• Korean Journal of Environmental Agriculture
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• v.39 no.4
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• pp.297-304
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• 2020

BACKGROUND: Emission of nitrous oxide (N2O) from the soil is expected to depend on the types of nitrogen fertilizer used. Biochar has recently been proposed as a potential mitigation of climate change by reducing the N2O emission. Although laboratory studies reported that biochar applications could reduce N2O emission, the number of field-based studies is still limited. Therefore, a field experiment was conducted to investigate the effect of biochar on N2O emission when different nitrogen fertilizers were applied in corn cultivated field. METHODS AND RESULTS: The field experiment consisted of six treatments: urea fertilizer without biochar (U), ammonium sulfate fertilizer without biochar (A), oil cake fertilizer without biochar (O), urea fertilizer with biochar (U+B), ammonium sulfate fertilizer with biochar (A+B), and oil cake fertilizer with biochar (O+B). Biochar was applied at a rate of 10 t/ha. Greenhouse gas fluxes were measured during growing seasons using static vented chambers. The cumulative N2O emissions were 0.99 kg/ha in the U, 1.23 kg/ha in the A, 3.25 kg/ha in the O, 1.19 kg/ha in the U+B, 0.86 kg/ha in the A+B, and 1.55 kg/ha in the O+B. CONCLUSION: It was found that N2O emission was related to application of both nitrogen fertilizer type and biochar. In particular, the N2O reduction effect was the highest in the corn field incorporated with biochar when oil cake was applied to the soil.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2961-2966
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• 2007

When the pressure at the weak spot established at a certain part of a high pressure vessel or piping system exceeds a design pressure, this weak spot is burst, and the pressurized gas emitted through the weak spot will cause a compression wave system. In this connection, in the present study, an experimental study by using a conventional shock tube facility is performed to estimate the effects of the material of diaphragm, curvature radius and thickness of materials on the valve opening time in diaphragm. Pressure sensor having 500kHz in natural frequency is installed at 35mm downstream of the rupture diaphragm to measure the static pressure history of propagating and being accumulated compression wave. 4 kinds of materials are used as diaphragm that is aluminium, copper, stainless steel and zinc. The diaphragm radii of curvature R are ${\infty}$, 120mm and 60, respectively. And the depth for $90^{\circ}$ groove is 0.04mm. It is found that the smaller the tensile strength and elongation of the rupture diaphragm is, the smaller the radius of curvature of the rupture diaphragm is, and for the same conditions the thinner the thickness of the rupture diaphragm is, the shorter the valve opening time becomes. Also, the tensile strength, elongation and the radius of curvature of the rupture diaphragm for the same conditions are smaller, the maximum pressure rise caused by the coalescences of the compression wave is smaller. Finally the pressure ratio is higher, the valve opening time is shortened and gradient of pressure increment is more steepen.

• Journal of the Korean institute of surface engineering
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• v.42 no.6
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• pp.267-271
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• 2009

Multicomponent transparent conducting oxide films were deposited on glass substrates at 150 by dual magnetron sputtering of AZO and ITO targets. In the case of mixing a limited amount of ITO (10W), resistivity of TCO films was significantly increased compared to the AZO film; from $3.5{\times}10^{-3}$ to $9.7{\times}10^{-3}{\Omega}{\cdot}cm$. Deterioration of the electrical conductivity is attributed to the decreases in carrier concentration and Hall mobility. Improvement of the conductivity could be obtained for the films prepared with ITO powers larger than 40 W. The lowest resistivity ($\rho$) of $7.3{\times}10^{-4}{\Omega}{\cdot}cm$ was achieved when ITO power was 100 W. Effects of $H_2$ incorporation on the electrical and optical properties of AZO-ITO films were investigated in this work. Addition of small amount of hydrogen resulted in the increase of carrier concentration and the improvement of electrical conductivity. It is apparent that the roughness of AZO-ITO films decreases dramatically after the transition of microstructure from polycrystalline to amorphous phase, which gives practical advantages such as an excellent uniformity of surface and a high etching rate. AZO-ITO films grown at sputtering ambient with hydrogen gas are expected to be applicable to optoelectronic devices such as organic light emitting diodes and flexible displays due to their sufficient electrical and structural properties.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.12
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• pp.1027-1034
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• 2016

In this research, experimental study about size effect of solid particles on erosion resistance is presented. A high-density polyethylene particle with a mm-sized diameter is accelerated using a two-stage light gas gun up to Mach number of approximately 3.0. An accelerated particle impacts aluminum alloy such as Al1050 and Al6061 T6, and infrared windows such as ZnS and sapphire specimens. For the aluminum alloy, craters that form on the surface of the specimens are measured to characterize the erosion resistance of the material. For the infrared windows, repetitive tests are conducted until a linear or circumferential crack is found to create damage threshold curves that define a material's erosive resistance. From the comparison of test data for various sizes of high-density polyethylene particles, it is found that erosion resistance of material is linearly dependent on the size of particles.

• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.1
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• pp.143-148
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• 2007

The objective of this study was to investigate the proper conditions of calcination and calcium extraction from powdered oyster shell. The physical characteristics such as particle size distribution, surface morphology, and thermal gravity were examined. The following result were obtained. As the powdered oyster shell was ignited in high temperature of $650^{\circ}C$ to $950^{\circ}C$, the calcination reactions was effectively progressed. The amount of weight loss during calcination would be matched with the generation of carbon dioxide gas. In the calcination of powdered oyster shell, the amount of weight loss increased according to the increased of calcination temperature and the decrease of mean particle size. It was founded that the proper temperature and retention time of calcination was $850^{\circ}C$ and 40 minute. In the extraction of calcium into liquid form using acid addition, the calcination oyster shell was more effective than the non-calcinated shell. The liquid calcium extraction technique using the calcinated oyster shell needed more researches considering cost evaluation.

