• Journal of Korean Society of Forest Science
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• v.89 no.3
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• pp.405-413
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• 2000

This study was conducted to develop an on-line monitoring system for a forest hydrological environment and its meteorological condition, such as temperature, wind direction and speed, rainfall and water level on V-notch, electrical conductivity(EC), potential of hydrogen(PH) by the motor drive sensor unit and measurement with a single-chip microprocessor as controller. These results are summarized as follows ; 1. The monitoring system consists of a signal process unit, motor drive sensor unit, radio modem unit and power supply. 2. The motor drive sensor unit protects the sensor from swift current or freezing and can constantly maintain fixed water level during measurements. 3. This monitoring system can transfer the data by radio modem. Additionally, this system can monitor hydrological conditions in real time. 4. The hardware was made of several modules with an independent CPU. They can be mounted, removed, repaired and added to. Their function can be changed and expanded. 5. These are the result of an accuracy test, the values of temperature, EC and pH measured within an error range of ${\pm}0.2^{\circ}C$, ${\pm}1{\mu}S$ and ${\pm}0.1pH$ respectively. 6. This monitoring system proved to be able to measure various factors for a forest hydrological environment in various experimental stations.

• Journal of the Korean Magnetics Society
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• v.24 no.2
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• pp.60-65
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• 2014

We obtained resonance field ($H_{res}$) and linewidth (${\Delta}H_{PP}$) from measured ferromagnetic resonance signal in the functions of polar angle (${\Theta}_H$) in Ni thin film of 240 nm thickness fabricated by electrodeposition method. The angular dependence of $H_{res}$ was well fitted with the calculated ones. We confirmed that the g-factor and effective demagnetization field were 2.18 and 445 emu/cc by the theoretical analysis of the resonance field, respectively. The angular dependence of ${\Delta}H_{PP}$ showed very large values at in-plane direction (${\Theta}_H=90^{\circ}$), which could not explained by the homogenous linewidth due to the Gilbert damping and inhomogeneous linewidth due to the angular variations and magnetization variations by the surface layer. Therefore, we considered the spin wave scattering (two magnon scattering) process in order to analyze the measured inhomogeneous linewidth, which was appeared in thicker film than the critical thickness of 50 nm. The defect medicated spin wave scattering played a key role in the electrodoposited Ni thin film of 240 nm thickness.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.5
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• pp.66-79
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• 2009

In this paper, we propose a new adaptive intra coding technique using 1-D and 2-D integer transforms for improving coding efficiency of H.264/AVC. Proposed technique selects the most effective transform and prediction mode for each block after processing 1-D and 2-D transforms of all prediction modes. In case of using 1-D transform, $4{\times}4$ block is divided into four $1{\times}4$ or $4{\times}1$ subblocks and then each subblock is predicted and subtracted by using the decoded subblock located at the nearest position in the direction of prediction. After prediction error subblock is processed by 1-D transform and quantization, four subblocks are merged back into original $4{\times}4$ block and then, reordered as 1-D signal by a DC biased zigzag scanning pattern according to the prediction mode. Finally, comparing the coding efficiency between bitstreams based on 1-D transform and conventional 2-D transform, prediction mode and quantized coefficients for each block are decided and corresponding quantized coefficients are transmitted. Experimental results show that the proposed adaptive technique increases 0.34dB in BD-PSNR and decreases 4.03% in BD-Bitrate on the average compared with H.264/AVC.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.609-617
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• 2016

In general, Personal Navigation Systems (PNSs) can be defined systems to acquire pedestrian positional information. GPS is an example of PNS. However, GPS can only be used where the GPS signal can be received. Pedestrian Dead Reckoning (PDR) can estimate the positional information of pedestrians using Inertial Measurement Unit (IMU). Therefore, PDR can be used for GPS-disabled areas. This paper proposes a PDR scheme considering various movement types over GPS-disabled areas as combat environments. We propose a movement distance estimation scheme and movement direction estimation scheme as pedestrian's various movement types such as walking, running and crawling using IMU. Also, we propose a fusion algorithm between GPS and PDR to mitigate the lack of accuracy of positional information at the entrance to the building. The proposed algorithm has been tested in a real test bed. In the experimental results, the proposed algorithms exhibited an average position error distance of 5.64m and position error rate in goal point of 3.41% as a pedestrian traveled 0.6km.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.11
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• pp.821-827
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• 2018

In devices used for re-forming osteoblasts to treat osteoporosis, a magnetic field is applied from the outside of the bone, and the minerals contained in the bone are aligned in a certain direction and undergo precessional motion. When a $90^{\circ}$ RF pulse is applied by using an RF coil, protons of minerals are brought to an excited state, and phosphorus activity promoting the deposition of osteoblasts in the bone is increased, thereby reshaping the bone. Miniaturizing the RF coil that generates a signal corresponding to the harmonic of the precessional motional frequency by means of the $90^{\circ}$ RF pulse can drastically reduce the overall size of the bone reshaping system. In this study, we propose a methodology for the miniaturization of the RF coil that can be used for osteoblast re-formation using a bone reshaping system. The capacitance of the designed RF coil is 25 pF, the inductance is approximately 100 nH, and the resonance frequency is 96 MHz. The radius of the end ring of the designed RF coil is 18 cm, and the total length of the leg is $2{\times}11.6cm$. The performance of the coil is verified through post-design measurement.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.299-302
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• 2014

