• Development and Reproduction
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• v.7 no.2
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• pp.119-126
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• 2003

In the previous study, we obtained list of differentially expressed genes between postnatal day 1 and day 5 mouse ovaries using suppression subtractive hybridization(SSH) and found that MT Oansposon-like element, clone MTi7(MTi7) was one of the highly expressed genes in the day 5 mouse ovary(Park et at., 2002). Results of in situ hybridization and RNA interference revealed that the expression of MTi7 is oocyte-specific in the ovary and may be involved in the regulation of oocyte maturation(Park et at., 2003). At present, MTi7 sequence has been known only in the mouse. Therefore, the present study was accomplished 1) to identify MTi7 sequence in the other mammalian species, such as bovine, porcine, rat, and human, and 2) to evaluate the flanking sequence of the mouse MTi7 since it has transposon characteristics. Using ovarian cDNAs derived from low different species, we cloned and identified new MTi7 sequence showing a high degree of sequence homology with the mouse MTi7(87∼98%). By using inverse PCR, we found that the mouse MTi7 may intercalated the beta-carotene 15, 15'-monooxygenase(Bcdo) gene and/or serine protease inhibitor, Kunitz Dpe I(Spint 1) gene. By finding the MTi7 sequences in the other mammalian species and the flanking gene of the MTi7 in mouse, it is expected to reveal the role(s) of MTi7 in the oogenesis as well as folliculogenesis in the near future.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.10 no.2
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• pp.82-87
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• 1985

The performance comparison method against ground clutter, when the trasnfer function of MTI filter or integrator is given, is considered for the MTI signal processors using a constant PRF. The MTI signal processors are modelled as the transversal filters, and the ground clutter power density spectrum as Gaussian type and the performance of the MTI signal processors are compared by calculating the MTI improvent factors. The MTI imrpovement factors versus normalized spectral width is depicted as examples for the MTI filters, the integrator using Hanning weighting function and the cascading of the two.

• Clinical and Experimental Reproductive Medicine
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• v.30 no.4
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• pp.299-307
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• 2003

Objectives: The present study was conducted to evaluate the mobile transposon-like element, clone MTi7 (MTi7) expression in the mouse ovary and to determine its role(s) in the mouse oocytes by RNA interference (RNAi). Methods: MTi7 mRNA expression was localized by in situ hybridization in day5 and adult ovaries. Double stranded RNA (dsRNA) was prepared for c-mos, a gene with known function as control, and the MTi7. Each dsRNA was microinjected into the germinal vesicle (GV) stage oocytes then oocyte maturation and intracellular changes were evaluated. Results: In situ hybridization analysis revealed that MTi7 mRNA localized to the oocyte cytoplasm from primordial to preovulatory follicles. After dsRNA injection, we found 43-54% GV arrest of microinjected GV oocytes with 68%-90% decrease in targeted c-mos or MTi7 mRNA. Conclusions: This is the first report of the oocyte-specific expression of the MTi7 mRNA. From results of RNAi for MTi7, we concluded that the MTi7 is involved in the germinal vesicle breakdown in GV oocytes, and MTi7 may be implicated with c-mos for its function. We report here that RNAi provides an outstanding approach to study the function of a gene with unknown functions.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.3
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• pp.299-311
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• 2011

In this paper, we have identified the system instability factors in a bistatic radar system using pulse chasing and considered their effects on the bistatic receiver's MTI(Moving Target Indication) improvement performance. The pulse chasing is a scan method that searchs a restricted area on the transmit pulse-to-pulse basis and the MTI filter is a signal processing that separates a target from some kinds of interferences such as clutter using small number of transmit pulses. Ideal MTI processing performance, e.g., clutter attenuation and improvement, has been limited by the property of the clutter itself, however, the MTI performance in a proposed bistatic receiver configuration could be affected by the receiving beam pointing error during pulse chasing scanning. Also, for the bistatic receiver, we have defined other system instability factors, which result from the time synchronization error, COHO's phase error, the frequency/phase synchronization error, and have analyzed their effects on the system performance improvement.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.11a
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• pp.169-171
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• 2007

We need two operation modes to obtain the complex hologram without bias and the conjugate image in the modified triangular interferometer(MTI). To solve the problem, we proposed the optimized MTI with one wave plate, which can obtain cosine and sine functions by the combination of one wave plate and one linear polarizer. In the extraction of phase term using the combination of polarization components, the phase error occurs, and we simulated such potential phase errors in the optimized MTI.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.10 no.2
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• pp.88-92
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• 1985

The performance of MTI signal processors against composite clutter depends not only on the power density functions of the clutter spectrum, but also on the average radar cross sections and the average doppler frequencies of each clutter. In this paper the effect of composite clutter composed of different kinds of clutter such as ground and weather on the MTI signal processors, is compared in terms of MTI improvement factors and the method of comparison is provided.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.7
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• pp.576-585
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• 2014

In this paper, we survey the Moving Target Indication(MTI) techniques for small UAVs. MTI consists of image alignment phase and frame differencing correction phase, and image alignment has two ways of parametric approach which is mainly focused in this paper and non-parametric approach. Since small UAVs are operated in the low altitude, the parallax is considerable and the epipolar geometry is applied to compensate the parallax. The related works and future works are presented.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.10
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• pp.1077-1083
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• 2009

To reject the Doppler frequency spectrum dispersion of clutter caused by high-speed antenna rotation of MTI radar system due to terrain characteristics, signal processing parameters(MTI filter constant, M/N detector ration, K-factor and offset of CFAR) are adjusted for the optimal elimination of the ground clutter. For this investigation, logging equipment is designed and utilized for the collection of classified ground clutter data. Test case is devised through Matlab simulation for the classified analysis and optimization of clutter rejection. Then indoor radar test and outside test in accordance with terrain characteristics are repeatedly performed for the verification of the test. This whole process is through the evolutional development model and repeated for the optimization. Final result is that ground-clutter rejection capability is 5.6 times(7.5 dB) better than that of existing radar system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.1
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• pp.47-58
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• 2011

MTI filter is used to separate target signal from clutter in many radar signal processing. By suppressing clutter before CFAR detection, the detection performance can be improved. As a radar system designed, a design engineer generally takes averaged SNR and CNR into account and does not include the effect of MTI filter's frequency response. In practice, when the signals including clutter are pass through the filter, SNR is widely varying according to target velocity and CNR is also varying according to clutter center frequency and spectrum spreading. In this paper, we have derived the relationship between the MTI filter's frequency response and a target's velocity and a clutter's spectrum characteristics. With the variation of SNR and CNR at the filter output, the detection performance of CFAR has been analyzed by the simulation and has made certain of their influences on the performance.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.1
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• pp.10-18
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• 2007

We synthesize and analyze the optical transfer function(OTF) of the modified triangular interferometer(MTI) using two-pupil synthesis method and we present the optimal MTI, which can obtain any bipolar function by combining a wave plate and a linear polarizer. Also, we analyze its potential phase error sources caused by polarization components.