• Journal of the Korean Geotechnical Society
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• v.19 no.5
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• pp.7-14
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• 2003

In the back analysis of braced excavation based on displacement measurements, the accumulated errors of abnormal displacement caused by unexpected loads are usually observed. To minimize such errors, in this study, displacement increment was used fur back analysis rather than displacement for the conventional method. That is, the increment of sequential displacement is used as the objective function and the back analysis program is developed by taking advantage of sequential linear programming method by modified method of feasible directions. Based on small scale model test, the analysis of proposed method is verified.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.2B
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• pp.137-144
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• 2002

In this paper, we optimize the base station placement and transmission power using genetic approach. A new representation describing base station placement and transmit power with real number is proposed, and new genetic operators are introduced. This new representation can describe the locations, powers, and number of base stations, Considering coverage, power and economy efficiency, we also suggest a weighted objective function. Our algorithm is applied to an obvious optimization problem, and then it is verified. Moreover, our approach is tried in inhomogeneous traffic distribution. Simulation result proves that the algorithm enables to fad near optimal solution according to the weighted objective function.

• Proceeding of EDISON Challenge
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• 2012.04a
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• pp.41-44
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• 2012

본 연구에서는 풍력발전에 충분한 가능성을 가진 산악 지형을 모델링하여 유동의 흐름을 분석하였다. 실제 지형(설악산, 점봉산)에 대한 1/500 축소모형을 Gaussian 함수로 표현하였다. EDISON_CFD을 사용하여 산악지형의 난류유동을 해석하였으며, 해석결과의 신뢰성 확인을 위해 격자분해능에 따른 속도분포를 비교하였다. 산악지형에 따른 유동현상을 속도분포 및 유선함수 등에 의해 분석하였다. 또한 풍력터빈 설치 높이 기준에 의거하여 지형변화에 따른 주 유동방향 속도분포를 살펴보았다. 지형효과에 따른 유동해석결과를 기반으로 풍력 발전 가능 영역이 논의되었다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.633-636
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• 2005

최근의 전자기기는 소형, 경량화가 가속화되고 있고, 특히 휴대용 기기에서의 MP3, MOD, VOD, DMB, 3D 게임, 등 다양한 멀티미디어 콘텐츠에 대한 일반인의 접근성이 확대됨에 따라 휴대용 기기에서의 입체음향 효과에 대한 사용자의 관심이 고조되고 있다. 하지만, 휴대용 기기에서의 입체음향 효과 구현은 PC 환경에서의 구현과는 다르게, 적은 CPU 점유율, 작은 메모리 사용, 등 열악한 재생환경에서의 구현이 필요해, 기대만큼의 성능을 내기가 쉽지 않다. 이러한 제약된 환경에서 만족스러운 입체음향 효과의 구현을 위해서는 기기별 H/W 특성을 감안한 알고리듬 최적화가 필수이다. 본 논문에서는 휴대용 기기 환경에 최적화된 입체음향 기술과 동향, 국내에서 상용화된 XEN$^{TM}$ 솔루션에 대해 살펴봄으로서 향후 휴대용 기기를 위한 입체음향 기술개발 방향을 제시하고자 한다.

• Composites Research
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• v.13 no.1
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• pp.61-68
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• 2000

A new approach is presented for the analysis of transient waves propagating in anisotropic composite laminates. The wavelet transform (WT) using the Gabor wavelet is applied to the time-frequency analysis of dispersive flexural waves. It is shown that the peaks of the magnitude of WT in time-frequency domain is related to the arrival times of group velocity. Experiments are performed using a lead break as the simulated fracture source on the surface of quasi-isotropic and unidirectional laminates. For predictions of the dispersion of the flexural mode, Mindlin plate theory is shown to give good agreement with the experimental results. Based on the frequency-dependent arrival times and angular dependence of group velocities of flexural waves, the problem of source location in anisotropic laminates is considered and the results are given.

