• Journal of radiological science and technology
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• v.30 no.2
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• pp.153-159
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• 2007

Digital medical image commenced with an introduction of PACS has become more popular today in the radiation diagnosis and radiation treatment and made great progress, in particular, for medical testing field, whereas it has made slow progress for radiation treatment field. In order to accommodate the current trend of digital from analog, a spherical mechanical check device(SMCD) that is the form of spherical differing from the existing form of flat or cube has been designed and tested its practicability to replace the part in mechanical check with digital image from QA operation. If the distance maintains constance between source(target) and image detector with constant distance to the center of spherical mechanical check device(SMCD), the size will be shown as a constant image at all times regardless of its direction exposed. For the test, two accurate hemispheres are made and put together which results in a sphere of the equilateral circle. It enables a variety of implementation of the existing mechanical check using digital image as follows: congruity level of radiation field and light field, size accuracy of radiation field and collimation field, gantry rotation isocenter check, collimation rotation isocenter check, room laser accuracy check, collimation rotation angle check, couch rotation angle check, and more. In addition, it has proved its practicability in checking isocenter congruity level as real time at the time of simultaneous rotation between gantry and couch that is applied to the non-coplanar field, which had been hard to apply as a device formed of existing flat or cube.

• The Journal of Korean Society for Radiation Therapy
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• v.19 no.1
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• pp.55-62
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• 2007

Purpose: Digital medical image commenced with an introduction of PACS has become more popular today in the radiation diagnosis and medical treatment and made great progress, in particular, for medical testing field, whereas it has made slow progress for radiation therapy area. In order to accommodate the current trend of digital from analog, a spherical type mechanical check device (SMCD) that is form of spherical differing from the existing form of flat or cube has been designed and tested its practicability to replace the part in mechanical check with digital image from QA operation. Materials and Methods: If the distance maintains constant between source(target) and image detector with constant distance to the center of spherical type mechanical check device(SMCD), the size will be shown as a constant image at all times regardless of its direction exposed. For the test, two accurate hemispheres are made and put together which results in a sphere of the equilateral circle. Results: It enables a variety of implementation of the existing mechanical check using digital image as follows: congruity level of radiation field and light field, size accuracy of radiation field and collimation field, gantry rotation isocenter check, collimation rotation isocenter check, room laser accuracy check, collimation rotation angle check, couch rotation angle check, and more. Conclusion: It has proved its practicability in checking isocenter congruity level as real time at the time of simultaneous rotation between gantry and couch that is applied to the non-coplanar field, which had been hard to apply as a device formed of existing flat or cube.

• Journal of Electrical Engineering and Technology
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• v.11 no.5
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• pp.1084-1092
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• 2016

• The Journal of Korean Academy of Prosthodontics
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• v.56 no.4
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• pp.278-286
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• 2018

Purpose: The purpose of this study was to evaluate the effect of healing abutment height and measurement angle on implant stability when using Periotest and AnyCheck. Materials and methods: 60 implants were placed into artificial bone blocks. After implant insertion, 2, 3, 4 and 5 mm healing abutments were installed on 15 specimens, respectively. Insertion torque value, implant stability test, Periotest value were measured. Insertion torque value was controlled between 45 - 55 Ncm. AnyCheck was used for measuring implant stability test and Periotest M was used for measuring Periotest value. Implant stability test and Periotest value were measured at the angles of 0 and 30 degrees to the horizontal plane. Measured values were analyzed statistically. Results: Insertion torque value had no significant difference among groups. When healing abutment height was higher, implant stability test and Periotest value showed lower stability. Also when measurement angle was decreased, implant stability test and Periotest value showed lower stability. Conclusion: When measuring stability of implants with percussion type devices, measured values should be evaluated considering height of healing abutments and measurement angle.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.1
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• pp.36-41
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• 2002

