• Wind and Structures
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• 제30권2호
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• pp.181-198
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• 2020

In the traditional buffeting response analysis method, the spanwise incomplete correlation of buffeting forces is always assumed to be same as that of the incident wind turbulence and the action of the signature turbulence is ignored. In this paper, three typical bridge decks usually adopted in the real bridge engineering, a single flat box deck, a central slotted box deck and a two-separated paralleled box deck, were employed as the investigated objects. The wind induced pressure on these bridge decks were measured via a series of wind tunnel pressure tests of the sectional models. The influences of the wind speed in the tests, the angle of attack, the turbulence intensity and the characteristic distance were taken into account and discussed. The spanwise root coherence of buffeting forces was also compared with that of the incidence turbulence. The signature turbulence effect on the spanwise root coherence function was decomposed and explained by a new empirical method with a double-variable model. Finally, the formula of a sum of rational fractions that accounted for the signature turbulence effect was proposed in order to fit the results of the spanwise root coherence function. The results show that, the spanwise root coherence of the drag force agrees with that of incidence turbulence in some range of the reduced frequency but disagree in the mostly reduced frequency. The spanwise root coherence of the lift force and the torsional moment is much larger than that of the incidence turbulence. The influences of the wind speed and the angle of attack are slight, and they can be ignored in the wind tunnel test. The spanwise coherence function often involves several narrow peaks due to the signature turbulence effect in the high reduced frequency zone. The spanwise coherence function is related to the spanwise separation distance and the spanwise integral length scales, and the signature turbulence effect is related to the deck-width-related reduced frequency.

• 한국미생물·생명공학회지
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• 제47권1호
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• pp.54-63
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• 2019

Rubus coreanus Miquel (RCM), also known as Korean blackberry or bokbunja, is used as a South Korean traditional medicine to treat acne and inflammatory skin conditions. The antimicrobial activity of RCM root and its active compounds remain unclear. In this study, we prepared a 50% ethanol fraction, ethyl acetate fraction, and acid-treated ethyl acetate fraction (aglycone fraction) of RCM root, and evaluated antibacterial activities against the skin pathogens Staphylococcus aureus, Pseudomonas acnes, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa. In a paper disc assay, all fractions of RCM root showed antimicrobial activities against the five skin pathogens. The ethyl acetate fraction displayed 6-, 12-, and 2-fold higher minimal inhibitory concentration (MIC) than the 50% ethanol fraction against S. aureus, E. coli, and P. acnes, respectively. The aglycone fraction displayed 2-fold higher MIC than methyl paraben against P. acnes, S. aureus, E. coli, and P. aeruginosa. The ethyl acetate fraction displayed a minimal bactericidal concentration (MBC) similar to that of methyl paraben, and the aglycone fraction showed 2- to 4-fold higher MBCs than those of methyl paraben. In particular, the ethyl acetate fraction was not cytotoxic and showed thermal stability after incubation at high temperatures ($60-121^{\circ}C$). Finally, the ethyl acetate fraction was separated and four components were identified: procyanidin C, propelagonidin dimer, ellagic acid, and methyl ellagic acid acetyl pentose. The compounds showed high antibacterial activities. These results suggest that RCM root is potentially applicable as a natural preservative in cosmetics.

• 생약학회지
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• 제30권1호
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• pp.48-53
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• 1999

Isolation and quantitative determination of costunolide from Saussurea lappa Clarke (Compositae) has been conducted by using HPLC method. Costunolide in an acetone extract from the crude drug was separated on a RP-18 column using a $MeOH-H_20$ mixture (65:35) as an eluent and the average content is about $1.32{\sim1.42%.$ The content of costunolide in dried extract was decreased by about 24% in seven days. However it showed a slight decrease in solution. It is highly recommended that quantitative determination of costunolide from Saussureae Radix should be conducted as early as possible after solvent extraction.

• Journal of Microbiology and Biotechnology
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• 제14권1호
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• pp.220-223
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• 2004

Club root caused by Plasmodiophora brassicae is found in crucifers. Among the over hundreds of Streptomyces isolated from soil in Korea. One strain showed prominent activity against P. brassicae. The strain was identified based on 16S rDNA sequencing and the morphology by a method of scanning electron microscopy. An active compound in the fermented broth obtained from the strain was separated. Even though the complete assignments of the compound remain for future work, the results regarding the isolation and characterization of the strain with a certain activity against P. brassicae are shown in this paper.

• 설비공학논문집
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• 제22권7호
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• pp.468-473
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• 2010

This paper deals with approximate integral solutions to the one-dimensional model describing the charging process of stratified thermal storage tanks. Temperature is assumed to be the form of Fermi-Dirac distribution function, which can be separated to two sets of cubic polynomials for each hot and cold side of thermal boundary layers. Proposed approximate integral solutions are compared to the previous works of the approximate analytic solutions and show reasonable agreement. The approach, however, has benefits in mathematical difficulties, complicated solution form and unstable convergence of series solution founded in the previous analytic solutions. Solutions for a semi-infinite region, which have simple closed form solutions, give close agreement to those for a finite region. Thermocline thickness is obtained in closed form and shows proportional behavior to the square root of time and inverse proportional behavior to the square root of flow rate.

