• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.6
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• pp.61-65
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• 2014

Construction heat insulating material for construction is used in large amounts in industry. In the manufacturing process of this insulation material, a thermal insulation material is completed while a polymer in a liquid state passes through Hall breaker. At this time, the quality and form of a product are determined by a hole in the breaker according to the oil pressure of the fluid and the change of the flow velocity. The friction wear action with regard to partner movement between the two levels of quality of materials affects the performance and the lifetimes of machine parts. In this study of a friction test, SM45C, which is a material used to create brake holes, was used. PVC was used to create the specimen. Moreover, an experiment divided a lubricous state and an unlubricated condition. The resulting value over the load of a pin, the revolving speed of a disk, and the standby state of an experimental result disk could be acquired.

• Journal of Drive and Control
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• v.17 no.4
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• pp.46-53
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• 2020

In this paper, the development of a manually and continuously variable impact force control mechanism for hydraulic breakers was studied. Generally, a hydraulic breaker has one or two piston strokes. Hydraulic breakers, which have two strokes, have two valve-switching ports and make short and long piston strokes. The piston stroke valve controls the piston stroke by opening and closing a short stroke-switching port. The short piston stroke mode is used to break soft rock, concrete, or asphalt. This stroke control valve system is not popular for small hydraulic breakers mounted on 1 to 14-ton excavators. To preserve the carrier-like excavator, proper breaking force is needed, and it can be easily controlled by multiple piston stroke control valves. The easiest way to control these breakers is to use several switching ports and valves but they are not easy to install in small hydraulic breakers and are expensive. To use only one switching port and valve, a method can be used to change the open area of the switching port to delay valve switching. This method provides multiple piston strokes.

• Trans-
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• v.1
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• pp.141-166
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• 2016

France owns a unique film production process with the big share of public funding. In its background there is the most developed film support scheme in the world. We consider the French film industry has the fair competition order than any other country. This study follows the French film production process from the project planning to film screening. It looks into various aspects French cinema: production scale of French films, investment/production agreement, actors casting, decision of the film budget, major investors, staffs' wages and collective convention, screening, overseas sales and profit-sharing. It aims to get across the French film industry, especially the film production sector. As a case study, we choose a romantic comedy, Heartbreaker(L'Arnacœur) made in 2010. This study presents a French film industry structure. It will give you some hints to reconsider the existing problems of Korean film industry, for example, screen monopoly, vertical integration of conglomerates, poor secondary market, low earnings rate… etc.

• Journal of Drive and Control
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• v.15 no.2
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• pp.9-21
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• 2018

The aim of this study was to develop and test a model of an auto-sensing hydraulic breaker that can automatically change its 4-step impact mode according to the rock strength using SimulationX. The auto-sensing hydraulic breaker with a 4-step variable impact mode has the advantage of obtaining optimal impact energy and impact frequency under various rock conditions compared to an auto-sensing hydraulic breaker with a 2-step variable impact mode, which has already been developed overseas. Several steps were necessary to conduct this study. First, the operation principle of the auto-sensing hydraulic breaker with the 2-step variable impact mode was analyzed. Based on the findings, an analysis model of the auto-sensing hydraulic breaker with the 4-step variable impact mode was developed (and compared with the 2-step variable impact mode) Finally, an analysis of the results established that the stepwise variable of the impact mode was implemented according to the rock strength and the difference of each impact mode was confirmed. This study is expected to contribute to the development of auto-sensing hydraulic breakers that are superior to those developed by advanced companies in foreign countries.

• Journal of Industrial Technology
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• v.22 no.A
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• pp.107-117
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• 2002

The blast works for open cuts and underground constructions near urban areas have recently increased complaint of ground vibration, air blast and fly rock. In order to reduce these problems, it is necessary to develop more cautious blasting, or non-blast excavation methods by mechanical power. For these breaker workings instead of blast are sometimes adopted. To compare the characteristics of blast vibration with breaker vibration, the level, range of frequency and spectrum amplifications of each vibration were studied.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.2
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• pp.96-101
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• 2000

In machining with cutting tool inserts having complex chip groove shape the flow curl and breaking pattern of the chip are different than in flat-face inserts. In the present work an effort is made to understand the three basic phe-nomena occurring in a chip since its formation in machining with groove type and pattern type inserts. These are the ini-tial chip flow the subsequent development of up and side curl and the final chip breaking due to the development of tor-sional and bending stresses. in this paper chip flow angle in a groove type and pattern type inserts. The expres-sion for chip flow angle in groove type and pattern type inserts is also verified experimentally using high speed filming techniques.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.6
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• pp.1005-1013
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• 1987

For the factory automation and unmanned machine operation, it is very important to manufacture highly reliable and efficient chip breakers for optimal chip control. In this research, using the CALMA CAD/CAM SYSTEM, the manufacturing process of 3-dimensional chip breakers is established. Using the results of the cutting test of the selected chip breakers with double-step grooves, the chip breaking mechanism is schematically analysed. An expression for the chip breaking relation is derived which considers chip material behavior following LUDWIK's stress-strain curve, chip breaking criterion and the shape of chip breakers. This contains the thickness of chip, the radius of chip curl, and the mechanical properties of chip materials. It is found that the expression agrees very closely with the experimental results.

• Tribology and Lubricants
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• v.19 no.2
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• pp.59-64
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• 2003

In this study, the hydraulic breaker system was analyzed and the analysis tool using GUI was developed. The analysis on the system with the accumulator was included. From the parametric analysis, the effects of each factor were revealed. Through the simulation with varying parameters, the method to improve the performance of the hydraulic breaker system was presented. The analysis tool will help a man without special knowledge about programming analyze the hydraulic breaker system. The result of this study will help improve the hydraulic breaker system in sight of Blow energy and Blows per minute.

• Journal of the Korean Society for Heat Treatment
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• v.26 no.4
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• pp.178-184
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• 2013

The effects of thickness and surface grinding condition on the fracture strength of Si wafer with a thickness under $100{\mu}m$ were investigated. Fracture strength was measured by ball breaker test for about 330 dies (size: $4mm{\times}4mm$) per each wafer. For statistical analysis of the fracture strength, scale factor was determined from Weibull plot. Ball breaker fracture strength was observed to increase with decreasing thickness of silicon die. For the silicon dies of different surface conditions, ball breaker fracture strength was high in the order of polished, ground (#4800), and ground (#320 grit) specimen. Probabilistic fracture strength (i.e., scale factor) increased with decreasing surface roughness of silicon die.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.78-82
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• 2001

This paper presents the numerical analysis and experimental verification to know the metal cutting burr formation mechanism in face milling operation. Finite element method are applied to predict the 2-D burr formation process prediction. Face milling process are adjusted to analyze the characteristics of burr shapes according to various cutting conditions. The cutting parameters were investigated with cutting speed, feed rate, depth of cut. Through a few experiments, various burr types are classified according to its shape and properties.