Due to the convergence between digital devices and the development of wireless communication technology, bit-signal sensor miniaturization, building an Electronic Medical Record (EMR) which is a digital version of a paper chart that contains all of a patient's medical history and the information of Electronic Health Record (EHR), Ubiquitous healthcare (u-Healthcare) that can monitor their health status and provide personal healthcare service anytime and anywhere. Also, the appearance of cloud computing technology is one of the factors that accelerate the development of u-healthcare service. However, if the individual information to be used maliciously during the u-healthcare service utilization, leads to serious problems directly related to the individual's life because if it goes beyond the level of simple health screening and treatment, it may not provide accurate and reliable healthcare services. For this reason, we analyzed a variety of security issues related to u-healthcare service in cloud computing environment and described about directions of secure health information sharing system construction. In addition, we suggest the future developmental direction for th activation of u-healthcare industry.

• The Journal of the Acoustical Society of Korea
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• v.38 no.4
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• pp.450-458
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• 2019

Passive cavitation imaging method is used to observe the ultrasonic waves generated when a group of bubbles collapses. A problem with passive cavitation imaging is a low resolution and large side lobe levels. Since ultrasound signals generated by passive cavitation take the form of a pulse, the amplitude distribution of signals received across the receive channels varies depending on the direction of incidence. Both the centroid and flatness were calculated to determine weights at imaging points in order to discriminate between the main and side lobe signals from the signal amplitude distribution of the received channel data and to reduce the side lobe levels. The centroid quantifies how the channel data are distributed across the receive channel, and the flatness measures the variance of the channel data. We applied the centroid weight and the flatness to the passive cavitation image constructed using the delay-and-sum focusing and minimum variance beamforming methods to improve the image quality. Using computer simulation and experiment, we show that the application of weighting in delay-and-sum and minimum variance beamforming reduces side lobe levels.

• Journal of the Korean Society of Radiology
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• v.16 no.3
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• pp.319-325
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• 2022

The Study In order to obtain a sharpness Image from Skull PA axial projection (Haas) in a head axial X-ray Examination, this study changed the posture angle using Skull Phantom and evaluated the image subjectively to 5 radiologists who worked in the Department of Imaging at University Hospital. In the prone position, the head was lowered 4 cm from the back of the head, entered 25° toward the head, and the image evaluation score was high with 20 points, such as the back bone, dorsum sellae projected in the large hole, and posterior clinoid process. In addition, the score significance was verified, and the Cronbach Alpha value was evaluated to have good reliability of 0.789. As a result of calculating the signal-to-noise ratio (SNR) by setting the region of interest (ROI) of the image, it was the highest at 5.957 for 25° incident at the back of the head and 6.430 for 30° incident at the back of the head. As a result of the study, in order to obtain a sharp image of the back of the head bone, dorsum sellae, and posterior clinoid process when shooting in the axial direction after the head, it is filmed by tilting 25° toward the head from 4 cm below the back of the head. In order to obtain a sharp image of rock pyramid symmetry, petrous ridge, sagittal suture, and lambdoid suture, it is thought that it will be helpful for clinical use if you shoot it 8cm down from the back of the head and tilt it 30° toward the head.

• Journal of the Korea Convergence Society
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• v.12 no.11
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• pp.99-107
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• 2021

We live in a myriad of data. Various data are created in all situations in which we work, and we discover the meaning of data through big data technology. Many efforts are underway to find meaningful data. This paper introduces an analysis technique that enables humans to make better choices through the trend and prediction of time series data as a principal component analysis technique. Principal component analysis constructs covariance through the input data and presents eigenvectors and eigenvalues that can infer the direction of the data. The proposed method computes a reference axis in a time series data set having a similar directionality. It predicts the directionality of data in the next section through the angle between the directionality of each time series data constituting the data set and the reference axis. In this paper, we compare and verify the accuracy of the proposed algorithm with LSTM (Long Short-Term Memory) through cryptocurrency trends. As a result of comparative verification, the proposed method recorded relatively few transactions and high returns(112%) compared to LSTM in data with high volatility. It can mean that the signal was analyzed and predicted relatively accurately, and it is expected that better results can be derived through a more accurate threshold setting.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.6
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• pp.241-249
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• 2022

This paper discusses the design of a ground clutter prevention fence for a radar wind profiler (RWP). The design point of the clutter fence is to improve the quality of the received signal by removing the non-weather clutter coming from the side. In this paper, a clutter prevention fence composed of a metallash mesh around the RWP is proposed, and the phase center of the antenna, the length, and height of the down fence, and the height and slop of the top fence through M&S are designed. The designed ground clutter prevention fence and 256 active phase array antennas were used as basic data. The effectiveness of the design was confirmed by a simulation. The side lobe in the ±90° direction was reduced by more than 30dB depending on the presence or absence of the designed ground clutter prevention fence. The fence was manufactured by 3D modeling, and the clutter shielding performance of approximately 20dB or more on the side of the antenna (±90°) was confirmed by applying it to the currently operated RWP.