• The Transactions of the Korean Institute of Electrical Engineers P
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• v.51 no.1
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• pp.10-17
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• 2002

Due to the development of information communication field, the interest of the SMPS(Switched Mode Power Supply) is increased. The size and weight of SMPS are decided by inductor, capacitor and transformer. Thus, the low loss converter which is operated in high speed switching is required. The resonant FB DC-DC converter is able to operate in high speed switching and apply to high power field because the switching loss is low. In this thesis, it is proposed to control strategy for constant output power of resonant FB DC-DC converter in variable input voltage. The proposed control system is a digital I-PD type control and apply to phase-shift resonant type controller. The output voltage tracks reference without steady state error in variable input voltage. The validity of proposed control strategy is verified from results of simulation and experiment.

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.623-628
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• 2009

There is an increasing demand for efficient high power/weight auxiliary power supplies for use on high speed traction application. Many new conversion techniques have been proposed to reduce the voltage and current stress of switching components, and the switching losses in the traditional pulse width modulation(PWM) converter. Especially, the phase shift full bridge zero voltage switching PWM techniques are thought most desirable for many applications because this topology permits all switching devices to operate under zero voltage switching(ZVS) by using circuit parasitic components such as leakage inductance of high frequency transformer and power device junction capacitance. The proposed topology is found to have higher efficiency than conventional soft-switching converter. Also it is easily applicable to phase shift full bridge converter by applying an energy recovery snubber consisted of fast recovery diodes and capacitors.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.895-897
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• 2008

ZnO films were fabricated using rf-magnetron sputter deposition process with different $N_2$ ambient. N-content in N-doped ZnO films was less than 1%. The wavelength of the highest intensity PL peak of N-doped ZnO was shifted to higher wavelength with increasing $N_2$ flow rate in the deposition ambient. These results indicated that the optical property of ZnO was significantly affected by the defect level created by doping with a very small amount of N.

• Electrical & Electronic Materials
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• v.8 no.1
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• pp.48-55
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• 1995

A surface acoustic wave (SAW) sensor for the detection of odorants has been constructed by depositing various phospholipids and fatty acids onto the surface of the SAW device. The characteristics of a SAW device operating at 310 MHz deposited with silicon monoxide were analyzed. Menthone, amylacetate, acetoin, and other organic gases show different affinities to the coated lipids. An explanation is given for different odorant affinities based on the monolayer properties of phospholipids. The identification of odorants depending on the tkpe of lipid used for coating is discussed in terms of the similarity of their normalized resonant frequency shift patterns. Using a number of different lipid-coated SAW devices, odorants can be identified by a computerized pattern recognition algorithm.

• JSTS:Journal of Semiconductor Technology and Science
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• v.5 no.2
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• pp.136-147
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• 2005

A theoretical design evaluation based on a hydrodynamic transport simulation of strained Si-SiGe on insulator (SSOI) type nMOSFETs is reported. Although, the net performance improvement is quite limited by the short channel effects, simulation results clearly show that the strained Si-SiGe type nMOSFETs are well-suited for gate lengths down to 20 nm. Simulation results show that the improvement in the transconductance with decreasing gate length is limited by the long-range Coulomb scattering. An influence of lateral and vertical diffusion of shallow dopants in the source/drain extension regions on the device performance (i.e., threshold voltage shift, subthreshold slope, current drivability and transconductance) is quantitatively assessed. An optimum layer thickness ($t_{si}$ of 5 and $t_{sg}$ of 10 nm) with shallow Junction depth (5-10 nm) and controlled lateral diffusion with steep doping gradient is needed to realize the sub-50 nm gate strained Si-SiGe type nMOSFETs.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.385-388
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• 2009

We have investigated the effect of the device structure on the performance of polycrystalline ZnO TFT and amorphous AZTO TFT with top gate and bottom gate structure. While the mobility of both TFTs showed relatively similar value in a top and bottom gate structure, bias stability was quite different depending on the device structure. Top gate TFT showed much less Vth shift under positive bias stress compared to that of bottom gate TFT. We attributed this different behavior to the defects formation on the gate insulator induced by energetic bombardment during the active layer deposition in a bottom gate TFT. We suggest the top gate oxide TFT would show more stable behavior under the Vgs bias.

• Progress in Superconductivity
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• v.1 no.1
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• pp.31-35
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• 1999

We have fabricated and tested a simple circuit of the rapid single-flux-quantum(RSFQ) four-stage shift register using a single layer high-$T_c$ superconducting (HTS) $YBa_2Cu_3O_{7-x}$ (YBCO) thin film structure with 9 step-edge Josephson junctions. The circuit includes two read superconducting quantum interference devices(SQUID) and four stages. To establish a robust HTS RSFQ device fabrication process, we have focussed on the reproducible process of sharp and straight step-edge formation as well as the ratio of film thickness to step height, t/h. The spread of step-edge junction parameters was measured from each 13 junctions with t/h=1/3, 1/2, and 2/3 at various temperatures. We have demonstrated the simplified operation of the shift register at 65 K.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.3
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• pp.63-69
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• 1998

In this paper, a new input method is proposed to improve shift-invariant property of a photorefractive correlator andwe implemented real-time optical pattern recognition system using it. In the conventional photorefractive correlator, it is vrey difficult to satisfy the Bragg condition in the pattern recognition process. So, correlation peak is decreased heavily for the shift of input image. If a liquid crystal television(LCTV) without an anlyzer is used as input device, we can get the correlation result regardless of shift of input image because beam path is not changed during storage of holographic filter and correlation process. Also recording time of a holographic matched filter in photorefractive crystal is reduced and the correlation peak is increased because incident beam on the LCTV is transmitted completely. Therefore total optical efficiency is improved. We compared and analyzed the correlation results of proposed photorefractive correlator by computer simulation and optical experiment. We used a BaTiO$_{3}$ single crystal which has high diffraction efficiency in optical experiment.

• Journal of Drive and Control
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• v.14 no.4
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• pp.29-36
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• 2017

Electronic control technologies that have long been developed for passenger cars spread to construction equipment and agricultural vehicles because of its outstanding performance achieved by embedded software. Especially, system program of transmission control unit (TCU) plays a crucial role for the superb shift quality, driving performance and fuel efficiency, etc. Since the control algorithm is embedded in software that is rarely analyzed, development of such a TCU cannot be conducted by conventional reverse engineering. Transmission simulator is a kind of electronic device that simulates the electric signals including driver operation command and output of various sensors installed in transmission. Standalone TCU can be run in normal operation mode with the signals provided by transmission simulator. In this research, transmission simulator for the tracked vehicle TCU is developed for the analysis of shift control algorithm from the experiments with standalone TCU. It was confirmed that shift experimental data for the simulator setup conditions can be used for the analysis of control algorithms on proportional solenoid valves and shift map.

• Journal of Internet Computing and Services
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• v.24 no.2
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• pp.57-66
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• 2023

Currently, a new energy system is emerging that implements consumption reduction by improving energy efficiency. Accordingly, as smart grids spread, the rate system by timing is expanding. The rate system by timing is a rate system that applies different rates by season/hour to pay according to usage. In this study, external factors such as temperature/day/time/season are considered and the time series prediction model, LSTM, is used to predict energy power usage data. Based on this energy usage prediction model, energy usage charges are reduced by analyzing usage patterns for each device and transferring power energy from the maximum load time to the light load time. In order to analyze the usage pattern for each device, a clustering technique is used to learn and classify the usage pattern of the device by time. In summary, this study predicts usage and usage fees based on the user's power data usage, analyzes usage patterns by device, and provides customized demand transfer services based on analysis, resulting in cost reduction for users.