• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2008년도 정기 학술대회
• /
• pp.397-401
• /
• 2008

Knowledge of dynamic characteristics of structural elements often can make difference between success and failure in the design of structure due to resonance effect. In this paper an analytical model of a cantilever beam having midpoint load is considered for structural optimization. This involves creating the geometry which allows parametric study of all design variables. For that purpose optimization of cantilever beam is elaborated in order to find the optimum geometry which minimizes its volume eventually for minimum weight using ANSYS. But such geometry could be obtained by different combinations of width and height, so that it may have the same cross sectional area yet different dynamic behavior. So for optimum safe design, besides minimum volume it should have minimum vibration as well. In order to predict vibration different dynamic analyses are performed simultaneously to solve the eigenvalues problem assuming no damping initially through MATLAB simulations using state space form for modal analysis, which identifies the resonant frequencies and mode shapes belonging to the lowest three modes of vibration. And next by introducing damping effects tip displacement, bending stress and the vertical reaction force at the fixed end is evaluated under some dynamic load of varying frequency, and finally it is discussed how resonance can be avoided for particular design. Investigation of results clearly shows that only structural analysis is not enough to predict the optimum values of dimension for safe design. Potentially this technique will meet maintenance and cost goals of many organizations particularly for the application where dynamic loading is invertible and helps a lot ensuring that the proposed design will be safe for both static and dynamic conditions.

• Journal of Preventive Medicine and Public Health
• /
• 제49권5호
• /
• pp.323-328
• /
• 2016

Objectives: A clean India is the responsibility of all Indians. One of the objectives of the Swachh Bharat Abhiyan (Clean India Initiative) is to bring about behavioural changes regarding healthy sanitation practices. While large-scale programs in India have increased latrine coverage, they have to some extent failed to bring behavioural changes ensuring optimal latrine use, including the safe disposal of child faeces, which is a significant source of exposure to faecal pathogens. Hence, this study was done to explore child faeces disposal practices in rural West Bengal and to elicit the determinants of unhygienic faeces disposal. Methods: Data collection was done using an interview method among the mothers of 502 under-5 children, following a pre-designed, semi-structured schedule during house-to-house visits in a set of villages in the Hooghly district of West Bengal. Results: The prevalence of unsafe disposal of child faeces was 72.4%, and maternal education, per capita income, and water source were found to be significantly associated with unsafe child faeces disposal. Conclusions: This study draws attention to the unsafe disposal of child faeces in this area of India and raises questions about the efficiency of sanitation campaigns in rural India that focus on expanding coverage rather than emphasizing behavioural changes, which are crucial to ensure the safe disposal of child faeces. Thus, it is urgently necessary to strengthen efforts focusing on behavioural changes regarding the safe disposal of child faeces in order to minimise adverse health outcomes.

• 한국콘텐츠학회논문지
• /
• 제18권2호
• /
• pp.169-177
• /
• 2018

가뭄, 홍수 등의 자연재난으로 인해 인명 손실이 많이 발생되고 있다. 특히 도시지역에 발생되는 집중호우로 인한 침수 피해는 인명 및 구조물에 심각한 피해를 발생시킨다. 이에 따라 본 연구에서는 침수피해가 높은 도시지역을 대상으로 사람들이 안전하게 대피할 수 있도록 하는 최적 대피경로에 관한 연구를 수행하였다. 이를 위해 Flo-2D 모형 및 A*알고리즘에 대하여 고찰하여 최적 대피경로를 도출하고자 하는 방법론을 설정하였다. Flo-2D모형을 통해 위험지역을 도출하였으며, 인원수가 많은 시작지점을 선정하고 홍수재난에 대해 안전한 대피지점을 선정할 수 있도록 하는 방법을 제시하였다. 그리고 A* 알고리즘을 활용하여 출발지점에서 안전한 대피지점까지 위험지점을 거치지 않고 최적의 대피경로를 도출하였다. 본 연구를 통해 대피경로 제시뿐만 아니라 도로정비와 대피시설물에 대한 사전 대비 자료로 활용될 수 있을 것으로 판단된다.

