• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.251-256
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• 1999

"Ploughing" on the flank face of the tool in the metal cutting process is due to the tool in the metal cutting process is due to the finite edge radius of the tool and due to the development of flank wear. Because of the high stresses near the cutting edge, elastic-plastic deformation would be caused between the tool and the machined surface over a small area of the tool flank. The deformation would affect the roughness of the machined surface. Recently, some attempts have been made to predict the surface roughness, but elastic-plastic effect due to ploughing in the cutting process has not been considered. The research has analyzed mechanism of the ploughing of the cutting process using contact mechanics. Tool and workpiece material properties have been taken into account in the prediction of the surface roughness. The surface roughness has been simulated by the surface-shaping system. The results between experiment and simulation have been compared and analyzed. analyzed.

• Transactions of Materials Processing
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• v.8 no.6
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• pp.554-562
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• 1999

In this paper, the stress and strain behavior in near homogeneous isotropic matrix of metal like steel was studied during roll forming of thin steel sheet for cylindrical pipe. Analytical result reveals a body which is on the area of square thickness along and perpendicular to the width of thin steel sheet is in the state of plane strain during roll forming. As a result, construction of analytical method for calculating deformation load and stably deformed length along the width of strained steel sheet was established. Also, loads applied during roll forming were analyzed using two typical thin steel sheets. 12.3mm thick steel sheet with 42.5kg/㎟ yield strength of pipe and 5.3mm thick steel sheet with 32.5kg/㎟ yield strength of pipe. Through this analysis, applicability of the analytical method for deformation load during roll forming of cylindrical thin steel pipe was evaluated with a study of necessary production technology for roll forming and design technology for roll forming machine.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.9
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• pp.127-134
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• 2009

Laser-assisted machining uses primarily laser power to heat the local area before the material is removed. It not only efficiently reduces the cutting force during the manufacturing process but also improves the machining characteristics and accuracy with regard to difficult-to-machine materials. The prediction of relative deformations between the cutting tool and workpiece is important to improve the accuracy of machined components. This paper presents the deformation errors caused for a cylindrical workpiece by thermal effects in the laser-assisted machine tool using finite element method. The results can be used to increase the cutting accuracy by compensating thermal distortion prior to laser-assisted machining.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.607-614
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• 2000

Settlement with crack on the hardened liners may occur in the weak clay due to waste load since the stiffness of the hardened liner is greater than that of the clay layers. Way of reducing deformation crack in the hardened liner is investigated using two computer programs, CONSOL and FLAC. The computer program CONSOL estimates the magnitude of settlement with time in clay layers and FLAC analyses the stress and deformation relationship between the foundation of landfill and waste load. The results show that a representative block of the analyzed area reaches the consolidation settlement of 1.32m, 8.8 years after the disposal of waste started with the degree of consolidation U=90%. The stress within the hardened liner exceeds the allowable vertical stress of 5kg/$\textrm{cm}^2$ and horizontal stress of 1.67kg/$\textrm{cm}^2$ at the concave part of the liner where the main and branch drainage pipes of leachate are located. It was recognized that the thickness of the interested area should be enlarged or the strength of the same area should be improved to tolerate the planned waste load.

• International Journal of Ocean System Engineering
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• v.1 no.4
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• pp.185-191
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• 2011

This research was described the prevention of coastal topographical change and sediment diffusive concentration incoming from small estuary after construction jetties. This structure is constructed to decrease sediment deposition incoming from the upstream river due to the urbanization and industrial development and to minimize effects on the coastal ecosystem. The physical modeling and numerical modeling for waves were conducted to analyze the configuration of Imrang sand beach deformation without and with construction of jetty. The specification of the installed jetty, which is able to control sedimentation concentration was decided based on the prediction of the Imrang beach area changes by space and time. As a result, the jetties constructed in the estuary retarded the rate of sand sediment, so that the effect area of sand sedimentation was obviously decreased. In addition, the measured field data indicated that the sediment deposition inside of dikes could be controlled and the right side area of jetties could be preserved without sediment deposition.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.319-324
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• 2004

