• Computational Structural Engineering
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• v.11 no.3
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• pp.229-239
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• 1998

복합재료는 강도-무게비가 다른 재료들에 비해 훨씬 크기 때문에 부재의 좌굴문제가 대단히 중요하게 취급되며, 본 논문에서는 축방향 압축력을 받는 복합재료로 된 쉘 부재의 좌굴해석이 수행된다. 이 재료는 일반적으로 이방성 재료 특성을 나타내 보이나, 섬유들이 한 방향으로만 배치되어 있는 경우 섬유방향에 연직한 평면에서의 강도나 탄성계수들은 모두 일정한 횡 등방성 재료성질을 가진 것으로 간주할 수 있다. 9 절점 degenerate 쉘 유한요소를 사용한 선형안정해석, LUSAS 범용 프로그램을 이용한 구조해석, 그리고 고전적 쉘 좌굴방정식에 의한 해석들을 수행하였으며, 그 결과들을 서로 비교, 분석하였다. 고려된 등방성 재료나 횡 등방성 재료의 경우 모두, degenerate 유한요소해석으로 계산한 임계하중들은 고전적 이론해에 의한 결과들 보다 낮았으며, LUSAS 결과들과는 거의 같았다. 이는 degenerate 유한요소에 의한 선형안정해석 결과들이 안전측에 듬을 의미하며, 복합재료로 된 쉘 구조물의 좌굴해석에 degenerate 유한요소를 효율적으로 적용할 수 있음을 의미한다.

• Fire Science and Engineering
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• v.22 no.3
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• pp.272-277
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• 2008

This study is performed for propose that exactly equivalent length of TBP in the applied at water-based fire protection system. For predict the measuring position of equivalent length, we determined the measuring position using the FVM about pressure drop of TBP. For the reckon of the exact about measured value we compared with the result of FVM and we knew the similar value each other. Using the results we proposed the friction loss measuring position that inlet of main dirction is 20 times of appellation diameter in main pipe, outlet of main dirction is 10 times of appellation diameter in main pipe and outlet of branched direction is 20 times of appellation diameter.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.316-319
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• 2002

본 논문에서는 먼저 영남지역의 장기적인 전력부족을 해결하기 위하여 일본의 규슈지역과 남한의 부산지역을 KVDC로 계통연계를 위한 시나리오 및 전력 조류의 분포도를 분석하는 것을 목적으로 한다. 특히 경인지역과 영남지역은 부하의 중심지라고 할 수 있으며, 영남지역은 현재의 경우에도 발전량보다 부하량이 많은 것으로 나타나 있다. 이러한 추세는 향후 계속적인 전력수요의 증가로 인해 더욱 문제가 될 것이며, 이런 증가하는 발전력의 부족을 해결할 만한 마땅한 대책이 없으리라 여겨진다. 본 논문의 시나리오에서는 영남지역에 전력을 공급할 목적으로 되어있기 때문에 일본측을 컨버터로 한국측을 인버터로 하여 일본에서 한반도 방향으로 전력을 흘려보내도록 하였다. 양국의 HVDC 전력 계통연계는 가상으로 시나리오를 작성한 후, PSS/E Tool을 사용하여 조류 계산을 시행하여 전력 분포도를 살펴보았다.

• 정보화사회
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• s.16
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• pp.17-25
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• 1989

통신시장 개방에 대한 한국측의 성의있는 자세에도 불구하고 미행정부는 우리가 받아들일 수 없는 시장개방협상안을 제시하며 지난 2월 23일 한국을 EC와 함께 통신부문 우선협상대상국으로 지정했다. 이러한 시기에 본협회를 중심으로 업계가 미국의 개방압력에 능동적으로 대처하고 자립기반 구축을 위한 총체적 의견을 결집할 필요성이 대두되었다. 따라서 협상에 앞서 가진 통신시장 개방대책 민관협의회(89. 1. 28)와 미국측의 요구, 그리고 회담시 제출한 그들의 개정안을 차례로 검토해보고 앞으로의 나아갈 방향을 가늠해 보고자 본란을 기획하였다. 이러한 취지에 부응하여 본협회는 이달 중순경에 "통신시장 개방에 관한 세미나"와 "전기통신 환경개선을 위한 워크숍"을 개최할 방침이다. 참고로 통신시장 개방 대책 민관협의회의 협회장 인사와 체신부차관 치사는 원고없이 행한 것임을 밝혀둔다.

• Journal of Korea Water Resources Association
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• v.54 no.11
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• pp.933-942
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• 2021

The surface image velocimetry was developed to measure river flow velocity safely and effectively in flood season. There are a couple of methods in the surface image velocimetry. Among them the spatio-temporal image velocimetry is in the spotlight, since it can estimate mean velocity for a period of time. For the spatio-temporal image velocimetry analyzes a series of images all at once, it can reduce analyzing time so much. It, however, has a little drawback to find out the main flow direction. If the direction of spatio-temporal image does not coincide to the main flow direction, it may cause singnificant error in velocity. The present study aims to propose a new method to find out the main flow direction by using a fast Fourier transform(FFT) to a spatio-temporal (image) volume, which were constructed by accumulating the river surface images along the time direction. The method consists of two steps; the first step for finding main flow direction in space image and the second step for calculating the velocity magnitude in main flow direction in spatio-temporal image. In the first step a time-accumulated image was made from the spatio-temporal volume along the time direction. We analyzed this time-accumulated image by using FFT and figured out the main flow direction from the transformed image. Then a spatio-temporal image in main flow direction was extracted from the spatio-temporal volume. Once again, the spatio-temporal image was analyzed by FFT and velocity magnitudes were calculated from the transformed image. The proposed method was applied to a series of artificial images for error analysis. It was shown that the proposed method could analyze two-dimensional flow field with fairly good accuracy.

