• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.9
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• pp.964-970
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• 2002

In this paper, cruciform radiation pattern antenna was designed and fabricated. The fabricated antenna is applicable to intersections which is composed of four eight-lane roads each having 60 m of width and 200 m of length. The design theory was based on Woodward-Lawson method and the 6 monopole elements with the strip feeding network are made by linear array on the micro-strip board. In the results, - 13.5 dB of return loss and 120 MHz(6 %) of -10 dB bandwidth were obtained at the 2 GHz. Also, at 1.95 GHz, -6 dB of gain fall was seen at $\pm$45$^{\circ}$ and thus, it is possible to say that the presented antenna has well-shaped cruciform radiation pattern.

• Environmental and Resource Economics Review
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• v.15 no.4
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• pp.741-760
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• 2006

As a part of the 21st Century Frontier Projects, Korea is building a proton linear accelerator complex. Using the discrete choice conjoint analysis method, this study evaluates the complex. Multinomial logit model is employed as an econometric model and Hicks' compensating variation is adopted as a welfare measure. The results show that an average willingness-to-pay (WTP) of a would-be user measured by the compensating variation is estimated by 1.93 million Korean won per hour for the specification of the complex being built.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.8
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• pp.766-773
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• 2016

This paper proposes an aircraft-installed compact offset-parabolic-reflector antenna for the spinning direction-finding applications. The feeder of the reflector antenna is a LPDA antenna that has the ultra-wideband characteristics and the $45^{\circ}$ slant linear polarization. The reflector is designed to be slanted by $5^{\circ}$ in the elevation and to be small in size on the basis of the reference parabolic shape for the purpose of the high gain and mounting on the underside of aircraft fuselage. Over the ultra-wideband 20:1 bandwidth from S to Ka band, the measured average gain of the proposed antenna is 27.97 dBi, and the average half-power beam width is $4.55^{\circ}$ in the azimuth and $4.3^{\circ}$ in the elevation which is the pencil-beam radiation pattern. All the measured data are similar to the simulation results. The designed compact offset-parabolic-reflector antenna that is installed in the limited area has the ultra-wideband and high-gain characteristics. We expect that the newly designed antenna can be applied to the spinning direction-finding antenna system installed in an aircraft.

• Progress in Medical Physics
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• v.27 no.2
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• pp.72-78
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• 2016

A CCD camera and an LED light source were combined to fabricate a compact optical CT scanner for the therapeutic radiation dose evaluation of a polymer gel dosimeter. After the collimated beam emitted by the LED passed through aquarium, gel phantom, and telecentric lens, an image was collected by the CCD camera and reconstructed using MATLAB. By using a stepping motor and LabVIEW, the gel dosimeter was rotated at every $0.72^{\circ}$, and the time for collecting 500 slice images per a revolution was within 20 min. At a spatial frequency of 4.5 lp/mm of the optical CT scanner, the modulation transfer function value was 72%. The linear correlation coefficient of the optical CT scanner for the polymer gel dosimeter was 0.987.

• Composites Research
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• v.29 no.5
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• pp.288-292
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• 2016

In this paper, a novel ultrasonic propagation imaging system, called a full-field pulse-echo ultrasonic propagation imaging (FF PE UPI) system is introduced. The system nondestructively inspected targets with two-axis translation stage. The coincident laser beams for ultrasonic sensing and generation are scanned and pulse-echo mode laser ultrasounds are captured. This procedure makes it possible to generate full-field ultrasound in through-the-thickness direction as large as the scan area. Structural inspection results in the form of full-field ultrasonic wave propagation videos are introduced, which are painted sandwich control surfaces. In addition, the inspection results of FF PE UPI system are compared with conventional ultrasonic testing methods such as waterjet and portable C-scan.

• Korean Journal of Optics and Photonics
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• v.18 no.4
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• pp.241-245
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• 2007

In this study, a two-dimensional fiber-optic radiation sensor has been developed using water-equivalent organic scintillators for photon beam therapy dosimetry. Two-dimensional photon beam distributions and percent depth doses(PDD) are measured according to the energies and field sizes of the photon beam. This sensor has many advantages such as high resolution, real-time measurement and ease of calibration over conventional radiation measurement devices.

• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.2
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• pp.74-80
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• 2005

A new dimension measuring method for the measurement of diameter of an object has been developed using laser triangulation. The 3D data of an object was calculated from the 2 dimensional image information obtained by the laser stripe using the laser triangulation. The system that use existing theory can measure the diameter of hole not only in a normal plane but also ill an incline plane. However, in the existing theory, since the lens with fixed feral length was used, the area of measurement was fixed. The simplest way to solve this problem is to change distance between a CCD camera and object. Other way is to use a zoom lens having variable focal length. In this paper, the zoom lens with variable focal length was used. Therefore, we ran experiment with magnification that is optimized according to size of object using zoom lens with variable focal length.