• 대한치과의사협회지
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• 제4권1호
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• pp.41-43
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• 1963

A rare case of a fused teeth on the side of upper left third molar was observed from a 28 years old Korean male. The characteristics were as follows: 1)The upper third molar fusrd with the suppernumerary tooth .2)The crown part of the fused teeth were separated and the root were fused. 3)On the x-ray finding. the pulp chamber was two , but it had only one pulp canal.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.330-335
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• 1996

The well-conditioned observer design method is extended for two-output systems where observer gains are not determined uniquely with respect to the desired observer poles. Similar to the previous results, this design method makes off-diagonal elements of the observer upper-left submatrix skew-symmetric and simulataneously, places the eigenvalues of the observer matrix widely separated by selecting upper two rows of the observer gain. The proposed design method is evaluated in a spindle-drive example where the load speed is estimated based on motor speed and the armature current.

• 대한소아치과학회지
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• 제46권4호
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• pp.400-408
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• 2019

이 연구는 3세부터 7세사이의 소아를 대상으로 촬영하여 획득한 Computed tomography (CT) 영상을 이용하여 유구치 근관의 개수, 위치를 평가하고 유구치 근관들의 관계 및 치근과 근관의 관계를 분석하여 유치 근관 치료시 참고자료로 활용하고자 하였다. 남아 81명, 여아 33명, 총 114명의 CT 시상면, 수평면 영상에서 유구치 근관의 개수와 위치, 치근의 개수와 위치에 대해 평가하였고 수집된 자료를 통계분석 하여 한 환자에게서 양측에 같은 위치의 치아에 나타나는 근관의 대칭성을 평가하였다. 상악 제 1유구치와 제 2유구치에 가장 많이 관찰 되었던 근관의 개수는 3개로 위치는 근심 협측, 원심 협측, 구개 근관이었다. 하악제 1유구치 제 2유구치에 가장 많이 관찰되었던 근관의 개수는 4개로 위치는 근심 협측, 근심 설측, 원심 협측, 원심 설측 근관이었다. 상악의 치근은 근심 협측 근관을 제외하고 1개의 근관을 가지려는 경향을 가지고 있었고, 하악의 치근은 2개의 근관을 가지려는 경향을 보였다. 특히 하악 제 2유구치의 근심 치근은 100%으로 2개의 근관을 가졌다. 상악 유구치의 구개측 치근과 하악 유구치의 원심 치근이 2개의 치근으로 나누어져 있는 경우, 그 치근들은 각각 1개의 근관을 가지려는 경향을 보였다. 상악 유구치에서 원심 협측 치근과 구개측 치근이 융합되어 있더라도, 치근은 각각의 근관을 가지려는 경향을 보였다. 같은 환자의 같은 위치의 반대편 치아의 근관의 대칭성은 하악 유구치부에서 상악 유구치보다 더 높게 나타났다. 이 연구를 통해 소아 환자의 유구치 근관에 대한 이해도를 높이고, 유구치 근관 치료 시 근관의 위치에 대해 미리 예측함으로 술식 시간을 줄이고 치료의 완성도를 높이는데 도움이 될 것으로 사료된다.

• 한국식물병리학회지
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• 제13권1호
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• pp.37-45
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• 1997

Disease incidence (DI), pre-emergence damping-off (PDO), days until the first symptom appeared (DUS), disease progress curve (DPC), and area under disease progress curve (AUDPC) were investigated in vivo after sowing ginseng seeds in each of 37 ginseng-cultivated soils which were sampled from 4 regions in Korea. Non linear fitting parameters, A, B, K and M, were estimated from the Richards' function, one of the disease progress models, by using the DI at each day from the bioassay. Inter- and intra-relationships between disease variables and stand-missing rate (SMR) in fields were investigated by using the simple correlation analysis. Disease variables of the root rot were divided into two groups: variables related to disease incidence, e.g., DI, AUDPC and A parameter, and variables related to disease progress, e.g., B, K and M parameters. DI, AUDPC, and DUS had significant correlations with SMR in ginseng fields, and then it showed that the disease development in vivo corresponded with that in fields. Soil samples could be separated into 3 and 4 groups, respectively, on the basis of the principal component 1 (PC1) and the principal component 2 (PC2), which were derived from the principal component analysis (PCA) of Richards' parameters, A, B, K and M. PC1 accounted for B, K and M parameters, and PC2 accounted for A parameter.

• Imaging Science in Dentistry
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• 제52권3호
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• pp.289-294
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• 2022

Purpose: This study aimed to evaluate the diagnostic performance of panoramic images compared to cone-beam computed tomography (CBCT) imaging for maxillary third molar (M3)-associated external root resorption (ERR), and to identify the risk factors of ERR on panoramic images. Materials and Methods: The study population was composed of all patients who underwent panoramic imaging at Dankook University Dental Hospital from May to October 2019. In total, 397 cases of maxillary M3s in 247 patients(147 men and 100 women) were included. The diagnostic accuracy of ERR in panoramic images compared to CBCT images was evaluated using the chi-square test. To identify risk factors for ERR, dental records and panoramic findings were evaluated by logistic regression analysis. Results: The diagnostic accuracy of ERR on panoramic images was 0.79 compared to CBCT images (P<0.05). Superimposition of M3s onto second molars (M2) was associated with an approximately 33 times higher risk of ERR than separated M3s(P<0.05). Impacted M3s showed a 5 times higher risk of ERR than erupted M3s(P<0.05). Conclusion: ERR related to M3s is a common clinical condition, and superimposition of M3 onto M2 on panoramic images was the most important risk factor for ERR. It seemed that CBCT examinations for maxillary M3s might be indicated for ERR diagnosis especially if panoramic radiographs show superimposition of M3 onto M2. Impaction itself was also a risk factor, and it should be carefully examined.