The cause and the elimination method for the chattering phenomena were investigated in a check valve attached to the exit of an auxiliary cooling water pump in a Korean nuclear powerplant. From the site experiment and the numerical calculation, the incident angle of the disk was so small that it was not able to produce the sufficient lifting force to overcome the gravitational component of the disk weight. Moreover, it turned out that the installation position was not symmetric for the secondary vortical flow generated inside the elbow so that the flow structure had strongly unstable flow characteristics. From this study, the tapping noise and the chattering phenomena were eliminated exactly by changing the incidence angle of the valve disk and the installation position of the calve body.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1848-1853
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• 2000

Cause and the elimination method for the chattering phenomena were investigated the check valve attached exit of the auxiliary cooling water pump at a korean nuclear powerplant. From the site experiment and numerical calculation the incident angle of the disk was so small that it was not able to produce the lifting force to overcome the component of disk weight. Moreover, it turned out that the installed position was not symmetric for the secondary vortical flow generated inside the elbow, so that the flow structure had strongly unstable flow characteristics. From this technical support, the tapping noise and the chattering phenomena were eliminated exactly by changing the incidence angle of the valve disk and installed position of the check valve.

• Industry Promotion Research
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• v.2 no.1
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• pp.9-13
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• 2017

This study deals with the check valve safety valve for residential gas piping. It can be manually shut off within 1 second in case of emergency, and it is possible to touch 3kg of pressure by hand force. To develop the technology so that it can be used repeatedly. Study results after first valve operation. And 0.61 seconds on average. Therefore, it was found that there was no problem in operation even when used as a safety valve. Third, it was found that all of the results of using the blocking ball diameter of 7mm were not abnormal. In this study, it is meaningful to develop the check valve safety valve of gas piping and verify the performance by testing with existing valve.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.315-320
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• 2004

Swing check valves are the most common type of check valve in nuclear power plant and need to be operated property to perform their functions and to keep the valve internals stable. However, for a swing check valve disc to remain stable, the opening characteristics should be identified and the upstream flow velocity should be enough to hold the disc fully open and without motion. Thus it is necessary to develop a model for predicting the flow velocity for a given disc opening. In the present study, the disc positions with mean flow velocity were measured for 3 inch and 6 inch swing check valves. Comparison of the measurements with the existing models showed that the models underestimate the mean flow velocity for a given disc position. Therefore, the existing model for predicting swing check valve disc position was improved with the realistic disc impingement area perpendicular to the flow stream and the experimental data. The result showed that the improved model with the best estimate of kb = 0.04 predicts well the disc openings of 6 inch swing check valve, especially in the low velocity region. For better prediction of the disc opening at high flow velocity, however, it is recommended to develop a kb correlation with the disc angle.

• International Journal of Fluid Machinery and Systems
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• v.1 no.1
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• pp.140-147
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• 2008

An experiment setup was introduced to study dynamic behaviour of different types of check valves and the effects of air entrainment on the check valve performance under pressure transient condition. The experiment results show that the check valves with low inertia, assisted by springs or small traveling distance/angle gave better performance under pressure transient condition than check valves without these features. Air entrainment was found to affect both wave speed and reverse velocity. With the increase of the initial air void fraction in pipeline, the experiment results show that the wave speed was reduced, the reverse velocity was increased. The first peak pressure increased initially and then decreased with the increase of the initial air void fraction, the pressure surge periods were increased proportionally with air void fraction due to the greatly reduced wave speed. The study can be applied to help choosing suitable check valves for a particular pumping system.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.1009-1019
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• 2009

Soil nailing method is widely used in reinforcing slopes and excavating earth. The analysis of nail-reinforced slopes, in order to determine the economical length ratio and nail angle, complicated analytical need to be applied by means of computer programs. Therefor this suggested Soil stability Chart for nailed slopes which may be very useful for pre-design, rapidly design, and final check. Three slope types, three nail length and three nail angles are selected for the stability analysis by using limit equilibrium method of Bishop and French Method. From the above results, this study propose the slope reinforced design charts for dry season and rainy season. This proposed reinforced design charts can check dry season as well as rainy season, also these charts can provide reinforcing requirement, soil nail's economical length ratio and nail angle as well.