• Journal of dental hygiene science
• /
• v.17 no.4
• /
• pp.283-289
• /
• 2017

The water discharged from dental unit waterlines (DUWLs) is heavily contaminated with bacteria. The development of efficient disinfectants is required to maintain good quality DUWL water. The purpose of this study was to establish a DUWL biofilm model using well-plates to confirm the effectiveness of disinfectants in the laboratory. Bacteria were obtained from the water discharged from DUWLs and incubated in R2A liquid medium for 10 days. The bacterial solution cultured for 10 days was made into stock and these stocks were incubated in R2A broth and batch mode for 5 days. Batch-cultured bacterial culture solution and polyurethane tubing sections were incubated in 12-well plates for 4 days. Biofilm accumulation was confirmed through plating on R2A solid medium. In addition, the thickness of the biofilm and the shape and distribution of the constituent bacteria were confirmed using confocal laser microscopy and scanning electron microscopy. The average accumulation of the cultured biofilm over 4 days amounted to $1.15{\times}10^7CFU/cm^2$. The biofilm was widely distributed on the inner surface of the polyurethane tubing and consisted of cocci, short-length rods and medium-length rods. The biofilm thickness ranged from $2{\mu}m$ to $7{\mu}m$. The DUWL biofilm model produced in this study can be used to develop disinfectants and study DUWL biofilm-forming bacteria.

• Journal of Wetlands Research
• /
• v.9 no.3
• /
• pp.35-42
• /
• 2007

The paved areas such as parking lots and roads are stormwater intensive landuses since they are impervious and have high pollutant mass emissions from vehicular activity. Vehicle emissions include different pollutants such as heavy metals, oil and grease, particulates from sources such as fuels, brake pad wear and tire wear. Especially, the released heavy metals can be easily absorbed on the surface area of small particulate materials because of its ionic strength. Therefore, by constructing the sedimental tank in structural BMPs as a pre-treatment facility, the particles and heavy metals both can be removed from the runoff at an instant. To understand the physico-chemical characteristics of sediments from sedimentation tank, one-year study at an infiltration trench and filtration system was conducted to quantify the metal mass absorbed on sediments with various particle sizes. The structural BMPs for this study are located in Yongin City, Kyunggido. The research results show that Cu, Zn and Pb are dominant metal compounds in the sediments. Also the metal concentrations are highest at the ranges of $425-850{\mu}m$ particle sizes. The results will provide the basic physico-chemical information of sediments to treat it as solid wastes and to determine the design criteria of sedimentation tank in structural BMPs.

• Journal of the Korean Society of Radiology
• /
• v.14 no.2
• /
• pp.85-95
• /
• 2020

The filtration characteristics of H₂O-C₆H₁₂O₆ solution at cell membrane model in renal tubule which irradiated by high energy x-ray(linac 6MV) was investigated. The cell membrane model used in this experiment was a polysulfonated copolymerized membrane of m-phenylene-diamine(MPD) and trimesoyl chloride(TMC)-hexane. They were used to two cell membrane models(CM-1, CM-2). The cell membrane model composed of 0.5 wt% TMC-hexane solution(CM-2) had higher permeate flux(Jv) and rejection coefficient(R) than composed of 0.1 wt% TMC-hexane solution(CM-1). The permeate flux(Jv) and rejection coefficient(R) of H₂O-C₆H₁₂O₆ solution in two cell membrane models(CM-1, CM-2) were increased with increase of pressure drop and effective pressure difference. In this experiment range(pressure 1.5-4 MPa, temperature 36.5 ℃), permeate flux(Jv) of H₂O solvent in irradiated membrane was found to be decreased about 20-30 times than non-irradiated membrane, permeate flux(Jv) and rejection coefficient(R) of H₂O-C₆H₁₂O₆ solution in irradiated membrane was found to be decreased about 2-13 times, about 4-6 times than non-irradiated membrane, respectively. The concentration increase of H₂O-C₆H₁₂O₆ solution at cell membrane model significantly was increased at rejection coefficient(R), was decreased at permeate flux(Jv). As the filtration of H₂O-C₆H₁₂O₆ solution in cell membrane model were abnormal, cell damages were appeared at cell.

