• Proceedings of the Korean Information Science Society Conference
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• 2001.04a
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• pp.157-159
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• 2001

최근 이동 단말 사용자의 수가 급증함에 따라 네트워크 트래픽을 줄여 신속한 호 설정을 가능하게 하는 것이 중요하게 되었다. 이러한 목적을 달성하기 위하여, 빈번하게 호 요청을 하는 이동 단말들에 대해서는 캐쉬를 사용하는 기법이 제안되었다. 그러나, 기존의 캐쉬 기법은 낮은 캐쉬 실패와, 캐쉬 실패 발생시 불필요한 네트워크 지연을 초래하는 문제점이 있다. 본 논문에서는 이동 단말 사용자들이 이동 지역성을 가진다는 점을 이용하여 캐쉬 실패가 발생하더라도 HLR까지 질의하지 않고 포워딩 포인터를 따라 인접 VLR들을 질의하게 함으로써 시스템 전반적으로 위치 질의 비용을 줄여 신속한 호 설정을 가능하게 한다. 이는 HLR로 집중되는 네트워크 트래픽을 감소시켜 PCS 네트워크 사용자들에게 보다 나은 QoS를 제공하는데 이용될 수 있다. 아울러 제안하는 기법이 기존의 위치 관리 기법들보다 위치 관리비용 측면에서 보다 효율적임을 수학적 성능 분석 모델을 통하여 보인다.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.04b
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• pp.1261-1264
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• 2002

개인 통신 서비스에서 주된 당면 문제중의 하나는 위치를 자주 이동하는 많은 이동 단말기들의 위치를 찾는 것이다. 위치 관리를 성취하기 위하여 많은 네트워크 신호처리 트래픽과 데이터베이스 질의가 요구된다. 다수의 정책들은 이동 단말기의 현재 위치를 저장하기 위하여 위치 레지스터 데이터베이스를 사용하고, 그 위치 레지스터의 고장에 대해 약점을 가지고 있다. 이 논문에서, 우리는 위치 레지스터들의 고장을 포용하는 분산 홈 위치 레지스터를 갖는 결함 포용 전방 포인터 방법을 제안한다. 제안하는 방법의 성공을 분석적 모델로 평가하고, Biaz의 우회 전방 정책, 두개 경로 전방 정책과 성능을 비교한다.

• Advances in environmental research
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• v.4 no.2
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• pp.83-104
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• 2015

Air Quality Index (AQI) is a pointer to broadcast short term air quality. This paper presents one day ahead AQI forecasting on seasonal basis for three major cities in Maharashtra State, India by using Artificial Neural Networks (ANN) and Genetic Programming (GP). The meteorological observations & previous AQI from 2005-2008 are used to predict next day's AQI. It was observed that GP captures the phenomenon better than ANN and could also follow the peak values better than ANN. The overall performance of GP seems better as compared to ANN. Stochastic nature of the input parameters and the possibility of auto-correlation might have introduced time lag and subsequent errors in predictions. Spectral Analysis (SA) was used for characterization of the error introduced. Correlational dependency (serial dependency) was calculated for all 24 models prepared on seasonal basis. Particular lags (k) in all the models were removed by differencing the series, that is converting each i'th element of the series into its difference from the (i-k)"th element. New time series is generated for all seasonal models in synchronization with the original time line & evaluated using ANN and GP. The statistical analysis and comparison of GP and ANN models has been done. We have proposed a promising approach of use of GP coupled with SA for real time prediction of seasonal multicity AQI.

• Journal of Digital Convergence
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• v.10 no.4
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• pp.207-215
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• 2012

This paper proposes a proxy-based caching optimization scheme for improving the streaming media services in wireless mobile ad hoc networks. The proposed scheme utilizes the proxy for data packet transmission between media server and nodes in WLANs, and the proxy locates near the wireless access pointer. For caching optimization, this paper proposes NFCO (non-full cache optimization) and CFO (cache full optimization) scheme. When performs the streaming in the proxy, the NFCO and CFO is to optimize the caching performance. This paper compared the performance for optimization between the proposed scheme and the server-based scheme and rate-distortion scheme. Simulation results show that the proposed scheme has better performance than the existing server-only scheme and rate distortion scheme.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.6
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• pp.50-63
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• 2000

In this paper, a new EMG pattern classification method based on soft computing techniques is proposed to help the disabled and the elderly handle rehabilitation robotic arm systems. First, it is shown that EMG is more useful than existing input devices such as voice, a laser pointer and a keypad in view of naturality, extensibility, and applicability. Then, a new procedure is proposed to select the minimal feature set. As methods of classifying the pre-defined motions, a fuzzy pattern classification and fuzzy min-max neural networks (FMMNN) are designed using the selected features. As results, the motions are recognized with success rates of 83 percent and 90 Percent using fuzzy pattern classification and FMMNN, respectively.

• Journal of KIISE:Computing Practices and Letters
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• v.7 no.5
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• pp.539-547
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• 2001

Cluster systems employ high speed interconnection networks and use efficient communication layers to gain high performance and scalability. But the diversity in implementation mechanism among these communication layers causes lack of portability. A solution is to provide communication standard APIs such as MPI. This paper introduces MPI-VMMC: an MPI implementation on VMMC. Though the direct deposit transfer mechanism used in VMMC is not suitable for Send/Recv mechanism used in MPI, the proposed sub-layer laid between MPI and VMMC efficiently translates from one mechanism to the other. We also use the lazy pointer and selective zero-copy transfer technique to gain high performance. The peak performance of MPI-VMMC is 90.7Mbytes/sec, which is about 95% of the base communication layer\`s.