Optimal seismic retrofit model for steel moment resisting frames with brittle connections     

Hyo Seon Park  Se Woon Choi  Byung Kwan Oh 《地震工程与工程振动(英文版)》2018,17(4):835-847

Based on performance-based seismic engineering, this paper proposes an optimal seismic retrofit model for steel moment resisting frames (SMRFs) to generate a retrofit scheme at minimal cost. To satisfy the acceptance criteria for the Basic Safety Objective (BSO) specified in FEMA 356, the minimum number of upgraded connections and their locations in an SMRF with brittle connections are determined by evolutionary computation. The performance of the proposed optimal retrofitting model is evaluated on the basis of the energy dissipation capacities, peak roof drift ratios, and maximum interstory drift ratios of structures before and after retrofitting. In addition, a retrofit efficiency index, which is defined as the ratio of the increment in seismic performance to the required retrofitting cost, is proposed to examine the efficiencies of the retrofit schemes derived from the model. The optimal seismic retrofit model is applied to the SAC benchmark examples for threestory and nine-story SMRFs with brittle connections. Using the retrofit efficiency index proposed in this study, the optimal retrofit schemes obtained from the model are found to be efficient for both examples in terms of energy dissipation capacity, roof drift ratio, and maximum inter-story drift ratio.  相似文献   

Investigating the Effects of Different LED Wavelengths on Aggregation and Swimming Behavior of Chub Mackerel (Scomber japonicus)     

Lee  Donggil  Oh  Wooseok  Gim  Byeong-Mo  Lee  Jung Suk  Yoon  Euna  Lee  Kyounghoon 《Ocean Science Journal》2019,54(4):573-579

Ocean Science Journal - Efficient fish aggregation systems are essential for catching chub mackerel (Scomber japonicus), which is a major target of purse seine fisheries in South Korea. To aid the...  相似文献   

EB-type contact binary do cas with a large temperature difference     

Kyu-Dong Oh  Young-Sook Ahn 《Astrophysics and Space Science》1992,187(2):261-270

NewUBV photoelectric observations of EB-type contact binary DO Cas were made on 4 nights from February 1986 to February 1987. The obtained light curves in combination with the radial-velocity curve of the primary published by Mannino (1958) of DO Cas have been solved simultaneously using the Wilson-Devinney synthesis code. The system is found to be a contact binary with a degree of overcontact of 14%. It may be concluded that DO Cas is an evolved contact binary.  相似文献   

Combined analysis of electrical resistivity and geotechnical SPT blow counts for the safety assessment of fill dam   总被引：1，自引：0，他引：1  

Seokhoon Oh  Chang-Guk Sun 《Environmental Geology》2008,54(1):31-42

Electrical resistivity survey and the geotechnical SPT blow counts (N value) method were simultaneously analyzed to investigate the stability of a center-core type earth-fill dam against the seepage phenomenon. The coupling of these heterogeneous field methods provided a chance to understand the status of underground material by comparing the geophysical and geotechnical view. The analysis shows that the zones with low resistivity value generally have low N value, which means low stiffness. However, some zones with a high resistivity pattern are not accompanied by an increase of its N value, and are even showing a lower N value. These results imply that one should be careful to directly correlate resistivity value with the real status of the core material of a fill dam. And a highly resistive zone may be in poor status due to the effect of increase of resistivity value as a result of the piping condition. Additional laboratory tests show that there is a deficiency of fine soil particles believed as the clay at the troubled region, which means an increase in resistivity value. Therefore, multiple explorations should be planned to reduce the uncertainty in application of geophysical methods to dam safety evaluation in order to compensate the resistivity information of core material.  相似文献   

Combined effect of the East Atlantic/West Russia and Western Pacific teleconnections on the East Asian winter monsoon     

Hyoeun Oh  Jong-Ghap Jhun  Kyung-Ja Ha  Kyong-Hwan Seo 《Asia-Pacific Journal of Atmospheric Sciences》2017,53(2):273-285

