• 대한기계학회논문집A
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• 제29권10호
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• pp.1377-1383
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• 2005

A general and efficient methodology has been developed to analyze dimensional variations of an assembly, taking into account of weld distortion. Weld distortion is generally probabilistic because of the random nature of welding parameters such as the welding speed, maximum welding temperature, ambient temperature, etc. The methodology is illustrated through a very simple example of two perpendicular plates fillet-welded to each other. Two steps comprise the methodology: establishment of a weld-distortion database, and tolerance analysis using the database. To establish the database, thermo-elasto-plastic finite element analyses are conducted to compute the weld distortion for all combinations of discrete values of major welding parameters. In the second step of tolerance analysis, the weld distortion retrieved from the database is used in addition to the dimensional tolerances of the parts. As a result of such an analysis, sensitivities of the assembly's dimensional variations to the part tolerances and weld distortion are obtained, which can be help improve the dimensional quality of the assembly.

• 한국생산제조학회지
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• 제19권5호
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• pp.609-615
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• 2010

Angular contact ball bearings in a high speed spindles are under the extreme conditions, such as high temperature, big centrifugal force and thrust cutting forces. So, the assembly contacts between spindle shaft and inner ring bearings, bearing housing and outer ring of bearings are occasionally unstable at high speed revolution. Furthermore, the ball contact angle of a bearing, which influence stiffness and lifetime of bearings, are changed according to loads and rotational speed. To analyze internal forces of a bearing under high speed revolution, the ball contact are calculated using nonlinear equations in consideration of rotational speed, thrust loads and raceway form. Diameter increase of inner and outer ring by influence factors, such as internal forces to inner and outer ring, centrifugal force and temperature of inner and outer rings are calculated to establish stable state in bearing assembly in high speed spindle. Finally, contribution ratio of influence factor to assembly design tolerance of inner and outer rings are shown and the stable assembly design tolerance are proposed.

• 한국작물학회지
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• 제50권2호
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• pp.67-72
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• 2005

Overwintering capacity, closely related to winter hardiness, of Chinese milk vetch planted with different sowing times and sowing practices was investigated to improve the incorporation into cropping system in Korea. The tolerance to low temperature was evaluated with $LT_50$ using leaf disc leaching method. Dry weight of CMV was reduced remarkably with delayed planting from Sep. 5 to Oct. 20. The differences in tolerance to freezing temperature were not conspicuous among CMV genotypes, however, the differences between genotype (collections at different regions) were due to the plant architecture, mainly to the leaf angle. The crouching genotype collected at central region of Korean peninsula, which showed excellent freezing tolerant, has planophile leaves. The feature of internal constituents of CMV genotypes did not show any noticeable differences with respect to the freezing tolerance which evaluated by leaf disc leaching experiment. To overcome the poor overwintering capacity, tolerant genotype should be developed by selection with considering the plant architecture. The reduction of CMV growth during overwintering period was ameliorated with furrow-sowing under late-sown condition, therefore, when the CMV is inevitably sown late after recommended time, the seeds should be sown on furrow to overcome the cold stress.

• 한국의류학회지
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• 제21권4호
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• pp.669-676
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• 1997

The purpose of this study is to examine the effect of the improved cold tolerance resulting from cool clothing in winter on heat tolerance in summer. Ten healthy women were divided into two groups, cold group(C group) (n=5) and warm group(W group) (n=5) . In the previous study, C group was proved that their cold acclimatization was achieved through wearing cool clothing from September to February of the following year, while Wgroup was not proved because of wearing warm clothing during same period. After February, no more clothing training was continued in two groups. To determine the heat tolerance, both groups were exposed from a thermoneutral environment(25$\pm$1$^{\circ}C$, 50$\pm$5% R.H.) to a hot environment (35$\pm$1$^{\circ}C$, 50$\pm$5% R.H.) before and after clothing training, respectively September in 1994 and truly in 1995. Rectal temperature, skin temperatures, thermal sensation and comfort were measured every 10 min., and Os uptake was measured at 10, 45, 85 min. after entering the chamber for 5 min. Body weight was measured before and after the experiment and amount of local sweat was measured during the 90 min long experiment. The results are as follows: Rectal temperatures in 35'c environment of C group were increased after training when compared with before clothing, while those of W group were not changed. But the changes of rectal temperature and heat production during 90 min in hot environment were almost the same in two groups after training. And mean skin temperatures, the changes of mean skin temperatures during 90 min in hot environment, total sweat amount and local sweat amount after training were also the same in two groups. From these results, it might be supposed that the heat loss of two groups were the same but the heat production, especially heat production during rest in C group was higher than in Wgroup. This fact suggests that the increase of rest heat production from cold acclimatization in winter is maintained to summer of the following year. And mild cold acclimatization coming from westing cool clothing does not have a negative effect on heat tolerance.

