• Structural Engineering and Mechanics
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• v.34 no.6
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• pp.755-778
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• 2010

Near-fault ground motion with directivity or fling effects is significantly influenced by the rupture mechanism and substantially different from ordinary records. This class of ground motion has large amplitude and long period, exhibits unusual response spectra shapes, possesses high PGV/PGA and PGD/PGA ratios and is best characterized in the velocity and the displacement time-histories. Such ground motion is also characterized by its energy being contained in a single or very few pulses, thus capable of causing severe damage to the structures. This paper investigates the characteristics of near-fault pulse-like ground motions and their implications on the structural responses using new proposed measures, such as, the effective frequency range, the energy rate (in time and frequency domains) and the damage indices. The paper develops also simple mathematical expressions for modeling this class of ground motion and the associated structural responses, thus eliminating numerical integration of the equations of motion. An optimization technique is also developed by using energy concepts and damage indices for modeling this class of ground motion for inelastic structures at sites having limited earthquake data.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.1
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• pp.25-32
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• 2007

In this paper, a new method for first order plus dead time(FOPDT) model identification is proposed, which can identity multiple points on a process step response in terms of classification of time response. The process input and output to the test are decomposed into the transient part and the steady-state part. The steady-state part express one FOPDT model and the transient part express variously FOPDT model using least square estimation method. The optimum parameter tuning algorithm for PID controller of the Smith Predictor is proposed through ITAE as performance index. The Simulation results show the validity and improvement of performance for various processes.

• Journal of Industrial Technology
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• v.19
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• pp.313-320
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• 1999

Steel railway bridge gets vibration from moving load ; additionally, this kind of moving load is going to be a sufficient reason, which causes fatigue damage to steel railway bridge. Fatigue damage and stress curve were raised by moving load depends on span length in steel railway bridge. In other words, stress curve appears index regarding every axial load in short span, but self weight lets stress curve's change decrease in proportion to increasing span length. Thereby, we have studied that how the steel railway bridge appear fatigue damage in proportion to span length of steel railway bridge. Dynamic strain was measured in 4 steel plate-girder railway bridge during the trains was passing, which is located on the line of Kyoung-chun railway. And time history response analysis has been done in order to ensure actual survey. The results of this study show the decreased of the fatigue damage in steel railway bridge according to length of span. This paper ends is bases research of fatigue design in steel railway bridges according to span length.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.6
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• pp.453-462
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• 2016

This paper proposes a torque control method for surface mounted permanent magnetic synchronous motor (PMSM) driven by a 2-level voltage source driven inverter, which has fast torque response and small torque ripple. The proposed torque control method follows the finite control set model predictive control (FCS-MPC) strategy. A reference state is derived at each time step for the given time varying torque reference and the cost index is defined so that the tracking error for this reference state should be penalized. The choice of an optimal output voltage vector is made first from the 6 possible active voltage vectors of the 2-level voltage source inverter. Then a modulation factor for the chosen optimal voltage vector is obtained so that the torque ripple can be reduced further. It is shown that the proposed FCS-MPC control method yields fast torque tracking response and small torque ripple through simulation and experiments.

• Earthquakes and Structures
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• v.9 no.5
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• pp.1091-1114
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• 2015

The adequacy of a number of advanced earthquake Intensity Measures (IMs) to predict the structural damage of earthquake resistant 3D R/C buildings is investigated in the present paper. To achieve this purpose three symmetric in plan and three asymmetric 5-storey R/C buildings are analyzed by nonlinear time history analysis using 74 bidirectional earthquake records. The two horizontal accelerograms of each ground motion are applied along the structural axes of the buildings and the structural damage is expressed in terms of the maximum and average interstorey drift as well as the overall structural damage index. For each individual pair of accelerograms the values of the aforementioned seismic damage measures are determined. Then, they are correlated with several strong motion scalar IMs that take into account both earthquake and structural characteristics. The research identified certain IMs which exhibit strong correlation with the seismic damage measures of the studied buildings. However, the degree of correlation between IMs and the seismic damage depends on the damage measure adopted. Furthermore, it is confirmed that the widely used spectral acceleration at the fundamental period of the structure is a relatively good IM for medium rise R/C buildings that possess small structural eccentricity.

• Fire Science and Engineering
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• v.34 no.4
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• pp.45-51
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• 2020

The aim of this study is to investigate the gas temperature and velocity during sprinkler activation considering the fire growth scenario based on the thermal response model of the sprinkler. The fire source is assumed to have time square fire growth scenarios with a maximum heat release rate of 3 MW. Eight types of standard and fast-response sprinkler heads with an operating temperature range of 65-105 ℃ and a response time index range of 25-171 m^1/2s^1/2 were adopted. The temperature difference between the gas stream and the sensing element of the sprinkler head decreased as the fire growth slowed down, and the RTI value decreased. The overall gas temperature and velocity conditions predicted using the FDS model at sprinkler activation were in reasonable agreement with those of standard test conditions of the sprinkler head response. However, the sprinkler head could be activated at lower limits of gas temperature and velocity under the current test conditions for a slowly growing fire scenario.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.1
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• pp.33-40
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• 2014

