• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1997년도 춘계학술대회 논문집
• /
• pp.118-122
• /
• 1997

This paper presents a 3d image processing which uses neural networks to combine a 2D vision camera and a laser slit beam. A laser slit beam from laser source is slitted by a set of cylindrical lenses and the line image of the slit beam on the object is used to estimate the object parameters. The neural networks allow to get the 3D image parameters such as the size, the position and the orientation form the line image without knowing the camera intrinsic parameters.

• 한국수산과학회지
• /
• 제44권4호
• /
• pp.413-422
• /
• 2011

An improved split-beam transducer for a 50 kHz fish-sizing echo sounder was developed. The main objective of this study was to minimize the side lobe level in the beam pattern and the distance between acoustic centers for adjacent transducer quadrants in the geometrical arrangement of array elements while maintaining a given number of transducer elements and beam width. To achieve these goals, a 32-element planar array transducer ($6{\times}6$ array with one element in each corner missing) was designed using the Dolph-Chebyshev shading function to suppress side lobes in the array beam pattern and fabricated by arranging the inter-element spacing to be substantially equal to half the wavelength using the transducer element of 0.4 times the wavelength in diameter. The performance characteristics of this split-beam transducer were evaluated in the experimental water tank of $5m{\times}5m{\times}6m$ (length${\times}$height${\times}$width). In this study, the design goal of the beam width and side lobe level for transmitting a beam pattern was initially set at $21^{\circ}$ and -30 dB, respectively. However, the measured beam width at 3 dB was $21^{\circ}$ in both directions with side lobe levels of -24.7 dB in the horizontal plane and -25.6 dB in the vertical plane. The averaged beam width at -3 dB of the receiving beam patterns for four receiving quadrants was $31.4^{\circ}$. The transmitting voltage response was 161.5 dB (re $1{\mu}Pa$/V at 1 m) at 50.23 kHz with a bandwidth of 2.16 kHz, and the averaged receiving sensitivity for four receiving quadrants was -178.13 dB (re 1 V/${\mu}Pa$) at 49.8 kHz with a bandwidth of 2.64 kHz.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1995년도 Proceedings of the Korea Automation Control Conference, 10th (KACC); Seoul, Korea; 23-25 Oct. 1995
• /
• pp.299-302
• /
• 1995

Recently, we proposed a 3-D range-image measuring system for a slowly moving object by mechanically scanning a laser light beam emitted from a self mixing laser diode. In this paper, we introduced that every object moves along a straight line course, which is set diagonally against the semiconductor laser beam so that we can recognize each shape and size parameters of objects separately from the acquired 3-D range-image. We measured a square mesa on a square plane as an object. The measured velocity was 4.44mm/s and 4.63mm/s with an error of 0.56mm/s to 0.37mm/s. And thickness error of the mesa was 0.5mm to 0.6mm, which was obtained from the 3-D range-image of the standstill or moving object with thickness of 17.Omm.

• 한국전자파학회논문지
• /
• 제22권10호
• /
• pp.934-940
• /
• 2011

본 논문에서는 이중 루프(double loops)를 이용한 새로운 재구성(reconfigurable) 빔 조향 (beam steering) 안테나를 제안하였다. 이중 루프 안테나는 내부 루프(inner loop)에 의한 동상(in-phase)의 빔과 외부 루프(outer loop)에 의한 이상(out-of-phase)의 빔이 중첩된 빔(superposed beam)을 가진다. 또한, 이중 루프 안테나는 내부 루프와 외부 루프를 연결하는 두 개의 가상 스위치(artificial switch)를 사용하여, 가상 스위치 동작(on/off)에 따라 동일한 안테나에서 서로 다른 세 가지 경우(Case 1, Case 2, Case 3)의 빔 방향(beam direction)을 가진다. 안테나의 동작 주파수는 14.5 GHz이며, Case 1에서의 최대 빔 방향은 ${\phi}_{max}=0^{\circ}$, ${\theta}_{max}=0^{\circ}$이고, Case 2와 Case 3에서의 최대 빔 방향은 각각 ${\phi}_{max}=230^{\circ}$, ${\theta}_{max}=40^{\circ}$와 ${\phi}_{max}=130^{\circ}$, ${\theta}_{max}=40^{\circ}$이다. 각 경우의 최대 이득(peak gain)은 6.5 dBi(Case 1), 7.6 dBi(Case 2), 7.8 dBi(Case 3) 값을 가지며, 각각의 반전력 빔 폭(HPBW)은 $86{\sim}104^{\circ}$이며, 3가지 빔에 의한 전체반전력 빔 폭(HPBW)은 $160^{\circ}$이다.

• 한국통신학회논문지
• /
• 제41권12호
• /
• pp.1748-1751
• /
• 2016

본 논문에서는 휘어지거나 굴곡진 array인 3차원 conformal array의 beam pattern을 보정하고자 interpolation technique을 3차원으로 확장하여 3-D uniform rectangular array(3-D URA)에 적용하는 방법을 연구하였다. 시뮬레이션 결과는 2차원 interpolation 결과보다 매우 우수한 특성을 보여준다.

