• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 A
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• pp.342-344
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• 2002

This paper presents a new strategy to find starting points for placing optimally Phasor Measurement Units(PMUs). The performance of the starting point, initial placement set of PMUs, affect critically the computational burden and/or time, because the Optimal PMU Placement (OPP) problem is formulated the combinatorial optimization. By analyzing the properties of OPP solutions on IEEE sample systems in detail, a new strategy for initial PMU placement, in this paper, is proposed. To verify the performance of the suggested strategy, the comparison with the existing strategy and the new one, on IEEE sample systems. is performed. By using the new strategy, the numbers of search spaces to solve the OPP problem is drastically decreased.

• 한국직업건강간호학회지
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• 제32권4호
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• pp.141-151
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• 2023

Purpose: This study explored caregivers' support needs to relieve their physical burden while working in long-term care facilities. Methods: Participants were 12 caregivers with more than 10 years of experience working at six long-term care facilities in Gwangju, South Korea. Data were collected through individual interviews conducted between June and July 2023. The results were analyzed using qualitative content analysis. Results: Of the four sub-categories and 13 codes, two categories emerged: "need for welfare medical devices" and "need for improved working conditions." Conclusion: Caregivers working in long-term care facilities require support in deploying and utilizing welfare medical devices to reduce their physical burden, along with improving staffing standards and ensuring they receive the proper amount of days off. Therefore, it is necessary to mandate the provision of a certain level of welfare medical devices to ease the physical burden on caregivers and improve the standards for the placement of caregivers in long-term care facilities.

• Smart Structures and Systems
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• 제31권3호
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• pp.247-257
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• 2023

In structural health monitoring of large-scale structures, optimal sensor placement plays an important role because of the high cost of sensors and their supporting instruments, as well as the burden of data transmission and storage. In this study, a vibration sensor placement algorithm based on deep reinforcement learning (DRL) is proposed, which can effectively solve non-convex, high-dimensional, and discrete combinatorial sensor placement optimization problems. An objective function is constructed to estimate the quality of a specific vibration sensor placement scheme according to the modal assurance criterion (MAC). Using this objective function, a DRL-based algorithm is presented to determine the optimal vibration sensor placement scheme. Subsequently, we transform the sensor optimal placement process into a Markov decision process and employ a DRL-based optimization algorithm to maximize the objective function for optimal sensor placement. To illustrate the applicability of the proposed method, two examples are presented: a 10-story braced frame and a sea-crossing bridge model. A comparison study is also performed with a genetic algorithm and particle swarm algorithm. The proposed DRL-based algorithm can effectively solve the discrete combinatorial optimization problem for vibration sensor placements and can produce superior performance compared with the other two existing methods.

• 대한전기학회논문지:전력기술부문A
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• 제49권7호
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• pp.313-322
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• 2000

This paper presents optimal placement of minimal set of Phasor Measurement Units (PMU's) and observability analysis of the network with PMU's. In order to find a observable system, a symbolic method which directly assigns an appropriate symbol for measurement or pseudo-measurement to every entry of node-branch incidence matrix is proposed. It is much simpler and easier to analyze the observability of the network with PMU's than the conventional ones. For the optimal PMU placement problem, two approaches which are based on a modified Simulated-Annealing (SA) method and a Direct Combination method are proposed. Some case studies with IEEE sample system are made to show the performance of the proposed methods are almost alike and more effective than the conventional simulated-annealing method. It is also shown that the Direct Combination method is more effective than the modified simulated-annealing one in the sense of computation burden. The results of this study showed also that the accuracy of power system estimation and system observability can be improved the proposed PMU placements.

• 대한전기학회논문지
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• 제39권4호
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• pp.364-370
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• 1990

In this paper, we propose a self-tuning PID controller for unknown systems with time-varying delay. Using pole placement equations, we derive the controller that can be extended to the multi-step time delay case. The time-varying delays are estimated by a prediction error delay method using multiple predictors. Since the order of the estimation vector is not increased, the persistant exciting condition of control input is alleviated. Since the least square method gives biased parameter estimates for colored noise cases, the recursive instrumental variable method is used to estimate system parameters. The computational burden of the proposed method is less than the conventional adaptive methods. Computer simulations are performed to illustrate the efficiency of the proposed method.

• 미래기술융합논문지
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• 제3권3호
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• pp.47-56
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• 2024

본 연구는 사회복지학과 성인학습자의 사회복지현장실습경험을 분석하고 개선점을 논의하는 것을 목적으로 한다. 사회복지현장실습은 사회복지사가 되기 위한 필수과정이다. 사회복지현장실습을 통해 성인학습자들은 이론적으로 배운 교육을 실제 현장에서 적용하고 예비사회복지사로서 미래의 역할을 이해할 수 있는 소중한 기회를 얻을 수 있다. 그러나 사회복지현장실습이 성인학습자의 특성을 적절하게 반영하지 못한다면 성공적인 사회복지현장실습 경험을 보장하기 어려울 수 있다. 성인학습자가 사회복지실습을 성공적으로 마무리 짓기 위해서는 대학과 실습기관의 통합적이고 일관된 지원이 필수적이다. 성인학습자의 실습경험에서 직면할 수 있는 어려움은 시간 관리의 힘듦, 심리적 스트레스, 이론과 실제의 간극 등이 있는데 이러한 문제를 해결하는 것이 필요하며, 가장 중요한 것은 실습 전 철저한 준비가 선행되어야 하겠다.

