• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.6
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• pp.37-43
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• 2013

In this paper, an UWB (Ultra Wide Band) band-pass filter with open stubs using SIR (Stepped Impedance Resonator) structure is presented. The proposed band pass filter (BPF) has SIR structure instead of open stubs for UWB application with low insertion loss. The bandwidth of the proposed BPF is 103 % at the center frequency of 5.8GHz and the insertion and return losses are 0.17dB and 13.1dB, respectively. Also, the entire size of the proposed band-pass filter is $21.6{\times}17.8mm^2$.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.7
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• pp.1-6
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• 2020

Micro-structure components applied to various disciplines are steadily demanded with lighter weight and better quality. This is because that ultra thin-wall injection molding has been paid attention with a lot of benefits such as cost reduction, shorter process period, and so forth. However, this technology is complicate and difficult to obtain high quality of products compared with conventional injection molding due to warpage caused by uneven shrinkage and molecular orientation. Since warpage of products directly affects product quality and overall performance of devices, it is essential to predict deformation behavior to achieve high precision of molded products. Therefore, this study aims to find out adequate thin-wall mold design for FPC connector housing by employing Moldflow simulation before application. In addition, experimental research is performed by using a fabricated mold structure based on simulated results to prove accuracy and reliability of the suggested simulation for warpage analysis.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.11
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• pp.36-40
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• 2013

A novel design method of ultra wideband bandpass filter using CRLH transmission line with Dumbell type DGS is presented in this paper. Defected Ground Structure and microstrip interdigital capacitor are used to design the ultra wideband (UWB) filter. CRLH transmission line has composite characteristics of low pass and high pass filter. As control of cutoff frequency of low pass and high pass response on CRLH transmission line, we can get characteristic of UWB filter. We designed and simulated for CRLH transmission lines with one, two, four, and eight cells. A UWB filter using four cells CRLH is designed and fabricated to verify the results. The characteristics of designed filter have center frequency of 5GHz and relative bandwidth of 88%.

• Journal of the Korea institute for structural maintenance and inspection
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• v.3 no.1
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• pp.129-136
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• 1999

In this paper, the new non-destructive equation will be proposed and evaluated in comparison to the other foreign's non-destructive equation. Through the comparisons cores strength of mock structure with compressive strength obtained from new non-destructive equation ; rebound hammer, ultra-sonic pulse velocity and combined method, it will be analyzed about application of non-destructive equation. The results are following. The new non-destructive equations follow ; (1) $F_c=9.5R{\cdot}N+62.5$ (2) $F_c=243Vp-739$ (3) $F_c=8.1R_o+205.3V_p-802$ where, $F_c$ : Compressive Strength, $R_o$ : Rebound Number. $V_p$ : Ultra-Sonic Pulse Velocity Trough the result of mock structure test, the combined method is superior to rebound method and ultra-sonic pulse velocity method in the estimation of concrete strength. In order to apply the non-destructive equation of concrete strength to the structures, it is necessary that we should be made process study on the non-destructive equation for estimation of concrete strength in the range, time and strength of application under long-term.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.307-308
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• 2006

In this paper, we propose an ultra wideband pass filter of ring type with embedded stripline stub. The fractional bandwidth was 98 % at the center frequency of 8 GHz and insertion loss was below 1 dB in passband. Two kinds of dielectric materials with the permittivity of 7.8 and 40, respectively were adopted in evaluating the suggested filter structure. As the permittivity of material became larger, the size of filter smaller as expected without any sacrifice in filter performance. In summary, the suggested filter structure has smaller size due to the embedded stripline stub and can be minimized by adopting dielectric material with higher permittivity again.

• Structural Engineering and Mechanics
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• v.88 no.3
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• pp.221-238
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• 2023

This paper developed and examined a novel passive vibration isolator (i.e., "X-inerter") motivated by combining a bio-inspired structure and a rack-pinion inerter. The bio-inspired structure provided nonlinear stiffness and damping owing to its geometric nonlinearity. In addition, the behavior was further enhanced by a gear inerter that produced a special nonlinear inertia effect; thus, an X-inerter was developed. As a result, the X-inerter can achieve both high-static-low-dynamic stiffness (HSLDS) and quasi-zero stiffness (QZS), obtaining ultra-low frequency isolation. Furthermore, the installed inerter can produce a coupled nonlinear inertia and damping effect, leading to an anti-resonance frequency near the resonance, wide isolation region, and low resonance peak. Both static and dynamic analyses of the proposed isolator were conducted and the structural parameters' influence was comprehensively investigated. The X-inerter was proven to be comparatively more stable in the ultra-low frequency than the benchmarking QZS isolator due to the nonlinear damping and inertia properties. Moreover, the inertia effect could suppress the bio-inspired structure's super- and sub-harmonic resonance. Therefore, the X-inerter isolator generally possesses desirable nonlinear stiffness, nonlinear damping, and unique nonlinear inertia, designed to achieve the ultra-low natural frequency, the anti-resonance property, and a wide isolation region with a low resonance peak.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.48-53
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• 1995

Recently, work of construction industry is not enough to do in tamping because of a lack of expert, advanced-age of worker, increase of structure of high-dengity arrangment and machanization of concrete pumping method Accordingly it is required for high-qualuily concrete with excellent flowability, Self-placeability and regregation registance. In this point of view, this study is investigated for requiremend properties of ultar-flow concrete using dimestic material as for development of Ultra-Flow concrete in the side of material

• Proceedings of the IEEK Conference
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• 2000.11b
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• pp.41-44
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• 2000

Ultra large scale integrated circuit(ULSI) & complementary metal oxide semiconductor(CMOS) circuits require gate electrode materials such as meta] silicides, titanium-silicide for gate oxides. Many previous authors have researched the improvements sub-micron gate oxide quality. However, little has been done on the electrical quality and reliability of ultra thin gates. In this research, we recommend novel shallow trench isolation structure and two step TiSi$_{2}$ formation for sub 0.1${\mu}{\textrm}{m}$ gate oxide.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.12
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• pp.30-36
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• 2009

Various types of ultra-wideband components with 10's of GHz bandwidth have been developed utilizing a uniplanar ultra-wideband balun, which is a simple microstrip-to-coplanar stripline (CPS) transition structure with the operating frequency range from near DC to over 40 GHz. Developed ultra-wideband components include antennas, mixers, doublers, and detectors in a carrier type and in a surface mountable type. One of surface mountable components, for example, single balanced doubler has output frequency 8 ~ 28 GHz. These high-Performance, low-cost ultra-wideband components may replace expensive conventional components, and also can be used to develop new multi-GHz OWE application areas.

• Proceedings of the KIEE Conference
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• 2001.11a
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• pp.131-133
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• 2001

Dendrimers represent a new class of synthetic macromolecules characterized by a regularly branched treelike structure. Peculiar features of the dendritic geometry are the large number of end groups as well as the shape persistence in higher generations, approaching spherical geometry. And one of the most peculiar characteristics of dendritic macromolecules is their controlled molecular structure and orientation, which means that they have a practical application in achieving a highly organized molecular arrangement. We attempted to fabricate a G4-48PyA dendrimer LB films containing 48 pyridinealdoxime functional end group that could form a complex structure with metal ions. Also, we investigated the surface activity of dendrimer films at air-water interface. And we have studied the electrical properties of the ultra-thin dendrimer LB films. The electrical properties of the ultra-thin dendrimer LB films were investigated by studying the current-voltage characteristics of metal/dendrimer LB films/metal (MIM) structure. And rectifying behavior of the devices was occurred in applied field.