• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.1
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• pp.73-77
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• 2008

We have investigated dielectric polarization in organic light-emitting diodes using 8-hydroxyquinoline aluminum($Alq_3$) as an electron transport and emissive material. We analyzed the dielectric polarization of organic light-emitting diodes using characteristics of impedance and equivalent circuit of $ITO/Alq_3/Al$. Impedance characteristics was measured complex impedance Z and phase ${\theta}$ in the frequency range of $1{\times}40Hz\;to\;1{\times}10^8Hz$. We obtained complex electrical conductivity, dielectric constant, and loss tangent(tan${\delta}$) of the device at room temperature. And, we obtained the equivalent circuit of $ITO/Alq_3/Al$ through analyzing dielectric constant and dielectric loss tangent. From these analyses, we could interpret a conduction mechanism and dielectric polarization.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.7
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• pp.120-127
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• 2003

A novel three degrees of freedom sensing method utilizing binary grid pattern image and vision camera is presented. The binary grid pattern image is designed by Pseudo-Random Binary Arrays and referenced to encode in-plane position of a moving stage of the contact-free planar actuator. First, the yaw motion of the stage is detected using fast image processing and then the other planar positions, x and y, are decoded with a sequence of images. This method can be applied to the system that needs feedback of in-plane position, with advantages of a good accuracy and high resolution comparable with the encoder, a relatively compact structure, no friction, and a low cost. In this paper, all the procedures of the above sensing mechanism are described in detail, including simulation and experiment results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1994.10a
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• pp.265-270
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• 1994

본 연구에서는 케비테이션 터널에서의 경사진 원형실린더의 유동유기진동시험을 통하여 경사각에 따른 유동유기진동 특성규명과 아울러 유체력 계수들의 실험적 산정을 시도하였으며 도출된 주요한 결론은 다음과 같다. 경사각이 20.deg. 이상되면 마찰저항력에 비해 수직항력이 지배적이 되며, 이때 수직항력계수는 여러 관찰자에 의해 관측된 범위의 값(1.7-2.0)을 갖는다. 또한, 양력계수 $C_{L,rms}$은 유속범위 4$_{n}$D<8의 범위에서 lock-in 현상에 의해 큰 값을 갖게 되며, 경사각이 커질수록 큰 값을 갖는다. 경사각이 30.deg.인 경우 최대값은 약 0.9, 20.deg.인 경우 0.4로 계측되었다.

• Journal of KSNVE
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• v.8 no.2
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• pp.289-296
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• 1998

To predict the noise propagation from an elevated railway, sound radiation characteristics of elevated structure are measured by using the sound intensity method. In the base of the results, we propose the source model of elevated structure noise and the calculation model for elevated railway noise. Acoustic model of the former is modeled a row of single sources with directivity cos .theta. positioned in the center of a bogie and arranged in the lower side of slabs. Also prediction model is presented with rolling noise and elevated structure noise calculated by considering the power level of a source for one-third octave band, ground absorption and barrier deflection. Noise level unit patterns of a passing train is calculated based on this model and the results are compared with available field data.

• Economic and Environmental Geology
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• v.17 no.4
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• pp.315-320
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• 1984

The newly discovered minerals found during 30 years have been discovered with election microprobe analysis, and several other new minerals have been described largely on the basis of probe analysis. Widely used types of instrument are the wavelength dispersive spectrometer (WDS) and the energy dispersive Spectrometer (EDS), with emitted X-ray dispersed by a curved crystal that is arranged to satisfy the Bragg equation ($n{\lambda}=2dsin{\theta}$). Atomic Nos of Z 4 to 92 can be analyzed quantitatively if they present in amount exceeding 50~100ppm. The application of the microprobe in mineralogical and geological research is quantitative chemical analysis of grains as small as a few microns in diameter, individual grains in a rock or can be analyzed in thin section and polished section, analysis can be made comparatively short time, methods in non-destructure, to photographical and crystallographical information. This paper was written in order to document data evaluation procedure for quantitative energy dispersive election probe analysis.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.6
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• pp.60-69
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• 2000

In order to obtain underwater or underground power sources, the closed cycle diesel engine is operated in the non air-breathing circuit system where the major species of the working fluid include oxygen, argon, and recycled exhaust gas. In the present study, the closed cycle diesel engine is designed to operate at the intake pressure between 2 and 3 bar. For operating in the open-cycle and closed-cycle situations, experimental apparatus using this diesel engine is made with ACAP as data acquisition system. In open, semi-open, and closed cycle modes, the predicted p-$\theta$ and P-V are compared with load bank power. Computation have been performed for wide range of major experimental parameters such as the specific fuel and oxygen concentrations, fuel conversion efficiency and polytropic exponent, IMEP and maximum cylinder pressure.

