• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.9 no.1
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• pp.56-72
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• 1999

Airborne concentrations of welding fumes in which 13 different metals such as Al, Cd, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Si, Sn, Ti, and Zn were analyzed were measured at 18 factories including automobile assembly and manufactures, steel heavy industries and shipyards. Air samples were collected by personal sampler at each worker's worksite(n=339). Blood levels of Cd, Cu, Fe, Mn, Pb and Zn were also measured from samples taken from 447 welders by atomic absorption spectrometry and compared with control values obtained from 127 non-exposed workers. The results were as follows ; 1. Among various welding types, $CO_2$ welding 70.2 % were widely used, shielded metal arc welding(SMAW) 22.1 % came next, and rest of them were metal inert gas(MIG) welding, submerged arc welding(SAW), spot welding(SPOT) and tungsten inert gas(TIG) welding. 2. Welding fume concentration was $0.92mg/m^3$($0.02{\sim}15.33mg/m^3$) at automobile assembly and manufactures, $4.10mg/m^3$($0.02{\sim}70.75mg/m^3$) at steel heavy industries and $5.59mg/m^3$($0.30{\sim}91.16mg/m^3$) at shipyards, respectively, showing significant difference among industry types. Workers exposed to high concentration of welding fumes above Korean Permissible Exposure Limit(KPEL) amounted to 7.9 % and 12.5 %, in $CO_2$ welding and in SMAW at automobile assembly and manufactures and 62.7 % in $CO_2$ welding, and 12.5 % in SMAW at shipyards, and 66.2 % in $CO_2$ welding and 70.6 % in SMAW at steel heavy industries. 3. Geometric mean of airborne concentration of each metal released from welding fumes was below one 10th of KPEL in all welding types. Percentage of workers, however, exposed to airborne concentration of metals above KPEL amounted to 16.8 % in Mn and 7.6 % in Fe in $CO_2$ welding; 37.5 % in Cu in SAW, 30 % in Cu in TIG; and 25 % in Pb in SPOT welding. As a whole, 76 Workers(22.4%) were exposed to high concentration of any of the metals above KPEL. 4. There were differences in airborne concentration of metals such as Al, Cd, Cr, Cu. Fe. Mn, Mo, Ni, Pb, Si, Sn, Ti and Zn by industry types. These concentrations were higher in shipyards and steel heavy industries than in automobile assembly and manufactures. Workers exposed to higher concentration of Pb above KPEI amounted to 7.4 % of workers(7/94) in automobile assembly and manufactures. In shipyards, 19.2 % of workers(19/99) were over-exposed to Mn and 7.1 % (7/99) to Fe above KPEL. In steel heavy industries, 14.4 %(21/146), 7.5 %(11/146) and 13 %(19/146) were over-exposed to Mn, Fe and Cu, respectively. As a whole, 76 out of 339 workers(22.4%) were exposed to any of the metals above KPEL. 5. Blood levels of Cd, Cu, Fe, Mn, Pb, and Zn in welders were $0.11{\mu}g/100m{\ell}$, $0.84{\mu}g/m{\ell}$, $424.4{\mu}g/m{\ell}$, $1.26{\mu}g/100m{\ell}$, $5.01{\mu}g/100m{\ell}$ and $5.68{\mu}g/m{\ell}$, respectively, in contrast to $0.09{\mu}g/100m{\ell}$, $0.70{\mu}g/m{\ell}$, $477.2{\mu}g/m{\ell}$, $0.73{\mu}g/100m{\ell}$, $3.14{\mu}g/100m{\ell}$ and $6.15{\mu}g/m{\ell}$ in non-exposed control groups, showing significantly higher values in welders but Fe and Zn.

