• Journal of the Korean Institute of Gas
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• v.19 no.1
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• pp.64-70
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• 2015

In order to evaluate the degree of hydrogen embrittlement of TRIP steels charged with hydrogen according to varying the current density and the charging time under acid and alkaline electrolyte conditions were tested by small punch test. The results of SP test showed that the degree of hydrogen embrittlement at acid electrolyte condition was more effective factor compared to that of alkaline electrolyte condition. Therefore, all of the charging time and the charging current density were at the condition of acid electrolyte appeared as the main factor of the degree of hydrogen embrittlement in the condition of acid electrolyte. But, it was considered that the charging time compared to the charging current density at the condition of alkaline electrolyte was more effective factor to raise the degree of hydrogen embrittlement.

• Korean Journal of Ecology and Environment
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• v.38 no.spc
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• pp.8-11
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• 2005

Carbon stable isotope ratios of producers varied in lake ecosystems. In tile present study, we tried to estimate the seasonal variations of carbon isotope ratios of phytoplankton and benthic diatoms in a strongly acidic lake ecosystem. Lake Katanuma is a volcanic, strongly acidic lake (average pH of 2.2), located in Miyagi, Japan. Only two algal species dominate in Lake Katanuma; Pinnularia acidojaponica as a benthic diatom, and Chlamydomonas acidophila as a green alga. Carbon isotope values of P. acidojaponica varied seasonally, while those of particulate organic matter, which were mainly composed of C. acidophila remained fairly stable. The differences suggested that $CO_2$ gas was more frequently limited for P. acidojaponica than C. acidophila, since high density patches of benthic diatoms were sometimes observed on the lake sediment. Generally, carbon concentration mechanisms (CCMs)of microalgae can fix bicarbonate in lakes, and affect the carbon isotope values of microalgae. While, in Lake Katanuma, CCMs of the microalgae may scarcely function because of high $CO_2$ gas concentration and low pH. This is the reason for low seasonal amplitude of carbon isotope values of phytoplankton relative to those in other lakes.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.5
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• pp.52-57
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• 2018

Most current ships have adopted on-board diesel generators to produce electricity, but the overall efficiency of equipment is down to about 50% due to thermal losses from operations such as exhaust gas, jacket water cooler, scavenge air cooler, etc. Recently, fuel cells have been highlighted as a promising technology to reduce the effect on the environment and have a higher efficiency. Therefore, this paper suggested a solid oxide fuel cell (SOFC)-gas turbine (GT) using waste heat from a SOFC and SOFC-GT-steam turbine (ST) with Rankine cycle. To compare both configurations, the fuel flow rate, current density, cell voltage, electrical power, and overall efficiency were evaluated at different operating loads. The overall efficiency of both SOFC hybrid systems was higher than the conventional system.

• Journal of Korean Society for Atmospheric Environment
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• v.2 no.1
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• pp.91-101
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• 1986

Relations of each factor affected by emissions and the prediction of performance have been analyzed numerically by cycle simulation in the Spark Ignition Engine. Through theoretical analysis and experiments, the results are obtained as below. The calculated results and the experimental ones are almost highly agreeable on cycle simulation model, exhaust gas analysis and efficiency for processes in cylinder. Therefore this model is proved appropriate and can be useful for optimum design of Spark Ignition Engines on parametric studies. It is reaffirmed that the Wiebe's function is suitable for predicting Combustion Ration in Spark Ignition Engines. On parametric studies, it is found that optimum conditions whose density of emissions are lower and efficiency is maximum within propriety value are crankangle ATDC $15^\circ-20^\circ$, 2400 rpm. A/F=16 in this experiment.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.E1
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• pp.13-20
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• 2002

The electrical and chemical properties of the dielectric barrier discharge (DBD) process for the benzene removal were investigated. The benzene removal was initiated with the applied voltage higher than the discharge onset value. The removal efficiency over 95 % was obtained at approximately 1.6 kJ lite $r^{r-1}$ of the electrical energy density. The increase of the inlet concentration decreased the removal efficiency. However, the benzene decomposition rate increased with the inlet concentration . While the increase of the gas retention time enhanced the removal efficiency, the decomposition rate decreased. Identification of the optimum condition between the decomposition rate and the removal efficiency is required for field applications of the DBD process.s.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.55.2-55.2
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• 2014

