• The Journal of the Korea Contents Association
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• v.11 no.5
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• pp.205-215
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• 2011

Films are sensitive to ultraviolet rays and in contrast, digital camera sensors are extremely sensitive to infrared rays due to the differences in spectral characteristics. As a result, all digital cameras that use CCD or CMOS are equipped with IR Cut-Off Filter on the overall sensor. Complete block out of infrared rays is ideal, but the actual experiment results showed that infrared rays were not being blocked out completely. Infrared permeability was also different for each camera. Therefore, this study aims to analyze the effect of the minute quantities of infrared rays, which get transmitted due to mechanical properties of IR Cut-Off Filters that are installed on digital cameras, on digital picture images. The results obtained by carrying out a comparative analysis of a UV Filter (infrared transmitting state) and a UV-IR Filter (infrared blocked out state) are as follows. It was confirmed that the minute quantities of infrared rays do affect dynamic range and resolution to some extent, despite the little or no difference in noise and color reproduction.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.4
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• pp.772-779
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• 2015

In this paper,a reconfigurable multi-band mobile antenna with switching line for LTE band 13, GSM, K-PCS, WCDMA band. The proposed antenna is planar strip line design and composed of stub shorted to the ground plane and two switching line for proposed band operation. To obtain the optimized parameters, we used the simulator, Using the obtained parameters is fabricated. The numerical and experiment results demonstrated that the proposed antenna satisfied the -6 dB impedance bandwidth requirement while simultaneously covering when the state of sw1 and sw2 on for LTE band 13, the state of sw1 off and sw2 on for GSM, K-PCS, the state of sw1 off and sw2 off for WCDMA. Respectively and characteristics of gain and radiation patterns are determined for a reconfigurable multi-band mobile terminal.

• Journal of the Korean Mathematical Society
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• v.52 no.3
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• pp.469-487
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• 2015

We consider a model of HIV infection with various compartments, including target cells, infected cells, viral loads and immune effector cells, to describe HIV type 1 infection. We show that the proposed model has one uninfected steady state and several infected steady states and investigate their local stability by using a Jacobian matrix method. We obtain equations for adjoint variables and characterize an optimal control by applying Pontryagin's Maximum Principle in a linear control problem. In addition, we apply techniques and ideas from linear optimal control theory in conjunction with a direct search approach to derive on-off HIV therapy strategies. The results of numerical simulations indicate that hybrid on-off therapy protocols can move the model system to a "healthy" steady state in which the immune response is dominant in controlling HIV after the discontinuation of the therapy.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.350-350
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• 2012

본 연구에서는 Oxide 두께가 각각 4, 6 nm인 Symmetric NMOSFET의 전기적 특성 분석에 관한 연구를 진행하였다. 게이트 전압에 따른 Drain saturation current (IDSAT), Threshold Voltage(VT) 및 드레인 전압에 따른 Off-states 특성 변화를 분석하였다. 소자 측정 결과 oxide 두께가 4 nm인 경우 Vt는 0.3 V, IDSAT은 73 ${\mu}A$ (@VD=0.05)로, oxide 두께가 6 nm인 경우 Vt는 0.65 V, IDSAT은 66 ${\mu}A$ (@VD=0.05)로 각각 측정되었다. 이는 oxide 두께가 얇은 경우 게이트 전압 인가 시 Electric field 증가에 따른 것으로 판단된다. 또한 드레인 전압 인가에 따른 소자 특성 분석 결과 oxide 두께가 4nm인 경우 급격한 Gate leakage 증가를 보였으며, 이에 따라 Off-state에서의 leakage current가 증가함을 확인하였다. 본 연구는 Oxide 두께에 따른 MOSFET 소자의 전기적 특성 분석을 위해 진행되었으며, 상기 결과와 같이 oxide 두께 가변은 Idsat, Vt, leakage current 등의 주요 파라미터에 영향을 주어 NMOSFET 소자의 전기적 특성을 변화시킴을 확인하였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.10
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• pp.912-917
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• 2006

