• Economic and Environmental Geology
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• v.54 no.6
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• pp.615-627
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• 2021

The Baekildo fault, a dextral strike-slip fault developed in Baekil Island, Goheung-gun, controls the distribution of tuffaceous sandstone and lapilli tuff and shows a complex fracture system around it. In this study, we examined the spatial variation in the geometry and connectivity of the fracture system by using circular sampling and topological analysis based on a detailed fracture trace map. As a result, both intensity and connectivity of the fracture system are higher in tuffaceous sandstone than in lapilli tuff. Furthermore, the degree of the orientation dispersion, intensity, and average length of fracture sets vary depending on the along-strike variation in structural position in the tuffaceous sandstone. Notably, curved fractures abutting the fault at a high angle occur at a fault bend. Based on the detailed observation and analyses of the fracture system, we conclude as follows: (1) the high intensity of the fracture system in the tuffaceous sandstone is caused by the higher content of brittle minerals such as quartz and feldspar. (2) the connectivity of the fracture system gets higher with the increase in the diversity and average length of the fracture sets. Finally, (3) the fault bend with geometric irregularity is interpreted to concentrate and disturb the local stress leading to the curved fractures abutting the fault at a high angle. This contribution will provide important insight into various geologic and structural factors that control the development of fracture systems around faults.

• Journal of Aerospace System Engineering
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• v.16 no.6
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• pp.1-7
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• 2022

A simulated radar terrain scan data generation method is employed for terrain following. This method scans the discrete terrain by sequentially radiating beams from the radar to the desired scan area with the same azimuth but varying elevation angles. The terrain data collected from the beam is integrated to generate the simulated radar terrain scan data, which comprises radar-detected points. However, these points can be located far from the beam centerline when the radar is far from them due to beam divergence. This paper proposes a geometry-based terrain scan data generation method for analysing simulated radar terrain scan data. The method involves detecting geometric points along the beam centerline, which forms the geometry-based terrain scan data. The analysis of the simulated radar terrain scan data utilising this method confirms that the beam width effects are accounted for in the results.

• Journal of IKEEE
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• v.9 no.2 s.17
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• pp.136-142
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• 2005

This paper describes some major schemes for developing timing signal generator which can be used for testing of 3D radars. The developed generator has a function not only to simulate information on elevation angle for the simulated target signals but also to generate a modulated signal up to 80MHz. Because this generator has an internal modulating function instead of an external modulating function and has sufficient memory enough to change the parameters according to operating programs, it realization of various test-environments for testing a radar can be made with easy and with low expense.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.70-70
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• 2003

금속용액을 이용하여 측면고상결정화 시킨 다결정 실리콘 박막내의 고각입계를 줄이기 위해 서 고온열처리를 실시하였다. SEM과 TEM을 이용하여 다결정 실리콘내의 바늘모양의 결정립의 폭의 증가를 관찰하였고, 결정 립내의 결함이 감소를 관찰하였다. 그리고 결정화된 다결정 실리콘의 표면 거칠기를 AFM이용하여 퍼니스에서 53$0^{\circ}C$에서 25시간 동안 결정화 시킨 시편과 이후 80$0^{\circ}C$에서 40분간 추가 고온 열처리시킨 시편을 비교한 결과 6.09$\AA$에서 4.22$\AA$으로 개선되었음을 확인할 수 있었다. 박막내의 금속에 의한 오염을 줄이기 위해 금속의 농도를 줄인 금속용액을 결정화에 사용하였다. 이때 저농도 금속용액을 사용하여 측면결정화시킨 다결정 실리콘 박막내의 소각입계를 이루는 결정립군의 크기가 고농도 금속용액을 이용하여 측면결정화시킨 경우보다 증가함을 확인 할 수 있었다. 박막트랜지스터를 제작하여 트랜지스터의 전기적특성을 살펴보았다. 전계이동도가 80$0^{\circ}C$ 고온 열처리에 의해서 53$\textrm{cm}^2$/Vsec 에서 95$\textrm{cm}^2$/Vsec 로 상승하였는데 이는 고온열처리에 의해서 측면결정화된 다결정 실리콘내의 트랩 밀도가 2.2$\times$$10^{12}$/$\textrm{cm}^2$ 에서 1.3$\times$$10^{12}$$\textrm{cm}^2$로 감소하였기 때문이다.

• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.1
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• pp.52-58
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• 2020

In this paper, a 2-dimensional phase comparison direction finding receiver was designed and fabricated. For 2-D comparison direction finding, direction finding formulas were derived from a uniformly arranged of four antennas. Based on this, a direction finding receiver was designed using Matlab simulink, and the direction finding receiver was fabricated. To analyze the performance of the designed direction finding receiver, the injection direction finding accuracy and simulation results were compared. As a result of the test, the fabricated direction finding receiver showed a maximum of 3° RMS precision, and the result of both tests showed similar trends. Also, it was confirmed that the direction finding accuracy of elevation angle is about 2.7 times better than azimuth angle, and both models performed well within 0.7° RMS at the boresight.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.8
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• pp.693-700
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• 2016

In this paper, it is represented that equations for design of linear interferometer antenna when the 3 dB beamwidth is only region of interest. Using the equations, relationships between angle measurement ambiguity and element antenna spacings are described. And then, operating frequency, angle measurement accuracy, beamwidth, correct measurement probability are calculated for five antennas interferometer to measure azimuth and elevation angle. The interferometer antenna was designed and fabricated using the calculated parameters. The angle measurement accuracy were $0.01^{\circ}$ and $0.016^{\circ}$ for azimuth and elevation axes with 99 % probability of doing measurements correctly which means that ambiguous solution did not occur more than 1 % of the time. These results validated the equations and design procedures.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.9
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• pp.125-131
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• 2015

The simulation programs with the kalman filter for the naval Electro Optical Tracking System(EOTS) is presented. We achieve that the dependency tracking aiming systems performance of EOTS can be enhanced by minimizing the target information error which including transfer delay and measurement. According to our experiment results, kalman filter can be used for various electro optical systems to eliminate error value.

• The Journal of the Acoustical Society of Korea
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• v.19 no.1
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• pp.61-66
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• 2000

In this paper, we are proposing an efficient 3D source localization algorithm using 3 uniform linear subarrays. The proposed algorithm replaces 3D search required in conventional 3D MUSIC algorithm with 3 1D searches, and thus reduces computational burden. The estimate of the 1D conic angle obtained from a subarray under the far-field assumption satisfies a nonlinear algebraic equation of the true source bearing angle, elevation angle, and range. The proposed algorithm estimates source location by solving 3 algebraic equations obtained from 3 subarrays. Comparing 3D MUSIC spectrums of the estimated source locations, the proposed algorithm solves pairing problem for multiple sources localization.

• The Journal of the Acoustical Society of Korea
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• v.35 no.1
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• pp.35-41
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• 2016

Based on correlation and least square method, a closed-form algorithm for estimating the location of mixed far-field and near-field source is presented using the Uniform Circular Array (UCA). Recently, for a homogeneous circular arrangement case, a correlation based closed-form algorithm is proposed to estimate 2-D angle (azimuth, elevation) and the extended algorithm is proposed to 3-D location (azimuth, elevation, range). These algorithms assume the far-field source or near-field source only. Therefore, for mixed source localization, the proposed algorithm estimates source location with the assumption of far-field source, and then estimates the range to distinguish the far-field from the near-field source. For both cases, numerical experiments have been performed, which confirmed the validity of the proposed algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10A
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• pp.988-995
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• 2006

In this Paper, we Present a nonharmonic may geometry design method using Euclidan minimum distance function in difference Phase spaces for 2-D (azimuth/elevation) multiple baseline antenna may which has a way to reduce the number of sensor antennas while maintaining accurate DOA estimate. The major advantages of our approach is that even the shortest interelement spacing can be larger than half-wavelength and is not limit13d to linear and it can be applied successfully to any array configuration. In multiple signals impinging situation, the performance simulation results of superresolution algorithms shows the effectiveness of the proposed method. Also the 2-D asymmetric may using the Proposed method is designed and the Performance of the manufactured away through the experimental test is verified.