• Journal of Radiation Protection and Research
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• 제43권2호
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• pp.59-65
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• 2018

Background: We analyzed changes in the doses, structure volumes, and dose-volume histograms (DVHs) when data were transferred from one commercial treatment planning system (TPS) to another commercial TPS. Materials and Methods: A total of 22 volumetric modulated arc therapy (VMAT) plans for nasopharyngeal cancer were generated with the Eclipse system using 6-MV photon beams. The computed tomography (CT) images, dose distributions, and structure information, including the planning target volume (PTV) and organs at risk (OARs), were transferred from the Eclipse to the MRIdian system in digital imaging and communications in medicine (DICOM) format. Thereafter, DVHs of the OARs and PTVs were generated in the MRIdian system. The structure volumes, dose distributions, and DVHs were compared between the MRIdian and Eclipse systems. Results and Discussion: The dose differences between the two systems were negligible (average matching ratio for every voxel with a 0.1% dose difference criterion = $100.0{\pm}0.0%$). However, the structure volumes significantly differed between the MRIdian and Eclipse systems (volume differences of $743.21{\pm}461.91%$ for the optic chiasm and $8.98{\pm}1.98%$ for the PTV). Compared to the Eclipse system, the MRIdian system generally overestimated the structure volumes (all, p < 0.001). The DVHs that were plotted using the relative structure volumes exhibited small differences between the MRIdian and Eclipse systems. In contrast, the DVHs that were plotted using the absolute structure volumes showed large differences between the two TPSs. Conclusion: DVH interpretation between two TPSs should be performed using DVHs plotted with the absolute dose and absolute volume, rather than the relative values.

• 한국지반공학회논문집
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• 제27권11호
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• pp.39-45
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• 2011

본 연구는 글라스 비드와 고무 혼합재의 부피비와 상대적인 크기 비에 따른 열적 거동에 관해 다루고 있다. 혼합 물질의 열전도도를 측정하기 위하여 비정상면열원법이 사용되었다. 개별요소법과 열 네트워크 모델을 결합하여 입상체 모사 시료에서 입자 단위의 열전달 매커니즘을 분석하였다. 실험 및 해석의 결과는 다음과 같다. 유효 열전도도는 고무의 부피비가 증가할수록 감소한다. 두 물질의 상대적인 크기는 열 전파경로의 대부분을 결정하는 입자간 접촉상태의 공간적 구성을 지배한다. 같은 부피비를 갖는 혼합물질 중에서, 열이 잘 흐르지 않는 물질(여기에서는 고무)의 입자 크기가 큰 경우 열전달이 더 원활하게 이루어진다. 이상의 실험결과와 입자 단위의 관찰은 물질의 열적 거동이 부피비 뿐 아니라 구성 성분의 공간적인 구성에도 영향을 받음을 보여준다.

• 한국지반환경공학회 논문집
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• 제19권1호
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• pp.25-30
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• 2018

저수지 및 제방에서의 계측은 가장 높이가 높은 구간을 선정하여 계측기를 매설하고 측정하는 집중계측 방식으로 최근에는 자동화 계측기술이 발달되어 실시간으로 계측결과가 관리사무소로 전달 및 수집, 저장되고 있다. 실시간 계측기술이 발달되었음에도 불구하고 계측결과가 시설물 관리와는 직접적으로 이용되지 못하고 있다. 최근 사물인터넷 기반의 무선 센서 네트워크 계측기술이 발달함에 따라 본 연구에서는 저수지 및 제방 구조물에 무선센서 네트워크 기술을 기반의 실시간 계측 및 평가시스템을 제안하였다. 적용성 평가를 위한 침투해석 결과 저수위 변화에 따라 제체 내부의 침윤선 변화와 함께 토체의 체적함수비가 함께 변화하여 체적함수비를 센서 노드로 설정한 계측시스템의 적용성을 확인하였다.

