• 한국치위생학회지
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• 제10권3호
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• pp.483-493
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• 2010

Objectives : The purpose of this study was to obtain the information for the improvement of the support in oder to expand the adjusted water fluoridation program to Myeong-dong water treatment plant in Gimhae city, Korea. Methods : Questionnaires were distributed to the parents of elementary schoolchildren and their responses were collected. All collected data were analyzed using the SPSS program. Results : The percentage of respondents using the tap water was 47.0% for drinking and 54.4% for cooking, respectively. The percentage of respondents using the water purified the tap water with the home water purifier was 45.1% for drinking and 36.2% for cooking, respectively. Respondents who knew the adjusted water fluoridation program was 48.3%. Respondents who knew the implementation of the adjusted water fluoridation program at the moment in Gimhae was 27.0%. 90.2% of residents agreed on the expansion of the adjusted water fluoridation program to Myeong-dong water treatment plant, Significant variables in the approval rates of the adjusted water fluoridation program were age, residence period, occupation, recognition of the program. Conclusions : It is desirable to expand the adjusted water fluoridation program to Myeong-dong water treatment plant in Gimhae as the percentage of respondents who agreed on the introduction of the program was high.

• 한국패류학회지
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• 제14권2호
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• pp.149-159
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• 1998

In order to observe the anticellulolytic localization in the epithelia of the digestive tract such as esophagus, crop, and intestine of a Korean land snail N. samarangae, a cytochemical method and a immunogold labelling method were applied. For the cytochemical study on the cellulase activity, Benedict reaction method applied. And for the immunocytochemical study, the rabbit serum immunoglobuins (IgG) was obtained from the rabbits injected with cellulase which was extracted from body fluid of the snail. The digestive tract tissues of N. samarangae were fixed with 4% paraformaldehyde and 2% OsO4 and embedded in Lowicryl K4M at -40$^{\circ}C$ under UV light (360 nm). The thin sections were loaded on the nickel grids and stained with the serum IgG and protein A-gold complex (particle size: 10 nm). Observations were undertaken with transmission electron microscope (Jeol, JEM-1010). The epithelium of the digestive tract was consisted of five types of cells. In the cytochemical study, the reaction products were found along the periphery of the vacuoles derived from the Bebedict reaction. In the immunocytochemical study, the protein-A gold particles were selectively labelled in Type 1, Type 3 and Type 4 cells in intestinal tissue. membranes of rER, in the surrounding cytoplasm of the rER and secretory granules, and in the apical cytoplasm of the cells. On the material being secreted from the apical cytoplasm was also labelled with the immunogold particles. The all results obtained throughtout present study suggest that the intestinal epithelium of the snail N. samarangae seretes cellulase as one of digestive enzymes.

• Molecular & Cellular Toxicology
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• 제4권4호
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• pp.360-365
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• 2008

In the last several years, studies on the association of oxidative stress damage with exposure in the work place have been conducted. Xenobiotics create an imbalance of the homeostasis between oxidant molecules and antioxidant defense. By monitoring oxidative stress biomarkers, information was obtained on damages induced by oxidative stress and the toxicity of xenobiotics. In the present study, a Job Exposure Matrix (JEM) was constructed using the data from the Working Environment Measurement (WEM) of painters in the shipyard industry from the past 3 years to assess the exposure status. Additionally, by measuring the concentration of urinary malondialdehyde (MDA), the effect of lipid peroxidation was examined. The subjects consisted of 68 workers who were exposed to mixed organic solvents in the painting process and 25 non-exposure controls. The exposure indices of the exposure groups were significantly different (sprayer: 0.83, touchup: 0.54, assistant: 0.13, P<0.05). The urinary MDA concentration of the exposure group was 48.60${\pm}$ 39.23 ${\mu}mol$/mol creatinine, which was significantly higher than 18.03${\pm}$16.33 ${\mu}mol$/mol creatinine of the control group (P<0.05). From the multiple regression analysis of urinary MDA, the regression coefficient for exposure grade was statistically significant. In future studies, evaluation of the antioxidant levels of subjects should be performed simultaneously with quantitative exposure measurements.

