• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집C
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• pp.293-298
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• 2001

In this paper, film thickness and temperature distribution are measured in EHL point contact at high roll/slip ratios. Infrared temperature mapping with two band pass filters, proposed by Ausherman (1976), is used to measure temperature distribution. And the optical interferometric method with two filters (red and green filters) is used to measure film thickness. Result of experiment showed that temperature rising at film and ball surface occurred very dramatically in Dimple zone. As slip velocity, roll/slip ratio and load increased, size of Dimple and temperature rising became more large. In addition, position and shape of Dimple were changed by roll/slip ratios, and increasing of Dimple size decreased traction coefficient. In short, it is appointed that the Dimple phenomenon be developed by the effect of viscosity wedge.

• 한국정밀공학회지
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• 제21권12호
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• pp.127-132
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• 2004

It is very important to find out causes of strip pinching for the high quality of products and fer the stable operation of rolling system. We have examined the strip pinching from three points of view to find out the causes of strip pinching in rolling system: strip shape, rolling operation conditions, and behavior of strip. Wedge, off center, and difference of rolling force through CMD(Cross machine direction) are found to possibly provide major initial causes of strip pinching. Generally strip pinching occurred in the tail of strip. Thus, computer simulations by using a FEM code were also carried out to find out the initial mechanism of strip pinching depending upon the force and geometric boundary conditions at the time of strip tail rolling. The strong compression force effect due to the sudden release of strip tail from the work roll and non-uniform strip tail shape (ex. Fish tail) across the CMD were found to provide possible major causes of strip pinching.

• 한국군사과학기술학회지
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• 제10권4호
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• pp.12-19
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• 2007

In this study, nonlinear flow-induced vibration(flutter) analyses of a 2-DOF launch vehicle airfoil have been conducted in supersonic and hypersonic flow regimes. Advanced aeroelastic analysis system based on computational fluid dynamics and computational structural dynamics is successfully developed and applied to the present analyses. Nonlinear unsteady aerodynamic analyses considering strong shock wave motions are conducted using inviscid Euler equations. Aeroelastic governing equations for the 2-DOF airfoil system is solved by the coupled integration method with interactive CFD and CSD computation procedures. Typical wedge type airfoil shapes with initial angle-of-attacks are considered to investigate the nonlinear flutter characteristics in supersonic(15). Also, the comparison of detailed aeroelastic responses are practically presented as numerical results.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1091-1096
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• 2003

It is very important to find out causes of strip pinching for the high quality of products and for the stable operation of hot roiling system. We have examined the strip pinching from three points of view to find out the causes of strip pinching in hot rolling system: strip shape, rolling operation conditions, and behavior of strip. Wedge, off center, and difference of rolling force through CMD are found to possibly provide major initial causes of strip pinching. Generally strip pinching occurred in the tail of strip. Thus, computer simulations by using a FEM code were also carried out to find out the initial mechanism of strip pinching depending upon the force and geometric boundary conditions at the time of strip tail rolling. The strong compression force effect due to the sudden release of strip tail from the work roll and non-uniform strip tail shape (ex. Tongue tail) across the CMD were found to provide possible major causes of strip pinching.

• Design & Manufacturing
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• 제2권4호
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• pp.48-53
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• 2008

We injection molded a thin type of plate and wedge type of plate with micro prizm patterns on its surface and investigated the fidelity of replication of the micro pattern depending on the process parameter such as mold temperature, melt temperature, injection rate or packing pressure. The size of the $90^{\circ}$ prizm pattern is $50{\mu}m$ and the size of the plate is about $335mm{\times}213mm$ and $400mm{\times}400mm$. The thicknesses are 2.6mm and 0.7mm at each edge of the wedge type of plate and 1mm at each edge of the thin type of plate. The fidelity of the replication turned out quite different according to the process parameters and location of the patterns on the plate. We measured the cavity pressure and temperature in real-time during the molding to analyze the effect of the local melt pressure and temperature on the micro pattern replication.

