• Journal of KIISE:Computing Practices and Letters
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• v.9 no.1
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• pp.77-85
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• 2003

The conversion into a new Local Area Network (LAN) environment without clear analysis of the problems with the conventional LAN environment nay bring about some improvement of performance, but in general, the result would not be as good as expected. Besides, in case new traffic or application programs are added In the near future, traffic overload similar to the past may incur. Therefore, the conversion into a new LAN environment should not only relieve the problems with the conventional environment but also be able to cope with future expansion of the network flexibly. In the present paper, in view of the above, the problems with protocols and traffic that may occur in the Bus-structured 10/100 Mbps shared Ethernet that has been widely used by many institutions are reviewed, and as a case study whether such conversion into a new LAN environment in order to increase the efficiency in the operation, management, and utilization of the network would be proper for the actual operational environment is implemented, and the results are analyzed.

• Journal of Korea Society of Digital Industry and Information Management
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• v.14 no.1
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• pp.45-55
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• 2018

Recently, because the arrival of the fourth industrial revolution era, many information and telecommunication services have grown rapidly in the mobile business market. So, companies are based Mobile Apps on user customized services and expanding their services. From the standpoint of the business, to generate revenue, the company needs to maintain the existing current computer environment and develop Mobile Apps to offer convenience in various areas such as finance, admiration, e-commerce and sales support. However, as the number of users increase due to expansion of various Mobile services, security threats that are related to Mobile Apps are increasing and its damage is also increasing. Due to the rapid technological transformation of Mobile devices using the Internet, the level of security threats to Smartphones are rising and getting more advance, so this thesis is structured as follows. In Chapter 2, it will look at the overall trends of Mobile Apps as related research. In Chapter 3, it will discuss various security concerns that related to the latest Mobile Apps and learn about the threatening factors. In Chapter 4, it will compare and analyze the threatening factors. Then it will find and suggest the possible plan. In Chapter 5, it will end with conclusion. Finally, to protect mobile devices from security threats, the environment of operating system which manages the resources and data of Apps needs to be protected. Also, it is important that users to have awareness and check activation FinTech technology security in the process of simple payment with fingerprint or IC card.

• Journal of Korea Foundry Society
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• v.33 no.4
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• pp.157-161
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• 2013

A ribbon-type polycrystalline silicon wafer was directly fabricated from liquid silicon via a novel technique for both a fast growth rate and large grain size by exploiting gas pressure. Effects of processing parameters such as moving speed of a dummy bar and the length of the solidification zone on continuous casting of the silicon wafer were investigated. Silicon melt extruded from the growth region in the case of a solidification zone with a length of 1cm due to incomplete solidification. In case of a solidification zone wieh a length of 2 cm, on the other hand, continuous casting of the wafer was impossible due to the volume expansion of silicon derived from the liquid-solid transformation in solidification zone. Consequently, the optimal length of the solidification zone was 1.5 cm for maintaining the position of the solid-liquid interface in the solidification zone. The silicon wafer could be continuously casted when the moving speed of the dummy bar was 6 cm/min, but liquid silicon extruded from the growth region without solidification when the moving speed of the dummy bar was ${\geq}$ 9 cm/min. This was due to a shift of the position of the solid-liquid interface from the solidification zone to the moving area. The present study reports experimental findings on a new direct growth system for obtaining silicon wafers with both high quality and productivity, as a candidate for an alternate route for the fabrication of ribbon-type silicon wafers.

• Journal of the Earthquake Engineering Society of Korea
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• v.1 no.4
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• pp.59-68
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• 1997

In analysis of underground structures, the effects of artificial boundary conditions are considered as one of the major reasons for differences from experimental results. These phenomena can be overcome by using the boundary elements which satisfy the multi-layered half space conditions. The fundamental solutions of multi-layered half-space for boundary element method is formulated satisfying the transmission and reflection of waves at each layer interface and radiation conditions at bottom layer. The governing equations can be obtained from the displacements at each layer which are expressed in terms of harmonic functions. All types of waves can be included using the complete response from semi-infinite integrals with respect to horizontal wavenumbers using expansion of Fourier series and Hankel transformation. Two dimensional Green's functions are derived from cylindrical Navier equations and potentials performing infinite integration in y-direction. In this case, it is effective to transform into two dimensional problem using semi-analytical integration and sinusoidal Bessel function. Some verifications are given to show the accuracy and efficiency of the developed method, and numerical examples to demonstrate the dynamic behavior of underground with various properties.

• Journal of Technologic Dentistry
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• v.39 no.1
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• pp.43-52
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• 2017

Purpose: Physical and chemical properties of gold is most suitable to be restored of teeth to its original state. Recently zirconia was used instead of gold because of esthetical and intimacy of human body. Because of high strength and high abrasion resistance of zirconia, all zirconia artificial tooth lead to wear the original tooth of opposite site. To preserve this original tooth, zirconia artificial tooth covered with dental ceramic glass was used. When joining the zirconia core and dental ceramic glass, difference of their thermal expansion coefficient and wetting ability is generated the residual stress at interface lead to crack. In order to solve this problem, intermediate layer what is called zir-liner was imported to decrease the residual stress and increase the bonding strength. Methods: In this study, to identify the optimum conditions for manufacturing process, various methods to rough the surface of zirconia core were adopted, and vary the thickness of interlayer, and analyzed bond strength. Results: Bond strength of sanding specimens group showed higher than that of non-sanding specimens group, and once applied intermediate layer with sanding specimens showed highest bond strength with 28 MPa. SEM photomicrographs of zirconia cores fired at $1500^{\circ}C$ showed parallel straight lines in sanding and pockmarked surface in blasting surfaces as abrasion traces. Observation of the destruction section after shear test by SEM were carried out. Liner applied non-sanding group and non-liner applied sanding group all showed interfacial crack. Sandblasting group with non-liner showed remained dental ceramic glass on the surface of zirconia. Sandblasting group with once applied liner showed partially remained liner and dental ceramic glass on the surface of zirconia. XRD analysis revealed that sandblasting group showed higher monoclinic peaks than other specimens group and this result was due to the high collision energy for stress induced phase transformation. Conclusions: A study on the improvement of bonding strength between zirconia and dental ceramic glass steadily carried out for the future to practical use.

