• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.424-429
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• 2005

In this paper, the response characteristics of one to one resonance on the rectangular cantilever beam in which basic harmonic excitations are applied by nonlinear coupled differential integral equations are studied. This equations have 3-dimensional non-linearity of nonlinear inertia and nonlinear curvature. Galerkin and multi scale methods are used for theoretical approach to one to one internal resonance. Nonlinear response characteristics of 1st, 2nd, 3rd modes are measured from the experiment for basic harmonic excitation. From the experimental result, geometrical terms of nonlinearity display light spring effect and these terms play an important role in the response characteristics of low frequency modes. Dynamic behaviors in the out of plane are also studied.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.4
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• pp.339-345
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• 1992

Estimates of maximum amplitudes of conductor galloping are needed in order to determine appropriate phase-to-phase clearances on the overhead lines. One approach to obtaining these estimates is through the use of mathematical models of conductor galloping. Unfortunately, the models that consider both vertical conductor motion (Den Hartog type) and torsional conductor motion are often too complex for practical use. However, the estimates of maximum amplitude obtained from galloping models that assume only vertical (Den Hartog type) conductor motion tend to be too conservative. This paper presents the DF method to obtain the estimates of the amplitude and the frequency of galloping limit cycle, along with the wind pressure at which they occur, from a nonlinear dynamic model that considers both Den Hartog type and torsional conductor motion. From these results, the useful data for the line design guide and further insight into the mechanism of the conductor galloping are obtained.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.7 s.100
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• pp.851-858
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• 2005

The response characteristics of one to one resonance on the quadrangle cantilever beam in which basic harmonic excitations are applied by nonlinear coupled differential-integral equations are studied. This equations have 3-dimensional non-linearity of nonlinear inertia and nonlinear curvature. Galerkin and multi scale methods are used for theoretical approach to one-to-one internal resonance. Nonlinear response characteristics of 1st, 2nd, 3rd modes are measured from the experiment for basic harmonic excitation. From the experimental result, geometrical terms of non-linearity display light spring effect and these terms play an important role in the response characteristics of low frequency modes. Nonlinear nitration in the out of plane are also studied.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.331-332
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• 2008

최근 엘리노 현상과 기상이변(태풍 및 폭설)으로 갤로핑 및 전선도약(Sleet jump) 등에 따른 송전선로 상간단락 고장의 우려가 날로 증가하고 있다. 특히 345kV급 간선계통의 상간단락 고장은 순간전압 강화 등 전기품질 저하로 이어질 수 있다. 이에 본 논문에서는 345kV 2도체용 폴리머 상간스페이서를 개발하여 상간단락고장에 대한 근본적인 예방책을 제시하였다. 폴리머용 345kV 절연 설계, 고강도 FRP ROD 설계 및 턴버클을 이용한 미세조정 장치 적용, 코로나 방지를 위한 코로나 링 채용 등을 통하여 최적의 345kV 2도체용 상간스페이서를 고안하였다. 또한 상간스페이서 소재의 성능 평가 및 해석을 위하여 Maxwell 2D Field Simulator를 이용하여 모델링하였으며 갓 형상에 따른 전계분포 해석과 FRP와 고무 계면에서의 전계분포 해석도 수행하였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.836-841
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• 2002

The nonlinear vibration of moving viscoelastic belts excited by the eccentricity of pulleys is investigated through experimental and analytical methods. Laboratory measurements demonstrate the nonlinearities in the responses of the belt, particularly in the resonance region and with the variation of tension. The measurements of the belt motion were made using a noncontact laser sensor Jump and hysteresis phenomenon are observed experimentally and are studied with a model which considers the nonlinear relation of belt stretch. An ordinary differential equation is derived as a working form of the belt equation of motion. Numerical results show good agreements with the experimental observations, which demonstrates the nonlinearity of viscoelastic moving belts

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.1
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• pp.48-57
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• 2003

This study presents nonlinear vibration of a cantilever beam subjected to electromagnetic forces. The dynamic responses of the beam show various nonlinear phenomena with the variation of the system parameters, such as the jump phenomenon, multiple solutions, and the movement of the natural frequency. In this study the nonlinear stiffness due to electromagnetic forces which depends on air gap size is measured experimentally, and the system is modeled by a single degree of freedom nonlinear dynamic system and solutions are solved numerically. The numerical results show good agreements with the experimental results, which demonstrate the nonlinearity of electromagnetic force. Finally the occurrences of the jump phenomenon and the first, second and fourth harmonic components are confirmed in using the method of multiple scales.

