• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.3
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• pp.140-148
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• 2014

A storm surge barrier is a specific type of floodgate, designed to prevent a storm surge or spring tide from flooding the protected area behind the barrier. A surge barrier is almost always part of a larger flood protection system consisting of floodwalls, dikes, and other constructions. Surge barriers allow water to pass under normal circumstances but, when a (storm) surge is expected, the barrier can be closed. Among the various means of closing, buoyant flap typed storm surge barrier which was indicated by MOSE project in Italy is chosen for Masan bay protection, and the motion of the surge barrier under the action of storm surge and wave is examined using FLOW-3D, a computational fluid dynamics software analyzing various physical flow processes. Numerical result shows that storm surge barrier is successfully operated under wave height 3 m, and tidal range 2 m.

• Asian Journal of Atmospheric Environment
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• v.10 no.3
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• pp.125-136
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• 2016

In this study, the effects of the mesh barrier on the free dispersion of ammonia were numerically investigated under different atmospheric conditions. This study presents the detail and flow feature of the dispersion of ammonia through the mesh barrier on various free stream conditions to decline and limit the toxic danger of the ammonia. It is assumed that the dispersion of the ammonia occurred through the leakage in the pipeline. Parametric studies were conducted on the performance of the mesh barrier by using the Reynolds-averaged Navier-Stokes equations with realizable k-${\varepsilon}$ turbulence model. Numerical simulations of ammonia dispersion in the presence of mesh barrier revealed significant results in a fully turbulent free stream condition. The results clearly show that the flow behavior was found to be a direct result of mesh size and ammonia dispersion is highly influenced by these changes in flow patterns in downstream. In fact, the flow regime becomes laminar as flow passes through mesh barrier. According to the results, the mesh barrier decreased the maximum concentration of the ammonia gas and limited the risk zone (more than 500 ppm) lower than 2 m height. Furthermore, a significant reduction occurs in the slope of the upper boundary of $NH_3$ risk zone distribution at downstream when a mesh barrier is presented. Thus, this device highly restricts the leak distribution of ammonia in the industrial plan.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1125-1128
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• 2007

In order to improve the acoustic performance of a noise barrier without increasing its height, various type of acoustic devices are suggested but, there is no proper method to estimate the performance in Korea. For this, an outdoor test facility was established in Expressway and Transportation Technology Institute(ETTI) of Korea Expressway Corporation for testing the acoustical performance of noise reducing devices installed on the top of a noise barrier. Noise measurements before and after installation of the noise reducing devices were carried out by using sound pressure level for long distance range from the barrier, from 10m to 40m. For considering the directivity effects of noise reducing devices, multivariate regression analysis was attempted.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.3
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• pp.579-584
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• 2012

In this paper, drain induced barrier lowering(DIBL) has been analyzed as one of short channel effects occurred in double gate(DG) MOSFET. The DIBL is very important short channel effects as phenomenon that barrier height becomes lower since drain voltage influences on potential barrier of source in short channel. The analytical potential distribution of Poisson equation, validated in previous papers, has been used to analyze DIBL. Since Gaussian function been used as carrier distribution for solving Poisson's equation to obtain analytical solution of potential distribution, we expect our results using this model agree with experimental results. The change of DIBL has been investigated for device parameters such as channel thickness, oxide thickness and channel doping concentration.

• Journal of Magnetics
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• v.10 no.4
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• pp.137-141
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• 2005

We confirmed that the improvement in properties of magnetic tunnel junctions prepared by radical oxidation after thermal treatment was mostly resulted from the redistribution of oxygen at the $AIOx/Co_{90}Fe_{10}$ interface. The as-deposited Al oxide barrier was oxygen-deficient but most of it re-oxidized into $Al_2O_3$, the thermodynamically stable stoichiometric phase, through thermal treatment. As a result, the effective barrier height was increased from 1.52 eV to 2.27 eV. On the other hand, the effective barrier width was decreased from 8.2 ${\AA}$ to 7.5 ${\AA}$. X-ray absorption spectra of Fe and Co clearly showed that the oxygen in the CoFe layer diffused back into the Al barrier and thereby enriched the barrier to close to a stoichiometirc $Al_2O_3$ phase. The oxygen bonded with Co and Fe diffused back by 6.8 ${\AA}$ and 4.5 ${\AA}$ after thermal treatment, respectively. Our results confirm that controlling the chemical structures of the interface is important to improve the properties of magnetic tunnel junctions.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.888-891
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• 2011

In this paper, drain induced barrier lowering(DIBL) has been analyzed as one of short channel effects occurred in double gate(DG) MOSFET. The DIBL is very important short channel effects as phenomenon that barrier height becomes lower since drain voltage influences on potential barrier of source in short channel. The analytical potential distribution of Poisson equation, validated in previous papers, has been used to analyze DIBL. Since Gaussian function been used as carrier distribution for solving Poisson's equation to obtain analytical solution of potential distribution, we expect our results using this model agree with experimental results. The change of DIBL has been investigated for device parameters such as channel thickness, oxide thickness and channel doping intensity.

