• 한국농공학회지
• /
• 제18권4호
• /
• pp.4259-4264
• /
• 1976

This paper, is about the test on the operating performance of diesel engine by using of soybean oil which farmers could supply in their farm yard. The diesel engine used is a swirl-chamber type, four stroke cycle with single cylinder, air cooling and its rated horse power is 2 PS per 1300 rpm. Several results obtained are as follows; 1. The starting performance of diesel engine with soybean oil is almost the same as that with light oil. 2. The variation of engine speed according to various engine load is small when soybean oil is used compared with light oil. It is considered that soybean oil is desirable for the purpose of industerial power machine fuel. 3. The specific fuel consumption increases approximately 10 percent high in the condition of rated horse power and maximum horse power and shows less or same during the load test in low velocity, when soybean oil is used 4. Though the brake thermal efficiency in the condition of rated horse power and maximum horse power is inclined to decrease when soybean oil is used compared during the load test in low velocityt shows good inclination.

• Wind and Structures
• /
• 제22권2호
• /
• pp.253-272
• /
• 2016

The paper concerns with the method and results of wind tunnel investigations of the Strouhal number (St) of a stationary iced cable model of cable-supported bridges with respect to different angles of wind attack. The investigations were conducted in the Climatic Wind Tunnel Laboratory of the Czech Academy of Sciences in $Tel{\check{c}}$. The methodology leading to the experimental icing of the inclined cable model was prepared in a climatic section of the laboratory. The shape of the ice on the cable was registered by a photogrammetry method. A section of an iced cable model with a smaller scale was reproduced with a 3D printing procedure for subsequent aerodynamic investigations. The St values were determined within the range of the Reynolds number (Re) between $2.4{\cdot}10^4$ and $16.5{\cdot}10^4$, based on the dominant vortex shedding frequencies measured in the wake of the model. The model was oriented at three principal angles of wind attack for each of selected Re values. The flow regimes were distinguished for each model configuration. In order to recognize the tunnel blockage effect the St of a circular smooth cylinder was also tested. Good agreement with the reported values in the subcritical Re range of a circular cylinder was obtained. The knowledge of the flow regimes of the airflow around an iced cable and the associated St values could constitute a basis to formulate a mathematical description of the vortex-induced force acting on the iced cable of a cable-supported bridge and could allow predicting the cable response due to the vortex excitation phenomenon.

• Current Research on Agriculture and Life Sciences
• /
• 제22권
• /
• pp.19-27
• /
• 2004

마늘 총 재배면적은 우리나라 채소재배면적의 약 9%을 점유하고 있으며, 연간 수요량도 1,000~1,500톤 정도씩 늘어가는 추세이다. 또한 개인 소비량도 약 10kg 내외로 매년 증가추세이므로 농가에서는 중요한 소득 작물로 자리 잡고 있다. 본 연구는 경운기 부착형 마늘 자동 파종기 개발에 필요한 설계인자 구명을 위하여 파종 작업과정, 파종방법, 마늘 종구의 파종깊이와 파종자세에 따른 생육상태를 조사하였고 마늘의 크기와 무게를 측정하였다. 또한 마늘 인편을 자유 낙하시켰을 경우의 인편의 착지자세를 조사하였다. 또한 가장 핵심 부분인 마늘 배종 장치의 자동정렬장치 개발을 위해 Working Model 3D Program를 이용하여 설계요소를 파악하였다. 연구결과는 다음과 같다. 1. 마늘의 크기를 측정한 결과 평균 폭 3cm, 높이 3cm 길이 4cm로 나타났다. 2. 마늘의 무게는 평균 4g정도였다. 3. 마늘 파종 깊이는 3cm가 적정함을 알 수 있었다. 4. 마늘 배종장치는 마늘을 자유 낙하시키는 장치로 개발한다. 5. 마늘을 15cm의 일정한 간격으로 파종하기 위해서 종구는 약 0.75초마다 하나씩 파종기에서 배종되어야 한다. 6. 마늘 자동정렬장치의 설계인자는 원통의 지름(D) 4cm, 원통사이의 거리(d) 1cm, 회전수 36rpm, 원통의 경사각(${\Theta}$) $8.4^{\circ}$가 가장 적당한 것으로 나타났다.

