• ETRI Journal
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• 제29권3호
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• pp.329-335
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• 2007

This paper considers a timeslot assignment problem in an interactive satellite multimedia (ISM) system with digital video broadcast-return channel via satellite (DVB-RCS). The timeslot assignment problem is formulated as a binary integer programming to maximize the overall weighted throughput and is shown to be NP-hard. Thus, three real-time heuristic algorithms including ratio-based, packet-size (PS)-based, and transmission gain (TG)-based are derived, and some computational experiments are made. Considering the results, the ratio-based heuristic algorithm is demonstrated to be the most effective and efficient. We propose adapting the ratio-based heuristic algorithm to the timeslot assignment problem to greatly improve the ISM system utilization.

• 정보와 통신
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• 제28권8호
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• pp.10-17
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• 2011

3GPP($3^{rd}$ Generation Partnership project)는 3세대 이동통신인 UMTS(Universal Mobile Telecommunication System)의 초기 표준화 이후 HSPA(High Speed Packet Access), MBMS(Multimedia Broadcast Multicast Service) 등의 기술 개발로 UMTS시스템을 지속적으로 발전시켜 왔다. 그리고, 최근 새로운 무선 접속 기술을 기반한 LTE(Long Term Evolution)시스템에 대한 표준화를 완료하고 ITU-T(International Telecommnunications Union-Radio)의 IMT-Advanced 요구사항을 만족하는 LTE-Advanced 시스템에 대한 연구를 진행하고 있다. 한편 LTE-Advanced 표준의 목표인 무선 전송속도를 한층 더 높이고, 단위비용(cost per bit)을 더욱 낮추고, 셀 커버리지 및 용량을 확대하기 한 저출력의 피코셀, 펨토셀, 무선중계기들을 이용하여 실내외의 소규모 영역을 서비스하도록 하는 heterogeneous network에 대한 국제 표준이 활발히 논의되고 있다. 그러나 여러 셀이 혼재하는 경우 셀들간의 신호 간섭이 발생하여 사용자의 통신 품질이 크게 저하될 우려가 있다. 본 고에서는 heterogeneous network 와 관련하여 국제 표준 LTE-Advanced에서 논의되고 있는 간섭 제어 기법에 대해 소개한다.

• 한국항공운항학회지
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• 제18권4호
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• pp.100-105
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• 2010

This study is to analyze the performance for ADS-B(Automatic Dependent Surveillance-Broadcast) operations by the Balanced Scorecard(BSC). It is also to collect the opinions of users(pilots, air traffic controllers and ground operators) relating ADS-B and to use the results as data about preparing political measures of aviation safety. For these purpose, BSC model redesigned on 4 different points of view is used for measuring the performance of the ADS-B operation. The proposed perspectives are affairs effectiveness, user orientation, system orientation and the capacity. As the results of this study, it is showed that the continuous development of ADS-B should be required and the users must be involved in the activities, additionally, the relevant authorities should try to be drawn the user-oriented results through the process.

• 한국통신학회논문지
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• 제33권8B호
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• pp.657-666
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• 2008

The intersection collision avoidance service among various telematics application services is regarded as one of the most critical services with regard to safety. In such safety applications, real-time, correct transmission of service is required. In this paper, we study on efficient infrastructure architecture for intersection collision avoidance using a cooperative mechanism between vehicles and wireless infrastructure. In particular, we propose an infrastructure, called CISN (Cooperative Infrastructure associated with Sensor Networks), in which proper numbers of sensor nodes are deployed on each road, surrounding the intersection. In the proposed architecture, overall service performance is influenced by various parameters consisting of the infrastructure, such as the number of deployed sensor nodes, radio range and broadcast interval of base station, and so on. In order to test the feasibility of the CISN model in advance, and to evaluate the correctness and real-time transmission ability, an intersection sensor deployment simulator is developed. Through various simulations on several environments, we identify optimal points of some critical parameters to build the most desirable CISN.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1835-1837
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• 2001

The interference of electromagnetic waves in factory is increasing according with development of industrial society and many use of electrical machinery. Electromagnetic wave is defined as the electrical and magnetic field formed by electrical and electronic equipment used in daily lives, which indiscriminatingly affects the human health and operation of machinery. The electromagnetic spectrum ranges from the shorter wavelengths(including gamma and x-rays) to the longer wavelengths(including microwaves and broadcast radio waves). Radiation that is not absorbed or scattered in the atmosphere can reach and affect on the operation of machine. In this study, electromagnetic wave that is interfered to the machine and human is detected in factory, and decrease method of electromagnetic wave interference is studied.

