• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1297-1300
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• 2008

A conventional linear accelerator system requires a flat-topped pulse with less than ${\pm}$ 0.5% ripple to meet the beam energy spread requirements and to improve pulse efficiency of RF systems. A pulse transformer is one of main determinants on the output pulse voltage shape. The pulse transformer was investigated and analyzed with the pulse response characteristics using a simplified equivalent circuit model. The damping factor ${\sigma}$ must be >0.86 to limit the overshoot to less than 0.5% during the flat-top phase. The low leakage inductance and distributed capacitance are often limiting factors to obtain a fast rise time. These parameters are largely controlled by the physical geometry and winding configuration of the transformer. A rise time can be improved by reducing the number of turns, but it produces larger pulse droop and requires a larger core size. By tradeoffs among these parameters, the high-voltage pulse transformer with a pulse width of 10 ${\mu}s$, a rise time of 0.84 ${\mu}s$, and a pulse droop of 2.9% has been designed and fabricated to drive a klystron which has an output voltage of 284 kV, 30-MW peak and 60-kW average RF output power. This paper describes design optimization of a high-voltage pulse transformer for high-power pulsed applications. The experimental results were analyzed and compared with the design. The design and optimal tuning parameter of the system was identified using the model simulation.

• 전기학회논문지
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• 제59권4호
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• pp.814-819
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• 2010

This study proposes the antenna circuit design for the transmitting wireless power, the development of the RF non-contact type Dosimeter. That is, the study designed the optimization and numerical analysis of the antenna circuit for the antenna design of 13.56MHz over the frequency bands for transmitting wireless power. We studied the needed items in the existing RF type Dosimeter with battery to implement the wireless power non-contact Dosimeter within the battery. We compared to the real measurement value as calculating the value of the inductance and capacitance through the numerical analysis for the antenna LC resonance using the theory of the electromagnetic induction method. This method to drive low power is designed to simplify the circuit and to improve the efficiency of the rectifier. We convince our research contributes not only to understand the simplified circuit and miniaturization, but also to help the design and application technology of the wireless power transmit system which is received power supply with wireless.

• 한국생산제조학회지
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• 제21권4호
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• pp.556-562
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• 2012

Micro electrical discharge machining (${\mu}EDM$) has been used for non-conventional material removal. One drawback of ${\mu}EDM$ is low productivity. In this study, we tried to find the optimal machining conditions to manufacture the micro hole with an optimal machining time without loss of accuracy. Taguchi method was used to figure out the relation between machining parameters and characteristics of the process. It was found that the electrode wear, the entrance and exit clearance gave a significant effect on the diameter of the micro hole when the diameter of the electrode was identical. Grey relational analysis was used to determine the optimal machining condition for minimum machining time without loss of accuracy. The obtained optimal machining condition was the input voltage of 80V, the capacitance of 680pF, the resistance of $500{\Omega}$, the feed rate of $1.5{\mu}m$/s and the spindle speed of 2900rpm. The machining time was reduced to 48% without loss of accuracy under the optimal machining condition.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.389-390
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• 2008

The dependence of $f_T$ and $f_{max}$ on the unit finger width is measured and analyzed for $0.13{\mu}m$ MOSFETs. The increase of $f_T$ at narrow width is attributed by the parasitic gate-bulk capacitance, and the decrease of $f_T$ at wide width is generated by the reduction of increasing rate of $g_{mo}$. The increase of $f_{max}$ at narrow width is originated from the abrupt reduction of gate resistance due to the non-quasi-static effect. These analysis results will be valuable information for layout optimization to improve $f_T$ and $f_{max}$.

• 전자공학회논문지C
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• 제36C권4호
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• pp.17-29
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• 1999

본 논문은 데이터 의존적인 CMOS 회로(예: DSP) 의 전력량을 감축하기 위한 상위 수준 합성 기법에 대한 연구이다. 상위수준 합성은 스케줄링, 자원 및 레지스터 할당의 세가지로 나우어서 수행한다. 스케줄링시의 저전력 설계의 목적은 자원할당 시 입력을 재 사용할 수 있는 가능성을 증가시키는 것이다. 스케줄링 후에 자원 및 레지스터 할당 문제는 가중차기 부가된 앙립 그래프로 표현하여 최소비용흐름 알고리즘을 수행함으로써 스위칭 동작횟수가 적은 해를 얻는다. 제안된 알고리즘은 저전력 레지스터 및 자원 할당 문제에 대하여 O({{{{ { n}^{3 } }}}}) (n은 그래프의 노드수) 시간에 최적해를 제공한다. 벤치마크 회로에 대한 실험 결과는 15%의 전력 감축 효과를 나타낸다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2003년도 추계종합학술대회
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• pp.442-445
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• 2003

