• International Journal of Precision Engineering and Manufacturing
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• v.4 no.5
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• pp.27-33
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• 2003

G-code, another name of ISO6983, has been a popular commanding language for operating machine tools. This G-code, however, limits the usage of today's fast evolving high-performance hardware. For intelligent machines, the communications between machine and CAD/CAM departments become important, but the loss of information during generating G-code makes the production department isolated. The new standard for operating machine tools, named STEP-NC is just about to be standardized as ISO14649. As this new standard stores CAD/CAM information as well as operation commands of CNC machines, and this characteristic makes this machine able to exchange information with other departments. In this research, the new CNC machine operated by STEP-NC was built and tested. Unlike other prototypes of STEP-NC milling machines, this system uses the STEP-NC file in XML file form as data input. This machine loads information from XML file and deals with XML file structure. It is possible for this machine to exchange information to other databases using XML. The STEP-NC milling machines in this research loads information from the XML file, makes tool paths for two5D features with information of STEP-NC, and machines automatically without making G-code. All software is programmed with Visual $C^{++}$, and the milling machine is built with table milling machine, step motors, and motion control board for PC that can be directly controlled by Visual $C^{++}$ commands. All software and hardware modules are independent from each other; it allows convenient substitution and expansion of the milling machine. Example 1 in ISO14649-11 having the full geometry and machining information and example 2 having only the geometry and tool information were used to test the automatic machining capability of this system.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.5
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• pp.1074-1083
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• 1993

NC simulation has been used to replace the test cutting of NC machining. Although it can reduce the NC part programming effort, it still has a problem. If any error is found during the simulation, then the part has to be reprogrammed and it is time consumming. This paper presents a method for verifying and editing the NC code after the post-processing without going back to the part programming stage. A data structure and an algorithm to verify and edit the NC code interactively with the aid of graphics is introduced. Z-map method is used for the shaded image display and cross-sectional view display of the macined parts. The method was implemented in a IBM/PC-386 with MS-Windows software, and the multi-window function of the of the MS-Windows is used for the simultaneous editing and verification.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.229-232
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• 2000

This research aims at developing a low-cost PC-NC system based on one-CPU and investigating the feasibility of its application to a simple-function lathe. Its hardware consists a two axes motion control board including a 24bit counter, 8253 timer, a 12bit DA converter, DIO board for PLC operation and a PC with Intel Pentium 466MHz. The fundamental real-time MC functions such as G-code interpretation, interpolation, position and velocity control of axes are performed. User programming interface with functions of icon manipulation, tool-path simulation and NC-code generation was implemented. In order to achieve real-time control and safety, axis control, NC interpretation, interpolation and user communication are completely executed during every interrupt interval of I msec.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.734-739
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• 2001

In this paper, we develop a six-axes machining center tool(MCT) and CAD/CAM system. The MCT consists of two mechanical parts, i.e., a X-Y-Z Cartesian coordinate typed MCT and a parallel-typed tilting table. Kinematics and singularity are accomplished to design the parallel-typed tilting table, and CAD/CAM system is developed for the six-axes MCT, which requires the commands of position as well as orientation for machining of complex shape. The CAD/CAM system has a tool path generator, a NC code generator and a graphic simulator. This paper designs the parallel-typed tilting table to meet the desired specification and presents the results of tool path, NC code and graphic simulation.

• Korean Journal of Computational Design and Engineering
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• v.5 no.4
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• pp.312-318
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• 2000

In this study, an exclusive CAD/CAM system is developed for enhancing the effectiveness and productivity of CNC universal cylindrical grinding machines on which the external/facing/internal grinding cycles and the wheel dressing cycles are integratively carried out. The CAD/CAM system can manage the various processes such as geometry design, NC code generation, NC code verification, DNC operation, and so on. Especially, the feature-based modeling concept is introduced to improve the geometry design efficiency. And the NC code verification is realized by virtual manufacturing technique based on the real-time analysis of NC codes and the boolean operation between workpiece and wheel.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.7
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• pp.612-622
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• 2013

