• Bulletin of the Korean Space Science Society
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• 2003.10a
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• pp.85-85
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• 2003

We examined the hypothesis that the crater formation rate exhibits periodicity, employing data sets of Grieve (1991), Moon et al. (2001), and the Earth Impact Database (2002; DB02). DB02 is known to supercede previous compilations in terms of its accuracy and precision of the ages; it is the first time that this database has been used for periodicity analysis. For data sets comprising impact structures with D$\geq$5km (and also those with $\geq$20km), there is no convincing evidence for periodicities in the crater ages, according to our Fourier analysis. However, we detected two peaks at 16.1Myr and 34.7Myr for craters with D$\geq$30km; we confirm that the age distribution of impact craters with D$\geq$45km has dominant power at 16.1Myr. Thus, we may conjecture a probable periodic shower of Earth impactors with sizes d$\geq$1.5km. In addition, we found that the selection of data sets, the lower limits on the ages and diameters of impact craters, as well as the accuracy and precision of the ages, all constitute crucial factors in reconstructing the impact cratering history of the Earth.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.158-167
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• 2016

This study was conducted to evaluate the quality of meta-analysis of social work in South Korea using the Assessment of Multiple Systematic Review (AMSTAR). Electronic databases including the Korean Studies Information Service System (KISS), DBpia, and RISS4U were searched for 'meta-analysis', 'social work', and 'social welfare' from 2000 to December 2015, and 42 meta-analysis studies were included. Data were analyzed using descriptive statistics, t-tests, and ANOVA. The mean score for AMSTAR evaluation was $4.766{\pm}1.66$, while 19 studies (45.2%) were classified at the low-quality level, and 22 (52.4%) were at the moderate-quality level. The scores of quality assessment were analyzed by publication year, participants, number of studies included, number of DB, reporting study quality, extraction diagram and topics. The findings indicated that the following changes should be implemented to improve the quality and reliability of meta-analysis results in social work research: 1) common reporting guidelines should be provided for the social work field, 2) quality analyses of each study should be conducted to achieve a high level of evidence of effectiveness of social work interventions, 3) the characteristics of the included studies should be provided, and 4) a consensus and procedure based on at least two independent data extractors should be reported.

• Journal of Information Technology Applications and Management
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• v.28 no.6
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• pp.97-116
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• 2021

Due to the decrease in the school-age population and government regulations, universities have made great efforts to secure their own competitiveness. In particular, the selection of universities with financial support based on the recent evaluation of the Ministry of Education has become a major concern enough to affect the existence of the university itself. This paper extracts three-year data from 124 major private universities nationwide, and quantitatively analyzes the variables of major universities selected as self-improvement universities, competency reinforcement universities, and universities with limited financial support. As a result of estimating the selection of self-powered universities using the ordered logit model by hierarchically inputting 12 variables, student competitiveness in the metropolitan area (1.318^**), Educational Restitution Rate (4.078^***), University operation expenditure index rate (1.088^***) values were found. Significant positive coefficient values were found in the admission enrollment rate (45.98^***) and the enrollment rate (13.25^***). As a result of analyzing the marginal effects, the increase in the rate of reduction of education costs has always been positive in the selection of self-powered universities, but it was observed that the rate of increase decreases in areas of increase of 150% or more. On the contrary, the probability of becoming a Em-powered university was negative in all sectors, but on the contrary, it was analyzed that marginal effects increased at the same time point. On the other hand, the employment rate of graduates was not able to find direct significance with the result of the selection of Self powered universities. Through this paper, it is expected that each university will analyze the possibility and shortcomings of the selection of Self powered universities in policy making, and in particular, the risk of dropout of selection for the vulnerable field can be predicted using marginal effects. It can be used as major research data for both university evaluators, university officials and students.

• Korean journal of food and cookery science
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• v.22 no.5 s.95
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• pp.720-727
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• 2006

The purpose of this study was to investigate the functional properties of medicinal plant extracts. Four kinds of medicinal plants, Dioscorea batatas(DB), Armeniacae Semen(AS) Crataegus pinnatifida Bunge(CP) and Ponciri Fractus(PF), were extracted with water and 70% ethanol and the extracts were tested for their electron donating ability(EDA), nitrite scavenging ability(NSA) and inhibitory effects on cancer cells(MDA cell and A549 cell)growth. EDA at 100-1,000 ppm of water extract ranged from 3% to 14%, 14% to 36%, 29% to 72% and 14% to 43%, and that of ethanol extract ranged from 9% to 62%, 27% to 59%, 33% to 89% and 14% to 44%, in DB, AS, CP and PF, respectively. NSA of extracts measured at various pH(1.2, 3.0, 4.2, 6.0) showed the highest ability in all extracts at pH 1.2 and decreased with increasing pH. The highest NSA of water extracts of 1,000 ppm at pH 1.2 was 6%, 31%, 55% and 44% and that of ethanol extract was15%, 32%, 69% and 52%, in DB, AS, CP and PF, respectively Inhibition ratio of water and ethanol extracts on MDA cell growth was 24% and 17%, 51% and 93%, 46% and 69%, and 48% and 47%, while that on A549 cell was 18% and 9%, 6% and 3%, 7% and 3%, and 43% and 11%, at 1,000 ppm, in DB, AS, CP and PF, respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.5
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• pp.651-663
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• 2016

