NR과 SBR 가황물의 경도와 강성도에 대한 온도의 영향

진현호 ( Hyun Ho Jin ),홍창국 ( Chang Kook Hong ),조동련 ( Dong Lyun Cho ),강신영 ( Shin Young Kaang ) 한국고무학회 2007 엘라스토머 및 콤포지트 Vol.42 No.3

본 연구에서는 고무제품의 수치 안정성과 성능유지에 직접적으로 영향을 미치는 중요한 특성 중 하나인 온도변화에 따른 고무재료의 경도변화를 고찰하였다. 새롭게 제작된 International Rubber Hardness Degree(IRHD, Normal type) 경도측정 시험기를 사용하여 미충전된 NR과 SBR시편의 여러 온도에서 경도변화를 측정하였으며 Young`s modulus 값과 비교하였다. NR과 SBR 모두 유리전이온도 근처에서 경도와 Young`s modulus의 급격한 변화를 보였다. 온도가 증가함에 따라 경도와 Young`s modulus 값이 증가하는 경향을 보였으며 이는 분자의 운동성과 엔트로피 영향으로 해석할 수 있다. 카본블랙과 실리카가 충전된 NR과 SBR의 경우 충전제의 함량이 증가함에 따라 경도에 미치는 온도의 영향이 감소함을 관찰하였다. Hardness of rubbery materials, which is important for dimensional stability and product performance, was investigated upon temperature change in this study. A newly developed IRHD (International Rubber Hardness Degree) tester was used to measure the hardness changes of NR and SBR specimens at various temperatures and the hardness values were compared with the Young`s modulus. The hardness and Young`s modulus of NR and SBR showed an abrupt change near the glass transition temperatures. The hardness and Young`s modulus were increased by increasing temperature due to the increased random chain conformation of molecules. The effect of temperature on hardness and Young`s modulus of NR and SBR specimens filled with carbon black and silica was decreased by increasing filler content.

Critical role of bile acid (BA) in the cellular entry and permissiveness of Hepatitis B virus in vitro

Hong‑Jai Lee,Bo‑Young Shin,Jae‑Seung Moon,Ailyn Fadriquela,Selikem Abla Nuwormegbe,Chun‑Chang Ho,Jin‑Su Shin,Jee‑Sang Yoon,Sang‑Kyou Lee,Soo‑Ki Kim 대한독성 유전단백체 학회 2020 Molecular & cellular toxicology Vol.16 No.3

Background Lack of universal replication system for hepatitis B virus with narrow host range and organ tropism has hampered to uncover the pathogenesis of HBV. Previously, we reported the essentiality of humoral milieu and its components toward HBV and hepatitis C virus survival/viability in vitro. Of these components, the precise role of enterohepatic humoral milieu such as bile acid (BA) on HBV cultivation in vitro and in vivo is unknown. Objective We explored whether BA, specifically taurochenodeoxycholic acid (tCDCA) would directly regulate the viral DNA and surface antigen expression of HBV in vitro, consequently rendering HBV to enter into human or murine immortalized hepatocytes, and non-hepatocytes. Result We found that higher concentration of taurochenodeoxycholic acid (tCDCA) is able to preserve the genomic stability of HBV in cell-free DMEM, showing higher the surface antigenicity than taurocholic acid (tCA). In line, we found that in vitro cell culture condition (100 μmol/L of tCDCA coupled with 1 × 108 g e/mL HBV) would be optimal for HBV entry into target cells. Using this, human (HepG2, Huh7), and rodent (Hepa1c1c7, H4-II-E) hepatoma cell lines were infected by HBV, as evidenced by the presence of HBV biomarkers (HBsAg, and HBV DNA in culture supernatant, as well as HBcAg in cell). Further, cellular entry test revealed that HBV is able to infect 12 different non-hepatic cell lines regardless of species, and organ/tissue, consequently reproducing progeny as confirmed by HBV biomarkers. Last, reinfection test showed that the progenies of HBV from immortalized HepG2, and Hepa1c1c7 cells are able to enter into each or vice versa naïve HepG2, and Hepa1c1c7 cells with or without BA. Conclusion This study demonstrates that enterohepatic humoral milieu such as BA, specifically tCDCA would directly regulate HBV DNA and its surface antigen expression in vitro, consequently rendering HBV to enter into human or murine immortalized hepatocytes, and non-hepatocytes. This is the first note to render HBV permissive to human or rodent hepatic and non-hepatic cells via sole manipulation of humoral milieu, thus establishing the platform for in vitro robust replication system of HBV.

