• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.250-251
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• 2009

For the fabrication of a multilevel resist (MLR) based on a very thin amorphous carbon (a-C) layer an $Si_{3}N_{4}$ hard-mask layer, the selective etching of the $Si_{3}N_{4}$ layer using physical-vapor-deposited (PVD) a-C mask was investigated in a dual-frequency superimposed capacitively coupled plasma etcher by varying the following process parameters in $CH_{2}F_{2}/H_{2}/Ar$ plasmas : HF/LF powr ratio ($P_{HF}/P_{LF}$), and $CH_{2}F_{2}$ and $H_2$ flow rates. It was found that infinitely high etch selectivities of the $Si_{3}N_{4}$ layers to the PVD a-C on both the blanket and patterned wafers could be obtained for certain gas flow conditions. The $H_2$ and $CH_{2}F_{2}$ flow ratio was found to play a critical role in determining the process window for infinite $Si_{3}N_{4}$/PVDa-C etch selectivity, due to the change in the degree of polymerization. Etching of ArF PR/BARC/$SiO_x$/PVDa-C/$Si_{3}N_{4}$ MLR structure supported the possibility of using a very thin PVD a-C layer as an etch-mask layer for the $Si_{3}N_{4}$ layer.

• Korean Journal of Organic Agriculture
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• v.11 no.4
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• pp.93-102
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• 2003

This research was made to determine the optimum mixing ratio cattle manure and food waste investigating the effect that gets the growth and reproductive efficiency of earthworm and productivity of earthworm casts at processing process when handled cattle manure and food waste by vermicomposting, in order to establish the treatment system of organic wastes by vermicomposting. Survival ratio of earthworm was highest in the mixing ratio 80~100% : 20~0% of cattle manure and food Waste, and the increasing ratio was highest in cattle manure 100%, and the number of young worms, the weight of young worms and the productivity of earthworm casts in plots more than the mixing ratio 60% of cattle manure were significantly higher than in the other treatment plots(p<0.05). Total nitrogen and carbon contents in earthworm cast were decreased when rearing time of earthworm was increased. Carbon and nitrogen rate(C/N) of earthworm cast in plots more than the mixing ratio 80% of cattle manure was significantly higher than in the other treatment plots(p<0.05). pH in earthworm cast was higher than that in residual matter. The contents of electrolytic conductivity in the higher mixing ratio of food waste were significantly higher than those in the other treatment plots(p<0.05).

• Solar Energy
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• v.9 no.3
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• pp.44-54
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• 1989

Heat transfer phenomena during inward melting process of the phase change material were studied experimentally. N-docosane paraffin [$C_{22}H_{46}$] is used for phase change material and its melting temperature is $42.5^{\circ}C$. Experiments were performed for melting of an initially no-sub cooled or subcooled solid in a horizontal cylinder, in order to compare and investigate the radial temperature distribution, ratio of melting and melted mass, various energy components stored from the cylinder wall, figure of the melting front in the horizontal cylinder. The solid-liquid interface motion during phase change was recorded photographically. The experimental results reaffirmed the dominant role played by the conduction at early stage, by the natural convection at longer time during inward melting in the horizontal cylinder. Ratio of melting and melted mass are more influenced by wall temperature, rather than by the initial temperature of solid. The latent energy is the largest contributor to the total stored energy.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.5
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• pp.219-226
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• 2003

The fatigue crack growth behavior of the SA516/60 steel used for pressure vessels was examined experimentally at room temperatures $25^{\circ}C$,$-30^{\circ}C$, $-60^{\circ}C$, $-80^{\circ}C$, $-100^{\circ}C$ and $-120^{\circ}C$ with stress ratio of R=0.05, 0.1 and 0.3. fatigue crack propagation rate da/dN related with stress intensity factor range $\Delta$K was influenced by stress ratio in stable than fatigue crack growth (Region II) with an increase in $\Delta$K. The resistance of fatigue crack growth at low temperature is higher compared with that at room temperature, which is attributed to the extent of plasticity-induced by compressive residual stress according to the cyclic loads. Fractographic examinations reveal that the differences of the fatigue crack growth characteristics between room and low temperatures are explained mainly by the crack closure and the strengthening due to the plasticity near the crack tip and roughness of the crack faces induced.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.359-365
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• 2002

