• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.6
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• pp.1-7
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• 2012

Due to the increasing demand of network convergence, in future, hybrid/integrated satellite and terrestrial systems will play an important role. In that case, compatibilities between the satellite and terrestrial systems are very important for efficiency of the systems. 3GPP Long Term Evolution (LTE) is one of the 4G system. Therefore, in this paper, we introduce the design of interleaver for mobile satellite system based 3GPP LTE specification. The 4G system including the LTE specification adopted adaptive modulation and coding (AMC) schemes for efficient usage of resources, and the updating interval of resource allocation is an order of msec. However, because of the long round trip delay of satellite systems, we cannot employ the same AMC scheme specified for the terrestrial system, and thus it cannot effectively counteract to short term fadings. Therefore, in order to overcome these problems, we propose an interleaver scheme combined with AMC. We present the interleaver design results considering mobile satellite system based on the LTE and analyze the simulation results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.3B
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• pp.259-266
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• 2002

In the CDMA system, the Multiple access interference(MAI) causes system performance and capacity degradation. One of the MAI cancel method is a feedback detector that orthogonal decision-feedback detector(ODFD) and Deocrrelating decision-feedback detector(DDFD) have been studied by now. In this paper, we propose a blind adaptive ODFD(BA-ODFD) with blind equalizer combined ODFD, Also we simulate the operation of BA-ODFD in AWGN channel and Rayleigh (tiding channel. and compare blind adaptive ODFD with blind adaptive DDFD.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.10A
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• pp.980-989
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• 2002

In this paper, we have proposed the sectorization method of the adaptive sector antenna and the new receiver structure for the CDMA wireless multi-media communication which uses multi-code and single-code. The sectorization and average BER performance of the adaptive sector antenna, which employs the proposed sectorization method, are obtained through simulation. The simulation results have shown that the sizes of sectors are properly controlled according to the distribution of the load and that the BER performance of the adaptive sector antenna is enhanced much more than that of the fixed sector antenna. Also, we have proposed two receivers, which are different from the positions to detect multi-code signals, for the multi-media communication. Each receiver has a simple cancellation scheme and two adaptive sector antennas, which are called the 1st adaptive sector antenna and the 2nd adaptive sector antenna, respectively. In this paper, the average BER performances of the receivers are compared through simulation. As the results of the simulation, we have recognized that all user' BER performances are greatly dependent on the positions to detect the multi-code signals. When we consider both system complexity and terget BERs of signals, we have concluded that the receiver, which detect multi-code signals in the 1st and the 2nd adaptive sector antenna, is appropriate for the CDMA wireless multi-media communication systems.

• Journal of KIISE
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• v.43 no.7
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• pp.801-811
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• 2016

Self-adaptive systems (SASs) can change their goals and behaviors to achieve its ultimate goal in a dynamic execution environment. Existing approaches have designed, at the design time, utility functions to evaluate and predict the goal satisfaction, and set policies that are crucial to achieve each goal. The systems can be adapted to various runtime environments by utilizing the pre-defined utility functions and policies. These approaches, however, may or may not guarantee the proper adaptability, because system designers cannot assume and predict all system environment perfectly at the design time. To cope with this problem, this paper proposes a new method of dynamic decision making, which takes the following steps: firstly we design a Dynamic Decision Network (DDN) with environmental data and goal model that reflect system contexts; secondly, the goal satisfaction is evaluated and predicted with the designed DDN and real-time environmental information. We furthermore propose a dynamic reflection method that changes the model by using newly generated data in real-time. The proposed method was actually applied to ROBOCODE, and verified its effectiveness by comparing to conventional static decision making.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10a
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• pp.472-474
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• 2003

그리드는 다양한 기관들에 의해 소유되고 관리되는 컴퓨팅 자원들을 통합적이며 협력적으로 사용하게 하는 기반 구조이다. 이러한 기반 구조를 제공하기 위해서 Globus, Legion, Condor 등 많은 시스템이 개발되어 왔고 현재도 계속 개발 중에 있다. 하지만 이런 시스템은 시스템의 경직성 때문에 다양한 환경에 적용시키기가 어렵다. 본 논문에서는 이러한 문제점을 보완하기 위해 기존의 시스템에 유연성을 제공하는 모듈 기반의 적응형 그리드 환경(Module-based Adaptive Grid Environment)을 개발하였다. 이에 개발자는 MAGE를 이용하여 유연하게 응용 프로그램을 개발할 수 있으며 사용자는 MAGE를 이용하여 자신이 사용하는 환경에 맞게 그리드를 사용할 수 있다. 더 나아가 MAGE를 사용하여 수시로 변화는 환경에 적응하여 반응하는 자기 반영적인 미들웨어를 제공할 수 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.8A
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• pp.859-867
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• 2004

