• ETRI Journal
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• 제39권2호
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• pp.255-263
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• 2017

This paper proposes a graph-theatrical approach to optimize spatial reuse by adopting a technique that quantizes the channel information into single bit sub-messages. First, we introduce an interference graph to model the network topology. Based on the interference graph, the computational requirements of the algorithm that computes the optimal spatial reuse factor of each user are reduced to quasilinear time complexity, ideal for practical implementation. We perform a resource allocation procedure that can maximize the efficiency of spatial reuse. The proposed spatial reuse scheme provides advantages in beamforming systems, where in the interference with neighbor nodes can be mitigated by using directional beams. Based on results of system level measurements performed to illustrate the physical interference from practical millimeter wave wireless links, we conclude that the potential of the proposed algorithm is both feasible and promising.

• 천문학회보
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• 제37권1호
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• pp.49.2-49.2
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• 2012

We present an investigation of X-ray hot gas halo in 12 isolated early-type galaxies from cross-matched sample of XMM-Newton and SDSS DR 7(0.025 < z < 0.08588 and Mr <-19.5). Isolated galaxies that the separation between galaxy and the closest neighbor is farther than its virial radius are not affected by environments, and their X-ray hot gas halo can be studied without contribution of intragalactic medium in all circumstances. We find that isolated galaxies in low density have correlation of $L_X-L_R$ and those in high density have no trend. This suggests that internal process is much effective in low density and environmental effects play important role of this relationship in high density. We also find the galaxies affected by environments in the large scale structure. In this paper, we report preliminary results for the study.

• 한국광학회지
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• 제5권2호
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• pp.204-211
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• 1994

팩시밀이나 복사기용으로 이용되는 micro lens array를 설계하였다. array 형태는 육각형배열이고 유효경은 0.160mm, 가장 가까운 이웃렌즈의 중심간 거리는 0.192mm로 하였다. 결상계의 횡배율은 1.0이다. single layer는 working distance가 10.55mm, double layer는 working distance가 7.90mm가 되었다. 각각의 성능은 ray fan을 계산하여 그 특성을 조사하였으며 서로 비교하였다.

• 화약ㆍ발파
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• 제18권1호
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• pp.59-70
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• 2000

The blasting work to construct a subway in seoul, korea have often cased increased neighbor＇s complaints because of ground vibration. In order to prevent the demage to the stucture it was necessary to predict the level of blasting induced vibration and to determine the maximum charge weigh per delay with an allowable vibration level. The effect of blasting pattem, rock strength and different explosive on the blast-induced ground vibration was studied to determine the maximum charage weight per delay within a given vibration level. The blasting vibration equation from over 100 test data was obtained, V= K(D/W(equation omitted), where the values for n and K are estimated to be 1.7 to 1.5 and 48 to 138 respectively.

• 디지털산업정보학회논문지
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• 제16권1호
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• pp.55-65
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• 2020

With the development of display hardware, image interpolation techniques have been used in various fields such as image zooming and medical imaging. Traditional image interpolation methods, such as bi-linear interpolation, bi-cubic interpolation and edge direction-based interpolation, perform interpolation in the spatial domain. Recently, interpolation techniques in the discrete cosine transform or wavelet domain are also proposed. Using these various existing interpolation methods and machine learning, we propose decision tree classification-based image interpolation methods. In other words, this paper is about the method of adaptively applying various existing interpolation methods, not the interpolation method itself. To obtain the decision model, we used Weka's J48 library with the C4.5 decision tree algorithm. The proposed method first constructs attribute set and select classes that means interpolation methods for classification model. And after training, interpolation is performed using different interpolation methods according to attributes characteristics. Simulation results show that the proposed method yields reasonable performance.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권5호
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• pp.2218-2244
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• 2016

In this paper, we propose a hybrid routing scheme that utilizes location information to support reliable data transmission in mobile ad hoc networks. The proposed scheme determines and maintains routing path by considering the directionality and connectivity of nodes using grid zones and information on neighbor nodes. In addition, it generates alternative paths with consideration for node distance and reliability. To show the superiority of the proposed routing scheme, a performance evaluation was conducted using simulations. The performance evaluation results show that the proposed scheme offers faster and more reliable data transmission than the existing routing schemes, and the number of messages decreases by approximately 31% compared to the existing schemes on average.

