• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.5
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• pp.504-514
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• 2014

An MMIC multi-function chip with a low DC power consumption for an X-band active phased array radar system has been designed and fabricated using a 0.5 ${\mu}m$ GaAs p-HEMT commercial process. The multi-function chip provides several functions: 6-bit phase shifting, 6-bit attenuation, transmit/receive switching, and signal amplification. The fabricated multi-function chip with a compact size of $16mm^2(4mm{\times}4mm)$ exhibits a gain of 10 dB and a P1dB of 14 dBm from 7 GHz to 11 GHz with a DC low power consumption of only 0.6 W. The RMS(Root Mean Square) errors for the 64 states of the 6-bit phase shift and attenuation were measured to $3^{\circ}$ and 0.6 dB, respectively over the frequency.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.12
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• pp.863-866
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• 2013

SiC crystal ingots were grown on 6H-SiC dual-seed crystals with different surface roughness and different seed orientation by a PVT (Physical Vapor Transport) method. 4H and 15R-SiC were grown on seed crystal with high root-mean-square (rms) value. The polytype of grown crystal on the seed crystal with lower rms value was confirmed to be 6H-SiC. On the other hand, all SiC crystals grown on seed crystals with different seed orientation were proven to be 6H-SiC. The surface roughness of seed crystals had no effect on the crystal structure of the grown crystals. However, the crystal quality of 6H-SiC single crystals grown on the on-axis seed were revealed to be slightly better than that of 6H-SiC crystal grown on the off-axis seed.

• Journal of Korea Water Resources Association
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• v.39 no.8 s.169
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• pp.659-668
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• 2006

The uncertainty of the risk of failure of hydraulic structures can be determined by estimating the variance of the risk of failure based on the methods of moments, probability weighted moments, and maximum likelihood assuming that the underlying model is the Gumbel distribution. In this paper, the variance of the risk of failure was derived. Monte Carlo simulation was peformed to verify the characteristics of the derived formulas for various sample size, design life, nonexceedance probability, and variation coefficient. As the results, PWM showed the smallest relative bias and root mean square error than the others while ML showed the smallest ones for relatively large sample siBes regardless of design life and nonexceedance probability. Also, it was found that variation coefficient does not effect on the relative bias and relative root mean square error.

• Journal of the Korea Concrete Institute
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• v.14 no.5
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• pp.677-688
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• 2002

A analytical model is developed which can simulate a complete inelastic biaxial moment-curvature relations of a reinforced concrete column. The model can simulate sudden drop in moment capacity after peak moment and due to spalling of cover concrete. Parametric studies are performed examine the effects of constituent material properties as well as topological arrangement of reinforcements on moment-curvature relations and P-M interaction curve. It has been analytically observed that ductility of a reinforced concrete column is influenced mostly by magnitude of the axial load and spacings or the volume of lateral reinforcements. Compared to ACI P-M interaction curve, overall increase about 10％ in square root of sum of squares of axial force and moment, and about 20％ in peak load are observed for the columns reinforced according to ACI seismic design code.

• Journal of Korean Medicine Rehabilitation
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• v.24 no.3
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• pp.121-130
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• 2014

Objectives The purpose of this study is to compare the effects of MET (muscle energy technique) and ICT (interferential current therapy) on lumbago by meridian muscle electrography (MMEG). We performed MET and ICT on quadratus lumborum muscle. Methods This study was carried out on 30 lumbago patients. 30 patients were randomly divided into MET group and ICT group. MET group take treatment 10 minutes. ICT group take treatment 15 minutes. After performing MET and ICT twice, we compared both in terms of root mean square (RMS), special edge frequency (SEF), VAS and ODI. Results 1. Both MET group and ICT group showed significant improvement in VAS and ODI after treatment. 2. Both MET group and ICT group showed significant improvement in special edge frequency (SEF) of the left side after treatment. But SEF of the right side showed insignificant improvement. 3. Both MET group and ICT group showed insignificant improvement in root mean square (RMS) for both sides. 4. There are no significant differences between both groups. Conclusions According to above results, we found out that performing MET or ICT on quadratus lumborum muscle has effect in terms of VAS and ODI. But, in terms of SEF, we found out different result for both side. And we can't found out effect in terms of RMS.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.4
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• pp.469-475
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• 2015