• Applied Microscopy
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• 제13권1호
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• pp.13-30
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• 1983

[ $1-{\beta}-D-Arabinofuranosylcytosine$ ](ara-C), which is a pyrimidine nucleoside analog is cytotonic to mammalian cells in culture and is active in vitro and in vivo against a variety of DNA viruses. The precise mechanism of action of ara-C has not been determined, although ara-C is thought to act as an antimetabolite, interfering with the synthesis of deoxyribonucleic acid(DNA). Cytosine arabinoside originally seemed to act principally by inhibiting the conversion of cytidine to deoxytidine, thus inhibiting DNA synthesis. But recent data suggest that effects upon DNA polymerase and effects via incorporation into DNA and RNA may well be of equal importance. The author have demonstrated the effect of cytosine arabinoside on the hepatocytes of albino mice treated with ara-C, observing changes in the cytoplasmic organelles of the hepatocytes. A total of 120 healthy male albino mice were divided into the control and ara-C treated groups. The animals of the ara-C group were given 10mg. per kg of body weight of mouse ara-C in physiological saline solution and the animals of control group were given physiological saline solution, intraperitoneally. After an administration of ara-C or physiological saline solution, the animal were killed at. interval of 6, 12, and 24 hours. The specimens, which were obtained from the left anterier lobe of the liver, were stained with uranyl acetate and lead citrate and observed with JEM 100B electron microscope. The results were obtained as follow: A pronounced dilatation, sacculation and fragmentation of the cisterane of rough endoplasmic reticulum with dissociation of membrane bound-ribosomes, disaggregation of free ribosomes in the cytoplasm, proliferation of the smooth endoplasmic reticulum associated with depletion of glycogen paracles, atrophies of Golgi complex, production of numerous lipid droplets, and formation of antophagic vacuoles, multivesicular bodies and residual bodies are recognized in the hepatocytes of ara-C treated mice. Consequently it is suggested that cytosine arabinoside would induce a changes of the cytoplasmic organelles of the hepatocytes in albino mice.

• Applied Microscopy
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• 제26권4호
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• pp.431-446
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• 1996

This experiment was performed to study the ultrastructural changes of the juxtaglomerular cell of mice following subcutaneous injection of heavy metallic agents. Male mice were divided into normal and experimental groups. The mice were subcutaneouly injected with $HgCl_2$ (2mg, 5mg or 10 mg/Kg/BW) or with $K_{2}Cr_{2}O_7$(5 mg, 10 mg or 20 mg/Kg/BW). Mice were sacrificed on 6 hours, 3 days and 14 days after the injection. Kidneys were fixed in the 2.5% glutaraldehyde-1.5% paraformaldehyde solution, followed by refixation in the 1% osmium tetroxide solution. Dehydrated blocks were embedded in araldite mixture. The sections were cut on a LKB-V ultratome, and ultrathin sections stained with uranyl acetate and lead citrate were observed with JEM 100CX II electron microscope. The results were as follow: 1. Juxtaglomerular cell of the experimental groups showed some alterations, especially in the structures of protein synthesis including dilations and degradations of granular endoplasmic reticula, atrophy of Golgi complex, and numerous free ribosomes in the cytoplasm. 2. Juxtaglomerular cells treated groups showed a number of vacuoles, protogranules and some myelin figures in the cytoplasm, especially in the earlier groups. 3. Juxtaglomerular cells of treated groups, contained a large number of secretory granules showing variable electron densities and pleomorphism in later groups (2 weeks). From the above results, it was concluded that, the mercuric chloride or potassium bichromate induces acute renin release from juxtaglomerular cells of the mice, but many juxtaglomerular cells may secrete prematured secretory granules, or the synthetic system of the cell can not perform normal function.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.630-630
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• 2013

