• 한국전자파학회논문지
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• 제21권2호
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• pp.143-151
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• 2010

본 논문에서는 Metamaterial CRLH 구조 기반의 0차 공진현상이 발생되는 새로운 직각 패치 안테나가 제안된다. 일반 마이크로스트립 패치 구조의 기본 공진 모드인 반파장 공진이나 반파장 공진의 양의 정수배가 아닌 구조 전체에 전계가 같은 위상을 갖게 하면서, 기존에 발표된 다수의 금속 쎌들이 일렬 연결된 1차원 0차 공진 안테나의 구조와 달리 금속 패치 주위에 하나의 용량성 결합 직각 링만을 부착하는 구조를 제안하는 것이다. 2.4 GHz에서 0차 공진 특성을 갖도록 설계된 등가회로에 따른 물리 구조의 치수들이 입력된 3차원 전자장 분석기에서 안테나의 성능에 대한 모의시험을 수행한다. 설계 결과 2.4 GHz에서 공진점을, 그리고 이득과 효율은 각각 5 dB와 98%를 얻었다. 또한 본 논문이 제안하는 안테나가 마이크로스트립 패치 안테나의 장점인 low-profile과 모노폴 안테나의 장점인 전방향 패턴을 동시에 가지는 특징이 논의된다.

• 대한기관식도과학회지
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• 제10권2호
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• pp.17-21
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• 2004

Background Insertion of tracheal stent in the treatment of benign tracheal & bronchial disease has increased since the introduction of expandable metallic stent. Material & Methods : Between Jan, 1995 and Feb. 2004, eight patients who had benign tracheo-bronchial disease underwent insertion of expandable metallic tracheal stent. We retrospectively analyzed stent insertion indications, complications, and following the result. Results : Surgical indications were post-intubation tracheal stenosis (1 case), tracheal stenosis following tracheal surgery (2 cases), tracheo-esophageal fistula (2 cases), broncho-pleural fistula(1 case), left main bronchus stenosis following bronchoplasty (1 case), and left main bronchus stenosis due to mediastinal repositioning (1 case). Expandable metallic tracheal stent was inserted in five patients to resolve dyspnea caused by airway obstruction, and to prevent recurrent pneumonia in three patients. The complication developed in 6 patients $75\%$; 3 cases of distal stenosis due to growth of granulation tissue, and one case each of tearing of posterior membrane, aggravation of tracheo-esophageal fistula, and airway partial obstruction due to stent migration. The stent was removed in 5 patients and tracheal surgery (tracheal resection and end to end anastomosis with primary repair of esophagus, pericardial patch tracheo-bronchoplasty, tracheal repair and omental wrapping) was performed in 3 patients. Conclusion Insertion of self expandable metallic stent in benign tracheo-bronchial disease is an effective means of relieving dyspnea for only a short period, and it did not increase the long term survival. Better means of treatment of benign tracheo-bronchial stenosis in necessary.

• Advances in materials Research
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• 제5권1호
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• pp.11-20
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• 2016

In bonded composite repair of aircraft structures, the damage of the adhesive can thus reduce significantly the efficiency and the durability of the bonded composite repair. The adhesive damage models using critical zone have proven their effectiveness due to simplicity and ap-plicability of the damage criteria in these models. The scope of this study is to analyze the effects of the patch thickness and the adhesive thickness on the damage damage in bonded composite repair of aircraft structures by using modified damage zone theory. The obtained results show that, when the thickness of adhesive increases the damage zone increases and the adhesive loses its rigidity, inversely when the patch is reduced the adhesive damage be-comes more significant.

• ETRI Journal
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• 제39권3호
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• pp.383-389
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• 2017

A small dual-polarized base station antenna with a simple isolation patch is presented. A high isolation is achieved when using a shorted metallic isolation patch. The experimental results indicate that the measured impedance bandwidth of the proposed antenna is 1.72 GHz to 1.89 GHz for small cell systems and that the isolation is more than 30 dB. The proposed antenna exhibits good radiation patterns with a peak gain of 8 dBi.

