• Journal of Magnetics
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• v.18 no.1
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• pp.9-13
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• 2013

Shielding effects in conductive and magnetic materials were investigated as a function of properties, thickness and diameter. In this work, evaluations on passive conductive and magnetic shield specimens were achieved through experimentation set-up using 50 Hz single and three phase induction field sources. Analysis on material microstructure properties and characteristics of shielding specimens were performed with the use of vibrating sample magnetometer (VSM) and field emission scanning electron microscopy (FESEM). An induction field at $136{\mu}T$ of single phase system and $50{\mu}T$ of three phase systems were observed to the shield specimens with the thickness ranged of 0.2 mm to 0.4 mm. It is observed that shield specimen efficiency becomes inversely proportionate to the increment of induction fields. The decrease was attributed to the surface structure texture which relates to the crystallization and non-crystallization geometrical effects.

• Journal of Environmental Science International
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• v.19 no.2
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• pp.217-227
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• 2010

This paper was studied $CO_2$ respiration rate with physicochemical properties of soils at wetland, paddy field and forest in Nongju-ri, Haeryong-myeon, Suncheon city, Jeollanam-do. Soil temperature and $CO_2$ respiration rate were measured at the field, and soil pH, moisture and soil organic carbon were analyzed in laboratory. Field monitoring was conducted at 6 points (W3, W7, W13, W17, W23, W27) for wetland, 3 points (P1, P2, P3) for paddy field and 3 points (F1, F2, F3) for forest in 10 January 2009. $CO_2$ concentrations in chamber were measured 352~382 ppm for wetland, 364~382 ppm for paddy field and 379~390 ppm for forest, and the average values were 370 ppm, 370 ppm and 385 ppm, respectively. $CO_2$ respiration rates of soils were measured $-73{\sim}44\;mg/m^2/hr$ for wetland, $-74{\sim}24\;mg/m^2/hr$ for paddy field and $-55{\sim}106\;mg/m^2/hr$ for forest, and the average values were $-8\;mg/m^2/hr$, $-25\;mg/m^2/hr$ and $38\;mg/m^2/hr$. $CO_2$ was uptake from air to soil in wetland and paddy field, but it was emission from soil to air in forest. $CO_2$ respiration rate function in uptake condition increased exponential and linear as soil temperature and soil organic carbon. But, it in emission condition decreased linear as soil temperature and soil organic carbon. $CO_2$ respiration rate function in wetland decreased linear as soil moisture, but its in paddy and forest increased linear as soil moisture. $CO_2$ respiration rate function in all sites increased linear as soil pH, and increasing rate at forest was highest.

• Journal of the Korean Society of Combustion
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• v.21 no.2
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• pp.1-6
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• 2016

To meet the Tier-4 emission standard, a variety of combustion technology in the field of off-road engine has been applied in conjunction with the engine after treatment technology. In this study, as the basis study for applying VGT and HPL EGR to 3.6 L CRDi engine, exhaust gas characteristics and fuel economy characteristics are confirmed in accordance with VGT and EGR operating conditions. Consequently, in the EGR applicable conditions, 60% VGT vane duty condition was confirmed that the trade-off characteristics between NOx and smoke are advantageous. In addition, in view of BSFC, VGT vane duty is considered desirable to control at around 50%.

• Journal of Animal Science and Technology
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• v.59 no.6
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• pp.14.1-14.9
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• 2017

Background: Garlic and its constituents are reported to have been effective in reducing methane emission and also influence glucose metabolism in body; however, studies in ruminants using garlic leaves are scarce. Garlic leaves contain similar compounds as garlic bulbs, but are discarded in field after garlic bulb harvest. We speculate that feeding garlic leaves might show similar effect as garlic constituents in sheep and could be potential animal feed supplement. Thus, we examined the effect of freeze dried garlic leaves (FDGL) on rumen fermentation, methane emission, plasma glucose kinetics and nitrogen utilization in sheep. Methods: Six sheep were fed Control diet (mixed hay and concentrate (60:40)) or FDGL diet (Control diet supplemented with FDGL at 2.5 g/kg $BW^{0.75}$ of sheep) using a crossover design. Methane gas emission was measured using open-circuit respiratory chamber. Plasma glucose turnover rate was measured using isotope dilution technique of [$U-^{13}C$]glucose. Rumen fluid, feces and urine were collected to measure rumen fermentation characteristics and nitrogen utilization. Result: No significant difference in rumen fermentation parameters was noticed except for rumen ammonia tended to be higher (0.05 < P < 0.1) in FDGL diet. Methane emission per kg dry matter ingested and methane emission per kg dry matter digested were lower (P < 0.05) in FDGL diet. Plasma glucose concentration was similar between diets and plasma glucose turnover rate tended to be higher in FDGL diet (0.05 < P < 0.1). Nitrogen retention was higher (P < 0.05) and microbial nitrogen supply tended to be higher (0.05 < P < 0.1) in FDGL diet. Conclusion: FDGL diet did not impair rumen fermentation, improved nitrogen retention; while absence of significant results in reduction of methane emission, glucose turnover rate and microbial nitrogen supply, further studies at higher dose would be necessary to conclude the merit of FDGL as supplement in ruminant feedstuff.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.3
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• pp.90-101
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• 2009

An objective of this study is to suggest a procedure to evaluate vehicle emissions regardless of the driving pattern. Field experiments using portable emission measurement system were conducted under the real world driving cycle. Standardized average for NOx, $CO_2$ emission and fuel consumption rates were calculated while the vehicle specific power distribution within each vehicle speed bin was taken into consideration. Composite emission factor and fuel economy, which were obtained based on the standardized average results and traffic statistics, showed good similarity to those acquired through the conventional chassis dynamometer tests qualitatively as well as quantitatively. Considering that a conventional method obviously has a limitation to reflect various characteristics of the real world, the new approach suggested in this study can be used as an alternative procedure to collect more specific data to establish the mobile emission factors.

