• Transactions of the Korean Society of Pressure Vessels and Piping
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• 제18권1호
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• pp.19-25
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• 2022

Nuclear Power Plants (NPP) should be designed to have sufficient safety margins and to ensure seismic safety against earthquake that may occur during the plant life time. After the 9.12 Gyeongju earthquake accident, the structural integrity of nuclear power plants due to the beyond design basis earthquake is one of key safety issues. Accordingly, it is necessary to conduct structural integrity evaluations for domestic NPPs under beyond design basis earthquake. In this study, the Level 3 LBB (Leak Before Break) evaluation was performed by considering the beyond design basis earthquake for the surge line of a OPR1000 plant of which design basis earthquake was set to be 0.2g. The beyond design basis earthquake corresponding to peak ground acceleration 0.4g at the maximum stress point of the surge line was considered. It was confirmed that the moment behaviors of the hot leg and pressurized surge nozzle were lower than the maximum allowable loading in moment-rotation curve. It was also confirmed that the LBB margin could be secured by comparing the LBB margin through the Level 2 method. It was judged that the margin was secured by reducing the load generated through the compliance of the pipe.

• Clinics in Shoulder and Elbow
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• 제26권4호
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• pp.406-415
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• 2023

Background: Surgical management of a massive rotator cuff tear (RCT) is always challenging. This study describes the clinical and radiological outcomes of patients who underwent bridging grafts using a plantaris tendon for an irreparable RCT. Methods: Thirteen patients with a massive RCT were treated with arthroscopic interposition of a folded plantaris tendon autograft between June 2017 and January 2020. For clinical evaluation, a visual analog scale (VAS), American Shoulder and Elbow Surgeons (ASES) score, Disabilities of the Arm, Shoulder, and Hand (DASH) score, Constant-Murley score, and range of motion values were collected. For radiographic evaluation, standardized magnetic resonance imaging and ultrasonography were performed to check the integrity of the interposed tendon. Results: A statistically significant improvement at the final follow-up was evident in scores for the VAS (-3.0, P=0.003), ASES (24.9, P=0.002), D ASH (-20.6, P=0.001), and Constant-Murley values (14.2, P=0.010). In addition, significant improvement was shown in postoperative flexion (17.3°, P=0.026) and external rotation (27.7°, P<0.001). In postoperative radiologic evaluations, the interposed tendons were intact at the last examination in 12 of the 13 patients. No complications related to donor sites were reported. Conclusions: An arthroscopic bridging graft for irreparable RCTs using a modified Mason-Allen stitch and a plantaris autograft resulted in improved short-term radiological and clinical outcomes. Graft integrity was maintained for up to 2 years in most patients. Level of evidence: IV.

• Journal of Biomedical Engineering Research
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• 제44권6호
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• pp.428-442
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• 2023

In this study, we have a goal to develop usability evaluation guidelines for heuristic-based artificial intelligence-based Software as a Medical Device (SaMD) in the medical field. We conducted a gap analysis between medical hardware (H/W) and non-medical software (S/W) based on ten heuristic principles. Through severity assessments, we identified 69 evaluation domains and 112 evaluation criteria aligned with the ten heuristic principles. Subsequently, we categorized each evaluation domain into five types, including user safety, data integrity, regulatory compliance, patient therapeutic effectiveness, and user convenience. We proposed usability evaluation guidelines that apply the newly derived heuristic-based Software as a Medical Device (SaMD) evaluation factors to the risk management process. In the discussion, we also have proposed the potential applications of the research findings and directions for future research. We have emphasized the importance of the judicious application of AI technology in the medical field and the evaluation of usability evaluation and offered valuable guidelines for various stakeholders, including medical device manufacturers, healthcare professionals, and regulatory authorities.

