• 제목/요약/키워드: Shock-Test

검색결과 980건 처리시간 0.023초

보행 장애인의 승차감 개선을 위한 휠체어용 능동형 서스펜션 시스템 개발 (Development of Active Suspension System for Wheelchairs to Improve Riding Comfort of Gait Disorders)

  • 허영준;전금상;이상훈;최성대;장익규
    • 대한의용생체공학회:의공학회지
    • /
    • 제41권5호
    • /
    • pp.203-209
    • /
    • 2020
  • As the number of people with gait disorders increases, the demand for using wheelchairs increases and the area of a ctivity for people with disabilities expands, thereby they increasing the demand for riding comfortability in various driving environments. Therefore, this study is to develop an entry-level active suspension system that apply to wheelchairs and to evaluate its usability. The suspension applied in this paper consists of a coil spring, a shock absorber, a control module to control the strength of the shock absorber, and a road surface condition monitoring system. A wheelchair occupant secures the riding comfort by adjusting the coil strength of the shock absorber in 12 steps according to various road conditions. Therefore, the mechanical properties were evaluated through the structural analysis of the suspension system, and the tendency toward the magnitude of the road surface vibration attenuated according to the rigidity of the suspension through the vibration test was attempted. In conclusion, as a result of structural analysis of the suspension system, stress in a range lower than the yield strength of the material was generated, and the vibration test showed the effect of attenuating the vibration generated from the road surface when the stiffness of the suspension was adjusted.

철도차량 장치의 진동 및 충격시험 방법 비교 분석 (Comparison and Analysis of Vibration and Shock Test Methods for Rolling Stock Equipment)

  • 김영국;박찬경;류준형
    • 한국철도학회논문집
    • /
    • 제16권4호
    • /
    • pp.246-252
    • /
    • 2013
  • 철도차량은 차량조건, 선로조건 및 운행조건들에 의한 많은 진동원에 의해 매우 복잡한 형태의 진동과 충격이 발생한다. 진동과 충격은 철도차량에 부착되어 있는 부품 및 구성품을 고장시키는 원인이 된다. 이러한 진동 및 충격에 의한 장치의 고장을 줄이기 위해서는 개발단계에서부터 진동과 충격시험을 통해 장치가 진동과 충격에 견디는 지를 확인한 후에 철도차량에 장착하고 있다. 국내에는 서로 상이한 방법을 적용한 여러 가지의 철도차량 진동 및 충격시험 규격이 사용되고 있다. 본 논문에서는 국내에서 대표적으로 사용되는 규격인 IEC 61373과 KS R 9144, KS R 9146에 대해 상대적 비교를 통해 진동과 충격시험의 방법에 대한 차이점을 고찰함으로써 진동시험 관련자들이 정확한 진동 및 충격시험을 할 수 있도록 하고자 한다.

분전반 관리시스템 평가를 위한 시험 장치의 제작 및 특성 분석 (Manufacturing and Characteristics Analysis of a Testing Device for the Evaluation of a Distribution Board Management System)

  • 고완수;이병설;최충석
    • 한국안전학회지
    • /
    • 제34권5호
    • /
    • pp.31-36
    • /
    • 2019
  • This study made a testing device to evaluate the distribution board management system. Power was supplied to the testing device using a loading-back method and the voltage applied to it was 440 V at the same turn ratio. When the human body electric shock current is 30 mA, the breaking time is set to be less than 240 ms while 30~45 mA current is flowing. The test result shows that in the case of the R-phase it was measured to be 5.19 Hz (193 ms). And the S-phase and T-phase were perfectly cut off at 5.39 Hz (186 ms) and 5.71 Hz (175 ms), respectively. When the human body electric shock current is 60mA, the breaking time is set to be less than 120 ms while 45~75 mA current is flowing. The test result shows that the R-phase, S-phase, and T-phase were accurately cut off at 8.39 Hz (11 ms), 8.87Hz (113 ms) and 9.69 Hz (103 ms), respectively. When the human body electric shock current is 90 mA, the breaking time is set to be less than 48 ms while 75 mA current is flowing. The test result shows that the R-phase, S-phase, and T-phase were accurately cut off at 19.8 Hz (50.4 ms), 16.9 Hz (59.2 ms), and 17.9 Hz (56.0 ms), respectively. That is, the developed testing device satisfied all the requirements of the distribution board evaluation criteria, and it becomes available for the performance evaluation of the distribution board management system.

