• Journal of Mechanical Science and Technology
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• v.17 no.12
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• pp.2053-2065
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• 2003

The current trend in automotive finishing industry is to use more electrostatic rotating bell (ESRB) need space to their higher transfer efficiency. The flow physics related with the transfer efficiency is strongly influenced by operating parameters. In order to improve their high transfer efficiency without compromising the coating quality, a better understanding is necessary to the ESRB application of metallic basecoat painting for the automobile exterior. This paper presents the results from experimental investigation of the ESRB spray to apply water-borne painting. The visualization, the droplet size, and velocity measurements of the spray flow were conducted under the operating conditions such as liquid flow rate, shaping airflow rate, bell rotational speed, and electrostatic voltage setting. The optical techniques used in here were a microscopic and light sheet visualization by a copper vapor laser, and a phase Doppler particle analyzer (PDPA) system. Water was used as paint surrogate for simplicity. The results show that the bell rotating speed is the most important influencing parameter for atomization processes. Liquid flow rate and shaping airflow rate significantly influence the spray structure. Based on the microscopic visualization, the atomization process occurs in ligament breakup mode, which is one of three atomization modes in rotating atomizer. In the spray transport zone, droplets tend to distribute according to size with the larger drops on the outer periphery of spray. In addition, the results of present study provide detailed information on the paint spray structure and transfer processes.

• Journal of Mechanical Science and Technology
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• v.20 no.11
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• pp.1934-1941
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• 2006

As the operating time of heat exchangers progresses, fouling caused by water-borne deposits and the number of plugged tubes increase and thermal performance decreases. Both fouling and tube plugging are known to interfere with normal flow characteristics and to reduce thermal efficiencies of heat exchangers. The heat exchangers of Korean nuclear power plants have been analyzed in terms of heat transfer rate and overall heat transfer coefficient as a means of heat exchanger management. Except for fouling resulting from the operation of heat exchangers, all the tubes of heat exchangers have been replaced when the number of plugged tubes exceeded the plugging criteria based on design performance sheet. This paper describes a plugging margin evaluation method taking into account the fouling of shell-and-tube heat exchangers. The method can evaluate thermal performance, estimate future fouling variation, and consider current fouling level in the calculation of plugging margin. To identify the effectiveness of the developed method, fouling and plugging margin evaluations were performed at a component cooling heat exchanger in a Korean nuclear power plant.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.20 no.2
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• pp.41-49
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• 2014

This study illustrates the synthesis of gelatin based zinc oxide nanoparticle (ZnONPs) incorporated nanocomposite films using different concentrations of ZnONPs. The ZnONPs were oval in shape and the size ranged from 100- 200 nm. The nanocomposite films were characterized by UV-visible, FE-SEM, FT-IR, and XRD. The concentrations of ZnONPs greatly influenced the properties of nanocomposite films. The absorption peaks around 360 nm increased with the increasing concentrations of ZnONPs. The surface color of film did not change while transmittance at 280 nm was greatly reduced with increase in the concentration of ZnONPs. FTIR spectra showed the interaction of ZnONPs with gelatin. XRD data demonstrated the crystalline nature of ZnONPs. The thermostability, char content, water contact angle, water vapor permeability, moisture content, and elongation at break of nanocomposite films increased, whereas, tensile strength and modulus decreased with increase in the concentrations of ZnONPs. The gelatin/ZnONPs nanocomposite films showed profound antibacterial activity against both Gram-positive and Gram-negative food-borne pathogenic bacteria. The gelatin/$ZnONP^{1.5}$ nanocomposite film showed the best UV barrier and antimicrobial properties among the tested-films, which indicated a high potential for use as an active food packaging films with environmentally-friendly nature.