This study investigates the individual effects of the East Atlantic/West Russia (EATL/WRUS) and Western Pacific (WP) teleconnection patterns and their combined effect on the East Asian winter monsoon (EAWM). The contributions of the respective EATL/WRUS and WP teleconnection patterns to the EAWM are revealed by removing the dependence on the Arctic Oscillation (AO) and the El Niño-Southern Oscillation (ENSO) using a linear regression, which are named as N_EATL/WRUS and N_WP, respectively. This is because the EATL/WRUS (WP) is closely linked to the Arctic (tropics) region. A significant increase (decrease) in temperature over East Asia (EA) corresponding to a weak (strong) EAWM is associated with the N_EATL/WRUS and N_WP teleconnection patterns during the positive (negative) phases. In order to examine impacts of these two teleconnections on the EAWM, three types of effects are reconstructed on the basis of ± 0.5 standard deviation: 1) Combined effect, 2) N_EATL/WRUS effect, and 3) N_WP effect. The positive N_EATL/WRUS teleconnection induces to a weakened Siberian High and a shallow EA trough at the mid-troposphere through wave propagation, leading to the weak EAWM. During the positive N_WP pattern, warm air from the tropics flows toward the EA along western flank of an anomalous anticyclone over the North Pacific that is relevant to the meridional shift of the Aleutian Low. When the two mid-latitude teleconnections have the in-phase combination, the increase in temperature over EA appears to be more pronounced than the individual effects by transporting warm air from tropics via strong southeasterly wind anomalies induced by anomalous zonal pressure gradient between the Siberian High and Aleutian Low. Therefore, the impact of the mid-latitude teleconnections on the EAWM becomes robust and linearly superimposed, unlike a nonlinear in-phase combined effect of the AO and ENSO.  相似文献   

Study of method for synthetic precipitation data for ungauged sites using quantitative precipitation model     

Hyo-Jun Bae  Jai-Ho Oh 《Asia-Pacific Journal of Atmospheric Sciences》2017,53(3):403-410

A method was developed to estimate a synthetic precipitation record for ungauged sites using irregular coarse observations. The proposed synthetic precipitation data were produced with ultrahigh hourly resolution on a regular 1 × 1 km grid. The proposed method was used to analyze selected real-time observational data collected in South Korea from 2010 to the end of 2014. The observed precipitation data were measured using the Automatic Weather System and Automated Synoptic Observing System. The principal objective of the proposed method was to estimate the additional effects of orography on precipitation introduced by ultrahigh- resolution (1 × 1 km) topography provided by a digital elevation model. The Global Forecast System analysis of the National Centers for Environmental Prediction was used for the upper-atmospheric conditions, necessary for estimating the orographic effects. Precipitation data from 48 of the more than 600 observation sites used in the study, which matched the grid points of the synthetic data, were not included in the synthetic data estimation. Instead, these data were used to evaluate the proposed method by direct comparison with the real observations at these sites. A bias score was investigated by comparison of the synthetic precipitation data with the observations. In this comparison, the number of Hit, False, Miss, and Correct results for 2010-2014 was 74738, 25778, 7544, and 367981, respectively. In the Hit cases, the bias score was 1.22 and the correlation coefficient was 0.74. The means of the differences between the synthetic data and the observations were 0.3, -3.9, -14.4, and -34.9 mm h^-1 and the root mean square errors (RMSEs) were 2.7, 8.3, 19.3, and 39.6 mm h^-1 for the categories of 0.5-10.0, 10.0-30.0, 30.0-50.0, and 50.0-100.0 mm h^-1, respectively. In addition, in each range, the 60% difference between the synthetic precipitation data and the observation data was -1.5 to +1.5, -5.0 to +5.0, -17.0 to +17.0, and -33.0 to +33.0 mm h^-1, respectively. Overall, the correlation coefficient of the synthetic precipitation data was > 0.7 for 43 of the 48 test stations and the RMSE was < 4 mm h^-1 at 31 stations. The results are significant at all evaluation stations at the 0.05 significance level.  相似文献   