In this paper, Trench emitter electrode IGBT structure is proposed and studied numerically using the device simulator, MEDICI. The breakdown voltage, on-state voltage drop, latch up current density and turn-off time of the proposed structure are compared with those of the conventional trench gate IGBT(TIGBT) structures. Enhancement of the breakdown voltage by 19 % is obtained in the proposed structure due to dispersion of electric field at the edge of the bottom trench gate by trench emitter electrode. In addition, the on-state voltage drop and the latch up current density are improved by 25 %, 16 % respectively. However increase of turn-off time in proposed structures are negligible.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.3
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• pp.109-114
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• 2008

The solenoid valve of ABS hydraulic modulator is a two directional on-off valve and is controlled by around 100Hz on-off control. When the on-off valve is switched from open state to closed state, there are braking force deterioration, noise and vibration due to surge pressure in the wheel cylinder. In this study, identifies surge pressure in the braking process of ABS, and investigates the way to reduce the phenomenon. To reduce the surge pressure, PWM(Pulse Width Modulation) control with high frequency of 20kHz was attempted. In conclusion, by using the results of this study for the pressure surge prediction, we could expect enhancement of braking performance in ABS.

• Transactions of the Society of Information Storage Systems
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• v.3 no.4
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• pp.167-172
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• 2007

The recently-developed off-line learning control approaches for the rejection of periodic disturbances utilize the specific property that the learning system tends to oscillate in steady state. Unfortunately, the prior works have not clarified how closely the learning system should approach the steady state to achieve the rejection of periodic disturbances to satisfactory level. In this paper, we address this issue extensively for the class of linear systems. We also attempt to remove the effect of other aperiodic disturbances on the rejection of the periodic disturbances effectively. In fact, the proposed learning control algorithm can provide very fast convergence performance in the presence of aperiodic disturbance. The effectiveness and practicality of our work is demonstrated through mathematical performance analysis as well as various simulation results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.105-106
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• 2005

The impact ionization MOS (I-MOS) transistor with 50nm channel length is presented by using 2-D device simulator ISE-TCAD. The subthreshold slope cannot be steeper than kT/q since the subthreshold conduction is due to diffusion current. As MOSFETs are scaled down, this problem becomes significant and the subthreshold slope degrades which leads an increase in the off-current and off-state power dissipation. The I-MOS is based on a gated p-i-n structure and the subthreshold conduction is induced by impact ionization. The simulation results show that the subthreshold slope is 11.7 mV/dec and this indicates the I-MOS improves the switching speed and off-state characteristics.

• Journal of the Korean Society for Precision Engineering
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• v.5 no.1
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• pp.71-77
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• 1988

This study applies dynamic deformation analysis to the rake face stress distribution of cemented carbide cut-off tools by turning, using a finite element method. The results are following: 1. The dynamic loaded state of a cut-off tool was very changeable for the first 0.6 seconds. Reaching the normal state, it became in active. 2. Chipping was influnced not only by the magnitude of stress but also by the abrupt change of tensile and compressive stresses. 3. The distribution chat of principal stress by dynamic load and the direction of resultant vector were almost constant regardless of load time.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.9
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• pp.911-915
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• 2004

In this study, the electrical characteristics of high-voltage LDMOSFET fabricated by the existing CMOS technology were investigated depending on its process and design parameter. In order to verify the experimental data, two-dimensional device simulation was carried out simultaneously. The off- state breakdown voltages of n-channel LDMOSFETs were increased nearly in proportional to the drift region length. For the case of decreasing n-well ion implant doses from $1.0\times{10}^{13}/cm^2$ to $1.0\times{10}^{12}/cm^2$, the off-state breakdown voltage was increased approximately two times. The on-resistance was also increased about 76 %. From 2-D simulation, the increase in the breakdown voltage was attributed to a reduction in the maximum electric field of LDMOS imolanted with low dose as well as to a shift toward n+ drain region. Moreover, the on- and off-state breakdown voltages were also linearly increased with increasing the channel to n-tub spacing due to the reduction of impact ionization at the drift region. The experimental and design data of these high-voltage LDMOS devices can widely applied to design smart power ICs with low-voltage CMOS control and high-voltage driving circuits on the same chip.