• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.32-33
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• 2006

Processing and properties of high power piezoelectric transformer (PT) fabricated by PIM with nano-sized piezoelectric powders are demonstrated. The high power characteristics of a PMed dome-shaped PT were examined by the lighting test for a 55watt PL lamp. The 55watt PL lamp was successfully driven by the PIMed PT with sustaining efficiency higher than 98%. The transformer with ring/dot area ratio of 2.1 exhibited the maximum properties in terms of output power, efficiency and temperature stability.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2006년도 춘계학술대회 논문집
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• pp.103-107
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• 2006

In this paper, the dimmable electronic ballast for the 250W metal halide lamp was realized by three stage structure. We developed stable the dimming ballast by using a Micro-controller, and measured the output wattage in the dimming range(illumination) from 100% to about 20%. Under the 35% dimming level, it is possible to cause the redution of lamp's life. The dimming performance can reduce the light system's wattage but can reduce the luminance efficiency (lux/watt).

• 전력전자학회:학술대회논문집
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• 전력전자학회 2020년도 전력전자학술대회
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• pp.338-339
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• 2020

화력 발전에 의한 전력 생산은 환경오염으로 이어지고 이를 극복하기 위해 태양광 발전 혹은 풍력발전과 같은 신재생에너지원을 이용한 전력 생산이 꾸준히 증가하고 있다. 하지만 신재생에너지는 불규칙적인 전력을 생산할 뿐만 아니라 전력 계통의 도선 및 부하의 임피던스에 의해 계통의 전압 및 주파수가 변동한다. 이러한 문제를 극복하기 위해 계통 연계형 스마트 인버터를 사용하여 신재생에너지를 사용함과 동시에 계통의 안전성을 높일 수 있다. 본 논문은 ESS를 사용한 계통 연계형 스마트 인버터의 Voltage-Watt, Voltage-Var 제어 및 Frequency-Watt 제어를 통해 신재생에너지에 의해 발생하는 계통의 문제를 해결하는 제어 알고리즘을 제안한다.

• 공업화학
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• 제10권3호
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• pp.343-348
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• 1999

저온 공정이 가능한 rf-plasma를 이용한 화학증착법으로 기판의 온도, 출력, $SiH_4$와 천음 함유한 유기화합불 진구체의 희석비 등을 변수로 각 실험 조건에 따라 iron silicide를 제조하였다. 일반적으로 iron silicide 막은 다단계 공정의 Ion Beam Synthesis (IBS)법으로 성장시키고 있으나, 플라즈마를 사용함으로써 단일공정에 의해 $Fe_aSi_bC_cH_d$로 결합된 iron silicide 및 ${\beta}$-상이 형성될 수 있음을 확인하였다. 철 전구체와 실란 (silane)의 희석비에 따라 막 내에 존재하는 탄소와 수소양의 차이로 인해 서로 다른 막의 특성을 나타내었다. 기관의 온도에 따른 광학에너지갭 ($E_b^{opt}$)은 박 표면에 존재하는 수소가 탈착되면서 제공할 수 있는 활성점이 한정되어 있기 때문에 큰 변화가 없었다. 240 watt 이하의 출력에서는 광학에너지갭이 감소하였고, 240 watt 이상의 높은 출력에서는 식각에 의해 미결합수가 증가하여 광학에너지갭은 높게 나타났다.

• 대한전자공학회논문지
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• 제12권3호
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• pp.13-19
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• 1975

