전도도계의 제작에 관한 연구

강용환,최석남,박병빈 공주대학교 사범대학 과학교육연구소 1980 과학교육연구 Vol.12 No.1

A low-cost student type conductance meter have been developed for the measurement of conductivity of electrochemical system. This instrument measures an impedance range from ?? Ohm with 2% accuracy. And this instrument could be applied to measure the rapid chemical reaction.

치환된 알킬요드화물 또는 크산테이트 화합물과 에틸 아크릴산 또는 메틸 비닐케톤과의 분자간 라디칼 탄소-탄소 결합형성반응

강석구,박영원,박천호,조일환,오원택 성균관대학교 1992 論文集 Vol.42 No.2

생리활성천연물인 lipoxin A, carpenter bee 페로몬, 뇌염모기 페로몬, exobrevicomin 등의 합성의 주요 키탈 중간체들을 치환된 요드화물 또는 크산테이트 화합물과 에틸아크릴산 또는 메틸비닐케톤과의 분자간 라디칼 탄소-탄소 형성 반응에 의해 합성하였다. The chiral building blocks for the synthesis of biologically active natural products such as lipoxin A, carpenter bee pheromone, mosquito ov-iposition pheromone, and exo-brevicomins were synthesized by intermol-ecular radical C-C bond formation of the appropriate substituted iodides or xanthates with ethyl acrylate or methyl vinyl ketone.

포르피린증 환자에서 보인 가역적 자기공명영상소견 1례

강석윤,마효일,곽규환,이상암 대한신경과학회 1998 대한신경과학회지 Vol.16 No.2

Flowable 및 microfill 복합레진으로 충전된 제 5급와동에서 load cycling 전,후의 미세변연누출 비교

강석호,김오영,오명환,조병훈,엄정문,권혁춘,손호현 大韓齒科保存學會 2002 Restorative Dentistry & Endodontics Vol.27 No.2

Low-viscosity composite resins may produce better sealed margins than stiffer compositions (KempScholte and Davidson, 1988; Crim, 1989). Flowable composites have been recommended for use in Class V cavities but it is also controversial because of its high rates of shrinkage. On the other hand, in the study comparing elastic moduli and leakage, the microfil had the least leakage (Rundle et al. 1997). Furthermore, in the 1996 survey of the Reality Editorial Team, microfills were the clear choice for abfraction lesions. The purpose of this study was to evaluate the microleakage of 6 composite resins (2 hybrids, 2 microfills, and 2 flowable composites) with and without load cycling. Notch-shaped Class V cavities were prepared on buccal surface of 180 extracted human upper premolars on cementum margin. The teeth were randomly divided into non-load cycling group (group 1) and load cycling group(group 2) of 90 teeth each. The experimental teeth of each group were randomly divided into 6 subgroups of 15 samples. All preparations were etched, and Single bond was applied. Preparations were restored with the following materials (n=15) : hybrid composite resin [Z250(3M Dental Products Inc. St.Paul, USA), Denfil(Vericom, Ahnyang, Korea)], microfil [Heliomolar RO(Vivadent, Schaan, Liechtenstein), Micronew(Bisco Inc. Schaumburg, IL, USA)], and flowable composite[AeliteFlo(Bisco Inc. Schaumburg, IL, USA), Revolution(Kerr Corp. Orange, CA, USA)]. Teeth of group 2 were subjected to occlusal load (100N for 50,000 cycles) using chewing simulator(MTS 858 Mini Bionix Ⅱ system, MTS Systems Corp., Minn, USA). All samples were coated with nail polish 1mm short of the restoration, placed in 2% methylene blue for 24 hours, and sectioned with a diamond wheel. Enamel and dentin/cementum margins were analyzed for microleakage on a sclale of 0 (no leakage) to 3 (3/3 of wall). Results were statistically analyzed by Kruskal-Wallis One way analysis, Mann-Whitney U-test, and Student-Newmann-Keuls method. (p=0.05) Results: 1. There was significantly less microleage in enamel margins than dentinal margins of all groups. (p<0.05) 2. There was no significant difference between six composite resin in enamel margin of group 1. 3. In dentin margin of group 1, flowable composite had more microleakage than others but not of significant differences. 4. There was no significant difference between six composite resin in enamel margin of group 2. 5. In dentin margin of group 2, the microleakage were R>A=H=M>D>Z. But there was no significant differences. 6. In enamel margins, load cycling did not affect the marginal microleakage in significant degree. 7. In dentin margins, load cycling did affect the marginal microleakage only in Revolution. (p<0.05)

액체-고체 순환유동층에서 액상의 반경 방향 혼합 및 액체-고체 Chaotic 흐름 거동

강석환,이찬기,송평섭,강용,김상돈,김승재 한국화학공학회 2004 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.42 No.2

