• Korean Journal of Poultry Science
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• v.18 no.3
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• pp.151-159
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• 1991

As a part of investigation on causes of drop in egg production in domestic chicken breeding farm, bacteriological contamination on air, feed, drinking water and artificial insemination instruments of randomly selected three farms was surveyed. Total bacterial population in the air was very high in all of the chicken houses tested and was not significantly different among these farms . However, total bacterial counts in the air of the problem house having egg drop problem and colibacillosis was higher than normal house within the problem farm. Bacterial population in the assorted feed was low before or after administration on the normal farm while it was much more increased after administration than before administration on the problem farm. Bacterial population of the drinking water in the source of water supply was very low and has no differences among farms tested. Also, bacterial population in the normal farm was not significantly different between source of water supply and after administration. However, population of total bacteria and coliform bacteria after administration was increased. Bacterial population was much higher in the artificial insemination instrument of problem farm than normal farm. However, this bacterial population in the problem farm was decreased to those of normal farm after these instruments were sanitized.

• Progress in Medical Physics
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• v.21 no.2
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• pp.145-152
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• 2010

Inveon PET is a recently developed preclinical PET system for small animal. This study was conducted to measure the performance of Inveon PET as recommended by the NEMA NU 4-2008. We measured the spatial resolution, the sensitivity, the scatter fraction and the NECR using a F-18 source. A 3.432 ns coincidence window was used. A $1\;mm^3$ sized F-18 point source was used for the measurement of spatial resolution within an energy window of 350~625 keV. PET acquisition was performed to obtain the spatial resolution from the center to the 5 cm offset toward the edge of the transverse FOV. Sensitivity, scatter fraction, and NECR were measured within an energy window of 350~750 keV. For measuring the sensitivity, a F-18 line source (length: 12.7 cm) was used with concentric 5 aluminum tubes. For the acquisition of the scatter fraction and the NECR, two NEMA scatter phantoms (rat: 50 mm in diameter, 150 mm in length; mouse: 25 mm in diameter, 70 mm in length) were used and the data for 14 half-lives (25.6 hr) was obtained using the F-18 line source (rat: 316 MBq, mouse: 206 MBq). The spatial resolution of the F-18 point source was 1.53, 1.50 and 2.33 mm in the radial, tangential and axial directions, respectively. The volumetric resolution was $5.43\;mm^3$ in the center. The absolute sensitivity was 6.61%. The peak NECR was 486 kcps @121 MBq (rat phantom), and 1056 kcps @128 MBq (mouse phantom). The values of the scatter fraction were 20.59% and 7.93% in the rat and mouse phantoms, respectively. The performances of the Inveon animal PET scanner were measured in this study. This scanner will be useful for animal imaging.

• Korean Journal of Optics and Photonics
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• v.7 no.3
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• pp.191-195
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• 1996

A optical system of a movile LIDAR is designed for air pollution research. After the inverse Cassegrain type collimator, the laser beam falls on the mirror which serve for coinciding optical axis of laser beam and the receiving telescope. Then, it is directed into the atmosphere and back scattered radiation back to the receiving telescope by the scanning mirror. The unit of scanning mirror allows to rotate the mirror along the altitude 0$^{\circ}$~60$^{\circ}$, and the azimuth 0$^{\circ}$~360$^{\circ}$. The scanning mirror is not connected with the receiving telescope but placed on the roof of the mobile. The received beam is spatial filtered by a spatial filter and collimated by a fabric lens. Thereafter, the beam is devided into 2 channel for registration by a beam splitter. Each laser beam is transformed into an electrical signal by means of the photomultifier and then processed to be analyzed.

• Journal of the Korean Vacuum Society
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• v.7 no.3
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• pp.237-241
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• 1998

The growth orientation and the surface roughness of AIN/Si(111) films grown by radio frequency (RF) reactive magnetron sputtering were investigated using in-situ x-ray scattering technique and atomic force microscopy (AFM). AIN films were initially grown with the <001> preferred growth orientation under most growth conditions. As the film gets thicker, however, the growth orientation changes significantly, especially at high substrate temperature and high RF powers. We attribute the observed behavior to the competition between the surface energy that prefers the <001> growth orientation and the strain energy that randomizes the growth orientation. In addition, we investigated the evolution of the surface morphology during the growth using the x-ray reflectivity measurement.

