• Nuclear Engineering and Technology
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• 제44권8호
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• pp.911-918
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• 2012

Steam generator level control at low power is difficult due to its adverse thermal hydraulic properties, and is usually conducted by an operator. The basic model predictive control (MPC) is similar to the action of an operator in that the operator knows the desired reference trajectory for a finite period of time and takes the necessary control actions needed to ensure the desired trajectory. An MPC is based on a model; the performance as well as the efficiency of the MPC depends heavily on the exactness of the model. In this study, steam generator models that can describe in detail its thermal hydraulic behaviors, particularly at low power, are used in the MPC design. The design scope is divided into two parts. First, the MPC feedwater controller of the feedwater station is determined, and then the MPC level controller for the overall system is designed. Because the dynamic properties of a steam generator change with the power levels, a realistic situation is simulated by changing the transfer functions of the steam generator at every time step. The resulting MPC controller shows good performance.

• Journal of Computing Science and Engineering
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• 제9권4호
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• pp.204-213
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• 2015

Under the conditional independence assumption among local features, the Naive Bayes Nearest Neighbor (NBNN) classifier has been recently proposed and performs classification without any training or quantization phases. While the original NBNN shows high classification accuracy without adopting an explicit training phase, the conditional independence among local features is against the compositionality of objects indicating that different, but related parts of an object appear together. As a result, the assumption of the conditional independence weakens the accuracy of classification techniques based on NBNN. In this work, we look into this issue, and propose a novel Bayesian network for an NBNN based classification to consider the conditional dependence among features. To achieve our goal, we extract a high-level feature and its corresponding, multiple low-level features for each image patch. We then represent them based on a simple, two-level layered Bayesian network, and design its classification function considering our Bayesian network. To achieve low memory requirement and fast query-time performance, we further optimize our representation and classification function, named relation-based Bayesian network, by considering and representing the relationship between a high-level feature and its low-level features into a compact relation vector, whose dimensionality is the same as the number of low-level features, e.g., four elements in our tests. We have demonstrated the benefits of our method over the original NBNN and its recent improvement, and local NBNN in two different benchmarks. Our method shows improved accuracy, up to 27% against the tested methods. This high accuracy is mainly due to consideration of the conditional dependences between high-level and its corresponding low-level features.

• 산업노동연구
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• 제19권1호
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• pp.65-104
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• 2013

본 연구는 자원기반관점을 기초로 고성과작업시스템-종업원성과-운영성과 간 관계를 실증적으로 검증하고자 하였다. 조직수준의 고성과작업시스템과 개인수준의 종업원 태도 간 실증분석을 위해 위계적 선형모형(hierarchical linear modeling)을 활용한 다수준분석을 실시하여 인과관계의 정확성을 높였다. 이를 위해, 제3차 인적자원기업패널(HCCP: Human Capital Corporate Panel) 데이터 가운데 316개 기업과 7,872명(팀장 923명 포함)의 응답자를 대상으로, 고성과작업시스템이 개인수준인 종업원성과에 미치는 영향을 확인하였다. 이후, 분석수준을 일치시키기 위해 개인수준(종업원성과)과 팀수준(운영성과)의 패널자료를 조직수준으로 집산(aggregation)하여 타당화 검증을 실시하고, 조직수준에서 매개효과를 검증하였다. 그 결과, 고성과작업시스템은 종업원성과(직무만족, 조직몰입, 신뢰)와 운영성과에 각각 유의한 영향을 미치는 것으로 나타났다. 종업원성과 개별변수의 매개효과 검증에서는 직무만족과 신뢰가 고성과작업시스템과 운영성과 간 관계를 매개하는 것으로 나타났다. 결론에는 연구의 결과, 이론적 시사점 및 한계점을 제시하고 있다.

• 시스템엔지니어링학술지
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• 제10권2호
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• pp.71-79
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• 2014

To enhance success probability of a system development project, its overall risk level should be minimized through systematically managing schedules, costs, and technical performances. However, Attempts to manage technical performance compared to numerous efforts to control costs and schedules in such projects are deficient. Particularly, a space launch vehicle, a large complex system, development project is much less likely to meet its technical performance objectives due to its technological difficulty, along with schedule delay and cost overrun. The technical performance management (TPM) is a method for tracking and managing technical progress in order to achieve technical performance targets within schedule and budget. In this paper, we investigate applications of the TPM in several space launch vehicle development projects. Then we propose and validate the TPM process to achieve a successful mission in such projects.

• Nuclear Engineering and Technology
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• 제30권1호
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• pp.58-74
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• 1998

A PC window-based computer code, CONPAS (CONtainment Performance Analysis System), has been developed to integrate the numerical, graphical, and results-operation aspects of Level 2 probabilistic safety assessments (PSA) for nuclear power plants automatically. As a main logic for accident progression analysis, it employs a concept of the small containment phenomenological event tree (CPET) helpful to trace out visually individual accident progressions and of the detailed supporting event tree (DSET) for its detailed quantification. For the integrated analysis of Level 2 PSA, the code utilizes five distinct, but closely related modules. Its computational feasibility to real PSAs has been assessed through an application to the UCN 3&4 full scope Level 2 PSA. Compared with other existing computer codes for Level 2 PSA, the CONPAS code provides several advanced features: (1) systematic uncertainty analysis / importance analysis / sensitivity analysis, (2) table / graphical display & print, (3) employment of the recent Level 2 PSA technologies, and (4) highly effective user interface. The main purpose of this paper is to introduce the key features of CONPAS code and results of its feasibility study.

