• Advances in aircraft and spacecraft science
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• 제5권3호
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• pp.319-334
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• 2018

In this study, the failure mode and energy absorption capabilities of a composite shock absorber device, during an emergency landing are evaluated. The prototype has been installed and tested in laboratory simulating an emergency landing test condition. The crash absorber presents an innovative configuration able to reduce the loads transmitted to a helicopter fuselage during an emergency landing. It consists of a composite tailored tube installed on the landing gear strut. During an emergency landing this crash absorber system should be able to absorb energy through a pre-designed deformation. This solution, compared to an oleo-pneumatic shock absorber, avoids sealing checks, very high values of the shock absorber pressure, and results to be lighter, easy in maintenance, inspect and use. The activities reported in this paper have become an attractive research field both from the scientific viewpoint and the prospect of industrial applications, because they offer benefits in terms of energy absorbing, weight savings, increasing the safety levels, and finally reducing the costs in a global sense.

• 드라이브 ㆍ 컨트롤
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• 제20권3호
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• pp.9-14
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• 2023

In this paper, the selection of a reliable accelerated life test code for a 2-ton forklift was accomplished by choosing the driving resistance coefficient failure-free test time based on a 10,000-hour B₁₀ life. The overall life and average equivalent load of the vehicle were then calculated based on actual driving test conditions using the selected driving resistance coefficient. The gear train's accelerated life test code was selected by adjusting the equivalent load to a torque and rotation speed that did not exceed 125%(about 75HP) of the vehicle rated power. The safety of the test standards was validated by conducting an actual accelerated life test utilizing the proposed test method in this study and comparing the test result with the corresponding theoretical value. It is anticipated that the reliability of the accelerated life test in this paper will be enhanced, by incorporating actual driving performance data collected directly from the forklift and adjusting the conditions used in developing the accelerated life test code.

• 한국군사과학기술학회지
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• 제26권2호
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• pp.113-121
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• 2023

High-precision lasers and anti-aircraft radars are the main equipment to protect the Korean Peninsula, and require preemptive maintenance before signs of failure. Of the key components in the drive sector, bearings do not have a fault alarm function. Therefore, the technology for diagnosing defects in bearings before the performance degradation of equipment occurs is becoming more important. In this paper, for the experimental analysis, we measured the acceleration of the four sets of the same lot using acceleration sensors. Through periodic measurements, the factors that changed until the bearing stopped rotating were analyzed. To determine the replacement time, the main factors and threshold values of the bearing signal were analyzed. The error of the theoretical and experimental analysis results of the defect frequency was within 2.8 %, and the validity of the theoretical analysis results could be confirmed. Based on the results, it is possible to remotely transmit trouble alerts to users through the system check function.

• 한국정밀공학회지
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• 제33권10호
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• pp.829-835
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• 2016

Electro-Mechanical Actuator installed on the aircraft plays a key role in an aircraft's flight control through flight control computer. Reliable prediction of the actuator is important for the aircraft. To estimate the lifetime of a product, it is necessary to test full target life. However, it is very difficult to perform it due to the long life time of actuator but short period of development time with increasing cost. Therefore, accelerated life test has been used to reduce the test time for various reasons such as reducing product's development cycle and cost. In this paper, to predict the lifetime of the actuator, we analyzed the flight profile of aircraft and adapted the method of accelerated life test in order to accelerate failure modes that might occur under user conditions. We also set up an endurance test equipment for validating the demanded lifetime of an actuator and performed accelerated life test.

• Nuclear Engineering and Technology
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• 제52권2호
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• pp.417-428
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• 2020

Investigations of the commercial aircraft impact effect on nuclear island infrastructures have been drawing extensive attention, and this paper aims to perform the safety assessment of Generation III nuclear power plant (NPP) buildings subjected to typical commercial aircrafts crash. At present Part III, the local damage of the rigid components of aircraft, e.g., engine and landing gear, impacting the steel concrete (SC) structures of NPP containment is mainly discussed. Two typical SC target panels with the thicknesses of 40 mm and 100 mm, as well as the steel cylindrical projectile with a mass of 2.15 kg and a diameter of 80 mm are fabricated. By using a large-caliber air gas gun, both the projectile penetration and perforation test are conducted, in which the striking velocities were ranged from 96 m/s to 157 m/s. The bulging velocity and the maximal deflection of rear steel plate, as well as penetration depth of projectile are derived, and the local deformation and failure modes of SC panels are assessed experimentally. Then, the commercial finite element program LS-DYNA is utilized to perform the numerical simulations, by comparisons with the experimental and simulated projectile impact process and SC panel damage, the numerical algorithm, constitutive models and the corresponding parameters are verified. The present work can provide helpful references for the evaluation of the local impact resistance of NPP buildings against the aircraft engine.

