• 한국철도학회논문집
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• 제7권1호
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• pp.14-19
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• 2004

The effect of surface damage on fatigue properties of catenary wires were investigated to estimate their service lift. As surface defects of the wires caused by surface corrosion increase, surface roughness gets worse, and as roughness increases, it is easy for moisture coming from rain and dew to be condensed around uneven parts of the surface. The condensed moisture causes a locally severe corrosion which leads to damage of the wires. Corrosion of catenaty wires can make their actual lifetime shorter than that originally designed. The amount of decrease was more prominent as environmental conditions became more corrosive. They are also vibrated with some amplitude everytime pantographs touch contact line. The frequent cyclic load on the wire may result in a fatigue fracture. Surface damage by corrosion can make formation of crack initiation at fatigue. In the present study, the fatigue life of the used wire was measured 35 to 50% compared with that of new one in average.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.155-156
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• 2002

During the sliding between a-CNx and $Si_3N_4$, applying nitrogen as environmental gas provided very low friction as the level of 0.01 in friction coefficient. In order to know the effect of the running-in process on the reduction of the friction, the effect of surface roughness of mating surface on friction was investigated. It was shown that smooth surface in wear scar of ball provided low friction coefficient. Friction coefficient after running-in was proportional to the Ry value of wear scar of ball. Also smooth thin transferred layer was observed on the wear scar of balls with an AFM after sliding test. Those results showed the smoothing of wear scar of ball, the generating of the transferred layer from CNx was necessary for low friction.

• 한국태양에너지학회 논문집
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• 제23권1호
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• pp.39-47
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• 2003

In order to test the predictability of the wind resource assessment computer code in our country a field experiment and prediction by WAsP has been compared. A field experiment has been performed in Songdang province, Jeju island, composed of sea, inland flat terrain, a high and a low slope craters. For this experiment, four meteorological towers have been installed at seashores, inland flat and on a crater. Wind resource at one site is predicted by WAsF with the meteorological data at the other three sites. The comparisons show that the WAsP preditions give better agreement with experimental data by adjusting the roughness descriptions.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.962-967
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• 2003

Recently, environmental pollution has become a serious problem in industry, and many researches have been done in order to preserve the environment. The coolant, which promotes lubrication, cooling and penetration, contains chlorine, sulfur and phosphorus to improve the machining efficiency. These additives, which move around into the air during machining, pollute working. Therefore, many researches on how to reduce the amount of coolant during machining have been carried out. However, to reduce even small amount of coolant causes high temperature of a workpiece and it brings thermal defects. In this study, the experiments of wet & dry grinding using cooling methods (using coolant only, mist and compressed cold air only) are performed to solve the problem of environmental contamination and to get a better surface integrity of a workpiece by comparing surface roughness, roundness and residual stress.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.19-24
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• 2003

Recently, various efforts to make more speedy and precision machine tool to improve productivity and also various efforts to solve environmental problem are going on, so that dry cutting in manufacturing industry, which needs environmental conscious design and development of manufacturing technique, is becoming a very important assignment to solve. Because dry cutting does not use cutting fluid, we need other methods that can be used instead of cutting fluid, which does cooling, lubricating, chip washing, and anti-corrosion. Especially, because turning is a continuous work, the consideration of tool life and surface roughness due to continuous heat and poor lubrication is important. The purposes of this paper are the consideration of how well the compressed air can work instead of cutting fluid, and also the development of the method to select the optimum machining condition by the minimum numbers of experiments through the Taguchi method.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.95-99
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• 2003

Recently, environmental pollution has become a significant problem in industry and many researches have been investigated in order to preserve the environment. Environmentally conscious machining and technology have more and more important position in machining process. The cutting fluid has greatly bad influence on the environment in the milling process. This research is experimental study on high speed machining of aluminum alloys through environmentally conscious machining. In this study, the machinability surface roughness and chip appearance was investigated in the machining of aluminum alloys applied dry machining and using cutting fluid, oil mist.

• Smart Structures and Systems
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• 제13권5호
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• pp.821-848
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• 2014

This paper presents a novel method to carry out monitoring of transport infrastructure such as pavements and bridges through the analysis of vehicle accelerations. An algorithm is developed for the identification of dynamic vehicle-bridge interaction forces using the vehicle response. Moving force identification theory is applied to a vehicle model in order to identify these dynamic forces between the vehicle and the road and/or bridge. A coupled half-car vehicle-bridge interaction model is used in theoretical simulations to test the effectiveness of the approach in identifying the forces. The potential of the method to identify the global bending stiffness of the bridge and to predict the pavement roughness is presented. The method is tested for a range of bridge spans using theoretical simulations and the influences of road roughness and signal noise on the accuracy of the results are investigated.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.706-708
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• 2003

Index for difference of vegetation surface roughness (BSI: Bi-directional reflectance factor structure Index) was proposed in our laboratory (Konda et al., 2000). It is thought that BSI is useful vegetation index for vegetation monitoring. If it can be applied for global covered satellite data, detailed monitoring of global vegetation can be expected. However, in order to apply BSI to global satellite data, there are some problems to be solved. In this study, in order to make global data set of BSI, it arranged about processing of the global satellite data for making BSI data sets.

• 한국기계기술학회지
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• 제13권4호
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• pp.49-55
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• 2011

Recently, various efforts to make more speedy and precision machine tool to improve productivity and also various efforts to solve environmental problem are going on, so that dry cutting in manufacturing industry, which needs environmental conscious design and development of manufacturing technique, is becoming a very important assignment to solve. Because dry cutting does not use cutting fluid, we need other methods that can be used instead of cutting fluid, which does cooling, lubricating, chip washing, and anti-corrosion. Especially, because turning is a continuous work, the consideration of tool life and surface roughness due to continuous heat and poor lubrication is important. The purposes of this paper are the consideration of how well the compressed air can work instead of cutting fluid, and also the development of the method to select the optimum machining condition by the minimum numbers of experiments through the Taguchi method.

• 한국멀티미디어학회논문지
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• 제24권11호
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• pp.1560-1566
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• 2021

Cyber Sickness, which occurs when using Virtual Reality contents, is the most serious problem in immersive Virtual Reality contents. The purpose of this study is to identify the effects and causes of graphic environmental factors on Cyber Sickness in Virtual Reality contents. To this end, cyber sickness experiments were conducted according to the light source and material settings, which are most commonly used in graphical environmental elements. Cyber Sickness measurements were based on the Simulator Sickness Question(SSQ) tool to derive an index that causes Cyber Sickness As a result of the analysis, the smaller the surface roughness, the higher the degree of Cyber Sickness, and the smaller the surface roughness, the smoother the surface of the 3D object, and many specular reflections from the light source occurred, which was confirmed to be the cause of great Cyber Sickness.