• Journal of the Korean Magnetics Society
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• v.11 no.4
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• pp.151-156
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• 2001

Recently many studies on manganese oxides Ln$_{1-x}$A$_{x}$MnO$_3$(Ln=La, Pr, Nd lanthannide; A=Ca, Sr, Ba, Pb +2 ions) reported CMR properties. CMR have been also found in chalcogenide spinels. We have investigated that Ni ion substitutions for Fe ion have effects on CMR properties in chacogenide spinels Ni$_{x}$Fe$_{1-x}$Cr$_2$S$_4$. It was found that with increasing Ni concentration Jahn-Teller distortion was strengthened and Curie temperature T$_{c}$ was increased. CMR properties could be explained with Jahnl-Teller effect, half-metallic electronic structure, and the alignment of magnetic domain due to the strong magnetic field, which is different in that double exchange interactions dominate CMR properties in manganese oxides.

• Korean Journal of Materials Research
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• v.5 no.1
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• pp.96-103
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• 1995

This art~cle reports on the formation of T - Gate with O.1$\mu$m foot and 0.4$\mu$m head width at PMMA/P( MMA/MAA) resist structure using a 30KV electron beam lithography system. From the result of Monte Carlo simulation on PMMA/P( MMA/MAA)/GaAs, we obtain the dissipation energy ratio of forwardscattered electron and backscattered electron within 0.1$\mu$m scattering radius is 19.5 : 1 0.1$\mu$m T - gate has been formed with 30KV gaussian electron beam at a 440$\mu C/\textrm{cm}^2$ dosage. The gamma value of PMMA and P(MMA/MAA) at MIBK : IPA=l : 1 developer was 2.3. The overlay accuracy(3$\sigma$) from mix-andmatch of optical stepper and Ekeam lithography system for fabricating HEMT device is accomplished below 0.1$\mu$m.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.253-260
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• 2005

Recently, the storms which hit Korean Peninsula are getting bigger, and the damages from the storms are wide spreaded. Thus, and approach with disaster prebention to offshore area and/or opened island area is neccessary. The existing wave design parameter was calculated with linear regular wave models inputting deep water design wave or wind sources. so it wasn't able to deal with wind-induced waves, interactions with waves, and redistribution of wave energy simultaneously. In this study, we made numerical simulation with SWAN(Simulation Waves Nearshore) Model which can consider development of waves and winds and their interference. The result from this model shows much different with those from existing model's. so the result from this study, especially in this modeling area, could be used for harbor design and coastal disaster prevention field in the future.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.10a
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• pp.149-150
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• 2013

Recently, various types of perforated breakwaters are being constructed for protecting offshore storm waves. In general, perforated breakwaters have wave chambers with perforated walls at seaside. Purposes of the wave chambers are to reduce wave reflections and maximum wave forces acting on the breakwater. Impact wave forces due to wave breaking can attack to the perforated wall directly, so the effects have to be considered in the design of the perforated wall carefully. Using resonance channels for wave energy dissipation, a new concept perforated breakwater is proposed, which is free from impact loads. Numerical simulation was made for wave reflection characteristics of the breakwater with respect to major design parameters. Numerical analysis was carried out using the Galerkin's FE model based on the linear potential theory considering energy dissipation on the perforated plate. Variations of wave reflection was investigated according to perforated ratios of perforated plate.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.1
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• pp.85-92
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• 2017

Recently, electric propulsion systems are used for unmanned surface vehicle, fish finder boat, etc. Some of these propulsion systems can be constructed of two electric motors and propellers for advanced impellent force. In this case, the speed difference generated between two propellers, namely, the synchronous error has a bad influence on the energy efficiency and course error. In this study, a synchronous control system is designed to restrain synchronous error caused by disturbance and mismatched dynamic characteristics. The control system is composed of the reference model, pre-filters, speed controllers, and synchronous controllers. The reference model is used for calculating the decoupled synchronous error and control input for each propulsion system. The pre-filters and speed controllers are designed in order that the propulsion system may follow the reference signal without overshoot and input saturation. And the synchronous controllers are designed from the viewpoint of stable and quick synchronization through root locus mothed approach. Finally, the simulation results show that the designed control system is effective for the disturbance.