• 방송과미디어
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• 제12권3호
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• pp.14-36
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• 2007

다양한 무선 통신 서비스의 등장으로 주파수 자원의 수요가 급증하여 스펙트럼 이용 효율을 극대화하기 위한 새로운 기술 개발의 필요성이 대두되고 있으며, 이에 대한 기술로 Cognitive Radio (CR) 기술이 주목받고 있다. CR 기술은 선택된 주파수 대역에 최적의 QoS를 제공하기 위해서는 먼저 주파수 환경에 적응성을 갖는 스펙트럼 센싱 (Spectrum Sensing) 기술이 필요하며, CR 기술이 적용된 무선 브로드밴드 네트워크 (AWBN : Adaptive Wireless Broadband Network) 모듈은 최근 각광받고 있는 방통융합 솔루션의 Hot Issue인 QoS 보장 홈네트워크 기반의 멀티미디어 전송(TV Portal Service)용 네트워크에 최적화된 솔루션으로 활용될 것으로 기대하고 있을 뿐만 아니라, IEEE 802.22 그룹에서 연구되고 있는 비어있는 TV 대역 및 마이크로폰 대역에 활용될 뿐만 아니라, 기존의 Mobile WiMax에 의한 브로드밴드 네트워크에도 활용 가능하다. 본 고에서는 IEEE 802.22/16d 시스템 규격에 의해 개발된 AWBN 시스템 개발 내용을 기술한다.

• 대한음성학회:학술대회논문집
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• 대한음성학회 2005년도 춘계 학술대회 발표논문집
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• pp.3-7
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• 2005

This research is for finding prototypes and characteristics of intonation found in ${\ulcorner}$-a/e, $t{\int}ijo$<${\lrcorner}$ and ${\ulcorner}$p/simnida${\lrcorner}$ among modern Korean predicate statements by constructing spoken corpus based on the current radio broadcast. So the result of the study is as follows. : (1) The construction of the balanced spoken corpus and the standard for boundary determination of rhythm are needed for the intonation model of speech synthesis. (2) Korean intonation units have the splited word tone which includes the nuclear tone and the pre-nuclear tone makes unclear tone more detailed. (3) I made man and woman intonation models individually through t-test of SPSS. (4) The standard intonation model is devided '-ajo'type and '-nida'type

• 대한음성학회:학술대회논문집
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• 대한음성학회 2007년도 한국음성과학회 공동학술대회 발표논문집
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• pp.197-200
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• 2007

The purpose of this study is to analyze the prosodic characteristics of Korean news utterances. In this paper, prosodic phrases were described in terms of the K-ToBI labeling system. In addition, the change of intonation contour that occurs throughout the sentences was discussed in terms of types of media and gender. According to analyzing the tendency of resets, 331 out of 729 resets were observed at the boundary of the intonation phrases. This means that resets are of the speaker's own volition regardless of prosodic units of intonation phrases. The declination of the intonation contour of radio news showed a gentler slope than that of TV news, because when the sentence is getting longer, the declination of the intonation contour becomes slower.

• Journal of information and communication convergence engineering
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• 제7권3호
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• pp.297-303
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• 2009

Automatic Identification System (AIS) is a VHF radio broadcasting system where transmits packets of data via VHF data link. It enables vessels and coastal-based station that equipped with AIS equipment to send and receive useful information. This information can be help in situational awareness and provide a means to assist in collision avoidance. In addition, AIS can be use as Aid-To-Navigation, by providing the location and additional information on buoys and lights. Besides, it can also contain details information in meteorological status of a particular ship location. This paper presents the standalone AIS system that able to receive and report own ship location, meteorological data collection and broadcast safety related information if necessary. With the unique ship's MMSI number, all the information of that particular ship can be monitor by using AIS program written in C++ programming language.

• 정보와 통신
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• 제26권2호
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• pp.23-30
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• 2009

3GPP(3rd Generation Partnership Project)는 3세대 이동통신인 UMTS(Universal Mobile Telecommunication System)의 초기 표준화 이후 HSPA(High Speed Packet Access), MBMS(Multimedia Broadcast/Multicast Service) 등의 기술 개발로 UMTS 시스템을 지속적으로 발전시켜 왔다. 그리고, 최근 새로운 무선 접속 기술에 기반한 LTE(Long Term Evolution)시스템에 대한 표준화를 거의 완료하고 ITU-R(International Telecommunications Union-Radio)의 IMT-Advanced 요구사항을 만족하는 LTE-Advanced 시스템에 대한 연구를 진행하고 있다. 한편 최근 다양한 무선 접속 기술간 핸드오버 기술이 중요한 이슈로 부각됨에 따라 LTE-Advanced에서도 이를 수용하기 위한 기술이 요구된다. 본 고에서는 3GPP에서 추진하고 있는 LTE-Advanced기술의 표준화 동향과 향후 이에 적용 가능한 다양한 무선 접속 기술간의 핸드오버 지원 기술을 살펴봄으로써 LTE-Advanced에서의 끊김없는 이동성(seamless mobility) 제공을 위한 근간을 제시하고자 한다.