• ETRI Journal
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• 제40권3호
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• pp.291-302
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• 2018

The deployment of an incremental hybrid decode-amplify and forward relaying scheme is a promising and superior solution for cellular networks to meet ever-growing network traffic demands. However, the selection of a suitable relaying protocol based on the signal-to-noise ratio threshold is important in realizing an improved quality of service. In this paper, an incremental hybrid relaying protocol is proposed using polar codes. The proposed protocol achieves a better performance than existing turbo codes in terms of capacity. Simulation results show that the polar codes through an incremental hybrid decode-amplify-and-forward relay can provide a 38% gain when ${\gamma}_{th(1)}$ and ${\gamma}_{th(2)}$ are optimal. Further, the channel capacity is improved to 17.5 b/s/Hz and 23 b/s/Hz for $2{\times}2$ MIMO and $4{\times}4$ MIMO systems, respectively. Monte Carlo simulations are carried out to achieve the optimal solution.

• International journal of advanced smart convergence
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• 제3권2호
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• pp.14-17
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• 2014

Precision agriculture relies on information technology, whose precondition is providing real-time and accurate information. It depends on various kinds of advanced sensors, such as environmental temperature and humidity, wind speed, light intensity, and other types of sensors. Currently, it is a hot topic how to collect accurate information, the main raw data for agricultural experts, monitored by these sensors timely. Most existing work in WSNs addresses their fundamental challenges, including power supply, limited memory, processing power and communication bandwidth and focuses entirely on their operating system and networking protocol design and implementation. However, it is not easy to find the self-localization capability of wireless sensor networks. Because of constraints on the cost and size of sensors, energy consumption, implementation environment and the deployment of sensors, most sensors do not know their locations. This paper provides maximum likelihood estimators for sensor location estimation when observations are time-of arrival (TOA) range measurement.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권4호
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• pp.805-821
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• 2011

Wireless Sensor Networks (WSNs) are rapidly emerging because of their potential applications available in military and civilian environments. Due to unattended and hostile deployment environments, shared wireless links, and inherent resource constraints, providing high level security services is challenging in WSNs. In this paper, we revisit various security attack models and analyze them by using a well-known standard notation, Unified Modeling Language (UML). We provide a set of UML collaboration diagram and sequence diagrams of attack models witnessed in different network layers: physical, data/link, network, and transport. The proposed UML-based analysis not only can facilitate understanding of attack strategies, but can also provide a deep insight into designing/developing countermeasures in WSNs.

• 품질경영학회지
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• 제36권3호
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• pp.1-12
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• 2008

Obtaining the accurate final importance of each customer attribute (CA) is very important in the house of quality(HOQ), because it is deployed to the quality of the final product or service through the quality function deployment(QFD). The final importance is often calculated by the multiplication of the relative importance rate and the competitive priority rate. Traditionally, the sample mean is used for estimating two rates but the dispersion is ignored. This paper proposes a new approach that incorporates statistical significance to consider the dispersion of rates in determining the final importance of CA. The approach is illustrated with a design of car door for each case of crisp and fuzzy numbers.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.749-752
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• 2005

In this paper, we introduce an Intersection Collision Avoidance (ICA) system as a convergence example of Telematics and USN technology and show several requirements for the ICA system. Also, we propose a system design that satisfies the requirements of reliable vehicular data acquisition, real-time data transmission, and effective intersection collision prediction. The ICA system consists of vehicles, sensor nodes and a base station that can provide drivers with a reliable ICA service. Then, we propose several technological solutions needed when implementing the ICA system. Those are about sensor nodes deployment, vehicular information transmission, vehicular location data acquisition, and intersection collision prediction methods. We expect this system will be a good case study applied to real Telematics application based on USN technology.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2004년도 춘계공동학술대회 논문집
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• pp.536-539
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• 2004

