• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.32 no.4
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• pp.74-80
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• 2000

A series of studies on nitric-acid pulping of municipal recycled waste papers were carried out to substitute the bleached chemical pulp imported for producing printing paper as well as to use its solidified spent-liquor as fertilizer. The first experiment was carried out to find the optimum treatment conditions such as pulp consistency, nitric acid charge and temperature in $HNO_3$-alkali pulping process. The results obtained were as follows: 1. Some selective delignification of OCC pulp was conducted by $HNO_3$-alkali process. The higher the temperature and concentration of nitric acid, the lower the pulp yield and kappa number of treated pulp. while its brightness was increased. 2. The higher consistency required the stronger mixing in case of more than 5% pulp. 3. In the laboratory, the suitable $HNO_3$-treating condition seemed to be less than 6% consistency, lower than 500% $HNO_3$charge on pulp and lower than $100^{\circ}C$ in cooking temperature. 4. The spent liquor with 1.77% N-content seemed to be slow-release nitrogen fertilizer suitable for agriculture.

• Resources Recycling
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• v.10 no.6
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• pp.35-42
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• 2001

A study was conducted in order to remove Poly vinyl chloride (PVC) from granular plastic mixture by using Air Table. The motion of plastic particle on Air Table was investigated, and separation test on the plastic mixture with the mixing ratio of PVC 10% and PE 90% was conducted. At the optimum condition obtained from this study, that is frequency of 9.2Hz, air velocity of 1.05 m/sec, End-slope of $7.5 ^{\circ}$, Side-slope of $1^{\circ}$, Feeding speed of 450 g/min, etc., we could separate the PE-PVC mixture to PE (99.96% grade and 98.9% yield) and PVC (88.7% grade and 99.6% yield).

• Journal of the Korean institute of surface engineering
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• v.35 no.1
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• pp.17-32
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• 2002

Electroplating methods by molten salts and non-aqueous melts were employed for aluminium coating on STS 316L stainless steel. After coated with Ni or non-coated surface on stainless steel, Al pulse plating was carried out in two different types of electrolytes at room temperature. The Al layer from $AlCl_3$-TMPAC melts could not obtain appreciable thickness for engineering application due to chemical reactions between deposits and moisture of air. However, The Al coating by pulse plating in the Ethylbenzene-Toluene-$AlBr_3$ systems was found to be solid coating layer with a few $\mu\textrm{m}$ scale. The conductivity of Ethylbenzene-Toluene-$AlBr_3$ electrolyte was as functions of time and agitation. By seven days exposure after mixing of the electrolyte, Al-deposited layer shows uniform and near by pore-free with high current density (higher than 30mA/$\textrm{cm}^2$). The roughness and imperfection of coating layer were decreased with a increasing agitation speed. It was found that the optimum condition for the Al pulse plating on the 316L stainless steel was a 400mA peak current, duty cycle, $t_{on}$ $t_{ off}$=3ms/1ms, and a current density of 30mA/$\textrm{cm}^2$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.1
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• pp.49-56
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• 2000

The 2-O-$\alpha$-D-glucopyranosyl L-ascorbic acid (AA-2G) which was enzymatically glucosylated with the cyclodextrin glucanotransferase (CGTase) [EC 2.4.1.19] from Bacillus sp. JK-43 has been reported previously. The presnet experiments examined the optimal conditons for the productio of AA-2G from AA and soluble starch, and characterized the properties of the CGTase from Bacillus sp. JK-43. The reaction mixture for the maximal production of AA-2G was followings; 12% total substrate concentration, 1,400 usits/mL of CGTase and a mixing ratio of 2 : 3(g or AA : g of soluble starch). Under this condition, 1.76mM of AA-2G, which corresponded to 2.53% yield based on AA, was produced after incubation for 24hrs at 45$^{\circ}C$ (pH 5.5). The optimum pH and temperature for the CGTase activity were 6.0 and 45$^{\circ}C$, respectively. The enzyme was stable at pH 5.5 to 9.5, and at temperature up to 5$0^{\circ}C$. The thermostability of the enzyme could be enhanced up to 6$0^{\circ}C$ by the addition of 30mM CaCl2.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.4
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• pp.367-372
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• 2002

