• Korean Journal of Materials Research
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• v.27 no.9
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• pp.489-494
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• 2017

ZnS powder was synthesized using a relatively facile and convenient glycothermal method at various reaction temperatures. ZnS was successfully synthesized at temperatures as low as $125^{\circ}C$ using zinc acetate and thiourea as raw materials, and diethylene glycol as the solvent. No mineralizers or precipitation processes were used in the fabrication, which suggests that the spherical ZnS powders were directly prepared in the glycothermal method. The phase composition, morphology, and optical properties of the prepared ZnS powders were characterized using XRD, FE-SEM, and UV-vis measurements. The prepared ZnS powders had a zinc blende structure and showed average primary particles with diameters of approximately 20~30 nm, calculated from the XRD peak width. All of the powders consisted of aggregated secondary powders with spherical morphology and a size of approximately $0.1{\sim}0.5{\mu}m$; these powders contained many small primary nanopowders. The as-prepared ZnS exhibited strong photo absorption in the UV region, and a red-shift in the optical absorption spectra due to the improvement in powder size and crystallinity with increasing reaction temperature. The effects of the reaction temperature on the photocatalytic properties of the ZnS powders were investigated. The photocatalytic properties of the as-synthesized ZnS powders were evaluated according to the removal degree of methyl orange (MO) under UV irradiation (${\lambda}=365nm$). It was found that the ZnS powder prepared at above $175^{\circ}C$ exhibited the highest photocatalytic degradation, with nearly 95 % of MO decomposed through the mediation of photo-generated hydroxyl radicals after irradiation for 60 min. These results suggest that the ZnS powders could potentially be applicable as photocatalysts for the efficient degradation of organic pollutants.

• Parasites, Hosts and Diseases
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• v.27 no.3
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• pp.213-216
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• 1989

Seven cases of Diphyllcbothrium latum infection were proved by collection of worms after prasiquantel treatment between October, 1986 and July, 1987. The patients were all males aged 20~44 years residing in Seoul or Ulungdo, Kyungpook Province. All of them had the history of eating several kinds of raw marine fishes, and they had never been to abroad. One of them exporienced abdominal pain and 6 experienced natural discharge of a chain of worm segments, but none revealed any sign of anemia, Total 12 worms (1~3/patient) were collected after praiiquantel treatment. The worms were 85~423 cm in length, and revealed the characteristic rosette-shape uterus in their gravid proglottides. The average egg size varied $61.0~65.3{\times}41.7~46.1{\;}{\mu\textrm{m}}$. The eggs were yellowish. brown, and ovoid to elliptical. Including the present 7 cases, the total number of human D. latum infections proven by worms in Korea becomes 28 cases.

• Journal of Life Science
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• v.11 no.5
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• pp.393-399
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• 2001

In order to improve functionality of kochujang which is one of the traditional foods in Korea, sea tangle powder(2, 4, 6 and 8% sea tangle powder on the glutinous rice weight basis) was added to the raw material of kochujang and then investigated the bacterial counts and enzyme activities with control kochujang during the fermentation at 3$0^{\circ}C$ for 120 days. Bacterial count was about 10$^4$ cfu/g at initial stage of fermentation and then maintained 10$^{8}$ cfu/g after 60 days of fermentation. $\alpha$-amylase activity was gradually reduced during fermentation periods, so the activity was lost almost at late of fermentation $\beta$-amylase activity was rapid increased until 30 days of fermentation and the rapid decreased at 60 days of fermentation and after 90 days was slightly decreased. Activities of acidic protease and neutral protease were increased until 30 days of fermentation and then these were shown irregularities decreased.

• Journal of the Korean Geophysical Society
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• v.8 no.2
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• pp.81-87
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• 2005

Acquisition and processing of vector seismic waves were conducted through simultaneous generation of P, SH, and SV waves and receiving those waves using three-component geophones. Test data were received by 24 8-Hz geophones at an interval of 2 m along a 94-m profile. The data were recorded for 512 ms with sampling intervals of 0.2 ms. Raw data indicate that both reflected and refracted P waves are strongly recorded on the vertical component while SH waves are significant on the transverse horizontal component. On the inline horizontal component, both direct P and converted PS waves are recorded. First arrivals of P and SH waves were detected simultaneously on the vertical and transverse horizontal axes, respectively. The recorded vector data were separately inverted using traveltime tomography to yield P- and SH-wave sections. Using those two velocity sections, Poisson's ratios were able to be obtained effectively.

• Applied Biological Chemistry
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• v.41 no.5
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• pp.363-366
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• 1998

Supercritical fluid(SCF) carbon dioxide was used to extract safflower yellow pigments from Carthamus tinctorius L. In this work, supercritical fluid extractions were performed at various conditions; pressure (2000, 3000, 4000, 5000 psig), temperature $(40,\;50,\;60,\;70,\;80^{\circ}C)$ and co-solvent $(0,\;3,\;6,\;10,\;14\;wt%\;H_2O)$. Total concentrations of safflower yellow pigments extracted were determined by spectrophotometric method. A maximum yield of yellow pigments was obtained at 4000psig, $60^{\circ}C$ and 10% co-solvent. The extraction yield of pigments was also closely related to moisture content of the raw material. Extraction yield of safflower yellow pigments by SCF extraction at optimized conditions was 6% higher than that by solvent extraction. Supercritical carbon dioxide was proved to be suitable for the extraction of safflower yellow pigments from Carthamus tinctorius L.

