISA ICBE (International Conference on Business Vol.2019 No.-

By comparing South Korea and advanced countries, in terms of the effects of retail legislations on a retail sector, the authors are to provide new insights for Korean policy makers. The research will review existing literature concerned about the effects analysis of retail regulations. When comparing Korea and other countries, the authors will focus on identifying the effects of retail employment and productivity, how regulations influence retail price, and further, whether retail restrictions really protect independent retailers. The authors found that developed countries have made a significant effort to protect small- and medium-sized retailers for social stability with many different regulations and/or budget. With regard to results, however, the degree of its achievement is lower than expected. In order to protect mom and pops efficiently and effectively, policy makers need to develop better sophisticated retail regulations than those of advanced countries.

Characterization of Silver Inkjet Overlap-printing through Cohesion and Adhesion

Sang?Ho Lee,Young?June Cho 대한전기학회 2012 Journal of Electrical Engineering & Technology Vol.7 No.1

We introduce an understanding of silver (Ag) inkjet overlap-printing characteristics from the viewpoints of cohesion between ink droplets and adhesion between an ink droplet and a surface. The printing characteristics were closely monitored by changing the surface energy to elucidate the effect of adhesion and cohesion on printing instability, such as droplet merging and line bulging. The surface energy of the substrate was changed through the hydrophilization of a hydrophobic fluorocarbon-coated surface. The surface energy and ink wettability of the prepared surfaces were characterized using sessile drop contact angle analysis, and printing instability was observed using an optical microscope after drop-on-demand inkjet printing with a 50% overlap in diameter of deposited singlet patterns. We found that the surface energy is not an appropriate indicator based on the experimental results of Ag ink printing on a hydrofluoric-treated silicon surface. The analytical approach using adhesion and cohesion was helpful in understanding the instability of the inkjet overlap-printing, as adhesion and cohesion represent the direct interfacial relationship between the Ag inks used and the substrate.

LC, Acute : O-061 ; Mode of cirrhosis related complication in Korean patients with liver cirrhosis -A prospective multicenter cohort study

( Hyun Young Woo ),( Jeong Won Jang ),( Sang Gyune Kim ),( Chang Hyeong Lee ),( Tae Yeob Kim ),( Won Young Tak ),( Sung Kyu Choi ),( Mong Cho1 ),( Jong Young Choi ) 대한간학회 2012 춘·추계 학술대회 (KASL) Vol.2012 No.-

Background: Cirrhosis-related complications are indications for transplantation. However, the mode of complication has not been evaluated so far. To better address this issue, we investigated the mode of cirrhosis related complication and impact of these complications on survival in prospective, multicenter, inception cohort study of subjects with liver cirrhosis presenting with the first onset of decompensated complication. Methods: In this observational study, 1515 patients with the confirmed onset time of the first decompensated complication were enrolled. The mortality risk of cirrhosis-related complications, including ascites, portal hypertensive gastrointestinal bleeding (PHGB), spontaneous bacterial peritonitis (SBP), hepatic encephalopathy (HE), hepatorenal syndrome (HRS), was analyzed in these cirrhotic patients. Result: As the first complication, ascites was the most frequent (53.8%), followed PHGB (36.2%), HE (7.6%), SBP (1.7%) and HRS (0.7%). During follow-up (mean 32±47 months), 484 (31.9%) experienced subsequent decompensations and the proportion of subsequent complication was consistently changed; the proportion of HE, SBP, HRS increased as time progressed. The interval between subsequent decompensative events was progressively shortened. The mortality rate according to the first complication was as follows; Ascites =PHGB> HE=SBP>HRS. The mortality rate of patients experienceing subsequent complication was significantly higher than those without subsequent complication. According to the kinds of subsequent complication, survival of HE was also higher than HRS but lower than ascites or PHGB and similar to that of SBP and this difference of survival disappeared after repeated complication. Conclusion: The mortality risk correlated with initial complication and the risk increases as the number of complication episodes is repeated. Patient`s mean age was 56±11.50 years and 72.1% was male. The cause of liver cirrhosis is hepatitis B virus (38.6%), alcohol (35.5%) and hepatitis C virus (8.9%).

