• 전산구조공학
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• 제7권3호
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• pp.83-93
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• 1994

도로 안전 구조물을 설계하고 동적 퍼포먼스를 측정하기 위하여 시행되는 충돌시험시 충돌차량의 운동량, 특히 각가속도를 Euler방정식의 수치적분을 통하여 구하는 기법을 설명하였다. 수치적으로 가장 안정적인 9-array 시스템안에 내지된 여러 형태의 7,8-array 서브시스템들의 시스템 미분방정식 및 이들 방정식의 수치 적분시 안정성을 실험데이터를 이용하여 파악하였다. 기본적인 9-array안에 있는 6개의 8-array시스템들은 모두 수치적으로 안정성을 보였고 12개의 7-array시스템들중 6개는 안정성을 보이고 6개는 불안정하였다. 안정성을 보이는 내재된 서브시스템을 활용하면 기본 9-array시스템을 구성하는 센서의 일부 고장시 효과적으로 각가속도를 측정할 수 있는 fail-safe 시스템을 구성할 수 있다.

• 한국기계가공학회지
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• 제10권6호
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• pp.63-69
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• 2011

This study analyzes stress, fatigue and vibration on main rotor and body of helicopter. The maximum stress is shown on adjoint part between body and main rotor at the lower position of main rotor. As the maximum displacement amplitude is happened at 4000Hz, there is no resonance and the state of helicopter becomes safe at hovering without the abnormal air current and the disabled rotor. Among the cases of nonuniform fatigue loads, 'SAE bracket history' with the severest change of load becomes most unstable but 'Sample history' becomes most stable. In case of 'Sample History' with the average stress of 0MPa to $-10^5MPa$ and the amplitude stress of 0MPa to $8.539{\times}10^5MPa$, the possibility of maximum damage becomes 3%. This stress state can be shown with 5 times more than the damage possibility of 'SAE bracket history' or 'SAE transmission'. The structural result of this study by using the analysis of vibration and fatigue can be effectively utilized for safe and durable design of helicopter.

• Nuclear Engineering and Technology
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• 제50권6호
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• pp.860-868
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• 2018

This article presents a new design of earthquake instrumentation that is suitable for quick decision-making after the seismic event at the nuclear power plant (NPP). The main objective of this work is to ensure more availability of the NPP by expediting walk-down period when the seismic wave is incident. In general, the decision-making to restart the NPP after the seismic event requires more than 1 month if an earthquake exceeds operating basis earthquake level. It affects to the plant availability significantly. Unnecessary shutdown can be skipped through quick assessments of operating basis earthquake, safe shutdown earthquake events, and damage status to structure, system, and components. Multidecision parameters such as cumulative absolute velocity, peak ground acceleration, Modified Mercalli Intensity Scale, floor response spectrum, and cumulative fatigue are discussed. The implementation scope on the field-programmable gate array platform of this work is limited to cumulative absolute velocity, peak ground acceleration, and Modified Mercalli Intensity. It can ensure better availability of the plant through integrated decision-making process by automatic assessment of NPP structure, system, and components.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.345-346
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• 2008

Most pedestrian-vehicle crashes involve frontal impacts, and the vehicle front structures are responsible for most pedestrian injuries. The vehicle bumper contacts the lower legs at first. The leading edge of the hood (bonnet) strikes the proximal upper leg and finally, the head and upper torso hit the top surface of the hood or windscreen. In essence, the pedestrian wraps around the front of the vehicle until pedestrian and vehicle are traveling at the same speed. Since the hood surface is made from sheet metal, it is a relatively compliant structure and does not pose a major risk for severe head trauma. However, serious head injury can occur when the head hits a region of the hood with stiff underlying structures such as engine components. The solution is to provide sufficient clearance between the hood and underlying structures for controlled deceleration of a pedestrian's head. However, considerations of aerodynamic design and styling can make it extremely difficult to alter a vehicle's front end geometry to provide more under-hood space. In this study, the safe hood will be developed by designing new conceptual inner panel in order to decrease the pedestrian's head injuries without changing hood outer geometry.

• 한국정밀공학회지
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• 제33권9호
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• pp.739-744
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• 2016

The truck that is used as running equipment for tank freight car support is a core structural part that supports the load of the car body and significantly influences the safety of freights and vehicles, as well as their running performance. Running equipment is composed of truck frames, wheels and wheel axles, independent suspensions, and brakes. Among these components, the truck frame supporting the load of the vehicles and freights may be the most important component. This study was carried out to analyze the structure of truck frames and to determine whether they are safe when the maximum vertical load, braking part load, and the front and rear load are applied to truck frames. This was achieved by subjecting the truck frames to stress tests and then measuring the stress on each part. The results of the stress tests showed that truck frames have a safe vehicle load design.

