• 한국토양환경학회지
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• 제2권2호
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• pp.53-60
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• 1997

중금속에 의해 오염된 토양에 대해 토양세척기법을 적용하기 위한 최적의 조건을 도출하고자 회분식 및 실험실 규모의 파이롯트 실험을 수행하였다. 대상 중금속으로는 구리, 납, 아연을 선정하였고 각 중금속의 농도는 구리 500mg/kg dry soil, 납 1,000mg/kg dry soil, 아연 500mg/kg dry soil로 결정하였다. 세정제로는 유기산 중 citric acid와 oxalic acid를 선정하였다. 회분식 실험 결과, 구리, 납, 아연의 세정효율은 각각 79%, 72%, 72%로 나타났으며, 구리와 납에 대한 세정제의 농도와 진탕비는 citric acid 50mM과 1:5(중량/체적비)가 최적조건으로 판명되었고, 계면활성제 OA-5 및 SDS l∼2%를 첨가함으로써 세정효율을 향상시킬 수 있었다. 파이롯트 규모실험에서는 납으로 오염된 토양에 대하여 1차 토양세척시 59%의 세정효율을 얻었으며, 2차 토양세척으로 78%까지 세척할 수 있었다.

• Journal of Biosystems Engineering
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• 제32권6호
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• pp.455-461
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• 2007

The electric current of a flow injection type enzyme-sensor was measured to confirm the stable operating conditions of the sensor. The current of the sensor was decreased as the buffer solution velocity increased. Under the limitation of the cycle time to be below 10 minutes, the effective ranges of the buffer solution velocity were suggested $0.10{\sim}0.26$, $0.12{\sim}0.24$, $0.1{\sim}0.25$ and $0.05{\sim}0.10\;cm/s$ of 1.0, 1.4, 2.4 and 3.4 mm of the electrode diameters, respectively. As the reaction time of the enzyme and the substrate was increased, the current was decreased because of the dilution between the sample and buffer solution. Therefore, it could be recommended that the reaction time was able to be selected as shortly as possible in consideration of the total cycle time. As the result of the experiments using a different volume ratio of the enzyme to substrate, it was concluded that the substrate had to be mixed with the same amount of the enzyme. The current have increased remarkably in proportion to the electrode diameter under 0.1 cm/s of the buffer solution velocity but there was no difference over 0.1 cm/s of the buffer solution velocity. The cross type arrangement of the electrode was highly suggested for application and machining of the sensor.

• 한국미생물·생명공학회지
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• 제15권6호
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• pp.430-435
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• 1987

전분으로부터 동시당화 발효법에 의한 에탄을 생산공정의 개발을 위하여 amyloglucosidase를 chitin 에 결합시킨 후 Zumomonas mobilis와 함께 sodium alginate젤에 재고정화 시킨 다음 에탄을 생산실험을 행한 결과 전분의 당화 및 발효속도를 증가시킬 수 있음이 발견되었다. 충진층 발효조를 사용한 연속식 에탄올 생산결과 40일 이상 안정하게 유지할 수 있었고, 최대 에탄올 생산성은 희석배율 0.83$hr^{-1}$에서 17.7g/$\ell$, h였다.

• Archives of Reconstructive Microsurgery
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• 제16권2호
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• pp.63-67
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• 2007

This study was designed to introduce free toe tissue transfer using infiltration method of local anesthetic agent. Four toe pulp tissues were transferred to reconstruct finger tip defect in four patients who were not suitable for general anesthesia. Two flaps taken from the lateral side of the great toe was used for reconstruction of thumb defect and two flaps from the medial side of the second toe for resurfacing of the index and fifth finger. Flap sizes were various from $2.0{\times}2.0\;cm^2$ to $1.6{\times}4.0\;cm^2$. Anesthesia was induced by infiltration of 2% lidocaine hydrochloride (with 1:100,000 epinephrine) with dilution of normal saline in same volume unit, as like as in ordinary digital block. All vessels were anastomosed within 2 cm of distance from the proximal margin of the defect. Whole operative procedures were carried out by one team. All flaps were successfully taken without complication. The average operation time was 4 hours 10 minutes. The amount of anesthetic agent used in whole operative procedures was roughly 4 mL in the toe, 8 mL in the finger, and 12 mL totally. In conclusion, free toe tissue transfer using infiltration method of local anesthetic agent would be good strategy for finger tip reconstruction in the patient not suitable for general anesthesia.

