• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.452-457
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• 2000

The object of this study is to develop a reliable FEM simulation technique for the analysis of can making process using PAM-STAMP software. The processes consist of doming and necking in addition to drawing, redrawing. After body making process, this study analyzed the stability for internal pressure by simulating buckling test. Through these technique, we estimated the dome reversal pressure of steel D&I Can for various can profile and process conditions. From this study, we found the cause and mechanism of wrinkling during necking process. This mechanism is largely affected by can wall thickness and the clearance between knock out punch and necking die. The dome reversal pressure improves with increasing dome depth. These results validate the usefulness of the developed simulation technique for the analysis of body making process and optimization of the dome profile.

• 한국해양공학회지
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• 제16권2호
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• pp.67-71
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• 2002

Damage process of CFRP laminates was characterized by Acoustic Emission (AE). The main objective of this study is to determine if the sources of AE in CERP laminates could be identified from the characteristics of the waveform signals recorded during monotonic tensile test. The time history and power spectrum of each individual wave signal recorded during test were examined and classified according to their special characteristics. The wave from and frequency of AE signal from a specimens is an aid to the determination of the extent of the different fracture mechanism such as matrix crack, debonding, fiber pull-out and fiber fracture as load is increased. Four distinct types of signals were observed regardless of specimen condition. The result showed that the AE method could be effectively used for analysis of fracture mechanism in CFRP laminates.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.664-670
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• 2010

The study on mechanical behavior of the structure at the site includes experimental method and numerical analysis method. Experimental method is categorized into true-scale test and laboratory model test. A laboratory model test is to monitor the failure mechanism with a model simulated similar with a real ground so as to identify the quantitative result, while a true-scale model test is the approach which enables to identify the potential problems that may occur with a simulated construction situation similar with a real site circumstance. Thus this study was intended to carry out the experimental test of non open-cut excavation by pipe roof method which is mostly common in domestic sites. as well as was aimed at identifying the ground behavior occurred during pipe penetration using laboratory model test. Appropriate reduced-scale model was selected, taking into account of domestic geological characteristics and operation characteristics of traditional and high-speed rail trains and the qualitative evaluation of displacement was carried out based on a certain ground loss volume depending on excavation after categorizing trackbed settlement pattern by depth of top soil.

• 한국가구학회지
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• 제22권1호
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• pp.18-25
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• 2011

This experiment was carried out to investigate the effects of nail diameter, driving distance from end on the nail check length, and the effects of nail diameter, prehole for nail driving, and nail driving slope on the nail withdrawal resistance, by the static test of universal testing machine. The test specimen were Japanese cedar (Cryptomeria japonica D. Don.) boards grown in southern district of Korea, and the nails for test were 2.02～4.82 mm in diameter. After nail driving, the back face checks of test boards were longer than the surface checks. The optimum nail diameter without checks or loss of nail withdrawal resistance were below 10% of board width and the optimum driving distance from end of boards were ten multiple of nail diameter. The relation between nail diameter (x) and withdrawal resistance (y) was linear and the regression formulae for Japanese cedar board was y = 8.66x + 7.6 ($R^2=0.978$). As both of the prehole diameter and driving slope were increased, the withdrawal resistances were significantly decreased.

• 열처리공학회지
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• 제13권2호
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• pp.71-84
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• 2000

A study on adhesion and wear resistance of VC(vanadium carbide) coating on die steels, STD11 and STD61, has been carried out. The VC coating on the die steels was made by immersing them in molten borax bath, a kind of TRD(thermo-reactive deposition and diffusion). Adhesion strength and wear resistance were investigated using scratch test, indentation test and plate-disc test(Ogoshi type) respectively. The influence of sliding distance on the amount of wear has been determined and dominant wear mechanisms has been characterized using optical microscopy, scanning electron microscopy and EDS spectroscopy. The critical adhesion strength($L_c$) between VC coating layer and substrate(STD11) was increased to 60N($L_c$) in the scratch test. In the case of STD61, the strength increased to 24N. The wear resistance of VC coated die steels was excellent because the diffusion layer formed just below the coating layer. The dominant wear mechanism was identified as adhesive wear for VC coating die steels which were worn by combination of cracking and plucking of VC fragments and disc.