The vertically well-aligned carbon nanotubes(CNTs) were successfully grown on Ni coated silicon wafer substrate by DC bias-assisted PECVD(Plasma Enhanced Chemical Vapor Deposition). As a catalyst, Ni thin film of thickness ranging from 15~30nm was prepared by electron beam evaporator method. In order to find the optimum growth condition, the type of gas mixture such as $C_2H_2-NH_3$ was systematically investigated by adjusting the gas mixing ratio at $570^{\circ}C$ under 0.4Torr. The diameter of the grown CNTs was 40~200nm and the diameter of the CNTs increased with increasing the Ni particles size. TEM images clearly showed carbon nanotubes to be multiwalled. The measured turn-on field was $3.9V/\mu\textrm{m}$ and an emission current of $1.4{\times}10^4A/\textrm{cm}^2$ was $7V/\mu\textrm{m}$. The CNTs grown by bias-assisted PECVD was able to demonstrate high quality in terms of vertical alignment, crystallization of graphite and the processing technique at low temperature of $570^{\circ}C$ and this can be applied for the emitter tip of FEDs.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.10 no.4
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• pp.304-315
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• 1981

This paper presents, the result of the study for the fluctuant temperature of the out-side air adopting the heat pump system in seoul, Taejean, Taegu, Busan and Jejeu among principle cities in korea for the purpose of checking the heating capacity, Heat pump capacity (outlet capacity), Coefficient of performance and running cost in comparison with the supporting the energy for the boiler's operation. According to the supply temperature changes of the out door coil by the out side air-return air mixing ratio, the Coefficient of performance is increased from 3. 1 to 5.0. Particularly, in Taegu, it is necessary to adopt the heat pump system against the supplement heat supply on the full outside air intake in January of the heating period, and it was recognized that the running cost is cheaper than that of the Boiler use. At the same time, if it is able to get $25\%$ of return air of the inside in the Seoul, it could be saved its costs when we use the supplementary boiler. And I think it is necessary to the development.

• Journal of the Korean Institute of Landscape Architecture
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• v.30 no.6
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• pp.66-78
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• 2003

The purpose of this study was to minimize the forest disturbance around an entry road of a power transmission tower construction site between Taean and Sinsesan, Chungnam. The main study field was classified into existing materials and a GIS, remote sensing analysis, and a field examination. This information was used to identify the most suitable entry road using a degree of green naturality map, eco-naturality map, actual vegetation map, and a forest state map as the existing materials. Also, the study used an normalized difference vegetation index, altitude and slope map in order to make the evaluation materials which used an remote sensing image, and GIS. This data was used to choose an optimum area, and diagnosed the current condition of the vegetation with a field survey of the area. It analyzed vegetation structure, species diversity, the age of trees in a field examination. Subsequently, we proposed four area types based on the analysis results--preservation area, transplantation area, restoration area and development area. As a result, the preservation area was categorized into 8 grades, according to the degree of green naturality, large area of breast diameter at Pinus densiflora community, competition area of Pinus densiflora and Quercus spp. and Quercus spp. community of over 20 years old. A transplantation area established 46 optimum areas according to the GIS analysis and vegetation investigation results. Vegetation restoration plan for disturbance area should be made based on ecological value of existing vegetation to worthwhile area as Quercus spp. mixing forest proposed. The development area selected a ecological worthless place as an artificial forest where Pinus densiflora and Pinus thunbergii growth is poor. This research results suggest that restoration of vegetation will be possible in the real world. Also, ecological restoration guidelines will be made through building and analyzing data base and routine monitoring of transplantation and restoration area.

