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- 저자 : Joungho Kim (검색결과 122 건)
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Jonghoon Kim,Hongseok Kim,In-Myoung Kim,Young-Il Kim,Seungyoung Ahn,Jiseong Kim,Joungho Kim 한국전자파학회JEES 2011 Journal of Electromagnetic Engineering and Science Vol.11 No.3
In this paper, we implemented and analyzed a wireless power transfer (WPT) system with a CSPR topology. CSPR refers to constant current source, series resonance circuit topology of a transmitting coil, parallel resonance circuit topology of a receiving coil, and pure resistive loading. The transmitting coil is coupled by a magnetic field to the receiving coil without wire. Although the electromotive force (emf) is small (about 4.5V), the voltage on load resistor is 148V, because a parallel resonance scheme was adopted for the receiving coil. The implemented WPT system is designed to be able to transfer up to 1 ㎾ power and can operate a LED TV. Before the implementation, the EMF reduction mechanism based on the use of ferrite and a metal shield box was confirmed by an EM simulation and we found that the EMF can be suppressed dramatically by using this shield. The operating frequency of the implemented WPT system is 30.7㎑ and the air gap between two coils is 150㎜. The power transferred to the load resistor is 147W and the real power transfer efficiency is 66.4 %.
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High-Resolution Synthesized Magnetic Field Focusing for RF Barcode Applications
Kim, Min-Woo,Kim, Ji H.,Cho, Yeonje,Kim, Minsik,Choi, Bo H.,Lee, Kwyro,Kim, Joungho,Cho, Gyu-Hyeong,Rim, Chun T. Institute of Electrical and Electronics Engineers 2018 IEEE transactions on industrial electronics Vol.65 No.1
<P>A prototype of a high-resolution synthesized magnetic field focusing (SMF) system for a possible application to radio frequency (RF) barcodes is proposed in this paper. It was recently found that coordinated control of array coil currents makes it possible to focus magnetic field, which is requisite for medical imaging, wireless power, and RF identification. Different from conventional phased array RF antennas, SMF is independent of frequency, which is quite promising for various applications. In this paper, an array of rectangular air coils is proposed, and various implementation issues, such as accurate control of coil currents and compact RF barcode design, are newly suggested. A prototype of an SMF system composed of a transmitter (Tx), an RF barcode, and a receiver (Rx) was implemented at below 1 MHz operating frequency. The Tx includes modularized control drivers, full-bridge switching converters, and 16 arrayed air coils, where the RF barcodes proposed in this paper include a self-resonating circuit at 20 mm × 20 mm and a tunable resonating circuit at 15 mm × 15 mm. In this way, a 5 mm resolution at a distance of 20 mm was achieved for the Tx arrayed air coils with spacing of 5 mm, which is about four times sharper magnetic field focusing compared to a nonfocusing conventional coil. Furthermore, the proposed SMF system allows the designed 5-bit RF barcode array to be fully distinguishable at a 15 mm distance.</P>
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Kim, Jonghoon J.,Heegon Kim,Jung, Daniel H.,Sumin Choi,Jaemin Lim,Youngwoo Kim,Junyong Park,Hyesoo Kim,Dongho Ha,Bae, Michael,Joungho Kim IEEE 2017 IEEE transactions on electromagnetic compatibility Vol.59 No.4
<P>As the data rate of Low Power Double Data Rate 4 (LPDDR4) memory now exceeds 3.2 Gb/s, it is becoming more difficult to meet the target specifications. While testing has become of utmost importance, it is not viable to have a direct access to the signal pins in a package on package configuration due to the densely located array of solder balls; instead, a test interposer with an excellent electrical performance needs to be adopted to provide test access. In this paper, we first propose a novel test interposer scheme for testing LPDDR4 memory packages. For accurate testing without significant influence on the intrinsic signal path, the proposed test interposer is designed considering a number of signal integrity issues such as intersymbol interference, jitter, impedance matching, and crosstalk. Furthermore, by adopting silicone rubber sheet in place of soldering, the proposed test interposer enhances reusability of the packages with a fast setup time. Moreover, a reconstruction method is proposed that can reconstruct the voltage at application processor using the waveform captured on the test interposer, instead of probing at the ball gray array directly. Through a series of simulations and measurements, we experimentally verified the proposed test interposer. The proposed test interposer scheme can be widely adopted for testing of high-performance packages with its high accuracy and practicality.</P>
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Kim, Jonghoon J.,Changhyun Cho,Bumhee Bae,Sukjin Kim,Sunkyu Kong,Heegon Kim,Jung, Daniel H.,Jiseong Kim,Joungho Kim IEEE 2014 IEEE transactions on components, packaging, and ma Vol.4 No.12
