• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1511_1512
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• 2009

This paper presents a polarization switching antenna integrated with silicon RF MEMS SPDT switches in the form of a package. A low-loss quartz substrate made of SoQ (silicon-on-quartz) bonding is used as a dielectric material of the patch antenna, as well as a packaging lid substrate of RF MEMS switches. The packaging/antenna substrate is bonded with the bottom substrate including feeding lines and RF MEMS switches by BCB adhesive bonding, and RF energy is transmitted from signal lines to antenna by slot coupling. Through this approach, fabrication complexity and degradation of RF performances of the antenna due to the parasitic effects, which are all caused from the packaging methods, can be reduced. This structure is expected to be used as a platform for reconfigurable antennas with RF MEMS tunable components. A linear polarization switching antenna operating at 19 GHz is manufactured based on the proposed method, and the fabrication process is carefully described. The s-parameters of the fabricated antenna at each state are measured to evaluate the antenna performance.

• Transactions of the Korean Society of Automotive Engineers
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• v.25 no.1
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• pp.35-41
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• 2017

The use of engineering plastics in automotive components is increasing with the trend towards improving the car strength and reducing weight. Among the different choices of materials, engineering plastic emerged as the necessary material for achieving lower costs, reduced weight and improved production efficiency. To produce the automotive parts, it is important to predict defect and validation of injection molding prior to design. Injection molding analysis and structural analysis are widely applied as a part of the design process when developing automotive parts. Injection molding analysis, in particular, involves a highly complicated mechanism that requires deep knowledge of polymer properties as well as an analytic approach different from that used for a general isotropic material when the molded material is used as a structural material. This is because the parts made of polymer have pre-stress factors such as intrinsic deformation and residual stress. The most important factors for injection molded plastic products are injection molding condition and cavity design, taking into account ease of molding, mass production and application. Despite optimal injection molding conditions and cavity design, however, glass fiber orientation is critically linked to strength reduction. The application of injection molding and structural coupled analysis provides a low-cost solution for product molding and structural validation, all prior to the actual molding. The purpose of this study involves the validation, pre-study, and solution of defect in injection-molded polymer automotive parts using the simulation software for injection molding and structural coupled analysis. Finally, this thesis provides validation of an injection molding and structural coupled analytic mechanism that can demonstrate the effect of glass fiber orientation on mechanical strength. Design improvement ideas for the injection molded product of PPS (Poly Phenylene Sulfide)+40% glass fiber are also suggested.

• Journal of Astronomy and Space Sciences
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• v.15 no.1
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• pp.209-220
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• 1998

The stability problem of steady motion of a rigid body with multi-elastic appendages and multi-liquid-filled cavities, in the presence of no external forces or torque, is considered in this paper. The flexible appendages are modeled as the clamped -free-free-free rectangular plates, or/and as the discrete mass- spring sub-system. The motion of liquid in every single ellipsoidal cavity is modeled as the uniform vortex motion with a finite number of degrees of freedom. Assuming that stationary holonomic constraints imposed on the body allow its rotation about a spatially fixed axis, the equation of motion for such a systematic configuration can be very complex. It consists of a set of ordinary differential equations for the motion of the rigid body, the uniform rotation of the contained liquids, the motion of discrete elastic parts, and a set of partial differential equations for the elastic appendages supplemented by appropriate initial and boundary conditions. In addition, for such a hybrid system, under suitable assumptions, their equations of motion have four types of first integrals, i.e., energy and area, Helmholtz' constancy of liquid - vortexes, and the constant of the Poisson equation of motion. Chetaev's effective method for constructing Liapunov functions in the form of a set of first integrals of the equations of the perturbed motion is employed to investigate the sufficient stability conditions of steady motions of the complete system in the sense of Liapunov, i.e., with respect to the variables determining the motion of the solid body and to some quantities which define integrally the motion of flexible appendages. These sufficient conditions take into account the vortexes of the contained liquids, the vibration of the flexible components, and coupling among the liquid-elasticity solid.

• Journal of the Korean Magnetic Resonance Society
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• v.9 no.1
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• pp.38-47
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• 2005

Axin is a scaffold protein of the APC/axin/GSK complex, binding to all of the other signalling components. Axin interacts with Glycogen synthase kinase 3$\beta$ (GSK 3$\beta$) and functions as a negative regulator of Wnt signalling pathways. To determine the solution structure of the GSK3$\beta$ binding regions of the axin, we initiated NMR study of axin fragment comprising residues 3$Val^{388} - Arg^{401}$using circular dichroism (CD) and two-dimensional NMR spectroscopy. The CD spectra of 3$axin^{pep}$ in the presence of 30% TFE displayed a standard 3$\alpha$-helical conformation, exhibiting the bound structure of 3$axin^{pep}$ to GSK3$\bata$. On the basis of experimental restraints including $NOE_s$, and $^3J_{HN\alpha} $ coupling constants, the solution conformation of $axin^{pep}$ was determined with program CNS. The 20 lowest energy structures were selected out of 50 final simulated-annealing structures in both water and TFE environment, respectively. The $RMSD_s$ for the 20 structures in TFE solution were 0.086 nm for backbone atoms and 0.195 nm for all heavy atoms, respectively. The Ramachandran plot indicates that the $\varphi$, $\psi$ angles of the 20 final structures is properly distributed in energetically acceptable regions. $Axin^pep$ in aqueous solutions consists of a stable $\alpha$-helix spanning residues form $Glu^{391}$ to $Val^{391} $, which is an interacting motif with GSK3$\beta$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.2
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• pp.236-247
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• 2002

