• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.240-247
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• 2010

The soil nailing system is becoming common as reinforcement method of slope face in soil. It has application to obtain slope stability method and scaffolding system. It has some troubles when the soil nailing system is applied to the downtown because it could be invaded someone's private area. Thus, in this paper, wedge type removable soil nailing system which can easily remove deformed bar in final excavation step is developed. Field pull-out test is performed to evaluate deformed bars removal and pullout resistance characteristics. According to this result, application of Wedge Type Removable Soil Nailing System is performed.

• Restorative Dentistry and Endodontics
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• 제33권2호
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• pp.107-114
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• 2008

본 실험에서는 다양한 방사선 노출 조건에 따른 aluminum step wedge에 대한 광학 밀도를 알아보고, 그 중 적절한 노출조건을 선택하여 수종의 근관 충전재와 치근단 역충전재의 방사선 불투과성 정도를 평가, 비교하였다. 방사선 불투과성의 기준을 위해 11개의 step으로 구성된 aluminum step wedge를 제작하여, 60 kVp, 70 kVp 관전압 상태에서 각각 0.2, 0.,3, 0.4초와 0.2, 0.3, 0.33초의 노출시간으로 교합 필름상에서 방사선 촬영 후 적절한 노출조건을 구하였다. 직경 5 mm, 각각의 두께 0.5, 1.0, 1.5, 2.0, 2.5, 3.0 mm인 10종 (Gutta-percha, amalgam, Super $EBA^{(R)}$, MTA, $IRM^{(R)}$, Fuji II LC, $Dyract^{(R)}$ AP AH, $26^{(R)}$, $Sealapex^{TM}$, Tubli-$Seal^{TM}$)의 근관 충전재와 치근단 역충전재 시편을 각 재료와 두께당 10개씩 제작한 후, 동일한 두께의 상아질 시편, aluminum step wedge와 함께 정해진 노출조건에 따라 방사선 촬영을 하였다. 모든 필름은 자동현상기로 현상하였다. 시편의 흑화도를 densitometer (Model 07-443, Victoreen Inc, Cleveland, Ohio, USA)로 5회 반복 측정 후, 평균값을 구하여 회귀분석 후 알루미늄 두께로 환산하였다. 얻어진 정보를 분석하여 다음의 결과를 얻었다. 1. 관전압 60 kVp에서 노출시간 0.2, 0.3, 0.4초, 70 kVp에서 0.2, 0.3. 0.33초로 변화를 주어 방사선 촬영을 하였을 때, 흑화도가 0.5-2.5 사이여야 한다는 ISO No. 6876 규격에 가장 적합한 것은 60 kVp, 0.2초일 경우였다. 2. 측정된 근관 충전재와 치근단 역충전재들의 방사선 불투과성 모두 ISO No.4049 규격에 적합하였다. 3. 광중합형 글래스 아이오노머 (Fuji II LC)와 컴포머 (Dyract)를 제외하고는 ANSI/ADA specification (2000) 또는 ISO No. 6876 (2001)규격이 제시한 최소한 3 mm Al 이상의 방사선 불투과성을 지녀야 한다는 규격에 적합하였다. 이상의 결과는 본 실험에 사용된 수종의 근관 충전재와 치근단 역충전재 중 Fuji II LC와 Dyract를 제외하고 모두 규격에 적합한 방사선 불투과성을 가지고 있음을 시사한다.

