• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.3
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• pp.77-81
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• 2012

In a cryogenic propellant tank the pressurant is contracted due to heat loss and the propellant itself evaporates. On a restartable propulsion system such phenomena are more intensive because the propellant contacts with the pressurant on the larger surface during the coast flight. Such heat and mass transfer phenomena should be considered for estimating the amount of pressurant. On the hypothesis that the heat and mass transfer quasi-equilibrium is achieved during the coast flight, the calculation process of the equilibrium pressure is presented. On the process the amount of loaded helium on the Falcon-1 second stage is calculated.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.201-205
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• 2011

In a cryogenic propellant tank the pressurant is contracted due to heat loss and the propellant itself evaporates. On a restartable propulsion system such phenomena are more intensive because the propellant contacts with the pressurant on the larger surface during the coast flight. Such heat and mass transfer phenomena should be considered for estimating the amount of pressurant. On the hypothesis that the heat and mass transfer quasi-equilibrium is achieved during the coast flight, the calculation process of the equilibrium pressure is presented. On the process the amount of loaded helium on the Falcon-1 second stage is calculated.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.238-241
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• 2003

In case of liquid rocket using turbopump, the inner pressure of liquid oxygen tank is maintained low, so vaporization of LOX is generally occurred. This vaporization tendency increases as the inlet helium gas temperature is higher. For estimating the amount of helium in the rocket system, the LOX vaporization phenomena should be carefully considered. In this paper, Inner process of LOX tank is analyzed by two phase flow modeling. the vaporization rate and required Helium mass is investigated with varying inlet helium temperature and heat transfer coefficient.

• Microbiology and Biotechnology Letters
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• v.20 no.6
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• pp.677-680
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• 1992

The effects of pH, temperature and oxygen transfer rate(OTR) on L-Ieucine fermentation were investigated employing Corynebacterium glutamicum CH 1516 in 71 fermentor. The optimum pH, temperature and OTR were determined to be 7.0, $30^{\circ}C$ and 0.21 kmole $O_2$/$m^3{\cdot}hr$, respectively. For the values of OTR lower than 0.19 kmole $O_2$/$m^3{\cdot}hr$ a significant amount of lactic acid was accumulated, while the packed cell volume(PCV) was rapidly increased at higher OTR values above 0.23 kmole $O_2$/$m^3{\cdot}hr$ and glutamic acid was produced to some extent. Scale-up studies for L-Ieucine fermentation which was carried out in 12001 pilot scale fermentor reaffirmed the results of 71 fermentation. The optimum redox potential value for L-Ieucine production was found to be -150 to -170 mY.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.6
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• pp.414-420
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• 2012

In an effort to commercialization of energy saving aeration apparatus, panel-type aeration membranes were prepared from polyurethane sheet of J company in Korea having tensile strength higher than $400kg_f/cm^2$ with thickness of 0.5mm. Micropores of 100 m size were made by poring technique utilizing needles. From lab-tests in 450 L water tank at temperature of $20^{\circ}C$, the performance of aeration panels at 40 L/min aeration rate showed 5 mg/L DO in less than 3 minutes approaching saturation point of 8 mg/L within 8 minutes. The results show very high efficiency with $K_{La(15)}$ ($16.34hr^{-1}$), Standard oxygen transfer efficiency (SOTE 54.7%) and Standard aeration efficienct (SAE 7.88 kg/kwh). Other pilot scale test in a $2m^3$ water tank with water temperature ($19^{\circ}C$) and aeration rate (30 L/min) showed DO exceeding 5 mg/L within 8 minutes along with $K_{La(15)}$ ($5.8hr^{-1}$), SOTE (42.1%) and SAE (6.41 kg/kwh). These efficiencies represent 2~2.5 times higher than conventional aeration devices. Especially, the achievement of higher Oxygen Transfer Rate indicate higher commercial viability. Conventional aeration devices when applied to clean water and wastewater frequently cause problems due to differences in actual Oxygen Transfer Rate. Our actual tests with $40^{\circ}C$ animal farm wastewater resulted very high efficiencies with Oxygen transfer efficiency ($OTE_f$ 22.1%) and $OTE_{pw40}$ (39.6%).

• Proceedings of the Korea Information Processing Society Conference
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• 2022.05a
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• pp.292-293
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• 2022

본 논문에서는 무선센서네트워크 기반의 연안·해양 환경모니터링 시스템을 이용해 연안·해양지역의 대기환경 정보는 물론 수질 환경의 정보를 측정하여 모니터링하였다. 연안 및 해양 환경의 모니터링을 위해 고려된 해양 센서를 사용하여 무선 센서 네트워크를 이용하여 온도, 습도, 조도, 기압, 이슬점의 대기환경 정보와 용존산소량(DO), 수소이온지수(pH), 수온 등의 수질환경 정보를 측정한 후 측정된 환경 정보를 베이스스테이션으로 전송하고 모니터링 하도록 하였다. 환경 정보를 전송할 때 정확하고 신속한 전송을 위하여 데이터 전달 확률이 높은 여러 라우팅 프로토콜 전송방식을 이용하여 전달하였다.

