• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.5
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• pp.267-273
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• 2012

The short-range communication module was developed in this paper which is suitable for the point-to-multipoint circumstances of 40 terminals communicating frequently in about 50 meters. The media access control layer of this communication module using asynchronous time-division multiplexing provides a fast and robust performance even in the worst case of simultaneous transmission events, and low packet error rate was measured a in LOS (Line-of-sight) circumstance by adding the function of acknowledge response to media access control layer. The difference test was carried out in order to measure the performance of point-to-multipoint communication. Two communication modules are respectively measured and graphed in 10 branches to 40 branches. The communication module developed in this paper showed a faster performance than the commercial Zigbee module in the specific case presented in this paper. Especially, in over 20 branches showed wide differences of the transmission speed. This results is caused by more network overhead of Zigbee whose wider applications needs the network layer and applicaiton layer besides media access control layer. Also, the asynchronous time-division multiplexing proposed in this paper are more suitable than CSMA-CA of Zigbee module when a lot of module ought to be frequently communicated in small area.

• Journal of the Korean Society for Library and Information Science
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• v.53 no.2
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• pp.5-27
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• 2019

The purpose of this study is to analyze the media of middle school social studies 1 textbooks with the information processing model and to suggest educational information services of teacher librarians under a collaborative Instruction. For this purpose, 1,089 inquiry tasks embedded in 8 types of textbooks for middle school social studies developed under the 2015 revised curriculum were analyzed. The media as an input element was analyzed by the type and the characteristic as a processing element was analyzed by the cognitive behavior types. And the aspect of the output factor of the media utilized the multiple intelligences. As a result of the analysis, the media in the inquiry task solving process mainly consisted of visual media based on photographs and illustrations and general reading materials. The processing method of media is understanding through analysis and inference through structuring. And the output utilized speaking and writing of the language intelligence. Based on the results, it is shown that educational information services that teacher librarians could provide for inquiry activities are composed of developing curriculum map, teaching inquiry processing and skills, and designing work sheets with graphic organizer and multiple intelligences under the information processing steps.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1995.10a
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• pp.597-600
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• 1995

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.653-655
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• 2013

This paper is the study of Multiple External Storage Configuration for the Android based Set-top Box system. Because of Mobile OS, Android has limitation in media streaming, recording and playing for Set-top box function with only support external storage device Micro-SD card. In this paper, we research for the Multiple External Storage configuration for external disk drive, USB Memory, SD card. in Android System with Multi-Volume Management system implementation.

• The Korean Journal of Applied Statistics
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• v.14 no.1
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• pp.191-199
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• 2001

본 소고는 n명의 심사자가 k개의 객체를 평가하여 얻어진 불완전 순위자료에서 객체간 선호도에 있어 차이가 없다는 영가설을 검정하는 방법에 관한 연구이다. 주어진 자료에서 결측값들을 다중대체하는 방식을 제안하고 이들을 평균 p-값으로 묶는 몬테칼로방식의 임의순열 검정을 제안한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.2
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• pp.199-208
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• 2014

Code division multiple access (CDMA) is one of the promising medium access control (MAC) schemes for underwater acoustic sensor networks because of its robustness against frequency-selective fading and high frequency-reuse efficiency. As a way of performance evaluation, sea or lake experiment has been employed along with computer simulation.. In this study, we design the underwater CDMA forward-link transceiver and evaluate the feasibility aginst harsh underwater acoustic channel in water-tank first. Then, based on the water-tank experiment results, we improved the transceiver and showed the improvements in a lake experiment. A pseudo random noise code acquisition process is added for phase error correction before decoding the user data by means of a Walsh code in the receiver. Interleaving and convolutional channel coding scheme are also used for performance improvement. Experimental results show that the multiplexed data is recovered by means of demultiplexing at receivers with error-free in case of two users while with less than 15% bit error rate in case of three and four users.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.3
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• pp.325-333
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• 1998

In this paper, conventional STM(Synchronous Transfer Mode) supports another traffics by using idle channels. Proposed mobile terminals are distributed independently at the BSA(Basic Service Area). So, MAC(Medium Access Control) specified on the wireless ATM networks, which is managing statistics multiplewing functions, idle channel's ultilization is maximized and multimedia service characteristic for conventional wired networks based fixed assignment scheme(connection-oriented) and random assignment scheme(connection-oriented) improving on dynamic reservation based MAC protocol.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1998.05a
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• pp.132-137
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• 1998

In this paper, conventional STM(Synchronous Transfer Mode) supports another traffics by using idle channels Proposed mobile terminals are distributed independently at the BSA(Basic Service Area). So, MAC(Medium Access Control) specified on the wireless ATM networks, which is managing statistics multiplexing functions, idle channel's utilization is maximized and multimedia service characteristic for conventional wired networks based fixed assignment scheme(connection-oriented) and random assignment scheme(connectionless) improving on dynamic reservation based MAC protocol.

