• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.9A
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• pp.755-761
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• 2005

In this paper, we proposed a channel estimation method by impulse signal train in OFDM. In order to estimate the channel response, 4 impulse signals are generated and transmitted during one OFDM (Orthogonal Frequency Division Multiplexing) symbol. The intervals between the impulse signals are all equal in time domain. At the receiver, the impulse response signals are summed and averaged. And then, the averaged impulse response signal is zero padded and fast Fourier transformed to obtain the channel estimation. The BER performance of the proposed method is compared with those of conventional estimation method using the long training sequence in fast fading environments. The simulation results show that the proposed method improves by 3 dB in terms of Eb/No, compared with the conventional method.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.104-104
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• 2003

As an effort to direct differentiation of human embryonic stem (hES, MB03) cells to dopamine-producing neuronal cells, Nurr1 was transfected using conventional transfection protocol into MB03 and examined the expression of tyrosine hydroylase (TH) after differentiation induced by retinoic acid (RA) and ascorbic acid (AA). Experimentally, cells were transfected with linearized Nurr1 cDNA in pcDNA3.1 (+)-hygovernight followed by selection in medium containing hygromycin-B (150 $\mu$/ml). Expression of Nurr1 mRNA was confirmed by RT-PCR and protein by immunocytochemistry in the drug resistant clones. In order to study the effect of Nurr1 protein on the differentiation pattern of ES cells, one of the positive clones (MBNr24) was allowed to form embryoid body (EB) for 2 days and were induced to differentiate for another 4 days using RA (1 $\mu M$) and AA (50 mM) (2-/4+ protocol) followed by selection in N2 medium for 10 or 20 days. After 10 days in N2 medium, cells immunoreactive to anti-GFAP, anti-TH, or anti-NF200 antibodies were 38.8%, 11%, and 20.5%, respectively. After 20 days in N2 medium, cells expressing GFAP, TH, or NF200 were 28%, 15% and 44.8%, respectively but approximately 9% of MB03 expressed TH protein when the cells were induced to differentiate using a similar prorocol, These results suggest that ectopic expression of Nurr1 enhances generation of TH+ cells as well as neuronal cells when hES cells were differentiated by 2-/4+ protocol.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.12
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• pp.3205-3214
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• 1996

In this paper, the microstrip phased array antennas with coupling-slots for the base station of mobile communication is proposed and anlyzed with accurate analysis method which is based on both reciprocity principle and full-wave analysis. The basis functions used for the numerical analysis are determined depending upon the accuracy, convergence properties of the solution, and the computation time. The patch uses 3 EB mode and the slot uses IPWS mode. The designed phased array antenna has 8 slot-coupled microstrip patch array elements and the beam scanning capability is obtained by using the 4-bit PIN-diode phase shifters as switching devices which are consisted of the loaded line phase shifters for 30.deg. and 60.deg. and the reflection type phase shifters for 90.deg. and 180.deg. repectively. The 4-bits phase shifters which aremade by connecting each phase shifter have about 2.deg.-3.deg. phase errors and their insertion loss are about 3dB for each phase state. The fabricated 8-element phased array antenna with 4-bits phase shifters provides 12.deg.-14.deg. beamwidths depending on the scanning angle and is capable of scanning its beam to .+-.45.deg. with 9.deg. intervals, and the gain 12dBi. The overall results show that the slot-coupled phased array antenna has great advantages of wideband, high gain and reduced spurious radiation. Also, the antenna can be made small and thin. Furthermore, the scanning property of this antenna allows for its application in several areas, such as mobile communication system and PCS.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.11 no.5
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• pp.38-59
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• 2008

This research has a meaning to provide basic data for eco-friendly way of district unit plans and ecological landscape planning by evaluation of biotope preservation value at the level of district unit and designating land development of the site, the whole area of Sinseo-dong (Dong-gu, Daegu metropolitan city) for research site. The summary of analysis result is as follows. As a result of classification of biotope types on the research site, it is divided into 11 biotope groups such as a residential biotope group and 51 specific biotope types which is subordinate to the groups. As a result of the first value assessment on classified biotope types, there are 16 types of natural rivers which is full of vegetation as a I class. Also it is analysed as 9 types of IIclass, 14 of IIIclass, 8 of IVclass, and 4 of Vclass. In particular, in light of a wildlife habitat, EB, in case of broad-leaved tree of mixed forest assessed as a II class, was classified into Iclass which is one-step upgraded as a final class with the analysis as there is a structural characteristic (more than 71% of low density, 50 years of age-class). As a result of second assessment, it is analysed that there are 17 special sites (1a,1b) and 33 special sites (2a, 2b, 2c) respectively for preservation of species and biotope. Particularly, in case of the No. 27 space, it was assessed that it has the value of about medium (IIIclass) level, but its value was upgraded with the on-spot detailed investigation that most of Aristolochia contorta, designated as a rare plant by Ministry of Environment, is growing. It is regarded that the above-mentioned research result on evaluation of biotope preservation value is expected to provide very important basic materials for future district unit plans and smooth integration with landscape ecology plans and eco-friendly space development.