• Journal of KSNVE
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• v.8 no.6
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• pp.1172-1180
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• 1998

Elastic wave scattering from an acoustically rigid or soft object is studied and compared with the acoustic wave scattering. The behavior of phases as well as magnitudes of partial waves and their total summation of scattered wave are numerically analyzed and discussed. The effect of mode conversion, which occurs between longitudinal and transversal waves in elastic wave scattering. on the magnitudes and phases of scattered waves is identified.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.3
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• pp.478-484
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• 2003

The electromagnetic wave scattering problems from inhomogeneous material bodies are considered. The formulation is made in terms of mixed potentials for the moment methods (MoM). The surfaces of a three-dimensional inhomogeneous scatterer of arbitrary shape are divide into triangular patches for descretization. Application of the boundary conditions leads to the coupled surface integral equations to be satisfied for the unknown surface equivalent electric and magnetic currents. The radar cross-section (RCS) for some structures is computed and the results are compared with the reported data.

• Korean Journal of Crystallography
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• v.20 no.1
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• pp.1-8
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• 2009

이온산란 분광법(ISS: Ion Scattering Spectroscopy)은 표면 원자의 구조를 러더포드 후방산란법(RBS: Rutherford Backscattering Spectroscopy) 등과 같이 실공간에 대하여 직접 정보를 얻는 방법이다. 그 중에서도 산란각도를 $180^{\circ}$로 고정하여 산란이온 검출기를 설치한 직충돌 이온산란 분광법(ICISS: Impact Collision Ion Scattering Spectroscopy)은 산란된 이온의 궤적이 입사궤도와 거의 동일하기 때문에 산란궤적의 계산이 간단해지고, 최외층 뿐만 아니라 표면에서 수 층 깊이의 원자구조의 해석이 가능하다. 또한 비행시간형(TOF: Time-Of-Flight) 분석기를 채택하여 산란 이온 및 중성원자를 동시에 측정하면 입사 이온의 표면에서의 중성화에 관계 없이 산란 신호를 얻으므로 표면 원자의 결합 특성에 영향 받지 않고 사용할 수 있다. 본고에서는 ICISS의 원리, 장치, 측정방법 등을 소개한 제1편 및 반도체 표면구조, 금속/반도체 계면 등의 해석에 관하여 기술한 제2편에 이어서 세라믹 재료의 표면 원자 구조, 세라믹 박막의 원자 구조, 흡착 기체의 구조, 원소의 편석 등에 관한 연구 사례를 소개하고자 한다.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.134-135
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• 2000

LCD의 전력소모중 약 70%를 차지하는 부분이 백라이트 유닛이다. 전세계적으로 저전력, 고화질, 대면적의 LCD 디스플레이를 개발하기 위한 연구가 활발히 진행중이다. 주로 백라이트 유닛을 구성하는 입사광학계와 도광체 및 프리즘 필름 등을 기존 제작공정 내에서 개선하는 것에 연구 개발의 초점이 맞추어져 있다. 본 연구는 기존의 개선 방법에서 벗어나 도광판의 형태와 산란입자의 크기에 따른 산란정도를 조절하여 기존의 도광판보다 더 나은 산란효율을 얻고자 한다. 이를 위해 투명도와 경도가 우수한 PMMA(polymethyl methacrylate)에 다양한 산란자를 투입하여 도광판을 제작한다. 도광판의 실제 제작 이전에 고효율 도광판속에서의 정확한 산란전산모사를 필수적으로 선행하여야 한다. 따라서 광산란 측정장치를 제작하여 산란자의 종류에 따른 원통형 도광체에서 측정한 산란강도와 산란전산모사에서의 결과를 비교 분석하여 저전력, 고화질, 대면적의 백라이트 유닛을 개발하기 위한 기초 자료로 사용하고자 한다. (중략)

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.10
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• pp.1454-1460
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• 1993

The scattering pattern, due to an E-Polarized wave incident on M circular parallel dielectric cylinders, is computed. The multiply-scattered fields between the cylinders are considered. Modeling of infinite cylindrical scatterer of arbitrary cross sections by a number of circular cylinders is executed. By enforcing the boundary conditions on the surface of each cylinder, an infinite set of equations is obtained. The first order of scattering results from the excitation of each cylinder by only the incident wave. The second order results from the excitation of each cylinder by the first order of scattering from the remaining cylinders, and so no to an infinite order of scattering. Although the resulting equation is of infinite size, proper truncation yields very accurate numerical results.

