• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.3
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• pp.83-91
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• 1999

In this paper, we suggest a virtual machining system that can simulate cutting forces of ball end milling at the stage of part design. Cutting forces, here, are estimated from the machanistic model that uses the concept of specific cutting farce coefficient. To this end, we need undeformed chip thickness which is used for calculating chip load. It is derived from the Z-map data of a CAD model. That is, chip load is the height difference between the cutting tool and the workpiece at an arbitrary position. The tool contact point is referred from the cutter location data. On the other hand, the workpiece height is acquired from the Z-map model of a CAD data. From the experimental verification, we can simulate machining process effectively to the slot and the side cutting of ball end mill.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.895-898
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• 2001

This paper presents an optimization cutting speed(OCS) program developed to improve the machining precision and tool life in high speed machining using ball end milling. This program optimized the cutting speed that is changing at any time in free surface machining of an automobile part like a connecting load die. The technique of optimization cutting speed makes the CAD/CAM-generated NC code go through a reverse post process, conducts cutting simulation, and obtain the effective tool diameter of the ball end milling. Then it changes the spindle revolution to within the range of critical cutting speed fit for the material of the workpieces depending upon the effective tool diameter. In this study, the machining precision and tool life were compared for the two connecting load dies processed using the general cutting method and the proposed optimization cutting speed technique, respectively.

• Proceedings of the KSR Conference
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• 2001.10a
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• pp.247-252
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• 2001

In this study, an aluminum electric motor car with a modular front end made of composite materials is numerically evaluated applying the standard specifications for the urban EMU(Electric Multiple Unit) train. Structural analyses under compressive load, torsional load and free vibration satisfy the standard specifications, but analysis under normal load doesn't. By the way, the aluminum bodyshell of the car except the modular front end is almost same to that of the Korean standard EMU, which satisfy the standard specifications. It is presumed that the stiffness of the modular front end made of composite materials haves some influence on the strength of the aluminum bodyshell.

• Journal of the Korean Society for Railway
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• v.6 no.4
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• pp.273-278
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• 2003

In this study, an aluminum bodyshell with a modular front end made of composite materials is numerically evaluated applying the standard specifications for the urban EMU (Electric Multiple Unit) train. Structural analyses under compressive load, torsional load and free vibration satisfy the standard specifications, but analysis under normal load doesn't. By the way, the aluminum bodyshell of the car except the modular front end is almost same to that of the Korean standard EMU, which satisfy the standard specifications. It is presumed that the stiffness of the modular front end made of composite materials has some influence on the strength of the aluminum bodyshell.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.13 no.4
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• pp.290-295
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• 2001

Subsets pipelines are exposed to several potential risks of damage due to corrosion, soil instability, anchor impact and other hazards. One of the main risk factors for the safety of a subsea pipeline is its free spanning. This paper examines the safety of subsea pipelines with free span under axial compressive load. The variation of allowable lengths of dynamic free span is examined for generalized boundary conditions. The free span is modelled as a beam with an elastic foundations and the boundary condition is replaced by linear and rotational springs at each end. A dynamic free span curve is obtained with a function of non-dimensional parameters and can be used usefully for the design of subsea pipelines with a free span. A case study is carried out to introduce the application method of the curve.

• Journal of Urban Science
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• v.7 no.1
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• pp.11-21
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• 2018

Abstract: Korea has designated free economic zones to build the foundation for national economic development by setting up special economic zones to be more competitive in cities. On August 5, 2003, the government designated Songdo, Yeongjong and Cheongna districts in Incheon as free economic zones. But while the development should have been completed nearly three years before the end of the development, the development has been slow and the population, foreign direct investment and other business results are far from the initial plan. Therefore, in this study, we will investigate the various problems occurring in the Incheon Free Economic Zone, investigate the causes of the problem, and then compare and analyze the Incheon Free Economic Zone and China's special economic zones. The two institutions share similar characteristics in many areas, but the Incheon Free Economic Zone system has yet to be settled, as the special economic zone has played a significant role in economic development in China. Therefore, the study is expected to find a solution to the problems of the free economic zones in Incheon and provide directions for future development.

• Archives of Reconstructive Microsurgery
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• v.14 no.1
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• pp.42-49
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• 2005

Between June 1989 and may 2004 Ipsilateral vascularized fibular transposition was performed on nine patients with segmental tibial defects combined with infection following trauma. Ipsilateral vascularized fibular graft was performed on two or three stage according to the degree of infection. Initially free vascular pedicled graft was done followed by ipsilateral vascularized fibular graft. Type of free flap used is scapular free flap 3 cases, latissimus dorsi free flap 5 cases and dorsalis pedis flap 1 cases. The patients were followed for an average of 3.4 years. the average time to union was 6.7 months, and in all patients the graft healed in spite of complication. Complication was free flap venous thrombosis in 1 cases, persistent infection in 1 cases, delayed bony union at the distal end of fibular graft in 2 cases. The results showed that more faster bony union was seen in which cases firmly internally fixated and more faster hypertrophy of graft in which cases was permitted to ambulate on early weight bearing and more faster healing in which cases debrided more meticulously. Reconstruction of tibia defect with free flap followed by Ipsilateral fibular transposition is a useful and safe method to avoid the potential risk of infection for patients with tibial large bone defect and soft tissue defect associated with infection.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.890-893
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• 2000

In this paper, the test of machinability according to the cutting positions when the ball end milling of hemispheric workpiece is carried out to find the optimum cutting position of free form surface die. Tool runout, cutting force. and chip form are measured. The results show that the optimum cutting condition to get the constant feed per tooth is the inclined angle of 40 degree of workpiece.

• Proceedings of the KOR-BRONCHOESO Conference
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• 2009.04a
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• pp.32-32
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• 2009

• International Journal of Control, Automation, and Systems
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• v.5 no.4
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• pp.471-478
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• 2007

In this paper, an optimal Wiener-Hopf decoupling controller formula is obtained which is expressed in terms of rational matrices, thereby readily allowing the use of state-space algorithms. To this end, the characterization formula for the class of all realizable decoupling controller is formulated in terms of rational functions. The class of all stabilizing and decoupling controllers is parametrized via the free diagonal matrices and the optimal decoupling controller is determined from these free matrices.