• 전기학회논문지
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• 제57권8호
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• pp.1464-1469
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• 2008

A CMOS Gm-C filter with variable cutoff frequency applicable for using in the direct conversion receiver is designed. The designed filter comprises the CMOS differential transconductors, and the gm of the transconductor is controlled by the bias voltage. This configuration can compensate variant of the cutoff frequency which could be generated by external noises, and also be used in multiband receiver. As a results of HSPICE simulation, the control range of the cutoff frequency is $1.5MHz{\sim}3.5MHz$ and the gain control range is $-2.8dB{\sim}2.6dB$. The layout of the designed 5th-order Elliptic low-pass filter is performed to fabricate a chip using $2.5V-0.25{\mu}m$ CMOS processing parameter.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.515-516
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• 2007

A novel design of contious-time filter for direct conversion receiver applications is proposed. The filter supports different modes including GSM, WCDMA. A 5th chebyshev filter is realized in a gm-C filter topology. The filter circuit is implemented in a standard CMOS $0.35{\mu}m$ processing parameter with a supply voltage of 2.5V. The HSPICE results show that the filter has 200KHz and 5MHz cutoff frequency, and each 3.4us and 85.44us gm value.

• 대한방사선기술학회지:방사선기술과학
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• 제20권2호
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• pp.28-33
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• 1997

For the Evaluation of X-ray image intensifier, we measured radiation dose at input of I. I., brightness and fluorescence at output of I. I. by using X-ray exposure meter, optometer and fluorescence meter for the relative conversion factor. Especially, by using fluorescence meter, we could easily get relative conversion factor without having regulated machine by JIS. Since using, the quality of image intensifier is going down. Consequently, it needs continuous quality maintenance.

• 문화기술의 융합
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• 제3권1호
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• pp.43-48
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• 2017

본 연구는 에너지 변환을 가하면 피부에 기능별 투과와 전달현상의 변화를 확인한다. 주어진 에너지의 변화로 피부에 진행되는 과정과 에너지 전달에 투과조절의 단계로 흐르는 과정을 구성하고, 알고리즘을 통하여 변화의 과정을 모델링한다. 에너지양의 조절과 과정의 처리를 모델링한 상태에서 피부의 표피 진피에 효과적 단계로 자동 조절 및 국부 조절을 통한 시스템 모델을 구성하였다. 에너지 변환에 따른 고정된 위치와 계획된 장치로 재현하는 에너지 조절기능이 크기 형태 조합을 변환시키는 모형으로인한 깊이에 따른 분포의 변화가 정확하게 얻어지도록 투과펄스시스템을 구성하였다. 따라서 효율적인 에너지 변환을 제어하는 전달시스템을 구성하기위해 변환모델을 세분화하여 구축하였다. 이를 통하여 피부효과에 기능적 에너지 조절이 가능한 투과 조절시스템이 구성되어 지속적인 피부의 개선효과가 진행 될 것으로 예상된다.

• 한국수소및신에너지학회논문집
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• 제30권2호
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• pp.170-177
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• 2019

Continuous solid circulation test at high temperature and high pressure conditions and batch type reduction-oxidation tests were performed to check feasibility of a 0.5 MWth chemical looping combustion system. Pressure drop profiles were maintained stable during continuous solid circulation up to 16 hours. Therefore, we could conclude that the solid circulation between an air reactor and a fuel reactor could be smooth and stable. The measured fuel conversion and $CO_2$ selectivity were high enough even at high capacity and even after cyclic tests. Therefore, we could expect high reactivity of oxygen carrier at real operation condition.

• 한국수소및신에너지학회논문집
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• 제25권2호
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• pp.209-217
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• 2014

To enhance the performance of SEWGS system by holding the WGS catalyst in a SEWGS reactor, a spring type bed insert was developed. In this study, effects of operating variables such as steam/CO ratio, gas velocity, syngas concentration on CO conversion were investigated in a fluidized bed reactor using the spring type bed insert to hold the WGS catalyst as tablet shape. CO conversion increased initially as the steam/CO ratio increased. But further increment of the steam/CO ratio caused decreasing of CO conversion because of increment of gas velocity and decrement of syngas concentration. Moreover, CO conversion decreased as the gas velocity increased and the syngas concentration decreased at the same steam/CO ratio. Continuous operation up to 48 hours (2 days) was carried out to check reactivity decay of WGS catalyst supported by spring type bed insert. The average CO conversion was 99.04% and we could conclude that the WGS reactivity at those conditions was maintained up to 48 hours.

