• Clean Technology
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• v.25 no.4
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• pp.302-310
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• 2019

A constructed wetland with the aerobic tank and anaerobic/anoxic tank connected in series was employed in order to treat highly polluted stream water. The aerobic tank was maintained aerobic with a continuous supply of air through the natural air draft system. Five pilot plants having different residence times were employed together to obtain parameters for the best performances of the wetland. BOD and COD removals at the aerobic tank followed the first order kinetics. COD removal rate constants were slightly lower than BOD. The temperature dependence of COD (θ = 1.0079) and BOD (θ = 1.0083) was almost the same, but the temperature dependence (θ_N) of T-N removal was 1.0189. The SS removal rate was as high as 98% and the removal efficiency showed a tendency to increase with increasing hydraulic loading rate (Q/A). The main mechanism of BOD and COD removal at the anaerobic/anoxic tank was entirely different from that of the aerobic tank. BOD and COD were supplied as the carbon source for biological denitrification. T-P was believed to be removed though the cation exchange between orthophosphate and gravels within the anaerobic and anoxic tanks. The wetland could successfully be operated without being blocked by the filtered solid which subsequently decomposed at an extremely fast rate.

• Proceedings of the KSAR Conference
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• 2002.06a
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• pp.183-183
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• 2002

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.606-609
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• 2000

These results indicate that the low-Sequency signal of T/P data (with periods greater than 200 days) can be interpreted most safely. Similarly to the case of the T/P data, corrections were also applied to those of tide gauge counterparts. Hence, when the 200-day effect was filtered out, the agreement between T/P and TG data sets was optimized.

• Korean Chemical Engineering Research
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• v.51 no.2
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• pp.257-262
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• 2013

As the regulation of total phosphorus (T-P) concentration in biologically treated sewage effluent is reduced to 0.2~2 mg/L, flocculation process is recommended to remove T-P. In this study, the performance of Ti-salt coagulant was investigated in terms of dosage and pH in removing phosphorus and the collected sludge after Ti-salt flocculation was calcined to produce titania for effective sludge recycling. The flocculation performance was carried out using two methods: sedimentation and air floatation. Both methods were feasible to apply for Ti-salt flocculation. Ti-salt flocculation was effective in reducing phosphorus concentration in sewage effluent, which showed similar performance of alum ($Al_2(SO_4)_3$). The calcined sludge was recycled to titania which is the widely used metal oxide. Titania produed from Ti-salt sludge indicated similar characteristics of commercially-available P-25 in regard to photocatalytic activity and surface area. Therefore, this can be easily adopted to titania application by replacing P-25.

• Journal of Chest Surgery
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• v.34 no.6
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• pp.454-464
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• 2001

Background: It has been recognized that systemic inflammatory reaction and oxygen free radical formed by activated leukocyte in the procedure of cardiopulmonary bypass(CPB) frequently produce postoperative cardiac and pulmonary dysfunction. The purpose of this study was to evaluate the efficacy of leukocyte-depleting filters in the cardiopulmonary bypass circuit for patients undergoing open heart surgery(OHS). Material and method: The study involved 15 patients who underwent OHS with a Leukoguard-6 leukocyte filter placed in the arterial limbs of the bypass circuit(filter group, n=15) and 15 patients who did not have the filter(control group, n=15). We analyzed the differences between the groups in intraoperative changes of peripheral blood leukocyte and platelet counts, pre- and postbypass changes of malondialdehyde(MDA), troponin-T(TnT), 5'-nucleotidase(5'-NT) in coronary sinus blood, spontaneous recovery rate of heart beat after CPB, pre-and postoperative cardiac index(Cl) and pulmonary vascular resistance(PVR), and the amounts of postoperative bleeding and sternal wound complication. Result: During CPB, total leukocyte count of the filter group(9,567$\pm$ 842/㎣) was significantly less than that of the control group(13,573+1,167/㎣) (p<0.01), but there was no significant difference in platelet count between the groups. Postoperative levels of MDA(3.78+0.32 $\mu$mol/L vs 5.86+0.65 $\mu$mo1/L, p<0.01), TnT(0.40$\pm$0.04 ng/mL vs 0.59$\pm$0.08 ng/mL, p<0.05) and 5'-NT(3.88$\pm$0.61 U/L vs 5.80$\pm$0.90 U/L, p<0.05) were all significantly lower in the filter group than the control group. Postoperative Cl was higher in the filter group than the control group(3.26$\pm$0.18 L/$m^2$min vs 2.75$\pm$0.17 L/$m^2$/min, p=0.05). PVR of the filter group was lower than that of the control group(65.87$\pm$7.59 dyne/sec/cm$^{5}$ vs 110.80+12.22 dyne/sec/cm$^{5}$ , p<0.01). Spontaneous recovery rate of heart beat in the filter group was higher than that in the control group(12 patients vs 8 patients, p<0.05). Postoperative wound infection occurred in one case in the filter group and 4 case in the control group(p<0.05). Postoperative 24 hour blood loss of the filter group was more than that of the control group (614$\pm$107 mL vs 380+71 mL, p=0.05).

