• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.3
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• pp.263-267
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• 2014

Super junction trench gate power MOSFETs have been receiving attention in terms of the trade-off between breakdown voltage and on-resistance. The vertical structure of super junction trench gate power MOSFETs allows the on-resistance to be reduced compared with conventional Trench Gate Power MOSFETs. The heat release of devices is also decreased with the reduction of on-resistance. In this paper, Lattice Temperature of two devices, Trench Gate Power MOSFET and Super junction trench gate power MOSFET, are compared in several temperature circumstance with the same Breakdown Voltage and Cell-pitch. The devices were designed by 100V Breakdown voltage and measured from 250K Lattice Temperature. We have tried to investigate how much temperature rise in the same condition. According as temperature gap between top of devices and bottom of devices, Super junction trench gate power MOSFET has a tendency to generate lower heat release than Trench Gate Power MOSFET. This means that Super junction trench gate power MOSFET is superior for wide-temperature range operation. When trench etching process is applied for making P-pillar region, trench angle factor is also important component. Depending on trench angle, characteristics of Super junction device are changed. In this paper, we focus temperature characteristic as changing trench angle factor. Consequently, Trench angle factor don't have a great effect on temperature change.

• Journal of Magnetics
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• v.6 no.1
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• pp.19-22
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• 2001

Change of magnetic properties in CoCrPt/Ti perpendicular media with varying CoCrPt film thickness has been studied. As the CoCrPt film thickness increases from 25 nm, the Ms (saturation magnetization) increases rapidly at first and then more gradually. This Ms behavior is associated primarily with the formation of an "amorphous-like"reacted layer created by intermixing of CoCrPt and Ti at the CoCrPt/Ti interface and secondarily with a change of the Cr segregation mode with varying CoCrPt film thickness. Magnetic domain structure distinctively changes with increasing CsCrPt magnetic layer (ML) thickness. Also the strength of exchange coupling measured from the slope in the demagnetizing region of the M-H loop changes with ML thickness. The expansion of lattice parameters a and c at smaller film thickness suggests that the Cr segregation mode may be connected with the residual stress of the films. Finally, the negative nucleation field (Hn) shows a unique behavior with the change of strength of the exchange interaction.teraction.

• Bulletin of the Korean Chemical Society
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• v.19 no.10
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• pp.1047-1054
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• 1998

We present the results of molecular dynamics simulations for three different systems of bilayers of long-chain alkyl thiol [S(CH2)15CH3] molecules on an solid-solid interface using the extended collapsed atom model for the chain-molecule. It is found that there exist two possible transitions: a continuous transition characterized by a change in molecular interaction between sites of different chain molecules with increasing area per molecule and a sudden transition from an ordered lattice-like state to a liquid-like state due to the lack of interactions between sites of chain molecules on different surfaces with increasing distance between two solid surfaces. The third system displays a smooth change in probability distribution characterized by the increment of gauche structure in the near-tail part of the chain with increasing area per molecule. The analyses of energetic results and chain conformation results demonstrate the characteristic change of chain structure of each system.

• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.772-784
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• 2024

The hexagonal nodal code RENUS has been enhanced to handle irregularly deformed hexagonal assemblies. The underlying RENUS methods involving triangle-based polynomial expansion nodal (T-PEN) and corner point balance (CPB) were extended in a way to use line and surface integrals of polynomials in a deformed hexagonal geometry. The nodal calculation is accelerated by the coarse mesh finite difference (CMFD) formulation extended to unstructured geometry. The accuracy of the unstructured nodal solution was evaluated for a group of 2D SFR core problems in which the assembly corner points are arbitrarily displaced. The RENUS results for the change in nuclear characteristics resulting from fuel deformation were compared with those of the reference McCARD Monte Carlo code. It turned out that the two solutions agree within 18 pcm in reactivity change and 0.46% in assembly power distribution change. These results demonstrate that the proposed unstructured nodal method can accurately model heterogeneous thermal expansion in hexagonal fueled cores.

• Journal of Magnetics
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• v.2 no.1
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• pp.28-33
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• 1997

Very large in electrical resistivity by several orders of magnitude is obtained when an external magnetic field is applied to the colossal magnetoresistnace (CMR) materials such as La-Ca-Mn-O. The magnetoresistance is strongly temperature-dependent, and exhibits a sharp peak below room temperature, which can be shifted by adjusting the composition or processing parameters. The control of lattice geometry or strain, e.g., by chemical substitution, epitaxial growth or post-deposition anneal of thin films appears to be crucial in obtaining the CMR properties. The orders of magnitude change in electrical resistivity could be useful for various magnetic and electric device applications. .

