• Nuclear Engineering and Technology
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• 제41권8호
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• pp.1109-1114
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• 2009

The evolution of a high burnup structure (HBS) in a light water reactor (LWR) $UO_2$ fuel was simulated using the Potts model. A simulation system for the Potts model was defined as a two-dimensional triangular lattice, for which the stored energy was calculated from both the irradiation damage of the $UO_2$ matrix and the formation of a grain boundary in the newly recrystallized small HBS grains. In the simulation, the evolution probability of the HBS is calculated by the system energy difference between before and after the Monte Carlo simulation step. The simulated local threshold burnup for the HBS formation was 62 MWd/kgU, consistent with the observed threshold burnup range of 60-80 MWd/kgU. The simulation revealed that the HBS was heterogeneously nucleated on the intergranular bubbles in the proximity of the threshold burnup and then additionally on the intragranular bubbles for a burnup above 86 MWd/kgU. In addition, the simulation carried out under a condition of no bubbles indicated that the bubbles played an important role in lowering the threshold burnup for the HBS formation, thereby enabling the HBS to be observed in the burnup range of conventional high burnup fuels.

• 한국진공학회지
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• 제17권6호
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• pp.523-527
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• 2008

GaAs/AlGaAs 물질계를 기반으로 한 양자폭포레이저를 제작하였다. 양자폭포레이저는 활성층의 위까지만 식각된 shallow mesa 구조와 활성층까지 식각된 deep mesa 구조로 제작되었다. shallow mesa 구조의 경우 문턱전류 밀도가 $26-32\;kA/cm^2$이었지만 deep mesa 구조의 경우 문턱전류 밀도는 $13\;kA/cm^2$로 대단히 감소되었다. Deep mesa 구조에서의 문턱전류 감소는 측면 방향으로의 전류 손실이 감소되었기 때문으로 설명되었다.

• Journal of Preventive Medicine and Public Health
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• 제46권1호
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• pp.19-27
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• 2013

Objectives: This study was conducted to investigate the relationship between heat-related illnesses developed in the summer of 2012 and temperature. Methods: The study analyzed data generated by a heat wave surveillance system operated by the Korea Centers for Disease Control and Prevention during the summer of 2012. The daily maximum temperature, average temperature, and maximum heat index were compared to identify the most suitable index for this study. A piecewise linear model was used to identify the threshold temperature and the relative risk (RR) above the threshold temperature according to patient characteristics and region. Results: The total number of patients during the 3 months was 975. Of the three temperature indicators, the daily maximum temperature showed the best goodness of fit with the model. The RR of the total patient incidence was 1.691 (1.641 to 1.743) per $1^{\circ}C$ after $31.2^{\circ}C$. The RR above the threshold temperature of women (1.822, 1.716 to 1.934) was greater than that of men (1.643, 1.587 to 1.701). The threshold temperature was the lowest in the age group of 20 to 64 ($30.4^{\circ}C$), and the RR was the highest in the ${\geq}65$ age group (1.863, 1.755 to 1.978). The threshold temperature of the provinces ($30.5^{\circ}C$) was lower than that of the metropolitan cities ($32.2^{\circ}C$). Metropolitan cities at higher latitudes had a greater RR than other cities at lower latitudes. Conclusions: The influences of temperature on heat-related illnesses vary according to gender, age, and region. A surveillance system and public health program should reflect these factors in their implementation.

• Journal of Preventive Medicine and Public Health
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• 제17권1호
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• pp.57-63
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• 1984