• Imaging Science in Dentistry
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• 제31권1호
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• pp.17-22
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• 2001

Purpose: To compare the film density of Insight dental X-ray film (Eastman Kodak Co., Rochester, NY, USA) with that of Ektaspeed Plus film (Eastman Kodak) under manual and automatic processing conditions. Materials and Methods : Insight and Ektaspeed Plus films were exposed at three different exposure conditions with an aluminum step wedge on the films under the three different exposure times. The exposed films were processed by both manual and automatic ways. The Base plus fog density and the optical density made by exposing step wedge were calculated using a digital densitometer (model 07-443, Victoreen Inc, Cleveland, Ohio, USA). The optical densities of the Insight and Ektaspeed film versus thickness of alumimun wedge at the same exposure time were plotted on the graphs. Statistical analyses were applied for comparing the optical densities of the two films. Results: The film density of both Insight films and Ektaspeed Plus films under automatic processing condition was significantly higher over the manual processing. The film density of Insight films was significantly higher than that of Ektaspeed Plus films on both automatic and manual processing conditions. Conclusion: The radiation exposure time can be reduced when using Insight over Ektaspeed Plus film. To take the full advantage of reducing exposure time, Insight film should be processed automatically.

• 치과방사선
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• 제22권2호
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• pp.293-303
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• 1992

Generally the patient's absorb dose and readability of radiograms are affected by the exposure time and kVp of which are related with the radiographic density and contrast The investigator carried studies to know the adequate level of exposure time and kVp to obtain the better readability of radiograms. In these studies dried human mandible with selfcuring acrylic resins attached with aluminum step wedge was used and readability of radiograms were compared with each other by videodensitometry among various combination sets of the exposure time, such as 5, 6, 8, 12, 15, 19, 24, 30, 38, 48 and 60, and varing level of kVp, such as 60, 65, 70, 80 and 90 respectively. The obtained results were as follows: 1. As exposure time and kVp were increased, radiographic density of radiograms was increased. 2. The subject contrast was increased where aluminum step wedge was thin and reduced in the reversed condition. At the thin aluminum step wedge, subject contrast was increased at the condition of lower kilovoltage than that of higher kilovoltage. 3. In the case of non-constant radiographic density, the radiographic contrast was reduced with the increment kilovoltage. The radiographic contrast was increased in the lower kilovoltage with the longer exposure time and the higher kilovoltage with the shorter exposure time. 4. At the condition of short exposure time, better readability of each reading item was obtained with the increment of the kilovoltage but at the opposite condition increasing exposure time worsened readability of radiograms. Since X-ray machine in the current dental clinics is fixed between the range of 60-70kVp and 10mA, good radiograms can be obtained by varied exposure time. But according to the conclusion of these studies, better radiograms can be obtained by using filtered high kVp and then the absorb dose to patient and exposure time can be reduced.

• 대한디지털의료영상학회논문지
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• 제10권1호
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• pp.35-40
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• 2008

I.objective The composition method with acquiring 2${\sim}$5 image not only lack perfection in compensating the geometrical distortion but could also cause inaccurate connection problem of compensating the geometrical distortion but could also cause inaccurate connection problem of continuing bone structure due to the enlargement ratio difference of ruller and bone, density difference in image composition process. This paper studies those mentioned problems through the experiments. II. Object and method Experiment 1 After attaching 3 step wedge(Pb) on detector and 2 ruller on upper, lower part of the step wedge, we have exposed them to create density difference between 1st image and 2nd image, then examined if there were any errors. Experiment 2 1st 100cm ruller was attached on the center of detector, and by escalating the distance between 2nd 100cm ruller and detector 5cm, 10cm, 15cm respectively, we investigated if there any errors caused by enlargement ratio. Experiment 3 The ruller was placed on detector, a joint photographing was performed through spot photographing after fully operating the electric field photographing to include hip joint ${\sim}$ ankle joint part and we have compared the values from two methods. III. Result : A horizontal axis error was caused when photopraphing is not poerated in equal density since the image shifted horizontally in accordance with the difference of Pb step wedge 1 due to the density difference, as the result of Epperiment 1.

