• Journal of the Korea Concrete Institute
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• v.14 no.5
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• pp.638-644
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• 2002

The stress-strain relationship of polymer concrete flexural member was evaluated using C-shaped polyester concrete specimen, the compressive strength of which is 1400 kgf/$\textrm{cm}^2$. Eccentric compression test was performed to estimate the parameters, ${\alpha}$, ${\beta}$1, ${\gamma}$ for equivalent rectangular stress block. The ultimate moment strength ware obtained from the bending test on reinforced polymer concrete beams which were prepared with S different tensile steel ratios with a shear span ratio of 4.0. These values were compared with theoretical ultimate moment strengths, which were obtained using the parameters ${\alpha}$=0.61 and ${\beta}$1=0.73 from stress-stain curves of C-shaped specimens. The results showed that, when tensile steel ratio was over 0.50 $\rho$b, the experimentally obtained moment strengths were well matched with theoretically calculated values. In order to develop accurate criteria for polymer concrete flexural members, however, many other expermental studies for parameter determination are necessary using C-shaped specimens which have various compressive strengths and different sizes.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.3
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• pp.259-268
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• 2016

The service life evaluation in RC(Reinforced Concrete) structure exposed to chloride attack can be classified into deterministic and probabilistic method, and it significantly varies with design parameters. The present work derives PDF (Probability of Durability Failure) and the related service life considering time-dependent diffusion coefficient and internal parameters such as reference diffusion coefficient, critical chloride content, and time-exponent. When critical chloride content increases to 133.3%, the changing ratios of service life are 134.0~145.4% for deterministic method and 149.2%~152.5% for probabilistic method, respectively. In the case of increasing time-exponent to 200%, they increase to 323.8% for deterministic method and 346.0% for probabilistic method. Through adopting time-diffusion coefficient for probabilistic method, reasonable service life evaluation can be achieved, and it is also verified that increasing time-exponent through mineral admixture is very effective to extension of service life in RC structure.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.6
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• pp.1-10
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• 2007

This paper presents a direct nonlinear multivariable self-tuning PID controller using neural network which adapts to the changing parameters of the nonlinear multivariable system with noises and time delays. The nonlinear multivariable system is divided linear part and nonlinear part. The linear controller are used the self-tuning PID controller that can combine the simple structure of a PID controllers with the characteristics of a self-tuning controller, which can adapt to changes in the environment. The linear controller parameters are obtained by the recursive least square. And the nonlinear controller parameters are achieved the through the Back-propagation neural network. In order to demonstrate the effectiveness of the proposed algorithm, the computer simulation results are presented to adapt the nonlinear multivariable system with noises and time delays and with changed system parameter after a constant time. The proposed PID type nonlinear multivariable self-tuning method using neural network is effective compared with the conventional direct multivariable adaptive controller using neural network.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.1
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• pp.22-28
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• 2013

Robotic GMA (Gas Metal Arc) welding process is one of widely acceptable metal joining process. The heat and mass inputs are coupled and transferred by the weld arc to the molten weld pool and by the molten metal that is being transferred to the weld pool. The amount and distribution of the input energy are basically controlled by the obvious and careful choices of welding process parameters in order to accomplish the optimal bead geometry and the desired quality of the weldment. To make effective use of automated and robotic GMA welding, it is imperative to predict online faults for bead geometry and welding quality with respect to welding parameters, applicable to all welding positions and covering a wide range of material thickness. MD (Mahalanobis Distance) technique was employed for investigating and modeling the GMA welding process and significance test techniques were applied for the interpretation of the experimental data. To successfully accomplish this objective, two sets of experiment were performed with different welding parameters; the welded samples from SM 490A steel flats. First, a set of weldments without any faults were generated in a number of repeated sessions in order to be used as references. The experimental results of current and voltage waveforms were used to predict the magnitude of bead geometry and welding quality, and to establish the relationships between weld process parameters and online welding faults. Statistical models developed from experimental results which can be used to quantify the welding quality with respect to process parameters in order to achieve the desired bead geometry based on weld quality criteria.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.11
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• pp.1221-1229
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• 2014

This paper proposes an approach for predicting the fatigue life of a propeller shaft of a forklift truck by an accelerated life test method. The accelerated life test method adopted in this study is the calibrated accelerated life test, which is highly effective in the prediction of the lifetime and enables significant reduction of the test time as well as a quantification of reliability in the case of small sample sizes. First, the fatigue test was performed under two high stress levels, and then, it was performed by setting low stress levels in consideration of the available test time and extrapolation. Major reliability parameters such as the lifetime, accelerated power index, and shape parameter were obtained experimentally, and the experimentally predicted lifetime of the propeller shaft was verified through comparison with results of an analysis of load spectrum data under actual operating conditions.

