• Journal of Veterinary Clinics
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• v.32 no.2
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• pp.162-167
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• 2015

Tei-index has been reported as one of reliable echocardiographic factors for evaluating cardiac function in human and small animals. In this study, Tei-index were measured and evaluated with other echocardiographic parameters in normal thirteen beagle dogs and thirty-one dogs with mitral valve degeneration. Normal range of Tei index with tissue Doppler obtained at septum and left ventricular free wall was $0.58{\pm}0.07$ and $0.60{\pm}0.07$, respectively. The values between septum and left ventricular free wall did not show significant difference. Tissue Doppler derived tei index showed better reproducibility and significantly lower values than the results obtained by pulsed wave Doppler. Tei index obtained in either method increased with the progression of clinical signs. Therefore, the increase of Tei index in dogs with mitral regurgitation is thought to be an useful factor reflecting left ventricular dysfunction.

• Journal of the Korean Vacuum Society
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• v.19 no.3
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• pp.169-176
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• 2010

Cryopumps can provide economical profits with a relatively high pumping speed per size. However, it is somewhat doubtful that pumping performance of cryopums, which is very sensitive to the temperature of the adsorption panel, can be maintained or recovered fast for large continuous or impulsive gas loads. The official evaluation items indicating cryopump performance for gas loads are the maximum throughput and the crossover value. There are two other, unofficial but widely used, items, the Ar recovery time and gulp characteristics. Although these evaluation items look absolutely different with each other, there are close relations and even duplications in their test schemes. Therefore, it is necessary to study how to improve practically each test procedure, and combine or unify some procedures.

• Journal of the Korean Society of Hazard Mitigation
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• v.6 no.3 s.22
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• pp.17-28
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• 2006

Structural health monitoring is important to maintain the safety and serviceability of the structures. The displacement in the structure should be precisely and frequently monitored because it is a direct assessment index indicating its stiffness. However, no practical method has been developed to monitor such displacement precisely, particularly for high-rise buildings and long span bridges because they cannot be easily accessible. To overcome such difficult accessibility, we propose to use a LIDAR system that remotely samples the surface of an object using laser pulses and generates the coordinates of numerous points on the surface. In this study, using terrestrial LiDAR, we develop a novel displacement measuring model for structural health monitoring and perform an indoor experiment to prove its performance.

• Korean Journal of Remote Sensing
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• v.33 no.3
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• pp.313-324
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• 2017

A lava tube is one of the hot issues of lunar science because it is regarded as a good candidate place for setting a lunar base. Recently much effort has been made to find lunar lava tubes. However, preceding works mainly made use of high-resolution lunar surface image data in conjunction with geomorphological consideration to present some lava tube candidates. Yet, those candidates stay no more than indirect indications. We propose a new data analysis technique of High Frequency (HF) radar observation data to find lunar lava tubes of which location depth is smaller than the range resolution of the radar pulse. Such shallow target echoes cannot be resolved from surface echoes, which presents the different location of the lunar surface compared to that of real lunar surface. The proposed technique instead finds the surface range (distance from LRS to the reflector of the most intense signal) anomaly which occurs as a result of the low range resolution of LRS pulse. We applied this technique to the surface range of Kaguya Lunar Radar Sounder (LRS) data. The surface range was deduced to make LRS surface elevation which was compared with the average surface elevation of Kaguya Digital Terrain Model (DTM). An anomalous discrepancy of the surface elevation was found in the Rima Galilaei area, which suggests the existence of a shallow lava tube.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.6
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• pp.169-180
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• 2018

White light-emitting diodes (LEDs) are more economical than fluorescent lights, and provide high brightness, a high lifetime expectancy, and greater durability. As LEDs are closely connected with people's daily lives, dimming control of LED is an important component in providing energy savings and improving quality of life. In visible light communications systems using these LEDs, multiple input multiple output (MIMO) technology has attracted a lot of attention, in that it can attain the channel capacity in proportion to the number of antennas. This paper analyzes the power performance of three kinds of modulation in visible light communications (VLC) systems applied space-time block code (STBC) techniques. The modulation schemes are return-to-zero on-off keying (RZ-OOK), variable pulse position modulation (VPPM), and overlapping pulse position modulation (OPPM), and dimming control was applied. The power requirements and power consumption were used as metrics to compare the power efficiency in $2{\times}2$ STBC-VLC environments under the three kinds of modulation. We confirm that dimming control affects the communications performance of each modulation scheme. VPPM showed greater consumption among the three modulations, and OPPM showed energy savings comparable to VPPM.

