• 한국기계가공학회지
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• 제2권1호
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• pp.39-44
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• 2003

In the present industry, there are necessary to cut not only iron metals but also non-ferrous metals such as aluminum, brass, plastic and wood(Paulownia) therefore it had been made the studies of non-ferrous metals by many scientists. The purpose of this study is to conduct the basic experiment about influencing of the feedrate adjustment and the change of the side rake angle at turning of non-ferrous metals. As the results, the surface roughnesses and Cutting force adjustments were on the decrease with a side-rake angle and feedrate diminution in the case of the plastic, brass, aluminum, and paulownia.

• 조명전기설비학회논문지
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• 제20권10호
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• pp.158-163
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• 2006

In this paper, we considered the received signal of the wideband CDMA systems using turbo code in the multipath channel environments, and analyze the performance of the system. This study is to analyze the performance for the variable system bandwidth according to the number of branches of rake receiver by passing the received signal through a rake receiver with a turbo code in Rayleigh fading channel environments. For the design of receiver in wideband CDMA systems, we presented the efficient parameters for the number of iterative decoding and the number of branches of rake receiver.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2000년도 종합학술발표회 논문집 Vol.10 No.1
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• pp.39-43
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• 2000

본 논문에서는 IMT-2000 시스템에 대한 제안된 표준안을 기초로 송수신 시스템을 구성하여 광대역 무선채널 환경 및 다양한 시스템 운용환경에서 시스템의 성능을 분석한다. 수신 성능의 개선을 위하여 CCI(Co-Channel Interference) Canceller와 Rake 수신기를 혼합하여 기존의 Rake 수신기에서 제거할 수 없었던 자기 간섭(Auto Interference)을 제거하는 새로운 Rake수신기를 제안하였다. 또한 다중 경로 페이딩 모델로는 ITU-R M.1225에서 제시된 모델을 적용하였다. 성능 분석 결과, 상대적으로 작은 지연 확산을 가지는 채널 A가 중간 지연 확산을 가지는 채널 B보다 수신성능이 양호함을 알 수 있었으며, 채널 A와 B에 관계없이 제안된 레이크 수신기를 채용하였을 경우 자기 간섭의 제거 효과로 인해 수신성능이 기존의 레이크 수신기를 채용하였을 경우에 비해 향상됨은 알 수 있었다. 또한 간섭제거기와 제안된 레이크 수신기를 직렬로 연결한 수신기를 채용하였을 경우 다중접속간섭을 효과적으로 제거할 수 있었으며, 수신성능의 차이는 채널 환경이 양호할수록, $E_{b/}$N/ sub o/값이 커질수록 차이가 커짐을 알 수 있었다.다.

• 한국공작기계학회논문집
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• 제10권4호
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• pp.1-6
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• 2001

In the present industry, there are necessary to cut only iron metals but also non-ferrous metals such as aluminum, brass, plastic and wood(Paulownia), therefor it had been made the studies of non-ferrous metals by many scientists. we hope this kind of study will continue. The purpose of this study is to conduct the basic experiment about influencing of the feedrate adjustment and the change of the side rake angle at turning of non-feerous metals. As the results, the surface roughnesses were on the decrease with a side-rake angle and feedrate diminution in the case of the pastic, aluminum, and paulownia.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.929-934
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• 1997

In the present industry, there are necessary to cut not only iron metals but also non-ferrous metals such as aluminum, brass, plastic and wood(Paulownia).therefore it had been made the studies of non-ferrous metals by many scientists. we hope this kind of study will continue. The purpose of this study is to conduct the basic experiment about influencing of the feedrate adjustment and the change of the side rake angle at turning of non-ferrous metals. As the results, the surface roughnesses and Cutting force adjustments were on the decrease with a side-rake angle and feedrate diminution in the case of the plastic, brass, aluminum, and paulownia

• 대한기계학회논문집
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• 제17권11호
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• pp.2664-2675
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• 1993

