전기비저항을 이용한 금속합금 열화도 평가기술

남승훈,유광민,류제천 한국비파괴검사학회 2001 한국비파괴검사학회지 Vol.21 No.5

재료의 노화에 의한 강도 및 인성 감소치를 정량적으로 평가하는 비파괴적 기법의 개발이 시도되고 있으며 전기비저항법도 그 중의 하나이다. 본 연구에서는 전기비저항법의 열화도 평가에의 적용성을 살펴보기 위해 먼저 6종 10 가지의 비자성 금속을 측정시료로 선택하여 직류 two-point probe법(혹은 2탐침법)으로 전기비저항을 계산한 결과와 비접촉식 와전류 방법으로 전기비저항을 측정한 결과를 서로 비교하였다. 또한, 1Cr-1Mo-0.25V강에 대하여 비파괴적 측정 방법인 four-point probe 방법(혹은 4탐침법)을 사용하여 얻은 결과와 기존의 2탐침법을 사용하여 얻은 결과를 서로 비교하여 현장에서의 4탐침 기술의 적용 가능성을 살펴보았다. 1Cr-1Mo-0.25V강에 대하여 2탐침법으로 구한 비저항값과 4탐침법으로 구한 비저항 측정값의 차이는 0.6%였다. 따라서 4탐침법을 사용하여 현장에서 금속소재의 열화도의 비파괴적 평가가 가능하다고 사료된다. Developments of nondestructive evaluation techniques for reduction of strength or toughness by aging of material have been carried out, and the method using electrical resistivity is one of them. In this study, to examine the application of electrical resistivity to the evaluation of the evaluation of degradation of metallic alloy, ten different non-magnetic materials were selected as test materials. Electrical resistivities measured by DC two-point probe method and those measured by non-contact type eddy current method were compared with each other. In addition, to examine the application possibility of four-point probe technology in field, the electrical resistivities for 1Cr-1Mo-0.25V steel measured by DC two-point probe method and four-point probe method were compared with each other. Differences between two measure values for the 1Cr-1Mo-0.25V steel were0.6%. Therefore, the four-point probe method can be applied to the estimation of the degradation of metallic alloy.ect.

한국어 구조 중의성 해소를 위한 부사 문법과 부사 확률 문법

신승은,정천영,서영훈 충북대학교 컴퓨터정보통신 연구소 2001 컴퓨터정보통신연구 Vol.9 No.2

본 논문은 말뭉치에서 추출된 통계 정보와 특징을 기반으로 한 부사 정보를 이용하여 부사 문법과 부사 확를 문법을 구축하고. 이를 적용하여 한국어의 구조 증의성을 해소하였다. 부사들의 사용과 수식 패턴들을 대량의 말뭉치로부터 조사하였고, 많은 패턴들 중에 비교적 규최적인 것들을 부사 문법으로 구축하였다. 그리고 부사 꽉률 문법은 부사와 릭수식어의 상대적 위치 확률과 피수식어의 품사 확률로 구성하였다. 구문 분석기에 의해 생성된 구문 구조들 중 가장 율은 구문 구조를 선택하기 위해 부사 문법과 부사 확률 문법을 적용하였고, 이것으로 부사에 의한 많은 구조적 증의 성들을 해소하였다. This paper describes a Korean structural disambiguation using adverb grammar and Probabilistic adverb grammar. These are made by adverb information which is based on statistical information and special features extracted from corpus. Usage and modification pattern of adverbs are fully investigated in large corpus. and relatively regular ones among a number of patterns are encoded in adverb grammars. And probability of part-of-speech and relative position of modified word is encoded in Probabilistic adverb grammar. Adverb grammar and Probabilistic adverb grammar are applied to select the best passe among parses generated by a general purpose parser. They resolve lots of ambiguities caused by adverbs.

