데이터베이스 시스템을 이용한 탄소강의 피로강도 및 수명분포

김정규,문준호,김도식,Kim, Jung Kyu,Moon, Joon Ho,Kim, Do Sik 한국강구조학회 1998 韓國鋼構造學會 論文集 Vol.10 No.1

The relational database system on fatigue strength was constructed, and the properties of fatigue life distribution were examined to analyze reliability and safety of metallic materials. Data manipulations were efficiently performed in relational fatigue strength database system using dependency diagram. Regardless of the distribution of fatigue strength, the proposed method, the Robust method and the complementary error function method using probability distribution, successfully estimated parameters of the 3-parameter Weibull distribution. The proposed criterion for estimating non-failure probability showed good results regardless of censoring time. The fatigue life distribution function described as a function of parameters of the Weibull distribution and applied stress ratio produced P-S-N characteristics reasonably. 기계 및 구조물의 안전성과 신뢰성 평가를 위하여 금속재료의 피로강도 데이터베이스 시스템을 구축하고, 이를 이용하여 금속재료의 피로수명 분포특성을 검토하였다. 종속도를 이용하여 구성한 관계형 피로강도 데이터베이스 시스템은 일련의 데이터 관리 및 해석작업을 효율적으로 수행하였다. 또한 Robust 방법과 보상오차함수(complementary error function)를 이용한 3-파라미터 Weibull분포의 파라미터 추정법 및 비파손확률를 검토하기 위하여 제안된 새로운 기준식의 타당성을 검토하였다. 조합분포모델을 이용하여 부하응력비와 Weibull분포의 파라미터 항으로 나타낸 피로수명 분포식은 탄소강의 P-R-N 특성을 해석함에 있어서 좋은 결과를 보였다.

노치부를 가진 Glass/Epoxy 복합재료의 노치강도 평가와 불안정 파괴조건

김정규(Jung-Kyu Kim),김도식(Do-Sig Kim) 한국해양공학회 1993 韓國海洋工學會誌 Vol.7 No.2

The fracture behavior of plain woven glass/epoxy composite plates with a crack is investigated under static tensile loading. It is shown in this paper that the characteristic length associated with the point stress criterion depends on the crack length. To predict the notched tensile strength, the point stress criterion proposed by Whitney and Nuismer are modified. An excellent agreement is found between the experimental results and the analytical prediction of the modified point stress criterion.<br/> The condition of unstable crack growth in the presence of a pre-existing flaw(machined notch) is examined by means of the maximum stress intensity factor Kmax using maximum load Pmax. The values of Kmax evaluated from energy release rate Gmax(the compliance method) and the standard expression normally used for isotropic materials(the isotropic method) indicate a wide difference. Therefore in regard to anisotropy and heterogeneity of the composite materials studied, the modified shape correction factor f*(a/W) is obtained. Kmax evaluated by the compliance method a little or insignificantly depends on the initial crack length a, the specimen thickness B, the crack angle θ and the specimen geometry.

저온하에서 LNG저장탱크용 멤브레인재(STS 304강)의 피로균열진전거동

김정규(JUNG-KYU KIM),김철수(CHUL-SU KIM),김도식(DOSIK KIM),윤인수(IN-SU YOON) 한국해양공학회 2000 韓國海洋工學會誌 Vol.14 No.1

The fatigue crack growth behavior of the cold-rolled STS 304 steel developed for membrane material of LNG storage tank was examined experimentally at 293K, 153K and 111K. The fatigue crack growth rate(da/dN) tends to increase as the stress ratio(R) increases over the testing temperature, when compared at the same stress intensity factor range(ΔK). The effect of R on da/dN is more explicit at low temperatures than at room temperature. The resistance of fatigue crack growth at low temperatures is higher compared with that at room temperature, which is attributed to the extent of strain-induced martensitic transformation at the crack lip. The temperature dependence of fatigue crack growth resistance is gradually vanished with an increase in ΔK, which correlates with a decreasing fracture toughness with decreasing temperature. Fractographic examinations reveal that the differences of the fatigue crack growth characteristics between room and low temperatures are mainly explained by the crack closure and the strengthening due to the martensitic transformation.

