• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.281-285
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• 1996

In this paper, I made visual inspection system using Vision Board and it is consist of an illuminator (a fluorescent lamp), image input device(CCD(Charge)Coupled Device) camera), image processing system(Vision Board(FARAMVB-02), image output device(videomonitor, printer), a measuring instrument(TELMN1000). Length measurement by visual inspection system is used 100mm gauge block instead of calculating distance between camera and object, it measured horizontal and vertical length factor from 400mm to 650mm by increasing 50mm. In this place, measured horizontal and vertical length factor made use of length measurement of a injection. A measuring instrument used to compare a measured length of a injection visual inspection system with it. In conclusion, length measurement of a injection compared a measuring instrument withvisual inspecion system using length factor of 100mm guage block. Maximum error of length compared two devices a measuring instrument with visual inspection system is 0.55mm. And operation program is made up Borland C++ 3.1. By changing, it is applied to various uses.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.2
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• pp.23-29
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• 2014

Less power consumption, lower cost, smaller size and more functionality are the increasing demands for consumer electronic devices. The three dimensional(3-D) TSV packaging technology is the potential solution to meet this requirement because it can supply short vertical interconnects and high input/output(I/O) counts. Cu(Copper) has usually been chosen to fill the TSV because of its high conductivity, low cost and good compatibility with the multilayer interconnects process. However, the CTE mismatch and Cu ion drift under thermal stress can raise reliability issues. This study discribe the thermal stress reliability trend for successful implementation of 3-D packaging.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.154-157
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• 2009

High dynamic range image can describe the real world scenes that have a wide range of luminance intensity. To display high dynamic range (HDR) image into conventional displayable devices such as monitors and printers, we proposed the logarithmic based global mapping algorithm that consider the features of image using mapping parameters. Based on characteristics of image, we first modify input luminance values for reproducing perceptually tuned images and then displayable output values are obtained directly. The experimental results show that the proposed algorithm achieves good subjective results while preserving details of image, furthermore proposed algorithm has fast simple and practical structure for implementation.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.19-21
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• 2006

In contrast with DC source, Fell cell has non linear characteristics that has lange voltage fluctuation due to load variation, and slow dynamic characteristics. when the loads are increase, the ripples of input and output voltage, also power densities, of inductor, capacitor, and switching devices, are bulky. This paper presents Interleaved boost converter using Fuel cell stacks, proposed converter has merits to promote power densities without increasing loss. Because each converter has same switching frequency and constant phase difference. In this paper, Interleaved boost converter was design for 1[kW], it's validity was proved by simulation and experiments.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.620-624
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• 1998

Higher operating frequency provides rising output power from modern power electronics devices. Nevertheless, the switch-mode operation results in EMI which is produced due to large di/dt and/or dv/dt. The methods to reduce EMI are the use of classic and expensive input filters or the addition of the active filter into the main circuits. In this paper, by using the randomized PWM the EMI effect can be reduced and implementation of the proposed control scheme into the forward converter can improve the harmonic spectrum as well

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.4
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• pp.513-519
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• 1990

In order to realize an efficient and stable X-band harmonic generator, a 100 MHz frequency multiplier, an impulse generator using SRD(Step Recovery Diode) module, and a narrow-band bandpass waveguide filter have been designed and tested. By properly combining these devices an X-band harmonic generator has been realized. The output power of the harmonic generator was measured to be -1.5 dBm at 9 GHz which is the 90th harmonic of the 100MHz input. The power fluctuation of the harmonic generator due to temperature variation was observed to the about 0.15 dB during 24 hours of 4\ulcorner temperature variation.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.10a
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• pp.225-232
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• 1999

For the study of the seismic-response control, it is necessary to use an experimental system with an earthquake simulator and control devices employing a hydraulic actuator system. However, such system is too expensive to prepare at the university laboratory. In this research, an economical experimental system is developed which has a small-sized earthquake simulator and an AMD using AC servo motors. An accurate mathematical model of the three-degree-of-freedom tests structure with an AMD is developed from the measurement of the input/output relationships of the structure. This paper demonstrates experimentally the efficacy of the frequency domain optimal control algorithm H$_2$in reducing the response of seismically excited building to verify the performance of the experimental system.

• ETRI Journal
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• v.37 no.6
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• pp.1055-1064
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• 2015

We demonstrate a next-generation high-capacity mobile fronthaul based on radio over fiber (RoF) technology, which links between a digital unit and a radio unit supporting two frequency assignments and $2{\times}2$ multiple input, multiple output antennas. To confirm the technical feasibility of a mobile fronthaul, we experimentally investigate its down- and uplink end-to-end performances including the optical and radio frequency (RF) signal path. Frequency-dependent performance deviations, error vector magnitude variations, overall system performance variations caused by optical to electrical conversion, and intermediate frequency to RF conversions are examined. Experimental verifications on multiple LTE uplink signals are performed for the first time. We also demonstrate several commercial mobile Internet services, YouTube video streaming, and file transfers using off-the-shelf mobile devices, through a mobile fronthaul based on RoF.

• Journal of electromagnetic engineering and science
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• v.10 no.4
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• pp.263-269
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• 2010

Multiple input multiple output (MIMO) has been considered one of the key enablers of broadband wireless communications. The indoor environment is known to be favorable to ensure both high rank property and high signal-to-interference/noise ratio (SINR) to fully exploit MIMO spatial multiplexing (SM) gain. In this paper, we describe several practical deployment cases where repeater links (or relay links), such as those present with an indoor distributed antenna system (DAS), can act as keyholes to degenerate the rank property of MIMO communications. In this case, we cannot exploit MIMO SM gain in indoor environment. We propose a novel MIMO communication scheme which uses simple converter in the devices in repeater links to resolve the rank degeneration issue and to ensure MIMO SM gain in highly MIMO-favorable indoor environment. MIMO SM is possible over the indoor DAS with single cable line through use of simple converters, which enables practical deployment in real fields.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.337-338
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• 2013

Combination the several type of single phase power conversion utilized simply topology are proposed in this paper. Totally four kind of converter are investigated, they are Boost AC/AC Converter, Buck AC/AC Converter, Boost AC/DC Converter, and Buck DC/AC Converter. Two types action mode are presented to determine the functional of circuit. First is AC chopper action mode, representation of the AC/AC converter. AC chopper action mode offered the sinusoidal current waveform, better power factor, faster dynamics, and smaller input/output filter. They present high robustness, offer safe commutation and have high efficiency. The second is full bridge action mode, determined the transformation AC to DC power and otherwise. Four switching devices and one magnetic contactor will establish the mode operation of circuit and manage the flow of power proceed in proper. The correction and advance of the kind of converter are verified by simulation.