• Journal of the Korean Geotechnical Society
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• v.24 no.5
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• pp.37-54
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• 2008

The standard construction manual of the SDA (Separated Doughnut Auger) piling method was proposed so that the resisting capacity of the augered piles could work effectively. 438 dynamic pile load tests were performed on 379 test piles, which were installed at 36 sites in Korea by the SDA piling method with application of various water-cement ratio of cement milks. The dynamic pile load test results showed that the bearing capacity of the SDA augered piles depended on the water-cement ratio of cement milks. And couple of the formulas were presented according to water-cement ratio and various grounds to estimate quantitatively both the unit end bearing and the unit frictional capacity of the SDA augered piles. It was also considered that the water-cement ratio of cement milks exerts an influence on the bearing capacity of the SDA augered piles. The presented formulas were compared with the existing formulas, which were presented by several standard design codes to design the augered piles.

• Journal of the Korea Concrete Institute
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• v.20 no.5
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• pp.601-609
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• 2008

The purpose of this study is to investigate the flexural strengthening effectiveness for the beams combined reinforced with NSM CFRP strips and EBR CFRP strips. To accomplish this objective, a total of nine concrete T beams were tested. From this study, it is found that the flexural stiffness and strength of the beams combined reinforced with NSM and EBR strips were significantly improved compared to the beams strengthened only with NSM CFRP strip. The maximum increase of flexural strength was 347% compared to the beam without CFRP strip. Failure of the beam combined reinforced with NSM and EBR strips (T shape) is initiated by debonding of EBR strips attached on the bottom face, and it was succeeded a part of separatio-n of NSM strips along the longitudinal direction and secondly failure of NSM strips was occurred, eventually sudden explosive failure with the separation of concrete cover in the shear region. This result shows that the NSM and EBR strips have good combination to resist applied load and the combined reinforcement with NSM and EBR strips can redistribute appropriately the total stress subjected concrete beam to the EBR and NSM strips.

• Journal of Bio-Environment Control
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• v.4 no.1
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• pp.17-24
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• 1995

This study was carried out to make fundamental data for structural safety test of pipe- houses. Experiment on the stress distribution of pipe- houses was conducted to find suitable structural analysis model by examination of end support conditions of pipe. Besides, the loading test and the pile driving test were done to find pull-out capacity and bearing capacity of pipe on the assumption that pipe is pile foundation. For single span pipe - house, the theoretical results assuming the end support condition of pipe is fixed under ground agreed closely with the experimental results of stress distribution. On the other hand for double span pipe -house, the end support conditions of pipe were fixed support when vertical load is applied, and hinged one when horizontal load is applied. The pull - out capacity and allowable bearing capacity of the pipe portion that was buried in the grounds that were soft soil of paddy field and medium or hard soils of dry field derived from experimental results.

• 주택과사람들
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• s.210
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• pp.42-45
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• 2007

경기도교육청은 주택법에 따라 앞으로 학교 지을 땅을 살 계획을 세우지 않고 추진하는 아파트 등의 개발 사업을 동의해주지 않기로 했다. 이 방침대로 도교육청이 공동 주택 건설 사업에 대한 혐의 요청을 거부할 경우 새로운 대규모 아파트 건설 사업 추진이 사실상 중단될 수 밖에 없다. 학교 용지 매입비에 대해 살펴본다

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.9
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• pp.356-365
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• 2017

Most studies of the effects of corporate patents on managerial performance conducted to date have been based on internally-generated patents. However, global pharmaceutical and biotechnology companies acquire patents not only from internal research and development (R&D), but also through university-industry collaboration and purchase. Focusing on this issue, our study collected patents from various sources, including internal R&D, purchased patents, and university-industry collaboration, to examine the real effects more accurately. Additionally, our study used a finite time lag model to consider the time lag between patent and corporate performance. The results of the quantitative analysis of the relationship between patents and corporate financial performance revealed that patent quantitative levels had less impact on sales than other types. However, quantitative patents levels appeared to have a significant impact on market value. Moreover, quantitative patent levels appeared to moderate impact on corporate profit. Patents acquired by internal R&D had the greatest impact on market value, while purchased patents had the greatest impact on corporate profit and sales. The purchased patents had a significant effect on financial performance in the pharmaceutical and biotechnology companies because of the long time required and expense associated with R&D. Overall, the results of this study provide the basis for global pharmaceutical and biotechnology companies to configure an optimal patent portfolio.

