• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.5
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• pp.289-296
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• 2016

The availability of NMP, a solvent used in the manufacturing process of cathode material for lithium ion battery, depends on importation, and the price remains high because of the monopoly of BASF and ISP. For these reasons, most Lithium ion battery manufacturers reuse NMP after recovering it from the exhaust air in the drying process. In Korea, absorption method is mainly used for recovering NMP from the absorption tower using the hydrophilicity of NMP. However, this system has a few disadvantages, such as low purity (80％) of the recovered NMP and 100％ emission due to high water content of the treated gas. In this study, we develop a hybrid NMP recovery system by combining cooling condensation method with concentration method, by which it is possible to obtain an NMP recovery rate of 99.6％, and a high purity (96.1％) of the recovered NMP.

• Journal of the Korean Society for Advanced Composite Structures
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• v.3 no.3
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• pp.1-8
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• 2012

Recently, underground pipes are utilized in various fields of applications such as sewer lines, drain lines, water mains, gas lines, telephone and electrical conduits, culverts, oil lines, etc. Most of pipes are installed for long-term purposes and they should be safely installed in consideration of installation conditions because there are unexpected various terrestrial loading conditions. In this paper, we present the result of investigation pertaining to the structural behavior of glass fiber reinforced thermosetting polymer plastic (GFRP) flexible pipes buried underground. The mechanical properties of the GFRP flexible pipes produced in the domestic manufacturer are determined and the results are reported in this paper. In addition, ring deflection is measured by the field tests and the finite element analysis (FEA) is also conducted to simulate the structural behavior of GFRP pipes buried underground. From the field test results, we predicted long-term, up to 50 years, ring deflection of GFRP pipes buried underground based on the method suggested by the existing literature. It was found that the GFRP flexible pipe to be used for cooling water intake system in the nuclear power plant is appropriate because 5% ring deflection limitation for 50 years could be satisfied.

• The Journal of the Acoustical Society of Korea
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• v.14 no.6
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• pp.13-20
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• 1995

In this paper, the thermoacoustic refrigerating system was implemented and its operation was experimentally verified. The system is composed of several parts ,4 inch midrange speaker, speaker housing, chamber, stack housing, stack of plates, heat exchangers, thin pipe and cavity. The system is filled with He gas at 10 bar and contains T-type thermocouples and condenser microphone for measuring the temperature and pressure inside, respectively. In addition, cooling water is used for protecting speaker from thermal destruction and cooling down the hot heat exchanger. For the experimental verification of the implemented refigerating system, electrical impedance and resonance characteristics were measured. The results showed that it was most efficient to drive the system at 340 Hz. When operated at 340 Hz, $30^\circ{C}$ environments and 50 electical watts, the temperature of the cold region decreased by $16^\circ{C}$. The dissatisfaction mainly comes from the incomplete thermal insulation of the cold region. We also pointed out some guidelines to improve the performance for later study.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.4
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• pp.152-159
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• 2014

Urea solution as a reductant of SCR has been widely used to reduce NOx emissions from diesel engine. But it has lots of problems which are freezing at low temperature due to liquid state, deposition of solid formation in the exhaust, dosing device, and complex package such as mixers for uniform concentration of ammonia. In order to overcome these obstacle, ammonium carbonate which is one of solid ammonium materials to produce ammonia gas directly by sublimation process is considered. Simple reactor with visible widow was designed to predict equilibrium temperature and pressure of ammonium carbonate. To simulate real operation conditions under automobile environment, several cycles of heating and cooling condition were settled, two different re-solidification materials were extracted from the reactor and visible window. Analytical study is performed to characterize these unknown materials by XRD(X-Ray Diffraction), FT-IR(Fourier Transform Infrared Spectroscopy), and EA(Elemental Analyzer). From analytical results, re-solidification materials from heating and cooling cycles are very similar to original material of ammonium carbonate.

• Environmental and Resource Economics Review
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• v.20 no.2
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• pp.381-398
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• 2011

Recently, electricity peaks have frequently occurred in winter, and the concerns about failure in power supply are soaring. One of reasons is due to the increase in industrial demand with economic recovery, and the increases in household and commercial demand with unusual cold waves are spotted as a primary cause. Especially, the diffusion of electricity heat pumps (EHP) has led to the rapid increase in commercial electricity demand. The EHP diffusion is mainly associated with low electricity tariff and cheaper heating and cooling costs compared to those of gas-engine heat pumps (GHP). The problem is that distorted electricity tariff and herd behaviour toward heating and cooling devices could bring about nation-wide inefficiencies in resource allocation. The key countermeasures are as follows. The electricity tariff should be readjusted to a realistic level. The tariff scheme should be so modified that consumers rationally respond to the tariff. In addition, one should find ways to effectively manage electricity demand.

