단일 시험편법에 의한 극저온용 구조재료의 파괴인성 저하에 관한 연구

권일현,Kwon, Il-hyun 대한기계학회 1998 大韓機械學會論文集A Vol.22 No.2

This paper was investigated degradation of the fracture toughness caused by sensitizing heat-treatment of the cryogenic structural material JN1 base metal using unloading compliance method reported as useful a method in evaluating the elastic-plastic fracture toughness at cryogenic temperature. The specimens used in this paper were 20% side-grooved 0.5T-CT specimens which were machined in the JN1 base metal. Also, to investigate cryogenic fracture toughness of the fusion line region in the JN1 GTA weldments, it was also used 20% side-grooved 0.5T-CT specimens that was machined fusion line to located in the middle of the specimen. The cryogenic fracture toughness values of the JN1 base metal were significantly decreased with increasing the time and temperature of the heat treatment. The fracture toughness value obtained from the fusion line specimen was invalid, but it was lower value than that of the JN1 base metal. Especially, this value was approximately equal with that obtained from the JN1 650.deg. C-5h heat-treated material.

핵 융합로 구조재료의 예민화 열처리에 따른 극저온 파괴거동 및 분극특성

권일현,정세희,Kwon, Il-Hyun,Chung, Se-Hi 대한기계학회 1998 大韓機械學會論文集A Vol.22 No.2

The cryogenic fracture behaviors of austenitic stainless steel HN2 developed for nuclear fusion reactor were evaluated quantitatively by using the small punch(SP) test. The electrochemical polarization test was applied to study thermal aging degradation of HN2 steel. The X-ray diffraction(XRD) analysis was conducted to detect carbides and nitrides precipitated on the grain boundary of the heat treated HN2 steel. The mechanical properties of the HN2 steel significantly decreased with increasing time and temperature of heat treatment or with decreasing testing temperature. The integrated charge(Q) obtained from electrochemical polarization test showed a good correlation with the SP energy(ESP) obtained by means of SP tests. From the results observed in the x-ray diffraction and anodic polarization curve, it was known that the material the grain boundary. Combining SP test and electrochemical polarization test, it could be useful tools to non-destructively evaluate the cryogenic fracture behaviors and the aging degradation for cryogenic structural material.

극저온용 구조재료의 파괴인성평가법에 관한 연구

권일현,정세희,Kwon, Il-Hyun,Chung, Se-Hi 대한기계학회 1998 大韓機械學會論文集A Vol.22 No.1

This paper was undertaken to develop the fracture toughness testing method using small and single specimen compared to the conventional method in evaluating elastic-plastic fracture toughness of the superconducting magnet structural material at cryogenic temperature. The elastic-plastic fracture toughness test was conducted by using the unloading compliance method recommended by ASTM E813-89 to accomplish the above purpose. And, the 20% side-grooved 0.5TCT and 1TCT specimens were used to evaluate the fracture toughness by using as possible as miniaturized CT specimen. The unloading compliance method was a very useful method in evaluating elastic-plastic fracture toughness at cryogenic temperature. It could be taken valid fracture toughness values by using 20% side-grooved 0.5TCT specimen recommended by ASTM E813-89.

전기화학적 재활성화 분극시험에 의한 터빈부재의 열화손상 평가

권일현,백승세,류대영,유효선,Kwon, Il-Hyun,Baek, Seung-Se,Lyu, Dae-Young,Yu, Hyo-Sun 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.7

The extent of materials deterioration can be evaluated accurately by mechanical test such as impact test or creep test. But it is almost impossible to extract a large test specimen from in-service components. Thus material degradation evaluation by non-destructive method is earnestly required. In this paper, the material degradation for virgin and several aged materials of a Cr-Mo-V steel, which is an candidated as structural material of the turbine casing components for electric power plant, is nondestructively evaluated by reactivation polarization testing method. And, the results obtained from the test are compared with those in small punch(SP) tests recommended as a semi-nondestructive testing method using miniaturized specimen. In contrast to the aged materials up to 1,000hrs which exhibit the degradation behaviors with increased ${\Delta}[DBTT]_{SP}$, the improvement of mechanical property can be observed on the 2,000hrs and 3,000hrs aged materials. This is because of the softening of material due to the carbide precipitation, the increase of ferritic structures and the recovery of dislocation microstructure by long-time heat treatment. The reactivation rates($I_R/I_{Crit},\;Q_R/Q_{Crit}$) calculated by reactivation current densityt ($I_R$) and charge($Q_R$) in the polarization curves exhibit a good correlation with ${\Delta}[DBTT]_{SP}$ behaviors.

슈퍼 오스테나이트 스테인리스강의 열화손상에 대한 비파괴적 평가

권일현,백승세,유효선,Kwon, Il-Hyun,Baek, Seung-Se,Iino, Y.,Yu, Hyo-Sun 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.7

This research was undertaken to clarify effects of thermal aging on electrochemical and mechanical properties of superaustenitic stainless steel and to detect the material degradation nondestructively. The steel was artificially aged at $300{\sim}650^{\circ}C$ for $240{\sim}10,000h$ and the mechanical properties were investigated at $-196{\sim}650^{\circ}C$ using small punch(SP) test. Also, the change in electrochemical properties caused by effects of thermal aging on superaustenitic stainless steel was investigated using electrochemical anodic polarization test in a KOH electrolyte. Carbides and ${\eta}-phase(Fe_2Mo)$ precipitated in the grain boundaries seem to deteriorate the mechanical properties by decreasing cohesive strength in the grain boundaries and to promote the current density observed in electrochemical polarization curves, The electrochemical and mechanical properties of superaustenitic stainless steel decreased significantly in the specimen aged at $650^{\circ}C$ corresponding to the sensitization temperature for conventional austenitic stainless steels.