• 한국산학기술학회논문지
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• 제15권8호
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• pp.4742-4748
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• 2014

전북 익산시 R회사에서 기 개발된 세미오토 클러치는 수동클러치 차량의 기어 변속시 클러치 페달을 밟아야하는 불편함을 해소하고자 만들어진 장치로써 클러치 페달을 밟지 않고, 운전자가 기어봉에 위치한 스위치 조작만으로도 클러치 동작을 제어할 수 있다. 차량의 변속과정에서 클러치 동작을 제어하기 위해 센서를 설치하여 차량정보를 수집하여 제어하였다. 그러나, 센서 기반의 제어기는 열악한 운전조건에서 고장 원인이 되고 있으며, 차량에 설치하고 보수하는 과정에서 시간소요가 과다하여 많은 불편을 가지고 있었다. 이를 위해 본 연구에서는 차량의 ECU와 CAN통신을 통해 차량의 주행정보를 수집하여 제어하고, 공압 액추에이터로 클러치를 동작시키는 세미오토 클러치를 개발하였다. 개발된 공압 액추에이터의 정상적인 동작을 위해서는 최소 3bar이상이 요구되었다.

• 한국항해항만학회지
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• 제41권5호
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• pp.277-286
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• 2017

IMO introduced e-Navigation concept to improve the efficiency of ship operation, port operation, and ship navigation technology. IMO proposed sixteen MSPs (Maritime Service Portfolio) applicable to the ships and onshore in case of e-Navigation implementation. In order to meet the demands of the international society, the system implementation work for the Korean e-Navigation has been specified. The Korean e-Navigation system has five service categories: the S2 service category, which is a ship anomaly monitoring service, is a service that classifies emergency levels according to the degree of abnormal condition when a ship has an abnormality in ship operation, and provides guidance for emergency situations. The navigation safety module is a sub-module of the S2 service that determines the emergency level in case of navigation equipment malfunctioning, engine or steering gear failure during navigation. It provides emergency response guidance based on emergency level to the abnormal ship. If an abnormal condition occurs during the ship operation, first, the ship shall determine the emergency level, according to the degree of abnormality of the ship. Second, an emergency response guidance is generated based on the determined emergency level, and the guidance is transmitted to the ship, which helps the navigators prevent accidents and not to spread. In this study, the operational concept for the implementation of the Korean e-Navigation system is designed and the concept is focused on the navigation safety module of S2 service.

• 한국소음진동공학회논문집
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• 제24권9호
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• pp.667-674
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• 2014

선박의 추진축계는 외부 변동 부하에 의해서 축계 손상을 일으킬 수 있다. 이러한 추진축계의 동역학적인 특성은 운전 중에 일어나는 공진을 견딜 수 있거나 또는 피하도록 설계 및 최적화 해야 한다. 이러한 공진은 대빙급 선박의 추진시스템의 설계에 요구되는 프로펠러에서 유체역학적인 상호작용에 기인한다. 추진축계는 프로펠러와 대빙 사이의 상호관계로 인한 과도부하와 시스템의 공진에 의해서 진지한 응력을 받게 된다. 이 논문은 대빙이 적용된 극지 연구 선박에서 추진축계의 과도비틀림 진동응답을 검토하고자 한다. 추진축계는 전기모터로 구동되는 원동기, 탄성커플링 기어 및 프로펠러로 구성되어 있다. 이론적인 해석은 프로펠러의 대빙 부하를 기진력으로 과도비틀림진동 해석을 수행하였다. 그리고 실선에서 비틀림 진동을 계측하고 공진점을 확인하고 이를 이용하여 추진축계 한계 설계 토크에 대한 적용된 평가 요소를 국제선급연합 규정과 비교하였다. 전기모터를 갖는 추진축계에서 공진을 초래하는 탄성커플링의 강성 선정의 영향을 검토하였다.

