• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.244-245
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• 2007

Specially, High Temperature Superconducting power-transmission cable(HTS cable), 3-phase 100m long, 22.9kV class HTS power transmission cable system have been developed by Korea Electrotechnology Research Institute (KERI) and LS cable Ltd. that is one of 21st century frontier project in Korea. This cable was installed in KEPCO(Go-chang) testing site. In case of manufacturing HTS cable, superconducting joint is very important because they need very long tapes. Therefore, this paper gives some investigation of AC Loss in joined HTS tape by using several joint methods. Finally, this paper was shown background data for the form of HTS cable joint.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.2
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• pp.126-132
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• 2009

This study examined the differences in spatio-temporal parameters, joint angle, ground reaction force (GRF), and joint power according to the changes of gait speed for trans-tibial amputees to investigate the features of the energy-storing foot for sports. The subjects walked at normal speed and at fast speed, wearing a single-axis type foot (Korec) and an energy-storing foot for sports (Renegade) respectively. The results showed that Renegade yielded faster gait speed as well as more symmetric gait pattern, compared to Korec. However, as gait speed was increased, there was no significant difference in kinematics, ground reaction force, and joint power between two artificial foots. This was similar to the results from previous studies regarding the energy-storing foot, where the walking velocity and gait symmetry have been improved. Nevertheless, the result of this study differed from the previous ones which reported that joint angle, joint power, and GRF increased as the gait speed increased except spatio-temporal parameters.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.2020-2022
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• 2000

The cross-linked polyethylene(herein after XLPE) insulated power cable emit the methane($CH_4$)gas in the course of chemical cross-linking process. The general stranded conductor easily discharge this methane gas through the gap of each stranded wires. But the special stranded conductor that filled with semi-conducting rubber compound to prevent water penetration which is applied to water proof type of cable(22.9kV CN/CV-W), disturb the methane gas emission. The pre-mold type cable joint shall be expanded gradually by emit of gas left in XLPE insulation. For example, sometimes the corona problem outbreak on a new power distribution line, resulted from the gap between the sleeve and semi-conductive layer of cable joint. If above mentioned problem especially happened on the way of operating. We have to shut down the line and try to discharge the methane gas in cable joint. In this point, we would like to explain the mechanism of methane gas & cable joint and our test result briefly. At last, we are pleased to introduce the solution for preventing reoccurrence of this problem.

• Journal of Korea Water Resources Association
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• v.40 no.2 s.175
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• pp.101-112
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• 2007

In this study, a methodology was developed to evaluate the effects produced in the event of joint-operation of dams from the viewpoint of water use. It was applied to evaluating the actual results of dam operation in the Han River basin. In order to evaluate the effects of real joint-operation in terms of water supply and flow conditions, the methodology used the satisfaction rate of water requirement and the stability of flow conditions at the evaluation site as indicator. In order to evaluate the effects of joint-operation in terms of power generation, the total power generation produced by dams was used as evaluation indicator. Actual operation results were evaluated by comparison of evaluation indicators relating to single dam operation by which the notified mont of water was supplied, as well as to optimization models. Results of actual joint-operation of the Han River basin, from 2001 to 2004, were compared yearly with results from single operation and optimization model; in terms of water supply, the satisfaction ratio of water requirement stood at $94.36{\sim}99.68%$ for single operation, $97.16{\sim}99.90%$ for actual joint-operation, and 100.0 % for optimization model for all four years. The stability of flow condition was evaluated by the coefficient of river regime and coefficient of flow conditions definitely, indicating that flow conditions were more stable in case of actual operation and optimization models than in case of single operation. The actual total power generation was compared with that generated by other operation rules, indicating that the optimization model increased the power generation by $-3.47{\sim}6.54%$ compared with the actual total power generation, and that the single operation decreased the power generation amount by $12.68{\sim}38.94%$ compared with the actual total power generation.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.410-412
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• 2001

초고압 CV 케이블용으로 다양한 형태의 접속함이 사용되고 있으나, 최근 케이블 시스템의 사용 전압이 초고압화됨에 따라 접속함 또한 고품질, 고신뢰성이 요구되고 있다. 따라서 공장에서 엄격한 품질 관리가 용이하고, 현장에서 쉽게 조립할 수 있는 프리몰드형 접속함(Premolded Joint: PMJ)의 사용이 급격하게 증대되고 있다. 본 논문에서는 국내에서 최초로 $110kV{\sim}170kV$ 전압급의 PMJ 접속함 개발에 관하여 소개 하였다. 전기적, 기계적 및 열적 설계의 개념을 간략하게 소개하였으며, 접속함의 초기 성능 및 장기 신뢰성을 검증하기 위한 시험 및 평가 결과를 소개하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.11
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• pp.5209-5228
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• 2016

Device-to-device (D2D) communication underlaying cellular networks can bring significate benefits for improving the performance of mobile services. However, it hinges on elaborate resource sharing scheme to coordinate interference between cellular users and D2D pairs. We formulate a joint mode selection, link allocation and power control optimization problem for D2D communication sharing uplink resources in a multi-user cellular network and consider the efficiency and the fairness simultaneously. Due to the non-convex difficulty, we propose a three-step scheme: firstly, we conduct mode selection for D2D pairs based on a minimum distance metric after an admission control and obtain some cellular candidates for them. And then, a cellular candidate will be paired to each D2D pair based on fairness. Finally, we use Lagrangian Algorithm to formulate a joint power control strategy for D2D pairs and their reused cellular users and a closed-form of solution is derived. Simulation results demonstrate that our proposed algorithms converge in a short time. Moreover, both the sum rate of D2D pairs and the energy efficiency of cellular users are improved.

