• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.576-581
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• 2002

The suspension is a structure that supports reading, writing head in information storage device. In order to develop the information storage device of high track density, it is necessary to study about the suspension. To satisfy operation condition of information storage device, the suspension shape is very important since it correlates to dynamic characteristics. Therefore, it is necessary to analyze the dynamic characteristics by using finite element analysis and to optimize the suspension of information storage device using size optimization and topology optimization. The suspension has various modes according to different kinds of frequency bandwidth. Sway mode and second torsion mode are especially critical among them. In this paper, we investigated method to improve bandwidth of sway and second torsion mode of HDD and ODD suspension by using size optimization and topology optimization.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.20-22
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• 2007

The H.264/AVC standard developed by the joint Video Team (JVT) provides better coding efficiency than previous standards. The new emerging H.264/AVC employs variable block size motion estimation using multiple reference frame with 1/4-pel MV(Motion Vector) accuracy. These techniques are a important feature to accomplish higher coding efficiency. However, these techniques are increased overall computational complexity. To overcome this problem, this paper proposes advanced fast mode decision suited for variable block size by classifying inter mode based on Rate Distortion Optimization(RDO) technique. Proposed algorithm is going to use to implement H/W structure for fast mode decision. The experimental results shows that the proposed algorithm provides significant reduction computational complexity without any noticeable coding loss and additional computation. Entire computational complexity is decreased about 30%.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2000.04a
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• pp.158-159
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• 2000

내기중의 입자 (aerosol)는 크게 직경이 0.01-0.1 $\mu\textrm{m}$ 대의 Aitken mode와 0.1-1 $\mu\textrm{m}$ 부근의 accumulation mode, 그리고 1 $\mu\textrm{m}$ 이상의 coarse mode로 분류할 수 있으며 대기 중에서 부유하여 서로응집(coagulation) 과 응축(condensation)풍의 과정을 겪으며 변화한다. 일반적으로 Aitken mode 의 입자들은 nucleation 둥에 의해 발생된 입자이며, accumulation mode는 Aitken mode입자간의 응집, 인위적인 배출 둥에 의하여 생성된 입자이다. Coarse mode는 주로 자연적으로 생성된 입자이며 주로 침적에 의해 제거된다. (중략)

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.1
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• pp.1-8
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• 2019

In this study, a maximum power point tracking (MPPT) algorithm based on the perturb and observe (P&O) method with variable step size is proposed to improve the dynamic response characteristic of MPPT, using the existing P&O method. The proposed algorithm, which we verified by simulation and experiment, can track the maximum power point (MPP) through duty control and consisted of three operation modes, namely, constant voltage mode, fast mode, and variable step mode. When the insolation is constant, the voltage variation of the operating point at the MPP is reduced through the step size reduction of the duty in the variable step mode. Consequently, the vibration of the operating point is reduced, and the power generation efficiency is increased. When the insolation changes, the duty and the photovoltaic (PV) voltage are kept constant through the constant voltage mode. The operating point then rapidly tracks the new MPP through the fast-mode operation at the end of the insolation change. When the MPP is reached, the operation is changed to the variable step mode to reduce the duty step size and track the MPP. The validity of the proposed algorithm is verified by simulation and experiment of a PV system composed of a PV panel and a boost converter.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.6
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• pp.347-353
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• 2021

In this study, we presented a novel size optimization framework to control the linear buckling temperature and several buckling modes of plates, by optimizing thickness values of composite structures for practical engineering applications. Predicting the buckling temperature and mode shape of structures is a vital research topic in engineering to achieve structural stability. However, optimizing designs of engineering structures through engineering intuition is challenging. To address this limitation, we proposed a method that combines finite element simulation and size optimization. Based on the idea that the structural buckling temperature and mode shape of a plate are affected by the thickness of the structure, the thickness values of the nodes of the target structure were set as the design variables in this optimization method; and the buckling temperature values, and buckling mode shapes were set as the objective functions. This size optimization method enabled the determination of optimal thickness distributions, to induce the desired buckling temperature values and mode shapes. The validity of the proposed method was verified in terms of their buckling temperature values and buckling mode shapes, using several numerical examples of rectangular composite structures.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.2
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• pp.162-167
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• 2015

In this paper, we propose a F-MBE algorithm for Dual mode seeker (CCD and IIR). The MBE algorithm show improved performance at the IIR target size estimation. but the MBE can't use at Dual Mode seeker. To overcome this problem,, we apply template matching method for CCD target size information. The performance of proposed F-MBE method is tested at target intercept scenario of dual mode seeker equipped missile. The experiment results show that the proposed algorithm has the relatively improved performance.

• Korean Journal of Optics and Photonics
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• v.26 no.6
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• pp.312-317
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• 2015

We investigate the effect of laser-resonator mode size on the output of a Yb:YAG laser that is mode-locked by a semiconductor saturable absorber mirror (SESAM). We demonstrate that the smaller the product of the mode sizes at a SESAM and at a Yb:YAG crystal, the more stable the mode-locked output is. Also, we found numerically that there is a resonator length at which the mode-locked output occurs, regardless of the thermal lens effect of a Yb:YAG.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.65-67
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• 2003

LCD TV market is rapidly growing. It is forecasted that the main size of the LCD TV will be about 20" to 52". The IPS mode is going to lead the large TFT LCD technology for TV application among other LC modes which are VA mode, WVTN mode and so on, because the display image quality of the IPS mode is superior to others.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.1
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• pp.114-120
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• 2008

Recently, the nano-PM's number concentration emitted by diesel internal combustion engine has focused on attention because this particulate matters are suspected being hazardous of human health. In this study, The nano-PM mass and size of diesel passenger vehicles were measured on chassis dynamometer test bench. The particulate matters(PM) emissions of these vehicles were investigated by number concentration too. A condensation particle counter(CPC) system was applied to measure the particle number and size concentration of diesel exhaust particles at the end of dilution tunnel along the NEDC(ECE15+EUDC) and CVS-75 vehicle test mode. As the research result, the characteristic of vehicle test mode on the diesel nano-particle number and size distribution was investigated in this study.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.6C
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• pp.512-522
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• 2005

In this paper, an optimal determination method of the subband-frame size and mode-switching level is proposed for adaptive OFDM-TDD systems in frequency-selective time-varying channels. The optimization problem considering frequency selectivity. user's mobility, and the signaling overhead caused by the mode change information is formulated in the maximum spectral efficiency sense satisfying the target BER. Assuming that subband-frame size is given, the mode-switching level is first optimized so that the spectral efficiency can be maximized satisfying the target BER. The subband-frame size among candidates is then determined, which maximizes the spectral efficiency. Simulation results show that the proposed scheme outperforms conventional schemes, in terms of the spectral efficiency and the BER.