• Journal of the Korea Organic Resources Recycling Association
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• v.18 no.1
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• pp.57-65
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• 2010

Two types of microbial fuel cells(MFC) were continuously operated using synthetic wastewater. One was conventional two-chambered MFC using proton exchange membrane(PEM-MFC), the other was upflow type membraneless MFC(ML-MFC). Graphite felt was used as a anode in PEM-MFC. In membraneless MFC, two MFCs were operated using porous RVC(reticulated vitreous carbon) as a anode. Graphite felt was used as a cathode in all experiments. In experiment of PEM-MFC, the COD removal rate based on the surface area of anode was about $3.0g/m^2{\cdot}d$ regardless of organic loading rate. And the coulombic efficiency amounted to 22.4~23.4%. The acetic acid used as a fuel was transferred through PEM from the anodic chamber to cathodic chamber. The COD removal rate in ML-MFC were $9.3{\sim}10.1g/m^2{\cdot}d$, which indicated the characteristics of anode had no significant effects on COD removal. Coulombic efficiency were 3.6~3.7 % in both cases of ML-MFC experiments, which were relatively small. It was also observed that the microbial growth in cathodic chamber had an adverse effects on the electricity generation in membraneless MFC.

• Progress in Medical Physics
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• v.20 no.2
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• pp.106-111
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• 2009

Total scatter factor ($S_{cp}$), head scatter factor ($S_c$) and phantom scatter factor ($S_p$) are very important for accurate radiation therapy at stereotactic radiosurgery (SRS) with irregular field shape using micro-MLC and intensity modulated radiation therapy (IMRT) including many small field sizes. In this study we measured and compared $S_{cp}$ with reference ion chamber, pinpoint chamber and diode detector and adapted the resuls form diode detector. Head scatter factors for small field sizes were also measured with diode detector covered 1.5 cm-thick solid water build-up cap. Some errors like as electron contamination of 1~3% were included in the values of Sc but trend of total results of $S_c$ was coincided with basic theory. Phantom scatter factors for small field sizes were calculated form $S_{cp}$ and $S_c$. The results of $S_p$ were compared and were well-agreed with those of other authors.

• Progress in Medical Physics
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• v.19 no.4
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• pp.305-312
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• 2008

The aim of this study is to introduce the accuracy of Ir-192 source's apparent activity using the well-type chamber and the Farmer-type ionization chamber in the high dose rate brachytherapy. We measured the apparent activity of Ir-192 that each medical center in the country has and the apparent activity of calibration certificate provided by manufacturer is compared with that by our experimental measurement. The number of sources used for the activity comparison was 5. The accuracy of the measured activity was in the range of -2.8% to -1.0% and -2.1% to 0.2% for the Farmer-type chamber system (Jig) and for the well-type, respectively. The maximum difference was within 1.0% for comparison with two calibration's tool. Our results demonstrate that well-type chamber as wall as Farmer-type chamber is a appropriate system as the routine source calibration procedures in HDR brachytherapy. Whenever a new source is installed to use in clinics, by periods, a source calibration should be carried out.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.1222-1229
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• 2012

The total area of a reclaimed tidal soil distributed on the south-west coast is approximately 156,600 ha, and the soil contains high contents of sand and silt as well as highly saline. Most of the reclaimed tidal soils are used as a paddy due to bad permeability and high groundwater table, resulting in easy accumulation of salts on the soil surface by capillary rise. Therefore, resalinization may occur because of rise of groundwater table after desalinization. The researches related to the reclaimed tidal soil mainly focused on desalinazation while most of the researches completed were limited to yields of crop based on desalinazation. pH of old reclaimed tidal soil is neutral or less than 7 while that of newly developed reclaimed tidal soils is greater than 7, that cause N-fertilizer to be volatile as ammonia. Thus, the physical and chemical properties should be investigated to be used as an arable upland instead of a paddy soil due to change in government policy. We need to develop measures to make soils grow crops normally by identifying problems related to reclaimed tidal soils.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.2
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• pp.137-145
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• 2008

An experimental study was performed in order to investigate the influence of Reynolds number on the drag coefficient variations of an oscillating airfoil. A NACA 0012 airfoil was sinusoidally pitched at the quarter chord point with an oscillating amplitude of ${\pm}6^{\circ}$. The free-stream velocities were 1.98, 2.83 and 4.03 m/s and the corresponding chord Reynolds numbers were $2.3{\times}10^4$, $3.3{\times}10^4$ and $4.8{\times}10^4$, respectively. The drag coefficient was calculated from the ensemble average velocity measured by an X-type hot-wire probe(X-type, 55R51) in the near-wakes region. In the case of Re=$2.3{\times}10^4$, variation of drag coefficient shows a negative damping (counter-clockwise variation), which implies an unstable state which could be excited by aerodynamic force, whereas the drag coefficient represents the positive damping (clockwise variation) as the Reynolds number increases from Re=$3.3{\times}10^4$ to $4.8{\times}10^4$. Hence, the drag coefficient variations show significant differences between Re=$2.3{\times}10^4$ and $4.8{\times}10^4$이다.

