• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2006.11a
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• pp.74-79
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• 2006

Generally, policymakers have a tendency to target achieving individual policy goals rarely considering their effects as a whole. In addition, the conventional policymaking practice lacks considerations on the various needs of industry participants and their response to public policies. To address this issue, a system dynamics model as a simulation model-based approach, which can examine the effectiveness of public policies in a systematic manner, is presented with an application example of the Singaporean government's policies to enhance construction productivity. Using this simulation model, the governmental policies are tested in a qualitative manner. Having obtained policy implications from the model structure and simulation results, suggestions and guidelines are provided to make the governmental policies more effective. Finally, based on the research findings it is concluded that the simulation model-based approach could be useful for construction policymaking.

• Journal of Korea Game Society
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• v.13 no.2
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• pp.49-58
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• 2013

In this study, a tree growth model is designed to represent a variety of trees consisting of a outdoor terrain of game efficiently and naturally. The proposed tree growth model is an integrated tree growth model, and is configured using the following approaches: (1) the tree modeling method based on growth volume and the convolution sums of divisor functions, which is used to model a variety kind of trees more intuitively and naturally; (2) a rendering method using a level of detail of branch based on instancing for real-time processing of numerous trees with complicated structures; and (3) a combination of the above methods to efficiently implement a game landscape. The natural and diverse growths of trees that emerged using the proposed tree growth model is evaluated through experimentation, along with the possibility of implementing the natural game landscape and the efficiency of real-time processing.

• The Korean Journal of Archival Studies
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• no.13
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• pp.41-90
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• 2006

It's needed for the archivists to design a flexible and stable ERMS(Electronic Records Management System) which can ingest and store records through a consistent way and let users search and use records easily what they want. The basis of the design for ERMS are the conceptual composition and the logical and physical structure of the records when they are stored and managed in the ERMS. This paper explains the process of defining components and designing structure of electronic records using 3-layered approaches which consist of conceptual, logical and physical layer and shows advantages of this approaches. After benchmarking the information models of OAIS which is a reference model for the long-term preservation of digital information objects, this paper applies the model of AIP to a record as a 'Record AIP' and discusses the composition and structure of it. It's a critical task to identify mandatory or optional metadata groups which consists of the 'Record AIP's in the conceptual layer. This paper emphases that the metadata group related to services for the record information to users is required as a result of benchmarking OAIS information models. Various issues about the structure of 'Record AIP's are discussed according to the kind of preservation strategy such as migration or emulation and whether the encapsulation of records is required or not in the logical layer.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.1
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• pp.25-32
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• 1999

교류전동기 구동을 위한 산업용 전력전자 시스템은 전력회생용 양방향 컨버터, VVVF 인버터, 교류전동기 벡터제어기, 및 다양한 전기ㆍ기계적 연계 장치들을 포함하는 전기기계 복합시스템 특성을 지니기 때문에 전체 시스템에 대한 컴퓨터 시뮬레이션이 용이하지 않다. 일반적으로 이러한 복잡성을 해결하기 위한 방안으로서 시스템을 근사화시키고 이에 대한 수학적인 등가모델을 유도한 후 이를 이용하여 시뮬레이션을 행하고 있지만, 이 경우 실계통의 다이나믹특성을 정확히 표현할 수 없기 때문에 시뮬레이션 신뢰성이 저하될 수 있다 본 논문에서는 가변구조 제어기법에 의해 역률1 제어기능을 갖는 PWM 컨버터, VVVF 인버터 및 유도기 간접벡터제어기 둥을 포함하는 유도전동기 구동전력전자 시스템을 다이나믹 노드 기법(Dynamic Node Technique DNT)과 시뮬링크(Simulink)를 이용하여 실제회로 구성상태와 유사한 형태로 시뮬링크 윈도우상에서 설계하고, 이를 통해 시뮬레이션을 행할 수 있는 기법을 제시한다. 시뮬레이션 결과를 통하여 전력전자 시스템의 특성과 제시된 다이나믹 노드 기법과 시뮬링크를 이용한 시뮬레이션 기법의 유용성을 보였다.

• Proceedings of the KIPE Conference
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• 2013.11a
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• pp.173-174
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• 2013

본 논문에서는 단상 전원과 고정자가 직접 연결되고 회전자에는 독립된 하나의 인버터가 적용되는 전동기 구동 시스템에 대한 분석을 진행한다. 이와 같은 전동기 구동 시스템의 구조는 양방향 운전이 가능하며, 인버터의 직류단 전압을 자유롭게 제어할 수 있다. 또한 입력단에 어떠한 추가적인 장치도 요구하지 않으므로 전동기를 단상 계통에 직접 연결할 수 있어 가전 제품의 적용에 용이하다. 본 논문에서는 이러한 권선형 전동기의 구동 방식을 설명하고, 세탁기 운전을 그 목표로 하여 권선형 전동기의 설계 및 FEM 시뮬레이션을 진행한다. 시뮬레이션은 Maxwell 로 설계된 전동기 FEM 모델을 Simplorer 시뮬레이션을 통해 연동해석을 진행하였다.