• 치과방사선
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• 제29권1호
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• pp.283-297
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• 1999

Purpose: To compare radiographic images of Digora/sup (R)/ system and Ektaspeed Plus film obtained from normal adults. Materials and methods: Storage phosphor plate(SPP) was placed in a film holder behind Ektaspeed Plus film package without lead foil. The effect of film on SPP was studied in a separate in vitro experiment. Forty-seven sets of images were prepared for the evaluaton. The regions of interest(ROI) for evaluation were designated at seven sites including normal anatomical structures. The image quality for each ROI was evaluated on enhanced and unenhanced storage phosphor(SP) images and Ektaspeed Plus film. Results: Two film-SPP configurations showed significantly different gray levels at each step of the aluminum step wedge(p<0.05). The contrasts were comparable. Enhanced SP images were significantly superior to unenhaned images and film in all anatomical sturctures(p<0.01). The differences between unenhanced SP images and film were significant(p<0.05) except root canal and cortical bone on alveolar crest. For anatomical items. there were statistically significant difference among five observers(p<0.05). Conclusions: The image quality of enhanced SP images were superior to Ektaspeed Plus film. and Digora system is potentially applicable to clinical diagnosis.

• 한국해양공학회지
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• 제21권3호
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• pp.8-15
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• 2007

This study is intended to examine the relationship between the magnitude of sand spit in the estuary of the stream and improvement of the quality of water that flaws into the sea, by means of hydraulic experimentation. In order to determine the effect of improvements of water quality when river flow is stagnant, the estuary flows into the sea through the small sand spit, and a two-dimensional physical model experiment was carried out. Distribution of concentration was decreased in response to an increase in length of sand spit and time. The experimental results are compared with theoretical results, based on the solution of the equation. Also, there are functions of influx prevention of salt wedge and purification of pollution water due to sand spit in small estuary.

• Journal of Magnetics
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• 제21권1호
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• pp.133-140
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• 2016

In this study the contralateral breast skin dose was decreased. It was to apply the results to the clinical study after analysis of different radiation dose amounts to contralateral breast with nonmagnetic bolus and without nonmagnetic bolus. A Rando phantom was computed tomography (CT) simulated, five treatment plans were generated: open tangents, open field in field, wedge 15, wedge 30, and intensity-modulated radiotherapy (IMRT) plan with 50.4 Gy to cover sufficient breast tissue. Contralateral breast skin dose was measured at 8 points using a glass dosimeter. The average contralateral breast dose using nonmagnetic bolus showed better excellence in decreasing the absorbed dose in the order of $168{\pm}11.1$ cGy, $131{\pm}10.2$ cGy (29%), $112{\pm}9.7$ cGy (49%), and $102{\pm}9.5$ cGy (64%) than changing the treatment plan. This study focused on decreasing the effect of scattered dose by use of a nonmagnetic bolus on the contralateral breast during radiotherapy in breast cancer patients and an intriguingly significant decrease was observed parallel to the opposed beam.

• 대한정형도수물리치료학회지
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• 제13권1호
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• pp.26-35
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• 2007

The purpose are to demonstrate the pain, stiffness, and physical function by the Korean Western Ontario MacMaster University(KWOMAC) score of the patients with varus deformity osteoarthritis of the knee after treatment period. Twenty outpatients with knee osteoarthritis(OA) were randomized and divided into the control(n=10) and wedge(n=10) groups. The remission scores of the KWOMAC index of severity for knee OA were compared between the groups. The result of repeated two-way ANOVA's revealed that a contact lateral-wedged insole with strapping produced significantly differences in the pain and physical function score between groups after treatment period(P<0.05), but it was not significant differences in the stiffness score between groups(P>0.05). These results suggest that the pain relief and improvement in function reported by patients with osteoarthritis while using lateral-wedged insole with strapping may be achieved by a reduction in external varus moment and medial compartment load.

• 한국해양공학회지
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• 제20권2호
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• pp.66-71
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• 2006

To develope a hull form of catamaran type dredging vessel, resistance characteristics is investigated to find the interaction effect of waves between the two hulls. Re fore body shape is simplified as two dimensional wedge shape for the maintenance and disassembly/assembly. Based on MAC method, numerical simulation is performed in staggered variable mesh system. Re conservation form of Euler equations and continuity equation are applied as governing equations. To verify numerical methods, the wive patterns along the hull surface are compared with the results of model tests. This study is performed as varying wedge shape of the bow and the distance between the two hulls. The wave interaction between two hulls are observed to investigate the relation the resistance performance and the flow characteristics. Suitable hull form and distance between two hulls are discussed.