• 항공우주기술
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• 제8권2호
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• pp.68-74
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• 2009

지구 관측용 광학탑재체를 포함하는 정지궤도 복합위성에는 관측 대상인 지구의 기준위치 정보를 제공하기 위해 적외선 지구센서가 장착된다. 정지궤도상에서 지구센서와 관측 탑재체사이의 지향차는 그 크기가 작더라도 관측 영상의 품질에 심각한 영향을 미칠 가능성이 있다. 따라서 이러한 지향차를 줄이기 위해 궤도상에서 기하학적 안정성을 보장할 수 있는 지지구조물이 적용되었다. 본 논문에서는 통신해양기상위성에서 지구센서 장착을 위해 사용된 지지구조물에 대한 설계 측면의 타당성을 제시한다. 이를 위해 설계 전반의 내용을 기술하고, 설계과정에서 고려된 안정성 측면의 제반 사항과 강성과 강도 등의 요구조건에 대한 부합 여부를 살펴볼 것이다.

• 한국군사과학기술학회지
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• 제21권3호
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• pp.264-278
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• 2018

The support structure of an optical mirror system is the one of the important design elements because the one affects the optical aberrations of the mirror surface. In this paper, Lagrange equation of the moving body of the fast steering mirror system(FSM) has been formulated to use with optimization design. Major goals for optimization are to assign the reasonably flexible stiffness to the structure and to enhance the first natural frequency of the mirror and support system in aid of more affordable control bandwidth for the FSM. Pursuing these purposes with the proposed method, the finite element analysis(FEA), optimization technique and the Zernike polynomial estimation are used for the design effects. It is concluded that the proposed approach for design well guides toward the desired design goals with regards to both structural and optical performances.

• 4차산업연구
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• 제2권2호
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• pp.47-60
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• 2022

Purpose - The purpose of this study is to investigate the role of Teamwork on Engagement among employees of private primary and secondary schools in Plateau State, Nigeria using the dimensions of Teamwork, which are Communication, Leadership, Team Structure, Situation Monitoring, and Mutual Support on Employee Engagement. Research design, data, and methodology - To analyze the relationship among the variables, the study adopted the descriptive and explanatory research design, and a cross-sectional survey method using a survey questionnaire containing 29 items, with a 5-point Likert scale. The samples of 274 employees (both academic and non-academic) were selected using a simple random probability sampling technique. Multiple Regression was used to analyze data with the aid of the statistical package for social sciences (SPSS version 23.0). Result - This shows that Communication, Leadership, and Situation Monitoring have a positive and significant relationship on Employee Engagement, while Team Structure and Mutual Support show a negative direction but still maintained a significant relationship. Conclusion - The management of private primary and secondary schools should pay attention to Communication, Leadership, Team Structure, Situation Monitoring, and Mutual Support among their employees to promote Employee Engagement in the workplace. It also recommends that future studies should be carried out in other sectors.

• Wind and Structures
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• 제27권1호
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• pp.41-57
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• 2018

Concentrated Solar Photovoltaic (CPV) is a promising alternative to conventional solar structures. These solar tracking structures need to be optimized to be competitive against other types of energy production. In particular, the selection of the structural parameters needs to be optimized with regards to the dynamic wind response. This study aims to evaluate the effect of the main structural parameters, as selected in the preliminary design phase, on the wind response and then on the weight of the steel support structure. A parametric study has been performed where parameters influencing dynamic wind response are varied. The study is performed using a semi-deterministic time-domain wind analysis method. Unsteady aerodynamic model is applied for the shape of the CPV structure collector at different configurations in conjunction with a consistent mass-spring-damper model with the corresponding degrees of freedom to describe the dynamic response of the system. It is shown that, unlike the static response analysis, the variation of the peak wind response with many structural parameters is highly nonlinear because of the dynamic wind action. A steel structural optimization process reveals that close attention to structural and site wind parameters could lead to optimal design of CPV steel support structure.

• 국제학술발표논문집
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• The 9th International Conference on Construction Engineering and Project Management
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• pp.245-252
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• 2022

Risk identification for bridge projects is a knowledge-based and labor-intensive task involving several procedures and stakeholders. Presently, risk information of bridge projects is unstructured and stored in different sources and formats, hindering knowledge sharing, reuse, and automation of the risk identification process. Consequently, there is a need to develop structured and formalized risk information for bridge projects to aid effective risk identification and automation of the risk management processes to ensure project success. This study proposes a semantic risk breakdown structure (SRBS) to support risk identification for bridge projects. SRBS is a searchable hierarchical risk breakdown structure (RBS) developed with python programming language based on a semantic modeling approach. The proposed SRBS for risk identification of bridge projects consists of a 4-level tree structure with 11 categories of risks and 116 potential risks associated with bridge projects. The contributions of this paper are threefold. Firstly, this study fills the gap in knowledge by presenting a formalized risk breakdown structure that could enhance the risk identification of bridge projects. Secondly, the proposed SRBS can assist in the creation of a risk database to support the automation of the risk identification process for bridge projects to reduce manual efforts. Lastly, the proposed SRBS can be used as a risk ontology that could aid the development of an artificial intelligence-based integrated risk management system for construction projects.

