노즐 이종금속용접부의 내면 보수용접부에서 수치해석법을 이용한 PWSCC 균열성장해석

김상철,김만원,Kim, Sang-Chul,Kim, Mann-Won 대한용접접합학회 2011 대한용접·접합학회지 Vol.29 No.2

In this paper, crack propagation analyses in the inner diameter (ID) repair weld of the dissimilar metal weldment of a nozzle were performed using a finite element alternating method (FEAM). To calculate the theoretical solution for the crack tip stress intensity factor, a weak type singular integral equation consisted of crack surface traction and dislocation density function was constructed and solved in conjunction with the FEAM. A two-dimensional axisymmetric finite element nozzle model was prepared and ID repair welding was simulated. An initial crack, 10% depth of weld thickness, was assumed and crack propagation trajectory from the initial crack to the 75% depth of thickness was calculated using the FEAM. Crack growth versus time curve was also calculated and compared with the curves obtained from ASME code method. With the method constructed in this paper, crack propagation trajectory and crack growth time were calculated automatically and effectively.

Message Complexity Analysis of MANET Address Autoconfiguration-Single Node Joining Case

김상철,Kim, Sang-Chul The Korean Institute of Communications and Informa 2007 韓國通信學會論文誌 Vol.32 No.5B

네트워크 계층의 MANET 라우팅 프로토콜이 개발될 때 가장 주요한 관심사는 라우팅 오버헤드 (Overhead)의 축소이다. 본 논문에서는 MANET 에서 단일 노드가 자동 네크워킹 프로토콜에 의해 IP 주소를 획득할 때의 라우팅 오버헤드 (메시지 복잡도)를 정량적으로 분석하는 수학적 방법을 제안한다. MANET에서 자동 네크워킹 프로토콜은 IP 주소 할당시 IP 주소 충돌회피에 사용된다. 메시지 복잡도는 Upper Bound에 의해 수학적으로 정량화 되고, 실제 주소 할당을 컴퓨터 시뮬레이터로 구현하여, 제안된 Upper Bound와 시뮬레이션 결과를 비교, 분석한다. 메시지 복잡도의 Upper Bound는 Worst Case 시나리오 분석에 의해 유도된다. This paper proposes a novel method to perform a quantitative analysis of message complexity and applies this method in comparing the message complexity among the mobile ad hoc network (MANET) address autoconfiguration protocols (AAPs). To obtain the upper bound of the message complexity of the protocols, the O-notation of a MANET group of N nodes has been applied. The message complexity of the single node joining case in Strong DAD, Weak DAD with proactive routing protocols (WDP), Weak DAD with on-demand routing protocols (WDO), and MANETconf has been derived as n(mO(N)+O(t)), n(O(N)+O(t)), n(O(N)+2O(t)), and nO((t+1)N)+O(N)+O(2) respectively. In order to verify the bounds, analytical simulations that quantify the message complexity of the address autoconfiguration process based on the different coflict probabilities are conducted.

하천복류수에 함유된 철과 망간의 오존산화

김상철,이철희,박영규,Kim, Sang-Chul,Lee, Chul-Heui,Park, Yung-Kyu 한국상하수도협회 1984 水道 Vol.32 No.-

대형시공사의 사업관리 역량 강화를 위한 교육 전략 수립에 관한 연구

김상철,박찬정,이상엽,손재호,Kim, Sang-Chul,Park, Chan-Jeong,Lee, Sang-Youb,Son, Jae-Ho 한국건설관리학회 2007 건설관리 : 한국건설관리학회 학회지 Vol.8 No.5

It is related to launch the CM market and to increase the profit and entire ability in company that is enforcing the ability of construction management in large-scaled construction company. According to the CM market in U.S, CM market is increased with competing to the companies, that is E&C, general contractor, design firm, specialized CM firm. Also domestic market is similar to US market. In this situation, large-scaled construction companies are filled with construction management ability for competing with foreign companies and domestic CM firms. This paper suggests how to enforce the construction management ability through education, and shows the detailed education strategy considered the fields, divisions and positions. 대형시공회사에 있어 CM 역량강화의 문제는 비단 CM 시장의 진출뿐만 아니라 회사의 역량 강화, 경쟁자와의 차별성 및 수익성의 증대라는 측면에서 대단히 중요한 의미를 갖는다. 현재 미국의 CM시장을 분석하여 본 결과 CM은 EC, GC, 그리고 설계 및 전문 CM사와의 각축속에서 그 규모가 점차 확대되고 있고, 국내의 경우의 경우도 그와 유사하게 진행되어가고 있다. 이러한 상황에 대형시공사는 국내시장에서 기존의 CM 강자들과의 경쟁과 해외시장에서 선진 외국사와의 경쟁을 위해서는 부족한 CM 역량에 대한 시급한 보완이 필요하다고 판단된다. 이에 본 논문은 CM 역량 강화를 위한 교육 전략 수립에 초점을 맞추어 연구를 진행하였고, 각 현장, 사업본부, 직급을 고려한 교육 전략을 제시하였다.