• Journal of Korean Society of Water and Wastewater
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• v.9 no.3
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• pp.99-107
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• 1995

Various humic substances are widely distributed in natural water body, such as rivers and lakes and cause the yellowish or brownish color to water. The evidence that humic substances are precursors of THMs formation in chlorinated drinking water has been reported m the Jiteratures. For the reason of public health as well as aesthetics, needs for humic substances removal have been increased in the conventional water treatment processes. In this research, the characteristics of aluminium coagulation of humic acids and humic acids were investigated. The optimum pH and coagulants dosage to remove these materials simultaneously by coagulation were alto studied. The results are as followed; 1. UV-254 absorptiometry for measuring the concentration of aquatic humic acids showed good applicability and stable results. 2. The optimal pH range for humic acids removal by aluminium coagulation was 5 to 5.5, however, an increase in aluminium coagulant dosage could enhance the removal rate of humic acids in the wide pH range. 3. Coprecipitation of humic acids in the typical pH range of 6.5 to 8 in water treatment processes may require the sweep coagulation mechanism with the excess aluminium coagulant dosage. 4. Using PAC(poly aluminium chloride) or PASS(poly aluminium silica sulfate) as coagulants was able to expand the operating range for removing humic acids. 5. From the coagulation of humic substances(UV-254) and turbidity at pH range of 5.5 - 6.0 and alum dose of 86 ppm, the removal efficiency of turbidity from the reservoir water was above 90% and that of UV-254 was above 70%. 6. By using the reservoir water, the optimum condition of rapid mixing for simultaneous removal of turbidity and UV-254 absorbance was pH of 5.8 and LAS dose of 86 ppm, in this study.

• Journal of the Korea Organic Resources Recycling Association
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• v.7 no.2
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• pp.93-104
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• 1999

Existing composting system was improved to have a high performance for organic degradation, deodorization and energy reduction. Compared with conventional devices, this developed system uses the heat recovered from platinum catalytic tower by three times heat exchange in which 65% of exhaust gas was recirculated. Evaporation of water was made easy by maintaining negative pressure in entire system. It was possible for reaction to be maintained steadily by microorganism agent. The optimum mixing volume ratio of garbage to sawdust was 15:1 contrary to 20:1 in conventional one. Moreover, aerobic condition was maintained efficiently. Effects obtained by using a inner circulation system were as follows. It was possible to reduce the ammonia causing offensive odor and verified that consumption of electricity cut down to 1/3 with reduction of exhaust gas inflowing. According to this inner circulation, the optimum air flow was $0.44m^3$ to 100kg treatment capacity. The electricity consumption was changed in proportion to inflowing air volume.

• Korean Journal of Materials Research
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• v.24 no.8
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• pp.407-412
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• 2014

Currently, diopside ($MgCaSi_2O_6$) crystal glaze is used frequently for pottery works or in earthen wares, though the process is not straightforward. However, to create and control the positions and sizes of the crystals in desired amounts when making pottery is difficult. To solve this problem, a diopside crystal seed was created at a temperature of $1450^{\circ}C$. After planting this seed in the glaze, a glaze combination and firing process which allows a user to create crystals with the desired position and at the desired size were established. In addition, in order to investigate the creation process of the crystals, the growth patterns of the crystals were observed and examined using Raman spectrography and XRD and SEM analyses. As a result, the optimum synthesis condition of the diopside seed was created by mixing 1 mole of $CaCo_3$, 0.2 mole of $(MgCo_3)_4(MgCoH)_2{\cdot}5H_2O$ and 2 moles of $SiO_2$ and then applying a firing process to the mixture at $1,450^{\circ}C$ for 30 minutes. The optimum glaze content of the seed was 70 % feldspar, 20 % limestone and 10 % $MgCo_3$. For the firing process, it was confirmed that the size of crystal is larger with a longer firing time at $1100^{\circ}C$ by completing a two-hour process at $1280^{\circ}C$. In addition, the diopside crystal has columnar structure and is less than $1{\mu}m$ in size.