• Journal of the Korean Society for Precision Engineering
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• 제27권6호
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• pp.55-63
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• 2010

Feedwater heaters of many nuclear power plants have recently experienced severe wall thinning damage, which will increase as operating time progresses. Several nuclear power plants in Korea have experienced wall thinning damage in the area around the impingement baffle inside feedwater heater installed downstream of the turbine extraction stream line. At that point, the extract steam from the turbine is two phase fluid at high temperature, high pressure, and high speed. Since it flows to reverse direction after impinging the impingement baffle, the shell wall of feedwater heaters may be affected by flow-accelerated corrosion. In this paper, to compare degree of shell wall thinning mitigation rate to squared type with mitigation rate of other type baffle plate, three different types of impingement baffle plate-squared, curved and mitigating type-applied inside the shell. With these comparison data, this paper describes operation of experiments and numerical analysis which is composed similar condition with real feed water heater. And flow visualization is operated for verification of experiments and numerical analysis. In conclusion, this study shows that mitigating type baffle plate is more effective than other baffle plate about prevention of pressure concentration and pressure value decrease.

• Journal of Internet Computing and Services
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• 제23권5호
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• pp.87-101
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• 2022

Cyber-attacks occur in the blink of an eye in cyberspace, and the damage is increasing all over the world. Therefore, it is necessary to develop a cyber common operational picture that can grasp the various assets belonging to the 3rd layer of cyberspace from various perspectives. By applying the method for grasping battlefield information used by the military, it is possible to achieve optimal cyberspace situational awareness. Therefore, in this study, the visualization screens necessary for the cyber common operational picture are identified and the criteria (response speed, user interface, object symbol, object size) are investigated. After that, the framework is designed by applying the identified and investigated items, and the visualization screens are implemented accordingly. Finally, among the criteria investigated by the visualization screen, an experiment is conducted on the response speed that cannot be recognized by a photograph. As a result, all the implemented visualization screens met the standard for response speed. Such research helps commanders and security officers to build a cyber common operational picture to prepare for cyber-attacks.

• The Journal of Engineering Geology
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• 제17권1호
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• pp.135-142
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• 2007

Although rock itself has high strength or low permeability, engineering properties of rock masses are significantly influenced by discontinuities such as cracks and joints. Considered with possibility of groundwater flow in massive rock mass of deep subsurface, the connectivity of micro cracks should be analyzed as a conduit of ground-water flow. The objective of this study is to estimate permeability characteristics of granite dependent on damage process with application of joint distribution analysis and modeling of permeability analysis in rock masses. In case of average permeability coefficients, the modeling results based on micro cracks data are well matched with the results from permeability tests. Based on the visualization result of three dimensional model, the average permeability coefficients through the discharge plane have a positive relationship with the number of microcrack induced by rock damage.

• Biotechnology and Bioprocess Engineering:BBE
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• 제4권1호
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• pp.72-77
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• 1999

An antibody containing a genetically engineered lipid group at the N-termunus and a hexahistidinyl tag at the C-terminus (Lpp-scF-His6) was immobilized in an oriented manner on the surface of liposome. Liposomes, consisting of antibody and phosphatidyl-choline, have been prepared and imaged by AFM. For AFM visualization, the resulting liposomes were bound on the surface of mica by two different mechanisms. The histidine tags present in the antibody molecules of the immonuliposome were anchored to the NiCl2 treated mica surface. Alternatively, the immunoliposomes were immunochemically bound on antigen-coated mica surface. Both approaches yielded liposomes which were clearly imaged without damage by AFM in ambient condition.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2007년도 추계학술대회
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• pp.101-104
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• 2007

Kiwifruit vines with broad leaves are easily torn or shed by high-speed wind. In this study, the threshold wind speed at which a cane is broken was investigated experimentally with varying physical parameters of a kiwifruit vine under two different ABL (atmospheric boundary layer) conditions. In addition, the temporal variation of wind-blown young canes was visualized using a high-speed camera. The average threshold wind speeds for ABL types A and B are about 20.5 m/s and 18.9 m/s, respectively. A wind-blown young cane takes periodic up-and-down motion when it is broken off. The mean motion frequency of young canes of the kiwifruit vines was found to be about 4.5Hz.