인터넷 중독 청소년들의 정신병리 및 대처 방식

안영균(Young Kyun Ahn),신영철(Young Chul Shin),고복자(Bok Ja Koh),심진현(Jin Hyun Shim),김범조(Bum Jo Kim),이승민(Seung Min Lee),이길홍(Kil Hong Lee) 한국중독정신의학회 2005 중독정신의학 Vol.9 No.1

This study was conducted to investigate the differences in psychopathology and coping strategies among internet addictors, over users and non addictors in high school students. Subjects were 273 high school students in Seoul city. Self rating questionnaires included demographic data, Young’s Internet Addiction Scale, SCL-90-R, Beck Depression Inventory, Spielberger State-Trait Anxiety Inventory, and The Way of Coping Strategy. Subjects were classified into 3 groups (addiction, over use, non addiction) by Internet Addiction Scale score. Prevalence of internet addiction was 4.3% and male adolescents were more addictive than female. Students who were mainly involved with internet chatting or game showed higher internet addiction score. The addiction group and over use group showed higher level of somatization, obsession, interpersonal sensitivity, depression, anxiety, hostility, and paranoia than non-addicted group. Addiction group and over use group used passive coping strategies more frequently in the stressful situation than nonaddicted group. Also, the regression analysis for finding out causal factors that predicts internet addiction showed that emotion relieving strategy were important variable which predict internet addiction. Interpersonal sensitivity and emotion relieving coping strategy was important to predict addiction. This study showed that problematic internet use was closely associated with psychopathology and psychiatric comorbidity. And high interpersonal sensitivity and emotion relieving coping strategy were related with internet addiction in adolescence.

야뇨증 환아들의 심리사회적 특성에 대한 다기관 연구 : 행동 및 정서 문제를 중심으로

조수철,김재원,신민섭,황준원,한상원,박관현,이상돈,김경도,김건석,서홍진,이유식,정재용,김영균,문두건,남궁미경,한창희,조원열,김영식,배기수,이종국,정우영,신의진 大韓神經精神醫學會 2005 신경정신의학 Vol.44 No.6

Objectives : The aim of this study was to examine the behavioral and emotional problems associated with nocturnal enuresis in Korean children. Methods : Three hundred eighteen children with nocturnal enuresis, together with their parents, completed the Child Behavior Checklist (CBCL), Disruptive Behavior Disorder Scale according to DSM-IV (DBDS), Children's Depression Inventory (CDI), State-Trait Anxiety Inventory for Children (STAIC), and Piers-Harris Children's Self-Concept Scale (PHCSC). Ninety-three normal students were selected as the control group. Results : Compared to the normal control group, the mean scores with regard to the withdrawn, social problems, attention problems, delinquent behavior, aggressive behavior, externalizing problems and total problems profiles were significantly higher in the nocturnal enuresis group according to the CBCL results. The nocturnal enuresis group also scored significantly higher in the ADHD and ODD profiles of the DBDS. The nocturnal enuresis group was more depressed and anxious than the control group according to the results of the CDI and STAI. The mean score of the PHCSC was significantly lower in the nocturnal enuresis group when compared to the normal control group. Conclusion : The results of this study suggest that children with nocturnal enuresis in Korea have clinically relevant behavioral and emotional problems. The findings support the link between nocturnal enuresis and psychopathology in Korean children.

