• Journal of Korean Society of Water and Wastewater
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• v.14 no.1
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• pp.62-75
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• 2000

Most of biological treatment to remove contaminants in municipal wastewater have been conducted by activated sludge process. But, the process have several probIems such as enormous site needed for construction of treatment facilities, unstable treatment due to limited ability to control load fluctuation, frequent sludge bulking and appearance of lots of surplus sludge. In this study, the experiments were performed through submerging biofilm of PEPP media in existing aeration tank with raw water from municipal wastewater treatment plant and then submerging PVDC and PEPP media, different from shape and chemical peculiarity in anoxic reactor. Throughout the experience, nutrient removal efficiency according to HRT, nitrogen phosphorous removal efficiency, behavior of nitrogen and dewatering efficiency have been compared and analysed with those of activated sludge process. As the results, BOD removal efficiency according to BOD volumetric load and F/M ratio was not found any differency in two processes, but was decreased below 90% as going along the condition of high load in activated sludge process. Kinetic coefficient was $K_{max}=1.162day^{-1}$, $K_s=53.77mg/L$, $Y=0.166mgVSS/mgBOD_{rem}$. and $K_d=0.019day^{-1}$. It was found that the removal efficiency, even though in aerobic condition, in biofilm process equipped anoxic reactor was higher than the one in activated sludge process within the range of 70~80%, and became better as HRT increased. Phosphorous removal efficiency was not found any differency in two processes. In biofilm process, treament efficiency even in conditions of high load was not decreased, because the biomass concentration could be maintained in high condition compared with activated sludge process. As HRT increased, suspended and attached biomass was increased and the other hand, F/M ratio was decreased as biomass' increasing. Biomass thickness was increased. from $10.43{\mu}m$ to $10.55{\mu}m$ as HRT increased and density of biomass within $40.79{\sim}41.16mg/cm^2$. The results also present that the dewatering efficiency of sludge generated in biofilm process was higher than in activated sludge process, and became better as HRT increased.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.4
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• pp.545-558
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• 2006

The current conditions of large water mains are evaluated by deteriorations and the causes of deterioration are investigated through visual assessments in the field, mechanical tests and analysis of chemical compositions in laboratory for each pipe material, unlined cast iron pipes (CIPs), ductile iron pipes (DCIPs) and steel pipes (SPs) Tubercles and scales from internal and external corrosion of unlined cast iron pipes were identified as the causes of functional performance limitations in large water mains. It is investigated that main causes of internal and external corrosion of water pipes are from lots of depositions of organic and inorganic substances on pipe surface, concentrated pitting, and uniform corrosion by local or global exfoliation or detachment of lining and coatings of DCIPs and SPs. Internal and external corrosion depths of CIPs were higher than those of DCIPs and SPs. Consequently, total corrosion rate summed internal and external corrosion rates of CIPs also were shown to be higher than those of DCIPs and SPs. The failure time from hole generation of CIPs by total corrosion rate was predicted to be taken sixteen years, and DCIPs and SPs were twenty-six years and one hundred and fifty three years. And longitudinal deflection of investigated water mains were not happened and mechanical strengths such as tensile strength, elongation, and hardness also were mostly suited to Korea Standards. It was thought that the weakness of tensile strength of one sample(S-11) was, however, due to higher carbon contents(%) in CIPs. Pipe deterioration score of S-46 was 55.2 and was preferentially assessed to be rehabilitated.

• Journal of the Korean housing association
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• v.22 no.4
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• pp.103-112
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• 2011

The purpose of this study was to determine the incomplete aspects of the government pilot project 'Livable City Making' Also, the study was conducted to consider a plan that residents will satisfy for the realization of the project. The study used a case study and a survey method in research process. For the case study, two projects in Busan that have similar planning were chosen. The contents of the survey included the residents' interest in their housing area, their recognition and opinions of the pilot project, their satisfaction about the environmental alterations, and their thought about conditions of sustainable housing. The main results of this study were as follows. First, the residents were satisfied with the alteration of the street space and the provision of green and open spaces. Meanwhile they revealed that the preservation of the natural environment and the vitalization of community are insufficient. Second, they also believed that the construction of the pedestrian streets, the provision of parking lots, and the remodeling of the deteriorated buildings are incomplete. Third, the residents believed that the following provisions need to be made for successful sustainable housing waste discharge needs to be minimized, facilities need to be used for saving energy, opportunities for employment need to be provided within their housing areas, and safe street spaces and comfortable traffic systems need to be provided.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.9
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• pp.1193-1200
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• 2001

