• Journal of Korean Society of Environmental Engineers
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• v.35 no.12
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• pp.889-896
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• 2013

Advanced Oxidation Processes (AOP) have been interested for removing micropollutants in water. Most of water treatment plants (WTPs) located along the lower part of Nakdong River have adopted the $O_3/BAC$ process and have interesting in peroxone process a kind of AOP. This study evaluated the removal characteristics of residual hydrogen peroxide ($H_2O_2$) combining with the biofiltration process in the next BAC process when the hydrogen peroxide is applied for the WTP operating $O_3/BAC$ process. In the experiment, changing the temperature and the concentration of $H_2O_2$ of influent, the biofiltration process showed rapidly dropped the biodegradability when the $H_2O_2$ concentration was increased and lowered water temperature while BAC process maintained relatively stable efficiency. The influent fixed at $20^{\circ}C$ and the concentration of $H_2O_2$ at 300 mg/L was continuously input for 78 hours. Most of the $H_2O_2$ in the influent did not remove at the biofiltration process controlled 5 to 15 minutes EBCT condition after 24~71 hours operating time while BAC process controlled 5 to 15 minutes EBCT showed 38~91% removal efficiency condition after 78 hours operating time. Besides, after 78 hours continuously input experiment, the biomass and activity of attached bacterial on the biofilter and BAC were $6.0{\times}10^4CFU/g$, $0.54mg{\cdot}C/m^3{\cdot}hr$ and $0.4{\times}10^8CFU/g$, $1.42mg{\cdot}C/m^3{\cdot}hr$ respectively. These biomass and activity values were decreased 99% and 72% in biofilter and 68% and 53% in BAC compared with initial condition. The biodegradation rate constant ($k_{bio}$) and half-life ($t_{1/2}$) in BAC were decreased from $1.173min^{-1}$ to $0.183min^{-1}$ and 0.591 min to 3.787 min respectively according to increasing the $H_2O_2$ concentration from 10 mg/L to 300 mg/L at $5^{\circ}C$ water temperature and the $k_{bio}$ and $t_{1/2}$ were $1.510min^{-1}$ to $0.498min^{-1}$ and 0.459 min to 1.392 min at $25^{\circ}C$ water temperature. By increasing the water temperature from $5^{\circ}C$ to $15^{\circ}C$ or $25^{\circ}C$, the $k_{bio}$ were increased 1.1~2.1 times and 1.3~4.4 times. If a water treatment plant operating $O_3/BAC$ process is considering the hydrogen peroxide for the peroxone process, post BAC could effectively decrease the residual $H_2O_2$, moreover, in case of spilling the $H_2O_2$ into the water process line, these spilled $H_2O_2$ concentration can be able to decrease by increasing the EBCT at the BAC process.

• Aerospace Engineering and Technology
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• v.13 no.2
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• pp.80-86
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• 2014

In this study, we the estimated surface normalized difference vegetation index by using the KOrea Multi-Purpose SATellite-3 (KOMPSAT-3) multi-spectral images for comparative analysis. The estimated NDVI from KOMPSAT-3 is used as for comparison with the high resolution GeoEye products. The geometry conditions for atmospheric effects are selected from meta files of KOMPSAT-3 bundle data. The used geometry conditions are consist of solar zenith angle, solar azimuth angle, viewing zenith angle, viewing azimuth angle, and date. And, Atmospheric effects such as attenuation, scattering and absorption were physically simulated from water vapor, ozone and aerosol information. Generally, although ground measurements are important for accurate information, in this study, MODIS atmospheric products are used as atmospheric constituents. The surface reflectance from radiative transfer model is utilized for estimating vegetation index. The present study, to reduce atmospheric and geometry conditions between KOMPSAT-3 and GeoEye having difference observation characteristics, data acquisition time is carefully determined for reliable vegetation spectral characteristics.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.4
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• pp.473-483
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• 1996