The fatigue crack growth behavior of the SA516/60 steel which is used for pressure vessels was examined experimentally at room temperature $25^{\circ}C,\;-30^{\circ}C,\;-60^{\circ}C,\;-80^{\circ}C,\;-100^{\circ}C$ and $-120^{\circ}C$ with stress ratio of R=0.05, 0.1 and 0.3. Fatigue crack propagation rate da/dN related with stress intensity factor range ${\Delta}K$ was influenced by stress ratio in stable of fatigue crack growth (Region II) with an increase in ${\Delta}K$. The resistance of fatigue crack growth at low temperature is higher compared with that at room temperature, which is attributed to tile extent of plasticity-induced by compressive residual stress according to the cyclic loads. Fractographic examinations reveal that the differences of the fatigue crack growth characteristics between room and low temperatures are mainly explained by the crack closure and the strengthening due to the plasticity induced and roughness induced.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.2
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• pp.124-129
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• 2000

The purpose of this study is to estimate the degradation rate and process efficiency of the composting according to the salinity concentration. The samples of food waste for this study were collected in Pocheon-Gun, Kyungki-Do. The collected samples were adjusted to the optimum range of moisture content, pH and C/N ratio. After that, adding the saline, the samples with 3 different salinity concentrations(1%, 5% and 10%) were made. Then each sample was fed into the reactor with temperature controller. During the aerobic composting process, the change of the physical and chemical properties of the sample as temperature, pH, C/N ratio and $CO_2$ and $O_2$ concentration in the reactor were measured. From the experiment of this study, the result are following. The highest temperatures are $59^{\circ}C$ at RUN 1(1% salinity conc.), $49^{\circ}C$ at RUN 2(5% salinity conc.) and $45^{\circ}C$ at RUN 3(10% salinity conc.). The change of $CO_2$ production and $O_2$ consumption have the positive correlation with the change of the temperature. $CO_2$ production and $O_2$ consumption are peaked at the low salinity concentration. During composting, Run 1, RUN 2 and RUN 3 are increased pH to 8.9, 8.6 and 7.2 and slowly decreased C/N ratio to 18.9, 19.1 and 22.1 and moisture content to 51.1%, 53.7% and 55.0%, respectively. It is supposed that increasing salinity concentration causes the retarding of the microbial degradation activities during the composting. And for the efficient composting, the salinity concentration in the sample hat to be maintained below 5%.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.5
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• pp.501-510
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• 2006

To investigate the effects of MLSS concentration and influent C/N ratio on the nitrogen removal efficiency of alternately intermittently aerated nonwoven fabric filter bioreactors, the MLSS concentrations of the reactors were maintained at approximately 5,500 mg/L, 10,000 mg/L and 15,000 mg/L, and the influent TCOD/TKN ratio was decreased gradually from 5 to 2 by adding $NH_4Cl$. The influent was prepared by diluting a food waste leachate to a TCOD concentration of about 300 mg/L. The results of the experiment showed F/M ratios less than 0.112 g TCOD/g MLSS-day, average TCOD removal efficiencies of above 95%, and an average observed microbial yield coefficient of 0.283 g MLSS/g COD removed. The nitrification efficiencies were computed to be always better than 96% except one case where the nitrification efficiency was 90.5% when the MLSS concentration and the influent TCOD/TKN ratio was 5,500 mg/L and 2, respectively. The denitrification efficiency deteriorated as the influent TCOD/TKN ratio decreased. The average denitrification efficiency at the MLSS concentration of 10,000 mg/L was 10.7% better than that at the MLSS concentration of 5,500 mg/L, and the denitrification rate improved at a rate of 2.66 mg NL as the MLSS concentration increased by 1,000 mg/L. When the MLSS concentration was 15,000 mg/L, however, the average denitrification efficiency was merely 4.6% higher compared to when the MLSS concentration was 5,500 mg/L, and the denitrification rate increased at a rate of 0.75 mg N/L per 1,000 mg/L MLSS increase. Therefore, no strict proportional relationship was found between MLSS concentration and endogenous denitrification rate. The average alkalinity consumption rate was 3.36 mg alkalinity/mg T-N removed, which is similar to the theoretical value of 3.57 mg alkalinity/mg T-N removed, but the rate increased as the influent TCOD/TKN ratio decreased.

