• Korean Journal of Optics and Photonics
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• v.4 no.2
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• pp.212-219
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• 1993

To reduce the mode noise induced from a multimode dye laser, a modeless laser generating amplified spontaneous emission was used as Stokes beam of the broadband CARS. A new technique for measuring species concentration from the modulation dip of nonresonant background of broadband CARS spectrum was proposed. The modulation dip was numerically calculated and fitted as a function of the concentration of the minor species and temperature of gas sample. We applied this technique in measuring CO concentration in a static cell and also the profile of CO concentration in a CHdair premixed flame of a counterflow burner.

• Journal of Powder Materials
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• v.10 no.4
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• pp.281-287
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• 2003

Ultrafine TiC-15%Co powders were synthesized by a thermochemical process, including spray drying, calcination, and carbothermal reaction. Ti-Co oxide powders were prepared by spray drying of aqueous solution of titanium chloride and $Ti(OH)_2$ slurry, both containing cobalt nitrate, fellowed by calcination. The oxide powders were mixed with carbon powder to reduce and carburize at 1100~125$0^{\circ}C$ under argon or hydrogen atmosphere. Ultrafine TiC particles were formed by carbothermal reaction at 1200~125$0^{\circ}C$, which is significantly lower than the formation temperature (~1$700^{\circ}C$) of TiC particles prepared by conventional method. The oxygen content of TiC-15%Co powder synthesized under hydrogen atmosphere was lower than that synthesized under argon, suggesting that hydrogen accelerates the reduction rate of Ti-Co oxides. The size of TiC-15%Co powder was evaluated by FE-SEM and TEM and Identified to be smaller than 300 nm.

• Journal of the Korean Society of Radiology
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• v.12 no.2
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• pp.123-131
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• 2018

This study compared PENELOPE with measured values from low energy peak to high energy peak to reduce peak to compton ratio and continuum background spectrum using $^{60}Co$, $^{137}Cs$ and mixed volume source. In addition, the change in backscattering and compton edge efficiency was compared with that of PENELOPE through changes in the vicinity of low energy. The results from the mixed volume source are applied to the soil samples to determine how much the minimum detection limits of the soil samples are reduced in the suppression and unsuppressed mode. The compton suppression of the low energy region of $^{60}CO$ (1,173 keV) was considerable, and the Compton edge RF for the $^{137}Cs$ (661 keV) peak was 2.8. In particular, the $^{60}Co$ source emits coincidence gamma rays of 1,173.2 keV and 1,332.5 keV, so compton inhibition was reduced by approximately 21%. RF of compton edges of 1,173 keV and 1,332 keV emitted from a $^{60}Co$ source was 3.2 and 3.4, and the peak to compton edge ratio was improved to 8: 1. And Compared with Penelope, the uncertainty was well within 2%. In compton unsuppressed mode, MDA values of 661 keV, 1,173 keV and 1,332 keV were 0.535, 0.173 and 0.136 Bq/kg, respectively, but decreased in compton suppressed mode to 0.121, 0.00826 and 0.00728 Bq/kg. Thus, Compton suppressed could reduce the background radioactivity and the radioactivity contained in the detector itself.

• Journal of Power System Engineering
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• v.18 no.4
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• pp.52-59
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• 2014

The purpose of this study is to evaluate the performance of after-treatment equipment and thermal storage devices for a heat recovery and combustor-type $CO_2$ generator fuelled a kerosene. To reduce the levels of harmful exhaust gases produced by a $CO_2$ generator, a catalyzed particulate filter(CPF) has been selected as an after-treatment device, by considering back pressure and exhaust gas temperature. The CO conversions of the catalyzed SiC filter(full plugging) were 92%, and the concentration of PM(particulate matter) was near ambient. A thermal recovery device was used to recover 13% of the heat energy from the exhaust gas through heat exchangers installed on the exhaust line of the $CO_2$ generator. 69% of the moisture within the exhaust gases was removed by condensing water, in order to minimize excessive humidity within the greenhouse.

• Journal of Korea Foundry Society
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• v.22 no.3
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• pp.121-129
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• 2002

According to the investigation of waste $CO_2$ molding sand in the 15 steel foundries in Busan and Gyeong area, about 1 ton of waste $CO_2$ molding sand per ton of steel castings production was produced In order to reduce amount of $Na_2O$, Loss of Boiling (L.O.B), Loss of Ignition (L.O.I), Conductivity and PH which are present in the waste $CO_2$ molding sand below the reclamation effect, more than 50% of elimination for reclamation was required. It was found that the waste $CO_2$ molding sand does not contain a harmful component designated by industrial waste materials. Reclamation of the waste $CO_2$ molding sand was practically achieved by an abrasive-dry reclamation process. According to bench time of the sodium silicate-bonded $CO_2$ molding sand, reduction of compressive strength and surface stability index(S.S.I) become slowdown. Therefore, the reclaimed sand could be allowed the reuse of molding sand in $CO_2$ molding process including core sand.

