• Nuclear Engineering and Technology
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• 제53권7호
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• pp.2295-2303
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• 2021

To investigate wall-thinning impact on axial load resistance of Zircaloy-4 cladding rods after a LOCA transient, axial tensile samples have been machined on as-received tubes with reduced thicknesses between 370 and 580 ㎛. After high temperature oxidation under steam at 1200 ℃ with measured ECR ranging from 10 to 18% and water quenching, machined samples were axially loaded until fracture. These tests were modeled using a fracture mechanics approach developed in a previous study. Fracture stresses are rather well predicted. However, the slightly lower fracture stress observed for wall-thinned samples is not anticipated by this modeling approach. The results from this study confirm that characterizing the axial load resistance using semi-integral tests including the creep and burst phases was the best option to obtain accurate axial strengths describing accurately the influence of wall-thinning at burst region.

• International Journal of Internet, Broadcasting and Communication
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• 제14권2호
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• pp.98-108
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• 2022

In this study, social network analysis was performed to compare and analyze changes in domestic tourism trends before and after the outbreak of COVID-19 in a situation where the damage to the tourism industry due to COVID-19 is increasing. Using Textom, a big data analysis service, data were collected using the keywords "travel destination" and "travel trend" based on the collection period of 2019 and 2020, when the epidemic spread to the world and became chaotic. After extracting a total of 80 key words through text mining, centrality was analyzed using NetDraw of Ucinet6, and clustered into 4 groups through CONCOR analysis. Through this, we compared and analyzed changes in domestic tourism trends before and after the outbreak of COVID-19, and it is judged to provide basic data for tourism marketing strategies and tourism product development in the post-COVID-19.

• 대한임베디드공학회논문지
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• 제16권3호
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• pp.89-97
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• 2021

Voice interface can not only make daily life more convenient through artificial intelligence speakers but also improve the working environment of the factory. This paper presents a voice-assisted work management system that supports both speech and speaker recognition. This system is able to provide machine control and authorized worker authentication by voice at the same time. We applied two speech recognition methods, Google's Speech application programming interface (API) service, and DeepSpeech speech-to-text engine. For worker identification, the SincNet architecture for speaker recognition was adopted. We implemented a prototype of the work management system that provides voice control with 26 commands and identifies 100 workers by voice. Worker identification using our model was almost perfect, and the command recognition accuracy was 97.0% in Google API after post- processing and 92.0% in our DeepSpeech model.

• Nuclear Engineering and Technology
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• 제52권12호
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• pp.2887-2900
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• 2020

Cladding failure in a fuel rod during operation in a BWR is analyzed using a FALCON code-based model. Comparative calculation with a neighbouring, intact rod is presented, as well. A considerable 'hot spot' effect in cladding temperature is predicted with the SLICE-DO model due to a thermal barrier caused by the localized crud deposition. Particularly significant overheating is expected to occur on the affected side of the cladding of the failed rod, in agreement with signs of significant localized crud deposition as revealed by Post Irradiation Examination. Different possibilities (criteria) are checked, and Pellet-Cladding Mechanical Interaction (PCMI) is shown to be one of the plausible potential threats. It is shown that PCMI could lead to discernible concentrated inelastic deformation in the overheated part of the cladding. None of the specific mechanisms considered can be experimentally or analytically identified as an only cause of the rod failure. However, according to the current calculation, a possibility of cladding failure by PCMI cannot be excluded if the crud thickness exceeded 300 ㎛.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2011년도 춘계학술발표대회
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• pp.1513-1516
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• 2011

우편물 접수 대기시간 개선과 업무부하 경감을 위해 개발된 무인우편접수시스템의 창구형 무인우편접수 장치의 효율성을 위하여 실시간으로 우편물 접수 정보를 우체국 우편물류시스템에 전송하기 위한 인터페이스를 설계하고 REST 방식을 이용하여 개발하였다.

• Nuclear Engineering and Technology
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• 제56권2호
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• pp.728-744
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• 2024

The presence of hydrogen absorbed by zirconium-based cladding materials during reactor operation can trigger degradation mechanisms and endanger the rod integrity. Ensuring the durability of the rods in extended time-frames like dry storage requires anticipating hydrogen behavior using numerical modeling. In this context, the present paper describes a hydrogen post-processing tool for Falcon - HYPE, a PSI's in-house tool able to calculate hydrogen uptake, transport, thermochemistry, reorientation of hydrides and hydrogen-related failure criteria. The tool extracts all necessary data from a Falcon output file; therefore, it can be considered loosely coupled to Falcon. HYPE has been successfully validated against experimental data and applied to reactor operation and interim storage scenarios to present its capabilities.

