• 한국정밀공학회지
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• 제16권4호통권97호
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• pp.71-78
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• 1999

The determination of the optimum biarc curve passing through a given set of points along involute curve is studied. The method adopted is that of finding the optimum number of span and the optimum length of the span such that error between the biarc curve and involute curve minimum. Iterative method is effectively used to find the optimim number and length of the span on involute curve with reduced length of NC-code.

• 한국정밀공학회지
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• 제13권12호
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• pp.78-85
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• 1996

The determination of the optimum biarc curve passing through a given set of points along involute curve is studied. The method adopted is that of finding the optimum no. of span and the optimum length of the span such that the error between the biarc curve and involute curve is minimum. Irregular curve span method is effectively used to describe the involute curve with reduced length of NC-Code.

• 한국인터넷방송통신학회논문지
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• 제15권2호
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• pp.31-37
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• 2015

사물인터넷(IoT)의 여러 분야에서 영상 정보의 보안은 매우 중요하며, 그 보안(저작권 등)을 표시하는 여러 방안을 연구하고 있다. 본 논문에서는 IoT에서 사용하는 영상 정보는 이산 코사인 변환(DCT)과 양자화를 통하여 계수값(QC)으로 변환된다. 그리고 워터마크(메시지)는 QR Code를 통하여 새로운 부호화된 메시지(WMQR)를 만든다. QC와 WMQR은 스테가노그래피 LSB 기법을 적용하고, 영상정보의 보안(저작권 등)을 얻을 수 있다. 스테가노그래피의 LSB 기법은 위치(Secret Key)의 결정에 따라 메시지를 삽입할 수 있다. 부호화된 영상은 인터넷을 통하여 수신자에게 전송하게 된다. 역 과정에서는 영상과 QR 코드, 워터마크(Message)를 얻을 수 있다. 영상정보의 보안에서 워터마크를 추출하는 방법은 부호화된 영상과 Secret Key 만을 사용하며, DCT와 양자화 과정을 통하여 워터마크(Message)를 분리하여 얻을수 있다. 본 논문에서 우리는 영상정보의 보안의 방법을 개선할수 있었으며, 이 모의실험을 통하여 영상의 화질(PSNR), 정규화 상관도(NC)를 통하여 높은 보안성을 얻을 수 있었다.

• 한국정밀공학회지
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• 제15권4호
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• pp.91-97
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• 1998

Design methodology of Interactive Measuring Part Program Generating Tools(IMPPGT) realized on the FANUC 15MA using touch trigger probes and interactive macro functions of the CNC was described in this paper. Measuring G codes were designed according to geometric form, precision attributes, relations between parts, datum hierarchies, and relevant technological data by using measuring arguments. Menu driven measuring and inspection functions of the IMPPGT were studied and implemented on the CNC through the macro executor and ROM writer. Using the developed measuring G code system on the machine tool, untended measurement and inspection operation was able to be realized in precision FMS lines.

• 한국CDE학회논문집
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• 제2권2호
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• pp.85-92
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• 1997

An axial flow fan design system has been made by integrating the self-developed programs and I-DEAS. By using the system, an axial flow fan was designed, manufactured and verified through the wind tunnel experiments in coorperation with a refrigerator appliance division. It has been shown that the optimal design without the ambiguity of the design parameters can be possible by the three-dimensional flow simulations using a self-developed CID code, FANS-3D. (Flow Analysis code using Navier Stokes aguations in Three-Dimensional curvilinear coordinates). By virtue of the fluency of the data flow, an optimally designed fan which satisfies design conditions can be selected in a short time and less cost. The manufacturing processes of a Mock-up and an injection molding die have been automated through the self-made interface programs which connnect from the start to the end. It has been shown that the newly developed fan by this system has a superior performance characteristics to an existing fan.

• Nuclear Engineering and Technology
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• 제56권4호
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• pp.1320-1329
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• 2024

When wall-thinning occurs in nuclear Class 2 and 3 pipes, reinforcement is typically applied rather than replacement. To analyze the structural integrity of reinforced wall-thinned pipe, stress analysis results using full 3-D FE analysis are not compatible to the design code equation, ASME BPVC Sec. III NC/ND-3650. Therefore, the efficient stress evaluation method for the reinforced wall-thinned pipe, compatible to the design code equation, needs to be developed. In this paper, stress evaluation methods for the reinforced wall-thinned pipe are proposed using the equivalent straight pipe concept. Furthermore, for fatigue analysis of the reinforced wall-thinned pipe, the stress intensification factor of reinforced wall-thinned pipe is presented using the structural stress method given in ASME BPVC Sec. VIII Div.2.

