• 대한토목학회논문집
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• 제31권4A호
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• pp.279-286
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• 2011

FRP 긴장재는 PS 강연선의 부식 문제를 해결하기 위한 대안으로써 사용될 수 있으며, FRP 긴장재의 재료특성(부착강도, 인장강도, 전달길이 등)은 구조물에 적용하기 위해서 결정되어야 한다. 재료특성 중에 부착은 FRP 긴장재로 긴장된 PSC 구조물에 적용하기 위해 명확하게 요구되어야 한다. 이 연구는 다양한 표면형상을 갖는 FRP 보강재의 부착특성을 연구하였다. 콘크리트의 철근과 강연선 대신에 사용되는 FRP 재료의 부착특성을 결정하기 위해 CAN/CSA S806-02에서 제안된 직접인발 시험을 수행하였다. 강연선, 이형 철근, 6가지 다른 표면 형상을 갖는 탄소 또는 유리섬유 FRP 보강재에 대하여 총 40개의 시편이 제작되었다. 부착실험 결과 각 실험체의 다양한 부착응력-슬립 곡선을 나타냈고, 국내에서 제작된 CFRP 긴장재의 부착특성과 비교하였다.

• 전기학회논문지
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• 제62권8호
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• pp.1080-1089
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• 2013

Interior Permanent Magnet Synchronous Machines (IPMSMs) with rare earth magnet are widely used in electric vehicles and hybrid electric vehicles. IPMSMs having high efficiency, high torque, and a wide speed range are employed in propulsion system. And the rotor in an IPMSM is generally made of a rare earth magnet to achieve a large energy product and high torque. This paper discusses issues regarding design and performance of IPMSMs using different factors of BH magnetic characteristic. It is necessary to choose factors of magnetic material according to permanent magnet shape in rotor for high performance. Response Surface Methodology (RSM) is selected to obtain factors of magnetic material according to variety of rotor shapes. The RSM is a collection of mathematical and statistical techniques useful for the analysis of problems in which a response of interest in influenced by several variables and the objective is to optimize response. Therefore, it is necessary to analyze the torque characteristics of an IPMSM having magnet BH hysteresis curve with different rotor shape. Factors of residual flux density (Br) factor and intrinsic coercive force (Hc) are important parameters in RSM for rotor shape. The rotor shapes for IPMSMs having magnet BH characteristic were investigated using the RSM, and three shapes were analyzed in detail using FEA. The results lead to design consequence of IPMSMs in the various rare earth magnet materials.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1691-1694
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• 2005

The fatigue characteristic of a material or a structure is derived from fatigue tests of standard specimens. However test results of standard specimens are very different from those of real structures or components. Therefore, to calculate more accurate fatigue life, the geometrical effect and surface condition must be considered by comparing test results of standard specimens with those of real structures or components. Thus the object of this paper is to evaluate the fatigue characteristic of a real waterwork pipe by conducting fatigue tests with standard specimens and non-standard(plate-shaped) specimens of base metal and weld metal. Also, to evaluate fatigue characteristic based on life distribution, statistical fatigue characteristic was analyzed by the normal distribution and related data of P-S-N curve.

• Tribology and Lubricants
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• 제39권6호
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• pp.273-277
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• 2023

This paper presents a molecular dynamics simulation-based numerical investigation of the influence of surface energy on water lubrication. Models composed of a crystalline substrate, half cylindrical tip, and cluster of water molecules are prepared for a tribological-characteristic evaluation. To determine the effect of surface energy on lubrication, the surface energy between the substrate and water molecules as well as that between the tip and water molecules are controlled by changing the interatomic potential parameters. Simulations are conducted to investigate the indentation and sliding processes. Three different normal forces are applied to the system by controlling the indentation depth to examine the influence of normal force on the lubrication of the system. The simulation results reveal that the solid surface's surface energy and normal force significantly affect the behavior of the water molecules and lubrication characteristics. The lubrication characteristics of the water molecules deteriorate with the increasing magnitude of the normal force. At a low surface energy, the water molecules are readily squeezed out of the interface under a load, thus increasing the frictional force. Contrarily, a moderate surface energy prevents expulsion of the water molecules due to squeezing, resulting in a low frictional force. At a high surface energy, although squeezing of the water molecules is restricted, similar to the case of moderate surface energy, dragging occurs at the soil surface-water molecule interface, and the frictional force increases.

• 한국산학기술학회논문지
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• 제10권10호
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• pp.2810-2818
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• 2009

본 연구는 화강풍화토로 구성된 절토사면에서 얕은파괴의 특성을 규명하고자 우리나라의 강우특성에 따른 한계투수계수를 산정하고, 국내에 분포하는 화강풍화토의 대표적 물성을 기준으로 절토사면의 파괴면까지의 수평거리, 사면의 경사각, 사면높이 그리고 강우로 인한 포화깊이 등에 따른 안정해석을 수행하여 그 결과를 분석하였다. 한계투수계수를 분석한 결과 국내의 지역별 강우특성을 고려한 최대 한계투수계수가 $7.16{\times}10^{-4}cm/sec$의 값으로 나타났다. 최대 한계투수계수 이하의 값을 갖는 국내의 화강풍화토로 구성된 절토사면에서 한계강우강도 이하의 강우가 최소 강우지속시간보다 오랫동안 지속될 때에는 포화깊이에 따른 얕은파괴의 검토가 고려되어져야 할 것으로 판단되었다. 또한, 가상파괴면이 발생하는 수평거리, 포화깊이, 강도정수 변화에 따른 사면안전율의 변화관계를 통해 절토사면의 얕은파괴 특성을 파악 할 수 있었다.

