The limited role of aquifer heterogeneity on metal reduction in an Atlantic coastal plain determined by push-pull tests     

Brian J. Mailloux  Stephanie Devlin  Mark E. Fuller  T.C. Onstott  Mary F. DeFlaun  Keun-Hyung Choi  Maria Green-Blum  Donald J.P. Swift  John McCarthy  Hailiang Dong 《Applied Geochemistry》2007

  相似文献   

Evidence of Chromospheric Activity on HR 1099     

Young Woon Kang  Kyu Dong Oh 《Astrophysics and Space Science》1999,268(4):415-424

We present an observational evidence of the chromospheric activity on HR1099. The IUE spectra of HR 1099 were used for the ultraviolet photometry and for the intensity variation of chromospheric emission line. Ultraviolet light curves were made from the low and high dispersion IUE spectra and were compared with a optical light curve. We have analyzed the ultraviolet and optical light curves by the Wilson and Devinney computing code including dark spots. The intensity variation of Mg II emission line depends on the orbital phase. The maximum intensity of Mg II emission line occurs at the phase of light minimum where dark spot visibility is maximum due to strong chromospheric activity. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Probabilistic corrosion rate estimation model for longitudinal strength members of bulk carriers     

Jeom Kee Paik  Sung Kyu Kim  Sang Kon Lee 《Ocean Engineering》1998,25(10):837-860

Many bulk carrier losses have been reported of late, and one of the possible causes of such casualties is thought to be the structural failure of aging hulls in rough weather. Clearly, in such cases, vessels that start out being adequate somehow become marginal later in life. Fatigue and corrosion-related potential problems may be the most important factors affecting such age related vessel damage. With respect to fatigue, extensive studies have been done worldwide both experimentally and theoretically, and the results have been applied to some extent. However, in the case of corrosion effects, additional research is still needed to better understand, clarify and address the various strength uncertainties and their effects on structural behaviour. This paper develops a probabilistic corrosion rate estimation model for the longitudinal strength members of bulk carriers. The model is based on available statistical data for corrosion of existing bulk carriers. The corrosion data collected are documented for future use.  相似文献   

Identification of the Hualien soil-structure interaction system     

C. -B. Yun  J. -S. Choi  J. -M. Kim 《Soil Dynamics and Earthquake Engineering》1999,18(6):689

This article demonstrates how system identification techniques can be successfully applied to a soil-structure interaction system in conjunction with the results of the forced vibration tests on the Hualien large-scale seismic test structure which was recently built in Taiwan for an international joint research. The parameters identified are the shear moduli of several near-field soil regions as well as Young's moduli of the shell sections of the structure. The soil-structure interaction system is represented by the finite element method combined with infinite element formulation for the unbounded layered soil medium. Preliminary investigations are carried out on the results of the static stress analysis for the soil medium and the results of the in-situ tests to divide the soil-structure system into several regions with homogeneous properties and to determine the lower and upper bounds of the parameters for the purpose of identification. Then two sets of parameters are identified for two principal directions based on the forced vibration test data by minimizing the estimation error using the constrained steepest descent method. The simulated responses for the forced vibration tests using the identified parameters show excellent agreement with the test data. The present estimated parameters are also found to be well compared with the average value of those by other researchers in the joint project.  相似文献   

Let-It-Rain: a web application for stochastic point rainfall generation at ungaged basins and its applicability in runoff and flood modeling     

Dongkyun?KimEmail author  Huidae?Cho  Christian?Onof  Minha?Choi 《Stochastic Environmental Research and Risk Assessment (SERRA)》2017,31(4):1023-1043

We present a web application named Let-It-Rain that is able to generate a 1-h temporal resolution synthetic rainfall time series using the modified Bartlett–Lewis rectangular pulse (MBLRP) model, a type of Poisson stochastic rainfall generator. Let-It-Rain, which can be accessed through the web address http://www.LetItRain.info, adopts a web-based framework combining ArcGIS Server from server side for parameter value dissemination and JavaScript from client side to implement the MBLRP model. This enables any desktop and mobile end users with internet access and web browser to obtain the synthetic rainfall time series at any given location at which the parameter regionalization work has been completed (currently the contiguous United States and Republic of Korea) with only a few mouse clicks. Let-It-Rain shows satisfactory performance in its ability to reproduce observed rainfall mean, variance, auto-correlation, and probability of zero rainfall at hourly through daily accumulation levels. It also shows a reasonably good performance in reproducing watershed runoff depth and peak flow. We expect that Let-It-Rain can stimulate the uncertainty analysis of hydrologic variables across the world.  相似文献   

