• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.5
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• pp.490-495
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• 2009

A small Hall-effect thruster with a thrust range near 10 mN and a specific impulse of about 1500 s has been designed to control or maintain the orbits of small satellites. The thruster system consists of a hall-effect thruster head, a power processing unit and a Xenon (Xe) gas feed system. The total mass, the consumed electric power and the efficiency of the thruster are approximately 10 kg, 300W and 30%, respectively. Analyses results that support the selection of the thruster for small satellites are provided along with a brief description of the thruster system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.3
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• pp.470-474
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• 2002

The graylevel image scanning system realization and design using CIS(Contact image Scanning)be amenable to recognize a papers, OMR and OCR sheet is proposed. The design technique is used CIS scanning sensor in fixing step motor and is optimized with DSP processor for inage processing, and transfer input image data par line in feeding a step unit to PC on the USB interfacer. This system is portable ad A4 size scanning. and keeps image scan processing speed 300mm/sec. The recognition percentage has 98% on the OCR and bar codes.

• The Journal of the Acoustical Society of Korea
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• v.23 no.2
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• pp.134-145
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• 2004

The study aims to develop the underwater wireless telephone system. The system is designed based on the underwater acoustic communication channel parameters such as ambient noise, multipath effect and diver breathing noise. The system adopts SSB modem and its carrier frequency is about 33 kHz in which ambient noise level is low and therefore a high S/N ratio is easily obtained. The source level of the transmitter is designed as 131 dB re 1μPa. Its intelligibility index of sentence shows as 80% or mure in the range of less than 300m in the sea trial.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.581-584
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• 2002

The graylevel image scanning system realization and design using CIS(Contact Image Scanning)be amenable to recognize a papers, OMR and OCR sheet is proposed. The design technique is used CIS scanning sensor in fixing step motor and is optimized with DSP processor for image processing., and transfer input image data par line in feeding a step unit to PC on the USB interfacer. This system is portable and A4 size scanning and keeps image scan processing speed 300mm/sec The recognition percentage has 98% on the OCR and bar codes.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.5
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• pp.481-491
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• 2017

In this study, we developed 300 W lightweight DMFC system for charging secondary battery in small unit military operation. In order to reduce the volumetric shape and weight of the system considering the environment of the individual soldier's, the arranging of system components has been optimized. A metal bipolar plates made of STS-470FC have been implemented to the DMFC stack to meet the weight demand of the system. As a result of the performance test of the stack, the target value was satisfied by outputting 561 W exceeding 24% of the stack output 450 W required to output 300 W required for the entire system. Moreover, 2,655 hours exceeding 1,000 hours also has been satisfied. To ensure good robustness of the metallic bipolar plate based DMFC stack, finite element method based simulations are conducted using a commercial ANSYS Fluent software.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.52 no.3
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• pp.248-256
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• 2016

The main purpose of this paper was to analyze the removal characteristics of gas/particulate phase pollutants for the present system. Experimentally, we performed to estimate the pressure drop and air pollution removal efficiency with physical variables such as stage number, tube velocity, tube diameter, water spray ($NH_4OH$), and so on. It was concluded that the pressure drop was shown below $111mmH_2O$ lower than that of the existing scrubber (centrifugal spray chamber, over 200 mmAq) at inlet velocity 3.46 m/s and 5 stage. The particular removal efficiency of this system was to be significantly higher at 99.8% in comparison with that of the existing scrubber for 5 stage, inlet velocity 3.46 m/s and $NH_4OH$ (aq) 300 mL/min. It was estimated that the removal efficiencies of $SO_2$ and $NO_2$ were 80% and 70% at system inlet velocity 2.07 m/s and $NH_4OH$ (aq) 300 mL/min respectively. Additionally, the present collection system was to be considered as an effective compact system for simultaneous removal of air pollutants (gas/particulate) due to much higher removal efficiency and appropriate pressure drop without a demister.

