• Wind and Structures
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• v.20 no.4
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• pp.549-564
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• 2015

The three-dimensional unsteady incompressible Reynolds-averaged Navier-Stokes equations and k-${\varepsilon}$ double equations turbulent model were used to investigate the effect on the measurements of anemometers due to a passing high-speed train. Sliding mesh technology in Fluent was utilized to treat the moving boundary problem. The high-speed train considered in this paper was with bogies and inter-carriage gaps. Combined with the results of the wind tunnel test in a published paper, the accuracy of the present numerical method was validated to be used for further study. In addition, the difference of slipstream between three-car and eight-car grouping models was analyzed, and a series of numerical simulations were carried out to study the influences of the anemometer heights, the train speeds, the crosswind speeds and the directions of the induced slipstream on the measurements of the anemometers. The results show that the influence factors of the train-induced slipstream are the passing head car and tail car. Using the three-car grouping model to analyze the train-induced flow is reasonable. The maxima of horizontal slipstream velocity tend to reduce as the height of the anemometer increases. With the train speed increasing, the relationship between $V_{train}$ and $V_{induced\;slipstream}$ can be expressed with linear increment. In the absence of natural wind conditions, from the head car arriving to the tail car leaving, the induced wind direction changes about $330^{\circ}$, while under the crosswind condition the wind direction fluctuates around $-90^{\circ}$. With the crosswind speed increasing, the peaks of $V_X,{\mid}V_{XY}-V_{wind}{\mid}$ of the head car and that of $V_X$ of the tail car tend to enlarge. Thus, when anemometers are installed along high-speed railways, it is important to study the effect on the measurements of anemometers due to the train-induced slipstream.

• Wind and Structures
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• v.27 no.1
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• pp.11-27
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• 2018

The straight-cone steel cooling tower is a novel type of structure, which has a distinct aerodynamic distribution on the internal surface of the tower cylinder compared with conventional hyperbolic concrete cooling towers. Especially in the extreme weather conditions of strong wind and heavy rain, heavy rain also has a direct impact on aerodynamic force on the internal surface and changes the turbulence effect of pulsating wind, but existing studies mainly focus on the impact effect brought by wind-driven rain to structure surface. In addition, for the indirect air cooled cooling tower, different additional ventilation rate of shutters produces a considerable interference to air movement inside the tower and also to the action mechanism of loads. To solve the problem, a straight-cone steel cooling towerstanding 189 m high and currently being constructed is taken as the research object in this study. The algorithm for two-way coupling between wind and rain is adopted. Simulation of wind field and raindrops is performed with continuous phase and discrete phase models, respectively, under the general principles of computational fluid dynamics (CFD). Firstly, the rule of influence of 9 combinations of wind sped and rainfall intensity on flow field mechanism, the volume of wind-driven rain, additional action force of raindrops and equivalent internal pressure coefficient of the tower cylinder is analyzed. On this basis, the internal pressures of the cooling tower under the most unfavorable working condition are compared between four ventilation rates of shutters (0%, 15%, 30% and 100%). The results show that the 3D effect of equivalent internal pressure coefficient is the most significant when considering two-way coupling between wind and rain. Additional load imposed by raindrops on the internal surface of the tower accounts for an extremely small proportion of total wind load, the maximum being only 0.245%. This occurs under the combination of 20 m/s wind velocity and 200 mm/h rainfall intensity. Ventilation rate of shutters not only changes the air movement inside the tower, but also affects the accumulated amount and distribution of raindrops on the internal surface.

• Management & Information Systems Review
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• v.34 no.2
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• pp.113-130
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• 2015

This study considers the relation between firms' earnings management and credit rating. Unlike preceding papers only focusing earnings management by accrual(thereafter, AM), this paper examines the effect of accrual earnings management(AMs) and real earning management(thereafter, RM) on credit rating. RMs have more negative effects on firms' forward cash flow generation abilities and long term operating performances than AMs. So, RMs are more negative signals for credit analysts than AMs. But credit analysts have much difficulty in seeing through RM, because if credit analysts want to find out RMs, they have to understand firms' internal operating activities, cost structures, receivables collection practices, and review whether profit distortions are due to abnormal change of them. Sample of this study consists of 2,150firm-year data listed companies from 2002 to 2010. Empirical evidence shows that AMs and RMs are negatively related to credit rating. This result implies that credit analysts see through AMs and RMs in interpreting financial informations, that is to say, they discount credit rating in considering level of earnings management that consist of real activity and accrual earning management. This paper also finds that RMs are more negatively related to credit ratings than AMs. This result suggests that credit analysts don't take RMs into account in credit rating process as much as AMs.

