• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.30 no.4
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• pp.342-352
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• 2020

Objectives: The characteristics of research workers are different from those working in the manufacturing industry. Furthermore, the reagents used change according to the research due to the characteristics of the laboratory, and the amounts used vary. In addition, since the working time changes almost every day, it is difficult to adjust the time according to exposure standards. There are also difficulties in setting standards as in the manufacturing industry since laboratory environments and the types of experiments performed are all different. For these reasons, the measurement of the working environment of research workers is not realistically carried out within the legal framework, there is a concern that the accuracy of measurement results may be degraded, and there are difficulties in securing data. The exposure evaluation based on an eight-hour time-weighted average used for measuring the working environment to be studied in this study may not be appropriate, but it was judged and consequently applied as the most suitable method among the recognized test methods. Methods: The investigation of the use of chemical substances in the research laboratory, which is the subject of this study, was conducted in the order of carrying out work environment measurement, sample analysis, and result analysis. In the case of the use of chemical substances, after organizing the substances to be measured in the working environment, the research workers were asked to write down the status, frequency, and period of use. Work environment measurement and sample analysis were conducted by a recognized test method, and the results were compared with the exposure standards (TWA: time weighted average value) for chemical substances and physical factors. Results: For the substances subject to work environment measurement, the department of chemical engineering was the most exposed, followed by the department of chemistry. This can lead to exposure to a variety of chemicals in departmental laboratories that primarily deal with chemicals, including acetone, hydrogen peroxide, nitric acid, sodium hydroxide, and normal hexane. Hydrogen chloride was measured higher than the average level of domestic work environment measurements. This can suggest that researchers in research activities should also be managed within the work environment measurement system. As a result of a comparison between the professional science and technology service industry and the education service industry, which are the most similar business types to university research laboratories among the domestic work environment measurements provided by the Korea Safety and Health Agency, acetone, dichloromethane, hydrogen peroxide, sodium hydroxide, nitric acid, normal hexane, and hydrogen chloride are items that appear higher than the average level. This can also be expressed as a basis for supporting management within the work environment measurement system. Conclusions: In the case of research activity workers' work environment measurement and management, specific details can be presented as follows. When changing projects and research, work environment measurement is carried out, and work environment measurement targets and methods are determined by the measurement and analysis method determined by the Ministry of Employment and Labor. The measurement results and exposure standards apply exposure standards for chemical substances and physical factors by the Ministry of Employment and Labor. Implementation costs include safety management expenses and submission of improvement plans when exposure standards are exceeded. The results of this study were presented only for the measurement of the working environment among the minimum health management measures for research workers, but it is necessary to prepare a system to improve the level of safety and health.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.6
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• pp.252-259
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• 2005

Single crystal $CuGaSe_2$ layers were grown on thoroughly etched semi-insulating CaAs(100) substrate at $450^{\circ}C$ with hot wall epitaxy (HWE) system by evaporating $CuGaSe_2$ source at $610^{\circ}C$. The crystalline structure of the single crystal thin films was investigated by the photoluminescence (PL) and double crystal X-ray diffraction (DCXD). The carrier density and mobility of single crystal $CuGaSe_2$ thin films measured with Hall effect by Van der Pauw method are $4.87{\times}10^{17}cm^{-3}$ and $129cm^2/V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $CuGaSe_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)=1.7998eV-(8.7489{\times}10^{-4}eV/K)T^2/(T+335K)$. The voltage, current density of maxiumun power, fill factor, and conversion, efficiency of $n-CdS/p-CuGaSe_2$, heterojunction solar cells under $80mW/cm^2$ illumination were found to be 0.41 V, $21.8mA/cm^2$, 0.75 and 11.17%, respectively.