• Proceedings of the Korean Society for Cognitive Science Conference
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• 2000.05a
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• pp.31-36
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• 2000

본 연구에서는 멀티미디어 환경에서 정보 제시 유형이 정보 처리에 어떤 영향을 미치는지를 알아보고자 하였다. 초등학교 아동을 대사으로 하여 텍스트와 나래이션을 제시한 조건, 텍스트와 애니매이션을 제시한 조건, 애니매이션과 나래이션을 제시한 조건에 따라 학습정도가 어떻게 달라지는지를 알아보았다. 학습 수행 평가는 학습자료를 보여주고 즉시 검사하였고, 학습한 후 일주일이 지난 후에 지연검사를 하였다. 그 결과 두 검사 모두에서 애니매이션과 나래이션을 제시한 조건이 다른 두 조건에 비해 효율적인 학습 수행 결과를 보였다. 이러한 결과는 아동에게 있어서 단일 매체(텍스트)로 정보를 제시하는 것보다는 다중매체(텍스트, 애니매이션)로 정보를 처리할 수 있도록 제시하는 것이 학습에 효과적임을 보요준다. 또한 이러한 결과는 기존의 이중보호이론과 작용기억이론을 지지해 준다.

• Proceedings of the Korea Society for Simulation Conference
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• 2001.05a
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• pp.133-133
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• 2001

무선 근거리 지역망(Wireless LAN;WLAN) 환경에서 다중 채널을 이용하여 실시간 서비스를 제공하기 위한 매체 접근제어 계층에서의 채널의 사용 구간 할당 방법을 제안하고, 컴퓨터 모의 실험을 통하여 제한된 방식의 실시간 서비스 지원 성능과 채널의 사용 효율을 분석한다. 제안한 채널 사용 구간 할당 방안은 개선된 매체 접근 제어 프로토콜 RICH-DP (Receiver-Initiated Channel-Hopping with Dual Polling)를 바탕으로 한다. 무선 환경에서 RTS-CTS를 사용하는 프로토콜은 SRMA, MACA, MACAW, IEEE 802.11, FAMA 등이 있다. 최근에 단일 채널을 환경에서 RICH(Receiver Initiated Channel-Mopping) 프로토콜이 제안되었다. RICH는 충돌 회피를 위해서 경쟁 구간에서 충돌 감지(carrier sensing)을 사용한다. RICH는 제한된 어플케이션에 국한되는 단절이 있다. 반면에 RICH-DP는 다중 채널 환경에서 충돌 감지와 특별한 코드(spreading code) 할당 없이 일반화된 충돌 회피를 제공한다. 실시간 서비스를 이용하자 차는 단말들로 하여금 RICH-DP를 사용하여 서비스를 제공할 때, 대역폭에 대한 정보를 AP(Access Point)로 전송토록 함으로써 비경쟁 구간에서 뿐 아니라, 경쟁구간에서도 높은 채널 효율이 얻어질 수 있도록 하고 있다. 제한된 방안의 성능 평가를 위한 모의 실험은 OPNET를 이용하여 실시간 서비스 데이터를 7개의 상태 천이를 갖는 VBR 소스로 모델링하고 비동기 트래픽들은 Poisson 소스로 모델링하여 실시간 서비스 단발들의 이용 대역폭과 채널 처리율과 시스템 지연시간을 성능 평가 인자로 하여 수행하였다. 논문에서 제한된 방법을 적용한 개선된 RICH-DP을 모의 실험을 통하여 분석한 결과 기존의 제한된 RICH-DP는 실시간 서비스에 대한 처리율이 낮아지며 서비스 시간이 보장되지 못했다. 따라서 실시간 서비스에 대한 새로운 제안된 기법을 제안하고 성능 평가한 결과 기존의 RICH-DP보다 성능이 향상됨을 확인 할 수 있었다.