• Applied Chemistry for Engineering
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• v.10 no.7
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• pp.1035-1040
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• 1999

Photocatalytic degradation of trichloroethylene has been carried out with UV-illuminated $TiO_2$-coated pyrex reactor in gas phase. Three commercial $TiO_2$ oxides were used as catalysts. The effect of reaction conditions, initial concentration of trichloroethylene, concentration of oxidant and light intensity on the photocatalytic activity were examined. Anatase-type catalyst showed higher activity than rutile-type, but P-25 catalyst showed the highest activity. The degradation rate increased with the decrease of flow rate and initial trichloroethylene concentration. It was preferable to use air as an oxidant. In addition, reactants with the water vapor decreased the activity and the degradation rate increased with the increase of light intensity, but it was very low with solar light. Photocatalytic deactivation was not observed at low concentration of trichloroethylene.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.5
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• pp.39-45
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• 2009

An experimental research with 2.0 liter 4-cylinder turbocharged diesel engine was carried out to investigate the combustion and emission characteristics for various alternative fuels. The conventional diesel fuel, neat GTL, blends of 80% of GTL and 20% of biodiesel derived from waste cooking oil are utilized without any modification of engine hardware and ECU data. For GTL and blends of GTL/biodiesel fuel, the ignition delay decreased at the same operating conditions, and overall combustion duration increased slightly. Also, the peak cylinder pressure increased for blends of GTL/biodiesel compared to diesel and GTL fuel. THC and CO emissions with blends of GTL/biodiesel compared to other fuels decreased for the low and middle load conditions. But NOx emission increased due to oxygen content in biodiesel. The number concentrations of PM are higher for blends of GTL/biodiesel than other test fuels in the nucleation mode, while it had an opposite tendency in the accumulation mode, which implies more reduction of PM for blends of GTL/biodiesel on the base of mass concentration.

• Journal of Physiology & Pathology in Korean Medicine
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• v.25 no.5
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• pp.934-944
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• 2011

This study was designed to investigate the effects of Kyungohkgo to improve aerobic capacity and eliminate exercise-induced fatigue in high school soccer players. Twenty four subjects were participated and randomly assigned into two groups [KG, Kyungohkgo group (n=12); PG, Placebo control group (n=12)]. Two groups were completed treadmill exercise protocol using graded exercise test at before and after experimental treatment of 4 weeks. The $VO_2$max and endurance time were measured by gas analysis and heart rate (HR) was measured by polar system at pre, post 0, post 5, post 15, post 30 and post 60 minutes. Blood samples were collected to analyze blood components. 1. The $VO_2$max was significant increased in the group of after intake Kyungohkgo compared to the group of after intake placebo (p<.05). 2. The HR was significant decreased in the group of after intake Kyungohkgo compared to the group of after intake placebo during recovery time at post 5 mins(p<.05), 30 mins(p<.01), 60 mins(p<.01). 3. Weight, body mass index, percent body fat, anaerobic threshold, endurance time, blood lactate concentrate, lactate dyhydrogenase, creatine kinase, serum glutamic oxaloacetic transaminase, serum glutamic pyruvic transaminase, other energy sources(total-cholesterol, triglyceride, high density lipoprotein-cholesterol, low density lipoprotein-cholesterol, creatinine) and electrolyte (Na, K, Cl) were shown no significant differences between groups. These results suggested that Kyungohkgo can be used as ergogenic aids to improve aerobic capacity and eliminate exercise-induced fatigue.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.6
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• pp.598-603
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• 2014

The level of nitrous oxide ($N_2O$), a long-lived greenhouse gas, in atmosphere has increased mainly due to anthropogenic sources, especially application of nitrogen fertilizers. Quantifying $N_2O$ emission in the agricultural field is essential to develop National inventories of greenhouse gases (GHGs) emission. The objective of this study was to develop emission factor to estimate direct $N_2O$ emission from agricultural field by measuring $N_2O$ emissions in the red pepper cultivating field from 2010 to 2012. Emission factor of $N_2O$ calculated from accumulated $N_2O$ emission, nitrogen fertilization rate, and background $N_2O$ emission was $0.0086{\pm}0.00043kg$ $N_2O-N\;kg^{-1}$ N resulted from three year experiment of the research sites. More extensive studies need to be conducted to develop $N_2O$ emission factors for other upland crops in the various regions of Korea because $N_2O$ emission is influenced by many factors including climate characteristics, soil properties, and agricultural practices.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.1
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• pp.39-45
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• 2014

Various approaches have been tried to reduce the emission of carbon dioxide in paper industry. One of important approaches is to use PCC manufactured from emission gas as a filler. However, it was recognized that PCC is inferior to other fillers in the paper strength properties of view. Therefore, pretreatment of PCC with pulp powder was tried to mitigate the strength reduction of paper. Pretreatment of PCC with pulp powder improved the bulk(7.4~12.9%) and air permeability(24.8~42.98%), but there is no significant change in opacity. Tensile index, burst index and stiffness were decreased by the use of pretreated PCC with pulp powder. Anionic and cationic PAM were used as a additive for PCC pretreatment in order to improve strength properties. There was no significant change in bulk in all kinds of PAM used in this study. Most strength properties were improved by the pretreatment of PCC with the anionic and cationic PAM and pulp powder, although the opacity and stiffness were more or less decreased.