• Environmental Engineering Research
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• 제11권3호
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• pp.134-142
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• 2006

The treatment of high-strength swine wastewater by anaerobic digestion combined with an aquatic plant system was investigated. Anaerobic digestion of swine wastewater gave volatile solids (VS) removal efficiencies of 43.3%, 52.1% and 54.5% for hydraulic retention times (HRTs) of 20, 30, 40 days, respectively. The removal efficiencies of VS, total chemical oxygen demand (TCOD) and soluble chemical oxygen demand (SCOD) decreased with increasing VS volumetric loading rate (VLR). Higher organic removal efficiency was observed at longer HRTs for the same VS volumetric loading rate. As VS volumetric loading rate increased, biogas production increased and the methane content of the biogas decreased. Experiments using duckweed (Lemna species) as an aquatic macrophyte gave the following results. In the case of nitrogen, removal efficiency was above 60% and effluent concentration was below 10.0 mg/L when the influent ammonia-N loading was about $1.0\;g/m^2/day$. In the case of phosphorus, removal efficiency was above 55% and effluent concentration was below 2.0 mg/L when the influent $PO_4$-P loading was about $0.15\;g/m^2/day$. In addition, crude protein and phosphorus content of duckweed biomass increased from 15.6% to 41.6% and from 0.8% to 1.6%, respectively, as the influent nutrient concentration increased. The treatment of high-strength swine wastewater by anaerobic digestion combined with an aquatic plant system offers good performance in terms of organics and nutrient removal for relatively low operation and maintenance costs. The results indicate that under appropriate operational conditions, the effluent quality is within the limits set by Korean discharge criteria.

• Transactions on Electrical and Electronic Materials
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• 제3권3호
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• pp.21-24
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• 2002

Two kinds of $Nd_{1+X}Ba_{2-X}Cu_3O_{7-{\delta}}$, the sintering samples and zone melting samples, were heat-treated under pure Ar at 950$^{circ}C$. The substitution of Nd ion for Ba ion in the $Nd_{1+X}Ba_{2-X}Cu_3O_{7-{\delta}}$ before and after the heat treatment was investigated by XRD. In order to confirm the effects of the heat treatment, the Tc and Jc of samples with/without the heat treatment under Ar were comparatively studied. $Nd_{1+X}Ba_{2-X}Cu_3O_{7-{\delta}}$ samples were oxygenated under pure oxygen at $300^{circ}C$. From the XRD pattern it was found that the sample with x<0.4 was transferred from tetragonal phase to orthorhombic phase after the oxygenation, while the sample with x>0.4 did not show the phase transition even after a long time oxygenation. Therefore, the low oxygen partial pressure (Ar+1 % O$_2$) was used for the ambient atmosphere of the zone-melting samples, which could reduce the melting temperature and depress the substitution of Nd for Ba. After the improvement in the zone-melting process, the Jc value was increased to 2 x $10^4$A/$cm^2$ (0 T, 78 K). The particle orientation and the structure of zone-melted NdBaCuO were studied by the XRD and SEM analysis.

• Archives of Plastic Surgery
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• 제34권5호
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• pp.543-550
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• 2007

Purpose: Diabetic foot ulcer is a representative disease of chronic would with multiple defects of wound healing factors. Many nutrition factors have been known to be essential for wound healing, but objective data are lacking. The purpose of this study is to determine those factors essential for wound healing, and to find out which of those factors are lacking in diabetic foot ulcer patients through this pilot study. Methods: We studied 100 patients who visited our clinic from March 2005 to February 2006 for treatment of diabetic foot ulcers with a duration of more than 6 weeks. We checked serum levels of protein, albumin, vitamin A, C, E, iron, magnesium, zinc, copper and hemoglobin by drawing 23cc blood after 8 hours of fasting. Protein, albumin, iron, magnesium levels were measured by colorimetry; hemoglobin levels were measured by auto analysis. Vitamin levels were measured by high performance liquid chromatography (HPLC), copper and zinc levels were measured by Inductively coupled plasma (ICP). They were compared with normal values. The patients were divided by transcutaneous oxygen pressure levels, age and sex to study the effects of these parameters. Results: 76% and 61% of patients had within-normal range serum protein and albumin levels, respectively. Among vitamins, only the level of vitamin C was low in 55% of the patients. Levels of vitamin A, E were normal or high in 93% and 100% of patients. As for trace elements, levels of iron and zinc were low in 63% and 60% of patients, but levels of magnesium and copper were usually normal or high. Levels of vitamin C, iron and zinc were lower in the low-transcutaneous oxygen pressure group. There were no definite differences according to age and sex. Conclusion: Serum levels of Hb, vitamin C, iron, zinc were low in most diabetic foot ulcer patients. The deficit was very severe in the low-transcutaneous oxygen pressure group.

