• Journal of Korean Society of Industrial and Systems Engineering
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• v.29 no.2
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• pp.20-30
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• 2006

Due to recent growing interest in autonomous software agents and their potential application in areas such as electronic commerce, the autonomous negotiation become more important. Evidence from both theoretical analysis and observations of human interactions suggests that if decision makers have prior information on opponents and furthermore learn the behaviors of other agents from interaction, the overall payoff would increase. We propose a new methodology for a strategy finding process using data mining in autonomous negotiation system; ANSIA(Autonomous Negotiation System using Intelligent Agent). ANSIA is a strategy based negotiation system. The framework of ANSIA consists of three component layers; 1) search agent layer, 2) data mining agent layer and 3) negotiation agent layer. ANSIA is motivated by providing a computational framework for negotiation and by defining a strategy finding model with an autonomous negotiation process.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.78.5-78
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• 2002

We propose an evolutionary reinforcement learning (RL) system with time-varying parameters that can deal with a dynamic environment. The proposed system has three characteristics: 1) It can deal easily with a dynamic environment by using time-varying parameters; 2) The division of state space is acquired evolutionarily by genetic algorithm (GA); 3) One does not have to design the rules constructing an agent in advance. So far many RL systems have been proposed. These systems adjust constant or non time-varying parameters; by those systems it is difficult to realize appropriate behavior in complex and dynamic environment. Hence, we propose the RL system whose parameters can vary temporally. T...

• Current Optics and Photonics
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• v.7 no.1
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• pp.15-20
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• 2023

We propose a new coherent optical receiver (COR) to detect optical receiver mode (ORM) subchannels selectively in coherent optical (CO) ORM division multiplexing (ORMDM) systems. In the CO-ORMDM systems, each optical channel is a linear sum of ORM subchannels, to obtain high spectral efficiencies (SEs). The COR uses an ORM subcarrier as its local oscillator (LO) and reads the transmitted data at the origin times of ORM signals. For example, if the m^th ORM subcarrier is used as the LO, then the COR reads the data of the m^th ORM subchannel. The proposed COR is fast and can make CO-ORMDM systems useful for real-time optical communication with high SE.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.4
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• pp.498-504
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• 2018

The conventional photovoltaic(PV) systems are designed the installation angle for maximizing power output by considering a geographical characteristics, weather and climate conditions such as the solar radiation and atmosphere temperature. However, the PV generators must be designed to deal with the extreme situations like typhoons, earthquakes because PV systems are exposed to the ambient conditions and external shock due to condition of PV location. Especially, the wind has relatively higher influence on the design of PV systems, in this paper we proposed the method of determining the optimal nominal dimension of the facilities, which can withstand the maximum wind pressure. By using the proposed method, we determined the optimal installation angle for the aspect stability of PV facilities and amount of power output. Moreover, we analyzed the monthly amount of power for each installation angle of PV systems, and proposed the changing strategy of installation angle by determining the optimal angle to produce maximum power for each period.

• Journal of Information Processing Systems
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• v.9 no.1
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• pp.157-172
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• 2013

There are many recommendation systems available to provide users with personalized services. Among them, the most frequently used in electronic commerce is 'collaborative filtering', which is a technique that provides a process of filtering customer information for the preparation of profiles and making recommendations of products that are expected to be preferred by other users, based on such information profiles. Collaborative filtering systems, however, have in their nature both technical issues such as sparsity, scalability, and transparency, as well as security issues in the collection of the information that becomes the basis for preparation of the profiles. In this paper, we suggest a movie recommendation system, based on the selection of optimal personal propensity variables and the utilization of a secure collaborating filtering system, in order to provide a solution to such sparsity and scalability issues. At the same time, we adopt 'push attack' principles to deal with the security vulnerability of collaborative filtering systems. Furthermore, we assess the system's applicability by using the open database MovieLens, and present a personal propensity framework for improvement in the performance of recommender systems. We successfully come up with a movie recommendation system through the selection of optimal personalization factors and the embodiment of a safe collaborative filtering system.

