• 한국자동차공학회논문집
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• 제20권5호
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• pp.81-87
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• 2012

New car assessment program (NCAP) originated from USNCAP in 1979 has been implemented in several countries or markets, for instance USA, Europe, Korea, Japan, China and Australia. NCAP has contributed greatly to reduce accidental tolls. But recently, NCAP performance has no distinction between cars because manufacturer have been continuously developed to improve NCAP performance. Therefore, NHTSA announced new USNCAP protocol becoming effective from MY2011. NHTSA had carried out many NCAP tests based on the new test protocol and announced these test results. In this paper, USNCAP test results were reviewed by statistical method. This review was focused on passenger cars and frontal crash test results in order to investigate effect of changes in new NCAP protocol. There are two key changes, one is sited female dummy in passenger position, the other is enlarged to 4 scoring body regions in each dummy. Results of this review were summarized as followings. Performance in Passenger (12.5%) is lower than Driver's (50%) for number of 5 star vehicle. Neck injury criterion is dominant to NCAP star rating for both dummies in the mean sense. For standard deviation, chest deflection is showed largest value in driver dummy but neck injury criterion is showed for passenger's. DKAB and PKAB were equipped 28.1% and 6.2%, respectively. Consequently, the countermeasure for new USNCAP frontal crash test is essential to control well dummy kinematics with some safety features including KAB to reduce neck injuries.

• 소프트웨어공학소사이어티 논문지
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• 제29권1호
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• pp.13-21
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• 2020

CNN 모델이 이미지 분류와 객체 탐지 등 여러 분야에 활용됨에 따라, 자율주행자동차와 같이 안전필수시스템에 사용되는 CNN 모델의 성능은 신뢰할 수 있어야 한다. 이에 CNN 모델이 다양한 환경에서도 성능을 유지하는지 평가하기 위해 배경을 변경한 이미지를 생성하는 이미지 데이터 증강 도구를 개발한다. 이미지 데이터 증강 도구에 객체가 존재하는 이미지를 입력하면, 해당 이미지로부터 객체 이미지를 추출한 후 수집한 배경 이미지 내에 객체 이미지를 합성하여 새로운 이미지를 생성한다. CNN 모델 성능 평가 방법으로 개발한 도구를 사용하여 기존 테스트 이미지로부터 새로운 테스트 이미지를 생성하고, 생성한 새로운 테스트 이미지로 CNN 모델을 평가한다. 사례 연구로 Pascal VOC2007 테스트 데이터로부터 새로운 테스트 이미지를 생성하고, 새로운 테스트 이미지로 YOLOv3 모델을 평가하였다. 그 결과 기존 테스트 이미지의 mAP 보다 새로운 테스트 이미지의 mAP가 약 0.11 더 낮아지는 것을 확인하였다.

• 한국자동차공학회논문집
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• 제20권6호
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• pp.61-66
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• 2012

Conventional method to transform vehicle driving condition to engine operation mode is to use vehicle road load under neutral gear and mechanical efficiency of drivetrain. But this method requires additional measurement of efficiency of drivetrain on a test rig. And this measurement is normally done at fixed speed and thus estimated accuracy of engine operation mode is not considered to be high enough. This study suggests new method to calculate engine operation mode for prescribed driving mode such as NEDC using vehicle coastdown test under gear engaged condition without measurement of mechanical efficiency of drivetrain. Coastdown test was done under neutral and gear engaged condition for comparison and also trial to extract mechanical loss of drivetrain was carried out. Calculated engine torque by conventional and newly suggested method was compared with actually measured torque of a vehicle on a chassis dynamometer during NEDC. Newly suggested method showed slightly higher accuracy of accumulated brake work during NEDC.

• 대한교통학회지
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• 제23권5호
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• pp.123-134
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• 2005

본 연구는 기존의 루프검지기의 설치 및 유지보수를 위한 성능평가 방법으로서 사용해왔던 L-R-C(Inductance-Resistance-Capacitance) Test에 의한 Q Factor(질 계수)방법을 대체/보완할 수 있는 새로운 방법에 대한 연구이다. 기존의 Q Factor방법은 크게 세 가지 문제점을 수반하고 있다. 첫째, 현장의 루프검지기의 전기적 특성인 L-R-C값을 Q Factor를 기준으로 루프검지기의 현재 성능을 평가함으로써 인력에 의존하는 효율성에 문제를 안고 있으며 둘째, 루프검지시스템의 전체를 대상으로 하지 않고 일부의 측정치만으로 전체시스템을 추론하고 있다는 점과 셋째, 기존의 방법으로는 루프검지기의 검지영역, 즉 높이별 검지영역를 알 수 없다는 것이다. 따라서 본 연구에서는 이러한 문제점을 보완할 수 있는 방법으로서 루프검지기헤드에서 발생하는 자기장을 측정하여 루프검지기 전체시스템의 현재상태를 파악하고자 하였다. 이를 위하여 루프검지기에서 생성되는 자기장을 검출할 수 있는 센서와 자료수집방법, 분석방법 및 진단방법 등을 개발하였다.