연령증가에 따른 혈압요소들의 좌심실비대 및 관동맥질환과의 관련성

박재석,박창규,박미영,박재형,김용현,나진오,신성희,서순용,홍순준,박성미,임홍의,김응주,서홍석,오동주,노영무 대한순환기학회 2004 Korean Circulation Journal Vol.34 No.2

고분자형 자외선 안정제를 함유한 SBR과 NR의 UV 노화 거동에 관한 연구

남경태 ( Kyoung Tae Nam ),홍창국 ( Chang Kook Hong ),채규호 ( Kyu Ho Chae ),강신영 ( Shin Young Kaang ) 한국고무학회 2006 엘라스토머 및 콤포지트 Vol.41 No.3

본 연구에서는 고분자형 자외선 안정제 DGEBA-HALS의 광분해 억제 효과를 평가하기 위해 SBR과 NR 고무를 사용하여 광안정제 첨가에 따른 UV 조사 영향을 고찰하였다. 이를 위해 광안정제를 첨가하지 않은 배합고무, 사용화된 광안정제인 Cyabsorb UV-3529를 첨가한 배합고무, 그리고 고분자형 DGEBA-HALS를 첨가한 배합고무의 영율, 인장장고, blow-off 변형, 가교밀도 측정을 통한 시편의 물리적 특성변화 등을 관찰하였다. UV 조사 후 모든 시편에서 영율이 증가하였으며 인장강도는 광안정제를 첨가한 시편이 첨가하지 않은 시편보다 우수했다. 특히 NR의 경우 DGEBA-HALS 첨가 시 인장강도가 향상되었다. Blow-off 변형 실험결과도 영율 실험 결과와 비슷하였다. UV-vis transmissinon spectra를 통한 SBR 배합고무의 투과도를 조사한 결과 광안정제를 첨가함으로써 약 4%의 향상된 투과도를 보였다. Cyabsorb UV-3529와 DGEBA-HALS의 첨가는 비슷한 경향의 투과도를 나타내었다. SEM을 통해 시편의 표면을 관찰한 결과 광안정제를 첨가함으로써 UV 조사에 의한 균열의 크기가 작아짐을 알 수 있었고, 특히 DGEBA-HALS는 상용화된 Cyabsorb UV-3529 보다 더 좋은 광분해 안정효과를 갖는 것을 확인할 수 있었다. The retardation effects of a new polymeric UV stabilizer, DGEBA-HALS, on the UV degradation of SBR and NR were investigated in this study. The UV degradation behaviors of three different rubber compounds, without any photostabilizer and with commercial Cyabsorb UV-3529 and DGEBA-HALS, were compared. Also, the physical characteristics such as Young`s modulus, tensile strength, blow-off deformation and crosslink density were examined. The Young`s modulus was increased by UV irradiation for all samples, and the tensile strength, after UV irradiation, of the compound with UV stabilizer was better than that of the compound without stabilizer. Especially, the tensile strength of UV irradiated NR was improved by adding DGEBA-HALS. The results of blow-off deformation were in accord with those of Young`s modulus. The degree of transmission of SBR compounds obtained from UV-vis transmission spectra was improved about 4% by adding the UV stabilizer. Commercial Cyabsorb UV-3529 and DGEBA-HALS showed similar trends of transmission. The SEM photographs of SBR surface showed that the size of cracks created by UV irradiation became smaller by adding UV stabilizer. In particular, it is observed that the stabilization effect of DGEBA-HALS was better than that of commercial Cyabsorb UV-3529.

치은섬유모세포 및 치주인대세포에 의한 교원질 수축에 관한 연구

홍영안,김현수,주성숙,신제원 慶熙大學校 齒科大學 1995 慶熙齒大論文集 Vol.17 No.2

The purpose of this in vitro study was to evaluate contraction of the human gingival and periodontal ligament fibroblast in the collagen matrix. The cell cultures were prepared using human gingiva and tooth. The collagen gels were observed daily with an inverted microscope and their area was determined by measuring the diameters of the collagen gel. The configurations of human gingival and periodontal ligament fibroblasts were done by SEM observation. The results as follows; 1. The contraction was found to be proportional to seeding cell without seeding cells, the contraction was not occured. 2. Periodontal ligament fibroblast was shown more fast contraction than gingival fibroblast. 3. The collagen matrix was translucent initially, but with fully contraction, the structure become opaque. 4. The collagen matrix with fibroblast were aggregated to form bundles and reorganized collagen fiber.

