• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.5
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• pp.930-934
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• 2006

In this study, we conducted water-quality analysis of wastewater and in-situ flow measurement using automatic flow rate measuring instrument to identify characteristics of wastewater in urban areas, and collected samples in gutter fur storm water drain, rainfall bucket, and aqueduct of pipe from roof, and outfalls of basins to examine the contribution by pollution origins such as base wastewater, atmospheric washing, runoff by roof surface, runoff by road surface, erosion of sewer sediment. In the result, the concentration of pollutants reached peak in the beginning of rainfall due to first flush, was 3 to 10 times higher than average concentration of dry period, and was lower than that of dry period due to dilution of storm water. In the analysis of the contribution by pollution origins, the ratio of load by sewer sediment resuspension to the total pollution load was 54.6% fer COD, and 73.3% fur SS. Accordingly, we can reduce the total pollutant load by periodical dredging and washing of sewer sediment, and control the loadings by overflow of combined sewer overflows.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.319-319
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• 2023

Flows of water in the environment (e.g. in a river or estuary) generally occur in complex conditions. This complexity can hinder a general understanding of flows and their related sedimentary processes, such as erosion and deposition. To gain insight in simplified, controlled conditions, hydraulic flumes are a popular type of laboratory research equipment. Linear flumes use pumps to recirculation water. This isn't appropriate for the investigation of cohesive sediments as pumps can break fragile cohesive sediment flocs. To overcome this limitation, the rotating annular flume (RAF) was developed. While not having pumps, a side-effect is that unwanted secondary circulations can occur. To counteract this, the top and bottom lid rotate in opposite directions. Furthermore, a larger flume is considered better as it has less curvature and secondary circulation. While only a few RAFs exist, they are important for theoretical research which often underlies numerical models. Many of the first-generation of RAFs have come into disrepair. As new measurement techniques and models become available, there is still a need to research cohesive sediment erosion and deposition in facilities such as a RAF. New RAFs also can have the advantage of being automatic instead of manually operated, thus improving data quality. To further advance our understanding of cohesive sediment erosion and deposition processes, a large, automatic RAF (1.72 m radius, 0.495 m channel depth, 0.275 m channel width) has been constructed at the Hydraulic Laboratory at Chungnam National University (CNU), Korea. The RAF has the ability to simulate both unidirectional (river) and bidirectional (tide) flows with supporting instrumentation for measuring turbulence, bed shear stress, suspended sediment concentraiton, floc size, bed level, and bed density. Here we present the current status and future prospect of the CNU RAF. In the future, calibration of the rotation rate with bed shear stress and experiments with unidirectional and bidirectional flow using cohesive kaolinite are expected. Preliminary results indicate that the CNU RAF is a valuable tool for fundamental cohesive sediment transport research.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.497-497
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• 2023

정수장에서 소독 및 여과 처리가 완료된 깨끗한 물은 배급수시설로 전달되나, 실제로 관의 노후화, 갑작스러운 유향 변동, 특정 구역의 관 내 정체 시간에 따른 Water Age 상승 등 여러 요인으로 인해 실제 수용가에는 안전하지 않은 용수가 공급될 가능성이 있으며, 이에 따라 적절한 위치에서 지속적인 감시를 통한 조기 발견 및 조치가 필요하다. 상수도 시설기준(2010)에 배수시설의 주요 지점 혹은 관 말단 등 필요에 따라 적절한 위치에 수질 계측기를 설치할 수 있도록 제시되어 있으나, 계측기 설치 위치나 개수에 대한 기준이 모호한 실정이다. 모든 구역에 수질계측기를 설치하여 감시하는 것이 이상적이지만, 현실적으로는 지자체 환경 및 경제적인 한계가 있어 주요 위치에 설치하는 것이 바람직하다. 본 연구에서는 대표적인 수리해석 모형인 EPANET을 사용하여 대상 관망의 노후도, 유속, 유향변동 등의 영향인자를 바탕으로 수질사고가 발생할 확률이 높은 관을 위험관으로 선정하고, 선정된 위험관을 대상으로 최단 경로와 Cost를 산출할 수 있는 Floyd Warshall Algorithm을 이용하여 각 Node(수용가)간 물이 이동할 때의 최소 도달시간과 경로를 파악하였다. 또한, 시간 서비스 수준(Level of T hour Serivice)의 개념을 도입하여 위험관으로부터 특정시간 이내에 흐름이 도달하는 Node를 파악한 뒤, 그 중 가장 많은 피해를 발생시킬 수 있는 위험관을 수질계측위치 지점으로 선정하였다. 제시된 수질사고 발생위험이 높은 위험관을 대상으로 수질계측 위치를 선정하는 방법이 전체 관망 네트워크를 대상으로 수질계측 위치를 판단하는 방법보다 결과 신뢰도 측면에서 더욱 효과적이고 효율적인 방법으로 사료된다.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2004.11a
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• pp.153-156
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• 2004

