• 한국정보통신학회논문지
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• 제23권8호
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• pp.959-965
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• 2019

본 논문에서는 CMOS 65-nm 공정을 이용하여 위성 통신 시스템에서 Ka-band를 지원하기 위한 저잡음 증폭기를 설계하였다. 제안된 저잡음 증폭기는 고이득 모드와 저이득 모드로 구성되어있으며, 입력신호의 크기에 따라 이득을 제어하도록 설계하였다. 전력소모를 줄이기 위해 회로 전체의 공급전압을 1 V 이하로 제한하였으며, 인버터 구조의 이득제어 회로에 대해 기술하였다. 제작된 회로의 크기를 줄이기 위해 3D EM 시뮬레이터를 사용하였으며, 패드를 포함하며 $0.33mm^2$의 면적을 갖는다. 제작된 증폭기는 3 dB 대역폭에서 -7 dB의 이득제어 범위를 가지며 반사계수는 고이득 모드에서 -6 dB, 저이득 모드에서 -15 dB 미만으로 측정되었다.

• 한국조경학회지
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• 제24권3호
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• pp.109-114
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• 1996

Generally, the size of our recreation sites is selected through use demand at the peak day. At same time, scale economic and diseconomic are applied to a recreation site. If you are a rational decision-maker, you would like to select the size of your park at profit-maximization point. This study is the first try for modelling a Gain-Loss by the size options of a theme park. For testing the validity of a financial model to select the size of theme parks. Ever-Land, Seoul-Land, Dream-Land's operating size was analyzed. By the size options, the revenue of each park was compared with cost. The profit-maximization point and break-even point of each park were found. Ever-Land and Dream-Land's size was selected between the profit-maximization point and the break-even point. In contrast with Ever-Land and Dream-Land's, Seoul-Land's was selected upper the break-even point. To increase the utility of this model in selecting the size of a theme park, a decision-maker must keep in mind a few limits of this study. That is, 1) this model can not be applied at public parks. 2) Sometimes the others can be more important than financial revenue and cost. Finally, there is the validity of Gain-Loss Model in estimating only the financial revenues and costs through the size options.

• Asian-Australasian Journal of Animal Sciences
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• 제10권3호
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• pp.277-283
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• 1997

Purified diets containing five levels of methionine with 0.4% cystine were fed to growing chicks (8 days old male Arbor Acre strain) to evaluate methionine requirements for growth and maintenance. A model was developed to separate methionine requirement for maintenance from requirement for growth. From this model the daily methionine requirement for growth was 4.22 mg/g gain, and the daily methionine requirement for maintenance was 0.034 times metabolic body size ($W^{0.75}$). Based on nitrogen gain response, the methionine requirement for growth was 0.162 mg/mg N gain, and the daily maintenance requirement was 0.037 times metabolic body size. The plateau of plasma methionine concentration reached at 117.16 mg intake pre day. The total methionine requirement determined based on weight gain response was 138.29 mg/day or 0.33% of the diet and the one determined based on nitrogen gain response was 141.7 mg/day of 0.34% of the diet, respectively. As a percentage of protein, methionine was calculated to be 2.6%; the reported methionine content of carcass CP was 1.76%.

• 융합신호처리학회논문지
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• 제2권4호
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• pp.71-76
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• 2001

본 논문에서는 5GHz 대역을 사용하는 고속 무선 LAN의 표준안의 IEEE 802.11a-1999 를 위한 디지털 자동 이득 제어기를 제언한다. 송수신간의 동기화를 위한 신호인 training symbol을 이용하여 수신기에 입력되는 신호의 이득을 측정한다. 측정된 이득을 이상적인 이득과 비교하여 갱신할 이득을 구한다. 갱신 이득은 신호를 증폭하는 GCA(Gain Controlled Amplifer)의 입력 전압으로 변환되어 신호의 증폭도를 제어하게 된다. 본 논문에서는 하드웨어 부담을 줄이기 위해 부분 선형 근사방법을 이용하여 갱신 이득을 본 논문에서 제안한 디지털 자동 이득 제어기는 VHDL을 이용하여 설계하였으며, Xilinx cAD tool을 이용하여 timing verification을 수행하였다.

• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2001년도 하계 학술대회 논문집(KISPS SUMMER CONFERENCE 2001
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• pp.101-104
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• 2001

본 논문에서는 5GHz 대역을 사용하는 무선 LAN의 표준안인 IEEE 802.11a-1999를 위한 디지털 자동 이득 제어기를 제안한다. 송수신간의 동기화를 위한 신호인 Training symbol을 이용하여 수신기에 입력되는 신호의 이득을 측정한다. 측정된 이득을 이상적인 이득과 비교하여 갱신할 이득을 구한다. 갱신 이득은 신호를 증폭하는GCA(Gain Controlled Amplifier)의 입력 전압으로 변환되어 신호의 증폭도를 제어하게 된다. 본 논문에서는 하드웨어 부담을 줄이기 위해 부분 선형 근사방법을 이용하여, 갱신 이득을 GCA의 입력 전압으로 변환한다. 보다 정확한 제어를 위하여 이득 측정 및 제어 값의 갱신을 7회 반복하여 수행한다. 본 논문에서 제안한 디지털 자동 이득 제어기는 VHDL을 이용하여 설계하였으며, Xilinx CAD Tool을 이용하여 Timing Verification을 수행하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 추계학술대회 논문집
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• pp.10-12
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• 1996

AlGaAs/GaAs Heterojunotion Bipolar Transistors (HBTs) with various emitter areas were fabricated and the device size dependence on the current gain was examined. With the different emitter areas, the passivated devices having the same peripheral length were fabricated and measured. The measured base current density in the Gummel plots shows an ideality factor of nearly 2. It is found that as the emitter area becomes small, the base current density with the ideality factor of 2 increases linearly, and as the emitter perimeter/area ratio becomes large, the surface recombination current density component increases. The current gain performance in AlGaAs/GaAs HBTs is mainly determined by either the larger emitter area or the smaller ratio of the emitter perimeter to the emitter area. These results will be compared with experimental works for GaInP/GaAs HBTs

• Communications for Statistical Applications and Methods
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• 제10권3호
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• pp.627-635
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• 2003

In this short communication we discuss the bias problem of C4.5 in split variable selection and suggest a method to reduce the variable selection bias among categorical predictor variables. A penalty proportional to the number of categories is applied to the splitting criterion gain of C4.5. The results of empirical comparisons show that the proposed modification of C4.5 reduces the size of classification trees.

• ETRI Journal
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• 제27권2호
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• pp.133-139
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• 2005

A monolithic microwave integrated circuit (MMIC) chip set consisting of a power amplifier, a driver amplifier, and a frequency doubler has been developed for automotive radar systems at 77 GHz. The chip set was fabricated using a 0.15 ${\mu}$ gate-length InGaAs/InAlAs/GaAs metamorphic high electron mobility transistor (mHEMT) process based on a 4-inch substrate. The power amplifier demonstrated a measured small signal gain of over 20 dB from 76 to 77 GHz with 15.5 dBm output power. The chip size is 2mm${\times}$ 2mm. The driver amplifier exhibited a gain of 23 dB over a 76 to 77 GHz band with an output power of 13 dBm. The chip size is 2.1mm${\times}$ 2mm. The frequency doubler achieved an output power of -6 dBm at 76.5 GHz with a conversion gain of -16 dB for an input power of 10 dBm and a 38.25 GHz input frequency. The chip size is 1.2mm ${\times}$ 1.2mm. This MMIC chip set is suitable for the 77 GHz automotive radar systems and related applications in a W-band.

• Journal of Nutrition and Health
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• 제36권5호
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• pp.446-451
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• 2003

The purpose of this study was to investigate the effects of wax gourd on weight, triglyceride, leptin and fat cell size in rats fed a high-fat diet. Male Sprague Dawley rats were fed an experimental diet containing total dietary fat at 40% of calories with wax gourd 0%, 5%, 10% and 15% (w/w) for 4 weeks. Weight gain and triglyceride level fell significantly in the 15% wax gourd group compared to the control group. Epididymal fat pad, abdominal fat and perirenal fat tended to decrease in the 15% wax gourd group. Leptin and free fatty acid level were not significantly different among the groups. Fat cell size significantly decreased in the 10% and 15% wax gourd groups compared to the control group. Weight gain correlated positively with visceral fat masses and the levels of leptin and triglyceride. Fat cell size significantly correlated with visceral fat and leptin level. Therefore, the 15% wax gourd diet substantially reduced weight, triglyceride and fat cell size. (Korean J Nutrition 36(5): 446∼451, 2003)

• 한국응용과학기술학회지
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• 제23권3호
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• pp.199-206
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• 2006

Direct decomposition of methane over three types of carbon black (N330-p, N330-f, and HI-900L) was carried out in a fluidized bed quartz reactor. Properties of carbon black before and after reaction were measured and found to be related with surface structure and weight gain. For N330-p and N330-f, some carbon deposit on the surface was considered to be the reason for the increase of BET surface area and pore volume with weight gain. Carbon deposits on the surface and the conglutination of some aggregates may explain the slight increase of particle size. Properties of HI-900L changed much more significantly with weight gain. It is supposed that the increase of aggregate size of HI-900L were due to some unknown oily components. The corresponding agglomeration might be the reason for the decrease of BET surface area with weight gain, as compared with the increase of that for the case of N330 black.