직경이 0.102m이고 높이가 3.5m인 액체-고체 순환유동층의 상승관에서 압력요동 및 액체의 반경 방향 혼합 특성을 고찰하였다. 상승관에서 얻은 압력요동을 해석하기 위하여 chaos 이론을 도입하였다. 액체 유속, 유동입자의 크기 그리고 고체 유동입자의 순환속도가 연속액상의 반경방향 분산계수 및 압력요동의 위상공간투영과 상관차원에 미치는 영향을 결정하였다. 본 연구의 결과 액상의 반경방향 분산계수는 유동입자의 크기와 순환속도가 증가함에 따라 증가하였으며 액상의 유속이 증가함에 따라 감소하였다. 상승관에서 압력요동의 위상공간투영은 유동입자의 크기가 고체 유동입자의 순환속도가 증가함에 따라 점점 분산되고 복잡하게 되었으나, 액체유속이 증가함에 따라서는 위상공간에서 궤적의 분산이 다소 감소하는 경향을 나타내었다. 압력요동의 상관차원은 유동입자의 크기와 고체 순환속도가 증가함에 따라 증가하였으나, 액체의 유속이 증가함에 따라서는 큰 변화가 없었다. 본 연구의 결과는, 상승관에서 액상의 반경 방향 혼합 특성 압력요동 측정함으로써 실시간으로 예측하는 것을 가능하게 하여 실제공정에 응용함으로써 그 실용적 측면이 크다고 하겠다. Characteristics of pressure fluctuations and liquid dispersion in the radial direction were investigated in the riser of a liquid-solid circulating fluidized bed whose diameter was 0.102m and 3.5m in height. The concept of chaos theory was employed to analyze the pressure fluctuations obtained in the riser. Effects of liquid velocity, particle size, and solid circulation rate on the liquid radial dispersion coefficient and phase space portraits and correlation dimension of pressure fluctuations were determined. It was found that the radial dispersion coefficient of liquid phase increased with increasing particle size or solid circulation rate, but decreased with increasing liquid velocity. The attractor in the phase space portraits became more scattered and complicated with increasing particle size or solid circulation rate, but it became somewhat less scattered with increasing liquid velocity. The correlation dimension of pressure fluctuations increased with increasing particle size or solid circulation rate, but it did not change considerably with increasing liquid velocity. The results of this study enable us to predict the characteristics of liquid radial dispersion by means of the pressure fluctuations for the practical applications.

대형연구개발사업 평가제도의 체계적 도입방안

윤석환,강근복 한국정책학회 2003 韓國政策學會報 Vol.12 No.4

최근 국가전략적인 원천기술개발의 필요성과 과거 대규모의 연구개발비를 투자했던 연구 개발사업의 성공사례를 바탕으로 대형 연구개발사업의 추진이 확대되고 있다. 연구개발평가는 평가대상이 되는 연구개발사업의 특성에 적합한 평가체계의 구축을 통해 운용되어야 한다. 이러한 관점에서 본 연구는 대형연구개발사업의 특성에 적합한 연구개발 평가제도의 체계화를 위해서 대형연구개발사업의 특성을 도출하고 이에 근거한 실태분석을 통해 평가제도의 개선방향을 제시하였다. 대형연구개발사업의 특성으로는 연구개발목표와 연구개발수단의 관점에서 국가 전략적 목표에 의한 사업추진과 광범위한 파급효과, 연구개발비의 대규모성, 연구기간의 장기성, 다수의 세부과제로 구성되어 있다는 특성이 도출되었다. 이러한 특성을 반영하여 대형연구개발사업의 평가체계를 구축함에 있어서는 사전타당성 평가의 제도화, 평가의 체계적 연속성 확보, 대형과제 단위의 평가, 평가결과 활용을 위한 환류체계의 강화가 중요시되어야 함을 제안하였다. Recently, many large-scale R&D programs with the national strategic purposes are made and performed. R&D evaluation system should be managed in accordance with the characteristics of R&D programs. The purpose of this study is to distinguish the characteristics of large-scale R&D program, to analyze the practice or R&D evaluation system, and to suggest a evaluation system for that. The national strategic objective, far-reaching influences. large-scale investment. long-tern period of R&D activities, and the composite of some sub projects are the characteristics of large-scale R&D program. We suggest that when we design the evaluation system for large-scale R&D programs, we have to consider these characteristics. And also the systematic continuity of evaluation processes, large-scale project based evaluation, pre-evaluation system, and reinforced feedback system are suggested as important factors to be considered.

