• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.908-911
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• 2002

This paper investigates the characteristics of deflection for circular plate that has same supporting condition along the width direction of plate according to the area change of supporting end. For two boundary conditions such as simple supporting and clamping on both ends, this study derives maximum deflection formula of circular plate using differential equation of elastic curve, assuming that a circular plate is a beam with different widths along the longitudinal direction. The deflection formula of circular plate is verified by carrying out finite element analysis with regard to the ratio of length of supporting part to radius of circular plate.

• Journal of the korean Society of Automotive Engineers
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• v.8 no.2
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• pp.65-74
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• 1986

A computer program was developed to predict swirling steady axisymmetric turbulent flows by extending TEACH Code. It was applied to a reciprocating engine cylinder with a intake valve on the flat head. Flows were assumed to be steady and swirling. Effects of Reynolds number, the valve lift, and the swirl ratio on flow patterns and turbulence were investigated numerically. Flow patterns were reasonably predicted in comparison with experimental results. Length of the recirculation zone was shortened with increasing valve lifts and swirl ratios. Static pressure distributions show maximum value near the reattachment point of the incoming circular jet and minimum value near the maximum width of the valve attached recirculation zone.

• KIEAE Journal
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• v.7 no.3
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• pp.89-96
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• 2007

The purpose of this experimental study is to investigate the compressive strength, shear strength, bending strength, and crack control by the mixture of the hwang-toh. The size of compressive specimens is $200{\times}200{\times}400(mm)$, and the size of shear, bending specimens is $200{\times}200{\times}600(mm)$. Finally, crack control specimens for comparative comparison is $200{\times}200{\times}15(mm)$. The mixture of the hwang-toh is as follows; Hwangtoh( H)+Water(W), H+W+Sand(S), H+W+S+sTraw(0.5%), H+W+S+sT(1.0%). The actual height, width, and the length are measured at the center of all specimens. The main parameters are mixture ratio of hwang-toh, straw and age of specimens. The test results are as follows. (1) The compressive strength is linearly increased until 15 weeks according to specimen ages. (2) About crack control, the specimen added in 1% straw is the most effective.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.69-70
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• 2008

Micro resonators have been actively investigated for bio/chemical sensors and RF M/NEMS devices. Among various materials, SiC is a very promising material for micro/nano resonators since the ratio of its Young's modulus, E, to mass density, $\rho$, is significantly higher than other semiconductor materials, such as, Si and GaAs. Polycrystalline 3C-SiC cantilever with different lengths were fabricated using a surface micromachining technique. Polycrystalline 3C-SiC micro resonators were actuated by piezoelectric element and its fundamental resonance was measured by a laser vibrometer in air and vacuum at room temperature, respectively. For the cantilever with $100{\mu}m$ length, $10{\mu}m$width and $1.3{\mu}m$ thickness, the fundamental frequency appeared at 147.2 kHz.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1754-1756
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• 2000

Organic semiconductors based on fused-ring polycyclic aromatic hydrocarbon have great potential to be utilized as an active layer for electronic and optoelectronic devices. In this study, pentacene thin films and electrode materials were deposited by Organic Molecular Beam Deposition(OMBD) and vacuum evaporation respectively. For the gate dielectric, polyamic acid was spin-coated and cured into polyimide at 350$^{\circ}C$. Electrical characteristics of the devices were investigated, where the channel length and width was 50${\mu}m$ and 5mm. It was found that field effect mobility was 0.012$cm^{2}/Vs$, and on/off current ratio was $10^5$.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.1-4
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• 2000

This paper presents the analytical results of local - global interaction buckling of orthotropic I-shape compression members. Employing the equilibrium approach, the characteristic equation for local and global interaction buckling of I-shape compression member is derived. Using the derived equation, the buckling coefficients with respect to the ratio of length to width for the I-shape column are suggested as a graphical form. In addition, graphical forms of local, global and FEM results are presents, and they are compared with those in published document.

• Annual Conference on Human and Language Technology
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• 1993.10a
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• pp.193-205
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• 1993

한글의 글자꼴과 장평율 그리고 글줄 길이와 글줄꼴 처리 방식이 가독성에 미치는 효과를 측정하였다. 글자꼴은 명조체, 고딕체, 샘물체를 사용하였고, 장평율은 글자의 가로 대 세로 비율을 1 대 1, 1 대 2 그리고 2 대 1로 변형시킨 세 가지를 사용하였다. 글줄 길이는 60mm와 120mm의 두 가지로 하였고 글줄 끝에서 음절 단위로 끊어 쓴 문장과 어절 단위로 끊어 쓰되 띄어쓰기 여백을 조절한 문장과 조절하지 않은 문장을 사용하였다. 연구결과, 글자꼴에서는 명조체와 고딕체의 가독성이 샘물체보다 좋았고, 가로 대 세로의 비율이 1 대 1이거나 1 대 2인 글자의 가독성이 2 대 1인 글자의 가독성보다 우수하였다. 이러한 연구 결과는 한글 정보 처리 과정에서 자모보다 글자가 중요한 시각 정보로 사용되고 한번 응시하는 동안에 표집되는 글자수가 가독성에 영향을 미칠 수 있다는 사실을 시사한다. 글줄 길이는 120mm일 때의 가독성이 더 좋았고 글줄 끝처리 방식은 가독성에 영향을 미치지 않는 것으로 나타났다.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.3
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• pp.84-91
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• 2001

Comparison between performance of a plate fin and that of a modified plate fin is investigated as a function of the position, the non-dimensional width and height of wings as well as the non-dimensional fin length using a two-dimensional separation of variables method. The ratio of the incremental rate of heat loss to that of the area of a modified plate fin is also presented as a function of the height of wings. The modified plate fin is made by attaching the wings to upper and lower sides of a plate fin. One of the results shows that performance of a modified plate fin is more improved as the wings approach left (higher) thermal reservoir.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.5
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• pp.976-981
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• 2009

This paper proposed optimal design and microcontroller driver for driving the thin-type ultrasonic motor. To find the optimal size of the stator, motions of the motor were simulated using ATILA by changing length, width and thickness of the ceramics. Two sinusoidal waves which have 90 degree phase difference were needed for driving the thin-type motor. The thin-type ultrasonic motor driver was composed of microcontroller(Atmega128), push-pull inverter, encoder and AD-converter. Microcontroller generates four square waves which have variable frequency and 25[%] duty ratio in $20{\sim}150$[kHz]. The output signals of microcontroller were converted to sine wave and cosine wave by push-pull inverter and were applied to the thin-type ultrasonic motor. The encoder and AD-converter were used for maintaining speed of the thin-type ultrasonic motor. The AD-converter controlled DC voltage of inverter in accordance with output signal of encoder. Using the driver, characteristics of the motor as speed and torque were measured.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.8
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• pp.491-495
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• 2017

We investigated solution-processed indium-zinc oxide (IZO) thin-film transistors (TFTs) by inserting a 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD) buffer layer. This buffer layer efficiently tuned the energy level between the semiconducting oxide channel and metal electrode by increasing charge extraction, thereby enhancing the overall device performance: the IZO TFT with embedded PBD layer (thickness: 5 nm; width: $2,000{\mu}m$; length: $200{\mu}m$) exhibited a field-effect mobility of $1.31cm^2V^{-1}s^{-1}$, threshold voltage of 0.12 V, subthreshold swing of $0.87V\;decade^{-1}$, and on/off current ratio of $9.28{\times}10^5$.