• 한국안전학회지
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• 제34권5호
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• pp.103-110
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• 2019

In order to reduce the accidents occurring at construction sites, it is necessary to approach with harmonious measures considering various aspects such as systems, training, facilities, and protection equipments. Suggestion of safe construction method can be a good alternative. In the previous study, the half-depth precast deck with RC rib panel was proposed as an alternative method for safe bridge deck construction, and the performance required by the design code was verified through a four-point bending test. But the actual bridge deck is subjected to the repetitive action of the wheel load rather than the bending condition due to the four-point load. In this study, fatigue test was performed by repeating the wheel load $2{\times}10^6$ cycles to verify the safety of the half-depth precast deck with RC rib panel under actual conditions. As a result, fatigue effect due to repetition of wheel load was not significant in terms of serviceability such as crack width and deflection. In the residual strength test conducted after the fatigue test, the half-depth precast deck with RC rib panel failed by punching shear which is typical failure mode of bridge decks and the residual strength was similar to the punching strength of the RC and PSC bridge decks in spite of the fatigue effects.

• Safety and Health at Work
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• 제12권3호
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• pp.317-323
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• 2021

Background: The surface mining industry has one of the highest fatality rates among private industries in the United States. Despite recent decreases in the fatality rates of comparable industries, the fatality rate in the surface mining industry has increased. Meanwhile, a lack of safety research in surface mining has hindered efforts to improve safety strategies in the surface mining workplace. Method: This study examined quarry workers' hazard identification skills by conducting a case study of a surface mining facility in the Mid-Atlantic region of the United States. Semistructured interviews were conducted with eight quarry workers who were employed at the mine facility. In addition to the interviews, data were collected through field notes, notes from an expert meeting with safety managers, and site photographs to explore quarry workers' safety behaviors in the workplace. Results: The results showed that quarry workers identified hazards and improved their safety performance by translating safety knowledge learned from training into practice, acquiring hands-on work experience, learning from coworkers, and sharing responsibilities among team members. Conclusion: This study contributes to understanding quarry workers' safe performance beyond what they have learned in safety training to include their interaction with other workers and hand-on experience in the workplace. This study informs practitioners in the surface mining industry to build a safe work environment as they design effective safety programs for employees.

• 문화기술의 융합
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• 제5권3호
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• pp.257-262
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• 2019

최근 드론 같은 무인 이동체에 대한 관심과 일상생활에 활용이 늘어나면서 많은 다양한 분야에서 이를 이용하는 응용 사례가 급속도로 확산되고 있다. 하지만 이러한 무인 이동체는 쉽게 외부 환경 요인으로 인한 균형 이탈이나 추락 등의 사고로 이어질 수 있는 많은 위험 요인을 내포하고 있다. 이러한 무인 이동체의 안전한 운용을 위하여 안정적인 자세 제어 알고리즘은 매우 중요한 부분을 차지하고 있으며 현재 널리 사용되고 있는 PID 제어 알고리즘은 거의 완벽한 단계의 자세 제어 기술을 선보이고 있다. 본 연구에서는 기존의 자세 제어 방법과는 달리 보다 외부 환경적인 요인으로 부터 안정적이고 지속적인 자세 제어를 할 수 있는 퍼지 로직을 기반으로 하는 스마트 자세 제어 알고리즘을 제안하고 모의실험을 통하여 기존의 방법과 그 성능을 비교 분석하고자 한다.

• 디지털산업정보학회논문지
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• 제15권2호
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• pp.43-52
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• 2019

The recent technological developments of smart devices, multiple services are provided to enhance the users' quality of life including smart city, smart energy, smart car, smart healthcare, smart home, and so on. Academia and industries try to provide the users with convenient services upon seamless technological research and developments. Also, whenever and wherever a variety of services can be used without any limitation on the place and time upon connecting with different types of devices. However, security weaknesses due to integrations of multiple technological elements have been detected resulting in the leakage of user information, account hacking, and privacy leakage, threats to people's lives by device operation have been raised. In this paper, safer communication framework is suggested by device control and user authentication in the mobile network environment. After implementations of registration and authentication processes by users and devices, safe communication protocol is designed based on this. Also, renewal process is designed according to the safe control of the device. In the performance evaluation, safety was analyzed on the attack of protocol change weakness occurred in the existing system, service halt, data leakage, illegal operation control of message, and so on, which confirmed the enhanced speed approximately by 8% and 23% in the communication and verification parts, respectively, compared to the existing system.

• 한국안전학회지
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• 제33권6호
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• pp.115-122
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• 2018

This study examined the effect of safety leadership coaching program on managers' safety management and workers' safety behaviors in construction site. Three or four managers and about one hundred workers at each site participated in this study. Safety leadership coaching program consisted of safety leadership education, goal setting, self-monitoring and feedback on workers' safety behavior, reward for three safety management behaviors; (1) safety observations of workers safety behavior and (2) providing positive feedback on safe behavior (3) providing corrective feedback on risk behavior and daily safety education for workers. Dependent variables were the percentage of safe behaviors of workers and frequency of managers' safety management behaviors. A nonconcurrent AB multiple baseline design across settings was adopted. After baseline(A), safety leadership coaching program (B) was introduced to each site. The results showed that safety leadership coaching program was effective to increase managers' and workers' safety behaviors. These results suggest that safety leadership coaching program developed in this study would be an alternative treatment technique to improve construction safety management. In addition, the implications, limitations of this study, and future studies are discussed.