• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.04a
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• pp.6-11
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• 1997

In most machining operations, undesirable burr are formed on the edge of the workpiece adjacent to the machined surface. Such burrs are often the cause of various problems during automatic maching process. Therefore, it is very important to know characteristics of burr formation in maching process. This paper describes characteristic of exit burrs generated during miniature drilling process. In particular, the effect of spindle speed, feedrate and drill diameter on burr formaton is investigated. The result showed that exit burr height increased significantly with increasing feedrate.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.985-990
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• 1995

Recently, the development of high speed and high precision NC-lathe for piston head machining is needed for the complexity and diversity of the piston head shape used in automobile reciprocating engine. THe piston head has many complex shapes in the aspect of fuel economy, such as ovality, profile, double ovality and recess. Among them, for the maching of the over shape of 0.1~1mm the cutting tool should move periodically symchronized with the rotation of piston workpiece. The cutting tool feeed system must have high positioning accuracy for the precise machining, high speed for the fast maching and high dynamic stiffness for the cutting force. The linear brushless DC motor is used for satisfying these coditions. The ballbush guide and supporting guide using turcite is used for the guidance of the feed drive system. Linear encoder, digital servo ampllifer and controller are used for driving the motor. THis paper presents the design and simulation of the new tool feed system for noncircular machining.

• Journal of the Korean Home Economics Association
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• v.35 no.5
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• pp.177-194
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• 1997

This study attempts to explore urban married women's needs for consumer information contents. In addition, the causality of the needs for consummer information contents and related variables is investigated. Major findings are the following: (1) Respondents' need for information on“the product selection”and “the use and management”of the washing maching or hair dryer is high, while the in need for the information on“the existing brands”is very low. (2) Among several relevent characteristics, respondents' product involvement is strongly related to the needs for consumer information contents. (3) The results of the analysis of casual model from washing maching showed that respondents' age, purchasing experience, perception of the price dispersion and quality difference, self confidence in the product evaluation affect on the need for consumer information contents directly. While respondents' income and education level show a indirect effect. (4) The results of the analysis of causal model from hair dryer showed that respondents' perception of the price dispersion, quality difference and product complexity affect on the need for consumer information contents directly. While respondents' age, purchasing experience, self-confidence in the product evaluation show a indirect effects.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.490-493
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• 2004

There is great difficulty in machine below 10 micrometers by conventional machining methods, such as micro-EDM. However, ultra micro machining using focused ion beam(FIB) is able to machine to 50 nanometers. Bie ＆ moulds techniques are better than one-to-one machining techniques in regards to production costs in the mass production of ultra size structures. Also, it is advantageous to machine die ＆ moulds to the 10 micrometers level by FIB technique rather than other techniques. It is difficult to machine the three dimensional machining, such as micro lens, using FIB system because of their machining characteristics. In this paper, three dimensional machining techniques were properly introduced, and also experiments showed effectiveness of their techniques.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.2 s.173
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• pp.338-346
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• 2000

Although the net-shape molding of composites is generally recommended, molded composites are frequently required cutting or grinding due to the dimensional inaccuracy for precision machine elements . During the composite machining operations such as cutting and grinding, the temperature at the cutting point may increase beyond the allowed limit due to the low thermal conductivity of composites, which might degrade the matrix of composite. Therefore, in this work, the temperature at the cutting point during cut-off grinding of carbon fiber epoxy composites was measured. The cutting force and surface roughness were also measured to investigate the cut-off grinding characteristics of the composites. The experiments were performed both under dry and wet grinding conditions with respect to cutting speed and feed rate. From the experimental investigation, the optimal conditions for the composite cut-off grinding were suggested.

