• 사물인터넷융복합논문지
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• 제6권4호
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• pp.1-6
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• 2020

최근 코로나 19 확산으로 비대면 화상회의에 대한 수요가 급증하고 있다. 기존의 줌, 구글 미트와 같은 서버-클라이언트 기반의 화상회의 시스템에서 서버는 회의키를 이용하여 회의 멤버 및 회의 내용을 제어한다. 만약 서버를 신뢰할 수 없다면 서버에 의한 조작 및 부정이 가능하기 때문에 회의 멤버들의 프라이버시는 보장되지 않는다. 따라서, 서버의 도움 없이 모든 참여자가 신뢰할 수 있는 회의키 생성 및 분배 기법의 개발이 필수적이다. 스마트계약은 블록체인에 저장되는 프로그램으로 블록체인의 특성상 수정될 수 없고 누구나 그 실행 결과를 검증할 수 있다. 본 논문에서는 스마트계약 기반의 회의용 키 분배 기법을 제안한다. 제안한 방법은 키 분배를 위한 스마트계약 발행, 회의키 생성 및 검증 단계로 구성된다. 스마트계약은 기존의 신뢰할 수 있는 서버의 역할을 대체하며, 회의 멤버들은 스마트계약에 구현된 프로토콜에 따라서 회의키를 생성한다. 제안한 방법은 화상회의 시스템에 적용할 수 있으며, 회의 멤버 이외의 다른 사용자들은 회의키에 접근할 수 없다.

• 디지털융복합연구
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• 제11권3호
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• pp.209-219
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• 2013

스마트폰 모바일 환경의 보편화는 기술의 진보 뿐만 아니라 소비자의 생활패턴의 변화에도 직접적인 영향을 미친다. 이렇듯 스마트폰과 같은 디지털 컨버전스 환경으로 패러다임이 변화함에 따라 소비자를 둘러싼 상품, 서비스, 그리고 유통환경까지 모든 것이 변화하고 있다. 그 변화의 한 가운데 국내 기업인 홈플러스에서는 세계 최초로 오프라인매장과 온라인 매장의 장점을 결합한 가상 스토어를 설치하고 모바일 쇼핑을 가능케 하는 제 4세대 유통모형을 운영하고 있다. 이에 본 연구는 홈플러스의 모바일 가상 스토어에 대한 사례 분석 및 소비자의 체험 평가를 통하여 소비자중심적 관점에서 새로운 디지털 유통 모델로서 모바일 가상 스토어의 발전 방안을 제언하고자 하였다. 기술이 혁신적으로 진보하는 경우, 기술의 개발에 초점이 맞추어지고 소비자는 수용자로서의 역할을 하지만 기술이 안정적으로 구현되고, 더 큰 산업의 발달을 위해서는 소비자 중심적 관점에서 평가하는 것이 매우 중요하다고 보았다. 이에 본 연구의 소비자 행동 중심적인 관점에서 스마트 가상 스토어를 평가하는 것은 새로운 유통모델의 등장 및 성공적 확산을 위해 필요한 탐색적 연구로서의 의의가 크다.

• 한국농공학회논문집
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• 제64권2호
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• pp.1-13
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• 2022

Agrivoltaic facility is the composite system that the solar panel is installed above the farmland, and it enables crop and electricity production simultaneously. Solar panels of the agrivoltaic facilities can block and reduce the amount of solar irradiance arriving at the farmland, but it can help the crop growth by preventing excessive solar irradiance. Therefore, to clarify how the agrivoltaic facilities affect the crop growth, precise solar irradiance distribution under the solar panel should be modeled. In this study, PAR (photosynthetically active radiation), radiation from 400 to 700 nm, which crops usually use to grow, was extracted from the total irradiance and its distribution model under various conditions was developed. Monthly irradiance distributions varied because the elevation of the sun was changed over time, which made the position changed that the local maximum and minimum irradiance appear. The higher panel height did not cause any significant difference in the amount of irradiance reaching below the solar panel, but its distribution became more uniform. Furthermore, the panel angles with the most irradiance arriving below the solar panel were different by month, but its difference was up to 2%p between the irradiance with 30° angle which is usually recommended in Korea. Finally, the interval between panels was adjusted; when the ratio of the length of the panel to the empty space was 1:2, the irradiance of 0.719 times was reached compared to when there was no panel, 0.579 times for 1:1 and 0.442 times for 2:1.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2012년도 춘계학술발표대회 논문집
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• pp.419-424
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• 2012

This paper discusses the state-of-the-art techniques in real-time state estimation for the Smart Microgrids. The most popular method used in traditional power system state estimation is a Weighted Least Square(WLS) algorithm which is based on Maximum Likelihood(ML) estimation under the assumption of static system state being a set of deterministic variables. In this paper, we present a survey of dynamic state estimation techniques for Smart Microgrids based on Belief Propagation (BP) when the system state is a set of stochastic variables. The measurements are often too sparse to fulfill the system observability in the distribution network of microgrids. The BP algorithm calculates posterior distributions of the state variables for real-time sparse measurements. Smart Microgrids are modeled as a factor graph suitable for characterizing the linear correlations among the state variables. The state estimator performs the BP algorithm on the factor graph based the stochastic model. The factor graph model can integrate new models for solar and wind correlation. It provides the Smart Microgrids with a way of integrating the distributed renewable energy generation. Our study on Smart Microgrid state estimation can be extended to the estimation of unbalanced three phase distribution systems as well as the optimal placement of smart meters.

