• Proceedings of the Korean Society for Agricultural Machinery Conference
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• v.10 no.2
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• pp.89-94
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• 2005

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.3
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• pp.218-226
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• 2002

This study was carried out to develop continuously variable-speed transmission(CVT) fur an agricultural tractor. The full-toroidal variator mechanism with flour discs and six rollers was utilized as a device fur changing speed ratio continuously. In system layout design, the sizes of the roller cylinders and the end-load cylinder, which were critical factors for controlling the variator, were designed. The planetary gear unit and six pairs of the gear assemblies were designed to establish the maximum speed of the vehicle at 30 ㎞/hr. In addition, the hydraulic clutch, the silent chain, the hydraulic manifold and the electronic controller were designed. Based on the design, a prototype CVT was developed and tested. Test results show that the CVT developed in this study could successfully provide variable speed of the tractor.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.07a
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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)

• Journal of the Society of Naval Architects of Korea
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• v.60 no.4
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• pp.288-295
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• 2023

This paper deals with the dynamic simulation method for analysis of driving characteristics of aircraft and towing vehicles (TUG) on carrier vessel in wave motions. For prompt deployment in a short period of time, optimization of the movement of carrier aircraft becomes a major issue. In this regards, strategy studies using real-time simulation technology and optimal decision-making technologies are being conducted. In the present work, the dynamic characteristics of carrier aircraft and TUG connected by towbar or towbarless mechanism were investigated by means of multi-body dynamics model. Meanwhile, for real-time simulation, Dugoff's model of tire loads calculation was adopted. Through comparative analysis it was confirmed that the similarity of results between the multi-body contact model and the tire load calculation model can be achieved by coefficients tuning.

• Journal of Korean Society of Forest Science
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• v.97 no.1
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• pp.61-70
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• 2008

This study was conducted to develop a mobile tower-yarder with tractor for agriculture and forestry that is the efficient yarder in steep terrains, thinning operation and small scale logging operation. It was designed and manufactured that the power source of tower-yarder is equiped three hydraulic pump connected to PTO of tractor, and three hydraulic pump is used to operate the four motor for drum, the cylinder for clutch of interlocker, the cylinder for tower expanding and the out-rigger cylinder. It was to adopt the running skyline system and the inter-lock function, and to equip the double capstan drum, the storage drum and the clutch for interlock in the development of tower-yarder. It was to develop the tower-yarder which the winch torque of double-capstan drum, the traction force of double-capstan drum, the number of rotation of double-capstan drum and the line speed is $191kg{\cdot}m$, 1,910 kgf, 220.5 rpm and 138.5 m/min, respectively. And it was known that the optimum flange diameter of the main and haulback storage drum is about 360 mm and about 460 mm in order to storage the main line length of 250m and the haulback line length of 450 m. The carriage was made to adopt the running skyline system and to equip the lock function in order to the convenience of chocking and the fall down preventing of tree. It was provided to develop the wire remote controller for the inter-lock function, the convenience of control and the efficiency of yarding. In development process, this tower-yarder was attached the 3-point linkage hitch equipment and the tire wheel for the traction and moving of tower-yarder. Also, it was equipped that the out-rigger and the guy line in order to raise the safety and efficiency of yarding of tower-yarder.

• Journal of Animal Environmental Science
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• v.8 no.3
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• pp.135-144
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• 2002

A computer simulation was carried out to investigate the optimum capacity of liquid manure tank spreader which is used as a tractor attachment. Soil physical properties, such as soil moisture content, bulk density, soil hardness and soil types were measured in the 10 major rice production area for computer simulation. Mathematical model which include soil physical properties and vehicle factor was used for computer simulation. Most of the soil type of the investigated area was sandy clay loam. Soil moisture content ranged between 30 and 40% mostly. Soil bulk density was in the range of 1,500 to 1,700 kg/$m^3$. Soil hardness ranged between 1 to 18 $cm^2$. Soil hardness incorporate the effects of many soil physical properties such as soil moisture content, soil type and soil bulk density, and so the range of soil hardness is greater than any other physical properties. The capacity of liquid manure tank spreader was above 3,000 kg$_{f}$ for the most of the investigated areas, and mostly in the range of 4,000 to 6,000 $kg_f$ depending upon the slip. But for the soft soil area such as Andong and Asan, the tractor itself has mobility problem and shows no pulling force for some places. For this area, the capacity of liquid manure tank spreader ranged between 1,000 and 2,000 $kg_f$ mostly, so the capacity of liquid manure tank spreader should be designed as a small capacity trailer compared to the other area.mpared to the other area.

