• Journal of Digital Convergence
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• v.11 no.11
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• pp.675-682
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• 2013

This paper tries to solve the problems which previous methods have the model using smart card for protecting digital contents. This study provides a contents distribution model to protect the rights of author, distributor, and user as well as user's information by using technologies such as cryptography, DRM(Digital Right Management), access control, etc. The proposed system is evaluated as the most safety model compared with previous methods because it not only solves the problems which the previous methods have, but also protects four type of risks such as use of contents which other mobile devices download, the attack on the key to decode the message, the attack on leaking the contents, and the internal attack such as an illegal reproduction.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.9
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• pp.683-694
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• 2008

The performance and durability of Polymer Electrolyte Fuel Cells (PEFCs) are strongly influenced by the uniformity of current density, temperature, species distributions inside a cell In order to obtain uniform distributions in them, the optimal design of flowfield must be a key factor. In this paper, the numerical study of land/channel flowfield optimizations is performed, using a multi-dimensional, multi-phase, non-isothermal PEFC model. Numerical simulations reveal more uniform current density and HFR(High Frequency Resistance) distributions and thus better PEFC performance with narrower land/channel width where the less severe oxygen depletion effect near the land region and more uniform contact resistance variation along the in-plane direction are achieved. The present study elucidates detailed effects of land/channel width and assist in identifying optimal flow-field design strategies for the operation of PEFCs.

• Korean Journal of Optics and Photonics
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• v.24 no.4
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• pp.159-167
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• 2013

The liquid crystal(LC) display is the most promising technology of the flat panel displays covering all applications from small mobile to large television applications. To understand the operating principles and improve the performances of the various LC displays, one should grasp the anisotropic nature of the LC and the propagation of light in the anisotropic media. Basic formulas governing the distribution of the LC molecules, directly related to the electro-optic effects of the LC devices, are described in view of the macroscopic interaction. Based on the matrix representation, the polarization analysis for the LC devices is also presented.

• Journal of the Korea Society of Computer and Information
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• v.22 no.6
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• pp.17-24
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• 2017

In recent digital broadcasting, up to 250 channels are multiplexed and transmitted. The channel transmission is made in the form of MPEG-2 Transport Stream (TS) and transmits one channel (Video, Audio). In order to check if many broadcast channels are transmitted normally, in multi-channel multi-view system, ability of real-time monitoring is required. In order to monitor efficient multi-channel, a distributed system in which functions and load are distributed should be implemented. In the past, we used an inefficient system that gave all of the functionality to a piece of hardware, which limited the channel acceptance and required a lot of resources. In this paper, we implemented a distributed multi-view system which can reduce resources and monitor them economically through efficient function and load balancing. It is able to implement efficient system by taking charge of decoding, resizing and encoding function in specific server and viewer function in separate server. Through this system, the system was stabilized, the investment cost was reduced by 19.7%, and the wall monitor area was reduced by 52.6%. Experimental results show that efficient real-time channel monitoring for multi-channel digital broadcasting is possible.

• Journal of Digital Contents Society
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• v.18 no.2
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• pp.357-363
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• 2017

The Linux operating system, considered to be a subset of the UNIX operating system, is becoming the backbone of the enterprise server market and is seen as the key to building cloud computing and big data infrastructures. Linux has a variety of Linux distributions due to the fact that the source is open and anyone can freely modify and distribute it. First of all, Linux dominated the server market, the emergence of various distributions dominates the desktop and mobile operating system markets. In this paper, we examine the birth and history of Linux and classify and characterize various Linux distributions. The emergence of various Linux distributions will play a pivotal role in the Internet of Things and will further expand their power.

• Journal of Industrial Convergence
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• v.18 no.5
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• pp.36-41
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• 2020

This paper aims to explore and shed light on how the rise of streaming services has been affecting the media landscape in the recent years by looking at the conflicts between the Hollywood film industry and Netflix. It especially examines Netflix's disregard for the theatrical release, as it is the most portentous issue that could reshape the film industry, and Hollywood's opposition to it as revealed through the 2019 Academy Awards where the issue was brought into sharp relief. At the same time, this paper also questions whether theatrical distribution makes a film any more cinematic by examining how Hollywood film production has been largely concentrated on tentpoles and franchises, while Netflix has been producing diverse films often shunned by the studios. In this light, it concludes the changes wrought by Netflix, including its bypassing of the theatrical release, are not likely to be reversed.