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   

Study on Ship Automatic Berthing System with Mooring Lines     

K. U. Yang  J. G. Hur  M. S. Choi  D. J. Yeo  J. H. Byun 《海洋工程》2017,31(1):19-29

This study describes an automatic berthing system with mooring lines. It is designed to be berthed by using mooring device on the upper deck of a ship. It is to berth once maintaining parallel with the quay by controlling both forward and aft breast lines. Berthing method is used through length adjustment of mooring lines connected between ship and quay by controlling the angular velocity and the torque of hydraulic motor in mooring device. The study is conducted under three changing conditions of draft, such as even-keel, rise of the gravity center and trim to stern. Variables affecting berthing stability are determined based on the control performance of each condition. Bond graphs method is used to model the system. Controller is designed as PID control method of reference-model algorithm. The control program is composed of synchronous control system based on the equations derived with the numerical analysis. The tank test is conducted to verify the usefulness of the control program.  相似文献   

Estimation of spawning area of <Emphasis Type="Italic">Pisodonophis sangjuensis</Emphasis> Ji and Kim, 2011 (Pisces: Ophichthidae) based on leptocephali size and distribution     

Hwan-Sung Ji  Kangseok Hwang  Jung Hwa Choi  Hyung-Kee Cha  Jin-Koo Kim 《Ocean Science Journal》2017,52(2):293-299

Pre-metamorphic leptocephali of Pisodonophis sangjuensis (n = 91, 10.4?90.2 mm in total length, TL) were collected in the East China Sea for the first time. Pre-metamorphic leptocephali of P. sangjuensis, which were identified using mitochondrial DNA cytochrome c oxidase subunit I gene (mtDNA COI), are characterized by various combinations of morphological characters: 8 moderate to pronounced gut loops with the kidney terminating on the 6-7th loops; and 8 subcutaneous pigment patches on the tail just ventral to the notochord. Pisodonophis sangjuensis leptocephali were more numerously collected offshore than inshore around Jeju Island. The smallest leptocephali (< 15.0 mm TL) were collected from the south far from Jeju Island, and the largest leptocephali (> 100.0 mm TL) were collected from around Jeju Island and the southern coast of Korea. Our findings indicate that P. sangjuensis spawns offshore south of Jeju Island that is an area associated with high water temperature, and then the hatched leptocephali are transported to Jeju Island or the southern coast of Korea by the Tsushima Warm Current.  相似文献   

Recent increase in surface fCO<Subscript>2</Subscript> in the western subtropical North Pacific     

Dongseon Kim  Yujeong Choi  Tae-Wook Kim  Geun-Ha Park 《Ocean Science Journal》2017,52(3):329-335

We observed unusually high levels (> 440 μatm) of carbon dioxide fugacity (fCO₂) in surface seawater in the western subtropical North Pacific, the area where Subtropical Mode Water is formed, during summer 2015. The NOAA Kuroshio Extension Observatory moored buoy located in this region also measured high CO₂ values, up to 500 μatm during this period. These high sea surface fCO₂ (fCO_2SW) values are explained by much higher normalized total dissolved inorganic carbon and slightly higher normalized total alkalinity concentrations in this region compared to the equatorial Pacific. Moreover, these values are much higher than the climatological CO₂ values, even considering increasing atmospheric CO₂, indicating a recent large increase in sea surface CO₂ concentrations. A large seasonal change in sea surface temperature contributed to higher surface fCO_2SW in the summer of 2015.  相似文献   

Annual gametogenesis and reproductive effort of the limpet <Emphasis Type="Italic">Cellana grata</Emphasis> (Gould, 1859) (Gastropoda: Nacellidae) in a rocky intertidal beach at Ulleungdo Island off the east coast of Korea     

Hyun-Sung Yang  Do-Hyung Kang  Heung-Sik Park  Kwang-Sik Choi 《Ocean Science Journal》2017,52(4):519-526

Widely distributed from the northern coast of Vietnam to the northern Japan, the limpet Cellana grata (Gould, 1859) occurs commonly on the south and east coasts of Korea. Despite their wide distribution range, few studies have investigated the annual gametogenesis and reproductive effort of C. grata. In an attempt to understand the reproductive physiology of the limpet, we investigated the annual gametogenesis and reproductive effort of C. grata from Ulleungdo Island off the east coast of Korea. Histology revealed that the gonial mitosis commenced in January, as the female exhibited small oogonia (10–40 μm) in the follicle. From March to June, the oocyte size increased dramatically, and fully mature eggs (110–170 μm in diameter) appeared in early summer. First spawning males and females were observed in July, as the surface seawater temperature (SST) reached 22.1°C. The spawning male and females could be observed until the end of December. Gonad somatic index (GSI), a ratio of gonad mass to the total tissue weight, of the male ranged from 0.6 (April) to 17.9 (July), while the female GSI varied from 1.0 (February) to 18.3 (July). GSI of male and female declined rapidly from July to August, suggesting that the major purse of the spawning at the study site was between July and August. Our study suggested that the commercial catch of C. grata during July and August must be suspended at Ulleungdo Island, in order to protect the spawning limpets, which enhances C. grata recruitment and the population.  相似文献