Recently, atomically smooth hexagonal boron nitride(h-BN) known as a white graphene has drawn great attention since the discovery of graphene. h-BN is a III-V compound and has a honeycomb structure very similar to graphene with smaller lattice mismatch. Because of strong covalent sp2bonds like graphene, h-BN provides a high thermal conductivity and mechanical strength as well as chemical stability of h-BN superior to graphene. While graphene has a high electrical conductivity, h-BN has a highly dielectric property as an insulator with optical band gap up to 6eV. Similar to the graphene, h-BN can be applied to a variety of field, such as gate dielectric layers/substrate, ultraviolet emitter, transparent membrane, and protective coatings. However, up until recently, obtaining and controlling good quality monolayer h-BN layers have been too difficult and challenging. In this work, we investigate the controlled synthesis of h-BN layers according to the growth condition, time, temperature, and gas partial pressure. h-BN is obtained by using chemical vapor deposition on Cu foil with ammonia borane (BH3NH3) as a source for h-BN. Scanning Transmission Electron Microscopy (STEM, JEOL-JEM-ARM200F) is used for imaging and structural analysis of h-BN layer. Sample's surface morphology is characterized by Field emission scanning electron microscopy (SEM, JEOL JSM-7100F). h-BN is analyzed by Raman spectroscopy (HORIBA, ARAMIS) and its topographic variations by Atomic force microscopy (AFM, Park Systems XE-100).

• 복식
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• 제5권
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• pp.65-81
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• 1981

I referred to documents to study the origin and the progressing process of textiles. Cotton seeds were first imported from China by Mun, Ik Jem at the end of the era of Koryeo, and cotton had several different names such as mok-myen, cho-myen, gil-pae, baek-chep-za, tap-po, ban-ki-wha, dong-yep-po and so on. Since the era of the Three Kingdoms, people had heard of cloth of superior quality but it was not certain whether it was imported from China or made in our country. It seems that cotton was not made during that period, white silk, hemp cloth, and ramie fabric were produced. At that time, linen was called cotton by mistake. After importing cotton seeds from China, all the people began to plant them and made their clothes from them. At the beginning of the Yi Dynasty, the weaving technique was dependent on China. However, the government persuaded farmers to plant them. At that time cotton was used as a means of purchasing instead of money. Silkworms raising started during the era of the Three Kingdoms and it was widely spread at the beginning of the Yi Dynasty. In order to encourage sericulture' spinning and weaving instruments were installed in the royal palace and the queen with sher court maids demonstrated how to spin and weave. The activity was named "chin-jam-ye." Linen was the representative of all textiles and it was also very popular. The technique of weaving had already been highly developed at the era of Silla. During the era of the Three Kingdoms people used "bang-chu-cha" as a weaving instrument. They discovered several new hand machines in the period of the Yi Dynasty: they were instrument of removing seeds, spinning wheel, hemp cloth loom and so on, and we find the remains of them these days.

• Safety and Health at Work
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• 제8권1호
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• pp.105-115
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• 2017

Background: The goal of this study is to develop a general population job-exposure matrix (GPJEM) on asbestos to estimate occupational asbestos exposure levels in the Republic of Korea. Methods: Three Korean domestic quantitative exposure datasets collected from 1984 to 2008 were used to build the GPJEM. Exposure groups in collected data were reclassified based on the current Korean Standard Industrial Classification ($9^{th}$ edition) and the Korean Standard Classification of Occupations code ($6^{th}$ edition) that is in accordance to international standards. All of the exposure levels were expressed by weighted arithmetic mean (WAM) and minimum and maximum concentrations. Results: Based on the established GPJEM, the 112 exposure groups could be reclassified into 86 industries and 74 occupations. In the 1980s, the highest exposure levels were estimated in "knitting and weaving machine operators" with a WAM concentration of 7.48 fibers/mL (f/mL); in the 1990s, "plastic products production machine operators" with 5.12 f/mL, and in the 2000s "detergents production machine operators" handling talc containing asbestos with 2.45 f/mL. Of the 112 exposure groups, 44 groups had higher WAM concentrations than the Korean occupational exposure limit of 0.1 f/mL. Conclusion: The newly constructed GPJEM which is generated from actual domestic quantitative exposure data could be useful in evaluating historical exposure levels to asbestos and could contribute to improved prediction of asbestos-related diseases among Koreans.

