안구의 비색소성 모양체 상피에서 발생한 유두상 선암종 -1예 보고-

최현주,최영진,이연수,이은정,강석진,김병기,심상인 대한병리학회 1998 Journal of Pathology and Translational Medicine Vol.32 No.12

Magnetron sputtering법으로 제조된 Al-1%Cu/Tungsten Nitride 다층 박막

이기선,서수정,김장현,김남철 공주대학교 자원재활용신소재지역협력센터 2000 2차년도 센터 사업 성과집 Vol.2000 No.1

표면 탄성파 디바이스의 전극재료로 사용되는 Al-1%Cu(4000Å)/tungsten nitride 박막을 magnetron sputtering법으로 제조하고 전기저항을 평가한 결과 비정질상의 tungsten nitride 박막을 제조할 수 있었고, 비정질 형성을 위해서 질소비 (R = N2/(Ar+N2))가 10∼40% 정도 필요하였다. Tungsten nitride 박막의 잔류응력은 비정질이 형성되면서 급격히 감소되었다. 이러한 비정질 박막위에 Al-1%Cu합금막이 형성되었다. 다층막은 453K에서 4시간 동안 열처리함으로써 3.6μΩ-cm의 저항를 나타냈는데, 이는 박막내 결정립 성장과 결정 결함의 감소에 기인하였다. As a power durable-electrode in SAW filter. Al-1%Cu/tungsten nitride multi-layer thin film was fabricated by magnetron sputtering process. Tungsten nitride films had the amorphours phase at the nitrogen ratio, R, ranging from 10~40%. The amorphization could be controlled by nitrogen ratio. R = N2/(N2+Ar) as a sputtering process parameter. Residual stress in tungsten nitride abruptly decreased with the formation of amorphous phase. Al-1%Cu thin film was deposited on the amorphous tungsten nitride. After the multi-layed thin film was annealed for 4 hours at 453K, the resistivity decreased as 3.6 μΩ-cm, which was due to grain growth and reduced crystal defects.

노화가 인체 중간엽 줄기세포로부터 조골세포로의 증식 및 분화에 미치는 영향

백기현,태현정,오기원,이원영,조정기,권순용,강무일,차봉연,이광우,손호영,강성구,김춘추 대한내분비학회 2003 Endocrinology and metabolism Vol.18 No.3