• 한국전자통신학회논문지
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• 제16권6호
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• pp.1295-1302
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• 2021

3D 프린터의 시장 규모가 증가되는 시점에서 출력물에 대한 정밀도와 모터에 의한 작업속도는 매우 중요한 사항 중 하나이다. 본 논문에서는 PLC 장비와 아두이노 CNC의 동일 출력물 비교를 위해서 CURA 프로그램을 이용하여 동일 출력물의 G-code를 생성하였으며, NC File로 변환 후, 각각의 장비에 펜을 부착하여 A4 용지에 특정 결과물을 출력하였다. 그 결과, 출력 시간이 PLC 장비의 경우 1m 39s, 아두이노 CNC의 경우 2m 5s로 측정되었으며 2D 출력물이 두 장비에서 동일하게 출력되는 것을 확인하였다.

• 한국정보과학회논문지:정보통신
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• 제41권4호
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• pp.186-191
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• 2014

네트워크 코딩은 시스템에서 전송되는 패킷 개수를 줄여 성능향상을 줄 수 있기 때문에 기존 연구들은 네트워크 코딩 기회를 극대화하는 점에만 집중하였다. 하지만 각 소스노드가 채널상황을 고려하여 코딩을 수행하는 중간노드로 최대한 높은 속도로 전송하기 때문에 혼잡을 발생시킬 수 있다. 따라서 본 연구에서는 채널상황과 혼잡을 고려하여 이득이 확실한 경우에만 기회적으로 네트워크 코딩을 수행하는 기법을 제안했다. 중간노드는 코딩할 수 있는 네트워크 코딩 조합 중에서 데이터 손실과 혼잡을 최소화하고 전송횟수를 줄일 수 있는 목적함수를 동적프로그래밍을 통해 구하고 최적의 코딩 조합을 선택한다. 퀄넷 시뮬레이터를 활용한 성능평가를 통해 제안하는 기법이 기존 연구들에 비해서 최대 20% 성능향상이 있음을 증명했다.

• Journal of Mechanical Science and Technology
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• 제18권7호
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• pp.1055-1061
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• 2004

In this research, a vision system for detecting breakages of small-diameter taps, which are rarely detected by the indirect in-process monitoring methods such as acoustic emission, cutting torque and motor current, was developed. Two HMI (Human Machine Interface) programs to embed the developed vision system into a Siemens open architecture controller, 840D, were developed. They are placed in sub-windows of the main window of the 840D and can be activated or deactivated either by a softkey on the operating panel or the M code in the NC part program. In the event that any type of tool breakage is detected, the HMI program issues a command for an automatic tool change or sends an alarm signal to the NC kernel. An evaluation test in a high-speed tapping machine showed that the developed vision system was successful in detecting breakages of small-diameter taps up to M1.

• Nuclear Engineering and Technology
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• 제52권9호
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• pp.1955-1962
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• 2020

In a sudden shutdown of primary pump or coolant loss accident in a marine nuclear power plant, the primary flow decreases rapidly in a transition process from forced circulation (FC) to natural circulation (NC), and the lower flow enters the steam generator (SG) causing reverse flow in the U-tube. This can significantly compromise the safety of nuclear power plants. Based on the marine natural circulation steam generator (NCSG), an experimental loop is constructed to study the characteristics of reverse flow under middle-temperature and middle-pressure conditions. The transition from FC to NC is simulated experimentally, and the characteristics of SG reverse flow are studied. On this basis, the experimental loop is numerically modeled using RELAP5/MOD3.3 code for system analysis, and the accuracy of the model is verified according to the experimental data. The influence of the flow variation rate on the reverse flow phenomenon and flow distribution is investigated. The experimental and numerical results show that in comparison with the case of adjusting the mass flow discontinuously, the number of reverse flow tubes increases significantly during the transition from FC to NC, and the reverse flow has a more severe impact on the operating characteristics of the SG. With the increase of flow variation rate, the reverse flow is less likely to occur. The mass flow in the reverse flow U-tubes increases at first and then decreases. When the system is approximately stable, the reverse flow is slightly lower than obverse flow in the same U-tube, while the flow in the obverse flow U-tube increases.