Korea Food and Drug Administration(KFDA) has peformed the calibration of therapy level dosimeters for Co-60 radiation since 1979. The reference standard ionization chamber has been calibrated at BIPM in France. The uncertainty on the KFDA calibration coefficients is 0.9 %(k=2) for air kerma and absorbed dose to water. Since 1999 a national quality audit program for ensuring dosimetry accuracy in Korea radiotherapy centers has been performed by the KFDA. The uncertainty associated with the determination of the absorbed dose to water from the TLD readings for high energy x-ray is 1.6 %(k=1). The correction factors for energy, non-linearity dose response, and TLD holder are used in the dose determination. Agreement between the user stated dose and KFDA measured dose within ${\pm}$ 5 % is considered acceptable. KFDA TLD postal dose quality audit program was peformed for 71 beam qualities of 53 domestic radiotherapy centers in 2003. The results for quality assurance showed that 63 out of 71 beam qualifies (89 %) satisfied the acceptance limit. The second audit was carried out for the centers outside the limit and ail of them have been corrected.

• Progress in Medical Physics
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• v.7 no.2
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• pp.19-28
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• 1996

It is important that the precise decision of the region and the accurate delivery of radiation dose required for treatment in the stereotactic radiosurgery. In this research, radiosurgery was carried with Leksell streotactic frame(LSF) which is especially developed water phantom to verify in experiment. Leksell Gamma Knife and LSF are used in radiosurgery is the spherical water phantom has the thickness of 2 mm, the radius of 160mm. The film for target localization and ionchamber for dose delivery was used in measurement instruments We compare the coordinate of target which is initialized by biplannar film with simple X-ray to the coordinate of film measured directly. The calculated dose by computer simulation and the measured dose by ionization chamber are compared. In this research, the target localization has the range ${\pm}$0.3mm for the acceptable error range and the absolute dose is :${\pm}$0.3mm for the acceptable error range. This research shows that the values measured by using the especially manufactured phantom are included the acceptable error range. Thus, this water phantom will be used continuously in the periodic quality assurance of Gamma Knife Unit and Leksell Stereotactic Frame.

• Progress in Medical Physics
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• v.15 no.4
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• pp.186-191
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• 2004

The periodic Quality Assurance (QA) of each radiation treatment related equipments is important one, but quality assurance of the radiation treatment planning system (RTPS) is still not sufficient rather than other related equipments in clinics. Therefore, this study will present and test the periodic QA program to compare, evaluation the efficiency of the treatment planning systems. This QA program is divided to terms for the input, output devices and dosimetric data and categorized to the weekly, monthly, yearly and non-periodically with respect to the job time, frequency of error, priority of importance. CT images of the water equivalent solid phantom with a heterogeneity condition are input into the RTPS to proceed the test. The actual measurement data are obtained by using the ion chamber for the 6 MV, 10 MV photon beam, then compared a calculation data with a measurement data to evaluate the accuracy of the RTPS. Most of results for the accuracy of geometry and beam data are agreed within the error criteria which is recommended from the various advanced country and related societies. This result can be applied to the periodic QA program to improve the treatment outcome as a proper model in Korea and used to evaluate the accuracy of the RTPS.

