• Journal of Korean Society for Atmospheric Environment
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• v.3 no.1
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• pp.27-33
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• 1987

The environment and biological studies of tritium have been carried out in the advanced countries since the mid 1950's. In the case of a potential tritium exposure, the usual procedure is trifium bioassay (as HTO) in human urine in order to determine the amount of tritium deposited in the body called tritium body burden. The maximum permissible body burden(MPBB) of tritium in total body is about $30{\mu}Ci/{\ell}$ for body tissue. In the bioassay, the most common investigation level for detection of tritium in urine is 1/10th of MPBB. For this bioassay project, the first priority is given to obtaining a quench correction curve. This consideration is necessary because of the variability in color of human urine specimens. Quenching effect in this case mainly is caused by the absorption of scintillation light flashes by the urine sample. By the least squares method on the statistical basis, an estimated formula for quench correction curve was determined to be Y = 0.771 + 1.836 ${\tmes}10^{-4}$X, where the efficiency(Y) was ranged from about 12% to 31% in the liquid scientillation counting. In this paper, a brief theory concerning the biological half-life of tritium and the retention formula to apply to systematically distributed tritium are described.

• Journal of electromagnetic engineering and science
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• v.15 no.3
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• pp.142-150
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• 2015

Several reports supported that continuous exposure to 60 Hz magnetic field (MF) induces testicular germ cell apoptosis in vivo. We recently evaluated duration- and dose-dependent effects of continuous exposure to a 60 Hz MF on the testes in mice. BALB/c male mice were exposed to a 60 Hz MF at $100{\mu}T$ for 24 hours a day for 2, 4, 6, or 8 weeks, and at 2, 20 or $200{\mu}T$ for 24 hours a day for 8 weeks. To induce the apoptosis of testicular germ cell in mice, the minimum dose is $20{\mu}T$ at continuous exposure to a 60 Hz MF for 8 weeks, and the minimum duration is 6 weeks at continuous exposure of $100{\mu}T$. Continuous exposure to a 60 Hz MF might affect duration- and dose-dependent biological processes including apoptotic cell death and spermatogenesis in the male reproductive system of mice. The safety guideline of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) indicates that the permissible maximum magnetic flux density for general public exposure is $200{\mu}T$ at 60 Hz EMF (ICNIRP Guidelines, 2010). In the present study, we aimed to examine the expression of pro- and anti-apoptotic genes regulated by the continuous exposure to 60 Hz at $200{\mu}T$ in Sprague-Dawley rats for 20 weeks. The continuous exposure to 60 Hz at $200{\mu}T$ does not affect the body and testicular weight in rats. However, exposure to 60 Hz MF significantly affects testicular germ cell apoptosis and sperm count. Further, the apoptosis-related gene was scrutinized after exposure to 60 Hz at $200{\mu}T$ for 20 weeks. We found that the message level of endonuclease G (EndoG) was greatly increased following the exposure to 60 Hz at $200{\mu}T$ compared with sham control. These data suggested that 60 Hz magnetic field induced testicular germ cell apoptosis through mitochondrial protein Endo G.

• Journal of Environmental Health Sciences
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• v.21 no.1
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• pp.56-67
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• 1995

