• Polymer(Korea)
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• v.26 no.4
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• pp.535-542
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• 2002

We have prepared the surfactant-free nanoparticles of poly(DL-lactide-co-glycolide) (PLGA) by dialysis method and their physicochemical properties such as particle size and drug contents were investigated against various solvent. The size of PLGA nanoparticles prepared by using dimethylacetamide (DMAc), dimethylformamide (DMF), and dimethylsulfoxide (DMSO) was smaller than that from acetone. Also, the order of drug contents was DMAc>DMF>DMSO=acetone. These phenomena could be expected from the fact that solvent affects the size of nanoparticles and drug contents. The PLGA nanoparticles have a good spherical shapes as observed from scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Also, surfactant-free nanoparticles entrapping norfloxacin (NFx) have a good drug loading capacity without free-drug on the surface of nanoparticles confirmed by the analysis of X-ray powder diffraction. Release kinetics of NFx used as a model drug was governed not only by drug contents but also by particle size. Also, the biodegradation rate of PLGA nanoparticles prepared from DMF was faster than that prepared from acetone, indicating that the biodegradation of PLGA nanoparticles is size-dependent.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.3
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• pp.592-599
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• 2007

The advancement of wireless technology improves the electronic learning by combining with the mobile function, and promotes the expanded transition to the mobile learning. Basically, the mobile learning provides the usefulness in terms of tile and space to provide learners with the access to the educational contents. However, the small display device and limited memory space of mobile device is limiting the access to the learning contents simply to the text-based transmission. This paper designed and implemented the multimedia mobile learning system that reduces the size of parser by define into MSMIL composed only of needed tag to multimedia contents production in the mobile devices by using the SMIL that supports the multimedia object synchronization reduces the data of multimedia learning data and enhances the transmission efficiency by applying the macro method in creating the contents of learning. The results of implementation indicates that it simplifies the designing language, makes the language learning easy, and saves the CPU resources for the parsing by reducing the size of parser.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.6
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• pp.1073-1080
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• 2023

The development and speed improvement of the Internet network, and the development of many platforms based on it, have brought about a rapid expansion of production and consumption of various contents. However, the existing IP-based Internet system cannot efficiently cope with such an urgent increase in data. Accordingly, an alternative called the CCN(Contents Centric Network) has emerged, enabling more efficient data transmission and reception centered on content rather than host. In this paper, we will deal with the mobility of intermediate nodes in CCN real-time streaming service, which is one of the major research fields of CCN, and minimize network overload through more efficient path switching through RSSI detection. In other words, by improving the method of selecting and switching a spare path when an intermediate node located between the requester(consumer) and the provider moves, a mechanism for managing data transmission is not interrupted and unnecessary load due to route switching does not occur in the network.

• Journal of the Korean Society of Costume
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• v.52 no.7
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• pp.71-85
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• 2002

The purpose of this study is (1) to research on the diverse evaluation criteria suggested in the existing literatures, selected the contents of the evaluation according to the evaluation factors, and examined whether they are appropriate for the evaluation of websites that offer Clothing and Ornament related information through reliability analysis - all to set the evaluation criteria for the websites that acquire data. In addition. (2) contents of evaluation which are deemed important by the users and developers were compared and recommended as the detailed evaluation contents according to evaluation factors. The results of this study were as follows. 1. The evaluation factors for the fashion websites that provide Clothing and Ornament related information were selected as follows: contents of the information(11 contents of evaluation), ease of use(12), screen design(10), accessibility(9), sensitive enjoyment(4), scope of information use(3), purpose(1), and target user(1). As result of reliability analysis. Cronbach's a contents of the information (0.76), ease of use (0.77), screen design (0.85), accessibility (0.81), sensitive enjoyment (0.71), and scope of information use (0.52). 2. When the level of importance for the detailed evaluation contents was examined from the user and developer point of view, recency of information. rapid speed for the websites access. fast loading of webtext and fast transmission speed topped the list as first, second and third places.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2012.07a
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• pp.466-467
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• 2012

DMB 는 이동 중에 멀티미디어를 시청할 수 있는 이동 멀티미디어 방송이다. 기술의 발전으로 최근 출시되고 있는 휴대용 기기에는 기본적으로 DMB 를 수신할 수 있고, 사용자는 어디든 이동 하며 DMB Contents 를 즐길 수 있다. 하지만 사용자가 DMB Contents 를 수신할 수 없는 지역으로 이동하면 DMB Contents 를 수신 할 수 없다. 이러한 단점을 극복하기 위해서, 휴대용 기기는 기본적으로 장착되어 있는 무선 네트워크 모듈을 통하여 Internet 의 DMB System 에 접속하고, DMB System 은 사용자 요구에 따라 DMB Contents 를 전송할 수 있는 Hybrid DMB System 이 필요하다. 이러한 Hybrid DMB System 은 Internet 을 통하여 DMB Contents 를 전송하게 되고, 결국 휴대용 기기는 장착되어 있는 무선 네트워크를 이용하여 DMB Contents 를 수신한다. 하지만 휴대용 기기에 장착되어 있는 무선 네트워크 모듈이 다양하기 때문에, 각 무선 네트워크의 전송 특성을 살펴볼 필요가 있다. 본 논문에서는 다양한 무선 네트워크 중 802.11 에서 DMB Contents 를 전송하고, 네트워크의 전송 특성을 살펴본다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.8
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• pp.744-751
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• 2003

