• Journal of Korean Vacuum Science & Technology
• /
• 제6권1호
• /
• pp.43-45
• /
• 2002

We have theoretically investigated steady-state carrier transport and current self-oscillation in negative-effective-mass (NEM) p$\^$+/pp$\^$+/diodes. The current self-oscillation here is a result of the formation and traveling of electric field domains in the p base having a NEM. The dependence of self-oscillating frequency on the applied dc voltage is obtained by detailed numerical simulations. In the calculations, we have considered the scatterings by carrier-impurity, carrier-acoustic phonon, carrier-polar-phonon, and carrier-nonpolar-phonon-hole interactions . This kind of NEM oscillator allows us to reach a current oscillation with terahertz frequency, thus it may be used as a broadband source of terahertz radiation.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
• /
• pp.239-242
• /
• 2008

We have investigated the reliability of short channel ($L=1.5{\mu}m$) p-type ELA poly-Si TFTs under hot carrier stress. Threshold voltage of short channel TFT was significantly more shifted to positive direction than that of long channel TFT under the same stress. This result may be attributed to electron trapping at the interface between poly-Si film and gate oxide layer.

• 한국전기전자재료학회논문지
• /
• 제19권3호
• /
• pp.216-221
• /
• 2006

Lifetime control technique by proton implantation has become an useful tool for production of modern power devices. In this work, punch-through type diodes were irradiated with protons for the high speed power diode fabrication. Proton irradiation which was capable of controlling carrier's lifetime locally was carried out at the various energy and dose conditions. Characterization of the device was performed by current-voltage, capacitance-voltage and reverse recovery time measurement. We obtained enhanced reverse recovery time characteristics which was about $45\;\%$ of original device reverse recovery time and about $73\;\%$ of electron irradiated device reverse recovery time. The measurement results showed that proton irradiation technique was able to effectively reduce minority carrier lifetime without degrading the other characteristics.

• 한국해양공학회:학술대회논문집
• /
• 한국해양공학회 2001년도 춘계학술대회 논문집
• /
• pp.295-300
• /
• 2001

The progressive die performs a series of fundamental sheet metal working, particularly this study regards to develop the center carrier feeding type die for thick sheet metal(SS41, 2.5mm) production that is a specific division. In order to prevent defect on the production, the analysis of production part, optimum design of strip process layout, die design and die making and tryout etc. are necessary. In this study, we designed and predicted a progressive die of multi stages by wide collected data base and computer aided method.

• 대한조선학회논문집
• /
• 제46권2호
• /
• pp.148-154
• /
• 2009

Type A LPG Carrier is the ship using the low temperature independent cargo tank separate from the hull, which has various support structures for laying independent tanks on the hull. In this paper, the direct strength analysis for the support structures has been performed through the direct load analysis, load transfer, stress analysis and strength assessment. Also, a rational modeling method of support structures has been proposed to obtain the dynamic load between the hull and the separate tank.

• Journal of Animal Science and Technology
• /
• 제46권6호
• /
• pp.925-936
• /
• 2004

본 연구는 낙농가의 소득과 직결된 원유 품질과 관계가 깊은 체세포 수(Somatic Cell Count, SCC)과 주요 우유 성분에 대하여 영향을 미치는 여러 요인 즉 아비 종모우, BLV type의 감수성 여부, 산차, 분만 월, 비유기 등에 대한 효과를 구명하였다. 조사기간은 2001년 1월부터 2004년 3월까지 분만한 홀스타인 젖소로부터 30$\pm$5일의 간격으로 시료를 채취하였으며, 우유성분과 체세포 분석은 Somascope MK2와 Lactoscope FTIR을 이용하여 총 3,897 개의 기록을 분석하였다. 비유기는 비유초기(30일 미만), 최고 비유기(30~60), 비유 중기(60~120), 비유 후기(120~180), 비유 말기(180일 이후)로 편의상 구분하였다. 분석 결과 대부분의 요인들이 모든 비유기에 걸쳐 유의적인 것으로 나타났으나 BLV type은 비유기에 따라서 차이를 나타내었다. 특히, BLV 감수성 여부는 조기에 검사를 통하여 보유 인자를 제거시키는 것이 장기적으로는 축군의 유질의 개선에 도움이 될 것으로 기대된다. 단백질에 대하여 BLV type은 각 비유기에 영향을 미치지 않았으며, 산차는 30일 이상에서 영향을 미쳤고, 분만월은 전 유기에 걸쳐 영향을 미치는 것으로 나타났다. 기타 유성분도 비유기에 따라서 각 각 다른 영향을 받는 것으로 나타났다.

