• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.3 s.357
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• pp.43-51
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• 2007

OneNAND flash combines the advantages of NAND and NOR flash, and has become an alternative to the former. But the advanced features of OneNAND flash are not utilized effectively in demand paging systems designed for NAND flash. We propose delayed dual buffering, a demand paging system which fully exploits the random-access I/O interface and dual page buffers of OneNAND flash demand paging system. It effectively reduces the time of page transfer from the OneNAND page buffer to the main memory. On average, it achieves and 28.5% reduction in execution time and 4.4% reduction in paging system energy consumption.

• Bulletin of the Korean Chemical Society
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• v.31 no.8
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• pp.2185-2189
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• 2010

Closely arranged CdSe and Zn doped CdSe vertical nanorod bundles were grown directly on FTO coated glass by using electrodeposition method. Structural analysis by XRD showed the hexagonal phase without any precipitates related to Zn. FE-SEM image showed end capped vertically aligned nanorods arranged closely. From the UV-vis transmittance spectra, band gap energy was found to vary between 1.94 and 1.98 eV due to the incorporation of Zn. Solar cell parameters were obtained by assembling photoelectrochemical cells using CdSe and CdSe:Zn photoanodes, Pt cathode and polysulfide (1M $Na_2S$ + 1M S + 1M NaOH) electrolyte. The efficiency was found to increase from 0.16 to 0.22 upon Zn doping. Electrochemical impedance spectra (EIS) indicate that the charge-transfer resistance on the FTO/CdSe/polysulfide interface was greater than on FTO/CdSe:Zn/polysulfide. Cyclic voltammetry results also indicate that the FTO/CdSe:Zn/polysulfide showed higher activity towards polysulfide redox reaction than that of FTO/CdSe/polysulfide.

• Korean Chemical Engineering Research
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• v.54 no.6
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• pp.830-837
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• 2016

In order to improve the compressive strength of graphite foams (GFms), mesophase pitch (MP) was stabilized in air atmosphere and then fluorinated at different conditions. The Fluorine/Carbon (F/C) in surface-chemical contents of fluorinated MP has range of 23.75%~61.48% according to the different fluorine partial pressure. The compressive strengths of GFms prepared from fluorinated MP were increased in proportion to the apparent densities. The compressive strength of the GFm produced from MP with 35.93% of F/C (%) showed maximum value in $2.93{\pm}0.06MPa$, which was increased up to 27.95% than that of the GFm prepared from un-fluorinated MP. This result was attributed that the interface bonding between of MPs due to fluorine functional groups with high surface energy helped to improve compressive strength of the GFm.

• 한국HCI학회:학술대회논문집
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• 2008.02b
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• pp.405-410
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• 2008

There is always a rhythm in our language and speech. As soon as we speech out, even just simple words and voice we make are edited as various emotions and information. Through this process we succeed or fail in our communication, and it becomes a fun communication or a monotonous delivery. Even with the same music, impression of the play can be different according to each musician' s emotion and their understanding. We 'play' our language in the same way as that. However, I think, people are used to the variety, which is, in fact, the variation of a set format covered with hollow variety. People might have been living loosing or limiting their own creative way to express themselves by that hollow variety. SPACIAL POEM started from this point. This is a new type of 'real-time visual interaction' expressing our own creative narrative as real-time visual by playing a musical instrument which is an emotional human behavior. Producing many kinds of sound by playing musical instruments is the same behavior with which we express our emotions through. There are sensors on each hole on the surface of the musical instrument. When you play it, sensors recognize that you have covered the holes. All sensors are connected to a keyboard, which means your playing behavior becomes a typing action on the keyboard. And I programmed the visual of your words to spread out in a virtual 3D space when you play the musical instrument. The behavior when you blow the instrument, to make sounds, changes into the energy that makes you walk ahead continuously in a virtual space. I used a microphone sensor for this. After all by playing musical instrument, we get back the emotion we forgot so far, and my voice is expressed with my own visual language in virtual space.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.6
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• pp.307-315
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• 2003

This paper proposes a novel simulation method of WPGS (Wind Power Generation System). The rotation speed control method of turbine under variable wind speed using the pitch control is proposed. Moreover, when wind speed exceeds the cut-out wind speed, the turbine will be stopped by controlling pitch angle to 90$^{\circ}$, otherwise it will be controlled to steady-state operation. For the purpose of effective simulation, the SWRW (Simulation method for WPGS using Real Weather condition) is used for the utility interactive WPGS simulation in this paper, in which those of three topics for the WPGS simulation: user-friendly method, applicability to grid-connection and the utilization of the real weather conditions, are satisfied. It is impossible to consider the real weather conditions in the WPGS simulation using the EMTP type of simulators and PSPICE, etc. External parameter of the real weather conditions is necessary to ensure the simulation accuracy. The simulation of the WPGS using the real weather conditions including components modeling of wind turbine system is achieved by introducing the interface method of a non-linear external parameter and FORTRAN using PSCAD/EMTDC in this paper. The simulation of long-term, short-term, over cut-out and under cut-out wind speeds will be peformed by the proposed simulation method effectively. The efficiency of wind power generator, power converter and flow of energy are analyzed by wind speed of the long-term simulation. The generator output and current supplied into utility can be obtained by the short-term simulation. Finally, transient-state of the WPGS can be analyzed by the simulation results of over cut-out and under cut-out wind speeds, respectively.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.156-157
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• 2005

