• 전자공학회논문지A
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• 제33A권10호
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• pp.130-138
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• 1996

The size of a device needs to scale down to increase its integrity and speed. As the size of the device is reduced, the hot-carrier degradation that severely effects on device reliabilty is concerned. In this paper, sub-micron buried-channel P-MOSFETs were fabircated, and the hot-carrier effects were invetigated. Also the hot-carrier effect in the buired-channel P-MOSFETs and the surface-channel P-MOSFETs were compared with simulation programs using SUPREM-4 and MINIMOS-4. This paper showed that the electric characteristics of sub-micron P-MOSFET are different from those of N-MOSFET. Also it showed that the punchthrough voltage ( $V_{pt}$ ) was abruptly drop after applying the stress and became almost 0V when the channel lengths were shorter than 0.6.mu.m. The lower punchthrough voltage causes the device to operte poorly by the deterioration of cut-off characteries in the switching mode. We can conclude that the buried channel P-MOSFET for CMOS circuits has a limit of the channel length to be around 0.6.mu.m.

• Tuberculosis and Respiratory Diseases
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• 제48권5호
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• pp.788-793
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• 2000

결절성 경화증의 폐침윤은 드문 것으로 알려져 있는데 저자들은 결절성 경화증과 신장의 혈관근지방종으로 추적 관찰중인 환자에서 폐의 기흉이 발생하여 고해상 전산화단층촬영과 병리조직소견에서 HMB-45 양성인 평활근의 증식을 보인 폐의 림프관평활근종증을 진단받은 1예를 경험하였기에 보고하는 바이다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 추계학술대회 논문집
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• pp.557-570
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• 2000

It is necessary to perform a study on the interrace between a G7 pantograph and a KTX catenary system prior to G7 on-line tests in the Korea High Speed Test Track in order to predict how high current collection quality can be obtained during the on-line tests and check if safety problems shall be caused b)Y the tests or not. According to the simulation results, current collection quality of the G7 pantograph at 350km/h is lower than that of a GPU pantograph at 300km/h, but the contact wire uplifts and average contact forces are within the safe-zone. In addition, the ratio of running speed (350km/h) to safe running. Therefore, the G7 on-line tests at 350km/h in the Korea High Speed Test Track is expected not to cause the safety problem.

• 센서학회지
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• 제14권6호
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• pp.374-380
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• 2005

Vibration sensors have a wide scope of applications in the field of monitoring systems that needs to perceive an undesirable physical vibration before a critical failure occurs in a system, and then costly unplanned repairs can be avoided. The conventional vibration sensors developed so far have many disadvantages, such as complex manufacturing process, bulkiness, high cost, less reliability and so on. This paper reports a simple-structured vibration sensor, which has been developed using a commercialized conductive ball and silicon bulk-micromachining technology. The sensor consists of a conductive ball placed in $600{\mu}m$-deep micromachined silicon groove, in which Au thin film has been patterned using a shadow mask technique. Prior to the formation of the Au thin film, the sharp convex corner was rounded for smooth meatl deposition on the non-planar surface at the edge of the groove. The measurement results of the fabricated vibration sensor demonstrate a stable response characteristic to low-frequency vibration range ($1{\sim}30{\;}Hz$).

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2010년도 춘계학술발표대회 초록집
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• pp.50-50
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• 2010

최근 토요타 자동차의 대량 리콜 사태로 안전과 관련된 자동차 품질에 대한 관심과 중요성이 크게 부각되었다. 본 연구에서는 나날이 높아지고 있는 자동차 품질 기준과 생산 비용 절감, 공정 자동화 요구에 부응하기 위한 차체 저항 점 용접부 품질 검사 자동화 기술 개발을 위해 적용 가능한 센서들을 비교, 검토하였다. 알려진 비파괴 검사 방법은 초음파, 와전류, 방사선 검사법 등 다양한 방법들이 존재하지만, 이 연구에서는 생산 라인 현장 적용이 가능한 소형 센서들을 중심으로 검토 영역을 제한하였다. 검토된 비파괴 검사 방법은 총 5가지 종류로 종래의 수동 초음파 검사법, 집적된 탐촉자를 이용한 3차원 초음파 검사법, NAUT(Non-contact Air-coupled Ultrasonic Test), EMAT(EletroMagnetic Acoustic Test), 그리고 너겟 프로파일러$^{TM}$이다. 이 연구에서는 각 검사법의 원리와 장단점을 설명하고 생산 라인 적용에 필요한 필수 항목들에 대해 고찰하였다.