• Korean journal of food and cookery science
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• v.33 no.1
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• pp.65-71
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• 2017

Purpose: This study was carried out to investigate the availability of raw Astragalus membranaceus as a food ingredient. Methods: Raw and dried A. membranaceus water extracts were used to examine the free radical scavenging activity, polyphenol and flavonoid contents, and antimicrobial activity. Also, the sensory characteristics of each water extracts were evaluated. Results: The free radical scavenging activity and total polyphenol and flavonoid contents of raw A. membranaceus extracts were higher than those of dried A. membranaceus extracts. The antimicrobial activities of raw and dried A. membranaceus extracts were examined against several food borne illness-causing microorganisms using the paper disc diffusion method. Inhibition zones were observed in Staphylococcus aureus subsp. aureus, Bacillus subtilis, Pseudomonas aeruglnosa, Salmonella enterica subsp. enterica, Escherichia coli and Bacillus cereus treated with raw extracts. Inhibition zones were observed in B. subtilis, P. aeruglnosa and S. enterica subsp. enterica treated with dried extracts. Raw A. membranaceus extracts had higher scores than dried extracts in sensory evaluation. Conclusion: Raw A. membranaceus was better in antioxidative, antimicrobial activities, and sensory characteristics than dried one.

• Parasites, Hosts and Diseases
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• v.44 no.2 s.138
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• pp.171-174
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• 2006

The status of intestinal parasitic infections and seroprevalence of cystic echinococcosis in the inhabitants In Dornod and Selenge, Mongolia, was observed with stool and serum samples from 165 and 683 residents from August 9 to August 15, 2003. A total of 10 inhabitants (6.1%) were found to be infected with protozoan cysts or oocysts by stool examinations; 7, 1 and 2 cases with Entamoeba coli, Giardia lamblia and Cryptosporidium parvum, respectively. A total of 62 people (9.1 %) revealed significantly high levels of specific antibodies against Echinococcus granulosus by enzyme-linked immunosorbent assay (ELISA). The surveyed areas are rural areas and the sanitized tab water is not available. There is a possibility of endemic transmission of water-borne protozoan diseases in these areas. The clinical echinococcosis is needed to be searched from the seropositive inhabitants.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.11
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• pp.1384-1389
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• 2004

As operating time of heat exchangers progresses, fouling generated by water-borne deposits and the number of plugged tubes increase and thermal performance decreases. Both fouling and tube plugging are known to interfere with normal flow characteristics and to reduce thermal efficiencies of heat exchangers. The heat exchangers of domestic nuclear power plants have been analyzed in terms of the heat flux and heat transfer coefficient at test conditions as a means of heat exchanger management. Except for the fouling level generated in operation of heat exchangers, also, all of the tubes of heat exchangers have been replaced when the number of plugged tubes exceeds the plugging criteria based on design performance sheet. This paper describes the plugging margin evaluation mettled reflected the fouling of shell-and-tube heat exchangers, which can evaluate the thermal performance for heat exchangers, estimate the future fouling variations, and reflect the current fouling level. To identify the effectiveness of the developed method, the fouling and plugging margin evaluations were performed for a component cooling heat exchanger in a nuclear power plant.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.195-195
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• 2020

이 연구는 기후변화 위험에 노출되어 있는 북한에 대한 잠재증발산량의 미래 변화를 전망하였다. 이를 위해 IPCC AR5의 RCP 기후변화 시나리오로부터 모의된 미래 기온자료를 APCC (APEC Climate Center) Integrated Modeling (AIMS)를 사용하여 25개 관측 지점에 대해서 상세화하여, McGuinness-Borne 방법으로 잠재증발산량을 추정하였다. 6개의 성능 지표와 TOPSIS(Technique for Order of Preference by Similarity to Ideal Solution)로 27개 GCMs 간의 과거 기후 재현성을 비교하여, 관측 지점 규모에서 적정 GCM을 선정하였다. 마지막으로 각 지점에서 선정된 대표 시나리오(representative climate change scenarios, RCCS)로 북한 지역의 잠재증발산량의 미래 변화를 3개의 구간(F1: 2011-2040; F2: 2041-2070; F3: 2071-2100)에서 all CCS(climate change scenario)와 비교하고, 미래 변화를 정량적으로 제시하였다. 그 결과 공간 해상도가 더 높은 GCM이 RCCS로 선정되었으며, 미래로 갈수록 잠재증발산량이 증가하리라 전망되었다. 또한, 여름철 잠재증발산량의 모델 간 변동성은 미래 구간에 따라 점진적으로 증가되었고, 연 평균 증발산량은 과거 기후대비 1.4배(F1), 2.0배(F2) 및 2.6배(F3) 증가하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.149-153
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• 2006

