• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.507-510
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• 2004

Oblique ion-induced secondary electron emission coefficient(${\gamma}$) with low energy ..and work function ${\phi}_{\omega}$(${\theta}$ = 0 and ${\theta}$ = 20) of the MgO thin film in AC-PDPs has been measured by ${\gamma}$-FIB system. The MgO thin film has been deposited from sintered material under electron beam evaporation method. The energy of $He^+$ ions used has been ranged from 50eV to 150eV. Oblique ion beam has been chosen to be 10 degree, 20 degree and 30 degree. It is found that the higher secondary electron emission coefficient(${\gamma}$) has been achieved by the higher oblique ion beam up to inclination angle of 30 degree than the perpendicular incident ion beam.

• Korean Chemical Engineering Research
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• 제52권3호
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• pp.371-377
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• 2014

Characteristics of holdup and flow behavior of fluidized solid particles were investigated in a liquid-solid circulating fluidized bed ($0.102m{\times}3.5m$). Effects of liquid velocity ($U_L$), particle size ($d_P$) and solid circulation rate ($G_S$) on the solid holdup, overall particle rising velocity, slip velocity between liquid and particles and hydrodynamic energy dissipation rate in the riser were examined. The particle holdup increased with increasing $d_P$ or $G_S$ but decreased with increasing $U_L$. The overall particle rising velocity increased with increasing $U_L$ or $G_S$ but decreased with increasing $d_P$. The slip velocity increased with increasing $U_L$ or $d_P$ but did not change considerably with $G_S$. The energy dissipation rate, which was found to be closely related to the contacting frequency of micro eddies, increased with increasing $d_P$, $G_S$ or $U_L$. The solid particle holdup was well correlated with operating variables such as $U_L$, $d_P$ and $G_S$.

• Nuclear Engineering and Technology
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• 제49권6호
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• pp.1199-1210
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• 2017

A new in-line method for sampling neutrons emitted in (${\alpha}$,n) reactions based on alpha particle source information has been developed for continuous-energy Monte Carlo simulations. The new method uses a continuous-slowing-down model coupled with (${\alpha}$,n) cross section data to precompute the expected neutron yield over the alpha particle lifetime. This eliminates the complexity and computational cost associated with explicit charged particle transport. When combined with an integrated alpha particle decay source sampling capability, the proposed method provides an efficient and accurate method for sampling (${\alpha}$,n) neutrons based solely on nuclide inventories in the problem, with no additional user input required. Results from several example calculations show that the proposed method reproduces the (${\alpha}$,n) neutron yields and energy spectra from reference experiments and calculations.

• 한국입자에어로졸학회지
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• 제8권4호
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• pp.133-141
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• 2012

A new depth filter media was designed and samples of flat sheet as well as cartridge assembly were prepared and tested to evaluate the filtration performance and compare with the commercial product. The arrangement of the depth filter media layers is important to reach the optimal filtration parameters like filter pressure drop, particle collection efficiency and dust holding capacity. Initially, both flat sheet samples of new media and commercial product have been tested using standard test units. Tests with new depth filter media cartridges of various pleat count were conducted in order to find the optimal pleat count which would represent the lowest pressure drop. These tests give an insight on how the pleat count and the assembly configuration affect the performance of the depth filter media cartridge. By comparing the samples with a commercial product we could confirm relatively high filtration performance of the sample cartridge with pleat count 150 made of new depth filter media. The cartridge with the same pleat count exhibits better performance without the outer mesh.

• EDISON SW 활용 경진대회 논문집
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• 제5회(2016년)
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• pp.37-54
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• 2016

The methods for estimating the change of free energy in dissipative particle dynamics (DPD) are discussed on the basis of fluctuation theorems. Fluctuation theorems are tactics to evaluate free energy changes from non-equilibrium work distributions and have several forms, as proposed by Jarzynski, Crooks, and Bennett. The validity of these methods however, has been shown merely with the molecular dynamics or Langevin dynamics. In this study, the appropriate forms of fluctuation theorems for dissipative particle dynamics, which has similar structure to that of Langevin dynamics, are suggested using Liouville's theorem, and they are proved equivalent to original fluctuation theorems. Work distribution functions, which are probability distribution functions of works exerted on the system within the systematic change, are the basics of fluctuation theorems and their shapes are turned out to be dependent on the phase space trajectory of the change of the system. The reliability of Jarzynski and Crooks methods is highly dependent on the number of simulations to measure works and the shapes of the work distribution functions. Bennett method, however, can evaluate free energy changes even when Jarzynski and Crooks methods fail to do so.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제11권4호
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• pp.247-253
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• 2011