• Journal of the Korean Electrochemical Society
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• v.2 no.1
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• pp.31-37
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• 1999

Copper-containig enzyme, laccase (Rhus vernicifera) was immobilized onto gold electrode using self-assembly technique and its surface properties and catalytic activities were examined. Laccase is an oxidoreductase capable to oxidize diphenols or diamines by 4-electron reduction of molecular oxygen without superoxide or peroxide intermediates. The electrode surface were modified by $\beta-mercaptopropionate$ to have a net negative charge in neutral solution and positively charged laccase (pI=9) was immobilized by electrostatic interaction. The successful immobilization was confirmed by cyclic voltammograms which showed typical surface-confined shapes and behaviors. The amount of charge to reduce the surface was similar to the charge calculated assuming the surface being covered by monolayer. The activity of the immobilized enzyme was tested by the capbility of oxidizing a substrate, ABTS (2,2-azine-bis-(3-ethylbenzthioline-6-sulfonic acid) and it was maintained for $2\~3$ days at $4^{\circ}C$. The immobilzed laccase showed about $10\~15\%$ activity compared to that in solution. The laccase-modified electrode showed the activity of elefoocatalytic reduction of oxygen in the presence of mediator, $Fe(CN)_6^{3-}$ The addtion of azide which is an inhibitor of laccase compeletly eliminated the catalytic current.

• Korean Journal of Food Science and Technology
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• v.6 no.4
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• pp.231-240
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• 1974

The growth of a mixed yeast culture consisting of Canda tropicalis var. KIST 76 and Tricosporon cutaneum KIST 76-H was compared with that of pure cultures under pilot plant conditions. The mixed culture was judged stable based on the nearly constant ratio of the two organisms at the completion of fermentation. We obtained higher cell yields, protein content and productivity in the mixed culture on n-paraffin than the pure culture of C. tropicalis var. KIST 76. T. cutaneum KIST 76-H did not grow on n-paraffin medium. With the batch cultivation of mixed organisms on n-paraffin, the specific growth rates during the exponential growth phase were 0.24-0.33 $hr^{-1};$ cell yields were 96-106% and productivities were 2.9-3.6g/l. hr. The cells obtained contained 55-58% crude protein and 5.5-6.3% lipid. The critical value of dissolved oxygen concentration Ccrit. and saturation constant, km, are approximately 1.5 ppm and 0.228 ppm respectively. Also we established the optimal conditions for the mixed culture in batch fermentation.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.2
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• pp.117-125
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• 2000

The waveform and spectrum analysis of Tursiops truncatus(bottlenose dolphin) sonar signals were carried out on the basis of data collected during the dolphin show at the aquarium of Cheju Pacificland from October 1998 to February 1999. When greeting to audience, the pulse width, peak frequency and spectrum level from the five dolphins'sonar signals were 3.0ms, 4.54kHz and 125.6dB, respectively. At the time of warm-up just before the show, their figures were 5.0㎳, 5.24kHz and 127.0dB, respectively. During the performance of dolphins, with singing, peak frequency ranged 3.28∼5.78kHz and spectrum level ranged 137.0∼142.0dB. With playing ring, pulse width, peak frequency and spectrum level were 7.0㎳, 2.54kHz and 135.9dB, and when playing the ball, the values were 9.0㎳, 2.78kHz and 135.2dB, respectively. The values determined from the five dolphins during jump-up out of water were : pulse width 2.0㎳, peak frequency 4.50kHz and spectrum level 126.8dB. When they responded to trainer's instructions, the values were 2.25㎳, 248kHz and 148.7dB, respectively, and greeting to audience, the peak frequency and spectrum level were 5.84kHz and 122.5dB. During swimming under water, peak frequency and spectrum level were determined to be 10.10kHz and 126.8dB. It was found that there exited close consistencies in pulse width, frequency distribution and spectrum level between whistle sounds and dolphin's sonar signals. Accordingly, the dolphins can be easily trained by using whistle sound based on the results obtained from the waveform and spectrum of the dolphin's sonar signals.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.3
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• pp.175-185
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• 2000

This paper described on a basic study to organize fishing vessel control system in order to control efficiently fishing vessel in Korean offshore. It was digitalized ARPA image on the fishing processing of a fleet of purse seiner in conducting fishing operation at Cheju offshore in Korea as a digital camera and then simulated by used VTMS. Futhermore, it was investigated on the application of FVTMS which can control efficiently fishing vessels in fishing ground. The results obtained were as follows ; (1) It was taken 16 minutes and 35 minutes to casting and hauling net in fishing processing respectively. The length of rope pulled by scout boat was 200m, tactical diameter in casting net was 340.8m, turning speed was 6kts as well. (2) The processing of casting and hauling net was moved to SW, NE as results of simulation when the current direction and speed set into NE, 2kts and SW, 2kts respectively. Such as these results suggest that can predict to control the fishing vessel previously with information of fishing ground, fishery and ship's maneuvering, etc. (3) The control range of VTMS radar used in simulation was about 16 miles. Although converting from a radar of the control vessel to another one, it was continuously acquired for the vector and the target data. The optimum control position could be determined by measuring and analyzing to distance and direction between the control vessel and the fleet of fishing vessel. (4) The FVTMS(fishing vessel traffic management services) model was suggested that fishing vessels received fishing conditions and safety navigation information can operate safely and efficiently.