• The Korean Journal of Malacology
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• v.31 no.2
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• pp.103-112
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• 2015

Bay scallop (Argopecten irradians) has been farmed only in the South Sea of Korea. East Sea Fisheries Research Institute (ESFRI) has developed bay scallop aquaculture technologies to extend its aquaculture area to the Southeast Sea of Korea. For the artificial spawning, the water temperature was maintained at $23^{\circ}C$. Over 100,000,000 eggs were spawned through artificial spawning inductions, such as air exposure and thermal shock by rising the water temperature. The fertilization rate was over 91% with nearly 94,000,000 fertilized eggs. The shape of fertilized eggs was spherical with an average diameter of $61.7{\pm}0.05{\mu}m(54.1-67.4{\mu}m)$. Five days after fertilization, the eggs developed into prodissoconch shell, and continuously grew into umbo stage and then umbones stage. After 8 days of fertilization, the size of larva became $179.7{\pm}8.4{\mu}m$ on average ($150.4-204.8{\mu}m$), and the larva formed a foot and an eye spot. The larvae grew to $235.4{\pm}9.7{\mu}m$ in 10 days and attached to adherence material, becoming juvenile bay scallop. The shells grew from 22.71 mm to 72.40 mm in 6 month (June-December). The total weight increased from 2.0 g to 32.7 g at the same period. The daily growth rates of young scallop were $0.35mm\;d^{-1}$ (Apr. to Jun.) and $0.41mm\;d^{-1}$ (Jun. to Aug.), which were comparable to those found in the South Sea. These findings suggest that the bay scallop aquaculture may be suitable in the Southeast Sea of Korea and may provide an additional crop to aquaculturists.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.4
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• pp.391-400
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• 2016

The purpose of this study was to evaluate the difference of remineralization effects of various anti-cariogenic toothpastes on artificial carious lesions in primary and permanent teeth using quantitative light-induced fluorescence-digital (QLF-D) system. Sound human primary (n = 48) and permanent teeth (n = 48) were randomly divided into following groups : control group (Group 1), fluoride toothpaste (Group 2), functionalized tricalcium phosphate (fTCP) + fluoride toothpaste (Group 3), and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) toothpaste (Group 4). Specimens were prepared by exposure in a demineralizing solution and then treated using the different toothpastes twice daily during 14 days. All specimens were analyzed with the QLF-D system. QLF data analysis indicated three different toothpastes showed significant remineralizing effects compared to Group 1 in both primary and permanent teeth. Also, the remineralizing effects in Group 3 and 4 were significantly higher than in Group 2. This study suggested that the toothpastes containing fTCP + fluoride and CPP-ACP have the significant anti-cariogenic effects on enamel demineralization in both primary and permanent teeth, and QLF-D is an useful device to assess the incipient carious lesion and remineralization effects of the anti-cariogenic materials quantitatively. Therefore, clinicians can consider the QLF-D system for the evaluation of demineralization and remineralization in primary and permanent teeth.

• Microbiology and Biotechnology Letters
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• v.37 no.2
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• pp.125-132
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• 2009

In order to develop probiotics which may be a viable alternative of antibiotic use in pig industry, five bacterial strains (Lactobacillus sp. HN 52, 92, 98, 235 and AP 116) possessing antimicrobial properties were selected from 500 strains isolates of pig intestines. The bacteriocin produced by Lactobacillus sp. HN 235 displayed a relative broad spectrum of inhibitory activity against all Enterococcus strains, Pseudomonas aeruginosa, Listeria monocytogenes and Clostridium perfringens using the spot-on-lawn method. The production of antimicrobial substance started in the middle of the exponential growth phase, reached maximum levels (6,400 AU/mL) in the stationary phase, and then declined. Bacteriocin activity remained unchanged after 30 min of heat treatment at $95^{\circ}C$ and stable from pH 2.0 to 10 for 1 h, or exposure to organic solvents; however, it diminished after treatment with proteolytic enzymes. The molecular weight of the bacteriocin was about 5 kDa according to a tricine SDS-PAGE analysis.

• The Journal of the Korea Contents Association
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• v.17 no.11
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• pp.383-388
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• 2017

The purpose of this study was to compare radiation dose among workers in the radiation zone and to compare the doses of students in clinical practice in the same area to provide basic data on optimization of radiation protection. The subjects were 121 radiation related workers, 36 radiation workers, and 121 students who completed 8 weeks of clinical practice from Jan. 2016 to Dec. The depth and surface dose between the radiation related workers and the radiation workers were the highest with $.7440{\pm}1.676mSv$ and $.7753{\pm}1.730mSv$, respectively, and statistically significant (p<.01). Among the three groups, the depth dose was the highest at $.143{\pm}.136mSv$ for clinical practice students and the highest at surface dose of $.1513{\pm}.139mSv$. The lowest in both cases, The mean difference between the two groups was statistically significant (p<.01). In conclusion, it is necessary to manage thoroughly according to the ALARA(As Low As Reasonably Achievable) principle. Especially, it is necessary to systematically manage the dose of radiation for clinical students who are in the blind spot of radiation safety management.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.418-421
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• 2002