• Resources Recycling
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• v.9 no.4
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• pp.56-62
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• 2000

This study was introduced an amalgamated septic tank system using mineral sintered body was made from non-metallic minerals with a ability being attached or accelerating a vitality of soil microorganism for the effective wastewater treatment. Experimentally, we made an amalgamated septic tank appling anaerobic-aerobic process experimental facilities to two personal houses for handling a residental sewage directly on a small scale from the place of origin. The results are shown as follows; The COD\ulcorner and BOD of effluent were about 10 mg/l after the treatments and T-N removal efficiency was 60-70%. Moreover these results suggested the possibility of denitrification without adding organics and more than 80% of T-P removal also showed the possibility of wastewater treatment biologically.

• Journal of dental hygiene science
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• v.9 no.3
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• pp.287-294
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• 2009

The purpose of this survey research was to investigation the relationship among dental health state, care and knowledge of patients who participate in dental hygiene process of dental hygiene students voluntarily. And the following conclusion were obtained from questionnaires for 266 volunteers using SPSSWIN 12.0. 1. For the dental health state according to sex distinction, it showed that women (DMFT index: 13.0) was higher than men (DMFT index: 10.4) and statistically significant difference. For DT rate, men (32.0) was higher than women (30.0), for MT rate men (32.2) was higher than women (26.6) and it showed statistically significant difference (P<0.05). 2. For the dental health knowledge according to sex distinction, 77.8% patients replied as the food causing teeth decay are chocolate, biscuits, etc. and it didn't showed significant difference statistically. 72.4% men and 84.7% women replied as they could take precautions against a dental caries using fluorine and it showed statistically significant difference(P<0.05). 3. For brushing their teeth from top to down for the upper tooth and from down to top for the lower one, 80.3% patients replied as they did like that but 62.5% patients as they didn't. And 68.2% patients replied as the food causing teeth decay arc chocolate, biscuits, etc. and 81.0% patients didn't like that. It showed statistically significant difference. (P<0.05) 4. 50.5% patients went to the dental hospital once per 6 month and it showed statistically significant difference. And 71.3% patients replied as the food causing teeth decay are chocolate, biscuits, etc. and 81.0% patients didn't like that, It showed statistically significant difference. (P<0.05)

• Proceedings of the KAIS Fall Conference
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• 2007.05a
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• pp.299-302
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• 2007

본 연구는 하 ${\cdot}$ 폐수 중의 유기물뿐만 아니라 질소, 인을 생물학적으로 제거하는 실험을 수행하였다. 공정 내 미생물의 유실을 방지하고 미생물이 고농도 상태로 유지 가능한 부착성장의 한 공법인 RBC에 끈상 나선형 미생물 접촉재를 설치한 반웅기를 이용하였다. 원수는 Glucose 1,800 mg/L, $NH_{4}Cl$ 500 mg/L, $KH_{2}PO_{4}$ 5mg/L를 혼합한 인공폐수를 제조하여 공정에 주입하였고, 그 결과 각각 미생물이 폐수에 적응하는 단계인 Period 1에서는 각 수질 분석 항목의 농도가 점차적으로 감소하는 경향을 보였으며, 정상상태라고 판단한 Period 2에서는 최종적으로 유입수에 대한 유출수의 제거율은 각각 $TCOD_{Cr}$ 94%, BOD 87%, T-N 85%, T-P 89%의 결과를 나타내었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.451-451
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• 2018

박층류 자연정화공법은 수로의 폭을 넓히고 수심을 낮추어 박층류를 조성하고, 이를 이용하여 하천을 정화하는 공법이다. 박층류가 조성되면 낮은 수심에서 상대적으로 느린 유속 조건이 형성되며 이 때 박층부에 침전된 오염물질은 자갈층 표면에 형성된 생물막에 의해 산화 분해되어 제거된다. 박층류에 의한 오염물질 제거는 생물막의 형성, 생물 산화를 위한 용존산소량 등이 중요한 인자로 작용하며, 박층부를 조성하기 위해서는 수심 10 cm, 유속 30~50 cm/s 의 조건이 적절하다. 본 연구에서는 박층류에 의한 자연정화 성능을 평가하기 위하여 용인시 오산천 일부 구간 고수부지에 사석자갈을 이용한 박층류 자연정화공법이 적용된 차집수로를 설치하고, 오산천으로 유입되는 농수로의 물을 공급하여 오염물질의 농도 변화를 측정하였다. 측정된 항목은 T-N, T-P, COD, DO 등이며, 측정 결과 박층류 자연정화 수로를 유출부에서의 오염물질의 농도가 유입부에서보다 저감되는 것을 확인 할 수 있었다.

• Journal of Korea Water Resources Association
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• v.30 no.6
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• pp.731-741
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• 1997

Optimum design conditions of rapid mixing impellers for an effective Water Treatment Plant operation were experimentally studied by thorough examination of parameters, such as impeller type and detention time. which govern the removal efficiency of turbidity. It was found that the impeller type is one of the major parameters governing the economic power consumption and the efficiency of turbidity removal. The experimental results showed that not only the velocity gradient G but also a new design guide. so called mixing energy per unit volume of raw water, could be used as a design and operation guides for rapid mixing in W.T.P.