연구배경: 일반적으로 골다공증과 연관된 위험인자로는 연령, 폐경, 약물, 불충분한 칼슘섭취, 만성질환 및 운동부족 등이 있는데, 특히 노화가 진행할수록 골밀도가 감소하는 것은 잘 알려져 있다. 노화와 관련하여 진행되는 골소실은 조골세포 및 전구조골세포의 기능적 결핍에 의한 골형성의 감소가 주요한 요인으로 여겨지고 있다. 그 동안 연령이 조골모 세포의 양과 조골모 세포로부터 성숙조골세포로의 분화 및 증식에 미치는 영향에 대한 일부 보고들이 있었으나 아직 일치된 견해는 없는 형편이다. 방법: 다양한 연령의 사람으로부터 골수를 채취, 중간엽 줄기세포가 포함된 단핵세포를 분리한 후 조골세포로 분화하기 좋은 조건하에서 배양하였다. 대상군은다시 젊은군과 노령군으로 구분하여 다양한 변수를 비교 분석하였다. 일차배양에서는 CFU-F를 계수하여 골수내 중간엽 줄기세포의 수를 추산하였고, 칼슘측정을 통하여 기질의 무기화 정도를 비교하였다. 계대배양후 이차배양에서는 시기별로 알카리성 포스파타제 활성도를 측정하고 오스테오칼신 mRNA의 발현을 관찰하여 젊은군과 노령군 사이의 증식능 차이를 비교하였다. 또한 이차배양 시기별로 MTT 측정을 하여 양군간에 증식능 차이가 있는지 알아보았다. 결과: 1. 일차배양 15일째에 평균 CFU-F의 수는 젊은군에서 유의하게 많았다(젊은군 148.3±28.9, 노령군 54.3±9.1, p=0.02). CFU-F의 평균면적은 젊은군에서 넓은 경향을 보였으나 통계적으로 유의하지는 않았다. 2. 일차배양 17일 경과 후 양군간에 기질 칼슘 침착정도는 유의한 차이를 보이지 않았다(젊은군 103.6±50.6, 노령군: 114.0±56.5, p=NS). 3. 이차배양 10일째에 젊은군에서 알카리성 포스파타제 활성도가 고령군에 비해 유의하게 높았다(젊은군: 935.5±115.0 U/mg, 노령군: 578.4±115.7U/mg,p.0.05). 고령군에서는 시간 경과에 따른 변화가 미약했으며 전반적으로 알카리성 포스파타제의 활성도가 젊은군에 비해 낮았다. 4. 이차배양도중 오스테오칼신 mRNA의 발현은 배양시기별로 젊은군에 비해 고령군에서 더 낮은 경향을 관찰할 수 있었다. 5. 이차배양 10일과 15일에 젊은군에서 노령군보다세포증식이 유의하게 증가된 양상을 보였다(10앓 젊은군 0.73±0.05, 노령군 0.58±0.04, p=0.05, 15일; 젊은군 0.80±0.05, 노령군 0.70±0.03, p=0.05).결론: 이상의 연구에서 저자들은 노령군에서 젊은군보다 골수 내 중간엽줄기세포의 수가 적고, 노령군에서 유래한 전구조골세포의 성숙조골세포로의 증식 및 분화가 젊은군 보다 감소해 있는 것을 관찰할 수 있었다. Background: Osteoblasts originate from osteoprogenitor cells in bone marrow stroma, termed mesenchymal stem cells (MSCs) or bone marrow stromal cells. Each MSC forms colonies (colony forming units-fibroblasts [CFL-Fs]) when cultured ex vivo. There are some reports about the age-related changes of the number and osteogenic potential of osteoprogenitor cells, but any relationship has not been clearly established in humans. In this study, we counted MSCs using CFU-Fs count and examined the proliferative capacity and differentiation potential of osteoprogenitor cells. Finally, we analyzed how these parameters varied with donor age. Methods: Bone marrow was obtained from the iliac crest of young (n=6, 27.2±8.6 years old) and old (n= 10, 57.4k6.7 years old) healthy donors. Mononuclear cells, including MSCs, were isolated and cultured in osteogenic medium. In primary culture, we compared the colony-forming efficiency of MSCs between the two groups and determined the matrix calcification. When primary culture showed near confluence, the cells were subcultured. Alkaline phosphatase activity, osteocalcin expression by RT-PCR and proliferative potential by MTT assay were examined by the time course of secondary culture. Results: At the 15th day of primary culture, the mean number of CFU-Fs was significantly higher in the younger donors (young: 148.3±28.9, old: 54.3±9.1, p=0.02) and the mean size of CFL-Fs was also larger in the younger donors than the older donors. However, matrix calcification was not different between the two groups (young: 103.6±50.6, old: 114.0±56.5, p=NS). In secondary culture, alkaline phosphatase activities were significantly lower in the older donors. The younger donors showed peak alkaline phosphatase activity at day 10, while the older donors didn't showed a remarkable peak (young: 935.5±115.OU/mg, old: 578.4±115.7U/mg, p<0.05). Total cell number as a proliferative index increased progressively during the secondary culture and a significantly greater cell number was noted in the younger donors. Osteocalcin expression was generally upregulated in the younger donors, but this was not statistically significant. Conclusion: Our study shows that the number of osteoprogenitor cells is decreased during aging and that the proliferative capacity and differentiation potential of osteoprogenitor cells seem to be reduced during aging (J Kor SOC Endocrinol 18:296-305, 2003).

학교와 학원의 비교를 통해 본 청소년의 플로우 및 내적경험

김기옥,현은자,최인수,유현정 대한가정학회 2004 Human Ecology Research(HER) Vol.42 No.4

The purpose of this study was to compare the school life of Korean high school students between public and proprietary schools, especially focused on their internal experience and flow. Internal experiences were composed of three dimensions: emotion, cognitive efficiency, and satisfaction. Flow was classified into four conditions: apathy, boredom, anxiety, and flow. The study results are: 1. Korean high school students felt more flow when they were in public school than in proprietary school,. In public school, they felt relatively more bored, and on the other hand, they were relatively more anxious in proprietary school. 2. Korean high school students felt more positive emotions when they were in public school than in proprietary school. 3. Korean high school students were more involved into study when they were in public school than in proprietary school. 4. Korean high school students were more satisfied when they were in public school than in proprietary school.

