• 한국해양공학회지
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• 제34권6호
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• pp.394-405
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• 2020

To assess the station-keeping performance of floating structures in the Arctic region, the ice load should be considered along with other environmental loads induced by waves, wind, and currents. However, present methods for performance evaluation in the time domain are not effective in terms of time and cost. An ice load generation module is proposed based on the experimental data measured at the KRISO ice model basin. The developed module was applied to a time domain simulation. Using the results of a captive model test conducted in multiple directions, the statistical characteristics of ice loads were analyzed and processed so that an ice load corresponding to an arbitrary angle of the structure could be generated. The developed module is connected to commercial dynamic analysis software (OrcaFlex) as an external force input. Station-keeping simulation in the time domain was conducted for the same floating structure used in the model test. The mooring system was modeled and included to reflect the designed operation scenario. Simulation results show the effectiveness of the proposed ice generation module and its application to station-keeping performance evaluation. Considering the generated ice load, the designed structure can maintain a heading angle relative to ice up to 4°. Station-keeping performance is enhanced as the heading angle conforms to the drift direction. It is expected that the developed module will be used as a platform to verify station-keeping algorithms for Arctic floating structures with a dynamic positioning system.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.1719-1724
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• 2010

In the areas susceptible to vibration and noise induced by railway traffic such as downtown area and stations under railway lines, the vibration and the structure-borne noise can be solved by floating slab track system separating the entire track structure from its sub-structure using anti-vibration mat or springs. In other countries, the core technologies for vibration-proof design and vibration isolator - one of key components - have been developed and many installation experiences have been accumulated. However, in Korea, since the design technology of system and components are not yet developed, the foreign systems are being introduced without any adjustment. Thus, in this study, the vibration isolator has been developed and its performance are investigated by the dynamic analysis of a station structure under railways lines and the floating slab track system. For this purpose, the loads transferred from the vibration isolator of the floating slab track were evaluated by train running simulation considering vehicle-track interaction, and then the dynamic analysis of station structure subjected to these loads was performed. The dynamic analysis results show that the proposed floating slab track can reduce the vibration of structure by about 25dB compared with that in conventional ballast track without floating system.

• 한국작물학회:학술대회논문집
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• 한국작물학회 1998년도 춘계 학술대회지
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• pp.61-62
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• 1998

• 농업과학연구
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• 제41권4호
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• pp.455-460
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• 2014

In this study, structural behavior of plastic greenhouse foundation was investigated using rational finite element modeling for structures which have different material properties each other. Because the concrete foundation of plastic greenhouse and soil which surround and support the concrete foundation have very different material property, the boundary between two structures were modeled by a interface element. The interface element was able to represent sliding, separation, uplift and re-bonding of the boundary between concrete foundation and soil. The results of static and dynamic analysis showed that horizontal and vertical displacement of concrete foundation displayed a decreasing tendency with increasing depth of foundation. The second frequency from modal analysis of structure including foundation and soil was estimate to closely related with wind load.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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• pp.89-94
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• 2002

n general, the function of intake structure, whether it be a open channel, a fully wetted tunnel, a sump or a tank, is to supply an evenly distributed flow to a pump station. An even distribution of flow, characterized by strong local flow, can result in formation of surface or submerged vortices, and with certain low values of submergence, may introduce air into pump, causing a reduction of capacity and efficiency, an increase in vibration and additional noise. Uneven flow distribution can also increase or decrease the power consumption with a change in total developed head. To avoid these sump problems pump station designers are considered intake structure dimensions, such as approaching upstream, baffle size, sump width, width of pump cell and so on. From this background, flow characteristics of intake within sump are investigated numerically to obtain the optimal sump design data. The sump model is designed in accordance with HI code.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.597-600
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• 2002

In general, the function of intake structure, whether it be a open channel, a fully wetted tunnel, a sump or a tank, is to supply an evenly distributed flow to a pump station. An even distribution of flow, characterized by strong local flow, can result in formation of surface or submerged vortices, and with certain low values of submergence, may introduce air into pump, causing a reduction of capacity and efficiency, an increase in vibration and additional noise. Uneven flow distribution can also increase or decrease the power consumption with a change in total developed head. To avoid these sump problems pump station designers are considered intake structure dimensions, such as approaching upstream, baffle size, sump width, width of pump cell and so on. From this background, flow characteristics of intake within sump are Investigated numerically to obtain the optimal sump design data. The sump model is designed in accordance with HI code.

