• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2006.10a
• /
• pp.477-478
• /
• 2006

• 한국정보디스플레이학회:학술대회논문집
• /
• 2009.10a
• /
• pp.1596-1599
• /
• 2009

Mobile ODF (one drop filling) portable display such as mobile phone and application product is needed high reliability than notebook, monitor and TV. Therefore, material development in order to optimize mobile & application ODF panel is needed. Through considering mobile ODF process and design, we have developed method of material matching test by several tests which is heat stress, UV stress and ODF process condition. So we have developed a material with characteristics of high reliability for mobile ODF panel.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2005.06a
• /
• pp.21-29
• /
• 2005

The HANARO, a multi-purpose research reactor of 30 MWth open-tank-in-pool type, has been under normal operation since its initial criticality in February, 1995. Recently, ten years after the initial operation of the HANARO, one of the two primary cooling pumps was decontaminated for overhaul maintenance in 2004. Before decontamination exposure doserate and surface contamination level of primary cooling pump measured at 4 points. After final decontamination exposure doserate and surface contamination level of primary cooling pump remeasured by same method done before. It is easy to decontaminate the out side exposed surfaces of the pump, but it is difficult to approach the inside surface due to double volute installed in the casing. Therefore, a new decontamination facility has been developed to solve this problem. A concentrated de-contaminant (DX-300) is rotated in the closed pump casing by the impeller actuated by a temporary motor. Nuclide particles are removed by the emulsification effect of the de-contaminant and the surface contaminants are chemically removed from the pump by the corrosion and dissolution effect. The inside surfaces of the primary cooling pump have been decontaminated by using the facility. As results, the contamination level of the inside surfaces was maintained below the surface contamination limit.

• Journal of Radiation Protection and Research
• /
• v.25 no.1
• /
• pp.21-30
• /
• 2000

For analyzing the direct contamination pathway of radionudides in rice plants, a Solution containing $^{54}Mn,\;^{57}Co,\;^{85}Sr,\;^{103}Ru$ and $^{134}Cs$ was applied to the aboveground Parts of the between RI application and harvest. Its highest observed value was 0.94. The fractions of the initial plant deposition that remained in rice plants at harvest were in the range of $19{\sim}47%,\;17{\sim}43%,\;19{\sim}42%,\;23{\sim}61%$ and $11{\sim}69%$ for $^{54}Mn,\;^{57}Co,\;^{85}Sr,\;^{103}Ru$ and $^{134}Cs$, respectively, when no decay was assumed. The translocation factors of those radionuclides in hulled seeds were in the range of $6.9{\times}10^{-4}3.8{\times}10^{-2},\;3.6{\times}10^{-3}{\sim}1.6{\times}10^{-1},\;5.8{\times}10^{-4}{\sim}3.2{\sim}10^{-2},\;1.6{\times}10^{-4}{\sim}7.6{\times}10^{-3}$ and $3.2{\times}10^{-2}{\sim}2.0{\times}10^{-1}$, respertively, and were highest when they were applied at the stage of active seed development. It was indicated that the remaining percentage and translocation factor would not be greatly affected by the difference in the rain frequency if it is within a factor of 2. These results can be utilzed for predicting the radionuclide concentrations in rice seeds when an accidental deposition of those radionuclides occurs during the rice-growing season.

• Journal of the Korea Concrete Institute
• /
• v.14 no.3
• /
• pp.420-429
• /
• 2002

The amount of $CO_2$-silicate bonded waste foundry sand(WFS) occurred in Korea is over 800,000 ton per year. WFS, as a by-product, is generated through manufacturing process of foundry may affect our environmental contamination, The reason is that WFS has been buried itself not less than 90％ out of total WFS. So, it can give damage on the ground of contamination in soil and underwater. Therefore, it is necessary to establish the method recycling WFS because of being intensified waste management law. In this study, we performed the research with respect to harmful component analysis, the qualities of WFS mortar and concrete mixed with WFS. As the results the specific gravity of WFS is the same as that of natural aggregate while unit weight and percentage of solids of WFS are smaller than those of it. But it is found that WFS can be used by substituting WFS for natural aggregate after control of poor grade of WFS. The flowability of mortar and concrete with WFS is inferior to those of natural aggregate, and the setting time of concrete with WFS is faster than that with only natural aggregate, On the contrary, the bleeding of concrete with WFS is shown good result, and compressive and tensile strength of concrete substituted WFS for 30％ are higher than those with only natural aggregate regardless of elapsed time.

• The Journal of Korean Academy of Prosthodontics
• /
• v.36 no.1
• /
• pp.64-80
• /
• 1998