• Restorative Dentistry and Endodontics
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• 제18권1호
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• pp.133-143
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• 1993

The aim of this study was to establish reproducible method for measurements of radiopacity and to investigate the level of radiopacity of root canal sealers. The experiments were performed in two parts. In the first part, densitometric readings were performed using an aluminum step wedge as a reference at variable voltages and exposure times. Then standard curves for the aluminum step wedge were compared to comprehend the effect of voltage and exposure time. In the second part, on the basis of these results, appropriate conditions for exposure were adopted for standardized measurements of radiopacity. Under standardized set of conditions, densitometric measurements of ten root canal sealers and one gutta-percha point were performed and the levels of radiopacity referable to an equivalent thickness of aluminum were compared. The following results were obtained : 1. At 50 and 60 kVp, increasing the exposure time caused a decrease in the slope of the standard curve for the aluminum step wedge. However, at 70 kVp increasing the exposure time causing a parallel shift of the standard curve to the right. 2. At constant exposure time, increasing the voltage caused a decrease in the slope of the standard curve. 3. The radiopacity of root canal sealers and a gutta-percha point varied between 2.43 mm Al and 9.20 mm Al equivalent. 4. All the root canal sealers had radiopacities more than dentin, and the radiopacity of the gutta-percha point was approximately 5 times as much as that of dentin in terms of equivalent thickness of aluminum. 5. The AH26 had radiopacity more than the gutta-percha point, and the radiopacities of ZOE, Vitapex, Canals, Kerr PCS, Nogenol were similar to that of the gutta-percha point, and Tubliseal, Apatite II, Apatite III, Silapex were less radiopaque than the gutta-percha point.

• 치과방사선
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• 제29권1호
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• pp.283-297
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• 1999

Purpose: To compare radiographic images of Digora/sup (R)/ system and Ektaspeed Plus film obtained from normal adults. Materials and methods: Storage phosphor plate(SPP) was placed in a film holder behind Ektaspeed Plus film package without lead foil. The effect of film on SPP was studied in a separate in vitro experiment. Forty-seven sets of images were prepared for the evaluaton. The regions of interest(ROI) for evaluation were designated at seven sites including normal anatomical structures. The image quality for each ROI was evaluated on enhanced and unenhanced storage phosphor(SP) images and Ektaspeed Plus film. Results: Two film-SPP configurations showed significantly different gray levels at each step of the aluminum step wedge(p<0.05). The contrasts were comparable. Enhanced SP images were significantly superior to unenhaned images and film in all anatomical sturctures(p<0.01). The differences between unenhanced SP images and film were significant(p<0.05) except root canal and cortical bone on alveolar crest. For anatomical items. there were statistically significant difference among five observers(p<0.05). Conclusions: The image quality of enhanced SP images were superior to Ektaspeed Plus film. and Digora system is potentially applicable to clinical diagnosis.

• Restorative Dentistry and Endodontics
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• 제34권1호
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• pp.61-68
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• 2009