Fundamental study on quasi-monochromatic parallel radiography using a polycapillary plate and a plane-focus x-ray tube is described. The x-ray generator consists of a negative high-voltage power supply, a filament (hot cathode) power supply, and an x-ray tube. The negative high-voltage is applied to the cathode electrode, and the transmission type target (anode) is connected to the ground potential. The maximum voltage and current of the power supply were -100 kV (peak value) and 3.0 mA, respectively. In this experiment, the tube voltage was regulated from 20 to 25 kV, and the tube current was regulated by the filament temperature and ranged from 1.0 to 3.0 mA. The exposure time is controlled in order to obtain optimum film density, and the focal spot diameter was about 10 mm. The polycapillary plate is J5022-21 made by Hamamatsu Photonics Inc., and the outside and effective diameters are 87 and 77 mm, respectively. The thickness and the hole diameter of the polycapillary are 1.0 mm and 25 ${\mu}$m, respectively. The x-rays from the tube are formed into parallel beam by the polycapillary, and the radiogram is taken using an industrial x-ray film of Fuji IX 100 without using a screen. In the measurement of image resolution, we employed three brass spacers of 2, 30, and 60 mm in height. By the test chart, the resolution fell according to increases in the spacer height without using a polycapillary. In contrast, the resolution slightly fell with corresponding increases in the height by the polycapillary. In angiography, fine blood vessels of about 100 ${\mu}$m are clearly visible.

• Journal of Periodontal and Implant Science
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• v.42 no.1
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• pp.13-19
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• 2012

Purpose: The aim of this study was to examine whether a previous peri-implantitis site can affect osseointegration, by comparing implant placement at a site where peri-implantitis was present and at a normal bone site. A second aim of this study was to identify the tissue and bone reaction after treating the contaminated implant surface to determine the optimal treatment for peri-implant diseases. Methods: A peri-implant mucositis model for dogs was prepared to determine the optimal treatment option for peri-implant mucositis or peri-implantitis. The implants were inserted partially to a length of 6 mm. The upper 4 mm part of the dental implants was exposed to the oral environment. Simple exposure for 2 weeks contaminated the implant surface. After 2 weeks, the implants were divided into three groups: untreated, swabbed with saline, and swabbed with $H_2O_2$. Three implants from each group were placed to the full length in the same spot. The other three implants were placed fully into newly prepared bone. After eight weeks of healing, the animals were sacrificed. Ground sections, representing the mid-buccal-lingual plane, were prepared for histological analysis. The analysis was evaluated clinically and histometrically. Results: The untreated implants and $H_2O_2$-swabbed implants showed gingival inflammation. Only the saline-swabbed implant group showed re-osseointegration and no gingival inflammation. There was no difference in regeneration height or bone-to-implant contact between in situ implant placement and implant placement in the new bone site. Conclusions: It can be concluded that cleaning with saline may be effective in implant decontamination. After implant surface decontamination, implant installation in a previous peri-implant diseased site may not interfere with osseointegration.

• Horticultural Science & Technology
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• v.33 no.1
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• pp.55-60
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• 2015

Skin blackening is a serious postharvest disorder occurring in 'Fuyu' persimmon fruits (Diospyros kaki, 'Fuyu'). Phenolic content, polyphenol oxidase (PPO) and peroxidase (POD) activity, and lipid saturation were investigated in skin tissue of 'Fuyu' fruits. The phenolic compounds were accumulated unevenly on fruit skin depending on sunlight exposure, i.e., the most accumulation on sunny side and the least on the opposite, shaded side. The fruits harvested from shaded branches inside the canopy showed relatively even distribution of phenolic compounds in the skin. The activity distribution of PPO and POD were also uneven but only in fruits suffering f rom skin b lackening disorder, w ith the h ighest and the lowest a ctivity of PPO and P OD, respectively, in the blackened area of the fruit. When the sunny, southern sides of fruits were marked at harvesting time and fruits were stored at low temperature, a round black spot, as a symptom of skin blackening disorder, developed during storage exactly on the marked region. In addition, the sunny side of fruit showed higher lipid saturation, thus indicating adaptation to high temperature caused by the sunlight. These results suggest that the skin blackening disorder of 'Fuyu' fruits can be considered as a kind of chilling injury symptom that develops on the high-temperature-acclimated skin tissue of sunlight-exposed fruits when they are later exposed to low temperature.