인터넷 서비스 수요의 급증으로 IP망의 대용량화와 고품질 서비스 제공에 대한 요구가 증대되고 있다. 이에 대해 네트워크 시설의 확충이나 트래픽 엔지니어링의 적용을 통해 대응해 왔으나, 멀티미디어 서비스 증가, 데이터 유형별 QoS 특성의 차이로 인해 기존에 적용해 오던 망 관리 시스템에의 의존에서 탈피, 현재 나타나고 있는 통신서비스 활동 특성의 변화를 감안, 실제 사용자의 서비스 이용 차원에서 고품질, 광대역 서비스를 제공해 줄 수 있는 관리 방안에 대한 모색이 필요하게 되었다. 이에따라, Intserv, Diffserv, RSVP, MPLS 등이 등장하였고, QoS 보증(SLA)에서는 서비스품질 보장 범위의 확대를 비롯한 다양한 고객요구가 증가하고 있는 상황이다. 이에 본 논문에서는 통신서비스 전반에 나타나고 있는 차별화된 프리미엄 서비스의 등장에 따른 QoS 보증방안에 대해서 다루고자 한다. 이를 위해, 우선 통신사업자의 네트워크 운용환경 변화방향에 대해 점검해 보고, 프리미엄 서비스의 도입이 가능한 대상과 범위에 대해서도 살펴본다. 이어서, 새로운 서비스 환경에서의 사업 기회와 진략 수립 방향, 법${\cdot}$제도적인 측면을 포함한 사업환경에 대한 시사점을 제공하고자 한다.

• 품질경영학회지
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• 제37권3호
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• pp.74-82
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• 2009

This article presents a six sigma project for improving purchase conversion rate in mobile game site. The project was carried out based on DMAIC process. First, a defect rate is defined as low purchase conversion rate. In addition, 60-days purchase data was analyzed and it is shown that the defects level was 2.48 sigma level. In this study, in order to raise the sigma level, six personalization services were used in the mobile game site. Six factors were determined based on FDPM(Functional Deployment Process Map), fishbone chart, linear regression analysis, effort-performance matrix, and so on. The sigma level of defects has improved from 2.48 to 2.93.

• 대한안전경영과학회지
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• 제2권4호
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• pp.153-164
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• 2000

QFD (Quality Function Deployment) was defined by the American Supplier Institute in 1987 as a system for translating consumer requirements into appropriate company requirements at every stage, from research, through product design and development, to manufacture, distribution, installation, and marketing, sales and services. Although QFD has complex and tedious procedure to complete, it has now been in use in the world for at least 15 years because QFD enables us to catch a lot of fruitful information on the given system. The objective of this paper is to provide and analyze the trend on the choice of subject courses of university students using QFD. The data are collected by questionnaires. The samples for this study are randomly chosen from the universities in Seoul, Kangnung, and Samchok during 3 months (2000. 3∼2000.5). The results of this study will play an important role not only for service of students but also for opening of courses.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2007년도 학술대회
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• pp.46-49
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• 2007

Multiple Antenna Technologies such as Multiple-Input Multiple-Output (MIMO) and Beamforming provide the increase of channel capacity and the reliability of wireless link. To obtain these advantages, WiBro, Mobile WiMAX and $4^{th}$ Generation System are employing multiple antenna technologies. There exist, however, many technical issues in considering the application of the technologies or the providing of services using them. In this paper, various technical topics are discussed and simple solutions are proposed. Beamforming has several technical issues which include coverage imbalance, difficulties in providing Multicast-Broadcast Service (MBS). In Addition, network planning is a critical point from a cell extension and initial network entry point of view. In case of MIMO, network deployment is discussed in that cellular data network such as WiBro has many repeaters. MIMO mode selection for maximizing the cell capacity is also covered.

• Journal of Electrical Engineering and Technology
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• 제10권5호
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• pp.2135-2141
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• 2015

Power line communication (PLC) is one of the major communication technologies in smart grid since it combines good communication capability with easy and simple deployment. As a power network can be modeled as a graph, we propose a vertex coloring based slot reuse scheduling in the time division multiple access (TDMA) period for PLCs. Our objective is to minimize the number of assigned time slots, while satisfying the quality of service (QoS) requirement of each station. Since the scheduling problem is NP-hard, we propose an efficient heuristic scheduling, which consists of repeated vertex coloring and slot reuse improvement algorithms. The simulation results confirm that the proposed algorithm significantly reduces the total number of time slots.