• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.1113-1116
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• 2005

Using COMSAT which provides multi-beam switching function, the optimal transmission channel environment which provides the high data rate communication are proposed in this paper. Also the link budget for communication transponder of COMSAT is designed. Based on the channel modeling for group delay, non-linear and gain flatness characteristics, the system performances which provide various data rate services were analyzed in Ka-band satellite channel. As the transmission data rate is increased, the degradation due to these channel characteristics is severely increased. The linear component of group delay and the AM-AM component of non-linear characteristics severely affect the system performance. To efficiently provide the various service via the same transmission system it is necessary to equalize the primary impairment factors. The optimum operating points of HDR satellite transmission system are implemented and operated by considering the analyzed results on channel characteristics.

• The Magazine of the IEIE
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• v.13 no.4
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• pp.7-11
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• 1986

• The Journal of Korean Institute of Communications and Information Sciences
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• v.13 no.4
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• pp.360-368
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• 1988

A 14 to 14.5 GHz low noise MIC amplifier is designed on the $Al_2$$O_3$ substrate. The amplifier which uses a GaAsMESFET developed at COMSAT Laboratories has been designed and optivized to have gain greater than 7dB and noise figure less than 2dB using Super-Compact program. Experimental results show that the gain of the amplifier is 7 to 7.7 dB, while noise figure is 3.8 to 4.3dB through the desired band.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.1
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• pp.184-190
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• 2006

Using COMS which provides multi-beam switching function, the optimal transmission channel environments which provides the high data rate communication are proposed in this paper. Also the link budget for communication transponder of COMSAT is designed. Bsaed on the channel modeling for group delay, non-linear and gain flatness characteristics, the system performances which provide high data rate (HDR) service were analyzed in Ka-band satellite channel. As the transmission data rate is increased, the degradation due to these channel characteristics is severely affect the system performance. To efficiently provide the various service via the same transmission system it is necessary to equlize the primary impairment factors. The optimum operating points of HDR satellite transmission system are implemeted and operated by considering the analyzed results on channel characteristics.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.4
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• pp.2311-2314
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• 2016

Pistagremic acid (PA) is a bioactive triterpenoid isolated from various parts of Pistacia integerrima plants. The aim of this research was to investigate PA for reversion of multidrug resistant (MDR) mediated by P-glycoprotein using rhodamine-123 exclusion study on a multidrug resistant human ABCB1 (ATP-binding cassette, sub-family B, member 1) gene-transfected mouse T-lymphoma cell line in vitro. Results were similar to those with verapamil as a positive control. Docking studies of PA and standard Rhodamine123 were carried out against a P-gp crystal structure which showed satisfactory results. Actually, PA cannot bind exactly where co-crystallized ligand of P-gp is already present. However, the docking study predicted that if a compound gives a lesser score then it may have some potency. The docking scores of PA and Rhodamine were similar. Therefore, we can conclude that there are certain important chemical features of PA which are responsible for the inhibiting potency of P-gp.

• Journal of Communications and Networks
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• v.17 no.3
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• pp.247-255
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• 2015

In this paper, we propose an adaptive time division multiple access based medium access control (MAC) protocol, called bitmap-assisted shortest job first based MAC (BS-MAC), for hierarchical wireless sensor networks (WSNs). The main contribution of BS-MAC is that: (a) It uses small size time slots. (b) The number of those time slots is more than the number of member nodes. (c) Shortest job first (SJF) algorithm to schedule time slots. (d) Short node address (1 byte) to identify members nodes. First two contributions of BS-MAC handle adaptive traffic loads of all members in an efficient manner. The SJF algorithm reduces node's job completion time and to minimize the average packet delay of nodes. The short node address reduces the control overhead and makes the proposed scheme an energy efficient. The simulation results verify that the proposed BS-MAC transmits more data with less delay and energy consumption compared to the existing MAC protocols.

• Korean Journal of Remote Sensing
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• v.18 no.1
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• pp.53-59
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• 2002

The MSC is a payload on the KOMPSAT-2 satellite to perform the earth remote sensing. The instrument images the earth using a push-broom motion with a swath width of 15 km and a GSD(Ground Sample Distance) of 1 m over the entire FOV(Field Of View) at altitude 685 km. The instrument is designed to haute an on-orbit operation duty cycle of 20% over the mission lifetime of 3 years with the functions of programmable gain/offset and on-board image data compression/storage. The MSC instrument has one channel for panchromatic imaging and four channel for multi-spectral imaging covering the spectral range from 450nm to 900nm using TDI(Time Belayed Integration) CCD(Charge Coupled Device) FPA(Focal Plane Assembly). The MSC hardware consists of three subsystem, EOS(Electro Optic camera Subsystem), PMU(Payload Management Unit) and PDTS(Payload Data Transmission Subsystem) and each subsystems are currently under development and will be integrated and verified through functional and space environment tests. Final verified MSC will be delivered to spacecraft bus for AIT(Assembly, Integration and Test) and then COMSAT-2 satellite will be launched after verification process through IST(Integrated Satellite Test). In this paper, the introduction of MSC, the configuration of MSC electronics including electrical interlace and design of CEU(Camera Electronic Unit) in EOS are described. MSC Operation parameters induced from the operation concept are discussed and analyzed to find the influence of system for on-orbit operation in future.