• Korean Journal of Environmental Agriculture
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• v.16 no.2
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• pp.170-174
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• 1997

Constructed wetland system was studied to treat wastewater from industrial complex in rural area. Pilot plant at the Baeksuk Nongkong Danzi in Chunahn-City was used for field study. For the DO, the effluent concentration was higher than the influent concentration and it implies that natural reaeration supplies enough oxygen to the system. For the SS, the effluent concentration was consistently lower than the water quality standard even though the influent concentration varied significantly, which showed that SS was removed by the system effectively which is consist of soil and plants. For the BOD and COD, the average removal rate of them were 56% and 43%, respectively, therefore, the effluent concentration could not meet water quality standards when influent concentration was high. The removal rate of BOD and COD can be improved by supplemental treatment in addition to this system if necessary. For the T-N and T-P, the influent concentration of them were lower than the water quality standards than no further treatment was needed. Overall, the result showed that constructed wetland system is a feasible alternative for the treatment of wastewater from industrial complex in rural area. For actual application of this system, further study on design factors including loading rate, removal mechanism, and temperature effects is required to meet water quality standard consistently. Compared to existing systems, this system is quite competitive because it requires low capital cost, almost no energy and maintenance, and therefore, very cost effective.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.4
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• pp.223-231
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• 2012

The purpose of this study is to investigate basically the mechanism of heat transfer by the resolution of complex fluid flow inside a sophisticated designed screw dryer for the treatment of sewage sludge by using numerical analysis and experimental study. By doing this, the result was quite helpful to obtain the design criteria for enhancing drying efficiency, thereby achieving the optimal design of a multiple screw type dryer for treating inorganic and organic sludge wastes. One notable design feature of the dryer was to bypass a certain of fraction of the hot combustion gases into the bottom of the screw cylinder, by the fluid flow induction, across the delicately designed holes on the screw surface to agitate internally the sticky sludges. This offers many benefits not only in the enhancement of thermal efficiency even for the high viscosity material but also greater flexibility in the application of system design and operation. However, one careful precaution was made in operation in that when distributing the hot flue gas over the lump of sludge for internal agitation not to make any pore blocking and to avoid too much pressure drop caused by inertial resistance across the lump of sludge. The optimal retention time for rotating the screw at 1 rpm in order to treat 200 kg/hr of sewage sludge was determined empirically about 100 minutes. The corresponding optimal heat source was found to be 150,000 kcal/hr. A series of numerical calculation is performed to resolve flow characteristics in order to assist in the system design as function of important system and operational variables. The numerical calculation is successfully evaluated against experimental temperature profile and flow field characteristics. In general, the calculation results are physically reasonable and consistent in parametric study. In further studies, more quantitative data analyses such as pressure drop across the type and loading of drying sludge will be made for the system evaluation in experiment and calculation.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.107-108
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• 2008

The spectacular development of AMLCDs, been made possible by a-Si:H technology, still faces two major drawbacks due to the intrinsic structure of a-Si:H, namely a low mobility and most important a shift of the transfer characteristics of the TFTs when submitted to bias stress. This has lead to strong research in the crystallization of a-Si:H films by laser and furnace annealing to produce polycrystalline silicon TFTs. While these devices show improved mobility and stability, they suffer from uniformity over large areas and increased cost. In the last decade we have focused on microcrystalline silicon (${\mu}c$-Si:H) for bottom gate TFTs, which can hopefully meet all the requirements for mass production of large area AMOLED displays [1,2]. In this presentation we will focus on the transfer of a deposition process based on the use of $SiF_4$-Ar-$H_2$ mixtures from a small area research laboratory reactor into an industrial gen 1 AKT reactor. We will first discuss on the optimization of the process conditions leading to fully crystallized films without any amorphous incubation layer, suitable for bottom gate TFTS, as well as on the use of plasma diagnostics to increase the deposition rate up to 0.5 nm/s [3]. The use of silicon nanocrystals appears as an elegant way to circumvent the opposite requirements of a high deposition rate and a fully crystallized interface [4]. The optimized process conditions are transferred to large area substrates in an industrial environment, on which some process adjustment was required to reproduce the material properties achieved in the laboratory scale reactor. For optimized process conditions, the homogeneity of the optical and electronic properties of the ${\mu}c$-Si:H films deposited on $300{\times}400\;mm$ substrates was checked by a set of complementary techniques. Spectroscopic ellipsometry, Raman spectroscopy, dark conductivity, time resolved microwave conductivity and hydrogen evolution measurements allowed demonstrating an excellent homogeneity in the structure and transport properties of the films. On the basis of these results, optimized process conditions were applied to TFTs, for which both bottom gate and top gate structures were studied aiming to achieve characteristics suitable for driving AMOLED displays. Results on the homogeneity of the TFT characteristics over the large area substrates and stability will be presented, as well as their application as a backplane for an AMOLED display.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.5
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• pp.401-412
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• 2016

