• Journal of Korean Ophthalmic Optics Society
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• v.12 no.3
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• pp.19-25
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• 2007

It was studied how using soft contact lens multi-purpose solution (MPS), often used for medical treatment, effects the inhibition on cell growth, and how using the MPS demages eye cells, on rabbit eye's corneal epithelium and endothelium tissue. $ReNu^{(R)}$ (Baush & Lomb, USA), Opti-free $express^{(R)}$ (Alcon, USA), Free-sol $plus^{(R)}$ (Hanamedicon, Korea) were used as MPS. After culturing Clone 1-5C-4 cell lines (Human conjunctival cell lines), cell growth inhibition rate was measured by MIT assay. By making Hematoxylin and Eosin stain specimen, the morphology was observed by optical microscope. In the In vivo experiment, 9 white rabbit eyes (18 eyes) were classified into 3 groups. The experiment group is left eyes (9 eyes) of rabbit, and MPS were dropped; however the control group, the right eyes (9 eyes), were only used a saline solution without a preservatives. After the dropping within the period, the cornea surface of rabbit endothelium tissue was observed using scanning electron microscopy (SEM).

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.30 no.1
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• pp.1-9
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• 2020

Objectives: The purpose of this case study is to assess workers' exposure to carbon nanotubes(CNTs) and characterize particles aerosolized during the process of producing CNT-enabled polytetrafuoroethylene(PTFE) composites at a worksite in Korea. Methods: Personal breathing zone and area samples were collected for determining respirable concentrations of elemental carbon(EC) using NIOSH(National Institute for Occupational Safety and Health) Method 5040. Personal exposure to nano-sized particles was measured as the number concentration and mean diameter using personal ultrafine particle monitors. The number concentration by particle size was measured using optical particle sizers(OPS) and scanning mobility particle sizers(SMPS). Transmission electron microscopy (TEM) area samples were collected on TEM grids and analyzed to characterize the size, morphology, and chemistry of the particles. Results: Respirable EC concentrations ranged from 0.04 to 0.24 ㎍/㎥, which were below 23% of the exposure limit recommended by NIOSH and lower than background concentrations. Number concentrations by particle size measured using OPS and SMPS were not noticeably elevated during CNT-PTFE composite work. Instant increase of number concentrations of nano-sized particles was observed during manual sanding of CNT-PTFE composites. Both number concentrations and mean diameters did not show a statistically significant difference between workers handing CNT-added and not-added materials. TEM analyses revealed the emission of free-standing CNTs and CNT-PTFE aggregate particles from the powder supply task and composite particles embedded with CNTs from the computer numerical control(CNC) machining task with more than tens of micrometers in diameter. No free-standing CNT particles were observed from the CNC machining task. Conclusions: Significant worker exposure to respirable CNTs was not found, but the aerosolization of CNTs and CNT-embedded composite particles were observed during handing of CNT-PTFE powders and CNC machining of CNT-PTFE composites. Considering the limited knowledge on the toxicity of CNTs and CNT composite particles to date, it seems prudent to take a precautionary approach for the protection of workers' health.

• Journal of Sericultural and Entomological Science
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• v.17 no.1
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• pp.1-26
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• 1975

These studies were attempted to find out the optimum silk reeling system by use of automatic silk reeling machine to increase raw silk yield and reeling efficiency with various silk reelable cocoons. The obtained results are as follows; 1. The mean silk reelability ratio(X)of the Korean cocoons during the last ten years was 61 per cent, beside 64.7 per cent in autumn cocoon and 57.3 per cent in spring cocoon. However, the ratio variation of autumn cocoons was larger than that of spring cocoons. 2. A positive correlation between cocoon filament breaks during its process and silk reelability levels was shown to be significant. The cocoons of both poor and good reelability evidenced "J" shape distribution on the filament break graph by the order of reeling cocoon end. Many bave breaks were found at the inner shell of the cocoons, or in case of poor reelability cocoons. 3. The morphology of broken cocoon ends during the process was classified into A, B, C, D, E and F types, The occurrence of B type was majority, but that of F type was minority among them. 4. In case of the cocoon cooking, H-type ion-exchanged soft water was better for good reelability cocoons, Na and H-type ion exchanged neutral soft water for those of fair reelability, and alkaline (Na-type) soft water for those of poor reelability, respectively. 5. The modification of cooking water by mixing the above different types of water (50％ Na-type and 50％ H-type passed by standard natural water; 75％ Na-type and 25％ H-type passed by hard natural water; 25％ Na-type and 75％ H-type passed by soluble natural water) made higher yield of raw silk with tess breaks of thread. 6, In case cocoon ends groping water included sodium hexametaphosphate as much as 800 ppm. the groping efficiency and raw silk yield of cocoon was improved. The effect was pronounced in case of poor reelability cordons. 7. The most reasonable cocoon cooking and silk reeling condition for automatic silk reeling process were observed to be rather incomplete cook with good reelability cocoons and optimum cook with poor reelability cocoons succeeded by the reeling bath temperature of 45$^{\circ}C$, 8. The reasonable silk reeling velocities were observed to be about 150m per min. for good reelability cocoons, 120m per min. for fair reelability ones and 90 to 120m per min. for poor reelability ones. 9. In order to improve the raw silk yield of cocoons and reeling efficiency, the cocoon stand-by-ratio for reeling should be kept at the level of 40 per cent for good reelability cocoons or at 60 per cent for poor reelability ones beside necessary end found cocoon condition.

