• Nuclear Engineering and Technology
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• 제11권3호
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• pp.219-229
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• 1979

The current status of the computational methods and computer codes for the analysis of reactor kinetics is reviewed. Computational methods which have been developed for space-dependent transient analyses are presented and recent progress in the development of methods is discussed.

• 한국IT서비스학회지
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• 제13권4호
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• pp.275-287
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• 2014

Recently, the volume of unstructured text data generated by various social media has been increasing rapidly; consequently, the use of text mining to support decision-making has also been growing. In particular, academia and industry are paying significant attention to topic analysis in order to discover the main issues from a large volume of text documents. Topic analysis can be regarded as static analysis because it analyzes a snapshot of the distribution of various issues. In contrast, some recent studies have attempted to perform dynamic issue tracking, which analyzes and traces issue trends during a predefined period. However, most traditional issue tracking methods have a common limitation : when a new period is included, topic analysis must be repeated for all the documents of the entire period, rather than being conducted only on the new documents of the added period. Additionally, traditional issue tracking methods do not concentrate on the transition of individuals' interests from certain issues to others, although the methods can illustrate macro-level issue trends. In this paper, we propose an individual interests tracking methodology to overcome the two limitations of traditional issue tracking methods. Our main goal is not to track macro-level issue trends but to analyze trends of individual interests flow. Further, our methodology has extensible characteristics because it analyzes only newly added documents when the period of analysis is extended. In this paper, we also analyze the results of applying our methodology to news articles and their access logs.

• 경영과학
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• 제31권3호
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• pp.61-76
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• 2014

There are three methods for calculating the optimal level for spare part inventories in a MIME (Multi Indenture and Multi Echelon) system : marginal analysis, Lagrangian relaxation method, and genetic algorithm. However, their solutions are sub-optimal solutions because the MIME system is neither convex nor separable by items. To be more specific, SRUs (Shop Replaceable Units) are required to fix a defected LRU (Line Replaceable Unit) because one LRU consists of several SRUs. Therefore, the level of both SRU and LRU cannot be calculated independently. Based on the limitations of three existing methods, we proposes a improved algorithm applying marginal analysis on determining LRU stock level and genetic algorithm on determining SRU stock level. It can draw optimal combinations on LRUs through separating SRUs. More, genetic algorithm enables to extend the solution search space of a SRU which is restricted in marginal analysis applying greedy algorithm. In the numerical analysis, we compare the performance of three existing methods and the proposed algorithm. The research model guarantees better results than the existing analytical methods. More, the performance variation of the proposed method is relatively low, which means one execution is enough to get the better result.

• 산업경영시스템학회지
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• 제44권4호
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• pp.136-144
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• 2021

This study focuses on the necessity of MOT methods in companies, especially the utilization level. Based on the analysis structure of the previous study (2012), this study was conducted to compare the results with the previous results. We investigated the settlement level of MOT, the degree of necessity for MOT methods, the degree of actual use, and the Product Realization Process (PRP) for MOT-related researchers in electronic companies (n=184). It was confirmed that the higher the demand for MOT methods in the corporate field, the higher the utilization level (ratio). In particular, the need for and utilization of techniques such as Environmental Analysis, Business Opportunity Analysis, Project Feasibility Review, Roadmap, Risk Management was high. These methods were beneficial along with cost management and quality management techniques. The most challenging part of using MOT methods was the lack of systematic use, the absence of experts, and the difficulty in selecting suitable techniques. The necessity of opening subjects such as Creative Thinking, Communication, Teamwork, and Professional Ethics was high among the PRP subjects. Furthermore, the necessity of opening courses in Cost and Safety Design and Applied Statistics was higher than in the previous study.

• Nuclear Engineering and Technology
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• 제54권4호
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• pp.1288-1294
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• 2022

Hydrogen as an environmentally friendly energy carrier has received special attention to solving uncertainty about the presence of renewable energy and its dependence on time and weather conditions. This material can be prepared from different sources and in various ways. In previous studies, fossil fuels have been used in hydrogen production, but due to several limitations, especially the limitation of the access to this material in the not-too-distant future and the great problem of greenhouse gas emissions during hydrogen production methods. New methods based on renewable and green energy sources as energy drivers of hydrogen production have been considered. In these methods, water or biomass materials are used as the raw material for hydrogen production. In this article, after a brief review of different hydrogen production methods concerning the required raw material, these methods are examined and ranked from different aspects of economic, social, environmental, and energy and exergy analysis sustainability. In the following, the current position of hydrogen production is discussed. Finally, according to the introduced methods, their advantages, and disadvantages, solar electrolysis as a method of hydrogen production on a small scale and hydrogen production by thermochemical method on a large scale are introduced as the preferred methods.