다양한 근관전색제는 방사선 사진상 주위 해부학적 구조와 구별될 만한 방사선 불투과성을 나타내야 한다. 따라서 이런 물질들이 근관에 충전될 때의 방사선 불투과성 정도를 평가해야 할 필요성이 대두되고 있다. 본 실험에서는 다양한 근관전색제들의 방사선 불투과성을 평가하고자, 방사선 노출조건에 따른 aluminium step wedge에 대한 광학 밀도를 알아보고, 그 중 적절한 노출조건을 선택하여 수종의 근관 전색재의 방사선 불투과성 정도를 알루미늄 두께로 환산하여 비교해 보고자 한다. 방사선 불투과성의 기준을 위해 11개의 step으로 구성된 aluminum step wedge을 사용하여, 60kVp, 70kVp 관전압 상태에서 각각 0.2, 0.3, 0.4초 그리고 0.2, 0.3, 0.33초의 노출시간으로 교합필름상에서 방사선 촬영후 적절한 노출 조건을 구하였다. 직경 5 mm, 각각의 두께 0.5, 1.0, 1.5, 2.0, 2.5, 3.0 mm인 10종 (Tubli-$Seal^{TM}$, Kerr pulp Canal $Sealer^{TM}$, $AH26^{(R)}$, $AHplus^{(R)}$, AH plus jet starter $kit^{TM}$, Ad $seal^{TM}$ $Sealapex^{TM}$, Nogenol root canal $sealer^{TM}$, ZOB $seal^{TM}$, $Epiphany^{TM}$)의 근관전색재 시편을 각 재료와 두께당 10개씩 제작한 후, 동일한 두께의 상아질 시편, aluminum step wedge와 함께 정해진 노출시간에 따라 방사선 촬영을 하였다. 모든 필름은 자동현상기로 현상하였다. 시편의 방사선 흑화도를 densitometer로 5회 반복 측정 후, 평균값을 구하여 알루미늄 두께로 환산하였다. 얻어진 정보를 분석하여 다음의 결과를 얻었다. 1. 관전압 60 kVp에서 노출시간 0.2, 0.3, 0.4초, 70 kVp에서 0.2, 0.3, 0.33초로 변화를 주어 방사선 촬영을 하였을 때, 흑화도가 ISO No. 6876 규격에 가장 적합한 것은 60 kVp, 0.2초 일 경우였다. 2. 측정된 근관 전색제의 방사선 불투과성은 2.29 mm Al (NOGENOL)로부터 13.69 mm Al (AH Plus jet)까지 다양하게 나타났으나, 모두 ANSI/ADA specification (2000) 또는 ISO No. 6876 (2001) 규격이 제시한 최소한 3 mm Al이상의 방사선 불투과성을 지녀야 한다는 기준에 적합하였다. 3. 재료의 두께가 증가할수록 방사선 불투과성은 증가하지만, 정비례하지는 않았다. 4. 각 실험재료의 1 mm 두께의 시편에 대한 mm Al값들은 통계적으로 유의한 차이가 있었다. 이상의 결과는 본 실험에 사용된 수종의 근관 전색재는 모든 규격에 적합한 방사선 불투과성을 가지고 있음을 시사한다.

• 소성∙가공
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• 제28권4호
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• pp.212-218
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• 2019

In this study, the first drawing die for the production of coil wedge is redesigned in order to enhance properties such as dimensional accuracy, dimensional uniformity, non-magnetism, and residual stress. The equivalent strain distribution is observed to be asymmetric at certain corners of the product and un-filling of material is also observed at the same location, based on the results of FEM simulation for the current drawing process. Additionally, a relatively huge amount of deformation is concentrated on the surface of the reference product leading to an increase in magnetic component and surface residual stress. After re-designing the cross-section of the first drawing step process conformed to relatively higher amount of reduction ratio, reduction of both surface residual stress and the volume fraction of magnetic component could be achieved for the finally-drawn coil wedge product.

• 한국방사선학회논문지
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• 제16권4호
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• pp.435-442
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• 2022

힐이팩트는 X선관의 양극 측과 음극 측의 강도가 균등하지 않아 X선 영상에 농도 차이를 발생시킨다. 이 연구의 목적은 스텝 웨지를 180도로 회전시킨 다음 거리를 변경하여 힐이팩트에 의한 농도 차이를 평가하는 것이다. 관전압과 관전류를 72 kVp, 10 mAs로 고정시킨 후 스텝 웨지를 이용하여 정방향과 역방향을 촬영하였다. 이때 거리(80 cm ~ 130 cm)는 10 cm 간격으로 촬영을 진행하였고 M6 프로그램을 통해 스텝 웨지의 각 계단별 관심영역을 설정하여 농도값을 측정하였다. 첫 번째로 조사선량 실험을 통해 음극과 양극의 강도 차이를 확인하였다. 또한 거리(80cm에서 130cm으로)를 달리하였을 때 촬영 거리가 멀어질수록 음극과 양극 사이의 농도 차이가 감소하였다. 이는 결론적으로 촬영 거리가 멀어질수록 균일한 농도의 영상을 획득할 수 있다.