Three-Dimensional Porous Collagen/Chitosan Complex Sponge for Tissue Engineering

Kim, Sung Eun,Cho, Yong Woo,Kang, Eun Jung,Kwon, Ick Chan,Lee, Eunhee Bae,Kim, Jung Hyun,Chung, Hesson,Jeong, Seo Young The Korean Fiber Society 2001 Fibers and polymers Vol.2 No.2

A three-dimensional, porous collagen/chitosan complex sponge was prepared to closely simulate basic extracellular matrix (ECM) constitutes, collagen and glycosaminoglycan. The complex sponge was prepared by a lyophilization method and had the regular network with highly porous structure, suitable for cell adhesion and growth. The pores were well interconnected, and their distribution was fairly homogeneous. The complex sponge was crosslinked using 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) to increase its boilogical stability and enhance its mechanical properties. The crosslinking medium has a great effect on the inner structure of the sponge. The homogeneous, porous structure of the sponge was remarkably collapsed in an aqueous crosslinking medium. However, the morphology of the sponge remained almost intact in a water/ethanol mixture crosslinking milieu. Mechanical properties of the collagen/chitosan sponge were significantly enhanced by EDC-mediated crosslinking. The potential of the sponge as a scaffold for tissue engineering was investigated using a Chinese hamster ovary cell (CHO-K1) line.

연구보문 : 식물환경 ; 폐가축사체의 농업적 재활용을 위한 가축사체 액상부산물의 액비화 조건 구명

서영진 ( Young Jin Seo ),서동철 ( Dong Cheol Seo ),강세원 ( Se Won Kang ),이상규 ( Sang Gyu Lee ),박주왕 ( Ju Wang Park ),최익원 ( Ik Won Choi ),성환후 ( Hwan Hoo Sung ),강석진 ( Seog Jin Kang ),조주식 ( Ju Sik Cho1 ) 한국환경농학회 2013 한국환경농학회지 Vol.32 No.4

가축사체 액상부산물을 이용하여 액비의 최적조건(미생물, pH, 미생물 주입량)을 조사하였고, 이들 최적 조건하에서 112일간 부숙하여 액비의 품질을 평가하였다. 가축사체 액상 부산물 액비 부숙시 최적 LP 미생물의 주입량은 0.5 mL/100mL이었으며, pH는 7 조건에서 각각 50점으로 완숙판정을 받았다. 최적조건하에서 112일 동안 부숙시킨 액비의 부숙도 는 부숙 후 28일에 50점을 받아 완숙판정을 받았으며, 부숙기 간이 길어짐에 따라 부숙 56일에는 온도가 60℃를 넘어 최고 점인 55점을 받았고, 이후 온도가 조금씩 낮아져 부숙 후 112 일에는 실온조건에 이르렀다. 완숙된 가축사체 액상부산물 액 비의 품질을 평가해본 결과, 최적조건하에서 부숙시킨 액비의 경우에는 T-N, P2O5 및 K2O의 함량이 28일에 가장 높았으며, 시간이 경과함에 따라 약간 감소하는 경향이었다. 또한, 유해성분(As, Cd, Cu, Cr, Hg, Ni, Pb 및 Zn)의 함량은 28일, 56일 및 112일 부숙시킨 액비에서 모두 비료공정규격 기 준치에 적합하였다. 이상의 결과를 미루어 볼 때 가축사체 액상부산물을 농업적 재활용을 위한 액비화 조건은 pH 7조건 에서 LP 미생물을 0.5 mL/100 mL 주입한 경우이다. 하지 만 본 연구에서 비교된 가축분뇨 발효액은 공시재료(가축사체)가 상이하여 향후 가축사체를 이용한 액비의 부숙도 기준이 개선되어야 할 것으로 판단된다. BACKGROUND: Globally, concern about emerging infectious diseases of livestock is growing. For the disposal of the animal carcass, it is necessary to recycle the carcass into an agriculturally usable product. The objective of this study was to investigate the composting conditions of liquid by-product obtained from degradation of animal carcass. METHODS AND RESULTS: Optimum conditions of liquid fertilizer were investigated using different microorganisms, pHs, and volumes of microorganisms (Lactobacillus rhamnosus + Pichia deserticola). Based on the results from the optimum conditions, compost maturity and quality of liquid fertilizer were evaluated for 112 days. The compost maturity of liquid fertilizer were higher in the order of LP(Lactobacillus rhamnosus + Pichia deserticola) > BC(Bacillus cereus) > BS (Bacillus subtilis). The optimum condition under different volumes of LP was injection of 0.5 mL/100 mL. The compost maturity under different pHs were higher in the order of pH 7 > 5 ≥ 9 ÷ 11. The liquid by-product at 56 days after composting was completely decomposed. The concentrations of T-N, T-P and K2O in liquid fertilizer at 56 days were 0.94, 0.17 and 3.78%, respectively, and the sum of those concentrations was 4.89%. CONCLUSION(S): Liquid fertilizer of by-product using pig carcass was decomposed with optimum conditions(LP, pH 7, injection of 0.5 mL/100 mL) in 56 days after composting, and was suitable for official standard of commercial fertilizer.

