• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.1
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• pp.105-109
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• 1987

Artificial roughness as a means of improving heat transfer gains more interest, especially for application to various heat exchanger. This study present experimental information for single-phase free and force convection heat transfer in a circular tube containing a internal spiral ribs. To examine the effect of inclined angle of tube, it was varied from 0 deg to 90 deg (0.deg., 22.5.deg., 45.deg., 90.deg.) with horizontal. Length of tube is 1.6m, and width, height and helix angle of rib are 4.2mm, 1.5mm, and 60 deg respectively. Water was used as a working fluid and test piece was heated with a constant heat flux by electric heater. Experiments have been performed with the range of modified Grashof number from 2 * 10$^{6}$ to 15 * 10$^{6}$ for free convection and with the range of Reynolds number from 3,000 to 40,000 for forced convection. Since the increase in heat transfer coefficients influence directly to the friction coefficient of the tube, the changes of the friction factors are also presented for several different cases considered in this investigation.

• Journal of Life Science
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• v.34 no.2
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• pp.86-93
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• 2024

Since replication of plasmids must be strictly controlled, plasmids that generally perform rolling circle replication generally maintain a constant copy number by strictly controlling the replication initiator Rep at the transcriptional and translational levels. Plasmid pJB01 contains three orfs (copA, repB, repC or repABC) consisting of a single operon. From analysis of amino acid sequence, pJB01 CopA was homologous to the Cops, as a copy number control protein, of other plasmids. When compared with a CopG of pMV158, CopA seems to form the RHH (ribbon-helix-helix) known as a motif of generalized repressor of plasmids. The result of gel mobility shift assay (EMSA) revealed that the purified fusion CopA protein binds to the operator region of the repABC operon. To examine the functional role of CopA on transcriptional level, 3 point mutants were constructed in coding frame of copA such as CopA R16M, K26R and E50V. The repABC mRNA levels of CopA R16M, K26R and E50V mutants increased 1.84, 1.78 and 2.86 folds more than that of CopA wt, respectively. Furthermore, copy numbers owing to mutations in three copA genes also increased 1.86, 1.68 and 2.89 folds more than that of copA wt, respectively. These results suggest that CopA is the transcriptional repressor, and lowers the copy number of pJB01 by reducing repABC mRNA and then RepB, as a replication initiator.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.6
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• pp.776-787
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• 1998

This paper analyzes the local specific absorption rates (SAR's) averaged over 1 g and 10 g in a human head model in contact with a mobile phone operating at 835 MHz. The used numerical method is a total field finite-difference time-domain (FDTD) technique. The phone was simulated with a conducting box, a plastic case, and a whip antennal composed of a monopole and a helix. The discrete human model of the spatial resolution 3 mm is based on Magnetic Resonance Imaging (MRI), computerized tomography (CT) and anatomical images. The near field and far field and far field patterns were analyzed for extended and retracted phone. The two methods to take the volumes of the weights, 1 g or 10 g in tissue are proposed and compared to offer a reproductive technique for SAR estimations.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.3
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• pp.231-239
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• 2002

Experiments on the single phase cooling heat transfer and pressure drop with microfin tubes were performed using water as a test fluid. Experimental data were obtained in the range of Reynolds number 3000 ~40000 and Prandtl number 4-6. The data of microfin tubes presented the characteristics of rough surface tube in pressure drop and heat transfer Experimental data were compared with the heat transfer and friction factor correlations of smooth tubes. Heat transfer enhancements of microfin tubes were lower than pressure drop penalty factors. The helix angle is more significant parameter in both of the pressure drop and heat transfer than the relative roughness. The correlations of Nusselt number and friction factor were suggested for the tested microfin tubes. Maximum deviations between correlations and experimental data were within $\pm15$% for Nusselt number and $\pm10$% for friction factor.

• Journal of Contemporary Eastern Asia
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• v.12 no.1
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• pp.81-93
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• 2013

Over the past several decades, educational systems in many parts of the world have undergone manifold changes that have significantly affected the work environment of educators. Among other negative impacts of the globalized reforms in higher education has been the increasing prevalence of workplace bullying. The purpose of this research note is to serve different purposes: (1) examine the causes behind the changing landscape of higher education; (2) discuss previous and current research on workplace bullying; (3) introduce the methodology of the Taiwan Higher Education Faculty Survey (THEFS); (4) outline its anticipated outcome.

