• Journal of the Society of Naval Architects of Korea
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• v.31 no.1
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• pp.102-110
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• 1994

The roll response of ships to the narrow band random exciting moment is investigated based on the multiple time scale technique. The results are compared with those calculated from statistical equivalent linearization method. The calculation results have shown that the results calculated from multiple time scale technique eve wider range of multiple values. Numerical simulations of rolling motion of ship are performed to confirm the results.

• ICROS
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• v.19 no.2
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• pp.34-38
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• 2013

자연계에서 빈번히 목격되는 군집 현상과 그 효용성의 고찰에 기인하여, 최근 다중 이동 로봇의 협업에 대한 연구가 활발히 수행되고 있다. 그 중, 본 논문에서는 다중 이동 로봇의 군집 제어 방법론들을 설명하고, 그와 관련된 최신 결과들도 소개한다. 특히 군집 제어 문제를 해결하기 위한 대표적인 방식인 행동 기반 접근법, 가상 구조 접근법, 선도-추종 접근법, 그래프 이론 기반 접근법 위주로 소개한다.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.4
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• pp.123-134
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• 1998

본 연구에서는 지반상태가 교량의 지진응답에 미치는 영향을 분석하기 위해 다양한 지반모델 상의 교량모델에 대한 지진해석을 수행하고 그 결과를 비교.분석하였다 이를 위해서 기존의 교량시방서에서 분류된 네가지의 서로다른 지반종류를 대상으로 보다 세분된 지반모델 상에 위치하는 대표적인 교량에 대한 지진해석을 수행함으러써 첫째로는 각 지반 종류 상호간의 지진응답 차이의 정도를 시방서 값과 비교.분석하였으며 둘째로는 동일 지반으로 분류되는 상이한 두 지반간의 응답차이의 정도를 확인하였다 해석을 위해서는 시방서에서 제시된 두가지 방법 즉 단일모드 스펙트럼해석법과 다중모드 스펙트럼해석법을 사용하였으며 이들 결과를 별도로 작성된 인공시간이력을 입력으로 하는 시간이력해석법을 사용한 결과와 비교.분석하였다 시간이력해석법에서는 진동수에 무관한 지반임피던스함수를 이용하는 시간영역해석법을 사용하였다 해석결과 시방서에서 제시한 단일모드 및 다중모드 스펙트럼해석방법은 일반적으로 안전측의 지반-구조물 상호작용 해석결과를 주는 것으로 확인되었다 그러나 유연성이 큰 지반 상의 구조물에대한 지진해석을 위한 해석모델 작성시에는 지반의 유연성이 반드시 고려되어야 하며 특히 낙교방지를 위한 변위는 지반의 유연성을 고려한 정밀해석법에 의한 계산이 필수적으로 요구됨을 확인하였다.

• Pediatric Infection and Vaccine
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• v.22 no.2
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• pp.97-105
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• 2015

Purpose: Serotyping pneumococcal isolates is important to monitor efficacy of pneumococcal vaccines. Because of difficulties of typing pnueumocci, a multiplex bead-based (multibead) serotyping assay was recently introduced. The aim of this study is to establish a new multibead serotyping assay and to apply this method to analyze clinical isolates of pneumococci in Korea. Methods: To establish the multibead serotyping assay, six key reagents were transferred from University of Alabama at Birmingham (UAB) to Ewha Center for Vaccine Evaluation and Study (ECVES): bead set coated with polysaccharide and monoclonal antibody pool were used in one multiplex inhibition-type immunoassay and 2 bead sets coated DNA probe and 2 primer pools were used in two multiplex PCR-based assays. After multibead serotyping assay was set up, 75 test samples of pneumococci were analyzed whether ECVES is able to identify serotype correctly. After confirming the performance, serotyping assay was applied to identify serotypes of 528 clinical isolates of pneumococci collected from 3 different hospitals. Results: After establishment of the multibead pneumococcal serotyping assay system at ECVES, 75 test samples were analyzed. There was no discrepancy of serotypes of 75 test samples between the results assigned at UAB and those at ECVES. The serotypes of 528 pneumococci isolated from patients or healthy subjects were determined in 94.3% of isolates (498/528). Conclusions: The multibead pneumococcal serotyping assay can be successfully established in Korea. With this method, surveillance of serotypes of pneumococci isolated from patients as well as healthy subjects could be studied.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.6
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• pp.11-18
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• 2007