소음작업(騷音作業) 근로자(勤勞者)들의 이보호구장용(耳保護具裝用)의 여부(與否)에 따른 청력보존(聽力保存)의 효과(效果)를 관찰하기 위해 $16{\sim}24$세(歲)사이의 건강(健康)한 여성(女性) 기직공(機織工) 1,237명을 대상(對象)으로 이전(耳栓)을 장용(裝用)하고 있는 자(者)들을 실험군(實驗群), 하지 않고 있는 자(者)들을 대조군(對照群)으로 하고, 1982년(年) 4월에서 1983년(年) 1월(月)사이에 실시된 특수건강진단(特殊健康診斷) 결과지(結果紙)에서 그들의 근속년수(勤續年數), 4,000Hz에서 AA-30A, RION Japon청력계(聽力計)로 측정된 최소가청치(最小可聽値)를 조사 비교하였다. 최소가청치(最小可聽値) 40 dB초과의 경우는 대조군(對照群)의 좌이(左耳) 44.6% 우이(右耳) 40.9%, 실험군(實驗群)의 좌이(左耳) 8.0% 우이(右耳) 6.6%였고 근속년수(勤續年數)가 길수록 대조군(對照群)과 실험군(實驗群) 모두에서 증가(增加)하였다. 최소가청치(最小可聽値)의 분포(分布)는 좌우이(左右耳)사이에 유의한 차(差)를 실험군(實,驗群)과 대조군(對照群) 모두에서 볼 수 없었으나, 대조군(對照群)과 실험군(實驗群)간에는 좌우이(左右耳) 모두에서 통계적으로 유의한 차(差)를 나타내었다(p<0.005). 대조군(對照群)과 실험군(實驗群)사이에 최소가청치(最小可聽値) 40 dB초과에 속하는 경우의 차이(差異)는 근속년수(勤續年數) 1년이하, 3년, 5년, 5년 초과에 따라 각각 좌이(左耳) 26.8%, 38.0%, 43.3%, 45.4%, 우이(右耳) 29.5%, 31.6%, 38.9%, 36.5%로 증가(增加)하는 경향이었다.

• 터널과지하공간
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• 제5권1호
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• pp.22-40
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• 1995

Thermomechanical characteristics of rocks such as thermal shock, thermal expansion, thermal cracking were experimentally investigaed using Iksan granite, Cheonan tonalite and Chung-ju dolomite to obtain the basic data for proper design and Chung-ju dolomite to obtain the basic data for proper design and stability analysis of underground structures subjected to temperature changes. The effect of thermal shock did not appear when the heating speed was under 3$^{\circ}C$/min. and there existed little difference between multi-staged cyclic heating and single-cycled heating. Thermal expansion of rocks was affected by mineral composition, crack porosity and the degree of thermal craking. In quartz-beraring multimineralic rocks such as Iksan granite and Cheonan tonalite, the thermal expansion coefficient increaseed continuously with temperature rise, but that of Chung-ju dolomite which was a monomineralic rock showed a constant value for the temperature above 250$^{\circ}C$, Chung-ju dolomite yielded the lowest critical threshold temperature(Tc) of 100$^{\circ}C$ and unstable thermal cracking was initiated above the new threshold temperature(Tc')of 300$^{\circ}C$. Above Tc' thermal cracks grew but they were not interconnected. Iksan granite showed closing of microcracks to the temperature of 100$^{\circ}C$, then expanded linearly to Tc of 200$^{\circ}C$. Above Tc, thermal cracking was initiated and progressed rapidly and almost all the grain boundaries were cracked at 600$^{\circ}C$. Cheonan tonalite also showed similar behavior to iksan granite except that Tc was 350$^{\circ}C$ and that thermal cracks propagated more rapidly. Thermal expansions calculated by Turner's equation were found to be valid in predicting the thermal expansion and cracking behavior of rocks.

• 디지털콘텐츠학회 논문지
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• 제19권4호
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• pp.615-620
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• 2018