• 해양환경안전학회지
• /
• 제24권6호
• /
• pp.670-678
• /
• 2018

선박의 통행량이 많은 연안해역은 선박들 사이에 복잡한 조우상황이 자주 발생하기 때문에 충돌사고의 가능성이 높다. 따라서 해상에서 충돌사고를 줄이기 위해서는 항해사의 국제충돌예방규칙(COLREG) 준수에 더하여 정량적인 충돌위험평가가 요구된다. 본 연구에서는 선박의 계획항로에 대한 충돌위험을 평가하기 위한 새로운 충돌위험도 평가시스템이 개발되었다. 먼저 기존의 충돌위험 평가모델들을 검토함으로써 적절한 충돌위험 평가방법이 제시되었다. 시스템은 MATLAB을 사용하여 개발되었으며 해도, 범퍼 및 평가의 세 부분으로 구성된다. 개발된 시스템은 시험을 위해 간단한 계산조건으로 시험해역에 적용되었으며, 그리고 검증을 위해 실제 계산조건으로 실제해역에 적용되었다. 그 결과 충돌위험은 자선의 길이, 항해시간 및 항로 등에 의해 영향을 받는 것으로 나타났다. 개발된 시스템은 항해사가 출항전 최적안전항로를 선택하는데 도움을 줄 수 있을 것으로 기대된다.

• 한국가스학회지
• /
• 제20권1호
• /
• pp.62-67
• /
• 2016

가장 깨끗한 화석연료 가운데 하나인 천연가스는 장거리 수송 시 부피를 줄이기 위해 액화된다. 그 중 소형 해양 천연가스 액화 플랜트는 면적이 작기 때문에 안전문제가 크게 대두된다. 하지만, 기존에 쓰이는 DMR (Dual Mixed Refrigerants) 공정은 가연성 냉매를 사용함으로써 화재의 위험이 있으며, N2 Expander 공정은 안전하지만 압축 에너지 효율이 낮다는 문제점이 있다. 따라서 안전하면서도 압축 에너지 효율 또한 높은 공정의 개발이 지속적으로 요구되는 상황이다. 본 연구에서는 DMR 공정에 비가연성 냉매인 Hydrofluorocarbon을 사용하여 안전성을 높임으로써 기존 공정들에 대한 대안을 제시하였다. 그 결과, 화재위험이 있는 DMR 공정보다 34.8% 낮은 압축에너지 효율을 보였으나, Single N2 Expander 공정보다 42.6% 향상된 압축 에너지 효율을 나타내었다. 결론적으로 이 연구에서는 안전하면서도 높은 에너지 효율을 내는 소형 해양 천연가스 액화 플랜트 공정을 설계하였다.

• 산업융합연구
• /
• 제20권11호
• /
• pp.191-196
• /
• 2022

핀테크 환경에서 스마트 폰을 이용한 금융거래가 활발하게 이루어지고 있다. 안전한 금융거래를 위해 사용자 인증 기술이 필수적이다. 기존 보안 키패드를 통한 PIN 인증은 입력 편리성이 좋지만, 보안성이 떨어지고 취약점이 존재한다. 생체인증 기법은 보안성이 안전하지만 오탐 및 미탐 인증 가능성이 있다. 이를 보완하기 위해 2-factor 인증을 사용한다. 본 논문에서는 생체인증 기법을 적용한 PIN 입력을 통해 편리성과 보안성을 높일 수 있는 1.5-factor 인증을 제안하고자 한다. 지문인증의 안정성과 2~4번의 PIN 입력을 통해 편리성을 제공하여 안전한 금융거래가 가능하다. 제안기법은 PIN 입력 시 생체인증을 동시에 수행하므로 PIN 입력할 때 터치하는 영역에 지문인식을 적용하는 방식이다. 보안이 요구되는 경우 높은 안전성이 요구되는 상황에서는 추가적인 PIN 입력을 통해 입력 편리성을 보장하면서 사용자 인증을 수행하여 안전한 금융거래가 가능하다.

