• Imaging Science in Dentistry
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• 제53권3호
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• pp.217-220
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• 2023

Purpose: This pilot study was conducted to evaluate half-value layer (HVL) measurements obtained using a semiconductor dosimeter for intraoral radiography. Materials and Methods: This study included 8 aluminum plates, 4 of which were low-purity (less than 99.9%) and 4 high-purity (greater than 99.9%). Intraoral radiography was performed using an intraoral X-ray unit in accordance with the dental protocol at the authors' affiliated hospital: tube voltage, 60 kVp and 70 kVp; tube current, 7 mA; and exposure time, 0.10 s. The accuracy of HVL measurements for intraoral radiography was assessed using a semiconductor dosimeter. A simple regression analysis was performed to compare the aluminum plate thickness and HVL in relation to the tube voltage (60 kVp and 70 kVp) and aluminum purity (low and high). Results: For the low-purity aluminum plates, the HVL at 60 kVp (Y) and 70 kVp (Y) was significantly correlated with the thickness of the aluminum plate (X), with Y=1.708+0.415X (r=0.999, P<0.05) and Y=1.980+0.484X (r=0.999, P<0.05), respectively. Similarly, for the high-purity aluminum plates, the HVL at 60 kVp (Y) and 70 kVp (Y) was significantly correlated with the plate thickness(X), with Y=1.696+0.454X (r=0.999, P<0.05) and Y=1.968+0.515X (r=0.998, P<0.05), respectively. Conclusion: This pilot study examined the relationship between aluminum plate thickness and HVL measurements using a semiconductor dosimeter for intraoral radiography. Semiconductor dosimeters may prove useful in HVL measurement for purposes such as quality assurance in dental X-ray imaging.

• 한국전자현미경학회:학술대회논문집
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• 한국현미경학회 2000년도 제31차 춘계학술대회
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• pp.63-64
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• 2000

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.939-942
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• 2008

Moir$\acute{e}$s are a natural interference phenomenon which occurs whenever a transparent regular pattern plate is overlapped on another regular pattern plate. In the contact-type 3 dimensional imaging systems, the moires are inherent because an image display panel is seen through a viewing zone forming optical plate. The mathematical analysis of moires in the systems shows that they can be minimized by the proper selection of overlapping angles between them. The angle is different for pixels with different aspect ratios.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 추계학술대회 논문집
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• pp.715-722
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• 2012

A structural health monitoring (SHM) technique for locating impact position in a composite plate is presented in this paper. The technique employs a single sensor and spatial focusing properties of time reversal (TR) and inverse filtering (IF). We first examine the focusing effect of back-propagated signal at the impact position and its surroundings through simulation. Impact experiments are then carried out and the localization images are found using the TR and IF signal processing, respectively. Both techniques provide accurate impact location results. Compared to existing techniques for locating impact or acoustic emission source, the proposed methods have the benefits of using a single sensor and not requiring knowledge of material properties and geometry of structures. Furthermore, it does not depend on a particular mode of dispersive Lamb waves that is frequently used in the SHM of plate-like structures.

• 비파괴검사학회지
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• 제34권6호
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• pp.435-440
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• 2014

Contact-guided-wave tests are impractical for investigating specimens with limited accessibility and rough surfaces or complex geometric features. A non-contact setup with a laser-ultrasonic transmitter and receiver is quite attractive for guided-wave inspection. In the present work, we developed a non-contact guided-wave tomography technique using the laser-ultrasonic technique in a plate. A method for Lamb-wave generation and detection in an aluminum plate with a pulsed laser-ultrasonic transmitter and Michelson-interferometer receiver was developed. The defect shape and area in the images obtained using laser scanning, showed good agreement with the actual defect. The proposed approach can be used as a non-contact online inspection and monitoring technique.

• Journal of Pharmaceutical Investigation
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• 제39권1호
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• pp.1-6
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• 2009

To overcome the stability problem of hydrophilic quantum dot (Q-dot), cellular uptake of hydrophobic instead of hydrophilic Q-dot was studied in the hope to find a simple method to use Q-dot as a cellular imaging probe. Hydrophobic Q-dot and poly-L-lactic acid (PLLA) were co-dissolved in chloroform to prepare stable films. Due to the cellular compatibility of PLLA, adherent cells were cultured on the film to observe the degree of Q-dot uptake and cytotoxicity of the prepared films. The results show that Q-dots were absorbed into NIH3T3 and EMT6 cells. Cellular uptake was also observed when hydrophobic Q-dots were coated directly on a glass plate. PLLA/Q-dot film and Q-dot coated on glass plate did not show major cytotoxicity. In vivo tumor model was also used to show the uptake of Q-dot from the PLLA/Q-dot film to the tumor site.