• Journal of Electrical Engineering and Technology
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• v.12 no.3
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• pp.996-1006
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• 2017

Phasor Measurement Unit (PMU) placement is a crucial problem for State Estimation (SE) of the power system, which can ensure that the power network is fully observed. Further, the observation reliability problem of the system has been concerned in the operation conditions. In this paper, based on modified weighted adjacent matrix ($A_w$), an optimal placement method is proposed to solve simultaneously two problems involving the optimal PMU placement problem and the observation reliability enhancement problem of the system. The purpose of the proposed method is to achieve both the minimum total cost and the maximum observation reliability, with a focus on increasing the security of observability, strengthening the observation reliability of buses as well as enhancing the effectiveness of redundancy. Simulations on IEEE 14, 24, 30 and 57 bus test systems are presented to justify the methodology. The results of this study show that the proposed method is not only ensuring the power network having the observability effectively but also enhancing significantly the observation reliability. Therefore, it can be a useful tool for SE of the power system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.1
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• pp.245-265
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• 2022

In response to problems such as insufficient extraction information, low detection accuracy, and frequent misdetection in the field of Thangka image defects, this paper proposes a YOLOv5 prediction algorithm fused with the attention mechanism. Firstly, the Backbone network is used for feature extraction, and the attention mechanism is fused to represent different features, so that the network can fully extract the texture and semantic features of the defect area. The extracted features are then weighted and fused, so as to reduce the loss of information. Next, the weighted fused features are transferred to the Neck network, the semantic features and texture features of different layers are fused by FPN, and the defect target is located more accurately by PAN. In the detection network, the CIOU loss function is used to replace the GIOU loss function to locate the image defect area quickly and accurately, generate the bounding box, and predict the defect category. The results show that compared with the original network, YOLOv5-SE and YOLOv5-CBAM achieve an improvement of 8.95% and 12.87% in detection accuracy respectively. The improved networks can identify the location and category of defects more accurately, and greatly improve the accuracy of defect detection of Thangka images.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.5
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• pp.48-56
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• 2009

In this paper, laser-assisted machining(LAM) has been employed to machine hot isostatically pressed (HIPed) Si3N4 work pieces. Due to little residual flaws and porosity, HIPed $Si_3N_4$ work pieces are more difficult to machine compared to normally sintered $Si_3N_4$ workpieces. In LAM, the intense energy of laser was used to enhance machinability by locally heating the workpiece and thus reducing yield strength. In experiments, the laser power ranges from 200W to 800W and the diameter of work pieces is 16mm. While machining, the surface temperature was kept nearly constant by laser heating except for a short period of rise time of max. 58 seconds. Results showed as feed rate increases the surface temperature of $Si_3N_4$ workpieces decreases slightly, whereas the effect of depth of cut is disregardable. With a laser power of 800W, achievable maximal depth of cut as 0.7mm and feed rate was 0.03mm/rev.

• Journal of the Society of Naval Architects of Korea
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• v.56 no.1
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• pp.1-10
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• 2019

Naval ship design and related other activities can be characterized by the complexity of the interactions among products, activities, and disciplines. Such complexities often result in inferior designs, cost overrun, and late-delivery. Hence there exist tremendous interests in both improving the design process itself and optimizing the interactions among design activities. This paper looks at the complexity of designing naval ships thereby leading to the innovation of current ship design practices using design structure matrix. It can be used to induce the optimal ordering of design activities as well as identify sources of complexities. The method presented here identifies coupled design activities useful for reducing the complexity of naval ship design as well as optimally reordering design activities. This paper recommends the use of design structure matrix method suitable for numerically optimizing the concept design process of naval ship, and reducing cost and time required in designing naval ships by modeling and analyzing the design activities and engineering tasks, defined in systems engineering planning documents.

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1555-1560
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• 2010

Quantum dots (QDs) are extensively employed for biomedical research as a fluorescence reporter and their use for various labeling applications will continue to increase as they are preferred over conventional labeling methods for various reasons. However, concerns have been raised over the toxicity of these particles in the biological system. Till date no thorough investigation has been carried out to identify the molecular signatures of QD mediated toxicity. In this study we evaluated the toxicity of CdSe, $Cd_{1-x}Zn_xS$/ZnS and CdSe/ZnS quantum dots having different spectral properties (red, blue, green) using human embryonic kidney fibroblast cells (HEK293). Cell viability assay for both short and long duration exposure show concentration material dependent toxicity, in the order of CdSe > $Cd_{1-x}Zn_xS$/ZnS > CdSe/ZnS. Genome wide changes in the expression of genes upon QD exposure was also analyzed by wholegenome microarray. All the three QDs show increase in the expression of genes related to apoptosis, inflammation and response towards stress and wounding. Further comparison of coated versus uncoated CdSe QD-mediated cell death and molecular changes suggests that ZnS coating could reduce QD mediated cytotoxicity to some extent only.