This study was carried out to observe how composting reaction proceed in the optimum composting condition and to understand the characteristics of final compost, when swine feces was amended with different bulking material. Sawdust, rice straw, and rice hull were selected as bulking materials and each of these was mixed with swine feces to obtain the optimum range of moisture contents and C:N ratio. To grasp the influence of newspaper on cornposting reaction when it flew into the composting site intentionally or accidentally, another composting reaction using newspaper as a bulking material was studied. In this experiment, raw material mixes containing the same amount of organic materials were put into 4 composting reactors and composted in the same environmental condition for 3 weeks from Aug. 1, 1994 to Aug. 22, 1994. The followings are the main results of this study. 1. The maximum temperatures reached at during cornposting reaction were 53.8$\circ$C, 51.9$\circ$C, 52.7$\circ$C, and 52.1$\circ$C in the reactor using sawdust, rice straw, rice hull, and newspaper as a bulking material respectively: Thermophilic temperatures were maintained for 72, 108, 108, and 111 hours in each reactor. Mean temperatures of reactors using sawdust, rice straw, rice hull, or newspaper as a bulking materials were 39.7$\circ$C, 39.5$\circ$C, 41.3$\circ$C, and 40.3$\circ$C, but no significant difference between these mean temperatures was observed(p>0.05). Each composter showed significant difference from room temperature(p<0.01), and the mean difference between them was 9.4$\circ$C. 2. Ash contents of each reactor increased rapidly in order of rice straw, rice hull, newspaper, and sawdust according to the pattern of second order function. This rate of increase seemed to result from structural characteristics of a bulking material. The absolute values of second order coefficient of these regression functions were 0.0199, 0.0159, 0.0157, and 0.0144 in each reactor using rice straw, rice hull, newspaper, or sawdust as a bulking material. 3. C:N ratio decreased as the reaction proceeded. Degree of decrease was in order of rice straw, rice hull, newspaper, and sawdust. This sequence was consistent with the increase rate of ash content. The ratios of initial C:N ratio to final C:N ratio were 0.45, 0.53, 0.64, and 0.75 in each reactor using rice straw, rice hull, newspaper, and sawdust as a bulking material respectively. From this ratios, it was possible to infer that all the composting reactions were completed. 4. Fertilizer content containing in the final compost was 1.61~2.20% of N, and 0.35~0.54% of P in dry weight base. According to the classification standard for compost constituent by Higgins, all composts had the intermediate grade of N, but below the low grade of P excepting the newspaper amended compost(fall into the range of the low grade). 5. Heavy metal contents contained in the composts were analyzed. In case of Cd, the range of 0.58~1.11 $\mu$g/g was observed, and in case of Pb, the range of 24.76~39.53 $\mu$g/g was observed(in wet weight base). These values are below the permissible heavy metal level for compost of foreign countries.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.39 no.6
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• pp.42-48
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• 2002

The design, construction and performance test of a convenient multi-purpose irradiator is described. A multi-purpose irradiator using Cesium-137 has been developed for studies of low dose radiation effects in biology and for calibration of Thermo Luminescent dosimeter(TLD). During the operation, three rods of radioactive material which are 10cm in length revolve 180 degrees and irradiate biological samples, or TLD, and return to their shielded position, after the programmed time. A programmable Logic Controller(PLC) controls the sequence of operation, interlock, motor rotation and safety system. The rotation speed of biological samples can vary up to 20 RPM. A real time monitoring system was also incorporated to check and control the operation status of the irradiator. The capacity of the irradiation chamber was 4.5 liters. The isodose distribution at arbitrary vertical planes was measured by using film dosimetry. The dose-rate was 0.13 cGy/min in air and 0.11 cGy/min in water equivalent material in the case of Cesium-137. Range of activity was 2 Ci. The homogeneity of dose distribution in the chamber was ${\pm}$7%. The actual radiation level on the surface was within permissible levels. The irradiator had a maximum 0.35 mR/min radiation leakage on its surface.

• Applied Biological Chemistry
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• v.22 no.4
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• pp.221-226
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• 1979

The soils and plants were sampled from 26 sites of Deogpyeongri, Goisangun, which had been found to be one of the uranium deposit areas. Uranium levels of the samples were determined and the amount of uranium intake by the residents through the food-chains was estimated. The average uranium concentration of Deogpyeongri soils was 15.5ppm with a range of from 4.9 to 43.6ppm showing rather higher values than those of control area, Yangjugun and Icheongun, Gyeonggi-do. The average uranium content of the plant samples from Deogpyeongri was 0.69ppm, about twice the uranium concentration of the control samples. The daily intake of uranium by an adult lived on the agricultural food stuffs produced in Deogpyeongri, was estimated to be about $247{\mu}g$, eqivalent to $0.83{\times}10^{-4}{\mu}Ci$, which is much higher activity compared to the daily intake of uranium by New York citizen, $1.3{\mu}g$. However the calculated uranium level accumulated in the human body of Deogpyeong area was $2.03{\times}10^{-4}{\mu}Ci$ which is still lower than $0.2{\mu}Ci$, the maximum permissible burden in total body recommended by the ICRP.