This paper describes about the method for designing an extended Kalman filter to accurately measure the position of the spatial-phase system using a semiconductor sensor. Spatial position is expressed by the correlation of the rotated coordinate system attached to the body from the inertia coordinate system (a fixed coordinate system). To express the attitude, quaternion was adapted as a state variable, Then, the state changes were estimated from the input value which was measured in the gyro sensor. The observed data is the value obtained from the acceleration sensor. By matching between the measured value in the acceleration sensor and the predicted calculation value, the best variable was obtained. To increase the accuracy of estimation, designation of the extended Kalman filter was performed, which showed excellent ability to adjust the estimation period relative to the sensor property. As a result, when a three-axis gyro sensor and a three-axis acceleration sensor were adapted in the estimator, the RMS(Root Mean Square) estimation error in simulation was retained less than 1.7[$^{\circ}$], and the estimator displayed good property on the prediction of the state in 100 ms measurement period.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.6
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• pp.108-116
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• 2008

In this paper, we propose an algorithm that can estimate the distance using disparity based on stereo vision system, even though the obstacle is located in long ranges as well as short ranges. We use sub-pixel interpolation to minimize quantization errors which deteriorate the distance accuracy when calculating the distance with integer disparity, and also we use enhanced adaptive fuzzy strong tracking Kalman filter(EAFSTKF) to improve the distance accuracy and track the path optimally. The proposed method can solve the divergence problem caused by nonlinear dynamics such as various vehicle movements in the conventional Kalman filter(CKF), and also enhance the distance accuracy and reliability. Our simulation results show that the performance of our method improves by about 13.5% compared to other methods in point of root mean square error rate(RMSER).

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.5
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• pp.217-221
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• 2003

In this work, chemical-solution derived silicate fibers were prepared by mixing tetraethyl orthosilicate, ethanol, distilled water, and hydrochloric acid in order to investigate surface roughness of fiber. Silicate fibers were drawn by using a viscous solution after evaporation at $80^{\circ}C$. The dried gel fibers were finally annealed at $1000^{\circ}C$, $1100^{\circ}C$, $1200^{\circ}C$ and $^1300{\circ}C$ for 60 min in dried air (flow rate = ∼200 ml/min). The crystallinity of the heat-treated silica fiber was analyzed by the X-ray diffraction $\theta$-2$\theta$ scan. A field emission-scanning electron microscope and an atomic force microscope were used to evaluate surface properties. The silicate fiber annealed at $1300^{\circ}C$ showed high value of root mean square roughness and had a relatively inhomogeneous surface structure.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.26 no.5
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• pp.493-504
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• 2008

Space-Based Augmentation System (SBAS), which is one of the GPS augmentation systems, is a Wide-Area Differential GPS that provides differential GPS corrections and integrity data. In this study, we did performance analysis of kinematic SBAS surveying by conducting Real-Time Kinematic (RTK), DGPS, standalone, and SBAS surveys. Considering static survey results as truth, 2-D Root Mean Square (RMS) error and 3-D RMS error were computed to evaluate the positioning accuracy of each survey method. As a result, the 3-D positioning error of RTK was 13.1cm, DGPS 126.0cm, standalone (L1/L2) 135.7cm, standalone (C/A) 428.9cm, and SBAS 109.2cm. The results showed that the positioning accuracy of SBAS was comparable to that of DGPS.

• The Journal of Korean Physical Therapy
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• v.18 no.2
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• pp.25-34
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• 2006

Purpose: This study conducted quantitative sensory test and nociceptive flexion reflex(NFR) measurement to examine degree of pain depending on polarity of high voltage pulsed current(HVPC) of hyperalgesia site in hyperalgesia rat by local thermal injury. mechanical pain threshold, thermal pain threshold and root mean square of NFR were measured. Methods: This study was conducted with control group I of hyperalgesia rat at hind paw by thermal injury and experimental groups divided into cathodal HVPC group II, anodal HVPC group III and alternate HVPC group IV. It measured pain threshold and root mean square(RMS) of NFR and obtained the following results. Results: Mechanical pain threshold of hyperalgeisa site was significantly increased at groups II, III and IV applying HVPC group compared to control group, but there was no difference among HVPC groups. Thermal pain threshold of hyperalgesia site showed a significant increase in group II. Group III showed significant difference after 4 days of hyperalgesia. RMS of NFR at hyperalgeisa site was significantly reduced in group II after 2 days of hyperalgesia. Group III showed significant decrease after 5 and 6 days of hyperalgesia. Conclusion: Consequently it was found that application of HVPC of hyperalgesia site increased pain threshold at hyperalgesia site by mechanical stimuli and thermal stimuli. NFR by electrical stimuli was similar to pain threshold by mechanical stimuli. Effects by polarity of HVPC showed the greatest reduction of hyperalgesia when cathodal electrode was used.