• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.1
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• pp.175-183
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• 2014

This study investigates the response of structures to tunnelling-induced ground movements in clay ground, varying tunnel excavation condition (tunnel depth and diameter), tunnel construction condition (ground loss), and tunnel ground condition (soft clay and stiff clay). Four-story block-bearing structures have been used because the structures can easily be characterized of the extent of damages with crack size and distribution. Numerical parametric studies have been used to investigate of the response of structures to varying tunnelling conditions. Numerical analysis has been conducted using Discrete Element Method (DEM) to have real cracks when the shear and tensile stress exceed the maximum shear and tensile strength. The results of structure responses from various parametric studies have been integrated to consider tunnel excavation condition, tunnel construction condition, and tunnel ground condition and provide a relationship chart among them. Using the chart, the response of structures to tunnelling can easily be evaluated in practice in clay ground.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1502-1508
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• 2011

Ground anchor expands the hollow wall of settled part and has the structure which resists the designed tensile load by the bearing pressure generated by the wedge of the anchor body pressing in the expanded part. Such ground anchor has been recognized for stability and economicality since 1960s in technologically advanced nations such as Japan and Europe, and in 1970s, the Japan Society of Soil Engineering has established and announced the anchor concept map. The ground anchor introduced in Korea, however, has the structural problem where the tensile strength is comes only from the ground frictional force due to expansion of the wedge body. In an interval where the ground strength is locally reduced due to fault, discontinuation or such, this is pointed out as a critical weakness where the anchor body of around 1.0m must resist the tensile load. Also, in the installation of concrete block, the concentrated stress of concrete block constructed on the uneven rock surface causes damage, and many such issues in the anchor head have been reported. Thus, in this study, by using the expanded bit for precise expansion of settled part, the ground anchor system was completed so that the bearing pressure of ground anchor can be expressed as much as possible, and the bearing plate was inserted into the ground to resolve the existing issues of concrete block. Through numerical analysis and pullout test executed for verification of site applicability, the pullout-behavior characteristics of anchor was analyzed.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.820-825
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• 2007

A ballscrew-linear motion(LM) guide is well-described by its name: it is a LM guide that runs by ballscrew. It consists of LM rail, LM block, end plate, screw, nut and bearing balls. The ballscrew-LM guide has many advantages compared with conventional LM guide. The high efficiency achieved with rolling contact devices permits the employment of antibacklash methods. The balls provide the only physical contact between nut rail and block and ball screw and nut replacing the sliding friction with a rolling motion. The life of the ballscrew-LM is determinated by the balls. The objective of this paper is to introduce the design of the ballscrew-LM with the safety working load.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.3 no.4
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• pp.1-10
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• 2000

This study aims at the new design system development of landscape architecture structures, as soundproof wall using reinforced soil block. This structures, that is new soundproof wall system, have to be maintained stability on acting critical wind load, which is combined exist soundproof wall system and soundproof wall system using environmental green stone block. To the harmony of this system, the post block, so-called landscape block or cast block, is manufactured. It's possible to stand of the post bearing system combined with post-pile and post block. Through the comparison with a serious code for the acting wind load on the soundproof wall, the reasonable wind load could be calculated. Also, the mechanical stability on the green stone block was checked by the Lab. tests based on the UBC (Uniformed Building Code). Because the critical height of soundproof wall system using green stone generally was restricted, the new system demands to combination of the exist system and the new system. For the stability analysis of them, the utility program, SAP2000, was used. And, a semi-auto program on the design system of the new soundproof wall using green stone was developed, which can be easily use because of the simplification.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.440-447
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• 2020

Masonry structures are used as bearing walls in small buildings, but they are generally considered non-bearing walls. They are used as partition walls that divide the interior spaces of the frame structures of buildings. In addition, wetting techniques that use mortar as an adhesive between blocks or bricks in construction are vulnerable to climatic conditions, especially cracks in mortar, which can cause conduction collapse of the walls in seismic loading. The purpose of this research was to propose a dry concrete block construction method that complements the weak axial shear stiffness and improves the weakness of the wet construction method as well as to investigate its structural behavior. In this study, the material properties of concrete blocks were examined, and the seismic performance of the proposed dry assembly structure was verified by structural behavior tests on horizontal cyclic loads. First, in these study results, concrete blocks can be applied to the dry block construction method instead of wet construction methods because they secure more than C-type blocks in KS regulations. Second, the structural performance of the wall against a horizontal cyclic load indicates that the resisting force of the assembly block wall is increased by increasing the horizontal length of the wall, forming several diagonal cracks. Finally, the proposed dry block wall structure requires a seismic performance assessment considering that the ratio of the shape of the wall by height and length is considered a major influence variable on the structural behavior under a horizontal load.

• Journal of the Korean Geosynthetics Society
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• v.5 no.1
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• pp.9-14
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• 2006

The reinforced soil retaining wall structures of serious types with environmental are widely expanding more and more in Korea, which divided conventional type's reinforced soil retaining wall on segmental retaining wall. The causes of most crack occurred at block in reinforced soil retaining wall structure caused by the differential settlement of foundation. It is difference of settlement for significant factor that with overall slope stability. In this study, design assessment of foundation bearing capacity related to differential settlement of foundation ground was considered. And, also, through case study, the countermeasure methods and its application were suggested that the bearing capacity of foundation had to stabilize. The foundation ground in charge of bearing capacity should be affected by the resisting force of sliding, because the foundation parts of reinforced soil retaining wall were belongs to potential slope sliding area in overall stabilizing including retaining wall structures. Therefore, the analyzing or the designing of bearing capacity for foundation should be considered control capacity on the overall slope sliding.