Fe-Ni-Co 저열팽창성 합금의 고온 변형 특성 및 열간가공에 따른 열팽창 거동 연구

이기안,박종혁,조봉현,남궁정,김문철 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.9

The high temperature deformation behavior and the effect of hot compression on the thermal expansion behavior of Fe-29Ni-17Co low thermal expansion Kovar alloy were investigated in the compressive temperature range of 900~1300℃ at the strain rate range of 25~0.01 sec.^(-1). The temperature (T) and strain rate (ε˙) dependence of the flow stress (σ_(0.7)) could be well described by hyperbolic sine law as ε˙= A [sinh(0.0084 σ)^(5.2018)] exp(-330.41/RT). Surface hot cracking and significant voids around grain boundary could be found at low temperature below 1000℃ and low strain rate (0.01 sec.^(-1)). Thermal expansion coefficient α_(30~400) generally increased with increasing compressive temperature. Moreover, α_(30~400) remarkably increased as strain rate decreased at high temperature above 1100℃. However the thermal expansion coefficient α_(30~400) of low compressive temperatures (900℃ and 1000℃) anomalously increased especially at high strain rates. Experimental results indicated that not only α phase appearance but also grain size had definite influence on the thermal expansion behavior with hot deformation. The correlation between microstructure and thermal expansion behavior of Kovar alloy were also discussed.

저열팽창성 Fe-29Ni-17Co 코바 합금의 고온균열 발생과 고온연성에 미치는 S 및 Mn의 영향

이기안,박종혁,조봉현,남궁정,김문철 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.12

The effect of S & Mn on the hot ductility of Fe-29Ni-17Co Kovar alloy and the mechanism of high temperature cracking occurrence were investigated. It has been found that the brittle intergranular fracture at high temperature cracking is closely associated with the sulfide along grain boundary. Experimental results showed, especially when the S content was high and the Mn content was free, that small cavities could be nucleated easily on FeS particles along grain boundary and propagated fast at high temperature. The hot ductility of Kovar alloy was drastically increased with the addition of Mn and it was also increased with decreasing S content. SEM and FE-SEM analyses showed that the Mn addition in this alloy could cause ductile intergranular fracture appearance below 1150℃ by the precipitation of MnS. It was proposed from the results that the addition of Mn and optimum S content (below 30 ppm) in Kovar alloy was necessary in order to reduce the hot cracking susceptibility.

고속 ATM 네트워크를 위한 통신 프로토콜에 관한 연구

박기현,안기중,이상배,강문식 연세대학교 산업기술연구소 1992 논문집 Vol.24 No.1

In this paper, a new network protocol, AD²R(ATM Distributed queue Dual Ring), is proposed for high-speed communication. This protocol is a slotted using ATM scheme. With the mathematical analysis and computer simulation, it is shown that proposed protocol is appropriate for the high-speed communication. Also, it is verified that the AD²R network performance is enhanced by using the ring topology, the destination release and the distributed queue scheme.

인터넷 쇼핑경험에서의 소비자만족 형성과정에 관한 연구

유현정,김기옥 대한가정학회 2002 Family and Environment Research Vol.40 No.5

This study aims to examine the forming procedure of consumer satisfaction from Internet shopping experience. Many studies on the satisfaction have primarily focused on the examination of the antecedents of satisfaction along with the expectation-disconfirmation paradigm dominating the former studies. This shady has built an Internet shopping expectation-disconfirmation model as to apply the expectation-disconfirmation model into the condition of the Internet shopping. The summary of study is represented in following. 1. The expectation of risk and performance of benefit had a significantly positive effect on the perceived disconfirmation. In addition, an expectation of benefit and performance of risk had a significantly negative effect on the perceived disconfirmation. 2. A performance of risk and performance of benefit not only had a significantly indirect effect, but also a significantly direct effect on the consumer satisfaction. But expectation of risk and expectation of benefit had no significant direct effect on satisfaction. 3. Not only the perceived disconfirmation had a significant positive effect on satisfaction, but also an effect of the perceived disconfirmation on satisfaction(0.472) is larger than that of the performance of risk or performance of benefit. Meaning that, it is desirable for one to apply the expectation-disconfirmation model into the Internet shopping circumstances as much as the off-line markets.

특발성 좌심실빈맥(Idiopathic Left Ventricular Tachycardia)의 성공적인 전극도자절제술을 위해 단극전기도(Unipolar Electrogram)가 유용한가?

최기준,남기병,강덕현,홍명기,송재관,김재중,박성욱,박승정,박종훈,김유호 대한순환기학회 2000 Korean Circulation Journal Vol.30 No.4

정사각튜브의 좌굴영역에 관한 실험적 연구

韓秉基,安大植,朴鳳賢,車正一 弘益大學校 科學技術硏究所 1996 科學技術硏究論文集 Vol.7 No.1

An experimental study is presented on the local and overall buckling of the square tubes made of mild steel. A total of 150 square tubes were axially loaded in quasi static loading condition. Three kinds of specimens were chosen according to the discrepancy of thickness to width. Based on th test results, a new domain for distinction of overall and local buckling is suggested on the square tube. It is different from that of the column. A experimental equation of the overall buckling is suggested.