Co-Pd alloy thin films prepared by a DC-sputter that have self-organized nano structure(SONS), are promising for high-density information storage media in information era. We prepared the samples by varying Pd contents of 0~8.1 wt% at the substrate temperatures of room temperature (RT) and 200 $^{\circ}C$, respectively Microstructure and Pd contents of the Co$_{1-x}$ Pd$_{x}$ films are probed by a scanning electron microscope (SEM), a transmission electron microscope (TEM) and an energy dispersive spectrometer (EDS). We also investigated the saturation magnetization (Ms), remanence and coercivity of the Co$_{1-x}$ Pd$_{x}$ films. Surface roughness are measured by an atomic force microscope (AFM). We revealed that self-organized nano size Co-enriched phase and Pd-enriched phase existed with Pd contents at the substrate temperatures of RT and 20$0^{\circ}C$ through microstructure characterization. SONS helped to keep the saturation magnetization and enhance the perpendicular anisotropy with Pd contents. Out result implies that we may tune the perpendicular magnetic properties with keeping the saturation magnetization by varying substrate temperatures and Pd contents for high density magnetic recording.rding.

• Journal of Digital Contents Society
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• v.9 no.4
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• pp.725-733
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• 2008

CDN(Content Delivery Network) has been used as contents transmission network for transmitting high capacity contents fastly and stably. Main goals of CDN are efficient distribution and management high capacity contents. Current CDN distributes contents by managing contents based on basic metadata created by contents provider. However, existing CDN management system doesn't provide a method for applying additional metadata in content itself that is necessary for efficient contents management and distribution. Since the existing system can not annotate additional information in metadata about contents itself, and can not search contents that user wants. This paper proposes a method for applying additional metadata in existing CDN and implemented it as contents metadata management system(CMMS). A user can search needed contents effectively via CMMS. Also, the searched result can help selecting and managing contents to distribute in CDN.

• The Journal of the Convergence on Culture Technology
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• v.4 no.1
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• pp.285-290
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• 2018

Vehicular ad hoc network (VANET) is one of the future communication technologies in which it offers safe-driving information and Internet access for both drivers and passengers by communicating among cars on the road. In case of applying Content Centric Network (CCN) rather than TCP/IP over VANET, called VCCN, it can provide efficient multicast communication of shared information among participating cars as well as offer corresponding one-to-one communications. This paper introduces SUMO for simulating traffic flows, VANET for car-to-car ad hoc communications, and CCN for a future Internet architecture. In addition, it compares and analyses the transmission performance of moving cars over VCCN. According to the simulation results using SUMO and VCCN, the larger the packet size, the better the transmission performance. In addition, VCCN provides higher packet transmission rate than that of TCP/IP when the clients shares the same contents. Furthermore, the overall data reception rate exceeds the physical transmission channel rate.

• Smart Media Journal
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• v.4 no.3
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• pp.38-43
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• 2015

The increased number of smart devices leads users to share multimedia contents with others. Smart device users transmit multimedia files using apps. For multimedia file transfer under NAT (Network Address Translator), a lot of apps exploit a server with public IP or short range communication technologies such as WiFi Direct or Bluetooth because smart devices with private IP address cannot communicate each other directly. We first proposed the push service based file transmission scheme without an additional server and distance limitation. Second, for the push service based transmission, we proposed congestion control scheme to adapt transmission rate to the receiver's link bandwidth. Third, we considered bandwidth aware transmission for senders with different bandwidth. We implemented apps to evaluate the proposed scheme, and conducted experiments with smart devices.

• Journal of Korea Society of Industrial Information Systems
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• v.12 no.1
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• pp.54-60
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• 2007

The Digital Multimedia Broadcasting(DMB) system is developed to offer high quality multimedia content to the mobile environment. The system adopts the MPEG-4 standard for the main video, audio and other media format. For providing interactive contents, it also adopts the MPEG-4 scene description that refers to the spatio-temporal specifications and behaviors of individual objects. With more interactive contents, the scene description also needs higher bitrate. However, the bandwidth for allocating meta data, such as scene description is restrictive in the mobile environment. On one hand, the DMB terminal renders each media stream according to the scene description. Thus the binary format for scene(BIFS) stream corresponding to the scene description should be decoded and parsed in advance when presenting media data. With this reasoning, the transmission delay of the BIFS stream would cause the delay in transmitting whole audio-visual scene presentations, although the audio or video streams are encoded in very low bitrate. This paper presents the effective optimization technique in adapting the BIFS stream into the expected bitrate without any waste in bandwidth and avoiding transmission delays inthe initial scene description for interactive DMB content.