• Journal of Korean Ophthalmic Optics Society
• /
• v.6 no.2
• /
• pp.47-52
• /
• 2001

We investigate the variation in the shape of confusion circle as the real amplitude distribution of incident beam in pupil area is shifted and the effect of the shift of incident beam on the astigmatism for eye. The shifted magnitudes of Incident beam are 0.0, 0.25, 0.5 and 0.75 and the shifted direction of incident beam ${\pi}/2$. We also consider the optical system having the astigmatism which are $0.0{\lambda}$, $0.25{\lambda}$, $0.5{\lambda}$ and $0.75{\lambda}$. As the shifted magnitude of the real amplitude distribution of incident beam increases, the shape of confusion circle on the image surface transfers from the rotational symmetry to the asymmetry like ellipse and the length of the major axis for confusion circle on the Image surface increases. We know from results in this paper that the shift of the incident beam in pupil area compensates the effect of astigmatism and the real amplitude distribution of incident beam in pupil area is shifted to minimize the effect of astigmatism for eye.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
• /
• 1991.07a
• /
• pp.36-39
• /
• 1991

현지 해안에서 발생하고 있는 표사이동량을 정확히 예측하기 위해서는 내습파랑의 방향 분산성과 불규칙성이 표사이동량에 어떠한 영향을 줄 것 인가에 대해 명백히 해둘 필요가 있다. 본 연구는 표사유송흐름으로서 해빈류의 추진적이 되는 radiation stress에 착목하여, 그들에 미치는 입사파랑의 방향분산성 및 불규칙성의 영향에 대하여, 주로 파별 해석법에 근거를 두고 수치적인 검사를 행한 것이다.(중략)

• Journal of the Korea Convergence Society
• /
• v.10 no.1
• /
• pp.1-6
• /
• 2019

In this paper, we have studied a direction finding method of the radio signal by comparing the phase difference and its pattern from the uniform circular array antenna. In the phase comparison direction finding, if the length of the antenna baseline is longer than 0.5 wavelength of the incident signal, azimuth ambiguity occurs in which two or more azimuth angles are calculated in the same phase difference. The azimuthal ambiguity is removed by fusing the phase difference of the 5 antennas. The developed ambiguity elimination technology reduces the azimuth error where the antenna baseline is shorter than 1.236 wavelength in the uniform circular array with five antennas. This algorithm is very useful for the design of direction finder of an electronic information system.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2022.06a
• /
• pp.401-402
• /
• 2022

해상 상태의 변화는 어선에 탑승하고 있는 선원들의 피로도, 인지능력, 활동성 및 숙련도 변화 등과 같은 현상이 발생한다. 어선의 동요가 심해지면 특히, 멀미 증상이 발생하게 되며 개개인의 작업수행 능력이 급격히 떨어진다. 본 연구에서는 3톤급, 7톤급, 10톤급, 20톤급 어선을 대상으로 하여 파랑 중 운동 성능을 평가하여, 실해역 조건으로 어선의 선내 위치별 수직가속도 성분을 선체 운동 계산법을 통하여 계산하였다. 어선의 크기별 정박상태에서 수직가속도 스펙트럼을 사용한 멀미의 정도를 표시하였으며, MSI 계산은 입사파 방향 180도, 150도, 120도, 90도, 60도, 30도, 0도로 수행하였다. 그 결과 특정 주파수에서 입사파 방향에 따른 멀미의 가능성이 나타났다.

• Journal of the Korean Society of Radiology
• /
• v.12 no.3
• /
• pp.373-379
• /
• 2018

The purpose of this study was to investigate quantitative data on the difference in breast entrance surface dose with changes in focus-film distance, patient posture (anteroposterior-posteroanterior), thoracic wall thickness, rib bone thickness, lung tissue thickness, tube voltage, and high-voltage rectification method in Whole Spine Scanography, which is necessary for the treatment of scoliosis patients. Given a tube voltage of 90 kVp, kerma of 0.1 mGy, focus-film distance of 260 cm, tube voltage ripple rate of 0, filter thickness of 3.5 mm, and thickness of patient's thoracic wall of 120 mm as an X-ray exposure condition, from the simulation results using the Simulation of X-ray Spectra program to confirm the reduction effect of breast entrance surface dose according to the patient's posture (AP and PA), there was a dose reduction effect in aluminum filter thickness of 2.6 times at 3.5 mm, 25.7 times the thoracic wall thickness at 120 mm, 1.43 times higher tube voltage, and 0 to 1.14 times the tube voltage ripple rate. The total dose reduction effect was about 109 times. In order to confirm the dose reduction effect of RANDO phantom posture (AP and PA), from the results of the measurements taken under the conditions that the focus-film distance was 260 cm, the tube voltage was 90 kVp, the tube current was 270 mA, the exposure time was 0.31 sec, and the tube voltage ripple rate of X-ray generators was 0, the entrance surface dose reduction effect of the breast in the PA position was found to be 20.56 times lower than that of the AP position.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.27 no.8
• /
• pp.676-683
• /
• 2016