• Journal of the Korean Chemical Society
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• v.30 no.5
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• pp.441-448
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• 1986

Dioxobis(sub.-salicylaldiminato) molybdenum (VI) complexes, $MoO_2\;(X-sal-N-R)_2,\;(X=H,\;5-CH_3,\;R=C_6H_5,\;p-F-C_6H_4,\;m-Cl-C_6H_4,p-I-C_6H_4\;and\;p-C_2H_5-C_6H_4)$, have been prepared by reactions of dioxobis(sub.-salicylaldehydato) molybdenum (VI), $MoO_2(X-sal)_2$ with primary amines, in which $MoO_2(X-sal)_2$ complexes were obtained by acidification of a mixture solution of ammonium paramolybdate in water and appropriate salicylaldehyde in methanol. All these complexes show two strong Mo=O stretching imodes in the 900-940$cm^{-1}$ and p.m.r. spectra exhibited only one signal for the azomethine group. These results confirmed that the complexes are six-coordinated octahedron with a $cis-MoO_2$ group and the geometrical configurations of the complexes possess a C2 axis of symmetry. From the mass analyses of the complexes, it found that the composition ratios of $MoO_2$ : ligand are 1 : 2. The charge transfer transition corresponding to N-Mo, and O-Mo occured at 29,000$cm^{-1}$ and 32,000$cm^{-1}$ respectively. Where, the complexes were found to be non-ionic materials by conductivity measurements in dimethylformamide.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.2476-2483
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• 2014

This study aims to review the characteristics of specialized classrooms for governmental secondary schools in the Japanese Colonial Era by analyzing architectural drawings collected by National Archives of Korea. The results of this study are summarized as follows 1) Under the influence of Japanese science promotion of that time, specialized classrooms for science were considered as one of essential facilities. Typically exclusive specialized classrooms were assigned to two major science subjects : physics-chemistry and biology. 2) To science specialized classrooms, ancillary rooms for preparation, experiment equipment and specimen were attached and science lecture room with stepped floor was planned additionally only for the lecture on theories and the demonstration of experiment. 3) Specialized classrooms for science were zoned independently of other facilities because of the special equipments and safety. 4) Art rooms were common to both boys' and girls' schools but concerning music rooms, girls' schools had special concerns, whereas boys' schools did not. 5) Specialized classrooms for homemaking subject of girls' school were as much important as those for science subjects of boys' school. 6) Some early-established Korean boys' schools had handicraft rooms which were the symbol of vocational education-oriented, unequal policy on Koreans. Though not general cases, specialized classrooms for geography-history were planned for Japanese boys' school. Restricted to governmental secondary schools but considering the uncommon state of specialized classrooms of that time, these characteristics show conditions of early time when special classrooms were introduced into Korea.

• Journal of Food Hygiene and Safety
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• v.22 no.3
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• pp.179-191
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• 2007

The purpose of this study was to monitor and compare the contamination levels of heterotrophic bacteria and pathogenic bacteria (total coliforms, Escherichia coli O157:H7, Salmonella spp., Vibrio parachaemolyticus, Staphylococcus aureus and Bacillus cereus). The samples collected at fish farms located in the Jeju-island were investigated from March to August in 2006. The contamination levels of S. aureus, B. cereus and Salmonella spp. ranged $0-3.3{\times}10^2 CFU/ml,\;0-2.2{\times}10^2 CFU/ml\;and\;0-5.1{\times}10^1CFU/ml$, respectively, and 85% of moist pellet feeds were contaminated with S. aureus, B. cereus and total coliforms. But total coliforms and E. coli O157:H7 were not detected in oliver flounder (Paralichthys olivaceus). For the production of safe oliver flounder (Paralichthys olivaceus), education of sanitation for employees, control of fish feed, and continuous monitoring for microorganism will be required.

• Journal of Life Science
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• v.18 no.10
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• pp.1355-1359
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• 2008

Endophytic fungi predominantly inhabit grasses, and produce a variety of beneficial metabolites for plant growth, as well as help their hosts against pathogens and herbivores. Current study was focused on plant growth promoting activity of endophytic fungi inhabited in the roots of sand dune grasses. We collected 49 fungal isolates from the roots of four most common sand dune grasses and screened them for their growth promoting capacity. Results showed that 37 fungal isolates (75.5%) promoted plant height and shoot length of waito-c rice, 11 fungal isolates (22.5%) suppressed it, while 1 fungus (2%) showed no effect on the growth attributes. The fungal strain Gibberella fujikuroi, along with distilled water and Czapek broth medium, were taken as control for this experiment. It was concluded that a major proportion of endophytic fungi inhabited in the sand dune plants produce metabolites, and thus help in growth and development of the host plant.

