• Journal of the Korean Society of Safety
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• v.34 no.4
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• pp.22-31
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• 2019

The flammable liquid conductivity is an important factor in determining the generation of electrostatic in fire and explosion hazardous areas, so it is necessary to study the physical properties of flammable liquids. In particular, the relevant liquid conductivity in the process of handling flammable liquids in relation to the risk assessment and risk control in fire and explosion hazard areas, such as chemical plants, is classified as a main evaluation item according to the IEC standard, and it is necessary to have flammable liquid conductivity measuring devices and related data are required depending on the handling conditions of the material, such as temperature and mixing ratio for preventing the fire and explosion related to electrostatic. In addition, IEC 60079-32-2 [Explosive Atmospheres-Part 32-2 (Electrostatic hazards-Tests)] refers to the measuring device standard and the conductivity of a single substance. It was concluded that there is no measurement data according to the handling conditions such as mixing ratio of flammable liquid and temperature together with the use and measurement examples. We have developed the measurement reliability by improving the structure, material and measurement method of measuring device by referring to the IEC standard. We have developed a measurement device that is developed and manufactured by itself. The test results of flammable liquid conductivity measurement and the data of the NFPA 77 (Recommended Practice on Static Electricity) Annex B Table B.2 Static Electric Characteristic of Liquids were compared and verified by conducting the conductivity measurement of the flammable liquid handled in the fire and explosion hazardous place by using Measuring / Data Acquisition / Processing / PC Communication. It will contribute to the prevention of static electricity related disaster by taking preliminary measures for fire and explosion prevention by providing technical guidance for static electricity risk assessment and risk control through flammable liquid conductivity measurement experiment. In addition, based on the experimental results, it is possible to create a big data base by constructing electrostatic physical characteristic data of flammable liquids by process and material. Also, it is analyzed that it will contribute to the foundation composition for adding the specific information of conductivity of flammable liquid to the physical and chemical characteristics of MSDS.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.6
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• pp.797-803
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• 2010

A method has been developed to tune the static stiffness at a rotation joint considering the whole machine tool system by interactive use of finite element method and experiment. This paper describes the procedure of this method and shows the results. The method uses the static experiment on measurement model which is set-up so that the effects of uncertain factors can be excluded. For FEM simulation, the rotation joint model is simplified using only spindle, bearing and spring. At the rotation joint, the damping coefficient is ignored, The spindle and bearing is connected by only spring. By static experiment, 500 N is forced to the front and behind portion of spindle and the deformation is measured by capacitive sensor. The deformation by FEM simulation is extracted with changing the static stiffness from the initial static stiffness considering only rotation joint. The tuning static stiffness is obtained by exploring the static stiffness directly trusting the deformation from the static experiment. Finally, the general tuning method of the static stiffness of machine tool joint is proposed using the force stream and the modal analysis of machine tool.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.06a
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• pp.68-75
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• 2000

The development of flexible automation in the manufacturing industry is concerned with production activities performed by unmanned machining system. A major topic relevant to metal-cutting operations is monitoring tool wear, which affects process efficiency and product quality, and implementing automatic tool replacements. In this paper, the measurement of the cutting force components has been found to provide a method for an in-process detection of tool wear. Cutting force components are divided into static and dynamic components in this paper, and the static components of cutting force have been used to detect flank wear. To eliminate the influence of variations in cutting conditions, tools, and workpiece materials, the force modeling is performed for various cutting conditions. The normalized force disparities are defined in this paper, and the relationships between normalized disparity and flank wear are established. Finally, Artificial neural network is used to learn these relationships and detect tool wear. According to the proposed method, the static force components could provide the effective means to detect flank wear for varying cutting conditions in turning operation.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.304-307
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• 2003