• 한국경영과학회지
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• 제31권4호
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• pp.49-68
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• 2006

E-business strategy has interests in Issues of strategic positioning and its impact on firm performance. These studies address the environmental factors as antecedents to strategic decision makings and its consequences such like firm performance. However most studies has not considered the role of business models In explaining e-business firm performance. We adopt Porter's generic strategies to the e-business context. We Identify business models and e-business environmental factors as antecedents and then examine these factors Influence on firm performance. We find that uncertainty of environment has a negatively related to the strategic choices of e-Business firms; in contrast, market turbulence positively affects the level of adoption of all the strategies. Among the strategies, marketing differentiation only makes an Impact on firm performance.

• 한국BIM학회 논문집
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• 제8권1호
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• pp.43-55
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• 2018

Recently, there have been increasing studies on the application of digital technology, which has its focus of the irregular building. However, most of these studies have not clarified the objective of the technology and the effectiveness of professional manpower on its performance. This study analyzes actual used technology and the role of specialty contractor. It presents a framework to quantify the performance of the specialty contractor. For these purposes, this paper presents a proposed method to evaluate the activities of specialty contractors using a queueing model. As an attempt to verify the model, an actual irregular building project, in which digital fabrication is applied, is investigated during the construction phase. In order to collect the digital fabrication data, digital fabrication reports and specialty contractor's work log of project are reviewed. In addition, Digital Fabrication input personnel, productivity data are collected through interviews with experts involving in the case project. Analysis of specialty contractor's performance in digital fabrication reveals that the wait status of project participants varies probabilistically depending on the digital technology application level. The results of this study are expected to contribute toward the improvement of the production level in the construction industry.

• Asian-Australasian Journal of Animal Sciences
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• 제22권10호
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• pp.1461-1476
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• 2009

This review focuses on the metabolic and osmoregulatory functions of betaine and its impact on nutrient digestibility and performance in pigs and poultry. Betaine is the trimethyl derivative of the amino acid glycine, and is present in plant and animal tissue. It has been shown to play an important role in osmoregulation of plants, bacteria and marine organisms. Due to its chemical structure, betaine exerts a number of functions both at the gastrointestinal and metabolic level. As a methyl group donor, betaine is involved in transmethylation reactions and donates its labile methyl group for the synthesis of several metabolically active substances such as creatine and carnitine. Therefore, supplementation of betaine may reduce the requirement for other methyl group donors such as methionine and choline. Beneficial effects on intestinal cells and intestinal microbes have been reported following betaine supplementation to diets for pigs and poultry, which have been attributed to the osmotic properties of betaine. Furthermore, betaine potentially enhances the digestibility of specific nutrients, in particular fiber and minerals. Moreover, at the metabolic level, betaine is involved in protein and energy metabolism. Growth trials revealed positive effects of supplemental betaine on growth performance in pigs and poultry, and there is evidence that betaine acts as a carcass modifier by reducing the carcass fat content. In conclusion, due to its various metabolic and osmoregulatory functions, betaine plays an important role in the nutrition of monogastric animals.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제18권8호
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• pp.2230-2252
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• 2024

Advances in deep learning technology have enabled the generation of more realistic deepfakes, which not only endanger individuals' identities but also exploit vulnerabilities in face recognition systems. The majority of existing deepfake detection methods have primarily focused on RGB-based analysis, offering unreliable performance in terms of detection accuracy and time. To address the issue, a grayscale-based deepfake detection method has recently been proposed. This method significantly reduces detection time while providing comparable accuracy to RGB-based methods. However, despite its significant effectiveness, the "key components" that directly affect the performance of grayscale-based deepfake detection have not been systematically analyzed. In this paper, we target three key components: RGB-to-grayscale conversion method, brightness level in grayscale, and resolution level in grayscale. To analyze their impacts on the performance of grayscale-based deepfake detection, we conducted comprehensive evaluations, including component-wise analysis and comparative analysis using real-world datasets. For each key component, we quantitatively analyzed its characteristics' performance and identified differences between them. Moreover, we successfully verified the effectiveness of an optimal combination of the key components by comparing it with existing deepfake detection methods.

• 한국유통학회지:유통연구
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• 제3권1호
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• pp.71-98
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• 1998

This study aimed to investigate how such retailers as department stores, large discount stores, book wholesalers, and clothing wholesalers used information technology for the QR strategy and whether the QR strategy had an effect on performance with a focus on the pipeline strategy. For this purpose, the QR strategy was divided into transaction efficiency, supplier partnership, and customer detail strategy. The differences in performance and information technology were analyzed according to the fit of the pipeline strategy, such as internal focus, supplier focus, and customer focus, the business strategy which were used by the retailers. And, an attempt was made to investigate whether performance was raised according to the level of adopting information technology. The results can be summarized as allows. First, the adaptive level of information technology had an effect on performance. But, seeing that the explanatory power of the regression analysis on the effect of the adaptive level of information technology on performance was shown to be very weak, it is judged that the level of QR information technology in the responding firms was very low compared to that of foreign firms. Second, information technology used by the retailers included universal product code, bar coding, customer database, and information utilities. It was shown that the group of firms seeking the transaction efficiency QR strategy and the internal focus pipeline strategy had the higher level of information technology than the retailers seeking other customer detail QR strategy and the customer focus pipeline strategy and the retailers with inconsistent strategy. This indicates that the firm seeking to raise its internal efficiency has a high level of using information technology. At the end of the paper, managerial implication and future research directions were discussed.