• Journal of Korea Multimedia Society
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• v.2 no.1
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• pp.69-79
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• 1999

We have implemented the telecommunication management functions based on TMN (Telecommunications Management Network) architecture that is standardized by ISO/ITU-T. TMN has been developed to manage heterogeneous networks, services and equipment. In this paper, we first analyze the detailed functions of EMS (Element Management System) that performs core functions in the subnetwork management of TMN architecture. We propose an implementation method of EMS for efficient subnetwork management and verify its performance and functionality through detailed implementation and various testing. The proposed EMS consists of EML-Manager module and NML-Agent module. The EML-Manager module controls NEL (Network Element Layer) through the CMIP operations on the managed-objects. The NML-Agent module processes the requests from NMS (Network Management System) in upper layer. We have implemented NMS that performs only the NML-Manager function to test the proposed EMS, and we have used NE-Agent that was designed and implemented by the B-ISDN Lab. of Yeungnam University. The implemented EMS has three management functions: configuration management function, performance management function, and fault management function. We confirmed that the EMS operated normally as we tested the EMS. As further research works, the implementation of NMS with both NML-Manager function and SML-Agent function is required.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.2
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• pp.150-157
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• 2006

Spatially resolved remote identification and quantification of trace gases in the atmosphere is desirable in various fields of scientific research as well as in public security and industrial contexts. Environmental observations investigating causes, extent md consequences of air pollution are of fundamental interest. We present an Imaging-DOAS system, a ground based remote sensing instrument that allows spatially resolved mapping of atmospheric trace gases by a differential optical absorption spectroscopy(DOAS) with sun scattered light as the light source. A passive DOAS technique permits the identification and quantification of various gases, e.g., $NO_2,\;SO_2,\;and\;CH_2O$, from their differential absorption structures with high sensitivity. The Imaging-DOAS system consists of a scanning mirror, a focusing lens, a spectrometer, a 2-D CCD, ad the integral control software. An imaging spectrometer simultaneously acquires spectral information on the incident light in one spatial dimension(column) and sequentially scans the next spatial dimension with a motorized scanning mirror. The structure of the signal acquisition system is described in detail and the evaluation method is also briefly discussed. Applications of imaging of the $NO_2$ contents in the exhaust plumes from a power plant are presented.

• Journal of IKEEE
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• v.7 no.2 s.13
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• pp.288-298
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• 2003

We consider a window-controlled selective-repeat ARQ scheme for error control between two adjacent nodes lying on a communication path. In this scheme, each packet to be transmitted is endowed with a serial number in a cyclic and sequential fashion. In turn, the transmitting node is not allowed to transmit a packet belonging to a window before every packet in the previous window is positively acknowledged. Such postponement of packet transmission incurs a degradation in throughput and delay performance. In this paper, aiming at improving packet delay performance, we employs a supplement scheme in which a serial number is duplicated within a frame. Classifying duplication rules into fixed, random and adaptive categories, we present candidate rules in each category and evaluate the packet delay performance induced by each duplication rule. From numerical examples, we observe that duplicating serial numbers, especially ADR-T2 effectively reduces mean packet delay for the forward channel characterized by a low packet error rate. We also reveal that such delay enhancement is achieved by a high probability of hitting local optimal window size.