• 한국CDE학회논문집
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• 제17권5호
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• pp.375-386
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• 2012

Most engineering design problems require analyses or simulations to evaluate objective functions. However, a single simulation can take many hours or even days to finish for many real world problems. As a result, design optimization becomes impossible since they require hundreds or thousands of simulation evaluations. The surrogate-based optimization (SBO) strategy became a remedy for such computationally expensive analyses and simulations. A surrogate-based optimization strategy has been developed in this study in order to improve global optimization performance. The strategy is a heuristic algorithm and it exploits not only multiple surrogates, but also multiple optimizers. Multiple optimizations of multiple surrogate models yield multiple candidate design points of optima. During the sequential sampling process, the algorithm ranks candidate design points, selects the points as many as specified, and builds the improved surrogate model. Various mathematical functions with different numbers of design variables are chosen to compare the proposed method with the other most recent algorithm, MSEGO. The proposed method shows superior performance to the other method.

• 농촌지도와개발
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• 제19권1호
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• pp.129-145
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• 2012

There are many positioning studies utilizing Analytic Hierarchy Process (AHP) in tourism industry. In this study, it was tried to develop new evaluation criteria for positioning and to discuss the importance of evaluation factors, as the development of tourist's spots was pursued in diversified ways. The purpose of this study was to allow the development of tourist spots more objectively and more efficiently utilizing Analytic Hierarchy Process ("AHP" hereunder) to appoint the best place for the tourism complex in Buyeo. According to AHP analysis procedures, 5 places near Baikje Cultural Block connecting with a ferry in Buyeo-gun were selected as candidates. To perform AHP analysis, evaluation criteria and a survey were used and then weight of evaluation criteria was induced. With the conditions on criteria, standard score of each criterion and candidate was calculated. By multiplying standard score and final weight and then summing up, the candidate place with the highest score shall be appointed as the most optimal place for Buyeo-gun Agricultural Tourism Complex.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2004년도 추계 학술대회논문집
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• pp.173-176
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• 2004

In this study, the multidisciplinary aerodynamic-structural optimal design is carried out for the supersonic fighter wing. Through the aeroelastic analyses of the various candidate wings, the aerodynamic and structural performances are calculated such as the lift coefficient, the drag coefficient and the deformation of the wing. In general, the supersonic fighter is maneuvered under the various flight conditions and those conditions must be considered all together during the design process. The multi-point design, therefore, is deemed essential. For this purpose, supersonic dash, long cruise range and high angle of attack maneuver are selected as representative design points. Based on the calculated performances of the candidate wings, the response surfaces for the objectives and constraints are generated and the supersonic fighter wing is designed for better aerodynamic performances and less weights than the baseline. At each design point, the single-point design is performed to obtain better performances. Finally, the multi-point design is performed to improve the aerodynamic and structural performances for all design points. The optimization results of the multi-point design are compared with those of the single-point designs and analyzed in detail.

• 전자공학회논문지SC
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• 제41권4호
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• pp.13-20
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• 2004

본 논문에서는 표적 추적에 널리 사용되는 다중 가설 추적(MHT: Multiple Hypothesis Tracking) 알고리듬의 추적 성능을 예측할 수 있는 방법을 제시한다. MHT 알고리듬은 최적의 베이시안 필터로서, 측정된 데이터를 기초로 가능한 가설들을 구성하고, 각 가설들의 확률을 구하게 된다. 모든 측정치들은 관심 있는 실제 표적에서 기인할 수 있을 뿐만 아니라, 새로운 표적이거나 표적이외의 거짓에서 발생할 수도 있다는 사건을 고려하고 있기 때문에 다른 여러 추적 필터에 비해 MHT 알고리듬은 우수한 추적성능을 가지고 있다고 알려져 있다. 측정 데이터와 무관하게 추적기의 성능을 표현하기 위해서 HYCA(Hybrid Conditional Average)방법을 이용하여 MHT 알고리듬에서 발생하는 모든 가설 확률의 기대 값을 구한 후, 이를 이용하여 성능을 예측하는 방법을 제시한다. 수치실험을 통하여 이 논문에서 제시한 성능 예측이 타당함을 보인다.

• Journal of Power Electronics
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• 제16권6호
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• pp.2231-2242
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• 2016

A simplified model predictive control method is presented in this paper. This method is based on a future reference voltage vector for a three-phase four-leg voltage source inverter (VSI). Compared with the three-leg VSIs, the four-leg VSI increases the possible switching states from 8 to 16 owing to a fourth leg. Among the possible states, this should be considered in the model predictive control method for selecting an optimal state. The increased number of candidate switching states and the corresponding voltage vectors increase the calculation burden. The proposed technique can preselect 5 among the 16 possible voltage vectors produced by the three-phase four-leg voltage source inverters, based on the position of the future reference voltage vector. The discrete-time model of the future reference voltage vector is built to predict the future movement of the load currents, and its position is used to choose five preselected vectors at every sampling period. As a result, the proposed method can reduce calculation load by decreasing the candidate voltage vectors used in the cost function for the four-leg VSIs, while exhibiting the same performance as the conventional method. The effectiveness of the proposed method is demonstrated with simulation and experiment results.

