• 한국표면공학회지
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• 제53권3호
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• pp.116-123
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• 2020

Ion beam irradiation induces self-organization of nanostructure on the surface of polymer film. We show that the incident angle of Ar ions on polyethylene naphthalate(PEN) film changes self-organized nanostructure. PEN film was irradiated by argon ion beams with the ion incident angle of 0°, 30°, 45°, 60°, and 80°. Nanostructure was altered from dimple to ripple structure as the angle increases. The ripple structure changed to pillar structure after 60°due to that the shallow incident angle increased the ion energy transfer per depth up to 50 eV/Å, which value could induce excessive surface heating and oligomer formation reacting as a physical mask for anisotropic etching. And quantitative analysis of the nanostructures was adapted by using ABC model and fractal dimension theory.

• 한국해양공학회지
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• 제33권2호
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• pp.123-130
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• 2019

The flow around a curved riser exposed to the current in various directions was investigated at a Reynolds number of 100 using a numerical simulation. The present study found that the flow features of the curved riser were distinct from those of a straight riser as a result of its large radius of curvature. Namely, there were various wake patterns according to the flow's incident angle. As the incident angle increased from $0^{\circ}$ to $90^{\circ}$, a two-row street of vortices that developed along the centerline of the curved riser became more apparent. However, when the incident angle approached $180^{\circ}$ from $90^{\circ}$, these vortices were completely suppressed by the interaction between the wake and an axial flow induced by the curvature of the riser. To identify this feature, the sectional force coefficients were also considered, and it was found that the force coefficients could be different from those found in a sectional analysis based on the strip theory when investigating vortex-induced vibration. As a result, this kind of study would be important to realistically estimate the riser VIV (vortex-induced vibration) and fatigue life, and a new force coefficient database that includes the three-dimensional effect should be established.

• Journal of Korean Biological Nursing Science
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• 제25권2호
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• pp.95-104
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• 2023

Purpose: The purpose of this study was to analyze the trends and characteristics of infection-related patient safety incident reporting before and during the coronavirus disease 2019 (COVID-19) pandemic in Korea, and to provide basic data for preventing infection-related patient safety incidents and improving their management. Methods: A cross-sectional analysis of secondary national data (Patient Safety Reporting Data) was conducted. In total, 517 infection-related patient safety incidents reported from 2018 to 2021 were analyzed. Changes in the number of reports before and during the COVID-19 pandemic and differences in variables related to infection-related patient safety incidents were analyzed using the chi-square test and independent t-test in SPSS 29.0. Results: This study found that infection-related patient safety incidents decreased during the COVID-19 pandemic compared to before the pandemic. Furthermore, incident-related characteristics, such as the type of healthcare organization, severity of harm, and post-incident actions, changed during the COVID-19 pandemic. Conclusion: The many changes in the infection control system and practices during the COVID-19 pandemic may have contributed to a decrease in the reporting of infection-related patient safety incidents. It is hoped that longitudinal studies on patient safety incidents related to the pandemic and analytical studies on factors influencing patient safety incidents will continue to be conducted to prevent and improve patient safety incidents.

• 한국가스학회:학술대회논문집
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• 한국가스학회 2007년도 춘계학술발표회 논문집
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• pp.180-185
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• 2007

Likelihood analysis was used for the revision of release probability/frequency in chlorine Injection facilities used in chlorine process. Typically these facilities consist of pressure cylinder, vaporizer, pipeline, measuring equipment and safety equipment. This paper described the incident scenarios considered, likelihood analysis procedure and the selection and application of basic events and for failure rates of mechanical components. Human errors were also considered. The major objective of this paper is to estimate the likelihood of each determined incident scenarios. We estimated failure rates of mechanical components based on likelihood analysis procedure. Human errors were also considered. It was estimated to have $5.73{\times}10^{-5}\;Cl_2$ leak per year during the major $Cl_2$ handling process. The probability of failure in scrubber system was $4.11{\times}10^{-2}/demand$.

• Structural Engineering and Mechanics
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• 제69권2호
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• pp.177-191
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• 2019

The local topography has a significant effect on the characteristics of seismic ground motion. This paper investigates the influence of topographic effects on the seismic response of a train-bridge system. A 3-D finite element model with local absorbing boundary conditions is established for the local site. The time histories of seismic ground motion are converted into equivalent loads on the artificial boundary, to obtain the seismic input at the bridge supports. The analysis of the train-bridge system subjected to multi-support seismic excitations is performed, by applying the displacement time histories of the seismic ground motion to the bridge supports. In a case study considering a bridge with a span of 466 m crossing a valley, the seismic response of the train-bridge system is analyzed. The results show that the local topography and the incident angle of seismic waves have a significant effect on the seismic response of the train-bridge system. Leaving these effects out of consideration may lead to unsafe analysis results.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.743-754
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• 2020

This study provides an insight of the nonlinear behavior of the Offshore Wind Turbine (OWT) structure using the distributed plasticity approach. The fiber section beam-column element is applied to construct the finite element model. The accuracy of the proposed model is verified using linear analysis via the comparison of the dynamic characteristics. For collapse risk assessment of OWT, the nonlinear effects considering the earthquake Incident Angle (IA) have been evaluated first. Then, the Incremental Dynamic Analysis (IDA) has been executed using a set of 20 near-fault records. Lastly, fragility curves are developed to evaluate the vulnerability of structures for different limit states. Attained results justify the accuracy of the proposed approach for the structural response against the ground motions and other environmental loads. It indicates that effects of static wind and wave loads along with the earthquake loads should be considered during the risk assessment of the OWT structure.

