• Journal of the Korean Magnetics Society
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• v.13 no.4
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• pp.176-181
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• 2003

The magnetic domain walls at the edges of a large patterned and exchanged-biased NiO(10-60 nm)/NiFe(10 nm) bilayers and their motions with applied field were investigated by magnetic force microscopy. Three kinds of domain walls, namely, head-to-head zig-zag and tail-to-tail zig-zag Bloch walls and straight Neel walls were found at specific edges of the unidirectional biased NiO(30 nm)/NiFe(10 nm) bilayer having the exchange biasing field (H$\sub$ex/) of 21 Oe. No walls were observed for the strong exchange-biased bilayer (60 nm NiO, H$\sub$ex/ = 75 Oe), while the amplitude of the zig-zag domain increased with decreasing exchange biasing. This may be explained by mutual restraint between H$\sub$ex/ and the demagnetization field of edge. We similarly investigated the magnetization reversal process, the subsequent motion of the walls and identified the pinning and nucleation sites during reversal.

• Journal of the Korean GEO-environmental Society
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• v.11 no.2
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• pp.61-68
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• 2010

Recently, it is a trend of the underground excavation to become larger and deeper for more effective use of available space and with the advent of new excavation technologies. The ground typically has a complex stratigraphy. The excavation can lead to large deformation in the nearby structures and large earth pressure on the wall. This can lead to serious problem in the stability of the wall. For the retaining wall to be safely constructed, it is important that the stratigraphy and engineering properties of the ground be accurately estimated, based on the excavation plan and appropriate excavation method. This study uses the measured field data and numerical results to characterize the characteristics of the lateral deformation of the retaining wall. A touredof six field data were analysed. SUNEX, a numerical program which uses the elasto-plastic model to represent the soil, was used. It was shown that the measured deformations exceeded the proposed values for shallow excavations. Overall, the maximum lateral deformation was within the proposed value and hence, the walls were analyzed as safe.

• Journal of the Korean Geotechnical Society
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• v.33 no.1
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• pp.17-30
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• 2017

There are many limitations for ensuring structural stability of retaining wall. Especially, L-shaped retaining wall and gravity retaining wall need large space, and massive concrete, respectively. Assembled Earth Retailing (AER) wall was developed to overcome the shortcomings. In this paper, stability of AER wall is verified by field model tests and the 3D-numerical analysis. The results show that horizontal displacement of AER wall was reduced by maximum 67.84% for conventional retaining walls, and earth pressure acting on the retaining wall was reduced by maximum 73.19%.

• Proceedings of the Korean Geotechical Society Conference
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• 1998.10a
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• pp.291-296
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• 1998

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.87-94
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• 2000

This paper concerns the distribution of earth pressures on a cantilever wall with unattached reinforcements in the backfill. This type of walls is different from the existing reinforced earth walls in that unattached reinforcements are placed in the backfill of rigid retaining wall such as gravity wall and cantilever wall, instead of connecting reinforcements to the wall segments. Two large-scale prototype tests have been carried out with a 4m high cantilever wall; one with unreinforced backfill, the other with unattached strips in the backfill. The reinforcing effect of unattached strips are discussed based on the earth pressure distribution measured in two large-scale prototype tests. Also, the comparison between measured and predicted earth pressure on a wall with unattached strips are discussed herein to confirm the validity of analytical prediction.

• The Journal of Engineering Geology
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• v.26 no.1
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• pp.51-61
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• 2016

New building methods are needed to aid increased inner-city redevelopment and industrial construction. A particular area of improvement is the efficient use of cut slopes, with the minimization of associated problems. A retaining wall of precast panels can resist the horizontal earth pressure by increasing the shear strength of the ground and reinforcing it through contact with the panels. Precast panels allow quick construction and avoid the problem of concrete deterioration. Other problems to be solved include the digging of borrow pits, the disposal of material cut from the slope, and degradation of the landscape caused by the exposed concrete retaining wall.This study suggest the methods of improvement of an existing precast panel wall system by changing the appearance of the panels to that of natural rock and improving the process of adhering the panel to a vertical slope. The panels were tested in the laboratory and in the field. The laboratory test verified their specific strength and behavior, and the field test assessed the panels' ground adherence at a vertical cutting. Reinforcement of the cutting slope was also measured and compared with the results of 3D numerical analysis. The results of laboratory test, identified that the shear bar increase the punching resistance of panel. And as a results of test construction, identified the construct ability and field applicability of the panel wall system adhered to in-situ ground. In addition to that, extended measurement and numerical analysis, identified the long-term stability of panel wall system adhered to in-situ ground.