• Journal of the Korean Society for Railway
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• v.19 no.2
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• pp.251-261
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• 2016

In this paper, changes of railway-related organization during the Japanese colonial period were studied indepth. The railway-related organizations were expanded from the Railway Management Bureau in 1906 (Residency-General). In 1910, this bureau changed to the General of Chosun Railway Bureau (Government-General) and the Chosun Railway Bureau (Government-General). In the 1940's, it developed into an organization called the Transport Bureau, dealing with the whole transport service. The number of employees in the railway sector increased along with the expansion of the organization and the establishment of a training institution for better recruitment. After examining the period of the construction of railway and connection system, which is deeply related to the railway organizations of the Japanese colonial period, this paper analyzes the transformation process of railway-related laws and organizations. Furthermore, this paper finds common characteristics and differences between railways in a comparison of three countries: Chosun, Japan and Taiwan.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.7
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• pp.1341-1347
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• 2007

The displacement field (Optical flow) has been calculated by bottom-up approaches based on local processing. In contrast with them, in this paper, a top-down approach based on expanding in turn from the lowest order mode the whole motion in an image pair of sequential images is proposed. The intensity of medical images usually represents a quantity which is conserved during the motion. Hence sequential images are ideally related by a coordinate transformation. The displacement field can be determined from the generalized moments of the two images. The equations which transform arbitrary generalized moments from a source image to a target image are expressed as a function of the displacement field. The appareent displacement field is then computed iteratively by a projection method which utilizes the functional derivatives of the linearized moment equations. This method is demonstrated using a pair of sequential heart images. For comparative evaluation, we applied Horn and Schunck's method, a standard multigrid method, and our proposed algorithm to sequential image.

• The Journal of the Korea Contents Association
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• v.18 no.11
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• pp.236-249
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• 2018

The purpose of this study is to examine the effects of educational activities based on oriental mythology on young children's creativity and personality. A total of 14 sessions were applied to 36 children (18 experimental group and 18 control group). For this study, myths in Shan-hai jing, The Classic of Mountains and Seas), which is the origin of oriental mythology, were used as basic data of class activities and developed to experimental groups. The collected data were analyzed using SPSS 21.0 statistical program and covariance analysis (ANCOVA) was conducted with covariance score of the group after the activity. The results of this study were as follows: First, integrated educational activities using oriental mythology had a positive effect on all children's creativity and all sub-factors. Second, integrated educational activities using Oriental mythology have a positive effect on children's personality. The expansion and transformation of educational texts to oriental mythology is not only helpful for young children's creativity and personality development, but also enables them to experience cultural balance through their new understanding of the Orient.

• The Journal of the Convergence on Culture Technology
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• v.5 no.3
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• pp.101-106
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• 2019

This paper considers the historicity and aesthetical implications of in the art world of Paul Ryan(1943-2013) who designed the aestheticization of relational circuit of society by realizing the value of social transformation being inherent in video with cultural practices and suggesting the interdisciplinary method of leaning and research in the early video art history. To do this, in Chapter II, I review the first artwork presented firstly in the art gallery exhibition "TV as a Creative Medium" in 1969, in which Ryan proposed a video medium as a communication system and experimented the concept of 'feedback' in Cybernetics. And Chapter III focuses Ryan's discursive activities contributed to magazine Radical Software and artist-collective Raindance Corporation with growing interest in communication technology. At this time, Ryan regarded video medium as the tool for cybernetic expansion. Finally Chapter IV deals with the development of ecological method based on "a shared perception of environmental realities" and verifies Ryan's vision that video medium would be most effective means of social change and communication.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.1
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• pp.53-60
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• 2018

For test on flooring board laminated with PVC decoration materials in order to replace the current surface materials such as HPL in decoration wood-based flooring board. the Results of comparison and analysis are as follows: For thermal conductivity, flooring board decorated with PVC did not show huge differences when temperature was rising and lowering compared to the flooring materials laminated with the existing HPL surface materials. It seems the most meaningful results for using it as indoor flooring materials. That is, in Korea where there is the culture focusing on ondol heating, use amount of heat energy and efficiency of flooring materials are very important and sensitive issues, involving immediately with household economy of final consumers, and it might be a criteria to judge basic performances required as flooring materials. As a result of the analysis on mandatory durability test items such as abrasion resistance, absorption width expansion rate, impact resistance, surface hardness, and impact absorption for flooring materials, compared to flooring board laminated with general HPL surface decoration materials, decoration wood-based flooring board laminated with PVC surface decoration materials which is higher abrasion resistance with smaller transformation and has better durability and impact absorption of the surface, is available for actual application as indoor flooring board, and for replacing surface decoration materials impregnated with heat-hardened resion such as HPL.