Rock Cutting Depth Model Based on Kinetic Energy of Abrasive Waterjet     

Tae-Min Oh  Gye-Chun Cho 《Rock Mechanics and Rock Engineering》2016,49(3):1059-1072

  相似文献   

Use of Lade's Single Surface Work-Hardening Model to Investigate Mechanical Behavior of Decomposed Soils     

Sewook Oh 《Marine Georesources & Geotechnology》2016,34(1):57-64

In this study, it was attempted to assess soil parameters necessary for Lade's single surface work-hardening model that reviewed the physical and mechanical properties of granite soil located in Korea based on the results of triaxial compression tests. In addition, finite element analyses coupled with the determined soil parameters as inputs were conducted based on Lade's single surface work-hardening model and the results were compared with element test results. It could be seen that, in predicting undrained mechanical behavior, the single surface model was reproducing the stress-strain relation obtained through element tests at high accuracy. It is worthwhile to inform that these differences in the initial loading stage and the impossibility to predict swelling behavior are caused by the fact that there is no prediction model for changes in shear properties, especially in dilatancy properties due to particle crushing occurring while element tests are conducted. Hence, it is concluded that, to expand the applicability of Lade's single surface work-hardening constitutive model to practical problems, the model should be modified in relation to the dilatancy of soils.  相似文献   

An analytical model with three sub-regions for m2 tide in the yellow sea and the East China Sea   总被引：1，自引：0，他引：1  

Kyung Tae Jung  Chang Wook Park  Im Sang Oh  Jae Kwi So 《Ocean Science Journal》2005,40(4):191-200

In this study an analytical tide model of uniform width with three sub-regions is presented. The three-subregions model takes into account step-like variations in depths in the direction of the channel as a way to examine the M₂ tide of the East China Sea (ECS) as well as the Yellow Sea (YS). A modified Proudman radiation condition has been applied at the northern open head, while the sea surface elevation is specified at the southern open boundary. It is seen that, due to the presence of an abrupt change in depth, co-amplitude lines of the M₂ tide are splitted to the east and west near the end of the ECS shelf region. Variations in depths, bottom friction and the open head boundary conditions all contribute to the determination of formation of amphidromes as well as overall patterns of M₂ tidal distribution. It is seen that increasing water depth and bottom friction in the ECS shelf results in the westward shift of the southern amphidrome. There is however no hint at all of the well-known degenerated tidal pattern being formed. It is inferred that a lateral variation of water depth has to be somehow incorporated to represent the tidal patterns in ECS in a realistic manner. Regarding the radiation factor introduced by Fang et al. (1991), use of a value larger than one, possibly with a phase shift, appears to be a proper way of incorporating the reflected waves from the northern Yellow Sea (NYS). Key words - analytical model, M₂ tide, Kelvin wave, Yellow Sea, East China Sea  相似文献   

Diffraction of multidirectional random waves by multiple rectangular submarine pits     

Hong Sik Lee  A. Neil Williams  Bo Hyung Lee  Jeill Oh 《Ocean Engineering》2003,30(1):1287-106

A numerical model is presented to predict the interaction of multidirectional random surface waves with one or more rectangular submarine pits. The water depth is assumed uniform and the method involves the superposition of diffraction solutions based on linearized shallow water wave theory obtained by a two-dimensional boundary integral approach. The incident wave conditions are specified using a discrete form of the Mitsuyasu directional spectrum. The present numerical model has been validated through comparisons with previous theoretical results for regular waves. Good agreement was obtained in all cases. Based on these comparisons it is concluded that the present numerical model is an accurate and efficient tool to predict the wave field around multiple submarine pits and navigation channels in many practical situations.  相似文献