• Journal of Biosystems Engineering
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• v.34 no.2
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• pp.71-76
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• 2009

This study was conducted to investigate the load acting on a tractor engine when it delivers the maximum power at drawbar. The results of the drawbar tests on the 5 locally-made and 14 imported tractors conducted at NIAE in 2004, and the 15 tractors tested at OECD test stations in foreign countries were analyzed and presented by the torque load ratio, defined as a ratio of the engine torque load caused by drawbar pull to its full-load capacity, as a function of pull speed. The NIAE test results showed that the torque load ratio increased from 20 to 80% with pull speed less than 5 km/h. At speeds faster than 5 km/h, it was 80${\sim}$110% regardless of the pull speed. However, the OECD test results showed that the torque load ratio was evaluated mostly to be 70${\sim}$90% in the entire pull speed range. The same trend was also shown for the maximum drawbar load. The difference in the torque load ratio may be attributable to bias-ply tires for locally-made and some imported tractors. It is also suggested that the input torque load may be increased safely up to 120% of the full load capacity of the tractor engine for an accelerated life test of tractor transmissions.

• Journal of the Korean Institute of Gas
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• v.22 no.6
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• pp.59-64
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• 2018

As part of measures to reduce fine dust, the government is promoting a project to convert the fuel of Yard Tractors(YT, tractors operated at ports), from diesel to LNG (Liquefied Natural Gas). While a port having a small number of yard tractors, it is not proper to construct a stationary LNG fueling station and supply LNG to YT due to a problem of BOG (Boil off gas) generation. Therefore, it is necessary to make a regulation and a standard on mobile LNG YT refueling station installation and inspection as an alternative. In this study, we have investigated domestic and foreign mobile LNG refueling cases and refueling standards, including the USA and Europe. In addition, we have suggested the risk reduction method according to the cause after investigation of the cause of LNG accidents. And last, based on the proposed risk reduction measures, we have proposed an amendment to the Regulation of the Urban Gas Business Law in Korea. The proposed mobile LNG YT refueling amendment of the Regulation includes ; maintenance of the safety distance from the protection facility, installation of an interlock device to prevent refueling in places other than the authorized place, installation of the identification system through biometrics, separation of the tank lorry and tow vehicle before refueling, checking the wheel fixed status of tank lorry before refueling, construction of the impounding area, safety measures before, during and after refueling, etc. The safety standards proposed in this study could be used as a reference in establishing standards for mobile LNG vehicle refueling in the near future.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.72-72
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• 2017

국내 농업에서 토양의 반전, 쇄토, 배토, 가능한 복합작업기인 무동력 디스크해로우 방식의 경운과 배토 고효율 복합작업기의 수요가 증가 하고 있다. 경운작업에서 일련의 과정은 작물의 생육과 관리차원에서 큰 의미를 지니며 작물재배의 첫 단계로 중요시 다루어져야할 과정이다. 이러한 작업기의 성능 시험에서 포장시험을 통해 복합기의 신뢰도와 실제 필드에서 발생하는 문제들을 포괄적으로 해결 할 수 있는 방안이 필요하다. 토양 경작을 위한 농업기기의 작업 저항은 식물 생산에서 유용성을 평가하는 가장 중요한 지표중 하나이다. 작업 저항(수평, 수직 방향의 힘)은 트랙터의 힘에 의해 생성된 동작을 방해하므로 토양 경운 시 에너지 소비를 결정하고 설계 매개 변수 측면에서 최적의 작업 조건을 결정하는 데 중요한 영향을 미친다. 따라서 본 연구에서는 경상대학교 내 위치한 실험동에서 Soil-bin에 이송장치를 설치한 후, 이송장치에 디스크 해로우 (Multidisc Vario, Tulip Agri., Netherlands)를 부착하여 실험을 진행하였다. 디스크 해로우의 원주 평면과 수직 평면 사이의 각 a(토양 표면에 수직)와 디스크의 해로우의 원주 평면과 작업 방향 사이의 각 b의 값을 독립 변수로 두고 a, b를 변화 시키면서 발생하는 이송장치의 견인력을 측정하여 농가 및 효율적인 경운작업 시 기초자료로 활용하고자 한다.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2003.02a
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• pp.244-250
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• 2003

국내에 보급된 방제기는 인력분무기, 동력 분무기, 동력 살분무기, 스피드 스프레이어, 붐방제기 등이 있다. 그 중 동력경운기에 탑재하거나 트랙터에 견인되는 동력분무기를 주축으로 기계화되어 있다. 작은 입경의 분무입자로서 가급적 적정량을 균일하게 뿌릴 때 방제효율을 높일 수 있는데도 불구하고, 동력분무기에 의한 액제 살포는 원거리 살포에 따라 분무입자의 입경 분포가 다양하며 대부분 분무입자가 매우 크므로 고른 살포를 기대하기 어렵기 때문에 약액을 1000대 1로 희석하여 흠뻑 적실 정도로 다량 살포를 하여 살포효율을 높이고 있다. 그러나 이러한 방제 방법은 효율성, 작업능률과 환경의 오염 측면에서 상당한 문제로 지적되고 있다. (중략)