• 전기의세계
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• v.25 no.4
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• pp.12-16
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• 1976

Thyristor등의 반도체등의 전자장치를 사용하여 전력의 변환, 제어 및 개폐등을 행하는 기술분야를 1962년 Storm씨가 Solidstate Power Electronics라고 부르기 시작한 이래 급속한 발전을 이룩하여 왔음은 다 아는 사실이다. Storm씨는 1950년대에 전력제어를 위한 장치로써 가포화 리액터를 이용한 자기증폭기의 개발과 이론전개에 공헌한 분으로 전력용 반도체 소자의 개발의 필요성과 그 응용면의 가치를 가장 절실히 느끼고 있었다. 이는 자기증폭기가 무접점의 자기적 switch가 기계적인 switch에 비하여 응답속도가 빠른 것은 사실이나 400Hz 이상에서는 그 한계성을 가져왔기 때문에 새로운 소자 즉 전자적 전력 switch의 개발의 필요성을 당연하였던 것이다. 이상과 같은 소자들은 동작면에서 전압의 증폭을 대상으로 한것이 아니고 전류의 단속에 의한 전력변환을 목적으로 한 것이라고 볼 수 있다. 즉, 단위전하의 에너지로 표시되는 전압의 조정이 아니고 전하의 수를 조정하는 전류조정작용을 가지 소자라는 점에서 이들을 이용한 장치는 전류제어형이어야만 할 것이다.

• Aerospace Industry
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• v.69
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• pp.52-55
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• 1999

미국에서의 항공기 운항업계에 대한 규제완화 여파로 우리나라 등 각국에도 규제 완화의 바람이 불고 있다. 항공기 제조업계는 기업의 통합과 구조 조정이 급진전하여 소수 정예의 과점 상황으로 나아가는가 하면 운항업계에서는 대규모 회사에 의한 독과점 체제가 무너지고 있다. 이런 배경 아래 항공기 사고에 대해서도 사고 조사가 제3자에 의하여 공정히 행해질 것을 바라는 소리가 높다.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.703-705
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• 1987

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.420-423
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• 2015

This paper proposes a method of non-linearity error detection and calibration for binary-weighted charge-driven DACs. In general, the non-linearity errors of DACs often occur due to the mismatch of layout designs or process variation, even when careful layout design methods and process calibration are adopted. Since such errors can substantially degrade the SNDR performance of DAC, it is crucial to accurately measure the errors and calibrate the design mismatches. The proposed method employs 2 identical DAC circuits. The 2 DACs are sweeped, respectively, by using 2 digital input counters with a fixed difference. A comparator identifies any non-linearity errors larger than an acceptable discrepancy. We also propose a calibration method that can fine-tune the DAC's capacitor sizes iteratively until the comparator finds no further errors. Simulations are presented, which show that the proposed method is effective to detect the non-linearity errors and calibrate the capacitor mismatches of a 12-bit DAC design of binary-weighted charge-driven structure.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.17.1-17.1
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• 2010

2000년대 들어 소재기술의 진보와 함께 혁신적인 성능개선이 이뤄지고 있는 유기박막 태양전지는 가장 신형의 3세대 태양전지로서, 유기 재료의 손쉬운 가공성과 다양성, 낮은 재료비, 그리고 프린팅, 코팅 공정과 같은 값싼 소자 제작공정으로 인해 차세대 저가 태양전지로서 큰 기대를 모으고 있다. 현재 유기박막 태양전지는 단위소자 기준으로 7%대의 광전변환 효율을 달성하고 있는데, 다양한 반도체성 고분자나 단분자 도너 물질에 특히 전자 수용성이 좋은 fullerene(C60)계 억셉터 물질을 채택함으로써 급격히 성능 개선이 이뤄지고 있다. 그러나 상용화를 위해서는 궁극적으로 대면적에서 10% 이상의 성능 수준이 요구되는 바, 유기재료의 낮은 전하 이동도와 짧은 수명을 극복하고 성능을 극대화하기 위해서는 고성능 신규소재의 개발이 필수이다. 태양광 스펙트럼의 장파장 까지 빛흡수가 가능하면서도 광흡수계수가 높은 저밴드갭 도너 물질, 전하 이동도가 획기적으로 개선되고 광 안정성도 높은 신규 소재 개발이 일차적으로 요구되며, 박막 특성 개선과 소자구조의 최적화 등에서도 보다 광범위한 연구개발이 요구되고 있다. 특히 저가의 용액공정에 의한 소자 제작시 박막의 나노-모폴로지 제어는 소자의 성능에 지대한 영향을 미치므로 공정별 한계와 최적조건을 구축하는 것도 매우 긴요하다. 본 발표에서는 당 연구팀을 포함한 국내외 연구그룹들의 최근 유기박막 태양전지 신소재 개발 및 용액공정 기술 현황에 대하여 간략히 살펴보고자 한다.