• Journal of Hydrogen and New Energy
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• v.27 no.1
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• pp.29-35
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• 2016

It is important to uniformly supply the fuel gas into the reaction activity area in polymer electrolyte membrane fuel cell (PEMFC). Recent studies have shown that the cell performance can be significantly improved by employing metal foam gas distributor as compared with the conventional bipolar plate types. The metal foam gas distributor has been reported to be more efficient to fuel transport. In this study, three-dimensional computational fluid dynamics (CFD) simulations have been performed to examine the effects of metal foam flow field design on the fuel supply to the reaction site. Darcy's law is used for the flow in the porous media. By solving additional advection equation for fluid particle trajectory, the gas transport has been visualized and examined for various geometrical configuration of metal foam gas distributor.

• Journal of Environmental Science International
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• v.16 no.6
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• pp.751-761
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• 2007

This study is carried out through ecological situation of native Bupleurum latissimum habitats and the research of environmental conditions for conservation of native sites, restoration of alternative habitats and preliminary data for application of useful medicinal plant. Native Bupleurum latissimum habitats were distributed on lower and middle part of the mountain from Altitude 54m to 185m, and the directions of slope were researched as usually northen and western slope. As a result of phytosociological research in 12 stands of native Bupleurum latissimum habitats, they were seperated to two communities(Bupleurum latissimum typical community and Bupleurum latissimum-Galium spurium community) in accordance with containable rate of the organic matter and soil hardeness. Soil condition is usually constituted as loamy sand and clay loam. Bupleurum latissimum is propagated in valuable soil conditions. Bupleurum latissimum lives with Morus bombycis, Reynoutria sachalinensis in Bupleurum latissimum typical community and Thalictrum aquilegifolium, Stellaria media, Hedera rhombea etc. is appeared with Bupleurum latissimum in Bupleurum latissimum-Galium spurium community. Especially, companion species were researched as Aster glehni, Dystaenia takeshimana and so on. The flora of vascular plants in this study is 44 families, 88genus 82species, 2 subspecies, 14 varietas, 4 forma and total 102 taxa. Plants of compositae occupied 10.78% among whole of them.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.9
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• pp.495-502
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• 2004

A rapid growth of the Internet user and rich media content cause an excessive server load and high network traffic, and thus it decreases the quality of service. A solution to this problem is to distribute the content on multiple replicated servers. However, in this circumstance, clients face additional task of selecting the best server to provide proper so${\gamma}$vice which clients request. This paper is intended to propose an adaptive server selection mechanism for a client request based on distance and server load. This will offer a fast and scalable service in response to the increase of massive and realtime multimedia content and contribute to floating a new business model of digital content service.

• Environmental Engineering Research
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• v.18 no.1
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• pp.3-8
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• 2013

Collision cell technology-inductively coupled plasma-mass spectrometry (CCT-ICP-MS) was used to measure the concentrations of approximately 19 elements associated with airborne PM2.5 samples that were collected from a roadside sampling station in Daejeon, Korea. Standard reference material (SRM 2783, air particulate on filter media) of the National Institute of Standards and Technology was used for the quality assurance of CCT-ICP-MS. The elemental concentrations were compared statistically with the certified (or recommended) values. The patterns of distribution were clearly distinguished between elements with their concentrations ranging over four orders of magnitude. If compared in terms of enrichment factors, it was found that toxic trace elements (e.g., Sb, Se, Cd, As, Zn, Pb, and Cu) of anthropogenic origin are much more enriched in PM2.5 samples of the study site. To the contrary, the results of the correlation analysis showed that PM2.5 concentrations can exhibit more enhanced correlations with the elements (e.g., Fe, K, Si, and Ti) arising from earth's crust. The findings of strong correlations between PM2.5 and the elements of crustal origin may be directly comparable with the dominant role of those species by constituting a major fraction of even PM2.5 as well as PM10 at the roadside area.