• Journal of the Korea Society of Computer and Information
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• v.21 no.3
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• pp.83-89
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• 2016

Internet of Things (IoT) is widely used for biomechanics in sports activities and AHRS(Attitude and Heading Reference System) is a more cost effective solution than conventional high-grade IMUs (Inertial Measurement Units) that only integrate gyroscopes. In this paper, we attach the AHRS to the snowboard to measure the motion data like Air To Fakie, Caballerial and Free Style. In order to reduce the measurement error, we have adopted the sensors equipped with Kalman filtering and also used Euler angle to quaternion conversion to reduce the Gimbal-lock effect. We have tested and evaluated the accuracy and execution time of the pattern recognition algorithms like PCA, ICA, LDA, SVM to show the recognition possibility of it on the basic motions of Snowboarding from the 9-axis trajectory information which is gathered from AHRS sensor. With the result, PCA, ICA have low accuracy, but SVM have good accuracy to use for recognition of basic motions of Snowboarding.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.2B
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• pp.151-159
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• 2002

Frequency synthesizer is an essential part for developing high speed frequency hopping radio. A high speed synthesizer using DDS driven PLL technique is designed and implemented for a X-band portable satellite terminal. It generates transmitter and receiver frequency ranging 6600∼7100MHz and 6140∼6640MHz, respectively by using 102.4MHz local oscillator, Its lock time is below 15 $\mu$sec and Its phase noise is below -754dBc at 1KHz offset Sequency.

• Proceedings of the KIEE Conference
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• summer
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• pp.563-565
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• 2004

It is expected to reduce stresses to components of high voltage circuit breaker and transferred switching surge from power system by applying controlled switching technique to high voltage system. This technique has at ready been applied in advanced countries. In this paper, basic principle of controlled switching technique is set up and a device to realize this technique is under developing. Controlled switching device will be improved by applying a method minimizing errors of operating time and by adopting compensation function relative to changes of ambient/operating condition.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.231-233
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• 2009

The object recognition is one of the major computer vision fields. The object recognition using features(SIFT) is finding common features in input images and query images. But the object recognition using feature methods has suffered of difficulties due to heavy calculations when resizing input images and query images. In this paper, we focused on speed up finding features in the images. we proposed method using block segmentation and histogram. Block segmentation used diving input image and than histogram decided correlation between each 1]lock and query image. This paper has confirmed that tile matching time reduced for object recognition since reducing block.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.155-158
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• 1999

This paper describe the design and measurements of dual PLL for IMT-2000 cellular phone. As a result, dual PLL was well-operated in the RF frequency ranges of 2300 ~ 2360 MHz and If frequency of 380 MHz. The output power of -4.28 ㏈m, phase noise of -107.66㏈c/Hz at 100KHz frequency offset, lock time of 675.6$mutextrm{s}$ were obtained at 2330MHz. The output power of -4.78 ㏈m, phase noise of -115.28㏈c/Hz were also obtained at 380MHz.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.353-356
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• 1999

A 3.3V PLL(Phase Locked loop) is designed for a high frequency, low voltage, and low power applications. This paper proposes a new PLL architecture to improve voltage to frequency linearity of VCO(Voltage controlled oscillator) with new delay cell. The proposed VCO operates at a wide frequency range of 30MHz~1㎓ with a good linearity. The DC-DC voltage up/down converter is utilized to regulate the control voltage of the two-stage VCO. The designed PLL architecture is implemented on a 0.6${\mu}{\textrm}{m}$ n-well CMOS process. The simulation results show a locking time of 2.6$\mu$sec at 1Hz, Lock in range of 100MHz~1㎓, and a power dissipation of 112㎽.

• Journal of the Semiconductor & Display Technology
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• v.14 no.2
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• pp.35-40
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• 2015

This paper presents the sensorless position control of the Permanent Magnet Synchronous Motor (PMSM) using stator flux estimation and Phase Lock Loop (PLL). The field current and the torque current are required in order to perform the vector control of the PMSM. At this time, it is necessary for the torque to know the exact position of the magnetic flux generated by the permanent magnet, because the torque must be applied torque current in the direction orthogonal to the permanent magnet. In general the speed of the PMSM is controlled by using a magnetic position sensor. However, this paper, we estimates the stator flux by using the PLL method without the magnetic position sensor. This method is simple and easy, in addition it has the advantage of a stabile estimation of the rotor. Finally the proposed algorithm was confirmed by experimental results and showed the good performance.

• Journal of Magnetics
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• v.6 no.1
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• pp.27-30
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• 2001

We present a new procedure to evaluate the residual life of 1Cr-1Mo-0.25V steel from reversible magnetic permeability. The method is based on the existence of first harmonics in the differential magnetization around the coercive force. The apparatus is based on the detection of the voltage induced in a coil using a lock-in amplifier tuned to the frequency of the exciting coil. Results obtained for the first harmonics and Vickers hardness on aged samples show that the peak interval of reversible permeability and Vickers hardness decrease as aging time increases. The correlation between Vickers hardness and the peak interval of the reversible permeability may be used to evaluate the residual life of 1Cr-lMo-0.25V steel, nondestructively.

• Journal of the Korea Furniture Society
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• v.20 no.2
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• pp.122-135
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• 2009

The objective of this work was to research click profile of laminate flooring by comparison of click and bonding laminate floorings, especially base on the click profile shape, bonding strength and international patents. Non-glue locking system has been used since laminate flooring was developed. For the reason of environment and saving installation time, the manufacturer in Europe and USA has developed click profile for laminate flooring. Each manufacturer has patent on each click profile. Although each click profile has good lock strength as shape, Berryand Unilin company's click profile systems showed higher locking strength than others. Korean laminate flooring company pay the fee of patent for using European and American manufacturer's click profile. From this work, we grope Korean style laminate flooring and click profile through research on the click profile shape, bonding strength and patents of European and American manufacturers.

• Journal of Veterinary Clinics
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• v.31 no.1
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• pp.61-65
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• 2014

The study aimed at determining the feasibility of three portal totally Laparoscopic cryptorchidectomy in small breed dogs. Four right sided and one left sided abdomen retained testicles in five dogs weighing 2.2~8.7 kg were retrieved successfully. Pampiniform plexus and vas deference were ligated and transected with Hem-o-lock/monopolar electrocauterization (1/5), or ultrasonic scalpel (4/5) and the latter provided more easy, quick and safe hemostasis and transection. The resected testis was easily removed through a insertion site. Mean surgical time was $19.9{\pm}15.2$ minutes and when the abdominal cavity was explored again, there were no major complications. The patient recovered favorably without unwilling events. This is the case report of laparoscopic cryptorchidectomies in small breed dogs weigh less than 10 kg. Laparoscopic cryptorchidectomy could be considered as an alternative in small animal surgery.