• 한국건설관리학회논문집
• /
• 제7권3호
• /
• pp.65-75
• /
• 2006

주한 미군의 EC(Engineering/Construction) 시장에서 최근 나타나는 경향은: (1) MATOC(Multiple Award Task Order Contract)의 도입: (2)프로젝트의 대형화: 그리고 (3)대형 미국 EC회사들의 주한 미군 시장 진입으로 요약된다. 이러한 새로운 경향에 대한 이해를 바탕으로, 본 연구는 주한 미군 EC 시장의 변화를 시공관리 주체의 변화에 초점을 맞추어 분석한다. 구체적으로 살펴보면, 주한 미군 EC 프로젝트들은 FED에 의해 관리되어 왔다. 그러나 최근에는 대형 미국 민간 EC 회사들이 한국에 진입하여 FED의 시공관리 역할을 대체하고 있다. 이러한 현상은 향 후 10여 년 간의 LPP(Land Partnership Plan: 한미연합 토지 관리계획)에 의한 한국에서의 비즈니스 기회와 시공관리 주체의 민영화를 통해 군 관련 공사비를 절약하려는 미 정부의 의도에 따라 가속화 되고 있다. 이러한 시장의 변화는 미국 대형 EC 회사들과의 JV(Joint Venture)를 통해 외국 시장에 관한 정보를 획득하고 선진 시공 관리 기술을 배울 수 있는 기회가 되기 때문에, 주한 미군 한국 EC 시장에 진입하는 미국의 대형 EC 회사들은 주한 미군 공사를 수주해 온 국내 EC 회사들에게는 위협임과 동시에 기회일 수 있다.

• Structural Engineering and Mechanics
• /
• 제16권1호
• /
• pp.1-15
• /
• 2003

This paper proposes a new method for the preliminary design of cable-stayed bridges that belong to the radial system subjected to static loads (self weight, traffic loads, concentrated loads, etc). The method is based on the determination of the each time existing relation between the tension forces of the cables and the corresponding bridge-deck deformations, and can be extended on any type of cable layout (fan, parallel, or mixed system). Galerkin's method is used for the final determination of the cable stresses and the bridge deformation. The determination of the equation, which gives the forces of the cables in relation to the deck's configurations, permits us to convert the problem to the solving of a continuous beam without cables.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
• /
• pp.979-984
• /
• 2008

본 연구는 실용적인 적용을 위한 기본적인 스트럿-타이 모델의 사용방법에 대해 논의한다. 스트럿- 타이 모델의 구성은 평형 조건식에 기초한 하중 경로를 그리는 것으로 시작한다. active sytems, vector active systems, 그리고 section active systems를 포함한 구조 시스템의 이해는 가능한 스트럿 -타이 모델을 위한 적절한 시스템을 선택할 수 있도록 한다. 간단한 원형 fan은 집중하중에서부터 분포하중까지 하중 경로를 표시할 수 있다. 스트럿의 강도는 인장 타이와 유효 압축 강도가 만나는 절점영역의 형태에 따라 결정된다. 스트럿의 유효 압축강도는 주로 transevers 변형률에 의해 영향을 끼치는 것으로 가정한다.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2010년도 춘계학술대회 논문집
• /
• pp.1-5
• /
• 2010

The Hyundai Rotem company is due to be conducted the main line Speed Qualification Test as regulated by CFR for SEPTA EMU and SCRRA Bi-level coach project. The regulated test items per 49CFR213.345 are wheel/rail interaction forces and carbody/truck accelerations during running on main line. Therefore the special two sets of instrumented wheelset (IWS) per each project have been made for measuring the interaction forces between wheel and rail at four wheels of one truck during running on main line. In this paper, regarding Speed Qualification Test, the required test items and data analysis method per 49CFR213.345 and the preparation status of instrumented wheelsets (IWS) are introduced.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2002년도 추계학술대회 논문집
• /
• pp.270-273
• /
• 2002

This paper presents an effective cutting force model that enable us to predict the instantaneous cutting force in milling process from a knowledge of the work material properties and cutting conditions. The development of the model is based on the orthogonal machining theory with the effective rake angle which is defined in the plane containing the cutting velocity and chip flow vectors. Face milling tests are performed at different feeds and, a fairly good agreement is shown between the predicted cutting forces and test results.