연령집단에 따른 노인의 허약(Frailty) 예측요인 분석

조성은 ( Cho Sung Eun ),최은영 ( Choi Eun Young ),오영삼 ( Oh Young Sam ),김영선 ( Kim Young Sun ),김성복 ( Kim Seong Bok ) 한국보건사회연구원 2017 保健社會硏究 Vol.37 No.3

본 연구의 목적은 연령집단에 따른 허약의 예측요인을 분석하는 것이다. 연구의 목적을 위해 2014년 노인실태조사를 사용하여 총 4,123명을 분석의 대상으로 설정하였다. 허약을 예측하는데 있어 연령의 중요성을 고려하여, 본 연구는 대상자를 75세 이상 85세 미만의 중 고령노인집단(n=3,373명)과 85세 이상의 초 고령노인집단(n=750명)으로 분류하여 연구모형을 검증하였다. 중 고령노인집단에서 전 허약노인과 허약노인은 각각 1453명(약 43%), 1,268명(약 37%)으로 나타났으며, 초 고령노인 집단에서 전 허약과 허약노인은 304명(약 40%), 396명(약 52%)으로 나타났다. 회귀분석의 결과 건강단계에서 허약전 단계로 진입하는 예측요인은 중 고령노인집단에서는 여성, 낮은 교육수준, 많은 만성질환, 낙상 유경험자, 높은 우울, 낮은 인지기능이 허약 전 단계를 예측하는 유의한 변인으로 밝혀졌으며 초 고령노인집단은 여성, 높은 우울, 낮은 사회활동이 유의한 예측요인으로 밝혀졌다. 허약 전 단계에서 허약 단계로의 진입을 예측하는 요인으로는 중 고령노인집단은 여성, 높은 연령, 미취업, 많은 만성질환, 낙상 유경험자, 높은 우울, 낮은 인지기능이 유의한 변인이었으며, 초 고령노인 집단은 높은 연령, 많은 만성질환, 높은 우울, 낮은 인지기능이 유의한 예측요인으로 밝혀졌다. 본 연구는 연령의 세분화와 다각적인 요인의 접근으로 허약의 예측요인을 밝히고자 하였다. 연구를 통해 밝혀진 예측요인은 추후 허약에 대한 다각적 연구의 기초자료로서 활용되리라 기대한다. This study aims to investigate the predictors of frailty in different age groups. To address this purpose, this study used the 2014 Survey of the Living Conditions of the Elderly (SLCE). In the research model, 4,123 older adults aged 75 and older were included from the SLCE. All participants were subdivided into two age groups based on their age; the young old group (75-85) and the old-old group (85+). The young old group consisted of 1,453 (43%) pre-frail older adults and 1,268 (37%) frail older adults; the old-old group consisted of 304 (40%) pre-frail older adults and 396 (52%) frail older adults. Our regression analysis showed that in the young-old, being female, lower levels of education, having more chronic diseases, having fall experience, higher depression, lower cognitive functioning significantly predicted transition to pre-frailty from non-frail status. In the old-old, being female, higher depression, lower level of social activity were significant predictors. On the other hand, predictors of transition to frailty from pre-frail status in the young-old were being female, higher age, being unemployed, having more chronic diseases, having fall experience, higher depression, lower cognitive functioning. In the old-old, predictors of transition to frailty from pre-frail status were only higher age, having more chronic disease, higher depression, and lower cognitive functioning. The research findings can be used as a reference point in the making of strategies for preventing frailty.

