• Journal of Biosystems Engineering
• /
• 제22권4호
• /
• pp.411-420
• /
• 1997

The mechanization efficiency using high ability machines such as tractors or combines in a paddy field rice farm is high. Mechanization in harvesting fruits and vegetables is difficult, because they are easy to be damaged. Therefore, Advanced techniques for careful handling fruits and vegetables are necessary in automation and robotization. An apple harvesting robot must have a recognition device to detect the positioning of fruit, manipulators which function like human arms, and hand to take off the fruit. This study is related to the development of a rotatic hand as the first stage in developing the apple harvesting robot. The results are summarized as follows. 1. It was found that a hand that was eccentric in rotatory motion, was better than a hand of semicircular up-and-down motion in harvesting efficiency. 2. The hand was developed to control changes in grasp forces by using tape-type switch sensor which was attatched to fingers' inside. 3. Initial finger positioning was set up to control accurate harvesting by using a tow step fingering position. 4. This study showed the possibility of apple harvesting using the developed robot hand.

• Journal of Biosystems Engineering
• /
• 제19권4호
• /
• pp.291-300
• /
• 1994

It is desired to operate tractor engines at or near maximum torque much of the time in field operation to increase fuel efficiency. To do this it is necessary to reduce engine speed and to shift gears to higher ratios as frequently as possible. Because of load variations in most drawbar work and inconvenience in gear shift, however, gear-type transmission are usually set in one ratio at unnecessarily high engine speeds, and engine-torque variations are used to compensate for changes in drawbar load. As a result, the most of time the tractor is not operated efficiently in terms of fuel consumption and work output. The objective of this study was to develop an automatic control system which is able to operate a tractor equipped with gear transmission under the optimal condition in terms of fuel efficiency with automatic governor setting and gear shift. An indoor experimental test set which can be used to simulate tractor operation, control engine speed and transmission ratio was developed in the previous paper. In this paper, the performance of the optimal operation system is reported. Through a series of tests, it was found that the automatic control system for optimal operation of tractors with gear transmission had a satisfactory performance.

• Journal of Biosystems Engineering
• /
• 제41권3호
• /
• pp.145-152
• /
• 2016

Purpose: This study aims to establish the effect of pinhole position errors in the planet carrier of a planetary gear set (PGS) on load sharing among the planet gears in the hydromechanical transmission (HMT) system of an agricultural tractor. Methods: A simulation model of a PGS with five planet gears was developed to analyze load sharing among the planet gears. The simulation model was verified by comparing i ts r esults w ith those of a model developed in a previous s tudy. The verified simulation model was used to analyze the load-sharing characteristics of the planet gears with respect to the pinhole position error and the input torque to the PGS. Results: Both simulation models had identical load magnitude sequences for the five planet gears. However, the load magnitudes on the corresponding planet gears differed between the models because of the different stiffnesses of the PGS components and the input torques to the PGS. The verified simulation model demonstrated that the evenness of load sharing among the planet gears increases with decreasing pinhole position error and increasing input torque. Conclusions: The geometrical tolerance of the pinhole position should be properly considered during the design of the planet carrier to improve the service life of the PGS and load sharing among the planet gears.

• Journal of Biosystems Engineering
• /
• 제30권6호통권113호
• /
• pp.327-332
• /
• 2005

In this study, the electronic power steering control system was developed and it was carried out to investigate experimentally the effect of the steering force for the on-road and off-road. The electronic power steering control system was engineered new trend system of power steering control system for tractor. It was composed of the electronic controller, detector, motor and mechanism mounted on tractor chassis. It was tested at the field in condition of tractor traveling speed 0 km/h, 3 km/h, 8 km/h, 11 km/h, 15 km/h, 18 km/h, 22 km/h, 25 km/h for measuring a maximum steering force. As a speed of tractor increased, a steering force decreased regardless of on-road or off-road. In addition, it is sufficiently a possibility of application of the steering system of tractor.

• Journal of Biosystems Engineering
• /
• 제28권6호
• /
• pp.537-544
• /
• 2003

The objectives of this study were to investigate the failure characteristics of a total of 90 parts of tractor driveline, and to predict their average annual demands required to perform the after-sales service. The failure characteristics such as failure mode, mean time between failures, characteristic life and reliability were analyzed using the data collected through the experienced mechanics at the part centers of the tractor manufacturers. The analysis was based on the assumption that the failure distribution follows the Weibull distribution. The average annual demands were also predicted for the replacement parts using the mean time between failures and the renewal theory based on the Weibull distribution. The results of the study revealed that the driveline parts failure was mostly from wearout and their average characteristic life is about 1.760 hours. The estimated mean time between failures was in a range of 670∼3,740 hours and reliability in a range of 40∼60％. The annual replacement demands were in a range of 4∼45 for a service of 100 tractors.

