• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.6
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• pp.162-170
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• 2010

The torque-coefficient of torque-shear type high-strength bolts is affected by the environmental factors, such as 'wet', 'rust', 'exposure to air' and workability during tightening high strength bolts. It is difficult to assume the direct tension induced into the bolt due to variation of torque-coefficient for torque-shear type high-strength bolts. Therefore, it is essential to measure tension loads of bolts and to verify the clamping force under construction. In this study, the manufacture of trial product was planned to identify the induced force into the bolts. The algorithm for a trial product was composed of the relation between electricity energy taken from torque shear wrench and tension force from hydraulic tension meter. The regression analysis equation to measure the direct tension was derived by statistical analysis using Minitab program. It is considered that the trial product is reliable tool to evaluate the tension force comparable to a commercial torque wrench.

• Journal of the Korean Electrochemical Society
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• v.10 no.1
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• pp.20-24
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• 2007

Lithium ion secondary battery has been applied widely to portable devices, and has been studied for application to high power electric cell system such as power tool or hybrid electronic vehicle. The structure change of the electrodes materials occur when lithium ions move between electrodes. Neutron or X-rays can analyze the structure of electrode. The advantage of X-rays is convenient in test. However X-rays is scattered by electron cloud in atoms. Therefore, The elucidation for correct position of lithium is difficult with X-rays because lithium has small atomic weight. Neutron analysis techniques could solve this problem. In this review, We wish to discuss about structure analysis and the principle of structural characterization method using neutron beam source.

• The Journal of the Acoustical Society of Korea
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• v.24 no.8
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• pp.431-440
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• 2005

The precise measurement of ultrasonic power is important to the qualify assurance and the safety of medical ultrasonic equipments In the Present work, a brier theory was introduced to determine the ultrasonic Power from the time valving balance-indication due to the radiation force acting on an absorbing target and/or other causes such as buoyancy during the repetition of on/off behavior of ultrasonic irradiation. The developed automated system measuring the ultrasonic power was described in detail with the precise mechanical alignment tool , the electric signal generation network, the control and measurement network and the appropriate procedure. The ultrasonic power measured by the developed system was compared to the reference data calibrated by the other national metrology institute at 1 MHz, 5 MHz, 10 MHz, and 15 MHz over the range 10 mW to 10 W. Their relative differences are within $5\%$.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.394-394
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• 2013

The spin-orbit interaction has received great attention in the field of spintronics, because of its property and applicability. For instance, the spin-orbit interaction induces spin precession which is the key element of spin transistor proposed by Datta and Das, since frequency of precession can be controlled by electric field. The spin-orbit interaction is classified according to its origin, Dresselhaus and Rashba spin-orbit interaction. In particular, the Rashba spin-orbit interaction is induced by inversion asymmetry of quantum well structure and the slope of conduction band represents the strength of Rashba spin-orbit interaction. The strength of spin-orbit interaction is experimentally obtained from the Shubnikov de Hass (SdH) oscillation. The SdH oscillation is resistance change of channel for perpendicular magnetic field as a result of Zeeman spin splitting of Landau level, quantization of cyclotron motion by applied magnetic field. The frequency of oscillation is different for spin up and down due to the Rashba spin-orbit interaction. Consequently, the SdH oscillation shows the beat patterns. In many research studies, the spin-orbit interaction was treated as a tool for electrical manipulation of spin. On the other hands, it can be considered that the Rashba field, effective magnetic field induced by Rashba effect, may interact with external magnetic field. In order to investigate this issue, we utilized InAs quantum well layer, sandwiched by InGaAs/InAlAs as cladding layer. Then, the SdH oscillation was observed with tilted magnetic field in y-z plane. The y-component (longitudinal term) of applied magnetic field will interact with the Rashba field and the z-component (perpendicular term) will induce the Zeeman effect. As a result, the strength of spin-orbit interaction was increased (decreased), when applied magnetic field is parallel (anti-parallel) to the Rashba field. We found a possibility to control the spin precession with magnetic field.

• The Journal of Korean Medicine
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• v.38 no.3
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• pp.1-12
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• 2017

Objectives: To interpret the meanings of Ryodoraku data and to use it as diagnosis tool, study on relationship between Ryodoraku and autonomic nervous reaction (ANR) has to be preceded prior to disease studies. This study aims to observe the change of Ryodoraku characteristics with ANR caused by treadmill exercise via a feasibility study. Methods: The electric current at 24 Ryodoraku points(H1~H6 at left/right wrists and F1~F6 at left/right feet) and vital signs were measured at rest, immediately after the treadmill exercise test, and at later recovery times(10min, 20min, 30min, 60min, 120min after the exercise test). The calculated Ryodoraku scores (RSs) were analyzed using repeated ANOVA test. Results: The RSs in the wrist Ryodoraku points were significantly increased immediately after the exercise (p<.05) and at 10min recovery time (p<.01), and no significant differences were found during the rest of the experimental sets. To the contrary, the RSs in the feet Ryodoraku points showed less difference throughout all the measurement time. Conclusions: The Ryodoraku characteristics change more sensitively in the wrists than in the feet in accordance with the previously reported sweat gland responses of the treadmill exercise. This is the first feasibility study to observe the change of Ryodoraku characteristics caused by treadmill exercise, and it shows the Ryodoraku characteristics are in accordance with known ANS responses.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.6
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• pp.1429-1435
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• 2012

DC-DC converter commonly used in photovoltaic systems, fuel cell systems and electric vehicles is a boost converter. The interleaved boost converter, connected in parallel by several boost converters and operated by the phase difference to reduce the input and output current ripple, has been widely used in recent years. Because of small input and output current ripples, the circuit can reduce the size of the input and output capacitors. Thus, instead of conventional electrolytic capacitor, the film capacitor with high reliability can be used and this is the life and reliability of the entire system can be improved. In this paper, the output current ripple formulas of the multi-stage interleaved boost converter are derived, and the characteristics in accordance with duty are found out. In order to verify the abovementioned contents, the derived results will make a comparison with the calculated values by using PSIM tool.

