• 대한기계학회논문집
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• 제13권1호
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• pp.115-124
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• 1989

본 연구에서는 2상계 스테인리스강의 모재,용접재 및 용접후 열처리재 3종류의 경우에 대하여 피로크랙 전파특성을 피로크랙의 하한계치 근방에서 금속조직적인 영향을 검토하기 위하여, 각 조건에 대한 피로크랙 전파속도의 하한 계치를 구하였고 피로식검후의 파단면을 주사전자현미경(SEM)으로 관찰하였다. 용접재에 대하여는 용착부 부근 용접열영향부의 입경측정, .alpha./.gamma.상의 체적비교율의 변화량 측정 및 용접재와 용접후열처리재의 잔유응력분포측정을 통하여 피로크랙의 하한계특성에 미치는 여러가지 영향인자에 대하여 검토하였다.

• 한국표면공학회지
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• 제43권3호
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• pp.127-131
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• 2010

Adhesion of DLC film is very significant property that exhibits wear resistance, chemical inertness and high hardness when being deposited to metal substrate. This study was considered that change adhesion of DLC film produced by Plasma Enhanced Chemical Vapor Deposition can be presented through inserting interlayer (Cr, Si-C:H). The thickness of interlayer was result of changing adhesion and residual stress. It was showed that the maximum 12 N of adhesion is on DLC film of Cr interlayer, and that a tendency is to be increased residual stress depend on the thickness. DLC film of Si-C:H interlayer represented 16 N of adhesion at $1{\mu}m$, whereas adhesion is decreased when the thickness is increased. For the interlayer at multi-layer, it was the best that adhesion of Cr/Si-C:H/DLC film was 33 N. Si-C:H interlayer at DLC film controled adhesion of the whole film. It was relaxed the internal stress of DLC film produced by inserting Cr, Si-C:H interlayer.

• 대한기계학회논문집
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• 제13권5호
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• pp.901-910
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• 1989

본 연구에서는 2상계 스테인리스강의 모재 및 용접부에 대하여 대기중의 피로시험과 인공해수중의 부식피로 시험을 모재부와 용접부의 .alpha.,.gamma.상의 상비율 변화에 따른 조직의 변화 및 용접잔유응력의 영향이 크랙전파에 미치는 영향을 검토하였다. 응력-스트레인의 히스테리스곡선에서 균열닫힘 거동을 실측하고 이들의 결과로 부터 유효응력확대계수와 균열전파속도와 관계를 정리하여 이들의 문제를 해석하였다.

• Steel and Composite Structures
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• 제41권5호
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• pp.731-746
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• 2021

The purpose of this paper is to investigate the axial bearing capacity and residual properties of steel reinforced recycled aggregate concrete (SRC) column after elevated temperature. A total of 48 SRC columns were designed for the static loading test after elevated temperature. The variables include replacement ratios, designed temperature, target duration, thicknesses of cover concrete, steel ratios and stirrup spacing. From this test, the mass loss ratio and stress load-deformation curve were obtained, and the influence of various parameters on residual bearing capacity were analyzed. ABAQUS was used to calculate the temperature field of specimens, and then got temperature damage distribution on the cross-section concrete. It was shown that increasing of the elevated temperatures leaded to the change of concrete color from smoky-gray to grayish brown and results in reducing the bearing capacity of SRC columns. The axial damage and mechanism of SRC columns were similar to those of reinforced natural aggregate concrete columns at the same temperatures. Finally, the calculation method of axial compressive residual bearing capacity of SRC columns recycled concrete columns after high temperature was reported based on the test results and finite element analysis.

• 대한통합의학회지
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• 제3권3호
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• pp.89-94
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• 2015

Purpose : This study was analyzed to researched the improvement of the posture and breathing ability on correction method of posture and breathing exercise in Forward Head Posture(FHP) Method : Eighten forward head posture subjects participated in this study. The control group applied to correction method of posture and the experiment group applied to correction method of posture with breathing exercises. Results : The results showed significant improvement in Craniovertebra-Angle on each two group(P<0.05). All the other result showed non-significant in respiratory(Tidal volume, Expiratory residual volume, Inspiratory residual volume) But value of result is slightly improved in after exercise. Conclusion : CVA angle is increased in each group but not increased between experiment group and control group. Total Volume(TV), Inspiratory Reserve Volume(IRV) and Expiratory Reserve Volume(ERV) are a little increased.

• 한국세라믹학회지
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• 제55권3호
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• pp.299-306
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• 2018

In order to improve the hardness of commercial bone china, we suggested a chemical strengthening process and new glaze for its process. New glaze contained about two times more $Na_2O$ and $Al_2O_3$ and had a higher transition temperature than that of commercial frit. Chemical strengthening enhanced the hardness of the new glaze-coated bone china by over 30% compared to that of commercial product. The change of glaze composition influenced potassium ion diffusion distance and depth of strengthened layer during chemical treatment. After chemical strengthening of new glaze-coated bone china, the residual compressive stress inside the glaze was measured and found to be greater than 160 MPa.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2002년도 학술대회 논문집
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• pp.259-262
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• 2002

Cable-in-Conduit Conductors (CICC) have been used for fabrication of nuclear fusion magnets. Bending process is included in fabrication of superconducting magnet such as termination of conductors. Because of plastic deformation by bending process, there can be a large residual stress and change of shape in bent conductors. Void volume fraction in conductors is also changed by bending process. In this study, Commercial code was used to analyze the bending process at various bending curvature radius. The calculated residual stress of conductors bent at less than about 40cm curvature radius exceeded the allowable stress.

• Tribology and Lubricants
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• 제10권2호
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• pp.51-55
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• 1994

Rolling friction test was carried out to investigate the effect of the wear amount on rolling contact fatigue process in lubrication oil. The methods of this process were conducted at two Hertzian contact pressure and three slide ratio in each case by employing normalized and annealed carbon steel. During process of the rolling contact fatigue, the number of rotation until surface damage was occurred, the wear amount of rolling contact surface, and residual stress and half-value breadth using X-ray reflection on rolling contact surface were investigated. The result of this study shows that rolling contact fatigue process was directly influenced by wear trend and was confirmed by change of residual stress and half-value breadth on rolling contact surface.

• 상하수도학회지
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• 제19권1호
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• pp.92-97
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• 2005

This research is to investigate the effect of the dual coagulant using inorganic coagulants($AICl3{\cdot}6H2O$) and polymer on the coagulant process. Jar-test was conducted by using Kaolin injected raw water. PDA(Photometric Dispersion Analyzer) equipment in order to analyze the size of the particles and the characteristics of the shapes. The change in the rate of sample ores' residual deposited after coagulants were also compared. According to the result derived from this experiment, the concentration of inorganic coagulant reduced 50% and the residual was lower by using dual coagulants compared to using single coagulant. However the dual coagulant required sufficient mixing time, and affected particle characteristics, with the effect of the injection order of coagulants, the simultaneous injection of inorganic coagulant and polymer showed the most effective in the particle removal.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 추계학술대회 논문집
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• pp.149-153
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• 2001

This paper presents an end-point control of 1-link flexible arm tip-mass by using fuzzy position control algorithm. The arm is mounted on a translational mechanism driven by a ballscrew, whose rotation is controlled by a DC servomotor. Tip position is controlled so that it follows a desired position. Feedback signal is composed of both tip displacement error and change of error. This paper gives tip responses according to the variations of tip-mass and beam length, and the effects of reducing the residual vibrations occurring at the end-point. In the case of the residual vibrations of tip displacement, fuzzy control has better results than the PD-control.