• Industrial Engineering and Management Systems
• /
• 제15권4호
• /
• pp.335-344
• /
• 2016

Construction project is a competitive business with high risk especially in developing countries like Iran which faces with many problems such as delay and time and costs increases. Thus, the first priority here is to determine the causes of prolongation of construction projects and to evaluate their importance. Khuzestan Steel Company (KSC) has made important contribution to the projects in Iran and in turn is required to finish them on time. In this study, an attempt was made to investigate the causes of delay in implementation of construction projects held by this company. Data was collected through questionnaire distributed among the sample including 10 owners, 10 consultants and 15 con-tractors. Accordingly, participants rated the causes in the questionnaire so the most important priorities of each area were specified using TOPSIS method. The results showed that according to the employers, consultants and contractors' viewpoints, the most important reason for delays in construction projects of KSC is related to the financial matters. Hence, according to the results obtained, causes for delays in the company's projects are largely related to the drilling permits and long administrative cycle to renew them. Besides, continuous production of steel in this company is another reason to delays of construction projects.

• 한국자동차공학회논문집
• /
• 제13권6호
• /
• pp.120-127
• /
• 2005

An IDI diesel engine used to agricultural tractors was fueled with $20\%$ biodiesel fuel(BDF 20) in excess of 300 hours. Engine dynamometer testing was completed at regularly scheduled intervals to monitor the engine performance and exhaust emissions. The engine performance and exhaust emissions were sampled at 1 hour interval for analysis. The combustion variation such as the combustion maximum pressure and the crank angle at this maximum pressure was not appeared during long-time dynamometer testing. Also, BSFC with BDF 20 resulted in lower than with diesel fuel. Since the biodiesel fuel used in this study includes oxygen of about $11\%$, it could influence the combustion process strongly. So, BDF 20 resulted in lower emissions of carbon monoxide, carbon dioxide, and smoke emissions without special increase of oxides of nitrogen than diesel fuel. It was concluded that there was no unusual deterioration of the engine, or any unusual change in exhaust emissions from using the BDF 20.

• 한국산학기술학회논문지
• /
• 제16권11호
• /
• pp.7377-7384
• /
• 2015

농업용 트랙터는 전도 사고 발생 시 운전자를 보호하기 위해 전도보호구조(ROPS: Roll Over Protective Structures)의 역할을 할 수 있어야 한다. 본 연구에서는 ROPS 강도시험 규격을 만족하는 트랙터 캐빈 프레임의 제작 기간과 비용을 줄이기 위해서 유한요소해석과 최적설계를 수행하였다. 해석 결과로부터 얻은 변위와 주 변형률의 크기를 통해 캐빈 프레임의 초기설계안은 ROPS 강도시험에 합격하는 것으로 나타났다. 또한 캐빈 프레임의 경량화 설계안을 도출하기 위하여 다구찌 실험계획을 이용해 최적설계를 수행하였다. 이를 통하여 캐빈 프레임 무게가 초기설계안보다 7% 저감된 최적설계안을 도출하였다.

• 한국항해항만학회:학술대회논문집
• /
• 한국항해항만학회 2005년도 추계학술대회 논문집
• /
• pp.319-325
• /
• 2005

본 연구의 목적은 초대형 컨테이너선 기항에 따른 컨테이너터미널의 항만생산성을 예측하는 것이다. 일반적으로 컨테이너터미널의 생산성은 컨테이너크레인, 야드크레인, 야드트랙터 등을 포함한 하역시스템의 생산성에 의해 평가된다. 그러므로 부산항 컨테이너터미널의 항만 생산성으로서 컨테이너크레인의 현재 생산성을 분석하고 초대형 컨테이너선에 의한 컨테이너를 처리하기 위한 순작업 생산성과 총작업 생산성을 예측한다. 생산성 향상을 위해 하역시스템 대안과 운영시스템 대안을 요약한다.

• Journal of Biosystems Engineering
• /
• 제10권2호
• /
• pp.19-26
• /
• 1985

This study was carried out to develop a versatile data acquisition/processing system for overall tractor performance utilizing a NEC PC-8001 microcomputer. The data acquisition system measures drawbar pull and power, wheel torque and axle power, ground speed, wheel slip, fuel flow, and engine speed. The system stores hexadecimal data for these variables in memory. Upon completion of each test run, all hexadecimal data stored in memory are recorded on floppy disc. The data processing system reads in the data collected on floppy disc and interprete them using several graphical and statistical techniques. The system uses the same microcomputer and a dot-matrix printer. The data acquisition system has been installed on a GOLDSTAR 500 tractor (2WD, 50 ps). A field study has shown that tractor performance data can be quickly and easily collected. It also appeared that the data processing system can be used to efficiently analyze the collected data. The data acquisition system has some troublesome in mounting and handling on tractor since it uses a general-purpose computer consisting of several components.