적층한 콘크리트 복합구조체의 파괴역학적 거동

김상철,김연태,Kim, Sang-Chul,Kim, Yeon-Tae 한국콘크리트학회 1999 콘크리트학회지 Vol.11 No.1

본 연구는 시멘트를 기초로 하는 준 취성재료를 2개 결합시킨 복합구조체의 파괴거동을 시뮬레이션 하는 데 그 목적이 있다. 이를 위해 작용하중방향에 직각으로 콘크리트와 시멘트를 적층하여 시편을 제작하였고, 비선형파괴해석에서 사용되는 각 구성재료별 파괴계수들을 구하기 위해 콘크리트와 시멘트 각각에 대해 3점휨시험 및 간접인장강도시험을 실시하였다. 시험을 통해 산정한 계수들을 도출한 이론식에 적용하여 복합체로 제작한 시편의 실험 결과치와 비교한 결과, 가상균열이론에 입각한 이론치와 실험결과치는 거의 유사한 경향을 나타내었다. 또한, 파괴에너지와 강도의 향상은 복합체를 구성하는 구성재료의 적층순서에 크게 의존하는 것으로 나타났다. 따라서 구조물의 목적에 맞게 복합체를 적절히 배열하므로써 구조물의 취성과 연성을 상승시킬 수 있음을 본 연구를 통해 알 수 있었다. The objective of this study is to simulate the fracture behavior of composite structure bonded with more than 2 different cementitious materials. For this, concrete and cement were stacked and bonded in a direction perpendicular to loading and specimens were tested. Each constituent material of concrete and cement was fabricated independently also, and three point bending and indirect tensile tests were carried out for the acquisition of measured values applicable to the proposed model. As a result of comparing theoretical results and experimental ones, it was found that the proposed model derived from fictitious crack theory can be used to predict the fracture behavior of composite structures on the vases of well agreement with experimental results. It was also noted that the degree of improvement of fracture energies and strengths is greatly dependent on the stacking sequence of layers composing of a composite structure. Thus, it can be concluded that brittleness or ductility of a composite structure can be accomplished by a proper arrangement of layers on one's purpose throughout the proposed analysis.

리스크 관리를 통한 프로젝트 타당성 검토방안에 대한 연구 -소규모 임대주택을 대상으로-

김상철,박찬정,윤준선,Kim Sang-Chul,Park Chan-Jeong,Yoon Jun-Seon 한국건설관리학회 2004 건설관리 : 한국건설관리학회 학회지 Vol.5 No.3

사업기획 및 타당성분석단계는 사업을 추진하는데 가장 큰 영향을 미치는 단계로써, 정확한 프로젝트 타당성 검토 수행은 프로젝트를 추진하는데 결정적인 기회를 제공해주므로 직관적인 접근방식보다는 객관적이고 정확한 방법의 제시가 요구되는 바이다. 사업타당성을 정확하게 분석하기 위하여 본 논문에서는 프로젝트 진행에 영향을 주는 리스크 인자를 식별하고 이 인자들을 성격별로 그룹화한다. 소규모 임대주택의 사례를 바탕으로 기존 방식인 금융부분의 프로젝트 타당성 분석을 실시한다. 위에서 식별된 리스크 인자들 중 금융부분을 포함하여 인자들간의 상관관계를 Influence Diagram으로 파악하여 리스크를 분석하고, 각 인자별의 중요도를 판별하기 위한 민감도 분석을 실시한다. 이와 같은 과정을 통하여, 기존의 프로젝트 타당성분석에서 사용하는 금융부분의 타당성분석 뿐만 아니라, 프로젝트 진행시에 나타나는 비정형적이고 주관적인 요소들을 리스크 인자로써 포함하여 분석할 수 있는 장점이 있다. 또한, 도출된 모든 리스크 인자를 정량화하여 객관적인 분석 및 의사결정을 할 수 있기 때문에 기존 방법보다 발전된 프로젝트 타당성 분석 방안을 본 논문에서 제시하였다. Planning phase became very important because the construction market in Korea is often unpredictable. The existing feasibility analysis cannot fulfill its purpose in development projects because they are based on intuitive approach rather than systematic approach. The purpose of this study is to make a prototype of feasibility model to be a good investment. To build the model, first, risk factors which can be occurred in project had to be selected. Risk factors were divided into several groups in basis of characteristical risk. Economical risk factors were input on financial analysis. Then, to catch the relevance and influence of all risk factors, influence diagram and decision tree were made. Finally, sensitivity analysis was activated, then what the critical factors were, and how those factors could be solved. Through these procedures, the feasibility model that was made in this study could include both quantitative and qualitative factors. This model is expected to be used as a guide of feasibility analysis including all risk factors and is to serve systematic frame in planning and feasibility stage.