• Horticultural Science & Technology
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• v.28 no.4
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• pp.678-684
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• 2010

In an attempt to improve biomass and bioactive compound production, we cultured adventitious roots of $Eleutherococcus$ $koreanum$ in 250 mL Erlenmeyer flasks using Murashige and Skoog (MS) medium with different concentrations of auxins (IBA, NAA, IAA) and cytokinins (BA, kinetin, TDZ). Root biomass (fresh and dry weight) was enhanced at $5mg{\cdot}L^{-1}$ indole-3-butyric acid (IBA) after 5 weeks of culture. The content of total phenolics and flavonoids was also increased with $5mg{\cdot}L^{-1}$ IBA compared to ${\alpha}$-naphtalene acetic acid (NAA) or indole-3-acetic acid (IAA) treatments. The combination of $5mg{\cdot}L^{-1}$ IBA with $0.1mg{\cdot}L^{-1}$ thidiazuron (TDZ; N-phenyl-N'-1,2,3,-thidiazol-5-ylurea) enhanced root fresh and dry weight (1.4- and 1.6-fold, respectively) as well as the content of total phenolics and flavonoids compared to the relative control (without cytokinin). On the contrary, $N_6$-benzyladenine (BA) and 6-furfurylaminopurine (kinetin) did not significantly affect root biomass and bioactive compound production in adventitious roots of $E.$ $koreanum$. These results suggested that $5mg{\cdot}L^{-1}$ IBA combination with $0.1mg{\cdot}L^{-1}$ TDZ supplementation was most suitable for both biomass and bioactive compound production from adventitious roots of $E.$ $koreanum$.

• Journal of Embryo Transfer
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• v.12 no.2
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• pp.181-188
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• 1997

This study was carried out to determine the effect of bovine follicular fluid(bFF), hormones, and fetal bovine serum(FBS) supplemented in the medium on the in vitro fertilization and development of bovine embryos. The ovaries were obtained from a local abattoir and placed in physiological saline kept at 30~32˚C and brought to the laboratory within 3~4 hours. The oocytes and follicular fluid were collected by aspiration from visible follicles, and the oocytes of grades I on the basis of the morphology of cumulus cells attached and the homogeneity of cytoplasmic granules were selected and used for maturation. The basal media used for oocyte maturation, fertilization and embryo development in vitro were Ham' F-10, TALP and TCM-199, respectively. The hormones supplemented in maturation medium were consisted of 35 pg /ml FSH, 10 pg /ml LH and 1 pg/mi estradiol-l7$\beta$. The bFF collected from 5~9 mm follicles was centrifuged, filtered and inactivated by heat-treatment at 56˚C for 30 min. FBS also was inactivated with the same method and kept at -20˚C until use. The embryos were co-cultured with the monolayer of bovine oviductal epithelial cells at 39˚C under 5% $CO_2$ in air for 9 days. The results obtained were summarized as follows: The fertilization rate of oocytes was found 87.4% from 10% FBS and hormones treatment for IVM, and 37.1% of these TVF embryos were developed to blastocyst stage in 10% FBS groups. Compared with this control system, the fertilization rate was decreased significantly(P<0.05) in the maturation without either FBS or hormones. These IVF embryos were developed to morula stage at the similar rate, but to blastocyst at significantly(P<0.05) lower rate in the embryo culture with or without FBS supplementation. The fertilization rate(82.9%) in hormones and 10% inactivated bFF was similar with 10% FBS and hormone groups(87.4%), but decreased significantly(P<0.05) in 20 or 30% bFF (61.0 or 66.0%), respectively. In vitro developmental competence to blastocyst stage in 10% FBS and 20% inactivated bFF(37.1% and 31.4%) was higher than in 10 or 30% inactivated bFF(20.0 or 19.2%) or 10, 20 and 30% fresh bFF(19.1, 21.0 and 17.5%) The results indicated that the in vitro fertillzation and development rate of the embryos should be improved in 10% FBS or 20% inactivated culture system and 20% inactivated bFF might be available economically for bovine oocyte maturation and embryo culture instead of fetal bovine serum.

