• 한국인터넷방송통신학회논문지
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• 제22권4호
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• pp.87-94
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• 2022

본 논문은 501 다트게임의 최소 다트 촉 투척 횟수인 9회에 대한 획득점수 조합을 찾는 연구를 수행하였다. 다트게임에서 한 번 투척으로 획득할 수 있는 최대 점수는 60점으로 60×8+21×1=501에 의거 60점을 8회, 21점을 1회 획득하면 9회 투척으로 퍼펙트 다트게임을 종료할 수 있다. 이를 9-다트 종료라 한다. 이와 같이 9회 투척으로 501점을 획득 가능한 점수의 조합에 관한 연구는 18개와 14개만 알려져 있으며, 전수탐색 알고리즘을 적용한 연구는 수행되지 않고 있다. 본 논문은 전형적인 전수탐색법인 분기한정법의 O(2ⁿ) 지수시간 수행 복잡도를 다항시간 복잡도로 단순화 시키는 방법으로 나눗셈 분기한정 알고리즘을 제안하였다. 제안된 방법은 레벨을 8로 한정시키고, 501/60의 몫 레벨로 점프하고 역추적으로 이전 단계에서의 가능한 점수 조합만을 탐색하는 방법을 적용하였다. 제안된 알고리즘으로 찾은 9회의 퍼펙트게임의 가능한 점수 조합은 90개(101개 경우)를 얻었다.

• 한국컴퓨터정보학회논문지
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• 제21권9호
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• pp.79-84
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• 2016

In this paper we consider the problem of finding the triplet (S,${\pi}$,f), where $S{\subseteq}V$, ${\pi}$ is a sequence of nodes in S and $f:V{\backslash}S{\rightarrow}S$ for a given complete graph G=(V,E). In particular, there exist two costs, $c^V_{uv}$ and $c^D_{uv}$ for $(u,v){\in}E$, and the cost of triplet (S,${\pi}$,f) is defined as $\sum_{i=1}^{{\mid}S{\mid}}c^V_{{\pi}(i){\pi}(i+1)}+2$ ${\sum_{u{\in}V{\backslash}S}c^D_{uf(u)}$. This problem is motivated by the integrated routing of the vehicle and drone for urban delivery services. Since a well-known NP-complete TSP (Traveling Salesman Problem) is a special case of our problem, we cannot expect to have any polynomial-time algorithm unless P=NP. Furthermore, for practical purposes, we may not rely on time-exhaustive enumeration method such as branch-and-bound and branch-and-cut. This paper suggests the simple heuristic which is motivated by the MST (minimum spanning tree)-based approximation algorithm and neighborhood search heuristic for TSP.

• 한국컴퓨터정보학회논문지
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• 제17권10호
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• pp.155-165
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• 2012

본 논문은 지금까지 해결하지 못한 NP-Hard 문제들 중의 하나인 외판원 문제를 해결할 수 있는 알고리즘을 제안한다. 제안된 알고리즘은 간선교환 방법을 적용한 발견적 알고리즘이다. 초기해를 구하는 전형적인 방법은 첫 번째 노드부터 가장 인접한 노드를 방문하여 외판원의 경로를 결정하는 방법이다. 본 논문에서는 각 노드의 최소 간선을 선택하여 선택된 간선들 중 최소값을 가진 노드부터 출발하는 Min-Min 방법과 최대값을 가진 노드부터 출발하는 Min-Max 방법을 적용하고 두 방법 중 최소 경로길이를 가진 방법을 초기해로 결정하였다. 초기해로부터 최적해를 구하는 과정은 기존의 2-간선 교환 방법 (2-opt)을 기본적으로 적용하고, 추가로 확장된 3-opt와 4-opt를 제안하였다. 이와 같은 방법을 7개의 실제 데이터들에 적용한 결과 지금까지 알려진 최적해를 빠르고 정확히 구하는데 성공하였다.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2010년도 하계학술대회
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• pp.9-11
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• 2010

Multiple-input multiple-output (MIMO) systems assisted by multi-relays with single antenna are considered. Signal transmission consists of two hops. In the first hop, the source node broadcasts the vector symbols to all relays, then all relays forward the received signals multiplied by each power gain to the destination simultaneously. Unlike the case of full cooperation between relays such as single relay with multiple antennas, in our case there is no closed form solution for optimal relay power gain with respect to minimum mean square error (MMSE). Thus we propose an alternative approach in which we use an approximation of the cost function based on rank-one matrix decomposition. As a cost function, we choose the trace of MSE matrix. We give several simulation results to validate that our proposed method obtains a negligible performance loss compared to optimal solution obtained by exhaustive search.

