• 대한방사선기술학회지:방사선기술과학
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• 제45권2호
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• pp.151-158
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• 2022

The Cardiac Gated Blood Pool (GBP) scintigram, a nuclear medicine imaging, calculates the left ventricular Ejection Fraction (EF) by segmenting the left ventricle from the heart. However, in order to accurately segment the substructure of the heart, specialized knowledge of cardiac anatomy is required, and depending on the expert's processing, there may be a problem in which the left ventricular EF is calculated differently. In this study, using the DeepLabV3 architecture, GBP images were trained on 93 training data with a ResNet-50 backbone. Afterwards, the trained model was applied to 23 separate test sets of GBP to evaluate the reproducibility of the region of interest and left ventricular EF. Pixel accuracy, dice coefficient, and IoU for the region of interest were 99.32±0.20, 94.65±1.45, 89.89±2.62(%) at the diastolic phase, and 99.26±0.34, 90.16±4.19, and 82.33±6.69(%) at the systolic phase, respectively. Left ventricular EF was calculated to be an average of 60.37±7.32% in the ROI set by humans and 58.68±7.22% in the ROI set by the deep learning segmentation model. (p<0.05) The automated segmentation method using deep learning presented in this study similarly predicts the average human-set ROI and left ventricular EF when a random GBP image is an input. If the automatic segmentation method is developed and applied to the functional examination method that needs to set ROI in the field of cardiac scintigram in nuclear medicine in the future, it is expected to greatly contribute to improving the efficiency and accuracy of processing and analysis by nuclear medicine specialists.

• Nuclear Engineering and Technology
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• 제54권2호
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• pp.627-636
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• 2022

In nuclear power plants and other nuclear facilities the removal of cobalt from radioactive liquid waste is needed to reduce the radioactivity concentration in effluents. In liquid wastes containing strong organic complexing agents such as EDTA cobalt removal can be problematic due to the high stability of the Co-EDTA complex. In this study, the removal of cobalt from NaNO₃ solutions using antimony oxide (Sb₂O₃) synthesized from potassium hexahydroxoantimonate was investigated in the absence and presence of EDTA. The uptake studies on the ion exchange material were conducted both in the dark (absence of UV-light) and under UV-C irradiation. Ca²⁺ or Ni²⁺ were included in the experiments as competing cations to test the selectivity of the ion exchanger. Results show that UV-C irradiation noticeably enhances the cobalt sorption efficiency on the antimony oxide. It was shown that nickel decreased the sorption of cobalt to a higher extent than calcium. Finally, the sorption data collected for Co²⁺ on antimony oxide was modeled using six different isotherm models. The Sips model was found to be the most suitable model to describe the sorption process. The Dubinin-Radushkevich model was further used to calculate the adsorption energy, which was found to be 6.2 kJ mol^-1.

• 한국전자통신학회논문지
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• 제16권6호
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• pp.1133-1144
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• 2021

Zero-copy는 메모리 무복사로도 불리는 기술로서 이에 대한 사용을 통해 사용자 영역과 커널 영역 간 컨텍스트 스위칭을 줄여 CPU의 부하를 최소화할 수 있다. 하지만 이 기술은 소규모의 랜덤한 파일을 전송하는 용도에 그치고, 대용량 파일 전송에는 아직 널리 활용되지 못하고 있다. 본 논문은 네트워크를 경유한 대용량 파일 처리에 있어서 Zero-copy의 실질적인 적용 방안에 대해 논의하고자 한다. 이를 위해 먼저 Zero-copy 기반으로 데이터를 전송, 저장할 수 있는 소규모 테스트베드 구축 및 프로그램을 개발하였다. 이후 세부 성능 평가를 통해 적용된 기술의 유용성을 세부 검증하고자 한다.

