• Journal of Drive and Control
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• v.20 no.4
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• pp.151-154
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• 2023

• Journal of Power System Engineering
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• v.13 no.6
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• pp.35-42
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• 2009

The piping systems in the steam-driven power engines lie under the cyclic condition of thermal expansion and contraction by superheated steam. These phenomena might cause some severe damages on the pipes and the accessory devices. To avoid these damages, the calculation of the proper strength and the consideration of the reduced resultant forces on the materials are needed. In the present study, numerical investigations on the effects of the thermal deformation of the industrial piping system were performed with comparison of the design data. Commercial software, ABAQUS with the thermal-fluidic loadings based on the design conditions was used for the thermal stress analysis of the piping system. From the analysis of the initially-designed pipe supporters, the rearrangement was suggested to improve the piping design.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2003.07a
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• pp.134-139
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• 2003

오늘날 산업용 차량은 대부분 유압식 클러치를 채택하여 사용하고 있다 유압식 클러치는 운전자가 손쉽게 엔진으로부터 동력을 바퀴까지 전달 또는 차단하는 기능을 갖고 있기 때문이다. 차량속도에 대한 운전자의 다양한 요구는 다수의 변속 단수를 갖는 기어트레인이나 연속가변식 변속기(CVT) 원하고 있다. 그 중에 기어단을 단속하는 클러치는 엔진의 회전력과 차량 관성력을 효과적으로 연결 또는 차단을 위해 다수의 마찰판과 유체압력을 이용하여 작동된다. 유압식 클러치는 동작방식에 따라서 유체압력이 작동하면 동력을 전달하는 POSITIVE방식과 자체 탄성 스프링력에 의해서 동력을 전달하는 NEGATIVE방식이 있다. POSITIVE방식 유압식 클러치는 동력전달시 어큐뮬레이터를 이용하여 충격을 줄이고, 부하 변동시 승차감각을 향상할 수 있는 장점이 있다 TRX500 트랙터에 사용되는 유압식 클러치는 POSITIVE방식을 채택하고 있다. (중략)

• Journal of Power System Engineering
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• v.4 no.4
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• pp.65-69
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• 2000

On the dynamic behavior of a simple beam subjected to an uniformly distributed tangential follower force, the influences of the velocities and magnitudes of a moving mass have been studied by numerical method. The instant amplitude of a simple beam is calculated and analyzed for each position of the moving mass represented by the time functions. The uniformly distributed tangential follower force is considered within its critical value of a simple beam, and four values of velocity is also chosen. Their coupling effects on the deflections of a simple beam are inspected too. When a moving mass moves after middle zone of a simple beam at the low velocities, its deflection is increased by the coupling of an uniformly distributed tangential follower force and moving mass.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2003.07a
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• pp.478-483
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• 2003

우리나라는 1960년대에 접어들면서 매년 농촌 인구가 급격한 감소를 보였으며, 이때부터 농업노동력 부족을 해소하기 위하여 동력농업기계가 널리 보급되기 시작하였다. 1970년대 중반 이후에는 급격한 경제실장과 정부의 식량 증산 책의 일환으로 동력경운기 및 콤바인, 트랙터 등 농업기계가 확대 보급되기 시작하였다. 중대형 농기계의 보급이 시작된 시기는 1980년대 전후이며 정부에서는 1990년대 상반기까지 벼농사 위주로 정책목표로 삼고 농업기계화사업을 꾸준히 추진해 왔다. 이와 같이 1960년대 이후 2000년대에 이르기까지 벼농사를 중심으로 우리나라 농업기계화 사업은 지속적으로 추진되어 왔지만, 2003년부터는 다양한 농작물 기계로 전환하여 지역 특수작물용 작업기 개발에 역점을 두고 있다. (중략)

• Journal of Drive and Control
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• v.11 no.2
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• pp.22-29
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• 2014

This paper presents simulation-based analysis of energy flow of a wheel loader. The objective of this study is to analyze the energy flow of a wheel loader during driving and working. Because the wheel loader powertrain consists of a mechanical and hydraulic powertrain, the generated power from the engine is divided into 2 powertrains. Further, a virtual prediction of energy flow in the powertrains is a key factor in terms of optimal design. Accordingly, the simulation model that is able to predict the virtual energy flow is developed and analyzed in this study. The proposed wheel loader simulation model has been constructed in the Matlab/Simulink environment. It is expected that the developed simulation model will analyze the energy flow and efficiency in the design stage.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.3
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• pp.267-273
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• 2013