• Journal of the Korean Vacuum Society
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• v.16 no.3
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• pp.197-204
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• 2007

Ultra thin Er-silicide layers formed by Er deposition on the clean p-silicon and in situ post annealing technique were investigated with respect to change of the Schottky barrier height. The formation of Er silicides was confirmed by XPS results. UPS measurements revealed that the workfunction of the silicide decreased and was saturated as the deposited Er thickness increased up to $10{\AA}$. We found that the silicides were mainly composed of Er5Si3 phase through the XRD experiments. After Schottky diodes were fabricated with the Er silicide/p-Si junctions, the Schottky barrier heights were calculated $0.44{\sim}0.78eV$ from the I-V measurements of the Schottky diodes. There was large discrepancy in the Schottky barrier heights deduced from the UPS with the ideal junction condition and the real I-V measurements, so that we attributed the discrepancy to the $Er_5Si_3$ phase in the Er-silicides and the large interfacial density of trap state of it.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.5
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• pp.627-634
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• 2018

In the study, computational fluid dynamics analysis was performed to estimate wind force coefficients for a box-type concrete girder bridge under the influence of wind. The drag, lift and pitching moment coefficients were obtained for the bridge section without noise barrier and compared with those of the bridge section with noise barriers of various heights. The shear stress transport $k-{\omega}$ turbulence model was employed to estimate the wind force coefficients, and the contribution of the friction drag force to the total drag force was investigated. It was found from the study that the drag force coefficients increased as the height of noise barrier increased when a wind blew horizontally, and that the contribution of the friction drag force was highest for the bridge section without noise barrier. It is concluded that the impact of the height of noise barriers should be considered in the design of bridges, and the friction force played an important role in evaluating wind forces on bridges.

• Journal of Trauma and Injury
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• v.18 no.2
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• pp.101-106
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• 2005

Purpose: The number of the deceased from free-fall is increasing nowadays. Free-fall comes to a great social problem in that even the survivor will be suffering for cord injury or brain injury, and so on. We analyzed the cases of free-fall patients to find out whether the injury severity is mainly correlated with the height of fall. Methods: We retrospectively investigated the characteristics of patients, who fall from the height above 2m from January 2000 to August 2004. We excluded the patients who transferred to other hospital, transferred from other hospital, and not known the height of fall. 145 patients were evaluated. Variables included in data analysis were age, height of fall, injury severity score (ISS), the being of barrier, and the survival or not. To find out the correlation between height of fall and death, we used receive operating characteristics (ROC) curve analysis. Results: The mean age of patients was $36.5{\pm}19.4$ years old. 110 were male and 35 were female. Mean height of fall was $11.1{\pm}8.5m$. 51 patients (35.2%) were died and 30 patients of them (58.9%) got emergency room on dead body. The mean height of fall is $8.9{\pm}5.8m$ for 94 survivors and $15.2{\pm}11.0m$ for the 51 deceased (p<0.001). The area under the ROC curve was 0.646, which means the height of fall was not adequate factor for predicting for death. At 13.5m, as cut?off value, sensitivity is 52.9%, specificity is 86.2%, positive predictive value is 67.5% and negative predictive value is 77.1%. There were statistical differences in mortality rate and ISS between 'below 13.5m group' and 'above 13.5m group', but there was not statistical difference in head and neck AIS. Conclusion: The height of fall is not adequate factor for prediction of death. So other factors like intoxication or not, the being of barrier or protection device need to be evaluated for predicting of free-fall patient's death.

• Journal of the Semiconductor & Display Technology
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• v.14 no.1
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• pp.27-30
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• 2015

SiC based Schottky barrier diodes were prepared by using the facing targets sputtering method. In this research, 4H-SiC polytypes of SiC were adopted and Molybdenum, Titanium was employed as the Schottky metal of the metal-semiconductor contacts. Both structures showed the rectifying nature in their forward and reverse J-V characteristic curve and the ideality factors calculated from these plots that were close to unity were represented the nearly ideal behavior. Difference of Schottky barrier height between prepared devices was also corresponding with the electrical characteristics of themselves. Therefore the suitability of the facing targets sputtering method for fabrication of Schottky diodes could be suggested from these results.