• 대한기계학회논문집
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• 제19권2호
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• pp.402-407
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• 1995

The effects of room temperature and strain aging treatment are discussed on the critical condition for the onset of growth of non-propagating cracks on 0.15% C low carbon steel, with special emphasis on the length of the critical non-propagating crack and on the crack opening displacement(COD) at the crack tip. It is found from the experimental analysis that room temperature and strain aging of a fatigue pre-cracked specimen introduced the closure of a crack tip of the pre-crack and the reduction of crack opening displacement at the wake of crack, together with an improvement in crack growth resistance of the microstructure. This may cause an increase in the endurance limit of the specimen, through the enhancement of effective stress for the onset of growth of the critical non-propagating crack.

• 소성∙가공
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• 제8권3호
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• pp.294-305
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• 1999

A vision-based surface-strain measurement system has been still improved since the authors devel-oped the first version of it. New algorithms for the subpixel measurement and surface smoothing are introduced to improve the accuracy and precision in the present study. The effects of these algorithms are investigated by error analysis. And the equations required to calculate 3D surface-strain of a shell element are derived from the shape function of a linear solid finite-element. The influences of external factors on the measurement error are also examined, and several trials are made to obtain possible optimal condition which may minimize the error.

• 한국육종학회지
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• 제40권2호
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• pp.106-112
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• 2008

International conferences to block the spread of Avian bird flu occurred in Beijing, 2006 and others warned of the seriousness of the H5N1 strain. The meetings succeeded in generating billions of dollars from USA, EU and World Bank. Migratory birds seem to play a major role in the spread of the aggressive strain globally from Asia to Europe and Africa. Experiences of tolerance breeding of maize (Zea mays L.) for four decades against 20 biotic stresses suggest that the prime cause of the occurrence of H5N1 strain was due to the human beings' counter-efforts against nature. Excessive use of chemicals (spray and injection) in the commercial poultry farms had created high selection pressure on virus. The new strain had mutated for survival. Attempting to eliminate the virus by chemicals for 100% control is a dangerous way to control biotic stresses. This can create more aggressive strains. A solution would be to build up tolerability of the commercial animals against the virus. Improvement of poultry cage environments and respect for nature must be integrated. Potential foes must be watched.

• 한국가금학회지
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• 제17권1호
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• pp.7-15
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• 1990

본 연구는 재래형 유색계통계와 상업용 백색 산난계의 혈중 지질과 단백질 함양을 비교하기 위하여 재래형 유색계통계로서 황갈색계 10수, 녹흑색학 13수, 백색계 7수, 오골계 10수를, 개량형으로서 상업용 백색산난계(Nick chick) 30수를 선정하여 동일한 사료를 1개월 간 급이한 다음 혈청중 Cholesterol, triglyceride 및 protein 함양을 측정한 결과를 요약하면 다음과 같다. 1. 혈청 cholesterol 함양은 상업용 백색산난계 ($172.50\pm$13.45 mg/100 $m\ell$)에서 고도의 유의차(P＜0.01)를 보였고 유색계통보다는 백색계통계에서 다소 높았고 유색계통간은 비슷했다. 2. 혈청 triglyceride 함양은 재래형 유색계간에는 차이가 없으나 상업용 산난계에서 유의성을 나타냈다. (p＜0.01) 3. 혈청 protein 합양은 상업용 산란계에서 $6.24\pm$0.23 mg/100 $m\ell$으로서 재래형보다 유의하게 높게 나타났다. (p＜0.01) 이상과 같이 재내형 유색계통보다 상업용 산난계에서 혈중 지질과 protein 농도가 높은 것은 닭의 개량정도에 의한 차이로서 상업용 산란계는 섭취한 사료의 영양소 흡수율이 높았기 때문인 것으로 사료된다.