We propose a cell－multiplexing scheme for the real－time communication service in ATM network and a new service discipline guarantee end-to-end delay based on pseudo-isochronous cell switching. The proposed scheme consists of two level frame hierarchy, upper and lower frame, which is used to assign the bandwidth and to guarantee the requested delay bound, respectively. Since the Proposed algorithm employs two level frame hierarchy, it can overcome the coupling problem which is inherent to the framing strategy It can be comparatively reduce the complexity, and still guarantee the diverse delay bounds of end-to-end. Besides, it consists of two components, traffic controller and scheduller, as the imput traffic description model and regulates the input traffic specification. The function of the traffic controller is to shape real -time traffic to have the same input pattern at every switch along the path. The end-to-end delay is bounded by the scheduller which can limit the delay variation without using per-session jitter controllers, and therefore it can decrease the required buffer size. The proposed algorithm can support the QoS's of non-real time traffic as well as those of real time traffic.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.5C
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• pp.445-453
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• 2002

We propose a cell-multiplexing scheme for the real-time communication service in ATM network and a new service discipline guarantee end-to-end delay based on pseudo-isochronous cell switching. The proposed scheme consists of two level frame hierarchy, upper and lower frame, which is used to assign the bandwidth and to guarantee the requested delay bound, respectively. Since the proposed algorithm employs two level frame hierarchy, it can overcome the coupling problem which is inherent to the framing strategy. The proposed scheme consists of two components, traffic controller and scheduller, as the imput traffic description model and regulates the input traffic specification. The function of the traffic controller is to shape real-time traffic to have the same input pattern at every switch along the path. The end-to-end delay is bounded by the scheduller which can limit the delay variation without using per-session jitter controllers, and therefore it can decrease the required buffer size. The proposed algorithm can support the QoS's of non-real time traffic as well as those of real time traffic

• Journal of the Korean Institute of Telematics and Electronics
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• v.8 no.2
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• pp.24-33
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• 1971

A noble method of delta modulation by means of pair transistor circuit having negative resistance charcteristic is presented. An RC parallel circuit is inserted between two eiuitter tarminals of the pair transistor circuit, and their emitters are driven by a square pulsed current source. Basically this is a relaxation oscillator circuit. But when the value of capacitors and resistanc R, and the pulse height of driving source are properly chosen, the RC parallel circuit apparently functions as integrating circuit of driviving pulses. Compared with the integrated voltage of capacitor C, a signal input voltatage supplied in series with RC parallel circuit between two emitters makes on or off either of the pair transistors. as the result, one bit pulse is sent out from the coupling resistance terminal of conducted transistor. The circuit diagram used for this experiment is presented, it i% composed with simple mod ulster circuit, differential amplifier and pulse shaping amplifier, The characteristics of the components of this ciruit are discussed, and especially quantumized noise in this delta modulation system is discussed in order to improve the signal to noise ratio which has a close relation with circut constants, quantumized voltage, pulse height and width of driving current source.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.3 s.333
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• pp.33-38
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• 2005

In this paper, we have designed and fabricated a hybrid ring coupler to prove the fabrication possibility of various passive components, applying millimeter wave using newly proposed transmission lines, i.e. BAMLs. The characteristics of the fabricated hybrid ing coupler were a the S31(coupling) of 3.58 dB, the S21(thru) of 3.31 dB at the 60 GHz center frequency, the S11(return loss) over 16.17 dB, S41(isolation) over 55 dB at 61 GHz, and the phase difference between port 2 and port 3 of $180{\pm}loat$ 60GHz. In order to reduce the size of hybrid ring coupler, we designed the hybrid ring coupler which inserts a slow wave structure. With this structure, we were able to reduce the hybrid ring coupler by $33\%$ area.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.2
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• pp.22-27
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• 2011

Rain sensor detecting the presence of rain outside windshield glass of automobile by receiving scattered light from rain drops is proposed. Rain sensor using windshield glass as light waveguide required precision optical apparatus to inject light signal into windshield glass, and it was susceptible to outside shock and vibration, resulting malfunction, which altered optical coupling ratio. Proposed rain sensor, which detected scattered light from rain drops outside optical waveguide, did not require optical components because it did not need to inject light signal into light waveguide. This was advantageous because the sensor was less effected by shock and vibration. Fabricated rain sensor using scattered light outside waveguide responded not only to rain drops but also mist particles under simulated rain conditions using spraying nozzle, thus it showed prospects as rain sensor for automobile application.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.11
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• pp.1130-1137
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• 2009

This paper proposes a new clock routing design for suppressing clock harmonic effects in a Printed Circuit Board (PCB) for a terrestrial Digital Multimedia Broadcasting(DMB) system. Typical crystal reference frequencies that are widely used in DMB tuners are 16.384 MHz, 19.2 MHz, 24.576 MHz. When the high-order harmonic components of these reference frequencies fall near the RF channel frequencies, receiver sensitivity of the tuners is seriously degraded. In this work, we propose a new clock routing design in order to address the clock harmonic coupling issue. The proposed design incorporates two inductors for isolating the clock ground from the main ground, and adopts a new strip line-style routing instead of the conventional microstrip line style routing to minimize the overlap area with the main ground. As a result, the RF sensitivity of the T-DMB tuner is improved by 2 dB.