• Korean Journal of Food Science and Technology
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• v.17 no.3
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• pp.208-212
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• 1985

The residence time distributions were measured experimentally to determine the effect of reverse screw elements at various screw configurations in twin screw extruder. A simple model was used to estimate the number of filled C-chamber on the forwarding screw. The inclusion of reverse-screw elements resulted in the increase of median residence time and the broadening of color distribution. True residence time was affected by using the reverse screw elements just before the die. The number of filled C-chamber was decreased with the increase of screw revolution speed at the same screw configuration.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.3
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• pp.345-353
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• 2007

Statement of problem. Implant abutment screw joints tend to loosen under clinical conditions. Abutment screw loosening results in loss of preload in function. Purpose. Anti-rotational inner post screw (ARIPS) systems were compared with conventional abutment screws to reduce screw loosening. Reverse torque values were evaluated. Material and methods. 32 implant assemblies (Warentec, Co, Ltd, Seoul, Korea) were organized as the 30-Ncm-torque conventional groups and 30-Ncm-torque ARIPS groups in external and internal system. The specimens were tested to 106 cycles at a load of 200N. Preload reverse torque, postload reverse torque, and the ratio of postload reverse torque to preload reverse torque were evaluated. The data were analyzed with unpaired t-test in external and internal systems. Results. In the ratio of postload reverse torque to preload reverse torque, the ARIPS groups showed significant differences than the conventional screw group in both external and internal system. Conclusion. Within the limitations of this study, abutment screw loosening was effectively reduced using ARIPS system.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.1
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• pp.93-98
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• 2010

The metal fastening method is the new technology to repair cracks in the casting material using specially designed reverse screws. In this study, we conduct the finite element analysis to analyze the pulling force characteristic of a reverse screw, the core component of the metal fastening method, with respect to the change of the applying torque, frictional coefficient and front screw angle. The simplified analysis model with single screw pitch is proposed for convergency of the non-linear contact analysis. As a results, the pulling force of a reverse screw increase in proportion to the applying torque but exponentially decrease according to frictional coefficient. And also we can find the optimum front screw angle with the largest pulling force is $20^{\circ}$.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.4 no.2
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• pp.24-30
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• 2005

This research presents a modeling and a manufacturing method of screw flow meter. This paper introduces the efficient design and manufacturing method of screw type flow meter using reverse engineering and test technology. The methods introduced this paper utilize the reverse engineering that is increasing accuracy of modeling and manufacturing of reverse model. And then it can be used in performance test with hydraulic test equipment. Hence this can be used in the basic document for development of the quite accurate flowmeter.

• 유체기계공업학회:학술대회논문집
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• 2005.12a
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• pp.601-606
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• 2005

This research presents a modeling and a manufacturing method of screw flow meter. This paper introduces the efficient design and manufacturing method of screw type flow meter using reverse engineering and test technology. The methods introduced this paper utilize the reverse engineering that is increasing accuracy of modeling and manufacturing of reverse model. And then it can be used in performance test with hydraulic test equipment. Hence this can be used in the basic document for development of the quite accurate flowmeter.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.132-137
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• 2005

This research presents a modeling and a manufacturing method of screw type flow meter. This paper introduces the efficient design and manufacturing method of screw type flow meter using reverse engineering and test technology. The methods introduced this paper utilize the reverse engineering that is increasing accuracy of modeling and manufacturing of reverse model. And then it can be used in performance test with hydraulic test equipment. Hence this can be used in the basic document for development of the quite accurate flow meter.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.3
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• pp.246-261
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• 2002

The screw loosening is one of the complications that happen frequently in dental implant prostheses. The purpose of this study was to evaluate the changes of reverse/loosening (opening) torque of the screw according to the surface modifications by sandblasting and 24K gold electroplating as well as to determine the possibility of the clinical use of a washer in dental implant. The reverse torque of 4 experimental conditions(control, sandblasted, use of washers, electroplasted) was measured by digital torque gauge (Model MGT50Z, Mark-10 Corp., 458 West John Street Hicksville, NY 11801 USA). Electronic torque controller (Nobel Biocare DEA 020) was used in fastening the gold screws into abutment replicas. Mixed Linear Model Analysis method was used for statistical analysis. To examine the changes of screw thread surface, microphotographs were taken by Olympus PME-3 metallurgic microscope (Olympus Optical Co. Ltd., Tokyo, Japan). Within the limitations of this study, the following results were drawn: 1. The surface modifications of the gold screws and the use of a washer have significantly affected the reverse torque value compared to the control group (P<0.01). 2. Sandblasting and electroplating treatments demonstrated significantly higher reverse torque value than that of control group. 3. The use of a washer may be one of the useful clinical methods that prevent the screw loosening. However, further studies are necessary for the material selection and design of the washer.

• Journal of Trauma and Injury
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• v.23 no.1
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• pp.1-5
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• 2010

Purpose: To investigate the results of treatment of reverse oblique trochanteric fractures with compression hip screw. Methods: We reviewed the results of 12 cases of reverse oblique trochanteric fracture treated with compression hip screw from January 2000 to December 2006 which could be followed up for more than 1 year. The mean follow up period was 26 months (15~40). The mean age was 48 years old. Injury mechanism was composed of 6 cases of traffic accident and 6 cases of fall down. 8 persons were man. We investigated the union time, degree of neck-shaft angle change, amount of sliding of compression hip screw, complications, functional and clinical results. Results: 10 cases were united and the mean union time were 5 months (3~8). The mean neck-shaft angle change was 3.5 degrees (0~12). The amount of sliding of compression hip screw was 8.9 mm (2~24). There were six coxa vara, six leg due to coxa vara shortening, two nonunion, and one superficial infection. Unsatisfactory results of Jensen's social function score and Parker and Palmer's mobility score were studied. Conclusion: The results of treatment of reverse oblique trochanteric fractures with compression hip screw were relatively unsatisfied.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.4 no.3
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• pp.51-56
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• 2005

This research presents a modeling and a manufacturing method of screw flow meter. This paper introduces the efficient design and manufacturing method of screw type flow meter using reverse engineering and test technology. The methods introduced this paper utilize the reverse engineering that is increasing accuracy of modeling and manufacturing of reverse model. And then it can be used in performance test with hydraulic test equipment. Hence this can be used in the basic document for development of the quite accurate flowmeter.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.5
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• pp.87-95
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• 2009

This research introduces the efficient modeling and manufacturing method using reverse engineering combined with rotational simulation of a pair of screw and mill-turn machining realized a proposed NC program. Because previously developed model had insufficient flow measuring accuracy, we considered that matter in the aspect of method of modeling and performance test. For that reason we modified the modeling which could minimize a gab between male and female screw, and developed precise tester which consists of constant tank, flowmeter and load cell, etc., and then conducted the test for defining characteristic and accuracy of flowmeter and repeated same test 5-times. Consequently we could obtain satisfied measuring accuracy and reproducibility indicated in the catalog of master model. Hence we give our conclusion as to the validity of developing accurate screw type flowmeter using the proposed process such as reverse engineering, mill-turn machining and precise performance test.