유공압부품의 가속 수명 시험법

김도식,김형의,Kim, D.S.,Kim, H.E. 유공압건설기계학회 2010 드라이브·컨트롤 Vol.7 No.1

미스 반 데어 로에(Mies van der Rohe)의 게릭케 주택의 공간적 특성에 관한 연구

김도식(Kim, Do-Sik),이희원(Lee, Hee-Won) 대한건축학회 2013 대한건축학회논문집 Vol.29 No.11

Gericke House, which Mies van der Rohe designed in 1935, although not actually built, is significant in that Mies applied his long pursued idea of the country house to a real site. Mies" idea of the country house, which started in 1923 from the Concrete Country House Project and the Brick Country House Project in 1924, was implemented in the design of the Gericke House, which was rendered with his consideration of the nature of the site and the architectural ideas he had sought to create a practical and sophisticated building. However, this paper argues that the importance of Gericke House lies in the richness of Mies" architectural ideas expressed in it more than in adoption of the idea of country house for it. In so doing, this paper studies the relationship between Gericke House and other previously designed structures, and interprets characteristics of spatial composition of various interior and exterior spaces of the building and its architectural effects. In the end, the paper presents a conclusion on comprehensive architectural effects of the entire building by analyzing Gericke House from its entrance to other areas in sequence. In the process of the analyses, the paper also studies Gericke House in relation with other numerous works by Mies, and attempts to interpret what important status the Gericke House holds in Mies" architectural career.

[의생활 분야] 섬유제품의 품질평가 및 안전성 동향

김도식(KIM DO SIK) 한국생활과학회 2017 한국생활과학회 학술대회 Vol.2017 No.06

산업화와 건축 디자인의 변천에 관한 연구

김도식(Kim, Do-Sik),이희원(Lee, Hee-Won) 한국산학기술학회 2011 한국산학기술학회논문지 Vol.12 No.2

산업화는 근대화 및 근대건축의 탄생에 중요한 역할을 담당하였다. 산업화에 의한 변화와 그 결과물에 대한 믿음은 건축에 대한 사고와 과정도 산업화와 연관 지으려는 시도로 나타나게 된다. 건축을 산업화 과정에 편입시키기 위해서는 건축을 더 이상 과거의 역사주의적 전통이 아니라 실질적인 과학기술과 직접적으로 접목시켜 이해하는 것 이 필요하게 되었다. 20세기 초 건축을 산업생산물의 일종으로 파악하려는 것은 두가지 의미로서 하나는 건축의 결과 물에 대한 인식이며 또하나는 건축의 과정도 산업 생산의 과정으로 이끌어가고자 하는 생각이다. 본 연구에서는 산업 혁명 이후 근대 초기 까지 이러한 산업화에 의한 건축의 변화 과정을 살펴보고 그 의의와 영향을 살펴보는데 그 목적이 있다. Industrialization played an important role in modernization and the birth of modern architecture. The changes caused by the industrialization and people’s faith in its output are reflected in an attempt to associate the concepts and process of architecture with industrialization. In the course of incorporating architecture into the industrialization process, it became necessary to understand the architecture from practical point of view connecting it directly with scientific technology rather than in the context of historical tradition in the past. Understanding architecture as a kind of industrial production signifies two concepts. One is regarding perception of architectural outputs. The other is regarding the intention to proceed architectural process as a process of industrial production. The purpose of this study is to review the changes in the architecture influenced by industrialization from post-industrialization through early modern period and to analyze its significance and influence.