To provide high-quality media streaming service over the best-effort Internet, a streaming methodology is required to response to the dynamic fluctuation of underlying networks. In this paper, we implement the MPEG-4 streaming system with adaptive transport based on priorities of media packets. The implemented system is composed of the common MPEG-4 streaming components such as elementary stream provider, sync and DMIF layer, and adaptive transport module including data prioritization and FEC control. More specifically, the prioritized sync layer packets (based on object level) are delivered to the transport module and then are encoded by an adaptive FEC encoder to help reliable transport. The FEC combination is dynamically adjusted by the feedback information from the receiver. In addition, low priority packets are selectively dropped to meet the limitation of available bandwidth. The experimental results over the emulation-based testbed show that the Proposed system can mitigate the impact of network fluctuation and thus improve the quality of streaming.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.12
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• pp.2511-2520
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• 2011

This paper describes the parameter adjustment method of fuzzy membership function to improve the performance of multi-sensor fusion system using adaptive fuzzy-Kalman filter and cross-validation. The adaptive fuzzy-Kanlman filter has two input parameters, variation of accelerometer measurements and residual error of Kalman filter. The filter estimates system noise R and measurement noise Q, then changes the Kalman gain. To evaluate proposed adaptive fuzzy-Kalman filter, we make the two-axis AHRS(Attitude Heading Reference System) using fusion of an accelerometer and a gyro sensor. Then we verified its performance by comparing to NAV420CA-100 to be used in various fields of airborne, marine and land applications.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.1
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• pp.17-26
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• 2016

IoT means things space networks that form the intelligent relationship such as sensing, networking, information processing about human being, things and service without explicit mutual cooperation of human being. Lately many IoT groups such as AllSeen Alliance, OIC launched a platform for IoT. Self-adaptive is aimed at implementation without the need for decisions of human being during the operation, so that the machine can respond to changes in its own determination. There is a need to apply the concept of self-adaptive to existing IoT and IoT platform. So In this paper, We look for trends of existing IoT, IoT platform and comparisons by applying a self-adaptive concept to IoT, IoT platform. In addition as an example of this paper, we suggest lacking self-adaptive elements to OIC.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04b
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• pp.253-255
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• 2001

인터넷을 통한 사용자의 선호도를 분석하고 협력적 여과 및 내용기반 여과 기술을 결합 이용하여 유머문서를 추천하는 MrHumor 시스템을 구축하였다. 유머문서 추천 기술은 다양한 아이템에 대한 여과 및 추천 기술로 확장되어 인터넷을 통한 과다 정보 시대에 필요한 소프트봇 혹은 지능형 에이전트 기술에 적용될 수 있다. MrHumor 추천시스템은 적응형 학습 시스템으로서 새로운 사용자의 선호도에 대한 학습량과 추천시기에 따라 이용할 추천방식이 다른 성능을 보이는데 여러 가지 상황에서도 적절한 동작을 보이기 위하여 MrHumor에서는 은닉변수 모델을 이용하여 사용자의 인구통계적 정보와 문서의 내용적 특징간의 관계를 학습하여 초기 추천을 행하고 SVM을 이용하여 개인의 선호도를 학습한 내용 기반의 여과와 적응형 k-NN모델을 이용한 협력적 여과를 결합하여 추천을 수행한다. 제안된 방식에 의한 추천 성능은 3방식이 각각 이용된 경우에 비해 안정적이고 높은 예측 정확도를 보인다.

• Proceedings of the Korea Information Processing Society Conference
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• 2021.11a
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• pp.367-370
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• 2021

스마트 시티에서 교차로의 통행을 관리하는 교통신호 시스템 분야의 목표는 교통 혼잡 최소화 및 처리량 최대화이다. 현재, 신호 제어 시스템은 고정형 시스템을 사용하고 있으며, 효율적이고 유동적으로 교통을 제어하기 위해 적응형 방식의 교통신호 제어 연구가 활발히 진행 중이다. 적응형 방식의 교통신호 방식 중에서 고정된 신호 순서에 상황에 맞는 신호시간을 할당하는 방법이 있다. 본 논문은 고정된 신호 순서가 교통 신호 성능에 미치는 영향을 분석하였다. 그 결과, 신호 순서가 교통신호 성능에 미치는 영향도가 크지 않다는 것을 확인할 수 있었다.