• Journal of Korean Ophthalmic Optics Society
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• v.10 no.4
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• pp.347-355
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• 2005

We investigate the distribution of central spot and the encircled energy in order to assess the performance of central obstructed optical system having central obstruction, when the central obstruction and the degree of truncated Gaussian amplitude of incident beam change. When the radius of central obstruction increases the radius of central spot on the image plane decreases, and when the degree of truncated Gaussian amplitude of incident beam increases the radius of central spot on the image plane increases. As the central obstruction and the degree of truncated Gaussian amplitude of incident beam increase, the depth of focus increases and the encircled energy of central spot decreases. We know from theses results that the effect of Gaussian factor is small as the central obstruction increases. These results was applied to develope the large optical reflection system.

• Composites Research
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• v.24 no.6
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• pp.25-30
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• 2011

This paper presents an experimental study on the enhancement of electromagnetic shielding (EMI) properties of glass fiber, carbon fiber, and glass-carbon fiber composites by adding layers of multi-walled carbon nanotubes (MWCNTs). In the case of glass-fiber composites, spraying 0.1~0.2 g of MWCNT over a fiber area of $200mm{\times}200mm$ (1.8~3.6 ${\mu}m$ in thickness) resulted in significant improvement in EMI shielding effectiveness (SE). Also, when applying multiple MWCNT layers, it was more effective to place the layers concentrated near the center of the composite rather than spreading them out. On the contrary, inherently conductive carbon fiber and glass-carbon fiber composites did not show appreciable improvement with the addition of MWCNT layers. In order to maximize the effectiveness of carbon nanomaterials as EMI shielding fillers, it is imperative to understand the effect of these materials on various EMI shielding mechanisms and their interactions.

• Journal of the Korean Society of Radiology
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• v.15 no.7
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• pp.949-956
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• 2021

The purpose of this paper is to evaluate whether tungsten nanoparticles have a shielding effect on scattered light generated at high doses as an alternative material to lead used to shield scattered light in electron beam therapy. A plate was manufactured to set the position of the dosimeter and the size of the radiation field to be constant. The glass dosimeter was placed at 12 points, which were 1, 2, and 4 cm apart from the center of the field of 10 × 10 cm² in the cross direction. A total of 12 types of tungsten nanoparticle shields were developed with a thickness of 0.75 mm to 4.00 mm and a size of 10 × 10 cm² using 0.4, 0.75, and 1 mm materials. Using a linear accelerator, measurements were made four times at 6 MeV and four times at 12 MeV, and the dose intensity was investigated at 100 MU. The 4 mm shielding plate showed the highest shielding effect at 1 cm from the irradiation field. The 1 mm shielding plate at 2 cm from the irradiation field had the lowest shielding effect. As the thickness of the tungsten shielding plate increased, the electron beam's shielding effect increased sharply. It was confirmed that tungsten nanoparticles can reduce the amount of scattered light generated by electron beam therapy. Therefore, this study will provide basic data when follow-up studies are conducted on the shielding ability of tungsten nanoparticles.

• Proceedings of the Korea Contents Association Conference
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• 2011.05a
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• pp.191-192
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• 2011

X선 촬영을 통한 집단 건강검진은 경제성, 신속성, 대량처리 능력을 충족시키고 있으며 찾아가는 이동 의료서비스에서 중요한 부분을 차지하고 있다. 이와 함께 X선 촬영을 통한 집단 건강검진 시스템도 발전하여 간접촬영방식에서 Digital Radiography를 이용한 직접촬영방식으로 기술력이 향상되었고 이로써 검진차량에서 검진을 받는 환자나 종사자들에 대한 피폭선량의 증가하고 있으나 차량 외부의 누설방사선량에 대한 조사는 아직도 미미하다 할 수 있다[1]. 이에 본 연구에서 실험을 통한 결과는 다음과 같이 나타났다. 누설방사설량이 가장 많이 발생하는 곳은 출입문과 후면(검출기)에서는 우측, 양측면에서는 중앙이 가장 많은 누설방사선량이 나타났고, 측정위치별로는 검출기가 인접한 후면에서 누설방사선량이 가장 높았다. 기준치에 크게 벗어나지는 않았지만 누설방사선량은 다양하게 나타났다. 특히 후면에서의 누설방사선량은 기준치를 크게 웃돌아 방사선 차폐시설이 잘 갖추어지지 않은 것을 알 수 있으며 향후 이동검진차량의 방사선 차폐시설을 갖추는데 있어 각별한 관심이 필요하리라 사료된다.