문화컨텐츠산업과 만화에 관한 연구 - 인디만화를 중심으로 -

권일현(Il Hyun Kwon),고은나(Eun Na Koh) 한국일러스아트학회 2002 일러스트레이션학 연구 Vol.11 No.-

Recently the rapid development in technology has generated new mediums and reborn the cultural industries in the traditional concepts as a new pattern of existing. As one kind of cultural industries, comics has been recognized for its economic value and made a display of its influence in the environments of Internet. Indi-comic which gushouts the discussion of an age by the unrestricted conception is an economic logic, a political spirit and an aesthetic attitude which is brought about from the level that is quite different from the bisection theory of `overground versus underground`. Indi-comic doesn`t always express positive aspect, but I want to set a much value on the culture of resistance which takes a look at this world whereas it expresses a visual characteristic and indivisuality by constructing an independant genre itself.

한국전통 보자속에 은유된 현대 포장디자인 요소

권일현(Il-Hyun Kwon),남용현(Young-Hyun Nam) 한국콘텐츠학회 2007 한국콘텐츠학회논문지 Vol.7 No.12

문헌과 풍속도를 통해 보자기의 용도와 쓰임새를 알아보고, 민보와 상용보를 중심으로 그 가치와 기능을 분석 하였다. 산업사회 가방문화의 단일성과는 달리 보자기는 다양성과역동성, 가변적수용성, 2차원과 3차원이 동시에 공존하고 있다는 것을 발견했고, 보자기를 만드는 과정에 있어서 짜투리 천조각의 재활용성은 세계 어느 전통 운반기구의 문화 에서도 찾아볼 수 없는 친환경적요소를 내재하고 있다. 이런 다의적 요소들은 기술과 재료의 발달로 다양한 기능으로 컨버전스 되어 새로운 관점의 포장디자인이 가능해진다. 이를 현대 포장디자인 관점에서 분석하여 복합적이고, 융합적인 다양한 기능의 현대 포장디자인 방향을 제시한다. In this study, the use of wrapping cloth was studied by examining documents and drawings from the past that reflect the life of people of the time with a focus on minbo (a wrapping cloth used by civilians) and gungbo (a wrapping cloth used by the ruling class). Unlike the bag culture of industrialized society, wrapping cloth has diversity, dynamic and receptiveness to changes as well as coexistence of 2 and 3-dimension. Environment-friendliness of recyclability of the cloth used for making wrapping cloth is not found in any other traditional transportation device cultures of the world. Such polysemous elements converge into a various functions with the development of technology and raw material and allow a package design from a new perspective. This study analyzes the above factors from a package design perspective to suggest an innovative modern package design that has fusional, diverse features.

한국 전통 보자의 유니버설 디자인 재해석에 관한 연구 : 캐리어백 디자인을 중심으로

권일현 ( Il Hyun Kwon ),한기웅 ( Ki Woong Han ) 한국기초조형학회 2007 기초조형학연구 Vol.8 No.4

아연도금 강판과 고장력 강판 3겹 점용접물의 용접특성 평가

권일현(Il-Hyun Kwon),김회현(Hoi-Hyun Kim),백승세(Seung-Se Baek),양성모(Seong-Mo Yang),유효선(Hyo-Sun Yu) 한국자동차공학회 2005 한국 자동차공학회논문집 Vol.13 No.5

In general, multi-lap spot weld joints are frequently present in automobile. Most research, however, has been focused on the single-lap spot weld joints until now. In this paper, tensile-shear strength tests are performed to examine the weldability of 3-lap spot joint welded by using the high strength steel sheet and the zinc coated steel sheet. The indentation depth and nugget diameter are used to propose the optimum welding conditions. The weldability is affected by the welding current and welding time for 3-lap spot joint. Meanwhile the expulsions is found to decrease with the increase of electrode force. The optimum welding conditions are presented for 3-lap spot joints of high strength steel sheet and zinc coated steel sheet.

질소처리된 슈퍼오스테나이트 스테인리스강의 시효손상 평가

권일현(Il-Hyun Kwon),이송인(Song-In Lee),백승세(Seung-Se Baek),Y. Iino,유효선(Hyo-Sun Yu) 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.2001 No.8

To ensure the structural integrity and design life-time of the superaustenitic stainless steel containing 0.17wt% N and 5.5wt% Mo induced by artificially thermal aging treatment, material damage evaluation of the superaustenitic stainless steel was conducted by small punch (SP) and electrochemical polarization technique. The material damage in high-temperature and short-time aged material was higher than that in low-temperature and long-time aged material. A reasonable agreement was found between the results obtained from small punch and electrochemical polarization tests, depending on SP energy and the current density corresponding to the passivation film formation.