• 한국의류산업학회지
• /
• 제19권4호
• /
• pp.504-514
• /
• 2017

Discomfort as well as muscular pain and musculoskeletal diseases occur in cases of stressed posture due to prolonged pressure. Therefore, the American Academy of Orthopaedic Surgeons (AAOS) and Pediatric Orthopaedic Society of North America (POSNA) recommend that bags that weigh no more than 15 - 20% of the wearer's weight. However, despite the prolonged pressure from using baby carriers, there are no recommendations and limited studies on how to protect wearers. Therefore, this study investigates subjective fatigue according to the usage of waist support and hip seat. Based on this, muscle fatigue and secondary subjective fatigue according to three types of currently commercial baby carriers (X-type, H-type, and H-hip type) were measured. Subjective comfortability was evaluated on a 5 point Likert-scale and subjective fatigue was evaluated on Borg's CR-10 scale. Objective muscle fatigue was also compared by measuring and analyzing electromyogram (EMG). The results of primary subjective fatigue showed statistically significant changes in the shoulders, waist, calves, and soles of the feet according to the usage of hip seats and waist support. Electromyogram measurements also showed less muscle fatigue at the upper trapezius muscle and thoracic erector spine muscle for the H-hip seat baby carrier, which has both waist support and hip seat, compared to an X-type baby carrier, which has neither. However, results of subjective fatigue showed opposite results at the waist despite having same results at the shoulders and beneath the shoulders. This show discrepancies between objective muscle fatigue and subjective fatigue; therefore, that both aspects must be taken into consideration when developing ergonomic baby carriers.

• 한국수소및신에너지학회논문집
• /
• 제20권2호
• /
• pp.151-160
• /
• 2009

Natural gas combustion characteristics of mass produced oxygen carrier particles were investigated in a batch type bubbling fluidized bed reactor. Five particles, NiO/bentonite, OCN601-650, OCN702-1100, OCN703-950, OCN703-1100 were used as oxygen carrier particles. Natural gas and air were used as reactants for reduction and oxidation, respectively. During reduction reaction, high fuel conversion and high $CO_2$ selectivity were achieved for most of oxygen carriers. During oxidation, NO emission was very low. These results indicate that inherent $CO_2$ separation and low NOx combustion are feasible for the natural gas fueled chemical-looping combustion system. Among the five oxygen carriers, OCN703-1100 particle was selected as the best candidate for demonstration of long-term operation in large-scale chemical-looping combustor from the viewpoints of fuel conversion, $CO_2$ selectivity, $CH_4$ concentration, and CO concentration.

• 한국항해항만학회:학술대회논문집
• /
• 한국항해항만학회 2006년도 춘계학술대회 및 창립 30주년 심포지엄(논문집)
• /
• pp.367-372
• /
• 2006

본 연구의 목적은 기존의 컨테이너터미널 이송차량의 기술대안을 분석하여 터미널 생산성을 높일 수 있는 새로운 이송차량 대안을 개발하는 것이다. 대안 개발을 위해 YT(Yard Trailer), S/C(Straddle Carrier), SHC(Shuttle Carrier), AGV(Automated Guided Vehicle) 등의 이송차량에 대한 기술적 사양을 분석하며, 이송차량의 기술단계별 세대를 분류하기 위하여 운영과 성능을 조사한다. 본 연구에서 제시하는 이송차량의 개발 대안은 향후 고생산성의 진보된 컨테이너 터미널에 유용 할 것이다.

• 한국인쇄학회지
• /
• 제8권1호
• /
• pp.1-20
• /
• 1990

$\alpha$,$\beta$,$\varepsilon$ type copper phthalocy $\alpha$,$\beta$,$\varepsilon$ type copper phthalocyanine(CuPc) pigment was purified by a simple train sublimation technique. The layered photoconductor was made with $\varepsilon$ type CuPc as a carrier generation layer(CGL) and polyvinly carvazol(PVCz) as a carrier transport layer(CLT). A CGL of CuPc was electrochemical deposited on an Al substrate used as cathode in pigment dispersion solutions. a CTL of PVCz pwas spin coated on $\varepsilon$ type CuPc thin film by a spin coater. The effect of sonication time, electrophotographic property of the layered photoconductor were studied with surface coverage, surface potential and sensitivity.