In this paper, we propose a coding packet group-based ARQ scheme (rNC) for file delivery in wireless networks. rNC assumes multiple network coding points between the source and the destination. Each network coding point gathers and codes a group of packets according to the queue polling system. A queue polling system makes a few or several packets available for coding in a queue while polling the other queues in the system. Thus, we assuem a queue polling system at each network coding point. We call this group of packets as coded packet group. Each coding point acknowledges the reception of every code packet group to its previous coding point for reliable delivery. Thus, the intermediate coding points including the source can release its buffer before the packet is delivered to the destination. To guarantee the ultimate file delivery to the destination, the destination sends acknowledgement to the sender. We evaluate our proposed scheme using ns-2 and compare the performance with CodeCast. The results show that rNC works better than CodeCast in terms of packet delivery ratio and control overhead in unreliable wireless networks.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.191-194
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• 1998

본 논문에서는 OFDM 시스템에서 사용되는 부 반송파의 수와 동일한 길이의 complementary code를 사용하여 각 부 반송파 데이터를 frequency 영역에서 scrambling하는 PAPR 감소 방안을 제안한다. 이 방법은 부 반송파의 수와 동일한 길이의 complementary code 집합을 이용하여 주어진 데이터에 부과해서 PAPR 값이 가장 적은 complementary code를 사용하여 scrambled된 데이터를 송신함으로서 PAPR 값을 감소시키는 방법이다. 수신기에서의 복호를 위하여 Nc개의 complementary code에 해당하는 log2Nc 비트의 code 인덱스를 데이터와 함께 전송한다. 이때 code 인덱스 비트가 PAPR 값에 영향을 주지 않도록 하기 위하여 CODE인덱스와 데이터가 함께 complementary code로 scrambling되어진다. 제안된 이 방법을 사용하면 주파수 대역효율을 높이면서 PAPR 값을 크게 줄일 수 있다.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.5
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• pp.15-24
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• 2000

NC 기술은 하드웨어적, 소프트웨어적으로 빠르게 발전하고 있다. 소프트웨어적인 측면에서 NC제어기는 다양한 적응제어, 지능제어를 지원하는 추세이며, NC 가공기의 경우 고속가공, 정밀가공의 기능적 측면에서 발전이 이루어지고 있다. 뿐만 아니라, 컴퓨터 기술의 발전에 힘입어 NC가공을 지원하기 위한 환경(CAD, CAM, CAE) 역시 바르게 변화하고 있다. 그러나 CAM과 CNC 사이의 데이터 인터페이스는 여전히 ISO 6983(“G-Code”)이 사용되고 있다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.11
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• pp.3091-3097
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• 1994

An expert system for NC part programming of NC lathe (ESPP-1) is developed as a part of Computer-Adied Manufacturing system. Conventional computer-assisted part programming system essentially requires an NC part programmer who is an expert in NC part programming. But the developed ESSP-1 can allow an inexperienced person to make an excellent NC data for the NC Lathe without any problem, since the system has a knowledge base composed of EIA and ISO NC code, feed rate, spindle speed, machining coordinates selection, and tool selection etc., which were directly evoked from some skilled NC part programmers, and referenced some machining handbooks. This paper discusses the algorithm of the expert system for NC part programming of the NC lathe (ESPP-1) and the performance comparisons between the developed expert system and the conventional system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.428-433
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• 1993

In this paper, the fast algorithm to calculate cutting force of milling and its application to NC verification system have been studied. The fast force algorithm can calculate the maximum cutting force fastly during one revelotion of tool. The NC verification using the fast force algorithm can verify excessive cutting force which is the cause of deflection and breakage of tool, and can so adjust the feed rate as to manufacture with the maximum force criterion or maximum machining error criterion. So, the fast force algorithm has been added to the NC verification system, the NC verification system can verify the physical problems in NC code effectively.