• 한국초전도ㆍ저온공학회논문지
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• 제24권2호
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• pp.7-18
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• 2022

European efforts to design superconducting conductors for a future tokamak have involved Nb₃Sn cable-in-conduit conductor (CICC). Nb₃Sn coils which undergo heat treatment to activate the Nb₃Sn material are mostly produced through the wind-then-react route. However, some Nb₃Sn coils have been proposed with CICCs of the react-then-wind route. The latter CICCs are physically constrained due to handling limitations which if not adhered to will result in irrecoverable damage to the Nb₃Sn cable inside, nullifying any performance advantage. A group at the Swiss Plasma Center has proposed such CICC designs, constructing samples and testing them for performance. The characteristics and performance of these react & wind (R&W) CICCs are compared with the more common wind & react (W&R) CICCs, and it is found that the R&W designs show more extreme characteristics than typical W&R Nb₃Sn CICCs for some parameters that are known to influence CICC performance. Where the R&W CICCs extend the range of those parameters, they also continue trends formed by the W&R CICCs with the parameters. The main observation, however, is that although the current sharing temperature performances of the R&W samples are above the average of the W&R samples they were compared to, they are not the highest. A similar observation applies to a cost comparison of the superconducting material where the R&W CICCs are found to be relatively cheap but not the cheapest. Given these results, clear practical advantages to the R&W CICC design is not evident.

• 한국항행학회논문지
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• 제27권1호
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• pp.146-153
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• 2023

산업통상자원부에서 추진하는 산업융합 규제 샌드박스 의결에 따라, 산학협력업체인 마이메이커(주)에서 신청한 "공장 내 공작기계 공유 서비스"를 실증 특례를 받았다.[1] 이를 실행하면서 수발주 서비스 부분을 소프트웨어로 개발해야 하는 상황으로 업체의 제조 도메인 문제를 파악 분석하고 절차를 정립하고 관련 요구사항에 맞는 시스템을 설계하였다. LINC+ 산업체 애로 사항 해결 공동연구 개발 프로젝트로 공유 온 팩토리 서비스[2]를 위한 수발주시스템을 최종 개발했다. 수 발주 시스템에 필요한 데이터 구조를 설계하고 관련 데이터를 활용한 화면 설계와 사용자 관점의 기능 구현을 중심으로 하였으며 정립된 절차와 요구사항 분석에 맞추어 기획, 설계, 프로토타이핑, 구현 제작 단계로 진행했다. 마지막으로 최종개발 내용을 요구사항에 맞게 잘 구현되었는지 검토 및 기능 검증 시연과 제품 인수인계를 통해 애로 사항 해결을 확인하였다.

• 한국산업융합학회 논문집
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• 제26권6_2호
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• pp.1097-1108
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• 2023

Recently, demand for technology for energy economy and stable supply is increasing due to the increase in power demand of loads. The amount of DC power generation using new and renewable energy is noticeably increasing, and the use of DC power supplies is also increasing due to the increase in electric vehicles and digital loads. During parallel operation to increase the capacity of the power converter, the module bus method or the method using Can communication and serial communication has significant difficulties in smooth operation due to communication time delay for information sharing. Synchronization of information sharing of each power converter is essential for smooth parallel operation, and minimization of communication time delay is urgently needed as a way to overcome this problem. In this paper, a new communication method using pulse width information is proposed as a communication method specialized for parallel operation of power converters to compensate for the disadvantage of communication transmission delay in the existing system. The proposed communication method has the advantage of being easily implemented using the PWM and Capture function of the microcomputer. In addition, the DC/DC converter for DC distribution was verified through simulation and experiment, and it has the advantage of easy capacity expansion when applied to parallel operation of various types of power converters as well as DC/DC converters.

• Journal of Communications and Networks
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• 제14권6호
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• pp.662-671
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• 2012

Plug-in hybrid electric vehicles (PHEVs) will be widely used in future transportation systems to reduce oil fuel consumption. Therefore, the electrical energy demand will be increased due to the charging of a large number of vehicles. Without intelligent control strategies, the charging process can easily overload the electricity grid at peak hours. In this paper, we consider a smart charging and discharging process for multiple PHEVs in a building's garage to optimize the energy consumption profile of the building. We formulate a centralized optimization problem in which the building controller or planner aims to minimize the square Euclidean distance between the instantaneous energy demand and the average demand of the building by controlling the charging and discharging schedules of PHEVs (or 'users'). The PHEVs' batteries will be charged during low-demand periods and discharged during high-demand periods in order to reduce the peak load of the building. In a decentralized system, we design an energy cost-sharing model and apply a non-cooperative approach to formulate an energy charging and discharging scheduling game, in which the players are the users, their strategies are the battery charging and discharging schedules, and the utility function of each user is defined as the negative total energy payment to the building. Based on the game theory setup, we also propose a distributed algorithm in which each PHEV independently selects its best strategy to maximize the utility function. The PHEVs update the building planner with their energy charging and discharging schedules. We also show that the PHEV owners will have an incentive to participate in the energy charging and discharging game. Simulation results verify that the proposed distributed algorithm will minimize the peak load and the total energy cost simultaneously.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권7호
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• pp.2496-2512
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• 2021

