• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.9-14
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• 1996

The deflection of an end mill is very important in machining process and cutting simulation because it affects directly workpiece accuracy, cutting force, and chattering. In this study, the deflection of the end mill was studied both experimentally and by using finite element analysis. And the moment of inertia of radial cross sections of tile helical end mill is calculated for the determination of the relation between cross section and rigidity of tile tools. Using tile Bernoulli-Euler beam and and the concept of equivalent diameter, a deflection model is established, which includes most influence from tool geomety parameters. It was found that helix angle attenuates the rigidity of the end mill.

• Nuclear Engineering and Technology
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• v.29 no.1
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• pp.68-77
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• 1997

The reactor power control system is described in the fashion of the order increased LQR system. To obtain the optimal state feedback gain vectors, the weighting matrix of the performance function should be determined. Since the contentional method has some limitations, stochastic searching methods are investigated to optimize the LQR weighting matrix using the modified genetic algorithm combined with the simulated annealing, a new optimizing tool named the hybrid MGA-SA is developed to determine the weighting parameters of the LQR system. This optimizing tool provides a more systematic approach in designing the LQR system. Since it can be easily incorporated with any forms of the cost function, it also provides the great flexibility in the optimization problems.

• Journal of Chest Surgery
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• v.18 no.4
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• pp.855-858
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• 1985

The mediastinoscopy was a well known useful diagnostic tool for detection of mediastinal lymph nodes invasion by bronchogenic carcinoma, and also useful means for histologic diagnosis of metastatic carcinoma and certain mediastinal tumors. 31 cases of mediastinoscopies were reviewed which were experienced at Kyung Hee University Hospital from July, 1979 to June, 1985. We experienced 20 cervical mediastinoscopies, 10 left anterior mediastinotomy, and 1 both procedures. Of the 31 cases, 22 cases were used for preoperative staging of bronchogenic carcinoma, 7 cases for mediastinal tumor diagnosis, and 2 cases for histologic diagnosis of metastatic carcinoma. In 22 mediastinoscopies which were used for preoperative staging, 10 cases were revealed positive mediastinal nodes, and could avoid meaningless thoracotomy. All 12 mediastinoscopy negative patients were received thoracotomy, and 10 of them were resectable. The resectability in bronchogenic carcinoma was 83%, on the contrary, the other series at premediastinoscopic era revealed only 65% resectability. Other mediastinal lesions such as tuberculous granuloma [4], sarcoidosis [2], malignant thymoma [1], and metastatic carcinoma [2] were also diagnosed successfully. Mediastinoscopy is very useful tool for determination of treating method of bronchogenic carcinoma, and for diagnosis of certain mediastinal tumors which, otherwise, need a thoracotomy for confirmatory diagnosis.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.2
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• pp.129-135
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• 1997

Experimental studies have been carried out to obtain uniform cups by one operation of backward extrusion. A lot of factors on dimensional accuracy of backward extruded cups are billet material, billet shape, punch shape, punch velocity, geometry of tool, tool material, and lubrication etc. In manufacturing cup-shaped parts by backward extrusion, it is very important to design the initial billet shape or the preform. The objective of this paper is to find that the shape of the initial billet is related to dimensional accuracy and also to manufacture the more accurate product simultaneously reducing the loss of material as forming the shape of the initial billet by means of upsetting.

• Journal of the Korean Society for Precision Engineering
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• v.9 no.4
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• pp.13-21
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• 1992

Standards concerning the determination of positioning accuracy and repeatability of numerically controlled(NC) machine tools have been published relentlessly over the last 20 years. Since the publication in 1988 of the International Standard 230-2 there has been a pronounced move, both at national and international standards level, to embrace further test procedures for a complete machine tool performance assessment. For example, measurements of angular (pitch, roll, and yaw) and straightness errors along linear axes are now commonplace and complement the existing positioning accuracy and repeatablity tests. More recently the subject of circularity evalutaion has also gained considerable interest. Here dynamic tests, using a kinematic ballbar or circular masterpiece, give an instant overview of the contouring ability of the machine in two axes at specific feedrates. This information is extremely important in optimising machining accuracy. This paper describes moves to complete the machine calibration package in national and international standardis- ation for the assessment of machine tool performance.

• 한국기계연구소 소보
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• s.17
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• pp.69-74
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• 1987

This paper introduces a case-building algorithm which can determine automatically a desired design case by categorizing known-variables and unknown-variables among design variables. Common CAD programs use a case-selection technique, where a programmer sets initially a few of design cases and then users can only choose one of the given cases. The case-building technique is a powerful tool for the expert computer-aided design technology.

• Computational Structural Engineering : An International Journal
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• v.1 no.2
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• pp.97-106
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• 2001

Safety and serviceability of a planar steel frame are assessed. Attention is turned to the individual main steps in the assessment procedure, i.e., to the definition of loads, selection of transformation model, determination of the response of the structure to the loading, and to the definition of the limiting values (considering safely and serviceability of the structure). The potential of the method using direct Monte Carlo technique as a powerful tool is emphasized.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.5
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• pp.107-116
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• 1992

Recently, it is gradually raised necessity that interface is measured accurately and managed in industrial circle and medical world. An Ultrasonic wave transmitted from a focused beam tranducer is being expected as a powerful tool for NDE of the delamination. The Ultrasonic NDE of the delamination is based on the form of the wave reflected from the interface. In this study results, automatically repeated discrimination analysis method can be devided in the category of all kinds of defects on semiconductor package, and also can be possible to have a sampling of partial delamination.

• Journal of Korean Society of Transportation
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• v.3 no.1
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• pp.76-85
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• 1985

The significant role of transportation system for economic development process has been recognized, but the argument that transportation improvements stimulate economic development has brought sometimes no resonance in lacking of a plausible theory on the conditions and process of economic development by transportation investment. This paper reviews the theory on regional differentiation of transportation system and shows why and how the installation of a new transportation system or the improvements of the old transportation quality differentiate the spatial order of economic activities. It presents the interaction between the change of transportation quality with introducing of definition "transportation value" as tool of its determination and economic activities following the regional differentiation process, which result means regional defferentiation of niveau of economic development.

• Proceedings of the Korean Magnestics Society Conference
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• 2009.12a
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• pp.87-88
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• 2009

A model system allowing the experimental determination of the spin-motive force from the vortex gyration motion in a circular nanodisk is presented. It provide an easy experimental detection of the spin-motive force and thus an important tool to study the relationship between the charge and spin transports in ferromagnetic system.