• Proceedings of the Korea Information Processing Society Conference
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• 한국정보처리학회 2022년도 추계학술발표대회
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• pp.100-101
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• 2022

본 논문에서는 폭우로 인한 피해를 줄이기 위해 공공데이터의 대피소 현황과 과거 침수, 범람 정보를 토대로 재난상황 발생시 시민들이 실시간으로 대비할 수 있는 재난대피소 시각화 시스템을 설계한다. 설계된 재난대피소 시각화 시스템은 인접한 대피소 안내, 과거 침수, 범람 구역 시각화, 예상 침수, 범람 구역 시각화 기능으로 구성되어 있다. 본 시스템을 통하여 시각화 된 예상 침수 구역을 기반으로 수방 시설 대비와 침수로 인한 피해를 최소화할 수 있을 것이다.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제19권5호
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• pp.1207-1212
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• 2015

In this paper, we propose three-dimensional (3D) visualization and recognition techniques of micro-objects under photon-starved conditions using photon counting integral imaging microscopy. To capture high resolution 2D images with different perspectives in the proposed method, we use Synthetic Aperture Integral Imaging (SAII). Poisson distribution which is mathematical model of photon counting imaging system is used to extract photons from the images. To estimate 3D images with 2D photon counting images, the statistical estimation is used. Therefore, 3D images can be obtained and visualized without any damage under photon-starved conditions. In addition, 3D object recognition can be implemented using nonlinear correlation filters. To prove the usefulness of our technique, we implemented the optical experiment.

• Journal of The Korean Association of Information Education
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• 제26권4호
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• pp.285-293
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• 2022

The COVID-19 outbreak, which took longer than expected, caused considerable damage to students' basic academic ability in mathematics. In this paper, a multiplication table practice application that can help students improve their basic multiplication arithmetic skills has been developed based on a cloud-service. The performance of the application was improved by integrating the Flutter framework, Google Cloud, and Google Sheets. As a result of applying this application to 72 6th graders in elementary schools located in K Metropolitan City, for one week. students' spending time required for solving multiplication table problems was reduced by more than 28% compared to the initial period, while students' learning data was able to be accurately collected without errors. It is hoped that the development case conducted through the Flutter framework in this study can lead to the development of other educational learning applications.

• The Journal of the Acoustical Society of Korea
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• 제39권1호
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• pp.16-23
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• 2020

In High-Intensity Focused Ultrasound (HIFU) treatment, effective localization of HIFU focus is important for developing a safe treatment plan. While Magnetic Resonance Imaging guided HIFU (MRIgHIFU) can visualize the ultrasound path during the treatment for localizing HIFU focus, it is challenging in ultrasound imaging guided HIFU (USIgHIFU). In the present study, a real-time ultrasound beam visualization technique capable of localizing HIFU focus is presented for USIgHIFU. In the proposed method, a short pulse, with the same center frequency of an imaging ultrasound transducer below the regulated acoustic intensity (i.e., Ispta < 720 mW/㎠), was transmitted through a HIFU transducer whereupon backscattered signals were received by the imaging transducer. To visualize the HIFU beam path, the backscattered signals underwent dynamic receive focusing and subsequent echo processing. From in vitro experiments with bovine serum albumin gel phantoms, the HIFU beam path was clearly depicted with low acoustic intensity (i.e., Ispta of 94.8 mW/㎠) and the HIFU focus was successfully localized before any damages were produced. This result indicates that the proposed ultrasound beam path visualization method can be used for localizing the HIFU focus in real time while minimizing unwanted tissue damage in USIgHIFU treatment.

• Composites Research
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• 제29권5호
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• pp.288-292
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• 2016

In this paper, a novel ultrasonic propagation imaging system, called a full-field pulse-echo ultrasonic propagation imaging (FF PE UPI) system is introduced. The system nondestructively inspected targets with two-axis translation stage. The coincident laser beams for ultrasonic sensing and generation are scanned and pulse-echo mode laser ultrasounds are captured. This procedure makes it possible to generate full-field ultrasound in through-the-thickness direction as large as the scan area. Structural inspection results in the form of full-field ultrasonic wave propagation videos are introduced, which are painted sandwich control surfaces. In addition, the inspection results of FF PE UPI system are compared with conventional ultrasonic testing methods such as waterjet and portable C-scan.