• Journal of Biosystems Engineering
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• 제36권1호
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• pp.1-8
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• 2011

Six models of operator seat supplied to local tractor manufacturers were tested in the laboratory in accordance with ISO 5007 and 78/764/EEC. No models out of the six met the allowable damping and transmissibility performance criteria of both ISO 5007 and 78/764/EEC. From the ISO criterion standpoint, one model failed in damping performance and 4 models in isolation performance. From the 78/764/EEC criterion standpoint, 4 models failed in damping performance and 4 models in isolation performance. However none of them failed in all of the criteria, either. Each model met the one acceptance criterion but failed in another. This indicated that operator seat must be improved to meet the current ISO 5007 or 78/764/EEC and the exposure limit value that will be enforced in EU tractor market from 2014 by EU Directive 2002/44 EC.

• Journal of Biosystems Engineering
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• 제34권4호
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• pp.205-210
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• 2009

It has been known from Willoughby's empirical equation that rating cone index can be determined if wheel sinkage and slip of a vehicle can be measured on soil surface. A field data of wheel sinkage and slip was collected from two tractors of different sizes on gravelly sand and gravelly loamy sand. Using the data, rating cone index of the soil was estimated. The estimated rating cone index demonstrated that it could be determined in real time by measuring wheel sinkage and slip. It was also demonstrated statistically that the same soil strength could be obtained under the same soil conditions regardless of the vehicle platforms used for the wheel sinkage and slip measurements.

• Agricultural and Biosystems Engineering
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• 제5권2호
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• pp.35-39
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• 2004

A review of accidents involving farm machinery, which occurred in Korea during 2002, shows that $90.7\%$ of farm-work accidents and $9.3\%$ of traffic accidents were linked to agricultural machinery. The frequency of accidents per annum amounts to 72.2 out of 10,000 vehicles, $94.4\%$ of which relates to tillers and tractors. An analysis of the causes of the accidents revealed that $49.1\%$ of farm-work accidents were due to the tiller driver's fault or error. In the case of traffic accidents, $83\%$ of farm machinery mishaps were found to be due to violation of traffic regulations while $60.4\%$ of the farm machinery damage resulted from faulty driving or lack of safe driving practices. The average casualty count of farm machinery-related accidents is 1.39 persons per case, which consist of 0.07 deaths, 0.74 serious injuries, and 0.58 slight injuries.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2002년도 하계 학술대회 논문집
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• pp.66-71
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• 2002

파워시프트는 동력전달의 단속 없이 변속할 수 있는 변속 방식이다. 기어는 동기 물림식으로 되어 있으며, 유압 클러치를 통하여 주행 중에도 동력의 흐름을 제어할 수 있다. 주요 구성 요소는 동력 흐름을 제어할 수 있는 유압 클러치와 동력을 전달하는 기어 조합이며, 유압 클러치는 피스톤, 리턴 스프링, 디스크, 플레이트 등으로 구성되어 있다. 접속 시에는 유압 피스톤이 리턴 스프링을 압축하며 전진하여 플레이트와 디스크에 수직력을 가하고 이를 결합시켜 동력을 전달한다. 해제 시에는 리턴 스프링에 의하여 피스톤이 후퇴하고 동력이 차단된다. 이때 유압 제어 시스템은 최대 견인 부하에서도 변속을 원활하게 하기 위하여, 클러치 압력을 이용해 변속 중 작동 클러치의 토크를 정교하게 제어한다. (중략)

• 한국자동차공학회논문집
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• 제7권8호
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• pp.216-223
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• 1999

This study was intended to determine the inertia , damping and stiffness properties of the cab-suspension of agricultural tractors by applying the direct system identification method (DSIM). Since the rigid and elastic modes of the cab-suspension are not likely to be separated clearly, direct application of the DSIM may result in large computation error. To solve such a problem, a method of locating mass center of the cab were determined by assuming the behavior of the cab-suspension is a rigid body motion. The dynamic parameters of the cab-suspension were then determined by applying the DSIM with the known coordinates of the mass center. The constraints of spatial matrices of the cab-suspension also make the algorithm for the DSIM perform better. The values of dynamic parameters determined by this method agreed well with those determined by the experiment.