Precipitation is the most important component and critical to the study of water and energy cycle. This study investigates the propagation of precipitation retrieval uncertainty in the simulation of hydrologic variables for varying spatial resolution on two different vegetation cover. We explore two remotely sensed rain retrievals (space-borne IR-only and radar rainfall) and three spatial grid resolutions. An offline Community Land Model (CLM) was forced with in situ meteorological data In turn, radar rainfall is replaced by the satellite rain estimates at coarser resolution $(0.25^{\circ},\;0.5^{\circ}\;and\;1^{\circ})$ to determine their probable impact on model predictions. Results show how uncertainty of precipitation measurement affects the spatial variability of model output in various modelling scales. The study provides some intuition on the uncertainty of hydrologic prediction via interaction between the land surface and near atmosphere fluxes in the modelling approach.

• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.7
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• pp.70-82
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• 2003

A pilot study was performed from July 1998 to December 2002, including winter performance, to examine seasonal performance of a constructed wetland and subsequent pond system for treatment of sewage in small communities of Korea. Pond was operated as a intermittent-discharge pond during winter period, and continuous flow system during growing season; its effects was evaluated from December 2001 to April 2003. The subsurface flow (SSF) wetland was satisfactory for treating sewage with good removal efficiency even during the winter period. The wetland effluent concentrations of $BOD_5$ and TSS were often higher in winter than in the growing season, but this was explained by the higher loading rates, rather than lower removal efficiency. The relatively poor-quality wetland effluent was further polished during winter in the pond. The upper layer of the pond water column became remarkably clear immediately after ice melt. In the growing season, ponds could be operated as a continuous flow system to remove nutrients and pathogens, and the effluent of pond could be reused as a supplemental irrigation water without risk of infection by sewage-borne pathogens as well as causing adverse effect on growth and yield. Overall, the wetland system was found to be adequate for treating sewage with stable removal efficiency, and the intermittent-discharge pond was found to be effective for further polishing if necessary. Therefore, the combination of a wetland and subsequent pond system and reuse of effluent as crop irrigation water is recommended as a practical alternative to treat sewage in Korean small communities, and partial discharge of pond water in March is suggested.

• Korean journal of food and cookery science
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• v.31 no.5
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• pp.581-587
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• 2015

This study was conducted to investigate the antioxidative and antimicrobial activities of Korean dandelion (Taraxacum coreanum). Water extracts, ethanol extracts and methanol extracts were used to examine the free radical scavenging activity, total flavonoid content, total polyphenol content and antimicrobial activity. The free radical scavenging activity, total flavonoid, total polyphenol and total antioxidant activity of the water extracts were higher than those of the other extraction solvents. The antimicrobial activties of Korean dandelion extracts were examined on several food borne illness microorganisms using the paper disc diffusion method. Inhibition zones were observed on Staphylococcus aureus subsp. aureus, Listeria monocytogenes, Bacillus subtilis, Bacillus cereus and Escherichia coli in ethanol extracts. Inhibition zones were also observed on Listeria monocytogenes in water extracts. The physico-chemical properties of Korean dandelion tea according to the roasting time and soaking amount of tea were studied. The pH of the dandelion tea significantly decreased while the soluble solid contents significantly increased with increased roasting time (p<0.01). The lightness of the dandelion tea decreased and the turbidity increased with increased roasting time. In sensory evaluation, the sensory scores for the color, flavor and total acceptability were highest in the 40 min roasted tea. These results suggest that the water extract of Korean dandelion could be used as an antioxidative and antimicrobial functional food source. The optimum roasting time for Korean dandelion tea was 40 min at $200^{\circ}C$.