• 한국습지학회지
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• 제22권2호
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• pp.145-152
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• 2020

고속도로는 많은 자동차 운행대수와 함께 높은 주행속도 및 급격한 주행속도 변화구간(휴게소, 영업소 등)으로 인하여 비점오염물질의 배출이 높은 지역에 해당한다. 국내 고속도로는 절토층 및 성토층에 조성됨으로써 적정 토양침투량 확보가 어려워 다양한 종류의 비점오염저감시설이 설치되지 못하고 있다. 본 연구는 토양치환 기법에 대한 연구를 통해 고속도로에 설치 가능한 시설의 종류를 확대하고 비용효율적 침투시설의 설계를 유도하기 위하여 수행되었다. 침투율이 낮은 원지반에 토양치환을 수행할 경우 시설 내 체류시간이 약 30% 지연되고, 시설 내 침투 및 저류율은 약 20% 증대하며, 비점오염물질 Total Suspend Soiled (TSS), Chemical Oxygen Demand (COD), Biological Oxygen Demand(BOD), Total Nitrogen(TN) 및 Total Phosphorus(TP) 제거효율이 약 20% 증가하는 것으로 나타났다. 원지반 내 침투율이 낮은 곳에 토양치환을 수행할 경우 저류량, 체류시간 및 침투면적이 증가하여 침투율이 향상되는 것으로 나타났다. 원지반 토양의 침투능이 낮은 토양에 침투시설을 적용하기 위해서는 물환경보전법 시행규칙 별표17(비점오염저감시설의 설치기준)의 개선이 필요하며, 이 경우 토양 침투율이 시간당 13 mm 이하일 때 토양치환을 통해 법적 처리용량을 확보하도록 요구할 수 있다.

• 상하수도학회지
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• 제9권4호
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• pp.87-96
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• 1995

The Electron/Hole Pair is generated when the activation energy produced by ultraviolet ray illuminates to the semiconductor and OH- ion produced by water photocleavage reacts with positive Hole. As a results, OH radical acting as strong oxidant is generated and then Photocatalytic oxidation reaction occurs. The photocatalytic oxidation can oxidate the non-degradable and hazardous organic substances such as pesticides and aromatic materials easier, safer and shorter than conventional water treatment process. So in this study, many factors influencing the oxidation of chlorophenols, such as inorganic electrolytes addition, change of oxygen and nitrogen atmosphere, temperature, pH, oxygen concentration, chlorophenol concentration, were throughly examined. According to the experiments observations, it is founded that the rate of chlorophenol oxidation follows a first-order reaction and the modified Langmuir-Hinshelwood relationship. And the photocatalytic oxidation occurs only when activation energy acting as Electron/Hole generation, oxygen acting as electron acceptor to prevent Electron/Hole recombination, $TiO_2$ powder acting as photocatalyst are present. The effects of variation of dissolved oxygen concentration, temperature and inorganic electrolytes concentration on 2-chlorophenol oxidation are negligible. And the lower the organic concentration, the higher the oxidation efficiency becomes. Therefore, the photocatalytic oxidation is much effective to oxidation of hazardous substances at very low concentration. The oxidation is effective in the range of 0.1 g/L-10 g/L of $TiO_2$. Finally when the ultra-violet ray is illuminated to $TiO_2$, the surface characteristics of $TiO_2$ change and Adsorption/Desorption reaction on $TiO_2$ surface occurs.

• 한국가스학회지
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• 제9권3호
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• pp.9-14
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• 2005

변성가스의 폭발특성을 평가하기 위하여, 산소농도 변화와 수소의 첨가에 따른 변성가스 조성을 변화시켜 폭발거동에 대한 실험을 행하였다. 이러한 실험을 행한 결과 산소농도 $21\%$에서 변성가스와 수소의 농도가 증가할수록 폭발하한계는 낮아졌으며, 산소농도 $6\%$에서 폭발한계산소농도를 구하였다. 변성가스의 최대폭발압력은 $4.61 kg_f/cm^2$의 최적값을 얻었고, 이때 최대폭발압력상승속도는 변성가스 농도 $40\%$에서 $130.75 kg_f/cm^2/s$를 구하였다. 또한 폭발에 필요한 최소점화에너지는 변성가스 농도 $50\%$에서 0.13 mJ를 구하였다.

• 한국미생물·생명공학회지
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• 제25권1호
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• pp.89-95
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• 1997

The current processer of the textile wastewater treatment are mostly consisted of a combination of a physico-chemical and a biological treatment. The overall efficiency of these processes is, however, assessed to be fairly low. It is even worse during the summer season when temperature of the wastewater rises above 40$\circ $C. Therefore, a feasible process of the textile wastewater treatment which can work efficiently at higher temperatures was investigated in this work. We used a bench scale reactor consisted of one 4 liter anaerobic and one 8 liter aerobic tank, and the thermophilic symbiotic PVA degraders, Pasteruella hemolytica KMG1 and Pseudomonas sp. KMG6 that had been isolated in our laboratory. In the preliminary flask experiments, we observed that the thermophilic symbiotic PVA degraders could not grow in the wastewater substrate. Then, we isolated the mutant strains by acclimating the KMG1and KMG6 strains to the wastewater medium. The mutant symbionts (KMG1-1 and KMG6-1) were isolated through 6 times successive transfers into the fresh wastewater medium after 5 days culture for each. The mutant strains obtained grew well in the mixed medium composed of 75% wastewater and 25% synthetic medium, and supplemented with 0.5% PVA as a sole carbon source. During the culture for 14 days at pH 7.0 and 40$\CIRC $C, the bacteria assimilated about 89% of the added PVA. The symbionts degraded equally well all the PVA substrates of different molecular weight (nd=500~30000). In contrast to the flask experiments, in the reactor system the mutant strains showed very low levels of the PVA and COD removal rates. However, the new reactor system with an additional aerobic tank attained 82% removal rate of COD, 94% of PVA degradation and 71% of color index under the conditions of 5% inoculm on the tank 2, incubation temperature of 40$\circ $C, dissolved oxygen level of 2~3 mg/l and retention time of 30 hours. This result ensures that the process described above could be an efficient and feasible treatment for the PVA contained textile wastewater at higher temperatures.

