• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.27 no.5
• /
• pp.437-450
• /
• 2014

In this study, we developed a methodology to determine the reference parameter for an aircraft impact induced risk assessment of nuclear power plant (NPP) using finite element impact analysis of containment building. The target structure used to develop the method of reference parameter selection is one of the typical Korean PWR type containment buildings. We composed a three-dimensional finite element model of the containment building. The concrete damaged plasticity model was used for the concrete material model. The steels in the tendon, rebar, and liner were modeled using the piecewise-linear stress-strain curves. To evaluate the correlations between structural response and each candidate parameter, we developed Riera's aircraft impact force-time history function with respect to the variation of the loading parameters, i.e., impact velocity and mass of the remaining fuel. For each force-time history, the type of aircraft is assumed to be a Boeing 767 model. The variation ranges of the impact velocity and remaining fuel percentage are 50 to 200m/s, and 30 to 90%, respectively. Four parameters, i.e., kinetic energy, total impulse, maximum impulse, and maximum force are proposed for candidates of the reference parameter. The wellness of the correlation between the reference parameter and structural responses was formulated using the coefficient of determination ($R^2$). From the results, we found that the maximum force showed the highest $R^2$ value in most responses in the materials. The simplicity and intuitiveness of the maximum force parameter are also remarkable compared to the other candidate parameters. Therefore, it can be concluded that the maximum force is the most proper candidate for the reference parameter to assess the aircraft impact induced risk of NPPs.

• Journal of Korean Society of Steel Construction
• /
• v.20 no.4
• /
• pp.455-467
• /
• 2008

The dynamic vehicle running tests were performed to analyze dynamic behavioral characteristics such as displacement, strain history loop and vibration acceleration in arch bridges. Also, the validity of the modeling was verified by comparing the results of the tests and those of the structural analysis modeling. With the resonance revision of verified modeling, when the ratio of excited frequencies to natural frequencies exceeds ${1{\pm}0.04}$, the stability of the bridge is obtained. Also, in the event of resonance by speed parameter, the second mode shape is dominant to the dynamic behaviors of arch bridges. It is found that manipulating the parameters involving arch ribs can increase the second mode natural frequency. It makes critical velocity greater than operational velocities to guarantee the stability of arch bridges.

• Explosives and Blasting
• /
• v.19 no.1
• /
• pp.63-70
• /
• 2001

발파진동에 영향을 미치는 여러 매개변수들 중에서 현재 발파진동 예상식을 도출하기 위해 장약량과 거리를 매개변수로 하여 발파진동을 예측하고 있다. 여기에 사용되는 장약랑은 지발당 최대장약량으로, 발파당 장약량과의 관계는 언급하고있지 않다. 따라서 본 연구에서는 지발당 최대장약량이 동일한 상태에서 발파공수를 변화시키는 방법으로 발파당 장약량이 변화할 때 발파진동속도의 변화를 비교·분석하였다. 발파공수를 5공에서 10공까지 변화시 켜가며 발파진동을 폭정하고 분석한 결과 지발당 장약량이 동일함에도 불구하고 공수가 증가함에 따라 환산거리 60∼90 구간에서 진동속도가 높게 측정되었다

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2011.04a
• /
• pp.473-476
• /
• 2011

본 논문에서는 열차와 교량의 상호작용과 주행속도에 의해 결정되어지는 진동지속시간과 차체연직가속도 증폭효과를 고려하여 철도교량의 진동사용성 허용처짐을 제시하고자 하였다. 열차가 교량을 통과할 때의 처짐 형상을 사인파로 가정하고 열차와 교량의 상호작용을 진동전달함수로 표현하여 철도교량의 진동 사용성 허용처짐을 유도하였다. 그리고 진동지속시간을 고려하기 위해 연직가속도 허용기준으로서 진동지속시간을 고려한 교량구조물의 진동사용성기준을 사용하였다. 매개변수연구를 통하여 열차 주행속도의 증가에 비례하여 차체연직가속도는 증가하지만 교량최대변위의 변화는 미미함이 확인됨으로 인하여 차체연직가속도 증가와 동반하여 연직가속도 허용기준역시 증가하는 것을 보정할 필요가 있을 것으로 판단하였다. 따라서 전개된 철도교량의 진동사용성 허용처짐식에 매개변수연구를 통하여 가정한 가속도 증폭계수를 적용하여 열차의 증속에 의한 가속도증폭효과를 고려하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2021.05a
• /
• pp.204-206
• /
• 2021

Real-time drilling parameters prediction is a considerably important study from the viewpoint of maximizing drilling efficiency. Among the methods of maximizing drilling, the method of improving the drilling speed is common, which is related to the rate of penetration, drillstring rotational speed, weight on bit, and drilling mud flow rate. This study proposes a method of predicting the drilling rate, one of the real-time drilling parameters, using a recurrent neural network-based deep learning model, and compares the existing physical-based drilling rate prediction model with a prediction model using deep learning.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.13 no.1
• /
• pp.30-34
• /
• 2009

