• 한국신뢰성학회지:신뢰성응용연구
• /
• 제11권1호
• /
• pp.97-110
• /
• 2011

BLDC(Brushless Direct Current) motor is a powerful device to control the automotive electronic components used in green cars such as HEV/EVs(Hybrid Electric Vehicle and Electric Vehicle). This study is to propose reliability test items derived through pretesting, suitability analysis abd classification of previous BLDC motor tests. For environmental stress tests are determined by analysing environmental conditions and relevant failure mechanisms induced by climate loads, mechanical loads, chemical loads, etc. ATL and HALT are also considered for life testing and screening.

• 한국위성정보통신학회논문지
• /
• 제5권1호
• /
• pp.69-74
• /
• 2010

통신해양기상위성 개발 과정의 일환으로 통신해양기상위성이 아리안-5ECA 발사체에 탑재되어 발사될 때 발생되는 음향하중으로 부터 안전한가를 검증하기 위하여 음향진동 시험이 수행되었다. 본 논문에서는 통신해양기상위성개발 과정에서 수행된 음향진동시험과 관련하여 시험 준비 과정을 설명하고, 시험 결과에 대한 검토를 통하여 통신해양기상위성이 발사 시 경험하게 되는 음향하중에 대하여 안전한지 검토하였다. 태양전지판, Ka Band 통신탑재체 안테나 및 피드, 해양탑재체, 기상탑재체 등에 대한 상세한 검토를 통하여 통신해양기상위성이 발사 시 음향하중으로부터 안전하다는 것을 확인하였다.

• 한국구조물진단유지관리공학회 논문집
• /
• 제4권2호
• /
• pp.103-111
• /
• 2000

The objectives of the study are to know the strain distribution and modal dynamic behaviour of steel bridge girders by actual traffic load. The live load effect depends on many parameters including the span length, gross vehicle weight, axle weight, axle configuration so on. For the estimation of static and dynamic characteristic, strain data caused by moving loads and traffic characteristics of passing vehicle under actual traffic load have measured using Bridge Weigh in Motion. To confirm the reliability of BWIM system, strain data measured using the $120{\Omega}$ strain gauge under the same condition. It is considered that the data acquired from BWIM system have reliability through the analysis and comparison between stress measured by strain data from BWIM and computed by FEM. Additionally according to the measured strain data of up-line and down-line on the highway, the up-line bridge grows more faster than the down-line bridge and girder 4 and 5 carry more load when vehicles pass the inner line and girder 2 and 3 does when vehicles pass the outer line as this case(the bridge composed with 5 girders).

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2003년도 제21회 추계학술대회 논문집
• /
• pp.1-5
• /
• 2003

This paper deals with dynamic instability of slender rocket-propelled flying bodies, such as launch vehicle and advances missiles subjected to aerodynamic loads and an end rocket thrust. A flying body is simplified into a uniform free-free beam subjected to an end follower thrust. Two types of aerodynamic loads are assumed in the stability analysis. Firstly, it is assumed that two concentrated aerodynamic loads act on the flying body at its nose and tail. Secondly, to take account of effect of unsteady flow due to motion of a flexible flying body, aerodynamic load is estimated by the slender body approximation. Extended Hamilton's principle is applied to the considered beam for deriving the equation of motion. Application of FEM yields standardeigen-value problem. Dynamic stability of the beam is determined by the sign of the real part of the complex eigen-values. If aerodynamic loads are concentrated loads that act on the flying body at its nose and tail, the flutter thrust decreases by about 10% in comparison with the flutter thrust of free-free beam subjected only to an end follower thrust. If aerodynamic loads are distributed along the longitudinal axis of the flying body, the flutter thrust decreases by about 70% in comparison with the flutter thrust of free-free beam under an end follower thrust. It is found that the flutter thrust is reduced considerably if the aerodynamic loads are taken into account in addition to an end rocket thrust in the stability analysis of slender rocket-propelled flying bodies.