다양한 유무연 도금 리드프레임에 적용된 Sn-8Zn-3Bi 솔더 접합부의 열충격 신뢰성 평가 (Reliability of Sn-8Zn-3Bi Solder Paste Applied to Lead and Lead-free Plating on Lead-frame under Thermal Shock Test)

  • 한성원;조일제;신영의
    • 마이크로전자및패키징학회지
    • /
    • 제14권2호
    • /
    • pp.35-40
    • /
    • 2007
  • Sn-8Zn-3Bi 무연 솔더 페이스트의 접합부신뢰성 및 적합성을 평가하기 위해 유(SnPb) 무연(Sn, SnBi)도금된 Cu 리드프레임 QFP(Quad Flat Packager)를 사용하여 열충격 조건 하에서의 인장 강도의 변화 및 파괴 기구에 대한 분석을 실시하였다. 리드 도금의 종류에 상관없이 모든 시험 시편에서 열충격 사이클 수의 증가에 비례하여 접합부의 취성 특성이 강화되어 인장 강도가 감소하는 것을 확인하였다. 하지만, 접합부에는 열팽창 계수의 차이에 의해 야기될 수 있는 미세 균열은 발견되지 않았다. 단면 관찰 및 변위 이력 곡선 분석을 통하여 열충격 사이클 수의 증가에 따른 인강 강도의 감소는 접합부의 파괴 기구의 변화에 기인되었음을 확인하였다. 본 실험을 통해 Sn-3Zn-3Bi 솔더의 유 무연 도금 Cu 리드프레임과의 우수한 작업 특성과 열충격 환경 하에서도 우수한 기계적 접합 특성을 유지하는 것을 확인할 수 있었다.

  • PDF

Effects of chemistry in Mars entry and Earth re-entry

  • Zuppardi, Gennaro
    • Advances in aircraft and spacecraft science
    • /
    • 제5권5호
    • /
    • pp.581-594
    • /
    • 2018
  • This paper is the follow-on of a previous paper by the author where it was pointed out that the forthcoming, manned exploration missions to Mars, by means of complex geometry spacecraft, involve the study of phenomena like shock wave-boundary layer interaction and shock wave-shock wave interaction also along the entry path in Mars atmosphere. The present paper focuses the chemical effects both in the shock layer and on the surface of a test body along the Mars orbital entry and compares these effects with those along the Earth orbital re-entry. As well known, the Mars atmosphere is almost made up of Carbon dioxide whose dissociation energy is even lower than that of Oxygen. Therefore, although the Mars entry is less energized than the Earth re-entry, one can expect that the effects of chemistry on aerodynamic quantities, both in the shock layer and on a test body surface, are different from those along the Earth re-entry. The study has been carried out computationally by means of a direct simulation Monte Carlo code, simulating the nose of an aero-space-plane and using, as free stream parameters, those along the Mars entry and Earth re-entry trajectories in the altitude interval 60-90 km. At each altitude, three chemical conditions have been considered: 1) gas non reactive and non-catalytic surface, 2) gas reactive and non-catalytic surface, 3) gas reactive and fully-catalytic surface. The results showed that the number of reactions, both in the flow and on the nose surface, is higher for Earth and, correspondingly, also the effects on the aerodynamic quantities.