• 한국해양공학회지
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• 제24권6호
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• pp.109-113
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• 2010

We present the minimum weight optimum design of cross sectional for frame structures subject to natural frequency. The optimum design in this paper employ discrete and continuous design variables and Genetic Algorithms. In this paper, Genetic Algorithms is used in optimization process, and be used the method of Elitism and penalty parameters in order to improved fitness in the reproduction process. For 1-Bay 2-Story frame structure, in examples, continuous and discrete design variables are used, and W-section (No.1~No.64), from AISC, discrete data are used in discrete optimization. In this case, Exhaustive search are used for finding global optimum. Continuous variables are used for 1-Bay 7-Story frame structure. Two typical frame structure optimization examples are employed to demonstrate the availability of Genetic Algorithms for solving minimum weight optimum of frame structures with fundamental and multi frequency.

• 대한전자공학회논문지
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• 제24권6호
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• pp.1068-1073
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• 1987

Traditional circuit partitioning algorithm using the cluster development method, which is suitable for such applications as single chip floor planning or multiple layer PCB system placement, where the clusters are formed so that inter-cluster nets are localized within the I/O connector pins, may not be appropriate for the functiona block placement in truly 3-D electronic modules. 3-D hybrid IC is one such example where the inter-layer routing as well as the intra-layer routing can be maximally incorporated to reduce the overall circuit size, cooling requirements and to improve the speed performance. In this paper, we propose a new algorithm called MBE(Minimum Box Embedding) for the layer assignment of each functional block in 3-D hybrid IC design. The sequence of MBE is as follows` i) force-directed relaxation in 3-D space, ii) exhaustive search for the optimal orientation of the slicing plane and iii) layer assignment. The algorithm is first explaines for a 2-D reduced problem, and then extended for 3-D applications. An example result for a circuit consisting of 80 blocks has been shown.

• 말소리와 음성과학
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• 제3권3호
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• pp.91-98
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• 2011

In this paper, a multi-channel speech enhancement method using the linearly constrained minimum variance (LCMV) algorithm and a variable learning rate control is proposed. To control the learning rate for adaptive filters of the LCMV algorithm, the direction of arrival (DOA) is measured for each short-time input signal and the likelihood function of the target speech presence is estimated to control the filter learning rate. Using the likelihood measure, the learning rate is increased during the pure noise interval and decreased during the target speech interval. To optimize the parameter of the mapping function between the likelihood value and the corresponding learning rate, an exhaustive search is performed using the Bark's scale distortion (BSD) as the performance index. Experimental results show that the proposed algorithm outperforms the conventional LCMV with fixed learning rate in the BSD by around 1.5 dB.

• 국제초고층학회논문집
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• 제6권1호
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• pp.91-99
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• 2017

Special consideration should be given to differential column shortening during the design and construction of a tall building to mitigate the adverse effects caused by such shortening. The effects of the outrigger - which is conventionally used to increase the lateral stiffness of a tall building - on the differential shortening are investigated in this study. Three analysis models, a constant-section, constant-stress, and general model, are prepared, and the differential shortenings of these models with and without the outrigger are compared. The effects of connection time, sectional area, and location of the outrigger on the differential shortening are studied. The sectional area of the outrigger shows a non-linear relation in reducing the maximum differential shortening. The optimum locations of the single and dual outriggers are investigated by an exhaustive search method, and it is confirmed that a global optimum location exists. This study shows that the outrigger can be utilized to reduce the differential shortening between the interior core wall and the perimeter columns as well as to reduce the lateral displacements due to wind or earthquake loads.

• ETRI Journal
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• 제33권3호
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• pp.434-442
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• 2011

This paper presents a practical differential fault analysis method for the faulty Advanced Encryption Standard (AES) with a reduced round by means of a semi-invasive fault injection. To verify our proposal, we implement the AES software on the ATmega128 microcontroller as recommended in the standard document FIPS 197. We reduce the number of rounds using a laser beam injection in the experiment. To deduce the initial round key, we perform an exhaustive search for possible key bytes associated with faulty ciphertexts. Based on the simulation result, our proposal extracts the AES 128-bit secret key in less than 10 hours with 10 pairs of plaintext and faulty ciphertext.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권3호
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• pp.1174-1192
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• 2021

With the assistance of non-orthogonal multiple access (NOMA), the spectrum efficiency and the number of users in cloud radio access network (CRAN) can be greatly improved. In this paper, the system performance of NOMA-assisted CRAN is investigated. Specially, the outage probability (OP) and ergodic sum rate (ESR), are derived for performance evaluation of the system, respectively. Based on this, by minimizing the OP of the system, a suboptimal power allocation (PA) scheme with closed-form PA coefficients is proposed. Numerical simulations validate the accuracy of the theoretical results, where the derived OP has more accuracy than the existing one. Moreover, the developed PA scheme has superior performance over the conventional fixed PA scheme but has smaller performance loss than the optimal PA scheme using the exhaustive search method.