• The Journal of the Convergence on Culture Technology
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• v.5 no.4
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• pp.401-406
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• 2019

The three-dimensional precision numerical analysis was performed using the finite element model applied with the railway track model consisting of rails, sleepers, and track elastic springs(ballast, rail pad). As a result of analyzing the track deformation level of the existing tracks due to the excavation work adjacent to the railway facilities, it was found that the track irregularity evaluation criteria (allowed values) of both conventional and high-speed railways lines were satisfied. Based on the numerical analysis using the track model, it was analyzed that the results of the prediction of the track irregularity due to the excavation work and the level of the track deformation occurring at the actual site could be approximated as closely as possible.

• Proceedings of the KIEE Conference
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• summer
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• pp.503-505
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• 2004

본 연구의 목적은 가공배전선로의 이도 및 장력 검토업무를 단순화하고 업무효율을 향상하는데 있다. 따라서 EDS(Every Day Stress)하중조건과 $고\cdot저온계$ 하중조건간의 임계경간을 계산할 수 없는 기존임계경간식의 한계점을 해결하기 위하여 다 조건간의 임계경간식을 개발하였으며, 이를 가장 많이 사용하는 알루미늄피복 강심 알루미늄 절연전선(ACSR/AW-OC)에 적용하는 방법을 보여주고 최종적으로 지역별 임계경간 및 적용하중조건 표를 완성하여 설계시 활용할 수 있도록 하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.1
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• pp.259-264
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• 2014

IEEE 802.15.4 has been emerging as the popular choice for various monitoring and control applications. In this paper, a fault management system for DC power-lines has been designed using IEEE 802.15.4, in order to monitor DC power-lines in real time, and to rapidly detect faults and shut off the line where such faults occur. Numbers were allocated for each node and unslotted CSMA-CA method of IEEE 802.15.4 was used, the performance of which was analyzed by a simulation. For such purpose, a total of 60 bits of the control data consisting of 16 bits of the current, 16 bits of the amplitude, 28 bits of the terminal state data were sent out, and the packet transfer rate and the transmission delay time of the fault management system for DC power-lines were measured and analyzed. When the traffic load was 330 packets per second or lower, the average delay time was shown to be shorter than 0.02 seconds, and when the traffic load was 260 packets per second or lower, the packet transfer rate was shown to be 99.99% or higher. Therefore, it was confirmed that the stringent condition of US Department of Energy (DOE) could be satisfied if the traffic load was 260 packets per second or lower, The results of this study can be utilized as basic data for the establishment of the fault management system for DC power-lines using IEEE 802.15.4.

• Therapeutic Science for Rehabilitation
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• v.10 no.3
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• pp.23-41
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• 2021

Objective : The purpose of this study was to analyze the effects of simultaneous dual-task training to assess executive function in older adults. Methods : We searched the PubMed, EMBASE, Cochrane, Web of Science, and RISS databases of publicated studies in the past decade. Seven studies were selected based on the inclusion and exclusion criteria. Qualitative assessment and meta-analysis were performed for the seven studies. Results : A randomized controlled trial design was used in the selected studies, and PEDro Scores above seven were obtained. The Trial Making Test (TMT) evaluated the effects of dual-task training on executive function in four studies. The Color Trail Test (CTT) was used in two studies, and Stroop test was used in three studies. The effect size for total executive function was 0.38, which was small. The effect sizes for TMT and CTT were 0.37. Stroop Test was 0.34, demonstrating that their effect sizes were also small. Only significant effects in total executive function, TMT, and CTT showed significant effects (all p<0.05). Conclusion : This study confirmed that dual-task training was effective in improving executive function in older adults. To improve the effectiveness of dual-task training, the difficulty of the dual-task training should be considered. It is also necessary to implement assessments that can evaluate performance under dual-task conditions as well as conventional test tools for executive function. In the future, dual-task training could be used as an appropriate intervention for executive function in older adults to delay the onset of dementia.