본 연구에서는 엑시머 레이저 여기용으로 40 J급 자기펄스압축시스템(WC : magnetic pulse compression system)을 개발하고, MPC의 각단에서 최적조건을 구하였다. MPC 시스템은 DC 전원 공급기, 펄스 트랜스, 네 단의 포화인덕터로 이루어져 있다. MPC 각 단에서 포화인덕터의 회전수는 140회, 26회, 5회와 1회이며, 각단에서의 최적 용량는 각각 34 nF, 28.9 nF, 22.1 nF, 22.1 nF이다. MPC 시스템의 개선으로 우리는 43 kV의 전압, 8.25 kA의 전류와 360 ns의 펄스폭을 얻을 수 있었으며, 이때 최대 펄스 압축율은 77.7, 전류 이득은 71.7이었다.

• 한국정보통신학회논문지
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• 제16권7호
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• pp.1391-1396
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• 2012

본 연구에서는 해저의 반사면이나 흡음재와 같이 주파수에 따라 다른 특성을 가지는 매체를 수치적으로 모델링하였다. 기존의 흡음재 해석 등가회로 모델에 용량성 성분을 부가하기 위해 Debye polarization 기법을 적용하여 흡음재의 모델링을 하였다. 이 모델의 파라미터를 추정하기 위해 폴리우레탄이라는 흡음재의 흡음 주파수 특성을 이용하였다. 파라미터의 추정에는 non-linear least squares라는 비선형 최적화 기법을 사용하였다. 먼저 두께 25 mm의 폴리우레탄의 흡음재의 파라미터를 추정하였으며, 이 파라미터를 이용해 50 mm의 폴리우레탄의 특성을 모델링하는 것이 가능하였다. 이를 바탕으로 흡음재의 주파수에 따른 흡음 특성을 하나의 간단한 모델로 모델링하는 것이 가능함을 보였다.

• Current Photovoltaic Research
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• 제2권2호
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• pp.69-72
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• 2014

We investigated current-voltage (I-V) and capacitance (C)-V characteristics of solution-processed thin film solar cells, consisting of $Cu(In,Ga)S_2$ and $CuInS_2$ stacked absorber layers. The ideality factors, extracted from the temperature-dependent I-V curves, showed that the tunneling-mediated interface recombination was dominant in the cells. Rapid increase of both series- and shunt-resistance at low temperatures would limit the performance of the cells, requiring further optimization. The C-V data revealed that the carrier concentration of the $CuInS_2$ layer was about 10 times larger than that of the $Cu(In,Ga)S_2$ layer. All these results could help us to find strategies to improve the efficiency of the solution-processed thin film solar cells.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.331-331
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• 2012

With the NAND Flash scaling down, it becomes more and more difficult to follow Moore's law to continue the scaling due to physical limitations. Recently, three-dimensional (3D) flash memories have introduced as an ideal solution for ultra-high-density data storage. In 3D flash memory, as the process reason, we need to use poly-Si TFTs instead of conventional transistors. So, after combining charge trap flash (CTF) structure and poly-Si TFTs, the emerging device SONOS-TFTs has also suffered from some reliability problem such as hot carrier degradation, charge-trapping-induced parasitic capacitance and resistance which both create interface traps. Charge pumping method is a useful tool to investigate the degradation phenomenon related to interface trap creation. However, the curves for charge pumping current in SONOS TFTs were far from ideal, which previously due to the fabrication process or some unknown traps. It needs an optimization and the important geometrical effect should be eliminated. In spite of its importance, it is still not deeply studied. In our work, base-level sweep model was applied in SONOS TFTs, and the nonideal charge pumping current was optimized by adjusting the gate pulse transition time. As a result, after the optimizing, an improved charge pumping current curve is obtained.

• 한국표면공학회지
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• 제54권3호
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• pp.152-157
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• 2021

The pseudocapacitor has a high energy density characteristic because it accumulates charges through a paradic redox reaction. However, due to its strong insulation properties, metal hydroxides should be designed as structural systems optimized for charge transfer to support fast electron transport. Also, Nickel material is weak to heat and is easily deformed when used as a cathode material, so stability must be secured. In this study, nickel hydroxide was produced by electrodeposition to secure the stability of nickel. Electrodeposition is a synthetic method suitable for growing optimized nickel hydroxide because it allows fine control. Nickel hydroxide (Ni(OH)₂) is a metal hydroxide used as a pseudocapacitor anode due to its high capacitance, electrical conductivity and resistance. Therefore, in order to determine how Ni(OH)₂ nanosheets are formed and what are the optimization conditions, various measurement methods were used to focus on structural growth of nanosheets produced by electrodeposition.