• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.340-350
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• 2021

This paper proposes a decision support model for USVs to improve the accuracy of collision avoidance decision-making. It is formed by Navigation Safety Domain (NSD) and domain-based Collision Risk Index (CRI), capable of determining the collision stage and risk between multiple ships. The NSD is composed of a warning domain and a forbidden domain, which is constructed under the constraints of COLREGs (International Regulations for Preventing Collisions at Sea). The proposed domain based CRI takes the radius of NSD in various encounter situations as threshold parameters. It is found that the value of collision risk in any directions can be calculated, including actual value and risk threshold. A catamaran USV and 6 given vessels are taken as study objects to validate the proposed model. It is found that the judgment of collision stage is accurate and the azimuth range of risk exists can be detected, hence the ships can take direct and effective collision avoidance measures. According to the relation between the actual value of CRI and risk threshold, the decision support rules are summarized, and the specific terms of COLREGs to be followed in each encounter situation are given.

• 한국경영과학회지
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• 제35권1호
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• pp.111-124
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• 2010

In the last decade, traveling purchaser problem (TPP) has received some attention of the researchers in the operational research area. TPP is a generalization of the well-known traveling salesman problem (TSP), which has many real-world applications such as purchasing the required raw materials for the manufacturing factories and the scheduling of a set of jobs over some machines, and many others. In this paper we suggest heterogeneous multiple traveling purchaser problem with budget constraint (HMTPP-B) which looks for several cycles starting at and ending to the depot and visiting a subset at a minimum traveling cost and such that the demand for each product is satisfied and the cost spent for purchasing the products does not exceed a given budget threshold. All the past studies of TPP are restricted on a single purchaser. Therefore we randomly generated some instances. CPLEX is used for getting optimal solutions in these experiments.

• 한국자동차공학회논문집
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• 제16권2호
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• pp.18-28
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• 2008

In inverse acoustic problem with nearfield sources, it is important to separate multiple acoustic sources and to measure the position of each target. This paper proposes a new algorithm by applying MUSIC(Multiple Signal Classification) to the outputs of discrete wavelet transformation with sub-band selection based on the entropy threshold, Some numerical experiments show that the proposed method can estimate the more precise positions than a conventional MUSIC algorithm under moderately correlated signal and relatively low signal-to-noise ratio case.

• 한국정보통신학회논문지
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• 제26권5호
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• pp.808-811
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• 2022

In this paper, a wide-range microphone system for lectures using dual 3D sensors is proposed. A previous work using a single sensor had lowering the detecting threshold to support wide-area. However it was found that an error occurred when lecturer wears clothes with low reflectivity or has small body size. When multiple sensors are used to expand the coverage it could be cause various problems. Each sensor could show different distance to the same target. We derive the rotation angle and and compensate for lecturing microphone system using sensors on the line. The proposed method shows a little improvement in performance by about 1dB compared to the previous works but the performance is uniform in all areas regardless of reflectivity.

• 인터넷정보학회논문지
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• 제23권3호
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• pp.21-33
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• 2022

본 논문은 기업비밀 노출로 초래될 손실을 현격히 줄일 안전 비밀조각 공유 시스템을 제안한다. 본 연구 시스템은 중앙서버 방식이 아닌 효율적 P2P 분산 시스템을 제안한다. 최근 비트코인 유통 시스템도 역시 P2P 분산 방식을 사용하고 있다. 본 연구는 기능이 단순하고 확장성이 높고 전송 효율적인 토렌트 P2P 분산 구조와 그 프로토콜을 사용하여 토렌트 파일조각 대신 임계 샤미르(Shamir) 비밀조각의 보안 유통을 설계한다. 본 연구는 임계 샤미르 비밀조각 공유기법 (Threshold Shamir Secret Sharing Scheme)을 시스템에 적용하고. 동시에 다중 협동장치의 서명기법을 사용하여 안전하고 강력한 다중인증방식의 사용자 인증을 수행한다. 안전한 비밀 데이터 유통도 공개키로 암호화 교환된 임시키의 대칭암호방식의 효율적 암호화로 전송을 한다. 짧은 유효기간의 임시키는 세션 동안 생성되고 세션 마감후 소멸하므로 키 노출에서 안전하다. 특별히 본 제안한 시스템의 특징은 임계 분산기법을 효율적 토렌트 P2P 분산 시스템에 구조적 변경없이 효과적으로 적용한다. 동시에 본 시스템은 효율적인 임시키 대칭암호방식으로 비밀파일 유통에 기밀성을 보장하고 임시키는 공개키 암호방식으로 안전하게 교환된다, 본 시스템은 외부 유출 기기도 사용자로 동적 등록이 가능하다. 이 확장성으로 기밀성과 인증성을 동적으로 등록된 사용자에게도 적용할 수 있다.

