• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.167-171
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• 2009

We conducted performance test of a 350 kW class wood pellet boiler installed at a dormitory whose total area is $1,354\;m^2$. The maximum heating capacity of the boiler is 350 kW(300,000 kcal/kg). The wood pellet boiler consists of 3 parts; boiler, hot water storage tank and wood pellet storage tank. In testing the boiler, we shut off hot water utility supply and open up floor heating water system in order to measure exact value of the heating output of the wood pellet boiler. To determine the efficiency and heating output of the wood pellet boiler, we measured mass flow rate of wood pellet, the lower heating value(LHV) of the wood pellet, mass flow rate and temperature of water for floor heating and so on. We measured the mass flow rate of fuel, wood pellet with respect to rotational speed of auger, wood pellet feeding screw. We also measured the flue gas concentration of the wood pellet boiler by using a gas analyser. The result shows that the efficiency of the wood pellet boiler is 80.6% based on lower heating value at 124 kW of heating output. At this condition, O2 concentration of the flue gas is 6.0%, CO and NOx concentrations are 85 and 102 ppm.

• Journal of the Korean Society of Safety
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• v.14 no.1
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• pp.73-77
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• 1999

In this study, $SO_2$ and $NO_2$ reduction have been investigated by using coil type plasma reactor. The experiments have been carried out changing discharge power, gas flow rate frequency and electrode style to obtain the decomposition rate. Decomposition rates of $SO_2$ and $NO_2$ were obtained 20~98% at gas flow rate 100ml/min~1,000ml/min and discharge power 5~25w respectively. The energy efficiency is very good at the high frequency power. The decomposition rate of $SO_2$ for 5kHz power supply is only 90%, but for 10kHz power supply is very high, more than 98% for 15w. The decomposition rate is increasing according to the residence time or the power consumption of the discharge. About 15W discharge power for 17$cm^2$ reactor is necessary to obtain the decomposition rate of $SO_2$ and $NO_2$ of more than 85% or 98%. From these experiments, the consumption power of the decomposition rate of 98% in 300ppm $NO_2$ gas in nitrogen gas proved to be 18W and 300ppm $SO_2$ gas to be 15w.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.248-249
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• 2007

The $V_{1.9}W_{0.1}O_5$ thin films deposited on Pt/Ti/$SiO_2$/Si substrates by RF sputtering method exhibited fairly good TCR and dielectric properties. It was found that film crystallinity, dielectric properties, and TCR properties were strongly dependent upon the annealing temperature. The dielectric constants of the $V_{1.9}W_{0.1}O_5$ thin films annealed at $300^{\circ}C$ were 37.7, with a dielectric loss of 2.535, respectively. Also, the TCR values of the $V_{1.9}W_{0.1}O_5$ thin films annealed at $300^{\circ}C$ were about -3.7%/K.

• Food Science and Preservation
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• v.13 no.3
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• pp.344-350
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• 2006

Soaking and drying were studied for seven grains and legumes including glutinous rice, brown rice, glutinous brown rice, glutinous barley, Seoritae, Heuktae and red bean to improve taste of cooked mixed grams and make easy to cook then Seoritae and Heuktae showed the highest water absorption and the rest were in the order of glutinous barley, glutinous rice, milled rice, brown glutinous rice, brown rice, and red bean. In regards with water absorption index by soaking temperature, the higher the temperature showed, the more water absorption and the shorter time to reach the water absorption balance, the more grinding legumes. showed the more water absorption and the shorter time to reach to the water absorption balance. The soaked samples were dried at mom temperature $30^{\circ}\C,\;50^{\circ}\C$, and microwave 300 W, 700 W and 1000 W power. As a result 700 W drying method br microwave can dry samples in the shortest time without damage to the samples. Therefore, it was considered as the best pretreatment conditions for mixed stains to dry with 700 W microwave after one-hour soaking at $30^{\circ}C$.

• Journal of the Korean Institute of Landscape Architecture
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• v.28 no.4
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• pp.21-28
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• 2000

This study is conducted to analyze effects of soil moisture on the growth of maple(Acer palmatum) under indoor low light intensity. Maples grew under three different light intensities such as sunny place(average 353.2W/$m^2$), half shade(average 7.7 W/$m^2$) and shade/(average 1.9W/$m^2$).Under half shady and shady condition, each 24 planters(2 maples planted in each planter) were used and divided into 3 groups treated with different watering points. Three levels of soil water potential were set for watering points, such as -200mbar, -300mbar or -500mbar. Under sunny condition, there were only group of 8 planters, as comparison. Watering was applied when soil water potentials reached -500maber. The results of plant growth experiment are as followed. 1. Under the shady condition, 32 maples died among 48 maples for 7 months. 9 maples survived, watered at soil water potential -200mbar, 5maples at -300mbar and 2maples at -500mbar. 2. Leaf water content ratios were higher under lower light intensity. For the cell wall became thinner under lower light intensity. 3. Maples in shady were easy to die due to having thin cell wall, therefore they were easy to loss the turgor pressure. 4. In case of half shady condition, the group, watered at soil water potential -200mbar, had much smaller amount of rootlet than -300mbar, because there were excessive soil water. The group, watered at soil water potential -500mbar, had smaller amount of rootlet than -300mbar and there was a remarkable difference in leaf water potential in spite of nearly same soil water potential, because leaves received the water stress under lower soil water potential. 5. When maples grew soundly, the leaf water potential was largely influenced by the soil water potential.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.6
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• pp.419-427
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• 2009

To test applicability for continuous flow treatment of ultrasound technology, sonolysis of TCE aqueous solution using 584 kHz multi irradiation reactor was performed under batch and continuous flow conditions. Under batch condition (3 and 4 sides irradiation, 600 W), first order degradation rate constant of TCE was higher under 4 sides than 3 sides irradiation conditions, while the generation of $H_2O_2$ and chloride was similar under both irradiation conditions. Under continuous flow condition with 4 sides irradiation, removal efficiencies of TCE in steady-state were decreased from 83 to 48% with increasing flow rate from 67 to 300 mL/min at 600 W, and were increased from 14 to 75% with increasing acoustic power from 100 to 600 W at 100 mL/min. Removal efficiency of TCE in groundwater was decreased 10% compared to in distilled water at 100 mL/min and 600 W.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.299-300
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• 2012

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.4
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• pp.290-298
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• 2018

Herein, an S-band internally-matched power amplifier that shows a power capability of 300 W in a Long Term Evolution(LTE) band 7 is designed and fabricated using a CGHV40320D GaN HEMT from Wolfspeed. Based on the nonlinear model, the optimum source and load impedance are extracted from the source-pull and load-pull simulations at the fundamental and harmonic frequencies, and the harmonic impedance tuning circuits are implemented inside a ceramic package. The internally matched power amplifier, which is fabricated using a thin-film substrate with a high relative permittivity of 40 and an RF35TC PCB substrate, is measured at the pulsed condition with a pulse period of 1 ms and a duty cycle of 10%. The measured results show a maximum output power of 257~323 W, a drain efficiency of 64~71%, and a power gain of 11.5~14.0 dB at 2.62~2.69 GHz. The LTE-based measurement shows a drain efficiency of 42~49% and an ACLR of less than -30 dBc(excluding 2.62 GHz) at an average power of 79 W.

• Journal of Korea Foundry Society
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• v.9 no.4
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• pp.294-300
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• 1989

• KIPE Magazine
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• v.27 no.2
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• pp.36-43
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• 2022