It is extremely difficult to apply conventional grouting methods to subsea tunnelling construction in the high water pressure condition. In such a condition, the rapid artificial freezing method can be an alternative to grouting to form a watertight zone around freezing pipes. For a proper design of the artificial freezing method, the influence of salinity on the freezing process has to be considered. However, there are few domestic tunnel construction that adopted the artificial freezing method, and influential factors on the freezing of the soil are not clearly identified. In this paper, a series of laboratory experiments were performed to identify the physical characteristics of frozen soil. Thermal conductivity of the frozen and unfrozen soil samples was measured through the thermal sensor adopting transient hot-wire method. Moreover, a lab-scale freezing chamber was devised to simulate freezing process of silica sand with consideration of the salinity of pore-water. The temperature in the silica sand sample was measured during the freezing process to evaluate the effect of pore-water salinity on the frozen rate that is one of the key parameters in designing the artificial freezing method in subsea tunnelling. In case of unfrozen soil, the soil samples saturated with fresh water (salinity of 0%) and brine water (salinity of 3.5%) showed a similar value of thermal conductivity. However, the frozen soil sample saturated with brine water led to the thermal conductivity notably higher than that of fresh water, which corresponds to the fact that the freezing rate of brine water was greater than that of fresh water in the freezing chamber test.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.1
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• pp.23-28
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• 2015

This study was performed to investigate the adequate standard pot and number of plants per tree of raising seeding pot on the foxtail millet transplanting culture in the southern province. Due to the various application of wellbeing-health food recently, for upbringing of the foxtail millet, millet and sorghum in minor cereals, R & D and policy support is being promoted actively. The foxtail millet growing season is so short from 90 to 130 days, and it is large variations for a growth temperature. The main results are as follows. When it comes to foxtail millet transplantation, seedling quality of 406 holes, 200 holes and 162 holes of raising seeding pot type were not all significant, and field rooting percentage is accounted for all 94 to 95%. Yield of a foxtail millet was exposed in 406holes 305 kg/10a>162holes 303 kg> 200holes 302 kg order, and it was no significance between test processing. When it's the raising seeding transplanting culture, in case of pot culture, 406holes pot culture were reduced the bed soil cost 63%, pot 50%, working hours 18% for 200holes pot. Transplanting seedling quality per a foxtail millet transplanting culture method, dry weight was high inclination as transplanting number of plant is less, and field rooting percentage displayed more than all 95%. Yield appeared to 2 plants seedling transplanting 315kg/10a> 3 plants seedling transplanting 304kg>1 plant seedling transplanting 256kg order. The projected cost per the pot-sort on the raising seeding transplanting culture of foxtail millet, the seedling transplanting culture of 406holes was reduced 40% percentages compared to 200holes as 76,230won/10a. As a result, 406holes pot and 2plants seedling transplanting culture, labor-saving culture was possible.