In this paper, the effects of chip breaker configuration on cutting forces for various cutting conditions are investigated and a method for predicting cutting forces effectively for chip breaker insert in milling is described. Based on the shear plane model and the relevant equations already existing for the relation among the parameters, the method makes use of the analytic geometric approach considering the configuration of cutting too by a 3-dimensional coordinate transformation matrix. The groove type chip breaker insert is modeled to be a double rake insert, represented by the first radial rake angle, the second radial rake angle and the length of land, and the program analyzing the cutting forces is developed. The program capability is verified by comparing the results with the experimental ones for a single cutter; and in case of primary cutting forces, the results of simulation and experiments agree very well showing 2%~16.7% difference within the feed rate range investigated.

• Geomechanics and Engineering
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• 제20권5호
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• pp.421-432
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• 2020

Cutting of rocks is very common encountered in tunneling and mining during underground excavations. A deep understanding of rock-tool interaction can promote industrial applications significantly. In this paper, a distinct element method based approach, PFC^3D, is adopted to simulate the rock cutting under different operation conditions (cutting velocity, depth of cut and rake angle) and with various tool geometries (tip angle, tip wear and tip shape). Simulation results showed that the cutting force and accumulated number of cracks increase with increasing cutting velocity, cut depth, tip angle and pick abrasion. The number of cracks and cutting force decrease with increasing negative rake angle and increase with increasing positive rake angle. The numerical approach can offer a better insight into the rock-tool interaction during the rock cutting process. The proposed numerical method can be used to assess the rock cuttability, to estimate the cutting performance, and to design the cutter head.

• 한국통신학회논문지
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• 제22권1호
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• pp.104-115
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• 1997

This paper investigates PN code acquistion algorithm and demodulation performance of the RAKE receiver in the DS/CDMA(direct sequence code division multiple access) sysytems under a multipath fading channel with multiusers. To speed up the acquisition process, PN matched filter is applied and postdetection integration technique comable withthe dynamic threshold set method is proposed. the Maximum-Likelihood algorithmin serial fashion is able to find PN code delay estimates for the RAKE branches using sliding window in a multipath fading channel. The correct acquistion probability and mean acquistion time are used as a performance measure of the system using the Monte Carlo method. The performance of the RAKEreceiver, afte the code acquisition is achieved is the CDMA systems, is also investigated for three major combining techniques.

• 한국생산제조학회지
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• 제23권6호
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• pp.569-575
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• 2014

In this study, the effect of cutting edge geometry, such as helix and rake angles, on surface roughness in ball-end milling is investigated by using the Taguchi method. A set of experiments adopting the $L_{27}(3^{13})$ design with an orthogonal array are conducted with special WC ball-end mills having different helix and rake angles. Analysis of variance (ANOVA) is performed to analyze the effects of tool geometry and machining parameters, such as cutting speed, feed per tooth, and depth of cut, on surface roughness. The ANOVA results reveal that helix and rake angles are critical factors affecting surface roughness; the interaction of helix angle and cutting speed is also important. This research can contribute to novel cutting edge designs of ball-end mills and optimization of cutting parameters.

• 한국통신학회논문지
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• 제33권5A호
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• pp.500-508
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• 2008

Direct-sequence ultra-wideband(DS-UWB) system is being considered as one of promising transmission technologies for wireless personal area networks(WPANs). Due to relatively low spreading factors and huge bandwidth of transmit signal, a DS-UWB receiver needs to be equipped not only with a rake receiver but also with an equalizer, of which the equalizer is not required for traditional direct-sequence code division multiple access(DS-CDMA) systems. The number of rake fingers is limited in practice, influencing the performance of the subsequent equalizer. In this paper, we derive a decision feedback equalizer(DFE) for DS-UWB systems based on the minimum mean square error(MMSE) criterion, and investigate the impact of various parameters on the DFE performance in realistic scenarios. In particular, we propose an approach to improving the performance of the DFE using additional channel estimates for multipaths not combined in the rake receiver, and discuss how the accuracy of channel estimation affects desirable DFE configuration. Moreover, we present simulation results that show the impact of turbo equalization on the DFE performance.