• Journal of the Korean Society of Radiology
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• v.14 no.5
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• pp.529-535
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• 2020

Geant4 is compatible with the Windows operating system in C++ language use, enabling interface functions that link DICOM or software. It was simulated to address the basic structure of the simulation using Geant4/Gate code and to specifically verify the density composition and lung cancer process in the human phantom. It was visualized using the Gate Graphic System, i.e. openGL, Ray Tracer: Ray Tracing by Geant4 Tracing, and using Geant4/Gate code, lung cancer is modeled in the human phantom area in 3D, 4D to verify the simulation progress. Therefore, as a large number of new functions are added to the Gate Code, it is easy to implement accurate human structure and moving organs.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.77-77
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• 1999

박막시료의 분석에는 RBS, XPS, SIMS, AES 등이 주로 이용되고 있으며, 특히 RBS는 비교체가 필요없고 정량성이 좋다는 장점 때문에 중요하다. 그러나 RBS는 원리적으로 경원소에 대한 감도가 낮아 기판원소보다 무거운 질량을 갖는 원소의 분석에만 이용되는 것이 보통이다. 이러한 단점을 보완하기 위해 본 연구에서는 수년전부터 RBS와 비슷한 원리를 갖고 같은 장비를 이용하여 수행이 가능한 경원소 분석법인 TOF-ERDA(Time of Flight Elastic Recoil detection)을 개발하여 실용화 하였다. 본 연구실에서 보유하고 있는 미국 NEC사의 5SDH 가속기는 최대 가속전압이 1.7MV로 Cl5+ 이온을 사용하는 경우 10 MeV가 최대 가속에너지가 된다. 이런 정도의 에너지 범위에서는 TOF spectrometer의 시간분해능이 아주 높을 필요가 없고 비교적 작은 가속기로도 분석이 가능하며, 수소의 검출효율이 우수하다는 점 등 많은 장점이 있다. 그러나 한편으로는 분석가능한 깊이가 수천 $\AA$ 정도로 제한되고 질량 분해능도 수십 MeV 내지 100MeV 이상의 고에너지 이온빔을 이용하는 경우에 비해 떨어진다는 단점이 있다. 또한 묵운 원소의 분석이 불가능하기 때문에 경원소의 분석에 국한하여 적용하고 무거운 원소에 대해서는 RBS를 병용하게 된다. 본 연구에서는 일본 이화학연구소의 선형가속기인 RILAC으로부터 얻은 40MeV Ar 이온 및 138 MeV Xe 이온을 이용하여 TOF-ERDA 시스템을 제작하였다. 그러기 위해서 고에너지 이온의 비행시간을 측정하는 목적으로 높은 시간 분해능을 갖는 시간 검출기를 설계, 제작하였다. 또한 표적함 밑에는 회전원판이 있어 시간검출기 및 에너지 검출기가 중앙의 시료홀더를 중심으로 회전이 가능하도록 되었다. 회전은 표적함 밖에서 원격조정 가능하다. 이렇게 함으로써 검출각을 임의로 바꾸면서 측정이 가능하도록 하였다. 제작된 분석시스템의 성능을 확인하기 위해 YBaCuO 초전도 박막을 측정하였으며 그 결과를 그림에 나타낸다. 저 에너지 ERDA에서는 나타나기 힘든 Ba, Y, Cu 등의 무거운 원소의 피크들이 분명히 나타남을 확인할 수 있다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.7 no.2
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• pp.198-208
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• 1995

Combining Iwan-Blevin's model into the approximated form of the nonlinear model derived for the dynamic analysis of the riser system with the inclusion of internal flow, current-vortex model is developed to investigate the effect of internal flow on vortex-induced vibration due to inline current The riser system includes a steadly flow inside the pipe which is modeled as an extensible or inextensible tubular beam. Galerkin's finite element approximation are implemented to derive the matrix equation of equilibrium for the finite element system. The investigations of the effect of internal flow on vibration due to inline current are performed according to the change of various parameters such as top tension, infernal flow velocity. current velocity, and so on. It is found that the effect of internal flow on vibration due to vortex shedding can be controlled by the increase of top tension. However, careful consideration has to be given, in design point in order to avoid the resonance band occurding near vortex shedding frequency, particularly for the long riser.