• Journal of Welding and Joining
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• v.16 no.2
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• pp.64-72
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• 1998

This study aims a investigating the effect of volume fraction of chromium carbide phase(VFC) of hardfaced iron/chromium alloys on fracture toughness. The alloys were deposited twice on a mild steel plate using self-shielding flux cored arc welding process. In order to examine VFC effect, different VFC (0.28∼0.62) were employed by changing the Cr and C content, while the ratio of Cr/C was fixed in the range of 5.7∼6.6. Fracture toughness was constant as increasing VFC because fracture surface was developed in the eutectic phase which was growing parallel with introduced sharp notch in the hypoeutectic alloys, but fracture toughness did not decreased in spite of increasing volume fraction of coarse primary chromium carbide phase which was easily craced at the low stress because the growth direction of chromium carbide phase were more irregular as increasing VFC in the hypereutectic alloys.

• Journal of the Korean Institute of Telematics and Electronics
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• v.15 no.6
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• pp.87-90
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• 1978

In previous VFC type A/D converter high linearity charateristics knave been achieved to several hundred kHz, and in the converter with maximum output frequency of several MHz, the conversion linearity is poor in upper frequency range. In this paper the problem of the extension of the output frequency to MHz range is studied in the following two view points: First, a tunnel diode VCO is used to increase the output frequency range to several MHz. Second, the linearity between the input voltage and the frequency of the output pulse is accomplished by using negative pulse feedback circuit. From the experimental results, it was followed that the linearity of the proposed converter was about 0.209 percent at the frequency of 3.7MHz.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.36T no.2
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• pp.48-55
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• 1999

To cope actively with the changes of external environments, it is necessary that a robot should have visual feedback control (VFC) using image informations. A VFC system consists of a manipulator and camera(s). For the fixed visual system, when feature value are located at the same line, we have a problem of singular value unable to be controlled by VFC. As a solution, we may define state values of the image Jacobians, then, by making comparisons and evaluations of feature values, select available ones. This method, however, has a demerit increasing numbers of feature values. To solve the problem, moving cameras of VFC system actively, we suggest an algorithm which dose not cause singular value, and prove its availability through simulations.

• Proceedings of the IEEK Conference
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• 2002.06b
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• pp.189-192
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• 2002

In this work, a Voltage-to-Frequency Converter.(VFC) in which the output frequency is proportional to the input voltage is proposed. To obtain temperature stable characteristics the VFC is designed by using two bandgap references. The difference between simulated and calculated values is less than about 5% in output characteristics. In the VFC using BiCMOS the temperature variation of sample output frequencies is less than $\pm$0.5% in the temperature range -$25^{\circ}C$ to 75$^{\circ}C$. And the CMOS VFC has error less than $\pm$0.8% in the temperature range -$25^{\circ}C$ to 75'$^{\circ}C$.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.3
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• pp.105-108
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• 2003

In this work, a Voltage-to-Frequency Converter(VFC) in which the output frequency is proportional to the input voltage is proposed. To obtain the temperature stable characteristics of the VFC circuit is designed by BiCMOS technology. The output frequency range is 24KHz to 65KHz and the difference between simulated and calculated values is less than about 5% for this range of output frequency. The temperature variation of sample output frequencies is less than $\pm$0.5% in the temperature range $-25^{\circ}C$ to 75$^{\circ}C$.

• Journal of Advanced Navigation Technology
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• v.15 no.4
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• pp.616-625
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• 2011

There are two representative geometry rendering methods. One is Geometry Clipmaps, another is ROAM 2.0. We propose an extended Geometry Clipmaps algorithm which does not focus on CPU operation but the GPU for faster and wider visibility area. The extended algorithm presents mesh configuration method of each level by LOD, how to configurate Mesh network between levels, mesh block method for rendering optimization using VFC, and image mapping method to get high resolution up to 1 m.

• The Journal of the Korea Contents Association
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• v.19 no.10
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• pp.607-619
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• 2019

This study used Natural Monument water spiders and their habitats as educational contents, so those students could have a scientific literacy and the beautiful memories of Eundaeri's marshes through developing a virtual fieldwork courses (VFC) and observing the ecology of water spiders. In order to develop the program, the 2015 revised national curriculum and its textbooks were analyzed. In accordance with the STEAM model, we developed teaching-learning materials for 7 classes. Students produced 3D panorama virtual fieldwork courses (PVFC) about water spider by team-based cooperative learning, enabling them to emotionally experience the meaning and value of water spiders. A panel of six education experts verified the validity of the program and found it to be fairly valid at 4.24 (CVI = .88) on the 5-point Likert scale. In order to confirm the suitability of the program, students in the middle school science clubs participated in pilot testing camp. Their average classes satisfaction was 4.24 and students were very satisfied with the usefulness of the program, the fresh learning contents, and the suitability of the convergence education class. This study could contribute to convergence education related to ecology and virtual reality for adolescents.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.31-31
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• 2000

In this paper, Ive design and test the V/F converter for KSR-III INS using commertial INC, VFC110, AD652. The test result shows that performance of AD652 is better than that of VFC110. Through the calibration of V/F converter, we show that the designed V/F converter has a good performance and is usable for KSR-III.

• The Journal of the Acoustical Society of Korea
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• v.14 no.6
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• pp.74-79
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• 1995

This paper proposes the stereo LVFC-Robot which Imitates eyes and arms of man. we derived linear approximation equation between visual space and joint space by minimum square method and then applied it to the proposed stereo LVFC-Robot. As a result of a simulation, its efficency is verified. Compared with the stereo VFC, the stereo LVFC Robot don't need the Image Jacobian and the Robot Jacobian. Thus it is possible to control Robot in real time.

• Journal of Welding and Joining
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• v.16 no.2
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• pp.73-83
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• 1998

This study investigated the relationships between the microstructure and the wear resistance of hardfaced iron/chromium alloys to examine the low stress abrasive wear mechanism. The effects of volume fraction of reinforcing phases(chromium carbide and eutectic phase) were studied. The alloys were deposited once or twice on a mild steel plate using a self-shielding flux cored arc welding process. The low stress abrasion resistance of he alloys against dry sands was measured by the Dry Sand/Ruber Wheel Abrasion Tester (RWAT). The wear resistance of hypoeutectic alloys, below 0.36 volume fraction of chromium-carbide phase (VFC), behaved as Equal Pressure Mode (EPM) for the inverse rule of mixture whereas the wear resistance of hypereutectic alloys, above 0.36 VFC, represented Equal Wear Mode (EWM) for the linear rule of mixture.