Role of environments is one of today's most widely discussed and debated topic in the field of extra-galactic astronomy. Extreme morphology-density relations found in low-mass galaxies are considered to be the result of an effective role played by environment in the evolution of these galaxies. I will present the results from our dedicated study of early-type dwarf galaxies (dEs) in different environments using imaging and spectroscopic data. We find that Virgo cluster dEs have a variety of structural and kinematic properties. A significant fraction of dEs possesses disk features, such as spiral arm and bar, while a central nucleus seems to be universal in these low mass galaxies. We also find that a majority of dEs are fast rotator and their rotation curves are much steeper than that of spiral galaxies of similar mass. Finally I will discuss how the different environmental mechanisms, i.e., gas-stripping or tidal interaction, can contribute to form heterogeneous dEs in Virgo cluster.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.221-222
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• 2006

This paper describes a Plasma Assisted Debinding and Sintering (PADS) equipment, which has been designed to process Metal Injection Molded (MIM) components. The use of a hybrid system combining a glow discharge with a conventional heating system makes debinding and sintering of MIM components, in the same heating cycle, a feasible industrial process. Characteristics as density, carbon content and mechanical properties are similar to traditionally processed MIM materials. The reduction of energy and gas consumption and shorter lead-times are economic advantages of PADS system. The clean environment of PADS is also an ecological advantage.

• Applied Chemistry for Engineering
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• v.31 no.4
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• pp.360-367
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• 2020

In this study, the accumulation and distribution routes of microplastics in soil environment were examined, and their analytical methodologies were summarized. Density separation and removal process of inhibition materials were introduced for the separation of microplastics in soil and the basic principles and limitations of quantitative and qualitative analyses including pyrolysis gas chromatography mass spectrometry, µ-Raman spectrometry, fourier transform infrared spectrometry, and microscopes were investigated. Chemical extraction methods for the analysis of mediated hazardous substance (additives and sorbed matters) in microplastics were also discussed with focusing on in vitro bioaccessibility assay for the human oral exposure route. Based on the described methodologies for the analysis of microplastics in soil, it is expected that these methods enable to select appropriate analysis techniques in consideration of medium state, contamination level and sample quantity.

• Korean Chemical Engineering Research
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• v.50 no.3
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• pp.464-470
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• 2012

To study characteristics of DME and Propane blended fuel in mixing drum as time passed, mixing experiment of two components was performed. After 20 wt% of DME and 80 wt% of Propane were injected into mixing drum sequentially, and the mixture ratio of blended fuel was analyzed at several sampling ports. Consequently, DME and Propane were not easily mixed and DME was sunk to the bottom of the mixing drum by the density difference. The daily rate of DME ingredient increase was 0.2-0.3 wt%, and it took over 500 hours until two of them were mixed uniformly. And after recirculation of blended fuel in mixing drum, DME and Propane were mixed immediately and uniformly.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.4
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• pp.528-535
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• 2017

Fuel cells have been spotlighted in the world for being highly efficient and environmentally friendly. A hydrogen which is the fuel of fuel cell can be obtained from a number of sources. Hydrogen source for operating the polymer electrolyte membrane fuel cell(PEMFC) in the current underwater environment, such as a submarine and unmanned underwater vehicles are currently from the metal hydride cylinder. However, metal hydride has many limitations for using hydrogen carrier, such as large volume, long charging time, limited storage capacity. To solve these problems, we suggest diesel reformer for hydrogen supply source. Diesel fuel has many advantages, such as high hydrogen storage density, easy to transport and also well-infra structure. However, conventional diesel reforming system for PEMFC requires a large volume and complex CO removal system for lowering the CO level to less than 10 ppm. In addition, because the preferential oxidation(PROX) reaction is the strong exothermic reaction, cooling load is required. By changing this PROX reactor to hydrogen separation membrane, the problem from PROX reactor can be solved. This is because hydrogen separation membranes are small and permeable to pure hydrogen. In this study, we conducted the pressurized diesel reforming and water-gas shift reaction experiment for the hydrogen separation membrane application. Then, the hydrogen permeation experiments were performed using a Pd alloy membrane for the reformate gas.