• Journal of Digital Convergence
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• v.15 no.4
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• pp.529-536
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• 2017

The purpose of this study is to examine the immediate effects of spiral taping applied to an affected leg on gait ability in stroke patients. Forty two stroke patients were divided into a spiral taping group (n=21) and a quadriceps femoris group (n=21), and each taping method was applied. Spatiotemporal Gait Parameters (Cadence, speed, gait cycle duration, stance phase duration, double support duration) were measured using the 10-meter walk test, the dynamic gait index (DGI) and an accelerometer for both groups. Both groups showed a significant increase in a 10-minute walk, the DGI, cadence, speed before and after the intervention, whereas no significant difference was detected in stance phase duration, gait cycle duration and double support duration on the affected side in all groups. All groups revealed no significant difference in variation. It has been found that the two taping methods augment gait ability in patients with stroke. This study suggests that spiral taping can be an easily applicable method at home.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1B
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• pp.11-20
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• 2008

The spillway type of small and midsize dams in Korea is almost overflow weir. To examine flood control capacity of overflow spillway, FLOW-3D was applied to Daesuho dam and analysis was focused on the discharge of dam spillway by changing weir shape. Overflow phases and discharges of linear labyrinth weir and curved labyrinth weir were compared with those of existing linear ogee weir. Hydraulic model experiment was performed to verify numerical result. Verification results showed that overflow behaviors and flow characteristics in the side channel by hydraulic model experiment and numerical simulation are well matched, and water surface elevation at side wall coincides with each other. When the reservoir elevation was increased up to design flood level, in case of the linear ogee weir the flow over the crest ran through smoothly in the side channel, whereas in cases of linear labyrinth weir and curved labyrinth weirs, the flow discharge was increased by 40 cms, and the flow over the weir crest, rotating counter-clockwise, was submerged in the side channel. The results of the water level-discharge curve revealed that labyrinth weir can increase discharge by 71% compared to the discharge of linear ogee weir at low reservoir elevation since it can have longer effective length. But as water surface elevation rises, the slope of water level-discharge curve of labyrinth weir becomes milder by submergence and nappe interference in the side channel.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.12
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• pp.209-216
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• 2000

The lateral behavior of the moving web is critical to the quality of the web products. The alignment of the rollers carrying the web is found to be one of important factors to the lateral behavior of the moving web. But, the study on the effect of the tilting roller in the direction of the normal to the moving web on the lateral behavior has not been reported in the literature yet. For example, the contact roller often contacts the winding roll in a tilted fashion and causes the lateral motion of the winding web, which induces the offset on the wound roll. The lateral dynamics of the moving web induced by a tilted roller in normal direction of a web is investigated in this paper. The two-dimensional dynamic model developed by Shelton is extended to investigate the effect of a titled roller in a normal direction of the moving web on the lateral motion of the moving web. New boundary conditions are developed to solve the extended model. Computer simulation study proved that the model developed can be used to predict the lateral motion of the moving web ？ to a tilted roller in normal direction of the moving web. The lateral deflection is increased exponentially a the tilting angle is increased. As the length of web span is increased, the amount of lateral deflection was increased almost linearly for the same tilting angle. The lateral dynamics turned out to be almost independent to the operating tension. The model developed can be used to solve the offset problem of the staggered winding and also to design a new web guiding mechanism.

• Journal of Biomedical Engineering Research
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• v.25 no.4
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• pp.289-293
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• 2004

In the present study, knee varus torque and mediolateral accelerations were measured using the three-dimensional motion analysis system and a linear accelerometry in odor to determine the effect of heel wedges during walking. Wedges were inclined with 10$^{\circ}$ and 15$^{\circ}$ in medial and lateral directions respectively Both knee varus torques and mediolateral accelerations showed two distinct positive peaks in loading response and preswing. Medial wedges resulted in significantly increased both knee varus torque and lateral acceleration in loading response, compared with the barefoot walking(p<0.05). On the other hand, lateral wedges decreased them in loading response(p<0.05). This became more significant for more inclined wedges. However, no significant correlations were found between knee varus torque and lateral acceleration according to the angle of heel wedges in preswing. From this study, it was found that a lateral wedge would be helpful to treat osteoarthritis, decreasing knee varus torque in loading response. In addition, lateral acceleration of the knee joint might be an alternative to determine the effect of wedges and the alignment of the knee joint during walking, instead of measuring knee torque by the three-dimensional motion analysis.

• Journal of the Korean Society of Propulsion Engineers
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• v.2 no.3
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• pp.54-61
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• 1998

A numerical simulation is attempted for the regenerative cooling heat transfer processes of the liquid propellant rocket engine. The heat transfer from the combustion gases to the thrust chamber wall is called gas side heat transfer. This heat is conducted radially to the coolant through the carbon deposit and metallic wall of thrust chamber Finally, this heat is convected away by the coolant flowing along the passages in the thrust chamber. The equivalence of these three heat fluxes of the above processes is utilized to determine the coolant side wall temperature, gas side wall temperature and the heat flux. When the number and shape(width, height) of coolant passages, the shape(size) of thrust chamber, oxidant and fuel properties, coolant properties, oxidant/fuel mixture ratio, coolant inlet temperature, the thickness of carbon deposit formed along the thrust chamber wall during combustion are given, reasonable radial direction temperature distributions and heat fluxes along the thrust chamber axis are obtained.