• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.9
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• pp.707-721
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• 2018

In this paper, a small synthetic aperture radar(SAR) system with 30 cm resolution is proposed, and a RAW data-based Doppler parameter estimation and motion compensation algorithm is described in detail. Acquisition of both PolSAR and InSAR data are enabled because there are two channels each in the transmitter and receiver modules. Automotive-based field work is performed to obtain PolSAR data, and signal processing results are ultimately obtained. A motion compensation algorithm is used to mitigate the residual phase error due to platform oscillation, and improved performance is obtained with the motion compensation algorithm using the automotive field test data.

• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.56-62
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• 2008

Characteristics of heat transfer were investigated in a three-phase swirling fluidized bed whose diameter was 0.102 m and 2.5 m in height. Effects of gas and liquid velocities, particle size and liquid swirling ratio ($R_S$) on the immersed heater-to-bed overall heat transfer coefficient were examined. The heat transfer characteristics between the immersed heater and the bed was well analyzed by means of phase space portraits and Kolmogorov entropy(K) of the time series of temperature difference fluctuations. The phase space portraits of temperature difference fluctuations became stable and periodic and the value of Kolmogorov entropy tended to decrease with increasing the value of liquid swirling ratio from 0.1 to 0.4. The value of Kolmogorov entropy exhibited its minimum with increasing liquid swirling ratio. The value of overall heat transfer coefficient (h) showed its maximum with the variation of liquid velocity, bed porosity or liquid swirling ratio, but it increased with increasing gas velocity and particle size. The value of K exhibited its maximum at the liquid velocity at which the h value attained its maximum. The overall heat transfer coefficient and Kolmogorov entropy were well correlated in terms of dimensionless groups and operating variables.

• Investigative Magnetic Resonance Imaging
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• v.14 no.2
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• pp.115-120
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• 2010

Purpose : To separate and evaluate the low frequency spontaneous fluctuation BOLD signals from the functional magnetic resonance imaging data using sensorimotor active task. Materials and Methods : Twenty female archery players and twenty three control subjects were included in this study. Finger-tapping task consisted of three cycles of right finger tapping, with a subsequent 30 second rest. Blood oxygenation level-dependent (BOLD) data were collected using $T2^*$-weighted echo planar imaging at a 3.0 T scanner. A 3-D FSPGR T1-weighted images were used for structural reference. Image processing and statistical analyses were performed using SPM5 for active finger-tapping task and GIFT program was used for statistical analyses of low frequency spontaneous fluctuation BOLD signal. Results : Both groups showed the activation in the left primary motor cortex and supplemental motor area and in the right cerebellum for right finger-tapping task. ICA analysis using GIFT revealed independent components corresponding to contralateral and ipsilateral sensorimotor network and cognitive-related neural network. Conclusion : The current study demonstrated that the low frequency spontaneous fluctuation BOLD signals can be separated from the fMRI data using finger tapping paradigm. Also, it was found that these independent components correspond to spontaneous and coherent neural activity in the primary sensorimotor network and in the motor-cognitive network.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.711-712
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• 2012

• 주택과사람들
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• s.199
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• pp.36-39
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• 2006

베트남이 WTO에 가입함으로써 향후 베트남 부동산 시장은 한 번 더 요동을 칠 것으로 보인다. 호치민 등 도심을 중심으로 빈 사무실을 찾아보기 힘들 정도를 오피스 수요가 많고 이에 따라 상류층과 주재원들이 거주하는 고급 아파트 시장도 함께 급성장하고 있다. 아시아의 작은 별, 베트남의 떠오르는 부동산 시장을 살펴본다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.97-98
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• 2009

• Digital Contents
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• no.8 s.87
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• pp.85-89
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• 2000

네트에 의해서 팽대해진 정보가 유통하게 되자 전체를 환원주의적인 요소로 분해하고, 이를 정비해서 생각하려는 사고방식이 생겨났습니다. 즉 정보가 너무나도 많으면 대상이 복잡해서 혼돈의 상태가 되어 이제까지의 사고 방식으로는 도무지 어찌할수 없게 됩니다. 혼돈을 구성하는 개개의 요소는 각기 독립해 있어 서로 관계를 맺고 개개가 전체를 바라보면서 결합해가는 공명관계가 생기게 됩니다. 그러면 일종의 요동현상이 일어나서 하나의 구조인 자기조직화가 일어난다는 논리가 있습니다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.5
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• pp.366-374
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• 2018

In cases of airborne equipped with SAR, because the occurrence of motion is inevitable, it is necessary to apply autofocus techniques to SAR images to improve the image performance degradations caused by residual errors. Herein, a robust autofocus algorithm based on the minimum entropy criteria is proposed for the real SAR data in the spotlight mode. The convergence condition of the phase error estimation is checked at every iteration and if it is violated, the size of the phase error estimation is adjusted to the convergence condition. The real SAR raw data is used to demonstrate the excellent performance of the proposed algorithm.

• Journal of the Korean Vacuum Society
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• v.14 no.1
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• pp.7-16
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• 2005

Oil-Hydraulic pump consisting of swing twin-cylinder becomes to be used as a next generation of low vacuum pump. However, there is no enough flow-analysis for design improvement. It is essential to develope a numerical method for flow-analysis before manufacturing, in economic sense. Using a commercial code (Fluent), developed for flow-analysis, useful informations for design of pump were provided. Two-dimensional analysis has been performed to investigate the flow parameters such as pressure and velocity distributions between the swing twin-cylinder and the fixed cylinder. This numerical method will be used to design a better performance of pump consisting of swing twin-cylinder.

• Korean Journal of Optics and Photonics
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• v.5 no.2
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• pp.245-251
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• 1994

The charateristics of switching between two modes in a ring dye laser has been analyzed by the Monte-Carlo computer simulation. The effect of including pump fluctuations in the first-passage-time (FPT) distributions was compared with the distribution with the quantum fluctuation. The results show the same tendency in both cases, such as steep increases from 0 to peak an exponential decrease in long time range. However the introduction of pumping fluctuation is turned out to shorten the mean FPT. The variation of the mean FPT is examined for the various fluctuationrelated parameters. The mean FPT is lengthened when pump parameter a is increased while it is shorted when Q. $\GAMMA$ are decreased. eased.