• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.63-68
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• 1996

In this study, the effect of tool rake angles and the change of cutting conditions on specific cutting pressure in face milling is investigated. The cutting force in face milling is predicted from the double cutting edge model in 3-dimensional cutting. Conventional specific cutting pressure model is modified by considering the variation of tool rake angles. Effectiveness of the modified cutting force model is verified by the experiments using special face milling cutters with different cutter pockets and various rake angles. From the comparison of the pressented model and the specific cutting pressure, it is shown that the axial force can be predicted by the tangential and redial forces without the knowledge of friction angle and shear angle. Also, the relation between specific cutting pressure and cutting cindition including feedrate, cutting velocity and depth of cut is studied.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.5
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• pp.116-123
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• 2000

This paper presents an NC code post-processor that adjusts feedrates to keep the variation of metal removal rate along the tool paths minimum. Metal removal rate is estimated by virtually machining the part, whose surface model is built from a series of NC codes defined in operation plan, with cutting-tool-assembly models, whose geometry are defined in a machining database. The NC code post-processor modifies the feedrates by the adjustment rules, which are based on the machining knowledge for effective machining. This paper illustrates a procedure fur grouping machining conditions and we also show how to determine an adjustment rule for a machining-condition group. An example part was machined and it shows that the variation of cutting force was dramatically reduced after applying the NC code post-processor. The NC code post-processor is expected to increase productivity while maintaining the quality of the machined part.

• Communications for Statistical Applications and Methods
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• v.16 no.5
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• pp.821-840
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• 2009

This article addresses the problem of estimating a family of general population parameter ${\theta}_{({\alpha},{\beta})}$ using auxiliary information in the presence of measurement errors. The general results are then applied to estimate the coefficient of variation $C_Y$ of the study variable Y using the knowledge of the error variance ${\sigma}^2{_U}$ associated with the study variable Y, Based on large sample approximation, the optimal conditions are obtained and the situations are identified under which the proposed class of estimators would be better than conventional estimator. Application of the main result to bivariate normal population is illustrated.

• Journal of Korean Neurosurgical Society
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• v.57 no.3
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• pp.219-220
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• 2015

Variations in the course and distribution of common palmar digital nerves and arteries are rare. A classic common palmar digital nerves and arteries are defined as concomitant. During routine dissection classes to undergraduate medical students we observed formation of each common palmar digital nerve divided into 2 or 3 branches and formed a ring enclosing the corresponding common palmar digital artery. Knowledge of the anatomical variations of the common palmar digital nerves and arteries is crucial for safe and successful hand surgery.

• Proceedings of the KIEE Conference
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• 2001.07e
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• pp.108-112
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• 2001

Vector control schemes are used in inverter-fed induction motor drives to obtain high performance. Crucial to the success of the vector control scheme is the knowledge of the instantaneous position of the rotor flux. However, the position of the rotor flux change with temperature and magnetic saturation of the motor. This variation cause deterioration of both steady state and dynamic operation of the motor drives. Performance degradation is in the form of input-output torque nonlinearity and saturation of the motor. Analytic expressions are derived to evaluate the effects due to parameter sensitivity.

• The Journal of Fisheries Business Administration
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• v.30 no.2
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• pp.79-89
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• 1999

This study is conducted to apply the insight of Johnson and Libecap(1982) to Korea's coastal vessel fishing. According to Johnson and Libecap(1982) the differences in fishing ability are largely attributed to acquired knowledge and innate skills. Since those skills are unlikely to be readily transferable assets, economic rents exist in the fishery, even under open access conditions. Therefore the paper tries to examine whether the acquired information from fishing experience and innate skill could also have an effect on catch variation of coastal vessel fishing in Kyung-Nam province. To do so, the paper is performing the analysis by establishing econometric model. Results show us that the acquired information from fishing experience have a significant effect on catch variation, but the innate skill does not.

• Wind and Structures
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• v.10 no.3
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• pp.249-268
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• 2007

Past experience indicates that the majority of failures of electrical transmission tower structures occurred during high intensity wind events, such as downbursts. The wind load distribution associated with these localized events is different than the boundary layer wind profile that is typically used in the design of structures. To the best of the authors' knowledge, this study represents the first comprehensive investigation that assesses the effect of varying the downburst parameters on the structural performance of a transmission line structure. The study focuses on a guyed tower structure and is conducted numerically using, as a case study, one of the towers that failed in Manitoba, Canada, during a downburst event in 1996. The study provides an insight about the spatial and time variation of the downburst wind field. It also assesses the variation of the tower members' internal forces with the downburst parameters. Finally, the structural behaviour of the tower under critical downburst configurations is described and is compared to that resulting from the boundary layer normal wind load conditions.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.1
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• pp.113-120
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• 1994

The dynamic characteristics of turning processes are complex, non-linear and time-varying. Consequently, the conventional techniques based on crisp mathematical model may not guarantee cutting force regulation. This paper presents a fuzzy controller which can regulate cutting force in turning process under varying cutting conditions. The fuzzy control rules are extablished from operator experience and expert knowledge about the process dynamics. Regulation which increases productivity and tool life is achieved by adjusting feedrate according to the variation of cutting conditions. The performance of the proposed controller is evaluated by cutting experiments in the converted conventional lathe. The results of experiments show that the proposed fuzzy controller has a good cutting force regulation capability in spite of the variation of cutting conditions.

• Iberoamérica
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• v.21 no.1
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• pp.127-158
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• 2019

In this paper, the variation in coda /ɾ/ is analyzed in the Spanish of the Tupe district in Peru. The work was carried out on the corpus of 24 semi-structured interviews. Four variants of /-ɾ/ were distinguished and 1920 tokens were analyzed. Praat was used to recognize and describe the variants and two statistical analysis were carried out: descriptive analysis and probabilistic analysis using the statistical program Goldvarb X. The results obtained from the analysis show that the assibilated variant is favored in the prepausal position and before homorganic consonants. The frequency of occurrence was very low before other consonants. Regarding the social factor that contributes to the assimilated variant, the young and middle-aged men (from 20 to 60), those who did not live more than a year on the Peruvian coast and male speakers favor it.

• International Journal of Precision Engineering and Manufacturing
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• v.2 no.1
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• pp.62-75
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• 2001

The design and manufacture of injection molded polymeric parts with desired properties is a costly process dominated by empiricism including repeated modification of actual tooling. This paper presents and expert design evaluation system which can predict the mechanical performance of a molded product and diagnose the design before the actual mold is machined. The knowledge-based system synergistically combines a rule-based expert system with CAE programs. An iterative boundary pressure reflection method(IBPR) is developed to automate the cavity filling simulation program and to predict thermo-mechanical properties of a molded part precisely. Mathematical models of weldline and frozen-in molecular orientation are established to determine the spatial variation of microstructural anisotropies of a molded part from the result of cavity filling simulation. The strength ellipse is devised as and index which represents th spatial distribution of the microstructural anisotropies of a molded part, Heuristic knowledge of injection molding, flow simulation, and mechanical performance prediction is formalized as rules of an expert consultation system. The expert system interprets the analytical results of the process simulation, predicts the performance, evaluates the design and generates recommendations for optimal design alternative.