• Structural Engineering and Mechanics
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• 제32권5호
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• pp.635-648
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• 2009

This paper describes fire performance of eight axially restrained reinforced concrete (RC) columns under a combination of two different load ratios and two different axial restraint ratios. The eight RC columns were all concentrically loaded and subjected to ISO834 standard fire on all sides. Axial restraints were imposed at the top of the columns to simulate the restraining effect of the rest of the whole frame. The axial restraint was effective when the column was expanding as well as contracting. As the results of the experiments have shown, the stiffness of the axial restraint and load level play an important role in the fire behaviors of both HSC and NSC columns. It is found that (a) the maximum deformations during expanding phase were influenced mostly by load ratio and hardly by axial restraint ratio, (b) For a given load ratio, axial restraint ratio had a great impact on the development of axial deformation during contraction phase beyond the initial equilibrium state, (c) increasing the axial restraint increased the value of restraint force generated in both the NSC and HSC columns, and (d) the development of column axial force during the contracting and cooling phase followed nearly parallel trend for columns under the same load ratio.

• Journal of Power Electronics
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• 제14권1호
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• pp.30-39
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• 2014

This paper studies a new three-level pulse-width modulation (PWM) resonant converter for high input voltage and high load current applications. In order to use high frequency power MOSFETs for high input voltage applications, a three-level DC converter with two clamped diodes and a flying capacitor is adopted in the proposed circuit. For high load current applications, the secondary sides of the proposed converter are connected in parallel to reduce the size of the magnetic core and copper windings and to decrease the current rating of the rectifier diodes. In order to share the load current and reduce the switch counts, three resonant converters with the same active switches are adopted in the proposed circuit. Two transformers with a series connection in the primary side and a parallel connection in the secondary side are adopted in each converter to balance the secondary side currents. To overcome the drawback of a wide range of switching frequencies in conventional series resonant converters, the duty cycle control is adopted in the proposed circuit to achieve zero current switching (ZCS) turn-off for the rectifier diodes and zero voltage switching (ZVS) turn-on for the active switches. Finally, experimental results are provided to verify the effectiveness of the proposed converter.

• 대한치과보철학회지
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• 제8권1호
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• pp.80-84
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• 1968

Observing the morphology of the incisal edges, the time of the loss of mamelon, the decrement rate of the mamelon and the increment rate of the flat edges in the lower incisors among 576 Korean from 7 to 16 years old, the author obtained the following results; 1) The morphology of the incisal edges of the lower incisors immediately after completing eruption is as follows; The lower central incisors show that three nodule is around 65%, flat edge is around 27%, two nodule is around 7% and the central prominence of the incisal edge is 2% The lower lateral incisors show that three nodule is around 23%, flat edge is 24.5%, two nodule is 4 to 12% and the central prominence of the incisal edges around 44%. 2) The loss of mamelon may start at the age of 10. 3) The decrement rate of the mamelon beyond 12 years old is above 80% in the lower central incisors and 70% in the lower lateral incisors. 4) The increment rate of the flat edges beyond 11 years old is above 170% in the lower central incisors and 30% in the lower lateral incisors. 5) None of significant differences are found between right and left sides.

• ALGAE
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• 제22권4호
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• pp.325-331
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• 2007

Cryptoglena pigra Ehrenberg from Korea was a photosynthetic euglenoid alga, which had typical characteristics of the Euglenales. The ultrastructure examination of C. pigra revealed certain features which were distinctly photosynthetic euglenoid: one U-shaped chloroplast with thylakoid membranes; two paramylon grains appressed to both sides of the chloroplast; eyespot associated with the chloroplast but not part of it. Three flagellar roots were associated with the two basal bodies. The four-membered dorsal root arose from the dorsal body and extended anteriorly following the reservoir membrane. At the base of the reservoir the dorsal band was nucleated by the dorsal root and it ran anteriorly between the reservoir membrane and eyespot. The dorsal band was continued with the microtubules of the canal and the pellicle. The singlet dorsal microtubules at the transition level arranged into doublets by a successive linkage of the existing adjacent microtubules, and the doublets rearranged into the cytoskeletal microtubules that were continuous with four microtubules in pellicles. Finally, the sixteen ridges gave rise to the pellicular ridges. The five to six-membered ventral root extended anteriorly into a cytoplasmic pocket through the reservoir and lined a cytoplasmic pocket.

• The Journal of Korean Physical Therapy
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• 제28권2호
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• pp.119-123
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• 2016

Purpose: The purpose of this study was to determine the intra- and inter-rater reliability of muscle thickness (MT) measurements of the abductor hallucis (AbdH) in subjects with hallux valgus (HV), using ultrasonography performed at different inward pressures of approximately 0.5 kg, 1.0 kg, 1.5 kg, and 2.0 kg, with no pressure control. Methods: Thirty-two subjects with HV were recruited. The thicknesses of both sides of the AbdH were measured randomly by two different examiners for assessment of the intra- and inter-rater reliability. The measurement values were analyzed using the intra-class correlation coefficient (ICC) with a 95% confidence interval (CI). ICC (2,1) was used to determine the inter-rater reliability of MT measurements of the AbdH, while ICC (3,1) was used to assess the intra-rater reliability. Results: The results showed higher ICC values for intra-rater reliability compared to inter-rater reliability, and the value for inter-rater reliability with no pressure control (ICC=0.74 [95%CI=0.53-0.87]) was smaller compared to pressures of 0.5 kg, 1.0 kg, 1.5 kg, and 2.0 kg. Other inward pressures for intra- and inter-rater reliability also showed excellent values (ICC=0.86-0.96). Conclusion: The findings showed that maintaining consistent inward pressure is essential for reliable results in measurement of the MT of the AbdH by different examiners in a clinical setting.

