• 한국유체기계학회 논문집
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• 제14권4호
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• pp.38-44
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• 2011

This paper deals with the detail rotordynamic analysis for BB5 eight stages pump as development of API 610 BB5 type pump. Dry-run analytical model, not considering operating fluid, and wet-run analytical model, considering operating fluid are established. In addition, plain circular and pressure dam bearings are chosen and it was discussed that each bearing has an effect on dynamic characteristics of pump rotor system. A rotordynamic analysis includes the critical speed map, Campbell diagram, stability, and unbalance response. As results, it was predicted that rated speed of the pump rotor passes through 1st critical speed in dry-run condition regardless of bearings, however, it was verified that, in wet-run condition, the rotor system doesn't have critical speeds even if more than twice rated speed. Hence the resonance problem caused by the critical speeds does not happen since actual operating is in wet-run condition including operating fluid. As a result of unbalance response analysis, the pump rotor has stable vibration response at rated speed, regardless of operating fluid and the proposed bearing types.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.1231-1234
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• 2005

For the purpose of objective and scientific inspection, traffic accidents should be appraised and inspected by righteous material evidences, computer simulation, and studies such as automobile engineering, traveling and collision accident dynamics, road and traffic engineering. In this paper, it displays the results of studying cases with the reasons of traffic accidents by analyzing and studying automobile kinetics, real traffic accidents and the results of in scientific and objective ways. In this paper, it is proved that with compared by dry and wet road surface condition, the transient brake time of wet condition is longer than dry road condition. Moreover, compared with unpacked road condition and packed road condition. unpacked road condition is shorter than packed road condition using computer simulation.

• 한국식품영양학회지
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• 제28권6호
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• pp.1065-1070
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• 2015

초다수성 가공용 품종인 보람찬 및 한마음 품종의 수분 함량, 수분결합도, 아밀로오즈 함량, 손상전분, 입도 분포 및 호화특성을 분석하였다. 국내 초다수성 품종의 습식 및 건식분쇄에 의한 쌀가루의 수분 함량은 보람찬 및 한마음의 경우, 각각 14.79, 13.56 및 7.98, 7.14%를 나타냈다. 수분결합도의 경우, 보람찬 및 한마음 시료는 습식과 건식분쇄에 의해서 각각 236.67, 231.35% 및 275.83, 279.73%를 나타내어 건식분쇄에 의해 수분결합도가 증가하는 것으로 확인되었다. 습식분쇄된 초다수성 쌀가루의 수분결합력은 대조구로 사용된 일반미의 수분결합력과 비교 시 낮게 나타나는 것으로 확인되었다. 건식분쇄에 의한 호품, 보람찬 및 한마음 품종의 아밀로오즈 함량은 각각 19.12, 19.55 및 19.59%를 나타내었다. 손상전분의 경우, 보람찬 및 한마음 시료의 경우 습식과 건식분쇄에 의해 12.51, 10.69 및 14.98, 15.22%를 나타내어 습식분쇄에 비해 건식분쇄했을 경우 전분손상도가 증가하는 것으로 확인되었다. 또한 습식분쇄된 초다수성 쌀가루의 손상전분은 대조구에 비해 낮게 나타났으나, 건식분쇄 시에는 손상전분 함량이 대조구에 비해 증가하는 것으로 확인되었다. 국내 초다수성 품종의 분쇄방법에 따른 입도 분포의 경우, 최빈값은 습식에 비해 건식으로 분쇄할 경우 입도가 높은 것으로 나타났다. 초다수성 품종인 보람찬, 한마음을 습식 및 건식분쇄한 쌀가루의 최고 점도는 각각 2,300, 2,319 및 3,352, 3,022 cP를 나타내었다. 최고점도 및 최종점도의 경우 습식분쇄한 초다수성 쌀가루 시료는 대조구에 비해 높은 값을 나타내었다. Setback의 경우, 초다수성 품종 중 건식분쇄한 보람찬 쌀가루의 경우 가장 낮은 값을 나타내었으나, 대조구와 비교했을 경우 초다수성 쌀가루의 setback 값은 대조구에 비해 높은 값을 나타내었다.

• 한국안전학회지
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• 제28권3호
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• pp.33-38
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• 2013

Many occupational workers or professionals have to walk on the various floors for a long period of time. The objective of this study was to develop the safety shoes with increased traction through the material selection. In order to fulfill our objective, first, two kinds of filler were selected to compare the wear mechanism at outsole surface. The developed rubber materials were tested with two kinds of portable slip meters. The sample safety shoes with developed rubber materials were also tested with subject in the laboratory. During walking, the safety shoes were naturally abraded with counter surface. The coefficient of friction(COF) was gradually decreased with number of steps to 30,000, while the COF was abruptly increased from 30,000 to 40,000. The experimental results showed that COF tested with silica rubber was at least 10% higher than that with carbon black rubber in wet or detergent condition. It has been well recognized that filler properties play a important role in wet traction in the tire industry. However it has been unclear that filler properties would be decisive factor in safety shoes. Our study shows that silica exhibits a higher slip resistance than carbon black without reference to wear states in wet or detergent condition. So, this results will provide guides for outsole compounders to develop new products and improve product performance.

