• Transactions of the Korean hydrogen and new energy society
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• v.22 no.5
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• pp.641-648
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• 2011

KEPRI (KEPCO Research Institute) designed and operated the lab-scale high temperature electrolysis (HTE) system for hydrogen production with $10{\times}10cm^2$ 5-cell stack at $750^{\circ}C$. The electrolysis cell consists of Ni-YSZ steam/hydrogen electrode, YSZ electrolyte and LSCF based perovskite as air side electrode. The active area of one cell is 92.16 $cm^2$. The hydrogen production system was operated for 2664 hours and the performance of electrolysis stack was measured by means of current variation with from 6 A to 28 A. The maximum hydrogen production rate and current efficiency was 47.33 NL/hr and 80.90% at 28 A, respectively. As the applied current increased, hydrogen production rate, current efficiency and the degradation rate of stack were increased respectively. From the result of stack performance, optimum operation current of this system was 24 A, considering current efficiencies and cell degradations.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.5
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• pp.708-717
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• 2015

This paper proposes a new reduction scheme of circulating current when two units of BESS (Battery Energy Storage System) are operated in parallel with conventional droop control. In case of using conventional droop, the terminal voltage of each BESS are not equal due to the unequal line impedance, which causes the circulating current. The operation performance of BESS is critically dependant on the circulating current because it increases system losses which causes the increasement of required system rating. This paper introduces a new reduction scheme of circulating current in which the terminal voltage difference of each BESS is compensated by adding feed-forward path of line voltage drop to the droop control. The feasibility of proposed scheme was first verified by computer simulations with PSCAD/EMTDC software. After then a hardware prototype with 5kW rating was built in the lab and many experiments were carried out. The experimental results were compared with the simulation results to confirm the feasibility of proposed scheme. Two parallel operating BESS with proposed scheme shows more accurate performance to suppress the circulating current than those with the conventional droop control.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.08a
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• pp.133-136
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• 2003

New porphyrin square (1) was prepared by reaction of porphyrin containing pyridine and $Re(CO)_5Cl$ in THF/toluene solvent. 2-(Methylenel5-crown-5)-nicotinoly ester(2) was synthesized by reaction of 2-(Hydroxymethyl-15-crown-5 and nicotinoly chloride in $CH_2Cl_2$. In fluorescence quenching studies luminescence was quenched by addition of the guest(2) into host(l). In the host-guest system we could obtain binding constant (K=$1.13{\times}10^7M^{-1}$) at decreasing concentration of (2). But the luminescence was dramatically increased after $Na^+$ was added into the host-guest system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.11
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• pp.1-5
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• 2015

In this paper, we propose the optical system design for a medium sized LED marine lanterns which simplifies the multi-layer structure into a single structure. In order to satisfy the target fixed intensity(35,000cd) and vertical divergence($-2.5^{\circ}{\sim}-4.0^{\circ}$, $+2.5^{\circ}{\sim}+4.0^{\circ}$), we use the total internal reflection collimator lens. And a Monte Carlo simulation has been utilized to optimize a condition of a LED package, TIR lens and outside lens. The computer simulation results indicated that this LED marine lanterns can produce of a fixed intensity(35,382cd) and vertical divergence($-3.1^{\circ}{\sim}+2.5^{\circ}$). Using the this optical system, we achieve the target value of LED lanterns.

• Journal of Embryo Transfer
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• v.25 no.4
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• pp.259-262
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• 2010

Optimization of the preimplantation mammalian embryo culture condition was widely focused on refining medium composition under the name of chemically defined media. However, recent research revealed that the alteration of physical environment can be a crucial factor to a successful embryo development. In this study, under the same embryo density, a novel culture device named oil-free micro tube culture (MTC) system was evaluated using porcine parthenogenetic embryos. The activated oocytes were placed into the 0.2 ml thin-wall flat cap PCR tube and cultured to the blastocyst stage. As a preliminary step, embryo density and culture medium volume were optimized under a standard drop culture system. The optimal embryo density range for in vitro culture was 0.5 embryos per ${\mu}l$ in $20\;{\mu}l$ drop (20.5%) and 1.0 embryos per ${\mu}l$ in $10\;{\mu}l$ drop (20.6%). Based on these results, we compared drop culture system and 'MTC' system in terms of the developmental rate to the blastocyst stage. In $20\;{\mu}l$ medium volume, the 'MTC' system showed similar blastocyst formation rate when compared with drop culture system (20.2% versus 20.5%, respectively) while the 'MTC' system showed lower blastocyst formation rate than drop culture system in $10\;{\mu}l$ one (12.7% versus 20.0%, respectively). Therefore the $20\;{\mu}l$ MTC system may be an alternative incubation system for short-distance embryo transport without carrying the $CO_2$ incubator and this provides novel embryo culture device to clinical veterinary embryologists.