대한민국 육군 사단의 상징에 관한 연구

김도식(Kim Dosik) 한국디지털디자인학회 2008 디지털디자인학연구 Vol.8 No.4

1948년 대한민국의 건국과 함께 국군이 창군되었다. 해방이후 한반도가 분단되고 치안이 혼란에 빠지자 미군정의 영향을 통하여 한국군 육군이 1945년 국방사령부가 설치되고 1948년 정부수립과 동시에 정식으로 육군이 창군되었다. 또한 6·25전쟁 이후 오늘날의 사단의 모습이 갖추어지게 되었으며 각 사단의 고유 부대 표식이 사용 되었다. 이러한 상징들은 기업의 심벌마크와과 같이 커뮤니케이션의 산물이란 측면에서 볼 때 대한민국의 시각적 정체성을 이해하는데 있어 중요한 부분을 차지한다고 할 수 있다. 본 연구에서는 육군의 각 사단의 상징을 이미지로 보고 의미의 대신관계 측면에서 분석하기 위하여 퍼스의 삼원적 기호론을 중심으로 도상 지표 상징의 범주에서 상징체계를 살펴보았다. 육군 사단의 상징표식의 특징은 대개 기호와 지시대상간의 관계성을 유추하기 어려운 상징성이 강한 기호였으나 1940년대 후반부터 1950년대 중 반 사이에 창설된 사단일수록 도상성이 강한 것으로 나타났으며 그 이후에 창설된 사단의 부대 표식들은 통상 명칭의 숫자를 중심으로 지표성이 강한 기호로 분석되었다. 형태는 원형과 방패형이 주를 이루고 있으며 칼라는 평화를 상징하는 청색이 주로 사용되었다. In 1948 the Korean Army was organized with the establishment of Korea. As the Korean Peninsula was separated and public security became unstable after the liberation the headquarters for national defense were established in the Korean army in 1945 under the influence of the U. S. military government and the regular army was organized in the same year of 1948 when the Korean government was established. In addition since the Korean War army divisions of today have been formed and symbols which stand for individual divisions have started to be used. It can be thought that these symbols play an important role in understanding the visual identity of Korea because they're products of communication such as symbol marks for enterprises. This study examined the signification system of the symbol of each military unit in the army divisions within the categories of the icon index and symbol centering around semiotics with trichotomy classifications by Peirce. It was found that the symbols of army divisions are characterized with their strong symbolic meanings from which it's hard to analogize the relation between signs and objects but the more the divisions were established between the late 1940s and the middle 1950s the more iconic their symbols were. As a result of analysis it was revealed that division symbols which have been appeared since then were more like indices focusing on numbers which are the common names of divisions. The symbols took mainly round and shield shapes and their major color was blue which symbolizes peace.

Markov Chain Model을 이용한 CFRP 복합재료의 피로손상누적거동에 대한 확률적 해석

김도식,김정규,김인배,Kim, Do-Sik,Kim, In-Bai,Kim, Jung-Kyu 대한기계학회 1996 大韓機械學會論文集A Vol.20 No.4

The characteristics of fatigue cumulative damage and fatigue life of 8-harness satin woven CFRP composites with a circular hole under constant amplitude and 2-level block loading are estimated by Stochastic Makov chain model. It is found in this study that the fatigue damage accumulation behavior is very random and the fatigue damage is accumulated as two regions under constant amplitude fatigue loading. In constant amplitude fatigue loading the predicted mean number of cycles to a specified damage state by Markov chain model shows a good agreement with the test result. The predicted distribution of the fatigue cumulative damage by Markov chain model is similar to the test result. The fatigue life predictions under 2-level block loading by Markov chain model revised are good fitted to the test result more than by 2-parameter Weibull distribution function using percent failure rule.

Plastic기 복합재료의 파손강도 및 파괴인성에 미치는 원공크기의 영향

김정규,김도식,Kim, Jeong-Gyu,Kim, Do-Sik 한국재료학회 1993 한국재료학회지 Vol.3 No.2

Plastic기 복합재료의 파괴거동에 미치는 원공크기오 판폭의 영향을 검토하기 위하여 단축인장시험을 행하였다. 점응력파손조건에서의 특성길이 $d_o$는 원공크기 및 판폭에 의존하며, 이를 기초로 파손강도를 예측하기 위한 수정 점응력 파손조건식을 제안하였다. 이 파손조건의 예측값은 실험값과 잘 일치하였다. 파손 강도는 원공선단의 손상비의 증가에 따라 증가하며, 이는 손상영역의 형성으로 인한 응력완화현상으로 설명되어 진다. 또한 불안정 파괴시의 최대균열길이 $a_c$는 특성길이 $d_o$의 약 2배의 값을 나타낸다. 파괴인성에 대응하는 한계에너지해방율 $G_c$의 변화는 원공선단의 손상영역의 증가에 의한 응력완화가 주요한 원인이라고 할 수 있다. Abstract The effects of the hole size and the specimen width on the fracture behavior of several fabric composite plates are experimentally investigated in tension. Tests are performed on plain woven glass/ epoxy, plain woven carbon/epoxy and satin woven glass/polyester specimens with a circular hole. It is shown in this paper that the characteristic length according to the point stress criterion depends on the hole size and the specimen width. An excellent agreement is found between the experimental results and the analytical predictions of the modified failure criterion. The notched strength increase with an increase in the damage ratio, which is explained by a stress relaxation due to the formation of damage zone. When the unstable fracture occurred, the critical crack length equivalent for the damage zone is about twice the characteristic length. The critical energy release rate $G_c$ is independent of hole size for the same specimen width. The variation of $G_c$ according to the material system, fiber volume fraction and specimen width relates to the notch sensitivity factor. $G_c$ increases with a decrease in the notch sensitivity factor, which can be explained by a stress relaxation due to the increase of damage zone.