• Journal of the Korean Ceramic Society
• /
• v.40 no.11
• /
• pp.1090-1095
• /
• 2003

In this paper, the modeling and design of high-Q multilayer passives and multilayer diplexer for GSM/DCS applications designed and fabricated using these passives have been investigated.. To miniaturize the system, configurations of inductor and capacitor have involved a square spiral structure and a vertically-interdigitated capacitor similar to 3D interdigital structure, respectively. Multilayer diplexers for GSM/DCS applications were designed and fabricated to apply high-Q multilayer passives to practical systems, which were designed by the proposed structural and equivalent circuit model. LPF for GSM band had the passband insertion loss of less than 0.55 dB, the return loss of more than 12 dB, and the isolation level of more than 26 dB by locating attenuation pole at 1800 MHz. HPF for DCS band had the passband insertion loss of less than 0.82 dB, the return loss of more than 11 dB, and the isolation level of more than 38 dB by locating attenuation pole at 930 MHz.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.54 no.4
• /
• pp.16-21
• /
• 2017

In this paper, a Small-sized and planer resonator design of Magnetic Resonance - Wireless Power Transfer(MR-WPT) were proposed for practical applications of mobile devices, such as a laptop, a smart-phone and a tablet pc. The proposed MR-WPT system were based on four coil MR-WPT and designed as a transmitter part (Tx) and a receiver part (Rx) both are the same shape with the same loop and resonator. There are four different spiral coil type of resonators with variable of line length, width, gap and turns in $50mm{\times}50mm$ size. The both of top and bottom side of substrate(acrylic; ${\varepsilon}_r=2.56$, tan ${\delta}=0.008$) ere used to generate high inductance and capacitance in limited small volume. Loops were designed on the same plane of resonator to reduce their volume, and there are three different size. The proposed MR-WPT system were fabricated with two acrylic substrate plane of Tx and Rx each, the Rx and Tx loops and resonators were fabricated of copper sheets. There are 12 combinations of 3 loops and 4 resonators, each combination were measured to calculate transfer efficiency and resonance frequency in transfer distance from 1cm to 5cm. The measured results, the highest transfer efficiency was about 70%, and average transfer efficiency was 40%, on the resonance frequency was about 6.78 MHz, which is standard band by A4WP. We proposed small-sized and planer resonator of MR-WPT and showed possibility of mobile applications for small devices.

• The KSFM Journal of Fluid Machinery
• /
• v.17 no.5
• /
• pp.43-53
• /
• 2014

This paper presents a the study on air curtain system of top and bottom bi-directional jet air discharge for blocking the spread of smoke in case of tunnel fire. The five kinds different air curtains of A, B, C, D, and E of models for various performance tested after manufactured. A results of the various performance test obtained the best efficiency from E model air curtain. And optimize the injection angle of the air curtain nozzle through the three-dimensional computational fluid dynamics (CFD) analysis and analyzed the effects of external pressure of tunnel. and also single factor design have been applied. At present, our attention is focused on the velocity distribution(flow width and flow position) of 1.5m on the ground in tunnel. Also, analyzed the influence of draft in the tunnel. Detailed effects of discharge angle of air curtain and velocity at nozzle exit are discussed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.23 no.3
• /
• pp.361-366
• /
• 2012

This paper proposes a low power capacitor cross-coupled 5.2 GHz band low noise amplifier(LNA) using the current-reused topology with the TSMC 0.18 ${\mu}m$ CMOS process. The proposed 5.2 GHz band LNA uses a capacitor cross-coupled $g_m$-boosting method for reducing current flow of circuit and a current-reused topology to decrease total power dissipation. The parallel LC networks are used to reduce size of spiral inductors. The simulation results show high gain of 17.4 dB and noise figure(NF) of 2.7 dB for 5.2 GHz.

• Journal of The Korean Association of Information Education
• /
• v.18 no.4
• /
• pp.585-594
• /
• 2014

In terms of development for CMC computer science curriculum was started from 2006 year, and it was confirmed at 2013 year and adapting through 1 to 8 grade. CMC is focused on the "Develop computer fluency, not just computer literacy", "Develop thinking process skills, not just content mastery", and "Highlight the interconnectedness of knowledge, not just address a topic/subject in isolation" as a base of the curriculum. CMC have selected core factors which are Thinking process skills, Computer literacy integrated with fundamental concepts and thinking skills, Thematic integration, Spiral curriculum, and Scalability. Once CMC have been developed as a common computer curriculum by India government, both of computer training course and textbook development were conducted by government. In addition, they are trying to enforce the computer education. It suggests to Korea some significant points which were the necessity of Computer education as an independent subject and the requirement of Software education and Computational thinking as an educational content.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.15 no.7
• /
• pp.713-721
• /
• 2004