• 생태와환경
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• 제42권4호
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• pp.465-475
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• 2009

The purpose of the study was to evaluate spatial and temporal effects of wastewater treatment plants (WWTPs) on the water quality of downstreams (Tan Stream, TS; Daemyeong Stream, DS; Gwangju Stream, GS, and Kap Stream, KS) located in four major watersheds along with impact analysis of nutrient enrichments on the WWTPs during 2004~2008. In the four streams, seasonal means of BOD, COD, TN, and TP were significantly (p<0.01) greater in the downstreams ($D_s$) than the upstreams ($U_s$). The removal effect of nutrients (nitrogen, and phosphorus) from the WWTPs was much less than the BOD, indicating a greater nutrient impact on the downstreams. Seasonal dilution of organic matter, based on BOD, during the summer monsoon of July~September was most pronounced in the downstreams of all four watersheds. However, mean TN in the downstreams during the monsoon varied little in all four streams. Regression analysis of TN in the downstreams against TN from the WWTPs showed that in the TS, and DS regression slopes in the upstreams were similar to the slopes of downstream but there was a significant difference in the GS (p<0.001) and KS (p<0.01). Tan-Stream WWTP showed low removal efficiency of BOD and COD concentrations, compared to the nutrients, whereas, two WWTPs of Gwangju and Kap Stream had low removal effects in TN and TP. Regression analysis of TN and BOD in the downstreams showed that they was closely related (p<0.01) with stream water volume only in the GS. Our data analysis suggests that greater treatment efficiencies of phosphorus and nitrogen from the WWTPs may improve the downstream water quality.

• 한국재료학회지
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• 제23권7호
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• pp.359-365
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• 2013

We investigated the nanostructural, chemical and optical properties of nc-Si:H films according to deposition conditions. Plasma enhanced chemical vapor deposition(PECVD) techniques were used to produce nc-Si:H thin films. The hydrogen dilution ratio in the precursors, [$SiH_4/H_2$], was fixed at 0.03; the substrate temperature was varied from room temperature to $600^{\circ}C$. By raising the substrates temperature up to $400^{\circ}C$, the nanocrystalite size was increased from ~2 to ~7 nm and the Si crystal volume fraction was varied from ~9 to ~45% to reach their maximum values. In high-resolution transmission electron microscopy(HRTEM) images, Si nanocrystallites were observed and the crystallite size appeared to correspond to the crystal size values obtained by X-ray diffraction(XRD) and Raman Spectroscopy. The intensity of high-resolution electron energy loss spectroscopy(EELS) peaks at ~99.9 eV(Si $L_{2,3}$ edge) was sensitively varied depending on the formation of Si nanocrystallites in the films. With increasing substrate temperatures, from room temperature to $600^{\circ}C$, the optical band gap of the nc-Si:H films was decreased from 2.4 to 1.9 eV, and the relative fraction of Si-H bonds in the films was increased from 19.9 to 32.9%. The variation in the nanostructural as well as chemical features of the films with substrate temperature appears to be well related to the results of the differential scanning calorimeter measurements, in which heat-absorption started at a substrate temperature of $180^{\circ}C$ and the maximum peak was observed at ${\sim}370^{\circ}C$.

• KSBB Journal
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• 제16권4호
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• pp.398-402
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• 2001

본 연구에서는 고정화된 한천분해효소가 충진된 packed-bed reactor를 이용하여 한천올리고당을 연속생산하였다. Packed-Bed 형 Reactor의 H/D를 조절하여 생산율이 가장 좋은 조건을 살펴 본 결과, H/D=14인 것으로 나타났으며, 한천올리고당의 연속생산시 35 h에서 효소활성반감기를 나타내었다. Packed-Bed Reactor내에서 기질 1 g/L agar, 1unit 고정화효소, 4$0^{\circ}C$, flow rate 24 mL/min 조건하에서 연속반응 시켰을 때, 중합도 4의 한천올리고당이 주로 생산되었으며 중합도 6당, 2당순으로 생산됨을 알 수 있었다. 또한 다중으로 연결된 반응기를 이용한 결과, 기질 1 g/L agar, 4$0^{\circ}C$, 48 mL/min의 조건하에서 41.7 mg/h의 한천올리고당이 생산됨으로서 다중으로 연결하지 않은 반응기보다 2.3배 한천올리고당의 생산율이 증가하였음을 알 수 있었다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 1999년도 정기총회 및 춘계 공동 학술발표회
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• pp.149-156
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• 1999

