• Earthquakes and Structures
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• 제4권1호
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• pp.109-132
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• 2013

Current codes incorporate simplified methods for the prediction of acceleration demands on secondary structural and non-structural elements at different levels of a building. While the use of simple analysis methods should be advocated, damage to both secondary structural and non-structural elements in recent earthquakes have highlighted the need for improved design procedures for such elements. In order to take a step towards the formation of accurate but simplified methods of predicting floor spectra, this work examines the floor spectra on elastic and inelastic single-degree of freedom systems subject to accelerograms of varying seismic intensity. After identifying the factors that appear to affect the shape and intensity of acceleration demands on secondary structural and non-structural elements, a new series of calibrated equations are proposed to predict floor spectra on single degree of freedom supporting structures. The approach uses concepts of dynamics and inelasticity to define the shape and intensity of the floor spectra at different levels of damping. The results of non-linear time-history analyses of a series of single-degree of freedom supporting structures indicate that the new methodology is very promising. Future research will aim to extend the methodology to multi-degree of freedom supporting structures and run additional verification studies.

• 한국전산유체공학회지
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• 제14권2호
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• pp.9-18
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• 2009

The cargo containment system (CCS) for ships carrying cryogenic fluid consists of at least two levels of barriers and insulation layers. It is because, even though there is a small amount of leak through the primary barrier, the liquid tight secondary barrier blocks further leakage of the cryogenic fluid. However, once the secondary barrier is damaged, it is highly possible that the leaked cryogenic fluid flows through the flat joint made of glass wool and reaches the inner hull of the ship. The primary objective of the present study is to investigate the influence of the damage extent in the secondary barrier on the amount of leaked cryogenic fluid reaching the inner hull and the temperature distribution there. Simulation results using a computational fluid dynamics tool were compared with the experimental data for the leaked cryogenic fluid flow and evaporation in the secondary insulation layer. The experimental and computational results suggest that, unless there is a massive leak, the cryogenic fluid mostly evaporates in the insulation layer and does not reach the inner hull in the state of liquid.

• 대한조선학회논문집
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• 제57권4호
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• pp.221-229
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• 2020

Naval ships could be seriously damaged by enemy attacks in battle. Moreover, this damage could be spread and deteriorated into a secondary accident. Secondary accidents that have adverse effects on naval ship's survivability, such as fire, flood, smoke extension, and patient occurrence, are defined as casualties. These casualties sharply degrade the survivability of naval ships. Furthermore, naval ships could be burned-out and sunk by casualties in isolated sea. Therefore, damage control and rapid suppression of the casualties in the naval ships is essential. This study was conducted in the establishment of suppression paths according to the characteristics of each casualty so that the developed system can support the rapid suppression in an emergency and even the training situation on a regular state. To establish the suppression paths, the two-dimensional numerical map is designed by converting the three-dimensional features of the naval ships, and the well known algorithms are compared to present the appropriate one for path finding problem on the naval ships. Finally, we devised a specific routing algorithm that fits the characteristics of each casualty in accordance with the Korean Navy's doctrines and handbooks of casualty suppression.

• 융합정보논문지
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• 제10권1호
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• pp.51-59
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• 2020

본 연구의 목적은 우리나라 다문화청소년의 폭력 피해경험과 정신건강과의 관련성을 파악하여 다문화청소년의 정신건강증진 중재를 개발하는데 기초자료로 활용되기 위함이다. 본 연구는 2018년도 청소년건강행태조사결과를 기초자료로 한 이차자료 분석연구이며, 우리나라 다문화청소년 835명을 대상으로 하였다. 자료 분석은 IBM 25 ver. SPSS를 이용하였으며 복합표본을 이용하여 로지스틱 회귀분석을 실시하였다. 본 연구 결과 다문화청소년의 정신건강 특성에 공통적으로 영향을 미치는 요인은 폭력피해경험, 성별, 주관적 건강인지이며, 폭력피해 경험이 있고, 여학생이며 주관적 건강인지가 나쁠수록 슬픔, 절망감 경험, 자살사고, 자살계획, 자살시도가 높은 것으로 나타났다. 본 연구는 이차자료 분석연구로 폭력피해와 정신건강 인과관계를 파악하기 어려운 제한점이 있으나 전국적 규모의 청소년 조사자료를 이용하여 분석함으로써 연구결과의 대표성을 가지며, 다문화청소년을 대상으로 분석하였다는데 의의가 있다.

• 디지털산업정보학회논문지
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• 제11권4호
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• pp.81-87
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• 2015

Recently, with the development of the ICT environment, the use of the software is growing rapidly. And the number of the web server software used with a variety of users is also growing. However, There are also various damage cases increased due to a software security vulnerability as software usage is increasing. Especially web shell hacking which abuses software vulnerabilities accounts for a very high percentage. These web server environment damage can induce primary damage such like homepage modification for malware spreading and secondary damage such like privacy. Source code weaknesses checking system is needed during software development stage and operation stage in real-time to prevent software vulnerabilities. Also the system which can detect and determine web shell from checked code in real time is needed. Therefore, in this paper, we propose the system improving security for web server by detecting web shell attacks which are invisible to existing detection method such as Firewall, IDS/IPS, Web Firewall, Anti-Virus, etc. while satisfying existing secure coding guidelines from development stage to operation stage.