• 한국정보통신학회논문지
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• 제17권1호
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• pp.151-157
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• 2013

본 연구에서는 다중게이트 구조인 나노 와이어 n-채널 무접합(junctionless)와 반전모드(inversion mode) 다중게이트 MOSFET(Multiple-Gate MOSFET : MuGFET)의 PBTI에 의한 소자 특성 저하를 비교 분석하였다. PBTI에 의해서 무접합 및 반전모드 소자의 문턱전압이 증가하는 것으로 관측되었으며 무접합 소자의 문턱전압 변화가 반전모드 소자보다 작음을 알 수 있었다. 그러나 소자특성 저하 비율은 반전모드 소자가 무접합 소자보다 큰 것으로 관측되었다. 특성저하 활성화 에너지는 반전모드 소자가 무접합 소자보다 큰 것을 알 수 있었다. PBTI에 의한 소자 특성 저하가 무접합 소자보다 반전모드 소자가 더 심한 것을 분석하기 위하여 3차원 소자 시뮬레이션을 수행하였다. 같은 게이트 전압에서 전자의 농도는 같으나 수직방향의 전계는 반전모드 소자가 무접합 소자보다 큰 것을 알 수 있었다.

• Animal Bioscience
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• 제34권2호
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• pp.185-191
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• 2021

Objective: The objective of this study was to estimate the genetic parameters for worm resistance (WR) and associated characteristics, using the linear-threshold animal model via Bayesian inference in single- and multiple-trait analyses. Methods: Data were collected from a herd of Santa Inês breed sheep. All information was collected with animals submitted to natural contamination conditions. All data (number of eggs per gram of feces [FEC], Famacha score [FS], body condition score [BCS], and hematocrit [HCT]) were collected on the same day. The animals were weighed individually on the day after collection (after 12-h fasting). The WR trait was defined by the multivariate cluster analysis, using the FEC, HCT, BCS, and FS of material collected from naturally infected sheep of the Santa Inês breed. The variance components and genetic parameters for the WR, FEC, HCT, BCS, and FS traits were estimated using the Bayesian inference under the linear and threshold animal model. Results: A low magnitude was obtained for repeatability of worm-related traits. The mean values estimated for heritability were of low-to-high (0.05 to 0.88) magnitude. The FEC, HCT, BCS, FS, and body weight traits showed higher heritability (although low magnitude) in the multiple-trait model due to increased information about traits. All WR characters showed a significant genetic correlation, and heritability estimates ranged from low (0.44; single-trait model) to high (0.88; multiple-trait model). Conclusion: Therefore, we suggest that FS be included as a criterion of ovine genetic selection for endoparasite resistance using the trait defined by multivariate cluster analysis, as it will provide greater genetic gains when compared to any single trait. In addition, its measurement is easy and inexpensive, exhibiting greater heritability and repeatability and a high genetic correlation with the trait of resistance to worms.

• 한국정보통신학회논문지
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• 제26권9호
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• pp.1367-1373
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• 2022

본 논문에서는 셀프리 다중안테나 네트워크에서 하위 성능 사용자의 주파수 효율을 증대시키기 위한 전력 재할당 기법을 고려한다. AP(Access Point)는 사용자의 대규모 페이딩(large-scale fading) 채널 정보를 이용해 채널 세기에 비례하여 전력을 할당하여 전체 네트워크의 전력효율을 극대화한다. 다음으로 AP는 하위 성능 사용자의 주파수 효율을 증가시키기 위해 할당전력 중 임계비율 이상의 전력을 할당받은 사용자의 전력을 임계비율과 같아지도록 줄이고, 회수한 전력을 채널이 가장 나쁜 사용자에게 추가로 할당한다. 시뮬레이션을 통해 전력 재할당 기법을 통해 증가시킬 수 있는 하위 성능 사용자의 주파수 효율을 정량적으로 검증한다.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2007년도 추계학술대회 및 정기총회
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• pp.195-203
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• 2007

In this paper, an analytic model of sleep model operation in the IEEE 802.16e is investigated. A mobile subscribe. station (MSS) goes to sleep mode after negotiations with the base station (BS) and wakes up periodically for a short interval to check whether there is downlink traffic to it. If the arrival of traffic is notified, an MSS returns to wake mode. Otherwise, it again enters increased sleep interval which is double as the previous one. In order to consider the situation more practically, we propose the sleep mode starting threshold, during which MSS should await packets before it enters the sleep mode. By modifying the M/G/1 with multiple vacations model, energy consumption ratio(ECR) and average packet response time are calculated. Our analytic model provides potential guidance in determining the optimal parameters values such as sleep mode starting threshold, minimal sleep and maximal sleep window.

• Journal of Astronomy and Space Sciences
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• 제29권1호
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• pp.11-21
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• 2012

In this paper, the authors introduced a new approach to find the optimal collision avoidance maneuver considering multi threatening objects within short period, while satisfying constraints on the fuel limit and the acceptable collision probability. A preliminary effort in applying a genetic algorithm (GA) to those kinds of problems has also been demonstrated through a simulation study with a simple case problem and various fitness functions. And then, GA is applied to the complex case problem including multi-threatening objects. Two distinct collision avoidance maneuvers are dealt with: the first is in-track direction of collision avoidance maneuver. The second considers radial, in-track, cross-track direction maneuver. The results show that the first case violates the collision probability threshold, while the second case does not violate the threshold with satisfaction of all conditions. Various factors for analyzing and planning the optimal collision avoidance maneuver are also presented.