항진균제 알릴아민류의 합성과 생물학적 평가

정병호,조원제,천승훈,박면지,유진철,천문우 朝鮮大學校 1998 藥學硏究誌 Vol.19 No.2

For the development of antifungal agents. modification of naftifine which exhibits significant antimycotic activity was performed by replacing the naphthalene ring of it to hetero cyclic rings such as morpholine. benzothiazole. piperidine and pyridine derivatives. The synthesized compounds were tested in vitro antifungal activity against five different fungi with naftifine as a comparative antimycotic molecule. From the biological evaluation two compounds. (E)-N-(3-phenyl-2-propenyl)-N-(4-piperidinylmethyl)amine(3d) and (E)-N-(3-phenyl-2-propenyl)-N-(3-pyndylmethyl)amine(3D) showed relatively noticeable activity(MIC=50㎍/㎖). On the other hand. the other compounds had no activity.

영상처리기법을 이용한 균열 진전 측정시스템 개발

류대현,남승훈,김용일,김시천 한국산업안전학회 2002 한국안전학회지 Vol.17 No.4

We proposed a new experimental method which is required to easily observe the growth behavior of fatigue cracks. In the proposed method, the image data of cracks were stored into the computer while the cyclic loading was interrupted. After testing, crack length was determined using an image processing software which was developed by authors. By comparing the data measured by the image processing system with those by the manual measurement with a microscope, the effectiveness of the image processing system was established. If the proposed method is used to monitor and observe the crack growth behavior automatically, the time and efforts for fatigue test could be dramatically reduced.

AI/CFRP 혼성튜브의 적층각과 단면형상에 따른 축방향 압궤 특성

김선규,이길성,김성훈,차천석,김정호,양인영 朝鮮大學校 機械技術硏究所 2004 機械技術硏究 Vol.7 No.1

알루미늄은 수송기계용 구조부재로 널리 쓰이고 있으며 복합재료가 이러한 수송기계용 구조부재로 쓰일 때 경량화와 많은 에너지 흡수 측면이 기대된다. 알루미늄 튜브는 CFRP(탄소 섬유 강화 복합재료)튜브에 비해 압궤하중은 낮지만 안정적인 소성변형에 의해 압궤되는 반면 CFRP 튜브는 알루미늄 튜브에 비해 압궤하중은 높지만 불안정한 취성파괴에 의해 압궤된다. 따라서 알루미늄과 CFRP의 조합은 안정적이며 뛰어난 에너지흡수를 기대할 수 있다. 본 연구에서는 알루미늄 원형과 사각튜브의 외측을 CFRP로 감싸 Al/CFRP 혼성튜브를 제작하여 축방향 압궤특성에 관하여 연구하였다. 알루미늄 튜브와 CFRP 튜브의 압궤특성을 기초로 하여, Al/CFRP 흔성튜브의 이방성 재료인 CFRP의 적층각과 단면형상의 변화를 주었다. 실험결과, Al/CFRP 흔성튜브는 알루미늄 튜브의 좌굴을 계기로 하여 CFRP 튜브의 불안정한 취성파괴의 단점을 보완하였다. 경량화 측면에서 단위 질량당 흡수에너지는 원형튜브가 사각튜브에 비해 약 45~70% 이상 높았으며 CFRP 적충각이 90˚일 때 가장높았다. Aluminum materials have been widely used in various vehicle structures. If composite materials are applied to vehicle structures, it is expected that not only the weight of the vehicle is decreased but also it absorb large amounts of energy. Aluminum tubes are lower than CFRP (Carbon Fiber Reinforced Plastics) tubes in the collapse load but absorb energy by stable plastic deformation. On the other hand, CFRP tubes are higher than aluminum tubes in the collapse load but absorb energy by unstable brittle failure. The combination of aluminum and composite may result in stable deformation and excellent energy absorption efficiency. The compressive axial collapse tests were performed to investigate collapse characteristics of Al/CFRP compound tubes which are aluminum tubes wrapped with CFRP outside the aluminum circular and square tubes. Based on collapse characteristics of aluminum tubes and CFRP tubes respectively, the axial collapse tests were performed for Al/CFRP compound tubes which have different CFRP orientation angles and cross-sections. Test results showed that Al/CFRP compound tubes supplemented the unstable brittle failure of CFRP tubes due to ductile nature of inner aluminum tubes. In the light-weight aspect, Absorbed energy per unit mass of circular tubes was higher than square tubes'. Absorbed energy per unit mass showed highest when CFRP orientation angle was 90 degrees.