There are many regulation test methods to be related with engine emissions such as CVS-75, D-13, ECE-15 modes and so on. Most of these modes are consisted of lots of transient conditions that have rapid acceleration, deceleration and cranking modes. In this experimental research, the engine characteristics of cranking, accelerating and power output in a S.I. engine were studied to compare with neat gasoline and alternative fuels of M30 (methanol 30%, aromatic series 32%, non-aromatic 38%) and M50 (methanol 50%, aromatic 30%, non-aromatic 20%) for performance and exhaust emissions. The results show that reformulated methanol fuels are better emissions reduction of 15.7% over than that of neat gasoline fuel especially in HC and CO emissions at cranking mode. And the accelerating performances coincide with the results of distillation curve. CO concentration for M50 fuel is varied in a just little for the condition of slow acceleration. At wide-open throttle condition, brake specific energy consumption of reformulated fuels is increased and thermal efficiency is some what lower than that of gasoline fuel.

• The Korean Journal of Mycology
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• v.35 no.1
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• pp.11-27
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• 2007

This study was conducted to investigate the diversity of higher fungi in NaeJangSan National Park from April 2004 to November 2006. The obtained results from investigation were as follows. The total of 5 classes, 19 orders, 60 families, 168 genera and 418 species (including 10 families, 13 genera and 15 species unrecorded) including saprophytic and ectomycorrhizal fungi was investigated. The higher fungi were classified into 47 families, 143 genera and 384 species in Basidiomycotina, 9 families, 19 genera and 28 species in Ascomycotina and 4 families, 6 genera and 6 species in Myxomycota. It was turned out that most of the higher fungi belong to Hymenomycetidae in Basidiomycotina, for which 34 families 122 genera, and 353 species were observed. Dorminant species belonged to Tricholomataceae(64 species) Russulaceae(39 species), Polyporaceae(36 species) and Boletaceae(36 species). The mushroom occurrence of higher fungi was closely related to climatic conditions such as high air temperature and lots of rainfall from July to September. The environment which has a favorable influence of mushroom occurrence was air temperature, relative humidity and rainfall of climatic environment.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.4
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• pp.333-342
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• 2009

Three-level Diode Clamped Multilevel Inverter, generally known as Neutral-Point-Clamped (NPC) Inverter, has an inherent problem causing Neutral Point (NP) potential variation. Until now, in many literatures NP potential problem has been investigated and lots of solutions have also been proposed. However, under fault and fault tolerant control, distinctive feature for NP potential variation problem was rarely published from the standpoint of reliability. In this paper, NP potential is analytically investigated both normal and faulty conditions under carrier based PWM. Subsequently, relation between fault detection time and size of capacitor is analyzed. This information is explored by simulation and experiment results, which contribute to enhance the reliability of inverter system.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.4
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• pp.152-159
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• 2014

Urea solution as a reductant of SCR has been widely used to reduce NOx emissions from diesel engine. But it has lots of problems which are freezing at low temperature due to liquid state, deposition of solid formation in the exhaust, dosing device, and complex package such as mixers for uniform concentration of ammonia. In order to overcome these obstacle, ammonium carbonate which is one of solid ammonium materials to produce ammonia gas directly by sublimation process is considered. Simple reactor with visible widow was designed to predict equilibrium temperature and pressure of ammonium carbonate. To simulate real operation conditions under automobile environment, several cycles of heating and cooling condition were settled, two different re-solidification materials were extracted from the reactor and visible window. Analytical study is performed to characterize these unknown materials by XRD(X-Ray Diffraction), FT-IR(Fourier Transform Infrared Spectroscopy), and EA(Elemental Analyzer). From analytical results, re-solidification materials from heating and cooling cycles are very similar to original material of ammonium carbonate.