• Earthquakes and Structures
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• 제1권2호
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• pp.147-162
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• 2010

The ground acceleration measured at a point on the earth's surface is composed of several waves that have different phase velocities, arrival times, amplitudes, and frequency contents. For instance, body waves contain primary and secondary waves that have high frequency content and reach the site first. Surface waves are composed of Rayleigh and Love waves that have lower phase velocity, lower frequency content and reach the site next. Some of these waves could be of more damage to the structure depending on their frequency content and associated amplitude. This paper models critical earthquake loads for single-degree-of-freedom (SDOF) inelastic structures considering evolution of the seismic waves in time and frequency. The ground acceleration is represented as combination of seismic waves with different characteristics. Each seismic wave represents the energy of the ground motion in certain frequency band and time interval. The amplitudes and phase angles of these waves are optimized to produce the highest damage in the structure subject to explicit constraints on the energy and the peak ground acceleration and implicit constraints on the frequency content and the arrival time of the seismic waves. The material nonlinearity is modeled using bilinear inelastic law. The study explores also the influence of the properties of the seismic waves on the energy demand and damage state of the structure. Numerical illustrations on modeling critical earthquake excitations for one-storey inelastic frame structures are provided.

• 한국방재안전학회논문집
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• 제16권2호
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• pp.57-63
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• 2023

기후변화로 인하여 발생하는 집중호우와 슈퍼태풍은 우리나라에서 많은 피해를 야기한다. 이러한 피해를 저감하기 위해서 다양한 형태의 하천정비사업이 추진되고 있으나, 홍수기와 갈수기가 뚜렷한 우리나라에서는 하천 균형을 유지하기가 어렵다. 특히, 하천정비 사업으로 설치된 하천구조물은 홍수기에 구조물 및 그 기초의 세굴이 발생되고 하상 변화 등 다양한 문제를 일으키고 있다. 이러한 하상세굴을 저감하기 위하여 하천의 만곡부에 다양한 베인이 많이 설치되며, 베인의 배치와 크기, 모양에 따라서 다양한 하상세굴 저감 효과가 나타난다. 베인은 원심력에 의해 발생하는 2차 흐름과 반대 방향으로 2차 흐름을 다시 생성함으로써 외측 하상 주변의 세굴이 감소하고 퇴적이 촉진된다. 본 연구의 이론은 질량보존법칙을 만족하는 연속방정식과 운동량 보존을 만족하는 운동량방정식을 적용한 지배방정식을 이용하고, 다양한 조건 하에서 베인의 영향을 조사하기 위해 설계 요인에 따라 전체 평균 유속 변화율을 측정한다. 사다리꼴 베인과 사각형 베인 모두에서 평균유속과 횡단면 유속이 모두 감소하였고, 이는 베인 설치로 인해서 원심력을 갖고 유하하는 하천유속이 방해를 받아 유속이 저감되기 때문이다. 또한, 하천흐름 방향에 수직으로 또는 경사적으로 설치된 베인은 원심력에 의해 발생하는 2차흐름의 역방향으로 2차흐름을 발생시켜 원심력 2차흐름의 상쇄를 나타내기 때문에 베인의 효과가 나타난다.

• Spatial Information Research
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• 제18권2호
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• pp.35-44
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• 2010

본 연구에서는 최근 활용성이 증가하는 항공사진과 GIS기법을 이용하여 집중호우로 인한 피해정보를 산출하기 위한 방법에 대해 연구하였다. 연구 대상지역은 경상북도 봉화군 춘양면 일대로써 2008년 7월 말 국지성 집중호우로 인해 수해를 입은 지역이다. 연구 수행을 위해 우선 연구 대상지역의 데이터를 수집하여 데이터베이스를 구축하였다. 아울러 항공사진을 이용하여 추출 가능한 피해 대상 항목을 선정하고, 활용 가능한 GIS 레이어를 분석하였다. 피해정보의 추출은 판독 가능한 항목을 대상으로 피해 전 후의 항공사진을 비교하는 방법을 시도하였다. 해당 피해 항목에 대한 레이어가 존재할 경우에는 GIS의 중첩기능을 통하여 정확하고 용이한 정보의 추출이 가능하였다. GIS와 항공사진을 이용한 피해정보 추출은 소규모의 피해는 물론, 현장조사 시 접근이 어렵고 피해 범위가 넓은 지역에 대한 피해정보를 신속히 추출함으로써 신속한 복구계획의 수립이 가능하였다. 나아가 이러한 방법을 통하여 신속한 피해의 복구를 지원하여 이차적인 피해를 최소화하고, 향후 집중호우에 의한 피해조사 업무의 혁신에 기여가 클 것으로 사료된다.

• Journal of Trauma and Injury
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• 제29권1호
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• pp.33-36
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• 2016

Traffic accidents involving agricultural machinery have been decreasing, but mortality is still high due to a lack of safety devices such as seat belts. Furthermore, secondary damage, such as abdominal impalement injury caused by loaded materials, is more likely to occur, and this type of injury leads to a poor prognosis. Impalement with pipes is often more fatal than other penetrating injuries because the diameter of the pipe is usually larger in size than other loaded materials. We report a case of a 72-year-old man with secondary abdominal impalement injury caused by a scaffolding pipe following a traffic accident.

• 국제초고층학회논문집
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• 제1권1호
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• pp.1-13
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• 2012

The importance of appropriate use of damping evaluation techniques and points to note for accurate evaluation of damping are first discussed. Then, the variation of damping ratio with amplitude is discussed, especially in the amplitude range relevant to wind-resistant design of buildings, i.e. within the elastic limit. The general belief is that damping increases with amplitude, but it is emphasized that there is no evidence of increasing damping ratio in the very high amplitude range within the elastic limit of main frames, unless there is damage to secondary members or architectural finishings. The damping ratio rather decreases with amplitude from a certain tip drift ratio defined as "critical tip drift ratio," after all friction surfaces between primary/structural and secondary/non-structural members have been mobilized.