• 한국멀티미디어학회논문지
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• 제20권6호
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• pp.893-910
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• 2017

In this paper, we propose a simple online multiple object (human) tracking method, LKDeep (Lucas-Kanade feature and Detection based Simple Online Multiple Object Tracker), which can run in fast online enough on CPU core only with acceptable tracking performance for embedded surveillance purpose. The proposed LKDeep is a pragmatic hybrid approach which tracks multiple objects (humans) mainly based on LK features but is compensated by detection on periodic times or on necessity times. Compared to other state-of-the-art multiple object tracking methods based on 'Tracking-By-Detection (TBD)' approach, the proposed LKDeep is faster since it does not have to detect object on every frame and it utilizes simple association rule, but it shows a good object tracking performance. Through experiments in comparison with other multiple object tracking (MOT) methods using the public DPM detector among online state-of-the-art MOT methods reported in MOT challenge [1], it is shown that the proposed simple online MOT method, LKDeep runs faster but with good tracking performance for surveillance purpose. It is further observed through single object tracking (SOT) visual tracker benchmark experiment [2] that LKDeep with an optimized deep learning detector can run in online fast with comparable tracking performance to other state-of-the-art SOT methods.

• 한국전기전자재료학회논문지
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• 제18권7호
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• pp.589-593
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• 2005

The electronic states of ZnO doped with Al, Ga and In, which belong to III family elements in periodic table, were calculated using the density functional theory. In this study, the calculation was performed by two Programs; the discrete variational Xa (DV-Xa) method, which is a sort of molecular orbital full potential method; Vienna Ab-initio Simulation Package (VASP), which is a sort of pseudo potential method. The fundamental mixed orbital structure in each energy level near the Fermi level was investigated with simple model using DV-Xa. The optimized crystal structures calculated by VASP were compared to the measured structures. The density of state and the energy levels of dopant elements were shown and discussed in association with properties.

• International Journal of Naval Architecture and Ocean Engineering
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• 제11권2호
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• pp.923-938
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• 2019

Surge motion of top-end platform induced by periodic wave makes marine flexible riser encounter equivalent sheared-oscillatory flow, under which the Vortex-induced Vibration (VIV) response will be more complicated than pure sheared flow or oscillatory flow cases. Based on a time domain force-decomposition model, the VIV response characteristics under sheared-oscillatory flows are investigated numerically in this paper. Firstly, the adopted numerical model is validated well against laboratory experiments under sheared flow and oscillatory flow. Then, 20 sheared-oscillatory flow cases with different oscillation periods and top maximum current velocities are designed and simulated. Under long and short oscillation period cases, the structural response presents several similar features owing to the instantaneous sheared flow profile at each moment, but it also has some different patterns because of the differently varying flow field. Finally, the effects and essential mechanism of oscillation period and top maximum current velocity on VIV response are discussed systematically.

• ETRI Journal
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• 제36권4호
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• pp.654-661
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• 2014

We develop accurate finite-difference time-domain (FDTD) modeling of polymer bulk heterojunction solar cells containing Ag nanoparticles between the hole-transporting layer and the transparent conducting oxide-coated glass substrate in the wavelength range of 300 nm to 800 nm. The Drude dispersion modeling technique is used to model the frequency dispersion behavior of Ag nanoparticles, the hole-transporting layer, and indium tin oxide. The perfectly matched layer boundary condition is used for the top and bottom regions of the computational domain, and the periodic boundary condition is used for the lateral regions of the same domain. The developed FDTD modeling is employed to investigate the effect of geometrical parameters of Ag nanospheres on electromagnetic fields in devices. Although negative plasmonic effects are observed in the considered device, absorption enhancement can be achieved when favorable geometrical parameters are obtained.

• 한국정보통신학회논문지
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• 제3권1호
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• pp.209-221
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• 1999

실시간 스케줄가능성 분석을 위한 여러 가지 방법들이 제안되었지만, 이들은 프로세스의 모든 상태공간을 추적하거나 고정 우선 순위 스케줄링 방법을 사용하기 때문에 시간 및 공간에 대한 복잡성의 증가를 야기한다. 따라서 상태공간의 수를 줄임으로써 보다 빠른 시간에 스케줄가능성을 판단하는 방법이 필요하다. 본 논문에서는 프로세스 대수의 전이규칙을 이용하여 번역시간에 결정될 수 있는 프로세스의 최소 수행시간, 주기, 마감시간, 동기화 시간을 고려하여 실시간 프로세스가 마감시간을 지키는가를 판단하는 개선된 알고리즘을 제안 및 구현한다. 구현 결과를 통하여 모든 상태 공간을 검색하지 않고도 스케줄가능성을 판단하는 효과적인 성능을 보였다.

