• Journal of Computing Science and Engineering
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• 제4권4호
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• pp.276-290
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• 2010

The join operator is fundamental in relational database systems. Evaluating join queries on large tables is challenging because records need to be efficiently matched based on a given key. In this work, we analyze join queries in SQL with large tables in which a foreign key may be null, invalid or valid, given a referential integrity constraint. We conduct an extensive join performance evaluation on three DBMSs. Specifically, we study join queries varying table sizes, row size and key probabilistic distribution, inserting null, invalid or valid foreign key values. We also benchmark three well-known query optimizations: view materialization, secondary index and join reordering. Our experiments show certain optimizations perform well across DBMSs, whereas other optimizations depend on the DBMS architecture.

• Journal of the Korean Data and Information Science Society
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• 제15권4호
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• pp.891-898
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• 2004

An effective video indexing is required to manipulate large video databases. Most algorithms for video indexing have been commonly used histograms, edges, or motion features. In this paper, we propose an efficient algorithm using the luminance projection for video retrieval. To effectively index the video sequences and to reduce the computational complexity, we use the key frames extracted by the cumulative measure, and compare the set of key frames using the modified Hausdorff distance. Experimental results show that the proposed video indexing and video retrieval algorithm yields the higher accuracy and performance than the conventional algorithm.

• Nuclear Engineering and Technology
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• 제54권4호
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• pp.1374-1381
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• 2022

Under the influence of nuclear radiation, the reliability of steam generators (SGs) is an important factor in the efficiency and safety of nuclear power plant (NPP) reactors. Motion planning that remotely manipulates an SG mobile tube-inspection robot to inspect SG heat transfer tubes is the mainstream trend of NPP robot development. To achieve motion planning, conditional traversal is usually used for base position optimization, and then the A^* algorithm is used for path planning. However, the proposed approach requires considerable processing time and has a single expansion during path planning and plan paths with many turns, which decreases the working speed of the robot. Therefore, to reduce the calculation time and improve the efficiency of motion planning, modifications such as the matrix method, improved parent node, turning cost, and improved expanded node were proposed in this study. We also present a comprehensive evaluation index to evaluate the performance of the improved algorithm. We validated the efficiency of the proposed method by planning on a tube sheet with square-type tube arrays and experimenting with Model SG.

• 한국정보통신학회논문지
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• 제8권1호
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• pp.102-107
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• 2004

본 논문에서는 시각적. 공간적 정보로 구성된 이미지의 효율적인 검색을 위하여, 색상특징정보와 모양특징정보를 멀티인덱스키로 구성하고 질의 이미지의 입력 시 자동으로 색상특징정보와 모양특징정보를 동시에 추출하여 유사한 이미지를 검색할 수 있는 내용기반 이미지 검색시스템을 제안하였다. 제안된 시스템은 기존의 단일 특징정보를 이용한 방법이나 2가지 이상의 특징정보를 단계적으로 검색하는 방법에 비해 향상된 효율성과 신속성을 보이고 있다.

• 융합보안논문지
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• 제13권1호
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• pp.25-30
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• 2013

본 논문에서는 국내 물류산업의 경쟁력을 높이고 물류 선진화를 도모하기 위한 성과지표를 분석하고 세부적인 IT서비스를 제시한다. 여기서 물류 기업의 성과는 크게 효율성, 지속가능성 및 경제성 측면으로 구분하여 평가지표를 설정하고 IT서비스는 기업 및 공공물류로 분류하여 기업들에게 필요한 IT서비스를 분석한다. 아울러 사례연구로서 평택항 관련 종사자 즉, 물류기업 및 무역업, 공무원, 지역주민 등을 대상으로 실시한 설문조사 결과(SPSS 분석)를 통하여 물류기업의 현황을 진단하고 우선적으로 요구되는 물류 IT서비스의 우선순위를 조사한다. 분석결과, 물류산업의 생산성과 효율성을 높이기 위하여 전문인력의 확보와 표준화가 요구되고 시급한 IT서비스로서 물류자동화 기계화, u-Port 구축, 녹색친환경물류 그리고 물류보안 기술의 구현이 필요함을 알 수 있다.

• Journal of Electrical Engineering and Technology
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• 제13권4호
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• pp.1724-1731
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• 2018

The conventional polynomial neural network (PNN) is a classical flexible neural structure and self-organizing network, however it is not free from the limitation of overfitting problem. In this study, we propose a space search-optimized polynomial neural network (ssPNN) structure to alleviate this problem. Ranking selection is realized by means of ranking selection-based performance index (RS_PI) which is combined with conventional performance index (PI) and coefficients based performance index (CPI) (viz. the sum of squared coefficient). Unlike the conventional PNN, L2-norm regularization method for estimating the polynomial coefficients is also used when designing the ssPNN. Furthermore, space search optimization (SSO) is exploited here to optimize the parameters of ssPNN (viz. the number of input variables, which variables will be selected as input variables, and the type of polynomial). Experimental results show that the proposed ranking selection-based polynomial neural network gives rise to better performance in comparison with the neuron fuzzy models reported in the literatures.

