• Structural Engineering and Mechanics
• /
• 제77권2호
• /
• pp.197-215
• /
• 2021

Under a severe environment of multiple hazards such as earthquakes and winds, the life-cycle performance of engineering structures may inevitably be deteriorated due to the fatigue effect caused by long-term exposure to wind loads, which would further increase the structural vulnerability to earthquakes. This paper presents a framework for evaluating the lifetime structural seismic performance under the effect of wind-induced fatigue considering different sources of uncertainties. The seismic behavior of a high-rise steel-concrete composite frame with buckling-restrained braces (FBRB) during its service life is systematically investigated using the proposed approach. Recorded field data for the wind hazard of Fuzhou, Fujian Province of China from Jan. 1, 1980 to Mar. 31, 2019 is collected, based on which the distribution of wind velocity is constructed by the Gumbel model after comparisons. The OpenSees platform is employed to establish the numerical model of the FBRB and conduct subsequent numerical computations. Allowed for the uncertainties caused by the wind generation and structural modeling, the final annual fatigue damage takes the average of 50 groups of simulations. The lifetime structural performance assessments, including static pushover analyses, nonlinear dynamic time history analyses and fragility analyses, are conducted on the time-dependent finite element (FE) models which are modified in lines with the material deterioration models. The results indicate that the structural performance tends to degrade over time under the effect of fatigue, while the influencing degree of fatigue varies with the duration time of fatigue process and seismic intensity. The impact of wind-induced fatigue on structural responses and fragilities are explicitly quantified and discussed in details.

• 한국전자통신학회논문지
• /
• 제16권6호
• /
• pp.1101-1112
• /
• 2021

정보가 조직의 핵심 관리 요인으로 인식되면서, 조직들은 정보 자산에 대한 침입 및 노출에 대처하기 위하여 정보보안 정책 및 기술에 대한 투자를 지속해서 증가하고 있다. 그러나, 엄격한 정보 관리를 위한 조직의 규정 및 행동 요구가 많아질수록, 실제 정보보안 정책을 업무에 적용하는 조직원에게는 스트레스를 일으켜 부정적 행동을 유발할 수 있다. 본 연구는 스트레스 조건이 긍정적, 부정적 행동 원인으로 작용하는 도전적, 방해적 스트레서가 정보보안 준수의도에 미치는 영향을 제시하고, 진성 리더십이 스트레서의 영향을 어떻게 조절하는지를 확인하는 것을 목적으로 한다. 연구 대상은 보안 정책을 업무에 적용하고 있는 조직 근로자로 하였으며, 서베이 기법을 적용하여 선행연구를 통해 도출한 측정 항목의 응답 결과를 확보하였다. 구조방정식모델링을 통해 검증한 결과, 도전적, 방해적 스트레서가 준수 의도에 영향을 주었으며, 진성 리더십이 스트레서의 영향을 조절하였다. 결과는 내부자의 보안 준수 수준에 영향을 주는 스트레서 조건과 리더의 행동 방향을 제시하였기 때문에, 내부자 정보보안 목표 달성을 위한 구성원 지원 전략 수립에 도움을 준다.

• 대한토목학회논문집
• /
• 제42권1호
• /
• pp.107-116
• /
• 2022

최근 안전점검자가 접근성 문제로 점검이 어려운 교량 부재의 상태평가를 위해 영상분석 기반의 시설물 점검 기법연구가 활발히 진행 중이다. 본 논문은 교량을 대상으로 딥러닝 기반 영상정보에 대해서 상태평가 연구를 진행하였고 이에 대한 평가 프로그램(프로토타입)을 개발하였다. 딥러닝 기반 교량 손상탐지 프로토타입을 개발하기 위해 딥러닝 모델 중 손상 검출 및 정량화가 가능한 의미론적 분할 모델인 Mask-RCNN를 적용하였고 학습데이터 6,540장(오픈 데이터 포함)과 손상유형에 적합한 레이블링을 구성하였다. 모델링에 대한 성능검증한 결과, 콘크리트 균열, 박리/박락, 철근노출과 도장 박리에 대한 정밀도(precision)는 95.2 %, 재현율(recall)은 93.8 % 나타내었다. 또한, 교량 콘크리트 부재 손상율을 이용하여 콘크리트 균열 실 데이터를 2차 성능검증 하였다.