In this paper, an adaptive nulling algorithm which can be used to form nulls in the direction of jammer or interference signals in array antennas of single port system is proposed. The proposed adaptive algorithm does not require a priori knowledge of the incoming signal direction and can be applied to the partially adaptive arrays. This algorithm is the combination of the PSO(Particle Swam Optimization) algorithm and the gradient-based perturbation adaptive algorithm, which shows stable nulling performance adaptively even on the moving jammer environment where the incident direction of the interference signal is changing with time.

• The Journal of the Korea Contents Association
• /
• v.19 no.6
• /
• pp.471-480
• /
• 2019

L-spine 3~4, L-spine 4~5, and L-spine 5~Sacrum 1 intervertebral disc(IVD) angle according to gender, age, body mass index(BMI), lumbar lordosis angle(LLA) were compared and analyzed. The anteriorposterior incidence angle of L-spine 3 ~ 4, L-spine 4 ~ 5 and L-spine 5~Sacrum 1 in body mass index were 5.66, 13.23 and 29.13 degrees in the head direction and L-spine 3 4, L-spine 4 ~ 5, L-spine 5~Sacrum 1 had 6.32 degrees, 16.09 degrees and 35.36 degrees in the head direction. The distortion area ratio comparison was performed with the phantom image using the proposed incidence angle. There was a significant difference in L-spine 4~5 and L-spine 5~Sacrum 1 IVD angle relative to body mass index and LLA(p<0.05), IVD angle and LLA were positively correlated(p<0.05).As a result of evaluating the usefulness of the image by applying the incidence angles of the disc angles according to the phantom angle of deviation to the head direction as 11 degrees for L4 and 26 degrees for L5, the distortion ratio area decreased from 14.90% to 12.11% in L4, And from 15.25% to 13.72% in L5. In anteriorposterior image of the Lumbar spine applying the incidence angle according to the measured disc angle, it is possible to reduce the distortion to purpose L4, L5. And improved the quality and diagnostic information of the target site.

• Journal of Navigation and Port Research
• /
• v.37 no.2
• /
• pp.221-229
• /
• 2013

To find the influence of incident angle of wave on the moment of 3 storied steel moment resisting frame which is placed on the concrete rectangular pontoon, the fluid dynamic analysis is carried out, varying the period of wave from 5 to 15 second by 2 seconds. As increasing incident angle of wave to longitudinal axis, the influence of RAO-rolling is increased. The moment of longitudinal frame is increased apparently by the wave pressure when the incident angle is $0^{\circ}$. And the moment of the frame due to the wave pressure is decreased as the incident angle is increased. But the moment of frame due to acceleration caused from pitching and rolling is increased. It is shown that the increased moment when incident angle is $90^{\circ}$ is much greater than that of incident angle $0^{\circ}$.

• Journal of the Korea Society of Computer and Information
• /
• v.15 no.5
• /
• pp.75-81
• /
• 2010

Adaptive array antenna system estimates target signal, as making a null pattern toward the interference signal. However, receiving a coherent interference signal at adaptive array antenna system, as target signal is regarded as interference signal, the performance of system rapidly decreases. The main beam does not direct an incidence direction of target signal due to sensitivity in directivity error. This paper proposes beamforming algorithm which combines high order limit condition and directivity error modify method. And it minimizes degree of freedom and decreases interference signal and directivity error using proposed algorithm. This paper compares and analyzes the performance of proposed algorithm and general algorithm using simulation. In this paper, the proposed algorithm correctly estimates an incident angle, but general algorithm occurs an error of about $0.8^{\circ}$.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2006.05a
• /
• pp.1950-1953
• /
• 2006

본 연구에서는 파랑의 방향에 따른 비대칭성을 고려한 방향 스펙트럼 식을 새로 제안하였다. 심해에서 생성된 다방향 불규칙 파랑이 등수심선에 대해 일정한 각도를 가지고 입사하는 경우, 각 방향의 파랑 성분의 굴절각의 차이에 의해 입사각에 대한 비대칭성이 발생하였다. 파랑의 굴절에 대해서는 Snell의 법칙을 이용하고 천수를 고려하여 해석적으로 계산하였으며, 이 결과와 새로 제안된 방향스펙트럼 식을 이용한 결과를 서로 비교하였다. 그 결과 비대칭성이 강한 천해역에서는 기존의 스펙트럼식에 비해 3배 이상 정확한 값을 재현하였다.