To protect the ozone layer, R22 will be replaced with HFCs. R407C is a leading candidate as alternative refrigerant for air conditioner due to its similar thermodynamic characteristics with R22. In replacing R22 with R407C, the compatibility with lubricating oil is of major concern. Polyol ester (POE) oil among the synthetic oils is considered to be the best lubricant for use with R407C because of good electrical properties and miscibility. However, lubricating ability of mixture of R407C/POE oil is lower than that of R22/mineral oil due to the production of acid by hydrolysis which causes corrosive wear. Therefore, to minimize water content, it is needed to develop a molecular sieve desiccant which is compatible with R407C and ester oil. This paper discusses (1) the change of properties of POE oil when current molecular seive is used, (2) the effects of POE oils and additives on durability of compressor. Through compressor life test and bench wear test, it was found that inadequate use of POE oils and additives may promote the deteriation of molecular sieve, resulting in decrease of durability of compressor.

• Korean Chemical Engineering Research
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• v.52 no.6
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• pp.755-767
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• 2014

Chlorine is one of the most produced and most used non-flammable chemical substances in the world even though its toxicity and high reactivity cause the ozone layer depletion. However, in modern life, it is impossible to live a good life without using Chlorine and its derivatives since they are being used as an typical ingredient in more than 40 percent of the manufactured goods including medicines, detergents, deodorant, fungicides, herbicides, insecticides, and plastic, etc. Even if Chlorine has been handled and distributed in various business (small and medium-sized businesses, water purification plants, distribution company, etc.), there have been few researches about its possible health hazard and transportation risks. Accordingly, the purpose of this paper is to make a detailed assessment of Chlorine-related risks and to model an index of chemicals transportation risks that is adequate for domestic circumstances. The assessment of possible health hazard and transportation risks was made on 13 kinds of hazardous chemicals, including liquid chlorine. This research may be contributed to standardizing the risk assessment of Chlorine and other hazardous chemicals by using an index of transportation risks.

• Journal of the Korean earth science society
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• v.37 no.7
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• pp.465-475
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• 2016

The diurnal and semidiurnal tides in the global atmosphere are examined using 3-hourly geopotential height field of the state-of-the-art reanalysis data. Unlike the previous studies, the spatial structure and seasonality of those tides are analyzed from the surface of the earth to the stratosphere. It is found that, at most levels, diurnal tide is strong in the midlatitudes while semidiurnal tide is predominant in the tropics. The former shows strong seasonal cycle with a larger amplitude in summer than in winter in both hemispheres. This is different from the semidiurnal tide which has essentially no seasonal cycle. In term of the vertical structure, while semidiurnal tide has a barotropic structure, diurnal tide exhibits a distinct vertical structure with increased amplitude and height. Especially tropical diurnal tide exhibits a nearly opposite phase from the surface to the free troposphere, and to the upper stratosphere. Its amplitude also varies nonlinearly with height, possibly influenced by water vapor, ozone, gravity waves and solar radiation.

• International Journal of Vascular Biomedical Engineering
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• v.2 no.2
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• pp.1-9
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• 2004

The history of studies in biology regarding reactive oxygen species (ROS) is approximately 40 years. During the initial 30 years, it appeared that these studies were mainly focused on the toxicity of ROS. However, recent studies have identified another action regarding oxidative signaling, other than toxicity of ROS. Basically, it is suggested that ROS are reactive, and degenerate to biomolecules such as DNA and proteins, leading to deterioration of cellular functions as an oxidative stress. On the other hand, recent studies have shown that ROS act as oxidative signaling in cells, resulting in various gene expressions. Recently ROS emerged as critical signaling molecules in cardiovascular research. Several studies over the past decade have shown that physiological effects of vasoactive factors are mediated by these reactive species and, conversely, that altered redox mechanisms are implicated in the occurrence of metabolic and cardiovascular diseases ROS is a collective term often used by scientist to include not only the oxygen radicals($O2^{-{\cdot}},\;{^{\cdot}}OH$), but also some non-radical derivatives of oxygen. These include hydrogen peroxide, hypochlorous acid (HOCl) and ozone (O3). The superoxide anion ($O2^{-{\cdot}}$) is formed by the univalent reduction of triplet-state molecular oxygen ($^3O_2$). Superoxide dismutase (SOD)s convert superoxide enzymically into hydrogen peroxide. In biological tissues superoxide can also be converted nonenzymically into the nonradical species hydrogen peroxide and singlet oxygen ($^1O_2$). In the presence of reduced transition metals (e.g., ferrous or cuprous ions), hydrogen peroxide can be converted into the highly reactive hydroxyl radical (${^{\cdot}}OH$). Alternatively, hydrogen peroxide may be converted into water by the enzymes catalase or glutathione peroxidase. In the glutathione peroxidase reaction glutathione is oxidized to glutathione disulfide, which can be converted back to glutathione by glutathione reductase in an NADPH-consuming process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.11
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• pp.6412-6418
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• 2014

