• 한국산학기술학회논문지
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• 제20권9호
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• pp.405-411
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• 2019

본 연구에서는 구조 및 압력용기용 소재 A516-60, A283-C, A285-C, SB410 에 대하여 상온 $20^{\circ}C$ 대비 저온영역, $-20^{\circ}C$와 $-40^{\circ}C$에서 인장시험을 수행하고 기계적 물성변화를 정리 및 분석하였다. 결과를 분석하면, A516-60의 경우, 상온 $20^{\circ}C$에서 저온 $-20^{\circ}C$ 및 $-40^{\circ}C$로 진입 시 평균 항복응력은 각각 6.4 % 및 7.5 % 증가하였고 평균 인장응력은 1.3 % 및 4.1 % 증가하였다. 반면, 평균 연신율은 상온상태 대비 각각 4.7% 및 20.4 % 감소하였다. A283-C의 경우, 평균 항복응력은 각각 8.8 % 및 9.8 % 증가함을 보였고 평균 인장응력 또한 각각 4.1 % 및 5.9 % 증가하였으나, 평균 연신율은 각각 7.4 % 및 9.9 % 감소하였다. A285-C 또한 평균 항복응력은 각각 1.8 % 및 8.6 % 증가하였고 평균 인장응력 또한 각각 2.6 % 및 5.3 % 증가하였으나 평균 연신율의 경우 거의 변화가 없는 것으로 나타났다. 마지막으로 SB410의 경우, 평균 항복응력은 각각 7.1 % 및 11.8 % 증가하였고 평균 인장응력은 각각 4.3 % 및 5.5 % 증가하였으나 평균 연신율은 각각 8.7 % 및 13.5 % 감소를 보였다. 한편, 저온 $-40^{\circ}C$로 진입 시, A516-60과 SB410의 평균 연신율은 상온상태 대비 각각 20.4 % 및 13.5 %의 급격한 감소를 보였으며 $-20^{\circ}C$에서 $-40^{\circ}C$ 로 온도 저하 시, 취성이 급격히 증가하는 것으로 사료된다.

• 한국산학기술학회논문지
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• 제17권1호
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• pp.374-388
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• 2016

본 제주도 산악관광도로를 대표하는 교통사고가 잦은 지방도 1100도로, 516도로, 비자림로를 중심으로 교통사고를 유형별로 구분하여 사고특성을 분석하고, 통행 AHP 분석을 통해 주요 사고요인을 분석하고 지점속도의 분포와 교통사고에 영향을 미치는 요인들을 비교 분석하였다. 도로특성상 관광객이 통행이 많고, 렌트카의 혼합율이 1100도로 및 비자림로는 36.70%~71.60%로 분석되었으며, 현재 조사대상 지방도는 60km/h의 제한속도로 규제하고 있으나, 도로선형 및 기후, 경관 등의 운전자 시거를 고려할 경우 제한속도를 40km/h로 규제할 필요성이 있으며, 조사대상 지방도의 40km/h이상 과속비율이 516도로는 87.0%, 1100도로는 88.57%, 비자림로는 93.1%로 분석되어 과속의 비율이 높은 것으로 분석되었으며, 과속에 따른 사고위험에 노출되어 있는 것으로 분석되었다. 516도로, 1100도로, 비자림로의 과속비율이 87.0%~93.1%로 무인과속단속시스템은 한 지점의 속도만으로 과속을 단속하는 시스템으로 단속지점에서만 속도를 줄이는 캥거루효과가 발생하고 있어 연속적인 속도감소 효과를 기대할 수 없다. 따라서 제주도의 도로특성상 연속적인 위험이 존재하는 도로구간에서는 교통사고 예방을 위해서는 위험구간의 평균속도로 과속차량을 단속하는 무인구간속도 위반단속시스템 도입이 필요하다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2000년도 추계학술대회 논문집
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• pp.240-245
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• 2000