• Journal of the Korean Applied Science and Technology
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• v.38 no.4
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• pp.1107-1116
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• 2021

The purpose of this study investigate the effects of 8 weeks plyometric training on power, dynamic balance and joint position sensory in Taekwoondo demmonstrators. Twenty healthy collegiate Taekwoondo demonstrators were randomly assigned to either an exercise group (Ex=10), and a control group (Con=10), Ex group completed the plyometric training in three times a week, 60 minute for 8 weeks. Testing before and after training include the Sargent jump, standing long jump, back muscle strength, Dynamic balance and joint position sensory. Sargent jump, standing long jump and back muscle strength were significantly development(p<.05). And dynamic balance were significantly exercise effect in posterolateral(p<.01) and posteromedial(p<.05). Not only but also, joint position sensroy were significantly exercise effect in left food 15°(p<.01) and 45°(p<.05). The results of the study showed that 8 weeks of plyometric training had a positive effect on the power, dynamic balance and joint position sensory in Taekwondo demonstrator.

• The Journal of Korean Physical Therapy
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• v.23 no.1
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• pp.13-19
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• 2011

Purpose:This study was designed to investigate difference in isokinetic muscle strength in the knee extensor muscle and characteristic differences in muscle strength between males and females through the ankle joint angles. Methods: Seventy-four subjects participated in this study. There were two groups: 36 males and 38 females. The mean age of the men was 24.58 years and women was 23.74 years. Subjects were seated on a CON-TREX LP (leg press) lean to back of chair, and there bodies were fixed by straps with the hip joint at an angle of $130^{\circ}$. After randomly fixing the ankle joint at $0^{\circ}$, $20^{\circ}$, and $40^{\circ}$ of plantar flexion (PF) in range of full extension of knee joint. We studied force max average, force max average/kg, power average, and total work through the angle of the ankle joint when the knee joint was extended from $90^{\circ}$ to $180^{\circ}$. Results: In the male group, all maximum measured value showed at the ankle joint $0^{\circ}$, all minimum measured value showed at $40^{\circ}$ PF (p<0.01). In the female group, all maximum measured value showed at the ankle joint $20^{\circ}$ PF, especially the power average increased significantly. All minimum measured value showed $40^{\circ}$ PF (p<0.01). Conclusion: There are differences between males and females in isokinetic muscle strength of the knee extensor through ankle joint angles in healthy adults. Males and Females have different characteristics of muscle strength through the ankle joint angles.

• Journal of the Korea Society of Computer and Information
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• v.21 no.10
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• pp.37-42
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• 2016

We investigate multi user joint rate scheduling and power allocation problem for a delay sensitive CDMA systems. First, we characterize the existing two user joint rate scheduling and power allocation. We then extend the problem to the case of the multi user systems. In general, there is no simple optimum solution for the multi user scheduling problem. To that end, we propose a sub optimum solution, termed 'virtual user approach'. We show the performance of the virtual user approach to verify the benefit of complexity.

• Korean Journal of Applied Biomechanics
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• v.15 no.2
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• pp.11-20
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• 2005

This study has a purpose on contributing to apprehend safe and right way to stop to the inline skate beginners and to the instructors who teaches line skating on the basis for the result of the kinematical analysis on Heel brake stop movement of the inline skate, focusing on the displacement on COG, angle displacement of ankle joint, angle displacement of knee joint, angle displacement of hip joint, using a 3D image method by DLT. To achieve this goal, we analysed the kinematical factor of the 3 well-trained inline skating instructors and obtained the following results. 1. During the movement of heel-brake stop, when strong power was given to a stable and balanced stop and the lower limbs, if the physical centroid is lowered the stability increases, and if it is placed high from the base surface, as the stability decreases compared to the case of low physical centroid, we should make a stop by placing a physical centroid in the base surface and lowering the hight of physical centroid. 2. To make a stable and balanced stop and to provide a strong power to the lower limbs, it is advisable to make a stop by decreasing an angle displacement of ankle joint during a "down" movement. In case of the left ankle joint, in all events and phases the dorsiflexion angle showed a decrease. Nevertheless, in the case of the right ankle joint, the dorsiflexion angle shows an increase after a slight decrease. The dorsiflexion angle displacement of ankle joint can be diminished because of the brake pad of the rear axis frame of the right side inline skate by raising a toe, but cannot be more decreased if certain degree of an angle is made by a brake pad touching a ground surface. To provide a power to a brake pad, it is recommended to place a power by lowering a posture making the dorsiflexion angle of the left ankle joint relatively smaller than that of the right ankle. 3. To make a stable and balanced stop and to add a power to a brake pad, the power must be given to the lower limbs in lowering the hight of physical centroid. For this, it is recommended to make a down movement by decreasing the flexion angle of a knee joint and it is necessary to make a down movement by a regular decrease of the angle displacement of knee joint rather than a swift down movement in every event and phase. 4. The right angle displacement of hip joint is made by lowering vertically the hight of physical centroid as leaning slightly forward. If too narrow angle displacement of hip joint is made by leaning forward too much, the balance is lost during the stop by placing the center in front. To make a stable and balance stop and to place a strong power to the lower limbs, it is recommendable to make a narrow angle by lower the hip joint angle. However, excessive leaning of the upper body to make the angle too narrow, can cause an instable stop and loss of physical centroid. After this study, it is considered to assist the kinematical understanding during the heel brake stop movement of the inline skate, and, to present basic data in learning a method of stable and balanced stop for the inline skating beginners or for the inline skate instructors in the present situation of the complete absence of the study in inline skating.