• 한국환경과학회지
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• 제11권4호
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• pp.361-366
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• 2002

Several effects on Pb$^{2+}$ removal by crab shell from aqueous solution were investigated. As the increase of initial Pb$^{2+}$ concentration and decrease of initial crab shell concentration, the time required to reach an equilibrium state and the residual Pb$^{2+}$ concentration increased. In our experimental ranges, the optimum initial Pb$^{2+}$ concentration and crab shell concentration were below 103 mg/$\ell$ and over 0.5 mg/$\ell$, respectively. Also, in order to investigate the mechanism of Pb$^{2+}$ removal by crab shell in aqueous solution, the crab shell was compared with chitosan and chitin on aspects of Pb$^{2+}$ removal capacity and Pb$^{2+}$ removal rate. The Pb$^{2+}$ removal by crab shell was greater than that by chitin and chitosan. The role of chitin was not so great in Pb$^{2+}$ removal by crab shell. The Pb$^{2+}$ removal by chitosan was not exactly correlated to the molecular weight of chitosan. weight of chitosan.

• Journal of Advanced Marine Engineering and Technology
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• 제25권6호
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• pp.1336-1340
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• 2001

Due to increase of air pollution substance, such as $SO_2$,$SO_3$, H2S ,CO, HCI, $Cl_2$ and so on, the operating environment of mechanical equipment and facilities like generating plants, ships, metal structure etc., are acidified and corroded. In these environments, the crevice corrosion of marine facilities frequently occurs at crevice like jointed bolt, gasket or sealant, riveted plates, contact of metal with non-metallic solids etc. Therefore, this paper was studied on the crevice corrosion behavior of mild steel(SS 400) in marine environment. In a variety of NaCl solutions, the aspect of he .crevice corrosion and polarization behavior under the crevice corrosion was investigated. The main results obtained are as follows: 1) Under crevice corrosion, the open circuit potential become less treble as the concentration of NaCl solution increased. 2) The corrosion current density of mild steel was high drained as the concentration of NaCl solution increased by 3.5%, but in the concentration increased over 3.5%, the corrosion current density was low drained. 3) The crevice corrosion is more sensitive to the synergy effect of dissolved oxygen and NaCl.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2007년도 추계학술대회 논문집
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• pp.477-478
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• 2007

• 한국환경보건학회지
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• 제35권3호
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• pp.201-208
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• 2009

Oxidation of phenol in aqueous media by electro-Fenton process using Ru-Sn-Sb/graphite electrode has been studied. Hydrogen peroxide was electrically generated by reaction of dissolved oxygen in acidic solutions containing supporting electrolyte and $Fe^{2+}$ was added in aqueous media. Phenol degradation experiments were performed in the presence of electrolyte media at pH 3. Effect of operating parameters such as current, electrolyte type (NaCl, KCl and $Na_2SO_4$) and concentration, $Fe^{2+}$ concentration, air flow rate and phenol concentration were investigated to find the best experimental conditions for achieving overall phenol removal. Results showed that current of 2 A, NaCl electrolyte concentration of 2g/l, 0.5M concentration of $Fe^{2+}$, air flow rate of 1l/min were the best conditions for mineralization of the phenol by electro-Fenton.

• Membrane and Water Treatment
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• 제2권3호
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• pp.147-158
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• 2011

Membrane distillation process was used for desalination of hot (333 K) geothermal water, which was applied in the plant producing heating water. The investigated water contained 120 g salts/$dm^3$, mainly NaCl. The mineral composition was studied using an ion chromatography method. The obtained rejection of solutes was closed to 100%, but the small amounts of $NH_3$ also diffused through the membrane together with water vapour. However, the composition of obtained distillate allowed to use it as a makeup water in the heating water system. The geothermal water under study was concentrated from 120 to 286 g NaCl/$dm^3$. This increase in the solution concentration caused the permeate flux decline by a 10-20%. The geothermal water contained sulphates, which was subjected to two-fold concentration to achieve the concentration 2.4-2.6 g $SO{_4}{^{2-}}/dm^3$ and the sulphates then crystallized in the form of calcium sulphate. As a results, an intensive membranes scaling and the permeate flux decline was observed. The XRD analysis indicated that beside the gypsum also the NaCl crystallites were deposited on the membrane surfaces. The fresh geothermal water dissolved the mixed $CaSO_4$ and NaCl deposit from the membrane surface. This property can be utilized for self-cleaning of MD modules. Using a batch feeding of MD installation, the concentration of geothermal water was carried out over 800 h, without significant performance losses.

