• 한국의학물리학회지:의학물리
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• 제17권1호
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• pp.32-39
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• 2006

CT 검사에서 조영제의 혈관외유출을 예방하기 위해 EDA시스템을 증폭기, ADC, 스트레인 게이지로 구성하여 개발하였고, 스트레인 게이지의 신호의 수치를 나타내도록 프로그램을 설계하였다. 신호비율은 500/1000 sec, 분해능 값은 0에서 4,096범위로 표시하고, 입력범위 $0{\sim}5$ V이다. 혈관외유출 검출 문턱 값은 50으로 하였고, 10 간격으로 조정하도록 하였다. 개발된 EDA 시스템을 성인 50명을 대상으로 적용하였다. 2명의 환자에서 혈관외유출이 검출되었고, 조영제 주입속도는 2.0 mL/sec, 2.5 mL/sec, 압력은 137 psi, 158 psi, 혈관외유출된 조영제 용량은 22 mL, 25 mL였다. 설정된 주입 조영제에 비해 20% 정도의 적은 용량이 혈관외유출되었다. 개발된 EDA 시스템은 소량의 조영제를 검출하여 혈관외유출을 예방하는 효과가 있다.

• 방사선산업학회지
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• 제8권1호
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• pp.23-27
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• 2014

Industrial single photon emission computed tomography (SPECT) is an useful technique to investigate the dynamic behavior of process flow. In the present study, to evaluate the influence of a void on the performance of industrial SPECT, industrial SPECT with various radioisotope sources and gas holdups was modeled by the Monte Carlo simulation. The results are very encouraging; that is, the void little influences the performance of industrial SPECT, which means that industrial SPECT could be a suitable tool to investigate the dynamic characteristics of the flow in a water-air phase process.

• 한국가시화정보학회지
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• 제20권2호
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• pp.86-92
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• 2022

Pipe failure due to thermal fatigue and environmental regulations are increasing the importance of pipe monitoring systems in industrial plants. Since most pipe monitoring systems are focus on external crack inspected, it is necessary to temperature and concentration measuring monitoring system inside the pipe. These systems have spatial uncertainty due to sample inspection by one-point measurement. In addition, real-time measurement is not possible due to the limitation of time delay due to contact measurement. In this study, CT-TDLAS (Computed tomography-Tunable diode laser absorption spectroscopy) apply to overcome the limitations of existing methods. Lasers exhibiting an absorption response at a wavelength of 1395 nm were arranged in a lattice pattern on measuring cell. It showed that the inside of the pipe changed to an unstable combustion state over time.

• 방사선산업학회지
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• 제6권3호
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• pp.245-249
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• 2012

Demand of fluid flow visualization has increased in industrial processes, because medical imaging technology is highly developed. As a part of the industrial process imaging technology, industrial single photon emission computed tomography (SPECT) system was developed to measure the cross-sectional distribution of the process fluid. The SPECT consists of 36 NaI (Tl) detectors with the hexagonal configuration. Reconstructed images were acquired for various positions of radioactive source to estimate SPECT device performance. To evaluate the reliability of the experimental results, the Monte Carlo simulation results are compared with experimental results. In general, the experimental and simulation results were consistent. However, as the source position was getting far from the center of the reactor, the accuracy of reconstructed images was compromised. It seems to be due to the inconsistent spatial resolution of the collimators according to the source position.

• 한국산학기술학회논문지
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• 제11권11호
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• pp.4411-4417
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• 2010

64채널 MDCT(multidetector computed tomography)와 128채널 DSCT(dual source computed tomography)를 이용한 관상동맥 전산화단층촬영 시 유효선량과 획득한 영상의 질을 평가함으로서 임상에서의 유용성을 평가하고자 하였다. 피폭선량은 선량길이곱(dose length product: DLP)에 흉부 조직의 가중치(0.017)을 곱하여 유효선량(mSv)으로 계산하였으며, 영상 평가는 심장촬영검사 후 영상의학과 전문의가 5점 Likert 척도(5점 최상)로 평가하였다. DLP 값은 64 채널 MDCT에서는 $851{\sim}1277\;mGy{\cdot}cm$ (평균 유효선량: 17.23mSv), 128 채널 DSCT에서는 $82{\sim}110\;mGy{\cdot}cm$ (평균 유효선량: 1.58mSv)로 각각 분포하였다. 영상 평가점수는 64 채널 MDCT에서 $3.31{\pm}0.62$(4점 이상 34명), 128channel DSCT에서 $4.05{\pm}0.46$(4점 이상 96명)으로 각각 나타났다. 유효선량은 64채널 MDCT에 비해 128채널 DSCT가 1/10 이상 감소함을 알 수 있었다. 영상 평가점수는 통계적으로 유의한 차이를 보였으며 4점 이상 점수의 빈도는 128채널 DSCT에서 2.8배 높게 나타났다. 결론적으로 관상동맥 전산화단층촬영검사에서는 128채널 DSCT가 64채널 MDCT에 비해 환자가 받는 유효선량은 감소하고 영상 평가점수는 높게 나타나 임상에서 보다 유용할 것으로 판단된다.