• Journal of the Korean Institute of Landscape Architecture
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• v.33 no.2 s.109
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• pp.32-47
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• 2005

This study was carried out to investigate and propose a green-wall system with evergreen plants for urban greening of Tongyeong City. To achieve these goals, the requirements and possibilities for wall greening were investigated and evaluated considering the location, topography, and climate of Tongyeong City. Existing walls were analyzed and then a suitable green wall system is proposed. Tongyeong City and its 151 islands covers the central and the southern parts of the Goseong peninsula. Most of the land is covered with hills and mountains; $43.9\%$ of the land area has a slope greater than $15\%$ and most hills and mountains near the urban area have a slope of more than $30\%$. As a result of the topographical properties, concrete retaining walls can often be seen along the streets in urbanized areas. These retaining walls are not only unattractive, but they also create environmental problems, and thus should be replaced with native evergreen plants. Options for replacing the retaining walls include evergreen vine-plants such as Hedaa spp. and Euonymus radicans, but native evergreen shrubs such as Pittosporum tobira, Nandina domestica, Raphiolepis umbellata, Ilex cornuta, flex crenata, Fatsia japonic, and Aucuba japonica may be a more attractive option. Current wall conditions are unsuitable for planting vines, therefore, a reservoir-drainage-type plant box filled with a light artificial substrate is required for greening these concrete retaining walls. These might be irrigated in the dry season and fertilized annually by an appropriate system. These plant boxes could be attached along the entire walls. An experiment investigating effects of substrates and bark-chip mulching on the growth of Hedera spp. showed that the mixture of cerasoil and field soil(v/v, 4:6) was superior to field soil alone and to the mixture of perlite small grain, large grain, and field soil(v/v/v, 2:2:6). Bark-chip mulching tended to increase the growth of Hedera spp..

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.207-207
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• 2000

Multi- and single-wall carbon nanotubes are promising new carbon materials in nano-electronics, field-emitters, CRT-displays, hydrogen storage materials, biomedical tracers and so forth. The present talk will deal with a high-yield synthesis on quasi-aligned multi-wall carbon nanotubes via a chemical vapor deposition technique. I will also talk about a possible growth mechanism on single-wall carbon nanotubes based on newly obtained experimental results.

• Journal of the Society of Disaster Information
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• v.12 no.4
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• pp.366-372
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• 2016

Recently in case of the concrete retaining wall precast technological change in the field assembled by the way. A precast wall is devied into upper and lower respectively, and the way, assembled in field is being performed. But the assembled part could have been damaged by the earth pressure in a relatively high buttress wall. And, it have been pointed out that large-scale disaster can be occurred. Thus, in this thesis, a structural stability for the buttressed retaining wall with pre-cast joint method was analyzed by a numerical analysis method. The structural stability of the three height retaining wall(7.6m, 8.5m, 10m) was conducted respectively for earth pressure. The maximum principal stress applied to the concrete retaining wall was analyzed to occur locally in the vicinity of the fixing anchor as 23.3 ~ 43.2 MPa.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.548-553
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• 2002

Most tasks of the large vertical or ceiling structures have been carried out by human power. Those tasks require us much operation costs and times, safety devices, etc. So the need of automation for those tasks have been rising. That automation needs a wall-climbing mobile vehicle. Most former researches are things about attachment devices and moving mechanisms. A wall-climbing mobile vehicle must be designed by a method different from the case of the vehicle of the horizontal environment. That is because gravity acts as a negative role on the stability of a wall-climbing vehicle. In this thesis, the particular shape characteristics of a wall-climbing mobile vehicle are derived by the wall-environment modeling. In addition, some design constraints of the permanent magnetic wheel as an attachment device was studied. According to those requirements and constraints, one specific wall-climbing mobile vehicle was designed and some experiments were made on the attachment ability of that vehicle.