• Korean Chemical Engineering Research
• /
• v.59 no.4
• /
• pp.548-556
• /
• 2021

This study was conducted to investigate the applicability of lignocellulosic fiber and coconut shell activated carbon (CSA) for the production of a particulate matter (PM)-reducing air-filter as raw materials to solve the environmental problems of non-woven fabrics. CSA had a good potential to use as a raw material of air-filter for reducing volatile organic compounds as well as noxious metals, and reduction capability of the CSA was 5 times higher than that of wood fiber. Natural adhesives formulated with proteinaceous wastes mostly were applied successfully to fabricate air-filters with the shape of fiberboard. The air-filter fabricated with the minimum target density of 200 kg/m³ and the maximum CSA-content of 40 wt% in fiberboard had a good manageable strength. However, the fiberboard filters was required to make vent-holes for improving an air-permeability of the filters. Size of the CSA particles was adjusted to greater than 2 mesh with the consideration of strength and formability of the fiberboard. Three-layers fiberboard that only wood fiber and the mixture of wood fiber and CSA were formed in the surface and middle layers, respectively, was determined to the optimal condition for the production of air-filters. In addition, traditional Korean paper handmade from mulberry trees (TKP) showed a good PM-reducing property as an air-filter. It is concluded that air-filtering set composed of fiberboard with vent-holes and TKP instead of conventional air-filters made with non-woven fabrics can be used as a filter for reducing the concentrations of PM, VOC and noxious metals existed in indoor and outdoor spaces.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.24 no.1
• /
• pp.128-138
• /
• 2019

Effects of feeding type and food resource availability on community structure of mollusks inhabiting hard-bottom subtidal areas were investigated. By following guidance from several references, mollusks observed in this study were divided into 5 groups according to feeding type - 1) grazing, 2) filter feeding, 3) deposit feeding, 4) omnivorous and 5) predation. The results showed that both grazing and filter feeders were the most numerous, explaining grazing type in the East Sea accounting for 47.9%, 32.6% in the South Sea and 29.6% for filter feeding, and filter feeding as a dominant feeding type in Yellow Sea accounting for 42.3%. Results of this study showed distinctive difference in community structure depending on mechanism of feeding type and geographical areas where sampling took place. With the results, attempts were made to understand whether community structure could be affected by feeding type or feeding availability and found out that community structure depended heavily on food resource availability. In the East Sea where marine algal density was high, the algal community in the forms of thick-leathery and sheet often occurred in water column with high transparency which provides proper environment for growth. In the South Sea where grazing and filter feeding types were predominated similarly, the algal density was high, but had the relative highest phytoplankton density. Whereas in the Yellow Sea showing the lowest algal biomass compared to the one in the East and the South Sea, and phytoplankton density was similar to those. It might be a adequate environment for filter feeders than grazers. This study concluded that community structure of mollusks showing high abundance was present where food resource availability with types and quantity was high.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2004.05b
• /
• pp.878-882
• /
• 2004

지하수를 이용한 물 문제 해결 방법은 여러 수공학자들에 의해 연구되어 왔고 많은 성과를 이루었다. 하지만, 과도한 지하수 개발은 새로운 공학적 문제를 야기하게 되어 각 수자원에 내한 개별적인 분석 단계를 지나 여러 수자원을 연계하여 이용할 수 있는 기법들이 연구되고 있다. 이 방법 중 하나로 지표수와 지하수를 연계 이용하는 방법이 연구되었고, 개발 대상 지역에 대한 우선순위 결정을 위해 계층분석과정(Analytic Hierarchy Process, AHP)이 적용되었다. 이리한 적지 분석을 위한 시스템(SASCU)을 GIS와 연계하여 개발함으로써 개랄 가능 후보지에 대한 개발 우선순위 결정에 도움이 괼될것으로 사료된다.