• Journal of Ocean Engineering and Technology
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• v.10 no.2
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• pp.77-87
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• 1996

The estimation of the remaining life for the aged components in power plant as well as chemical and peroleum plants has been recently coberned. The raw materials used in this syudy are the 1Cr-1Mo-0.25V rotor steel which intensified P and S compositions along with the nominal compositions of ASTM A470 standard. Five kinds of specimens with the different degradation levels were prepared by isothermal aging teat treatment at $630^{\circ}C$ The mechanical properties and fatigue strength of virgin and aged 1Cr-1Mo-0.25V rotor steel have been inbestigated through the hardness, tensile, fatigue test, SEM fractograph and EDS analysis at room temperature. Thus, the data of aged specimens were compared with those of virgin specimen to evaluate the aging effects. The main results obtained in this study are as follows; The decrease of the hardness due to degradation was distinguished until 50, 000hrs simulated service time. And is was confirmed that the considerable amount of P, Mn, Cr and S was precipitated at the grain boundary of aged material through the SEM and EDS analysis. The fatigue strength of 25, 000, 50, 000, 75, 000 and 100, 000hrs aged material was decreased 29.5%, 24.4%, 28.6%, 35.7% than that of virgin material at $10^7$ cycles of room temperature. The major cracks of virgin and aged materials initiated at the inclusions including Si, P and Mn compositions which were located at the outer periphery of the specimen.

• Parasites, Hosts and Diseases
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• v.57 no.6
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• pp.705-708
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• 2019

Gymnophalloides seoi (Digenea: Gymnophallidae) is a human intestinal trematode contracted by eating raw oysters (Crassostrea gigas) in the Republic of Korea (=Korea). It has been known to be highly endemic in Aphae Island, Shinan-gun, Jeollanam-do (Province). However, recent epidemiological status of G. seoi has not been reported since the 1990s. In this study, we investigated the prevalence of G. seoi metacercariae in natural and cultured oysters collected from 3 islands and 2 coastal areas in western parts of Korea. The oysters were examined using the artificial digestion method followed by stereomicroscopy. The overall positive rate of G. seoi metacercariae in natural oysters was 66.0% (99/150), and the oysters collected from Yubu Island showed the highest infection rate (74.0%). However, the metacercarial density per oyster was relatively low (1.5-2.4 per oyster). By contrast, no metacercaria was found in cultured oysters purchased from 2 coastal areas in Chungcheongnam-do. Thus, we could confirm that natural oysters produced from 3 western coastal islands are infected with G. seoi metacercariae, whereas cultured oysters purchased from 2 coastal areas were free from infection.

• Journal of Sericultural and Entomological Science
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• v.43 no.2
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• pp.109-115
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• 2001

Silk sericin protein was extracted by treatment with enzyme or NaOH solution from raw silk and culled-cocoon shell. The extracted sericin was characterized and examined the functional properties as well as subjective properties for its use as a soap and a body cleaner. The optimum extraction conditions on specimen are NaOH (0.02 wt.%) or enzyme, Flavourzyme 3% under N2 gas. Molecular weights of sericin was decreased by treatment with enzyme, Actinase, from 10,000-30,000 to 2,700-4,200. Sericin showed important bioactive properties, for instance, lowering effect on blood glucose and alcohol. Subjective test of sericin soap and body cleaner showed superior in washability, foamability, and skin hydration, etc., to commercial soap and body cleaner. Therefore, it is thought that silk sericin can be expected as the source of bioactive and skin-compatible materials.

• Journal of dental hygiene science
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• v.21 no.3
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• pp.185-197
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• 2021

Background: This study aimed at investigating the meal regularity, health, and oral health habits of single Korean households to understand the impact of these factors on the risk of metabolic syndrome, in addition to preventing and managing metabolic syndrome. Methods: Using raw data from the 8th Korea National Health and Nutrition Examination Survey (2019), 274 study subjects, aged 19 to 64, were selected primarily from single adult households. Complex sample statistical analysis was performed using the Predictive Analytics Software Statistics ver. 18.0 program. Results: Regarding the meal regularity in single-person households in Korea, the younger group outperformed the middle-aged group, and those who drank more than once a month performed better than those who drank less than once a month. In terms of oral health, regardless of the age and the income level, participants who ate three meals a day had a higher rate of speech problems and chewing difficulties than those who ate irregularly or regularly on a regular day. Factors influencing the risk of developing metabolic syndrome were age, speech problems, and frequency of toothbrushing. Compared to the younger group, there were 0.361 times more people in the middle-aged group; and compared to those without speech problems, there were 1.161 more people with speech problem. Compared to those who tooth brushed more than four times a day, there were 1.284 more people who tooth brushed 2 to 3 times a day and there were 5.673 times more people who tooth brushed less than once. Conclusion: Based on the study results, it is necessary to implement a program that can plan and apply customized management measures and prevent metabolic syndrome by improving and correcting the health and oral health behaviors of single-person households in Korea. Therefore, active mediation measures, such as support and publicity at the local or national level, should be planned.

• Journal of the Korean Society of Mineral and Energy Resources Engineers
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• v.55 no.6
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• pp.517-526
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• 2018

In order to remove pollutants from the soil in the Ka-hak mine site, this study investigates optimization of the acid washing conditions for the soil. The soil at the site is presumed to be contaminated by diffused heavy-metal-contaminated tailings. The major heavy metal pollutants in the soil are copper, lead, and zinc. Gravels larger than 5mm in size constitute approximately 38% of the soil, and these are the least polluted by heavy metals. On the other hand, it is difficult to reduce the concentration of heavy metals in fine soils, particularly those whose sizes are less than 0.075 mm. The results of the continuous process using a hydro-cyclone show that fine soil particles consisting of at least 20% of the raw soil must be separated before the chemical soil washing process in order to achieve reliable cleaning.