• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.1
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• pp.67-76
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• 1989

Although the standard 2-CR network filter, one of the filters used for measuring surface roughness, is being used widely in the field of industry it possesses a weak point of causing Phase-distortion when the wavelength is passing through. Phase-corrected filter is used for eliminating these phase-distortion and the difference of phase characteristics between these two filters is thought to have considerable amount of effect on the surface roughness value. Moveover, the definition on this is as yet unclear. Therefore, the Rt and Rz value, obtained when the wavelength are passed through the standard and phase-corrected filters from the same random machine-processed surface, and its standard deviation are compared and experimented in this paper. Also, the ratio of relative bearing curve complying to the phase characteristics of these two filters are acquired. As a result, the use of phese-corrected filter is appropriate in experiments where the form of wavelength is important, and the standard deviation on the same experimented values appeared greater with when using the standard filter. The rate of relative bearing curve became greater as .lambda.$_{c}$, the cut-off value of filter, became smaller.r.

• International Journal of Highway Engineering
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• v.5 no.1 s.15
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• pp.35-45
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• 2003

This paper presents a theoretical approach for estimation of CBR-value of subbase course and subgrade using a portable pavement dynamic cone penetrometer(PDCP). The PDCP used in this paper was based on a design from South Africa and extensive studies by Kleyn(1982) and more recently by Liveneh and Ishai(1987) and Chua(1988). To date, California Bearing Ratio[CBR] value was studied mainly for application of pavement structural design. This study was initiated to develop a method of obtaining the in situ CBR-values of subbase and subgrade for the structural evaluation of pavements in the swift and inexpensive manner. PDCP tests were implemented at 20 different kinds of soil samples in the lab and test results were analysed by a theoretical approach introduced. The procedure presented provides acceptable and promising results.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.2
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• pp.25-33
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• 2012

To examine the performance of a thin plate damper attached to coupling beam of bearing wall system, 5 specimens were designed with the variable parameters of the thickness and length of a thin steel plate, which was constructed and tested with a lateral load with up to a 5% drift ratio. The result was that the total amount of the energy dissipation of the specimen with the thin plate damper was greater than that of the standard RC specimen, and the plate buckling and plastic deformation could be seen in steel plate. The shorter the length of the damper, the higher was the lateral resistant force, but there was no apparent increase in the energy dissipation. By comparison of the experiments with the elastic buckling analysis, it was shown that the buckling force from the analysis could properly estimate the maximum value of the linear elastic range.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.993-1000
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• 2009

In general, a drilled shaft embedded in weathered rock has a large load bearing capacity. Therefore, most of the load tests are performed only up to the load level that confirms the pile design load capacity, and stopped much before the failure load of the pile is attained. If a reliable failure load value can be extracted from the premature load test data, it will be possible to greatly improve economic efficiency as well as pile design quality. The main purpose of this study is to propose a standard for judging the reliability of the failure load of piles that is obtained from extrapolated load test data. To this aim, eleven static load test data of load-displacement curves were obtained from testing of piles to their failures from 3 different field sites. For each load-displacement curve, loading was assumed as 25%, 50%, 60%, 70%, 80%, and 90% of the actual pile bearing capacity. The limited known data were then extrapolated using the hyperbolic function, and the failure load was re-determined for each extrapolated data by the ASCE 20-96 method (1997). Statistical analysis was performed on the reliability of the re-evaluated failure loads. The results showed that if the ratio of the maximum-available displacement to the failure-load displacement exceeds 0.6, the extrapolated failure load may be regarded as reliable, having less than a conservative 20% error on average. The applicability of the proposed standard of judgment was also verified with static load test data of driven piles.

• Journal of Korean Association for Spatial Structures
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• v.17 no.2
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• pp.21-32
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• 2017

The objective of this study is to analysis the mechanical characteristics on the geometric nonlinear behavior of radial cable roof systems for long span retractable cable roof structures. The retractable roof is designed as a full control system to overcome extreme outdoor environments such as extreme hot or cold weather, strong wind or sunlight, and the cable roof greatly can reduce roof weight compared to other rigid structural system. A retractable cable roof system is a type of structures in which the part of entire roof can be opened and closed. The radial cable roof is an effective structural system for large span retractable roofs, the outer perimeter of the roof is a fixed membrane roof and the middle part is a roof that can be opened and closed. The double arrangement cables of a radial cable truss roof system with reverse curvature works more effectively as a load bearing cables, the cable system can carry vertical load in up and downward direction. In this paper, to analyze the mechanical characteristics of a radial cable roof system with central posts, the authors will investigate the tensile forces of bearing cables, stabilized cables, ring cables, and the deflection of roof according to the height of the post or hub that affects the sag ratio of cable truss. The tensile forces of the cables and the deflection of the roof are compared for the cases when the retractable roof is closed and opened.