• 한국농공학회지
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• 제39권4호
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• pp.55-63
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• 1997

Constructed wetland system which can be applied to the rural wastewater treatment system was examined by pilot plant in Kon-Kuk University. Hydraulic loading rate of wastewater was about 0.16m$^3$/m$^2$. day and theoretical detention time in the system was 1.38 days. The effluent of the septic tank for the school building was applied as inflow to the system. The influent concentration of DO was zero but effluent was up to 4.37mg/${\ell}$ which implies that oxygen was supplied enough from atmosphere by reaeration to support biological activity of the system. Average influent concentration of BOD was 104mg/${\ell}$ and effluent was 24mg/${\ell}$ with average removal rate of 76%. Average influent concentration of COD was 215mg/${\ell}$ and effluent was 63mg/${\ell}$ with average removal rate of 70 % . Average influent concentration of SS was 78mg/${\ell}$ and effluent was 10mg/${\ell}$ with average removal rate of 87%. Two components, BOD and SS, are regulated by law to keep maximum water quality standard of 80mg/${\ell}$ when daily outflow rate is less than 100$m^3$/day which is the case of most rural communities. Therefore, the results from the experiment showed that constructed wetland system can meet the water quality standard easily. Average influent concentration of total nitrogen was 165mg/lwhich is relatively higher than normal wastewater, and effluent was about 156mg/${\ell}$ with average removal rate of only 6%. Average influent concentration of total phosphorus was 41 mg/${\ell}$ and effluent was 6mg/${\ell}$ with average removal rate of 87%. Overall, constructed wetland system was thought to be effective to treat wastewater if nitrogen removal mechanism is improved. Considering low cost, less maintenance, and high treatability, this system can be a practical alternative for the wastewater treatment in rural area The experiment was performed during the summer and fall season, and treatment efficiency of the system is expected to decrease in low temperature. therefore, further study including temperature is required to evaluate feasibility of the system more in detail.

• 한국농공학회지
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• 제40권3호
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• pp.83-92
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• 1998

Field experiment was performed from August 1996 to January 1998 to examine the applicability of constructed wetland system for wastewater treatment in rural area. The pilot plant was installed in Kon-Kuk University and the school building septic tank effluent was used as an influent to the treatment basin. Hydraulic loading rate was about 0.1 6$0.16^3/m^2$ day and theoretical detention time in the system was 1.38 days. The treatment basin was composed of sand and reed. The influent DO concentration was low and many cases close to zero, but effluent concentration was higher than the influent which implies that oxygen was supplied naturally. The average concentration of influent BOD was 126mg/L, and with average removal rate of 69 % the average effluent concentration was 4Omg/L which satisfied the effluent water quality standard for the system of interest. The average influent concentration of COD was 2Olmg/L and average effluent concentration was 75mg/L with average removal rate of 60%. The performance of BOD and COD tends to deteriorate in the low temperature, and appropriate action needs to be taken during the cold winter time for stable operation. The average influent concentration of SS was 5Omg/L, and effluent was 1 1mg/L with average removal rate of 76% which satisfied the effluent water quality standard for the system of interest. The results for the regulated components, SOD and SS, from the experiment showed that constructed wetland system can meet the effluent water quality standards. The average influent concentration of total phosphorus was 25.6mg/L and average effluent concentration was 7.8mg/L with average removal rate of 63%. Not like the performance of the above components, average nitrogen removal rate was only 11.2% which is not satisfactory. Although, nitrogen is not regulated at this moment, it can cause many environmental problems including eutrophication. Therefore, nitrogen removal efficiency should be improved for actual application. From the result of the field experiment, constructed wetland system was thought to be an appropriate alternative for wastewater treatment in rural area.

• 한국전기전자재료학회논문지
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• 제31권3호
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• pp.156-159
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• 2018

Inductively coupled plasma (ICP) treatment with argon and a mixture of argon and oxygen gases has been used to modify the surface of polycarbonate (PC) substrates. The results showed that the surface contact angle was inversely proportional to the plasma discharge power and that the mixed-gas plasma (gas flow 10:10 sccm, discharge power 60 W) decreased the surface contact angle as low as $18.3^{\circ}$, indicating a large increase in the surface hydrophilicity. In addition, $SnO_2$ thin films deposited on the PC substrate effectively enhanced the ICP plasma treatment, and could also enhance the usefulness of PC in the inner parts of automobiles.