• Korean Journal of Soil Science and Fertilizer
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• v.43 no.6
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• pp.1035-1039
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• 2010

For 65 national forest areas in 1993 to 2008, the ambient sulfur dioxide ($SO_2$) concentrations were measured monthly using passive samplers and compared to the those of urban areas in order to investigate the characteristics of temporal and spatial distribution. In the forest areas, annual average concentration of sulfur dioxide gradually decreased from the beginning year of monitoring to 1997 and then had no significant change, such as the annual trend in urban areas monitored by Ministry of Environment. For the monitoring term, average concentration of sulfur dioxide in the forest areas was 5.6ppb, which was lower than the 10.1ppb in the urban areas and the EC ecological standard level (7.6 ppb). Seasonally, both in forest areas and urban areas the monthly average concentrations were much higher in winter and spring due to much more heating fuel consumption, and lowest in summer. Regional comparison to other regions of Gyeongbuk and Gyeonggi province showed that the concentration of sulfur dioxide was the highest during year. A significant positive correlation between sulfur oxides' emissions and sulfur dioxide concentration by province was observed, reflecting that the size and proximity of sources of atmospheric sulfur oxides could be important factors in determination.

• KSBB Journal
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• v.17 no.6
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• pp.543-548
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• 2002

The enantioselective esterification of racemic ibuprofen catalyzed by a Candida rugosa lipase was studied according to reaction conditions such as a lipase concentration, reaction temperature, alcohol chain length and alcohol concentration. The S-(+)-ibuprofen alkyl esters prepared were converted to S-(+)-ibuprofen by hydrolysis with sulfuric acid as a catalyst. High conversions in the esterifications were obtained at 60$^{\circ}C$ and an equimolar ratio of octanol to ibuprofen. The initial reaction rate of the esterification decreased with increasing octanol concentration. Conversion and initial reaction rate increased with increasing alcohol chain length. Values of enantiomeric excess(ee) according to esterification reaction conditions did not change below 60$^{\circ}C$. On the other hand, values of conversion and ee for the chemical hydrolysis of S-(+)-ibuprofen alkyl esters were independent of alcohol alkyl chain length. Optical resolution of racemic ibuprofen was achieved by lipase catalyzed esterification and chemical hydrolysis. The separation method provided a high yield and enantioselectivity for the production of S-(+)-ibuprofen from racemic ibuprofen.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.262-262
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• 2020

새만금 유역 내에는 다수의 보 및 제수문이 위치하고 있으며, 관개, 배수, 오염원 등이 영향을 받고 있다. 선행연구 중에는 보 및 제수문을 고려하기 위해 모형의 소스코드를 일부 수정하여 연구되고 있으나 유역모형으로 구현하기에는 한계가 있으며, 이에 대한 연구는 미흡한 실정이다. 본 연구에서는 만경강 유역을 대상으로 유역 모형과 전산유체역학 모형을 이용하여 하류 제수문에 대한 유입, 유출 그리고 오염원 등의 영향을 분석하고자 한다. SWAT (Soil and water assessment tool)은 유역 모형으로 미국 농무부에서 농업유역의 수문순환 및 비점오염원을 모의하기 위해 개발한 모형이다. CFD (Computational fluid dynamics)는 전산유체역학 모형으로 구조물을 설계하고 유체, 기체 등을 모의할 수 있다. SWAT 모형을 이용하여 농업유역 하류 제수문 위치를 출구로 지정하여 수문을 모의하고 그 결과자료는 CFD에 입력할 수 있다. CFD는 하류 제수문 구조물을 설계하고 SWAT 모형의 수문자료를 입력하여 제수문의 영향을 평가할 수 있다. 우선, 만경강 유역을 대상유역으로 선정하고 부용, 황산, 상리, 고은교 등 제수문의 위치를 파악하였다. SWAT 모형 구축을 위해 2015-2018년까지 기상, 수위, 유량 관측자료를 수집하였으며, 보정기간과 검증기간은 각 2년이며, 모형 성능 검증에 사용한 적합성 평가 지수는 R² (Determine coefficient), RMSE (Root mean square error), 그리고 NSE (Nash-sutcliffe efficiency coefficient)를 사용하였다. 모형의 보정은 SWAT-CUP 자동보정프로그램을 사용하였으며, 모형의 보정지수는 NSE를 사용하였고, 1,000회 반복 수행을 통해 매개변수를 최적화하였다. 보정기간의 유출량 적합성 평가 지수는 R², RMSE 그리고 NSE가 각각 0.84, 2.96 mm/day, 0.70을 나타냈다. 검증기간의 유출량 적합성 평가 지수는 R², RMSE 그리고 NSE가 각각 0.72, 2.94 mm/day, 0.46을 나타냈다. 본 연구는 유역 차원과 구조물 차원의 모델링을 연계하는 것으로 향후 제수문 모니터링 자료를 활용하여 CFD 모형을 구축하고 유입량에 따른 제수문의 검보정 및 영향을 평가하고자 한다. 이러한 결과는 최근 기후변화에 따라 급격히 변화하는 유역환경에 대처할 수 있는 방안이 될 수 있을 것이며, 제수문 시설을 관리하는 기관에서도 합리적인 운영방안에 대한 기초자료로 기여할 수 있을 것으로 사료된다.