• The Korean Journal of Malacology
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• v.2 no.1
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• pp.10-12
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• 1986

Pettancylus nipponicus (freshwater limpet) collected from the Lake Choon Cheon were cultrued in aquarium and studied in the respects of an egg deposition and the developmental characters of cleavage. The species were collected only in the Lake Uiam and Choon Cheon and easily sampled on the debris like vinyls and cans. Those smooth surfaces were suitalble substrata for attaching. P. nipponicus, about 4 mm in adult, deposited an egg in one calcareous egg-capsule on the aquarium walls, while many eggs are surrounded in a jelly-like egg-envelope in the most gastropods. And another special features was that an egg-capsule was consisted of two valves and the suture was opended as hatching. A diameter of its egg was $55{{\mu}m}$ and the length of an egg capsule was $620{{\mu}m}$ and $510{{\mu}m}$ in long and short diameter, respectively. It took about 8 hours from beginning cleavage to 16-cell stage and about one year to become an adult.

• Korean Journal of Environmental Biology
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• v.22 no.1
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• pp.159-166
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• 2004

The effects of polychlorinated biphenyls (PCBs) on the reproduction of the oily bitterling, Acheilognathus koreensis were investigated using histological methods. The experimental fishes were exposed to 0. 3.4, 9.3 and 25.8 ${\mu}g\; L^{-1}$ PCBs fey 8 weeks. Dead fishes and abnormal behavior were not observed in control and PCBs exposure group. In compared with control group, PCBs exposure fishes showed differences of gonadal development, gonadosomatic index (GSI), hepatosomatic index (BSI), nuptial color index (NCI) and ovipositor length index (OLI). These results showed that PCBs could disrupt reproductive process in the fish.

• Journal of radiological science and technology
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• v.5 no.1
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• pp.15-19
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• 1982

Authors made an experiment to know the relation of surface doses and multiple factors of exposure by using grids, fields, tube voltages objects and distances and obtained the results as follows: 1. Surface doses were increased in proportion to the thickness of objects. 2. Surface doses were more influenced when irradiated fields were small and tube voltages were low. 3. Surface doses were a logarthmic proportion to the focus-object distance. 4. Multiple factors of exposure by using grid were under the control of the thickness of objects, irradiated fields and tube voltages but the relation of them were not fixed.

• Journal of radiological science and technology
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• v.8 no.2
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• pp.15-19
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• 1985

The seattered-ray have a bad effect to the image of x-ray film. Therefore, to obtain the better x-ray image, the most important point is to eliminate the scattered-ray, come from the patient, and the easiest method to eliminate the scattered-ray is to use a proper grid for tube voltages. Authors made an experiment on the scattered-ray contents and the image quality in skull radiography, and obtained the results as follows; 1. The scattered-ray content in skull radiography was 83%, but it could be reduced to 35%-50% by using grid. 2. The image contrast was most increased when the using grid ratio was 8:1. 3. The image quality was not influenced by the scattered-ray contents between 32% and 45%.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.361-361
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• 2011

하나로 냉중성자원(CNS: Cold Neutron Source)은 원자로 수조내 반사체 탱크에 위치한 수직 조사공에 설치되어 하나로 노심에서 발생하는 열중성자를 감속재인 액체 수소층을 통과시켜 냉중성자를 생산한다. 생성된 냉중성자는 유도관을 통하여 냉중성자 산란장치에 공급되어 이용 연구에 활용된다. 감속재로 사용되는 수소는 헬륨냉동계통의 운전에 따라 수소가 수조내기기 집합체(IPA: In Pool Assembly) 내로 이동되어 액화되어지므로, 극저온의 헬륨가스의 흐름이 중요하다. 헬륨냉동기에 의해 만들어진 극저온인 헬륨은 IPA 내의 수소와 열교환을 하기 위해서 배관을 통해 이동되며, 열손실없이 전달하기 위하여 헬륨 배관은 진공층이 형성된 이중배관으로 설계되어 있다. 헬륨 이중배관은 공급 및 회수 배관으로 구성되어 있으며, 헬륨 배관의 외관에 진공층을 20개의 구간으로 나누어 제작 및 설치되었으며, 각각의 진공도를 유지하고 있다. 이 논문에서는 하나로 냉중성자원 헬륨 이중배관의 특성과 헬륨냉동계통의 운전 및 정지시 온도 변화에 따른 이중배관 진공도의 변화를 분석하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.6 s.121
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• pp.664-673
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• 2007

In this paper, the ID-FDTD scheme, proposed in Reference [1] and [2], is modified and completely analyzed. The modifications are composed of three parts: rigorous stability analysis, dispersion relation for linear lossy media, and new scaling factors for permittivity, permeability, and conductivity. As a result, it is shown that the proposed scheme has lower dispersion error in spite of larger time step than the conventional standard scheme of Reference [3]. To validate the scheme, there are presented two scattering examples, which show excellent results.