A sustainability of electricity supply has emerged as a critical issue for low carbon green growth in South Korea. Wind power is the fastest growing source of renewable energy. However, due to its own intermittency and volatility, the power supply generated from wind energy has variability in nature. Hence, accurate forecasting of wind speed and power plays a key role in the effective harvesting of wind energy and the integration of wind power into the current electric power grid. This paper presents a short-term wind speed prediction method based on support vector regression. Moreover, particle swarm optimization is adopted to find an optimum setting of hyper-parameters in support vector regression. An illustration is given by real-world data and the effect of model regularization by particle swarm optimization is discussed as well.

• Journal of Electrical Engineering and Technology
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• 제10권4호
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• pp.1780-1785
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• 2015

In this paper, the adaptive particle swarm optimization (APSO) algorithm is employed to design a gain-enhanced antenna with a reflector for energy harvesting. We placed the reflector below the main radiating element. Its back-radiated field is reflected and added to the forward radiated field, which could increase the antenna gain. We adopt the adaptive particle swarm optimization (APSO) algorithm, which improves the speed of convergence with a high frequency solver. The result shows that performance of the optimized design successfully satisfied the design goal of the frequency band, gain and axial ratio.

• 한국컴퓨터정보학회:학술대회논문집
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• 한국컴퓨터정보학회 2012년도 제46차 하계학술발표논문집 20권2호
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• pp.243-246
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• 2012

A new multi inner stage(MIS) cyclone was designed to remove the acidic gas and minute particles of harmful materials produced from electronic industry. To characterize gas flow in MIS cyclone, pressure and velocity distribution were calculated by means of computational fluid dynamics(CFD) commercial program. Also, the flow locus of particles and particle removal efficiency were analyzed by Lagrangian method. When outlet pressure condition was -1,000 Pa, the efficiency was the best in this study. Based on the CFD simulation result, the pressure loss and destruction removal efficiency was measured through MIS cyclone experiment.

• Korean Chemical Engineering Research
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• 제44권3호
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• pp.294-299
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• 2006

백-형상 필터의 투과율에 따른 필터 표면에서의 유동속도와 입자궤적을 수치해석 하였다. 필터의 투과율이 널리 사용되는 저급의 부직포 백필터의 투과율 이하의 조건에서는, 투과율에 따른 필터 표면에서의 유동속도와 입자궤적 분포의 변화가 아주 미미하였다. 필터의 바닥면 모서리와 출구 근처를 제외한 필터 표면에서 유선들과 반경 방향 유속들이 균일하게 분포하였다. 필터 표면으로의 입자궤적은 필터의 바닥면 모서리 근처에 더 조밀하게 분포하여 그 위치에 도달하는 입자의 수가 가장 많았고, 필터의 출구 쪽으로 향함에 따라 필터 표면에 위치하는 입자의 수는 점점 감소하는 추세를 보였다.

• 인터넷정보학회논문지
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• 제18권1호
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• pp.1-9
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• 2017

클라우드 컴퓨팅에서 바이오 영감 컴퓨팅 기술과 같은 연구들을 통해, 오프로딩 기법에서 새로운 차원의 솔루션이 개발되고 있다. 모바일 장비 사용의 증가 추세에 따라, 바이오 영감 기술은 모바일 클라우드 컴퓨팅의 발전에 기여하고 있다. 모바일 클라우드 컴퓨팅에서의 에너지효율적인 기법은 총 에너지 소비를 줄이기 위해 필요하지만, 지금까지의 연구는 태스크 분산을 위한 의사결정과정에서 에너지 소비에 관해 고려하지 않고 있다. 본 논문에서는 클라우드렛에서 데이터센터로의 오프로딩 전략으로 Particle Swarm Optimization (PSO) 방법을 제안하며, 이 과정에서 각 태스크는 입자(particle)로 표현된다. 입자의 수를 줄이기 위해 PSO를 적용하기 전에 K-means 클러스터링을 사용하여 수집한 태스크를 클라우드렛 상에서 분류하며, PSO 처리과정 중에는 모든 태스크를 대상으로 하지 않고 분류된 태스크에 따라 최적의 데이터 센터를 찾는다. 시뮬레이션 결과, 제안한 PSO기법이 처리 시간 관점에서는 전통적인 방법에 비해 조금 늦지만, 에너지 관점의 데이터 센터 선택에서는 우수함을 나타내었다.