• Radiation Oncology Journal
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• v.14 no.1
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• pp.41-52
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• 1996

Purpose : This paper reports a dosimetric study of 88 patients treated with a combination of external radiotherapy and high dose rate ICR for FIGO stage IIB carcinoma of the cervix. The purpose is to investigate the correlation between the radiation doses to the rectum, external radiation dose to the whole pelvis, ICR reference volume, TDF BED and the incidence of late rectal complications, retrospectively. Materials and Methods : From November 1989 through December 1992, 88 patients with stage IIB cervical carcinoma received radical radiotherapy at Department of Radiation Oncology in Yonsei University Hospital. Radiotherapy consisted of 44-54 Gy(median 49 Gy) external beam irradiation plus high dose rate intracavitary brachytherapy with 5 Gy per fraction twice a week to a total dose of 30 Gy on point A. The maximum dose to the rectum by contrast(r, R) and reference rectal dose by ICRU 38(dr, DR) were calculated. The ICR reference volume was calculated by Gamma Dot 3.11 HDR planning system, retrospectively The time-dose factor(TDF) and the biologically effective dose (BED) were calculated. Results : Twenty seven($30.7\%$) of the 88 patients developed late rectal complications:12 patients($13.6\%$) for grade 1, 12 patients($13.6\%$) for grade 2 and 3 patients($3.4\%$) for grade 3. We found a significant correlation between the external whole pelvis irradiation dose and grade 2, 3 rectal complication. The mean dose to the whole pelvis for the group of patients with grade 2, 3 complication was Higher, $4093.3\pm453.1$ cGy, than that for the patients without complication, $3873.8\pm415.6$ (0.05$7163.0\pm838.5$ cGy, than that for the Patients without rectal complication, $0772.7\pm884.0$ (p<0.05). There was no correlation of the rate of grade 2, 3 rectal complication with the iCR rectal doses(r, dr), ICR reference volume, TDF and BED. Conclusion : This investigation has revealed a significant correlation between the dose calculated at the rectal dose by ICRU 38(DR) or the most anterior rectal dose by contrast(R) dose to the whole pelvis and the incidence of grade 2, 3 late rectal complications in patients with stage IIB cervical cancer undergoing external beam radiotherapy and HOR ICR. Thus these rectal reference points doses and whole pelvis dose appear to be useful Prognostic indicators of late rectal complication in high dose rate ICR treatment in cervical carcinoma.

• Journal of the Korean Institute of Landscape Architecture
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• v.47 no.6
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• pp.67-77
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• 2019

The purpose of this study is to analyze how much particulate matter at the center of the urban park is reduced compared to the entrance of the park, where the particulate matter problem is serious. It also endeavored to analyze the relationship between the space closure rate and particulate matter reduction rate in the center of the park through the collection and analysis of experimental data. Seven flat land type urban neighborhood parks in Suseong-gu, Daegu were measured at the same place for three days. The research results are as follows. First, the center of the urban neighborhood park had an average temperature 1.05℃ lower than at the entrance and an average humidity of 2.57% higher. Second, the rate of fine dust reduction was PM1- 17.09%, PM2.5- 17.65%, PM10- 14.99%. As for the reduction rate of particulate matter, the smaller the size of the park, the greater the reduction rate. In addition, the reduction rate at the center of the park was lower on days when particulate matter concentration based on the weather reports was low. The higher the concentration at the park entrance, the higher the reduction rate was. Third, a higher the rate of space closures at the center of the park resulted in a higher effect of particulate matter reduction. Noting this, the relationship between particulate matter reduction and the space closure rate in urban neighborhood parks was clearly shown. We hope to be the basis for more extensive experimental data collection.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.67.2-67.2
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• 2011

Schwarzschild-Chang 망원경은 두 개의 반사경을 사용한 비축 망원경이다. 이 망원경에 사용된 비축 광학 이론을 이용하면 선형 비점수차를 완전히 제거할 수 있으며 3차 이상의 고차수차들도 동축 광학계와 동일한 정도로 최소화 시킬 수 있다. 이 망원경 디자인을 응용하면 단일 광학계 망원경을 제작할 수 있을뿐만 아니라 2개의 망원경 시스템을 조합할 경우 색수차나 중앙차폐 없이 대형 망원경의 focal reducer 또는 분광기의 내부 광학 장치로도 사용할 수 있다. 본 연구팀은 현재 구경 50 mm, 유효초점거리 100 mm, 시야각 $8{\times}8^{\circ}$ 인 Schwarzschild-Chang 망원경 시험 모델을 완성했다. 본 발표에서는 적외선 관측을 직접 할 수 있는 Schwarzschild-Chang 망원경의 개발 진행과정에 대하여 설명한다.