• Journal of Radiation Protection and Research
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• v.23 no.2
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• pp.109-114
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• 1998

Radiological safety for the conventional operation of Demonstration-Scale Incineration Plant (DSIP) was assessed on the basis of the results of trial burns using the simulated and real radioactive wastes. Radiation dose assessments for routine releases on an annual basis as well a several severe accidental releases on a short-term basis (2h) revealed that there would be no significant environmental impact when low-level waste Is incinerated in DSIP. For semivolatile radioactive cesium species, expected emission concentrations slightly exceeded 10% of maximum permissible concentration. Removal characteristics of the bag filter for condensed-phase cesium species was investigated by the trial burns of simulated waste with inactive cesium tracer. In the off-gas before passing through bag filter, distributions of condensed cesium species in the transition size ranging between the diffusional and inertial region are less than 5%. The overall collection efficiency of the bag filter for cesium species was higher than 99.9%, showing enough decontamination capability as a primary filter for the low-temperature dry off-gas system in radwaste incineration plant.

• Journal of the Korean GEO-environmental Society
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• v.12 no.1
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• pp.13-26
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• 2011

Because the allowable current loading of buried electrical transmission cables is frequently limited by the maximum permissible temperature of the cable or of the surrounding ground, there is a need for cable backfill materials to be maintained at a low thermal resistivity during the service period. Temperatures greater than $50^{\circ}C$ to $60^{\circ}C$ may lead to breakdown of cable insulation and thermal runaway if the surrounding backfill material is unable to dissipate the heat as rapidly as it is generated. This paper describes the results of studies aimed at the development of backfill material to reduce the thermal resistivity. A large number of different additive materials were tested to determine their applicability as a substitute material. The results of Dong-rim river sand (relatively uniform) show that as water content level increases, thermal resistivity tends to decrease, whereas the thermal resistivity on dry condition is very high value($260^{\circ}C-cm/watt$). In addition, other materials(such as Jinsan granite screenings, A-2(sand and gravel mixture), E-1(rubble and granite screenings mixture) and SGFC(sand, gravel, fly-ash and cement mixture)) are well-graded materials with low thermal resistivity($100^{\circ}C-cm/watt$ when dry). Based on this research, 4 types of improved materials were suggested as the environmentally friendly backfill materials with low thermal resistivity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.13 no.2
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• pp.215-221
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• 1984

To investigate stability for the quality of selected ginseng products, their sorption properties were clarified in red ginseng extract(RGEP), and red ginseng extract powder(RGEP), and red ginseng extract tea(RGET). Simultaneously, the BET monolayer value of each product was determined in order to inquire out the possibility of establishment as a criterion for the optimum moisture content of the ginseng products. Based on the BET monolayer moisture level of spray dried RGEP which ranged from 4.08 to 4.65%, it would be desirable to establish the optimum moisture content of the products at 4.4${\pm}$0.3%. This is 1.3 to 1.9% lower than the criter on, "less than 6.0%". The optimum moisture level for RGET of which monolayer value ranged 0.93 to 1.37% would be 1.2${\pm}$0.17%. In this case, the maximum permissible limit of moisture content could presumably be raised up to 1.37% in place of current criterion, "less than l.2%". From the results of a study on the growth of molds, the optimum moisture content for RGE assumed to be extended up to 40.0${\pm}$1.07 despite 36.0${\pm}$1.0% of the present criterion. On the other hand, a storage study under the maltreated condition, $48{\pm}2^{\circ}C$ 75%RH, was also carried out in order to make it clear whether the BET monolayer values were able to be used as indices for optimum moisture level of the products. In all samples tested adsorption occurred at even higher levels of moisture than the monolayer values. However, since there are many other possible factors affecting the quality of products the optimum moisture content is preferable to be reduced to the monolayer value. As a result, it was proved that the optimum level of moisture for both RGEP and RGET could be established by the monolayer values.