조구등(釣鉤藤)의 4-VO로 유발한 흰쥐뇌허혈에 대한 신경방어효과

李仁煥,林康鉉,李鍾錫,石庚浩,安德均,朴虎君,김頀哲 대한본초학회 1999 大韓本草學會誌 Vol.14 No.2

Uncariae Ramulus et Uncus(UR, ???) has sweet in flavour and slightly cold in property, acting on the liver and pericardium channels. This drug was described in a medical classic as having the ability to remove "heat", check hyperfunction of the liver and relieve dizziness, tremors, and convulsion, and subdue "endogenous wind". So this study was planned to check the neuroprotective effect of UR on the global ischemia induced by 4-vessel occlusion in Wistar rats. and UR extract was lyophilized after extraction with 70% methanol. We induced 4-vessel occlusion for 10 minutes and reperfused again. The number of CA1 pyramidal neurons were counted after 7 days of reperfusion under the cresyl violet staining. In 4-VO ischemia model, UR showed significantly neuroprotective effects(1,000 and 500 ㎎/㎏ of UR extracts, p<0.05) compared with control group. Each neuroprotective ratio was about 23.0%, 19.0% respectively. Consequently, Uncariae Ramulus et Uncus has neuroprotective effects on the global ischermia induced by 4-vessel occlusion in Wistar rats. So we expect that Uncariae Ramulus et Uncus can be used as a drug for neurodegenerative disease.

學生用 自動記錄計에 關한 硏究

崔錫南,姜庸煥 공주대학교 사범대학 과학교육연구소 1981 과학교육연구 Vol.13 No.1

A low cost student type recorder have been developed for measurement of temperature of chemical system. This instrument measure a temperature range from 0℃ to 100℃ And this instrument could be applied to measure the thermochemical reaction.

삼상 순환유동층의 상승관에서 연속 액상의 축방향 혼합특성

유명선,손성모,강석환,강용,김상돈 한국공업화학회 2004 공업화학 Vol.15 No.1

직경이 0.102 m이고 높이가 3.5 m인 기체-액체-고체 순환 유동층의 상승관에서 액상의 축방향 혼합특성을 고찰하였다. 기체유속(0.01~0.07 ㎧), 액체유속(0.25~0.31 ㎧) 그리고 고체순환속도(2~8 ㎏/㎡s)를 실험변수로 선정하였으며 이들 변수들이 액상의 축방향 분산계수에 미치는 영향을 고찰하였다. 축방향의 추적자 농도분포로부터 분산모델을 사용하여 액상의 축방향 분산계수를 구하였다. 액상의 축방향 분산계수는 기체유속과 고체순환속도가 증가함에 따라서 증가하였으나 액체의 유속의 증가에 따라서는 약간 감소하였다. 또한, 액상의 축방향 분산계수는 등방성 난류 모델을 적용한 무차원군으로 표현되는 상관식으로 나타낼 수 있었다. Characteristics of liquid dispersion in the axial direction were investigated in the riser of a three-phase circulating fluidized bed whose diameter is 0.102 m and 3.5 m in height. Effects of gas (0.01-0.07 m/sl and liquid (0.25-0.31./s) velocities and the circulation rate of solids (2∼8 kg/m^(2)s) on the dispersion coefficient of the continuous liquid phase in the axial direction were determined. A dispersion model was employed to obtain the axial dispersion coefficient of the liquid phase from the radial concentration profiles of tracer with variations of axial position. The axial dispersion coefficient of the liquid phase increased with increasing gas velocity or solid circulation rate, however, decreased slightly with increasing liquid velocity in the riser bed. The axial dispersion coefficient of the liquid phase was well correlated in terms of dimensionless groups based on the isotropic turbulence theory.

포러스콘크리트의 기초물성에 미치는 시멘트페이스트의 유동성 및 진동다짐시간의 영향에 관한 실험적 연구

김무한,백용관,최영욱,강석표,김재환,이성일 忠南大學校 産業技術硏究所 2001 산업기술연구논문집 Vol.16 No.2

This study analyzed the influence of paste fluidity and vibration time for fundamental properties of porous concrete. Results of this study were shown as follows: 1) Even if target void ratio is same, void ratio and compressive strength of porous concrete is different according to w/c, paste flow and vibration time. So, In case of target void ratio, we must consider the influence of w/c, past flow and vibration time. 2) Though w/c and vibration time is same, as paste flow increase, all void ratio, continuous void ratio, and compressive strength decrease and difference between upper and lower void ratio increase. 3) Though w/c and paste flow is same, as vibration time increase, all void ratio and continuous void ratio decrease and difference between upper and lower void ratio increase. Also, compressive strength increase by 10 seconds and decease after 10 seconds. 4) As types of superplasticizer is different, all void ratio, continuous void ratio, and compressive strength is different. So, we must give consideration to paste fluidity and vibration time in order that increase of strength of porous concrete and distribution of uniform void.