• 전기학회논문지
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• 제63권1호
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• pp.18-26
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• 2014

A microgrid can play a significant role for enlargement of renewable energy sources and emission reduction because it is a network of small, distributed electrical power generators operated as a collective unit. In this paper, an application of optimization method to economical operation of a microgrid is studied. The microgrid to be studied here is composed of distributed generation system(DGS), battery systems and loads. The distributed generation systems include combined heat and power(CHP) and small generators such as diesel generators and the renewable energy generators such as photovoltaic(PV) systems, wind power systems. Both of thermal loads and electrical loads are included here as loads. Also the emissions trading scheme to be applied in near future, the cost of unit start-up and the operational characteristics of battery systems are considered as well as the probabilistic characteristics of the renewable energy generation and load. A mathematical equation for optimal operation of this system is modeled based on the mixed integer programming. It is shown that this optimization methodology can be effectively used for economical operation of a microgrid by the case studies.

• 품질경영학회지
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• 제44권4호
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• pp.751-770
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• 2016

Purpose: Two-stage ${\bar{X}}$ chart is a useful tool for process control when a surrogate variable may be used together with a performance variable. This paper extends the two-stage ${\bar{X}}$ chart to a three stage version by decomposing the first stage into the preliminary stage and the main stage. Methods: The expected cost function is derived using Markov-chain approach. The optimal designs are found for numerical examples using a genetic algorithm combined with a pattern search algorithm and compared to those of the two-stage ${\bar{X}}$ chart. Sensitivity analysis is performed to see the parameter effects. Results: The proposed design outperforms the optimal design of the two-stage ${\bar{X}}$ chart in terms of the expected cost per unit time unless the correlation between the performance and surrogate variables is modest and the shift in process mean is smallish. Conclusion: Three-stage ${\bar{X}}$ chart may be a useful alternative to the two-stage ${\bar{X}}$ chart especially when the correlation between the performance and surrogate variables is relatively high and the shift in process mean is on the small side.

• 한국건축시공학회지
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• 제23권6호
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• pp.809-820
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• 2023

현대 사회에서는 1인 가구가 증가하고 주거 공간에 대한 수요가 증가하고 있으며 이에 대한 적절한 대안 모색이 중요하다. 빠른 시간 내에 경제적이고 지속 가능한 주거 공간을 제공하기 위한 방법으로 모듈러 건축이 주목받고 있다. 본 연구에서는 BIM(Building Information Modeling) 기술을 활용한 모듈러 건축 유닛 설계 및 시공 과정 최적화 방법을 제안한다. 1인 가구의 주거 요구사항과 삶의 질 향상을 위한 요인을 분석하였다. 이를 바탕으로 BIM을 활용하여 효율적이고 경제적인 모듈러 공동주택 유닛을 개발하였다. BIM은 건축 요소의 시각화 및 상호 연결을 제공하여 설계 과정의 오류를 최소화하고 생산성을 향상시킬 수 있다. 모듈러 건축의 장점과 한계를 평가하였다. BIM을 활용한 모듈러 건축물은 주거 문제를 해결할 수 있는 효과적인 대안으로 제시될 수 있으며 주거 공간의 품질과 다양성을 높일 수 있다. 다만 기술적 요구사항 및 비용 등의 한계도 고려되어야 한다. BIM 기반 1인 가구 공동주택 유닛 설계의 가능성과 장점을 제시하고 1인 가구 개선을 위한 실질적인 해결책으로 활용될 수 있다.

• ETRI Journal
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• 제40권2호
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• pp.266-274
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• 2018

In error-prone wireless environments, it is difficult to realize video coding systems that are robust to various types of data loss. In this paper, a novel motion-vector refinement approach is presented for video error concealment. A traditional boundary-matching approach is exploited to reduce blocky effects along the block boundary. More specifically, a downhill simplex approach is combined with a boundary-matching approach to fine-tune the motion vectors, reducing the blocky effects along the prediction unit block boundary, and minimizing the computational cost. Extensive simulations are performed, and the results obtained verify the robustness and effectiveness of the proposed approach.