• The Korean Journal of Nuclear Medicine Technology
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• v.17 no.1
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• pp.62-66
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• 2013

Purpose: I-131 is a radioisotope widely used for thyroid gland treatments. The physical half life is 8.01 and characterized by emitting beta and gamma rays which is used in clinical practice for the purpose of acquiring treatment and images. In order to reduce the recurrence rate after surgery in high-risk thyroid cancer patients, the remaining thyroid tissue is either removed or the I-131 is used for treatment during relapse. In cases of using a high dosage of radioactive iodine requiring hospitalization, the patient is administered dosage in the hospital isolation ward over a certain period of time preventing I-131 exposure to others. By checking the radiation amount emitted from patients before discharge, the patients are discharged after checking whether they meet the legal standards (50 uSv/h). After patients are discharged from the hospital, the contamination level is checked in many parts of the ward before the next patients are hospitalized and when necessary, decontamination operations are performed. It is expected that there is exposure to radiation when measuring the ward contamination level and dose check emitted from patients at the time of discharge whereby the radiation exposure by health workers that come from the patients in this process is the main factor. This study analyzed the correlation between discharge dose of patients and ward contamination level through a variety of factors such as renal functions, gender, age, dosage, etc.). Materials and Method: The study was conducted on 151 patients who received high-dosage radioactive iodine treatment at Soon Chun Hyang University Hospital during the period between 8/1/2011~5/31/2012 (Male: Female: 31:120, $47.5{\pm}11.9$, average dosage of $138{\pm}22.4$ mCi). As various factors expected to influence the patient discharge dose & ward contamination such as the beds, floors, bathroom floors, and washbasins, the patient renal function (GFR), age, gender, dosage, and the correlation between the expected Tg & Tg-Tb expected to reflect the remaining tissue in patients were analyzed. Results: In terms of the discharge dose and GFR, a low correlation was shown in the patient discharge dose as the GFR was higher (p < 0.0001). When comparing the group with a dosage of over 150mCi and the group with a lower dosage, the lower dosage group showed a significantly lower discharge dose ($24{\pm}10.4uSv/h$ vs $28.7{\pm}11.8uSv/h$, p<0.05). Age, gender, Tg, Tg-Tb did not show a significant relationship with discharge dose (p> 0.05). The contamination level in each spot of the treatment ward showed no significant relationship with GFR, Tg, Tg-Tb, age, gender, and dosage (p>0.05 ). Conclusion: This study says that discharge of the dose in the patient's body is low in GFR higher and Dosage 150mCi under lower. There was no case of contamination of the treatment ward, depending on the dose and renal association. This suggests that patients' lifestyles or be affected by a variety of other factors.

• Korean Journal of Microbiology
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• v.17 no.3
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• pp.97-130
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• 1979

