• Wind and Structures
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• v.7 no.4
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• pp.281-291
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• 2004

The flutter characteristics of long span bridges are discussed from the point of the unsteady pressure distribution on bridge deck surface during heaving/torsional vibration related to the aerodynamic derivatives. In particular, it is explained that the coupling terms, which consist of $A_1^*$ and $H_3^*$, play a substantial role on the coupled flutter, in comparison with the flutter characteristics of various structural sections. Also the effect of the torsional/heaving frequency ratio of bridge structures on the flutter instability is discussed from the point of the coupling effect between heaving and torsional vibrations.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.31-32
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• 2005

It is known that an oscillating airfoil can produce a driving force through the generation of a reversed $K\acute{a}rm\acute{a}n$ vortex street, and this can be expected to be a new highly effective propulsion system. We have been examined various conditions such as frequency number, amplitude in NACA 0010. As Strouhal number is greater than 0.08, wake profile with velocity deficit can be transformed into the wake with velocity excess. We also presented the experimental results on the unsteady vortices structure of the heaving airfoil at various parameters.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09b
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• pp.131-137
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• 2010

`Frost heave' is volumetric extension behavior of soil due to freezing. It could have a bad effect to foundations of infrastructures like building, road, railroad and bridge. Therefore, it is considered as a primary design parameter with 'adfreeze bond' and 'creep deformation' for foundation design in cold region. In some countries, studies for analyzing frost heave in many ways have being performed, however, only a few studies for evaluating frost susceptibility of soils by measuring frost heave rate of frozen soils in Korea. For analyzing frost heave as a foundation design parameter, both frost heaving rate and heaving pressure are should be addressed in study. Hence, in this study, development of experimental apparatus to evaluate frost heave and pressure is suggested.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1487-1493
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• 2008

The frost heaving is related with thermal conduction rate and permeability. If the thermal conduction rate can be controlled, it is effective to prevent from frost heaving. If soil mixed with shredded tire which has relatively lower thermal conduction rate than soil, it helps preventing from frost heaving. However, in this case, the shear strength can get weak. In this study, we compared thermal conduction rate of soil and shredded tire, and test uniaxial compression strength of soil which is mixed with shredded tire and cement in different ratio.

• Bulletin of the Society of Naval Architects of Korea
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• v.13 no.3
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• pp.1-9
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• 1976

A numerical method for solving the boundary-value problem related to potential flows with a free surface and an experimental work are introduced in this paper. The forced heaving motion of cylinders with arbitrary shapes in water of finite depth are Considered here. The Fredholm integral equation of the first kind is employed in determining strengths of singularities distributed on the body surface. And the results obtained by the present method for the case of a heaving circular cylinder on water of finite depth agree well with existing results of earlier investigators.

• Journal of the Korean GEO-environmental Society
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• v.17 no.6
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• pp.23-31
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• 2016

Nowadays abnormal coldness happens frequently in Korea and frost heaving causes unexpected ground deformation which results in severe problems for structures such as roadway, railroad and cutoff slope. 'Frost heave' as one of the primary phenomenon is considered to be an important factor together with 'adfreeze bond-strength' and 'creep deformation' for structural design process in permafrost area. Therefore, the fundamental study for frost heave has to be preceded for design of geo-structures in cold region. While various experimental apparatuses have been developed, there still exist a certain level of limitation to evaluate the frost-heave characteristics as design parameters. There are no standard testing method and criteria for analyzing frost heaving in Korea because temperature controlled testing apparatuses including a freezing chamber are expensive. In this paper, a new standard freezing and thawing testing apparatus is introduced, which simulates various freezing and thawing conditions in a soil specimen by using a temperature controlled triaxial cell. Frost heaving tests were performed to assess the new testing apparatus and experimental procedure to evaluate frost heaving for soils is proposed.

• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.65-74
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• 2003

Most of land reclamation projects are being implemented along the south and west coastal lines of the Korean Peninsula. The earth structures and in-ground LNG tank, and buildings can be constructed using artificial freezing method on the reclaimed land to control the uplift pressure caused by capillary forces. In this study, upon freezing a saturated soil in a closed-system from the top, a considerable frost heaving pressure was developed. Decomposed granite soils, silty soil, and sandy soil were used in the laboratory freeze test which is sometimes subjected to thermal gradients under closed-systems. A major concern has been the ability to predict the frost heaving pressure over the results of relatively short-term laboratory tests. The frost heaving pressure arising within the soil samples and the temperature of the samples inside were monitored with time elapse. The degree of saturation versus heaving pressure curve is presented for each soil sample and the maximum pressure is closely related to this curve. TDR apparatus was used to measure the volumetric water content by the measurement of unfrozen water contents of frozen soils. Unfrozen water increased in soils containing a high percentage of fine-grained particles. In fine-grained soils with strong attractive farces between soil grains and water molecules, additional water is attracted into the pores leading to further volume changes and ice segregation.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.10a
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• pp.55-57
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• 2005

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.1
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• pp.142-154
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• 2002

This study was performed to investigate constraint effects of deformation (heaving, lateral displacement) of clayey foundation reinforced with sheet pile at the tip of banking on soft ground, under intact state (natural) and the state of vertical drain respectively. The following results are obtained. 1. In view of reduction in heaving or lateral displacement, sheet pile is not supposed to be of use. 2. Sheet pile is effective only when vertical drain is installed for acceleration of consolidation and gradual loading is applied.

• Bulletin of the Society of Naval Architects of Korea
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• v.17 no.2
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• pp.33-42
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• 1980

This paper compared the seakeeping quality of U, V type ships in infinite depth by using the finite element method. From the calculated results, it is found that heaving and pitching motions of V type are comparatively better than those of U type ship in the water of infinite depth and the reversed phenomenon occures in the water of finite depth. And the seakeeping quality of U type is better than V type ship in larger ranges than the nondimensional wave number 2.0.