• Progress in Medical Physics
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• v.7 no.1
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• pp.37-52
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• 1996

Image-guided localized, water-suppressed in vivo $^1$H MR spectroscopic studies were performed on the patients with brain tumors, acute cerebral infarction and schizophrenia, and dogs. GE Signa 1.5 T whole-body MRI/MRS system using STEAM pulse sequence was used. Proton metabolite ratios relative to creatine (Cr) were obtained using a Marquart algorithm. In vivo $^1$H MR spectra in brain neoplastic tissues revealed the changes of signal intensities of N-acetylaspartate (NAA), choline (Cho) and lactate (Lac) resonances. The present results suggest that the observed metabolite alterations from localized, water-suppressed in vivo $^1$H MR spectroscopy can be useful as an index of brain tumors, cerebral infarction and schizophrenia, and provide good quality metabolic information of cerebral tissue in the field of thanato-chronology.

• Journal of the Korea Society for Simulation
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• v.28 no.3
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• pp.75-82
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• 2019

A Satellite Communication (SATCOM), which is applied to various systems to communicate with other systems at the limited wired communication situation, is required to head at a stable point of the space, because this system uses a geostationary satellite. It is important to know satellite tracking heading angles such as elevation angle and azimuth angle for the immovable antenna's latitude, longitude, and altitude. Moreover, calculation of heading angle is critical for SATCOM antenna on a moving platform. In this study, a antenna heading angle calculation method is applied to compute elevation and azimuth angle for a SATCOM antenna and the heading angle simulation is executed for the Korea peninsula and surrounding areas. To verify this simulation, satellite tracking test is conducted using a SATCOM antenna which uses monopulse signal tracking method. The simulation is confirmed by comparing this test result with the simulation. And we make a suggestion for calculation of polarization angle of this antenna.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.8
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• pp.444-451
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• 2016

Most research on membrane fouling models in the past are based on theoretical equations in lab-scale experiments. But these studies are barely suitable for applying on the full-scale spot where there is a sequential process such as filtration, backwash and drain. This study was conducted in submerged membrane system which being on operation auto sequentially and treating wastewater from G-water purification plant in Incheon. TMP had been designated as a fouling indicator in constant flux conditions. Total volume of inflow and SS concentration are independent variables as major operation parameters and time-series analysis and prediction of TMP were conducted. And similarity between simulated values and measured values was assessed. Final prediction model by using genetic algorithm was fully adaptable because simulated values expressed pulse-shape periodicity and increasing trend according to time at the same time. As results of twice validation, correlation coefficients between simulated and measured data were $r^2=0.721$, $r^2=0.928$, respectively. Although this study was conducted limited to data for summer season, the more amount of data, better reliability for prediction model can be obtained. If simulator for short range forecast can be developed and applied, TMP prediction technique will be a great help to energy efficient operation.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.3
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• pp.194-201
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• 2014

This paper is able to be solved by improving degradation in multi-path environment by adjust beam pattern angle through modifying pulse phase of each antennas by using TRM (Transmitter Receiver Module). Beam Scanning Array Antenna, which is transmitter/receiver that improves degradation in multi-path environment without any signal distortion, is designed and manufactured. Beam Scanning Array Antenna should be able to send/receive signal at the antenna's longitudinal part without distortion and should not influences other systems. Also, it should include target detecting ability by beam steering.Dispersion characteristic of Beam Scanning Antenna, which is designed, is analysed by using fidelity, and steering and radar resolution performance is verified by using $1cm{\times}1cm$ sized target. To manufacture Beam Scanning Array Antenna, control board and GUI, which is able to control Vivaldi Antenna for IR-UWB, Tri-Band Wilkinson power divider, and TRM (Transmitter Receiver Module), is designed. Throughout this research, developed Beam Scanning UWB Array Antenna system is adoptable for radar application field. and time domain analysis techniques by using network analyser made the antenna characteristics analysis for setting up antenna more accurate. In addition, it makes beam width checking without difficulties.

• Progress in Medical Physics
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• v.26 no.1
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• pp.1-5
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• 2015

The C-band compact linear accelerator (linac) is being developed at Dongnam Institute of radiological & Medical Sciences (DIRAMS) for medical and industrial applications. This paper was focused on the output measurement of the electron beam generated from the prototype electron linac. The dose rate was measured in unit of cGy/min per unit pulse frequency according to the IAEA TRS-398 protocol. Exradin-A10 Markus type plane parallel chamber used for the measurement was calibrated in terms of dose to water at the reference depth in water. The beam quality index ($R_{50}$) was determined by the radiochromic film with a solid water phantom approximately due to low energy electrons. As a result, the determined electron beam output was $17.0cGy/(min{\cdot}Hz$. The results were used to monitor the accelerator performance during the development procedure.