당뇨병성 다발성 신경병증 환자들을 진단하는 전류지각 역치 시험과 진동 감각 지각 역치의 임상학적 유용성에 대한 평가는 당뇨병성 다발성 신경병증에 대한 진단방법 중의 하나이다. 현재까지 당뇨병성 다발성 신경병증 환자들에 대해 몇 가지 방법들이 사용되어 왔는데, 예를 들면, 하지 신경병증 장애 시험, 신경전도 시험, 냉각감지 역치 시험, 열-고통 역치 시험 등을 들 수 있다. 그러나, 이들 대부분의 시험은 고가이거나 시험하는데 많은 시간을 필요로 한다. 본 논문에서는 진동 감지 능력을 평가하는 새로운 기구가 소개되고, 이를 위해 환자의 말초 신경을 자극하는 보이스 코일 모터(voice coil motor)와 전류 증폭기를 제작하였다. 또한, 당뇨병성 다발성 신경병증 환자들의 정량적 진동 감지 수준을 측정하기 위하여 진동 감지 역치 시험을 센싱하고 구동하는 소프트웨어가 개발되었다.

• 한국가스학회지
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• 제21권4호
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• pp.6-15
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• 2017

화학사고의 발생을 감소시키고, 예방하기 위한 공정안전관리(PSM) 제도는 우리나라의 경우 1996년부터 시행되었다. 그러나 PSM 제출대상인 기존 21종 물질에 대한 규정량과 새로이 추가된 브롬화수소 등의 독성물질의 규정량에 대한 타당성 검토가 미흡하여 많은 문제점이 발생되고 있다. 본 연구에서는 25종의 PSM 제출대상독성물질의 규정량을 국내 외 공정안전관리제도와 관련된 규정량과 비교 검토하였다. 그리고 흡입독성, NFPA 지수 등으로 구성된 독성 유해 위험성 식을 제안하여 고위험, 중위험, 저위험의 3등급으로 독성물질을 분류하고, 규정량의 조정에 반영하였다. 본 연구결과의 규정량 개선안은 유사 공정안전관리제도의 규정량 차이로 인한 사업장의 혼란과 부담 완화 및 합리적 개선에 도움을 줄 것으로 기대된다.

• 한국표면공학회지
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• 제50권5호
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• pp.405-410
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• 2017

In order to study current-voltage-luminance and impedance characteristics according to elapsed time, a blue fluorescent OLED was fabricated. The current density and luminance gradually decreased in accordance with elapsed time and did not emit light after 480 hours, and the threshold voltage increased as time elapsed. The Cole-Cole plot was a semicircular shape of a very large size at 2 V of the applied voltage below the threshold voltage, and the maximum value of the real number impedance did not change greatly from 9314.5 to $9902.2{\Omega}$ as time elapsed. Applied voltages 4, 6, and 8 V above the threshold voltage showed a large change in the real number impedance value at the semicircle end to 9,678.2, 9,826, $9,535.4{\Omega}$ according to the elapsed time from 2,222.5, 183.7, $48.2{\Omega}$ immediately after fabricating the device. By increasing the applied voltage beyond the threshold voltage just after device fabrication, the energy difference between the device and the organic layer was overcome and the current flowed, the maximum value of the real number impedance sharply decreased. As time passed, current did not flow through the element even at high applied voltage due to degradation of the element, and even when the applied voltage was higher than the threshold voltage, it showed an impedance value such as applied voltage equal to or less than the threshold voltage. As a result, it can be learned that the change in the impedance with elapsed time reflects the characteristics due to the degradation of the OLED and can predict the characteristics and lifetime of the OLED.

• 한국광학회:학술대회논문집
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• 한국광학회 2005년도 제16회 정기총회 및 동계학술발표회
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• pp.216-217
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• 2005

• Genomics & Informatics
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• 제1권1호
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• pp.25-31
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• 2003

Local alignment is an important task in molecular biology to see if two sequences contain regions that are similar. The most popular approach to local alignment is the use of dynamic programming due to Smith and Waterman, but the alignment reported by the Smith-Waterman algorithm has some undesirable properties. The recent approach to fix these problems is to use the notion of normalized scores for local alignments by Arslan, Egecioglu and Pevzner. In this paper we consider the problem of finding all local alignments whose normalized scores are above a given threshold, and present a fast heuristic algorithm. Our algorithm is 180-330 times faster than Arslan et al.'s for sequences of length about 120 kbp and about 40-50 times faster for sequences of length about 30 kbp.