• Nuclear Engineering and Technology
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• 제12권3호
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• pp.171-179
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• 1980

중성자 및 감마선에 대한 선량율 환산인자(flux-to-dose-rate conversion factors)를 최대흡수선량 개념을 근거로 하여 계산하였다. 중성자 및 감자선에 대한 선량율 군산인자는 에너지 범위가 각각 2.5$\times$$10^{-8}$ 20MeV 및 0.01-15MeV에 대하여 계산하였다. 이제까지 선량율 환산인자는 단일에너지에 대한 값이 였었는데 본 연구에서는 유사인체조직 (phantom)내에서 방사선의 에너지 분포가 직선적이 아니라고 가정하여 계산되었다. 특히 DLC-23, DLC-27, DLC-31 등 핵정수 자료의 각 근에 적합한 선량율 환산인자를 결정하였다는 점이 특색이다. 결과적으로 ANSI N666에 있는 값과 본 연구에서 계산된 값이 잘 일치된다는 것을 확인하였고, 본 결과는 어떤 방사선장에서도 중성자나 감마선 선량율 분포를 계산하는데 이용될 수 있고, 방사선 차폐해석, 방사선방어, radiation dosimetry 등에 필요한 값이 될 것이다.

• 한국실내디자인학회논문집
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• 제20권3호
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• pp.59-68
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• 2011

As society alters and building ages, many industrial facilities lost their function and abandoned in central city areas, and sometimes creating many problems. However, many European countries successfully transformed those urban decay to vivid cultural hub. The purpose of this study was to analyze a concept and methods of converting idle industrial facilities to successful cultural spaces. A case study of Tate Modern, Baltic Center for Contemporary Art, and Ruhr Museum was conducted using literature review, site visit, and interview methods. Findings indicated that converting historically significant idle industrial facilities to cultural center had not only reused abandoned site but also helped regenerating adjacent urban areas. This article demonstrates the key factors of successful conversion strategies as convenience, participation, placeness, historicity, and accessibly; and thus an effort to actively enhance the strategic factors were demanded in future conversion projects. A continuous studies on exploring extensive cases in various perspectives are required for further generalization in future studies.

• Bulletin of the Korean Chemical Society
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• 제35권2호
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• pp.525-530
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• 2014

Titanium dioxide nanotube supported ZSM-5 zeolite composite catalyst was fabricated by decorating ZSM-5 zeolite on the hydrothermally synthesized titanium dioxide via hydrothermal process and subsequent annealing. The catalyst was characterized by X-ray powder diffraction (XRD), Transmission electron microscopy (TEM) and Nitrogen adsorption-desorption (BET). The surface acidity of the catalyst was measured by means of Fourier transform infrared (FT-IR) spectrum of pyridine adsorption. And the catalytic activity for ethanol dehydration to ethylene was evaluated in a continuous flow fixed-bed reactor. Attributed to the increase of the effective surface acid sites caused by titanium dioxide nanotube as electron acceptor, titanium dioxide nanotube supported ZSM-5 zeolite composite catalyst exhibits strongly enhanced activity for ethanol dehydration to ethylene.

• Biotechnology and Bioprocess Engineering:BBE
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• 제7권4호
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• pp.225-230
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• 2002

Experiments on deactivation kinetics of immobilized lipase enzyme from Candida cyl-indracea were performed in stirred bath reactor using rice bran oil as the substrate and temperature as the deactivation parameter. The data were fitted In first order deactivation model. The effect of temperature on deactivation rate was represented by Arrhenius equation. Theoretical equations were developed based on pseudo-steady state approximation and Michaelis -Menten rate expression to predict the time course of conversion due to enzyme deactivation and apparent half-life of the immobilized enzyme activity in PFR and CSTH under constant feed rate polity for no diffusion limitation and diffusion limitation of first order. Stability of enzyme in these continuous reactors was predicted and factors affecting the stability were analyzed.