• 한국세라믹학회지
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• 제28권5호
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• pp.353-358
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• 1991

Fine powders of the 2212 superconducting phase of bismuth system have been prepared directly from solution using ultrasonic spray pyrolysis. The fine superconducting powders produced by pyrolysis were characterized for the size, shape, and crystalline phase by SEM and XRD. The pyrolysis temperature, flow rate of the carrier gas, residence time of the droplets greatly influenced the size, shape, and crystalline phase. The optimum temperature and flow rate of the carrier gas for the preparation of fine powders of the 2212 superconduting phase were found to be 830$^{\circ}C$and 3ι/min, respectively.

• 한국수소및신에너지학회논문집
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• 제20권1호
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• pp.45-54
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• 2009

Reduction reactivity and carbon deposition characteristics of three oxygen carrier particles(OCN01, OCN02, OCN03) have been investigated by using hydrogen, methane, syngas, and natural gas as fuels. For all particles, the maximum conversion, the oxygen transfer capacity, and the degree of carbon deposition increased as the reactive carbon contents increased. The reduction rate and the oxygen transfer rate increased as the moles of required oxygen per input gas increased. The change of maximum conversion, reduction rate, oxygen transfer capacity, oxygen transfer rate and degree of carbon deposition for different fuels can be explained consistently by using parameters such as the reactive carbon contents and the moles of require oxygen per input gas.

• 한국전자통신학회논문지
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• 제7권1호
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• pp.33-38
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• 2012

수중 음향 채널은 매우 복잡하고 지속적인 시변 특성을 가지므로 양질의 통신 서비스를 제공하기란 쉽지 않다. 이러한 수중 음향 채널의 열악한 환경에 대해서 신뢰성이 있고 강건한 통신 서비스를 제공하기 위해서 본 논문에서는 데이터 전송율을 가변시키는 다중 반송파 CDMA(MC-CDMA) 시스템의 성능을 분석한다. 제안한 시스템에 적용한 가변 전송율 알고리즘은 사용자 데이터 전송율을 순시 채널 조건의 함수로 계산하여 채널의 정보를 파악한다. 채널 상태 정보의 획득은 보다 효율적으로 데이터를 전송할 수 있게 하고 시스템의 전반적인 성능을 개선하게 한다. 본 논문에서는 제안한 가변 전송율 다중 반송파 CDMA 시스템의 성능 분석을 시뮬레이션을 통해서 검증한다. 또한 다중 반송파에 적용하는 확산부호들의 적용 가능성을 분석한다.

• 한국통신학회:학술대회논문집
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• 한국통신학회 1987년도 춘계학술발표회 논문집
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• pp.212-218
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• 1987

The error rate equations of digital modulatuon techniques(M-ary PSK MSK Multi-level QAM) have been derived in the environment of Qaussian noise and Jamming And the results are shown in the figures as parameters of carrier power to noise power ration(CNR) carrier power to Jamming power ration(CJR) Jamming power to carrier power ration(JCR) alteration figure of envelope of Jamming(M) As the results of analysis the system performance is more degreeded by Qau-ssian Famming than Tone Famming In case that envelope of Famming has m-distribution, the s/stem parformance is desreeded in the deep alteration of envelope

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2001년도 종합학술발표회 논문집 Vol.11 No.1
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• pp.44-48
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• 2001

In this paper we describe the design of symbol timing and carrier synchronization algorithms for burst receiver. The demodulator consists of digital down converter, matched filter and synchronization circuits. For symbol timing recovery we use modified Gardner algorithm. And we use decision directed method for carrier phase recovery. For the sake of performance analysis, we compare simulation results with the board implemented by FPGA which is APEX20KE series chip for Alter. The performance results show it works quite well up to the condition that a frequency offset equal to 0.1% of symbol rate.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.114.1-114
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• 2001

GPS Receiver gives pseudorange Doppler and integrated carrier phase for measurements to compute navigation information. Thought the integrated carrier phase can be transfer to the equal domain as pseudorange by multiplying the wave length of the received signal, in order to get position information from the carrier phase measurements the integer ambiguity should be resolved. And differencing technique is generally used to eliminate the common error terms of the integrated carrier phase measurements between robber and server. In short baseline double-differencing operation has effect on elimination the common biases for both stations and thus ambiguity resolution are to be reliable. But the baseline increases, the integer ambiguity resolution is hardly, due to the correlated common error is increase ...