• E2M - 전기 전자와 첨단 소재
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• 제8권2호
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• pp.144-150
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• 1995

Ceramic filter using energy trapping effect is used bandpass filter at high frequency. In this paper, the resonant points of the symmetrical modes and antisymmetrical modes were theoretically analyed and synthesized these modes in order to know the filter characteristics. We simulated them using the computer and also fabricated the ceramic filter using PZT-4 piezoelectric plate made by Valpey Fisher Co., The 1.5[.mu.m] - thick platinum electrode were deposited on the ceramic plates with the various masks. The characteristics of the fabricated filters were measured using the spectrum analyzer. Experimental data were compared with the theoretical results. The maximum-pass frequencies coinsided exactly. The bandwidths of the fabricated filters were slightly different between theoretical and experimental results. We found that these phenomenon were caused by the stray capacitance between the two neighbor electrodes..

• 동력기계공학회지
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• 제14권5호
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• pp.48-55
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• 2010

When a large ship is advancing in waves, ship undergoes the hydroelastic response, which has influences on structural stability and the fatigue destruction etc. of the ship. Therefore, to predict accurate hydroelastic response, it is necessary to analyze hydroelastic response including fluid-structure interaction. In this research, a ship is divided into many hull elements to calculate the fluid forces and wave exciting forces on each elements using three-dimensional source distribution method. The calculated fluid forces and wave exciting forces are assigned to nodes of hull elements. The neighbor nodes are connected with elastic beam elements. We analyzed hydroelastic responses, and those are formulated by using finite element method. Particularly, to estimate the influence of forward speed on the hydroelastic responses, we use two different methods : Full Hull Rotation Method(FHRM) and Sectional Hull Rotation Method(SHRM).

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2000년도 추계학술발표논문집 (하)
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• pp.1373-1376
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• 2000

외판원 문제(Traveling Salesman Problem)는 주어진 n개의 도시들과 그 도시들간의 거리 비용이 주어졌을 매, 처음 출발도시에서부터 정확히 한 도시는 한 번씩만 방문하여 다시 출발도시로 돌아오면서 방문한 도시들을 연결하는 최소의 비용이 드는 경로를 찾는 문제로 최적해(optimal value)를 구하는 것은 전형적인 NP-완전 문제중의 하나이다[2,4,5, 8]. 따라서 이들의 수행시간을 줄이고자 하는 연구가 많이 진행된다. 본 논문에서는 외판원 문제의 최적의 해를 구하는데. 휴리스틱 알고리즘인 최근접 휴리스틱을 이용한다. 물론 수행 시간을 줄이고자 최적화 문제에서 좋은 성능을 보이는 유전 알고리즘 (Genetic Algorithm)으로 얻은 근사해(near optimal)를 초기 분기 함수로 사용하고, 근거리 통신망(Local Area Network)에 기반한 분산 처리 환경에서 여러 프로세서에 분산시켜 병렬성을 살린다.

• 한국컴퓨터정보학회논문지
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• 제22권5호
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• pp.81-88
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• 2017

Solar-powered wireless sensor nodes can use extra energy to obtain additional data to increase the precision. However, if the amount of data sensed is increased indiscriminately, the overhead of relay nodes may increase, and their energy may be exhausted. In this paper, we introduce a sensing and compression rate selection scheme to increase the amount of data obtained while preventing energy exhaustion. In this scheme, the neighbor nodes of the sink node determine the limit of data to be transmitted according to the allocated energy and their descendant nodes, and the other nodes select a compression algorithm appropriate to the allocated energy and the limitation of data to be transmitted. A simulation result verifies that the proposed scheme gathers more data with a lower number of blackout nodes than other schemes. We also found that it adapts better to changes in node density and the amount of energy harvested.