• International journal of advanced smart convergence
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• 제9권1호
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• pp.54-62
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• 2020

According to the Ministry of Health and Welfare, "Status of Registered Persons with Disabilities", the number of people with disabilities is 2,494,460 as of 2015. The lowest rates of children with disabilities were intellectual disabilities (23%) and mental disorders (33.3%). The highest rates of screening were blindness (97%), heart failure (94.4%), and hearing impairment (92.7%). 65.2% of visually impaired people who have already had a disability at the time of marriage, and the remaining 34.8% can be thought to be the cause of high incidence of disability after marriage. 'SID (Seed in the Dark)' project was designed to recapture the visually impaired parent's desire for attachment and the space difficulties of the blind who want to be a normal parent to their children through a visual impairment of a father with 7-year-old daughter. Using Gear VR(Virtual Reality), the general public was able to feel the surroundings as if they had no vision and focused on the hearing. Especially, We expressed the sound wave visually and added the hilarious game element which grasps the terrain of the maze by sound wave like a 'blind person who perceives the surroundings by sound' and catches up with daughter. People with disabilities who are far from mental illness often have a form of family with children. The fact that the rate of childbirth is high means that there is relatively little problem in daily life. It is wondered that the rate of blindness among the visually impaired, which accounts for 10% of the total disabled, is the highest at 97%. This is because, in the case of the visually impaired, the obstacle is often caused by aging, accidents, or diseases due to inherited causes rather than the visual disorder. In particular, However, the fact that there is an obstacle in vision that accounts for 83% of the body's sensory organs causes other difficulties in the nursing process of children who are non-disabled. Parents do not know the face of child when their visual impairment is severe. Parents are extremely anxious about worry that they will be lost or abducted if their children are not by their side. And that the child recognizes the disability of his or her parents other than the other parents easily and takes it as a deficiency. Since visually impaired parents are mentally mature parents with non-disabled people, they may want their children not to feel deprived of their disability. The number of people with visual impairments has been increasing since 2001, and people with impairments often become disabled. In addition, there is much research on the problem of nondisabled parents who have children with disabilities, while there is relatively little interest and research on the problem of nondisabled child rearing of parents with disabilities.

• 한국안전학회지
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• 제25권6호
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• pp.34-39
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• 2010

본 연구는 건설현장에서 사용하고 있는 타워크레인에 대한 검사기관의 검사결과를 토대로 위험성과 중요도를 미리 검토하고 분석하여, 상호간의 검사 기준에 대한 판정기준을 정립하고 검사능력을 UP-Grade 시킬 수 있는 기회로 활용하기 위한 방안으로, 적절한 평가방법을 도입하여 객관적인 평가 모텔을 제시하는데 목적이 있다. 타워크레인은 건축물 또는 구조물 등, 건설현장에 설치되어 짧게는 2~3개월부터 2년 남짓 동안 지상에서 20~150M 이상 높은 곳으로 건설자재와 중량물 등을 실어 나르는 기계장치로, 건설 현장에서는 없어서는 안될 중요한 설비이다. 그러나 설치해서 사용하는 기간이 짧고, 건설 현장의 기술자들이 타워크레인에 대한 전문 기술력이 부족하여 체계적이고 정량적인 안전관리가 이루어지지 않고 있다. 이러한 문제점을 해결하기 위해서 전문가들의 지식과 경험을 바탕을 한 지식기반기법과 타워크레인에 적용 가능한 RBI절차 연구의 일환으로 정량적 위험우선순위를 FMEA기법을 활용하여 RPN을 적용시켜 보았다. 일반적인 RBI 80/20 Rule을 적용시켜 보았을 때, 위험도가 높은 부분은 와이어로프, 권과방지장치 및 브레이크와 권상감속기 등으로 나타났다. 하지만, 아직 타워크레인에 대한 위험분석이 제대로 이루어지지 않아 미흡한 부분이 많지만, 본 연구를 시작으로 좀 더 경험과 지식이 풍부한 전문가들이 나서서 중요 정보를 공유하고 data base화 하여, 타워크레인에 대한 활발한 RBI 기법의 보완과 지속적인 연구개발이 필요하다.