한우 난소에서의 angiogenin분포와 mRNA발현에 관한 연구

이흥식,이인세,강태천,서제훈,송승훈 대한해부학회 1999 Anatomy & Cell Biology Vol.32 No.1

트리에탄올아민의 혼입률 변화에 따른 콘크리트의 초기 강도발현 특성

황인성,金光華,김규동,이승훈,한천구 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.1(구조계)

In this study, the influence of TEA on early strength development of concrete is discussed in order to reduce a construction period in RC structure by early removal of forms. According to the results, as for the properties of fresh concrete, fluidity of concrete shows no difference, and air content increases with an increase of the mixing ratio of TEA. Setting time is shortened upto mixing ratio of 0.025%, but is retarded above the mixing ratio of 0.025%. The time when compressive strength gains 5MPa is fast in about 2 hours in the case of the mixing ratio of 0.05%, but it is retarded above the mixing ratio of 0.05%. The relativity between compressive strength and the rebound value of P-type Schmidt hammer is also favorable at early age, and compressive strength of 5MPa, which the side forms can be removed, is estimated at the rebound value of 23.

시멘트 제조사 및 W/C 변화에 따른 콘크리트의 초기 강도발현 특성

金光華,裵正烈,김규도,이승훈,한천구 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.1(구조계)

This study is to investigate the influence of cement manufacturing company and W/C on the properties of fresh concrete, strength of hardened concrete and rebound value of P type Schmidt hammer. According to the result, setting time of concrete is shortened with and increase of W/C, and when cement made in A and B corporation is used in concrete, the final setting time is measured at about 10 hours and 13 hours. Compressive strength increases with elapse of time and decrease of W/C, and concrete using cement made in A corporation shows higher compressive strength and rebound value until 24 hours, but from 3rd day, the contrary tendency is shown. As for the properties of early strength, the strength develop fast with decrease of W/C, and the time when compressive strength of 5MPa is gained and the form can be removed, is about 15, 18, 21 hours and 20, 22, 27 hours at the W/C 40, 45, 50% in concrete using cement made in A and B Co. respectively. The correlativity between compressive strength and the rebound value, which a coefficient of correlation is over 0.97, is very favorable. Therefore this method is effective to estimate the strength of removing the form.

블리딩저감용 AE감수제의 개발 및 실용성 검토

황인성,장덕우,김규동,이승훈,한천구 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.2

This study is intended to develop AE water reducing agent for reduction of bleeding and investigate its practical use. According to the results, fluidity and air content increases with an increase of superplasticizer and MC viscosity agent, AE water reducing agent for reduction of bleeding is developed after determining the ratio of superplasticizer and MC viscosity agent as 3:1 to satisfy the same fluidity and air content to conventional concrete and reduce bleeding amount. As the adding ratio of developed AE water reducing agent for reduction of bleeding increases, fluidity also increases, air content satisfies the aimed range, bleeding and sinking amount of concrete are reduced, and compressive strength is almost not different from plain concrete. Therefore, developed AE water reducing agent for reduction of bleeding satisfies the aimed air content in the range of slump 12~21cm, and can also reduce bleeding amount effectively without quality deterioration of compressive strength.

조기강도 발현형 AE감수제를 사용한 콘크리트의 특성에 관한 연구

황인성,김규동,이승훈,한천구 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.2

This study discusses the fundamental properties and early strength development of concrete using AE water reducing agent of early-strength type. According to the result, when AE water reducing agent of early-strength type is used, slump and air content loss is smaller than normal AE water reducing agent. While setting time is retarded with an increase of the adding amount of normal AE water reducing agent, it is maintained constantly regardless of the adding amount and faster than normal AE water reducing agent in the case of AE water reducing agent of early-strength type, and bleeding amount is larger than normal AE water reducing agent especially at early age. At curing temperature of 20℃, early compressive strength gains 5MPa, which side form can be removed, before 16 hours in the case of AE water reducing agent of early-strength type, but early compressive strength development is delayed in the case of normal AE water reducing agent. At curing temperature of 10℃, AE water reducing agent of early-strength type is also better than normal AE water reducing agent especially for early compressive strength development.