• Progress in Medical Physics
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• v.9 no.2
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• pp.105-113
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• 1998

Accurate radiation dosimetric characters is very important to determine of dose to a radiotherapeutic patient. Medical linear accelerators have been developed not only its new quality of convenient operation but also electric moderation. It is reliable to measure more detail physical parameter that linac's internal ability. Typically, radiation dosimetric tool is classified ionization chamber, film, thermoluminescence dosimeter, etc. Nowaday, Electronic Portal Imaging Device is smeared in radiation field to verification of treatment region. EPID's image was focused that using both on-line image verification and absolutely minimum absorbed dose during radiotherapy. So, Electronic Portal Imaging was tested for quality evaluation of medical linear accelerator had its pure conditional flash. This study has performed symmetry, Light/Radiation field congruence, and energy check, geometry difference on wedge filter using a liquid filled ion chamber (EPID). Prior to irradiated on EPID, high energy photon beam is checked with ion chamber. Using these results more convenient dosimetric method is accomplished by EPID that taken digital image. Medical image is acquired with EPID too. Therefore, EPID can be analyzed by numerical information for what want to see or get more knowledge for natural human condition.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.6
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• pp.75-82
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• 2002

Design for a quiet operation of fluid power system requires the understanding of noise and vibration characteristics of the system. It's not easy to analyze noise problem in hydraulic cylinder used in typical actuator Because they've got complex fluid dynamics. One of the fundamental problems associated with the hydraulic system is the pulsating flow in pipe lines, which can be tackled by the analysis under simplifying assumptions. The present study focuses on theoretic analysis and experimental study on the dynamics of laminar pulsating flow in a circular pipe. We analyze the propagation characteristics of the pressure pulse within a hydraulic pipe line taking into account the pulsating flow frequency variation. We also measure instantaneous pressure pulses within pipe line to identify the transfer functions. We conduct series of experiments to investigate the propagation characteristics of pressure pulse for various pressure of pulsating flow. The working fluid of the present study is ISO VG46 and the temperature ranges from 20 to $60^{\circ}$ with normal pressure at 4000kPa. The flow rate is measured by using an ultrasonic flow meter. Pressures at fixed upstream and downstream positions are measured concurrently. The electric signals of the pressure sensor are stored and analyzed using a system analyzer(PKE 983 series). The frequency is varied in the range of 10~500Hz. The Reynolds number is kept below 2,000. In the present study, boundary condition was varied by installing a surge tank and an orifice at the end of pipe. Experimental and theoretical results were compared each other under various boundary conditions.

• Journal of Radiation Protection and Research
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• v.28 no.2
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• pp.145-154
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• 2003

By optimizing the radiation protection the collective dose and individual dose could be reduced during YGN #4 $5^{th}$ outage in 2001. The collective doses for the two high radiation jobs decreased to 85% and 65% of expected doses. The proportion of workers with low dose (below 1mSv) exposure increased 4% while the proportion of workers with over 3mSv and 5mSv exposure are decreased to 2%, 1% respectively. But none is exposed over 8mSv for the annual dose. To aid decision of utilizing the robot, cost- benefit analysis was performed and reasonable point was proposed to use the robot. For the first time job, repeated ALARA meeting and mock up training were implemented to set up working procedure by identifying the trouble. To easily set up standard procedure, mockup process was videotaped and reviewed during ALARA meeting. Monitoring is a good approach to chase radiological working condition such as working time, dose rate. behavior of workers, especially for high radiation work. Those data were estimated and adjusted from the stage of work planning to mock up. At the stage of actual work the monitoring data were compared to the estimation and recorded to database. This database will not only be used as a powerful tool for dose optimization at the following outage but also as a guideline to dose constraint set up for optimization for each specific situation.

• Journal of Soil and Groundwater Environment
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• v.8 no.1
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• pp.48-56
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• 2003

A geophysical conductivity logging technique has been adopted to determine hydraulic constants using a simplified physical model that depicts the borehole condition. An experiment has been made by monitoring the conductivity change within the model hole using borehole environment water and incoming-outgoing water of different salinity, under the state of constant flow rate by maintaining balance between inflow and outflow. Conductivity variation features were observed that depended on flow rate, salinity contrasts between fluid within the hole and incoming-outgoing fluid, and density contrasts between fluid conductivity within the hole and incoming fluid. The results of the experiment show the uniform change of fluid conductivity within the hole with time, a fairly good correlation between the flow rate and the conductivity change rate. The geophysical conductivity logging technique can be an efficient tool for determining hydraulic constants if the model equation is verified by henceforward experiments.