• Journal of Biosystems Engineering
• /
• 제40권3호
• /
• pp.212-223
• /
• 2015

Purpose: Physical properties of Detarium microcarpum seeds were investigated as a function of moisture content to explore the possibility of developing bulk handling and processing equipment. Methods: Seed size, surface area, and 1,000-seed weight were determined by measuring the three principal axes, measuring area on a graph paper, and counting and weighing seeds. Particle and bulk densities were determined using liquid displacement and weight in a measuring cylinder, respectively. Porosity was computed from particle and bulk densities. Roundness and sphericity were measured using shadowgraphs. Angle of repose and static and kinetic coefficients of friction were determined using the vertical cylindrical pipe method, an inclined plane, and a kinetic coefficient of friction apparatus. Results: In the moisture range of 8.2%-28.5% (db), the major, intermediate, and the minor axes increased from 2.95 to 3.21 cm, 1.85 to 2.61 cm, and 0.40 to 1.21 cm, respectively. Surface area, 1,000-seed weight, particle density, porosity, and angle of repose increased from 354.62 to $433.19cm^2$, 3.184 to 3.737 kg, 1060 to $1316kg/m^3$, and 30.0% to 53.1%, respectively, whereas bulk density decreased from 647.6 to $617.2kg/m^3$. Angle of repose increased from $13.9^{\circ}$ to $28.4^{\circ}$. Static and kinetic coefficients of friction varied between 0.096 and 0.638 on different structural surfaces. Conclusions: Arithmetic mean, geometric mean, and equivalent sphere effective diameters determined at the same moisture level were significantly different from each other, with the arithmetic mean diameter being greatest. Surface area, 1,000-seed weight, particle density, porosity, and angle of repose all increased linearly with moisture content. Bulk density decreased linearly with moisture content. The coefficients of friction had linear relationships with moisture content. The highest values of static and kinetic coefficients of friction were observed on galvanized steel and hessian fabric, respectively, whereas the lowest values were observed on fiberglass.

• 한국축산시설환경학회지
• /
• 제19권1호
• /
• pp.9-18
• /
• 2013

Currently, there was no producing system of TMR for pig feeding in Korea. In this study, we examined unrolling, cutting, and softening for the round bale silage. We designed and developed the prototype system of round bale silage for pig feeding. Unroll method were lower chain conveying and upper belt conveying which includes an hydraulic vertical fodder knife. Gathering and cutting method were rotating auger and flywheel which have 10 cutters, input roller of 280 rpm, and cutter rotating speed of 1,750 rpm. Softening device was rotating hammer in inclined cylinder adjustable to $25^{\circ}C$ and rotating speed up to 1,300 rpm. The prototype system was integrated working for unrolling, cutting, and softening. We found that when the round bale silage in unrolling apparatus cut length of 20 cm to input cutting apparatus, the cutting performance was well in continuous working up to input rate of 1,000 kg/h, the softening apparatus was working well.

• 에너지공학
• /
• 제23권2호
• /
• pp.13-20
• /
• 2014

헬리컬 코일이 덕트 내부에 있을 때, 기울기에 따른 자연대류 열전달을 실험적으로 측정하였다. 고부력 조건을 구현하기 위하여 유사성에 기초하여 열전달 실험을 대신하여 물질전달 실험을 수행하였다. RaD 수 $4.55{\times}10^6$에서, 턴(Turn) 수를 1~10, P/D를 1.3~5, 헬리컬 코일의 기울기를 $0^{\circ}{\sim}90^{\circ}$까지 변화시켰다. 헬리컬 코일의 턴 수가 1일 때, 측정된 $Nu_D$ 수는 McAdams의 수평관 자연대류 열전달 상관식과 거의 일치하였다. 기울어진 덕트 내 헬리컬 코일의 자연대류 열전달은 피치, 턴 수, 덕트 높이에 따라 복합적으로 변화하였고 이는 속도 효과, 굴뚝 효과, 예열 효과로 분석되었다. 본 연구의 결과는 Compact heat exchanger에서의 자연대류 열전달에 대한 현상학적 분석에 기여한다.