• 한국생활과학회지
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• 제20권5호
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• pp.1025-1034
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• 2011

The purpose of this study was to examine the evaluation of fabric characteristics on the drapability, texture image and preference of blouse fabrics, and to analyze the effects of the texture image, objective and subjective drapability on the preference. As specimen, silk and polyester fabrics were collected. 52 female subjects evaluated 16 specimens with semantic differential scale of 18 fabric image and 20 sensibility. Data were analyzed through factor analysis, pearson correlational coefficient using spss win 12.0. For the evaluation, structural characteristics such as fiber contents, weave type, weight and thickness were analyzed. The results were as follows: The evaluation results of objective and subjective drapability showed differences. Sensory image factors of blouse fabrics were 'surface smoothness', 'elasticity', 'weight' and 'flexibility'. Sensibility image factors were 'elegance', 'classic', 'characteristic' and 'mannish'. 'Elegance', 'classic' and 'characteristic' of sensibility images showed high correlation with 'surface smoothness' and 'elasticity' of sensory image, also 'mannish' of sensibility image showed significant correlation with 'weight' of sensory image. The significant fabric characteristics affecting objective drapability were density, weight, thickness. The significant texture image factors affecting objective drapability were 'weight', 'flexibility' of sensory image and 'elegance' of sensibility image. On the other hand, the significant factors affecting subjective drapability were thickness of fabric characteristics and 'elegance', 'characteristic', 'mannish' of sensibility images. 'Elegance', 'characteristic' and 'classic' of sensibility image, 'elasticity' of sensory image and subjective drapability affected on the purchase preference.

• 대한임상전기생리학회지
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• 제8권1호
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• pp.23-29
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• 2010

Purpose : This study is to offer clinical primary data that examines the change of imaging structure and the quantitative evaluation of muscle activity on myofascial trigger points. This study examines neuromuscular physiological characteristic by comparing the differences in physical findings, pressure pain threshold, imaging, and electrophysiological characteristics in latent and active myofascial trigger points muscle and normal muscle through the following experimental procedures. Methods : The participants for the study were thirty-three adults in their twenties. We divided three groups into normal, latent and active myofascial trigger points groups by physical findings. We analyzed the results of measured pressure pain, threshold for pain, ultrasound imaging perform for structure characteristic of muscle, surface EMG according to type of muscle contraction for function of muscle contraction. Results : Significant differences were indicated in pressure pain threshold (p<0.05). Significant differences were discovered in the ultrasound imaging analysis. There were increases in muscle Echogenicity white area index (p<0.001). There were significant differences that decrease in %MVIC (p<0.05), increase in MDF (p<0.05). Conclusion : From these results, active rnyotascial trigger points muscle showed quality deterioration on ultrasound imaging and decreased function of muscle contraction, increased motor unit action potential of II type fiber, and electrophysiologically. Imaging structure and neuromuscular physiological characteristic can be diagnostic and quantitative analytical techniques for myofascial pain syndrome and a primary factor that reflected in physical therapy intervention.

• 한국표면공학회지
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• 제44권5호
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• pp.220-225
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• 2011

304 stainless steel plate was colored by hot dip and electrochemical treatment in a solution containing sulphuric and chromic acids. In the process, treatment variables such as operating time and methode were changed. The surface characteristics that changed by the treatment of the samples such as surface composition, oxide film thickness, color, surface roughness and reflectivity were studied. Surface composition was varied as follows. Fe was decreased, but Cr and O were increased. Ni was increased until 20 min, but reveals decreasing tendency as time passed after that. These means the surface film becomes chrome rich oxide phase as the treatment times increase. The thickness of film was about 220 nm at 30 min by dip treatment and it reduced as the treatment times increased. On the other hand, the thickness was about 150 nm at 10 min by electrochemical method and it doesn't increased with time. Surface color changed from metallic white of the base plate to gray, black, red, and green-blue, gradually, as the treating time increased. The reflectivity of colored surface measured by UVVIS-NIR spectrophotometer was reduced from max 38% of basis metal to min 3.5%.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.1205-1208
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• 2005

By adding user interface to the usual router, an improved functional router is implemented in this paper. Due to the massive amount of spatial data processing, spatial information processing area has been rapidly grown up in recent years based on powerful computer hardware and software development. Spatial index structures are the core engine of geographic information system(GIS). Analyzing and processing of spatial information using GIS has a lot of applications and the number application will be increased in the future. However, study on the under ground is in its infancy due to invisible characteristic of this information. This paper proposes the sub-surface fault detection system using the sub-surface layer information gathered from elastic wave. Detection of sub-surface fault provides very important information to the safety of above and sub-surface man made structures. Development of sub-surface fault detection system will serve as a pre-processing system assisting the interpretation of the geologist.

• 대한기계학회논문집
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• 제15권2호
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• pp.685-692
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• 1991

The pool boiling behavior of a heated surface has been investigated experimentally, focusing on the cases when only a part of the contact surface is heated. Characteristic boiling curves are obtained with circular metal surface test pieces heated below while immersed in Refrigerant-113. Locally heated test pieces are fabricated by inserting a heating block at the center inside a larger conducting block. Overall heat transfer rates are measured while the experimental conditions are systematically varied. The local temperature profiles along the radius are measured for conducting blocks. It is found that the conjugated boiling condition exists and the total heat fluxes should be correlated to a suitably defined temperature difference.