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곡면 엘보우를 가진 사각덕트 내의 유속측정 및 수치계산에 관한 연구
윤영환,박원구 대한설비공학회 2003 설비공학 논문집 Vol.15 No.11
Fluid flow in a rectangular duct for 90$^{\circ}$ bend elbow with the ratio of 1.5 between its curvature radius and width is measured by 5 W laser doppler velocity meter. The fluid flow is also computed by commercial software of STAR-CD for comparison between measured and computed velocity profiles in the duct. Reynolds numbers for the comparison are 11,643, 19,746 and 24,260. From the comparison, computation of principal velocity components in the duct predicts the experimental data somewhat satisfactorily even though those of minor velocity components and turbulent kinetic energy do not match with the experimental data quite well. K-factor for the bend elbow is computed to be average 0.086 while the equivalent ASHRAE data is 0.07.
벼 생육중기 및 출수기 태풍 "올가" 건풍에 의한 엽신 피해의 품종간 차이와 수량 및 품질 변화
윤영환,김정곤,정남진,곽강수,강양순 한국국제농업개발학회 2003 韓國國際農業開發學會誌 Vol.15 No.4
1999년 8월3일~8월4일간 태풍 올가 도래시 건풍에 의한 생육중기 엽신 피해의 품종간 차이와 출수기 이삭 갈변에 따른 수량 및 품질에 미치는 영향을 조사하여 다음과 같은 결과를 얻었다. 1. 잎의 증산량 및 수분저하속도가 클수록, 잎이 길이가 길고 폭이 넓을수록 엽신의 피해정도가 컸다. 2. 이삭의 피해 정도가 증가될수록 임실 및 등숙비율은 현저히 낮아지는 경향이며, 쌀 수량은 무피해 대비 피해 3~5는 14~16%, 피해 7은 28%, 피해 9는 48% 감수하였다. 3. 이삭의 피해 정도별 백미 완전미 비율은 피해 정도가 클수록 감소를 보였으며 피해 0~3에서 63~65%, 피해 5~9에서 42~58%의 분포를 보였다. 4. 이삭의 피해정도가 증가할수록 백도 및 색도치가 낮아지며, 단백질 함량은 증가하고 식미치는 저하하는 경향을 보였다. This study was carried out to characterize the influence of dry wind by typhoon "Olga" during Aug. 3~Aug. 4, 1999 on the rice plant(Oryza sativa L.). For the purpose, the affection of the dry wind during the mid-growing stage and heading stage on the leaf damage, yield and rice quality were investigated. The extent of the leaf damage increased with the increase of leaf size and transpiration rate, and also with the decrease of moisture content in the leaves. The percentage of fertile grain decreased in proportion to the increase of the extent of the panicle damage. Compared with none-damaged rice plants in the panicle, the milled rice yield decreased by 14~16% in the degree 3~5 of the panicle damage, and 28~48% in the degree 7~9. The percentage of head rice was the same in the both milled and brown rice in the degree 0~3 of the panicle damage. Above the degree 5, however, it decreased with the increase of the panicle damage. The whiteness and lightness decreased in proportion to the increase of the degree in the unhulled, brown and milled rice. And, there was a tendency that the protein content in the milled rice increased but eating quality decreased with the increase of the panicle damage.
윤영환 國立 昌原大學校 産業技術硏究所 2000 産技硏論文集 Vol.14 No.-
Experimental measurement of velocities in branches of a heat exchanger is performed in order to examine fluid flow distribution in the equipment since un-uniform flow distribution makes hot spots on the heat transfer material or reduced heat transfer coefficients. The measurement apparatus is simplified into a system of a dividing manifold, 8 branches of glass tubes and a combining manifold. Velocities in the glass tubes are measured by Ar-ion LDV system. From the experiments, it is found that uneven flow distributions are obtained as flow rate is increased, on the contrary, the fluid flow in the branches are almost evenly distributed as diameter of manifold is increased with the same flow rate. It is also found that turbulence intensities are increased as diameter of the manifold and flow rate are increased.
윤영환,최명진 경희대학교 산학협력기술연구원 1999 산학협력기술연구논문집 Vol.5 No.-
Since semi-active suspension systems of automobile. of which suspension damper are controlled actively, exhibit high performance with light system weight, low cost and low energy consumption. From this view point, semi-active suspension systems are greatly expected to be in the mainstream of future controlled suspension systems In this paper, to improve the performance of the continuous variable damper, the damping force of reverse continuous variable damper(HS-SH damper) are measured and the reverse damping control mechanism is presented The HS-SH damper offers good body control without much transferred input force from tire, compared with any other type of suspension system. In this system, rebound and compression damping force can be tuned independently
윤영환 國立 昌原大學校 産業技術硏究所 1993 産技硏論文集 Vol.7 No.-
Prototype of an electric paint heater is manufactured in order to obtain the design data for localization of the product. The paint is heated from encased electric coil through heating oil. theoretical calculations of heat exchanger rating are compared with experimental results. Performance curves of the paint heater are also presented after the rating computation. Extensive overall heat transfer coefficient, ρ*UiF*Cp where F is correction factor, is found to be 0.38*10^-4 for most operation ranges. This value is almost constant because paint flow in the tube is laminar. Finally, performance testing of automatic temperature control shows us that it function better as the flow rate is in creased from 533 to 1070 ml/min