• 한국산업정보학회논문지
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• 제21권5호
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• pp.73-83
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• 2016

국내 1위 인터넷포털 사업자인 네이버는 사용자가 지정하는 키워드가 특정 기간 동안에 네이버에서 얼마나 자주 검색되었는지에 관한 피검색빈도자료를 제공한다. 본 연구는 네이버의 피검색빈도자료를 활용하여 기업명의 피검색빈도와 그 기업의 미래 주식수익률과의 관계에 대해 분석하였다. 그 결과는 다음과 같다. 첫째, 기업명의 피검색빈도는 극단적 수익률 및 거래회전율과 같은 기존의 투자자 관심(investor attention)변수와 중복되지 않는 새로운 투자자 관심변수이다. 둘째, 금주의 피검색빈도가 높은 기업일수록 그 다음 주의 주간수익률이 높다. 셋째, 피검색빈도가 높은 기업은 이후에도 수익률 반전현상이 관찰되지 않으므로, 피검색빈도는 해당 기업에 대한 본질적 정보를 포함하는 것으로 볼 수 있다. 넷째, 피검색빈도가 주식수익률에 미치는 영향은 시장 수준의 투자자 관심사건(market-wide attention grabbing events)이 발생한 이후 더욱 강하게 나타난다.

• 정보기술과데이타베이스저널
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• 제6권1호
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• pp.27-46
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• 1999

This study was intended to find the use patterns of internet search engines of librarians and to measure the relationship between internet use frequency and the use behavior of internet search engines. The results showed that librarians use Web search engines for academic information retrieval and are satisfied with the search results. The major problems when librarians use search engines were that search engines retrieve many non-relevant documents. As a result of hypotheses test, the relationship between internet frequency and the preference of search engines was not significantly different. On the other hand, the hypotheses that internet frequency affects satisfaction of search results, recognition of importance of search engines, and the need of retraining of librarians for internet information retrieval were shown to be significant.

• 전기학회논문지
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• 제58권7호
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• pp.1255-1262
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• 2009

The present study explained the phenomenon that low frequency oscillation is synchronized with discrete data obtained from a wide area system, and a sync search method. When a disturbance occurs in an power system, various controllers operate in order to maintain synchronization. If the system's damping is poor, low frequency oscillations continue for a long time and the oscillations are synchronized with one another at specific frequency. The present study estimated dominant modes, magnitude and phase of signals by applying parameter estimation methods to discrete signals obtained from an power system, and performed sync search among wide area signals by comparing the estimated data. Sync search was performed by selecting those with the same frequency and damping constant from dominant oscillation modes included in a large number of signals, and comparing their magnitude and phase. In addition, we defined sync indexes in order to indicate the degree of sync between areas in a wide area system. Furthermore, we proposed a wide area sync search method by normalizing mode magnitude in discrete data obtained from critical generator of the wide area. By applying the sync search method and sync indexes proposed in this study to two area systems, we demonstrated that sync scanning can be performed for discrete signals obtained from power systems.

• International Journal of Control, Automation, and Systems
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• 제4권2호
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• pp.155-164
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• 2006

This paper focuses on a new optimization technique of a fuzzy logic based proportional integral (FLPI) load frequency controller by the multiple tabu search (MTS) algorithm. Conventionally, the membership functions and control rules of fuzzy logic control are obtained by trial and error method or experiences of designers. To overcome this problem, the MTS algorithm is proposed to simultaneously tune proportional integral gains, the membership functions and control rules of a FLPI load frequency controller in order to minimize the frequency deviations of the interconnected power system against load disturbances. The MTS algorithm introduces additional techniques for improvement of the search process such as initialization, adaptive search, multiple searches, crossover and restart process. Simulation results explicitly show that the performance of the proposed FLPI controller is superior to conventional PI and FLPI controllers in terms of overshoot and settling time. Furthermore, the robustness of the proposed FLPI controller under variation of system parameters and load change are higher than that of conventional PI and FLPI controllers.

• 한국정보과학회논문지:데이타베이스
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• 제36권4호
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• pp.321-326
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• 2009

기존의 웹 검색 엔진들은 사용자의 검색 의도를 충분히 반영하지 못하기 때문에 사용자가 원하는 정확한 정보를 찾기가 어렵다. 따라서 최근에는 개인의 검색 패턴을 분석하여 검색에 반영함으로써 검색 결과에 대한 만족도를 높이기 위한 많은 연구들이 진행되고 있다. 이러한 개인화 검색을 통해 사용자는 방대한 웹상의 정보들 중 자신의 검색 의도에 보다 적합하고 정확한 정보를 획득할 수 있다. 본 논문에서는 웹 사용자들의 질의어 사용 빈도수(Frequency)에 대한 랭킹 정보를 통해 최근 주요 관심사(Interest)를 파악하고, 주요 관심사 별로 형성된 커뮤니티(Community)를 기반으로 수행되는 개인화 검색 방안을 제안한다. 실험결과 질의어 빈도수, 관심사 및 커뮤니티를 검색에 반영할 경우 개인의 검색 의도에 보다 적합한 검색 결과가 제공되는 것을 확인할 수 있다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.139-144
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• 2008

