• Title/Summary/Keyword: SAFE in Korea

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Fatigue Life Evaluation of Fiber Reinforced Composite Rotor Blades Considering Impact Damages (충격손상을 고려한 섬유강화 복합재 로터 블레이드의 피로수명 평가)

  • Kee, Young-Jung;Park, Jae-Hun;Kim, Sung-Man;Kim, Gi-Hun
    • Journal of Aerospace System Engineering
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    • v.14 no.spc
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    • pp.22-30
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    • 2020
  • Composite rotor blades for rotorcraft have an intrinsic vulnerability to foreign object impact from its inherent structural characteristics of insufficient strength in the thickness direction, which may easily lead to internal structure damage. Therefore, defects and strength reducing effects caused by foreign object impact should be considered in fatigue evaluation of composite blades. For this purpose, the flaw tolerant safe-life and fail-safe concepts were adopted in fatigue evaluation since 1980s, and recently those concepts have been replaced by the damage tolerance concept. In this paper, the relevant standards for fatigue evaluation are analyzed focusing on fiber reinforced composite rotor blades used in rotorcraft. In addition, fatigue evaluation procedure of composite blades considering impact damages is proposed by reviewing the practices implemented through domestic development projects.

The Assessment of Safe Navigation Regarding Hydrodynamic forces between Ships in Restricted Waterways

  • Lee, Chun-Ki;Lee, Sam-Goo
    • Journal of Mechanical Science and Technology
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    • v.20 no.11
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    • pp.2002-2009
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    • 2006
  • This paper is primarily focused on the safe navigation between overtaking and overtaken vessels in restricted waterways under the external forces, such as wind and current. The maneuvering simulation between two ships was conducted to find an appropriate safe speed and distance, which is required to avoid collision. From the viewpoint of marine safety, a greater transverse distance between two ships is more needed for the smaller vessel. Regardless of external forces, the smaller vessel will get a greater effect of hydrodynamic forces than the bigger one. In the case of close navigation between ships under the forces of wind and current, the vessel moving at a lower speed is potentially hazardous because the rudder force of the lower speed vessel is not sufficient for steady-state course-keeping, compared to that of the higher speed vessel.

Planning of Safe and Efficient Local Path based on Path Prediction Using a RGB-D Sensor (RGB-D센서 기반의 경로 예측을 적용한 안전하고 효율적인 지역경로 계획)

  • Moon, Ji-Young;Chae, Hee-Won;Song, Jae-Bok
    • The Journal of Korea Robotics Society
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    • v.13 no.2
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    • pp.121-128
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    • 2018
  • Obstacle avoidance is one of the most important parts of autonomous mobile robot. In this study, we proposed safe and efficient local path planning of robot for obstacle avoidance. The proposed method detects and tracks obstacles using the 3D depth information of an RGB-D sensor for path prediction. Based on the tracked information of obstacles, the paths of the obstacles are predicted with probability circle-based spatial search (PCSS) method and Gaussian modeling is performed to reduce uncertainty and to create the cost function of caution. The possibility of collision with the robot is considered through the predicted path of the obstacles, and a local path is generated. This enables safe and efficient navigation of the robot. The results in various experiments show that the proposed method enables robots to navigate safely and effectively.

A Basic Study on the VTS Operator's Minimum Safe Distance (VTS관제사의 최소안전거리에 관한 기초 연구)

  • Kim, Jong-Sung
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.19 no.5
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    • pp.476-482
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    • 2013
  • This study aims to enhance the effectivity of VTS(Vessel Traffic Service) control by investigating the minimum safe distance between vessel and vessel, vessel and land(obstacle) for the vessel's safe navigation within the VTS control area. In addition, to suggest basic data for the safe navigation, this study has done survey and analysis to each VTS center, and individual on the minimum safe distance to VTS operators of each ports of korea. Through ocean voyage by training ship, Singapore and Malacca strait's congested vessel traffic zone's control distance was compared and investigated the difference on safe distance by the different VTS operators. As a result, there was huge difference of minimum safe distance between the VTS operators belong to the same center. Over all, the port with gentle coastline, like donghae, the safe distance was wider than the other port. On the other hand, port with complex coastline and frequent entry and departure of the vessel, like mokpo, the safe distance was the shortest of all. Therefore, development of module suitable to port's natural conditions and traffic volume's necessity is required, for the operators affiliated to the same VTS center control according to formal method. Lastly, the full discussion by the expert group about establishment of standard control procedure in the future should be considered as well.

A Study on Expressing the Methods of Light for Creating Safe Space (안전한 공간 조성을 위한 빛의 표현방안 연구)

  • Kim, Myoung-Seon;Moon, Jeong-Min
    • Journal of the Korean housing association
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    • v.27 no.3
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    • pp.39-46
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    • 2016
  • On account of the increasing crime rates annually and the consequent rising anxiety, safety has become an important topic in the aspect of environmental formation to provide decent lives to urban dwellers. As a result, great emphasis has been placed in the importance of Crime Prevention through Environmental Design (CPTED), a design method which utilizes physical environmental design to prevent crime. The definition of CPTED encompasses the technological level of crime prevention as well as comprehensive environmental design which takes into consideration fear or terror in view of human recognition and emotion. However, the current application method of CPTED in Korea is still limited to the technical supplementation of facilities, such as CCTV and streetlight, and fragmental modification like village mural paintings. Moreover, the guideline for CPTED in Korea is only a theoretical adaptation of foreign books and does not offer sufficient studies for a practical design method that will improve the life of city dwellers. The purpose of this study is to examine design methods for safe environment construction in accordance with the changing concept of CPTED by understanding the characteristic of space and analyzing the how the methods of light are expressed. This study aims to provide basic material which will serve as a guideline in creating a safe environment in the future.