Original Articles : Clinical significance of occult hepatitis B virus infection in chronic hepatitis C patients

( Jae Young Jang ),( Soung Won Jeong ),( Sung Ran Cheon1 ),( Sae Hwan Lee1 ),( Sang Gyune Kim ),( Young Koog Cheon ),( Young Seok Kim1 ),( Young Deok Cho1 ),( Hong Soo Kim ),( So Young Jin ),( Yun Soo 대한간학회 2011 Clinical and Molecular Hepatology(대한간학회지) Vol.17 No.3

Background/Aims: We investigated the frequency of occult hepatitis B virus (HBV) infection in anti-hepatitis C virus (HCV)-positive individuals and the effects of occult HBV infection on the severity of liver disease. Methods: Seventy-one hepatitis B virus surface-antigen (HBsAg)-negative patients were divided according to their HBV serological status into groups A (anti-HBc positive, anti-HBs negative; n=18), B (anti-HBc positive, anti-HBs positive; n=34), and C (anti-HBc negative, anti-HBs positive/negative; n=19), and by anti-HCV positivity (anti-HCV positive; n=32 vs. anti-HCV negative; n=39). Liver biopsy samples were taken, and HBV DNA was quantified by real-time PCR. Results: Intrahepatic HBV DNA was detected in 32.4% (23/71) of the entire cohort, and HBV DNA levels were invariably low in the different groups. Occult HBV infection was detected more frequently in the anti-HBc-positive patients. Intrahepatic HBV DNA was detected in 28.1% (9/32) of the anti-HCV-positive and 35.9% (14/39) of the anti-HCV-negative subjects. The HCV genotype did not affect the detection rate of intrahepatic HBV DNA. In anti-HCV-positive cases, occult HBV infection did not affect liver disease severity. Conclusions: Low levels of intrahepatic HBV DNA were detected frequently in both HBsAg-negative and anti-HCV-positive cases. However, the frequency of occult HBV infection was not affected by the presence of hepatitis C, and occult HBV infection did not have a significant effect on the disease severity of hepatitis C. (Korean J Hepatol 2011;17:206-212)

Neuroprotective effects of bovine colostrum on intracerebral hemorrhage-induced apoptotic neuronal cell death in rats

Kim, Sung Eun,Ko, Il Gyu,Shin, Mal Soon,Kim, Chang Ju,Ko, Young Gwan,Cho, Hanjin Medknow PublicationsMedia Pvt Ltd 2012 Neural regeneration research Vol.7 No.22

<P>Brain cell death after intracerebral hemorrhage may be mediated in part by an apoptotic mechanism. Colostrum is the first milk produced by mammals for their young. It plays an important role in protection and development by providing various antibodies, growth factors and nutrients, and has been used for various diseases in many countries. In the present study, we investigated the anti-apoptotic effects of bovine colostrum using organotypic hippocampal slice cultures and an intracerebral hemorrhage animal model. We performed densitometric measurements of propidium iodide uptake, a step-down avoidance task, Nissl staining, and caspase-3 immunohistochemistry. The present results revealed that colostrum treatment significantly suppressed N-methyl-D-aspartic acid-induced neuronal cell death in the rat hippocampus. Moreover, colostrum treatment improved short-term memory by suppressing hemorrhage-induced apoptotic neuronal cell death and decreasing the volume of the lesion induced by intracerebral hemorrhage in the rat hippocampus. These results suggest that colostrum may have a beneficial role in recovering brain function following hemorrhagic stroke by suppressing apoptotic cell death.</P>