충격파 터널을 이용한 고속추진기관 시험 연구 (High Speed Propulsion System Test Research Using a Shock Tunnel)

  • 박기수;변종렬;최호진;진유인;박철;황기영
    • 한국추진공학회지
    • /
    • 제18권5호
    • /
    • pp.43-53
    • /
    • 2014
  • 충격파 터널은 초음속 및 극초음속 비행조건의 유동장을 지상에서 가장 유사하게 모사할 수 있는 시험설비로서, 거의 반세기 동안 전 세계적으로 유용하게 운용되고 있다. 국내의 극초음속 비행체에 대한 많은 관심의 결과로 충격파 시험장치에 대해 주목하고 있으며, 최근에 KAIST에서는 중간 크기의 충격파 터널을 갖추게 되었다. 본 논문은 개발된 충격파 터널의 성능과 최근 수행된 모델 스크램제트 시험자료를 제시하고 있다. 본 연구에서 모사된 자유흐름 유동조건은 마하수 5.7 비행속도에 해당하며, 이러한 비행조건에서 스크램제트의 초음속 연소기내에 유동 환경을 모사하였다.

Tests on explosion-resisting properties of high-performance equal-sized-aggregate concrete composite sandwich plates

  • Yizhong Tan;Songlin Yue;Gan Li;Chao Li;Yihao Cheng;Wei Dai;Bo Zhang
    • Structural Engineering and Mechanics
    • /
    • 제87권4호
    • /
    • pp.297-304
    • /
    • 2023
  • Targeted introduction of explosion-resisting and energy-absorbing materials and optimization of explosion-resisting composite structural styles in underground engineering are the most important measures for modern engineering protection. They could also improve the survivability of underground engineering in wartime. In order to test explosion-resisting and energy-absorbing effects of high-performance equal-sized-aggregate (HPESA) concrete, the explosive loading tests were conducted on HPESA concrete composite plates by field simple explosion craters. Time-history curves of the explosion pressure at the interfaces were obtained under six conditions with different explosion ranges and different thicknesses of the HPESA concrete plate. Test results show that under the same explosion range, composite plate structures with different thicknesses of the HPESA concrete plate differ significantly in terms of the wave-absorbing ability. Under the three thicknesses in the tests, the wave-absorbing ability is enhanced with the growing thickness and the maximum pressure attenuation index reaches 83.4%. The energy attenuation coefficient of the HPESA concrete plate under different conditions was regressively fitted. The natural logarithm relations between the interlayer plate thickness and the energy attenuation coefficient under the two explosion ranges were attained.

VAR 모형을 이용한 주가, 금리, 물가, 주택가격의 관계에 대한 실증연구 (An Empirical Analysis on the Relationship between Stock Price, Interest Rate, Price Index and Housing Price using VAR Model)

  • 김재경
    • 유통과학연구
    • /
    • 제11권10호
    • /
    • pp.63-72
    • /
    • 2013
  • Purpose - This study analyzes the relationship and dynamic interactions between stock price index, interest rate, price index, and housing price indices using Korean monthly data from 2000 to 2013, based on a VAR model. This study also examines Granger causal relationships among these variables in order to determine whether the time series of one is useful in forecasting another, or to infer certain types of causal dependency between stochastic variables. Research design, data, and methodology - We used Korean monthly data for all variables from 2000: M1 to 2013: M3. First, we checked the correlations among different variables. Second, we conducted the Augmented Dickey-Fuller (ADF) test and the co-integration test using the VAR model. Third, we employed Granger Causality tests to quantify the causal effect from time series observations. Fourth, we used the impulse response function and variance decomposition based on the VAR model to examine the dynamic relationships among the variables. Results - First, stock price Granger affects interest rate and all housing price indices. Price index Granger, in turn, affects the stock price and six metropolitan housing price indices. However, none of the Granger variables affect the price index. Therefore, it is the stock markets (and not the housing market) that affects the housing prices. Second, the impulse response tests show that maximum influence on stock price is its own, and though it is influenced a little by interest rate, price index affects it negatively. One standard deviation (S.D.) shock to stock price increases the housing price by 0.08 units after two months, whereas an impulse shock to the interest rate negatively impacts the housing price. Third, the variance decomposition results report that the shock to the stock price accounts for 96% of the variation in the stock price, and the shock to the price index accounts for 2.8% after two periods. In contrast, the shock to the interest rate accounts for 80% of the variation in the interest rate after ten periods; the shock to the stock price accounts for 19% of the variation; however, shock to the price index does not affect the interest rate. The housing price index in 10 periods is explained up to 96.7% by itself, 2.62% by stock price, 0.68% by price index, and 0.04% by interest rate. Therefore, the housing market is explained most by its own variation, whereas the interest rate has little impact on housing price. Conclusions - The results of the study elucidate the relationship and dynamic interactions among stock price index, interest rate, price index, and housing price indices using VAR model. This study could help form the basis for more appropriate economic policies in the future. As the housing market is very important in Korean economy, any changes in house price affect the other markets, thereby resulting in a shock to the entire economy. Therefore, the analysis on the dynamic relationships between the housing market and economic variables will help with the decision making regarding the housing market policy.