The risk of cross-contamination in dental clinic is very high. Those who are engaged in dental clinic are exposed to various microorganisms in saliva and blood of patient. Potential possibility of cross-contamination of patient to patient, patient to dentist, dentist to laboratory technician always exist, which is important in the view of public health. It is well known that microorganisms may cause cross-contamination by suck-back of microorganisms into the water supply line or air supply line of dental unit and sprayed back into the next patient's oral cavity. The majority of microorganisms coming from dental unit are water microorganisms from the main water supply which have colonized the tube within the units and multiplied in the relatively warm and stagnant conditions. The purpose of this study is to measure the extent of microbial contamination of dental unit and ultrasonic scaler, to evaluate that dental unit water supply is suitable for drinking water, and to assess the effect of flushing on reduction of microbial contamination of dental unit and ultrasonic scaler. In the first experiment, water samples(50ml) from 20 dental units and 10 ultrasonic scalers in Seoul National Univ. Hosp. were tested for the presence of coliform. The samples were filtered by membrane filtration technique.(Microfil system, Millipore Co. U. S. A.) The filter was then placed onto MacConkey agar plate and the plates with filter on it were incubated aerobically at $37^{\circ}C$ for 5 days. The colors and shapes of colonies were examined if those were coliform. To verify the presence of coliform, the colonies were inoculated into phenol red lactose broth and incubated aerobically at $37^{\circ}C$ for 2 days. The fomation of gas was observed. In the second experiment, water samples from 20 handpieces, 10 ultrasonic scalers and 30 A/W syringes after 0, 2, 4, 6 min. flushing respectively were taken. $200{\mu}l$ water samples were spreaded on Brain Heart Infusion agar plate and the plates were incubated aerobically at $37^{\circ}C$ for 5 days. The number of colony was counted. The results obtained were summarized as follows 1. The water from dental unit and ultrasonic scaler was not suitable for drinking water. 2. No coliform was founded in dental unit and ultrasonic scaler water supply. 3. The number of colony of dental unit and ultrasonic scaler was highest in the group of o min. flushing(p<0.05). 4. There was no statistically significant difference in the extent of microbial contamination among handpiece, ultrasonic scaler and A/W syringe (p>0.05). 5. The number of colony was lowest in the group of 4 min. flushing, but there was no statistically significant difference among 2, 4, 6 min. flushing groups.(p>0.05) 6. It is recommended to flush dental unit water line for 4 min. after use on each patient.

• Journal of Food Hygiene and Safety
• /
• v.35 no.1
• /
• pp.13-22
• /
• 2020

A total of 244 cereal samples (oat, sorghum, adlay, and proso millet) were collected from fields to examine the contamination of Fusarium mycotoxins in cereals during harvest season in 2017 and 2018. The contamination levels of deoxynivalenol (DON), nivalenol (NIV), and zearalenone (ZEA) were analyzed individually by using the immunoaffinity column clean-up method with ultra performance liquid chromatography, and fumonisins (FUM) were analyzed by using the QuEChERS method with liquid chromatography-mass spectrometry. Highest level of NIV contamination (120.0-3277.0 mg/kg) was observed in oat samples among the analyzed cereals. In the adlay samples, DON contamination was the highest (maximum level 730.0 ㎍/kg). The proso millet samples had a high frequency of detection of NIV and ZEA (61.5% and 57.9%, respectively), but the levels were low (average detection level of NIV, 75.6 ㎍/kg, for ZEA, 21.5 ㎍/kg). Among the cereal samples, sorghum had the highest contamination frequency of DON, ZEA, and FUM, and the co-occurrence of Fusarium mycotoxin was 70.0%, which was higher than the average of 29.9%. In order to safely manage Fusarium mycotoxin levels in cereals, continuous research on the development of contamination prevention technologies together with monitoring of mycotoxin contamination is needed.

• Journal of Soil and Groundwater Environment
• /
• v.10 no.2
• /
• pp.28-34
• /
• 2005

The aim of this article is to assess the application characteristics of the site by remediating oil-contaminated area using DSB (Deep-site Biopile) system. In the contaminated area, the soil was composed of penetrable sand and the leaked oil was spread widely (total 7,201 cubic meters) through 2.5 meter deep underground water flow. DSB system was operated for 30 minutes intervals for 24 hours in a day (30 minutes opεration and 30 minutes stop). To check contamination level change in the contaminated area after DSB system was operated, samples were taken. The result from the site shows that BTEX/TPH contamination level was dropped 50% after 30-day operation of DSB system, and that contamination level was dropped below contamination level check standard after 165 days and the remediation was completed. Unlike traditional biological remediation methods DSB system could efficiently process soil and water which were contaminated by high levels of oil compounds.

• Membrane Journal
• /
• v.27 no.1
• /
• pp.104-107
• /
• 2017

Among many methods in solving the organic contamination in the reverse osmosis operation, caustic soda (NaOH) wash method is efficient and commercially affordable. In continuation of our many organic pollution removal works, this study focused mainly on caustic soda wash with micro-bubble to removal the organic contamination of the spent membrane from reverse osmosis process. First, the membrane was forced the pollute using known organic pollutants such as Humic acid, Bovine serum albumin, Sodium alginate drug. The organic contamination on the membrane was monitored flux. The decontamination of organic contaminants was derived flux variation at individual caustic soda was injected micro-bubble methods and combined method as well. the found results explain removal of organic contaminants effective only by combined caustic soda wash with micro-bubble methods.

• Journal of Soil and Groundwater Environment
• /
• v.27 no.spc
• /
• pp.34-50
• /
• 2022

Principal component analysis (PCA) was conducted using hydrochemical data in four testbeds (A to D) built for the development of site characterization technologies to assess the hydrochemical processes controlling the hydrochemistry in each site. The PCA results indicated the nitrogen loading to deep bedrock aquifers through permeable fractures in Testbed A, the chemical weathering enhanced with the biodegradation of petroleum hydrocarbons in Testbed B, the reductive dechlorination in Testbed C, and the different hydrochemistry depending on the depth to bedrock in Testbed D, consistent with the characteristics of each site. In Testbeds B and D, outliers seemed to affect the PCA result probably due to the small number of samples, whereas the PCA result was still consistent with site characteristics. This study result indicates that the PCA is widely applicable to hydrochemical data for the assessment of major hydrochemical processes in contamination sites, which is useful for site characterization when combined with other site characterization technologies, e.g., geological survey, geophysical investigation, borehole logging. It is suggested that PCA is applied in contaminated sites to interpret hydrochemical data not only for the distribution of contamination levels but also for the assessment of major hydrochemical processes and contamination sources.