• 한국산학기술학회논문지
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• 제17권4호
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• pp.332-339
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• 2016

본 연구는 유해 화학 물질 방출에 의해 손상 받은 환자들을 대상으로 중증 화상에 관하여 연관된 요인들의 강도를 밝힘을 목적으로 하였다. 2010년 1월 1일부터 2014년 12월 31일 까지 화학 손상으로 본원 응급실을 방문했던 총 446명의 환자를 조사 하였다. 중증 화상은 화학 손상의 중증도를 대변하는 종속변수로 사용되었다. 중증 화상과 관련이 있는 독립변수들을 밝혀내기 위한 통계 방법으로 카이 제곱 검정(Chi-square test, CST)과 이분형 로지스틱 회귀분석(Binary logistic regression test, BLRA)이 사용되었다. CST상, 중증 화상에 관하여 여성과 사고 현장에 있던 군, 다발 부위 손상 군이 동시에 연관성을 보였다(p<0.05). BLRA상 사고 현장에 있던 군과 폭발 군에 비하여 누출 군과 입원 군에 비하여 퇴원 군이 동시에 중증 화상과 관련 있었다(p<0.05). 본 연구에서는 사고 현장에 존재 여부가 중증 화상에 관하여 가장 중요한 요인 이었다. 뿐만 아니라 성별과 손상의 개수, 사고 노출 기전(폭발에 비해 누출), 응급실 진료 후 배치(입원에 비해 퇴원)가 또한 중증 화상과 관련이 있었다.

• 디지털융복합연구
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• 제10권6호
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• pp.205-211
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• 2012

허베이스피리트호 사고로 인해 원유 $12,547k{\ell}$가 해상에 유출되어 총 4만여 가구의 주민들이 피해를 입었으며, 태안군을 포함한 11개 시 군이 특별재난구역으로 선포되었다. 이러한 대형 유류오염사고는 자연환경파괴 뿐만 아니라 지역의 주변환경 변화에 중대한 영향을 주게 된다. 본 연구에서는 허베이스피리트호 유류오염사고 피해가 가장 큰 지역인 태안을 중심으로 유류오염사고가 피해지역 주변환경에 미치는 영향을 조사 분석하였다. 조사항목은 크게 인구변화, 지역경제변화, 주민건강영향, 지역사회갈등 등으로 구분하여 수행하였다. 이러한 분석결과는 향후 유류사고 발생시 피해지역에 미치는 직 간접적인 영향을 예측하고 정부의 효율적인 정책방안을 수립하는데 매우 중요한 요소로 활용될 수 있을 것이다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2010년도 춘계학술대회
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• pp.285-288
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• 2010

중국의 해커가 제3국으로 한국IP를 우회 접속하여 전자상거래사이트를 해킹하여, 대포계좌로 금융피해를 입히는 한 침해사고가 났었다. 7.7 DDoS공격은 국가의 주요사이트를 마비시킨 해커의 공격사건이었다. 본 논문에서는 해커의 침해사고와 DDoS공격에 취약점 분석을 한다. 해커의 공격에 대한 전조 증상 및 공격 연관성 분석을 통하여 실시간으로 Red, Orange, Yellow, Green에 속하는 위험등급을 나눈다. 해커에 대한 블랙리스트를 작성하여 실시간으로 공격을 차단 방어하는 보안공조시스템을 연구한다. 침해사고 후 패킷에 대한 역추적과 탐지를 통해 포렌식 자료를 생성하고 법정에서 책임소재의 증거로 확정하는 연구를 하여 국가 침해사고 대응과 포렌식 기술 발전에 기여한다.

• 한국ITS학회 논문지
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• 제20권1호
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• pp.86-99
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• 2021

교통혼잡을 완화하기 위한 방안 중 하나로 도로 이용자에게 교통상황 예측정보를 제공함으로써 교통량을 분산 시켜 도로 이용 효율을 증대시키는 방법이 있다. 이를 위해서는 신뢰성이 보장되고 정량적인 실시간 교통 속도 예측이 필수적이다. 본 연구에서는 상황별 교통속도 분석을 기반으로 이력 속도 데이터와 이력 속도 외의 교통류에 상관관계가 있는 데이터를 LSTM 입력 데이터로 활용하였다. 정상 교통류 상황에 대응하여 속도를 예측하는 LSTM 모델과 유고상황에 대응하여 속도를 예측하는 CNN-LSTM 모델을 개발하여 유고발생 후 1시간까지 5분 단위로 교통속도 예측을 시도하였다. 모델의 검증은 테스트 데이터를 통하여 교통상황별 예측성능을 분석하였다. 그 결과 정상 교통류에서는 평균 7.43km/h, 유고상황에서는 7.66km/h의 오차율로 각각 예측되었다.