In this study, damage detection method using harmony search method and frequency response is proposed. In order to verify this method, the following approaches are implemented. Firstly, damage detection method using harmony search is developed. To detect damage, objective function that minimize difference with natural frequency and modal strain energy from undamaged and damaged model is used. Secondly, finite element model for beam structure is created. And damage scenario is determined. Lastly, damage detection is performed by proposed method and utility of proposed method is verified.

• 한국해양공학회지
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• 제27권5호
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• pp.36-42
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• 2013

We present the optimum design for the cross-sectional(sizing) and shape optimization of truss structures with natural frequency constraints. The optimum design method used in this paper employs continuous design variables and the Harmony Search Algorithm(HSA). HSA is a meta-heuristic search method for global optimization problems. In this paper, HSA uses the method of random number selection in an update process, along with penalty parameters, to construct the initial harmony memory in order to improve the fitness in the initial and update processes. In examples, 10-bar and 72-bar trusses are optimized for sizing, and 37-bar bridge type truss and 52-bar(like dome) for sizing and shape. Four typical truss optimization examples are employed to demonstrate the availability of HSA for finding the minimum weight optimum truss with multiple natural frequency constraints.

• 전기전자학회논문지
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• 제22권4호
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• pp.999-1005
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• 2018

본 논문에서는 전력계통에서 정밀하고 변화에 수렴성이 빠른 탐색을 기반으로 하는 주파수 추정 기법을 제안하였다. 제안된 주파수 추정 알고리즘은 고분해능 스펙트럼의 기울기를 추정하여 스펙트럼의 peak 점을 탐색하는 구조를 적용하였다. 과도적으로 주파수 변화가 큰 경우에 기존 방법들의 단점인 수렴속도가 늦는 점을 보완 또는 개선하기 위한 방법으로 Context analysis를 통하여 Full-search 기법과 주파수 추정변수들을 적응적으로 적용하여 주파수 추정의 정밀도와 수렴속도를 향상시키고 대표적인 주파수 추정기법인 DFT(discrete Fourier transform) 방법, ECKF(extended complex Kalman filter), MV(minimum variable)방법들과 비교하여 수렴성과 정밀도가 우수함을 보였다.

• 한국실내디자인학회논문집
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• 제22권5호
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• pp.152-161
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• 2013

This study is about the visual appreciation by sex with the analysis of time range of observing data which was got through observation experiment with the space of lobby in hospitals. The observation data of the subjects who observed the space include the frequency and time, through which the process of visual appreciation could be evaluated with the definition of the frequency and the time of observation. First, the fact that men had higher frequency of observation than women means the former had more movement than the latter, and another fact of their fewer times can be understood as the time of their staying was shorter. That is, even though the men had more movements of sight, they showed the feature of staying shorter. Second, the rate high and low of observation frequency and times made it possible for observation characteristics to be defined as 'intensive search' 'active search' 'fixed concentration' and 'search wandering.' The definition of understanding this process of visual appreciation can be available for a frame of effective analysis of observation characteristics according to the passage of time. Third, the intense search is the case of 'high frequency' having the feature of high visual appreciation owing to the active visual actions for acquiring information. Men were found to have more intense search which decreased gradually as time passed, while women showed the feature of many times of intense search. Fourth, it was found that with many observation data in a certain range of time the subjects had fixed concentration, where women were found to have repetitive fixed concentration along with the change of observation time while men were seen to have more observation tendency for fixed concentration. Fifth, at the cross tabulation of frequency and times, men had the feature of dispersed visual appreciation while women had more distinction between fixation and movement, which revealed that there is surely the difference between men and women in the process of visual appreciation.

• 대한가정학회지
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• 제36권5호
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• pp.1-15
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• 1998

The purpose of this study is to examine the effects of the extent of information search on consumer satisfaction and to provide, ultimatly, effective consumer search for consumer satisfaction. Data for this study were collected from 452 computer purchasers who living in Seoul. This study has focused on new computer purchasers. The amount of internal information was measured by three categories, such as the number of computer purchase, the frequency, duration of computer use and the degree of computer education. In addition, the amount of prepurchase search was measured by threecategories, such as neutral information, commercial information and private information. The research results shows that the variables affecting on the level of consumer satisfaction are objective search, the degree of computer education, the frequency and duration of computer use, the number of computer purchase. Meanwhile, commercial information search and private information search are not significant affecting variables on the level of consumer satisfaction.