• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.5
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• pp.468-474
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• 2002

In this paper a novel two-arm microstrip spiral antenna with a circular slot on the ground plane is presented. The proposed antenna structure is constructed in a planar form without a balun circuit and the radiation characteristics of conventional and eccentric spiral antennas are obtained simultaneously. The main beam direction is normal to the plane of the spiral for characteristic frequency band and the direction of the main beam moves linearly into $\theta$ and $\phi$ direction as the frequency increases.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2001.11a
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• pp.176-179
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• 2001

본 논문에서는 접지면에 스파이럴 형태로 식각된 패턴을 갖는 DGS (Defected Ground Structure) 전송선로가 제시되었다. 제시된 스파이럴 DGS 회로에 대한 새로운 등가회로 모델을 제안하였고 등가회로의 각 파라미터는 EM-시뮬레이션과 DGS의 공진 특성 조건식으로부터 유도하였다. 스파이럴 DGS의 등가회로는 λ/2 단락 전송선로와 병렬로 연결된 인턱터로 구성된 비교적 간단한 구조로 제시되었다. 등가회로의 각 파라미터를 추출하고 기존의 아령 형태의 DGS 회로와 특성을 비교하여 장단점에 따른 그 응용성을 고찰하였다.

• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.276-278
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• 2003

본 논문에서는 축대칭 유한요소법을 이용하여 고주파에서 사용하는 스파이럴 인덕터를 분석하였다. 스파이럴 인덕터는 고주파 운용시 인덕터 도체에서 발생하는 표피 효과와 근접 효과, 실리콘 기판의 전도성으로 인한 와전류에 의한 저항 손실, 그리고 대류 전류에 의한 기생 용량으로 인덕턴스의 감소와 같은 현상이 발생한다. 이러한 다양한 전자기적 기생 효과들이 실리콘 기판에서 스파이럴 인덕터의 성능을 저하시키게 된다. 그러므로 이러한 점들이 실리콘 기판에서 스파이럴 인덕터를 설계 및 모델링 함에 있어서 동기를 부여해 준다. 그래서 우리는 복잡한 형상에도 적용이 용이한 유한요소법을 이용하여 스파이럴 인덕터를 해석 및 설계하였다.

• Explosives and Blasting
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• v.29 no.1
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• pp.10-16
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• 2011

To make large slopes or rock structures stable, supporting systems, such as anchor bolt, rock bolt and spiral bolt which are developed recently, are commonly used. In this study, in-situ pull-out tests were carried out to compare the characteristics of rock bolt that is most widely used with ones of spiral bolt that is newly developed. Re-pull-out test for the spiral bolt in which loading and unloading cycles are repeated three times showed that the maximum pull-out load is almost constant irrespective of the number of loading cycles, which may be due to no failure between spiral bolt and filler. On the other hand, the maximum pull-out load for the conventional rock bolt decreases with the number of loading cycles due to the partial failure between rock bolt and filler.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.2
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• pp.208-214
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• 2009

A design and its experimental result of a wideband self-complementary spiral antenna for UWB USPR(Ultrashort-Pulse Radar) system applications is presented. By utilizing the planar-type ultra-wideband microstrip-to-CPS balun, ultra-wideband characteristics of the inherent spiral antenna are retrieved. Also, the design procedure of the spiral antenna is simplified by performing simple impedance matching between separately designed balun and antenna. The proposed spiral antenna is equiangular self-complementary spiral antenna. The implemented antenna demonstrates widebaad performance for frequency ranges from 2.9 to 12 GHz with the relatively flat antenna gain of 2.7 to 5.3 dB and broad beamwidth of more than $70^{\circ}$. From these result, the possibility of a spiral antenna using a ultra-wideband microstrip-CPS balun is verified.

• Tunnel and Underground Space
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• v.19 no.3
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• pp.181-189
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• 2009

This study is to evaluate an effect of supports with respect to these supports after comparing the characteristic of support between rock bolt of a widely used type and spiral bolt of a new type. For these purposes, we performed pull-out test in laboratory about rock and spiral bolts in the case of cement-mortar grout curing periods, 7 and 28 days, then calculated pull-out load, displacement, external pressure, inner pressure and shear stress using data obtained from the results of pull-out test, respectively. In relation between pull-out load and displacement, displacement of spiral bolt is larger than one of rock bolt. It is considered that mechanical property of rock bolt is due to larger than one of spiral bolt. In addition, displacement of supports shows nearly same or decreasing with curing periods. We found that because adhesive force between supports and cement-mortar grout is increasing with compressive strength of grout according to curing periods. The inner pressure of spiral bolt is represented larger than one of rock bolt at a step of same pull-out load. It is suggested that spiral bolt is more stable than rock bolt, maintaining stability of ground or rock mass, when supports are installed in a ground or rock mass under the same condition. Putting together with above results, we can consider that spiral bolt as a new support on an aspect of pull-out load and inner pressure is larger than rock bolt in a ground or rock mass under the same condition. Moreover, spiral bolt is more effective support than rock bolt, considering an economical and constructive aspects of supports, as well as ground or rock stability before or after installing supports.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.575-579
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• 2015

본 연구에서는 스파이럴 보강을 한 원형 실린더 주위의 유동를 분석하였다. 이를 위해 스파이럴 보강 부분을 사각형 부착물로 분리해서 나타내었다. EDISON_CFD의 가상 경계법을 이용하여 원형 실린더와 부착물 주위의 유동 현상을 해석하였다. 부착물의 두께와 각도를 다르게 하여 각각의 공력 계수와 총 합력을 구하고 이에 따른 특성을 분석하였다.

• Tunnel and Underground Space
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• v.20 no.5
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• pp.332-343
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• 2010

This study aims to evaluate the supporting effect of a spiral bolt that is superior to a rock bolt in terms of constructability, stability, environmental and economic aspects as a support system. This study thus analyzed the mechanical properties of a rock bolt which is widely used as a support and a spiral bolt. In addition, laboratory pull-out tests were conducted for the evaluation of properties of the supports such as displacement, pull-out load, confining pressure etc. Moreover, the differences between a rock bolt and a spiral bolt were drawn by comparing the two results of laboratory pull-out tests and in-situ pull-out tests. Then, the differences of the supporting effect of the two supports were analysed by comparing the results of the two pull-out tests with a numerical analysis using FLAC3D.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.3
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• pp.269-277
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• 2010

In this paper, the design of a 0.5~2 GHz cavity-backed spiral antenna is described. Combined arm pattern with a log spiral in the inner region and an Archimedean spiral in the outer region, a backing cavity, and a Marchand coaxial balun for feeding are designed. Termination resistors are used to improve antenna characteristics at the lower frequency of the operation frequency. VSWR, axial ratio, gain and HPBW(Half Power Beam Width) characteristics are simulated using CST's MWS. Finally, the validity of these approaches is verified by comparing the simulated results with the measured ones. Also, the measurement results are compared with the performance of a commercial spiral antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.12
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• pp.1322-1332
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• 2008

In this paper, we proposed a divided two-arms spiral slot antenna fed by coplanar waveguide using the magnetic flow at slots. This antenna has characteristics of which one is to short-circuit at the end of the slot and another is to turn spirals separately. To reduce the offset of magnetic flow, two spiral slots are fed by 1800 phase difference. Because we proposed a printed two-arms spiral slot antenna without a balun circuit, antenna size become smaller substantially. And frequency characteristics are studied using the various design parameters. The bandwidth of the realized antenna is $2.7{\sim}12\;GHz$ below the return loss of -10 dB.