The requirements for powerful computing capability, high capacity, low latency and low energy consumption of emerging services, pose severe challenges to the fifth-generation (5G) network. As a promising paradigm, mobile edge networks can provide services in proximity to users by deploying computing components and cache at the edge, which can effectively decrease service delay. However, the coexistence of heterogeneous services and the sharing of limited resources lead to the competition between various services for multiple resources. This paper considers two typical heterogeneous services: computing services and content delivery services, in order to properly configure resources, it is crucial to develop an effective offloading and caching strategies. Considering the high energy consumption of 5G base stations, this paper considers the hybrid energy supply model of traditional power grid and green energy. Therefore, it is necessary to design a reasonable association mechanism which can allocate more service load to base stations rich in green energy to improve the utilization of green energy. This paper formed the joint optimization problem of computing offloading, caching and resource allocation for heterogeneous services with the objective of minimizing the on-grid power consumption under the constraints of limited resources and QoS guarantee. Since the joint optimization problem is a mixed integer nonlinear programming problem that is impossible to solve, this paper uses deep reinforcement learning method to learn the optimal strategy through a lot of training. Extensive simulation experiments show that compared with other schemes, the proposed scheme can allocate resources to heterogeneous service according to the green energy distribution which can effectively reduce the traditional energy consumption.

• 한국수소및신에너지학회논문집
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• 제33권4호
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• pp.267-283
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• 2022

In these day, the environmental issues of climate change have been continuously highlighted and there is an active discussion on the transition from fossil fuel-based energy to eco-friendly energy use. This study considered psychological attitudes as a major influencing factors for successful implementation of a hydrogen society totally based on the use of hydrogen energy, which is regarded as an alternative energy for future. Accordingly, familiarity, risk perception, and acceptability of psychological factors were investigated. In addition, this study identified whether there are differences in psychological factors according to the general characteristics of gender, age, occupation, and housing type. The results showed that awareness of hydrogen cars and fuels is below the average level, and we also have obtained the implication that social knowledge sharing should precede the implementation of hydrogen policy. Although we found that the degree of urban acceptance of hydrogen energy was high, it was also confirmed that the charging infrastructure was generally perceived as having a high risk. Our findings implicate that it is necessary to figure out policy strategies for suitable locating charging infrastructure in order to promote the use of hydrogen energy more.

• 한국초전도ㆍ저온공학회논문지
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• 제3권1호
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• pp.11-15
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• 2001

Stability of a Bi-2223/Ag tape was studied by using a numerical model considering the temperature distribution of cross-sectional area. The dynamic evolution of normal zone of a HTS tape can be shown by the developed two-dimensional Program using finite difference method. Two kinds of analyses are compared to quantify the critical disturbance energy for quenching HTS tapes. One is the length-thickness(x-r) side and the other is the length-width(x-z) side. For each case. the governing energy balance equations and corresponding boundary conditions are formulated. The results of analyses shows that the critical disturbance energies for each cases seem to be very close for considered Bi-2223/Ag tape .

• 신재생에너지
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• 제3권4호
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• pp.69-76
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• 2007

In this paper, a PV multi-string PCS with a grid-connection is proposed. An improved MPPT algorithm for the PV multi-string PCS is suggested. Each PV string has its own MPP tracker and the proposed MPPT algorithm prevents LMPP tracking due to power ripple. In the PV PCS with single-phase inverter has a large current ripple at twice the grid frequency. The current ripple reduction algorithm without external component is suggested. Also, this paper proposes a simple control method to achieve sharing of the PV string voltage and current among the interleaved parallel boost converters. All algorithms and controllers are implemented on a single-chip microcontroller. Experimental results obtained on a 3kW prototype show high performance of the proposed PV multi-string PCS.

• 한국위성정보통신학회논문지
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• 제8권3호
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• pp.6-9
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• 2013

Cognitive Radio는 유휴 스펙트럼을 찾아 환경에 맞는 통신방식과 주파수 대역폭을 능동적으로 판단해 재활용하는 지능적인 간섭회피로 방식으로 스펙트럼을 공유하여 전파자원효율을 극대화 하는 기술이다. 이때 PU에 간섭을 일으키지 않기 위한 스펙트럼 센싱 기술이 중요하다. 하지만 상황에 따라 스펙트럼 센싱 알고리즘을 선택할수 있다면 좀더 효율적 센싱을 할수 있을 것이다. 따라서 본 논문에서는 퍼지컨트롤러를 통해 에너지검출, 자기상관검출,M atched filter 검출 등을 개별 센싱에 반영하는 시스템 모델을 제안하고 분석한다.

• Journal of Radiation Protection and Research
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• 제13권2호
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• pp.88-94
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• 1988

조사된 경수로 핵연료의 도로 수송시, 방사선 영향을 INTERTRAN 코드로 평가하였다. 계산된 결과는 인구밀도로 구분한 각 지역의 소집단과 작업자에 따라 집단 선량당량으로 구하였다. 정상 수송과 수송 사고에 대한 평가 결과, 각 집단의 선량은 매우 낮은 수준을 나타내었다. 계산 프로그램은 다양한 입력 자료에 의하여 정량화 되므로 앞으로 입력 자료의 확보를 위한 연구가 필요하다.