• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.24 no.6
• /
• pp.637-643
• /
• 2011

The bond-based peridynamic model is able to capture many of the essential characteristics of dynamic brittle fracture observed in experiments: crack branching, crack-path instability, asymmetries of crack paths, successive branching, secondary cracking at right angles from existing crack surfaces, etc. In this paper we investigate the influence of the stress waves on the crack branching angle and the velocity profile. We observe that crack branching in peridynamics evolves as the phenomenology proposed by the experimental evidence: when a crack reaches a critical stage(macroscopically identified by its stress intensity factor) it splits into two or more branches, each propagating with the same speed as the parent crack, but with a much reduced process zone.

• Proceedings of the Korean Information Science Society Conference
• /
• 2001.10c
• /
• pp.13-15
• /
• 2001

최근에 이르러 프로세서의 병렬성을 분석적 기법으로 예측하기 위한 연구가 활발해지면서 프로세서의 성능 예측 모델에 대한중요성이 대두되고 있다. 그러나 기존의 연구는 현재 광범위하게 사용되고 있는 다중 분기 예측법을 이용하는 프로세서에 대하여 분기 차수와 관계없는 재귀적 성능 모델을 제공해주지 않는다. 본 논문에서는 이것을 해결하기 위하여, 매 싸이클마다 명령어 종속 트리를 구성하고 종속인 명령어 간에 상대적인 병렬도 갓을 부여하여 성능 예측 모델 입력 데이타를 측정하였다. 그 곁과, 다중 분기 예측법을 사용하는 프로세서에서 정수형 프로그램에 대한 성능을 기존의 성능모델보다 작은 상대 오차로 예측할 수 있다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2000.05a
• /
• pp.156-159
• /
• 2000

A new analysis method of Tap-Off for CATV, DBS, CS systems was proposed and investigated by using 4-port and Lport equivalent circuits. As an analysis method the even$.$odd-mode theory for a symmetrical coupled-line directional coupler was introduced, and then it was applied to transformer type directional couple By comparing the results of simulation and measurement, the validity of the proposed analysis method was confirmed. Furthermore, the Tap-off has been broadened from 5 MHz to 4,000 MHz by adopting the propose theory.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 1998.11a
• /
• pp.578-582
• /
• 1998

CATV(Cable Television) 및 MATV(MasterTelevision) 시스템용 방향성결합기의 광대역 설계법을 제안한다. 결합선로형 방향성결합기의 이론을 도입하여 그 이론을 변성기형에 적용, 해석법을 확립하고, 제안한 해석법의 타당성을 입증하기 위하여 시뮬레이션결과 및 실험결과를 비교 검토한다. 그 결과 주파수특성이 반사계수 20dB, isolation 25dB를 만족하는 신호분기기를 5∼2150 MHz까지 광대역화 하였다.

• Communications for Statistical Applications and Methods
• /
• v.16 no.1
• /
• pp.41-50
• /
• 2009

Chain-linking is a method for aggregating volume measures which would improve the quality of estimates of economic growth over the present fixed base in Korea. There is a risk that choice of chain-linking techniques such annual overlap, one-quarter overlap or over-the-year overlap may create an artificial seasonality to the volume series. The empirical results on Korean GDP suggest that the use of the annual overlap is recommended. And conducting seasonal adjustment after chain-linking to produce the chain-linked seasonally adjusted GDP is more appropriated in Korea.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.420-424
• /
• 2003

Stacking sequence optimization needs discrete programming techniques because ply angles are limited to a fixed set of angles such as $0^{\circ},\;{\pm}45^{\circ},\;90^{\circ}$. Two typical methods are genetic algorithm and branch and bound method. The goal of this paper is to compare the methods in the light of their efficiency and performance in handling the constraints and finding the global optimum. For numerical examples, maximization of buckling load is used as objective and optimization results from each method are compared.

• Water for future
• /
• v.27 no.3
• /
• pp.135-143
• /
• 1994

This paper presents a model for the optimal design of dendritic water distribution systems using linear progranning technique. The optimization model was formulated and applied to a coastal region reclamation project site located in Hae-Ham, Jun-Nam province. The water distribution systems in the region had aleady been designed using a hydraulic simulator(BRANCH). The optimization model developed in this research utilized the data given in the report of the project. The comparison between the systems designed by the simulator and by the optimization model shows that the optimization model provides better results and can be utilized more efficiently in the design of dendritic water distribution systems.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.12 no.3
• /
• pp.346-351
• /
• 2001

A new analysis method was proposed, where the even . odd-mode theory for a symmetrical coupled-line directional coupler was applied to a transformer-type directional coupler. In addition, the tap-offs were analyzed by the proposed theory, which are widely used in CATV (Cable Television), DBS (Direct Broad- casting Satellite), CS (Communication Satellite) systems. By comparing the calculation results to the measured ones using the even . odd-mode reflection coefficients only, the validity of the proposed analysis method was confirmed. Then, the tap-off has been broadened from 5 MHz over 4,000 MHz by adopting the proposed theory.

• The Korean Journal of Applied Statistics
• /
• v.35 no.4
• /
• pp.517-525
• /
• 2022

In the era of big data, various data mining techniques have been proposed as major analysis methodologies. As complex and diverse data is mass-produced, data mining techniques have attracted attention as a method that forms the foundation of data science. In this paper, we focused on the decision tree, which is frequently used in practice and easy to understand as one of representative data mining methods. Specifically, we analyzed the effect of the splitting method of decision trees on the model performance. We compared the prediction power and structures of decision tree models with different split methods based on various simulated data. The results show that the linear combination split method can improve the prediction accuracy of decision trees in the case of data simulated from nonlinear models with complex structure.

• Proceedings of the Optical Society of Korea Conference
• /
• 2003.07a
• /
• pp.210-211
• /
• 2003

Y-형 분배기(Y-branch) 소자는 광 집적 회로(Optical Integrated Circuit)에 있어서 중요한 요소이다. 두 부분의 출력 분기 영역에 대하여 입사광을 균일하게 나눠주는 특징을 갖고 있으며 광 스위치, Mach-Zehnder 간섭기 등에 많이 응용되고 있다. 그러나 분기 부분에서 구조적인 영향으로 손실이 발생하며, 또한 미세한 분기 부분을 제작함에 있어서 공정상의 어려움으로 인해 손실이 발생하는 경우도 있다. (중략)