• 한국항공우주학회지
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• 제33권3호
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• pp.18-25
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• 2005

다분야 통합해석 시스템의 신뢰성 해석에 대한 기존의 연구들은 대부분 비선형 최적화 기법을 기반으로 하고 있다. 이들은 다분야 통합최적설계 프레임워크를 이용하여 신뢰성을 직접 해석하기 때문에 효율적인 AFORM기법을 적용하는 것이 불가능하다. 본 논문은 AFORM기법을 적용한 다분야 통합시스템의 순차적 신뢰성 해석기법(SARAM)을 제안한다. 이를 위해 신뢰성 해석과 다분야 통합시스템의 해석(MDA)을 분리하고, 순차적으로 배열하여, 되풀이구조를 가지는 해석구조를 구성하였다. 제안된 방법의 효율성은 계산량, 정확도, 그리고 동시 수행기능의 관점에서 평가하였다. 3개의 다분야 통합시스템 예제를 계산한 결과, 제안된 기법은 정확도를 보장하면서 기존의 방법에 비해 우수한 계산효율을 보였다.

• Communications for Statistical Applications and Methods
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• 제13권3호
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• pp.567-576
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• 2006

In this paper, we applied the multiblock dimension reduction methods to the classification of tumor based on microarray gene expressions data. This procedure involves clustering selected genes, multiblock dimension reduction and classification using linear discrimination analysis and quadratic discrimination analysis.

• Communications for Statistical Applications and Methods
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• 제8권1호
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• pp.39-49
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• 2001

When an appropriate model is fitted to explain a certain categorical data, outlying cell detection plays very important role to reduce the lack of fit. There exist many statistical methods to identify outlying cells in contingency table. In this paper, correspondence analysis is applied to identify one or two outlying cells. When corresponding relationships between categories of the row and columns are explored, we find that outlying cells could be identified via the correspondence analysis map.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
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• pp.223-226
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• 2004

The importance of a proper sample preparation and analysis technique has getting attention due to the complicity of toxic elements of interest from environmental samples depend on analytical purposes. It is critical to use proper analytical method to evaluate trace elements concentration in many environmental samples especially for making remediation decisions. Therefore, it is critical to apply a proper sampling and analytical method such as EPA publication SW-846 (Test Methods for Evaluating Solid Waste, Physical/chemical Methods). The objective of this study was to compare the USEPA Methods 3050B, modified 3050B, 305 la, and KBSI method (modified EPA 3052 Method) in term of recovery rate of metals. The NIST SRM (Montana soil) was used to compare the extraction and digestion efficiency. After sample has been collected the analysis were achieved by ICP-MS (Elan 6100, Perkin Elmer) as well as ICP-AES (Ultima 2C, JY) for trace elements and major elements.

• 한국문헌정보학회지
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• 제37권4호
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• pp.295-310
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• 2003

본 연구는 1991년부터 2003년까지 이용자연구 논문의 내용분석을 통하여 우리나라 이용자연구의 연구 방법과 연구동향을 제시한 것이다. 분석자료는 연구의 주제, 연구방법, 자료수집방법, 자료분석방법, 가설설정 등을 조사하였다. 이용자연구논문의 경우 1991∼2003년 가을까지 발표된 논문의 연 평균은 12.8편으로 나타났다. 연도별 발표량은 200l년이 24 편으로 가장 많고, 주제별 발표논문 현황은 정보이용행태, 이용자연구, 이용자 인터페이스, 도서관 및 정보이용교육, 온라인 목록 이용행태의 순으로 연구되었다. 연구방법은 문헌연구, 서베이 연구, 사례연구의 순서로 이루어지고 있으며, 자료 분석방법은 주로 기술통계를 사용하고 이용자연구자들은 카이자승(28.0%), 상관관계(22.7%), T-검증(17.35), 분산 분석(14.7%), 다변량분석(4.0%) 등을 사용하며, 연구자의 약 17%가 가설을 설정하고 있다.