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.698-699
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• 2011

This paper analyzes the switching surge in distribution system with photovoltaic (PV) generation system. The change of overvoltage by PV generation system is analyzed using lattice diagram. To verify the analysis results, the distribution system with PV generation system is modeled using EMTP-RV and the various simulations are performed.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.4
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• pp.159-163
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• 2010

Co-(0.5 mol%) and Ce-(0~0.3 mol%) doped cubic zirconia ($ZrO_2:Y_2O_3$=64:36 mol%) single crystals grown by a skull melting method were heat-treated in $N_2$ at $1200^{\circ}C$ for 3 hrs. The brown-colored as-grown single crystals were changed into either green or blue color after the heat treatment. Before and after the heat treatment, the YSZ (yttriastabilized zirconia) single crystals were cut for wafer form (${\phi}7mm{\times}t2mm$) and round brilliant cut ($\phi$ 12 mm). The optical and structural properties were examined by UV-VIS spectrophotometer and X-ray diffraction. Absorption by $Ce^{3+}(^2F_{5/2},\;_{7/2}(4f){\rightarrow}^2T_g(5d^1)),\;Co^{2+}(^4A_2(^4F){\rightarrow}^4T_1(^4F)$ or $^4T_1(^4P))$ and $Co^{3+}$, change of ionization energy and lattice parameter were confirmed.

• Nuclear Engineering and Technology
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• v.49 no.1
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• pp.1-5
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• 2017

The heavy water zero power reactor (HWZPR), which is a critical assembly with a maximum power of 100 W, can be used in different lattice pitches. The last change of core configuration was from a lattice pitch of 18-20 cm. Based on regulations, prior to the first operation of the reactor, a new core was simulated with MCNP (Monte Carlo N-Particle)-4C and WIMS (Winfrith Improved Multigroup Scheme)-CITATON codes. To investigate the criticality of this core, the effective multiplication factor ($K_{eff}$) versus heavy water level, and the critical water level were calculated. Then, for safety considerations, the reactivity worth of $D_2O$, the reactivity worth of safety and control rods, and temperature reactivity coefficients for the fuel and the moderator, were calculated. The results show that the relevant criteria in the safety analysis report were satisfied in the new core. Therefore, with the permission of the reactor safety committee, the first criticality operation was conducted, and important physical parameters were measured experimentally. The results were compared with the corresponding values in the original core.

• Journal of the Korean Magnetic Resonance Society
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• v.18 no.1
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• pp.15-23
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• 2014

The structural properties and relaxation processes of $MCsSO_4$ (M = Na, K, or Rb) crystals were investigated by measuring the NMR spectra and spin-lattice relaxation rates $1/T_1$ of their $^{23}Na$, $^{39}K$, $^{87}Rb$, and $^{133}Cs$ nuclei. According to the NMR spectra, the $MCsSO_4$ crystals contain two crystallographically inequivalent sites each for the M and Cs ions. Further, the relaxation rates of all these nuclei do not change significantly over the investigated temperature range, indicating that no phase transitions occur in these crystals in this range. The variations in the $1/T_1$ values of the $^{23}Na$, $^{39}K$, $^{87}Rb$, and $^{133}Cs$ nuclei in these three crystals with increasing temperature are approximately proportional to $T^2$, indicating that Raman processes may be responsible for the relaxation. Therefore, for nuclear quadrupole relaxation of the $^{23}Na$, $^{39}K$, $^{87}Rb$, and $^{133}Cs$ nuclei, Raman processes with n = 2 are more effective than direct processes.

• Journal of the Korea Fashion and Costume Design Association
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• v.17 no.4
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• pp.91-100
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• 2015

The purpose of this study is to analyze the style of check dresses shown in collections from 2011 to 2014 and to extract main expressional words for the development of semantic differential scales of visual images according to the change in silhouette of block check dresses. The results of this study are as follows: 1) 120 check dresses shown in collections were composed of 57 straight silhouette dresses, 38 fitted silhouette dresses, 23 hourglass silhouette dresses, 1 barrel silhouette dress, and 1 atypical silhouette dress. And check pattern mostly used in the current collections a square pattern of block check, tartan check that is a Scotch traditional lattice pattern, a small lattice pattern of gingham check, over check that other check patterns are arranged on check pattern, star-shaped hound tooth check, glen check mixing small pattern and big pattern. The visual image for check dress differs according to changes in the check pattern and silhouette of the dress. 2) Main expressional words of visual images for block check dresses differ greatly depending on the silhouette of dresses. The visual images are ranked in the order of 'graphic', 'simple', 'hard', 'modern' for straight silhouette of block check dresses. The words of 'lively', 'girlish', 'feminine', 'cute' are ranked for hourglass silhouette of block check dresses. And the words of 'confident', 'feminine', 'modern' are marked down for fitted silhouette of block check dresses.