Disciplinary Session 2 / Sport History / Cultural and Historical Overview of Sport and Physical Education : 한국 무도의 문화적 이해

김상철,허건식,박범남 ( Sang Chul Kim,Keon Sik Heo,Beom Nam Park ) 한국체육학회 1998 국제스포츠과학 학술대회 Vol.1998 No.1

하중진폭제어에 따르는 피로균열전파거동

김상철,함경춘,강동명,Kim, Sang-Chul,Ham, Kyoung-Chun,Kang, Dong-Myeong 한국정밀공학회 1992 한국정밀공학회지 Vol. No.

The effect of mechanical, properties in the plastic zone near the crack-tip was investigated, under various controlled loading conditions, i.e., ${\Delta}K$ increasing, ${\Delta}K$ decreasing, and single overload test. For both ${\Delta}K$ decreasing test and ${\Delta}K$ increasing test with constant stress ratio, it is found that the ratio of material constant m'( ${\Delta}K$ decreasing test) to material constant m( ${\Delta}K$ increasing test) is larger than 1 for n<0.1, and it is equal to 1 for 0.1<n<0.2. But it is smaller than 1 for n>0.2. A modified crack growth rate equation based on Forman's equation which applied stable region of fatigue crack propagation in ${\Delta}K$ decreasing test is proposed. Within the limit of this single overload test, an empirical relation between among the retardation ratio (Nd/ $N^{*}$), the strain hardening exponent (n) and the percent peak load (%PL) has been established.established.

헬리콥터 조종사의 상황인식과 교육 만족도의 상관분석을 통한 교육개선연구

김상철,이용혁,Kim, Sang-chul,Lee, Oyong-hyeok 한국항공운항학회 2021 한국항공운항학회지 Vol.29 No.1

The topic of this paper was analyzed as "t -test" and "multiple regression analysis" for 303 helicopter pilot trainees from aviation schools in the county for "improvement of education through correlation analysis of helicopter pilots' situational awareness and education satisfaction." In addition to the factors for overcoming situational awareness and situational awareness, the level of satisfaction of the instructor and the level of satisfaction of the learning management system (LMS) is the confidence interval p<.05, 95%. It was analyzed to be significant at the level of 05, 95%. Therefore, it was analyzed that in order to improve the "quality of the instructor" in future education, institutional supplementation and "learning management system (LMS)" need to be established including VR and AR so that pilot trainees can use it at all times.

수치해석방법을 이용한 이종금속용접부에서의 균열성장해석

김상철,김만원,Kim, Sang-Chul,Kim, Maan-Won 대한용접접합학회 2010 대한용접·접합학회지 Vol.28 No.1

In this paper crack propagation analyses in the dissimilar metal weldment of a nozzle were performed using a finite element alternating method (FEAM). A two-dimensional axisymmetric finite element nozzle model was prepared and welding simulation including the thermal heat transfer analysis and the thermal stress analysis was performed. Initial cracks were inserted at weld and heat affected zone in the finite element model which has welding residual stress distribution obtained from the welding simulation. To calculate crack propagation trajectories of these cracks, a new fatigue crack evaluation module was developed in addition to the previous FEAM program. With the new FEAM fatigue crack evaluation module, crack propagation trajectory and crack growth time were calculated automatically and effectively.