• Journal of the Earthquake Engineering Society of Korea
• /
• v.11 no.4
• /
• pp.53-63
• /
• 2007

Seismic design codes are developed mainly based on the observation of the behavior of structures in the high seismicity regions where structures may experience significant amount of inelastic deformations and major earthquakes may result in structural damages in a vast area. Therefore, seismic loads are reduced in current design codes for building structures using response modification factors which depend on the ductility capacity and overstrength of a structural system. However, structures in low seismicity regions, subjected to a minor earthquake, will behave almost elastically because of the larger overstrength of structures in low seismicity regions such as Korea. Structures in low seismicity regions may have longer periods since they are designed to smaller seismic loads and main target of design will be minor or moderate earthquakes occurring nearby. Ground accelerations recorded at stations near the epicenter may have somewhat different response spectra from those of distant station records. Therefore, it is necessary to verify if the seismic design methods based on high seismicity would he applicable to low seismicity regions. In this study, the adequacy of design spectra, period estimation and response modification factors are discussed for the seismic design in low seismicity regions. The response modification factors are verified based on the ductility and overstrength of building structures estimated from the farce-displacement relationship. For the same response modification factor, the ductility demand in low seismicity regions may be smaller than that of high seismicity regions because the overstrength of structures may be larger in low seismicity regions. The ductility demands in example structures designed to UBC97 for high, moderate and low seismicity regions were compared. Demands of plastic rotation in connections were much lower in low seismicity regions compared to those of high seismicity regions when the structures are designed with the same response modification factor. Therefore, in low seismicity regions, it would be not required to use connection details with large ductility capacity even for structures designed with a large response modification factor.

• Korea journal of population studies
• /
• v.35 no.1
• /
• pp.31-52
• /
• 2012

The purpose of this study is to analyze the effectiveness of policies in response to low fertility in Korea. Using a recent nationwide survey on marriage and fertility, this study analyzes the effect of low fertility policies on plan of further birth among young married women according to the number of their children. Awareness of polices in response to low fertility is relatively high, showing the great differences among policy measures. In contrast, the degree of polices in response to low fertility is very low. ranging from 2.0% to 27.6%. The distribution of awareness and experience is different according to the number of children. The results of logistic regression analysis show that awareness of polices in response to low fertility such as economic support, promotion of equality of the sexes significantly affects on plan of further birth. However, this effects disappear when we apply parity specific approach. For example, the plan for first child is quite universal as no difference is found by their awareness of policies in response to low fertility. Similar results are found in married women having plan for second child and third child. With respect to the degree of experience of policies in response to low fertility, the results show that economic support, work-family coexistence, and promotion of equality of the sexes significantly affects the plan of further birth. Like awareness of policies in response to low fertility, these effects disappear as we apply parity specific approach. The results indicate that the effect of policies in response to low fertility differs by the current number of children. Thus, consideration of such difference would help us deepen our understanding of fertility behaviors and polices in response to low fertility.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2002.09a
• /
• pp.35-42
• /
• 2002

Frequency responses for most of the local seismic sensors in Korea have been roughly checked by mutual comparison of Fourier spectra of seismic records from accelerometer and seismometer, both of which are installed at the same location. Especially, because the frequency content of the seismic energy is usually above 1 Hz for local earthquakes, the reliability of low frequency response could have not been evaluated. Fortunately a recent large earthquake, Ms=7.2 on 02/06/29 containing dominant low frequency energy makes it possible to check the low frequency response of the seismic sensors, especially EpiSensor and JC-V100. Considering two types of sensor pairs, (STS-2 and EpiSensor, JC-V100 and EpiSensor), the low frequency response of EpiSensor is confirmed first by comparison with STS-2 which has proved low frequency response. Second, reliable low frequency limit of instrumentally corrected seismic data from JC-V100 data is estimated to be about 0.03 Hz by comparison with EpiSensor data.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.22 no.2
• /
• pp.77-86
• /
• 2018

This study develops an empirical prediction equation of spectral acceleration responses of earthquakes which can induce structural damages. Ground motion records representing hazards of low-to-moderate seismic regions were selected and organized with several influential factors affecting the response spectra. The empirical equation and estimator coefficients for acceleration response spectra were then proposed using a robust nonlinear optimization coupled with a regression analysis. For analytical verification of the prediction equation, response spectra used for low-to-moderate seismic regions were estimated and the predicted results were comparatively evaluated with measured response spectra. As a result, the predicted shapes of response spectra can simulate the graphical shapes of measured data with high accuracy and most of predicted results are distributed inside range of correlation of variation (COV) of 30% from perfectly correlated lines.

• Journal of Advanced Marine Engineering and Technology
• /
• v.24 no.6
• /
• pp.110-119
• /
• 2000

In this paper, an experimental study is carried out under the operating conditions of low speed and rapid acceleration in order to investigate and improve the response characteristics of a turbocharged diesel engine with radial turbine driven by exhaust gas. A rapid acceleration for investigating the response performance is applied to the fuel-pump rack of the engine from 0-10% to 0-40% in steps of 10%, and accelerating time of 1, 2 and 3 seconds is applied to the engine. Further experiment for improving the low speed torque and acceleration performance is also performed by means of injecting air into the inlet manifold at compressor exit during the period of low speed and application of a rapid acceleration. The effects of air injection on the response performance are represented at subjected engine speed with the changes of response performance factors such as air injection pressure, air injection period, accelerating rate, accelerating time and load. From the experimental results obtained throughout this study, it is shown that air injection into the inlet manifold at compressor exit is closely related to the improvement of low speed and acceleration performance of a turbocharged diesel engine.

