• Journal of Communications and Networks
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• v.10 no.3
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• pp.297-300
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• 2008

The capacity of ultra-wideband (UWB) systems in presence of narrowband interference (NBI) is studied. By appropriately modifying the Shannon capacity formula, an analytical expression for the capacity of M-ary pulse position modulation (PPM) signals in the presence of NBI is obtained. Performance evaluation results for the capacity of such signals as a function of the NBI carrier frequency and power are also presented.

• Journal of Communications and Networks
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• v.10 no.3
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• pp.308-315
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• 2008

When operating in frequency-division duplex (FDD) mode, transmit beamforming in multiple-input single-output (MISO) wireless communication systems typically requires accurate knowledge of downlink channel state information (CSI) at the transmitter. In practical FDD systems, obtaining such downlink CSI at the transmitter is challenging, if not impractical. To circumvent such challenge and support user mobility, we present a new method for transmit beamforming based on simple beam-control commands (BCCs) in MISO FDD mobile systems. We then numerically evaluate the effects of BCC errors in terms of transmit power efficiency, system capacity, and outage probability.

• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.594-596
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• 1999

It is extremely important to compress a very large multimedia data under the currently used communication networks because of the forthcoming high fast multimedia informations. Wavelets are very popular and useful mathematical tool in the field of signal processing recently. In this paper, signal compression methods using the wavelet packet transform are compared with the other compression method under same threshold condition. As the result, the compression of using the wavelet packet transform is much more effective than the other compressing methods.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.182-184
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• 2000

There are several facilities in Kochang distribution test center such as artificial fault generator(AFG), new distribution automation system(NDAS), communication networks (wireless and optic), lumped constant circuit, switches for distribution automation, overhead and underground distribution line. We have been field testing on remote control, data acquisition. remote metering, feeder automation and so on for distribution automation using those equipment.

• Proceedings of the Korean Information Science Society Conference
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• 2008.06d
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• pp.176-180
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• 2008

무선 메쉬 네트워크는 최근 무선 네트워크 환경에서 유선을 효율적으로 연장할 수 있는 기술로서 주목 받고 있으며 무선 백본망을 통해 저렴한 비용으로 광대역 네트워크 인프라를 구성하는 기술이다. 무선 메쉬 네트워크는 기존 네트워크 기술과는 달리 노드의 이동성이 적고 에너지 영향도 덜 제한적인 특징을 가지고 있다. 따라서 이러한 네트워크 특성을 반영할 수 있는 경로 설정 기술이 필요하며 적합한 경로를 결정하기 위한 새로운 라우팅 메트릭이 요구된다. 본 논문에서는 데이터를 효율적으로 전달하기 위해 노드 간 링크 성능과 노드의 부하를 고려한 새로운 라우팅 메트릭을 제안한다.

• Proceedings of the Korean Information Science Society Conference
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• 2008.06d
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• pp.428-431
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• 2008

Recently, people have been interested in new intelligent transport system (ITS) architecture, so that vehicular networks are becoming an attractive research area. When vehicles try to access data through a roadside unit (RSU), data scheduling of RSU needs to improve service ratio due to limited bandwidth and service time. In this paper, we propose a service scheduling algorithm based on transmission delays and service deadlines of vehicles in order to improve the service ratio. In our algorithm, we assume the promiscuous operation of wireless nodes and it can make a single transmission of RSU serve multiple requests. We evaluated the performance of our scheme via simulations, and results show that our schemes have better performance than existing algorithms.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.367-370
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• 2004

We model a moving object as a sizable physical entity equipped with GPS, wireless communication capability, and a computer such as a PDA and mobile phone. Furthermore, we have observed that a real trajectory of a moving object is the result of interactions among moving objects in the system yielding Multi-points instead of a line segment. In this paper, the new types and operations are integrated seamlessly into the moving object framework to achieve a relatively simple, consistent and powerful overall model and query language for constrained and unconstrained movement.

• Electronics and Telecommunications Trends
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• v.19 no.3 s.87
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• pp.32-40
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• 2004

상황정보(context information)는 사용자의 요구와 주변 상황이 수시로 변화하는 이동통신 환경에서 더욱 중요하게 활용된다. 따라서, 차세대 이동통신 시스템의 서비스는 음성, 텍스트, 멀티미디어 서비스의 고도화에 이어 일상 곳곳에 편재된 센서 및 컴퓨터들이 수집한 각종 환경정보를 효과적으로 상호 공유하여 사용자 및 주변 환경의 상황(context)을 알아내고 그에 맞는 다양한 정보에 근거하여 자발적으로 서비스를 제공하는 상황인식(context-aware) 특징을 가지게 될 것이다. 이러한 상황인식 서비스를 가능하게 하기 위해서는 사용자 및 사물 등의 객체를 인식하고, 이들의 현 상태에 따른 상황정보를 수집하여 서비스에 적응하는 기술 등이 필수적이다. 본 논문에서는 IMT-2000 이후의 차세대 이동통신 시스템의 진화방향을 상황인식 서비스 제공 관점에서 살펴보고, 상황인식 서비스를 위한 관련 기술과 차세대 이동통신 환경에서 상황인식 서비스가 어떻게 제공될 수 있을지를 살펴본다.

• International journal of advanced smart convergence
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• v.9 no.3
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• pp.85-96
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• 2020

It is important to extract salient object image and to solve the invariance problem for image recognition. In this paper we propose a new hybrid algorithm for invariance and improved classification performance in image recognition, whose algorithm is combined by FT(Frequency-tuned Salient Region Detection) algorithm, Guided filter, Zernike moments, and a simple artificial neural network (Multi-layer Perceptron). The conventional FT algorithm is used to extract initial salient object image, the guided filtering to preserve edge details, Zernike moments to solve invariance problem, and a classification to recognize the extracted image. For guided filtering, guided filter is used, and Multi-layer Perceptron which is a simple artificial neural networks is introduced for classification. Experimental results show that this algorithm can achieve a superior performance in the process of extracting salient object image and invariant moment feature. And the results show that the algorithm can also classifies the extracted object image with improved recognition rate.

• Journal of the Korea Society of Computer and Information
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• v.21 no.10
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• pp.99-105
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• 2016

The active rule system is a key element of the rule-based mobile agent middleware system for activeness and autonomy of the sensor network. The rule manager, which is the main components of active rule based mobile agent framework and active rule system, performs the control and management of the rule-related processes. In this paper, we design and implement the roles and functions of the rule manager in detail. The proposed rule manager plays an important role in the sensor network environment. The sensor data server loads the active rule on the mobile agent by the rule manager according to the situations, and the mobile agent migrates to the destination node and performs the designated action. This active rule-based mobile agent middleware system presents the usefulness for the various sensor network applications. Through the rule execution experiment using the rule-based mobile agent, we show the adaptability and applicability of rule-based mobile agent middleware system to the dynamic environmental changes in sensor networks.