• 한국항공우주학회지
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• 제44권1호
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• pp.1-11
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• 2016

큰 가로세로비를 가지는 유연날개의 변형정보는 구조 건전성 평가를 위한 실시간 모니터링에 필요하다. 비행 중인 날개 구조 대변형은 날개 외피의 변형률과 곡률의 관계식을 기반으로 한 비선형 변위 예측 알고리즘을 통해 예측될 수 있다. 그러나 동체에 고정된 날개의 기하학적인 형상으로 인하여 고정단 부근에서의 변형률 분포는 복잡한 양상을 나타내며, 변형률 센서가 부착된 센싱라인의 코드방향 위치에 따라 변위가 다르게 예측될 수 있다. 본 논문에서는 스팬방향 변형률의 보정을 통하여 변형률 센싱라인의 코드방향 위치에 관계없이 예측변위의 정확도를 향상시키는 연구를 수행하였다. 변형률 보정을 위하여 스팬방향 및 코드방향 변형률의 비, 재료의 포아송비, 보와 평판 모델의 변형률 비를 이용하였다. 보정된 변형률을 이용하여 예측한 변위는 해석변위와 잘 일치하였으며, 이를 실험을 통하여 검증하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.312-315
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• 2002

This paper summarizes the results of a numerical study conducted to analyze the effect of selected process parameters on material flow and thread profile in thread rolling of large diameter blanks. Based on the previous work where a plane strain mode was found to provide a reasonable approximation of the thread rolling process, the effect of varying thread form, friction factor, flow stress, and blank diameter on effective strain and thread height was analyzed using the finite element code DEFORM. This study show that effective strain for flank angle, that blank diameter had important effect on the as-rolled thread while flow stress, friction factor, and crest round of dies had significant impact on effective strain at the thread root and crest and load of thread rolling. While the rate of strain harding was found to have an effect on the crest profile, the results indicate that it is the primary factor responsible for seam formation in rolled threads.

• 한국미생물·생명공학회지
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• 제23권4호
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• pp.461-471
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• 1995

The heterofermentative Leuconostoc mesenteroides, which is propagated from the initial to the intermediate stage of Kimchi fermentation, produces organic acids and carbon dioxide to impart refreshment, weak acid taste to Kimchi. But owing to lactic acid production by the homofermentative Lactobacillus Plantarum, Kimchi finally reaches its acidified state. So, Leu. mesenteroides was isolated from Kimchi and identified and was improved by mutation for carbon dioxide production at low pH, and for the high total acceptability. We tested with a wild-type strain K-1 and its improved mutant strain M-10 of Leu. mesenteroides. The wild-type strain K-1 could grow in pH 4.2 at 30$\circ$C or 20$\circ$C, and in pH 5.0 at 10$\circ$C. But the mutant strain M-10 could grow in pH 3.3 at 10$\circ$C. In the respect of total acceptability, mutant strain M-10 inoculated Kimchi was ever better than any others. Mutant M-10 inoculated Kimchi prolonged the optimum ripening period of Kimchi up to two times as compared with the control group.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.525-530
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• 2003

Recently an automobile industry is concerned about an automobile wiring harness system. It means that development of component modules is on the increase. An importance of the connector in one part of the modules will be enhanced. A connector is made of P.B.T. (Poly Butylene Terephthalate). PBT is resistant to the high temperature. This paper deals with thermal strain of connector. According as temperature increase, effects of the temperature and thermal strains give an analysis of the deformation using ABAQUS. This apparent thermal strain results actually from the variation of temperature. Being based on this analysis, axiomatic design applies to design parameters of the connector. As compared with CAE analysis, a performance improvement makes certain of the truth of the matter.

• 한국산학기술학회논문지
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• 제15권8호
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• pp.4784-4789
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• 2014

본 논문의 목적은 세척기를 구조 변경하여 새로운 세척기를 개발하는데 있다. 세척 성능을 향상시킨 세척기 개발을 위하여 기존의 세척기 구조를 변경하여 설계하였다. 설계 시 프로그램은 CATIA를 사용하였으며 구조해석에 필요한 모델링도 CATIA를 사용하였다. 또한 모델링된 세척기에 대하여 3차원 유한요소해석 프로그램인 ANSYS를 사용하여 구조해석을 실시하였으며 해석결과로서 총변형량, 응력, 변형률을 구하였다. 이러한 구조해석의 결과는 새로운 세척기의 제품개발에 활용되었다.

• 토지주택연구
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• 제2권1호
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• pp.79-85
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• 2011

지반의 지지력은 안정화, 다짐공법등 고전적인 지반개량공법에 의한 증대된다. 최근, 지지력을 향상시키기 위한 내구성이 있고 강성이 큰 토목섬유의 유용성때문에 지오텍스타일의 사용은 보편화되고 있다. 본 논문에서는 모래지반에 보강재를 수평으로 등간격 배치하여, 평면 변형률 상태의 실내모형실험을 실시하고 지지력의 개량효과와 거동을 분석하였다.