• Journal of Biosystems Engineering
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• 제16권3호
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• pp.219-227
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• 1991

This paper concerns with experimental verification of the theory on the safe VHP positions presented in the first part of this study. In the experiment, tillage operation was conducted using a plow mounted to the threepoint hitch and the forces acting on the hitch points were measured. Using the data from the test tractor and plow, computer simualtion was also conducted and its results were compared with those obtained from the field experiment. The comparison showed a reasonable agreement between the two results, by which the theoretical method for the determination of safe VHP positions for steering control can be verified. Some guidelines for expanding the safe VHP region were finally proposed.

• 지능정보연구
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• 제4권1호
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• pp.1-10
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• 1998

Process planning is a very complex task and requires the dynamic informatioon of shop foor and market situations. Process plan selection is one of the main problems in the process planning. In this paper, we propose a new process plan selection model considering operation flexibility for the computer aided process planing. The model is formulated as a 0-1 integer programming considering realistic shop factors such as production volume, machining time, machine capacity, transportation time and capacity of tractors such as production volume, machining time, machine capacity, transportation time capacity of transfer device. The objective of the model is to minimize the sum of the processing and transportation time for all parts. A genetic algorithm a, pp.oach is developed to solve the model. The efficiency of the proposed a, pp.oach is verified with numerical examples.

• 한국항해항만학회지
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• 제30권4호
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• pp.285-290
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• 2006

Shipping companies consider most of the ship turnaround time as a critical factor when selecting a rolling port for reducing costs. So, many researchers have been studying for the optimization of preplanning and high~performance of the Gantry Cranes (GCs) in container terminals for faster loading and unloading. Therefore, in this paper, we propose an RFID (Radio Frequency Identification) based RTLS (Real-Time Location System) for reducing the ship turnaround time in ubiquitous port environment. In addition, pre-planning based on ubiquitous computing environment will support the GC and Yard Tractors (YTs), and reduce ship turnaround time more effectively. Especially, the proposed method enormously enhances the productivity of loading for the twin-lift system It will reduce the whole lead-time in the process of port logistics.

• 한국시뮬레이션학회논문지
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• 제7권2호
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• pp.91-104
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• 1998

This paper describes the simulation study which evaluates operation plans of container terminal. The operation plans of container terminal consist of berth plan, load plan, unload plan, yard plan, and equipment plan. It is discussed how to apply the simulation method to evaluate those plans that are interrelated with each other. This paper also deals with the assignment and coordination problems of container-handing equipment such as container cranes, transfer cranes, yard tractors, and trailers used in the transportation of containers. Simulation analysis is bases on data about plans from the operation planning system through an interface program. It is discussed what we should got the statistics about container-handing equipment in the simulation.

• 대한전자공학회논문지
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• 제18권2호
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• pp.1-13
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• 1981

부궤환증폭기의 잡음지수를 해석하는데 있어서, 부궤환증폭기를 기본증폭기와 궤환회로망으로 나누어서 신호전달을 2원적으로 생각하였다. 이 개념으로 일반적이고 기븐적인 4가지 형태의 부궤환증폭기의 잡음지수 해석에 간편한 잡음등가회로 모델을 유도하고, 이를 이용하여 각 경우에 대한 잡음지수를 구하였다. 이 이론을 적용하는 한 보기로, 트란지스터로서 4가지 각각의 부궤환증폭기를 구성하여, 이 이론을 이들의 잡음지수를 구하는데 적용 하였다. 잡음지수의 이론치와 실험치 간에는 약 11%의 오차 범위 내에서 이론의 타당성을 보였으며, 그리고 회로구성 및 오차에 대하여 검토하였다.