• Journal of Food Hygiene and Safety
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• v.32 no.4
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• pp.284-289
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• 2017

Oxidized polyethylene wax (OPEW) is, one of the food additives, used as a coating agent in citrus fruits and nuts. OPEW is authorized to quantum satis in EU, USA, and is acceptable less than 250 mg/kg in Australia and New Zealand. But OPEW is unauthorized as a food additive in Korea. This study was to establish the analytical method of OPEW and demonstrate the effective application of various food samples. We first conducted to compare the various analytical method including acid value (AV), high temperature gel permeation chromatography (HT-GPC), matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS), gas chromatography flame ionization detector (GC-FID) and fourier transform infrared spectroscopy (FT-IR). This result indicated that FT-IR spectrum of OPEW treated food sample displayed absorption bands for carbonyl group (C=O, $1714cm^{-1}$), ester group (C-O, $1463cm^{-1}$), aliphatic group (C-H, $2916cm^{-1}$). Furthermore, IR spectrum of OPEW treated food sample showed similar tendency with IR spectrum of OPEW standard. Therefore, it is confirmed that analytical method using FT-IR can be detected on analysis of OPEW in food. As a result of monitoring of 111 samples using established analytical method, OPEW was not detected in the food samples.

• Korean Journal of Food Science and Technology
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• v.42 no.5
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• pp.613-619
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• 2010

Three varieties of taro flours (Altoran, Josaengjong, and Jaeraejong) were analyzed to evaluate their nutrient composition and physicochemical properties. Moisture contents of the three taro cultivars varied from 5.74-10.30%. Among the three cultivars, Altoran flour had higher protein and fat contents than other cultivars. There were 17 kinds of amino acids in the three taro flours. The major fatty acids in the three taro flours were linoleic acid (46.5-51.4%), palmitic acid (21.7-25.8%), and oleic acid (12.3-18.7%), and two thirds of the total fatty acids were unsaturated fatty acids. Potassium, phosphorus, magnesium, and calcium were the most plentiful minerals in the three taro flours, and the free sugars were glucose, fructose, and sucrose. The total dietary fiber contents of the three taro flours ranged from 12.97 to 17.60%. From these results, Altoran contained a high level of dietary fiber, minerals, essential amino acids, and free sugars. Jaeraejong showed the highest water absorption index. The water soluble index of Altoran was higher than that of the other cultivars. From the differential scanning calorimeter results, the gelatinization temperatures of the three taro flours were $84.98-89.91^{\circ}C$. The pasting temperature of the three taro flours was from 46.77 to $49.30^{\circ}C$ by rapid visco-analyzer. Among these varieties, Josaengjong had the highest peak viscosity and final viscosity, whereas Altoran had the lowest. These taro cultivars are expected to be potential material for application in taro processed foods, due to their gelatination and pasting properties.

• Applied Microscopy
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• v.38 no.4
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• pp.279-284
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• 2008

The phase change materials have been extensively used as an optical rewritable data storage media utilizing their phase change properties. Recently, the phase change materials have been spotlighted for the application of non-volatile memory device, such as the phase change random access memory. In this work, we have investigated the crystallization behavior and microstructure analysis of In-Sb-Te (IST) thin films deposited by RF magnetron sputtering. Transmission electron microscopy measurement was carried out after the annealing at $300^{\circ}C$, $350^{\circ}C$, $400^{\circ}C$ and $450^{\circ}C$ for 5 min. It was observed that InSb phases change into $In_3SbTe_2$ phases and InTe phases as the temperature increases. It was found that the thickness of thin films was decreased and the grain size was increased by the bright field transmission electron microscopy (BF TEM) images and the selected area electron diffraction (SAED) patterns. In a high resolution transmission electron microscopy (HRTEM) study, it shows that $350^{\circ}C$-annealed InSb phases have {111} facet because the surface energy of a {111} close-packed plane is the lowest in FCC crystals. When the film was heated up to $400^{\circ}C$, $In_3SbTe_2$ grains have coherent micro-twins with {111} mirror plane, and they are healed annealing at $450^{\circ}C$. From the HRTEM, InTe phase separation was occurred in this stage. It can be found that $In_3SbTe_2$ forms in the crystallization process as composition of the film near stoichiometric composition, while InTe phase separation may take place as the composition deviates from $In_3SbTe_2$.