• Structural Engineering and Mechanics
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• v.48 no.5
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• pp.711-736
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• 2013

In this paper new implicit time integration called N-IHOA is presented for dynamic analysis of high damping systems. Here, current displacement and velocity are assumed to be functions of the velocities and accelerations of several previous time steps, respectively. This definition causes that only one set of weighted factors is calculated from the Taylor series expansion which leads to a simple approach and reduce the computational efforts. Moreover a comprehensive study on stability of the proposed method i.e., N-IHOA compared with IHOA integration which is performed based on amplification matrices proves the ability of the N-IHOA in high damping vibrations such as control systems. Also, wide range of numerical examples which contains single/multi degrees of freedom, damped/un-damped, free/forced vibrations from finite element/finite difference demonstrate that the accuracy and efficiency of the proposed time integration is more than the common approaches such as the IHOA, the Wilson-${\theta}$ and the Newmark-${\beta}$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.16 no.4
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• pp.410-412
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• 1983

On maturation of abalone KIKUCHI'S concept of accumulative temperature expressed ${\Sigma}(t_i-{\theta})$ have been apply importantly for an anniversary spawning of the animals. In case of Haliotis discus hannai he was formulated ${\Sigma}(t_i-7.6)>1300$. This expression is able to modify by UKI'S the relationship between the daily feeding rate ($\%$) (Y) ana temperature ($^{\circ}C$) (t) expressed Y= 0.4291 t-0.1501. The modified expression is as the formula ${\Sigma}(Y-3.05)>570$. And the concept its meaning involves is replaced with accumulative ingestion instead of accumulative temperature. This modified concept is understood that on maturation of abalone temperature decide on satiation level, food ingestion decide on gonad maturity rate.

• Journal of Biomedical Engineering Research
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• v.15 no.3
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• pp.245-252
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• 1994

의료용으로 사용되는 초음파 진단장치와 PC간의 인터페이스를 통해서 초음파 의료 영상 정보를 관리할 수 있는 시스템을 구현하였다. 초음파 진단장치와 PC간의 양방향 데이터 전송이 가능하도록 양방향 인터페이스 카드를 하드웨어로 제작하였고, 이에 맞는 통신 프로토콜을 구현하였다. 또한 영상 정보의 데이터 베이스를 구축하기 용이하도록 영상 파일의 형태를 새로이 정의하였으며 진단장치에서 디스플레이되는 영상을 PC에 맞도록 좌표 변환해서 디스플레이할 수 있도록 소프트웨어를 구현하였다. 특히, 초음파 진단장치의 컨벡스(convex)와 섹터(sector)의 의료영상을 PC에서 디스플레이하기 위해 위치지정과 인터폴레이션(interpolation)기법을 적용하였다. 본 시스템의 타당성을 입증하기 위해서 진단장치와 PC에서 디스플레이되는 영상을 서로 비교함으로써 전송시 영상의 좌표변환이 성공적으로 이루어졌음을 증명하였다.

• Bulletin of the Korean Mathematical Society
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• v.49 no.4
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• pp.693-704
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• 2012

We consider Weierstrass functions and divisor functions arising from $q$-series. Using these we can obtain new identities for divisor functions. Farkas [3] provided a relation between the sums of divisors satisfying congruence conditions and the sums of numbers of divisors satisfying congruence conditions. In the proof he took logarithmic derivative to theta functions and used the heat equation. In this note, however, we obtain a similar result by differentiating further. For any $n{\geq}1$, we have $$k{\cdot}{\tau}_{2;k,l}(n)=2n{\cdot}E_{\frac{k-l}{2}}(n;k)+l{\cdot}{\tau}_{1;k,l}(n)+2k{\cdot}{\sum_{j=1}^{n-1}}E_{\frac{k-1}{2}(j;k){\tau}_{1;k,l}(n-j)$$. Finally, we shall give a table for $E_1(N;3)$, ${\sigma}(N)$, ${\tau}_{1;3,1}(N)$ and ${\tau}_{2;3,1}(N)$ ($1{\leq}N{\leq}50$) and state simulation results for them.