This paper performed a numerical study of an air-liquid ejector. An ejector is a fluid-transportation device that spouts high-pressure fluid from driving pipes using the kinetic energy of the spouted fluid and increases the pressure through the exchange of momentum with the surrounding gases of the lower pressure. The air-liquid ejector was investigated through steady three-dimensional multiphase CFD analysis using commercial software ANSYS-CFX 14.0. Water as the primary fluid is driven through the driving nozzle and air is ejected as the second gas instead of ozone in real applications. The difference in performance according to the shape of the diffuser of the ejector was examined. The results provide deep insight into the influence of various factors on the performance of the air-liquid ejector. The proposed numerical model will be very helpful for further design optimization of the air-liquid ejectors.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.3
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• pp.429-439
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• 2000

Various wastewater treatment technologies were applied for decolorization and disposal of the wastewater containing the pigments, which consist of Lake Red C(Barium) or/and Lithol Rubine(Calcium) pigments. In an application of ozonation $COD_{Mn}$ was generally decreased with an increase of amounts of ozone applied, however, the decolorization effect was not that good except for Lithol Rubine series. In an application of Fenton oxidation and electrochemical process, a good $COD_{Mn}$ removal effect for all the pigment wastewater and a slight decolorization effect for a part of Lithol Rubine series were observed. In an application of ultra filtration(UF) and reverse osmosis(RO), an excellent $COD_{Mn}$ removal and decolorization(almost 100%) effects of all the pigment wastewater were observed. Thus the water treated by the UF and RO could be reusable and thus save operating costs of the pigment manufacturing plants.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.30 no.2
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• pp.100-106
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• 2018

Recently, the development of a heat pump technology to recover process waste heat and to generate steam of $120^{\circ}C$ or higher required for industrial processes, has attracted attention. The research of conventional heat pump utilizing the available energy is used primarily for air conditioning, and the production temperature is about $60^{\circ}C$, so it is difficult to utilize it for industrial use. Therefore, in this study, we developed a steam heat pump (SGHP) which recovers the waste heat of process and generates steam at $120^{\circ}C$. The low-pressure refrigerant R245fa, considered to be an eco-friendly refrigerant, has been selected as the refrigerant for SGHP in this study since its Ozone Depletion Potential (ODP) is zero and the Global Warming Potential (GWP) is relatively low. A flash tank functioning as a phase separator was installed in the rear stage of the condenser, and the saturated water of high temperature was decompressed to generate steam. It was started at the initial temperature of $70^{\circ}C$, and it was confirmed that $120^{\circ}C$ steam was produced after the system stabilized. We have conducted experiments by modifying the system, and ultimately achieved a heating capacity of 101.4 kW and a COP of 3.05.

• Ocean and Polar Research
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• v.27 no.1
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• pp.87-95
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• 2005

The vertical profiles of radiative flux and heating rate at King Sejong Station in West Antarctica were calculated with radiative transfe model by Chou and Suarez (1999) and Chou et al (2001). To run this model, the profiles of temperature, mixing ratios of water vapor and ozone at King Sejng Station were derived from ECMWF Reanalysis data. The surface temperature and albedo were also derived from NCEP/NCAR Reanalysis and CERES data. The radiative flux strongly depends on the cloud optical path length that was calculated using the measured W-h data and model by Chou and Lee(1996). Durins the period of $2000{\sim}2001$ (12 and 18 UTC), the correlation coefficient between calculated and measured downward solar fluxes at surface was 0.90 and the coefficient for downward longwave flux was 0.61. The calculated net heating rates of surface layer decreased during the same period, the trend of which was in accordance with the decrease of measured temperature.