• Journal of Life Science
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• v.17 no.8 s.88
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• pp.1100-1103
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• 2007

In proton therapy, the Bragg peak is spread out by modulating or degrading the energy of the particles to cover a well-defined target volume at a given depth. Proton transfer plays a key role in a variety of biological, the origin of the elements, tests of the standard model along with applications in medicine, industry and chemical phenomena such as water autoionization, fast proton diffusion, acid-base neutralization. We have studied the radiolysis of various natural resources and have evaluated the antioxidant activity of radiolysis products by proton beam. The most of antioxidant activities of natural resources were decreased with increasing proton fluence. Proton beam induced antioxidant activities both in 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) assay and 2,2'-azinobis(3-ethylbenzot hialozinesulfonic acid) cation radical $(ABTS^{.+})$ assay by a dose dependent fashion.

• Applied Chemistry for Engineering
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• v.5 no.3
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• pp.509-516
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• 1994

Liquid phase hydrogenation come into use for the removal process of unsaturated hydrocarbon such as croton aldehyde. The croton aldehyde is generated in a very small amount as by-product in the ethanol production, and it is converted into n-butanol through hydrogenation. Liquid phase hydrogenation is low energy consumption process as compared with gas phase hydrogenation. The nickel catalyst is selected with respect to the economic aspect such as durability and cost. The analysis of the conversion were performed by method of the PMT(permangante time) test. The PMT was sharply decreased as the initial concentrations of croton aldehyde in the ethanol solution were increased. The hydrogenation of croton aldehyde to n-butanol was carried out in sequence after the saturation of the carbon-carbon double bond. The formation of both butyraldehyde and n-butanol followed zero order kinetics. Within expermental conditions the PMT gets longer as reaction temperature goes higer and as LHSV becomes slower, while the reaction pressure has almost no relation with PMT.

• Journal of Power System Engineering
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• v.20 no.6
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• pp.99-104
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• 2016

In this study, we researched the energy load according to the change of the inner window area ratio, the distance of the air gap and the azimuth of the curtain wall building, which installed the multistory double-skin facade(DSF). and we compared the results with the no double-skin facade situation as follows. With the DSF, it is better than other case, when the window area ratio is 40% and the air gap is 1.2m on the west, south-45-west, south-45-east and east. And it's best when the window area ratio is 40% and the air gap is 0.4m on the south. And on the east or south-45-east, the window area ratio is 40% and the air gap is 1.2m is better than other case with the DSF. On south, it is best when the window area ratio is 100% without DSF. On the south-45-west or west, it is best when the window area ratio is 40% without the DSF.

• Journal of the Korean Vacuum Society
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• v.6 no.2
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• pp.159-164
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• 1997

We have studied initial oxidation of the alkali metal(AM)/Si(111) surface using X-ray photoelectron spectroscopy(XPS) and reflection high energy electron diffraction(RHEED) at room temperature(RT) and high temperature(HT)(300~50$0^{\circ}C$). The oxidation of the Si(111)7$\times$7 surface was promoted by the adsorption of 1 momolayer(ML) AM, whereas no promotion occurred for submonolayer(<0.5 ML) adsorbed Si(111)7$\times$7 surface at RT. O Is core level spectra were measured with increasing oxygen exposure. It was found that the oxygen adsorbed on the Si(111)7$\times$7-AM surface have two different bond configuration, Si-O and Am-O, respectively. From these results, we discussed the role of AM-O bonding in the promoted oxidation. At HT(300~50$0^{\circ}C$), the AM-adsorbed surface became very inactive with the structural transformation to the 3$\times$1-AM. We present the results of the oxidation of the Si(111)3$\times$1-AM(Na, K, Cs) surface.

• Korean Journal of Food Science and Technology
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• v.30 no.6
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• pp.1279-1284
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• 1998

This study was designed to investigate the reasonable roasting condition of chicory. Extraction and surface color development of roasted chicory were significantly influenced by roasting temperature and time, and they were increased with increasing time, and roasting at $170^{\circ}C$ showed the highest browning color development. Soluble solid contents was not affected by roasting temperature and time. Roasting for 10min at $150^{\circ}C$ exhibited the highest sensory score, at which the free sugar composition of the extract was 0.87% xylose, 0.62% fructose and 0.84% sucrose. A total of 17 volatile components were identified by GC/MSD from the dried and roasted chicories. Aldehyde, ketone and pyrazine compounds were found to be major volatile flavor components in chicory roots. It was concluded that the results of this work will be useful to determine the optimum conditions for roasting of chicory roots.