• Nuclear Engineering and Technology
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• 제56권3호
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• pp.886-892
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• 2024

The cladding temperatures and axial mass distribution computed by MAAP5 were compared with their measured values in the test bundle of the Phebus Test FPT0. The computed cladding temperatures were in good agreed with the measured values in the pre-transient phase. In the transient heat-up phase, the computed temperatures were overestimated by the Baker-Just correlation in MAAP5, but the computed temperatures could simulate the subsequently measured values. The computed mass distribution in the axial direction was in qualitative agreement with the measured one for post-test fuel damage observations. The calculated flow areas of inner and outer regions in the test bundle were compared with the photographic observations. MAAP5 computed them at the height of 0.2 m where the molten pool formed was in qualitative agreement with the photographic observations. It was found that the remaining steam flow paths might be caused by the gas-liquid two-phase flow counter-current flow limitation.

• Nuclear Engineering and Technology
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• 제56권4호
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• pp.1277-1283
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• 2024

This study presents a radiation-induced thermal conductivity degradation (TCD) model of zirconium as compared to the conventional UO2 TCD model. We derived the governing factors of the radiation-induced TCD model, such as maximum TCD value and temperature range of TCD. The maximum TCD value was derived by two methods, in which 1) experimental result of 32 % TCD was directly utilized as the maximum TCD value and 2) a theoretical approach based on dislocation was applied to derive the maximum TCD value. Further, the temperature range of TCD was determined to be 437-837 K by 1) experimental results of post-annealing of irradiation hardening as compared to 2) the rate theory and thermal equilibrium. Consequently, the radiation-induced TCD model of zirconium was derived to be $f_r=1-{\frac{0.32}{1+{\exp}\,\{(T-637)/45\}}}$. Because the thermal conductivity of zirconium is one of the factors determining the storage and transport system, this newly proposed model could improve the safety analysis of spent fuel storage systems.

• 한국산학기술학회논문지
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• 제22권2호
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• pp.127-133
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• 2021

낙상 판단을 위한 최근 발표되는 연구는 RNN(Recurrent Neural Network)을 이용한 낙상 동작 특징 분석과 동작 분류에 집중되어 있다. 웨어러블 센서를 기반으로 한 접근 방식은 높은 탐지율을 제공하나 사용자의 착용 불편으로 보편화 되지 못했고 최근 영상이나 이미지 기반에 딥러닝 접근방식을 이용한 낙상 감지방법이 소개 되었다. 본 논문은 2D RGB 저가 카메라에서 얻은 영상을 PoseNet을 이용해 추출한 인체 골격 키포인트(Keypoints) 정보로 머리와 어깨의 키포인트들의 위치와 위치 변화 가속도를 추정함으로써 낙상 판단의 정확도를 높이기 위한 감지 방법을 연구하였다. 특히 낙상 후 자세 특징 추출을 기반으로 Convolutional Neural Networks 중 Gated Recurrent Unit 기법을 사용하는 비전 기반 낙상 감지 솔루션을 제안한다. 인체 골격 특징 추출을 위해 공개 데이터 세트를 사용하였고, 동작분류 정확도를 높이는 기법으로 코, 좌우 눈 그리고 양쪽 귀를 포함하는 머리와 어깨를 하나의 세그먼트로 하는 특징 추출 방법을 적용해, 세그먼트의 하강 속도와 17개의 인체 골격 키포인트가 구성하는 바운딩 박스(Bounding Box)의 높이 대 폭의 비율을 융합하여 실험을 하였다. 제안한 방법은 기존 원시골격 데이터 사용 기법보다 낙상 탐지에 보다 효과적이며 실험환경에서 약 99.8%의 성공률을 보였다.

• 한국콘텐츠학회논문지
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• 제20권12호
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• pp.154-165
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• 2020

COVID-19 팬데믹의 장기화로 인해 우리는 유례없는 사회경제적 위협에 직면해 있다. 인적 교류의 통제로 보건의료 측면에서의 위협 뿐 아니라 경제 활동 위축에 따른 부담에까지 동시에 노출되어 있다. 이러한 상황은 우리가 그간 위기상황에 대비해 마련해 놓았던 사회안전망에 대해 재점검해 볼 기회를 마련해 주었다. 본 연구는 이러한 맥락에서 사회안전망에 대한 평가가 정부의 신뢰도 및 정부 주도의 증세 정책에 대한 수용에 미치는 영향력을 살펴보고자 하였다. 이를 위해 본 연구는 COVID-19가 팬데믹 국면으로 접어든 이후인 2020년 5월, 전국의 성인남녀 1000명을 대상으로 시행한 설문조사의 자료를 토대로 분석을 시행하였다. 분석 결과, COVID-19 발발 이후 우리나라의 사회안전망에 대한 평가는 정부에 대한 신뢰에 정(+)의 영향력을 미치고 있었으며, 이는 개인의 증세 정책에 대한 수용을 보다 증진시키는 것으로 나타났다. 아울러, 정부 신뢰의 증세 수용에 대한 정(+)의 영향력은 소득 수준이 높아질 때 보다 증폭되는 것으로 확인되었다. 이러한 일련의 결과는 향후 코로나 이후를 대비한 정책과 시스템의 재정비에 있어 이론적 기틀을 마련하는데 도움을 줄 수 있을 것이다.