• Korean Journal of Optics and Photonics
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• v.14 no.4
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• pp.429-433
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• 2003

We try to analyse the localization phenomenon of a lightwave in random media by means of considering the solution of the propagation equation on a transmission line in which the propagation constants are randomly distributed. Lightwave localization is generated at the turning point where the solution is changed suddenly from an increase to a decrease. First, in order to investigate the changing process of the solution, we have derived the approximated one-dimensional Schrodinger equation from the two-dimensional wave equation by using the Brags condition. Considering the many types of solutions of the wave equation, we have investigated the conditions that allow the solutions to exist. Also, we have investigated the relationships between the localization of the solution and the variation of the propagation constant. In case of the exponential solution, we know that the permittivity $\varepsilon$=(0,0$\varepsilon$$_{0}$) is a very important parameter to influence the phase of the lightwave and to generate the localization.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.1079-1082
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• 2015

In Article 23 of Technical regulations for Telecommunication Line and Facilities, we have criteria of separation distance between telecommunication lines and power lines, and its related exceptional conditions. However, this is a conflicts condition with Article 32 that provides the type of indoor telecommunication cables such as twisted-pair cables and optical fiber cables. Also, it is frequently raised that exceptional condition related the PoE cables with up to 15.4W is improved to accept PoE cables with up to 30W. In this paper, we have proposed improvement plans of Technical regulations for separation distance between telecommunication lines and power lines by analyzing the variety of standard specifications at home and abroad.

• Journal of the Korean Society for Railway
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• v.16 no.4
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• pp.246-252
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• 2013

The vibration characteristics of railway vehicles are very complex because they are not only dependent on vehicle and track conditions but also on operating conditions. Vibration can cause the failure of rolling stock equipment. To verify that the quality of rolling stock equipment is acceptable, it should be able to withstand vibration tests of reasonable magnitude and duration. There are many standards for vibration and shock tests of equipment in Korea. In this paper, we have reviewed and compared the standards (KS R 9144, R 9146 and IEC 61373) for vibration and shock tests.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.8 no.1
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• pp.37-45
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• 1994

A method of optimal active and reactive power control for economic operation in electrical power system is presented in this paper. The major features and techniques of this paper are as follows: 1) The method presented for obtaining the equivalent active power balance equation applying the sparse Jacobian matrix of power flow equation instead of using B constant as active power Balance equation considering transmission loss, and for determining directly optimal active power allocation without repeating calculations. 2) More reasonable and economic profit by minimizing total fuel cost of thermal power plants instead of using transmission loss as objective function of reactive Power control can be achieved. 3) Particularly in reactive power control, computing time can be considerably reduced by using Fuzzy Linear Programming instead of using conventional Linear Programming.

• Proceedings of the Korean Society of Computer Information Conference
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• 2016.07a
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• pp.259-260
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• 2016

본 논문에서는 전력선의 부식에 따른 물성 변화에 대한 확인 및 검증을 위한 연구를 수행하였다. 산업단지 및 염해지역에 설치되어진 송전선로에 사용되고 있는 강심알루미늄연선(Aluminum Conductors Steel Reinforced, ACSR)은 타 지역에 비하여 스페이서, 슬리브 등의 접속부에서의 부식 정도가 상당히 빠르게 진행된다. 따라서 현재와 같은 내용연한을 획일적으로 적용할 수 없으므로 설치된 선로의 주위 환경 및 사용되는 부하의 조건 등이 반영된 합리적인 송전선로 운용이 필요하다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2007.04a
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• pp.364-366
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• 2007

본 논문은 철도차량이 주행하는 선로에 존재하는 수많은 곡선과 경사, 속도 제한 조건 때문에 열차성능해석 계산시 열차의 견인, 제동 특성이 비선형이기 때문에 해석적인 방법으로 해를 구하는데 어려움이 많은 경제운전 문제를 운행 시간 여유분을 고려하여 에너지 소비를 최소화하는 운전 모형을 제시한다. 경제운전모형을 한국형 고속열차에 적용하여 그 타당성을 입증하였다.