• Journal of Microbiology and Biotechnology
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• v.27 no.3
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• pp.460-470
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• 2017

Mussels are major fouling organisms causing serious technical and economic problems. In this study, antifouling activity towards mussel was found in three compounds isolated from a marine bacterium associated with the sea anemone Haliplanella sp. This bacterial strain, called PE2, was identified as Vibrio alginolyticus using morphology, biochemical tests, and phylogenetic analysis based on sequences of 16S rRNA and four housekeeping genes (rpoD, gyrB, rctB, and toxR). Three small-molecule compounds (indole, 3-formylindole, and cyclo (Pro-Leu)) were purified from the ethyl acetate extract of V. alginolyticus PE2 using column chromatography techniques. They all significantly inhibited byssal thread production of the green mussel Perna viridis, with $EC_{50}$ values of $24.45{\mu}g/ml$ for indole, $50.07{\mu}g/ml$ for 3-formylindole, and $49.24{\mu}g/ml$ for cyclo (Pro-Leu). Previous research on the antifouling activity of metabolites from marine bacteria towards mussels is scarce. Indole, 3-formylindole and cyclo (Pro-Leu) also exhibited antifouling activity against settlement of the barnacle Balanus albicostatus ($EC_{50}$ values of 8.84, 0.43, and $11.35{\mu}g/ml$, respectively) and the marine bacterium Pseudomonas sp. ($EC_{50}$ values of 42.68, 69.68, and $39.05{\mu}g/ml$, respectively). These results suggested that the three compounds are potentially useful for environmentally friendly mussel control and/or the development of new antifouling additives that are effective against several biofoulers.

• Elastomers and Composites
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• v.37 no.3
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• pp.159-169
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• 2002

The improvement of flame retardancy of the foams based on NBR/GTR compounds was conducted by formulating various materials i.e. NBR, GTR, inorganic and phosphorus containing flame retardants, foaming agent, cross-linking agent and activator. The foaming properties, morphology, smoke density and flame retardancy of the specimens were investigated using SEM, LOI tester, smoke density control system and cone calorimeter. The phosphorus containing flame retardant reduces heat release rate, increases the limiting oxygen index and a char formation. The inorganic flame retardant increases the limiting oxygen index and reduces heat release rate with an increased CO yield by char formation, and smoke suppressing effect. The formed char seemed to intercept the oxygen transport and heat transfer into the core area. When the composition ratios of the compounds of NBR/GTR were $100{\sim}80/0{\sim}20 wt.%$, and the ratios of the rubbers/flame retardants were $1/1.55{\sim}3.60 wt.%$, we could developed foams with low heat release rate, high limiting oxygen index($28.0{\sim}39.3$), closed or semi-closed cell of uniformity and reasonable expandability($225{\sim}250 %$).

• Journal of the Society of Cosmetic Scientists of Korea
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• v.34 no.4
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• pp.269-274
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• 2008

In this study we successfully altered the structural characteristics of the mica surface and were able to control oil-absorption by using the microwave enhanced etching (MEE) technique, which has originally been used in semiconductor industry. When microwave energy is applied to the mica, the surface of the mica is etched in a few minutes. As the result of etching, oil-absorption of the mica was enhanced and surface whiteness was improved by modifying the silicon dioxide layer. Additionally, the high whiteness was maintained even though the etched mica absorbed the sebum or sweat. The surface modification of mica was performed by microwave irradiation after the treatment of hydrofluoric acid. The degree of etching was regulated by acid concentration, irradiation time, the amount of energy and slurry concentration. The surface morphology of the etched mica appears to be the shape of the 'Moon'. The characteristics of surface area and roughness were examined by Brunauer-Emmett-Teller (BET) surface area analysis, atomic force microscopy (AFM), scanning electron microscopy (SEM), spectrophotometer and goniophotometer.

• Korean Security Journal
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• no.59
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• pp.161-188
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• 2019

Not much is known about the factors of North Korean refugees willingness to report crime. Based on the survey of 800 North Korean refugees living in the metropolitan area of South Korea, this study examined the theoretical factors influencing North Korean refugees' willingness of reporting crime. Focusing on the legal cynicism, procedural justice, and the behavior of law theory, this research verified that procedural justice model is most important in explaining their willingness to report crime. Variables under procedural justice model(i.e., perceived fairness of the law, confidence in the law, and perceived necessity of the law) were significant in an expected direction. On the other hand, most of the hypotheses based on social conditions derived from the five types of stratification, morphology, culture, organization, and social control presented by Donald Black (1974) showed no significant effects on the intent to report crime among North Korean refugees. Implications for research and policies were discussed based on the findings.

• Journal of Veterinary Clinics
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• v.28 no.1
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• pp.13-19
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• 2011

Semen cryopreservation induces the formation of reactive oxygen species (ROS), and the ROS cause sperm damage. We aimed to investigate the effects of the antioxidative enzyme catalase (CAT) on sperm quality and ROS during cryopreservation. Sperm rich fractions collected from five Duroc boars were cryopreserved in freezing extender with (200 or 400 U/mL) or without CAT (control). After thawing, sperm motility, viability, normal morphology, plasma membrane integrity, mitochondrial function and intracellular ROS were evaluated. CAT significantly improved total sperm motility at a concentration of 400 U/mL (P < 0.05), but didn't improve progressive sperm motility, viability, morphological defects, plasma membrane integrity and mitochondrial function in frozen-thawed boar sperm. In evaluation of ROS, CAT had no effect on reduction in ${\cdot}O_2$, but scavenged $H_2O_2$ in viable frozen-thawed boar sperm at concentrations of 200 and 400 U/mL (P < 0.05). In conclusion, CAT was not enough to improve quality of frozen-thawed sperm, but can reduce $H_2O_2$ generation in viable boar sperm during cryopreservation.