• Journal of Electrical Engineering and Technology
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• 제6권5호
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• pp.697-705
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• 2011

In this paper, a closed-loop system constructed with a linear plant and nonlinearity in the feedback connection is considered to argue against its planar orbital stability. Through a state space approach, a main result that presents a sufficient stability criterion of the limit cycle predicted by solving the harmonic balance equation is given. Preliminarily, the harmonic balance of the nonlinear feedback loop is assumed to have a solution that determines the characteristics of the limit cycle. Using a state-space approach, the nonlinear loop equation is reformulated into a linear perturbed model through the introduction of a residual operator. By considering a series of transformations, such as a modified eigenstructure decomposition, periodic averaging, change of variables, and coordinate transformation, the stability of the limit cycle can be simply tested via a scalar function and matrix. Finally, the stability criterion is addressed by constructing a composite Lyapunov function of the transformed system.

• Journal of Yeungnam Medical Science
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• 제16권2호
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• pp.228-236
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• 1999

저자들은 한국인 갑상선 기능 항진증에 동반된 주기성마비의 임상적 특정을 알아보고자 1986년 3월부터 1996년 3월까지 영남대학교 의과대학 부속 병원 내과에 내원하여 갑상선기능 항진증을 진단받은 환자 997명 중 주기성마비를 보였던 19명을 관찰하여 다음과 같은 결과를 얻었다. 대상환자 997명 중 남자는 296명, 여자는 701명이었고, 이들 중 주기성마비는 19명에서 발생하여 빈도는 1.9%이었다. 성별분포는 남자에서 6%(18/296), 여자에서는 0.2%(1/701)의 발생률을 보였다. 또한 마비가 시작된 연령은 19 - 55세로서 평균 35세이었다. 마비는 주로 하지(14/19, 73.6%)에 일어났고, 상하지 모두에서 발생한 경우도 3명(15.7%)이었으나, 상지만 발생된 경우는 없었다. 그리고 원위부보다 근위부에 더 심한 마비를 보였다. 총 19명의 대상환자들 중 6명(38.5%)의 환자에서는 선행 유발요인을 찾을 수 없었으나 나머지 환자들에서는 과식(5/19, 26.3%), 음주(3/19, 15.7%), 육체적 과로(4/19, 21%), 감염(1/19, 5.2%) 등이 유발요인으로 작용하였다. 19명의 환자의 마비발작시 혈중 칼륨 수치는 1.5-6.1(평균 $3.2{\pm}1.2$ mEq/L)으로 다양하게 나타났다. 환자들은 칼륨투여와 동시에 모두 PTU와 베타차단제로 치료받았으며, 갑상선 기능이 정상화되면서부터 재발한 환자는 2명이었고, 나머지 17명에서는 정상 갑상선 기능하에서 마비가 생기지 않았다. 이상에서 갑상선 기능항진증 환자에서 발생하는 주기성마비는 갑상선 기능항진증에 의해서 유발되는 것이 확실하나, 정상 갑상선기능하에서도 주기성 마비가 재발하고, 갑상선 기능항진증의 2% 정도에서만 주기성 마비가 발생한다는 것은 근세포막전위를 유지하는 생화학적 경로 이상 이외에 유전적 감수성 등과 같은 다른 기전들도 갑상선 중독성 주기성마비에 관여할 것으로 생각된다. 또한, 마비발작이 어떻게 시작되는지, 마비발작은 어떠한 기전으로 저절로 호전이 되는지, 왜 젊은 아시아인에서 많이 발생하는지에 대해서는 알려진 바가 없어, 향후 이에 대해서도 많은 연구가 필요할 것으로 생각된다.

