• 전자공학회논문지T
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• 제36T권2호
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• pp.14-20
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• 1999

본 논문에서는 자율분산로봇의 무선 통신시스템에 관하여 연구하였다. 이동로봇 사이의 협조 동작을 위하여 통신의 구현이 필요하다. 따라서, 우리는 이동로봇에 무선통신시스템을 적용하여 실험하였다. 그리고, 여러 이동로봇 사이의 상호작용을 연구하기 위하여 분산된 제어구조의 개념과 실험적 구조를 설명한다.

• 대한산업공학회지
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• 제32권2호
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• pp.120-125
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• 2006

Since Korean government has implemented the "Number Portability System" in the domestic mobile communications market, mobile communication companies have been striving to hold onto existing customers and at the same time to attract new customers. This paper presents a competing risk model that considers the characteristics of a customer in order to predict the customer's life under the "Number Portability System." Three competing risks considered are pricing policy, quality of communication, and usefulness of service. It was observed that the customers who pay more are less sensitive on pricing policy younger people are less sensitive than older people to the quality of communication and women are more sensitive than men to the degree of usefulness of service. We expect that the result of this study can be used as a guideline for effective management of mobile phone customers under the Number Portability System.

• 한국지능정보시스템학회:학술대회논문집
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• 한국지능정보시스템학회 2001년도 The Pacific Aisan Confrence On Intelligent Systems 2001
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• pp.186-191
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• 2001

Mobile agent technologies are getting popular as means for accessing network resources efficiently. In order for mobile agents to be accepted as a reliable technology for applications such as e-commerce, a proper framework for mobile database should be established. In this paper, we first discuss weak points of current mobile computing systems that mostly result from the limitations of current mobile computing technology including frequent disconnection, limited battery capacity, low-bandwidth communication and reduced storage capacity. These weak points also have become the cause of transaction problem where mobile devices issue transactions. In order to eliminate this transaction problem in the mobile environment, we propose a mobile database framework, Proxyne, which is based on the proxy and SyncML.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권11호
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• pp.2035-2051
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• 2011

Theoretical Bit Error Rate (BER) and channel capacity analysis are always of great interest to the designers of wireless communication systems. At the center of such analyses people are often encountered with a high-dimensional multiple integrals with quite complex integrands. Conventional Gaussian quadrature is inefficient in handling problems like this, as it tends to entail tremendous computational overhead, and the principal order of its error term increase rapidly with the dimension of the integral. In this paper, we propose a new approach to calculate complex multi-fold integrals based on the number theory. In contrast to Gaussian quadrature, the proposed approach requires less computational effort, and the principal order of its error term is independent of the dimension. The effectiveness of the number theory based approach is examined in BER and capacity analyses for practical systems. In particular, the results generated by numerical computation turn out in good match with that of Monte-Carlo simulations.

• 한국전자통신학회논문지
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• 제11권1호
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• pp.87-92
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• 2016

Van der Pol 발진기는 비선형 제동 현상을 가진 비보존 발진기로서 높은 진폭에서의 에너지는 소산적이며 (dissipative)이고 낮은 진폭들에서는 생성되는 구조를 가진다. 본 논문에서는 Van Der Pol 발진기 모델에서 다른 거동을 확인하기 위하여 주기적 외력을 인가하고 여기에서 파라미터 변화에 따라 어떻게 리미트 사이클이 변화하는지에 대한 패턴을 확인하고자 한다.

• 한국전자통신학회논문지
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• 제9권4호
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• pp.439-446
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• 2014

본 연구는 디지털위성중계기의 우주인증 모델에 대한 성능분석 및 구현에 대해 기술하였다. 사전 성능 분석은 각 구성품 회로 시뮬레이션을 통해 각 구성품에 대한 요구 규격 대비 만족 여부를 사전 검증하고, 각각의 구성품을 순서대로 연결하여 전체적인 디지털위성중계기의 요구 규격에 만족하는지를 사전 검증하였다. 사전 시스템 성능 분석을 통하여, 각 구성품의 요구 규격을 정의하고, 그 규격을 바탕으로 제작하였으며, 최종적으로 시스템 통합하여 전체적인 디지털위성중계기의 성능 측정을 하였다.

• Journal of information and communication convergence engineering
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• 제8권3호
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• pp.289-294
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• 2010

In the vehicle communication system, transferred information is needed to be detected as possible as fast in order to inform car status located in front and rear side. Through the moving vehicle information, we can avoid the crash caused by sudden break of front one or acquire to real time traffic data to check the detour road. To be connecting the wireless communication between the vehicles, fast timing synchronization can be a key factor. Finding out the sync point fast is able to have more marginal time to compensate the distorted signals caused by channel variance. Thus, we introduce the combination method which helps find out the start of frame quickly. It is executed by auto-correlation and cross-correlation simultaneously using only short preambles. With taking the absolute value at the implemented synch block output, the proposed method shows much better system performance to us.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.510-513
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• 2005

Due to the asymptotic property, deadbeat control can hardly be applied to the continuous time system control. But some delay element method can deal such a problem. Besides delay element method, well-known digital deadbeat control can be used by the aid of some smoothing elements. In this paper, 2nd order smoothing element is used for the smoothing of the digital deadbeat controller. And this element is argumented to the plant, and so control problem is to control the argumented system digitally. We simulated this control system using Matlab language and finally apply this algorithm to the rotary inverted pendulum system.

• 전자공학회논문지S
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• 제35S권5호
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• pp.1-10
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• 1998

Satellite communication is getting more important in the coming 21st century because of its wide areas sevice capability, ease of access, and fast channel establishment. As such, satellite communication networks will be the basis of the global communication system in cooperation with the ground ATM networks. In this paper, we consider an efficient transmission methodology of ATM cells over the satellite communication channel. We first analyze possible bottlenecks and performance deterioration factors in the case, and then propose an enhanced cell trasmission mechanism. In order to use satellite channel for ATM cell transmission, the application of complicated channel coding is inevitable. However, the forwared error control such as convolutional encoding brings forth burst errors, which calls for the application of some kind of interleaving mechanism to randomize the burst errors at the receiver. Another aspect which should b econsidered in satellite communication system is the inherent transmission delay, which can be very considered in satellite communication system is te inherent transmission delay, which can be very critical to the delay-sensitive ATM traffic. Therefore, we propose that the processing delay at the block interleaving stage should be controlled propose a variable-size block interleaving mechanism which utilizes the predicted transmission delay for each traffic in the queues of the transmitter. According to the computer simulation, the proposed mechanism could improve the overall performance by drastically reducing the ATM cell drop rate owing to the excessive transmission delay.

• 한국정보통신학회논문지
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• 제17권9호
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• pp.2167-2173
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• 2013

최근 실내 공기오염으로부터 발생되는 많은 문제점에 대한 관심이 증가하고 있으며, 실내 환경정보를 측정하여 사용자에게 사전 조치를 취할 수 있는 시스템에 대한 필요성이 점차 증대되고 있다. 이와 관련하여 본 논문에서는 휴대용 단말기, 환경 센서를 이용하여 각종 실내 환경정보를 측정할 수 있는 근거리 무선통신을 이용한 실내 환경정보 모니터링 시스템을 설계하고 구현하였다. 제안하는 시스템은 사용자의 휴대 단말기로 센서노드가 설치되어 있는 실내 환경 정보를 사전 인지하고, 위험 요소가 인지될 경우 적절한 대비를 취할 수 있는 장점이 있다.