• Journal of Food Hygiene and Safety
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• v.24 no.4
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• pp.299-306
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• 2009

Aflatoxin (AF) and Ochratoxin A (OTA) are carcinogenic and possible carcinogenic mycotoxins respectively produced by Aspergillus spp or Penicillium spp. The study for contamination survey and proposal for reduction of mycotoxin in red pepper were carried out. 192 samples were collected at such various stages and markets as pre/post-harvest stages, internet shopping mall /super-market and small stakeholder mill/geographically indicated company. As only 2 samples were positive for aflatoxin, so contamination rate was 1.04%. In the meanwhile, contamination rate for ochratoxin A was 21.88% and a various amount of OTA was detected in 42 positive samples. 6 samples were found to be contaminated at higher level than $5\;{\mu}gkg^{-1}$ for ochratoxin A, which was established recently as a maximum permissible limit in korea. There was no difference in degree of contamination with regard to cultivation type because any mycotoxin was not found at all in both organically and conventionally grown red pepper. But, there was statistically significant difference in the process of manufacturing. Finished products were OTA-contaminated at a level of $2.32\;{\pm}\;6.54\;{\mu}gkg^{-1}$(mean ${\pm}$ SD), even though OTA was not detected in deep frozen red peppers right after long term storage. And contamination for OTA was a level of $0.33\;{\pm}\;0.91\;{\mu}gkg^{-1}$(mean ${\pm}$ SD) in red paprika powder after uv sterilization, while the contamination for OTA was $2.78\;{\pm}\;4.49\;{\mu}kg^{-1}$(mean ${\pm}$ SD) in non-uv sterilized powder. In addition, our investigation shows that higher OTA contamination occurred in some of famous brand products sold in super-market and domestic products than products collected through on-line shopping or from small stakeholder mills and imported products respectively, however, difference was not statistically significant.

• Journal of Food Hygiene and Safety
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• v.3 no.1
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• pp.7-18
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• 1988

In 1987, the level of heavy metals were determined ina total of 200 samples of 9 species of shellfish of Korea. The samples were collected at the fish. markets by 10 Public Institute of Health. The samples were whelk (Buccinum striatiBBimum), oyster (Crassostrea gigas), ark shell(Tegillarca granesa), shartnecked clam (Venerupis semidecussta), hard clam (Meretrix lusoria), top shell (Turbo cornutus), abalone (Haliotis gigantea), ark shell (Scapharea broughtonii), sea-mussel (Mytilus conuscus gould), respectively. The levels of total mercury, lead, cadmium, arsenic, copper, zinc and manganese were determined. The total mercury levels were determined by mercury analyzer using the combustion gold amalgamation method. The arsenic level were determined by spectrophotometry using colorimetric sil ver diethyldithiocarbamate method after dry ash dige8tion of the samples with magnesium oxide and magnesium nitrate. The levels of other metals were determined by inductively coupled pluma spectrophotometry after wet digestion of the samples with nitric acid and su1furic acid. The results were summerized as follows; 1. The overallranges and mean(ppm) were; Hg, ND-O.221 (0.036); Pb, 0.05-1.51 (0.37); Cd, 0.02-1.86 (0.61); As, 0.5-3.97 (1.22); Cu, 0.14-54.16 (4.93); Zn, 7.40-207.17 (30.09); Mn, 0.13-s.72 (3.40). 2. The levels of all 6 metals were found to be below the maximum permissible Iimits set by the Japan lor mercury, the Netherland for lead the Hong Kong for cadmium. The Finland for Arsenic no statutory Iimits for Zn and Mn in shellfish in any countries. 3. The results show that all the 9 species of shellfish studied, none have accumulated levels dangerous enough to pose a health problem.roblem.