• Nuclear Engineering and Technology
• /
• 제54권10호
• /
• pp.3855-3863
• /
• 2022

An evaluation of the radiation shielding performance of high-Z-particle-loaded polylactic acid (PLA) composite materials was pursued. Specimens were produced via fused deposition modeling (FDM) using copper-PLA, steel-PLA, and BaSO₄-PLA composite filaments containing 82.7, 75.2, and 44.6 wt% particulate phase contents, respectively, and were tested under broad-band flash x-ray conditions at the Sandia National Laboratories HERMES III facility. The experimental results for the mass attenuation coefficients of the composites were found to be in good agreement with GEANT4 simulations carried out using the same exposure conditions and an atomistic mixture as a model for the composite materials. Further simulation studies, focusing on the Cu-PLA composite system, were used to explore a shield design parameter space (in this case, defined by Cu-particle loading and shield areal density) to assess performance under both high-energy photon and electron fluxes over an incident energy range of 0.5-15 MeV. Based on these results, a method is proposed that can assist in the visualization and isolation of shield parameter coordinate sets that optimize performance under targeted radiation characteristics (type, energy). For electron flux shielding, an empirical relationship was found between areal density (AD), electron energy (E), composition and performance. In cases where ${\frac{E}{AD}}{\geq}2MeV{\bullet}cm{\bullet}g^{-1}$, a shield composed of >85 wt% Cu results in optimal performance. In contrast, a shield composed of <10 wt% Cu is anticipated to perform best against electron irradiation when ${\frac{E}{AD}}<2MeV{\bullet}cm{\bullet}g^{-1}$.

• Clinical and Experimental Pediatrics
• /
• 제65권2호
• /
• pp.85-89
• /
• 2022

Background: There is evidence of a relationship between prenatal excess androgen exposure and central nervous developmental problems and attention-deficit/hyperactivity disorder (ADHD) in the offspring of mothers with polycystic ovary syndrome (PCOS). Purpose: Here we aimed to use a meta-analysis to investigate whether the offspring of mothers with PCOS are at an increased chance of developing ADHD. Methods: Three main English databases were searched for articles published through December 2020. The Newcastle-Ottawa Scale was used to assess study quality. Study heterogeneity was determined using I² statistics and publication bias was assessed using Begg and Egger tests. The results are presented as odds ratio (OR) and relative ratio (RR) estimates with 95% confidence intervals (CIs) using a random-effects model. Results: Six articles (3 cohort and 3 case-control studies; 401,413 total ADHD cases) met the study criteria. Maternal PCOS was associated with an increased risk of ADHD in the offspring based on OR and RR (OR, 1.42; 95% CI, 1.27-1.57) and (RR, 1.43; 95% CI, 1.35-1.51), respectively. There was no heterogeneity among the included articles based on OR (I²=0.0%, P=0.588) and RR (I²=0.0%, P=0.878). Conclusion: Our study showed that maternal PCOS is a risk factor for ADHD. Therefore, screening their offspring for ADHD should be considered part of the comprehensive clinical care of women with PCOS.

• Current Optics and Photonics
• /
• 제6권2호
• /
• pp.202-211
• /
• 2022

In the pasteurization of escalator handrails using ultraviolet (UV) sterilizers, a combination of light distribution and escalator speed has priority over other important factors. Furthermore, since part of the escalator handrail has a curved structure, proper design is needed to improve the sterilization rate on the surfaces touched by users. In this paper, two types of sterilizers satisfying these conditions are manufactured with 275-nm UV-C LEDs, after modeling the three-dimensional (3D) structure of an escalator handrail and simulating optical distributions of UV-C irradiation on the handrail's surface according to light-emitting diode (LED) positions and reflector variations in the sterilizers. Pasteurization experiments with the UV-C LED sterilizers are conducted on six types of gram-positive and gram-negative bacteria, with exposure times of 0.2, 5, and 15 s at an actual installation distance of 20 mm. The sterilization rates for the gram-positive bacteria are 10.63% to 27.94% at 0.2 s, 89.44% to 96.30% at 5 s, and 99.64% to 99.88% at 15 s. Those for the gram-negative bacteria are 57.70% to 77.63% at 0.2 s, 98.90% to 99.49% at 5 s, and 99.88% to 99.99% at 15 s. The power consumption of the UV-C LED sterilizer is about 8 W, which can be supplied by a self-generation module instead of an external power supply.