• Journal of the Korean Society for Nondestructive Testing
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• 제5권2호
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• pp.22-33
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• 1986

The application and development of on-line monitoring technology of AE to surveillance of crack propagation will contribute to the structural integrity of reactor pressure vessel and piping system. This research has been performed in order to obtain the evaluation technology for source location of AE and the analysis for the AE signal of the welded specimen. AE is detected by 4-channels AE system during pressurization in small pressure vessels. The cracking of artificial defects can be accurately located and categorized in real time. The welded specimens have more events rate and higher amplitude than the weldless less specimens, and the events rate have a peak around the yield point and just before the failure under tensile test.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.281-286
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• 2007

Needs of fuel's performance evaluation for the dual-cooled fuel pellet (annular shape) necessitate the irradiation test in the test reactor. Irradiation test rig for the HARARO reactor, which is a special-purposed equipment used for material, irradiation and creep test, must satisfy the operational requirement on the hydraulic characteristics and structural integrity. In this paper, pressure drop and flow-induced vibration test for the newly developed non-instrumented test rig were carried out using FIVPET as a out-pile evaluation test. The test results show that the new test rig satisfy the HANARO operational requirement with sufficient margin. The spectral response characteristics of the flow-induced vibration of the test rid were also discussed.

• Journal of the Korean Society for Precision Engineering
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• 제19권2호
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• pp.58-64
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• 2002

In these days, according to increasing the technical development, the dimension of a product goes up for ultra-precision. For the net shape manufacturing, grinding is a important process that influences directly the accuracy and the integrity of produced products. In this study, an experimental evaluation was carried out. Workpiece materials were used STD11, SUS304, and STB2 in accordance with varing condition of feedrate and depth of cut. From measuring the grinding force and the surface roughness, material characteristics of grinding by using CBN wheel were examined.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• 제5권1호
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• pp.14-19
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• 2009

NDE(Nondestructive examination) detects a flaw or discontinuity in materials. Flaws detected by the examination shall be evaluated for the decision basis of the integrity. The internal flaws of forging products can be detected by UT. However, UT has detection limits because of its reflected signal weakness. Normally, a 1mm or less flaw is known as the limit. If a flaw was detected, the size of flaw would be evaluated by AVG(or DGS) technique. To verify the evaluation data, alternative examination methods are needed. But there is no alternative examination methods until now. In this study, Phased array ultrasonic technique can be used to size the flaws in the generator rotor with focused beam of ultrasonic wave as a supplement method of AVG. Also, the phased array ultrasonic technique described enables the shape of flaw to be depicted exactly.

• Corrosion Science and Technology
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• 제14권1호
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• pp.33-39
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• 2015

Pipe wall-thinning by flow-accelerated corrosion and various types of erosion is significant damage in secondary system piping of nuclear power plants(NPPs). All NPPs in Korea have management programs to ensure pipe integrity from degradation mechanisms. Ultrasonic test(UT) is widely used for pipe wall thickness measurement. Numerous UT measurements have been performed during scheduled outages. Wall-thinning rates are determined conservatively according to several evaluation methods developed by Electric Power Research Institute(EPRI). The issue of reliability caused by measurement error should be considered in the process of evaluation. The reliability analysis method was developed for single and multiple measurement data in the previous researches. This paper describes the application results of reliability analysis method to real measurement data during scheduled outage and proved its benefits.

• Proceedings of the KSME Conference
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.49-54
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• 2001

Measurement of welding residual stresses is one of important tasks to assess the structural integrity of welded structures. For operating components, especially, nondestructive techniques are required. By now, authors have proposed a new residual stress evaluation method, the bead flush method, where residual stresses are calculated from eigenstrain distribution determined by surface removal of reinforcement. In this paper, a brief description of the bead flush method is given and its utility and problem to be overcome are discussed. And also stabilization method of solution set of eigenstrain in inverse analysis is proposed.

• Proceedings of the Korean Nuclear Society Conference
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• 한국원자력학회 1998년도 춘계학술발표회논문집(2)
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• pp.795-801
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• 1998

Metallic fatigue of Pressurized Water Reactor(PWR) materials is a generic safety issue for commercial nuclear power plants. It is very important to obtain the fatigue usage factor for component integrity and life extension. In this paper, fatigue usage was obtained at the inside surface of Kori unit 2, 3 and 4 RCP casing weld, based on the design transient. And it was intended to establish the procedure and the detailed method of fatigue evaluation in accordance with ASME Section III Code. According to this code rule, two methods to determine the stress cycle and the number of cycles could be applied. One method is the superposition of cycles of various design transients and the other is based on the assumption that a stress cycle correspond to only one design transient. Both method showed almost same fatigue usage in the RCP casing weld.