• Earthquakes and Structures
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• 제22권2호
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• pp.185-201
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• 2022

Structural Health Monitoring (SHM) is used to provide reliable information about the structure's integrity in near realtime following extreme incidents such as earthquakes, considering the inevitable aging and degradation that occurs in operating environments. This paper experimentally investigates an integrated wireless sensor network (Wi-SN) based monitoring technique for damage detection in concrete structures. An effective SHM technique can be used to detect potential structural damage based on post-earthquake data. Two novel methods are proposed for damage detection in reinforced concrete (RC) building structures including: (i) Jerk Energy Method (JEM), which is based on time-domain analysis, and (ii) Modal Contributing Parameter (MCP), which is based on frequency-domain analysis. Wireless accelerometer sensors are installed at each story level to monitor the dynamic responses from the building structure. Prior knowledge of the initial state (immediately after construction) of the structure is not required in these methods. Proposed methods only use responses recorded during ambient vibration state (i.e., operational state) to estimate the damage index. Herein, the experimental studies serve as an illustration of the procedures. In particular, (i) a 3-story shear-type steel frame model is analyzed for several damage scenarios and (ii) 2-story RC scaled down (at 1/6th) building models, simulated and verified under experimental tests on a shaking table. As a result, in addition to the usual benefits like system adaptability, and cost-effectiveness, the proposed sensing system does not require a cluster of sensors. The spatial information in the real-time recorded data is used in global damage identification stage of SHM. Whereas in next stage of SHM, the damage is detected at the story level. Experimental results also show the efficiency and superior performance of the proposed measuring techniques.

• Applied Microscopy
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• 제29권1호
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• pp.25-41
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• 1999

종양의 치료제로 많이 사용되고 있는 대표적인 항암제 가운데 대사길항제인 5-fluorouracil과 항암항생제인 mitomycin C가 콩팥토리에 미치는 영향을 미세구조적으로 비교 관찰하고자 이 실험을 시행하였다. Mitomycin C는 $LD_{50}$의 1/20 이하인 $400{\mu}g/kg$를, 5-fluorouracil는 $LD_{50}$의 1/4 정도인 60mg/kg를 격일 간격으로 계속 투여하였다. 각 항암제투여군은 처음 주사후 4일 (2회 투여)과 7일 (3회 투여) 째에 희생시킨 후 콩괄겉질부위의 조직을 메어 JEM 100CX-II 전자 현미경으로 관찰하였다. 1. 5-fluorouracil 및 mitomycin C 투여후 4일군에서는 다같이 혈관사이막이 증가하여 모세혈관과 주머니공간이 매우 좁아 보이는 부분이 많았는데, 그 현상은 mitomycin C 투여군에서 더 심했다. 2. 5-fluorouracil 투여 7일군은 토리의 미세구조가 거의 정상군의 모습과 비슷하게 회복되어 보였으나 mitomycin C 투여 7일군은 토리의 미세구조가 정상군의 모습과 비슷하게 회복된 모습을 거의 관찰할 수 없었다. 3. Mitomycin C 투여 4일군과 7일군에서는 내피세포의 종창현상(swelling) 이 심해서 내강으로 돌출되었을 뿐만 아니라 혈관사이세포가 모세혈관내강으로 돌출되어 내강을 거의 막고 있는 경우가 자주 관찰되었다. 4. Mitomycin C 투여 4일군에서는 토리모세혈관바닥막의 속투명판과 바깥투명판의 전자밀도가 높아서 치밀판과의 경계가 뚜렷하지 못한 부분이 많았는데, 부위에 따라서는 속투명판이 넓어진 부분이 관찰되기도 하였다. 이상의 결과를 종합해 보면 mitomycin C를 투여하였을 경우에는 마우스의 콩팥토리는 모세혈관의 내강이 좁아지고 혈관사이막이 증가하며 내피세포는 종창현상을 보이는 등의 미세구조적 변화를 보였다. 그러나 5-fluorouracil을 투여하였을 경우, 초기 (4일)에는 발세포와 혈관사이막의 경우 mitomycin C 투여군에서와 비슷한 미세구조적 변화를 보였으나, 7일군에서는 거의 정상군의 소견과 비슷한 모습을 보였다. 이와 같은 결과는 콩팥토리를 비롯한 콩팥조직에 미치는 세포독성은 mitomycin C가 5-fluorouracil에 비하여 훨씬 더 강하기 때문이라고 생각된다.