• Journal of Life Science
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• v.24 no.10
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• pp.1110-1117
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• 2014

Tidal flats are continuously contaminated by human activities. This study assessed the bioremediation efficiency of tidal flat soil using microcosm reactors and microorganisms originating from the tidal area. We screened 135 bacterial strains that produce extracellular enzymes from the tidal area located in the North port of Incheon bay. Two bacterial strains (Pseudoalteromonas sp. and IC35 Halothiobacillus neapolitanus IC_S22) were selected and used in the microcosm reactors, which were specially designed to functionally mimic the ecological conditions of the tidal flats. Pseudoalteromonas sp. IC35 was selected based on its relatively high activity of the enzymes amylase, cellulose, lipase, and protease. Halothiobacillus neapolitanus IC_S22 was selected for oxidation of sulfur. The M1 and M2 microcosm reactors were operated by continuous feeding of seawater under the same conditions, but M2 was first inoculated with Pseudoalteromonas sp. IC35 before the seawater feeding. The initial COD in both the M1 and M2 microcosm reactors was 320 mg/l. The final COD was 21 mg/l (M1) and 7 mg/l (M2). The M3 and M4 microcosm reactors were operated by continuous feeding of seawater under the same conditions, but M4 was first inoculated with H. neapolitanus IC_S22. The initial sulfate concentration in both the M3 and M4 microcosm reactors was 660 mg/l, and the maximum sulfate concentration was 1,360 mg/l (M3) and 1,600 mg/l (M4).

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.3 no.1
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• pp.1-8
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• 2000

Purpose: This study was undertaken to evaluate the clinical features and complication such as esophageal stricture in children with corrosive esophagitis. Methods: We retrospectively reviewed medical records of 31 children who accidentally ingested corrosive materials and visited to emergency room of Chonnam National University Hospital from Jan. 1992 to Dec. 1999. Twenty-one children were examined by upper gastrointestinal (UGI) endoscopy to evaluate location and severity of caustic injury. Results: 1) Among 31 patients, there were 20 males and 11 females and the ratio of male to female was 2:1. Average age at diagnosis was 2.3 years (12 months to 9.8 years). Twenty-seven (87.1%) patients were accidentally ingested vinegar. 2) Initial presenting symptoms were dysphagia (54.8%), vomiting (48.3%), chemical burn on lips and skin (45.2%), excessive salivation (45.2%), coughing and respiratory grunting (32.3%) and aspiration pneumonia (9.8%). 3) UGI endoscopic examination showed caustic injury in 17 children: grade I in 8, grade II in 7 and grade III in 2. The region of caustic injury was proximal esophagus in 5, distal esophagus in 3, entire esophagus in 9 and stomach in 6. 4) Corrosive esophageal strictures developed in 6 children (19.4%) and gastric outlet stricture in 1 (3.2%). All of them showed grade II or III caustic injury on endoscopic examination. Conclusion: The development of esophageal stricture was related to the severity of the caustic injury. Early UGI endoscopic examination in caustic ingestion seems to be useful for prediction of development of caustic stricture.