• Tuberculosis and Respiratory Diseases
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• 제52권5호
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• pp.545-549
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• 2002

임신시에 발생한 폐동정맥기형은 드문 질환으로 유전성 출혈성 모세혈관확장증과 같이 유전적으로 동반되어 나타날 수 있는 질환이다. 저자들은 임신시에 발생한 호흡곤란과 흉부방사선촬영상의 종괴를 주소로 내원한 환자에서 발견된 폐동정맥기형 1예를 경험하였기에 문헌고찰과 함께 보고하는 바이다.

• 한국환경과학회지
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• 제26권1호
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• pp.79-85
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• 2017

Multi-Walled Carbon Nanotubes (MWCNTs) were modified with epoxy and aminosilane diethanolamine (DEA), and nanocomposites of poly(butylene adipate-co-terephthalate) (PBAT) and the modified MWCNTs were prepared with the aim of improving the physical properties of biodegradable PBAT. The physical and the thermal properties of the PBAT/MWCNT nanocomposites were investigated using various techniques. Fourier transform infrared spectroscopy measurements revealed that the MWCNTs were efficiently modified with DEA. Scanning electron micrographs of the nanocomposites indicated that the modified MWCNTs were dispersed homogeneously in PBAT. The thermal stability of the nanocomposite decreased with increase in the content of epoxy-MWCNT-DEA due to the poor thermal stabilities of epoxy and amino silane DEA. However, the surface hydrophobicity of the nanocomposite increased. The highest stress (170% of PBAT) was observed when the content of epoxy-MWCNT-DEA in the nanocomposite was 2 wt%.

• 동력기계공학회지
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• 제14권1호
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• pp.16-21
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• 2010

This research focused on the spray and distribution characteristics of urea solution by applying flow visualization techniques and did durability and driver test on injectors as well. The spray characteristics of urea solution was observed by CCD camera. Also, the distribution characteristics of urea solution was evaluated quantitatively as well by using 3D laser scanner equipment. It was considered that it was reasonable to use the injector for gasoline engine in order to inject the urea. The best distribution chart result was observed near 45cm distance difference between catalyst and urea spray injector. As a result of trapped urea distribution chart analysis, optimal pressure and volumetric flow rates of air and urea were derived in order to improve the distribution of Urea. This information may contribute to provide fundamental data in the future.

• 한국임상수의학회지
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• 제14권2호
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• pp.208-214
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• 1997

The objective of this study was (a) to examine the change of bloodchemistry and (b) to investigate the secretion trend of endocrinological substance in a dog model after laser-beam radiation at different level of frequency (250 Hz, 2,000 Hz, 5,000 Hz and 8,000 Hz). The experimental groups were divided into four groups were divided into four groups on the basis of the level of frequency radiated and stimulated for five minutes. Before stimulation and after a lapse of time (10-minute, 30-minute and 60-minute) all dogs were checked the following parameters; cortisol, ACTH, RBC, hemoglobin, hematocrit, WBC, Ca, P, ALT, AST and creatinine. The results were as follow: ten minutes after stimulation, cortisol level of 250 Hz group, 2,000 Hz group, 5,000 Hz group and 8,000 Hz group was increased 18.8%, 20.5%, 23.2% and 309%, respectively. Ten minutes after stimulation, ACTH level of 250 Hz group, 2,000 Hz group, 5,000 Hz group and 8,000 Hz group was increased 26.7%, 26.6%, 30.5% and 29.5%, respectively. It began to decrease and at 30-minute after stimulation resturned to pre-stimulation level at 60-minute after stimulation. In blood examination RBC, hemaoglobin, hematocrit and WBC level showed slight increase and decrease and returned to pre-stimulation level at 60-minute after radiation. In bloodchemical examination serum calcium, inorganic phosphorus, ALT, AST and creatinine level were within normal physiological ranges.

• 정신신체의학
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• 제5권1호
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• pp.63-72
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• 1997

For the purpose of examining the relationship between perceived stress, vulnerability variables, and somatization tendency, the self-report questionnaires of perceived stress, styles of stress coping(passive and active copings), self-perception, gender, and somatization tendency were administered to university entrants(n=2,024). The results were as follows: 1) Perceived stress, styles of stress coping(passive and active copings), self-perception, and gender accounted for 15.56% of the total variance in somatization tendency. As a result of comparing the relative contributions of all predictor variables to somatization tendency, the highest was perceived stress, and the next in order were passive coping style, self-perception, and gender, whereas direct effect of active coping style was not significant. 2) The two-way and three-way interaction effects of perceived stress X vulnerability variables were not significant. 3) The two-way and three-way interaction effects of gender X psychosocial variables were not significant. To conclude, perceived stress and vulnerability variables independently contribute to somatization tendency in university entrants, and furthermore it is suggested that vulnerability variables as well as perceived stress must be considered to account for somatization tendency.