Cross wedge rolling process is utilized to manufacture multi-stepped axis symmetrical parts. This process is generally performed under high temperature conditions in order to induce serious deformation. But cold cross wedge rolling process has been rarely studied due to the limits of deformation. Recently, the cold cross wedge rolling process has been utilized to enhance the material strength in specified parts of manufactured products. In this paper, experimental researches were carried out with various forming conditions of cold cross wedge rolling process in order to suggest the design guidance to make preform for cold cross wedge rolling. The tensile strength and the surface hardness of specified region were compared to that of initial material with the variation of the area reduction and the rotational speed of rolling die. With respect to the area reduction, the maximum tensile strength was linearly increased and the surface hardness was rapidly increased within lower percent of area reduction. The surface hardness was saturated over the rotational die speed of 0.8 RPM.

• 한국지구물리탐사학회:학술대회논문집
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• 2007.06a
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• pp.93-100
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• 2007

During tunnel excavation, drawdown of groundwater table or discharge from tunnel faces may not only reduce stability of tunnel and work efficiency but cause environmental problems. We have investigated the applicability of electrical resistivity survey for the establishment of the monitoring system for groundwater behavior and detecting flow channel of groundwater during tunnel excavation. The groundwater level was continuously measured at several points for 1 year. Survey was conduted at every 3 months using preinstalled electrical resistivity cables on site. The results show that observed changes in resistivity ratios in the area can be explained with observed changes in groundwater level. Thus, we believed that electrical resistivity analysed together with groundwater data can be applied for the monitoring of groundwater in tunnel area.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.605-613
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• 2008

Application of anchored or strutted wall system for the earth retention of excavation works in a populated urban area or a poor soil deposit can be limited due to various restrictions. Since the strut becomes longer in a wide excavation site, the stability of an earth retaining wall is decreased, the wall deformation is increased, and the ground settlement is also increased due to an increased buckling or bending deformation of struts. Especially, in a populated urban area, the installation of anchors can be problematic due to the property line of adjacent structures or facilities. Thus, a new concept of earth retaining system like Self-Supported diaphragm Wall can solve several problems expected to occur during excavation in the urban area. Application of self-supported counterfort diaphragm wall was verified in this paper though comparing the design of self-supported counterfort diaphragm wall with the data monitored during excavation in Singapore.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.4C
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• pp.408-414
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• 2010

When we are collecting traffic information on CCTV images, we have to install the detect zone in the image area during pan-tilt system is on duty. An automation of detect zone with pan-tilt system is not easy because of machine error. So the fisheye lens attached camera or convex mirror camera is needed for getting wide area images. In this situation some troubles are happened, that is a decreased system speed or image distortion. This distortion is caused by occlusion of angled ray as like trembled snapshot in digital camera. In this paper, we propose two methods of de-blurring to overcome distortion, the one is image segmentation by nonlinear diffusion equation and the other is deformation for some segmented area. As the results of doing de-blurring methods, the de-blurring image has 15 decibel increased PSNR and the detection rate of collecting traffic information is more than 5% increasing than in distorted images.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.1
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• pp.45-51
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• 2001

In order to investigate the optimal design weight of sinkers for preventing cage net from deforming in current, the model experiment on 2 types of square cage nets with different S sub(n)/S, the ratio of total area of netting projected to the perpendicular to the water flow S sub(n) to wall area of netting S, and 4 kinds of sinkers was carried out in circulation water channel. The model cage nets were made in 1/10 scale and the total weight in water of 4 sinkers attached to each corner of their bottom frames was 18, 54, 90, and 126g, respectively equivalent to 0.1, 0.3, 0.5, and 0.7 kg per unit area of prototype net. The results obtained can be summarizes as follows; Due to the deformation of each net where it was lifted towards the surface in severe conditions, its volume was reduced. This depended highly on the weight of sinkers placed in the bottom corner of cage nets, even if the variation of S sub(n)/S had a little effect on their deformation in current less than 0.4 m/s. In addition, it was observed that the total weight of sinkers for preventing the net from deforming to the extent of less than 50% inside its initial volume was 31 to 245 kg in the range of 0.3 to 0.6 m/s and the adequate design weight of sinker was approximately 0.5 kg per its unit area.