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1355-1359
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• 2004

The two way subscriber transmission systems have tendency to spread its carrier frequency bandwidth or information bit rate and average bit error rate according to popularization of high speed information through the digital communication system, transmission medium and the Internet. This fact is an important incentive to realize new systems. These two way subscriber transmission systems usually use same cable or same carrier frequency bandwidth for up stream channel and down stream channel. In the systems, the disturbances of noise, crosstalk or fading affect the characteristics. Specifically, these disturbances cause the decrease of information bit rate and degradation of transmission quality. This paper proposes the improved method of their degradations using the particular feature of two way subscriber transmission systems and it makes clear proposed method is effective by theoretically and some numerical examples.

• KSBB Journal
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• 제13권5호
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• pp.477-482
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• 1998

A biosensor with PZT piezoelectric ceramic crystal was developed for the detection of formaldehyde gas. Poled PZT piezoelectric ceramic disk was made from ZrO2, TiO2 and Nb2O5, together with the addition of PbO and polyvinyl alcohol, through various processes of mixing, calcination drying, crushing, forming, sintering, polishing, ion coating and poling. Oscillator circuit of sensor was made of operational amplifier(AD811AN). Formaldehyde dehydrogenase was immobilized onto a piezoelectic ceramic crystal, together with the cofactors, reduced glutathione and nicotinamide adenine dinucleotide. The effect of flow rate on the sensitivity was determined by varing the flow rate of carrier gas from 24.7mL/min to 111.7mL/min through detector cell. The results indicated that as the flow rate was increased, the recovery rate was increased. And a significant increase in the sensitivity was observed in enhanced flow rate of carrier gas. Frequency difference(ΔF) of immobilized PZT piezoelectic disk increased proportionally to the concentration gas and reproduced to repeated exposures of formaldehyde gas(28ppm, Δ68Hz).

• 한국환경과학회지
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• 제10권4호
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• pp.281-286
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• 2001

Wastewater from the pigment industry has high levels of organics and is known as hardly biodegradable. The objective of this study is to evaluate the applicability of aerobic fixed-bed boifilm reactor packed with ceramic support carrier for the pigment wastewater treatment. Orange 2(widely used azo pigment) adsorption experiment onto biofilm and activated sludge, and continuous treatment experiments were performed. In batch adsorption experiment, maximum adsorption quantity of biofilm was at least two times higher than that of activated sludge. In continuous experiment using aerobic fixed-bed biodilm reactor, the influent concentration of COD and Orange 2 were 75~500mg/${\ell}$(0.45~3.00kg COD/$m^3.day), 5~50mg/$\ell$(0.03~0.30kg Orange 2/$m^3$.day), respectively. At a COD loading rate 2.5kg COD/$m^3$.day and Orange 2 loading rate of 0.18kg Orange 2/$m^3$.day, removal efficiency of COD and Orange 2 were over 95%, 97%, respectively.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.166-171
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• 2008

LNG carrier is a special-purpose vessel to transport natural gas (NG) from the place of origin to each consuming country. To increase the capacity of canying LNG carrier, the natural gas is conveyed as a state of liquid called LNG (Liquefied Natural Gas) during a voyage because the total volume of NG is surprisingly reduced when it is cooled down to $-162^{\circ}C$. That is why the design of insulation of the carriers is important to protect LNG from the external heat invasion, and it has been a great challenging subject for several decades in the shipbuilding industry. For this ultimate goal, the boil-off rate (BOR) needs to be accurately estimated during a voyage. Therefore, the goal of this study is to propose a numerical method for estimating the BOR of LNG for given insulation containment subject to external temperature conditions during voyage.