• Korean Journal of Optics and Photonics
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• v.6 no.1
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• pp.21-25
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• 1995

Q-switched Waveguide $CO_{2}$ laser using polygon mirror were constructed and their output characteristics were measured. Waveguide was made of the beryllium oxide tube of inner diameter of 2 mm, outer diameter of 20 mm, and length of 200 mm. A flat ZnSe output coupler of 80% reflectivity was placed on the 9 mm distance from the end of the waveguide. Convex lens was used to reduce the coupling loss between the polygon mirror and the waveguide. The polygon mirror was located behind of convex lens. With this condition, continuous output of the laser were measured as 1.2 W. In the Q-switched mode. pulse width 120 ns were measured with rotational speed 7,559 RPM. and peak power of up to 250 W. 250 W.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.4-4
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• 2017

Atmospheric carbon dioxide enrichment ($eCO_2$) often increases soil nitrous oxide ($N_2O$) emissions, but the underlying mechanisms are not fully understood. Emerging evidence suggests that $eCO_2$ alters plant N preference in favor of ammonium ($NH_4{^+}-N$) over nitrate ($NO_3{^-}-N$). Yet, whether and how this attributes to the enhancement of $N_2O$ emissions has not been investigated. We examined the effects of $eCO_2$ on soil $N_2O$ emissions in the presence of two N forms ($NH_4{^+}-N$ or $NO_3{^-}-N$), using wheat (Triticum aestivum L.) as a model plant. Our results showed that N forms dominated $eCO_2$ effects on plant and microbial N utilization, and thus soil $N_2O$ emissions. Elevated $CO_2$ significantly increased the rate and the sum of $N_2O$ emissions by three to four folds when $NO_3{^-}-N$, but not $NH_4{^+}-N$, was supplied. Enhanced $N_2O$ emission was related to the reduced plant $NO_3{^-}-N$ uptake in wheat. We propose a new conceptual model in which $eCO_2$-inhibition of plant $NO_3{^-}-N$ uptake and/or $CO_2$-enhancement of soil labile C enhances the N and/or C availability for denitrifiers and increases the intensity and/or the duration of $N_2O$ emissions. Together, these findings suggest that to enhance plant N use efficiency and reduce $N_2O$ emission, crop breeding and management need to consider altered plant preference of N sources under future $CO_2$ scenarios.

• Plant Journal
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• v.13 no.2
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• pp.34-38
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• 2017

To reduce global warming, there are so many studies, investments and efforts. The Post Combustion $CO_2$ Capture technology is one of these efforts. But the technologies are having trouble with reducing operating prices. And CCS technology which is using amine solvent uses high price amine solvent. There is solvent losses naturally when operating plant. The solvent loss makes operating and maintenance price higher. In this study, how the washing column of treated flue gas affects the losses of amine solvent and operating was studied.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.21-27
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• 2016

Global warming due to greenhouse gas emissions is considered as a major problem worldwide, and many countries are making great efforts to reduce carbon dioxide emissions. Many technologies in post-combustion, pre-combustion and oxy-fuel combustion $CO_2$ capture have been developed. Among them, a hybrid pre-combustion $CO_2$ capture system of a water gas shift (WGS) reactor and a membrane gas separation unit was investigated. The 2 stage WGS reactor integrated high temperature shift (HTS) with a low temperature shift (LTS) was used to obtain a higher CO conversion rate. A Pd/Cu dense metal membrane was used to separate $H_2$ from $CO_2$ selectively. The performance of the hybrid system in terms of CO conversion and $H_2$ separation was evaluated using a 65% CO, 30 % $H_2$ and 5% $CO_2$ gas mixture for applications to pre-combustion $CO_2$ capture. The experiments were carried out over the range of WGS temperatures ($200-400^{\circ}C$), WGS pressures (0-20bar), Steam/Carbon (S/C) ratios (2.5-5) in a feed gas flow rate of 1 L/min. A very high CO conversion rate of 99.5% was achieved with the HTS-LTS 2 stage water gas shift reactor, and 83% $CO_2$ was concentrated in the retentate using the Pd/Cu membrane.

• KIEAE Journal
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• v.14 no.2
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• pp.37-46
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• 2014

University buildings are energy-guzzling facility that consume more than 10,000TOE within a campus annually. Even the consumption is on an upswing trend. Behind such high consumption are there cheap power rates for education facility, lack of high-efficiency equipment and ever-increasing use of various information equipment. Being keenly aware that greenhouse gas emission increases due to such rise of energy consumption, the present study carried out a case study. In the case study, the study chose the buildings of E university from top 10 universities that consume energy most in Seoul and examined the current status of their energy consumption and greenhouse gas emission. And then it set the reduction target of greenhouse gas by year. Putting aside a middle and long-termed strategy for later endeavor, it first established the 1st year's implementation plan (2014) for energy saving and greenhouse gas reduction with limited budget and according to greenhouse gas reduction target. The plan is specified as follows. Targets for energy saving are mainly divided into two sectors: machine equipment and electric equipment. 7 ideas were proposed. Three ideas to improve machine equipment are to replace with high-efficiency boilers and chillers and to adjust the position of the cooling tower. By doing so, it was estimated that energy could be saved by 176.34TOE in total and greenhouse gas could be reduced by 370.771t$CO_2$-eq. Four ideas to improve electric equipment include the replacement with LED lights, LED emergency lights and high-efficiency motors and the installation of motion sensors. It was calculated that such replacement could conserve 1,076.08TOE (electric energy) and reduce 2,181.420t$CO_2$-eq (greenhouse gas).