• 로봇학회논문지
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• 제3권3호
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• pp.226-236
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• 2008

In this paper, control software architecture is designed to enable a heterogeneous multiple humanoid robot demonstration executing tasks cooperating with each other. In the heterogeneous humanoid robot team, one large humanoid robot and two small humanoid robots are included. For the efficient and reliable information sharing between many software components for humanoid control, sensing and planning, CORBA based software framework is applied. The humanoid tasks are given in terms of finite state diagram based human-robot interface, which is interpreted into the XML based languages defining the details of the humanoid mission. A state transition is triggered based on the event which is described in terms of conditions on the sensor measurements such as robot locations and the external vision system. In the demonstration of the heterogeneous humanoid team, the task of multiple humanoid cleaning the table is given to the humanoid robots and successfully executed based on the given state diagram.

• Current Photovoltaic Research
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• 제3권2호
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• pp.61-64
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• 2015

In solar industry, numerous researchers reported about cold spray method among various electrode formation technic, but there are no known a bonding mechanism of metal powder. In this study, a cross-section of copper electrode formed by cold spray method was observed and heterogeneous phase between silicon substrate and copper electrode was analyzed using morphology observation technic. SEM and TEM analysis were performed to analyze a crystallinity and distribution shape of heterogeneous copper phase. Molecular dynamics simulation was performed to calculate glass transition temperature of copper metal. In the result, amorphous copper phase was observed near interface between silicon substrate and metal electrode. The results of the molecular dynamics simulation show that an amorphous copper phase could be formed at a temperature below the melting point of copper because cold spraying resulted in a lower glass transition temperature.

• Journal of Information Processing Systems
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• 제13권3호
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• pp.500-517
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• 2017

In this paper, an improved zone-based routing protocol for heterogeneous wireless sensor networks is proposed. The proposed protocol has fixed the sized zone according to the distance from the base station and used a dynamic clustering technique for advanced nodes to select a cluster head with maximum residual energy to transmit the data. In addition, we select an optimal route with minimum energy consumption for normal nodes and conserve energy by state transition throughout data transmission. Simulation results indicated that the proposed protocol performed better than the other algorithm by reducing energy consumption and providing a longer network lifetime and better throughput of data packets.

• 한국정보통신학회논문지
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• 제4권3호
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• pp.549-555
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• 2000

본 논문에서는 n개의 버스트 입력 트래픽을 처리하는 이산 시간 큐잉 모형을 분석하기 위한 근사 계산 알고리즘을 제안한다. 입력되는 각각의 버스트 트래픽은 IBP(Interrupted Bernoulli Process)로 모형화된다. 이 알고리즘은 n 개의 입력 프로세스를 하나의 상태 변수로 표시하여 n 개의 입력 프로세스로 표현된 마코프 체인(Markov Chain)의 확률 전이 상태를 단순화한다. 이렇게 단순화된 하나의 상태 변수를 이용하여 큐잉모형의 상태 전이를 표현하고 이를 완전 수치 계산에 의해 해를 구한다. 이러한 절차를 통해 구한 큐 길이, 대기 시간 분포를 시뮬레이션에 의해 구한 값과 비교하여 알고리즘의 타당성을 검증한다.

• Computers and Concrete
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• 제7권5호
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• pp.469-482
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• 2010

This paper investigates the concrete permeability through a numerical and statistical approach. Concrete is considered as a random heterogeneous composite of three phases: aggregates, interfacial transition zones (ITZ) and matrix. The paper begins with some classical bound and estimate theories applied to concrete permeability and the influence of ITZ on these bound and estimate values is discussed. Numerical samples for permeability analysis are established through random aggregate structure (RAS) scheme, each numerical sample containing randomly distributed aggregates coated with ITZ and dispersed in a homogeneous matrix. The volumetric fraction of aggregates is fixed and the size distribution of aggregates observes Fuller's curve. Then finite element method is used to solve the steady permeation problem on 2D numerical samples and the overall permeability is deduced from flux-pressure relation. The impact of ITZ on overall permeability is analyzed in terms of ITZ width and contrast ratio between ITZ and matrix permeabilities. Hereafter, 3680 samples are generated for 23 sample sizes and 4 contrast ratios, and statistical analysis is performed on the permeability dispersion in terms of sample size and ITZ characteristics. By sample theory, the size of representative volume element (RVE) for permeability is then quantified considering sample realization number and expected error. Concluding remarks are provided for the impact of ITZ on concrete permeability and its statistical characteristics.