Gas hydrate is ice-like crystalline lattice, formed at appropriate temperature and pressure, in which gas molecules are trapped. It is worldwide popular interesting subject as a potential energy. In korea, a seismic survey for gas hydrate have performed over the East sea by the KIGAM since 1997. In this paper, we had conducted numerical and physical modeling experiments for seismic properties on gas hydrate with field data which had been acquired over the East sea in 1998. We used a finite difference seismic method with staggered grid for 2-D elastic wave equation to generate synthetic seismograms from multi-channel surface seismic survey, OBC(Ocean Bottom Cable) and VSP(Vertical Seismic Profiling). We developed the seismic physical modeling system which is simulated in the deep sea conditions and acquired the physical model data to the various source-receiver geometry. We carried out seismic complex analysis with the obtained data. In numerical and physical modeling data, we observed the phase reversal phenomenon of reflection wave at interface between the gas hydrate and free gas. In seismic physical modeling, seismic properties of the modeling material agree with the seismic velocity estimated from the travel time of reflection events. We could easily find out AVO(Amplitude Versus Offset) in the reflection strength profile through seismic complex analysis.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.2
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• pp.95-101
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• 2017

In this study, we derived theoretical equations for the zigzag movement of a leading vehicle, which is the most frequent behavior in train accidents, by using a simplified spring-mass model for the rolling stock. In order to solve the equations of motion, we applied the Runge-Kutta method, which is the typical numerical analysis method used for differential equations. Furthermore, the lateral displacement of the wheel-set at the wheel-rail interface was estimated using kinetic energy. In order to verify the derived equations, we compared the theoretical and simulated results under various collision conditions. The maximum relative deviations of the lateral displacements were 0.8 [%] ~ 4.7 [%] in light collisions and 0.6 [%] ~ 5.1 [%] under derailment conditions. When an accident is simulated, these theoretical equations can be used to predict the overall behavior and obtain the offset of the body-to-body link as the initial perturbation.

• Journal of the Korean Chemical Society
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• v.24 no.4
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• pp.295-301
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• 1980

The electrical conductivity of solid electrolyte $RbAg_4I_5$ single crystal was studied at various temperatures. The four-probe method was used in measuring the conductance with an ac signal imposed on the specimen. The ionic conductivity was $0.284 ohm^{-1} cm^{-1}\;at\;25^{\circ}C$, and the activation energy for $Ag^+$ ion migration was calulated to be 1.70 kcal/mole. These values agree well with those reported for polycrystalline samples. Reactions at $Ag/RbAg_4I_5$ interface were studied by cyclic voltammetry with a silver reference electrode. It was found that silver ion is reversibly reduced at silver surfaces below zero volt, and iodide was oxidized above +0.67 volt.The anodic current arising from the oxidation of the electrode was small in magnitude initially over a wide range of potential, but, after silver was cathodically deposited on the electrode, reversing the potential sweep to the anodic direction resulted in a sharp peak of anodic current.

• Journal of the Korea Society of Computer and Information
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• v.16 no.12
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• pp.167-174
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• 2011

This paper described the estimation methods of CO2 emission of vehicles. The important of energy and environment has emerged in the world, and the field of vehicle's development as well. CO2 was particularly the object of emission-regulation that caused of global warming. There are performance comparison methods by driving mileage, International Panel on Climate Change (IPCC) and chemical equation for the combustion of Octane. We took the measurement by getting data through OBD-II port from vehicle covered 5 km on road. We got the diagnosis information, specific mileage and fuel consumption in this experiment. We are able to expect similar CO2 emission by the methods in the normal speed driving. Also, we can make more realistic approach of CO2 emission by the method of estimation by IPCC and chemical equation for the combustion of Octane in rapid acceleration driving.

• Journal of the Korean Magnetics Society
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• v.6 no.4
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• pp.235-241
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• 1996

Co/Pd and Co/Pt multilayered thin films for perpendicular magnetic recording media were fabricated by sput¬tering method and the effects of the sputtering pressure during the formation of Pd or Pt underlayers on the magnetization behavior and coercivity of the multilayers were investigated. It was found that the coercivity of Co/Pd multilayers was strongly dependent on the sputtering pressure of underlayer and could be enhanced to a large extent merely by increasing the sputtering pressure of underlayer, while in case of Co/Pt films, the degree of coercivity enhancement by controlling the sputtering pressure of underlayer was almost negligible. Coercivity variation of Co/Pd and Co/Pt multilayers with the underlayer material and deposition pressure of underlayer could be well explained in terms of the interface roughness of multilayer films induced by underlayer topology, which could also be correlated to the change of perpendicular anisotropy energy and magnetic reversal feature with the sputtering pressure of underlayer. Kerr rotation angle was hardly affected by the preparation conditions of underlayers.