• Journal of the Korean institute of surface engineering
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• v.29 no.5
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• pp.371-378
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• 1996

An RF inductively coupled plasma (ICP) torch has been developed as a typical thermal plasma generator and reactor. It has been applied to various materials processings such as plasma flash evaporation, thermal plasma CVD, plasma spraying, and plasma waste disposal. The RF ICP reactor has been generally operated under one atmospheric pressure. Lately the characteristics of low pressure RF ICP is attracting a great deal of attention in the field of plasma application. In our researches of RF plasma applications, low pressure RF ICP is mainly used. In many cases, the plasma generated by the ICP torch under low pressure seems to be rather capacitive, but high density ICP can be easily generated by our RF plasma torch with 3 turns coil and a suitable maching circuiit, using 13.56 MHz RF generator. Plasma surface modification (surface hardening by plasma nitriding and plasma carbo-nitriding), plasma synthesis of AIN, and plasma CVD of BN, B-C-N compound and diamond were practiced by using low pressure RF plasma, and the effects of negative and positive bias voltage impression to the substrate on surface modification and CVD were investigated in details. Only a part of the interesting results obtained is reported in this paper.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.5
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• pp.27-34
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• 2021

This study analyzes machining characteristics and presents optimal cutting conditions by measuring the surface roughness, dimensional accuracy, and dimension straightness based on the feed rate after processing the inner diameter hall of SCM415 steel using an automatic CNC(Computerized Numerical Control) lathe. The testing material was cut using an 11.8 mm-diameter Chamdrill after mounting the 32 mm-diameter round bar on an automatic CNC lathe. The cut depth was set at 3 mm, and the cutting speed was fixed at 1500 rpm. The surface roughness, dimensional accuracy, and dimension straightness of 15 testings were measured by changing the feed rate to 0.05, 0.1, and 0.15 mm/rev, respectively. It was difficult to process more than 15 tests during the maching due to noise or break. Additionally, the optimum cutting of SCM415 steel showed excellent surface roughness in the 10^th and 11^th of testing at cutting speed and feed speed of 1500 rpm and 0.05 mm/rev, respectively. The dimensional accuracy was measured in three dimensions after drilling, which showed good results with an average range of 0.0138-0.0208 mm. Moreover, the lower the feed speed, the higher the accuracy. Additionally, the measurement results of the dimensional straightness showed that the straightness is the straightness was the best at the 1^th and 2^th cutting regardless of the feed speed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.367-370
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• 2015

This paper proposes an improve method of the detection performance of traffic lights for autonomous driving cars. Earlier detection methods used to adopt color thresholding, template matching and based learning maching methods, but its have some problems such as recognition rate decreasing, slow processing time. The proposed method uses both detection mask and morphological preprocessing. Firstly, input color images are converted to YCbCr image in order to strengthen its illumination, and horizontal edge components are extracted in the Y Channel. Secondly, the region of interest is detected according to morphological characteristics of the traffic lights. Finally, the traffic signal is detected based on color distributions. The proposed method showed that the detection rate and processing time improved rather than the conventional algorithm about some surrounding environments.

• Smart Media Journal
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• v.11 no.3
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• pp.62-73
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• 2022

Researches on the prediction of domestic apartment sales price have been continuously conducted, but it is not easy to accurately predict apartment prices because various characteristics are compounded. Prior to predicting apartment sales price, the analysis of major factors, influencing on sale prices, is of paramount importance to improve the accuracy of sales price. Therefore, this study aims to analyze what are the factors that affect the apartment sales price in Gwangju, which is currently showing a steady increase rate. With 6 years of Gwangju apartment transaction price and various social factor data, several maching learning techniques such as multiple regression analysis, random forest, and deep artificial neural network algorithms are applied to identify major factors in each model. The performances of each model are compared with RMSE (Root Mean Squared Error), MAE (Mean Absolute Error) and R² (coefficient of determination). The experiment shows that several factors such as 'contract year', 'applicable area', 'certificate of deposit', 'mortgage rate', 'leading index', 'producer price index', 'coincident composite index' are analyzed as main factors, affecting the sales price.