• Korean Chemical Engineering Research
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• v.43 no.5
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• pp.603-608
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• 2005

The molded macroporous poly (glycidyl methacrylate-co-ethylene glycol dimethacrylate) rods produced by a facile molding process were polymerized in situ within a tubular mold, chromatographic column ($4.6{\times}100mm$) by free radical polymerization. It was complemented by epoxy derivatized monolithic column and chemical modification of the epoxide groups with the sulphuric acid. By variation of the polymerization conditions, such as the ratio of the monomers, the porogen (pore generating material), and the temperature, the pore size could be varied, so the retention time of the samples may be adjusted. For the mixture of caffeine and tryptophan in the prepared monolithic column, the influences of polymerization material compositions to the efficiency, selectivity, and resolution of the monolithic column were investigated.

• 한국문화재보존과학회:학술대회논문집
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• 2004.03a
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• pp.78-91
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• 2004

염(Salts)은 일반적으로 가장 강력한 풍화요인 물질 중 하나이다. 염의 결정화(crystallization) 및 수화(hydration)작용은 석재의 화학적 풍화 뿐만이 아니라 물리적 풍화를 가속화 시킨다. 감은사지 석탑은 오랜 세월 대기 중에 노출되어 대기환경오염으로 인한 화학적 풍화 뿐만이 아니라 지리적으로 바다에 인접해 있어 바다에서 기원한 염화나트륨(NaCl)의 영향으로 다른 석조물에 비해 심한 물리적 풍화현상을 보이고 있다. 편광 현미경 및 SEM, XRD, XRF를 이용하여 석탑의 구성석재 및 염(salts)에 대한분석을 실시하였으며, 용출실험을 통해 얻은 용액에 대해서는 IC와 ICP-AES를 이용하여 분석하였고, 염류와 석재의 반응산물로 만들어진 염에 대해서는 정방위시료와 부정방위시료를 제작하여 분석하였다. 감은사지 석탑을 이루는 암석은 결정응회암으로 주 구성 광물은 사장석 및 정장석이며 소량의 석영 및 흑운모 등이 함유되어 있고 소량의 유리질 석기로 구성되어 있다. 석재의 표면에는 주 구성 광물들의 화학적 풍화로 인해서 생성된 2차 광물로 팽창성 점토광물인 스멕타이트가 존재하며, 대기오염물질과의 결합에 의해 생성된 대표적인 황산염인 석고$(gypsum,\;CaSO_4{\cdot}2H_2O)$, 소금(halite, NaCl), 해양기원 염류인 소금성분과 대기오염물질이 만들어낸 테나다이트$(thenardite,\;Na_2SO_4)$가 존재한다. 이들 염류는 일차적으로 암석의 표면에 백화현상을 초래하기도 하고, 대기 중의 오염물질과 결합하여 일부는 흑화현상을 보이기도 한다. 또한 암석 내 수분이 증가할 경우 이들 염들이 암석의 공극이나 열극을 따라 내부로 이동하여 subflorescence를 발생시켜 박락 및 박탈의 원인이 되었으며, 온도와 수분의 변화에 따른 이들 염(salts)의 수화 및 결정 작용 그리고 새로운 염(salts)의 침전작용을 반복하면서 석재 내부와 외부의 암석 및 결정에 균열과 미세열극 등이 생성되어 석재 자체의 구조적 안정성에 영향을 주고 있다. 따라서 감은사지 석탑은 지리적 환경 차이로 인해 일반적인 환경의 석조물들과는 다른 형태의 풍화양상을 보이고 있어서 풍화양상 및 풍화형태에 대한 정확한 연구와 이해를 바탕으로 보존대책이 마련되어야 한다.