This paper presents a high Performance LNA based on InGaP/GaAs HBT for 5.4㎓ WAM band applications. During the past days, InGaP/GaAs HBT has been being used for mainly high power amplifiers, but InCaP/GaAs is recognized as a suitable device for RF single chip. At this point, the research about a high performance LNA based on InGaP/GaAs HBT must be preceded, and in this paper, a excellent linearity and noise characteristics LNA based on InGaP/GaAs HBT is desisted and fabricated. The LNA is integrated in new of 0.9${\times}$0.9$\textrm{mm}^2$ single chip with high Q spiral inductors and MIM capacitors. The proposed LNA is biased at current point for optimum noise figure and gain characteristics, futhermore, excellent linearity is achieved. The proposed LNA shows 13㏈ gain, 2.1㏈ noise figure, and excellent linearity in terms of IIP3 of 5.5㏈m.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.36 no.6
• /
• pp.591-598
• /
• 2012

In this study, the cutting characteristics of bulk metallic glass (BMG) cut using a computer numerically controlled (CNC) lathe were investigated for different insert tool materials and cutting speeds. The surface roughness, chip morphology, cutting forces, and tool wear during turning of $Zr_{50}Cu_{40}Al_{10}$ BMG alloy were examined. Four kinds of tool materials were used to cut an 8-mm-diameter BMG. The examination of the surface roughnesses of the BMG specimens machined at each cutting speed showed that the surface roughness became better as the cutting speed increased, and the tool materials also influenced the surface roughness. The chip morphology investigations showed that the unoxidized BMG chips had serrated curled chips with adiabatic shear bands, while the oxidized chips exhibited local melting and tangling rather than the usual spiral-shaped chips. The cutting force induced during machining of the Zr-based BMG was the largest for the TiN-WC tool, followed by the polycrystalline diamond (PCD) tool. The cermet tool exerted the smallest cutting force.

• Development and Reproduction
• /
• v.4 no.1
• /
• pp.1-6
• /
• 2000

Ultrastructure of the zona radiata the micropyle and fertilization process in the rainbow trout (Oncorhynchus mykiss) were examined by light, scanning and transmission microscopes . The egg micropyle of rainbow trout consists of a funnel-shaped vestibule and a tapered canal transversing the zona radiata. The micropyle showed the type with a flat pit leading into a long canal and the micropylar wall showed the clockwise spiral structure. There were a great number of microvilli secreting adhesive materials having trapping function attracting the spermatozoa in the vicinity of micropyle. It was apparent that ridges extended between the projections. In the initial stages of penetration, the spermatozoon still within the micropylar canal attached perpendicularly at its apical tip to the egg surface, then the sperm head was rapidly engulfed by the folded egg surface with its many microvilli. The spermatozoon disappeared from the outer surface of the egg before the fertilization cone completely retracted 250 seconds after insemination. No interconnecting ridges was present in the egg surface. In short, the block to polyspermy to permit entry of a single sperm is considered to be mechanical by the morphological design of the micropyle and fertilization cone.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.51 no.3
• /
• pp.55-60
• /
• 2014

For an high speed communication, a 40GHz VCO was implemented using a 0.11um standard CMOS technology. The mm-wave VCO was designed by a LC type using a spiral inductor, and a simplified architecture with buffers and a smart biasing technique were used to get a high performance. The frequency range of the proposed VCO is 34~40GHz which is suitable for mm-Wave communication system. It has an output power of -16dBm and 16% tuning range. And the phase noise is -100.33dBc/Hz at 1MHz offset at 38GHz fundamental frequency. The total power consumption of VCO including PADs is 16.8mW with 1.2V supply voltage. The VCO achieves the FOMT of -183.8dBc/Hz which is better than previous VOCs.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.16 no.12 s.103
• /
• pp.1186-1193
• /
• 2005

In this paper, a new 3 dB branch line hybrid using asymmetric spiral-shaped defected ground structure(DGS) microstrip is proposed. The proposed branch line hybrid suppresses the 2nd and the 3rd harmonic component effectively. Also a DGS $\lambda$/4 bias line that can suppress high frequency harmonics as well as low frequency intermodulation component is proposed. With the harmonic termination tuner using the proposed hybrid and the harmonic blocking bias line, the 2nd and the 3rd harmonic components of the fabricated amplifier that operated in IMT-2000 basestation transmitting band were suppressed up 25 dB and 27 dB, respectively. The proposed harmonic load-pull setup of amplifier is more easily accomplished with proposed circuits than the previous.