Correlations between Sensory Processing Abilities and Safe Driving Behavior in Older Adults (노인의 감각처리능력과 안전운전행동에 관한 상관성 연구)

  • Kim, Hee-Dong;Ko, Hyo-Eun;Jang, Yeon-Sik;Cho, Nam-Ju;Baek, Ji-Young
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.5
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    • pp.2743-2748
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    • 2014
  • The research was conducted to understand the correlation between sensory processing ability and safe driving behavior of over 65. Questionnaires regarding sensory processing ability and safe driving behavior were given to 31 people who are in their 65 or over and Pearson Correlation Analysis was carried out on the survey. The result of the research indicates that there is interrelationship between total score of sensory processing ability and safe driving behavior, and sub factors. According to the findings, over 65 showed certain difficulties in sensory processing ability and safe driving behavior due to aging. Therefore, it would be necessary to evaluate their driving behavior and arbitrate appropriate operation therapy.

Development of a safe operation capability chart as the design basis of a rudder area

  • You, Youngjun;Kim, Sewon;Kim, Woojin
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.10 no.5
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    • pp.529-544
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    • 2018
  • Ship owners now demand a new design approach for the rudder that considers detailed design information such as maneuverability and environmental loads etc. on a quantified basis. In this paper, we developed the concept of a safe operation capability chart for the design of a rudder area. The chart can be used as the basis of design considering the maneuverability and environmental loads. To confirm the applicability of the safe operation capability chart for use as the basis of design, four different rudders are assumed in this work. First, it is determined whether or not it is appropriate to design a rudder by applying a conventional design approach based on IMO maneuvering tests. The proposed concept is reviewed for use as the basis of the design by investigating the effect of rudder area on capability charts that are plotted according to the rudder under various environmental conditions.

Online Adaptation of Control Parameters with Safe Exploration by Control Barrier Function (제어 장벽함수를 이용한 안전한 행동 영역 탐색과 제어 매개변수의 실시간 적응)

  • Kim, Suyeong;Son, Hungsun
    • The Journal of Korea Robotics Society
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    • v.17 no.1
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    • pp.76-85
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    • 2022
  • One of the most fundamental challenges when designing controllers for dynamic systems is the adjustment of controller parameters. Usually the system model is used to get the initial controller, but eventually the controller parameters must be manually adjusted in the real system to achieve the best performance. To avoid this manual tuning step, data-driven methods such as machine learning were used. Recently, reinforcement learning became one alternative of this problem to be considered as an agent learns policies in large state space with trial-and-error Markov Decision Process (MDP) which is widely used in the field of robotics. However, on initial training step, as an agent tries to explore to the new state space with random action and acts directly on the controller parameters in real systems, MDP can lead the system safety-critical system failures. Therefore, the issue of 'safe exploration' became important. In this paper we meet 'safe exploration' condition with Control Barrier Function (CBF) which converts direct constraints on the state space to the implicit constraint of the control inputs. Given an initial low-performance controller, it automatically optimizes the parameters of the control law while ensuring safety by the CBF so that the agent can learn how to predict and control unknown and often stochastic environments. Simulation results on a quadrotor UAV indicate that the proposed method can safely optimize controller parameters quickly and automatically.

Path Planning based on Ray-casting in Indoor Environments for Safe Navigation of a Mobile Robot (이동로봇의 안전한 주행을 위한 광선투사법 기반의 실내 경로계획)

  • Kim, Jong-Won;Song, Jae-Bok
    • The Journal of Korea Robotics Society
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    • v.5 no.4
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    • pp.302-308
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    • 2010
  • A gradient method can provide a global optimal path in indoor environments. However, the optimal path can be often generated in narrow areas despite a sufficient wide area which lead to safe navigation. This paper presents a novel approach to path planning for safe navigation of a mobile robot. The proposed algorithm extracts empty regions using a ray-casting method and then generates temporary waypoints in wider regions in order to reach the goal fast and safely. The experimental results show that the proposed method can generate paths in the wide regions in most cases and the robot can reach the goal safely at high speeds.

A Study on big data utilization for implementation of the resident participation type safe community planning of the smart city (스마트시티의 주민참여형 안전도시 계획을 위한 빅데이터 활용에 관한 고찰)

  • Chang, Hye-Jung;Kim, Do-Nyun
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.9 no.5
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    • pp.478-495
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    • 2016
  • The existing city planning was performed by internal few decision-maker, but the information that an individual could contact with through the evolution of the ICT technology increased in the smart city, and a channel diversified and came to be able to participate in a decision making process by various methods. I show that it is in the collaborative planning process to come to a mutual understanding with residents directly or indirectly if utilize big data in a process of the safe community planning of the smart city. Therefore, I compare the utilization contents between data of Matsubara-shi,Japan and data of certification city of Korea which received the certification of the WHO international safe community. In the area where this study prepares for the approval of the international safe community, it wants you to use it though you utilize the data as the supporting role of the residents participation plan.