• Journal of the Korean Society of Combustion
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• v.17 no.1
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• pp.58-65
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• 2012

The influence of magnetic field on propane and acetylene diffusion flames have been experimentally investigated using an electromagnetic system. Periodically induced magnetic field having various frequencies and duty ratios was established in square wave form. The maximum intensity and gradient of magnetic field were 1.3 T and 0.27 T/mm, respectively. The width of a propane flame was reduced up to 4.5% and the brightness was enhanced up to 25% when the magnetic field was induced. The soot emission from an acetylene flame was ceased when magnetic field was induced. The alteration of flow field, which is due to the paramagnetic characteristics of oxygen molecule, is most likely to be responsible for the change in flame size and brightness. The effect of magnetic field on diffusion flames, which competes with the gravitational effect, was more apparent from a smaller size flame. The magnetic field effect, therefore, could be important under microgravity conditions. Since the time required to alter the flow field must be finite, the magnetic field effect is likely to be less significant for a periodically oscillating magnetic field at a high frequency or having a small duty ratio.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.5
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• pp.432-436
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• 2006

The $ZnGa_2O_4$ and Mn, Cr-doped $ZnGa_2O_4$ Phosphors were synthesized through conventional solid state reactions. The XRD patterns show that the $ZnGa_2O_4$ has a (3 1 1) main peak and a spinel phase. The emission wavelength of $ZnGa_2O_4$ showed main peak of 420 nm and maximum intensity at the sintering temperature of $1100^{\circ}C$. In the crystalline $ZnGa_2O_4$, the Mn shows green emission (510 nm, $^4T_1-^6A_1$) with a quenching concentration of 0.6 mol%, and the Cr shows red emission (705 nm, $^4T_2-^4A_2$) with a quenching concentration of 2 mol%. These results indicate that $ZnGa_2O_4$ Phosphors hold promise for potential applications in field emission display devices with high brightness operating in full color regions.

• Journal of the Korean Vacuum Society
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• v.16 no.6
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• pp.414-423
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• 2007

Field Emission Display(FED) has significant advantages over existing display technologies, particularly in the area of small and high quality display. In order to test the feasibility of fabricating the System-on-Chip(SOC) with FED, we conducted the experiment to use the p-n junction as an electron beam source for the flat panel display. A novel structure was constructed to form p-n junctions by generating inversion layer with the electric field from the cantilever style gate. When we applied more than 220V at the cantilever style gate which has a height of $1{\mu}m$, avalanche breakdown onset was successfully achieved. The characteristics was compared with the electron emission from the ultra shallow junction in the avalanche region. The experiment result and the future direction were discussed.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.12
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• pp.65-71
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• 1996

A novel lateral field emitter triode has been designed and fabricated. It has self-vacuum environmets and low turn-on voltage, so that the chief problems of previous field emission devices such as additional vacuum sealing process and high turn-on voltage are settled. An in-situ vaccum encapsulation empolying recessed cavities by isotropic RIE (reactive ion etch) method and an electron beam evaporated molybdenum vacuum seals are implemented to fabricate the new field emitter triode. The device exhibits low turn-on voltage of 7V, stabel current density of 2.mu.A/tip at V$_{AC}$ = 30V, and high transconductance (g$_{m}$) of 1.7$\mu$S at V$_{AC}$ = 22V. The superb device characteristics are probably due to sub-micron dimension device structure and the pencil type lateral cathode tip employing upper and lower LOCOS oxidation.

• Journal of Korean Society for Atmospheric Environment
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• v.29 no.5
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• pp.601-614
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• 2013

The commercial charcoal kiln was projected the largest source of biomass burning sector in Korea. Commercial charcoal kiln was operated to emit air pollutants into the air without any air pollution prevention equipment. The object of this field survey was to understand characteristics of air pollutants concentration and emission factors and to provide preliminary data for effective processor from oak charcoal manufacturing process. As result of field survey, TSP, $PM_{10}$ and $PM_{2.5}$ concentration from charcoal kiln were 400~37,000 $mg/m^3$. These values were over the 100 $mg/m^3$ in TSP, this value was effluent quality standard of Clean Air Conservation Act. The average concentration of CO, $SO_2$ and TVOC were 2~5%. 0~110 ppm and 820~10,000 ppm respectively. The emission factors were 42.4 g-PM/kg-oak in TSP, 40.3 g-PM/kg-oak in $PM_{10}$, 38.2 g-PM/kg-oak in $PM_{2.5}$, 182.5 g-CO/kg-oak, 1.0 g-NO/kg-oak, $SO_2$ 0.2 g-$SO_2/kg$-oak and 104.4 g-TVOC/kg-oak. The part of commercial charcoal kiln had air pollution prevention equipment but it was difficult to work properly. Much wood tar excreted in exhaust emissions from oak charcoal manufacturing process. This wood tar was cause of many troubles sticking in the air pollutant prevention equipment. For handling particulate matters and gaseous air pollutants from oak charcoal manufacturing process in biomass burning, air pollutant prevention equipment design and management needs preprocessor for removal wood tar.