• 한국통신학회논문지
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• 제38B권4호
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• pp.240-246
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• 2013

이종 네트워크 환경에서 이종셀 간 간섭 제어를 위해 Almost Blank Subframes (ABS)이 제안 되었다. ABS에서는 서브프레임에 대한 자원 할당을 하지 않음으로써 동일 채널 간섭을 줄일 수 있다. 기존 연구에서는 ABS 기술의 성능 평가를 위한 수학적 모델링이 제안되지 않았다. 본 논문에서는 ABS 기술에 대한 수학적 모델을 제시하였다. 분석을 위한 가정에서 OFDMA 기반의 다중 반송파 (multi carrier) 시스템을 가정하였고, large-scale 페이딩을 가정하였다. 성능 평가로써 effective SINR에 대한 누적분포함수를 나타낸다. 시뮬레이션과 분석에 대한 결과 비교를 통해 수학적 모델에 대한 정확도를 보인다.

• 대한기계학회논문집A
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• 제28권6호
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• pp.685-692
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• 2004

A stochastic approach has been presented for superplastic deformation of Ti-6Al-4V alloy, and probability functions are used to model the heterogeneous phase distributions. The experimentally observed spatial correlation functions are developed, and microstructural evolutions together with superplastic deformation behavior have been investigated by means of the two-point and three-point probability functions. The results have shown that the probability varies approximately linearly with separation distance, and deformation enhanced probability changes during the process. The stress-strain behavior with the evolutions of probability function can be correctly predicted by the model. The finite element implementation using Monte Carlo simulation associated with reconstructed microstructures shows that better agreement with experimental data of failure strain on the test specimen.

• Interaction and multiscale mechanics
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• 제1권1호
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• pp.53-81
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• 2008

The theory of microlocal analysis of hyperbolic partial differential equations shows that the energy density associated to their high-frequency solutions satisfies transport equations, or radiative transfer equations for randomly heterogeneous materials with correlation lengths comparable to the (small) wavelength. The main limitation to the existing developments is the consideration of boundary or interface conditions for the energy and power flow densities. This paper deals with the high-frequency transport regime in coupled heterogeneous structures. An analytical model for the derivation of high-frequency power flow reflection/transmission coefficients at a beam or a plate junction is proposed. These results may be used in subsequent computations to solve numerically the transport equations for coupled systems, including interface conditions. Applications of this research concern the prediction of the transient response of slender structures impacted by acoustic or mechanical shocks.

• 대한기계학회논문집
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• 제10권1호
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• pp.164-169
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• 1986

본 연구에서는 구성원의 분포를 명확히 지시하는 체적 distribution을 기본 으로하고 Walsh 해석을 적용하므로서 혼합상태를 일련의 수치로 표시한다.이변환 과정에서 정보량의 분포가 변하는 현상을 고찰한 후 그 특징을 비균질체의 단순한 형태인 다공성고체의 체적변화거동에 응용하여, 현재 통용되는 구형모텔해석의 이론 적 근거를 밝힌다.

• 한국시뮬레이션학회논문지
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• 제8권4호
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• pp.9-24
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• 1999

We describe a heterogeneous simulation framework, so called DEVS-HLA, in which conventional simulation models and the DEVS (Discrete Event System Specification) models are interoperable. DEVS-HLA conceptually consists of three layers: model layer, DEVS BUS layer, and HLA (High Level Architecture) layer. The model layer has a collection of heterogeneous simulation models, such as DEVS, CSIM, SLAM, and so on, to represent various aspects of a complex system. The DEVS BUS layer provides a virtual software bus, DEVS BUS, so that such simulation models can communicate with each other. Finally, the HLA layer is employed as a communication infrastructure, which supports several good features for distributed simulation. The DEVS BUS has been implemented on the HLA/RTI (Run-Time Infrastructure) and a simple example of a flexible manufacturing system has been developed to validate the DEVS-HLA.