간호대학생의 전환충격과 임상실습적응의 관계에서 감성지능의 조절효과 (The Moderating Effect of Emotional Intelligence on the Relationship between Transition Shock and Adaptation on Clinical Practice among Nursing Students)

  • 이외선;김은재
    • 디지털융복합연구
    • /
    • 제17권11호
    • /
    • pp.387-394
    • /
    • 2019
  • 본 연구는 간호대학생의 전환충격과 임상실습적응과의 관계에서 감성지능의 조절효과를 파악하기 위해 시도되었다. 간호대학 3학년에 재학 중인 185명을 대상으로 설문지를 이용하여 2019년 5월 1일부터 2019년 6월 14일까지 자료를 수집하였다. SPSS WIN 23을 이용하여 빈도, t-test, ANOVA, Pearson's correlation, 위계적 회귀분석으로 분석하였다. 연구결과 간호대학생의 전환충격은 4점 만점에 2.32점, 감성지능은 5점 만점에 3.61점, 임상실습적응은 5점 만점에 3.40점으로 나타났다. 전환충격은 감성지능(r=-.26. p <.001), 임상실습적응(r=-.43. p <.001)과는 유의한 부적 상관관계가 있는 것으로 나타났고, 감성지능은 임상실습 적응과는 유의한 정적 상관관계(r=.36. p <.001)가 있는 것으로 나타났다. 그리고 감성지능이 전환충격과 임상실습적응과의 관계를 조절하는 것으로 나타났다(${\Delta}R^2=0.21$, p<.001). 따라서 간호대학생의 감성지능을 향상 시킬 수 있는 프로그램을 적용하여 전환충격을 감소시켜 임상실습에 잘 적응하도록 하여야 할 것으로 생각된다.

열간단조 금형강의 열충격과 열피로 특성연구 (Analysis of Thermal Shock and Thermal Fatigue in Tool Steels for Hot Forging)

  • 김정운;문영훈;류재화;박형호
    • 소성∙가공
    • /
    • 제11권1호
    • /
    • pp.61-68
    • /
    • 2002
  • The thermal shock and thermal fatigue test has been carried out to analyze the thermal characteristics of tool steels for hot forging and the effects of mechanical properties on this study have been investigated. The resistance to thermal shock is first of all a matter of good toughness and ductility. Therefore, a proper hot-work tool steel should be characterized by high fracture strength and high temperature toughness. Based on these results, some critical temperature($T_{fracture}$) at which fracture occur can be measured to characterize the thermal resistance of the materials. During thermal fatigue tests, the thermal fatigue cracks occur because of the repetitive heating and cooling of the die surface and the thermal fatigue damage was evaluated by analyzing different number of cycles to failure. The results showed that the resistance to thermal shock and thermal fatigue were found to be favoured by high hot tensile strength and high hot hardness, and thermal resistance of SKD61 was superior to that of ESC, SKT4 and this was caused by higher mechanical properties of SKD61.