• Journal of the Korea Institute of Building Construction
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• v.11 no.3
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• pp.229-237
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• 2011

The pullout test is a nondestructive testing method certified by the American Society for Testing and Materials (ASTM) and British Standards (BS). Research has shown that it is very reliable in terms of evaluating the concrete strength of reinforced concrete members. However, the pullout test is rarely performed on domestic construction sites due to the complex procedures and high costs involved. This study proposes a new pullout test composed of a post installable break-off bolt, an insert nut, and a pullout tester, which satisfy both economical and practical purposes on a construction site. Three different types of special fastening methods, a temporary fixed bolt, a plastic fixed panel, and a fixed bar, have been developed. A pullout tester is proposed that is driven by the circle force introduced into a handle composed of eight gears without a load cell and a hydraulic cylinder. The serviceability and reliability of these instruments were investigated through experiments at construction sites. Furthermore, the sample pullout test with a wall specimen was conducted to estimate the usefulness of the temporary fixed bolt type of fastening methods and pullout devices. Eventually, the developed instruments will be useful on construction sites if minor requirements are met.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.1
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• pp.73-85
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• 2014

The CFT (Concrete Filled steel Tubes) column-footing connection is cast-in-place embedded type which provides simple construction procedure, low cost, and superior structural performance. In this study, CFT column-footing connection of modular pier is proposed and structural performance is evaluated by experimental tests. To evaluate structural performance of the CFT column-footing connection, a series of experimental tests were performed for the 4 specimens with different embedded depth. As a result of the quasi-static test, the specimen with 0.6D (0.6 times the outside diameter of steel tube) embedded depth showed relatively low ductility than other specimens with larger embedded depth due to cone failure of base concrete occurred during the lower loading step. On the contrary, cone failure of the base concrete was not observed in the specimens with larger embedded depth than 0.9D, but typical flexural failure in lower part of CFT column was observed. With the analyses of force-displacement curve, displacement ductility, and energy dissipation capacity, it is concluded that the rational range of embedded depth of the CFT column-footing connection is from 0.9D to 1.2D in view of good seismic performance.

• Journal of the Korean Geotechnical Society
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• v.29 no.8
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• pp.53-63
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• 2013

Bored pre-cast piles using PHC piles is widely used in foundation of building structures constructed in urban areas because noise and vibration due to pile installation are low. However, since slime is formed at the base of borehole and the density of bearing stratum surrounding the base of borehole is decreased due to stress relaxation in drilling process of bored pre-cast pile method, the base load capacity of bored pre-cast piles is very low compared to the strength of bearing stratum. In this study, a new type of PHC pile, which short steel pipe with the same diameter as the PHC pile is attached to the pile tip, is developed to increase the base load capacity of bored pre-cast piles. In order to check the effect of the use of new PHC pile on the base load capacity of bored pre-cast piles, field pile load tests are performed for bored pre-cast piles using the new and existing PHC piles. Results of the pile load tests show that the new PHC pile gives higher base load capacity to bored pre-cast piles than the existing PHC pile, since the tip of new PHC pile is penetrated to undisturbed bearing stratum passing through the slime at the base of borehole and the loosened bearing stratum under the slime by pile driving using light hammer.

• Journal of the Korea Concrete Institute
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• v.25 no.1
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• pp.37-43
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• 2013

Recently, experimental and analytical researches have been performed in order to find interface failure between FRP plate and concrete in near surface-mounted (NSM) retrofit using FRP plate. As a result, it was found that the bond strength between concrete and NSM FRP plate had a close relationship with shape of FRP, concrete compressive strength and bond length. However, research need is increasing about another factors such as suitable space of FRP plate and group effect. In this study, therefore, a bond test was performed with aforementioned factors and compared with a previous equation to verify its suitability for predicting bond strength of NSM FRP plate. From the test, it was found that the bond strength increased according to the increase of space of NSM FRP plates even if its bond length was same. The splitting failure of concrete governed when space of FRPs was too narrow and it changed to FRP's tensile failure with increase of the space. From the evaluation of test specimens using previous equation, it was found that the bond strength could be predicted properly with consideration of group effect.

• Land and Housing Review
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• v.7 no.2
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• pp.67-75
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• 2016

This research suggests improvement strategies for the problems of 'public housing supplied through the purchase of existing house' by understanding the situation of supply to lowest income class in Seoul where there are many demands. Due to the heavy housing expenditure burden, in spite of the fact that the needs for affordable housings are increasing, the number of 'public housing supplied through the purchase of existing house' which has been supplied to Seoul by LH & SH has decreased since 2009. It is caused by the low standard purchasing price set by government especially Seoul. Since 'the public housing supplied through the purchase of existing house' is targeted for indigenous inhabitants, different supply stocks among different regions cause equity problem. Generally regions with low income class are in short supply, on the contrary the supply is especially concentrated specific regions in outskirts of Seoul. The main reason of such new supply stagnation and regional concentration is the low standard purchasing price. Therefore, it is necessary to increase the government's standard price according to the actual transaction price. Also it is needed to associate actual transaction price's increasing rate with the government's standard price. The housing supply based on demands must be established. In addition, the provision of 'public housing supplied through the purchase of existing house' should be expanded to low-middle income inhabitants and low income youth in the regions where the supply of the affordable housing excess demands.