Fatigue crack propagation rates and characteristics of the SA516-60 steel which is used for the low temperature pressure vessels, were studied in the room temperature of $25^{\circ}C$ and low temperature ranges of $10^{\circ}C,\; -10^{\circ}C,\; -30^{\circ}C,\; -50^{\circ}C, \;and\; -70^{\circ}C4 with stress ratio of R=0.05. The obtained experimental results are as follows; 1) In the logarithmic relationship between the fatigue crack propagation rate(da/dN) and stress intensity factor K, the linear relationship was obtained up to da/dN 〉$8\times10^{-3}$/mm/cycle in the same of room temperature, but in low temperature case, the relationship was extended to the range of crack propagation rate. 2) The lower limit stress intensity factor of SA516-60 $\DeltaK_{th}$ was 15.8MPa and in the case of low temperature $-50^{\circ}C\; and\; -70^{\circ}C$, the crack propagation rate da/dN which showed a linear relation, reached rapidly to the $\DeltaK_{th}$/. As the results, the crack propagation rates of $-50^{\circ}C\; and\; -70^{\circ}C$ were lower than that of room temperature and according to the testing temperature the rates were decreased rapidly to the $\DeltaK_{th}$/. 3) On the relationship between the stress intensity factor $\DeltaK$ and the crack propagation cycle, the stress intensity factors of low cycle region was rapidly increased at low temperature, but $\DeltaK$ was increased rapidly at room temperature of high cycle. 4) On the relationship between the fatigue crack propagation rate and cycle, the fatigue crack propagation rate showed higher gradient in the room temperature than the low temperature due to the increment in ductility at low temperature.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2013년도 추계학술발표대회
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• pp.516-519
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• 2013

최근 에너지 소비가 급증함에 따라 오피스 건물에 주광을 유입하여 조명에너지를 절감하는 연구가 진행중이다. 그러나 직접적인 주광유입은 작업환경의 조도분포를 불균일하게 만들어 빛의 품질을 떨어 뜨리고 업무효율을 저하시킨다. 이에 본 논문은 창측에 주광을 조절할 수 있는 베네시안 블라인드를 설치하여 블라인드의 슬랫 각도(Open, $-60^{\circ}$, $-30^{\circ}$, $0^{\circ}$, $+30^{\circ}$, $+60^{\circ}$)에 따라 실내로 유입되는 주광의 조도 및 균제도를 비교 분석하고, 작업환경의 조도분포가 가장 균일한 슬랫 각도로 블라인드를 제어한다. 이때 블라인드의 슬랫 각도별로 목표조도에 부합하기 위해 LED가 소모하는 누적 전력량을 산출한다. 슬랫 각도별로 산출된 균제도, 전력량을 기준으로 성능평가를 실시하여 성능이 우수한 슬랫 각도를 확인한다.

• 동력기계공학회지
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• 제4권4호
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• pp.41-47
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• 2000

Fatigue crack propagation rate and threshold characteristics of the SA516/70 steel which is used for the low temperature pressure vessels, were studied in the room temperature of $25^{\circ}C$ and low temperature ranges of $-10^{\circ}C,\;-30^{\circ}C,\;-60^{\circ}C\;and\;-80^{\circ}C$ with stress ratio of R=0.1. In the logarithmic relationship between the fatigue crack propagation rate($d{\alpha}/dN$) and stress intensity factor range ${\Delta}K$, the linear relationship was obtained up to $d{\alpha}/dN=4.425{\times}10^4mm/cycle$ in the same of room temperature, but in low temperature case, the relationship was extended to the range of low crack propagation rate. The fractured specimens were examined by SEM. Tested results showed that specimen failed at low temperature exhibit the quasi-cleavage fracture formation however considerable ductility proceed final fracture.

• Journal of Advanced Marine Engineering and Technology
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• 제25권6호
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• pp.1228-1236
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• 2001

In this study, CT specimens were prepared from ASTH A5l6 steel which was used for pressure vessel plates for moderate and lower temperature service. And we got the fellowing characteristics from fatigue crack growth test carried out in the environment of room and low temperature at $25^{\circ}C$ , $-30^{\circ}C$, $-60^{\circ}C$, $-80^{\circ}C$, $-100^{\circ}C$ and $-120^{\circ}C$ and in the range of stress ratio of 0.1, 0.3 by means of opening mode displacement. At the constant stress ratio, the Threshold stress intensity factor range ΔAKth in the early stage of fatigue crack growth (Region I) and stress intensity factor range $\DeltaK$ in the stable of fatigue crack growth (Region II) was increased in proportion to descend temperature. It assumed that the fatigue resistance characteristics and fracture strength at low temperature is considerable higher than that of room temperature in the early stage and stable of fatigue crack growth region. The straight line slope relation of logarithm da/dN-$\Delta$K in Region II that is, the fatigue clack growth exponent m increased with descending temperature at the constant stress ratio. It assumed that the fatigue crack growth rate da/dN is rapid in proportion to descend temperature in Region II and the cryogenic-brittleness greatly affect a material with decreasing temperature.