• Journal of the Korean Society of Radiology
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• v.18 no.3
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• pp.239-248
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• 2024

Radiation therapy uses high energy, which can have side effects on the human body. Therefore, it is important to ensure that the appropriate dose is set for irradiation and to have confidence in the radiation produced by the generator. The EPR/Alanine dosimetry system is characterized by water equivalence, dose response linearity, and low fading, which makes it useful for quality control of radiation therapy equipment. In this study, we compared the signal and dose response curves of EPR/Alanine dosimetry by mass of alanine using 6 MV energy of a LINAC. An alanine dosimeter and EPR spectrometer from Burker, and a LINAC from Elekta, were used. A dose response curve and a 1st order regression equation were constructed from the irradiated dose and the EPR signal from the alanine dosimeter. We compared the signal magnitude and dose response curve with mass and checked the confidence through the measurement uncertainty of the dose response curve. As a result, it was found that the magnitude of the EPR signal increased by about 1.3 times at 64.5 mg, and the sensitivity of the dose response curve increased as the mass increased. The measurement uncertainty was evaluated to be between 5.84 % and 8.93 %. Through this study, it is expected that the EPR/alanine dosimetry system can be applied to the quality assurance and quality control of a LINAC.

• Journal of Korea Water Resources Association
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• v.52 no.12
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• pp.1075-1086
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• 2019

Recently, as the incidence of climate warming and abnormal climate increases, the forecasting of hydrological factors such as precipitation and river flow is getting more complicated, and the risk of water shortage is also increasing. Therefore, this study aims to develop a model for predicting the amount of water intake in mid-term. To this end, the correlation between water intake and meteorological factors, including temperature and precipitation, was used to select input factors. In addition, the amount of water intake increased with time series and seasonal characteristics were clearly shown. Thus, the preprocessing process was performed using the time series decomposition method, and the support vector machine (SVM) was applied to the residual to develop the river intake prediction model. This model has an error of 4.1% on average, which is higher accuracy than the SVM model without preprocessing. In particular, this model has an advantage in mid-term prediction for one to two months. It is expected that the water intake forecasting model developed in this study is useful to be applied for water allocation computation in the permission of river water use, water quality management, and drought measurement for sustainable and efficient management of water resources.

• Journal of Sensor Science and Technology
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• v.30 no.3
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• pp.154-164
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• 2021

In this study, the IoT sensor technology required for improving the survival rate and high-density productivity of individual shrimp in smart shrimp farming (which involves the usage of recirculating aquaculture systems and biofloc technology) was analyzed. The principles and performances of domestic and overseas water quality monitoring IoT sensors were compared. Furthermore, the drawbacks of existing aquaculture monitoring technologies and the countermeasures for future aquaculture monitoring technologies were examined. In particular, for farming white-legged shrimp, an IoT sensor was employed to collect measurement indicators for managing the water quality environment in real-time, and the IoT sensor-based real-time monitoring technology was then analyzed for implementing the optimal farming environment. The results obtained from this study can potentially contribute to the realization of an autonomous farming platform that can improve the survival rate and productivity of shrimp, achieve feed reduction, improve the water quality environment, and save energy.

• Journal of radiological science and technology
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• v.30 no.2
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• pp.139-145
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• 2007

Dose evaluation for small field such as stereotactic radiosurgery was performed using $Gafchromic^{(R)}$ EBT film. Every film which irradiated 6MV photon beam was scanned and obtained the optical density(OD) by flat bed scanner after 24 hours of irradiation. This study compared dose from diode in water and Gafchromic $EBT^{(R)}$ film in acrylic phantom to verify the reliability of the film, and to evaluate the SRS in clinical dose distributions from calculation and measurement in the region of virtual target in humanoid and cylindrical phantoms were compared. The Gafchromic $EBT^{(R)}$ film was found to be linear up to 9Gy. The $D_{max}$ for 6 MV was measured at 1.5 cm from the surface by both of diode and the film. As the depth is deeper, the error was measured within $2{\sim}3%$ at $10{\sim}20\;cm$ depth. Comparing between distribution from calculation and measurement, we found that there is 5% error at 90% isodose line. We found that given dose could be measured accurately by using the phantoms. It was feasible to use the Gafchromic $EBT^{(R)}$ film in quality assurance of SRS.