• Tuberculosis and Respiratory Diseases
• /
• v.58 no.2
• /
• pp.167-173
• /
• 2005

Background : Airborne particles during Yellow Sand phenomena are known to be associated with the respiratory disease. The purpose of this study was to evaluate the concentration and metal component properties of Yellow Sand particles and compare with airborne microbial concentration and species in non Yellow Sand and Yellow Sand phenomena. Methods : Samplings were carried out in 2002 in Seosan, during non Yellow Sand and Yellow Sand phenomena. Samples were taken using the 8-stage Cascade impactor and metallic elements were analyzed by XRF. Those were culture on the media for bacterial and fungal culture and celline for virus. Results : The concentration of total suspended particulate matter were respectively $80.2{\mu}g/m^3$, $40.3{\mu}g/m^3$ in non Yellow Sand and Yellow Sand phenomena. The concentration of metallic elements such as Ca, Fe, Cu and Zn in Yellow Sand phenomena were higher than its in non Yellow Sand. Two bacteria, Bacillus species and Staphylococcus were grown in two periods. In both periods, several fungal spores(Mucor species, Cladosporum, Alternaria, Aspergillus, Penicillium, and Alternaria species) were identified. The differences of bacteria and fungus species not observed in Yellow Sand and non Yellow Sand. Any viruses were not isolated in between both periods. Conclusions : The concentration of total suspended particulate matter and some metallic elements in Yellow Sand phenomena were higher than its in non Yellow Sand. The difference of bacteria and fungus species was not observed in non Yellow Sand and Yellow Sand phenomena.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.11
• /
• pp.5311-5316
• /
• 2012

Single Photon Emission Computed tomography(SPECT) was performed on 13 healthy adults (average age: 39) to investigate the changes of cerebral blood flow according to brain imaging analysis algorithm. The acquired images were filtered and reconstructed through Filtered Back Projection (FBP) and Ordered Subset Expectation Maximization (OSEM). The brain distribution data of radiopharmaceuticals were compared using Statistical Parametric Mapping (SPM), and the changes of blood flow was expressed in Cluster. As a result, uptake rate was increased in Sub-gyral, Sub-Lobar, Extra-Nuclear, Limbic lobe and Cingulate Gyrus, while uptake rate was decreased in Middle frontal gyrus, Inferior Frontal Gyrus and Precentral Gyrus. The discriminable SPM was shown according to cerebral blood flows in Cluster by the reconstruction algorithm.

• Applied Biological Chemistry
• /
• v.33 no.3
• /
• pp.203-208
• /
• 1990

The physical characteristics of texture, water holding capacity, color and swelling of soybean curd were studied for 14 varieties of soybeans grown in Korea. The relative water holding capacity, measured by moisture absorption method with using filter paper, was high for Millyang-21. Danyeob and Hwangum, low for Suwon-138, -141 and -142. All of the soybean curd prepared showed negative Sag values, which indicates swelling properties of Tofu as it as released from pressed condition. The most swollen variety was Suwon-138 and the least one was Suwon-142. Generally, soybean curd having high moisture content had low valuss in hardness but no significant relationship was found. Elasticity ud cohesiveness showed a little differences except Suwon-138. Other textural characteristics of fracturability, adhesiveness and gumminess showed a wide range in their values among the varieties.

• Analytical Science and Technology
• /
• v.25 no.6
• /
• pp.410-415
• /
• 2012

In this study, a fundamental study was conducted to establish the method for quantitative analysis and pretreatment of triclosan, one of the chemicals to be used as bactericides, detergents, and sterilizers. The extraction efficiency of triclosan was the highest when it was extracted by soxhlet apparatus with n-hexane, and it showed a satisfactory result when the samples were analyzed with both GC/ECD and GC/MS. To evaluate the reproductivity of the results, each 30 reference samples made with paper filter and cotton wool was prepared in this study. From the results with high extraction effectiveness, low analysis deviation, and good statistical analysis data, the method for the extraction and analysis for triclosan were resonable for the paper and textile samples applied in this study.