• Journal of the Korean Chemical Society
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• v.34 no.2
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• pp.136-142
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• 1990

PMO (Pertubation Molecular Orbital) energies, ${\delta}E$, have been calculated from NBMO (Nonbonding Molecular Orbital) coefficient for some hydrocarbons by PMO method. It was found that the stabilization energies are correlated with activation energies, bond dissociation energies, and G-values observed from vapor phase radiolysis in the free radical reactions.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.2
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• pp.139-144
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• 2001

In this study, we have investigated the photoinduced birefringence of Ag plarized-photodoping in double-layer of Ag doped chalcognide thin films and dependence of polarization states in chalcogenide thin films. Also, we have investigated the polarization dependence of photoinduced birefringence and the anisotropy of absorption in an amorphous As$\sub$40/Ge$\sub$10/Se$\sub$15/S$\sub$35/ chalcogenide thin films using two 632.8nm He-Ne lasers, which have a smaller energy than the optical energy gap (E$\sub$OP/) of the film, i.e., an exposure of sub-bandgap light (hν$\sub$op/). The photoinduced phenomena of Ag polarized-photodooping increasing the linear dichroism(d), about 84% and birefringence(Δn), about 23%. It will offer lots of information for the photodoping mechanism and analysis of chalcogenide thin films.

• Journal of Mechanical Science and Technology
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• v.15 no.12
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• pp.1691-1698
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• 2001

In recent years, significant progress has been made in modeling turbulence behavior in plasma and its effect on transport. It has also been made in diagnostics for turbulence measurement; however, there is still a large gap between theoretical model and experimental measurements. Visualization of turbulence can improve the connection to theory and validation of the theoretical model. One method to visualize the flow structures in plasma is a laser Schlieren imaging technique. We have recently applied this technique and investigated the characteristics of a highly underexpanded pulsed plasma jet originating from an electrothermal capillary source. Measurements include temporally resolved laser Schlieren imaging of a precursor blast wave. Analysis on the trajectory of the precursor blast wave shows that it does not follow the scaling expected for a strong shock resulting from the instantaneous deposition of energy at a point. However, the shock velocity does scale as the square root of the deposited energy, in accordance with the point deposition approximation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.6
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• pp.845-852
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• 2001

The characteristics of evaporation cooling of single droplet on a heated surface were studied experimentally. The two kinds of heater modules were tested to measure cooling characteristics of metal surface (high conductivity) and Teflon surface (low-energy surface, low conductivity). The results showed that time averaged heat flux during droplet evaporation increased exponentially with initial surface temperatures of brass, copper and steel. The heat flux and evaporation time did not varied with metal conductivities. However, the temperature drop after the deposition of droplet was larger on Teflon than on the metals. Thus, the correlation of interface temperature between liquid droplet and metal surface was proposed as a function of the initial surface temperature of heating materials, which could be applied to both metal and non-metal ones.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.1
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• pp.9-15
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• 2013

This paper presents a uniform analytical model by energy method and Fourier series expansion to analyze detent force in uneven magnetic field for permanent magnet linear synchronous motor (PMLSM). The model reveals that detent force in long-primary type is mainly influenced by non-ideal distribution of permanent magnet magnetic motive force, while nounified air-gap permeance makes a great impact on detent force of short-primary type. Hence, magnetic field similarity of motor design techniques referring rotary counterpart are adopted. For long-primary type novel method of splitting edge magnets is proposed to reduce end effects force, and optimal widths of edge tooth in short-primary type also verify the effectiveness of magnetic field similarity. The experimental results validate finite element analysis results.

• Solar Energy
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• v.18 no.2
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• pp.115-121
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• 1998

In this study a channel cavity flow was performed. The channel has small size in the upper cavity region. At the gap is supplied by driven flow for Reynolds number. The experimental study was carried out in a channel cavity with square heat surface by visualization equipment with Mach-Zehnder interferometer and laser apparatus. Heat source was uniform heat flux($0.4W/cm^2,\;0.8W/cm^2,\;1.2W/cm^2$). When the bottom wall is heated, the tendency of natural convection flows are vigorous increasing heat flux.

• Progress in Superconductivity
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• v.11 no.2
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• pp.112-117
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• 2010

We examine phase transition of the spin density wave and $\pi$ phase shifted superconductivity in the Fe pnictide superconductors. The phase diagram is described in the plane of the temperature T and the doping x with the combination of Ginzburg-Landau expansion of the free energy near the multi-critical temperature $T_c$ and the self-consistent numerical iterations of the gap equations. The phase separation or coexistence is determined by computing the 4-th order terms of the free energy which is confirmed by the numerical calculations. We can show the phase coexistence when the spin density wave is incommensurate. And the first order phase transition is observed near the boundary between commensurate and incommensurate spin density wave.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.2
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• pp.232-242
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• 2015

Analytical study of surface recombination at the $Si/SiO_2$ interface is carried out in order to set the optimum surface conditions that result in minimum dark base current and maximum open circuit voltage in silicon solar cells. Recombination centers are assumed to form a continuum rather than to be at a single energy level in the energy gap. It is shown that the presence of a hump in the dark I-V characteristics of high efficiency PERL cells is due to the dark current transition from a high surface recombination regime at low voltage to a low surface recombination regime at high voltage. Successful fitting of reported dark I-V characteristics of a typical PERL cell is obtained with several possible combinations of surface parameters including equal electron and hole capture cross sections.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.631-632
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• 2015

최근 정부는 에너지관리의 중요성을 인식하여 수요관리 및 분산형발전시스템을 2015년도 에너지기본계획에 포함시켰다. 이에 따라 K-water는 K-water형 BEMS(Building Energy Management System) 구축을 위한 태양광 연계 ESS(Energy Storage System)를 검토했다. 그리고 BEMS를 시범적용하여 실제적인 분석과 문제점을 고찰하였다. 이를 통해 태양광발전을 연계한 ESS를 이용하여 K-water형 BEMS 모델의 방법론 및 실행방법을 알아보고자 한다.

• Journal of the Korean Society of Safety
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• v.15 no.4
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• pp.95-100
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• 2000

This study was performed in Hartmann type dust explosion apparatus in order to research the dust explosion characteristics of hydroxypropyl methyl cellulose(HPMC): minimum explosive limit, minimum ignition energy, limiting oxygen concentration, maximum explosion pressure, rate of pressure rise, etc. The samples of HPMC dust were distributed into 120-140 mesh, 170-230 mesh and 325 under, and the gap distance of the discharge electrode was setted up at 5mm. The experimental results were obtained as follows: (1) The minimum explosive limit for HPMC dust was founded at 180g/㎥. the minimum ignition energy at 9.8mJ and the limiting oxygen concentration at 12%. (2) The maximum explosion pressure of HPMC dust was $8.1kg/cm^2\;{\cdot}\;$abs at the concentration of $500g/m^3$ and the maximum rate of pressure rise was 203.98 bar/sec at the concentration of $480g/m^3$ for 325 under.