• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.2
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• pp.79-83
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• 2011

Magnetic seal uses a magnetic fluid to seal a gap between a rotating shaft and housing. It is distinguished from other kinds of seals from the fact that solid contact does not occur in the seal. This implies that it is free from solid rubbing thus dustless and provides a clean circumstance. That is the reason why the magnetic seal is used exclusively for most of vacuum chambers in semiconductor process where dustless clean circumstance is critical. A magnetic seal has been developed of which design parameters are determined based on published data, and an air pressure test has been done to examine its sealing capability. Effects of some design parameters have been studied through FEM analysis. The results show some notable aspects of design parameters and provide suggestions for developing the seals. Regarding the sealing capacity of the magnetic seal the factor to match the theoretical value with the actual one was found to be 0.4~0.7, which means still there is some discrepancy between theory and actual.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.6
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• pp.233-241
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• 2005

The present model of a SF6 arc accounts for the copper vapour contamination from the electrodes inside a Laval nozzle of a circuit breaker. Steady state simulations have been done for the arc with electrode gap of 60mm and DC electric current of 500A, 1000A and 1500A for both cases with and without copper contamination. The effects of electrode polarity are considered for the arc current of 1000A. It was found out that evaporation of copper from the anode results in a cooling of the arc in a region close to the electrodes. The electrical potential across the electrodes is not sensitive to the presence of copper vapour, typically less than $4\%$ difference. Transient analysis has been done in order to obtain the arc properties at current zero. The arc current is increased linearly from -1000 to 0A when the upstream electrode is cathode with constant dI/dt of $27.0A/{\mu}s$ (or decreased linearly from 1000 to 0A when upstream electrode is anode). It has been predicted that the presence of copper vapour reduces the interruption capability of the breaker.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.5
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• pp.393-397
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• 2002

Polyimide (PI) films have been studied widely as the interlayer dielectric materials due to a low dielectric constant, low water absorption, high gap-fill and planarization capability. The polyimide film was etched using inductively coupled plasma system. The etcying characteristics such as etch rate and selectivity were evaluated at different $CF_4/(CF_4+O_2)$chemistry. The maximum etch rate was 8300 ${\AA}/min$ and the selectivity of polyimide to SiO$_2$was 5.9 at $CF_4/(CF_4+O_2)$ of 0.2. Etch profile of polyimide film with an aluminum pattern was measured by a scanning electron microscopy. The vertical profile was approximately $90^{\circ}$ at $CF_4/(CF_4+O_2)$ of 0.2. As 20% $CF_4$ were added into $O_2$ plasma from the results of the optical emission spectroscopy, the radical densities of fluorine and oxygen increased with increasing $CF_4$ concentration in $CF_4/O_2$ from 0 to 20%, resulting in the increased etch rate. The surface reaction of etched PI films was investigated using x-ray photoelectron spectroscopy.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.300-303
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• 2004

To fill the gap of films for metal-to-metal space High density plasma fluorinated silicate glass (HDP FSG) is used due to various advantages. However, FSG films can have critical drawbacks such as bonding issue of top metal at package, metal contamination, metal peel-off, and so on. These problems are generally caused by fluorine penetration out of FSG film. Hence, FSG capping layers such like SRO(Silicon Rich Oxide) are required to prevent flourine penetration. In this study, their characteristics and a capability to block fluorine penetration for various FSG capping layers are investigated through FTIR analysis. FTIR graphs of both SRO using ARC chamber and SiN show that clear Si-H bonds at $2175{\sim}2300cm^{-1}$. Thus, Si-H bond at $2175{\sim}2300cm^{-1}$ of FSG capping layers lays a key role to block fluorine penetration as well as dangling bond.

• Journal of Physiology & Pathology in Korean Medicine
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• v.29 no.3
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• pp.256-266
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• 2015

Apparently, in the field of Traditional Korean Medicine(TKM), lots of papers have been published and they have helped TKM grow quantitatively. But from the inside, there has been a lot of problems like the gap of theory and practice, doubts about necessity of basic theory, and lack of internal communication. There could be many reasons for it, but it could be considered due to the lack of ideal talent that should be goal of teaching and performing TKM. In the field of TKM, the absence of ideal talent of Korean medical doctors(KMD) and inferior social position of KMD than Medical Doctors(MD) has beeb derived from the laws promulgated in Japanese Occupation. These days, KMD should have ability for diagnosis of diseases as primary care and capability for diagnosis and treatment based on TKM theory, therefore careful study of basic theory of TKM is necessary.

• Nuclear Engineering and Technology
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• v.53 no.9
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• pp.3058-3067
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• 2021

Sodium zinc borate glasses doped with dysprosium and modified with different concentrations of barium oxide (0-50 mol %) were fabricated using the melting quenching technique. The structural properties of the prepared glass systems were characterized using XRD and FTIR methods. The absorption spectra of the prepared glasses were measured to determine their energy gap and their related optical properties. The density of the glasses and other physical parameters were also reported. Additionally, with the help of Photon Shielding and Dosimetry (PSD) software, we investigated the radiation shielding parameters of the prepared glass systems at different energy values. It was found that an increase in the density of the glasses by increasing the concentration of BaO significantly improved the gamma ray shielding ability of the samples. For practical results, a compatible irradiation set up was designed to check the shielding capability of the obtained glasses using a gamma ray source at 662 keV. The experimentally obtained results strongly agreed with the data obtained by PDS software at the same energy. These results demonstrated that the investigated glass system is a good candidate for several radiation shielding applications when comparing it with other commercial shielding glasses and concretes.