• 한국환경성돌연변이발암원학회지
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• 제18권2호
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• pp.77-82
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• 1998

In order to compare the suppressive effect of galangin on the genotoxicity by N-methyl-N-nitrosourea (MNU) or benzo[a]pyrene B(a)P, in vivo micronycleus test using mouse peripheral blood and in vitro sister chromatid exchange(SCE) test using mouse spleen lymphocytes were performed. MNU or B(a)P-induced micronucleated reticulocytes in vivo was decreased by the simultaneous treatment of galangin. MNU or B(a)P-induced SCEs in vitro was also decreased by the simultaneous treatment of galangin. On the other hand, the determinations of [$^3$H]MNU-induced total DNA binding and methylated DNA were performed to find out the mechanism of action. [$^3$H]MNU-induced total DNA binding was inhibited by the treatment of galangin in calf thymus DNA. HPLC analysis of DNA hydrolysates showed that galangin caused a decrease of 7-methyl guanine and $O^{6}$-methyl guanine in calf thymus DNA. To elucidate the action mechanism of galangin against B(a)P, alteration of B(a)P metabolism was studied. Galangin inhibited B(a)P metabolism in the presence of S-9 mix and decreased B(a)P-DNA binding in calf thymus DNA with S-9 mix.

• 한국지반신소재학회논문집
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• 제9권4호
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• pp.47-55
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• 2010

일반적으로 초연약지반에서는 건설장비의 주행성 확보 등을 위하여 토목섬유와 같은 표층 보강재를 적용하게 된다. 그러나 최근 토목섬유로 표층 처리된 초연약지반의 거동에 관한 많은 고찰이 수행되어 왔지만 대부분의 연구에서 토목섬유와 지반의 경계조건을 적절히 표현하지 못하고 있는 실정이다. 따라서 본 연구에서는 토목섬유와 지반의 경계조건이 토목섬유로 표층처리된 초연약지반의 거동에 미치는 영향에 대하여 수치해석적 고찰을 수행하였다. 수치해석에서는 토목섬유와 지반의 마찰에 대한 경계조건을 다양하게 표현하기 위하여 조인트 요소를 적용하였다. 수치해석의 결과는 기존의 실내모형실험 결과와의 비교를 통하여 그 신뢰성을 검증하였으며 파라메트릭 스터디를 통하여 토목섬유와 지반의 경계조건에 따른 초연약지반의 거동을 규명하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.468-473
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• 2004

The magnetic jack type Control Element Drive Mechanism (CEDM) had been developed and verified through electromechanical testing including the testing of the magnetic force required to lift the control element assembly. It would become inefficient in view of cost and time for parametric studies to be performed by test to improve the CEDM system. So it becomes necessary to develop a computational model to simulate the electromagnetic characteristics of the CEDM in order to improve the CEDM design efficiently. In this paper it is presented that the electromagnetic analysis using a 2D axisymmetric FEM model has been carried out to simulate the operation of the latch magnet of the CEDM to generate a current trace for latch coil. The results show the calculated current trace is very similar to the real current trace taken from the CEDM.

• 대한기계학회논문집
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• 제18권12호
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• pp.3404-3412
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• 1994

The present study was undertaken to investigate the dry wear process and wear mechanism of the alumina ceramics in the purity variation which are used for the mechanical seal, roll, liner and dies. The wear test was carried out under different experimental condition using the wear testing device and in which the annular surface rubbed on dry sliding condition various sliding speed, contact pressure and sliding distance. In case of alumina purity 95%, there was speed range which wear loss increased rapidly owing to enlargement of heat impact force and temperature rise of wear surface. According as the alumina purity increased, wear loss decreased but alumina purity 85% with much void and defect had the most wear loss than any other alumina purity. The friction coefficient of sliding initial stage of wear curves has a large value but according to increase of sliding distance, it decreased owing to drop of the shear strength of wear surfaces.

• Tribology and Lubricants
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• 제12권1호
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• pp.22-28
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• 1996

This study was undertaken to investigate the dry wear characteristics and mechanism of KP-4M steel for plastic molding against SKD 61 hardened by heat treatment. The wear test was carried out under different conditions such as sliding speed, contact pressure, sliding distance, with frictional tester of pin on disc type. The wear loss on variation of sliding speed was little in lower speed range below 0.5 m/sec and in higher speed range above 1.5 m/sec,'but wear loss was high in intermediate speed range. The critical sliding speed, which showed the maximum value of specific wear rate, became lower with increased contact pressure. Increasing the contact pressure, the critical sliding distance Lcr which the wear mechanism changes from severe wear to mild wear was increased due to the decrease of oxidation reaction velocity. Through this study we suggested a model of generation and elimination process of wear debris of KP-4M steel for plastic molding.