Corn silk, Job's tears, Lentinus edodes, and apple peel 70% ethanol extracts (CS, JT, LE, and AP) were studied for their antioxidant activities. CS among all extracts showed the highest antioxidant activities based on total polyphenol and flavonoid contents, 2,2-diphenyl-${\beta}$-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) radical scavenging activity, and reducing power. Adipocyte differentiation was investigated by Oil Red O staining assay using CS, JT, LE, AP, and extract of developed bread containing corn silk, Job's tears, Lentinus edodes, and apple peel (DB) treated to 3T3-L1 adipocytes. DB1 and DB2 showed anti-adipogenic and antioxidant effects. Triglyceride (TG) accumulation in 3T3-L1 cells was measured, and among the samples tested (CS, JT, LE, and AP), CS was found to have the highest inhibitory activity against TG accumulation of differentiated 3T3-L1 adipocytes and regulated factors associated with adipogenesis. CS suppressed lipid droplet formation and adipocyte differentiation in 3T3-L1 cells in a dose-dependent manner. We examined the effects of CS on the levels of CCAAT-enhancer-binding protein ${\beta}(C/EBP{\beta})$, peroxisome proliferator activated receptor ${\gamma}(PPAR{\gamma})$, and adipocyte-specific lipid binding protein (aP2) mRNA as well as protein levels in 3T3-L1 cells treated with CS at various concentrations (0, 10, 50, and $100{\mu}g/mL$) during adipocyte differentiation and treatment with CS in 3T3-L1 adipocytes down-regulated expression of $PPAR{\gamma}$ and aP2 mRNA. CS also significantly inhibited up-regulation of $C/EBP{\beta}$, $PPAR{\gamma}$, and aP2 proteins during adipocyte differentiation. These data indicate that DBs have anti-adipogenic activity induced by CS in 3T3-L1 preadipocytes, and CS exerts anti-adipogenic activity by inhibiting expression of $C/EBP{\beta}$, $PPAR{\gamma}$, and aP2 signaling pathway in 3T3-L1 adipocytes. JT, LE, and AP had no inhibitory effects on differentiation of 3T3-L1 preadipocytes but displayed strong antioxidant effects. These results suggest that the developed bread may be a health beneficial food that can prevent or treat obesity and diseases induced by oxidative stress.

• Restorative Dentistry and Endodontics
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• v.44 no.2
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• pp.16.1-16.12
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• 2019

Objectives: The upper molars generally have three roots; therefore, different combinations of fusion can occur, increasing the possibility of finding more complex root canal systems. The purpose of this study was to evaluate the prevalence and characterization of fused roots in first and second maxillary molars using cone-beam computed tomography (CBCT) in a Colombian population. Materials and Methods: A total of 1274 teeth were evaluated, of which 534 were maxillary first molars and 740 were maxillary second molars. Axial sections were made at the cervical, middle, and apical levels to determine the prevalence of root fusion and the types of fusion. Results: Overall, 43% of the molars (n = 551) presented some type of fused root. Root fusion was present in 23.4% of the maxillary first molars. The most frequent type of fused root was type 3 (distobuccal-palatal; DB-P) (58.9%). Root fusion was observed in 57.6% of the maxillary second molars, and the most prevalent type of fused root was type 6 (cone-shaped) (45.2%). Of the maxillary molars, 12.5% were classified as C-shaped. Conclusion: Within the limitations of this study, there was a high prevalence of fused roots in maxillary molars in the Colombian population, mainly in the maxillary second molars. In first molars, the most common type of fused root was type 3 (DB-P) and in second molars, the most common type was type 6 (cone-shaped). Additionally, molars with root fusion presented variation at different levels of the radicular portion, with implications for treatment quality.

• International Journal of Industrial Entomology and Biomaterials
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• v.27 no.2
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• pp.237-242
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• 2013