• Journal of the Korea Concrete Institute
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• v.24 no.5
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• pp.567-575
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• 2012

A research was conducted to develop a 2-D nonlinear Galerkin finite element analysis of reinforced concrete structures subjected to high temperature with experiments. Algorithms for calculating the closed-form element stiffness for a triangular element with a fully populated material conductance are developed. The validity of the numerical model used in the program is established by comparing the prediction from the computer program with results from full-scale fire resistance tests. Details of fire resistance experiments carried out on reinforced concrete slabs, together with results, are presented. The results obtained from experimental test indicated in that the proposed numerical model and the implemented codes are accurate and reliable. The changes in thermal parameters are discussed from the point of view of changes of structure and chemical composition due to the high temperature exposure. The proposed numerical model takes into account time-varying thermal loads, convection and radiation affected heat fluctuation, and temperature-dependent material properties. Although, this study considered standard fire scenario for reinforced concrete slabs, other time versus temperature relationship can be easily incorporated.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.7
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• pp.3519-3528
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• 2012

Inhibitory effects of Maclura amboinenesis Bl, one plant used traditionally for the treatment of cancers, on metastatic potential of highly metastatic B16F10 melanoma cells were investigated in vitro. Cell proliferation was assessed using the MTT colorimetric assay. Details of metastatic capabilities including invasion, migration and adhesion of B16F10 melanoma cells were examined by Boyden Chamber invasion and migration, scratch motility and cell attachment assays, respectively. The results demonstrated that n-hexane and chloroform extracts exhibited potent anti-proliferative effects (p<0.01), whereas the methanol and aqueous extracts had less pronounced effects after 24 h exposure. Bioactivity-guided chromatographic fractionation of both active n-hexane and chloroform extracts led to the isolation of two main prenylated xanthones and characterization as macluraxanthone and gerontoxanthone-I, respectively, their structures being identified by comparison with the spectral data. Interestingly, both exhibited potent effective effects. At non-toxic effective doses, n-hexane and chloroform extracts (10 and $30{\mu}g/ml$) as well as macluraxanthone and gerontoxanthone-I (3 and $10{\mu}M$) significantly inhibited B16F10 cell invasion, to a greater extent than $10{\mu}m$ doxorubicin, while reducing migration of cancer cells without cellular cytotoxicity. Moreover, exposure of B16F10 melanoma cells to high concentrations of chloroform ($30{\mu}g/ml$) and geratoxanthone-I ($20{\mu}M$) for 24 h resulted in delayed adhesion and retarded colonization. As insights into mechanisms of action, typical morphological changes of apoptotic cells e.g. membrane blebbing, chromatin condensation, nuclear fragmentation, apoptotic bodies and loss of adhesion as well as cell cycle arrest in the G1 phase with increase of sub-G1 cell proportions, detected by Hoechst 33342 staining and flow cytometry were observed, suggesting DNA damage and subsequent apoptotic cell death. Taken together, our findings indicate for the first time that active n-hexane and chloroform extracts as well as macluraxanthone and gerontoxanthone-I isolated from Maclura amboinensis Bl. roots affect multistep of cancer metastasis processes including proliferation, adhesion, invasion and migration, possibly through induction of apoptosis of highly metastatic B16F10 melanoma cells. Based on these data, M. amboinensis Bl. represents a potential candidate novel chemopreventive and/or chemotherapeutic agent. Additionally, they also support its ethno-medicinal usage for cancer prevention and/or chemotherapy.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.7
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• pp.779-785
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• 2015

Cathodic protection is recognized as the most cost-effective and technically appropriate corrosion prevention method for the submerged zone of offshore structures, ships, and deep-sea facilities. When cathodic protection is applied, the cathodic currents cause dissolved oxygen reduction, generating hydroxyl ions near the polarized surface that increase the interfacial pH and result in enhanced carbonate ion concentration and precipitation of an inorganic layer whose principal component is calcium carbonate. Depending on the potential, magnesium hydroxide can also precipitate. This mixed deposit is generally called "calcareous deposit." This layer functions as a barrier against the corrosive environment, leading to a decrease in current demand. Hence, the importance of calcareous deposits for the effective, efficient operation of marine cathodic protection systems is recognized by engineers and scientists concerned with cathodic protection in submerged marine environments. Calcareous deposit formation on a marine structure depends on the potential, current, pH, temperature, pressure, sea-water chemistry, flow, and time; deposit quality is significantly influenced by these factors. This study determines how calcareous deposits form in sea water, and assesses the interrelationship of formation conditions (such as the sea water temperature and surface condition of steel), deposited structure, and properties and the effectiveness of the cathodic protection.