• Korean Journal of Environmental Agriculture
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• v.4 no.2
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• pp.78-87
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• 1985

To investigate the effects of paper sludge, by-products of paper manufactory, on the chemical properties of paddy soil and growth of paddy rice, paper sludges were applied to the pots at the rates of 300, 600, 900 and 1,200㎏/l0a which were either pread-justed C/N ratio to 30 : 1 or not adjusted. The effects were compared with those of control. Seasonal variations of various forms of soil organic nitrogen, the mineralization of organic nitrogen and the contents of soil minerals were analyzed. The results were summarized as follows: 1) The contents of soil organic nitrogen, especially amino sugar-N and amino acid-N, organic matter, CEC and available $SiO_2$ were increased by application of paper sludge compared with that of control. 2) The mineralizations of organic nitrogen after 6 weeks of incubation at $30^{\circ}C$ were 12. 2, 12.6, 15.1, 9.7 and $15.2^{\circ}C$ in the control, 300㎏/l0a sludge treatment, 300㎏/l0a sludge treatment(C/N ratio adjusted), 600㎏/l0a sludge treatment and 600㎏/l0a sludge treatment(C/N ratio adjusted), respectively. 3) Cu and Pb contents in the soil were in the range of $0{\sim}0.2100$ and $0{\sim}0.0013$ ppm, respectively. Cr and Cu in the soil were not detected at all. There were no differences in the contents of all the heavy metals among all the treatments in the soil.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.2
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• pp.248-255
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• 2011

For the environmental friendly soil management on the cultivation of crops in the greenhouse, organic materials, such as the by product-fertilizer derived from livestock manure, rice straw, mushroom media, rice hulls, wood sawdust, and cocopeat, were used as carbon sources adjusting the ratio of carbon to nitrogen to 10, 20, and 30 based on the inorganic soil N. In each C/N ratio of greenhouse soil, watermelon was cultivated in the greenhouse as crop for experiment for the spring and summer of the year and the experimental results were summarized as follows. The concentration of T-C in the organic materials applied were between $289{\sim}429g\;kg^{-1}$, In the C/N ratio of 10, using watermelon as the crop cultivated during the second half of the year in the greenhouse soil, the $NO_3$-N and EC were reduced by 21 to 37%, and 26 to 33%, respectively, except the by product-fertilizer from livestock manure, compared to the soil $NO_3$-N and EC used in the experiment. After the watermelon was cultivated in soils that C/N ratios were controlled as 10, 20, and 30 with wood sawdust adding as carbon sources in the three soils with the different EC values, EC values of the soils were reduced by 33, 42, and 39%, respectively, compared to the soil EC used in the experiment. The weight of watermelon was 10.1-13.4 kg per one unit, and, of the three soils with different EC values. In the soils with three different EC values controlled at C/N ratio of 20, the weight of watermelon was good. The degree of sugar of watermelon were 11.8 to 12.3 Brix, which means that the difference between the treatments was not significant. In conclusion, the C/N ratio of 20 controlled by the proper supply of organic materials according to the representative EC values shown in the greenhouse soils was optimal condition enough to maintain the soil management for the organic culture with the proper nutrient cycling.

• Proceedings of the KSMRM Conference
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• 2001.11a
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• pp.108-108
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• 2001

Purpose： To correlate the histological differentiation of hepatocellular carcinomas (HCCs) with finding on triple contrast-enhanced MR imaging using gadolinium-chelates, superparamganetic ire oxides (SPIO), and mangafodipir trisodium. Method： Ten patients with proven HCC underwent triple contrast-enhanced MRI befo surgical resection. Subjective ratings of the enhancement pattern and degree were compare with the histological grades determined on surgical specimen. Quantitative measurements signal-to-noise ratio (S/N) of the lesion and the lesion-to-liver contrast-to-noise ratio C/N on the enhanced MR images, and the degree of S/N and C/N changes between the unenhanced and enhanced images were also correlated with the histological grades.