CuCl, KDP 결정체를 이용한 지그재그형 진헹파 전기광학적 레이저 변조기에 대해 자세히 해석했다. 변조기와 크기와 대역폭은 변조용 결정체의 광학적 특성및 M/W유전특성에 의해 결정됨을 알수 있다. 더욱 광손실과 M/W손실의 영향, 입사각, 회절등의 영향을 규명했고 최적 설계법을 제시했다. 중요한 결과를 요약하면 다음과 같다. (1) CuCl, KDP로 10(GHz)이상의 대역폭에서 3(watt)이하의 변조전력으로 50%변조를 얻었다. (2) 변조주파수 한계의 상한은 레이저 빔폭에 의한 차단주파수로 인해 제한된다. A detailed analysis has been carried out of a zigzag traveling wave electro-optic laser modulator usin3 CuCl, KDP Crystal. The inclusion of such practical factors as M/W and optical loss results in an optimum design in which modulator dimensions and bandwidth limitation are uniquely determined by optical and M/W dielectic properties of modulating crystal. The main conclusion of the analysis are: (1) CuCl, KDP may be used to produce 50% modulation over bandwidth of 10(GHz) with less than (watt) of modulating power. (2) The upper modulation frequency limit is set by a cutoff frequency which arises from finite width of optical beam.

• 대한후두음성언어의학회지
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• 제21권2호
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• pp.133-138
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• 2010

Background and Objectives : High-speed imaging can be useful in studies of linguistic and artistic singing styles, and laryngeal examination of patients with voice disorders, particularly in irregular vocal fold vibrations. In this study, we introduce new laryngeal imaging systems which are commercially available high speed cameras connected with a laryngoscope. Materials and Method : The laryngeal images were captured from three different types of cameras. First, the adapter was made to connect with laryngoscope and Casio EX-F1 to capture the images using $2{\times}150$ Watt Halogen light source (EndoSTROB) at speeds of 1,200 tps (frame per second)($336{\times}96$). Second, Phantom Miro ex4 was used to capture the digital laryngeal images using Xenon Nova light source 175 Watt (STORZ) at speeds of 1,920 fps ($512{\times}384$). Finally, laryngeal images were captured using MotionXtra N-4 with 250 Watt halogen lamp (Olympus CLH-250) light source at speeds of 2,000tps ($384{\times}400$) by connecting with laryngoscope. All images were transformed into the Kymograph using KIPS (Kay's image processing Software) of Kay Pentex Inc. Results: Casio EX-F1 was too small to adjust the focus and screen size was diminished once the images were captured despite of high resolution images. High quality of color images could be obtained with Phantom Miro ex4 whereas good black and white images from Motion Xtra N-4 Despite of some limitations of illumination problems, limited recording time capacity, and time consuming procedures in Phantom Miro ex4 and Motion Xtra N-4, those portable devices provided high resolution images. Conclusion : All those high speed cameras could capture the laryngeal images by connecting with laryngoscope. High resolution images were able to be captured at the fixed position under the good lightness. Accordingly, these techniques could be applicable to observe the vocal fold vibration properties in the clinical practice.

• 전기전자학회논문지
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• 제25권3호
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• pp.479-484
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• 2021

본 논문은 SIMT구조의 GPGPU에서 적은 core수로 고성능을 달성하기 위한 구조를 제안하고 설계하였다. 모바일기기에 적용하기 위한 GPGPU는 소모전력대비 성능을 높이기 위한 구조가 필수적이다. 소모전력을 줄이기 위해서 core수가 줄어든 대신 성능을 높이기 위해 thread를 관리하기 위한 warp scheduler의 size를 4로 하여 일반적인 GPGPU의 32 보다 크게 줄였다. Warp size를 적게 되면 pipeline의 idle cycle수를 줄일 수 있고 cache 메모리 접근시 miss penalty를 줄이기 위한 memory latency 적용이 효율적이다. 설계된 GPGPU는 부동소수점 연산을 포함하는 테스트 프로그램으로 연산 성능을 측정하고 28nm CMOS공정으로 소비전력을 측정하여 전력당 성능지수로 104.5GFlops/Watt를 얻었다. 본 논문의 결과는 Nvidia의 Tegra K1과 비교하였을 때 약 4배 우수한 전력당 성능지수를 보였다.

