• Proceedings of the KSME Conference
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• 2001.06a
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• pp.157-162
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• 2001

Fretting is a potential degradation mechanism of structural components and equipments exposed to various environments and loading conditions. The fretting degradation, for example, can be observed in equipments of nuclear, fossil as well as petroleum chemical plants exposed to special environments and loading conditions. It is well known that a cast stainless steel(CF8M) used in a primary reactor coolant(RCS) degrades seriously when that material is exposed to temperature range ken $290^{\circ}C{\sim}390^{\circ}C$ for long period. This degradation can be resulted into a catastrophical failure of components. In the present paper, the characteristics of the fretting fatigue are investigated using the artificially aged CF8M specimen. The specimen of CF8M are prepared by an artificially accelerated aging technique holding 1800hr at $430^{\circ}C$ respectively. Through the investigations, the simple fatigue endurance limit of the virgin specimen is not altered from that obtained from the fatigue tests imposed the fretting fatigue. The similar tests are performed using the degraded specimen. The results are not changed from those of the virgin specimen. The significant effects of fretting fatigue imposed on both virgin and degraded specimen on the fatigue strength are not found.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.8
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• pp.1287-1293
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• 2001

Fretting is a potential degradation mechanism of structural components and equipments exposed to various environments and loading conditions. The fretting degradation, for example, for example, can be observed in equipments of nuclear, fossil as well as petroleum chemical plants exposed to special environments and loading conditions. It is well known that a cast stainless steel(CF8M) used in a primary reactor coolant(RCS) degrades seriously when that material is exposed to temperature range from 290$\^{C}$∼390$\^{C}$ for long period. This degradation can be resulted into a catastrophical failure of components. In the present paper, the characteristics of the fretting fatigue are investigated using the artificially aged CF8M specimen. The specimen of CF8M are prepared by an artificially accelerated aging technique holding 180hr at 430$\^{C}$ respectively. Through the investigations, the simple fatigue endurance limit of the virgin specimen is not altered from that obtained from the fatigue tests imposed the fretting fatigue. The similar tests are performed using the degraded specimen. The results are not changed from those of the virgin specimen. The significant effects of fretting fatigue imposed on both virgin and degraded specimen on the fatigue strength are not found.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.2
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• pp.243-251
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• 1989

Assuming plastic zones spreading out on each slip plane of the two materials under out-of-plane shear loading, the size of each plastic zone is computed. The effect of the different frictional shear stresses in the two materials on the size of each plastic zone and the relative displacement at the crack tip are investigated. The relation between the J-integral in this model and the relative displacement at the crack tip is also obtained.

• Journal of the Earthquake Engineering Society of Korea
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• v.13 no.6
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• pp.87-98
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• 2009

It is well known that reinforcement details in the plastic hinge region of bridge piers give the most important effects on the seismic performance of bridges, from investigations of bridge failures in many earthquake events and in laboratory tests. Longitudinal reinforcement details give larger effects than lateral reinforcement details do. The lap-spliced longitudinal steel shows slip during earthquake events, which results in low ductility and inadequate seismic performance. However, before the issue of the earthquake design code, a considerable number of bridge piers were constructed with lap-spliced longitudinal steel in the plastic hinge region. Therefore, a large amount of research has been conducted on the seismic performance and retrofit of circular and rectangular shaped bridge columns with lap-spliced longitudinal steel. However, research on wall type piers is very limited. This paper investigates the seismic performance of a pier wall by a quasi-static test in the weak axis direction and proposes a retrofit method. From the test with variables being the longitudinal steel detail and the transverse steel amount, it is shown that the currently used definition of yield displacement is not adequate. Therefore a new definition of yield displacement for the ductility investigation for a pier wall is proposed. In addition, a retrofit method by steel plates and bolts is proposed to improve ductility, and test results show that slip of the longitudinal steel is prevented by up to a considerably large displacement.

• Journal of the Korean Society of Clothing and Textiles
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• v.19 no.3
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• pp.483-503
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• 1995

The purpose of this study was to clarify the origin which have misused terms, analyze Its meanings and suggest the unified terms. The content of this study are as follows. The origin of the terms in western dress is different with the areas of cultural influence. Japanese occupied much more than other languages in the apparel industry after the civilization. and English has dominated in the educational filed since 1945 the Liberalization. French, German, Portuguese, Spanish, Dutch are added. These languages came to the clothing field via Japanese and English or directly from the countries. 망토(manteau프), 메리야스(medias스), 러닝셔츠(일) 라사(raxa네), 오트 쿠튀르(Haute Couture 프), 비로드(veludo 포), etc. However the words of foreign origin have misused or corrupted until now a days. 마이 (재킷, 상의), 노 슬립, 소데나시 (슬리브리스, 민소매) 넌라쟈(브래지어), 노타이, 노타이샤쓰(오픈칼라 셔츠, 넥타이를 매지 않은 셔츠) 와이샤쓰(드레스 ttu츠), etc. And also these terms are confused in using because of the word's diversity, the different nationality, change of the marking rules, and the difference between the education and production field terms. On the others hand, this study explained the differences between western costume and Korean costume as the clothing manufacture terms were translated to Korean. bodice-길, collar, neckline-깃, belt, sash-(허리)띠 And then the untied terms were suggested through the comparison production field and educational area (including schools and institutes). lapel, 라펠(학교용어) (학원용어), 가에리 (일) (의류산업 현장용어), 아랫깃(통일어) By the way, this study involved the origin of and misused teams in sewing and presented the unified terms. 미까시 (X)-미 카에시(일) - 안단($\bigcirc$), 이새(X)―홈줄임 ($\bigcirc$) As the above , the characteristics of clothing terms which have misused are Japans,;e, corrupt Japanese, false reports foreign words via Korean, Japanese, compound words of Korean and Japanese, compound words of English and Japanese. And also the words of foreign origin in clothing had the following tendency in the marking system. There are ellipsis of form, sex, timber, grammatical case '-ing', '-ed' in adjective and long vowels express to short vowels. We can see this phenomena as the rule of curtailment labor.

• Korean Journal of Materials Research
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• v.10 no.2
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• pp.155-159
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• 2000

Microstructural processes during high cycle fatigue are investigated according to plastic-strain hardening, crack formation, crack propagation and fracture. It is shown that the fatigue test resembles the uniaxial tensile test. The logarithm of the number of cycles to failure is proportional to the elongation in the tensile test. Under high cycle fatigue test, the strain is normally elastic. If the strain is absolutly elastic, fatigue could not result. But this is over simplication. Nearly all metals undergo a minor amount of plastic strain even at low stress. Damage accumulation leadling to crack formation can continue in the persistent slip bands at very low average plastic strain amplitude. In the ten­s sile test the overall specimen follows the failure procedure whilst in the high cycle fatigue test the local persistent slip band follows the failure procedure. However accumulations of strain per unit volume in the deforming region before failure in both cases are equal locally.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.4
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• pp.39-49
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• 2003

This research is a part of a research program to develope a new design method for reinforced concrete bridge columns under axial load and cyclic lateral load. A nonlinear analytical method is proposed to obtain moment-curvature relationship and lateral load-displacement relationship. Various analytical models that contribute seismic behavior of reinforced concrete bridge columns are adopted and modified by comparing quasi-static test results of reinforced concrete columns with spirals of circular hoops. The analysis adopts confined concrete model, longitudinal reinforcement test result of reinforced concrete columns with spirals or circular hoops. The analysis adopts confined concrete model, etc. The results obtained using the propose analytical method agree well with test results and give conservative estimations particularly for deformation capacity and ductility.