• 한국조경학회지
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• 제33권6호
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• pp.90-97
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• 2006

The effects of a green buffer zone to protect a residential area from air pollution from industrial facilities and traffic was examined by analyzing the case of a green buffer zone in the Shiwha industrial complex. The green buffer zone is 175 m wide. The intent was to assess the dispersion patterns of atmospheric air pollutants and the reduction in concentration around the green buffer zone. To measure atmospheric sulfur dioxide$(SO_2)$ and nitrogen dioxide$(NO_2)$ concentration, badge-type passive samplers were used and set up at 76 locations in order to measure the concentration of air pollutants with respect to the spatial dispersion. The weighted mean values of $SO_2\;and\;NO_2$ concentration were $3\~57 ppb\;and\;18\~62 ppb$ and the differences among the green buffer zone, the industrial area and the residential areas were $0.7\~1.1 ppb$. Mean values of atmospheric concentrations of $NO_2$ were similar in industrial and, residential areas and the green buffer zone. Results of the study show that the effect of the green buffer zone on reducing the dispersion of air pollutants was very low. This study also recommends that micro-climate, i.e., wind direction should be considered as a factor for planning and design of green buffer zones.

• KSBB Journal
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• 제20권4호
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• pp.271-277
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• 2005

본 연구에서는 당의 초기농도는 물론 NaCl과 $MgSO_4{\cdot}7H_2O$의 농도가 T. aureum ATCC 34304 균주의 성장특성, 지질의 생성특성 및 DHA의 생성특성에 미치는 영향을 규명하였다. 당농도 15 g/L까지는 당농도가 증가하면 균체증가량에 대한 지질증가량의 비율인 $Y_{Lipid/X}$간과 지질증가량에 대한 DHA 증가량의 비율인 $Y_{DHA/Lipid}$ 값이 모두 증가하였다. $Y_{lipid/X}$와 $Y_{DHA/Lipid}$의 최대값은 0.18 g/g 과 0.41 g/g을로 모두 당의 초기농도 15 g/L에서 나타났다. 반면 균체수율인 $Y_{x/s}$ 값은 당의 초기농도 변화에 관계없이 0.378 g/g으로 일정하였다. 당의 농도변화에 대한 균체의 비성장속도 역시 당농도 15 g/L까지는 최대 $0.79\;day^{-1}$까지 증가하였으나, 20 g/L에서는 $0.57\;day^{-1}$로 감소하였으며, 그 이상의 당농도에서는 증감현상을 나타내지 아니하였다. 해수배지 조성을 기본으로 하고 NaCl 농도를 0.1 g/L에서 48 g/L까지 변화시켰을 때 NaCl의 농도가 0 g/L인 경우 균체의 성장, 지질의 생성 및 DHA의 생성이 모두 정지되었으며, NaCl 24 g/L에서 균체성장, 지질생성 및 DHA의 생성이 최대값을 나타내었다. 또한 기본해수배지 조성에 $MgSO_4{\cdot}7H_2O$의 농도를 0 g/L에서 24 g/L까지 변화시켰을 때, $MgSO_4{\cdot}7H_2O$ 0 g/L에서는 균체성장, 지질생성 및 DHA 생성이 정지되었으며, $MgSO_4{\cdot}7H_2O$ 18 g/L에서 균체성장, 지질생성 및 DHA의 생성이 최대값을 나타내었다.