• 한국멀티미디어학회:학술대회논문집
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• 한국멀티미디어학회 2003년도 춘계학술발표대회논문집
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• pp.374-379
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• 2003

본 논문에서는 pattern recognition을 위하여 support vector fuzzy inference system을 제안하였다 Fuzzy inference system의 structure와 parameter를 identification 하기 위하여 Support vector machine을 이용하였으며 에러 최소화 기법으로는 gradient descent 방법을 사용하였다. 제안된 SVFIS 방법의 성능을 파악하고자 COIL 이미지를 이용한 3차원 물체 인식 실험을 수행하였다.

• 대한토목학회논문집
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• 제12권4_1호
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• pp.9-21
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• 1992

논문에서는 주구조물의 기초와 부구조물의 지지점에 설치된 감진장치가 구조물의 지진응답 감소에 미치는 영향을 분석하였다. 여러가지 지진하중의 특성에 따른 감진장치가 설치된 주구조물과 부구조물의 거동을 비교분석하였으며, 이때 사용된 해석모델은 고정기초 구조물에 지지점이 고정된 부구조물, 감진기초 구조물에 지지점이 고정된 부구조물, 고정기초 구조물에 지지점 감진장치가 설치된 부구조물과 같은 세가지이다. 부구조물의 응답계산에서는 주구조물과 부구조물의 상호작용을 고려하였다. 계산에 사용한 수치적분방법은 constant average acceleration 방법이며, 이 방법과 축소행렬방법을 이용한 전산프로그램(KBISAP)을 사용하였다. 또한 지진하중에 대한 구조물의 지면에 대한 상대변위를 제한시키기 위하여 여러가지 지진하중에 대한 구조물의 가속도와 변위의 상관관계를 계산하여 감진장치의 적합한 수평강성을 분석하였다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1997년도 춘계학술대회 논문집
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• pp.150-155
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• 1997

Rapid Prototyping(RP) is the technique which is used to make prototypes or functional parts directly using the 3-D solid data. Before building the prototype, several processes such as transfering 3D data from CAD system(STL) determination of build-direction, adding support structure and slicing are required. Among the above processes. determination of build-direction is the target of this study. The build direction is determined by many factors according to the objective of the user, like part accuracy, number of support structure, build time, amount of trapped volume, etc, But it is not easy to determine the build-direction because there are many factors and some factors have dependent properties with one another. So, in this study the part accuracy, the number of support structures and build time are considered as the main factor to determine the optimal build-direction. To determine the optimal build-direction for increasing part accuracy, sum of projected area which caused stairstepping effect was considered. The less the projected area is the better part accuracy is About the optimal build-direction to minimize the amount of support structure, sum of projected area of facets that require support structures was considered. About the build time, we considered the minimum height of part we intended. About the build time, we considered the minimun height of part we intended to make.

• 한국해양공학회지
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• 제24권1호
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• pp.153-160
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• 2010

This paper deals with the topology optimized design of the riser support structures for floating production storage and offloading units (FPSOs) under global and local loading conditions. For a preliminary study and validation of the numerical approach, a simplified plate under static loading is first evaluated with the representative topology optimization methods, the Homogenization Design Method (HDM) and Density Method (DM) or Simple Isotropic Material with Penalization (SIMP). In the context of the corresponding riser support structures, the design problem is formulated such that structure shapes based on design domain variables are determined by minimizing the compliance subject to a mass target, considering the stress criterion. An initial design model is generated based on an actual FPSO riser support configuration. The topology optimization results present improved design performances under various loading conditions, while staying within the allowable limit of the offshore area.

• Journal of Advanced Research in Ocean Engineering
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• 제4권2호
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• pp.47-52
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• 2018

The Korea Offshore Wind Power (KOWP) is planning to construct offshore wind energy farms with an overall rated power of 2.5 GW in the south-western coast of the country until 2019. Various types of support structures for offshore wind turbines have been proposed in the past. Nevertheless, in South Korea, jacket structures have in general, been applied as support structures for offshore wind turbines owing to the many accumulated experiences and know-how regarding this kind of support structure. The choice of offshore structure is mainly influenced by site conditions such as seabed soil type and sea environment during installation. In installing jacket sets on the seabed, the mudmat is necessary to maintain the equilibrium of the jacket without the aid of additional devices. Hence, this study proposes the installation of skirt plates underneath the bottom frame of jackets in order to improve the installation stability of jacket structures under rougher sea conditions. To confirm the effect of skirt plates, installation stability analyses considering overturning, sliding and bearing capacity have been performed. From the results, it is shown that jacket structures with skirt plates can contribute to improving the sliding stability of the structures of new wind power farms, while providing economic benefits.