• Magazine of the Korean Society of Agricultural Engineers
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• v.30 no.1
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• pp.38-49
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• 1988

This paper presented as follows results of laboratory model tests with various shaped footings on soil bed reinforced with the strips on the base of behaviour of soil structure according to the loads and triaxial test results reinforced with geotextiles. Their parameters studied were the effects on the bearing capacity of a footing of the first layer of reinforcement, horizontal and vertical spacing of layers, number of layers, tensile strength of reinforcement and iclination load to the vertical 1.Depending on the strip arrangement, ultimate bearing capacity values could be more improved than urreinforced soil and the failure of soil was that the soil structure was transfered from the macrospace to microspase and its arrangement, from edge to edge to face to face. 2.The reinforcement was produced the reinforcing effects due to controlling the value of factor of one and permeable reinforcement was never a barrier of drainage condition. 3.Strength ratio was decreased as a linear shape according to increment of saturation degree of soil used even though at the lower strength ratio, the value of M-factor was rot influenced on the strength ratio but impermeable reinforcement decreased the strength of bearing capacity. 4.Ultimate bearing capacity under the plane-strain condition was appeared a little larger than triaxial or the other theoretical formulars and the circular footing more effective. 5.The maximum reinforcing effects were obtained at U I B=o.5, B / B=3 and N=3, when over that limit only acting as a anchor, and same strength of fabric appeared larger reinforcing effects compared to the thinner one. 6.As the LDR increased, more and more BCR occurred and there was appeared a block action below Z / B=O.5, but over the value, decrement of BCR was shown linear relation, and no effects above one. 7.The coefficient of the inclination was shown of minimum at the three layers of fabrics, but the value of H / B related to the ultimate load was decreased as increment of inclination degree, even though over the value of 4.5 there wasn't expected to the reinforcing effects As a consequence of the effects on load inclination, the degree of inclination of 15 per cent was decreased the bearing capacity of 70 per cent but irnproved the effects of 45 per cent through the insertion of geotextile.

• Journal of the Society of Naval Architects of Korea
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• v.49 no.4
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• pp.304-311
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• 2012

One of the main features of Drillship or FPSO is a moonpool structure. The moonpool structures have various accuracy tolerances according to their functions and targets. This study is mainly interested in roundness of a circular moonpool structure in FPSO. Because this structure needs abrasion-resistance at which bearing of machine touches on inner wall of moonpool, we should do over-lay welding widely and deeply by using Inconel weld material. But a general over-lay can cause a severe distortion at ship block structure. If we can analyze the roundness by thermal distortion under Inconel over-lay, we can establish a special erection policy by the results. In this study, we designed stress-strain curve for strain-boundary condition analysis by an elasto-plastic material property. The results made us to decide an appropriate ship-block size and policy of crane manipulation will follow for its capacity. If a structure that needs over-lay is not large, solid elements also are not a bad choice for FEM modeling. Therefore we also developed a standard of using strain-boundary method that shell elements are used as over-lay on solid element modeling.

• The Korean Journal of Ecology
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• v.14 no.1
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• pp.25-38
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• 1991

Berchemia berchemiaefolia is a native a native rare plant which has been designating as the Natural Monument, No. 266, since 1980. The floristic composition, population structure and maintenance mechanism of the Berchemia berchemiaefolia forest were investigated in conjunction with the habitat consisted of the block field or screes. Through the present study, the authors found a new habitat of Berchemia berchemiaefolia in the northeastern slope on Mt. Kumdansan located at Hajeok-ri, Cheongcheon-myeon, Koesan-gun, chungbuk province. Gravels consisted of the block field belonged to granule, pebble and cobble as the range of grain size, $\Phi$=-1.5~6.6 values. The tree layer of Berchemia berchemiaefolia community was mainly composed of Quercus variabilis, Pinus densiflora and Q. serrata including Berchemia berchemiaefolia and of this community were similar to that of Q. variabilis. By the age distribution, it was considered that the community was a discontinued one as the pattern of distribution was a normal distribution type(N type). Phenological cycle including leafing, blooming and seed-bearing period between both sites of block field and valley or close canopy showed some differences. The seed production of Berchemia berchemiaefolia was 8, 655, 000 seeds/ha/year, but only 406, 000 seeds/ha/year of them were developed as saplings, and only 4 saplings were developed to mature trees.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.6 s.58
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• pp.176-182
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• 2009

Other damage can occur due to the preexisting dull structure and installation of nonenvironmental-friendly concrete structure, lack of function for preventing coastal erosion. Increase of personal income and fast spread of the concept of waterfront casued the initiation of many project to improve aging coastal ports. However, none of environment-friendly structure has been developed and pre-existing solid block, igloo block, tunnel block are used commonly. In piers and lighter's wharf where the ships are mooring, resonance by the generation of a reflected wave caused by penetration wave in the port and port wave increases wave heights in the port and makes difficult to maintain the temperature, causes problems in mooring ships and cargo-working, and eventually increase the occurance of damages of the small ships by the collision. Therefore, development of new types of blcok is necessary. To apply Coastal Environments block developed for this reason, it requires allowable bearing capacity evaluation of shear key. For this study, we made test specimen for connecting part of C.E. Block, and conducted friction test of boundary surface. Data obtained by the experiment was analyzed by finite element analysis and assessed the coefficient of friction between C.E. Block and boundary surface.