• 한국정밀공학회지
• /
• 제15권11호
• /
• pp.137-144
• /
• 1998

In this paper we present our research dealing with the problem of tool deflection during the milling. We try to compensate the errors by considering a new tool trajectory. In order to determine the compensated tool trajectory, the problem is divided in three steps : cutting forces model, tool deflection model and trajectory compensation. Starting from experimental data, we determine a cutting forces model., which allows us to anticipate the tool deflection along one nominal path. In order to determine the compensated tool trajectory, we propose in this paper a method of path compensation, called “mirror method”. This method of tool path optimization allows to minimize errors due to tool deflection. Several examples are processed in simulations and validated experimentally.

• Strategy21
• /
• 통권36호
• /
• pp.180-214
• /
• 2015

The Republic of Korea navy challenged from the unexpected surprise attacks by the North Korea navy, albeit, the developments of up-to-date naval forces' technology, and the ceaseless efforts for war preparedness. My study divided into two categories. Qualitative methods used for literature review of international relations theory related to the war onset and for investigating events occurred on the Peninsula and its surrounding seas from 1968 to 2007. Quantitative method used such as the analyses of national power index of the two Koreas, the United States, and China, the uses of equation model to calculate power index of alliance, COPDAB(Conflict and Peace Data Bank) index analysis. Like Choi's study on East Asia maritime conflict, as a conclusion, considering both AT theory and maritime national power as a tool for predicting maritime conflict in the Peninsula proved significant. Based on the study, ROK navy need to prepare for the maritime conflict because the results showed North Korea would initiate maritime disputes sooner or later using fatal asymmetric forces and methods. As a policy suggestion, we are required to maintain a concrete ROK-US alliance ties and to construct naval forces due to the deterring functions of maritime national power.

• 한국소음진동공학회논문집
• /
• 제20권9호
• /
• pp.805-815
• /
• 2010

This paper studies the influence of internal moving fluid and flow-induced structural instability of multi-wall carbon nanotubes conveying fluid. Detailed results are demonstrated for the variation of natural frequencies with flow velocity, and the flow-induced divergence and flutter instability characteristics of multi-wall carbon nanotubes conveying fluid and modelled as a thin-walled beam are investigated. Effects of various boundary conditions, Van der Waals forces, and non-classical transverse shear and rotary inertia are incorporated in this study. The governing equations and three different boundary conditions are derived through Hamilton's principle. Numerical analysis is performed by using extended Galerkin's method which enables us to obtain more exact solutions compared with conventional Galerkin's method. This paper also presents the comparison between the characteristics of single-wall and multi-wall carbon nanotubes considering the effect of van der Waals forces. Variations of critical flow velocity for different boundary conditions of two-wall carbon nanotubes are investigated and pertinent conclusion is outlined.

• Structural Engineering and Mechanics
• /
• 제69권5호
• /
• pp.499-509
• /
• 2019

While the wheel flat is an asymmetrical phenomenon in the railway, majority of researches have used two-dimensional models in the investigation of the effect of wheel flat on the wheel rail forces. This is due to the considerably low computational costs of two dimensional (2D) models although their reliability is questionable. This leaves us with the question of "what is the optimum modeling technique?". It is addressed in this research. For this purpose, two and three dimensional numerical models of railway vehicle/track interaction were developed. The three dimensional (3D) model was validated by comparisons of its results with those obtained from a comprehensive field tests carried out in this research and then, the results obtained from the 2D and 3D models were compared. The results obtained indicate that there are considerable differences between wheel/rail forces obtained from the 2D and 3D models in the conditions of medium to large wheel-flats. On the other hand, it was shown that the results of the 2D models are reliable for particular ranges of vehicle speed, railway track stiffness and wheel-fats lengths and depths. The results were used to draw a diagram, which presents the optimum modeling technique, compromising between the costs and accuracy of the obtained results.

• International Journal of Advanced Culture Technology
• /
• 제11권1호
• /
• pp.147-152
• /
• 2023

The South Korean military has undergone four changes in operating methods since its inception with 31 nursing officers in August 1948. While it initially began as a special unit for nursing and other specialized services, it later expanded to include various fields including technology, administration, and special forces. However, analysis shows that there have been few significant changes in how it operates and remains largely centered around technology, administration, and special forces. With the development of advanced science and technology and a decrease in military resources, there is a need for the South Korean military to proactively expand its use of female personnel, as has been done by the US military, Canadian military, Israeli military with female conscription, and Norwegian military. In order to achieve this, there needs to be a cultural shift towards co-ed military units, improvements in facilities and equipment, adequate pay and benefits, and resolution of childcare issues through institutional reforms.