• 교육시설 논문지
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• 제26권2호
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• pp.11-18
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• 2019

There is a growing demand for public kindergartens due to the problem of private kindergartens. However, when the kindergarten is built in the residential land development area, the cost of purchasing the land increases, and the overall project cost is increasing. This situation puts a lot of burden on educational finances. Therefore, to reduce the cost of establishing a kindergarten, it is required to revise related laws including act on the special cases concerning the procurement, etc. of school sites. The purpose of this study is to propose the revised laws to expand public kindergartens. In this study, the present situation of infants and kindergartens was analyzed through policy data and statistics. And the analysis of the investment evaluation data also analyzed the problems in establishing kindergarten. In addition, we conducted surveys and FGI analyzes on school sites and kindergarten related laws and regulations. Finally, this study aims to find a way to amend related acts of urban and architectural Planning for Invigoration of Public kindergarten establishment by analysis data.

• Journal of Power Electronics
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• 제19권4호
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• pp.1000-1010
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• 2019

The use of internal-model-based linear controller, such as resonant controller, is a well-established technique for the current control of grid-connected systems. Attractive properties for resonant controllers include their two-sequence tracking ability, the simple control structure, and the reduced computational burden. However, in the case of continuous-designed resonant controller, the transient performance is inevitably degraded at a low switching frequency. Moreover, available design methods for resonant controller is not able to realize the direct design of transient performances, and the anticipated transient performance is mainly achieved through trial and error. To address these problems, the zero-order-hold (ZOH) characteristic and inherent time delay in digital control systems are considered comprehensively in the design, and a corresponding hold-equivalent discrete model of the grid-connected converter is then established. The relationship between the placement of closed-loop poles and the corresponding transient performance is comprehensively investigated to realize the direct mapping relationship between the control gain and the transient response time. For the benefit of automatic tuning and real-time adaption, analytical expressions for controller gains are derived in detail using the required transient response time and system parameters. Simulation and experimental results demonstrate the validity of the proposed method.

• 대한치과보철학회지
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• 제53권1호
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• pp.58-65
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• 2015

완전 무치악 환자의 수복 시 총의치나 임플란트 지지 피개의치와 더불어 임플란트를 지대치로 이용하는 국소의치가 치료 방법의 하나로 고려될 수 있다. 적은 수의 임플란트를 전략적으로 중요한 위치에 식립한 후 가철성 국소의치로 수복할 경우, 임플란트를 통해 안정을 얻고 부가적으로 유지 및 지지를 확보할 수 있을 뿐만 아니라 광범위한 임플란트 식립을 통한 고정성 보철물에 비해 환자의 수술 부담을 줄여줄 수 있으며, 치료비용 절감 효과도 기대할 수 있다. 본 증례는 오랫동안 국소의치를 사용해 온 환자에서 치아 상실 후 잔존 치조골의 상태 및 환자의 요구를 고려하여 임플란트 지지 국소의치를 제작한 증례로서 전치부에 식립한 임플란트는 고정성 보철물로 수복하고 구치부의 짧은 임플란트는 지지 기능만 부여하였다. 또한 의치상과 클래스프를 열가소성 아크릴 레진으로 제작함으로써 기능적, 심미적으로 만족스러운 치료 결과를 얻었기에 이를 보고하는 바이다.

• 실천공학교육논문지
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• 제12권2호
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• pp.309-319
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• 2020

당구는 재미있는 스포츠이지만, 처음 입문한 초심자가 득점 가능한 경로를 계산하고 올바르게 공을 쳐서 보낼 정도로 숙련되기까지의 진입 장벽이 높은 편이다. 당구 초심자가 어느 정도 수준에 도달하기 위해선 지속적인 집중과 훈련을 필요로 하는데, 적절한 동기 부여 요소가 없다면 흥미를 잃어버리기 쉽다. 본 연구는 스테레오 카메라와 VR 헤드셋을 결합한 몰입도 높은 증강 현실 플랫폼 상에서 당구 경로 안내 및 시각 효과를 통해 초심자의 흥미를 유도하고 당구 학습을 가속하는 것을 목표로 두었다. 이를 위해 영상처리를 활용하여 당구공 배치를 인식하고 Unity Engine의 물리 시뮬레이션을 통해 경로 탐색과 시각화를 수행해 실제와 유사한 경로 예측을 구현했다. 이는 당구에 처음 입문하는 초심자가 경로 설계에 대한 부담 없이 공을 올바르게 보내는 훈련에만 집중할 수 있게 만들며, 나아가 오랜 시간 알고리즘이 제안하는 경로를 익힘으로써 점진적으로 당구 숙련도를 높일 수 있다는 점에서 AR 당구의 학습 보조 도구로서의 가능성을 확인할 수 있었다.