• Korean Journal of Environmental Agriculture
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• v.1 no.1
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• pp.22-30
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• 1982

Water quality of downstream of the Nagdong river, using for agricultural irrigation of the Gimhae plain, were observed. Water temperature, turbidity, residue, pH, BOD, COD, DO, hardness, chloride, sulphate, phosphate, inorganic nitrogenous compounds, sodium, general bacteria, E. coli and heavy metals of the water were investigated at Daejeo, Sikman, Bongrim, Noksan, Machal and Jangyou pumping stations in the Gimhae plain in May, July and October, 1981. The results obtained were as follows; 1) Average value of analyzed components of the water at all sampling sites were 7.8 pH, 6.3 ppm BOD, 6.5 ppm COD, 6.4 ppm DO, 231 ppm hardness, 582 ppm Cl-, 412 ppm $SO_4--$, 2.32 ppm $PO_4---$, 3.8 ppm $NH_4+,\;478\;ppm\;Na+$, 2964 No. /100 ml total coliform, 0.0040 ppm Cd, 0.0066 ppm Pb, respectively. 2) The most heavily polluted site of all investigated ones was Sikman. It seemed to be caused by the vast quantity of wastewater discharged from industrial district in Gimhae city. The next polluted sites were Bongrim, Daejeo and Noksan, and comparatively less polluted sites were Machal and Jangyou, judging from both appearance and physicochemical observation. 3) At Sikman, the most heavily polluted site, average value of components were 8.0 pH, 8.1 ppm BOD, 8.2 ppm COD. These values were close to the limit point of agricultural water quality standard of 8.0 ppm BOD (COD). 4) Any apparent variation was not observed by the sampling season in most components except DO and $NH_4+$. DO of October was higher than that of May or July but $NH_4+$ was low. 5) $NH_4+$ content was comparatively high in downstream of the Nagdong river of which water is used as the agricultural irrigation in the Gimhae plain. Therefore, fertilizer application on the farming land must make account of nitrogen content of the irrigation water 6) It was considered that chloride and sodium contents would not influence the crop cultivation in common season, but in dry season irrigation must be done carefully.

• Journal of the Korean Wood Science and Technology
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• v.33 no.1 s.129
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• pp.87-96
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• 2005

This study was carried out to evaluate the shear bond strength and adhesive bond durability of structural glued laminated timber (glulam) manufactured with mixed species lumber of Korean red pine, Korean pine and Japanese larch, using resorcinol adhesive and water-based polymeric-isocyanate adhesive (WPI). Each board used as a glulam lamina was graded by visual inspection. The visual lumber grade of the all species was very low due to the large size and number of knots and the steep slope of grain. In view of the results, appropriate pruning, sawing and drying processes might be needed to produce high grade lamina lumber with small knot size and drying defect free. Shear bond strength of every tested glulam specimen ranged between 7.9 and $9.9N/mm^2$, and much higher than the Korean Standard (KS) for glulam shear bond strength, $7.1N/mm^2$. There was not much shear bond strength difference between wood/resorcinol and wood/WPI. The resorcinol adhesive bond durability exceeded KS requirements. However, delamination on the end-grain surfaces of WPI glulam submerged in both room temperature and boiling water severely occurred, and its durability did not meet KS requirements. Further investigations may be required, and special care should be taken, to ensure long service life of WPI glulam used for exterior application. Results of this study are expected to be useful for improvement of mechanical properties and structural performance of mixed species glulam.