• Journal of the Korean Society for Library and Information Science
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• v.47 no.3
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• pp.407-435
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• 2013

The purpose of this study is to have the development of special libraries in Korea and produce policy alternatives and current implications as well as to analyze the management evaluation of Korea special libraries in 2011. The evaluation of 39 detailed index scored at 51.8 out of 100. There were five evaluation territory. Among them, the facility environment's score was the highest as 77.3 and manpower was 53.5, library management were 51.0. The information resource and service territory were analyzed under 50 as scored 49.3 and 45.4. Closely look at the detailed index, the highest index was 'user amenity' (96.7) from facility environment and the lowest index was 'participation record of the long-term educational training of library staff' (13.0). This study diagnosed current management of libraries and problem as well as to analyze the result of administration evaluations of special libraries in nation throughout 2012. The institution type of special libraries in Korea is very varied such as central administrative agency, government-funded research institute, local government, and education office in local-affiliated institute, business, private organization, hospital, the press and so on; therefore, the analysis result can be utilize for basic information to provide future special libraries type in order to make differentiated policy making.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.10 no.6
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• pp.62-72
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• 1996

In this paper, ozonizer using U-type lamp(Olamp) has been designed and manufactured, which can perform a role of lighting source and ozonizer by using photo and chemical methods. The discharge, spectrum, illuminance, ozone concentration, ozone generation, ozone yield and sterilization characteristics of Olamp have been studied. The important conclusions obtained from this paper can be summa'||'&'||'not;rized as follows. As a result of spectrum characteristics for Olamp, ultraviolet ray of a short wave'||'&'||'not;lengths and a visible ray are radiated. The illuminance of Olamp was found to be useful for "color distinctive and intermittent works in the dark working spaces" in accordance with KS A 3011. The ozone concentration of gaseous phase is inversely proportional to quality of supplied gas. Also, ozone conce tration and generation of gaseous phase are rised more commercial oxygen gas than those trial air gas for constant quality of supplied gas. Ozone generation and ozone yield of gaseous phase are proportion'||'&'||'not;al to ozone concentration of gaseous phase. The characteristics of liquid ozone concentration at distilled water are proportional to circulating velocity of fermentation chamber and ozone concentration of gas'||'&'||'not;eous phase. As a result, the sterilization characteristics of Escherichia coli have been obtained more than 97[ % J.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.6
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• pp.706-714
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• 2020

Currently, 90 % of the world's population breathes air with a fine dust content exceeding the World Health Organization's annual average exposure limit (10 ㎍/㎥). Global efforts have been devoted toward reducing secondary pollutants and ultra-fine dust through regulations on nitrogen oxides released over land and sea. Domestic efforts have also aimed at creating clean marine environments by reducing sulfur emissions, which are the primary cause of dust accumulation in ships, through developing and distributing environment-friendly ships. Among the technologies for reducing harmful emissions from diesel engines, electrostatic precipitator offer several advantages such as a low pressure loss, high dust collection efficiency, and NOx removal and maintenance. This study aims to increase the durability of a ship by improving equipment quality through failure mode effects analysis for the preventive maintenance of an electrostatic precipitator that was developed for reducing fine dust particles emitted from the 2,427 kW marine diesel engines in ships with a gross tonnage of 999 tons. With regard to risk priority, failure mode 241 (poor dust capture efficiency) was the highest, with an RPN of 180. It was necessary to determine the high-risk failure mode in the collecting electrode and manage it intensively. This was caused by clearance defects, owing to vibrations and consequent pin loosening. Given that pin loosening is mainly caused by vibrations generated in the hull or equipment, it is necessary to manage the position of pin loosening.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.9
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• pp.917-922
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• 2005

The wastewaters from textile and dyeing industries are difficult to treat due to its high pH, temperature, color intensity and non-biodegradable organic contents. This study investigated the removal of recalcitrant organics in a dyeing wastewater by using a packed bed reactor (PBR) that contained cell-immobilized pellets. The feed, obtained from an effluent of a biological treatment plant, had $SCOD_{Cr}$ of 330 mg/L and $SBOD_5$ of 20 mg/L on average. In immobilizing the cells to a Polyethylene Glycol(PEG) based medium, activated sludges from either a sewage treatment plant or an industrial wastewater treatment plant were used. When the empty bed contact time (EBCT) was above 8 hrs in the PBR, the $COD_{Cr}$ removal efficiency was over 50% and the $COD_{Mn}$ concentration was 72 mg/L or lower on average, which was substantially lower than the discharge standard of 90 mg/L. The results indicated that the optimum EBCT in the PBR was 8 hrs. The PBR with cell-immobilized pellets was effective as an advanced treatment process after an activated sludge process for treating dyeing wastewaters.

• Journal of Bio-Environment Control
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• v.9 no.4
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• pp.201-206
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• 2000

A certain system to overcome high temperature should be introduced for the stable year-round cultivation in greenhouses. There are efficient methods to overcome high temperature such as ventilation system with shading screen, fan and pad system with screen, and fog system with screen. This study was carried out to find a means to determine the capacity of such system. Heat balance equations for each system were established and verified by experimental results. The calculated ventilation rates from heat balance equations showed a good agreement with the measured ones. The evapotranspiration coefficient was the most important parameter affecting the ventilation requirement among input parameter affecting the ventilation requirement among input parameters except weather data. When the evaportanspiration coefficient increased 1%, the ventilation requirement decreased 1.3%. Therefore the data of evapotranspiration coefficient should be accumulated by various experiments, and then design standards and selection guidelines should be provided. The simulation results for same design conditions shown that air exchanges requirement and evaporating water of fan and pad system were 5.1∼7.7% and 6.8∼9.3% larger than those of fog system, respectively.