Multiple linear cryptanalysis has been researched as a method building up the linear attack strength. We indicate that the lastest linear attack algorithm using multiple approximations, which was proposed by Biryukov et al. is hardly applicable to block ciphers with highly nonlinear key schedule, and propose a new multiple linear attack algorithm. Simulation of the new attack algorithm with a small block cipher shows that theory for the new multiple linear cryptanalysis works well in practice.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1C
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• pp.90-97
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• 2009

The advantages of the orthogonal frequency division multiplexing (OFDM) are high spectral efficiency, resiliency to RF interference, and lower multi-path distortion. To further utilize vast channel capacity of the multiuser OFDM, one has to find the efficient adaptive subchannel and bit allocation among users. In this paper, we propose an 0-1 integer programming model formulating the optimal subchannel and bit allocation problem of the multiuser OFDM. We employ a dual-decomposition method that provides a tight linear programming (LP) relaxation bound. Simulation results are provided to show the effectiveness of the 0-1 integer programming model. MATLAB simulation on a system employing M-ary quardarature amplitude modulation (MQAM) assuming a frequency-selective channel consisting of three independent Rayleigh multi-paths are carried with the optimal subchannel and bit allocation solution generated by 0-1 integer programming model.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.1
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• pp.35-40
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• 2015

The paper proposes a meta-learning approach for building multi-classifier systems in a GA-based inductive learning environment. In our meta-learning approach, a classifier consists of a general classifier and a meta-classifier. We obtain a meta-classifier from classification results of its general classifier by applying a learning algorithm to them. The role of the meta-classifier is to evaluate the classification result of its general classifier and decide whether to participate into a final decision-making process or not. The classification system draws a decision by combining classification results that are evaluated as correct ones by meta-classifiers. We present empirical results that evaluate the effect of our meta-learning approach on the performance of multi-classifier systems.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.284-288
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• 2005

본 연구에서는 낙동강수계 일별 운영 계획 수립을 위한 저수지군 최적 연계운영 모형(CoMOM, Coordinated Multiple Reservoir Operating Model)을 개발하였다. 이를 위하여 동적 네트워크 흐름 모형을 기반으로 한 다중목적 혼합 정수 목표계획 모형 (MOMIGP, Multiple Objective Mixed Integer Goal-Programming)을 수립하였다. 이 모형은 월말 목표 수위 및 운영 제약 등을 목표 계획법으로 구성하였으며, 일별 운영의 특성을 고려하여 하도추적의 효과를 반영하였고, 선형화된 발전함수를 이용하여 발전량을 최대화 하도록 한 후 정확한 발전량을 사후에 산정하였다. 이와 같이 수립된 수학 모형을 GUI를 비롯한 프로그램(CoMOM)으로 개발하여 사용자가 편리하게 수행 할 수 있도록 하였다. 이 프로그램은 의사결정자의 운영 목표와 의도를 효과적으로 반영할 수 있도록 대화형 목표 계획법을 구현하였으며, 상충되는 여러 목적에 대하여 가능한 파래토(Pareto) 최적해를 제시하고 의사결정자가 가장 선호하는 해를 선택하도록 대화형 다중목적 계획법 CBITP(Convex hull of individual maxima Based Interactive Tchebycheff Procedure)를 활용하여 구현하였다. 한편 객체지항적 프로그램 기법을 활용하여 수계 내의 노드(저수지, 수요지, 발전소 등)를 추가 하거나 삭제 할 수 있도록 하여, 다른 수계로의 확장이 용이하도록 개발하였다.

• Communications for Statistical Applications and Methods
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• v.17 no.6
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• pp.899-907
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• 2010

Several non-response imputation methods are suggested, however, mainly cross-sectional imputations are studied and applied to this analysis. A simple and common imputation method for panel data is the cross-wave regression imputation or carry-over imputation as a special case of cross-wave regression imputation. This study suggests a multiple imputation method combined time series analysis and cross-sectional multiple imputation method. We compare this method and the cross-wave regression imputation method using MSE, MAE, and Bias. The 2008 monthly labor survey data is used for this study.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.4
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• pp.45-52
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• 2000

We present a novel method for simple and efficient analysis of the rectangular MQW waveguide. Preferentially two-dimensional structure is transformed into one-dimensional structure by using the effective index method. Then, the characteristic matrix of the resultant planar MQW waveguide is analyzed by scanning angle method. The effective index, modal intensity, and optical confinement factor of rectangular MQW waveguide can be effectively obtained by this method. Our simulation results show excellent agreement with the accurate solutions based on the finite element method. We also introduce the approximation methods for the analysis of rectangular MQW waveguide and investigate their validity. By using perturbation approach, modal power loss of guided wave in rectangular MQW waveguide is newly investigated and compared with the conventional method using the approximation of planar MQW waveguide.