• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.2016-2019
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• 1997

To solve the low efficiency problem of low-voltage power supplies, it has been studied to replace the schottky barrier diode with the MOSFET synchronous rectifier. In this paper, Phase Shift-Controlled Clamp Mode Zero Voltage Switching-Multi Resonant Converter with Synchronous Rectifier (PSC CM ZVS-MRC with SR) is presented to achieve high efficiency in low-voltage power supplies. The characteristics analysis of synchronous rectifier is established by using the MOSFET equivalent circuit and efficiency comparison is established between the Synchronous Rectifier and the schottky barrier diode. To verify the validity of the analysis, 33W(3.3V, 10A) PSC CM ZVS-MRC with self-driven synchronous rectifier at switching frequency of 1MHz is designed and tested. And it is confirmed that the experimental results are well consistent with the theoretical results. The maximum efficiency of the converter is 83.4% at full load, which is 3.3% higher than conventional schottky diode rectification.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.5
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• pp.195-205
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• 2001

The mechanical properties of aluminum honeycomb on the direction of axial crushing under quasistatic loading test was investigated. The crushing process was simulated numerically by full-scale finite element models. Simulations reproduce the experimental results both qualitatively as well as quantitatively. From the investigation, we suggested the constitutive model of energy absorbing honeycomb structure for large scale impact analysis. Real impact test of the WB(Moving Deformable Barrier) was carried and compared with finite element simulation. Constitutive model used in the numerical simulation had a good correlation with experiment. By suggesting the optimizing method fur honeycomb cell configuration design, relationship between cell configuration and crush strength is studied.

• Proceedings of the KWS Conference
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• v.43
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• pp.174-176
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• 2004

The duplex stainless clad vessel with 38m & over thickness shall be performed to PWHT based on the ASME code. In this case, it is well-known that precipitators such as carbides and sigma($\sigma$) phase are formed at gram boundary between ferrite and austenite phase. Therefore, a weld test for simulating this situation has been planned and performed by 3309LMo71-1 for barrier layer and E2209Tl-1 for 2nd & over layer and then carried out to investigate the overlaid weld metal. Based on the test results, it could be concluded that PWHT should be carried out after the completion of 1st(barrier) layer and then 2 & over layer should be applied.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.13 no.1
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• pp.9-18
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• 2007

Nanocomposite has been considered as an emerging technology in developing a novel food packaging materials. Polymer nanocomposites exhibit markedly improved packaging properties due to their nanometer size dispersion. These improvements include increased barrier properties pertaining to gases such as oxygen, carbon dioxide, and water vapor, as well as to UV rays, and increased mechanical properties such as strength, stiffness, dimensional stability, and heat resistance. Additionally, biologically active ingredients can be added to impart the desired functional properties to the resulting packaging materials. New packaging materials created with this technology demonstrate an increased shelf life with maintaining high quality of the product. Nanotechnology offers big benefits for packaging. Nanocomposite technology paves the way for packaging innovation in the flexible and rigid packaging applications, offering enhanced properties such as greater barrier protection, increased shelf life and lighter-weight materials.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1136-1141
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• 2003

Among various methods to manufacture the PDP barrier ribs, the pressing and the roll forming methods are simple and economical because they form the ribs by utilizing the plastic flow of the green tape in a relatively short time without generating air-polluting dusts. In the present study, the roll forming method was investigated by experiments as well as numerical analyses and in result the groove roll and the preform were designed. The effect of draft angle, comer radius, and initial thickness of the green tape on the plastic flow was examined by a series of parametric studies. The preform was recommended to ease the plastic flow into the grooves and to avoid the occurrence of crack during rolling and sintering processes.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.12
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• pp.2166-2172
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• 2007

In this study a low-signal equivalent circuit based on the Double Schottky Barrier model is proposed for ZnO-based varistor. Since pin-lead inductance and stray capacitance are considered in pin-lead type ZnO varistor these inductance and capacitance could be removed from the experimental dielectric data of the varistor. According to the equivalent circuit simulation results the higher the varistor-voltage of varistor sample the capacitance of dielectric layer is larger, and the capacitances of semiconducting layer and depletion layer are smaller, while the parallel resistances of semiconducting layer and depletion layer are more larger values. Spectra of the dielectric loss factor $tan{\delta}$ show 2 peaks in low frequency and high frequency regions respectively. The low-frequency peak is due to the relaxation by deep donors and the high-frequency peak is due to the relaxation by shallow donors. Above results are well consistent with the theoretical mechanism of ZnO varistor.

• Journal of the Korea Computer Industry Society
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• v.9 no.3
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• pp.105-114
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• 2008

We present an eye tracking system using a low cost 3D CMOS imager for 3D displays that ensures a correct auto stereoscopic view of position- dependent stereoscopic 3D images. The tracker is capable of segmenting the foreground objects (viewer) from background objects using their relative distance from the camera. The tracker is a novel 3D CMOS Image Sensor based on Time of Flight (TOF) principle using innovating photon gating techniques. The basic feature incorporates real time depth imaging by capturing the shape of a light-pulse front as it is reflected from a three dimensional object. The basic architecture and main building blocks of a real time depth CMOS pixel are described. For this application, we use a stereoscopic type of display using parallax barrier elements that is described as well.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.12
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• pp.623-627
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• 2006

This paper deals with the optimum rotor design solution on torque ripple reduction for a SynRM with concentrated winding using response surface methodology (RSM). The RSM has been achieved to use the experimental design method in combination with finite element method (FEM)and well adapted to make analytical model for a complex problem considering a lot of interaction of design variables. Comparisons are given with characteristics of a SynRM according to flux barrier number, flux barrier width variation, respectively.

• Journal of the Korean institute of surface engineering
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• v.43 no.5
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• pp.217-223
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• 2010

For an application as templates of high performance with proper pore size and shape, porous anodic alumina films were prepared by anodization in oxalic acid, and formation behaviors of anodic alumina layer as well as dissolution process in acid solution have been investigated. The surface characteristics on anodic alumina layer were shown to be dependent on the fabrication parameters for anodization. For the dissolution behaviors of anodic alumina, the thickness of the barrier-type alumina layer decreased linearly with the rate of 0.98 nm/min in $H_3PO_4$ solution at $30^{\circ}C$. The changes of the anodic alumina layers were analyzed by SEM and TEM.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.589-593
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• 2005

It is well known that proper encapsulation is crucial for the lifetime of organic light emitting diode (OLED) displays. With the development of increasingly better barrier coatings and perimeter seals, it has now become very desirable to be able to precisely measure the rate of water vapor and oxygen permeation through barrier coatings and perimeter sealing. This paper demonstrates a new permeation measurement method that uses tritium-containing water (HTO) as a tracer material. The theoretical detection limit of this direct method is $2.4{\times}10^{-8}g/(m^2day)$.