Purpose: Many companies developed a lot of programs with continuous effort for program upgrading. With this acquire superior image quality for the purpose of quick examination and progress in spatial resolution. This study was to obtained clinical usefulness on a appropriate parameter of FWHM for speed and alpha value for superior image quality. Materials and Methods: Gamma camera by Siemens (e.cam) and spatial resolution phantom and four quadrant bar phantom used. Compared for FWHM by changed scan speed 15, 20, 25, 30, 35, 40 cm/min in scatter and non scatter in Onco Flash of spatial resolution phantom. Visual evaluation of count rate and bar phantom image for increased of alpha value of 10% in 0~100%. Results: FWHM by the scan speed was 9.37, 9.40, 9.28, 9.30, 9.31, 9.53 mm in the scatter. Count rate increased alpha value 10% increased. Visual evaluation was suitable to below 30%, Therefore spatial resolution improved on FWHM at the scan speed 25~35 cm/min applying for alpha value 30% in Onco Flash was average 9.3 mm less than FWHM of below 15 cm/min and above 40 cm/min. Conclusion: We found on appropriate parameter to progress of image quality. And there be a useful guideline for you that appropriate scan speed on vary in parameters of reduction on examination time and advancing image quality.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.24 no.2
• /
• pp.128-137
• /
• 2012

This paper deals with the local scour around a pipeline exposed to combined waves and current in the shallow water zone. To investigate the characteristics of the scour around a pipeline on the sea bed, experiments were performed according to the various pipe diameters, wave periods, wave heights, and current velocities. Wave generator and current generator were used for the experiments. Two current directions were used ; co-direction and counter direction to the waves. With the experimental results, the correlations between the scour depths and non-dimensional parameters such as Keulegan-Carpenter number(KC), Froude number(Fr), Ursell number(Ur) and velocity ratio were analysed. The relative scour depths were found obviously to be dominated by the wave component when the velocity ratio function approaches zero and those are gorverned by the current component when the velocity ratio approaches unity. Velocity ratio function was approved to be a proper parameter which is able to express the change of the scour in the combined wave and current zone. Also considering the orbital velocity and the current velocity into Fr numer and KC number respectively, scour depths show more favorable correlationship with the parameters.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.12 no.2
• /
• pp.123-130
• /
• 1992

We check up on whether the one-dimensional station precipitation model of Geogakakos and Bras is suitable to the storm model for Chonju station or not. The fundamental variables of the physically based model consists of the pressure at the cloud top, the hight-averaged updraft velocity(HAUV), and the inverse of the average diameter of the hydrometeors(ADH) at cloud base. And they are parameterized by input variables. The parameters are eastimated by the direct search algorithm of Hooke and Jeeves in this paper. The results show that HAUV and ADH are dominant factors to minimize root mean square error between the calculated and the observed rainfall. In this numerical analysis, the deviation between the calculated and the total observed rainfall is small, otherwise the gap for the time distribution is quite big.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.25 no.8
• /
• pp.1032-1038
• /
• 2021

Rate of penetration(ROP) is one of the important variables for maximizing the drilling performance. In order to maximize drilling efficiency, it is necessary to increase the drilling speed, and real-time ROP prediction is important so that the driller can identify problems during drilling. The ROP has a high correlation with the drillstring rotational speed, weight on bit, and flow rate. In this paper, the ROP was predicted using a data-driven supervised learning model trained from the drilling efficiency parameters. As a result of comparison through the performance evaluation metrics of the regression model, the root mean square error(RMSE) of the RF model was 4.20 and the mean absolute percentage error(MAPE) was 9.08%, confirming the best predictive performance. The proposed method can be used as a base model for ROP prediction when constructing a real-time drilling operation guide system.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.9A
• /
• pp.1329-1338
• /
• 1999

In this paper, an efficient signal interference control technique to improve the convergence speed of LMS algorithm is introduced. The convergence characteristics of the proposed algorithm, whose coefficients are multiply adapted in a symbol time period by recycling the received data, are analyzed to prove theoretically the improvement of convergence speed. According as the step-size parameter $\mu$ is increased, the rate of convergence of the algorithm is controlled. Also, a increase in the step-size parameter $\mu$ has the effect of reducing the variation in the experimentally computed learning curve. Increasing the eigenvalue spread has the effect of controlling down the rate of convergence of the adaptive equalizer and also increasing the steady-state value of the mean squared error and also demonstrate the superiority of signal interference control to the filter algorithm increasing convergence speed by (B+1) times due to the data-recycling LMS technique.