• 한국전자파학회논문지
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• 제22권5호
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• pp.516-521
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• 2011

본 논문에서는 5 GHz WLAN 대역 저지를 위한 슬롯과 접지면에 굴곡이 있는 역삼각형 모노폴 UWB 안테나를 제안하였다. 제안된 안테나는 CPW 형태로 급전하였으며, 패치면과 접지면 사이에 3개의 각을 이용하여 모노폴 안테나의 대역폭을 확장시켜 3.1～10.6 GHz에서 약 -10 dB 이하의 반사 손실을 만족시켰다. 제작된 안테나는 비유전율 6.15, 두께 0.64 mm인 Taconic사의 RF-60A 기판을 사용하였으며, 안테나 패치의 크기는 36 mm${\times}$19.5 mm이다. 측정 결과, WLAN 대역을 제외한 UWB 시스템 전 대역에서 약 -10 dB 이하의 반사 손실과 전방향성에 근접한 복사 패턴의 특성을 나타내었다. 제안된 안테나는 접지면의 굴곡각을 이용하여 주파수 대역에 따라 임피던스를 조절하기 용이하다는 이점이 있으며, 비교적 간단한 형태의 슬롯을 삽입하여 대역 저지 특성을 나타낼 수 있다.

• Journal of Power Electronics
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• 제18권2호
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• pp.640-650
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• 2018

A TRIAC dimmable LED driver with a wide tuning range and a two-stage uniform dimming scheme is proposed in this paper. To solve the restricted dimming range problem caused by the limited conduction ratio of TRIAC dimmers, a conduction ratio compensation technique is introduced, which can increase the output current up to the rated output current when the TRIAC dimmer turns to the maximum conduction ratio. For further optimization, a two-stage uniform dimming diagram with a rapid dimming curve and a slow dimming curve is designed to make the LED driver regulated visually uniform in the whole adjustable range of the TRIAC dimmer. The proposed control chip is fabricated in a TSMC $0.35{\mu}m$ 5V/650V CMOS/LDMOS process, and verified on a 21V/500mA circuit prototype. The test results show that, in the 90V/60Hz~132V/60Hz ac input range, the voltage linear regulation is 2.6%, the power factor is 99.5% and the efficiency is 83%. Moreover, in the dimming mode, the dimming rate is less than 1% when the maximum dimming current is 516mA and the minimum dimming current is only about 5mA.

• 전기학회논문지
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• 제60권3호
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• pp.509-516
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• 2011

This paper studies a novel method to find the profit-maximizing Nash Equilibriums in allocating generation quantities with consideration of ramp-rates under competitive market environment. Each GenCo in a market participates in a game to maximize its profit through competitions and play a game with bidding strategies. In order to find the Nash equilibriums it is necessary to search the feasible combinations of GenCos' strategies which satisfy every participant's profit and no one wants various constraints. During the procedure to find Nash equilibriums, the payoff matrix can be simplified as eliminating the dominated strategies. in each time interval. Because of the ramp-rate, generator's physically or technically limits to increase or decrease outputs in its range, it can restrict the number of bidding strategies of each generator at the next stage. So in this paper, we found the Nash Equilibriums for multi-stage generation allocation game considering the ramp-rate limits of generators. In the case studies, we analyzed the generation allocation game for a 12-hour multi-stage and compared it with the results of dynamic economic dispatch. Both of the two cases were considered generator's ramp-rate effects.

• 한국축산식품학회지
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• 제36권4호
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• pp.516-522
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• 2016

Goat milk is highly nutritious and is consumed in many countries, but the development of functional foods from goat milk has been slow compared to that for other types of milk. The aim of this study was to develop a goat milk protein hydrolysate (GMPH) with enhanced digestibility and better hypoallergenic properties in comparison with other protein sources such as ovalbumin and soy protein. Goat milk protein was digested with four commercial food-grade proteases (separately) under various conditions to achieve the best hydrolysis of α_s -casein and β-lactoglobulin. It was shown that treatment with alcalase (0.4%, 60℃ for 30 min) effectively degraded these two proteins, as determined by SDS-PAGE, measurement of nonprotein nitrogen content, and reverse-phase high-performance liquid chromatography. Hydrolysis with alcalase resulted in a significant decrease in β-lactoglobulin concentration (almost to nil) and a ~40% reduction in the level of α_s-casein. Quantification of histamine and TNF-α released from HMC-1 cells (human mast cell line) showed that the GMPH did not induce an allergic response when compared to the control. Hence, the GMPH may be useful for development of novel foods for infants, the elderly, and convalescent patients, to replace cow milk.