• The Journal of Advanced Prosthodontics
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• 제13권2호
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• pp.71-78
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• 2021

Purpose. This study aims to compare the volumetric change, degree of conversion (DOC), and cytotoxicity of 3D-printed restorations post-cured under three different conditions. Materials and Methods. 3D-printed interim restorations were post-cured under three different conditions and systems: 5 min, 30 min, and 24 h. Three-unit and six-unit fixed dental prostheses (n = 30 for each case) were printed; ten specimens from each group were post-cured and then scanned to compare their volumetric changes. Root-mean-squared (RMS) values of the data were acquired by superimposing the scanned files with original files. Thirty disk-shaped specimens were printed to evaluate the DOC ratio. Fourier transform infrared spectroscopy was used to compare the DOCs of 10 specimens from each group. Human gingival fibroblasts were used to measure the cell viability of every specimen (n = 7). The data from this experiment were employed for one-way analysis of variance and Tukey's post-hoc comparisons. Results. Differences between the three-unit restorations were statistically insignificant, regardless of the post-curing conditions. However, for the six-unit restorations, a high RMS value was acquired when the post-curing duration was 30 min. The average DOC was approximately 56 - 62%; the difference between each group was statistically insignificant. All the groups exhibited cell viability greater than 70%, rendering them clinically acceptable. Conclusion. The post-curing conditions influenced the volume when the length of the restoration was increased. However, this deviation was found to be clinically acceptable. Additionally, post-curing did not significantly influence the DOC and cytotoxicity of the restorations.

• Journal of Periodontal and Implant Science
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• 제52권5호
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• pp.370-382
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• 2022

Purpose: The aim of this study was to evaluate the preclinical results of 2 types of commercially available deproteinized bovine bone mineral (DBBM) when applied to alveolar bone defects in dogs. Methods: This study was conducted using 6 beagles. Alveolar defects in the mandible were formed and filled with 2 DBBMs produced by a similar procedure. Defects were randomly assigned to be filled using DBBM 1 or 2. All defects were covered with a collagen membrane and had a healing period of 12 weeks. After the dogs were sacrificed, histological, histomorphometric, and linear/volumetric analyses were performed. Results: Both DBBM groups showed similar histological findings, demonstrating that bone remodeling had occurred and new bone had formed. The residual bone particles were surrounded by newly formed vital bone. In the histomorphometric analysis, the ratio of the area of vital bone and residual bone substitute in DBBM 2 (38.18% and 3.47%, respectively) was higher than that of DBBM 1 (33.74% and 3.41%, respectively), although the difference was not statistically significant. There were also no statistically significant differences between both groups in linear and volumetric analyses using micro-computed tomography scans and digitized images of dental casts. Conclusions: In the present study, DBBM 1and 2, which were produced by similar processes, showed similar results in histological, histomorphometric, and volumetric analyses. Further studies are needed to identify more specific differences between the 2 DBBMs.

• 한국수소및신에너지학회논문집
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• 제33권1호
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• pp.67-76
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• 2022

We developed a technology that can measure the hydrogen uptake and diffusivity of rubber materials by using the volumetric analysis method and diffusivity analysis program through the measurement of the water level in the graduated cylinder. In this method, hydrogen gas is charged at a certain pressure for a certain period of time for a rubber material exposed to a high-pressure hydrogen gas environment, and then the pressure is reduced to measure the change in the water level in the graduated cylinder in real time, and based on the measured value, it is a technology that can evaluate hydrogen uptake and diffusivity using diffusivity analysis program. Using this method, the hydrogen uptake and diffusivity of the NBR material were measured with respect to the change in the type and weight ratio of the filler used to improve the physical properties of the rubber material. In addition, uncertainty analysis was performed on the diffusivity measurement method.