• Journal of the Korea Fashion and Costume Design Association
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• v.12 no.4
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• pp.149-157
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• 2010

After observing various changed colors by some dyeing conditions in case of the Indio and Indigo Pulberata Levis, we had below result. 1. Best reduction temperature for Indigo was $50^{\circ}C$, and the reduction temperature had an effect on level dyeing and dye-uptake. For the Indigo Pulberata Levis, best reduction temperature was $60^{\circ}C$, and best reduction time for Indigo was 20 minutes, for the Indigo Pulberata Levis was 30~40 minutes. 2. Both Indigo and Indigo Pulberata Levis showed high K/S without using alkali, but it was almost not possible to be dyed without reduction agent. The best amount of potassium carbonate concentration and soldium hydrosulfite concentration was $2{\sim}3g/{\ell}$ and $2g/{\ell}$ each for dyeing. 3. The best dyeing temperature for Indigo was $30^{\circ}C$ and $60^{\circ}C$ for Indigo Pulberata Levis. 4. In case of Indigo, K/S increased slightly at $5g/{\ell}$ concentration. Thus, $5g/{\ell}$ is efficient amount. However, it needed $50g/{\ell}$ to increase K/S for Indigo Pulberata Levis. It tells that we need a lot of Indigo Pulberata Levis for dyeing dark color. 5. Indigo dyed cotton looked more greener than silk. Since silk absorbs lots of red color, it looked strong red color. However, Indigo Pulberata Levis looked greenish on both cotton and silk. 6. Since the hue's range of Munsell's value was PB for both Indigo and Indigo Puberata Levis, we are able to know that red color's indirubin is contained as well as blue color's indigo.

• Journal of Korean Society on Water Environment
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• v.29 no.5
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• pp.641-647
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• 2013

We installed mesocosms including zooplankton, fishs, artificial marshy land and aquatic macrophytes in Kyoungan stream to study the reduction effects of algae from Sep. 16 to Oct. 28, 2011. The control tendency of phytoplankton taxa was compared by analyzing community structure and dominant species in each mesocosm. Under the condition where Bluegill was absent, Daphnia similoides showed good effect of algal control since it has large food area and has high grazing pressure. Bluegill selectively preys upon large zooplankton, Daphnia similoides, as it also preys on small zooplanktons that flow in. In condition that Bluegill was absent, Daphnia similoides preyed selectively large phytoplankton (Cryptomonas ovata). Due to the shading of light, removal of nutrients and providing refuge for small zooplanktons, aquatic macrophytes and artificial marshy land showed high level of algal control. In corrals with aquatic macrophytes and artificial marshy land, the dominancy of genus Coelastrum and Pediastrum, which are difficult for small zooplanktons to feed on, relatively increased. In conclusion, under conditions of small number of predators such as Bluegill, Daphnia similoides is thought to be useful in algal bloom; however, when lots of predators are present, using small sized zooplanktons along with artificial marshy land and aquatic macrophytes is thought to be more useful than using large zooplanktons.

• Journal of Korean Society of Transportation
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• v.29 no.1
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• pp.113-123
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• 2011

The application of micro-simulation model has been extended farther with improvement of computer performance and development of complicated model. To make a micro-simulation model accurately replicate field traffic conditions, model calibration is very crucial. Studies on calibration of micro-simulation model have not been enough while lots of studies on calibration of macro-simulation model have been continued in our country. This paper presents an auto-calibration of parameter values in micro-simulation model(VISSIM) using genetic algorithm. RMSE(Root Mean Square Error) of collected volume on the urban expressway versus simulated volume is set as MOP(measure of performance) and objective function of optimization is set as to minimize the RMSE. Applying to urban expressway(Nae-bu circular) as a case study, it shows that RMSE of optimized parameter values decrease 60.4%($19.3{\longrightarrow}7.6$) compared to default parameter values and the proposed auto-calibration system is very effective.