• Journal of Korean Ophthalmic Optics Society
• /
• v.17 no.1
• /
• pp.75-81
• /
• 2012

Purpose: The study tried to figure out accommodative changes by measuring accommodative response, appearing on the full vision correction and low vision correction, with both eyes open-view auto-refractometer (Nvision-K5001, Shin-nippon, Japan). Methods: It carried out objective and subjective refractions, targeting 79 college students (58 males and 21 females) aged between 20 and 30($21.14{\pm}2.00$), by measuring accommodative changes with fixation distance at 1.0 m for eyesight of 1.0 after full version correction. The distances of 5.0 m, 1.0 m, 0.50 m, 0.33 m and 0.25 m for eyesight of 0.8, 0.7 and 0.6 after low vision correction arbitrarily added plus lens were applied. Results: the shorter measure fixation distances were, the greater changes accommodative response showed a tendency in the state of both full vision correction and low vision correction(0.7). The state of full vision correction showed a greater change of accommodative response than that of low vision correction(0.7). Both right and left eyes showed low accommodative responses in the state of low vision correction(0.7) than that of full vision correction. As a result of analyzing accommodative response at an eyesight of 0.8, 0.7, and 0.6 after low vision correction, the poorer eyesight was the lower accommodative response. Conclusions: Low vision correction from a near distance is expected to avoid unnecessary accommodative response, make eyes relaxed and prevent accommodative function disorder.

• Structural Engineering and Mechanics
• /
• v.20 no.4
• /
• pp.451-463
• /
• 2005

Structural members commonly employed in marine and off-shore structures are usually fabricated from plates and shells. Collision of this class of structures is usually modeled as plate and shell structures subjected to dynamic impact loading. The understanding of the dynamic response and energy transmission of the structures subjected to low velocity impact is useful for the efficient design of this type of structures. The transmissions of transient energy flow and dynamic transient response of these structures under low velocity impact are presented in the paper. The structural intensity approach is adopted to study the elastic transient dynamic characteristics of the plate structures under low velocity impact. The nine-node degenerated shell elements are adopted to model both the target and impactor in the dynamic impact response analysis. The structural intensity streamline representation is introduced to interpret energy flow paths for transient dynamic response of the structures. Numerical results, including contact force and transient energy flow vectors as well as structural intensity stream lines, demonstrate the efficiency of the present approach and attenuating impact effects on this type of structures.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2008.10a
• /
• pp.228-230
• /
• 2008

The response time characteristic of low voltage liquid crystals (LCs) is investigated and a new simulator for low voltage LCs is proposed. In order to enable low voltage operation, it is important to minimize Vth of LCs and variation of pixel voltage caused by dynamic capacitance operation of LC Display. Because dynamic capacitance variation is much larger for low voltage LC operation compared to that of conventional LC material, it is necessary to make a better model for dynamic capacitance operation. A proposed minimizing Vth of LCs and variation of pixel voltage study results through a new constant charge model improve response characteristics for low voltage LCs operation.

• Journal of IKEEE
• /
• v.23 no.2
• /
• pp.552-556
• /
• 2019

This paper present a capless low drop out regulator (LDO) that improves the load transient response characteristics by using a current regulator. A voltage regulator circuit is placed between the error amplifier and the pass transistor inside the LDO regulator to improve the current characteristics of the voltage line, The proposed fast transient LDO structure was designed by a 0.18 um process with cadence's virtuoso simulation. according to test results, the proposed circuit has a improved transient characteristics compare with conventional LDO. the simulation results show that the transient of rising increases from 1.954 us to 1.378 us and the transient of falling decreases from 19.48 us to 13.33 us compared with conventional capless LDO. this Result has improved response rate of about 29%, 28%.

• Clinical and Experimental Reproductive Medicine
• /
• v.14 no.2
• /
• pp.101-108
• /
• 1987

In order to evaluate the consistency of the serum estradiol pattern and response and to determine the influence of number of ovary on them in repeat cycles in the same patient, 57 cycles in 24 patients who underwent in Vitro Fertilization-Embryo Transfer or Gamete Intrafallopian Transfer in Seoul National University Hospital. The patients were stimulated by follicular stimulating hormone and human menopausal gonadotropin and classified as high(${\geqq}$400 pg/ml) and low(<400 pg/ml) response group according to preovulatory estradiol concentration and classified as three estradiol patterns (A,G.B) according to Jones criteria. Seventeen(89.5%) of 19 patients in when a high response to ovulation induction in their first cycle showed a high response. 40%(2/5) of the second ovulation induction cycle were low response in the patient whose first cycle resulted resulted in a low response. Serum estradiol pattern in the first ovulation induction cycle tended to be repeated in the second cycle. Women with high response tended to be more likely to have A and G patterns and less likely to have a cancellation than those with low response. One-ovary patients were at higher risk for inadequate ovulation induction response.