• 한국지능시스템학회논문지
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• 제14권2호
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• pp.239-246
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• 2004

In this paper, we develop and implement a high integrity GNC(Guidance, Navigation, and Control) system, based on the combined use of the Global Positioning System (GPS) and an Inertial Measurement Unit (IMU), for autonomous land vehicle applications. This paper highlights guidance for the predetermined trajectory and navigation with detection of possible faults during the fusion process in order to enhance the integrity of the navigation loop. The implementation of the GNC system to the autonomous land vehicle presented with fault detection methodology considers high frequency faults from the GPS receiver caused by shadowing and multipath error The implementation, based on a low-cost, strapdown INS aided by standard GPS technology, is described. The results of the field test in the urban environment are presented and showed effectiveness of the GNC system.

• 제어로봇시스템학회논문지
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• 제14권3호
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• pp.295-300
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• 2008

In this paper, a new looper controller is proposed to minimize the tension variation of a strip in the hot strip finishing mill. The proposed control technology is based on a receding horizon control (RHC) to satisfy the constraints on the control input/state variables. The finite terminal weighting matrix is used instead of the terminal equality constraint. The closed loop stability of the RHC for the looper system is analyzed to guarantee the monotonicity of the optimal cost. Furthermore, the RHC is combined with a 4SID(Subspace-based State Space System Identification) model identifier to improve the robustness for the parameter variation and the disturbance of an actuator. As a result, it is shown through a computer simulation that the proposed control scheme satisfies the given constraints on the control inputs and states: roll speed, looper current, unit tension, and looper angle. The control scheme also diminishes the tension variation for the parameter variation and the disturbance as well.

• 조명전기설비학회논문지
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• 제24권10호
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• pp.49-57
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• 2010

In order to provide electricity to users economically and safely, distribution automation systems (DASs) monitor and operate components of distribution systems remotely through communication networks. The fiber optic communication network has been mainly installed for the DAS of Korea Electric Power Corporation (KEPCO) because of its huge bandwidth and dielectric noise immunity. However, the fiber optic communication network has some shortcomings that its installation cost and communication fee are expensive. This paper proposes a complex network where WLANs are combined with conventional fiber optic communication networks in order to expand DAS easily and inexpensively. A fixed wireless bridge communication unit (FWB-CU) for the proposed complex network is implemented using IEEE 802.11a WLAN technology. The proposed complex network is built actually to verify its feasibility experimentally as a DAS communication network.

• 전기학회논문지
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• 제61권1호
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• pp.173-178
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• 2012

The quantity bill writing of organized electrical construction can be an effective to quality and process management in the construction. Therefore, in order to overcome confusion of the construction and doing an effective work, the clearly quantity bill writing is need. This paper is a focused to solve a problem of existing quantity bill as the difference in terms of work section and item information, regulatory information of ordering authority. Therefore, a terms of work section and item information, regulatory information of ordering authority has been normalized. Moreover, basic data of simplification for quantity bill writing and structure has been guaranteed.

• International Journal of Computer Science & Network Security
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• 제23권8호
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• pp.33-39
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• 2023

The global surge in depression and anxiety, intensified by challenges such as cost and stigma, emphasizes the pressing need for accessible, evidence-based digital solutions. The research centers on the creation of a mobile application specifically designed to address mental health challenges. By integrating cognitive behavioral therapy techniques and features like appointment bookings and mindfulness feedback tools, the app is positioned to improve user outcomes. Utilizing platforms like React Native and React, combined with NestJS for enhanced backend security, the application adheres to the rigorous standards required for mental health interventions. Collaborative efforts with experts, notably the counseling unit of IIUM, ensure the app's alignment with contemporary best practices and research. Preliminary findings indicate a promising tool with the potential to address the global mental health treatment disparity.

• Journal of Advanced Marine Engineering and Technology
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• 제39권3호
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• pp.342-347
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• 2015

플로팅 엘엔지선박은 해상에서 LNG 생산 및 천연 가스 공급을 담당하는 새로운 개념으로 부유식 생산설비는 과도한 투자 비용으로 인해 개발 지연중인 한계 가스전에 활력을 주고 있으며, 부유식 공급설비는 육상 LNG 인수기지 인프라가 미비한 지역에 에너지를 경제적이며 효과적으로 공급할 수 있다는 장점을 제공하고 있다. LNG 화물창은 플로팅 엘엔지선박에서 생산 또는 적재된 LNG를 보관하는 주요기능 중 하나이다. 본 연구를 통해 기존 화물창 시스템들의 장점을 결합한 복합 화물창 시스템을 화물창 시스템의 설계 개선방안으로 제안하였고 플로팅 엘엔지선박에의 적용 타당성에 대한 연구를 수행하였다.