• 영어영문학
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• 제54권1호
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• pp.3-29
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• 2008

Ian Watt, author of The Rise of the Novel, maintained that the novel originated in modern England, came from prose discourses such as the news, political essays and journalistic writing which propagated the Enlightenment, and the novels represent formal realism. The main point of this paper is to examine Watt's theory of the rise of the novel on the basis of the criticism of antinomy of the Enlightenment and "the public sphere" in Habermas' terms. At first, I will criticize formal realism, which is not a new literary species, but a formally renovated realistic form that represented capitalism and protestantism. And, then, I will show that formal realism is a kind of antinomy because it turned away from the voices and reality of the low-class and women though the novel concentrated on common people, not the aristocrats. Secondly, I will inquire into the antinomy of the Enlightenment in the aspects of reason, freedom, individualism and women. In my view, as soon as the high-middle class acquired their political rights, these values were no more encouraged and the result revealed antinomy of the Enlightenment more explicitly. Thirdly, I'd argue that "the public sphere" had positive meanings to everyone when the bourgeosie were fighting against the Absolutism and the aristocracy. I'll also insist that the high-middle class and the intellectuals were in "the public sphere" in which Habermas argues that rationality and equality were thought to have been realized, while the low-middle class and most women were de-enlightened and disciplined by reading the novel privately. In conclusion, formal realism is not the rise of the novel, but the opening of the novel peculiar to bourgeosie parliamentarism from the middle-eighteenth century to the middle-twentieth century.

• 전기전자학회논문지
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• 제27권4호
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• pp.657-667
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• 2023

배전계통에 연계되는 분산전원의 수가 증가함에 따라 계통 내 과전압 문제를 일으키지 않고 접속될 수 있는 한계접속용량인 photovoltaic(PV) hosting capacity(HC)를 추정하는 것이 매우 중요해졌다. 이에 본 연구에서는 접속점의 전압을 유지하는 제어를 수행하면서 향상된 hosting capacity를 추정하기 위한 방안을 제안하고 있다. 제안된 방안은 two-stage optimization framework로 구성되며 Stage 1에서 IEEE Std 1547-2018 가이드라인을 이용한 Volt-Var(VV) 및 Volt-Watt(VW) 제어 PV hosting capacity 추정을 수행한다. Stage 2에서는 VV 및 VW의 파라미터를 개선하는 절차를 거쳐 향상된 PV HC 값을 다시 도출해낸다. 제안한 방식의 성능 검증을 위해 IEEE 37-버스 시스템이 OpenDSS를 사용해 테스트되었으며 결과에서 제안된 방식의 적용을 통해 PV hosting capacity가 증가함을 확인하였다.

• Journal of Electrochemical Science and Technology
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• 제15권3호
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• pp.388-404
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• 2024

In the present work, the operating parameters were optimized using Box Behnken Design (BBD) in response surface methodology (RSM) to maximize the hydrogen production rate (R₁) and hydrogen production rate per unit watt consumed (R₂) of a proton exchange membrane electrolysis cell (PEMEC), a third response (R₃) which was the sum of the scaled values of R₁ and R₂ were selected to be maximized so that both hydrogen production rate and hydrogen production rate per unit watt consumed could be maximized. The major parameters which were influencing the experiment for enhancing the output responses were oxygen electrode/anode electrocatalyst loading (A), current supplied (B) and water inlet temperature (C). The commercial proton exchange membrane Nafion^® was used as the electrolyte. The acetylene black carbon (C_AB) supported IrO₂ was used as the electrocatalyst for preparing oxygen electrode/anode whereas commercial Pt (40 wt%)/C_HSA was used as the H₂ electrode/cathode electrocatalyst. The quadratic model was developed to predict the output/ responses and their proximity to the experimental output values. The developed model was found to be significant as the P values for both the responses were < 0.0001 and F values were greater than 1. The optimum condition for both the responses were O₂ electrode/anode electrocatalyst loading of 1.78 mg/cm², supplied current of 0.33 A and water inlet temperature of 54℃. The predicted values for hydrogen production rate (R₁) and hydrogen production rate per unit watt consumed (R₂) were 2.921 mL/min and 2.562 mL/(min·W), respectively obtained from the quadratic model. The error % between the predicted response values and experimental values were 1.47% and 3.08% for R₁ and R₂, respectively. This model predicted the optimum conditions reasonably in good agreement with the experimental conditions for the enhancement of the output responses of the developed PEM based electrolyser.