• Fire Science and Engineering
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• v.13 no.3
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• pp.19-26
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• 1999

$CO_2$ extinguishing system is the most $\phi$pular among the gas extinguishing system. $CO_2$ is usually stored with liquified state. But, it gasifies at the tip of nozzle when $CO_2$ was released through the pipe and head. A ro$\alpha$n temperature is very low when $CO_2$ was released. So electrical instrument, magnetic storage equipment and memory semiconductor are electrically or physically injured by cooling effect in a few minutes. So, we intend to find out temperature profile and electrical damage in compartment area, and supply basic d data for research and making standards and code through the full scale experiment. As result of experiment on the damage due to cooling effect from $CO_2$ extinguishing system, i instantaneous discharging temperature. was $-82.5^{\circ}C$ in average. An average temp. in the compartment after discharging $CO_2$ was $-40^{\circ}C$.

• Applied Chemistry for Engineering
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• v.28 no.1
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• pp.118-124
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• 2017

An air cooling, open cathode type polymer electrolyte membrane fuel cell (PEMFC) has the advantages of system simplification and cost effectiveness. Open cathode PEMFC could suffer from reduced performance due to the membrane dehydration in low humidity of air. Effects of the cathode air flow rate, anode purge interval and long term storage on PEMFC performance were investigated in this work. Fan voltage is an important factor on air cooling PEMFC performance because the cathode air flow rate and stack temperature were controlled by fan voltage. The dead ended anode (DEA) method was applied to increase hydrogen usage. Periodical purge was used to discharge accumulated water and gas. The influence of long term non-operating condition on PEMFC performance degradation due to the membrane dehydration was also studied and the quick recovery method was developed.

• Clean Technology
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• v.13 no.1 s.36
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• pp.72-78
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• 2007

As a basic research fur the separation of effective components included in pyrolysis gas oil, the crystallization on each system of naphthalene with 2-methylnaphthalene, indene and 1-methylnaphthalene as impurity has been carried out in column and cold-finger type crystallizer, respectively. In crystallization operation, the purity of naphthalene has been a tendency of increase with decreasing of cooling rate and in the presence of impurity with lower melting point. In comparison of crystallizer types, naphthalene purity in column type crystallizer was a higher value than that in cold-finger type due to effective sweating operation after crystallization.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.2
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• pp.299-305
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• 2016

The High Temperature Superconducting power cables (HTS power cables) become increasingly longer to commercialize the HTS power cable system. Accordingly, demands on refrigerators of large cooling capacity per a unit system have been increased. In Korea, it is currently imported from abroad with the high price due to insufficient domestic technologies. In order to commercialize the HTS power cables, it is necessary to develop the refrigerators with large cooling capacity. The Brayton refrigerators are composed of recuperative heat exchangers, compressors and cryogenic turbo expanders. The most directly considering the efficiency of the Brayton refrigerator, it depends on performance of the cryogenic turbo expander. Rotating at high speed in cryogenic temperature, the cryogenic turbo expanders lower temperature by expanding high pressure of a helium or neon gas. In this paper, the reverse Brayton cycle is designed and the cryogenic turbo expander is designed in accordance with the thermodynamic cycle.

• Journal of the Korean Solar Energy Society
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• v.40 no.2
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• pp.1-10
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• 2020

Korea government published renewable energy obligation policy that public building must be supplied some part of total consumption energy (2019: 27%, 2020: 30%). RETScreen is freely available global energy tool that developed by Canadian National Energy Laboratory to quantify energy saving to compare conventional system. This program can be performed energy modeling, cost analysis, greenhouse gas emission analysis and financial analysis. In this study, GSHP (Ground source heat pump) heating and cooling system were studied for the energy deliverly and ROI (Return On Investment) in an office building. Three cases were studied according to the number of HP (Heat pump) units for the 1,000㎡ office building located in Daejeon. Results indicated that the energy delivery of the case 1 (1 HP unit) covered 57% of the office building heating and cooling energy consumption. The case 2 (2 HP units) covered 87.8% and the case 3 (3 HP units) covered 96.8% of the office building energy consumption. The ROI of the case 1 indicated 7.9 years. While 8.2 years for the case 2 and 9.7 years for the case 3.