• 한국유체기계학회 논문집
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• 제20권1호
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• pp.21-28
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• 2017

Optimization process of pre-swirl nozzle geometry was conducted to improve the discharge coefficient of pre-swirl system by using CFD. The optimization of pre-swirl nozzle shape covered the converging angle and the location of the converging nozzle. Optimization process included Optimal Latin Hyper-cube Design method to get the experimental points and the Kriging method to create the response surface which gives candidate points. The process was finished when the difference between the predicted value and CFD value of candidate point was less than 0.1 %. This paper compared the Reference model, Initial model which is the first model of optimization and Optimized model to study flow characteristics. Finally, the discharge coefficient of Optimized model is improved about 17 % to the Reference model.

• Genomics & Informatics
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• 제8권2호
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• pp.81-85
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• 2010

The aim of the study was to investigate pig reference families, generated from Korean native pigs (KNP) that were crossed with Yorkshire (YS) breeds, which were used to evaluate genetic markers to select breeding animals with superior pork quality. A set of five candidate genes (PRKAG3, MC4R, CAST, ESR, and PRLR ) was analyzed for association with pork quality traits. PRKAG3 (I199V) SNP genotypes were significantly associated with muscle moisture, protein, and fat contents. The MC4R D298N polymorphism was significantly associated with meat tenderness and color traits. The CAST polymorphism was significantly associated with muscle moisture and crude protein traits. These three genes have been associated with pork quality traits in other pig populations, and some of our results are consistent with earlier studies. In addition, two reproductive candidate genes (ESR and PRLR ) did not have significant associations. These results suggest that further study is warranted to investigate and develop more DNA markers associated with pork quality in our KNP-crossed pig families.

• Journal of Information Processing Systems
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• 제13권4호
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• pp.805-817
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• 2017

Cross-lingual query expansion is usually based on the relationship among monolingual words. Bilingual comparable corpus contains relationships among bilingual words. Therefore, this paper proposes a method based on these relationships to conduct query expansion. First, the word vectors which characterize the bilingual words are trained using Chinese and Thai bilingual comparable corpus. Then, the correlation between Chinese query words and Thai words are computed based on these word vectors, followed with selecting the Thai candidate expansion terms via the correlative value. Then, multi-group Thai query expansion sentences are built by the Thai candidate expansion words based on Chinese query sentence. Finally, we can get the optimal sentence using the Chinese and Thai query expansion method, and perform the Thai query expansion. Experiment results show that the cross-lingual query expansion method we proposed can effectively improve the accuracy of Chinese and Thai cross-language information retrieval.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권5호
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• pp.1951-1972
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• 2018

Wi-Fi Access Point (AP) optimization approaches are used in indoor positioning systems for signal coverage enhancement, as well as positioning precision improvement. Although the huge power consumption of the AP optimization forms a serious problem due to the signal coverage requirement for large-scale indoor environment, the conventional approaches treat the problem of power consumption independent from the design of indoor positioning systems. This paper proposes a new Fast Water-filling algorithm Group Power Constraint (FWA-GPC) based Wi-Fi AP optimization approach for indoor positioning in which the power consumed by the AP optimization is significantly considered. This paper has three contributions. First, it is not restricted to conventional concept of one AP for one candidate AP location, but considered spare APs once the active APs break off. Second, it utilizes the concept of water-filling model from adaptive channel power allocation to calculate the number of APs for each candidate AP location by maximizing the location fingerprint discrimination. Third, it uses a fast version, namely Fast Water-filling algorithm, to search for the optimal solution efficiently. The experimental results conducted in two typical indoor Wi-Fi environments prove that the proposed FWA-GPC performs better than the conventional AP optimization approaches.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권8호
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• pp.2879-2899
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• 2021

The tone reservation (TR) scheme is an attractive method to reduce peak-to-average power ratio (PAPR) in the filter bank multicarrier with offset quadrature amplitude modulation (FBMC-OQAM) systems. However, the high PAPR of FBMC signal will severely degrades system performance. To address this issue, a cyclic shift based TR (CS-TR) scheme with embedding side information (SI) is proposed to reduce the PAPR of FBMC signals. At the transmitter, four candidate signals are first generated based on cyclic shift of the output of inverse discrete Fourier transform (IDFT), and the SI of the selected signal with minimum peak power among the four candidate signals is embedded in sparse symbols with quadrature phase-shift keying constellation. Then, the TR weighted by optimal scaling factor is employed to further reduce PAPR of the selected signal. At the receiver, a reliable SI detector is presented by determining the phase rotation of SI embedding symbols, and the transmitted data blocks can be correctly demodulated according to the detected SI. Simulation results show that the proposed scheme significantly outperforms the existing TR schemes in both PAPR reduction and bit error rate (BER) performances. In addition, the proposed scheme with detected SI can achieve the same BER performance compared to the one with perfect SI.