• Investigative Magnetic Resonance Imaging
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• v.18 no.4
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• pp.290-302
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• 2014

Purpose : Susceptibility-weighted magnetic resonance (MR) sequence is three-dimensional (3D), spoiled gradient-echo pulse sequences that provide a high sensitivity for the detection of blood degradation products, calcifications, and iron deposits. This pictorial review is aimed at illustrating and discussing its main clinical applications. Materials and Methods: SWI is based on high-resolution, 3D, fully velocity-compensated gradient-echo sequences using both magnitude and phase images. To enhance the visibility of the venous structures, the magnitude images are multiplied with a phase mask generated from the filtered phase data, which are displayed at best after post-processing of the 3D dataset with the minimal intensity projection algorithm. A total of 200 patients underwent MR examinations that included SWI on a 3 tesla MR imager were enrolled. Results: SWI is very useful in detecting multiple brain disorders. Among the 200 patients, 80 showed developmental venous anomaly, 22 showed cavernous malformation, 12 showed calcifications in various conditions, 21 showed cerebrovascular accident with susceptibility vessel sign or microbleeds, 52 showed brain tumors, 2 showed diffuse axonal injury, 3 showed arteriovenous malformation, 5 showed dural arteriovenous fistula, 1 showed moyamoya disease, and 2 showed Parkinson's disease. Conclusion: SWI is useful in detecting occult low flow vascular lesions, calcification and microbleed and characterising diverse brain disorders.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2006.11a
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• pp.384-389
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• 2006

The needs for Light Railroad Transit(LRT) have been increased due to the heavy traffic congestions in large cities like Seoul, Korea. Korean government is seeking the LRT system development (including planning, designing, construction, and maintenance and operations) in terms of public-private-partnership (PPP). At the private sector side, it is crucial to estimate the life cycle cost (LCC) to project the cash flow during the O&M period. Since the most construction and O&M cost of LRT project is at the bridge construction, a cost analysis model and a cost breakdown structures (CBS) on LRT bridges are discussed through in depth literature reviews. Construction and maintenance cost of bridges are collected and analyzed. LCC is analyzed by types of bridge superstructures and historical data of repair and rehabilitation (R&R) is investigated. There have been scarce number of LCC analysis on railway bridges. This research delivers a well-defined CBS and maintenance cost data, which will be a great benefit to the systematic maintenance strategy development for railroad bridges.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.99-104
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• 2009

For recycling of waste foundry sands, researchers recently try to recycle them rather than depend on reclamation, and are studying on how to combine waste foundry sands with cement and use them for various kinds of construction material as the effective recycling method of waste foundry sand. In this research, The ways to find the proper replacement rate of waste foundry sands and to make use of them were suggested through the experiments on the range to apply waste foundry sands with two levels of 1:3 mixture rate of W/C 43% and 50%. The research result showed that in terms of liquidity as the characteristic of unhardened mortar, as the replacement rate of waste foundry sands increased, its flow tended to decrease. The amount of air also displayed a similar tendency to that of liquidity in that the higher the replacement rate of waste foundry sands became, the lower it became. With regard to the solidity trait of hardened mortar, it increased when the waste foundry sands were replaced more, and the replacement of waste foundry sands caused increased initial solidity. As for the amount of water permeated and that of water absorbed as the water tight proofing properties, the amount of permeated water was proved to decrease because of the gap recharge effect by the fine powder of waste foundry sands, and the replacement of waste foundry sands in the structures requiring watertightness is concluded to be very effective.

• Composites Research
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• v.12 no.5
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• pp.31-39
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• 1999

Glass-fiber reinforced polymeric composites provide the desitable properties of high stiffness and strength as well as specific weight. Hence, they have become some of the most important materials in several industries. These composites can be grouped into thermoplastic and thermoset composites, with thermoplastic composites having several advantages over thermoset composites in mechanical properties and processing. As a result, the study of the material behavior and forming techniques of such composites has attracted considerable attention in recent years. When the continuous fiber-reinforced polymeric composites are molded by flow molding, the molded parts leads to be nonhomogeneity and anisotropic because of the separation and orientation of fibers. As the characteristics of the products are greatly dependent on the separation, it is very important to clarify the separation in relarion to molding conditions, fiber mat structures and mold geometry. In this study, the effects of the mold geometry and the fiber mat structure on the compression moldability are studied using the cup-type molding.