• 원예과학기술지
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• 제32권2호
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• pp.241-251
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• 2014

본 연구는 남부 지방에서 널리 사용되고 있는 상록활엽수인 돈나무의 내한성 예측을 위한 편리하고 신뢰성 있는 평가 모델 개발을 목적으로 전해질 용출법을 통한 내한성 평가에서 나타나는 실험방법 상의 오차를 최소화하는 내한성 평가 모델을 도출하고자 수행되었다. 평가 모델링은 저온 처리된 식물체에 대한 재생검사와 전해질 용출 평가로 구성되었고, 전해질 용출법에서 표본조직 선택, 최대 전해질 용출 측정을 위한 온도 처리법, 치사 온도 예측을 위한 통계 분석법에 의한 방법적 조합들로부터 예측된 치사 온도들이 재생검사 결과와 비교되었다. 재생 검사 결과 돈나무의 저온 치사 온도는 50% 미만의 생존율을 보이는 최고온도인 $^-10{\circ}C{\sim}-5^{\circ}C$로 분석되었고, 이 결과를 바탕으로 전해질 용출법에 의해 예측된 저온 치사 온도를 분석한 결과, 잎을 표본 조직으로 하여 냉각치사법으로 최대 전해질 용출을 측정한 방법적 조합에서 재생 검사 결과와 가장 근접한 예측 저온 치사 온도가 나타났다. 저온 치사온도 예측을 위한 통계 모델 평가에서는 선형보간법이 비선형회귀에 비하여 내한성을 과대평가하는 경향이 상대적으로 높았다. 결론적으로 돈나무 내한성 예측을 위한 내한성 평가 모델은 잎을 표본 조직으로 사용하고, 최대 전해질 용출 측정을 위한 온도 처리 방법으로 냉각치사법을 적용하며, 치사온도 예측을 위한 통계 분석 기법으로 비선형회귀를 활용하는 방법적 구성이 가장 적합한 것으로 나타났다.

• 한국수산과학회지
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• 제33권3호
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• pp.213-218
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• 2000

전북 곰소만에 서식하는 바지락, Ruditapes philippinarum을 대상으로 $18{\circ}C$와 $25{\circ}C$에 순응시킨 후 수온상승 ($1{\circ}C/day, 2{\circ}C/day$ 및 $3{\circ}C/day$) 및 염분 ($32.0, 25.6, 19.2, 12.8, 6.40$ 및 $3.20{\%_{\circ}}$) 변화에 따른 생존율, 여수율 및 산소소비율 둥을 조사하였다. $18{\circ}C$와 $25^{\circ}C$에 순응시킨 바지락의 반수치사온도 (LT-(50))는 두 순응온도구간에 차이를 나타내지 않았으나, 최대 임계온도는 $18^{\circ}C$에 순응시킨 실험구는 $36^{\circ}C$, 그리고 $25^{\circ}C$에 순응시킨 실험구는 $37^{\circ}C$로 고수온에 순응시킨 실험구에서 높았다. 염분변화에 따른 바지락의 생존율은 $19.2{\%_{\circ}}$이하에서 감소하였다. 산소소비율은 $18^{\circ}C$에 순응시킨 바지락의 경우, 염분감소에 따라 감소한 반면 $25^{\circ}C$에 순응시킨 실험구에서는 산소소비율이 불규칙하였다. 한편, 수온증가에 따른 여수율은 $18{\circ}C$에 순응시킨 실험구의 경우 $24^{\circ}C{\~}28^{\circ}C에서$, $25{\circ}C$에 순응시킨 실험구의 경우는 $31{\~}33^{\circ}C$에서 최대를 보인 후 감소하였으며, 염분변화에 따른 여수율은 염분감소에 따라 감소하는 경향을 나타내었다.

• 한국산림과학회지
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• 제111권2호
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• pp.251-262
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• 2022