SUS 304 마이크로 와이어 직선화 처리에 관한 연구

신홍규,김남수,김웅겸,홍남표,김병희,김헌영 江原大學校 産業技術硏究所 2004 産業技術硏究 Vol.24 No.A

In the study, we have developed a straightening system for the SUS 304 micro wires that are normally used in the medical and semi-conductor fields. To apply heat to the micro wires, we introduced the direct wire heating method which generates the thermal energy by the electrical resistance of the wire itself. To avoid the deterioration of the wire surface by the environment, such as the oxidation or the hydration, the N_(2) gas was filled in the glass pipe in which the straightening process was being performed. A precision tension meter was also attached to control the tension of the wire during the heating and straightening process. In order to control the straightening process, several experimental investigations with varying the tension, the feeding velocity and the temperature (current) was carried out. As a result of experiments, we obtained the optimal processing conditions satisfying the straightness requirement of the micro wires.

건설장비와 농기계에서 배출되는 연도별 대기오염 배출량 변화추세

신문기,김호정,장영기,홍지형 한국대기환경학회 2003 한국대기환경학회지 Vol.19 No.6

The annual air pollution emissions from construction and agricultural equipments were estimated from 1987 through 2000. The annual numbers and operation hours of 5 major construction equipments (Excavator, Bulldozer, Loader, Fork lift, Crane) and 3 major agricultural equipments (Power Tiller, Agricultural Tractor, Combine) were investigated for emission estimation. And monthly variation factors of operation hours of construction equipment were investigated too. The NOx emission from construction equipment have been gradually increased since 1987 to 1997, but sharply decreased as -45% in 1998 due to economic crisis in Korea. The NOx emission was estimated as 64,300 ton/year from construction equipment, and as 23,300 ton/year from agricultural equipment in 2000.

실용적인 전자투표 프로토콜 제안

홍영기,이재신,김순석,김성권 중앙대학교 정보통신연구소 1999 정보통신연구소논문집 Vol.1 No.1

정보화 시대에 세계적으로 컴퓨터의 보급 및 네트워크의 발달로 컴퓨터 응용분야에서 많은 발전이 이루어지고 있다. 그 중에서도 암호학을 이용한 전자투표는 전자화 되어 가는 민주 사회에서 필요한 요소로 부각되고 있다. 그러나 지금까지의 전자 투표는 중요성에도 불구하고 많은 문제점이 지적되었다. 본 논문에서는 추적할 수 없는 통신망[1]과 신뢰할 수 있는 선거관리센터를 가정함으로써 전자 투표의 요구사항인 안전성, 공정성, 투표자의 비밀성, 선거 집계의 정확성 등을 만족하는 대규모적이고 실용적인 전자투표 프로토콜을 제안한다. 블라인딩기법(Blinding Technique)을 이용하여 투표자의 투표내용을 노출시키지 않고 투표권을 획득하며, 부정할 수 없는 도전 및 응답프로토콜(Challenge and Responsible Protocol)을 사용하여 투표자와 집계자 사이의 부정을 확인할 수 있으며, 투표자나 집계자의 부정으로 인한 전자 투표의 무결성과 투표자의 프라이버시를 보호하기 위해 투표자의 익명을 기반으로 안전한 전자투표를 방식을 제안한다. We have seen a lot of developments on computer application areas with the wide spread use of computers and the rapid growth of communication network. It is necessary to use a cryptographic technique for electronic voting, but, at present, despite of its importance electronic voting protocols so far have many shortcomings. In this paper, with the assumption of untraceable communication channels and trustable voting centers we propose a large-scale and practical electronic voting protocol satisfying protocol requirements, such as secureness, fairness, privacy of voter and correctness. Voters are able to get a vote without revealing their voted information by using the blinding technique. We can find the injustice between a voter and the tallier by using undeniable challenge and responsible protocol. Also, we proposes a secure protocol that compensates a integrity of electronic voting and protects a privacy of voter from outer attacks as using a anonymity of voter.