• 한국컴퓨터정보학회논문지
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• 제19권3호
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• pp.55-62
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• 2014

본 논문에서는 기존의 주기적 링크 상태 갱신 기법의 장점인 링크 상태 갱신(Link State Update : LSU) 메시지 수 제어 기능과 적응형 링크 상태 갱신 기법의 장점인 라우팅 성능을 가지는 하이브리드 링크 상태 갱신 기법(Hybrid LSU)을 제안한다. Hybrid LSU 기법은 네트워크 트래픽 정보를 기반으로 임계값이 변하는 적응형 링크 상태 갱신 기법을 가지고 있으며 플로우의 요구 대역폭 정보를 통해 LSU 메시지 전송 중요도를 판단하고 단위 시간 당 업데이트 비율에 따라 LSU 메시지 전송 여부를 판단하여 LSU 메시지 수를 제어할 수 있는 메커니즘을 포함한다. 성능 평가를 위해 기존에 제시된 다양한 LSU 기법과 본 논문에서 제안하는 Hybrid LSU 기법을 MCI 네트워크상에서 라우팅 블록율과 링크 당 평균 LSU 메시지의 개수 등을 성능 평가 항목으로 시뮬레이션 하였다. 그 결과 트래픽 부하가 높아질수록 라우팅 블록율 성능은 그대로 유지하면서 평균 LSU 메시지의 개수를 기존의 적응적 링크 상태 갱신 기법에 비해 10% 정도 줄일 수 있었고 이를 통해 제안하는 기법의 우수성을 확인하였다.

• 대한기계학회논문집B
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• 제26권2호
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• pp.227-237
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• 2002

A numerical technique for simulating the aggregation of charged particles was presented with a Brownian dynamic simulation in the free molecular regime. The Langevin equation was used for tracking each particle making up an aggregate. A periodic boundary condition was used for calculation of the aggregation process in each cell with 500 primary particles of 16 nm in diameter. We considered the thermal force and the electrostatic force for the calculation of the particle motion. The electrostatic force on a particle in the simulation cell was considered as a sum of electrostatic forces from other particles in the original cell and its replicate cells. We assumed that the electric charges accumulated on an aggregate were located on its center of mass, and aggregates were only charged with pre-charged primary particles. The morphological shape of aggregates was described in terms of the fractal dimension. In the simulation, the fractal dimension for the uncharged aggregate was D$\_$f/ = 1.761. The fractal dimension changed slightly for the various amounts of bipolar charge. However, in case of unipolar charge, the fractal dimension decreased from 1.641 to 1.537 with the increase of the average number of charges on the particles from 0.2 to 0.3 in initial states. In the bipolar charge state, the average sizes of aggregates were larger than that of the uncharged state in the early and middle stages of aggregation process, but were almost the same as the case of the uncharged state in the final stage. On the other hand, in the unipolar charge state, the average size of aggregates and the dispersion of particle volume decreased with the increasing of the charge quantities.

• Geomechanics and Engineering
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• 제28권6호
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• pp.613-624
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• 2022

A study of the evolution of overburden fractures under the solid-fluid coupling state was conducted based on the geological and mining characteristics of the coal seam depth, weak strata cementation, and high-intensity mining in the mining areas of West China. These mining characteristics are key to achieving water conservation during mining or establishing groundwater reservoirs in coal mines. Based on the engineering background of the Daliuta Coal Mine, a non-hydrophilic simulation material suitable for simulating the weakly cemented rock masses in this area was developed, and a physical simulation test was carried out using a water-sand gushing test system. The study explored the spatial distribution and dynamic evolution of the fractured zone in the mining overburden under the coupling of stress and seepage. The experimental results show that the mining overburden can be vertically divided into the overall migration zone, the fracture extension zone and the collapse zone; additionally, in the horizontal direction, the mining overburden can be divided into the primary fracture zone, periodic fracture zone, and stop-fracture zone. The scope of groundwater flow in the overburden gradually expands with the mining of coal seams. When a stable water inrush channel is formed, other areas no longer generate new channels, and the unstable water inrush channels gradually close. Finally, the primary fracture area becomes the main water inrush channel for coal mines. The numerical simulation results indicate that the overlying rock breaking above the middle of the mined-out area allows the formation of the water-conducting channel. The water body will flow into the fracture extension zone with the shortest path, resulting in the occurrence of water bursting accidents in the mining face. The experimental research results provide a theoretical basis for the implementation of water conservation mining or the establishment of groundwater reservoirs in western mining areas, and this theoretical basis has considerable application and promotion value.