• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.26 no.2
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• pp.225-236
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• 2016

Objectives: Nanomaterials have been used in various fields. As use of nanoproducts is increasing, workers dealing with nanomaterials are also gradually increasing. Exposure assessments for nanomaterials have been carried out for protection of worker's health in workplace. Exposure studies were mainly focused on manufacturing processes, but these studies on after-treatment processes such as refinement, weighing, and packing were insufficient. So, we investigated exposure characteristics of particles during after-treatment processes of $Al_2O_3$ fibers and Ni powders. Methods: Mass-production of Ni powder process was carried out in enclosed capture-type canopy hood. In a developing stage, $Al_2O_3$ was handled with a local ventilation unit. Exposure characteristics of particles were investigated for $Al_2O_3$ fiber and Ni powder processes during the periods of 10:00 to 16:00, 20 May 2014 and 13:00 to 16:00, 21 May 2014, respectively. Three real-time aerosol instruments were utilized in exposure assessment. A scanning mobility particle sizer(SMPS, nanoscan, model 3910, TSI) and an optical particle counter(OPC, portable aerosol spectrometer, model 1.109, Grimm) were used to determine the particle size distribution in the size range of 10-420 nm and $0.25-32{\mu}m$, respectively. In addition, a nanoparticle aerosol monitor(NAM, model 9000, TSI) was used to measure lung-deposited nanoparticle surface area. Membrane filters(isopore membrane filter, pore size of 100 nm) were also used for air sampling for the FE-SEM(model S-5000H, Hitachi) analysis using a personal sampling pump(model GilAir Plus by 2.5 L/min, Gilian). Conclusions: For Ni powder after-treatment process, only 27% increase in particle concentration was found during the process. However, for $Al_2O_3$ fiber after-treatment process, significant exposure(1.56-3.34 times) was observed during the process.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.8
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• pp.755-760
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• 2010

In this study, we mainly focused on the PM (Particulate Matter) emission characteristics of a diesel engine. To analyze particle behavior in the tail-pipe, particle emission was measured on the engine-out (downstream of turbocharger), each upstream and downstream both of DOC (Diesel Oxidation Catalyst) and DPF (Diesel Particulate Filter). Moreover, particle emission contours on each sampling point were constructed. The reduction efficiency of particle number concentration and mass through the DOC and DPF was studied. Parameters such as EGR (Exhaust Gas Recirculation) and the main injection timing were varied in part load conditions and evaluated using the engine-out emissions. The DMS500 (Differential Mobility Spectrometer) was used as a particle measurement instrument that can measure particle concentrations from 5 nm to 1000 nm. Nano-particles of sizes less than 30 nm were reduced by oxidation or coagulated with solid particles in the tail-pipe and DOC. The DPF has a very high filtration efficiency over all operating conditions except during natural regeneration of DPF.

• Korean Journal of Veterinary Service
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• v.17 no.2
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• pp.95-113
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• 1994

To establish an effective diagnostic measure for detection of the antibodies against Actinobacillus pleuropneumoniae, the methods for tube agglutination test (TAT), plate agglutination test (PAT), micro-agglutination test(MAT) and agar-gel immunodiffusion test(ID) were improved and standarized, and the comparative studies were carried out. The results obtained through the experiments were summarized as follows. 1. The rabbit hyperimmune sera to reference serotypes 1 to 6 were cross-tested with TAT, PAT, MAT and ID. In the homologous systems, the range of antibody titers in TAT was 80 to 640, showing the cross-reaction in serotypes 3, 4, 5 and 6. The range of antibody titers in PAT was 4 to 64, showing the cross-reaction in serotypes 3, 4, 5 and 6. In ID, the range of antigen titers was 8 to 32, and cross-reaction was observed in serotype 5. 2. The optimal concentration of antigen in PAT and MAT were 100mg /ml and 1.25mg /ml respectively. The most sensitive reaction in MAT was observed in 52$^{\circ}C$ for 18hrs. 3. In ID, the most promising antigen and the buffer for agar-gel were EDTA-treated antigen and 0.05M tris buffer (pH 7.2), respectively. 4. By the tests for 200 swine sera, it was found that the frequency of positive reaction were 203 in TAT, 240 in PAT and 163 in ID. 5. When compared the titers of TAT with those of MAT for 200 swine sera, MAT showed the higher titer than TAT being increased by relative correlation. Int was found that the titer for positive readings were 20 in TAT and 40 in MAT. 6. when compared the results of ID with those of TAT for 200 swine sera, all sera with TAT titer under 10 were negative in ID. Of the sera with TAT titer 20 and 40, 55.1% nd 91.8% were positive in ID, respectively. All sera with TAT titer above 80 were positive in ID. In comparison of ID and MAT, all sera with MAT titer under 20 were negative in ID. Of the sera with MAT titer 40 and 80, 24.7% and 93.9% were positive in ID, respectively. All sera with MAT titer over 160 showed positive in ID. 7. In conclusion, the established MAT showed high sensitivity but low specificity, wherease ID revealed low sensitivity but high specificity.