• 콘크리트학회논문집
• /
• 제28권5호
• /
• pp.509-517
• /
• 2016

교량의 슬래브에 파손이 발생할 경우 슬래브의 보수보강을 위한 공사로 인해 차량 통행이 제한된다. 모듈러 교량의 경우 이러한 시간적 비용을 줄일 수 있는 방법으로서 많은 연구가 진행되고 있다. 본 연구에서는 연결부에 높은 응력이 발생하는 모듈러 도로 슬래브를 온도하중과 차량하중을 적용하여 구조해석을 실시하였으며 수직연결부 부근에 나선철근을 매입하여 그 성능을 확인하였다. 또한 인양 시의 모듈러 도로 슬래브의 거동 및 취약부분을 확인하기 위하여 인양하중을 적용한 구조해석을 실시하여 유리한 조건의 인양방법을 살펴보았다. 그 결과 온도하중에 의해 수직연결부가 항복하는 것이 확인되었으며, 나선철근을 수직연결부 부분에 매립할 경우 인양 시에 구조물의 손상이 감소하는 것을 확인할 수 있었다. 또한 6개 수직연결부를 이용하여 인양할 시 3개 수직연결부 사용대비 50%의 응력을 감소시킬 수 있는 것으로 확인되었다.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
• /
• pp.2487-2492
• /
• 2011

At high rail temperature above the neutral temperature, high compressive axial stresses will occur in the rails. High thermal axial force and vehicle loads cause the track to shift in a lateral direction and the formation of track geometry imperfections (track irregularity). When the thermal stress level and track irregularity with vehicle load reach a critical value, the track loses stability. In many studies, the stability of CWR tracks is analyzed. However these studies are only considered in temperature load. The main objective of this investigation was to estimate a new, comprehensive, realistic, the stability of CWR tracks considering wheel load. The ballast resistance is changed by wheel load. When the wheel load is applied, rails and ties are moved upward or downward. In this case the friction between ties and ballasts is decreased or increased. In this study the change of the ballast resistance of each tie was applied to the nonlinear analysis of CWR tracks.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2008년도 정기 학술대회
• /
• pp.490-494
• /
• 2008

U-Channel Bridge is effective bridge type, because its edge beam performs role of barrier and enables to reduce additional dead loads. Although it is effective to reduce additional dead loads, there is possibility of bridge collapse under impact load due to car crash. Also, edge beam must have ability to induce safe driving and prevent falling accidents. Therefore, it requires behavior analysis and property investigation through the vehicle impact crashing edge beam. This study presents method of structural analysis of U-channel bridge and investigates design specifications for the effect of the edge beam under the vehicle impact. Also, it carries out stability investigation of behavior of edge beam and slab, based on Korean Highway Bridge Design Specifications and AASHTO LRFD Bridge Design Specification.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2005년도 춘계학술대회논문집
• /
• pp.521-524
• /
• 2005

To protect a satellite and electronic equipment from the acoustic loads generated by rocket propulsion system, many launch vehicle use acoustic blanket. Most high frequency region of the acoustic loads is reduced by nose fairing skins and acoustic barrier, but low frequency region is not. In order to control low frequency acoustic mode, we designed away resonator panel which was made of composite materials. This paper shows the absorption coefficient measurement result of resonator and SPL(Sound Pressure Level) reduction by using resonators in a rectangular cavity for experiment. Proper arrangement of acoustic resonators at each mode reduce effectively SPL around the satellite through changing boundary condition.

• Structural Engineering and Mechanics
• /
• 제10권3호
• /
• pp.197-209
• /
• 2000

The effects of weight and axial inertia of a beam are taken into account for studying the nonlinear vibration of the Timoshenko beam due to external loads. The combination of Galerkins method and Runge-Kutta method are employed to obtain the dynamic responses of the beam. A concentrated force and a two-axle vehicle traversing on the beam are taken as two examples to investigate the response characteristics of the beam. Results show that the effect of axial inertia of the beam increases the fundamental period of the beam. Further, both the dynamic deflection and the dynamic moment of the beam obtained with including the effect of axial inertia of the beam are greater than those of the beam without including that effect of the beam.

• 대한조선학회 특별논문집
• /
• 대한조선학회 2013년도 특별논문집
• /
• pp.60-65
• /
• 2013

Now days, the demands of new type hull lines and optimum design in relation with the EEDI (Energy Efficiency Design Index) regulation and eco-friendly high efficiency vessel design are mandatory clauses in Euro financial crises era. Therefore, in correlation with the above, we tried to find the optimum results and revealed the alterations of supporting structure for liftable car deck latch on PCTC. Generally, PCTC (Pure Car & Truck Carrier) design has been performed by 2 pillar space model F. E analysis without vehicle loads on liftable car deck to evaluate the structural adaptability. So, we applied mentioned vehicle loads on pillar and side transverse web on model to compare with not applied model and performed the ultimate strength analysis of improved design for the safety evaluation.