• Korean Journal of Plant Tissue Culture
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• v.25 no.5
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• pp.323-327
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• 1998

The flavonoid biosynthetic pathway has been studied as a genetic model system, particularly in Petunia hybrida. In order to study the flavonoid biosynthetic pathway, we constructed a fusion gene system between Cauliflower Mosaic Virus (CaMV) 35S promoter and eggplant flavonoid 3', 5'-hydroxylase in pBI 121 plasmid. An optimal condition for plant regeneration was observed when internode explants were cultured on MS medium supplemented with IAA 0.2 mg/L plus BA 3 mg/L. For plant transformation internode explants of Petunia hybrida were precultured on BM medium supplemented with IAA 0.2 mg/L plus BA 3 mg/L. Putative transgenic plants were selected on medium containing kanamycin 50 mg/L plus cefotaxim 300 mg/L. Putative selected transformants were confirmed by amplification of selectable marker gene (nptII) by polymerase chain reaction (PCR) and Southern hybridization of flavonoid 3',5'-hydroxylase gene.

• Korean Journal of Environmental Biology
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• v.37 no.4
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• pp.579-584
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• 2019

The flight characteristics of 11 cinereous vultures (Aegypius monachus) were analyzed by a global positioning system (GPS) tracker(WT-300; KoEco, Inc.). The wintering period in Korea averaged 131 days (SD=17.4) and the average flight rate was 19.6%. The flight altitude was below 100 m for 21.6% of the flight, 101-200 m for 25.3%, 201-300 m for 19.0%, and below 300 m for 65.9%. There was a positive correlation (r=0.929) between the hourly flight rate and altitude. The predominant monthly flight altitude was 101-200 m (p<0.05). The wintering cinereous vultures lowered their flight rate and flew at an altitude of less than 300 m. This is thought to be an efficient way to find food through social interaction.

• Applied Chemistry for Engineering
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• v.20 no.4
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• pp.423-429
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• 2009

The purpose of this study is to investigate the optimal condition for the hydrogen-rich gas production and the CO removal by reforming of gliding arc plasma reforming system using biogas. The parametric screening studies were carried out according to changes of steam feed amount, catalyst bed temperature in water gas reactor and catalyst bed temperature, input air flow rate in preferential oxidation reactor. The standard condition is as follows. The steam/carbon ratio, catalyst bed temperature, total gas flow rate, input electric power and biogas composition rate ($CH_4$ : $CO_2$) were fixed 3, $700^{\circ}C$, 16 L/min, 2.4 kW and 6 : 4, respectively. The results are as follow, HTS optimum operating conditions were S/C ratio of 3 and reactor temperature of $500^{\circ}C$. LTS were S/C ratio of 2.9 and temperature of $300^{\circ}C$. Also, PROX I optimum conditions were input air flow rate of 300 mL/min and reactor temperature of $190^{\circ}C$. PROX II were 200 mL/min and $190^{\circ}C$ respectively. After having passed through each reactor, the results were as follows: 55% of $H_{2}$ yield, 0% of CO selectivity, 99% of $CH_4$ conversion rate, 27% of $CO_2$ conversion rate, respectively.

• Explosives and Blasting
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• v.33 no.3
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• pp.21-28
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• 2015

The objective of this study is to develop a method for monitoring continuously the combustion propagation behavior of commercial thermite reaction mixtures using conventional continuous VOD (velocity of detonation) system. In order to monitor the combustion front propagation with elapsed time during thermite reaction, the VOD system employs two types of commercial VOD probes and one self-made probe: VOD PROBEROD-OS, VOD PROBEROD-HS and VOD PROBEROD-ES, respectively. Among the probes, the only self made VOD PROBEROD-ES successfully demonstrates the velocity of combustion propagation (VOC) with elapsed time. It was found that VOC of the thermite reaction mixture inside a steel tube has been reached around 200m/s within 100mm distance from the ignition and dramatically increased up to about twice the speed of sound in the range between 100mm and 300mm distance. Finally the VOC reached up to around 800m/s. This results imply that it is necessary to use over 300mm long cartridge of thermite reaction mixture in order to achieve normal VOC of the mixture.