• Steel and Composite Structures
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• v.7 no.4
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• pp.339-354
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• 2007

Arched Corrugated Steel Roof (ACSR) is a kind of thin-walled steel shell, composing of arched panels with transverse small corrugations. Four full-scale W666 ACSR samples with 18m and 30m span were tested under full and half span static vertical uniform loads. Displacement, bearing capacities and failure modes of the four samples were measured. The web and bottom flange in ACSR with transverse small corrugations are simplified to anisotropic curved plates, and the equivalent tensile modulus, shear modulus and Poisson's ratio of 18m span ACSR were measured. Two 18 m-span W666 ACSR samples were analyzed with the Finite Element Analysis program ABAQUS. Base on the tests, the limit bearing capacity of ACSR is low, and for half span loading, it is 74-75% compared with the full span loading. When the testing load approached to the limit value, the bottom flange at the sample's bulge place locally buckled first, and then the whole arched roof collapsed suddenly. If the vertical loads apply along the full span, the deformation shape is symmetric, but the overall failure mode is asymmetric. For half span vertical loading, the deformation shape and the overall failure mode of the structure are asymmetric. The ACSR displacement under the vertical loads is large and the structural stiffness is low. There is a little difference between the FEM analysis results and testing data, showing the simplify method of small corrugations in ACSR and the building techniques of FEM models are rational and useful.

• Economic and Environmental Geology
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• v.8 no.4
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• pp.175-182
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• 1975

The chemical similarity of the magnetite-bearing amphiboltes of the Yangyang iron mine to mixtures of sedimentary pelites and limestone or dolomite and to the Gyeonggi para-amphibolites (So, 1974) is consistently indicated by all the chemical data of the rocks. Eight amphibolite samples were each analyzed for 18 elements, by wet chemical and emission spectroscopic methods, and these chemical data were compared with the para-amphibolites from the Gyeonggi metamorphic complex. Petrography and oxidation ratios were also considered.

• Journal of the Korea Institute of Building Construction
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• v.11 no.5
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• pp.501-514
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• 2011

Recently, there have been many cases in which the difficulty of repair and replacement of principal elements in the bearing wall structure for apartment buildings, which is a major part of apartment buildings in Korea, has led to the reconstruction of buildings rather than their remodeling. To address this problem, the Korea government now allows a floor area ratio of up to 20 %, and has relaxed the building height limits to encourage the use of a rahmen structure instead of a bearing wall structure. However, since reinforced concrete rahmen structures have many problems, including higher floor height and greater construction cost, a great deal of research into rahmen composite precast concrete structures have been conducted. Green Frame, one of the developed prototypes, is expected to provide economic benefits through in-situ production for precast concrete column and beam. For in-situ production of composite precast concrete members, a detailed plan for production, curing, and installation is needed. However, it needs to be confirmed that the space is sufficient to produce the precast concrete members on-site before planning those activities. Therefore, this study proposes in-situ production analysis of composite precast concrete members of Green Frame with the evaluation of structural safety and available area on the parking structure. The result of this study shows that the in-situ production of precast concrete members is possible through a case study.

• 한국해양학회지
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• v.30 no.2
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• pp.138-146
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• 1995

Present study was performed to describe the growth of Leptochela gracilis (STIMPSON, 1860), the dominant species of the coastal water near Kanghwa Island, Korea. Samples were collected from 1 sampling point by long bag seine net at monthly interval from April 1993 to January 1994 except for August 1993. In the population study of Leptochela gracilis, ovigerous female has appeared from April to September 1993 and the ratio (egg-bearing female/female) showed over 70% from May to July 1993. Female individuals were predominant from May 1993 to January 1994 and it was found that sex ratios were not significantly different between pregnant and non-pregnant period(p>0.05). The population of Leptochela gracilis was divided into 2 types of generation; i) short term generation. and ii) long term generation. Longevity of the long term generation was presumed to vary from 12 to 15 months. In the case of short term generation, spawned by egg-bearing stock of September, however, it was not certain whether they absorbed in the long term generation, thus overcome winter season or die after December by environment factors. The growth in cavalcade length of the long term generation was better fitted to Pauly and Gaschutz model than Von Bertalanffy.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.1
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• pp.19-28
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• 2022

In this study, three types of combined isolator consisting of High Damping Rubber Bearing (HDRB) and wire isolator were developed for Uninterruptible Power Supply system (UPS). The dynamic characteristics of the combined isolator were investigated through one-axis shaking table test. The input acceleration were generated in accordance with ICC-ES AC156 code. Scale factors of the input acceleration were designed to be 0.5-2 times the required response spectrum defined in ICC-ES AC156. Based on the test results, damage and dynamic characteristics of the UPS were investigated: including natural frequency, damping ratio, acceleration time history response, dynamic amplification factor and relative displacement. Based on that, it was found that the combined isolator developed in this study could improve the seismic behavior of the UPS, in particular, the response acceleration.