• Nuclear Engineering and Technology
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• v.53 no.10
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• pp.3379-3397
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• 2021

In this study, a multi-physics modeling method was developed to analyze a nuclear fuel rod's thermo-mechanical behavior especially for high temperature anisotropic creep deformation during ballooning and burst occurring in Loss of Coolant Accident (LOCA). Based on transient heat transfer and nonlinear mechanical analysis, the present work newly incorporated the nuclear fuel rod's special characteristics which include gap heat transfer, temperature and burnup dependent material properties, and especially for high temperature creep with material anisotropy. The proposed method was tested through various benchmark analyses and showed good agreements with analytical solutions. From the validation study with a cladding burst experiment which postulates the LOCA scenario, it was shown that the present development could predict the ballooning and burst behaviors accurately and showed the capability to predict anisotropic creep behavior during the LOCA. Moreover, in order to verify the anisotropic creep methodology proposed in this study, the comparison between modeling and experiment was made with isotropic material assumption. It was found that the present methodology with anisotropic creep could predict ballooning and burst more accurately and showed more realistic behavior of the cladding.

• Journal of Korea Trade
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• v.23 no.3
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• pp.38-51
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• 2019

Purpose - An appreciable number of small- and medium-sized exporters have continuously succeeded in their export marketplaces even though they do not possess enough resources. Advocating that affiliation with an export service-provider plays an important role in this phenomenon, we aimed to theoretically explain how export service providers' competences and relational factors drive small- and medium-sized exporters' competitive advantages in the long-run. Design/methodology - Drawing prominently on the resource-based view and the relationship-marketing theory, we built an empirically testable model. The model showed the roles of exporter capabilities, export service-provider competences, and relational factors on small- and medium-sized exporters' sustainable competitive advantages. Findings - The results of our research showed that exporter production and branding capabilities positively influenced their sustainable competitive advantage. In addition, export service-providers' marketing competence and relationship-building competence positively moderated the effects of exporter capabilities on their parties' sustainable competitive advantages. Finally, affiliation parties' interfirm trust and relationship commitment positively moderated the effects of export service-provider competence on the relationship between exporter capabilities and sustainable competitive advantages. Originality/value - Although prior studies have highlighted the effects of an exporter's resources on export performance, our research filled a knowledge gap of the effects of other resources on export performance. First, we proposed two types of export service-provider, competence marketing and relationship-building, influencing exporters' competitive advantage. Second, the effects of relational factors were proposed in the context of export affiliations.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.2
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• pp.49-61
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• 2019

As the technological gap amongst manufacturers decreases, the life cycle of products has shortened, and competition accelerates due to the development of technology, incumbent manufacturing companies face growth limitations. In order to overcome such business issues, manufacturing companies are increasingly interested in changes in business models and innovations, especially in the direction of providing services where they can maintain the competitive advantage of their products. In such context, this empirical study examines managerial leadership, differentiation strategies, and products and services pricing as 'servitization factors', which can be driving forces for moving into a new era of growth for Korean SMEs, focusing on the mediating effects of servitization competency. The results are as follows : First, it was confirmed that executive leadership, differentiation strategy, and information & communication technology capability have a direct effect on service sales. Second, the process competency, partnership competency, and ICT competency, which are presented as the service competence of SMEs, were found to play an important role in inducing service sales in managerial leadership, differentiation strategy, product and services pricing. It also emphasized the role of the public policy such as helping to foster SMEs as key partners in the expansion of social facilities and establishing platforms through ICT and data utilization for the convergence of manufacturing services.

• Journal of Korean Elementary Science Education
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• v.38 no.2
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• pp.287-304
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• 2019

Teaching with technology has been widespread in practical classroom settings, and increased the needs to enhance pre-service teachers' capability with a variety of technologies. The purpose of this study is focused on designing and implementing a training program to develop pre-service teachers' Technological Pedagogical Content Knowledge(TPACK) which promotes them use technologies tactically in integrated science classes. Based on the theoretical framework of TPACK and Practitioner's Guide to TPACK, the authors developed ten periods of lessons comprised instructional skills in elementary science education. Subsequently, the program was applied into a teacher trainee course in Korea. The results of this study indicate that the TPACK training program for pre-service teachers significantly influenced on attitude toward convergence, TPACK, and science teaching efficacy of the engaged participants. The developed program, meanwhile, caused a significant TPACK improvement of female participants of the teachers college more effectively. Furthermore, it mitigated the gap between science and humanity tracks coming from their high schools. Consequently, there are possibilities to improve pre-service teachers' teaching strategies for integrated classes, if they have opportunities to review the comprehensibility of technological, pedagogical, content knowledge, and intersected areas with metacognitive perspectives.