• 도시과학
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• 제9권2호
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• pp.31-44
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• 2020

This study aims to analyze the relations among greenbelt, air pollution empirically in order to assess the environmental effects of the greenbelt in the Seoul metropolitan area, objectively. For this purpose, this study conducts an empirical analysis of impacts of greenbelt on urban air pollution using a multiple-regression model. The major findings are summarized as follows. As a result of an empirical analysis of the impacts of greenbelt on air pollution, it is found that the characteristics of the city have impacts on air pollution concentration. It is found that the population and employment are the causes of increases in CO and NO2 concentrations, and the number of employees in the manufacturers has impacts on increases of O3 and SO2, while power plants have impacts on PM10, CO and NO2. Intersections have impacts on O3 and SO2, while the areas of the roads have impacts on CO and NO2. In addition, as for the spatial distribution of air pollutants, it is found that CO and NO2 concentrations are relatively higher in the center of the Seoul metropolitan area, while PM10, O3 and SO2 concentrations are relatively higher in the suburbs. It is found that air pollution concentration is low in greenbelt zone. In the greenbelt zone, PM10, CO and SO2 concentrations are low.

• 한국대기환경학회지
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• 제24권4호
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• pp.415-422
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• 2008

This study was carried out to investigate the effect of operating and design conditions of gas dispersion type of absorber on $SO_2$ removal efficiency. pH difference between upper and lower part of gas dispersing plate of absorber was 0.2, which was relatively low. This was supposed that recirculation capacity of absorbing liquid between froth zone and reaction zone of absorber be increased by oxidation air injection through liquid riser which acted as liquid pump. Test results showed that $SO_2$ removal efficiency was more sensitive than absorber ${\Delta}P$. High $SO_2$ removal even at lower pH resulted from very low concentration of $HSO_3^-$ ion in absorbing liquid because of direct supply of dissolved oxygen into froth zone. 96% of $SO_2$ removal efficiency was obtained under the condition of absorber pH 5.2, flue gas flow rate of $1,530\;Nm^3/hr$, inlet $SO_2$ concentration of 800 ppm, absorber ${\Delta}P$ of 250mmAq. The following equation by a multiple linear regression was obtained to describe the relationship between $SO_2$ removal and operating variables. $$f=1-{\exp}(-1.3939+1.060pH+0.0139{\Delta}P-0.00267G-0.000064SO_2Conc.),\;R^2=0.9719$$

• 대한안전경영과학회지
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• 제16권2호
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• pp.237-246
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• 2014

Researches on the elimination of sulfur and nitrogen oxides with catalysts and absorbents reported many problems related with elimination efficiency and complex devices. In this study, decomposition efficiency of harmful gases was investigated. It was found that the efficiency rate can be increased by moving the harmful gases together with SPCP reactor and the catalysis reactor. Calcium hydroxide($Ca(OH)_2$), CaO, and $TiO_2$ were used as catalysts. Harmful air polluting gases such as $SO_2$ were measured for the analysis of decomposition efficiency, power consumption, and voltage according to changes to the process variables including frequency, concentration, electrode material, thickness of electrode, number of electrode winding, and additives to obtain optimal process conditions and the highest decomposition efficiency. The standard sample was sulfur oxide($SO_2$). Harmful gases were eliminated by moving them through the plasma generated in the SPCP reactor and the $Ca(OH)_2$ catalysis reactor. The elimination rate and products were analyzed with the gas analyzer (Ecom-AC,Germany), FT-IR(Nicolet, Magna-IR560), and GC-(Shimazu). The results of the experiment conducted to decompose and eliminate the harmful gas $SO_2$ with the $Ca(OH)_2$ catalysis reactor and SPCP reactor show 96% decomposition efficiency at the frequency of 10 kHz. The conductivity of the standard gas increased at the frequencies higher than 20 kHz. There was a partial flow of current along the surface. As a result, the decomposition efficiency decreased. The decomposition efficiency of harmful gas $SO_2$ by the $Ca(OH)_2$ catalysis reactor and SPCP reactor was 96.0% under 300 ppm concentration, 10 kHz frequency, and decomposition power of 20 W. It was 4% higher than the application of the SPCP reactor alone. The highest decomposition efficiency, 98.0% was achieved at the concentration of 100 ppm.