Many industrial processes those employ bacteria are subjected to phage infestations. In L-glutamic acid fermentions using acetic acid, the phage infestations of the organisms have been recently recognized. In efforts to elucidate the sources of phage contamination involved in the abnormal fermentation, a series of study was conducted to isolate the phages both from the contents of abnormally fermented tanks and the soil or sewage samples from the surroundings of a fermentation factory, to define major charateristics of the phage isolates, and finally to determine the correlation between the phage isolates and temperate phages originating from the miscellaneous bacterial species isolated from the soil or sewage samples. The results are summarized as follows; 1) All phages were isolated from the irregular fermentation tanks and soil or sewage samples, and they were designated as phage PR-1, PR-2, PR-3, PR-4, PR-5, PR-6, and PR-7, in the order of isolation. These PR-series phages were proved to be highly specific for the variant strains of Br. lactofermentum only, namely, phage PR-1 and PR-2 for Br. lactofermentum No. 468-5 and phage PR-3~PR-7 for Br. lactofemrentum No. 2256. By cross-neutralization test, the 7 phagescould be subdivided into 3 groups, i. e., phage PR-I and PR-2 the first, phage PR-3, PR-4, PR-5, PR-6 the second, and the phage PR-7 the third. 2) The 7 phages were virulent under the experimental conditions. They produced plaques with clear and relatively sharp margins without distinct halo. The mean sizes of plaques were 1.5mm in diameter for phage PR-1 and PR-2, and 1. Omm for phages PR-3~PR-7. Double layer technique modified by Hongo and described by Adams, was applied to assay of the PR-series phages. The factors influencing the plaques were as follows;young age cells of host bacteria cultured for 3-6 hours represented the largest number and size, optimum was pH 7.0, incubation temperature was $30^{\circ}C$, and agar concentration and amount of overlayer medium were 0.6% and 0.2ml, respectively. 3) PR-series phages were stable in 0.05M tris buffer and 0.1M ammonium acetate buffer solution. The addition of $5{\times}10^{-3}M$ magnesium ion effectively increased the stability. Thermostability experiments indicated that PR-series phages were stable at the teinperture between $50^{\circ}{\sim}55^{\circ}C$ in nutrient medium, $45^{\circ}{\sim}50^{\circ}C$ in buffer solution. However, the phages mere completely inactivated at 603C and 65$^{\circ}$C within 10 minutes. The phages were stable at the range of pH6~9 in nutrient medium and of pH 8-9 in buffer solution, respectively. Exposure of the phages to UV for 25, 60 and 100 seconds resulted in the complete loss of infectivily, respectively. 4) Electron microscopy showed that PR-series phage particles exhibited rather similar morphology, differing in the size All of PR-series phages had a multilateral head and had a simple long tiil about three to five times long as compared with head. By the size, phage PR-1 and PR-2, PR-3, PR-4, PR-5, and PR-6 and PR-7 were classified into same groups, respectively. The head and tail size of phage PR-1, PR-5, PR-5(T) and PR-7 were 85nm, 74nm and 235nm and 350mm, and 72nm and 210nm, respectively. 5) Nucleic acids of PR-series phages were double stranded DNA. The G+C contents of phage PR-1, PR-5 and PR-7 were 56.1, 52.9 and 53.7, respectively. The values of G+C contents derived from the $T_m$ were in agreement with the chemically determined values. 6) PR-series phages effectively adsorbed on their host bacteria at the rate of more than 90% during 5 min. K value for phage PR-1, PR-5 and PR-7 were calculated to be $6{\times}10^9 ml$ per minute, respectiveky. The pH of the medium did effect adsorption rate, but both temperature and age of host cells did not. Generally, optimum adsorption condition of phages seemed to be almost same as optimum growth conditions of host bacteria. 7) In one-step growth experiments, the latent periods at $30^{\circ}C$ for PR-1, and PR-7 were about 70, 50 and 55 min, respectively. The corresponding average burst size was 200, 70 and 90, respectively. Lpsis period according to the multiplicity of infection and a phage series. In case of m. o. i. 100, strain No. 2256 (PR-5) and No. 468-5(PR-1) failed to grow and turbidity decreased after 50 and 70min, respectively. 8) In the lysate of a plaque purified phage PR-5 infected bacteria, there observed 2 types ofphage particles, i. e., phage PR-5 and PR-5 (T) of similar morphology but differing at the length of phage tail, and phage tail like particles. The phage taillike particles could be divided into 4 types by the length. Induction experiments of Br. lactofermentum with UV irradiation, mitomycin C or bacitracin treatment produced neither phage PR-5 (T) or phage tail-like particles. 9) No lysis occured when the growth of 7 strains of miscellaneous bacteria, isolated from soil and sewage samples, were inoculated with either phage PR-5 (T) or phage tail-like particles the inoculation of phage PR-5 pellet resulted in the growth inhibition of the orgainsms in the spot test. The lysates obtained from 3 miscellaneous soil derived bacteria following mitomycin C treatment the growth of Br. lactofermentum, but did not lyze the bacterium.