• Journal of Animal Environmental Science
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• v.21 no.2
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• pp.41-46
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• 2015

The objective of this study is to measure the levels of ammonia and hydrogen sulfide in livestock manure composting facility according to seasonal condition. Mean concentrations of ammonia in livestock manure composting facility were 84.3 (${\pm}15.2$) ppm for spring, 115.2 (${\pm}34.7$) ppm for summer, 76.2 (${\pm}18.9$) ppm for autumn, and 38.1 (${\pm}10.4$) ppm for winter, respectively. Based on the results obtained from this study, the seasonal levels of ammonia in livestock manure composting facility were highest in summer followed by autumn, spring and winterroom (p<0.05). Mean concentrations of hydrogen sulfide in livestock manure composting facility were 7.46 (${\pm}2.24$) ppm for spring, 9.42 (${\pm}2.82$) ppm for summer, 8.15 (${\pm}3.06$) ppm for autumn, and 10.18 (${\pm}4.11$) ppm for winter, respectively. The livestock manure composting facility showed the highest levels of hydrogen sulfide in winter followed by summer, autumn and spring. However, there was no significant difference of hydrogen sulfide concentration among seasons (p>0.05).

• Fire Science and Engineering
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• v.30 no.4
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• pp.103-110
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• 2016

While the demand for the gas system fire extinguishers increases every year, there are insufficient safety measures for assessing the extinguishing performance, such as system safety and reliability in the preparation of increasing demand, which has emerged as a social problem. One of the most critical causes of accidents occurring with the gas extinguishing system is pressure leakage from the extinguishing agent storage container. This is considered to be one of the critical factors on which the success of fire suppression depends. In this study, its safety measure was studied, Because it was deemed urgently necessary. The newly developed pressure leakage monitoring system is a system monitoring storage condition, pressure, leakage and discharge of the storage container related to agent concentration, which is one of the critical factors for fire suppression. This was developed to be applicable to the $CO_2$ and HFC-23 systems. Therefore, for structural safety analysis, the safety performance was verified by the fluid structure coupling analysis of the safety problems that may occur when the pressure leakage monitoring system is applied to the gas fire extinguisher. For analysis programs, the FloEFD program from Mentor Graphics was used for computational fluid dynamics analysis and ABAQUS from Dassault Systems was used for structural analysis. From the result of numerical analysis, the structure of $CO_2$ did not develop plastic deformation and its safety was verified. However, plastic deformation and deviation issue occurred with the HFC-23 monitoring system and therefore verified the structural safety of pressure leakage monitoring system by data obtained from redesigning and adjusting the condition of numerical interpretation three times.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2009.06a
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• pp.84-85
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• 2009