We investigated the 1-deoxynojirimycin (1-DNJ) content of extracts from silkworm larvae at each developmental stage within three silkworm varieties. We also compared the content of the following polyhydroxylated alkaloids in the silkworm extracts: 1-DNJ, fagomine, and 1,4-dideoxy-1,4-imino-d-arabinitol (DAB). In addition, we evaluated the glucose-lowering effects of silkworm extract powder in db/db mice. The 1-DNJ content was the highest in Yeonnokjam $5^{th}$ instar $3^{rd}$ d larvae and Hansaengjam $5^{th}$ instar $3^{rd}$ d larvae, which contained 18.4 mg/100 g dry weight and 18.3 mg/100 g dry weight, respectively. The $5^{th}$ instar $3^{rd}$ d larvae exhibited a higher content of 1-DNJ than that of $5^{th}$ instar $5^{th}$ d larvae among all varieties. The glucose-lowering effects of silkworm extracts and Yeonnokjam powder were tested on db/db mice, and the blood glucose levels were found to decrease significantly in the YR70 group. Silkworm extracts (180 mg/kg, 90 mg/kg, 45 mg/kg, and 22.5 mg/kg) and acarbose (50 mg/kg) were administered orally for 4 wk. Changes in water intake were not statistically significant between control and silkworm extract-treated groups. Compared to the control group, blood glucose levels in the silkworm extract powder-treated group decreased in the 22.5 mg/kg/d group after being administered for 4 wk. This decrease was statistically significant. Furthermore, biochemical changes in the AST(Aspartate aminotransferase), ALT(Alanine aminotransferase), TCHO(Total Cholesterol), TG(Triglyceride), LDL(Low density lipoprotein), and HDL(High density lipoprotein) levels in blood were not observed. However, statistically significant decreases in blood GLU in the 22.5 mg/kg/d group compared to that of the control group occurred. In addition, the epididymal fat weight of the silkworm extract powder-treated group decreased significantly in both the 22.5 mg/kg/d group and 180 mg/kg/d group compared to that of the control group, but there were no statistically significant changes in perirenal fat weight. These results demonstrate that silkworm extracts inhibit changes in blood glucose levels in model diabetic mice.

• Toxicological Research
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• v.25 no.1
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• pp.41-45
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• 2009

This study was conducted to monitor the level of bifenthrin residues in pear sprayed with 2% bifenthrin wettable powder (WP) at the recommended rate at four different schedules prior to harvest. The target analyte was extracted with acetone, partitioned into dichloromethane, and then purified by florisil chromatographic column. The residue determination was performed on a DB-5 capillary column using GC with electron capture detector (ECD). Linearity of this method was quite good ($r^2$ = 0.9951) in the concentration ranged from 0.2 mg/kg to 10 mg/kg. Recovery test was carried out at two concentration levels, 0.2 mg/kg and 1.0 mg/kg, in three replicates, and their rates were from 82.9% to 107.2%. No quantitative bifenthrin was detected in pear of all kinds of treatments including the treatment sprayed 4 times until 7 days before harvest. This sensitive and selective method can be used to monitor the trace residual amounts of bifenthrin in pear in a quite low concentration level.

• Journal of the Korean Society of Safety
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• v.30 no.1
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• pp.60-65
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• 2015

This study is to explore floor impact sound and sound insulation of reinforced concrete structure with void-deck slab system which combines polystyrene void foam and T-shaped steel deck plate. A void-deck slab system can effectively reduce the amount of concrete used and hence the mass of a reinforced concrete slab. Also void slab system has dynamically favorable for bending. Three-bay 2-story building was constructed as a mock up test specimen using void-deck slab system and floor impact sound was measured to valuate sound insulation performance. Light weight floor impact and heavy weight floor impact were investigated. Light weight floor impact pressure levels were 32dB, 28dB, and 29db at representative locations which are $1^{st}$ level in the floor impact sound insulation performance grading system. The heavy-weight floor impact pressure levels were 44dB, 45dB, and 43dB at representative locations which are $2^{nd}$ level in the floor impact sound insulation performance grading system. Therefore void-deck slab system can be used in public housing apartment building in terms of not only effectively reduced construction materials but also floor impact sound insulation.

• The Journal of the Acoustical Society of Korea
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• v.25 no.5
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• pp.213-221
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• 2006

Phone segmentation of speech waveform is especially important for concatenative text to speech synthesis which uses segmented corpora for the construction of synthetic units. because the quality of synthesized speech depends critically on the accuracy of the segmentation. In the beginning. the phone segmentation was manually performed. but it brings the huge effort and the large time delay. HMM-based approaches adopted from automatic speech recognition are most widely used for automatic segmentation in speech synthesis, providing a consistent and accurate phone labeling scheme. Even the HMM-based approach has been successful, it may locate a phone boundary at a different position than expected. In this paper. we categorized adjacent phoneme pairs and analyzed the mismatches between hand-labeled transcriptions and HMM-based labels. Then we described the dominant error patterns that must be improved for the speech synthesis. For the experiment. hand labeled standard Korean speech DB from ETRI was used as a reference DB. Time difference larger than 20ms between hand-labeled phoneme boundary and auto-aligned boundary is treated as an automatic segmentation error. Our experimental results from female speaker revealed that plosive-vowel, affricate-vowel and vowel-liquid pairs showed high accuracies, 99%, 99.5% and 99% respectively. But stop-nasal, stop-liquid and nasal-liquid pairs showed very low accuracies, 45%, 50% and 55%. And these from male speaker revealed similar tendency.