• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05b
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• pp.164-168
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• 2003

Digital 방사선투과검사 시스템인 1차원 Radiometric scanning system을 개발하여 부식 및 침적물이 있는 배관의 두께평가에 적용하였다. 단일 방사성 동위원소에서 나오는 방사선을 선현으로 접속하여 시험체를 투과시킨 방사선을 BGO 검출기를 사용하여 측정하는 single source - single detector alignment system과 제어 프로그램을 개발하였다. 개발된 시스템의 성능을 GEANT4 프로그램을 사용하여 예측하였다. 그리고, 인공결함을 제작하여 넣은 시편과 두께 변화를 준 시편에 적용하여 실제 성능을 평가하였다. 방사성 동위원소를 이용하여 배관의 부식과 침적물에 의한 두께 변화에 대하여 실시간으로 필름을 사용하지 않고 평가할 수 있음을 확인하였다.

• Journal of the Korean Society of Radiology
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• v.6 no.2
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• pp.99-106
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• 2012

The radioprotective effects of white ginseng and Entomopathogenic Fugi Extract on liver damage induced by X-ray were investigated. To one group of ICR male mice were given white ginseng(150 mg/kg/day for 7days, orally) and Entomopathogenic Fugi (200 mg/kg/day for 7days, orally) before X-ray irradiation. To another group were irradiated by 5 Gy(1.01 Gy/min) dose of X-ray. Contrast group were given with saline(0.1 ml). The levels of reduced(GSH) and oxidized(GSSG) glutathione in liver tissue were measured. The ratio of GSSG/total GSH was significantly decreased in the white ginseng and Entomopathogenic Fugi (200 mg/kg/day)(150 mg/kg/day) groups than irradiation group.

• Journal of Conservation Science
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• v.34 no.6
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• pp.539-548
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• 2018

This study was conducted to evaluate the effects of scattering radiation, which was not considered in the cultural Heritage radiography, by evaluating the relationship between the tube voltage (unit: kVp), film-floor-distance(FFD), and lead screen layout. The density (unit: D) of the test specimens and the scattered radiation increased with the tube voltage. The density of the test specimens showed an average deviation of 1.4 D; it was 0.17 D at 60 kVp, 1.54 D at 160 kVp, and 2.97 D at 220 kVp. The mean density of the scattered radiation was 0.10 D at 60 kVp, 0.40 D at 160 kVp, and 0.46 D at 220 kVp. The density tended to increase when the tube voltage ranged between 60 kVp and 160 kVp, as the FFD distance increased. However, a change in the permeation density was not observed for high voltages(160 kVp-220 kVp). Scattered radiation was observed when FFD was 50 mm, 100 mm, and 200 mm and no lead screen was used and the bottom surface was replaced with the lead screen. No scattered radiation was observed when FFD was 0 mm. The identification rate ranged from 2.08% to 2.67%, according to the FFD, for a 160 kVp tube voltage, and from 2.67% to 3.33% for a 220 kVp tube voltage.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.3
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• pp.490-497
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• 2007

Odontoma is defined as a benign odontogenic tumor containing enamel, dentin as well as cementum and constitued 22% of all odontogenic tumors. Although the lesions are commonly asymptomatic, they may be discovered routine radiographic examination. Odontomas often cause disturbances in the eruption of teeth such as, impaction or delayed eruption, retention of primary teeth, or abnomalities in the position of the teeth such as tipping or displacement of adjacent teeth. Radiologically, odontomas manifest as a dense radiopaque lesion surrounded by a thin radiotransparent halo. However, in some cases, radiopacity was not quite clear and images of the teeth shadowed very tiny odontomas. And at early development stages of odontoma, calcification remains immature and is difficult to diagnose on radiographs. This suggests that when delayed eruption of the teeth is found, periapical radiographs should be taken to clarify whether any small area of radiopaque material exists. This case report shows tiny odontomas involving an impacted tooth and crowding and we remove the tiny odontoma surgically.

• Restorative Dentistry and Endodontics
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• v.35 no.3
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• pp.188-197
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• 2010

The purpose of this study was to compare radiopacity and radiographic discriminability of various FRC-Posts. Six FRC-Posts were investigated ; 1) FRC Postec Plus (Ivoclar Vivadent AG, Schaan, Liechtenstein), 2) Snowlight (Carbotech, Lewis center, OH, USA), 3) Dentin Post (Komet Brasseler, Lamgo, Germany), 4) Rely-X Fiber Post (3M ESPE, St.paul, MN, USA), 5) D.T.-Light Post (BISCO, Schaumburg, IL,USA), 6) Luxapost (DMG, Hamburg, Germany) The radiographs of each post with a reference 1 mm / 2 mm aluminum step-wedge was taken using digital sensor. The optical density were calculated by gray value of $10{\times}10$ pixel and compared in mm Al equivalent at five points. Six maxillary incisors of similar radiopacity were used. Radiographs of posts in Mx. incisors of lingual side of dry mandible were taken. We showed radiographs and asked the questionnaire to 3 radiologists, 3 endodontists, 3 general practitioners. The questionnaire was comprised of choices of the highest, lowest radiopaque individual post and the choices of best discriminable post at apical, coronal area. The following results were obtained. 1. Each post system showed various radiopacity. 2. There was change of discriminability between each post and simulated specimens regardless of examiner. Although each post showed various radiopacity, the difference of radiopacity did not affect on discriminability.

• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.5
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• pp.483-489
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• 2002

The computer simulation has been done for non-insulated and insulated pipes which are vacant or half filled with liquid. The simulation results showed that the density profile on the radiography is continuous and symmetrical around the center of pipe in the case of vacant pipe. On the other hand the density profiles are not symmetrical and depend on geometrical setting for radiography in the case of half filled pipes. Finally, experimental testing on a non-insulated carbon steel pipe with artificial notches of different depth is carried out using Ir-192 and industrial film. Comparing the measured density profile on the radiograph to the calculated one, it has been shown that it is possible to evaluate thickness variation by measuring density profile on a radiograph.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.16 no.1
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• pp.7-17
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• 1986

치성종양은 악구강계 영역의 질환 중 중요한 관심거리가 되어왔으며, 이중 상피성 치성종양에 관한 보고는 많으나, 중배엽성 치성종양에 관한 보고는 많이 이루어지지 않았다. 저자는 1975년부터 1985년까지 서울대학교병원 치과진료부에서 방사선학적, 병리학적으로 중배엽성 치성종양인 치성섬유종, 치성점액종, 백악질형성섬유종으로 진단된 증례들을 토대로 하여 연구, 분석한 결과 다음과 같은 결과를 얻었다. 1. 치성섬유종의 연령분포는 32세에서 72세로 광범위 하였으며, 발생위치는 모두 상악구치부이었고, 단방성이 2증례, 다방성이 1증례이었다. 2. 치성점액종의 연령분포는 40세에서 55세로 비교적 중년층에서 호발했고, 4증례가 상악에, 2증례가 하악에 발생하였다. 6증례 모두 방사선학적으로 다방성 방사선투과성을 보였으며, 경계는 비교적 불분명하였다. 3. 백악질형성섬유종은 주로 ?년에서 중년 성인 사이에 많이 발행하였고 40대에 가장 많은 출현율을 보였다. 남녀비는 약 1:2로 여자에게서 빈발하였다. 19증례중 하악에 15증례, 상악에 4증례가 발생하여, 하악이 호발부위였으며, 상하악 소구치, 대구치 부위에 발생하였다. 방사선학적으로 방사선투과성이 2증례, 혼합성이 12증례, 방사선불투과성이 5증례이었다.

• Radiation Oncology Journal
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• v.4 no.1
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• pp.1-13
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• 1986

In order to clarify the effect of radiation on the mouse jejunal crypt cells by combined administration of administration and radiation and also to evaluate the enhancing effect of adriamycin, the authors performed this study by delivering single irradiation of 1,000 to 1,600 rad to the whole abdomen of mice by cobalt-60 teletherapy unit. In combination with adriyamycin treatment groups, the drug was administered as single dose of 10 mg/kg either 2 hours before or 4 hours after graded single dose,900 to 1,400 rad, of irradiation. The authors studied the quantitative changes of intestinal crypt cells by microcolony survival assay technique and the morphological changes of small intestinal villi by scanning electron microscope in mice following to combined therapy with adriamycin and irradiation, The average number of jejunal crypts per circumference was $130{\pm}16$ in control group. The mean lethal dose(Do) of each irradiation alone and combined therapy groups 2 hours before and 4 hours after irradiation, were 160, 170, and 170 rad in cell survival curves, respectively. The dose effect factor(DEF) of adriamycin in each groups of pre-irradiation and post-irradiation were 1.19 and 1.26, respectively. The conical shaped villi were noted on 1,200 rad in irradiation alone group and 1,000 rad in combined groups. For the proper clinical application we must be careful of the radiation injury to small bowel when the anticancer chemotherapy and radiation therapy to the abdomen and pelvic area are used as combined therapeutic modality.

• Journal of Welding and Joining
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• v.12 no.4
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• pp.35-40
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• 1994

비파괴검사(NDT)란 시험품에 손상을 주지 않고 내.외부에 존재하는 불연속부(결함)을 찾아내는 방법으로 다음과 같이 그 종류를 분류할 수 있다. (1) 표면결함 검출을 위한 비파괴검사 - 육안검사(VT) : 확대경 등에 의한 치수, 형상확인 - 자분탐상검사(MT) : 강자성체에 적용, 표면(하) 결함검출 - 침투탐상검사(PT) : 금속, 비철금속에 적용, 표면개구 결함검출 - 와류탐상검사(ET) : 도체 표층부(봉, 관 등) (2) 내부결함 검출을 위한 비파괴검사 - 방사선 투과검사(RT) : 결함의 종류, 형상의 판별 우수 - 초음파 탐상검사(UT) : 균열 등 면상 결함검출 등 우수 (3) 기타 비파괴검사 - Strain 측정 : 안전성 평가 - 음향방출시험(AET) - 누설시험(LT) - 중성자 방사선시험(NRT) 이상에서 보는 바와 같이 여러 종류의 비파괴검사가 있으나, 그 중에서 용접부에 적용되는 가장 일반적인 검사방법인 방사선 투과검사에 대해 기술하고자 한다.

• Journal of the Korean Society of Radiology
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• v.13 no.4
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• pp.565-572
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• 2019

In this study, shielding analysis of material and thickness of 3D printer filaments was performed for the manufacture of custom shielding by radiation workers during outdoor radiographic test. The shielding was attached to the ICRU Slab Phantom after selecting the voxel source $^{192}Ir$ and $^{75}Se$ through simulation using MCNPX, and the distance between the source and the slab Phantom was set at 100 cm. The 12 shielding materials were divided into 5 mm units up to 200 mm from the absence of shielding materials to evaluate the energy absorbed per unit mass of each shielding material. The results showed that the shielding effect was high in the order of ABS + Tungsten, ABS + Bismuth, PLA + Copper, PLA + Iron from all sources of radiographic test. However, compared to lead, the shielding effect was somewhat lower. Based on this study in the future, further study of the atomic number and the high density filament material is necessary.