• Journal of the Korean Society for Marine Environment & Energy
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• v.5 no.1
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• pp.11-18
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• 2002

Directional breaking waves are generated by the component wave focusing both in direction and frequency based on constant wave steepness and constant wave amplitude spectrum models. The generated breaking waves are classified in the incipient, single and multi breaking waves. The characteristics of directional breaking waves are investigated in terms of surface profile parameters of wave crest steepness and asymmetry. The evolution of breaking wave characteristics is analyzed in a view of focusing efficiency. It shows that the front steepness and vertical asymmetry play an important role in breaking process, while the crest rear steepness and horizontal asymmetry are nearly constant during the process. The superposition of directional components greatly enhances the focusing efficiency and it suggests that characteristics of directional breaking waves may significantly different from uni-directional ones.

• Composites Research
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• v.20 no.5
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• pp.13-19
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• 2007

Fiber-reinforced thermoplastic composites not only approach almost near to the strength of thermosetting composite but also has excellent productivity, recycling property, and impact resistance, which are pointed as weaknesses of thermosetting composites. The study for strength calculation of one direction fiber-reinforced thermoplastic composites and the study measuring precisely fiber orientation distribution were presented. Need the systematic study for the data base that can predict mechanical properties of composite material and fiber orientation distribution by the fiber content ratio was not constructed. Therefore, this study was investigated what affect the fiber content ratio and fiber orientation distribution have on the strength of composites. Fiber-reinforced thermoplastic composites by changing fiber orientation distribution and the fiber content ratio were made. Tensile strength ratio of $0^{\circ}$ direction of fiber-reinforced composites increased being proportional the fiber content and fiber orientation function as change from isotropy(J=0) to anisotropy(J=1). But, tensile strength ratio of $90^{\circ}$ direction by separation of fiber filament decreased when tensile load is imposed fur width direction of reinforcement fiber length direction.

• The Journal of the Korea Contents Association
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• v.22 no.3
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• pp.513-528
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• 2022

The purpose of this study is to analyze Korean game-related issues and policies to increase the effectiveness of related policies in the future and to increase the consistency of social norms of the policies. this study analyzes related issues by analyzing changes in Korean newspaper articles using spline function and text mining methods, and analyzes the contents of newspaper articles at the time of amplification of issues to present major issues and development directions. As a result of the analysis, game-related issues appeared in various topic, and there are not only support from the government and local governments but also coexisted with game-related regulations (taxation, gambling regulations, game addiction disease, and prevention of fee expansion). Despite regulations, the government presents preemptive responses to problems caused by the application of metabuses and NFTs to games, fostering game-related experts, start-up support, and supporting manpower departure as policy implications.

• Proceedings of the Acoustical Society of Korea Conference
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• 1992.06a
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• pp.96-99
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• 1992

섬유강화 복합재료의 동탄성계수와 감쇠특성을 규명하기 위하여 랜덤하게 분포된 무한 실린더 형상의 산란체를 가진 매질내에서, 조화운동을 하는 압축 및 SV탄성파의 전파에 관하여 연구하였다. 단일 실린더에 대한 산란계수로부터 La의 준결정근사법을 이용하여 다중산란에 관한 이론을 유도하였고, 매질내에서의 파동전파 특성을 내포하는 분산관계식을 얻었다. 수치적으로 분산관계식의 해를 구함으로써 2 차원 유효체적강성, 횡방향 유효전단강성 및 각 파동의 전파에 따른 감쇠계수를 주파수와 체적비의 함수로서 제시하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2000.04a
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• pp.668-670
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• 2000

공개키 암호 알고리즘의 암호화 함수는 한 방향으로의 계산은 매우 쉬우나, 역 계산은 매우 어렵다는 일방향성과 특별한 정보를 가지면 역 계산이 가능하다는 트랩도어(trapdoor)성질이 있어야 하기 때문에 NP 문제나 계산상 풀기 어려운 수학 문제에 기반하여 연구되고 있다. 본 논문에서는 정수 계획법이라는 NP-완전 문제를 이용한 새로운 공개키 암호 알고리즘을 제안한다. 이 알고리즘의 키 생성 방식은 기존의 배낭꾸리기 암호 TTMXPA의 방식과 유사히지만 기존 시스템의 공격 대상이었던 비밀키가 가지는 취약성을 보완하였다.