In order to provide effective operating conditions for the fan in a wet cooling tower with film fill, a new program to search for the minimum fan power was developed using a model of the optimal total annual cost of the tower based on Merkel's model. In addition, a type of design map for a cooling tower was also developed. The inlet water temperature and heat load were considered as key parameters. The present program was first validated using several typical examples. The results showed that for a given heat load, a three-dimensional graph of the fan power (z-axis), mass flux of air (x-axis, minimum fan power), and inlet water temperature (y-axis, maximum of minimum fan power) showed a saddle configuration. The minimum fan power increased as the heat load increased. The conventionally known fact that the most effective cooling tower operation coincides with a high inlet water temperature and low air flow rate can be replaced by the statement that there exists an optimum mass flux of air corresponding to a minimum fan power for a given inlet water temperature, regardless of the heat load.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.1
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• pp.53-63
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• 2016

Wheel dynamometers are used to measure dynamic load that is conveyed from the road to a vehicle while driving. In this paper, two types of six-component wheel dynamometers utilizing shear deformation and bending deformation were designed and evaluated. Prior to designing the shear and bending type wheel dynamometers, the shear and bending deformation behaviors of the basic structure of the wheel dynamometer itself were analyzed using finite element analysis. Strain analysis was performed repeatedly in order to obtain a similar output sensing strain for each load component. The design was modified with a bridge circuit in order to minimize coupling strain. The results indicated that the shear type dynamometer was expected to obtain stable characteristics due to uniform strain distribution while the bending type dynamometer was expected to obtain high-quality sensitivity performance due to consistent output sensitivity.

• Journal of the KSME
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• v.29 no.1
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• pp.12-13
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• 1989

분쇄도구는 점차수차, 풍차 그리고 증기기관이란 동력기술과 맞물려 제분공정이 대규모화되어 지배자는 이를 독점, 집중화시켜 마침내 공장제도의 원형이 이루어졌던 것이다. 여기서 우리는 wind mill, water mill, rolling mill, miller, milling M/C 등 단어가 뜻하듯 단순히 "제분하는 기계" 뿐만 아니라 "자연력으로 구동되는 기계설비를 사용하였던 모든 Manufacture"라는 것을 공통어 밀(mill)에서 엿볼 수가 있다. James Watt의 증기기관이 실용 중에도 한동안 수차는 산 업 여러 분야에서 동력원으로 자리를 지켜 왔지만 현재는 획기적으로 성능이 좋은 Francis, Pelton, 및 Ossberger 수차가 상업발전소에서 쉬지 않고 돌아가고 있다. 통차, 동미차, 번차, 수대, 연애, 파쇄 등 전통적인 수차와 석구가 기본이 되어 분명히 근세 생산기계설비를 발명케 하였고 동력원으로서 화려한 전성기를 누렸다. 지금은 역사속에 잊혀져 가지만 우리는 시골 산간에서 돌아가는 물레방아의 수연한 고태를 볼 때면 민속문화학, 그리고 기술사적 측면에서 문화재로서의 명맥을 기려 잘 보존할 의무가 절실하다고 생각한다. 보존할 의무가 절실하다고 생각한다.

• Journal of Hydrogen and New Energy
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• v.33 no.6
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• pp.786-794
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• 2022

Green ammonia is a promising renewable energy carrier. Green ammonia can be used in various energy conversion devices (e.g., engine, fuel cell, etc.). Ammonia has to be fed with hydrogen for start-up and failure protection of some energy conversion devices. Ammonia can be converted into hydrogen by decomposition and partial oxidation. Especially, partial oxidation has the advantages of fast start-up, thermally self-sustaining operation and compact size. In this paper, thermodynamics, start-up and operation characteristics of ammonia partial oxidation were investigated. O₂/NH₃ ratio, ammonia flow rate and catalyst volume were varied as operation parameters. In thermodynamic analysis, ammonia conversion was maximized in the O₂/NH₃ range from 0.10 to 0.15. Ammonia partial oxidation reactor was successfully started using 12 V glow plug. At 0.13 of O₂/HN₃ ratio and 10 LPM of ammonia flow rate, ammonia partial oxidation reactor showed 90% of ammonia conversion over commercial Ru catalyst. In addition, Increasing O₂/NH₃ ratio from 0.10 to 0.13 was more effective for high ammonia conversion than increasing catalyst volume at 0.10 of O₂/NH₃.