• Journal of electromagnetic engineering and science
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• 제1권1호
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• pp.67-72
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• 2001

In this paper, the plano-convex lens antenna fed by a single patch is studied for a microwave remote-traffic monitoring sensor with constraints of small size and low cost. Measurement of an AUT (Antenna Under Test) involves the considerations of a triangular groove for matched layer and metallic shielding effects. A formulation for extracting the parameters of a piano-convex lens antenna, based on geometrical optics, is introduced using Fermat`s principle of the equi-phased ray condition. Teflon ($\varepsilon_{{\gamma}}$/ =2.0) is chosen as a material of a plano-convex lens antenna for adjustment of aberrations on the lens surfaces automatically. A fabricated plano-convex lens shows 3-dB beamwidth of 7.5 degree and side-lobe level of -29 dB with an aperture distribution of the parabolic-squared taper on pedestal. This lens supports easier integration with the planar microwave circuits by using a microstrip single patch as a primary feeder of the lens antenna.feeder of the lens antenna.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.606-612
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• 2008

Creep force is one of the only appeared at conventional train which used to be driven by metallic wheel and rail contact. Due to the elastic deformation of wheel/rail contact patch by the weights of wheel and all the components related to it, creep force generates and becomes to the decision factor of critical speed of bogie(or railway vehicle) which is the criteria of avoiding vehicle to be unstable. There are many kind of factors which affect generation of creep force at a wheel/rail contact surface such as viscosity of contact patch, velocity, wheel and rail geometric profile, mechanical properties of wheel and rail. This paper concentrates on a wheelset simple 2 DOF Equation of Motion being exerted. From the simple numerical analysis using linear solution about getting creep force some factors could find roughly. Among the factors geometric parameter could be the one of most important for this study. In the future we'll prolong the range of study to find out method of measuring creep force easily.

• Smart Structures and Systems
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• 제8권1호
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• pp.93-105
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• 2011

This paper presents a flexible low-profile antenna sensor for fatigue crack detection and monitoring. The sensor was inspired by the sense of pain in bio-systems as a protection mechanism. Because the antenna sensor does not need wiring for power supply or data transmission, it is an ideal candidate as sensing elements for the implementation of engineering sensor skins with a dense sensor distribution. Based on the principle of microstrip patch antenna, the antenna sensor is essentially an electromagnetic cavity that radiates at certain resonant frequencies. By implementing a metallic structure as the ground plane of the antenna sensor, crack development in the metallic structure due to fatigue loading can be detected from the resonant frequency shift of the antenna sensor. A monostatic microwave radar system was developed to interrogate the antenna sensor remotely. Fabrication and characterization of the antenna sensor for crack monitoring as well as the implementation of the remote interrogation system are presented.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권9호
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• pp.2253-2265
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• 2012

A novel folded dipole type microstrip patch antenna designed for ultrahigh frequency (UHF) band radio frequency identification (RFID) tag is presented in this paper, which can be used on the metallic objects. The presented antenna is fabricated on a very thin Rogers 5880 substrate with a thickness of 0.508 mm. The structure consists of two folded dipole and two symmetrical shorting pins placed at both sides of feed point. An adjustable frequency response can be easy obtained via modify the location and radius of the shorting pins. The antenna has been analyzed by full wave simulations soft. The simulated bandwidth is about 67.2 MHz, which covers the Europe and North America UHF RFID frequency range. A manufactured prototype has been fabricated and measured to demonstrate the antenna performances. The simulation results agree with the measurement data well. The measured maximum reading range of the prototype can be reached 4.1 m in free space, and 3.2 m on a metal plate whose size is $150{\times}150{\times}8mm^3$.

• 한국전자파학회논문지
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• 제10권5호
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• pp.727-737
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• 1999

마이크로스트립 안테나는 츄전체층이 있으므로 해서 대역폭과 방사 효율의 제한을 받고 있다는 것은 잘 알려져 있다. 본 논문에서는이러한 제한을 극복하기 위해 유전체를 갖고 있는 구조체의 사용대신 금속봉이나 비금속봉으로 지탱되는 금속판으로 구성된 구조체를 사용한다. 본 연구의 가장 중요한 동기는 기존의 안테나보다 높은 방사효율을 보이는 광대역 마이크로스트립 안테나를 구현하는 데에 있다. 또한 대역폭의 증가를 위해 패치의 크기와 높이 그리고 임피던스 정합이 고려된다.

• ETRI Journal
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• 제32권3호
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• pp.472-474
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• 2010

In this letter, a novel zeroth-order resonant (ZOR) antenna on vialess co-planar waveguide (CPW) is proposed. It is based on a composite right/left-handed CPW transmission line. To achieve a compact size, this antenna utilizes the ZOR condition, and its reactive parameters determine the resonant frequency. Each unit cell is composed of a metallic top patch and meander lines. Since it is realized on the CPW single layer, the proposed antenna has the benefits of being a compact size and easy to fabricate. The bandwidth of 6.8% and efficiency of 62% are experimentally achieved. Its bandwidth is enhanced compared with other ZOR antennas.