• 한국재료학회지
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• 제15권5호
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• pp.285-292
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• 2005

Anti-reflection film was coated by using spherical silica nano colloids. Silica colloid sol was reserved between two inclined slide glasses by capillary force, and particles were convectively stacked to form a film onto the substrate as the water evaporates. As the sliding speed increased, the thickness of the film decreased and the wavelength at the maximum transmittance decreased. The microstructure observed by SEM showed that silica particles were nearly close packed, which enabled the calculation of the effective refractive index of the film. The film thickness was measured by proffer and calculated from the wavelength of maximum transmittance and the effective refractive index. The effective refractive index of the film could be controlled by a subtle controlling of the coating speed and by mixing two different sized silica particles. When the 100 nm and 50 m particles were mixed at 4:1-5:1 volume ratio, the maximum transmittance of $95.2\%$ for one-sided coating was obtained. This is the one that has increased by $3.8\%$ compared to bare glass substrate, and shows that $99.0\%$ of transmittance or $1.0\%$ of reflectance can be achieved by the simple process if both sides of the substrate are coated.

• 한국태양에너지학회 논문집
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• 제24권1호
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• pp.39-45
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• 2004

The thermal performance of glass evacuated tube solar collectors with finned tubes is numerically modelled with code and investigated to see the effect of toe inner tube diameter and incidence angle. The solar collector consists of a two-layered glass tube and an inner tube. Finned tubes are used as the inner tube of the collector in order to improve the performance of the solar collector. Two strip-type fins are attached on the opposite sides of the inner tube surface. The fin is wide enough to be tightly fatted inside the glass tube. The results show that if the incidence angle is small, the effect of the tube diameters is not significant on the thermal performance and the outlet air temperature. If the incidence angle is large, however, the outlet air temperature and the performance increases as the inner tube diameter increases.

• Progress in Superconductivity
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• 제4권2호
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• pp.172-175
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• 2003

Critical current ratio and n-value of Bi(2223)/Ag superconducting joint tape were measured as a function of uniaxial pressure. In the superconducting joint method, MM and MSM joint were used ; MM joint is direct connection of two -multi filamentary tapes, and MSM is connection of them by using a single -filamentary tape. It was observed that the critical current ratio(CCR) for jointed tapes was not dependent on the uniaxial pressure but joining methods. The n-value of jointed tapes has similar trends with that of the CCR. Especially, double MSM joint showed the highest electrical properties as 63.4-76.0%(CCR) and 3.5-5.1 (n-value). It is considered that the improvements are due to the better inter connections of multifilaments by two single filamentary tapes on both sides.

• 한국IT서비스학회지
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• 제12권3호
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• pp.39-54
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• 2013

IT consulting is becoming a norm rather than exception in this age of smart work and information revolution. As IT consulting is one of the knowledge intensive services requiring high credence on both sides, maintaining a good trustful relationship is critical in sustenance of strategic partnership between business firms and IT service firms. Trust is known to be one of the salient constructs in service relationships. In this study, building from the social psychology literature, trust is conceptualized as two dimensions : cognitive and affective trust. Using two dimensions of trust as mediators, a research model is constructed for IT consulting specific context : relationship continuance intention as the dependent construct while expertise, service performance, reputation, relationship satisfaction and value similarity as antecedents of cognitive and affective trust. 145 data points were collected through a survey of IT service client project managers retrospectively asking their experience with IT consultants. Findings suggest that cognitive trust is associated with perceived level of expertise and service performance while affective trust with relationship satisfaction and value similarity, respectively. Interestingly, the paths from reputation are found to be statistically insignificant towards both dimensions of trust, indicating IT service context would be more practically outcome oriented than any other professional service context. Also, cognitive trust seems to maintain stronger influence on relationship continuance intention as anticipated. Implications and limitations are discussed at the end.

• 한국철도학회논문집
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• 제12권6호
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• pp.1011-1017
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• 2009

남북철도 연계를 위해서는 남한과 북한 공히 균형 있는 철도시스템을 구축하여 효율적인 한반도철도망을 구성하는 것이 중요하다. 하지만 남한과 북한이 서로 다른 건설기준을 가지고 있어 남북철도 현대화의 걸림돌로 작용하고 있다. 이를 해결하기 위해서는 남북한 철도건설기준에 대한 상호비교가 필요하다. 본 연구에서는 남북한 철도건설기술 관련 법령을 조사하였고, 특히 남북한의 상이한 철도시스템, 특히 철도시설분야 즉, 궤도, 철도구조물, 전력, 신호분야를 중심으로 한 남북한 철도시스템의 비교분석을 수행하였다. 본 연구결과는 향후 북한 철도의 기존선 개량 및 신선 건설에 활용될 수 있을 것이다.