• 한국항해항만학회지
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• 제32권10호
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• pp.845-850
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• 2008

본 논문에서는 SVM을 이용한 번호판 위치 추출 알고리즘을 제안한다. 일반적으로 번호판 영역은 가로-세로 비율 컬러, 공간 주파수 성분 등의 특징을 포함하고 있다. 제안하는 기법은 영상 획득, 번호판 후보 영역 추출, 번호란 위치 검증 세가지 단계로 구성되어 있다. 번호판 후보 영역 추출 단계에서는 컬러 필터링과 경계선 검출을 하여 번호판 후보 영역을 찾아내고 후보 영역의 DCT 계수를 SVM에 적용하여 검증한다. 이러한 검증과정을 거침으로써 잘못된 추출을 막아 신뢰성 있는 번호판 영역 추출이 가능하다. 실험을 통해 제안한 방법을 검증하였다.

• 한국융합학회논문지
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• 제8권4호
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• pp.199-205
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• 2017

이 연구에서는 3D 프린터 히팅 블록의 발열로 인해 가이드로 열이 전달되어 필라멘트가 녹는 문제점을 개선하기 위해 설계 해석과 폭발압접을 융합한 방법으로 클래드 판재를 만들었다. 클래드 판재에 대한 전단 강도시험을 하였으며, 히팅 블록으로 가공한 다음 열 해석, 열전도도, 열화상 측정 결과 다음과 같은 결론을 얻었다. 구리와 타이타늄 클래드 판재로 만든 히팅 블록에 대하여 3D 모델링 열 해석 한 결과 필라멘트 가이드 부위의 표면온도가 히팅 블록 표면온도 보다 낮은 온도가 예측되었다. 구리와 타이타늄 클래드 판재로 만든 다음 전단 강도를 측정한 결과 평균 195.6MPa 값을 얻었다. 구리와 타이타늄 클래드 판재로 만든 히팅 블록에 대하여 열전도도를 3회 측정한 결과 평균 $62.52W/m{\cdot}K$값을 나타내었다. 구리와 타이타늄 클래드 판재로 만든 히팅 블록에 대하여 열화상 카메라로 표면 온도를 측정한 결과 최대 $107.3^{\circ}C$ 측정되었으며, 필라멘트 가이드 부근에서는 $183.2^{\circ}C$ 측정되었다. 기존 필라멘트의 부위의 온도 보다 $89^{\circ}C$ 낮은 온도 분포를 보였다.

• Imaging Science in Dentistry
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• 제44권2호
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• pp.149-154
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• 2014

Purpose: This study assessed the effectiveness of three antimicrobial mouthrinses in reducing microbial growth on photostimulable phosphor (PSP) plates. Materials and Methods: Prior to performing a full-mouth radiographic survey (FMX), subjects were asked to rinse with one of the three test rinses ($Listerine^{(R)}$, $Decapinol^{(R)}$, or chlorhexidine oral rinse 0.12%) or to refrain from rinsing. Four PSP plates were sampled from each FMX through collection into sterile containers upon exiting the scanner. Flame-sterilized forceps were used to transfer the PSP plates onto blood agar plates (5% sheep blood agar). The blood agar plates were incubated at $37^{\circ}C$ for up to 72 h. An environmental control blood agar plate was incubated with each batch. Additionally, for control, 25 gas-sterilized PSP plates were plated onto blood agar and analyzed. Results: The mean number of bacterial colonies per plate was the lowest in the chlorhexidine group, followed by the Decapinol, Listerine, and the no rinse negative control groups. Only the chlorhexidine and Listerine groups were significantly different (p=0.005). No growth was observed for the 25 gas-sterilized control plates or the environmental control blood agar plates. Conclusion: The mean number of bacterial colonies was the lowest in the chlorhexidine group, followed by the Decapinol, Listerine, and the no rinse groups. Nonetheless, a statistically significant difference was found only in the case of Listerine. Additional research is needed to test whether a higher concentration (0.2%) or longer exposure period (two consecutive 30 s rinse periods) would be helpful in reducing PSP plate contamination further with chlorhexidine.

• 비파괴검사학회지
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• 제32권1호
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• pp.47-55
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• 2012

본 논문에서는 단일 센서와 시간역전 원리를 이용하여 간단한 판에서 충격 위치를 결정할 수 있는 탐상법을 다루었다. 수치적인 시뮬레이션과 실험을 통하여 시간역전에 의한 충격위치와 그 주변에서 신호의 집속효과를 관찰하고, 충격위치 결정에 영향을 미칠 수 있는 인자들(가진력의 크기, 신호의 기록시간)에 대해 살펴보았다. 이러한 결과를 기초로 두 가지 다른 충격위치에 대한 실험을 수행하고 그 결과를 가시화하였으며, 실제 충격위치를 정확하게 결정할 수 있음을 확인하였다. 여기서 제안한 방법의 특징은 단일센서를 사용하는 것과 시험체의 형상과 물성을 몰라도 된다는 점이다. 또한 판에서와 같이 분산성의 다중모드 파동이 발생하는 경우에도 특정 모드나 주파수에 의존할 필요가 없다. 따라서 기존의 충격위치 결정법에 비해 많은 장점을 지니고 있다.