• Journal of Contemporary Eastern Asia
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• v.13 no.2
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• pp.3-14
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• 2014

Online communities are an important source of electronic-word-of-mouth (eWOM), however few studies have examined these types of messages within the Middle Eastern context. This study focuses on Kuwaiti women as members of an online beauty forum; previous work has suggested a mediating effect of gender with women being more likely to trust and follow-up word-of-mouth with a purchase. A conceptual model, based on existing theoretical contributions, provides the basis of a coding framework for the message characteristics that influence members' eWOM adoption. A sub-set of the analysis is presented: 218 threads (1820 messages, coded into 6702 units) illustrating cases where eWOM was adopted and thereby demonstrating continuance intention with members returning to the forum. Content analysis revealed the prevalence of emotional aspects in messages, coded into a new category of 'community bonding'. Findings show that emotion expressed in messages is as influential and important as cognitive aspects of argument quality.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.26 no.2
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• pp.257-261
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• 2017

Drilling file is medical mini-drill which is made of Ni-Ti material and has tapered shape. It's for removing teeth nervine which helps the endodontic treatment. All files, saled at domestic market, are imported from U.S. and Europe. Also they have low manufacturing efficiency and high price because it is made by universal 5 axis CNC grinding machine. To solve these problem, 3 axis CNC table, controllable tilting angle spindle and helix angle moving table are devised. To confirm divised CNC grinding machine's manufacturing accuracy, conveying amount and finish product size measurement expreiment has been practiced. Also to automate all manufacturing processes, automatic mechanism is designed.

• Genomics & Informatics
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• v.9 no.2
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• pp.79-84
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• 2011

Two initial models of cold-adapted lipase PsLip1 have been constructed, based on homology with the bacterial lipases Chromobacterium viscosum (CvLip) and Pseudomonas cepacia (PcLip), whose X-ray structures have been solved and refined to high resolution. The mature polypeptide chains of these lipases have 84% similarity. The models of Mod1 and Mod2 have been compared with the tertiary structures of CvLip and PcLip, respectively, and analyzed in terms of stabilizing interactions. Several structural aspects that are believed to contribute to protein stability have been compared: the number of conserved salt bridges, aromatic interactions, hydrogen bonds, helix capping, and disulfide bridges. The 3-dimensional structural model of PsLip1 has been constructed in order to elucidate the structural reasons for the decreased thermostability of the enzyme in comparison with its mesophilic counterparts.

• Bulletin of the Korean Chemical Society
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• v.18 no.1
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• pp.50-56
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• 1997

The mode of action of mastoparan B, an antimicrobial cationic tetradecapeptide amide isolated from the hornet Vespa basalis, toward phospholipid bilayers was studied with synthetic mastoparan B and its analogs with individual Ala instead of hydrophobic amino acids (1-Ile, 3-Leu, 6-Leu, 7-Val, 9-Trp, 13-Val, 14-Leu) in mastoparan B. Mastoparan B and its analogs were synthesized by the solid-phase method. Circular dichroism spectra showed that mastoparan B and its analogs adopted an unordered structure in buffer solution. In the presence of neutral and acidic liposomes, most of the peptides took an α-helical structure. The calcein leakage experiment indicated that mastoparan B interacted strongly with neutral and acidic lipid bilayers than its analogs. Mastoparan B also showed a more or less highly antimicrobial activity and hemolytic activity for human erythrocytes than its analogs. These results indicate that the hydrophobic face in the amphipathic α-helix of mastoparan B critically affect biological activity and helical contents.

• Journal of Contemporary Eastern Asia
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• v.17 no.2
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• pp.237-253
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• 2018

In order to understand China's internet governance, this paper examined 1,931 Internet policies of China by bibliometric techniques. Specifically, the bibliometric techniques include simple document counting, co-word analysis, collaboration network analysis and citation analysis. The findings include: (1) China's Internet legislations mainly emphasized e-commerce and Internet governance, and, to some extent, neglected personal data protection; (2) China's Internet is under intensive multiple regulatory controls by central government. A large number of government agencies are involved in Internet policy-making. The Propaganda Department of the Central Committee of the Communist Party of China and the State Information Leading Group of the State Council, enforced fewer policy documents, but occupy higher positions in the Internet governance hierarchy; (3) China's Internet legislation system is primarily composed of industry-specific administrative rules, rather than laws or administrative regulations. Nevertheless, laws and administrative regulations received significantly more citations owing to their superior force. This paper also discussed current gaps in China's internet governance and how the country's internet policies are situated in the broader global context.