• 스마트미디어저널
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• 제12권5호
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• pp.65-72
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• 2023

스마트팜은 농업과 ICT의 융복합을 통해 농업의 생산뿐만 아니라 유통과 소비를 포함한 농업과 관련된 다양한 분야로 새로운 가치를 창출하는 것을 의미한다. 국내에서도 스마트 농업 확산을 위한 임대형 스마트팜을 조성하고, 스마트팜 빅데이터 플랫폼을 구축하여 데이터 수집·활용 촉진. 스마트 APC 확대, 온라인거래소 운영 및 도매시장 거래정보 디지털화 등 산지에서 소비지까지 농산물 유통 디지털 전환을 추진하고 있다. 이처럼 농업 데이터는 다양한 출처에서 특성에 따라 정보가 생성되고 있지만, 통계 및 정형화된 데이터를 이용한 서비스로만 활용되고 있다. 이는 농업에서 생산·유통·소비까지 분산된 데이터 수집으로 인해 한계가 있으며 다양한 출처로부터의 다양한 형태의 데이터를 수집·처리하기 어렵기 때문이다. 그러므로 본 논문에서는 디지털 농업을 위한 국내 농업 데이터 수집·공유 현황을 분석하고 인공지능 서비스를 위한 데이터 수집·연계 방법을 제안한다. 그리고 제안하는 데이터를 이용하여 딥러닝 기반의 환경 인자를 추천하는 방법을 제안한다.

• 전기학회논문지
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• 제61권1호
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• pp.1-6
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• 2012

Five smart grid projects was started with large scale at Jeju Island in South Korea from 2009, and smart-grid test-bed was started in Nov. 2010. The five projects are Smart Power Grid (SPG), Smart Renewable (SR), Smart Transportation (ST), Smart Place (SP) and Smart Electric Service (SES). Korea government constructed the smart grid public relations center at Nov. 2010 in Jeju Island and there will be continued the field operation and interface testing among five smart gird projects until May. 2013.

• 산경연구논집
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• 제13권10호
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• pp.31-39
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• 2022

Purpose: Smart city has been observed to benefit most urban areas in different nations. Despite its advantages in the promotion of environmental sustainability and improving business competency in the current context, various literature review papers should be introduced to analyze its drawbacks. The present research aims to provide valuable suggestions for sustainable smart cities development. Research design, data and methodology: Using the qualitative content analysis (QCA), the current author could understand the target audience's motivations and habits by gathering data. This implies that the author may predict the kinds of future initiatives. As a result, the current researcher could ensure developed pertinent research questions and a well-planned method for analyzing the replies. Results: The implementation of green city development suggests encouraging the greening of public spaces and reducing heat from the atmosphere caused by the emission of gases from vehicles and companies. Smart cities are offering a new industrial paradigm that is based on the convergence of information technology. Conclusions: The projection illustrates that most people are migrating to the cities, which calls for an immediate transformation to overcome the immense pressure of making the city accessible, sustainable, prosperous, and safer. Therefore, implementing smart cities within the current world promotes efficiency and increases business sustainability.

• 전기학회논문지
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• 제61권10호
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• pp.1412-1419
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• 2012

In this paper, we propose the protection coordination algorithm using communication methode based on IEC 61850. The communication protocol in power distribution management system has been issued by IEC standard, IEC61850 of them, which was made for substation automation system, has researched to apply into power distribution system, even though the standard is not a suitable for the system. In smart distribution management system' launched in 2009, the communication network based on the ethernet network for IEC 61850 has been designed to apply the self-healing concept, which is to perform the system protection through the communication between remote terminal units(RTU) according to the standard. However, it is first time to apply the scheme in the real. Thus, this paper proposed the protection algorithm and consideration for applying communication method and introduced the result of demonstration.

• 전기학회논문지
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• 제61권8호
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• pp.1083-1090
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• 2012

In this paper, we present the section load estimation program of distribution system for smart distribution management system. The proposed program is composed with three parts. One is the consistency check part for switch measurements which consist a section. The consistency check is divided into the current and angle test. For the current test, we examine the input and output power flow for the switch group. For the angle test, the result of power flow calculation at previous step is used. Another is the voltage estimation part for the measured switches. We use the weighted least square (WLS) method for the voltage estimation. The third is the part of final section load calculation. The database structure for accomplishing the developed estimation program is also proposed. To verify the accuracy of the experimental results, case studies are performed using a actual data of Jeju island. The developed program can be effectively applied to the distribution operation systems.

• Journal of Electrical Engineering and Technology
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• 제7권6호
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• pp.824-833
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• 2012

In this paper, a coordinated state-of-charge (SOC) control strategy for the energy storage system (ESS) operating under microgrid islanded mode to stabilize the frequency and voltage was proposed. The proposed SOC control loop is made up of PI controller, which uses a SOC state of the energy storage system as an input and an auxiliary reference value of secondary control as an output. The SOC controller changes the auxiliary reference value of secondary control to charge or discharge the ESS. To verify the proposed control strategy, PSCAD/EMTDC simulation study was performed. The simulation results show that the SOC of the ESS can be regulated at the desired operating range without degrading the stabilizing control performance by proposed coordinated SOC control method.