• Journal of Advanced Marine Engineering and Technology
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• v.21 no.2
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• pp.136-143
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• 1997

직경 비가 0.56인 이중동심관에 내외측모두 매끈한 벽면, 벽면 거칠기를 안측, 외측, 그리고 양측 모두의 4경우에 대한 난류 유동과 열전달특성을 실험과 이론으로 연구하였다. 시간평균속도분포, 마찰계수, 그리고 최대 속도 지점과 전단응력이 0인 지점들을 피토튜브와 X형 열선 풍속계로 측정하였다. 이중동심관내에서 4가지 경우에 따른 사각돌출형 거칠기효과가 난류 유동과 열전달에 미치는 영향을 수정난류모델을 기초로 하여 연구하였다. 직경비, 거칠기 위치, 레이놀즈수, 그리고 프란틀수 등의 여러 변수에 의해서 난류 유동과 열전달을 고찰하였다. 본 연구는 전체적 효율 측면에서 유리하게 열전달율을 향상시킬수 있는 거칠기 구조를 밝혔다.

• Journal of the Korea Society for Simulation
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• v.17 no.2
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• pp.31-47
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• 2008

As OWL(Web Ontology Language) has been selected as a standard ontology description language by W3C, many ontologies have been building and developing in OWL. The lena developed by HP as an Application Programming Interface(API) provides various APIs to develop inference engines as well as storages, and it is widely used for system development. However, the storage model of Jena2 stores most owl documents not acceptable into a single table and it shows low processing performance for a large ontology data set. Most of all, Jena2 storage model does not consider hierarchical structures of classes and properties. In addition, it shows low query processing performance using the hierarchical structure because of many join operations. To solve these issues, this paper proposes an OWL ontology relational database model. The proposed model semantically classifies and stores information such as classes, properties, and instances. It improves the query processing performance by managing hierarchical information in a separate table. This paper also describes the implementation and evaluation results. This paper also shows the experiment and evaluation result and the comparative analysis on both results. The experiment and evaluation show our proposal provides a prominent performance as against Jena2.

• Journal of Korea Port Economic Association
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• v.26 no.2
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• pp.1-18
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• 2010

With the maturity and fierce competition of domestic logistics market, Korea government is actively working on the overseas investments in global logistics market after establishing the basic plan since 2006. In particular, India is selected one of promising countries for logistics investments since it has more 1.1 billion people and is regarded as post-China. In fact, a number of global logistics enterprises have started their businesses in the logistics market of India so that the competition already started. In this regard, it is highly necessary to find out feasible investment projects and then detemin the priority of the alternatives for successful investments. Therefore this study proposes a fuzzy-based AHP model by which the overseas investment problem was systematically structured and then evaluated. The model was established by exploiting a fuzzy theory and AHP for capturing the inexactness and vagueness of information. The results show that the investment of port operations is the number one priority in the India's logistics market and ODCY operations, road transportations, forwarding operations, inland depot operations in order. Finally the proposed model will help Korea's policy makers to have a better reliable investment strategy.

• Information Systems Review
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• v.18 no.4
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• pp.89-106
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• 2016

The latest movement in live video streaming service is mobile personal broadcasting (MPB), which refers to consumers accessing the service through social media with mobile devices, such as smartphones and tablet PCs. This service is possible through the advancements in mobile video technology and platforms. Features such as enhanced user interaction, personalization, and real-time broadcasting, combined with a greater variety of content, have led to the development of MPB. The increase in MPB users calls for research, including that on the hedonic motivational angle. This study aims to assess MPB users' intrinsic motives through the hedonic-motivation system adoption model (HMSAM) using seven factors: joy, temporal dissociation, escapism, focused immersion, perceived ease of use, perceived usefulness and intention to watch. Survey data collected from 154 samples were analyzed with statistical techniques, such as structural equation modeling. Results showed that time dissociation, escapism, and perceived ease of use have a positive relationship with heightened enjoyment. Joy significantly affects focused immersion and intention to watch. Escapism also had a statistically significant influence on focused immersion. This study contributes to the advancement of the MPB study under the HMSAM theoretical framework and offers practical suggestions to managers to enhance MPB content viewership.

• The Journal of the Korea Contents Association
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• v.18 no.5
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• pp.215-229
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• 2018

The purpose of this study was to examine the structural relationships among factors affecting teachers' robot-based SW education acceptance in primary school. In addition, this study investigated moderating effects of gender, age, and experience. For this purpose, 171 elementary school teachers participated in this study and structural equation modeling analyses were employed to examine the causal relationships among variables. The result of this study showed that perceived ease of use, perceived usefulness, personal innovativeness had direct effects on attitude. Furthermore, attitude mediated relationships between perceived usefulness, perceived ease of use, personal innovativeness and intention to use. Third, the moderating effects of experience between perceived usefulness, personal innovativeness and attitude were significant, but gender and age were not significant on all paths. Based on the results of this study, successful teaching practices, cases, and contents should be shared with teachers. Also, continuous supports and differentiated strategies based on experience are needed.