• Journal of the Korean Vacuum Society
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• v.7 no.4
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• pp.306-313
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• 1998

The electrochromic $WO_3$thin films were prepared by using the electron-beam evaporatin technique. Flms prepared at a vacuum pressure of $10^{-4}$ mbar were found to be most stable during repeated potential cycles. The chemical stability of the film in aqueous solutions was also affected by the vacuum pressure during evaporation. The redox current and the optical properties of the degraded films were affected by the thickness of the film. The 5,000$\AA$-thick films were found to be most stable, undergoing the least degradation during the repeated coloring and bleaching cycles. The origin of the mechanism dominating the degradation during the repeated coloring and bleaching cycles was the accumulation of lithium in the film, which results in decreasing redox current. Tungsten oxide films with titanium content of about 10-15 mol% was found to be most stable, undergoing the least degradation during the repeated cycles. The origin of the mechanism dominating the least degradation during the repeated cycles was the reduction of lithium ion trapping sites in the films, which results in a increased durability.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.2
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• pp.1-10
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• 2022

Exhaust gases emitted from internal combustion engines contain nitrogen oxides (NOx) and sulfur oxides (SOx), which are major air pollutants causing acid rain, respiratory diseases, and photochemical smog. As a countermeasure, scrubber systems are being studied extensively. In this study, the pressure drop characteristics were analyzed by changing the exhaust gas inflow velocity using a scrubber for a 700 kW engine as a model. In addition, the fluid flow inside the scrubber and the behavioral characteristics of the droplets were studied using CFD, and the design compatibility of the cleaning device was verified. Flow analysis was performed using inertial and viscous resistances by applying porous media to the complex shape of the scrubber. The speed of the exhaust passing through the outlet nozzle from the inlet was determined through the droplet behavior analysis by spraying, and the flow characteristics for the pressure drop were studied. In addition, it was confirmed through computational analysis whether there was a stagnation section in the exhaust gas flow in the scrubber or the sprayed droplets were in good contact with the exhaust gas.

• Journal of Veterinary Clinics
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• v.31 no.3
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• pp.199-205
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• 2014

Acidosis conditions either acute or chronic following ingestion of excessive amounts of readily fermented carbohydrate are great production problems for goat in Bangladesh. This study designed to investigate the prevalence of lactic acidosis and then response to different therapeutic agents. For this purpose, 1,128 goat were examined at outdoor District Veterinary Hospital, Faridpur, Bangladseh for treatment of which 40 goats were found positive for lactic acidosis showing 3.55% prevalence of disease. The highest occurrence found in female (4.64%) of over 3 years age (4.64%) in indigenous goat (2.7%). For therapeutic assessment the forty affected goats were divided into four groups A, B, C and D comprising of 10 animals each. Group A were given magnesium hydroxide 8% w/v at 1 g/kg body weight orally. In group B magnesium hydroxide 8% w/v at a dose as group A combination with 7.5% sodium bicarbonate at the rate of 0.9 ml/Kg body weight intravenously administered. Goat in group D were treated with mixture of ginger, nuxvomica, sodium carbonate, cobalt sulphate, dried ferrous sulphate and thiamin mononitrate at the rate of 1 g/kg body weight orally. Goat of group C treated with combination drugs of group A, B and D. The rectal temperature, pulse rate, respiration rate, was performed before and after treatment. It was found that the highest recovery in group C with an average period of $21{\pm}1.8$ hours. It was concluded that lactic acidosis is a common disease of goats and its severity can be effectively reduced by using combination drugs.