• 정보교육학회논문지
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• 제1권1호
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• pp.49-59
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• 1997

이 논문은 자료접근 방법중 신속한 자료접근 및 갱신작업을 위해 일반적으로 많이 사용되는 인덱스(INDEX) 기법을 분석 비교함으로써 효율적인 데이타베이스 시스템을 위한 기초를 제공하고자 한다. 이를 위해 기존의 자료접근 기법들을 편의에 의해 자료 군집형태와 검출 형태에 따라 분류하고 인덱스 기법을 단일키와 다중키로 구분하였다. 단일키 인덱싱 기법을 동적 인덱스와 정적 인덱스 기법으로 나누어 비교 설명하고, 다중키 인덱스 기법중에서 K-d 트리, K-d-B 트리 및 역 화일과 그리드 화일의 자료 구조 특성을 비교 분석한 다음 각 기범들의 구조적 특성과 추출 질의어에 의한 일반적인 성능 특성을 비교 분석하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제26권2호
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• pp.233-240
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• 2013

The objective of this study was to investigate the effects of L-carnitine on growth performance, organ weight, biochemical parameters of blood, heart and liver, and ascites susceptibility of broilers at different ages reared under a low-temperature environment. A total of 420 1-d-old male Ross 308 broilers were randomly assigned to two dietary treatments with fifteen replicates of fourteen broilers each. Treatment diets consisted of L-carnitine supplementation at levels of 0 and 100 mg/kg. At 11-d of age, low temperature stress was used to increase ascites susceptibility. Blood, heart and liver samples were collected at different ages for analysis of boichemical parameters. The results showed that, there was no significant difference in growth performance with L-carnitine supplementation, but the mortality due to ascites was significantly decreased. Dietary L-carnitine supplementation significantly reduced heart index (HI) and ascites heart index (AHI) on d 21, lung index (LUI) on d 35 and liver index (LI) on d 42. The broilers fed diets containing L-carnitine had significantly lower red blood cell counts (RBC), hemoglobin (HGB) concentration and hematocrit (HCT) on d 42. Dietary L-carnitine supplementation significantly reduced malondialdehyde (MDA) content of heart tissue on d 21 and 35, and significantly increased total superoxide dismutase (T-SOD) and Glutathione peroxidase (GSH-Px) activity of the heart on d 21 and 42. L-carnitine supplementation significantly reduced serum triglyceride (TG) content on d 28 and 35 and serum glucose (GLU) on d 35 and 42, and significantly increased serum total protein (TP) and globulin (GLO) content on d 42. L-carnitine supplementation significantly enhanced liver succinodehydrogenase (SDH), malic dehydrogenase (MDH) and $Na^+$-$K^+$-ATPase activity on d 28, and tended to reduce the lactic acid (LD) level of liver on d 35 (p = 0.06). L-carnitine supplementation significantly reduced serum uric acid (UA) content on d 28, 35 and 42. Based on the current results, it can be concluded that dietary L-carnitine supplementation reduced organ index, red blood cell counts and hematocrit, enhanced antioxidative capacity of the heart, enhanced liver enzymes activity involved in tricarboxylic acid cycle, and reduced serum glucose and triglyceride. Therefore, it is suggested that L-carnitine can potentially reduce susceptibility and mortality due to ascites.

• Structural Engineering and Mechanics
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• 제48권3호
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• pp.291-308
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• 2013

Structural health monitoring is crucial to maintain the structural performance safely. Moreover, the Kullback-Leibler divergence (KLD) is applied usually to asset the similarity between different probability density functions in the pattern recognition. In this study, the KLD is employed to detect the damage. However the asymmetry of the KLD is a shortcoming for the damage detection, to overcoming this shortcoming, two other divergences and one statistic distribution are proposed. Then the damage identification by the KLD and its three descriptions from the symmetric point of view is investigated. In order to improve the reliability and accuracy of the four divergences, the gapped smoothing method (GSM) is adopted. On the basis of the damage index approach, the new damage index (DI) for detect damage more accurately based on the four divergences is developed. In the last, the grey relational coefficient and hypothesis test (GRCHT) is utilized to obtain the more precise damage identification results. Finally, a clear remarkable improvement can be observed. To demonstrate the feasibility and accuracy of the proposed method, examples of an isotropic beam with different damage scenarios are employed so as to check the present approaches numerically. The final results show that the developed approach successfully located the damaged region in all cases effect and accurately.

• 한국방재안전학회논문집
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• 제13권1호
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• pp.25-39
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• 2020

현재 스마트시티는 전 세계적인 추진에도 불구하고 스마트워터그리드 조성을 위한 기준이 부재하여 이들의 성공 여부를 판단하기에는 한계가 있다. 스마트워터그리드의 요건과 목표를 설정하고 기존 스마트워터그리드의 한계와 문제점을 정확히 진단하고 개선할 필요성은 분명하며, 이를 위해 스마트워터그리드 목표에 적합한 인덱스의 활용은 매우 중요하다. 따라서 본 연구에서는 스마트워터그리드의 목표측정과 달성정도 평가가 가능하고, 향후 스마트워터그리드 구축을 위한 이행계획에 근거로 활용할 수 있는 스마트워터그리드 성과평가지표(SWG KPI)를 개발하였다. 개발된 스마트워터그리드 성과평가지표(SWG KPI)를 통해 지속적인 스마트워터그리드의 역량평가를 수행할 수 있는 기반을 마련하고, 평가결과로 인한 영향력 확보를 통해스마트워터그리드 성과평가지표(SWG KPI)의 신뢰도 향상과 스마트워터그리드 역량평가를 위한 평가 테이블를 제공하여 계획 중인 스마트워터그리드에 대한 성과평가카드(Challenge Evaluation Card) 작성 및 사전평가 가능할 것으로 기대된다.