<P>A simultaneous switching current (SSC) drawn by an integrated circuit (IC) creates simultaneous switching noise on power nets, which in turn causes jitters in the I/O signals and reduces the maximum clock frequency. For a thorough analysis of high-speed ICs, there is a dire need to measure currents at specific power pins of the ICs. In this paper, a novel magnetically coupled embedded current probing structure is proposed for measuring the SSC on the chip level resulting from the logical activity of the I/O buffers. SSCs are found by capturing the magnetic flux induced by the SSC of interest, with the proposed embedded current probing structure using magnetic coupling, and then reconstructing the original current waveform using the transfer impedance profile. Through a series of measurements with test vehicles fabricated on the chip level, we experimentally verified the proposed probing structures in the time and frequency domains and proved that they can effectively measure the SSC. Finally, future directions for improvements are discussed at the end of this paper.</P>
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Through-Silicon Via Capacitance–Voltage Hysteresis Modeling for 2.5-D and 3-D IC
Kim, Dong-Hyun,Kim, Youngwoo,Cho, Jonghyun,Bae, Bumhee,Park, Junyong,Lee, Hyunsuk,Lim, Jaemin,Kim, Jonghoon J.,Piersanti, Stefano,de Paulis, Francesco,Orlandi, Antonio,Kim, Joungho IEEE 2017 IEEE transactions on components, packaging, and ma Vol.7 No.6
<P>We propose, for the first time, an explicit semiconductor physics-based through-silicon via (TSV) capacitance-voltage (CV) model. The effect of TSV CV hysteresis is demonstrated in the model, and the TSV capacitance is modeled with respect to dc bias voltage and the dimension of the TSV. The proposed model is verified by comparison to the measurement results. The effect of hysteresis in the model correlates well with the measurement results. This model can be utilized in a circuit level simulation to expand the possible application of the model to, but not limited to, hierarchical power distribution network impedance analysis, RC delay analysis, input-output power consumption analysis, and crosstalk and eye diagram simulation in any 3-D-IC systems using TSVs.</P>
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Kim, Youngwoo,Cho, Jonghyun,Kim, Jonghoon J.,Cho, Kyungjun,Kim, Subin,Sitaraman, Srikrishna,Sundaram, Venky,Raj, Pulugurtha Markondeya,Tummala, Rao R.,Kim, Joungho [Institute of Electrical and Electronics Engineers 2017 IEEE transactions on electromagnetic compatibility Vol.59 No.3
<P>In this paper, we propose glass interposer electromagnetic bandgap (EBG) structure to efficiently suppress power/ground noise coupling. We designed, fabricated, measured, and analyzed a glass interposer EBG structure for the first time. Glass interposer EBG structure test vehicles were fabricated using a thin-glass substrate, low-loss polymer layers, and periodic metal patches with through glass vias (TGVs) in glass interposer power distribution network. Using the dispersion characteristics, we thoroughly analyzed and derived f(L) and f(U) of the glass interposer EBG structure. We experimentally verified that the proposed glass interposer EBG structure achieved power/ground noise suppression (below -40 dB) between f(L) of 5.8 GHz and f(U) of 9.6 GHz. Derived f(L) and f(U) based on dispersion analysis, full three-dimensional electromagnetic (3-D-EM) simulation and measurement achieved good correlation. In the glass interposer EBG structure, tapered structure of the TGV and thickness of the low-loss polymer used for metal-layers lamination affected the noise suppression bandgap significantly. The effectiveness of the proposed glass interposer EBG structure on suppression of the power/ground noise propagation and coupling to high-speed TGV channel was verified with 3-D-EM simulation. As a result, the proposed glass interposer EBG structure successfully and efficiently suppressed the power/ground noise propagation and improved eye-diagram of the high-speed TGV channel.</P>
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Kim, Hong Kwan,Park, Min Soo,Choi, Yong Soo,Kim, Kwhanmien,Shim, Young Mog,Han, Joungho,Kim, Byoung Joon,Kim, Jhingook Elsevier 2007 Journal of thoracic and cardiovascular surgery Vol.134 No.3
<P><B>Objectives</B></P><P>The objectives of this study were to compare the clinical features and the outcomes after thymectomy between patients with and without thymoma and to evaluate the influence of thymectomy on the subsequent clinical course of myasthenia gravis.</P><P><B>Methods</B></P><P>Between 1995 and 2003, 64 consecutive patients underwent thymectomy, and of these, 60 patients were followed up for at least 12 months postoperatively. The study population was divided into 2 groups based on the presence of thymoma. We performed a retrospective analysis to compare the neurologic outcomes of thymectomy between patients with thymomatous myasthenia gravis and those with nonthymomatous myasthenia gravis.</P><P><B>Results</B></P><P>Twenty-four patients had a thymoma. No significant differences were observed between the 2 groups regarding the preoperative severity of myasthenia gravis. There was no significant difference in the follow-up duration between the 2 groups. There was no significant difference in the overall remission rate between the 2 groups (<I>P</I> = .064). The mean time required to reach a remission was 10.6 months and 23.5 months in the thymoma and nonthymoma groups, respectively. The mean duration of remission was 43.1 months and 30.8 months in the thymoma and nonthymoma groups, respectively. In the early phase of follow-up, more patients reached remission in the thymoma group than those in the nonthymoma group (<I>P</I> = .040).</P><P><B>Conclusions</B></P><P>Neurologic outcomes of the thymoma group were no worse than those of the nonthymoma group. It is expected that earlier thymectomy is likely to result in a better prognosis by shortening the disease period, even for patients with nonthymomatous myasthenia gravis.</P>
