• Transactions of Materials Processing
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• v.25 no.3
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• pp.161-168
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• 2016

Sheet metals are often required to be formed into three dimensional curved shapes for use as skin structures. As a result various sheet metal forming methods, such as press die forming, stretch forming, and line heating have been used over the years in industrial production lines. Although they are extensively used in industry, these methods are not suitable for small quantity batch productions. Studies have been conducted to improve or replace these methods with plausible flexible forming technologies. As a part of these studies, we developed a new and more efficient forming device named flexibly-reconfigurable roll forming (FRRF). The current study presents the process development and experimental verification for the applicability of this device. To improve the efficiency of the FRRF apparatus, several hardware components were invented and a suitable operating program was developed using MFC of visual C++. The ways to make the FRRF apparatus fully functional are also described. Sheet metal was formed into three dimensional shapes using the FRRF apparatus and the final products are presented as evidence for the applicability of the developed device.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.233-237
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• 1998

In this work, to identify the dynamic characteristics of disk-spindle system in hard disk drive, experimental modal analysis was performed. And an experimental analysis system including testing apparatus, precision sensors, and analysis software was established in order to perform the testing effectively. From the experimental results, coupled and uncoupled modal characteristics of 3-disk spindle system are clearly identified.

• Journal of the Korean Geosynthetics Society
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• v.10 no.4
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• pp.93-103
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• 2011

In order to design suitable geo-structures in cold region, it is generally required to consider the mechanical properties of permafrost soils. 'Frost heave' as one of the primary phenomenon is considered to be an important factor together with 'adfreeze bond-strength' and 'creep deformation' for structural design process in permafrost area. Therefore, the fundamental study for frost heave has to be preceded for design of geo-structures in cold region. While various experimental apparatuses have been developed, there still exist a certain level of limitation to evaluate the frost-heave characteristics as design parameters. In this paper, a new type of experimental apparatus is proposed to evaluate the engineering characteristics of frost heave in permafrost soils and a set of verification test results is presented. Based on the verification tests, the proposed apparatus is a suitable to obtain frost characteristics of soils.

• Journal of Science Education
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• v.37 no.2
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• pp.348-358
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• 2013

The purpose of this study is to develop the science item on computer-based performance assessment which is able to replace the assessment with actual experimental apparatus. The survey on the necessities and the difficulties of the assessment with actual experimental apparatus was conducted with 57 physics teachers. By reflecting the results of the survey, the computer-based assessment items which are related with constructing circuits with an ammeter and a voltmeter were developed. The developed computer-based assessment items were organized in similarity to assessment conducted with actual experimental apparatus, proper feedback was provided by students' performance in the process of assessment so as to grading performance results automatically. To achieve them, the algorithm was developed so that computer can judge the accuracy of students' performance results.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.2
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• pp.171-179
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• 2009

An object of this study is to confirm application characteristics of the vortex tube apparatus for substitution of the intercooler in a common-rail diesel engine. The turbo pressure, the intake air mass flow rate and the charging air cooling ratio of the intercooler were measured in an experimental engine. The vortex tube apparatus was made after confirmation of the geometric phenomena in fundamental experiments. The vortex tube designed with fundamental data was applied to a conventional common-rail diesel engine instead of the intercooler. Its application characteristics, engine performances and emissions were investigated. From this experimental results, we suggested the vortex tube can be applied to a conventional common-rail diesel engine throughout extra complement. We can also expect the higher cooling effect, if we consider the application of the vortex tube in supercharging diesel engine without the intercooler.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.27 no.2
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• pp.168-174
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• 2017

In this work, a piezostack single-stage valve (PSSV) system is proposed and its control performance is experimentally evaluated at high temperature up to $150^{\circ}C$. In order to achieve this goal, a PSSV system is designed and operating principle and mechanical dimensions are discussed. A displacement amplifier and an adjust bolt are used to generate target displacement and to compensate thermal expansion. Then, an experimental apparatus is constructed to evaluate control performance of the PSSV system. The experimental apparatus consists of a heat chamber, a hydraulic circuit, a pneumatic circuit, pneumatic-hydraulic cylinders, thermal insulator, electronic devices, sensors, data acquisition (DAQ) board and a voltage amplifier. The flow rate and displacement control performance of the valve system are evaluated via experiment. The experimental results are evaluated and discussed at different temperatures and frequencies showing the controlled flow rate and spool displacement.

• Journal of the Korean Applied Science and Technology
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• v.37 no.5
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• pp.1402-1408
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• 2020

In order to save energy, a lot of research has been conducted to develop a high-efficiency heat pump. Research to reduce or eliminate the occurrence of frost in the outdoor unit coil is also being conducted at the same time. A constant temperature chamber was constructed that allows experimentation under the same conditions as in the natural state so that frost does not occur in the outdoor unit of the heat pump regardless of the season. In order to verify the validity of the experimental apparatus, a simulation was conducted by dividing the straight length of the duct in front of the outdoor unit in the constant temperature chamber, which is the experimental apparatus, into three conditions. As a result, it was found that a straight space must be secured 10 times the diameter of the duct.

• Journal of Korean Elementary Science Education
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• v.18 no.1
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• pp.65-73
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• 1999

The purpose of this study is tile development of tile observation Assessment criteria that is used to assess manipulative skills in elementary science. The procedures of developing observation Assessment criteria are as follows. First, we investigated the actual condition about science process skills assessment with tile questionnaire. Second, we selected 7 experimental apparatus through the analysis of the science textbooks. The selected experimental apparatus are dropper, alcohol lamp, thermometer, test tube, filtering device, able balance, graduated cylinder Third, the observation Assessment criteria arc developed through tile analysis of the related experimental textbooks, the demonstrations, and the questionnaire, Forth, tile validity is verified by science education specialists and graduate students who major in science education. Fifth, the first jilter-rater agreement is investigated in the result of the field with observation criteria of which the validity was verified. The second inter-rater agreement is investigated through the revision and the addition of the criteria with the low agreement. In result, the jilter-rater agreement ranged from 0.86 to 0.98. One of the major problems in observation assessment is the rater's subjective viewpoint. So, this research shows a more specified scale and criteria for the assessment. This suggests that the observation Assessment criteria developed in tile study satisfies the high reliability and validity requirements. Considering the results, this criteria call be used effectively for assessing manipulative skills of elementary school students.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 1999.02a
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• pp.189-193
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• 1999

An experimental study was carried out to improve the cooling capacity and performance of the pulse tube refrigerator. Three buffer pulse tube refrigerator was designed and fabricated, and the experimental apparatus was constructed. This paper presents operating process of three buffer pulse tube refrigerator and results obtained with the performance test. The cooldown characteristics and load characteristics are described. The lowest temperature measured in three pulse tube refrigerator was 88K and the cooling capacity at the optimum operating condition was 27W at 120K.

• Progress in Superconductivity and Cryogenics
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• v.1 no.2
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• pp.54-59
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• 1999

An experimental study was carried out to improve the cooling capacity and performance of the pulse tube refrigerator. Three buffer pulse tube refrigerator was designed and fabricated, and the experimental apparatus operating process of the therr buffer pulse tube refrigerator and results obtained with the performance test. The cooldown characteristics and load characteristics are described. The lowest temperature measured in the three buffer pulse tube refrigerator was 88K and the cooling capacity at the optimum operating condition was 27 W at 120K.