New approaches for detecting, preventing and remedying environmental damage are important for protection of the environment. Procedures must be developed and implemented to reduce the amount of waste produced in chemical processes, to detect the presence and/or concentration of contaminants and decontaminate fouled environments. Contamination can be classified into three general types: airborne, surface and structural. The most dangerous type is airborne contamination, because of the opportunity for inhalation and ingestion. The second most dangerous type is surface contamination. Surface contamination can be transferred to workers by casual contact and if disturbed can easily be made airborne. The decontamination of the surface in the nuclear facilities has been widely studied with particular emphasis on small and large surfaces. The amount of wastes being produced during decommissioning of nuclear facilities is much higher than the total wastes cumulated during operation. And, the process of decommissioning has a strong possibility of personal's exposure and emission to environment of the radioactive contaminants, requiring through monitoring and estimation of radiation and radioactivity. So, it is important to monitor the radioactive contamination level of the nuclear facilities for the determination of the decontamination method, the establishment of the decommissioning planning, and the worker's safety. But it is very difficult to measure the surface contamination of the floor and wall in the highly contaminated facilities. In this study, the poly(styrene-ethyl acrylate) [poly(St-EA)] core-shell composite polymer for measurement of the radioactive contamination was synthesized by the method of emulsion polymerization. The morphology of the poly(St-EA) composite emulsion particle was core-shell structure, with polystyrene (PS)as the core and poly(ethyl acrylate) (PEA) as the shell. Core-shell polymers of styrene (St)/ethyl acrylate (EA) pair were prepared by sequential emulsion polymerization in the presence of sodium dodecyl sulfate (SOS) as an emulsifier using ammonium persulfate (APS) as an initiator. The polymer was made by impregnating organic scintillators, 2,5-diphenyloxazole (PPO) and 1,4-bis[5-phenyl-2-oxazol]benzene (POPOP). Related tests and analysis confirmed the success in synthesis of composite polymer. The products are characterized by IT-IR spectroscopy, TGA that were used, respectively, to show the structure, the thermal stability of the prepared polymer. Two-phase particles with a core-shell structure were obtained in experiments where the estimated glass transition temperature and the morphologies of emulsion particles. Radiation pollution level the detection about under using examined the beta rays. The morphology of the poly(St-EA) composite polymer synthesized by the method of emulsion polymerization was a core-shell structure, as shown in Fig. 1. Core-shell materials consist of a core structural domain covered by a shell domain. Clearly, the entire surface of PS core was covered by PEA. The inner region was a PS core and the outer region was a PEA shell. The particle size distribution showed similar in the range 350-360 nm.

• Journal of the Korean Society of Radiology
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• v.6 no.6
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• pp.507-513
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• 2012

This research was performed to evaluate the superparamagnetic iron oxide nanoparticles'(SPIONs) cell toxicity and to measure the radiation cell survival curve changes of SPIONs-uptake glioblastoma multiforme cells. The results could be practically used as the fundamental data to ameliorate proton beam cancer therapy, for example, providing necessary GBM treatment dose in the proton beam therapy when the therapy takes advantage of SPIONs. The assessment of the toxicological evaluation of synthesized SPIONs was accomplished by MTT assay as an in vitro experiment. The results showed no meaningful differences in the cell survival rate at the $1-100{\mu}g/ml$ SPIONs concentrations, but the cell toxicity was shown as the cell survival rate decreased up to 74.2% at the $200{\mu}g/ml$ SPIONs concentration. Then, we measured each radiation cell survival curve for U373MG cells and SPIONs-uptake U373MG cells with 0~5 Gy of proton beam irradiations. It is learned from the analysis of the experimental results that the SPION-uptake cells' radiation survival rate was more rapidly decreased as the irradiation dose increased. In conclusion we confirmed that SPIONs-uptake in U373MG cells induces cell death at the much less dose than the lethal dose of SPION-non-uptake cell. This research shows that the therapeutic efficacy of glioblastoma multiforme treatment in proton beam therapy can be improved by SPIONs targeting to the GBM cells.

• Journal of Applied Biological Chemistry
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• v.62 no.4
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• pp.391-398
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• 2019

The antioxidant, whitening, and anti-wrinkle activity of Spirodela polyrhiza extracts and fractions were evaluated to determine its efficacy as a functional cosmetic material. 1,1-diphenyl-2-picrylhydrazyl and 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid radical scavenging activities were 44.2 and 74.3%, respectively, at 100 ㎍/mL of SE-E (the ethyl acetate fraction of 70% ethanol extract). To measure anti-wrinkle effects, procollagen biosynthesis and matrix metalloproteinase-1 (MMP-1) inhibition activity were determined. At 25 ㎍/mL of SE (70% ethanol extract), the biosynthesis activity was 48.5%, and SE-E showed the best activity (57.8%) at the same concentration. MMP-1 inhibition activity of SE and SE-E was 13.4 and 28.5%, respectively, at 25 ig/mL. Finally, the inhibition of cellular melanin synthesis and cellular tyrosinase were measured to determine the whitening effect; at 25 ㎍/mL, the inhibition activities of SE were 9.6 and 13.8%, respectively, and those for SE-E were 15.4 and 22.0%, respectively. Our results confirmed the possibility of SE and SE-E as effective functional materials. Further research investigating the antimicrobial, anti-inflammatory, and anticancer activities of S. polyrhiza is necessary to confirm its potential use in the food, cosmetics, and drug industries.