Reliability analysis of jacket type offshore wind turbine (OWT) support structure under extreme ocean environmental loads was performed. Limit state function (LSF) of OWF support structure is defined by using structural dynamic response at mud-line. Then, the dynamic response is expressed as the static response multiplied by dynamic response factor (DRF). Probabilistic distribution of DRF is found from response time history under design significant wave load. Band limited beta distribution is used for internal friction angle of ground soil. Wind load is obtained in the form of thrust force from commercial code called GH_Bladed and then, applied to tower hub as random load. In a numerical example, the response surface method (RSM) is used to express LSF of jacket type support structure for 5MW OWF. Reliability index is found using first order reliability method (FORM).

• Environmental Mutagens and Carcinogens
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• v.22 no.3
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• pp.187-198
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• 2002

Chlorpyrifos is an organophosphate insecticide and one of the most commonly and widely used insecticide. However, a little known about the dermal risk of chlorpyrifos on human being. Therefore, this study was conducted for the dermal risk assessment after exposure to chlorpyrifos in Korean farmers. First, skin irritation by chlorpyrifos (10 mg/$\textrm{cm}^2$, 50 mg/$\textrm{cm}^2$, 100 mg/$\textrm{cm}^2$, 250 mg/$\textrm{cm}^2$ in acetone) was determined in rabbits for 5 days considering the usage of chlorpyrifos short term highly exposure. The index of skin irritation by chlorpyrifos was increased in each dose and length of exposure dependent manners. Next, using benchmark dose (BMD$_{5}$) approach, the dose-response relationship was assessed to calculate the reference dose (RfD). The value of RfD was 2.84 $\mu\textrm{g}$/kg/day from 142.16 $\mu\textrm{g}$/kg/day BMD5 value divided uncertainty factor 50. Finally, we assessed human dermal risk of chlorpyrifos with exposure level and RfD. Skin absorbed levels were assumed with several exposure scenarios encounting the circumstances of exposure that application method, protection equipment and cloth, exposure time and exposure frequency during chlorpyrifos spraying. By the comparison of skin absorbed dose with the reference dose, it was identified that risk values (risk index) to skin chlorpyrifos exposure were 0.958 from the point of above results and it was recommended that the occurrence of hazard effect (skin irritation toxicity) of chlorpyrifos would not be expected. Risk index was smaller than 1 in the case of spraying vehicle mounted application, 1hour exposure time and wearing protective cloth exposure. Whereas, risk index was above 1 in the case of hand-held application, 2hour exposure time and wearing common cloth. Comparing two kinds of application method, total risk index of the hand held application (1.67) was higher than vehicle mounted (0.27). Therefore, chlorpyrifos skin exposure was mainly affected by application equipment and applied form. The results of risk assessment on the human dermal toxicity of chlorpyrifos should be required to control in keeping safety rules, skin surface area available for contact, spraying time ,and spraying frequency.y.

• Journal of Nutrition and Health
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• v.21 no.2
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• pp.113-121
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• 1988

The purpose of this study was to investigate the effects of dietary zinc on immune response in mice. Weanling male mice was placed individually in stainless steel cages and fed a zinc dificient diet and control diet. All mice were given deionized water ad libitum. The introduction of extraneous zinc was minimized in all cage by washing feed jars and water bottles sequentially with 4mM EDTA and conc-nitiric acid followed by deionized water. After 4 and 5 weeks of the diets, mice were immunized with lx 106 Naegleria fowleri intraperitoneally. Mice were weighed once a week. The results from this study are summarized as followed ; 1) Mice fed the zinc dificient diet showed growth retardation. After 3 weeks of diets, mean body weight of zinc deficient mice was 21.4g and that of control was 25.0g. This difference is singnificant statistically (p<0.01). The more time passed, the more remarkable difference was found. 2) The weigth of organs were measured on liver, kidney, spleen, thymus, heart, lung, brain. Difference in weight were observed only in liver and spleen. 3) Proliferative response of spleen cells of zinc deficient mice to con A was lower than that of control mice after one week on immunization(p<0.005). 4) Stimulation index was lower in zinc deficient mice to phytohemagglutinin after two weeks on immunization (p<0.05). 5) Blastogenesis of speen cells of zinc deficient mice to Naegleria fowleric lysate was lower after 10 days on immunization (p<0.05). 6) Immunoglobulin G antribody titers of zinc deficient mice sera by ELISA was lowered to control mice after 5 weeks on immunization (p<0.005).

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.1
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• pp.32-38
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• 2007

In order to establish the environmental condition of sounds in the classroom, we measured the impulse response in cases of using and not-using PA(Public-Address). By calculating the physical index of acoustics, I examined the differences between the two cases. The degree of improvement in listening with the help of PA has also been studied by testing the voice articulation with the use of the measured impulse response. As a result, I found that the clearness is enhanced by increasing the sound pressure level in the case of short reverberation. However, it was not the case when the reverberation time was long.