• 디지털콘텐츠학회 논문지
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• 제14권1호
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• pp.65-72
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• 2013

기상, 바이오, 천문학, 암호학 등 다양한 분야의 대규모 작업을 처리하기 위하여 다수의 계산 자원을 동시에 사용하기 위한 병렬 컴퓨팅 기법들이 제안되어져 왔다. 병렬 컴퓨팅은 여러 프로세서에게 작업을 분담시켜 동시에 계산을 수행하게 함으로써 프로그램의 실행시간을 단축시킬 수 있을 뿐만 아니라 해결할 수 있는 문제의 규모를 확장 시킬 수 있다. 본 논문에서는 실제 암호 알고리즘 분석하기 위하여 병렬 처리 방식을 적용하여 그 효율성을 분석하였다. 암호 알고리즘의 실질적인 안전성 요소인 키의 길이는 전수조사 계산량에 의존한다. 이에 병렬 처리 환경에서 DES 키 탐색 암호 알고리즘의 키 전수조사 작업을 수행하기 위한 세부적인 절차에 대해서 논하였고, 클러스터링 장비에 적용하여 시뮬레이션 수행하였다. 그 결과 컴퓨터의 양에 따라서 계산량의 추이를 실증적으로 예측함으로써 암호 알고리즘의 안전성 강도를 측정할 수 있다.

• Journal of the Korean Physical Society
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• 제73권12호
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• pp.1808-1813
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• 2018

I develop a transfer matrix algorithm for computing the geometric quantities of a square lattice polymer with nearest-neighbor interactions. The radius of gyration, the end-to-end distance, and the monomer-to-end distance were computed as functions of the temperature. The computation time scales as ${\lesssim}1.8^N$ with a chain length N, in contrast to the explicit enumeration where the scaling is ${\sim}2.7^N$. Various techniques for reducing memory requirements are implemented.

• 대한산업공학회지
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• 제1권2호
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• pp.73-81
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• 1975

In an earlier paper ('Scheduling Jobs on a Number of Identical Machines' by Elmaghraby and Park, March 1974, AIIE Transactions) a branch-and-bound algorithm was developed for the sequencing problem when all jobs are available to process at time zero and are independet (i.e., there are not a priori precedence relationships among jobs.). However, the amount of computation required by the algorithm was not considered to be short if more than 50 jobs were processed. As an effort to improve the algorithm, the present paper modifies the implicit enumeration procedure in the algorithm so that moderately large problems can be treated with what appears to be a short computational time. Mainly this paper is concerned with improving the lower bound in the implicit enumeration procedure. The computational experiences with this new branch-and-bound algorithm are given.

• Journal of Power Electronics
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• 제18권5호
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• pp.1369-1379
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• 2018

In this paper, a model predictive torque control (MPTC) without the use of a weighting factor for surface mounted permanent-magnet synchronous machine (SPMSM) drive systems is presented. Firstly, the desired voltage vector is predicted in real time according to the principles of deadbeat torque and flux control. Then the sector of this desired voltage vector is determined. The complete enumeration for testing all of the feasible voltage vectors is avoided by testing only the candidate vectors contained in the sector. This means that only two voltage vectors in the sector need to be tested for selecting the optimal voltage vector in each control period. Thus, the calculation time can be reduced when compared with the conventional enumeration method. On the other hand, a novel cost function that only includes the dq-axis voltage errors between the desired voltage and candidate voltage is designed to eliminate the weighting factor used in the conventional MPTC. Thus, the control complexity caused by the tuning of the weighting factor is effectively decreased when compared with the conventional MPTC. Simulation and experimental investigation have been carried out to verify the proposed method.

• Journal of Information Processing Systems
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• 제17권2호
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• pp.271-283
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• 2021

When generating layout schemes, both the material usage and practicality of the cutting process should be considered. This paper presents a two-section algorithm for generating guillotine-cutting schemes of rectangular blanks. It simplifies the cutting process by allowing only one size of blanks to appear in any rectangular block. The algorithm uses an implicit enumeration and a linear programming optimal cutting scheme to maximize the material usage. The algorithm was tested on some benchmark problems in the literature, and compared with the three types of layout scheme algorithm. The experimental results show that the algorithm is effective both in computation time and in material usage.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• 제28권3호
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• pp.174-182
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• 2017

Objectives: This study was conducted in order to develop a computerized test to measure the level of mathematic achievement and related cognitive functions in children and adolescents in South Korea. Methods: The computerized Comprehensive Learning Test-Mathematic (CLT-M) consists of the whole number computation test, enumeration of dot group test, number line estimation test, numeral comparing test (magnitude/distance), rapid automatized naming test, digit span test, and working memory test. To obtain the necessary data and to investigate the reliability and validity of this test, 399 children and adolescents from kindergarten to middle school were recruited. Results: The internal consistency reliability of the CLT-M was high (Cronbach's alpha=0.76). Four factors explained 66.4% of the cumulative variances. In addition, the data for all of the CLT-M subtests were obtained. Conclusion: The computerized CLT-M can be used as a reliable and valid tool to evaluate the level of mathematical achievement and associated cognitive functions in Korean children and adolescents. This test can also be helpful to detect mathematical learning disabilities, including specific learning disorder with impairment in mathematics, in Korea.

• 한국가스학회지
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• 제21권2호
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• pp.32-40
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• 2017

SIS는 공정안전시스템 분야에서 폭넓게 활용될 수 있는 계장안전시스템이다. SIS는 유해화학물질 누출 사고로부터 인간, 물질적 자산 그리고 환경에 미치는 피해를 줄이기 위해 필수적이다. 현재 전기, 전자 그리고 프로그래밍 가능한 전자 (E / E/ PE) 장치가 기계, 공압 및 유압 시스템과 상호 작용하는 통합 안전 시스템은 IEC 61508과 같은 국제 안전 표준을 따르도록 되어있다. IEC 61508은 안전 수명주기의 모든 사항을 규정한다. SIS 지원 도구 없이 안전 수명주기에 따라 IEC 61508의 요구 사항을 충족시키는 것은 복잡한 일이다. 본 연구에서는, 사용자가 보다 쉽게 안전 수명주기의 설계 단계를 구현할 수 있도록 도움을 줄 수 있는 On-Line SIS 지원 도구를 제시하였다. On-Line SIS 지원 도구는 데이터 읽기 및 수정 시스템과 통합될 수 있는 안드로이드 응용 프로그램의 형태로 되어있다. 이 도구는 안전 수명주기의 설계 단계에서 소요되는 계산 시간을 줄이고 계산 과정에서 발생할 수 있는 오류를 줄인다. 또한 On-Line SIS 지원 도구는 비용 요소에 근거한 최적화 접근법을 제시할 수 있으며, multi-objective GA를 사용하여 최적의 솔루션 조합을 찾을 수 있도록 하였다.