• Nuclear Engineering and Technology
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• 제54권1호
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• pp.36-48
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• 2022

As a valid numerical method to obtain a high-resolution result of a flow field, computational fluid dynamics (CFD) have been widely used to study coolant flow and heat transfer characteristics in fuel rod bundles. However, the time-consuming, iterative calculation of Navier-Stokes equations makes CFD unsuitable for the scenarios that require efficient simulation such as sensitivity analysis and uncertainty quantification. To solve this problem, a reduced-order model (ROM) based on proper orthogonal decomposition (POD) and machine learning (ML) is proposed to simulate the flow field efficiently. Firstly, a validated CFD model to output the flow field data set of the rod bundle is established. Secondly, based on the POD method, the modes and corresponding coefficients of the flow field were extracted. Then, an deep feed-forward neural network, due to its efficiency in approximating arbitrary functions and its ability to handle high-dimensional and strong nonlinear problems, is selected to build a model that maps the non-linear relationship between the mode coefficients and the boundary conditions. A trained surrogate model for modes coefficients prediction is obtained after a certain number of training iterations. Finally, the flow field is reconstructed by combining the product of the POD basis and coefficients. Based on the test dataset, an evaluation of the ROM is carried out. The evaluation results show that the proposed POD-ROM accurately describe the flow status of the fluid field in rod bundles with high resolution in only a few milliseconds.

• 중환자간호학회지
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• 제15권3호
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• pp.115-127
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• 2022

Purpose : This study aimed to investigate sleep parameters and to identify differences according to respiratory support therapy, sedation, and pain medication in intensive care unit (ICU) patients. Methods : In this observational study, sleep parameters were measured using actigraphy. We observed 45 sleep events in 30 ICU patients receiving respiratory support therapy. We measured the sleep parameters, time, efficiency, and wakefulness after sleep onset (WASO). The differences in sleep parameters according to the respiratory support therapy were analyzed using the Mann-Whitney U test. Results : The average daily sleep time of the participants was 776.66±276.71 minutes, of which more than 60% accounted for daytime sleep. During night sleep, the duration of WASO was 156.93±107.91 minutes, and the frequency of WASO was 26.02±25.82 times. The high flow nasal cannula (HFNC) group had a significantly shorter night sleep time (𝑥²=7.86, p =.049), a greater number of WASO (𝑥²=5.69, p =.128), and a longer WASO duration (𝑥²=8.75, p =.033) than groups of other respiratory therapies. Conclusion : ICU patients on respiratory support therapy experienced sleep disturbances such as disrupted circadian rhythm and sleep fragmentation. Among respiratory support regimens, HFNC was associated with poor sleep parameters, which appears to be associated with the insufficient use of analgesics. The results of this study warrant the development of interventions that can improve sleep in ICU patients receiving respiratory support, including HFNC.

• Nuclear Engineering and Technology
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• 제53권4호
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• pp.1189-1198
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• 2021

When performing remote tasks using robots in nuclear power plants, a 3D shape measurement system is advantageous in improving the efficiency of remote operations by easily identifying the current state of the target object for example, size, shape, and distance information. Nuclear power plants have high-radiation and underwater environments therefore the electronic parts that comprise 3D shape measurement systems are prone to degradation and thus cannot be used for a long period of time. Also, given the refraction caused by a medium change in the underwater environment, optical design constraints and calibration methods for them are required. The present study proposed a method for developing an underwater 3D shape measurement system with improved radiation tolerance, which is composed of commercial electric parts and a stereo camera while being capable of easily and readily correcting underwater refraction. In an effort to improve its radiation tolerance, the number of parts that are exposed to a radiation environment was minimized to include only necessary components, such as a line beam laser, a motor to rotate the line beam laser, and a stereo camera. Given that a signal processing circuit and control circuit of the camera is susceptible to radiation, an image sensor and lens of the camera were separated from its main body to improve radiation tolerance. The prototype developed in the present study was made of commercial electric parts, and thus it was possible to improve the overall radiation tolerance at a relatively low cost. Also, it was easy to manufacture because there are few constraints for optical design.

• 방송공학회논문지
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• 제26권4호
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• pp.441-452
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• 2021

본 논문에서는 VVC의 LMCS에서 휘도 신호 매핑 방법의 부호화 효율을 향상시키기 위한 휘도 신호 매핑 함수 생성 방법을 제안한다. 본 논문에서 제안하는 방법은 기존 LMCS에서 지역적 특징을 반영하기 위하여 사용하는 지역적 공간 분산에 합성 곱 신경망의 어텐션 맵을 곱하여 인지 지각적 특징을 추가적으로 반영한다. 제안하는 방법의 성능 평가를 위하여 AI (All Intra) 조건에서 VVC 표준 실험 영상의 A1, A2, B, C, D 클래스를 이용하여 VTM-12.0과 BD-rate 성능을 비교한다. 실험 결과로서 본 논문에서 제안하는 방법이 VTM-12.0 대비 BD-rate 성능 관점에서 휘도 성분이 평균 -0.07%의 성능 향상을 보이고, 부/복호화 시간은 거의 동일하다.