• Nuclear Engineering and Technology
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• v.9 no.1
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• pp.7-13
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• 1977

This paper attempted to investigate the temperature characteristics and electrical conduction when low density polyethylene is irradiated. It was found that the log $\rho$ versus 1/T in irradiated polyethylene specimen resulted in different characteristics when it was heated upto above the melting point from when it was heated at the beginning stage. It was also found that the relation between the temperature and volume resistivity represented jumping phenomenon and that crystallization by thermal change was closely related to the fusion of crystalline region.

• Proceedings of the Korea Port Economic Association Conference
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• 2003.07a
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• pp.359-367
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• 2003

21세기 해양시대를 맞이하여 선진 해양수산 경남으로의 발전 도약을 위하여 2002년부터 2006 년까지 5개년에 걸쳐 지역특성을 살린 자율적이고 미래지향적인 해양수산업 및 삶의 질이 향상되는 해양수산종합발전계획을 수립하였다. 해양수산업의 현 실태는 대외적으로는 신 해양질서의 재편, 대내적으로는 해양환경오염 등으로 어업여건이 악화되고 있으며, 또한 체계적인 어업관리 미비로 인하여 잡는어업 관리의 문제점이 노출되었다. 양식어장 관리부실 및 수산물 수입 급증으로 양식기반이 위축되고, 소득기반 및 정주환경 열악으로 탈어촌ㆍ노령화 현상이 가속화되고 있는 실정이다. 이와 같은 문제점을 극복하기 위해 연근해 어업의 구조조정 및 어업자원 관리를 통해 연근해어업의 경쟁력을 강화시키고, 기르는 어업의 육성과 연안어장 목장화 및 쾌적하고 생명력 넘치는 해양환경 조성으로 수산물 생산량을 향상시키는 수산업에 대한 종합발전계획을 수립하였다. 또한, 수산물 수출촉진과 유통혁신 및 가공산업 현대화를 통해 수산물 가공업의 영세성을 탈피하여 풍요롭고 활력이 넘치는 어촌개발, 해양레져타운 건설 및 선진 어업인을 육성하기 위한 해양산업발전계획도 수립하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.1
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• pp.110-121
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• 2016

Link-16 is a representative TDL operated by US air force and NATO and supports structure of Multi-net. Under Multi-net, military operation can be conducted effectively since terminal nodes in Link-16 hop over total frequency band simultaneously. As air traffic is rapidly increasing, new aeronautical system is introduced or existing system should be expanded to accommodate increasing air traffic and frequency band assigned for operating this system is scarce. It is scheduled to implement frequency remapping to solve frequency scarcity. With limited frequency band for operating Link-16, as frequency remapping is implemented, degradation of Multi-net performance can happen since multiple access interference in Link-16 is increasing so it is difficult to conduct multiple military operations. Thus, Group-based frequency hopping scheme is proposed to solve this problem. We verified the performance of the proposed scheme is improved.

• The Journal of the Korea Contents Association
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• v.18 no.10
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• pp.348-360
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• 2018

Purpose : The purpose of this study was to explore the meaning and essence of experience of family members as care givers of patient with head and neck cancer. Methods : This study was based on the colaizzi's phenomenological method, which describes the experiences about the family care givers. We had in-depth interview with family of five head and neck cancer patients. Results : Data was classified by 24 themes, 9 theme clusters and 4 categories. The categories are as follows: 'Shocking and actuality like a deadly maze', 'Cut off from the world by changes in family's physical image', 'Exhaustion of family', 'Take-off for mature care'. Conclusion : The results of the study provide useful information in understanding care givers' experience of patient with head and neck cancer and establishing effective strategies to support these care givers.