• Nuclear Engineering and Technology
• /
• 제31권5호
• /
• pp.512-521
• /
• 1999

A feasibility study was performed to design an epithermal neutron beam for BNCT using the neutron of 2.45 MeV on the average produced from $^2H(d,n)^3$He reaction induced by plasma focus in the z-pinch instead of the conventional accelerator-based $^3H(d, n)^4$He neutron generator. Flux and spectrum were analyzed to use these neutrons as the neutron source for BNCT. Neutronic characteristics of several candidate materials in this neutron source were investigated Using MCNP Code, and $^7LiF$ ; 40%Al + 60%$AIF_3$, and Pb Were determined as moderator, filter, and reflector in an epithermal neutron beam design for BNCT, respectively. The skin-skull-brain ellipsoidal phantom, which consists of homogeneous regions of skin-, bone-, or brain-equivalent material, was used in order to assess the dosimetric effect in brain. An epithermal neutron beam design for BNCT was proposed by the repeated work with MCNP runs, and the dosimetric properties (AD, AR, ADDR, and Dose Components) calculated within the phantom showed that the neutron beam designed in this work is effective in tumor therapy. If the neutron source flux is high enough using the z-pinch plasma, BNCT using the neutron source produced from $^2H(d,n)^3$He reaction will be very feasible.

• 한국인터넷방송통신학회논문지
• /
• 제20권6호
• /
• pp.123-128
• /
• 2020

본 논문에서는 3차원 동영상을 구현하기 위하여 인체에 유해한 방사능 피폭량이 부챗살 형태의 Fan Beam 보다 상대적으로 적은 원추형 Cone Beam CT 시스템을 설계하였다. 설계된 시스템은 X-ray가 조사된 각도에서 획득한 데이터를 영상처리부로 전송하고 영상을 구성하는 계산 속도를 빠르게 하기 위하여 초월함수가 보다 적은 3단계 회전 행렬을 이용하여 3차원 영상을 구현하는 회전 기반법을 사용하였다. 본 연구에서는 3차원 영상을 구성하는 시간단축을 통해 초당 3~5장의 영상을 얻음으로써 3차원 동영상을 실시간으로 구현하였으며 기존의 데이터 적층 방법에 비해 본 논문에서 사용한 회전 기반법이 우수함을 증명하였으며 단점 및 해결방법 제시하였다.

• 한국정밀공학회지
• /
• 제22권7호
• /
• pp.170-176
• /
• 2005

Analysis of structures which are composed of numerous repeated unit structures can be simplified by using homogenized properties. If the unit structure is repeated in one direction, the whole structure may be regarded as a beam. Once the effective stiffness is obtained from the analysis of the unit structure in a proper way, the effort for the detail modeling of the global structure is not required, and the real structure can be replaced simply with a beam. This study proposes a kinematical periodicity constraint to be imposed on the FE model of the unit structure, which improves the accuracy of the effective stiffness. The method is employed to a one dimensionally arrayed 3D structure containing periodically repeated un-symmetric holes. It is demonstrated that the deformation behavior of the homogenized beam agrees well with that of the real structure.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2011년도 춘계학술대회 논문집
• /
• pp.779-780
• /
• 2011

• 한국의학물리학회지:의학물리
• /
• 제7권2호
• /
• pp.3-17
• /
• 1996

방사선 치료분야에서 선량 보상체가 널리 이용되고 있으나, 그 보상효과에 대한 확실한 검증 방법은 알려진 바가 거의 없다. 본 연구에서는 Missing Tissue 뿐 아니라, Internal Tissue Inhomogeneity 까지 고려한 3차원 보상체를 제작하고, Exit Beam Dose Profile의 측정값과 본 연구에서 고안한 방법으로 기대값을 구해 비교함으로써 보상체의 성능을 평가하고자 하였다. 환자정보는 CT Simulator를 사용하여 얻었고, 보상체 정보는 Render Plan 3-D Planning System을 통해 얻었다. Computer Controlled Milling Machine으로 알루미늄 보상체를 제작해서 보상체가 있는 경우와 없는 경우의 선량 프로파일을 측정하여 비교하였다. 측정은 폴리스티렌 팬톰 사이에 필름을 삽입하여 팬톰 내에서의 실제 선량 분포를 구하고, 필름 카셋트를 이용해서 Exit Beam Dose Profile 을 동시에 얻었다. Oblique Beam, Parallel Opposing Beam, Inhomogeneus Human Phantom에 대해 제작된 보상체가 각각 선량보상 효과가 잘 나타남을 볼 수 있었고, 이 연구에서의 성능확인 방법을 통해 보상체의 성능을 확인할 수 있었다.