• Journal of Internet Computing and Services
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• v.8 no.5
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• pp.117-123
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• 2007

Catadioptric mirrors are widely used in automatic surveillance system. The major drawback of catadioptric mirror is its unequal image resolution. Equidistance catadioptric mirrir can be the solution to this problem. The exact axial alignment and the exact mount of mirror are the sources that can be avoided but the focal length variation is inevitable. In this paper, the effects of focal length variation on the computation of depth and height of object' point are explained and the effective and simple focal length finding algorithm is presented. First two object's points are selected, and the counterparts on the other stereo image are to be found using MSE criterion. Using four pixel distance from the image center, the assumed focal length is calculated. If the obtained focal length is different from the exact focal length, 24mm, the focal length value is modified by the proposed method. The method is very simple and gives the comparable results with the earlier sophisticated method.

• Journal of Animal Reproduction and Biotechnology
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• v.34 no.3
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• pp.166-172
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• 2019

Heart rate is a relatively simple and non-invasive method that is used as an important physiological indicator in many studies and has a close relationship with heart structure and function, cardiovascular disease and sudden cardiac death. In general, appropriately low heart rate during resting means effective heart function and cardiovascular fitness; heart rate at recovery is an important indicator of health and disease condition. We found a beagle dog (Dog_1) with a high heart rate in the previous preliminary experiment. Therefore, purpose of this study was to compare the heart rate response of the Dog_1 with the control group during 12 weeks of interval exercise, to evaluate the structural and functional abnormalities of the heart and to verify the applicability of exercise program. Heart rate was checked during 12 weeks of interval exercise, and after the exercise was over, imaging examination and hematological and serum biochemistry were performed. As a result, Dog_1 (165.6 ± 1.5) showed significantly higher heart rate in low intensity session of interval exercise than control group (133.3 ± 0.5, p < 0.01). In addition, Dog_1 (181.2 ± 1.4) showed significantly higher heart rate than control group (155.1 ± 0.9) in high intensity session (p < 0.01). The heart rate (30 sec, 60 sec) during recovery state was higher in Dog_1 (30 sec: 156.8 ± 4.0, 60 sec: 166.8 ± 5.8) than in the control group (30 sec: 111.2 ± 2.5, 60 sec: 104.0 ± 5.1, p < 0.01). The results of the imaging examination of Dog_1 with high heart rate confirmed that the heart had no functional and structural abnormalities. All beagles with the interval exercise program did not show maladjustment, and in the hematological and serum biochemistry results, all the parameter were within the reference range. If the interval exercise program of this study is used in the future, it is expected to be used as an important basic data to achieve the purpose of health, welfare, and physical fitness improvement of dogs.

• International Journal of Aeronautical and Space Sciences
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• v.13 no.4
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• pp.491-498
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• 2012

A Ground Based Augmentation System (GBAS) is an enabling technology for an aircraft's precision approach based on a Global Navigation Satellite System (GNSS). However, GBAS is vulnerable to interference, so effective GNSS interference detection and mitigation methods need to be employed. In this paper, an intentional GNSS interference detection and characterization algorithm is proposed. The algorithm uses Automatic Gain Control (AGC) gain and adaptive notch filter parameters to classify types of incoming interference and to characterize them. The AGC gain and adaptive lattice IIR notch filter parameter values in GNSS receivers are examined according to interference types and power levels. Based on those data, the interference detection and characterization algorithm is developed and Monte Carlo simulations are carried out for performance analysis of the proposed method. Here, the proposed algorithm is used to detect and characterize single-tone continuous wave interference, swept continuous wave interference, and band-limited white Gaussian noise. The algorithm can be used for GNSS interference monitoring in an excessive Radio Frequency Interference environment which causes loss of receiver tracking. This interference detection and characterization algorithm will be used to enhance the interference mitigation algorithm.

• Fire Science and Engineering
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• v.27 no.1
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• pp.20-25
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• 2013

This study is experimentally analyzed to extract the major parameters affecting the performance of the smoke-control system and the relations of pressure difference between vestibule and supply air pressure zone effect of supply mass flow rate and leakage area in the smoke-control zone. To obtain this, the mock-up building of three-story scale with a total of 10 compartments was constructed, and several apparatus were also installed for in-situ measurement of the ventilation flow rate, pressure difference between compartments, smoke defensive air velocity, the opening-closing force of door, etc. This article show that pressure difference in the smoke-control zone is significantly related with leakage area of vestibule in low pressure region, leakage area of supply air pressure in over pressure region and both of them in pressure control region when the pressure control range of damper is 45 Pa~55 Pa.

• The Korean Journal of Applied Statistics
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• v.33 no.4
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• pp.451-466
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• 2020

CCC-r chart is effective for high-quality processes with a very low fraction nonconforming. The values of process parameters should be estimated from the Phase I sample since they are often not known. However, if the Phase I sample size is not sufficiently large, an estimation error may occur when the parameter is estimated and the practitioner may not achieve the desired in-control performance. Therefore, we adjust the control limits of CCC-r charts using the bootstrap algorithm to improve the in-control performance of charts with smaller sample sizes. The simulation results show that the adjustment with the bootstrap algorithm improves the in-control performance of CCC-r charts by controlling the probability that the in-control average number of observations to signal (ANOS) has a value greater than the desired one.