In the United States (U.S.), the monitored natural attenuation (MNA) approach has been used as an alternative remedial option for organic and inorganic compounds retained in soil and dissolved in groundwater. The U.S. Environmental Protection Agency (EPA) defines the MNA as“in-situ naturally-occurring processes include biodegradation, diffusion, dilution, sorption, volatilization, and/or chemical and biochemical stabilization of contaminants and reduce contaminant toxicity, mobility or volume to the levels that are protective of human health and the environment”. The Department of Soil Environment. National Institute Environmental Research (NIER) is in the process for demonstrating the MNA approach as a potential remedial option for the BTEX contaminated site in Uiwang City. The project is charactering the research site in terms of the nature and extend of contamination, biological degradation rate, and geochemical and hydrological properties. The microbial-degradation rate and effectiveness of nutrient and redox supplements will be determined through laboratory batch and column tests. The geochemical process will be monitored for determining the concentration changes of chemical species involved in the electron transfer processes that include methanogenesis, sulfate and iron reduction, denitrification, and aerobic respiration. Through field works, critical soil and hydrogeologic parameters will be acquired to simulate the effects of dispersion, advection, sorption, and biodegradation on the fate and transport of the dissolved-phase BTEX plume using Bioplume III model. The objectives of this multi-years research project are (1) to evaluate the MNA approach using the BTEX contaminated site in Uiwang City, (2) to establish a standard protocol for future application of the approach, (3) to investigate applicability of the passive approach as a secondary treatment remedy after active treatments. In this presentation, the overall picture and philosophy behind the MNA approach will be reviewed. Detailed discussions of the site characterization/monitoring plans and risk-based decision-making processes for the demonstration site will be included.

• 대한금속재료학회지
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• 제48권8호
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• pp.765-774
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• 2010

Oxygen equilibrium and the solubility of MgO have been measured in the $CaO-Fe_tO-MgO-SiO_2({\leq}5mass%)-{\Sigma}M_xO_y$ slag in equilibrium with liquid iron in the temperature range of 1550 to $1700^{\circ}C$. The effect of oxides on the MgO solubility, and a method for calculating the solubility of MgO using slag composition and temperature,were discussed. The solubility of MgO is increased with increasing temperature and $Fe_tO$ content, and with decreasing basicity (C/S). The effect of ${\Sigma}M_xO_y$ on the solubility of MgO is a dilution effect due to the increase in slag volume. The activity and activity coefficient of $Fe_tO$ decreased with increasing basicity (B). The effect of temperature on the activity was negligible. The value of ${\rho}=Fe^{3+}/Fe^{2+}$ increased with the increase of the slag basicity (B") and the decrease of the $Fe_tO$ content in the slag.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2020년도 학술발표회
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• pp.325-325
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• 2020

Low impact development (LID) is a widely used technology that aims to reduce the peak flow volume and amount of pollutants in stormwater runoff while introducing physicochemical, biological or a combination of both mechanisms in order to improve water quality. This research aimed to determine the effect of hydrologic factors in removing the pollutants on stormwater runoff by an LID facility. Monitored storm events from 2010-2018 were analysed to evaluate the hydraulic and hydrological performance of a small constructed wetland (SCW). Standard methods for the examination water and wastewater were employed to assess the water quality of the collected samples (APHA et al, 1992). Primary hydrologic data were obtained from the Korea Meteorological Administration. The recorded average rainfall intensity and antecedent dry days (ADD) of SCW were 5.26 mm/hr and 7 days respectively. During the highest rainfall event (27 mm/hr), the removal efficiency of SCW for all the pollutants was ranging from 67% to 91%. While on the lowest rainfall event (0.7 mm/hr), the removal efficiency was ranging from -36% to 62%. Rainfall intensity has a significant effect to the removal efficiencies of each facility due to its dilution factor. In addition to that, there was no significant correlation of ADD to the mean concentrations of pollutants. Generally, stormwater runoff contains significant amount of pollutants that can cause harmful effects to the environment if not treated. Also, the component of this LID facility such as pre-treatment zone, media filters and vegetation contributed to the effectivity of the LID facilities in reducing the amounts of pollutants present in stormwater runof.