• 상하수도학회지
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• 제13권4호
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• pp.35-44
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• 1999

In this study, it was attempted to remove nitrate and carbon in a single-stage reactor using acetate as substrate. Hybrid type upflow sludge baffled filter reactor was adopted using anaerobic sludge. Sludge bed in the bottom of reactor was intended to remove carbon and nitrate by denitrification and methanogenesis. And floating media in the upper part of reactor were intended to remove remaining carbon which was not removed due to the inhibition of nitrogen oxide on methane producing bacteria. The reactor removed over 96% of COD and most of nitrate with volumetric loading rate of $4.0kgCOD/m^3{\cdot}day$, hydraulic retention time of 24hr, 4,000mgCOD/L, and $266mgNO_3-N/L$. Nitrate in anaerobic sludge was converted to nitrogen gas(denitrification) or ammonia (ammonification) according to pH of influent, COD removal efficiency was easily affected by the change of volumetric loading rates and nitrate concentration. And when influent pH was about 4.7, most nitrate changed to ammonia while when influent pH was about 6.8~7.0, most nitrate denitrified independent of $COD/NO_3-N$ ratio. Most granules were gray and a few were black. In gray-colored granule, black inner side was covered with gray substance and SEM illustrated Methanoccoci type microorganisms which were compact spherical shape. Anaerobic filter removed residual COD effectively which was left in sludge bed due to the inhibition of nitrogen oxide.

• 한국산업융합학회 논문집
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• 제18권2호
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• pp.110-118
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• 2015

In this study, it is designed and used the test engine bed which is installed with turbocharger, and in addition to equipped using by oxygen adder. It has been controlled the oxygen volumetric fraction of intake air chrge, and supercharged flow rate into the cylinder of SI 4-stroke engine, and then, has been analyzed engine performance, combustion characteristics, and exhaust emission as analysis parameters. The tested parameters were the oxygen fraction and the variation of engine speed and air-fuel ratio.

• Journal of Mechanical Science and Technology
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• 제17권4호
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• pp.581-589
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• 2003

Film absorption involves simultaneous heat and mass transfer in the gas-liquid system. While the non-absorbable gas does not participate directly In the absorption process. its pretence does affect the overall heat and mass transfer. An experimental study was performed to investigate the heat and mass transfer characteristics of LiBr-H$_2$O solution flow ing over 6-row horizontal tubes with the water vapor absorption in the pretence of non-absorbable gases. The volumetric concentration of non-absorbable gas, air, was varied from 0.17 to 10.0%. The combined effects of the solution flow rate and its concentration on the heat and mass transfer coefficients were also examined. The presence of 2％ volumetric concentration of air resulted in a 25% reduction in the Nusselt number and 41% reduction in the Sherwood number Optimum film Reynolds number was found to exist at which the heat and mass transfer reach their maximum value independent of air contents. Reduced Nusselt and Sherwood numbers. defined as the ratio of Nusselt and Sherwood numbers at given non-absorbable gas content to that with pure water vapor, were correlated to account for the reduction in the heat and mass transfer due to non-absorbable gases in a falling film absorption process.

• 멤브레인
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• 제4권3호
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• pp.142-151
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• 1994

역삼투 공정을 농축공정에 이용하기 위해 향류식 역삼투 나권형 모듈을 고안, 제작하여 염수의 농축실험을 수행하였다. 역삼투 분리의 배제도와 농축도의 관계를 고찰한 결과, 배제유량에 대한 투과유량의 비가 양쪽 관계의 중요한 매개 변수이며, 반사계수 값에 따라, 역삼투막의 배제도와 농축도가 Spiegler-Kedem 식의 경향을 따른다. 향류식 역삼투 공정은 일반 역삼투 농축 공정에 비해 농축의 장애 요소인 삼투압차를 효과적으로 저하시키는 효과가 있으며 농축도가 상대적으로 우수하였다. 향류식 나권형 모듈의 수치모사 결과 농축공정의 농축도 증가를 위해서는 모듈의 지름보다 모듈의 길이를 늘리는 것이 유리함을 알 수 있었다.