• Journal of Gifted/Talented Education
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• v.26 no.2
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• pp.405-421
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• 2016

The purpose of this study was to investigate students' perception of Advanced Placement Program. Participations of this study were 1144 students from 14 science high schools. The results showed as follows. First, students perceived positively regarding AP program and were willing to take AP courses because of interesting and challenging in academic area which is provided by AP courses. Secondly, many students would like to take AP courses in Differential and Integral Calculus 1, General Physics I, General Chemistry I and General Biology. Also, they would like to take AP courses in first term as a mandatory subjects. Third, responses perceived that AP courses were challenging, difficult, and of high quality. Finally, students perceived the benefit of AP courses in earing college credit. However, 35% of responses wished to receive an exemption for all AP courses. Also, they wished to have dual-major or participate in students exchange program as a benefit of AP program. Implications of the study were discussed in depth based on the results.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.2
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• pp.198-202
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• 1997

Jangkimchi is a kind of Kimchi which is made with soy-sauce instead of salt. Occasionally, when sugar is added to Jangkimchi for condiment, the kimchi juice becomes viscous. In this study. the nature of the viscous material and the condition for producing viscous property in Kimchi juice were investigated. HPLC analysis showed that the viscous material in Jangkimchi is polysaccharide composed of glucose. Sucrose was more effective in forming viscous juice than glucose and the viscosity increased with the addition of sucrose up to 10%. Soy-sauce also played a role in increasing the viscosity of Kimchi juice compared with salt. Aerobic fermentation condition was found to be another factor to make the juice viscous. The population of Leuconostoc mesenteroides, well-known producer of viscous dextran was not different in the Kimchi juice prepared with the addition of sucrose from that without sucrose, which implys that the Jangkimchi preparation methods such as addition of sucrose and soy-sauce would do some effects on the production of viscous material in Jangkimchi.

• Korean Journal of Environmental Agriculture
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• v.8 no.2
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• pp.142-147
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• 1989

In this report, we set up a simple device which enabled us to obtain data useful to estimate the relative capacity of thermal energy retention of greenhouse built with various plastic coverings. A box($20cm{\times}20cm{\times}30cm$) framed with flexiglass at the edges and covered with thin plastic films was made, in which were placed a thermostat-controlled nichrom wire heater and a thermal probe made of thermister to monitor temperature changes. A wheaston-bridge type transducer and a chart recorder were used to record the changes of temperature inside the box The data obtained by using the device showed that the relative rate of heat toss through plastic films with identical thickness decreased in the order of PE film>EVA film>PVC film and that IR additives such as fine silica gel improved the insulating power of plastic films. This observations are in well accord with general information, demostrating the feasibility of the device in usefulness for the purpose of screening of various commercial plastic coverings.

• Journal of the Korean Society of Food Culture
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• v.8 no.3
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• pp.249-255
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• 1993

To minimize the waste amount of surface layer kochujang during aging, the effects of the three finishing methods(nothing, salt scatering and Polyethylene film on the kochujang surface) and sunning(conventional aging method) or nonsunning aging(cap covering) on water content, redness and spreadability, film forming yeast occurance and salinity of surface layer kochujang during 120 days aging were investigated. In the case of sunning aging, film forming yeast was not visually found on the surface. The surface layer kochujang was so low spreadability(zero) and very high salinity(18-30%) that could not eat. However, the aging method after PE-film covering on the kochujang surface, and then cap covering(nonsunning) was very effective in keeping of soundness of surface layer kochujang without film forming yeast growth on the surface kochujang, especially was greatly effective in keeping of redness, moderate moisture content and spreadability. The PE-film and cap covering aging were effective in prevention of water evaporation and $CO_2$ release, and in accumulation of ethanol and organic acids between the PE-film and surface layer of kochujang.