Usually, the thrust of a Linear Pulse Motor(LPM) is calculated by magnetic equivalent circuit modelling method. Analytical thrust deviation exists to calculating magnetic flux density by using Permeance Modelling Method, Finite Element Method, and Velocity Electric Motive Force method. For calculating accuracy thrust by using these every method, tire thrust is calculated and compared by Lorentz Force method, Magnetic coenergy Method, and Maxwell correspondence forte Method. And that becomes Important factor at the comparison of each capacity and parameter of motor. So this study wants to compare and analyze measurement data and calculating data of the static thrust of LPM. and then we can get more accuracy method, calculating the static thrust of LPM.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.6
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• pp.59-66
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• 2001

Fatigue strength of the welding structure is governed by the residual stress at the weldment toe and static tensile overloads were known as relieving the residual stresses. In this study, static tensile overloads were applied to the welding structures which caused the relief of residual stresses. The amount of residual stress relief was found as proportional to the change of fatigue limit at the given conditions. Based on the fact of the proportionality between the change of fatigue limit and that of residual stress, simple measurement technique is proposed. Modified stress-life curves base on proposed technique gave good agreement with test results.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.549-554
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• 2008

The recent trains are almost being operated by the mechanical propulsion force to drive the gear and wheel with the traction motor. However Magnetic Levitation Vehicle is differently operated. Magnetic Levitation Vehicle is applied with Linear Induction Motor(LIM) that has many advantage like to high capability of going up to slope, low noise, easy to control of speed. So domestic and many advanced countries are interested in Magnetic Levitation Vehicle and they have been studying about it continuously. Thus this paper is studied the LIM test method of static states and guess the optimum driving point by characteristic of static states for LIM. The test items are measurement of thrust force by changed air gap, measurement of thrust force and normal force by changed slip frequency etc.

• Journal of the Korean Vacuum Society
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• v.20 no.5
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• pp.313-321
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• 2011

The Korea Research Institute of Standards and Science (KRISS) has three major vacuum systems: an ultrasonic interferometer manometer (UIM), a static volume expansion system (SVES), and an orifice-type dynamic expansion system (ODES). For each system explict measurement model equations with multiple variables are respectively given. According to ISO standards, all these system variables errors were used to calculate the expanded uncertainty (U).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.381-382
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• 2010

• Structural Engineering and Mechanics
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• v.63 no.2
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• pp.251-257
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• 2017

A local damage identification method using measured structural static displacement is proposed in this study. Based on the residual force vector deduced from the static equilibrium equation, residual strain energy (RSE) is introduced, which can localize the damage in the element level. In the case of all the nodal displacements are used, the RSE can localize the true location of damage, while incomplete displacement measurements are used, some suspicious damaged elements can be found. A model updating method based on static displacement response sensitivity analysis is further utilized for accurate identification of damage location and extent. The proposed method is verified by two numerical examples. The results indicate that the proposed method is efficient for damage identification. The advantage of the proposed method is that only limited static displacement measurements are needed in the identification, thus it is easy for engineering application.

• Journal of the Korean Society of Physical Medicine
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• v.16 no.1
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• pp.17-22
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• 2021

PURPOSE: This study examined the correlations between gait, static balance, and pelvic inclination in patients with chronic stroke. METHODS: Twenty-two chronic stroke patients were included in this study. The subjects participated in gait, static balance, and pelvic inclination tests. In the gait measurement, the cadence and gait velocity were measured, and the average of three trials was calculated and recorded. The static balance was measured using a force platform. The data was captured for ten seconds, and five successful trials were recorded. Pelvic inclination in the sagittal plane was measured using a palpation meter. For data processing, a KolmogorovSmirnov test was used to determine the type of distribution for all variables. Pearson's correlation coefficient was used for correlation analysis. The correlations among the gait, static balance, and pelvic inclination was calculated. The level of significance was .05. RESULTS: Significant negative correlations were observed between the gait variables (cadence, velocity) and static balance variables (COP path length, COP average velocity, and 95% confidence ellipse area) (p < .05). On the other hand, there was no significant correlation between pelvic inclination and gait or between the pelvic inclination and static balance variables. CONCLUSION: Significant correlations were observed between the gait function and static balance. On the other hand, there were no significant correlations between the pelvic inclination and gait and static balance. These results suggest that the pelvic inclination is not an important consideration for increasing the gait function and static balance.