• 한국산학기술학회논문지
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• 제22권4호
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• pp.42-48
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• 2021

최근 4차산업혁명을 통해 융합 기술이 발달하면서, 국방 분야에서도 이러한 흐름을 바탕으로 무기체계의 첨단화, 고도화 등을 모색하고 있다. 하지만 첨단 기술을 바탕으로 개발되는 무기체계의 성능시험은 여러 변수들이 존재하며, 실제 운용환경에서 시험을 수행하기에 많은 어려움이 따른다. 이러한 문제점을 극복하기 위한 방안으로 M&S 자원을 적극 활용하여 그 성능을 입증하고 있으나, 사용 중인 M&S 자원의 신뢰성을 보증할 수 있는 수단을 추가로 요구하고 있다. 이에 따라 위한 VV&A 업무 수행을 통해 M&S 자원의 신뢰성을 확보하고 있다. VV&A 업무의 지속적인 요구와 수행으로 인해 관련 제도 등은 많은 발전이 이루어졌지만, 업무 수행을 위한 도구나 기법 등은 제도에 맞추어 발전하지 못하여 업무 수행에 있어 비효율적인 부분이 존재하며, 체계적인 시스템의 부재로 인하여 보안 등 여러 안전사고가 발생할 수 있는 위험성을 다수 내포하고 있다. 본 논문에서는 수행중인 국방M&S VV&A 업무의 문제점 분석을 통해 보다 효율적이고 안전한 방법을 모색하고, 이를 기반으로 업무의 발전방향을 제시하고자 한다.

• Human Ecology Research
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• 제60권2호
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• pp.243-256
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• 2022

Undergraduate freshmen are currently encountering numerous difficulties in adapting to college life due to the outbreak of the COVID-19 pandemic. Thus, several studies have underlined the need to develop interventions focused on undergraduate students' resilience during this situation. We adopted the service design method in identifying the difficulties faced by undergraduate freshmen during this pandemic, and also developed interventions for raising their resilience. The service design method is a person-centered approach which adopts the user's viewpoint in developing solutions, thereby enabling their requirements to be satisfied. Surveys and in-depth interviews revealed that undergraduate freshmen were experiencing psycho-emotional problems which were derived from schoolwork and college life. This is particularly the case with students who are experiencing greater levels of academic difficulty, and were insufficiently equipped with resources such as stress-coping strategies and social support. Four undergraduate freshmen were recruited online to test the effectiveness of a resource promotion program aimed at enhancing their resilience. This program has proved to be helpful in relieving daily/academic stress and in building relationships among freshmen, regarding which the participants showed a high level of satisfaction. The results were discussed by focusing on psycho-emotional difficulties and resources of college freshmen, as well as the effectiveness of the resource promotion program. Further research is required in order to verify the efficiency of the program and to confirm conclusions.

• 한국응급구조학회지
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• 제26권3호
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• pp.37-46
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• 2022

Purpose: TThe experiment was designed to compare the efficiency of ventilation between conventional BVM ventilation and a newly devised A-BVM ventilation method with Tidal volume, total ventilation rate, average Ventilation speed, and average Ventilation volume. Methods: 40 Paramedical students who agreed to participate in the study were analyzed. Values were measured using IMB PASS after 2 minutes of Brayden Pro manikin with BVM and A-BVM ventilation. The difference in general characteristics was assessed by t-test and ANOVA and the difference in ventilation methods was analyzed by IBM SPSS. Results: A significant difference was found between the two ventilation methods in terms of tidal volume (t=-11.203, p<.001), ventilation time (t=-3.834, p<.001), and optimum ventilation probability (t=10.770, p<.001). A-BVM ventilation method, rather than BVM ventilation method, showed a value close to the appropriate amount recommended by Korean Advanced Life Support (500~600mL) in tidal volume, and higher in optimum ventilation probability. Conclusion: We could identify the a better mode of ventilation. Further studies on the efficacy of existing BVM ventilation methods as compared to device augmented BVM ventilation methods should be carried out to ensure that adequate ventilation is available to patients in clinical practice.