• Journal of radiological science and technology
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• v.32 no.4
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• pp.393-399
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• 2009

In this study, we measured the dose distribution of scattered ray in X-ray radiography room using an ion chamber and examined the dependency of scattered ray content on the scattered ray source and exposure condition. To study the factors of scattered ray occurrence in the acryl phantom, we measured the change in the scatted ray content according to the X-ray tube voltage (40~140 kV) and the field size ($10{\times}10\;cm^2$, $20{\times}20\;cm^2$, $35{\times}35\;cm^2$). For the $35{\times}35\;cm^2$ field size, the side-scattering rate ranged from 3.1% to 14.5%. The scattered ray contributions of the phantom, collimator, X-ray tube and wall were also measured. The scattered ray contribution of the phantom was higher than 95.4% for the entire tube voltage, and those of the collimator, X-ray tube and wall were 2.6%, 1.3% and 0.7%, respectively.

• Journal of radiological science and technology
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• v.40 no.1
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• pp.71-78
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• 2017

Scattered radiation is inherent phenomenon of x-ray, which occurs to the subject (or patient). Therefore it cannot be avoidable but also interacts as serious noise factor because the only meaningful information on x-ray radiography is primary x-ray photons. The purpose of this study was to quantify scattered radiation for various shooting parameters and to verify the effect of anti-scatter grid. We employed beam stopper method to characterize scatter to primary ratio. To evaluate effect on the projection images calculated contrast to noise ratio of given shooting parameters. From the experiments, we identified the scattered radiation increases in thicker patient and smaller air gap. Moreover, scattered radiation degraded contrast to noise ratio of the projection images. We find out that the anti-scatter grid rejected scattered radiation effectively, however there were not fewer than 100% of scatter to primary ratio in some shooting parameters. The results demonstrate that the scattered radiation was serious problem of medical x-ray system, we confirmed that the scattered radiation was not considerable factor of dig ital radiog raphy.

• The Journal of the Acoustical Society of Korea
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• v.24 no.8
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• pp.441-446
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• 2005

This paper presents the changes of acoustic scattering pattern from a single cylinder and two identical cylinders in both theoretical calculations and experimental measurements. Bi-static scattering pattern by single cylinder and two parallel cylinders (length 2m, radius 30mm) was measured in $5m\times5m\times5m$ water tank using high frequency projector (120 kHz) and hydrophone. The results show similar agreement between experiment and theory. In case of single cylinder scattering. omni-directional pattern was observed in backward but there are fluctuations or target strength in forward. Interference between each cylinder's scattering fields produce fluctuations of target strength in all directions of two cylinders.

• Korean Journal of Ichthyology
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• v.33 no.1
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• pp.15-21
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• 2021

The Nakdong nose loach, Koreocobitis naktongensis is an endangered freshwater fish endemic to Korea. The spawning behaviour of the K. naktongensis was observed after treating Ovaprim in laboratory aquarium from 20~27 April 2010. The behavioral patterns were categorized into three stages of pre-spawning, spawning and post-spawning behaviors. Before spawning K. naktongensis usually repeated taking a rest and swimming. On average, initial spawning activity started 11 to 12 hours later after injection with Ovaprim. During the spawning period, the number of spawning acts ranged from 1 to 18. The spawning ratio of female to male was 1 : 1. The male embraced the back of the female's dorsal fin with his lamina circularis. It looked like a complete circle at that time. After spawning, parental care was not observed. Individuals not participating in spawning have been observed to feed on some of the fertilized eggs.

• Radiation Oncology Journal
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• v.19 no.1
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• pp.74-80
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• 2001

Purpose : Irradiation cones by using backscatter electrons are made for the treatment of superficial small lesions of skin, oral cavity, and rectum where a significant dose gradient and maximum surface dose is desired. Methods and Materials : Backscatter electrons are produced from the primary electron beams from the linear accelerators. The design consists of a cylindrical cone that has a thick circular plate of high atomic number medium (Pb or Cu) attached to the distal end, and the plate can be adjusted the reflected angle. Primary electrons strike the metal plate perpendicularly and produce backscatter electrons that reflect through the lateral hole for treatment. Using film and a parallel plate ion chamber, backscatter electron dose characteristics are measured. Results : The depth dose characteristic of the backscatter electron is very similar to that of the hard x-ray beam that is commonly used for the intracavitary and superficial lesions. The basckscatter electron energy is nearly constant and effectively about 1.5 MeV from the clinical megavoltage beams. The backscatter electron dose rate of $35\~85\;cGy/min$ could be achieved from modern accelerators without any modification. and the depth in water of $50\%$ depth dose from backscatter electron located at 6mm for $45^{\circ}$ angled lead scatter. The beam flatness is dependent on the slit size and the depth of treatment, but is satisfactory to treat small lesions. Conclusions : The measured data for backscatter electron energy, depth dose flatness dose rate and absolute dose indicates that the backscatter electrons are suitable for clinical use.