• 대한산업공학회지
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• 제31권3호
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• pp.228-239
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• 2005

In this paper, we propose a new conceptual HVRPCR(Heterogeneous Fleet Vehicle Routing Problem with Customer Restriction) model including additional restrictions that are consisted of loadage limit and possible visit number of demand post in HVRP. We propose HVRPCR algorithm using the heuristic in order to solve speedily because VRP is NP-Hard and need many solution time. The proposed model is simulated with changing demand post location, demand weight, loading and possible visit number limitation. Results of the computational experiment are provided along with some analysis like travel cost reduction rate.

• 한국CDE학회논문집
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• 제10권5호
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• pp.303-313
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• 2005

This paper proposes a generalized NURBS model, called Volumetric NURBS or VNURBS for representing volumetric objects with multiple attributes embedded in multidimensional space. This model provides a mathematical framework for modeling complex structure of heterogeneous objects and analyzing inside of objects to discover features that are directly inaccessible, for deeper understanding of complex field configurations. The defining procedure of VNURBS, which explains two directional extensions of NURBS, shows VNURBS is a generalized volume function not depending on the domain and its range dimensionality. And the recursive a1gorithm for VNURBS derivatives is described as a computational basis for efficient and robust volume modeling. In addition, the specialized versions of VNURBS demonstrate that VNURBS is applicable to various applications such as geometric modeling, volume rendering, and physical field modeling.

• 제어로봇시스템학회논문지
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• 제17권3호
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• pp.229-235
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• 2011

To make a robust object tracking and identifying system for an intelligent robot and/or home system, heterogeneous sensor fusion between visible ray system and infrared ray system is proposed. The proposed system separates the object by combining the ROI (Region of Interest) estimated from two different images based on a heterogeneous sensor that consolidates the ordinary CCD camera and the IR (Infrared) camera. Human's body and face are detected in both images by using different algorithms, such as histogram, optical-flow, skin-color model and Haar model. Also the pose of human body is estimated from the result of body detection in IR image by using PCA algorithm along with AdaBoost algorithm. Then, the results from each detection algorithm are fused to extract the best detection result. To verify the heterogeneous sensor fusion system, few experiments were done in various environments. From the experimental results, the system seems to have good tracking and identification performance regardless of the environmental changes. The application area of the proposed system is not limited to robot or home system but the surveillance system and military system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권6호
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• pp.2873-2892
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• 2019

Reducing the interference to the licensed mobile users and obtaining the energy efficiency are key issues in cognitive heterogeneous networks. A corresponding rate loss constraint is proposed to be used for the sensing-based spectrum sharing (SBSS) model in cognitive heterogeneous networks in this paper. Resource allocation optimization strategy is designed for the maximum energy efficiency under the proposed interference constraint together with average transmission power constraint. An efficiency algorithm is studied to maximize energy efficiency due to the nonconvex optimal problem. Furthermore, the relationship between the proposed protection criterion and the conventional interference constraint strategy under imperfect sensing condition for the SBSS model is also investigated, and we found that the conventional interference threshold can be regarded as the upper bound of the maximum rate loss that the primary user could tolerate. Simulation results have shown the effectiveness of the proposed protection criterion overcome the conventional interference power constraint.

• 한국통신학회논문지
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• 제32권10A호
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• pp.941-949
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• 2007

신규 무선 네트워크 기술의 발전은 현재의 단일 네트워크 위주의 구성을 가진 무선 서비스 사업자에 새로운 다중 네트워크 (Heterogeneous Network) 환경을 맞이하게 하였다. 또한 무선 통신 사용자 수는 계속적인 증가추세에 있고 사용자들이 원하는 서비스의 종류 또한 계속적으로 다양해지고 있으며 사용자가 기대하는 서비스의 질과 수준 역시 높아지고 있다. 이에 무선 서비스 사업자들은 사용자들의 높아진 서비스 품질을 만족시키고 새로운 형태의 서비스를 안정적으로 공급하며, 현재의 네트워크와 신규 네트워크의 조화로운 운용을 위해 새로운 형태의 운용 구조 (Operation Framework)를 필요로 한다. 본 논문에서는 네트워크간의 비용/효용에 대한 한계 비용 (Marginal Cost) 산정 기법을 도입하여 서비스에 따른 최적 네트워크 운용 기법에 대해 논술한다.