• 한국군사과학기술학회지
• /
• 제26권1호
• /
• pp.102-112
• /
• 2023

This research mainly focuses on the transport and dispersion of chemical agent plume according to the Lagrangian Puff Model and Lagrangian Particle Model of NBC_RAMS(Nuclear, Biological, Chemical Reporting And Modeling S/W System). NBC_RAMS was developed with the purposes of estimating the fate of Chemical, Biological, and Radioactive(CBR) agent plumes and evaluating damages in the Republic of Korea. First, it calculates the local weather pattern, i.e. wind speed, wind direction, and temperature, by considering the effects of land uses and topography. The plume behaviors are calculated by adopting the Lagrangian Puff Model(LPFM) or Lagrangian Particle Model(LPTM). In this research, we assumed a virtual chemical agent exposure event in a stable atmospheric condition during the summer season. The plume behaviors were estimated by both LPFM and LPTM on the used area(urbanized and dry area) and the agricultural land. The higher heat flux in the used area led to stronger winds and further downward movement moving of the chemical agent than the farmland. The lateral dispersion of the chemical plume was emphasized in the Lagrangian Puff Model because it adopted Gaussian distribution.

• 생물정신의학
• /
• 제30권1호
• /
• pp.17-23
• /
• 2023

Objectives This study aims to develop valid experimental models for depression through chronic reserpine exposure to zebrafish (Danio rerio). Methods The effect of chronic reserpine on zebrafish behavior in the novel tank was examined. Changes of gene expression on telencephalon were also investigated. Results Chronic reserpine (40 mg/L, 7 days) induced overt behavioral effects, but markedly reduced activity, resembling motor retardation in depression. In telencephalon of zebrafish, gene expression associated with monoamine oxidase and norepinephrine transporter was decreased. Expression of serotonin transporter gene was increased. Conclusions Our results show that the pharmacological model of depression in zebrafish can induce not only behavioral changes, but also monoamine changes in the homology of human mood regulation centers.

• 한국환경복원기술학회지
• /
• 제26권3호
• /
• pp.29-42
• /
• 2023

As the destruction of habitats due to recent development continues, there is also increasing interest in endangered species. Mankyua chejuense is a vulnerable species that is sensitive to changes in population and habitat, and it has recently been upgraded from Endangered Species II to Endangered Species I, requiring significant management efforts. So in this study, we analyzed the potential habitats of Mankyua chejuense using MaxEnt(Maximum Entropy) modeling. We developed three models: one that considered only environmental characteristics, one that considered artificial factors, and one that reflected the habitat of dominant tree species in the overstory. Based on previous studies, we incorporated environmental and human influence factors for the habitats of Mankyua chejuense into spatial information, and we also used the habitat distribution models of dominant tree species, including Ulmus parvifolia, Maclura tricuspidata, and Ligustrum obtusifolium, that have been previously identified as major overstory species of Mankyua chejuense. Our analysis revealed that rock exposure, elevation, slope, forest type, building density, and soil type were the main factors determining the potential habitat of Mankyua chejuense. Differences among the three models were observed in the edges of the habitats due to human influence factors, and results varied depending on the similarity of the habitats of Mankyua chejuense and the dominant tree species in the overstory. The potential habitats of Mankyua chejuense presented in this study include areas where the species could potentially inhabit in addition to existing habitats. Therefore, these results can be used for the conservation and management planning of Mankyua chejuense.

• 한국전자통신학회논문지
• /
• 제18권6호
• /
• pp.1197-1206
• /
• 2023

가상현실로 구현한 공중화장실의 위험도를 산출하기 위하여 공중화장실에 존재하는 공간요소를 평가하고자 하였다. 평가대상과 평가 기준에 이론적 기반을 마련하기 위해 공중화장실의 안전성을 높이기 위한 체크리스트를 제안한 선행연구를 도입하였다. 평가 기준을 설정하기 위해 Paul J. Brantingham과 Patricia L. Brantingham의 이론을 바탕으로 공간과 범죄자의 상호작용에 초점을 맞춰 분석하고 수립하였다. Ronald V. Clarke의 "일상활동 이론"도 도입하여 평가 접근 방식에 통합하였다. 공중화장실의 범죄자, 이용자, 공간적 요소 간의 상관관계를 토대로 범인의 행위, 범죄와의 공간적 관련성, 이용 중 이용자 노출을 분석하였다. 이러한 기준을 이용하여 공중화장실의 공간요소 평가 알고리즘을 개발하고 이를 기반으로 애플리케이션을 개발하여 평가 도구 개발이 가능함을 입증하였다.