• ALGAE
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• 제23권3호
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• pp.219-230
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• 2008

The structure of phytoplankton community was studied for one year round at 6 stations in the Beopsu Marsh, Haman-gun, Gyeongsangnam-do, Korea. One hundred seventy-eight taxa (69 taxa belonging to Chlorophyta, 55 taxa to Bacillariophyta, 33 taxa to Cyanophyta, 15 taxa to Euglenophyta, 2 taxa to Rhodophyta, 2 taxa to Dinophyta and 1 taxon to Xanthophyta) were observed. Phytoplankton bloom occurred at the staions 2, 3 and 4 where waters were polluted by sewage and treated water of purification plants from the vicinity. The species diversity index of phytoplankton was the lowest (0.66) in November at the station 3, which the station showed the most eutrophic water due to the diverse pollutants from surroundings of the marsh. For the whole seasons, Fragilaria sp. and Euglena sp. appeared in pollutant water at the station 3, while Cyclotella sp. and Pinnularia sp. inhabited in relatively clean water at the station 5. To reserve the natural treasure, the wetland should be more specially managed by a local governing institution.

• 한국안전학회지
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• 제25권6호
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• pp.123-127
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• 2010

A fire disaster is very serious in the closing space like subway station. In this study, the simulation on fire diffusion is performed to get the temperature history curve, which is used for the fire resisting structural analysis. Most of subway stations are built by the reinforced concrete structure, but recently steel structures are selected for the larger space or beauty. Steel structures relatively have more weaknesses against fire, so it is necessary to develop the method for evaluating fire-resisting capacity in this kind of structures. The developed method is applied to the subway station in Daegu city. It shows that the developed method can be used to simulate the fire disaster and to get the temperature history curve and evaluate the safety of steel structures against the fire.

• 생태와환경
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• 제41권2호
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• pp.137-143
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• 2008

The abundance and community structure of epilithic diatoms grown on different substrata were investigated in two first-order streams located in a limestone and granite area, north of the Suzuka Mountains in Central Japan. Experiments were conducted as follows: limestone and granite without algae were submerged in their own streambed or another stream station and incubated for seven weeks, while limestone and granite with algae were transferred to another stream station and incubated at the same time. The diatom biomass was consistently high in the lime-stone station experiments compared to those at the granite station. In addition, there was more diatom biomass on granite substrata than on the limestone substrata at both stations. The present results suggested that the difference in water chemistry including the major nutrient concentrations was the limiting factor for algal growth in these two streams; however, when the water chemistry was the same in each stream, the difference in substratum characteristics became the important factor affecting the diatom abundance. The diatom community grown on the transferred substrata with and without algae became similar to those grown on the original substrata in each stream during the incubation period. It was suggested that the effect of the substrata characteristics on the diatom community structure was rather small.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.848-853
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• 2005

The objective of this paper is to address to the providing an adequate noise and vibration solution, required for High Speed Rail while maintaining the stability criteria of the ChonAn station structure, the first constructed in Korean High Speed Railway. The significant acoustic pressure level will be induced by the high speed trains passing-by. Therefore, the high level study of this case is necessary. The acoustic pressure level of 85 dB(A) inside the ChonAn station is expected, and the spaces below concrete slab are not suitable for commercial purpose, thus installation of filtering systems (spring boxes containing viscous dampers, ballast mats and acoustic shield) are provided to reduce the effect of the noise and vibration to acceptable level of 55 dB(A). But, a major drawback of application of the previously conducted experimental results was that the actual effect of installation of filtering system was never been validated. Therefore, the acquisition of noise and vibration on the present structure were obtained and compared to the computer simulations. These predicted the behavior of the station reasonably well. Also, the installation of filtering systems gave the superior reduction on noise and vibration. This application is successfully adapted without scarifying stability criteria related to the structural stability including excessive deformations or displacements. Three traffic operation safety limits: deck vertical acceleration, deflection of the structure, and longitudinal displacement of the slab were satisfactory.