• 구강회복응용과학지
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• 제26권3호
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• pp.265-271
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• 2010

심미적 보철물을 제작하는 데 있어 색조의 선택은 중요한 단계이다. 이러한 색조선택과정은 광원, 표면, 관찰자 의 능력, 주변 배경색상, 관찰각도, 명암적응력 등과 같은 다양한 원인에 의해 좌우된다. 색조를 선택하는 시점에 따라 치아의 건조정도는 달라지게 되므로 본 실험에서는 치아 건조정도가 자연치아의 색조에 미치는 영향에 대해 살펴보고자 하였다. 구강내 색조측정기를 이용하여 구강가글 즉시 측정한 군을 실험군으로 구강가글 10초 후, 1분 후, 5분 후, 30초간 건조 후 색조를 측정하여 ${\Delta}E$값을 비교하였다. 각 실험군사이 ${\Delta}E$값은 유의할 만한 차이를 보였으나 대부분의 경우 구강내에서 시각적으로 구별할 수 없는 정도의 근접치를 보였다. 실험결과 시각적인 방법으로 색조 견본을 이용하는 방법은 건조정도에 따른 색조 차이가 없는 것으로 사료되고 기계를 이용하는 경우 건조정도가 색조 선택에 유의할 만한 영향을 줄 것이라고 사료된다.

• 항공우주기술
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• 제9권2호
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• pp.98-104
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• 2010

대기 중의 수증기는 가스터빈엔진의 주요성능에 많은 영향을 끼친다. 습공기의 영향은 기온 및 기압이 높은 여름철 해면 고도, 높은 비행 마하수 그리고 낮은 엔진 회전수에서 이 더욱 두드러진다. 이러한 습공기 유입에 따른 가스터빈 엔진의 성능변화의 정도를 살펴보고자 가스터빈 시뮬레이션 프로그램(GSP)과 200lbf 급 초소형 터보제트 엔진의 고공환경 성능시험을 통해 습도가 엔진성능에 미치는 영향에 대하여 알아보았다. 고공환경 엔진시험을 통해, 건공기 유입에 비해 습공기 유입 시 순추력에서 2.826% 낮게, 비연료소모율에서 1.325% 높게 측정되었다.

• 터널과지하공간
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• 제7권2호
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• pp.91-99
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• 1997

To stabilize the energy price, the more storage facilities of energy are required and among the storage methods of LPG and LNG, the method of storage at low temperature under normal confining pressure is considered. It is needed to understand the mechanical and thermal characteristics of rock under temperature variation so that the behaviors of rock can be predicted. In this paper, the variation of the rock charateristics of the Hwangdeung granite and the Boryung sandstone is studied at low temperature. The mechanical characteristics of rock under low temperatures are that as temperature decreased, unaxial compression strength and Young's modulus increased for Hwangdeung granite; strength and Young's modulus in wet condition were greater than those in dry condition. In the case of Boryung sandstone, as temperature decreases unaxial compression strength and Young's modulus increase but decrease below -10$0^{\circ}C$ in dry condition and below -16$0^{\circ}C$ in wet condtion. The mechanical characteristics of rock after cooling to previous temperature and thawing are that uniaxial compression strength and Young's modulus decrease as temperature decreases. Uniaxial compression strength and Young's modulus in wet conditon decrease more than those in dry condition. Brazilian tension strength decreases as temperature decreases.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.335-338
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• 2010

대기 중의 수증기는 가스터빈엔진의 주요성능에 많은 영향을 끼친다. 습공기의 영향은 기온 및 기압이 높은 여름철 해면 고도, 높은 비행 마하수 그리고 낮은 엔진 회전수에서 그 영향이 더욱 두드러진다. 이러한 습공기 유입에 따른 가스터빈 엔진의 성능변화의 정도를 살펴보고자 200lbf 급 초소형 터보제트 엔진의 고공환경 성능시험을 통해 습도가 엔진성능에 미치는 영향에 대하여 알아보았다. 고공환경 엔진시험을 통해, 건공기 유입에 비해 습공기 유입 시 순추력에서 2.826% 낮게, 비연료소모율에서 1.325% 높게 측정되었다.

• 한국농공학회논문집
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• 제54권5호
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• pp.69-77
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• 2012

Relative density, used to express dynamics condition of sand quantitatively, is measured by RI Test, Standard Penetration Test and Cone Penetration Test. Each measurement method has demerits, which is complicated or needs a specific analysis instrument and an analysis of expert. Also the ground is in wet condition commonly because of an unsaturated zone between a saturated zone and a surface, so the behaviour of the ground has different engineering properties unlike the dry ground and it diminishes accuracy of measuring relative density. In this study, the correlation between relative density and penetration of fall cone test in dry condition and wet condition with variation of water content was analyzed and a simple measuring method for relative density was suggested. As a result, there were difference of penetration between dry sands and wet sands, the correlation between relative density and penetration showed linear expression and relative density could be measured by the linear relation.

• Water Engineering Research
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• 제5권1호
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• pp.1-16
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• 2004

The purpose of this study is to understand the characteristics of hourly PET(Potential Evapo Transpiration) variation estimated using Penman ET model. The estimated PET using Penman model was compared with measured ET. For this study, two subwatersheds were selected, and fluxes, meteorological data and soil moisture data were measured during the summer and winter days. During the winter days, the aerodynamic term of Penman ET is much greater than that of energy term of Penman ET for dry soil condition. The opposite phenomena appeared fer wet soil condition. During the summer days, energy term is much more important factor for ET estimation compared with aerodynamic term regardless of soil moisture condition. Penman ET, measured ET, and energy term show the similar hourly variation pattern mainly because the influence of net radiation on the estimation of Penman ET is much more significant compared with other variables. Even though there are much more soil moisture in the soil during the wet days, the estimated hourly ET from Penman model and measured hourly ET have smaller values compared with those of dry days, indicating the effect of cloudy weather condition.