• Bulletin of the Korean Chemical Society
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• 제33권3호
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• pp.980-986
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• 2012

In this paper we develop a minimalist model of single molecule spectroscopy in a dynamic environment. Our model is based upon a lattice system consisting of a probe molecule embedded in an Ising-model like environment. We assume that the probe molecule interacts with the Ising spins via a dipole-dipole potential, and calculate free energy curves and lineshapes of the system. To investigate fluctuation behavior of the system we exploit the metadynamics sampling method. In particular, using the method, we calculate the free energy curve of magnetization of the lattice and that of the transition energy of the probe molecule. Furthermore, we compare efficiencies of three different sampling methods used; unbiased, umbrella, and metadynamics sampling methods. Finally, we explore the lineshape behavior of the probe molecule as the system undergoes a phase transition from a sub-critical and to a super-critical temperature. We show that the transition energy of a probe molecule is broadly distributed due to the heterogeneous, local environments.

• 동력기계공학회지
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• 제17권5호
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• pp.44-51
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• 2013

This paper proposes and analyzes recycling of optical phonons emitted by nonradiative decay, which is a major thermal management concern for high-power light emitting diodes (LED), by introducing an integrated, heterogeneous barrier cooling layer. The cooling is proportional to the number of phonons absorbed per electron overcoming the potential barrier, while the multi-phonon absorption rate is inversely proportional to this number. We address the theoretical treatment of photon-electron-phonon interaction/transport kinetics for optimal number of phonons (i.e., barrier height). We consider a GaN/InGaN LED with a metal/AlGaAs/GaAs/metal potential barrier and discuss the energy conversion rates. We find that significant amount of heat can be recycled by the barrier transition cooling layer.

• 한국결정성장학회지
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• 제8권1호
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• pp.187-192
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• 1998

일반적으로 재료의 응고조직은 주상정과 등축정 수지상 영역으로 이루어지는데 이것은 제품의 기계적, 물리적 성질과 밀접한 관계를 가지기 때문에 주상정-등축정 천이에 관한 많은 이론적 연구가 행하여지고 있다. 본 연구에서는 J.D. Hunt에 의하여 일방향응고시 주상정앞에서의 핵생성과 결정성장조건을 이용하여 구하여진 해석학적 주상정-등축정 조건식을 바탕으로 응고속도에 따라 변하는 분배계수와 액상선기울기를 적용하여 수정된 조건식을 구하였다. 그리고 Al-Cu합금에 대하여 응고변수인 핵생성수, 핵생성온도, 합금의 조성, 응고속도 온도기울기에 따른 천이현상의 변화를 조사하였다.

• 전기학회논문지
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• 제65권9호
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• pp.1504-1510
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• 2016

The aim of this study is to improve properties both glass transition temperature($T_g$) and coefficient of thermal expansion(CTE) using epoxy/micro-nano alumina composites with adding glycerol diglycidyl ether (GDE:1,2,3,5g). This paper deals with the effects of GDE addition for epoxy/micro alumina contents (40, 50, 60wt%)+surface modified nano alumina(1_phr) composites. 20 kinds specimen were prepared with containing micro, nano alumina and GDE as a micro composites(10, 20, 30, 40, 50, 60, 70wt%) or a nano/micro alumina composites(1phr/40, 50, 60wt%). Average particle size of nano and micro alumina used were 30nm and $1{\sim}2{\mu}m$, respectively. The micro alumina used were alpha phase with Heterogeneous and nano alumina were gamma phase particles of spherical shape. The glass transition temperature and coefficients of thermal expansion was evaluated by DSC and TMA. The glass transition temperature decreased and coefficients of thermal expansion become smaller with filled contents of epoxy/micro alumina composites. On the other hand, $T_g$ and CTE as GDE addition variation(1,2,3,5g) of epoxy/micro-nano alumina composites decreased and increased respectively.

• East Asian Economic Review
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• 제21권3호
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• pp.201-230
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• 2017

This paper studies the long-run behavior of relative price dispersion among cities in Korea with a special emphasis on heterogeneous transitional patterns of price level dynamics. Formal statistical tests indicate considerable evidence for rejecting the null of relative price level convergence among the majority of cities over the sample period of 1985-2015. The analysis of gravity model suggests that the effect of transportation costs on intercity price level differentials is limited, while other socioeconomic factors, such as income, input factor prices, demographic structure, and housing price growth, play key roles in accounting for persistent regional price level disparities. Individual price levels are found to be better explained by a multiple-component model, and the deviations from PPP may be attributed to distinct stochastic common trends that are characterized by income and demographic structure.