• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.52-57
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• 2000

STD11 is one of difficult-to-cut materials and its cutting characteristic data is not built enough. A bad cutting condition of it leads to low productivity of die and mould, so it is necessary to evaluate the machining characteristics of STD11. In this paper, the relations of the geometry of ball-end mill and mechanics of machining with it are studied. The helix angle of ball-end mill varies according to a location of elemental cutting edge in the cutting process are difficult to calculate accurately. To calculate instantaneous cutting forces, it is supposed that the tangential, radial and axial cutting force coefficients are functions of elemental cutting edge location. Elemental cutting forces in the x,y and z direction are calculated by coordinate transformation. The total cutting forces are calculated by integrating the elemental cutting forces of engaged cutting edge elements. This model is verified by slot and side cutting experiments of STD11 workpiece which was heat-treated to HRC45.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.565-566
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• 2006

High speed machining experiment on the inclined surfaces of hardened mold steel(STAVAX at hardness HRC 53) is carried out using the long-neck type ball endmill. Surface texture and roughness are compared fur various cutting conditions. Tool overhang length greatly affects the roughness of machined surface. It is found that, fur this type of long-neck endmill, the chip load should be carefully selected by reducing either the axial depth of cut or feedrate to avoid tool vibration. Feedrate adjustment is more appropriate method in terms of tool wear.

• International Journal of Precision Engineering and Manufacturing
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• v.4 no.4
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• pp.13-18
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• 2003

This paper presents the in-process compensation to control cutter ronout and to improve the machined surface quality. Cutter ronout compensation system consists of the micro-positioning servo system with piezoelectric actuator which is embeded in the sliding table to manipulate radial depth of cut in real-time. Cutting force feedback control was proposed in the angle domain based upon repetitive learning control strategy to eliminate chip load variation in end milling process. Micro-positioning control due to adaptive actuation force response improves the machined surface quality by cutter ronout compensation.

• Journal of Welding and Joining
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• v.20 no.5
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• pp.72-77
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• 2002

Flip-chip interconnection that uses solder bump is an essential technology to improve the performance of microelectronics which require higher working speed, higher density, and smaller size. In this paper, the shear strength of Cr/Cr-Cu/Cu UBM structure of the high-melting solder b01p and that of low-melting solder bump after aging is evaluated. Observe intermetallic compound and bump joint condition at the interface between solder and UBM by SEM and TEM. And analyze the shear load concentrated to bump applying finite element analysis. As a result of experiment, the maximum shear strength of Sn-97wt%Pb which was treated 900 hrs aging has been decreased as 25% and Sn-37wt%Pb sample has been decreased as 20%. By the aging process, the growth of $Cu_6Sn_5$ and $Cu_3Sn$ is ascertained. And the tendency of crack path movement that is interior of a solder to intermetallic compound interface is found.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.6
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• pp.789-796
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• 2014

A CMOS photo detection bias quenching circuit is developed to be used with single photon avalanche photodiodes (SPADs) operating in Geiger mode for the detection of weak optical signals. The proposed bias quenching circuits for the performance improvement reduce the circuit size as well as improve the performance of the quenching operation. They are fabricated in a $0.18-{\mu}m$ standard CMOS technology to verify the effectiveness of this technique with the chip area of only $300{\mu}m^2$, which is about 60 % of the previous reported circuit. Two types of proposed circuits with resistive and capacitive load demonstrated improved performance of reduced quenching time. With a commercial APD by HAMAMATSU, the dead time can be adjusted as small as 50 ns.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.12
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• pp.2228-2233
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• 2008

This research paper aims to establish a test process of the AFE SiP chip. It measured the sensitivity, current consumption and power consumption both on the evaluation socket board and Catalyst load board. As a result, the sensitivity became deteriorated with an average of 0.2[dBm] at the channel 62 only, the current consumption increased to an average of 0.57[mA] and the power consumption increased to an average of 1.76[mW], But all characteristics incomes the tolerance of the measurement, it also keeps almost the same level. Therefore this design of the test process improved a valid design.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.707-710
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• 2005

This paper presents a 3kW grid-connection photovoltaic power generation system and its topology. Photovoltaic system must provide the sinusoidal output voltage wave for unity power factor High frequency switching converters are becoming more popular because of several benefits which are essential in power conversion system. This paper introduces a high speed digital controller using TMS320F2812 DSP chip which can be used for high frequency switching converters. The experimental results of the proposed PWM Inverter demonstrates its high performance with unity input power factor having very low distorsion in input current waveforms and good dynamic characteristics at full load.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.182-184
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• 2005

The human beings have Increased concern about Energy saving and alternative energy. The power demand has increased the growth of industry and the improvement of life We have to explore alternate energy sources and utilize effectively domestic resources. The lighting equipments developed Energy saving by using an electric ballast. The load installation should be promoted to rational power management, according to the network, intelligent, and high-function. Therefore, this paper has studied the method of energy saving and consulting.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.838-840
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• 1998

The power demand has increased the groth of industry and improvement of life. Otherwise the power supply is more difficult. because of regional egoism, reinforcement for environment, and investment of money. The load installation should be promoted to rational power management, according to the network, inteligent, and high-function. Therefore, this paper is made a study for the method of energy saving and for energy saving of medium-small type small type-below 500kW medium type-between $500{\sim}1.000kW$.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.7
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• pp.594-601
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• 2000

EIA-709.1 Control Network Protocol is the basic protocol of LonWorks systems that is emerg-ing as a fieldbus device. In this paper the protocol is implemented by using VHDL with FPGA and C program on an Intel 8051 processor. The protocol from the physical layer to the network layer of EIA-709.1 is im-plemented in a hardware level,. So it decreases the load of the CPU for implementing the protocol. We verify the commercial feasibility of the hardware through the communication test with Neuron Chip. based on EIA-709.1 protocol which is used in industrial fields. The developed protocol based on FPGA becomes one of IP can be applicable to various industrial field because it is implemented by VHDL.