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Sukjin Kim,Jung, Daniel H.,Kim, Jonghoon J.,Bumhee Bae,Sunkyu Kong,Seungyoung Ahn,Jonghoon Kim,Joungho Kim IEEE 2015 IEEE transactions on components, packaging, and ma Vol.5 No.7
<P>As technology develops, the number of chips increases while the thickness of mobile products continuously decreases, which leads to the need for high-density packaging techniques with high numbers of power and signal lines. By applying wireless power transfer technology at the printed circuit board (PCB) and package levels, the number of power pins can be greatly reduced to produce more space for signal pins and other components in the system. For the first time, in this paper, we propose and demonstrate a high-efficiency PCB- and package-level wireless power transfer interconnection scheme. We enhance the efficiency by applying magnetic field resonance coupling using a matching capacitor. The proposed scheme can replace a high number of power interconnections with rectangular spiral coils to wirelessly transfer power from the source to the receiver at the PCB and package levels. The equivalent circuit model is suggested with analytic equations, which is then analyzed to optimize the test vehicle design. For the experimental verification of the suggested model, the $Z$ -parameter results obtained from the model-based equation and measurement of the designed and fabricated test vehicles are compared at up to 1 GHz. The power transfer efficiency from the source coil to the receiver coil in this scheme is able to reach 85.6%. Finally, we designed and fabricated a CMOS full-bridge rectifier and mounted it on the receiver board to convert the transferred voltage from ac voltage to dc voltage. A measured dc voltage of 2.0 V is sufficient to operate the circuit, which generally consists of 1.5 V devices.</P>
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Coil Design and Shielding Methods for a Magnetic Resonant Wireless Power Transfer System
Jiseong Kim,Jonghoon Kim,Sunkyu Kong,Hongseok Kim,In-Soo Suh,Nam Pyo Suh,Dong-Ho Cho,Joungho Kim,Seungyoung Ahn IEEE 2013 Proceedings of the IEEE Vol.101 No.6
<P>In this paper, we introduce the basic principles of wireless power transfer using magnetic field resonance and describe techniques for the design of a resonant magnetic coil, the formation of a magnetic field distribution, and electromagnetic field (EMF) noise suppression methods. The experimental results of wireless power transfer systems in consumer electronics applications are discussed in terms of issues related to their efficiency and EMF noise. Furthermore, we present a passive shielding method and a magnetic field cancellation method using a reactive resonant current loop and the utilization of these methods in an online electric vehicle (OLEV) system, in which an OLEV green transportation bus system absorbs wireless power from power cables underneath the road surface with only a minimal battery capacity.</P>
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A Wideband On-Interposer Passive Equalizer Design for Chip-to-Chip 30-Gb/s Serial Data Transmission
Heegon Kim,Jonghyun Cho,Joohee Kim,Sumin Choi,Kiyeong Kim,Junho Lee,Kunwoo Park,Pak, Jun So,Joungho Kim IEEE 2015 IEEE transactions on components, packaging, and ma Vol.5 No.1
<P>In this paper, a novel on-interposer passive equalizer is proposed for chip-to-chip high-speed data transmission on the silicon-based on-interposer channel. The proposed equalizer uses the parasitic resistance and inductance of the on-interposer shunt metal lines to produce the high-pass filter. This filter enables the proposed equalizer to exhibit wideband channel equalization and low power-consumption. Based on the equivalent-circuit model of the proposed on-interposer passive equalizer, the physical dimensions of the equalizer are optimized for 30-Gb/s serial data transmission. The performance of the proposed equalizer with the optimized dimensions was successfully demonstrated by both frequency- and time-domain measurements at data rates of up to 30 Gb/s. In addition, a compact on-interposer passive equalizer was designed for the wide I/O interposer using the same mechanism. The improved quality of serial data transmission in the equalized wide I/O on-interposer channel was successfully verified by simulations at data rates of up to 10 Gb/s.</P>
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