• Journal of the Korean Chemical Society
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• v.28 no.5
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• pp.279-283
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• 1984

${\beta}$-Substituent effect on the reactivity of retro-ene decarboxylation of but-3-enoic acid was investigated theoretically. It was found that charge effect is important not only through ${\pi}$-electron transfer as has been claimed to rationalize experimental results but also through polarization as found for the $CH_3$ substituent. The reactivity was not determined by the charge effect alone but the HOMO-LUMO energy gap was also found to affect the reactivity. In general it was confirmed that the greater the ${\pi}$-electron donating power of the substituent, the greater is the reactivity.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.39 no.3
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• pp.1-7
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• 2002

This paper presents a new PLL clock generator that can improve a jitter noise characteristics and acquisition process by designing a multi-PFD(Phase Frequency Detector) and an adaptive charge pump circuit. The conventional PLL has not only a jitter noise caused from such a demerit of the wide dead zone and duty cycle, but also a long delay interval that makes a high speed operation unable. An advanced multi-structured PFD circuit using the TSPC(True Single Phase Clocking) circuit is proposed, in which it shows an excellent functionalities in terms of the jitter noises by designing its circuit with the exact dead zone and duty cycle. Our new designed adaptive charge pump in the loop filter of a PLL can improve an acquisition characteristic by adaptively increasing of current. The Hspice simulation is done to evaluate the performance of the proposed circuit. Simulation result shows that our PLL has under 0.01ns in the dead zone, no influence from the duty cycle of input signals and under 50ns in the acquisition time. This circuit will be able to be used in develops of high-performance microprocessors and digital systems.  

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.9
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• pp.13-21
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• 2011

In this paper, the CMOS programmable interface circuit for MEMS gyroscope is presented, and evaluated with the MEMS sensing element. The circuit includes the front-end charge amplifier with 10 bit programmable capacitor arrays, 9 bit DAC for accurate offset calibration, and 10 bit PGA for accurate gain calibration. The self oscillation loop with automatic gain control operates properly. The offset error and gain error after calibration are measured to be 0.36 %FSO and 0.19 %FSO, respectively. The noise equivalent resolution and bias instability are measured to be 0.016 deg/sec and 0.012 deg/sec, respectively. The calibration capability of this circuit can reduce the variations of the output offset and gain, and this can enhance the manufacturability and can improve the yield.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.4
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• pp.269-278
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• 2005

In order to produce only a pH-controlled solution without discharging any unwanted solution, this work has developed a continuous electrolytic system with a pH-adjustment reservoir being placed before an ion exchange membrane-equipped electrolyzer, where as a target solution was fed into the pH-adjustment reservoir, some portion of the solution in the pH-adjustment reservoir was circulated through the cathodic or anodic chamber of the electrolyzer depending on the type of the ion exchange membrane used, and some other portion of the solution in the pH-adjustment reservoir was discharged from the electrolytic system through the other counter chamber with its pH being controlled. The internal circulation of the pH-adjustment reservoir solution through the anodic chamber in the case of using a cation exchange membrane and that through the cathodic chamber in the case of using an anion exchange membrane could make the solution discharged from the other counter chamber effectively acidic and basic, respectively. The phenomena of the pH being controlled in the system could be explained by the electro-migration of the ion species in the solution through the ion exchange membrane under a cell potential difference between anode and cathode and its consequently-occurring non-charge equilibriums and electrolytic water- split reactions in the anodic and cathodic chambers.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.497-500
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• 2006

An theoretical analysis on the electro-osmotic flow in a 2-dimensional slit, that is induced by an external electric field acting on the electrical double layers near the slit wall, was performed. Especially, although there were many studies on the interacting electrical double layers, it was found in this study that they have several physical or mathematical fallacies. To resolve these, the general solution on the charge-regulating slit with the height as a parameter was obtained. The results of this work can provide the electrokinetic solution of nanoscale slit with the electrical double layer interaction as well as that of microscale slit without the interaction and can be used as the benchmark of a numerical analysis and the reference of electrokinetic flow path design.