• Journal of the Korean Statistical Society
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• 제30권1호
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• pp.31-39
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• 2001

For estimating parameters of possibly nonlinear and/or non-stationary seasonal autoregressive(AR) processes, we introduce a new instrumental variable method which use the direction vector of the regressors in the same period as an instrument. On the basis of the new estimator, we propose new seasonal random walk tests whose limiting null distributions are standard normal regardless of the period of seasonality and types of mean adjustments. Monte-Carlo simulation shows that he powers of he proposed tests are better than those of the tests based on ordinary least squares estimator(OLSE).

• 한국염색가공학회지
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• 제12권6호
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• pp.361-371
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• 2000

The problematic effects of fly creation on circular knitting machines during the knitting process were investigated in order to develop a new method for tackling the problem. A new idea, i.e. coating the yarn surface with a polymer film, was studied. Important physical properties of the coated yarm were studied and compared with normal yarn. A new test-rig was designed to measure the coefficient of friction and the degree of shedding of yarn. Yarns were coated with seven polymer materials and the performance of the coated yarns was tested and the results are discussed.

• 한국농공학회논문집
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• 제50권3호
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• pp.91-104
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• 2008

This study developed the WSM (weighted scenario method)-AHP method that can optimize the weighting value for multi-criteria to make GIS grid-based potential surface. The potential surface has been used to simulate urban expansion using distributed cellular automata model and to generate land-use planning as basic data. This study formulated the WSM-AHP method in mathematically and applied to test region, Suwon city, which located on south area from Seoul. WSM-AHP method generates potential map for each pair of weighting value for all criteria, which one criterion is weighted with high weighting value and the others use low weighting value, considering that the summation for all criteria weighting values should be "1". The potential change rate to the step of weighted scenario for weighting value of criteria is standardized like AHP intensity matrix in this study. From the standard potential change rate, WSM-AHP intensity matrix is completed, and then the optimal weighting value is calculated from the maximum eigenvector of the WSM-AHP matrix, according to the new WSM-AHP method developed in this study. The applied results of new method showed that the optimal weighting value from WSM-AHP is more resonable than the general AHP specialists' evaluation for weighting value. The another new finding of this study is to suggest the deterministic approach to optimize the weighting value for the distributed CA model, which is used to find new city area and to generate rational land-use planning.

• Journal of applied mathematics & informatics
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• 제15권1_2호
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• pp.29-51
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• 2004

In this paper, we propose a new mixed finite element method, called the characteristics-mixed method, for approximating the solution to Burgers' equation. This method is based upon a space-time variational form of Burgers' equation. The hyperbolic part of the equation is approximated along the characteristics in time and the diffusion part is approximated by a mixed finite element method of lowest order. The scheme is locally conservative since fluid is transported along the approximate characteristics on the discrete level and the test function can be piecewise constant. Our analysis show the new method approximate the scalar unknown and the vector flux optimally and simultaneously. We also show this scheme has much smaller time-truncation errors than those of standard methods. Numerical example is presented to show that the new scheme is easily implemented, shocks and boundary layers are handled with almost no oscillations. One of the contributions of the paper is to show how the optimal error estimates in $L^2(\Omega)$ are obtained which are much more difficult than in the standard finite element methods. These results seem to be new in the literature of finite element methods.

• 한국안전학회지
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• 제15권1호
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• pp.28-35
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• 2000

As huge energy transfer systems like a nuclear power plant, steam power plant and petrochemical plant are operated for a long time, mechanical properties are changed by degradation. The life time of the systems can be affected by the mechanical properties. So determination of the integrity of the metallic structure is required either to en4sure that failure will not occur during the service life of the components or to evaluate the lifetime extension of the structure. An automated ball indentation(ABI) method was developed as a non-destructive technique for evaluating the integrity of such metallic components. In this paper, we would like to present the aging evaluation technique by the ABI method. The five classes of the thermally aged CF8M specimens were prepared using an artificially accelerated aging method. After holding 100, 300, 900, 1800 and 3600 hours at 43$0^{\circ}C$, the specimens were cooled down using water to room temperature respectively. The tensile test, hardness test, charpy impact test, ABI test were performed. The results of the fracture test were compared with those of ABI test and the new evaluation technique of the integrity of metallic structures was developed.

• Wind and Structures
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• 제30권2호
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• pp.199-210
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• 2020

Building wind pressure coefficient transiting test is a new method to test the building wind pressure coefficient by using the wind generated by a moving vehicle, which is susceptible to natural wind and other factors. In this paper, the Commonwealth Advisory Aeronautical Research Council standard model with a scale ratio of 1:300 is used as the test object, and the wind pressure coefficient transiting test is repeated under different natural wind conditions to study the influence of natural wind. Natural wind is measured by an ultrasonic anemometer at a fixed location. All building wind pressure coefficient transiting tests meet the test conditions, and the vehicle's driving speed is 72 km/h. The mean wind pressure coefficient, the fluctuating wind pressure coefficient, and the correlation coefficient of wind pressure are used to describe the influence of natural wind on the building wind pressure coefficient transiting test qualitatively and quantitatively. Some rules, which can also help subsequent transiting tests, are also summarized.