• Journal of the Korean Solar Energy Society
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• v.31 no.6
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• pp.103-110
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• 2011

The aim of this study was to analysis the Heating/cooling performance and Daylighting performance of Solar Window System built in apartments. the solar window is the idea to integrate daylight as a third form of solar energy into a PV/Solar Collector system. The process of this study is as follows: 1)Solar Window system was designed through the investigation of previous paper and work. 2)The simulation program(Lightscape3.2) was used in daylighting performance analysis. the reference model of simulation was made up to analysis daylighting performance on Solar Window system. 3)The simulation program(ESP-r, Therm5.0, Window6.0) was used in energy performance analysis. the reference model of simulation was made up to analysis energy and daylighting performance on Solar Window system. 4)The Size of Simulation model for daylighting and heating/cooling energy analysis was $148.5m^2$ 5)The lighting performance analysis was carried out with various variants, such as the size and installed area of Solar Window system. 6)Energy performance simulation was carried out with various variants, such as Integrated U-value of Solar Window system according to its position, installed angle and insulation thickness. Consequently, When Solar Window system is equipped with balcony window of Apartment, Annual heating and cooling energy of reference model was cut down at the average of $4.1kWh/m^2$ or 4.2%.

• Korean Journal of Clinical Pharmacy
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• v.26 no.4
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• pp.330-340
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• 2016

Objective: The outbreak of Middle East Respiratory Syndrome (MERS) started in South Korea in May 2015 and the end of crisis was declared in December 2015 by Korea Centers of Disease Control and Prevention (KCDC). However, Zika virus emerged in less than 2 months following MERS and showed higher mortality than other countries. This study is to assess the current prevention system of overseas infectious diseases, based on MERS and Zika virus outbreak and to suggest effective response system for the future. Methods: We conducted two surveys on medical specialists working at tertiary general hospitals regarding the effectiveness of responding system by KCDC against MERS and Zika virus and education in individual medical institutions using 5-Likert points. Response system was examined in three different periods as initial period, spreading period, and post disease period. Results: Although medical specialists received the notifications in initial period, no practical prevention was proven to be placed in responding stage by medical facilities (averagely 3.5/5 points in total and sub-analyses). During spreading period, there were several academic seminars conducted, which were evaluated as helpful. In post disease period, all answered that there were changes on patient treatment in all medical facilities, with mainly report system and the treatment regulations in case of suspicious patients for infection. Only 49% respondents answered positive on the possibility of initial responses. For questionnaire items regarding Zika virus, all answered that there were notifications prior to the first outbreak of the infected patient. Eighty% of respondents were aware of 'the Guideline system for traveling to dangerous areas', and answered that the system was moderately effective (averagely 3.8/5 points in total). For the effectiveness of prevention measures for foreign novel disease by KCDC, the average point was 3.0 in both of total and sub-analyses. Conclusion: There is not enough response system to prevent infectious disease in medical institutional and governmental levels in Korea. It would warrant the modification of overall medical system to improve preventive measures for initial spread of such diseases.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1715-1720
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• 2016

In the upcoming 5-generation mobile communication system, various techniques for improving the power efficiency and spectral efficiency have been proposed. 5G mobile communication system also have been studied a lot of multi-carrier-based modulation techniques like the 4G mobile communication system. In this paper, we analyzed the conventional system structure of the Zero-tail DFT-s-OFDM and UW (Unique Word) -DFT-s-OFDM system based on DFT-s-OFDM system in these techniques. UW and zero are added and used each system, and CP is removed. the result of quality of systems for simulation, OOB(Out of Band) power of Zero-tail DFT-s-OFDM and UW-DFT-s-OFDM use the less time resource as long as CP length, also both systems are reduced about 11dB than DFT-s-OFDM system. In these result, Zero-tail DFT-s-OFDM and UW-DFT-s-OFDM system are more effective than DFT-s-OFDM system.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.5
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• pp.381-390
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• 1987

To evaluate the effects of the cooling water system on the primary production of marine phytoplankton, a series of experiments were made at the cooling water system of Samchonpo Power Plant from May 1985 to May 1986. Mechanical and physiological perturbations of the entrained process are the most detrimental to the primary production of marine phytoplankton. Nevertheless the primary production is increased by the heated water within the upper limit of temperature tolerence of the phytoplankton. The cooling water system, on the average, reduces the gross production and net production by 4.6 to 12.1 and 8.4 to $11.9\;mgC/m^3/h$, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.2
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• pp.163-169
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• 2003

The floating bead filter was tested for treatment of aquacultural water in a pilot-scale recirculating aquaculture system. Performance of floating bead filter on the removal of total suspended solids (TSS) and the treatment of nitrogen sourer such as total ammonia nitrogen (TAN), nitrite nitrogen and nitrate nitrogen were evaluated. The system was stocked with Nile tilapia at an initial rearing densities of $5\%\;and\;7\%$ over 30 days. The average TSS removal rates were $43.0\;g/m^2{\cdot}day\;and\;39.5\;g/m^2{\cdot}day$ for rearing density of $5\%\;and\;7\%$, respectively. As rearing density increased from $5\%\;to\;7\%$. the TAN removal efficiency decreased from $22.0\%\;to\;17.7\%$. At the rearing densities of $5\%\;and\;7\%$, the average TAN removal rates and removal efficiencies were $38.8\;g/m^2{\cdot}day,\;15.6\%\;and\;37.8\;g/m^2{\cdot}day.\;17.7\%,$ respectively. The average TAN removal rate was $37.8-38.8\;g/m^3{\cdot}day.$ The oxygen consumption by floating bead filter was higher than theoretical oxygen consumption rate by nitrification.