• Cement
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• s.59
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• pp.26-38
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• 1975

본고는 일본 소야전Cement Co.의 중앙연구소주임연구원으로 있는 Hiroshi Uckikawa 박사가 일본의 Ceramics-Japan지(''74.10)에 기고한 것을 번역한 것으로서 그 내용에 의한 목차는 다음과 같다. 즉 근년에 개발된 새로운 cement로서는 1. 속경성 cement 2) 초속경 cement(jet cement, regulated set cement) 2) Alumina cement 3) 초조강 cement 4) 급경 cement 2. 고강도 cement 3. 내구성 cement 1) 내유산균 cement 2) 내화 cement (1) alumina cement 계 (2) barium, strontium 계 cement (3) 인산 aluminium 계 cement 3) 방사선차폐용 cement 4. 팽창 cement 1) alumine 산, 유산 calcium 수화물의 생성에 의한 것 2) 수산화 calcium의 생성에 의한 것 3) 기타 5. 시공성을 개선한 cement (예: 유정용 cement, 도장용 cement) 등이 있다. 머지 않아 우리나라에서도 cement 품종의 다양화가 필연적인 문제로 대두될 것을 생각하여 본번역문이 다소나마 도움이 되기를 바란다.

• Analytical Science and Technology
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• v.20 no.4
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• pp.323-330
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• 2007

A simple and rapid HPLC method with fluorescence detection(FLD) for quantitation of penciclovir in human plasma using a monolithic column was developed and validated. Penciclovir and ganciclovir(internal standard, I.S.) were separated on a Chromolith column RP-18e ($4.6{\times}100mm$) with a mobile phase consisting of a mixture of (A) methanol/50 mM sodium phosphate buffer containing 200 mg/L sodium dodecyl sulfate (3/97, pH 2.5) and (B) methanol/50 mM sodium phosphate buffer containing 200 mg/L sodium dodecyl sulfate (50/50, pH 2.5) at a flow gradient of $1.6{\sim}4.0mL/min$. The retention times of penciclovir and internal standard were less than 4.0 min. Calibration curve was linear ($R^2=0.9994$) over a concentration range of $0.1{\sim}5{\mu}g/mL$. Intra-day precision, accuracy and inter-day precision were 1.36~8.55 %, 92.8~100.0 % and 0.93~5.62 %, respectively with a limit of quantitation at $0.1{\mu}g/mL$. The present HPLC-FLD method is sensitive, precise and accurate. The method described herein has been successfully used for the bioequivalence study of a famciclovir formulation product after oral administration to healthy Korean volunteers.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.2
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• pp.159-165
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• 2010

Purpose: Positron emission tomography scan has been growing diagnostic equipment in the development of medical imaging system. Compare to $^{99m}Tc$ emitting 140 keV, Positron emission radionuclide emits 511 keV gamma rays. Because of this high energy, it needs to reduce radioactive emitting from patients for radiotechnologist. We searched the external dose rates by changing distance from patients and measure the external dose rates when we used shielder investigate change external dose rates. In this study, the external dose distribution were analyzed in order to help managing radiation protection of radiotechnologists. Materials and Methods: Ten patients were searched (mean age: $47.7{\pm}6.6$, mean height: $165.5{\pm}3.8$ cm and mean weight: $65.9{\pm}1.4$ kg). Radiation were measured on the location of head, chest, abdomen, knees and toes at the distance of 10, 50, 100, 150 and 200 cm. Then, all the procedure was given with a portable radiation shielding on the location of head, chest and abdomen at the distance of 100, 150 and 200 cm and transmittance was calculated. Results: In 10 cm, head (105.40 ${\mu}Sv/h$) was the highest and foot (15.85 ${\mu}Sv/h$) was the lowest. In 200 cm, head, chest and abdomen showed similar. On head, the measured dose rates were 9.56 ${\mu}Sv/h$, 5.23 ${\mu}Sv/h$, and 3.40 ${\mu}Sv/h$ in 100, 150 and 200 cm respectively. When using shielder, it shows 2.24 ${\mu}Sv/h$, 1.67 ${\mu}Sv/h$, and 1.27 ${\mu}Sv/h$ in 100, 150 and 200 cm on head. On chest, the measured dose rates were 8.54 ${\mu}Sv/h$, 4.90 ${\mu}Sv/h$, 3.44 ${\mu}Sv/h$ in 100, 150 and 200 cm, respectively. When using shielder, it shows 2.27 ${\mu}Sv/h$, 1.34 ${\mu}Sv/h$, and 1.13 ${\mu}Sv/h$ in 100, 150 and 200 cm on chest. On abdomen, the measured dose rates were 9.83 ${\mu}Sv/h$, 5.15 ${\mu}Sv/h$ and 3.18 ${\mu}Sv/h$ in 100, 150 and 200cm respectively. When using shielder, it shows 2.60 ${\mu}Sv/h$, 1.75 ${\mu}Sv/h$ and 1.23 ${\mu}Sv/h$ in 100, 150 and 200 cm on abdomen. Transmittance was increased as the distance was expanded. Conclusion: As the distance was further, the radiation dose were reduced. When using shielder, the dose were reduced as one-forth of without shielder. The Radio technologists are exposed of radioactivity and there were limitations on reducing the distance with Therefore, the proper shielding will be able to decrease radiation dose to the radiotechnologists.