• Analytical Science and Technology
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• v.17 no.3
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• pp.251-262
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• 2004

It is for the purpose of investigating the tritium distribution in the leachates, the raw and treated leachates and the condensates of the methane gas, which have occurred from domestic solid waste landfills. Also it aims to measure the tritium distribution level on the colloid size of the leachates, the raw and treated leachates. It was found that the major inorganic contaminants of the leachates were Na, K, Ca, Mg, $NH{_4}^+$-N and $Cl^-$. The mean tritium level of the raw leachates of the investigated 13 landfill sites for 6 months was 17 ~ 1196 TU. It corresponded to a several scores or hundreds of magnitude higher value than that of the normal environmental sample level except for two landfill sites. Also such a high concentration of the tritium was found in the treated leachates and methane gas condensates as well. Nevertheless it is important to emphasize that the tritium level which was found in this research is about 100 times lower than the tritium limit for the drinking water quality. And most of the tritium existed in the dissolved colloid of the leachate of which the colloid size is below $0.45{\mu}m$. Also, according to the tritium analysis results of the leachates after filtration with $0.45{\mu}m$ membrane filter for some landfills, it is likely that some tritium of the leachate would be distributed in a colloid size over $0.45{\mu}m$. In general the relationship between the tritium and other contaminants in the raw leachate was low, but it was relatively high between the tritium and TOC. However, the tritium content in the leachate had no meaningful relationship with the scale, hydrological characteristics and age of the landfill.

• The Korean Journal of Pain
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• v.12 no.1
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• pp.36-42
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• 1999

Background: The current maximal recommended doses of lidocaine are 7 mg/kg with $5\;{\mu}g/ml$ of epinephrine. But in clinical practice, sometimes more doses of lidocaine are required to produce adequate regional anesthesia. Method: Twenty-two healthy women patients were divided into two groups and pretreated with valium 5 mg p.o., morphine 5 mg i.m., and midazolam 2 mg i.v. before operation. Of these, 7 mg/kg of 2% lidocaine with $5\;{\mu}g/ml$ of epinephrine were given to 11 patients epidurally. Initial 3 ml of epinephrine mixed lidocaine was given as a test dose and remaining doses were given 5 ml/30 sec with 3 min intervals. Radial arterial blood were drawn at 5, 10, 15, 20, 30, 45, 60, 90, 120 min to measure plasma lidocaine concentrations. After confirming all of the peak plasma concentrations of 7 mg/kg lidocaine were absolutely under $5\;{\mu}g/ml$, the other 11 patients were given 10 mg/kg of 2% lidocaine with $5\;{\mu}g/ml$ of epinephrine epidurally and blood samplings were taken according to the same method of 7 mg/kg group. The peak plasma concentration ($C_{max}$), time to reach to $C_{max}$ ($T_{max}$), time to reach to $T_4$, maximal sensory block level, systemic toxicity, and vital sign changes were investigated. Result: $C_{max}$ was significantly higher in 10 mg/kg group ($5.1{\pm}1.3\;{\mu}g/ml$) than 7 mg/kg group($3.3{\pm}0.5\;{\mu}g/ml$), but $T_{max}$ ($10.5{\pm}2.7$ min vs $10.9{\pm}3.1$ min) was not different. Time to reach $T_4$ was significantly shorter in 10 mg/kg group ($9.5{\pm}2.7$ min) than 7 mg/kg group ($12.7{\pm}3.2$ min) but maximal sensory block level ($T_{3.7{\pm}0.7}$ vs $T_{2.7{\pm}1.0}$) was not different. In four patients of 10 mg/kg group, peak plasma concentrations exceeded $5\;{\mu}g/ml$, but no systemic toxicities appeared. No significant vital sign changes were observed. Conclusion: The current maximal recommended doses of lidocaine, merely based on body weight are not always appropriate. Further studies are needed to determine more precise guideline of maximal doses that include various pharmacokinetic components.