• 한국산학기술학회논문지
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• 제13권11호
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• pp.5311-5316
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• 2012

뇌 영상분석 알고리즘 적용에 따른 뇌혈류의 변화를 관찰하기 위해 정상 성인 13명(평균연령 39세)을 대상으로 뇌혈류 단 광자 단층촬영(Single Photon Emission Computed Tomography, SPECT)을 시행하였다. 획득된 영상을 여과후 역투영법(Filtered Back Projection, FBP)과 반복적 방법(Ordered Subset Expectation Maximization, OSEM)으로 영상을 재구성하여 통계학적 파라미터 뇌지도법으로 비교하여 방사성 의약품의 뇌 분포양상을 확인하였으며, 혈류의 변화는 크러스트(Cluster)로 표현시켰다. 이에 대한 결과로는 여과후 역투영법이 반복적 방법보다 섭취가 증가된 부위는 우측 전두엽, 대뇌회전하부, 외핵, 좌측대뇌 변엽과 대상이랑이며, 섭취가 감소된 부위는 좌측전두엽, 중간전두이랑, 하측전두이랑, 중심전이랑, 하측전두이랑, 중심전이랑이었다. 이는 영상재구성시 적용되는 알고리즘에 따라 뇌 혈류분포가 다르게 나타난 것을 크러스트(Cluster)로 표현시켰고, 명확한 시각적 표시가 가능하도록 뇌 확룔 지도로 보여주는데 의의가 있다.

• 한국산학기술학회논문지
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• 제11권6호
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• pp.2240-2245
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• 2010

심근영상의 SPECT(Single Photon Emission Computed tomography)검사는 감마선을 방출하는 방사성의약품을 환자에게 정맥주사한 후 이 의약품이 심장에 고루 퍼지면 관심부위를 촬영하여 질병으로 인한 변화를 컴퓨터를 이용하여 진단하는 검사법이다. 기능적인 정보를 담고 있는 심근관류 영상은 비침습적인 심근질환 검사에 유용한 방법이지만, 물리적 인자들에 의해 잡음과 낮은 해상도는 판도하는데 어려움을 주게 된다. 본 논문은 심근영상을 레벨 셋 알고리즘을 이용하여 영상을 분할하고 분할된 영역을 3차원으로 구현하여 판독에 도움을 주는 방안을 제안하였다. 판독의 어려움을 해결하기 위하여 레벨 셋을 이용하여 관심부위인 좌심실 영역을 분할하였고 분할된 영역을 3차원영상으로 모델링 하였다.

• Computers and Concrete
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• 제31권5호
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• pp.433-442
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• 2023

This study presents the visually observed behavior of fibers embedded in concrete samples that were subjected to a flexural bending test. Three types of fibers such as macro polypropylene, macro polyethylene, and the hybrid of steel and polyvinyl alcohol were mixed with cement by a designated mix ratio to prepare a total of nine specimens of each. The bending test was conducted by following ASTM C1609 with a net deflection of 2, 4, and 7 mm. The X-ray computed tomography (XCT) was carried out for 7 mm-deflection specimens. The original XCT images were post-processed to denoise the beam-hardening effect. Then, fiber, crack, and void were semi-manually segmented. The hybrid specimen showed the highest toughness compared to the other two types. Debonding based on 2D XCT sliced images was commonly observed for all three groups. The cement matrix near the crack surface often involved partially localized breakage in conjunction with debonding. The pullout was predominant for steel fibers that were partially slipped toward the crack. Crack bridging and rupture were not found presumably due to the image resolution and the level of energy dissipation for poly-fibers, while the XCT imaging was advantageous in evaluating the distribution and behavior of various fibers upon bending for fiber-reinforced concrete beam elements.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.195-196
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• 2006

Direct laser sintering (DLS) technology for the resign coated sand is one of attractive technologies to produce molds and cores for the foundry industry rapidly and cost effectively. The objective of this case study is to develop casting pilot models using computer simulation technology, DLS RP machine and industrial computed tomography. The proposed casting design was verified by the Z-Cast software in the fields of fluid flow and solidification during the casting process. Casting parts with aluminum alloy using the post-curing treated sand moulds and cores are accurate to dimension and defect free.

• Journal of International Society for Simulation Surgery
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• 제3권1호
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• pp.16-21
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• 2016

Computed tomography (CT) can completely digitize the interior and the exterior of nearly any object without any destruction. Generally, the resolution for industrial CT is below a few microns. The industrial CT scanning, however, has a limitation because it requires long measuring and processing time. Whereas, 2D X-ray imaging is fast. In this paper, we propose a novel concept of 3D non-destructive inspection technique using the advantages of both micro-CT and dual X-ray images. After registering the master object’s CT data and the sample objects’ dual X-ray images, 3D non-destructive inspection is possible by analyzing the matching results. Calculation for the registration is accelerated by parallel computing using graphics processing unit (GPU).