• 대한임상독성학회지
• /
• 제21권2호
• /
• pp.128-134
• /
• 2023

Purpose: The Prescott nomogram has been utilized to forecast hepatotoxicity from acute acetaminophen poisoning. In developing countries, emergency medical centers lack the resources to report acetaminophen concentrations; thus, the commencement and cessation of treatment are based on the reported dose. This study investigated risk factors that can predict acetaminophen detection after 15 hours for safe treatment termination. Methods: Data were collected from an urban emergency medical center from 2010 to 2020. The study included patients ≥14 years of age with acute acetaminophen poisoning within 15 hours. The correlation between risk factors and detection of acetaminophen 15 hours after ingestion was evaluated using logistic regression, and the area under the curve (AUC) was calculated. Results: In total, 181 patients were included in the primary analysis; the median dose was 150.9 mg/kg and 35 patients (19.3%) had acetaminophen detected 15 hours after ingestion. The dose per weight and the time to visit were significant predictors for acetaminophen detection after 15 hours (odds ratio, 1.020 and 1.030, respectively). The AUCs were 0.628 for a 135 mg/kg cut-off value and 0.658 for a cut-off 450 minutes, and that of the combined model was 0.714 (sensitivity: 45.7%, specificity: 91.8%). Conclusion: Where acetaminophen concentrations are not reported during treatment following the UK guidelines, it is safe to start N-acetylcysteine immediately for patients who are ≥14 years old, visit within 15 hours after acute poisoning, and report having ingested ≥135 mg/kg. Additional N-acetylcysteine doses should be considered for patients visiting after 8 hours.

• 로봇학회논문지
• /
• 제3권3호
• /
• pp.186-193
• /
• 2008

We propose a novel real-time obstacle avoidance method for rescue robots. This method, named the ELA(Emergency Level Around), permits the detection of unknown obstacles and avoids collisions while simultaneously steering the mobile robot toward safe position. In the ELA, we consider two sensor modules, PSD(Position Sensitive Detector) infrared sensors taking charge of obstacle detection in short distance and LMS(Laser Measurement System) in long distance respectively. Hence if a robot recognizes an obstacle ahead by PSD infrared sensors first, and judges impossibility to overcome the obstacle based on driving mode decision process, the order of priority is transferred to LMS which collects data of radial distance centered on the robot to avoid the confronted obstacle. After gathering radial information, the ELA algorithm estimates emergency level around a robot and generates a polar histogram based on the emergency level to judge where the optimal free space is. Finally, steering angle is determined to guarantee rotation to randomly direction as well as robot width for safe avoidance. Simulation results from wandering in closed local area which includes various obstacles and different conditions demonstrate the power of the ELA.

• 로봇학회논문지
• /
• 제3권4호
• /
• pp.345-350
• /
• 2008

This study aims to propose the concept design of oil spill protection robot which can rapidly intervene to control the oil spillage situation at the sea. Taking into account the fact that a huge amount of oil is transported trans-continentally by oil tanker, none of industrialized countries are completely safe from the marine oil spill which results in social, economical and ecological damages to their communities. The employment of double hull-oil tanker, pipe line transporting can be most safe way. Yet complete prevention of oil spill is probably not realistic. Accordingly the alternative solution to control marine oil spill and minimize the damages caused by the incident using intelligent robot technology based on swarm control method is proposed. The main features of oil spill protection(OSP) robot is explained via following three perspectives. Firstly, from functional point of view, OSP robot system safely and efficiently replaces oil boom installation manually conducted by human workers with intelligent robot technology based on swarm control theory. For second, its modular architecture brings efficient storage of main components including oil boom and facilitates maintenance. For the last, its geometric form and shape enables whole system to be installed to helicopter, boat or oil tanker itself with ease and to rapidly deploy the units to the oil spill area.

• Geomechanics and Engineering
• /
• 제10권4호
• /
• pp.547-563
• /
• 2016

This paper describes a geotechnical field investigation in Giresun hazelnut licenced warehause and spot exchange during twelve months to determine the soil profile and static project applicability. It is also aimed to determine the superstructure loads and evaluate the relevance of foundation filling materials of the main, laboratory, package and admin buildings. The main building has $88.50{\times}63.20(5593.2)m^2$ site area. It has a big raft foundation. Eleven geotechnical reports were prepared between 2 December 2014 and 25 May 2015. Maximum settlements and safe bearing capacities were calculated to decide to be able to proceed to the next step. Also, the detail observations and evaluations were presented from October 2014 to December 2014. It has been seen that the foundation is designed as a single foundation one. But, in the light of observations, it has been evaluated that the foundation project for package building is not adequate, and after these excavations it must be revised as a raft foundation. The thickness of foundation and structural details should be defined/drawn after analyzing the details by using a special software. Construction joints should be designed between different buildings interfaces to avoid damages and cracks with in different settlements. The environmental drainage must be projected and applied to avoid the probable damage of surface waters on foundations.