• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.8
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• pp.652-660
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• 2003

T-history method, measuring heat-of-fusion of phase change material (PCM) in sealed tubes, has the advantages of a simple experimental device and no requirements in sampling process. However, a degree of supercooling used in selecting the range of latent heat release and neglecting sensible heat during the phase change process can cause significant errors in determining the heat of fusion in the original method, which has been improved in order to predict better results by us. In the present study, the modified method was applied to a variety of PCM such as paraffin and lauric acid having very small or no supercooling with a satisfactory precision. Also the selection of inflection point and temperature measurement position was fumed out not to affect the accuracy of heat-of-fusion significantly. As a result, the method can provide an appropriate means to assess a new developed PCM by cycle test even if a very accurate value cannot be obtained.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.4
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• pp.80-86
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• 2021

Plastics are widely used in mechanical and other fields due to their light weight, design flexibility, and molding processability. In processing plastics, defective products are mixed and reprocessed to improve production efficiency and reduce costs. In this study, an experiment was conducted to confirm the coefficient of thermal expansion of HDPE during this reprocessing. The coefficient of thermal expansion was measured at different measurement directions and heating rates. As a result, we observed that the coefficient of thermal expansion in the direction perpendicular to the injection direction is greater than that in the horizontal direction.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.12
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• pp.28-33
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• 2020

Oil-related products have provided many benefits to humanity, but are significant contributors to environmental pollution. As per the International Maritime Organization (IMO) requirements, in the future, all ships must be equipped with filtering equipment and 5ppm bilge alarms that can help remove or reduce oil products during wastewater treatment. In this study, a UV fluorescence measurement system that can detect the oil components in wastewater containing both water and oil was developed. When an excitation wavelength of 254nm was used to irradiate the wastewater, the amount of UV at a divergent wavelength of 360nm was measured to measure the contamination. Based on the measurement, it was concluded that this system is suitable for use as the 5ppm bilge alarm proposed by IMO.

• International Journal of Korean Welding Society
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• v.2 no.1
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• pp.29-32
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• 2002

In previous study, the decrease and recovery of total stiffness in welded structure was discussed on the basis of experimental examination through tensile loading and unloading test of welded specimen. The recovery of structure stiffness was caused by the release of welding residual stress through mechanical loading. In this study, analysis model that is indispensable for the effective application of MSR method was established on the basis of test and measurement result. Thermal elasto-plastic analysis for welding process was performed by non- coupled analysis. Analysis results of welding process were transfer to elasto-plastic model for tensile loading & unloading by restart technique. In elasto-plastic analysis model for mechanical loading & unloading, hardening appearance of weld metal was considered by rezoning technique and tying technique was used for JIG condition of test machine.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.5
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• pp.148-156
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• 1996

Automatic product system is gradually increasing according to development of industrial society. On-line measurement makes a important role in view of economic and effective side in industrial product system. Syncronization system is developed to measure screw thread which is rotating. In-process measuring of rotating body have a lot of difficuties even thoufht using various method containing high speed camera. So, now we suggest one of the new method which is not so expansive. In this study, digital value was produced through the image processing algorithm from acquired orignal image. As a result, we have a good agreement between measuring values calculated from image conture and measuring values acquired from profile project by means of experiment, respectively.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.10
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• pp.15-27
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• 1997

Quasti-static cutting force variations in milling process are measured indirectly using spindle motor current. Quasi-static sensitivity of the spindle motor current is higher than that of the feed motor current. Magnitude of the spindle motor current is independent of cutting direction. The linear relationship between the cutting force and the spimdle motor RMS current at various spindle rotational speed is obtained. Frequency/ Voltage(F/V) converter voltage is measured to identify the spindle speed and to determine the cutting force at various spindle speeds. Overload on the tool during milling process can be detected using the proposed indirect cutting force measurement. Based on these measurements, cutting force is regulated at a constant level by feedrate control.

• International conference on construction engineering and project management
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• 2013.01a
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• pp.587-591
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• 2013

Measuring the process of construction operations for productivity improvement remains a difficult task for most construction companies due to the manual effort required in most activity measurement methods. There are many ways to measuring the process. But past measurement methods was inefficient. Because they needed a lot of manpower and time. So, this article focus on the vision-based object recognition and tracking methods for automated construction. These methods have the advantage of efficient that human intervention was reduced. Therefore, this article is analyzed the performance of vision-based methods in the construction sites and is expected to contribute to selection of vision-based methods.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.5
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• pp.93-99
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• 2002

In general, manufacturing error is originated from bad material, machine tool defection and tool breakage. When the manufacturing process is stable, the most of error come from the tool wear. In common on-machine measurement teaching probe and touch sensor are widely used however in this paper the electric touch point type automatic tool compensation system is developed the performance of it is validated and effective operating is proposed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.232-236
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• 1996

This paper deals with an on-the-machine measurement method for roughness of ground surface by using flux ratio of scattered lights. A sensor and control unit is developed so as to e applied to surface grinding processes. The performance of the sensor is compared with that of stylus. The experimental investigation shows that not onlythe sensor has good performance as a surface roughness sensor but alsothe sensor is very useful for monitoring grinding condition in order to detect ill-conditioned grinding or dressing time.

• Journal of the Korean Society of Safety
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• v.6 no.4
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• pp.58-65
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• 1991

In - process measurement of surface roughness is introduced which employs an optical method by using laser beam. This makes it possible to detect the surface roughness not only along the circurnferential path but also along the feed direction even during machining. The maximum roughness value is always abtainable from the reading along the feed direction.