본 연구는 기후변화에 대응하여 남부지역에서 주로 재배되는 차나무 품종인 '참녹', '보향', '상녹', '명녹'을 대상으로 다수의 내한성 지표를 이용하여 신뢰성 있는 평가를 통해 내한성 차나무를 선발하고자 수행하였다. 저온 피해도 조사결과, -10℃에서 '참녹'과 '보향'은 청고 피해가 조사되었고, '상녹'과 '명녹'은 적고 피해가 조사되었다. 전해질 용출량은 처리 온도가 낮아질수록 그 값이 증가하였다. 비선형 회귀 분석을 통해 치사온도를 예측한 결과 '참녹'(-9.344℃), '보향'(-8.883℃)은 '명녹'(-8.092℃), '상녹'(-7.632℃) 보다 상대적으로 내한성이 강한 것으로 나타났다. Proline 분석 결과 '보향'은 다른 품종들에 비교하여 높게 조사되었고, 항산화 활성도 조사 결과 '참녹'과 '보향'이 저온 처리 시 다른 품종과 비교하여 항산화 활성 수치가 높게 나타났다. 지질과산화 반응 측정 결과 '상녹'과 '명녹'은 저온 처리시 다른 품종과 비교하여 MDA 축적 함량이 높았다. 본 연구 결과 '참녹'과 '보향'은 비선형 회귀 분석을 통해 치사온도를 예측한 결과와 저온피해도, 항산화 활성도, 지질과산화 반응과도 일관성 있게 조사되어 내한성이 강한 것으로 나타났다. 본 연구 결과는 기후변화에 대응한 차나무의 내한성 평가와 선발 뿐만 아니라 내한성 식물의 육성에도 활용될 수 있을 것으로 판단된다.

• 한국반도체및디스플레이장비학회:학술대회논문집
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• 한국반도체및디스플레이장비학회 2002년도 추계학술대회 발표 논문집
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• pp.59-63
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• 2002

This paper reports on the fabrication process and characteristics of a ceramic thin-film pressure sensor based on Ta-N strain-gauges for harsh environment applications. The Ta-N thin-film strain-gauges are sputter-deposited on a thermally oxidized micromachined Si diaphragms with buried cavities for overpressure tolerance. The proposed device takes advantage of the good mechanical properties of single-crystalline Si as a diaphragm fabricated by SDB and electrochemical etch-stop technology, and in order to extend the temperature range, it has relatively higher resistance, stability and gauge factor of Ta-N thin-films more than other gauges. The fabricated pressure sensor presents a low temperature coefficient of resistance, high-sensitivity, low non-linearity and excellent temperature stability. The sensitivity is 1.21 ~ 1.097 mV/V.kgf/$\textrm{cm}^2$ in temperature ranges of 25~ $200^{\circ}C$ and a maximum non-linearity is 0.43 %FS.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2022년도 추계학술대회
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• pp.283-283
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• 2022

Abiotic stresses such as high/low temperature, drought, salinity, and submergence directly or indirectly influence the physiological status and molecular mechanisms of rice which badly affect yield. Especially, the low temperature causes harmful influences in the overall process of rice growth such as uneven germination and the establishment of seedlings, which has become one of the main limiting factors affecting rice production in the world. It is of great significance to find the candidate genes controlling low-temperature tolerance during seed germination and study their functions for breeding new rice cultivars with immense low-temperature tolerance during seed germination. In this study, 120 lines of Cheongcheong/Nagdong double haploid population were used for quantitative trait locus analysis of low-temperature germinability. The results showed significant difference in germination under low different temperature conditions. In total, 4 QTLs were detected on chromosome 3, 6, and 8. A total of 41 genes were identified from all the 4 QTLs, among them, 25 genes were selected by gene function annotation and further screened through quantitative real time polymerase chain reaction. Based on gene function annotation and level of expression under low-temperature, our study suggested OsGPq3 gene as a candidate gene controlling viviparous germination, ABA and GA signaling under low-temperature. This study will provide a theoretical basis for marker-assisted breeding.

• 한국전기전자재료학회논문지
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• 제16권1호
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• pp.46-52
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• 2003

In this paper, we fabricated PRT(platinum resistance thermometers) with the trimming technology using high fine laser system. U. V.(wavelength： 355nm) laser was mainly used for adjusting Pt thin films resistors to 100Ω at 0$^{\circ}C$. Internationally, the accepted A-class tolerance of temperature sensor is ${\pm}$0.06Ω at 0$^{\circ}C$. according to DIN EN 60751. The width of trimmed lines was about 10$\mu\textrm{m}$ and the best trimming conditions of Pt thin films were power : 37mW, frequency : 200Hz and bite size：1.5$\mu\textrm{m}$. And 96 resistors, fabricated by photolithography and etching process, have 79∼90Ω and 91∼102Ω as the proportion of 45.7% and 57.3%, respectively. As result of sitting Pt thin films resistors to the target value(109.73Ω at 25$^{\circ}C$), 82.3% of all resistors had the tolerance within ${\pm}$0.03Ω and the others(17.7％) were within ${\pm}$0.06Ω of A-class tolerance. The PRTs which wore fabricated in this research had excellent characteristics as follows； high accuracy, international standard TCR(temperature coefficient of resistance) value, long-term stability, wide temperature range, good linearity and repeatability, rapid response time, etc.