• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.4
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• pp.599-609
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• 2000

In this paper, sub-harmonically pumped single balanced resistive mixers are presented . Frequency bandwidth is selected for a Ku-band, which is 11.75-12.25GHz for RF, 5.375∼5.625 GHz for LO, and 1 GHz for IF signals. A rat-race hybrid is designed for the accomplishment of single balanced type. A low pass filter (LPF) with photonic band gap(PBG) structure is used for good conversion loss and unwanted harmonics suppression. Two types of mixers are suggested, which are one with no gate bias for no DC power consumption and the other with the IF amplifier for conversion gain. When a LO signal with the power of 6 dBm at 5.5 GHz is injected, a conversion loss of 12.17dB and a conversion gain of 7.83 dB are obtained for each mixer. For the both mixers , LO to RF isolation of 20 dB and LO to IF isolation of 60dB are obtained. With the RF power of -30dBm to -3dBm, the mixer shows linear characteristics region of IF. this mixer can be applied for Ku-band and other microwave communication systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.10 no.6
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• pp.317-326
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• 1985

A broad-band design method of a lumped-element 3dB quadrature hybrid without magnetic coupling is proposed and discussed, where techniques of cascading fundamental hybrids via second-order delay equalizers and adding matching sections are adopted. It is shown that the designed broad-band lumped-element 3dB quadrature hybrid can be easily constructed and its bandwidth reaches up to 54%. Furthermore, the esperiments have been carried out, the results of which agree with the theoretical ones, and hence, the validity of the broad-band design method proposed here was confirmed.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.2073-2075
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• 2004

본 논문에서는 nonradiative dielcctric (NRD) 도파로를 이용하여 28GHz대에서의 single balanced mixer를 설계하였다. 혼합기에 필요한 $90^{\circ}$ hybrid direction기 3dB 결합기를 NRD 도파로를 이용하여 설계 하였고 CST MWS를 이용하여 설계 결과를 검중 하였으며 결과는 중심 주파수 28GHz에서 대역폭이 1GHz의 결합기를 설계하였음을 확인할 수 있었다. 이와동시에 다이오드를 부착하기 위해 NRD 도파로와 마이크로스트립의 매칭 구조를 1 pole UDR과 patch를 이용하여 혼합기를 설계, 제작하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.332-335
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• 2008

The purpose of this study is analysis of flow field where is around of injector of supersonic combustor which is bluff-body stabilized flame and hyper-mixer type of supersonic combustor injector by using hydrogen or hydrocarbon fuel. Various schemes are evaluated to supersonic backward step flow filed with massive separation region in validation step. Compounded scheme of 5th-order TVD-MUSCL, Roe FDS, S-A DES/DDES has a good performance in base and base-bleed flow.

• The Journal of the Korea Contents Association
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• v.7 no.3
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• pp.17-24
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• 2007

SIP-based tightly coupled conference, which has a centrally located conference server for controlling and management, can be classified several models according to location of focus and mixer. These are centralized server model, endpoint server model, media server component model and distributed mixing model. However each model has its strength and weakness. In this paper, we propose and implement a SIP-based effective hybrid-type conference model which decreases amount of SIP signaling messages, lowers load of server media mixer, and can be easily expandable to large scale conference. In this model, when the number of participants exceeds a pre-defined limit, the conference server selects some participants which posses specific functions and let them share functions of notifications of conference state event package and media mixing. When each participant subscribes conference state event package to the server, it can indicates its possession of such functions by a specific header message. The server stores the indication to the conference information database, and later uses it to select participants for load sharing. The performance of our proposed model is evaluated by experiments.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.3
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• pp.339-345
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• 2001

In this paper, FG-CPW (Finite-Ground Coplanar Wave-Guide) balanced diode mixer is presented. Frequency bandwidth is selected for a C-band, which is 5.72~5.82 GHz for RF, 5.58~5.68 GHz for LO, and 140 MHz for IF signals. A rat-race hybrid is designed for the accomplishment of single balanced type. A low pass filter (LPF) with CPW structure is used far good conversion loss and unwanted harmonics suppression. When LO signal with the power of 4 dBm at 5.635 GHz is injected, a conversion loss of 6.2 dB is obtained for the mixer. Also, the LO to RF and LO to IF isolation of 30 dB and 40 dB are obtained, respectively. This mixer can be used in the area on wireless LAN application.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.4
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• pp.667-673
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• 2000

This paper presents the modeling method of nonlinear circuits with lumped elements by using a hybrid Haar -wavelet MRTD/FDTD techniques. To analyze nonlinear circuits with lumped elements, the Haar-wavelet MRTD scheme is applied to the entire structure of interest and the conventional FDTD scheme is locally used to describe the characteristics of the lumped elements. To validate the scheme, microstrip structure with lumped elements and a single diode mixer are simulated.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.1
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• pp.77-83
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• 2016

Intricate deflection requires many conventional actuators (motors, pistons etc.), which can be financially and spatially wasteful. Novel smart soft composite (SSC) actuators have been suggested, but fabrication complexity restricts their widespread use as general-purpose actuators. In this study, a hybrid manufacturing process comprising 3-D printing and casting was developed for automated fabrication of SSC actuators with $200{\mu}m$ precision, using a 3-D printer (3DISON, ROKIT), a simple polymer mixer, and a compressor controller. A method to improve precision is suggested, and the design compensates for deposition and backlash errors (maximum, $170{\mu}m$). A suitable flow rate and tool path are suggested for the polymer casting process. The equipment and process costs proposed here are lower than those of existing 3D printers for a multi-material deposition system and the technique has $200{\mu}m$ precision, which is suitable for fabrication of SSC actuators.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.4 s.119
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• pp.379-388
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• 2007

This paper presents a real-time respiration and heartbeat detector comprised of a 1.6 GHz single-channel Doppler sensor and analog/digital signal processing block for remote vital sign detection. The RF front end of the Doppler sensor consists of an oscillator, mixer, low noise amplifier, branch-line hybrid and patch antenna. We apply artificial transmission lines(ATLs) to the branch-line hybrid, which leads to a size reduction of 40 % in the hybrid, while its performance is very comparable to that of a conventional hybrid. The analog signal conditioning block is implemented using second order Sallen-Key active filters and the digital signal processing block is realized with a LabVIEW program on a computer. The respiration and heartbeat detection is demonstrated at a distance of 50 cm using the developed system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.3
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• pp.292-300
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• 2010

In this paper, we propose a RF front-end architecture based on hybrid conversion which is available to receive both broadband and multiband DVB-H receiver, and a multi-function circuit for implementing the RF front-end is fabricated. A multi-function circuit is operated as a sub-harmonic mixer mode in the case of receiving a broadband VHF/UHF band, which show a conversion loss of -10.0 dB, noise figure of 7.0 dB and IIP3 of 2.0 dBm. On the other hand, it is performed as a attenuation mode with a insertion loss of -10.0 dB in receiving a multiband, L-band.