• Title/Summary/Keyword: Foundation failure

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Development and Evaluation of Hollow-head Precast Reinforced Concrete Pile (말뚝머리 중공 프리캐스트 철근콘크리트 말뚝의 성능 평가)

  • Bang, Jin-Wook;Hyun, Jung-Hwan;Ahn, Kyung-Chul;Kim, Yun-Yong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.21 no.2
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    • pp.130-137
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    • 2017
  • Due to the economic growth and development of construction technology, a role of foundation to resist heavy loads has been increased. In this present study to improve the structural performance of reinforced concrete pile, the precast HPC pile reinforced with rebar and filling concrete was developed and the strength of pile was predicted based on the limit state design method. The safety of HPC pile strength was evaluated by comparing with the design values. The geometry of HPC pile is a decagon cross section with a maximum width of 500 mm and a minimum width of 475 mm, and the hollow head of pile thickness is 70 mm. The inner area of the hollow head part was made as the square ribbed shape presented in the limit state design code in order to achieve horizontal shear strength between pile concrete and filling concrete. From the shear test results, it was found that the stable shear strength were secured without abrupt failure until maximum load stage despite the shear cracks was found. Shear strength is 135% and 119% higher than that of design value calculated from limit state design code. The driving test results of HPC pile according to the presence of additional reinforcement showed the outstanding crack resistance against impact loads condition. From the bending test results the flexural load between PHC pile and HPC pile was 1.51 times and 1.48 times higher than that of the design flexural load of conventional PHC pile.

Examination of Applicability of Liquefaction Potential Index to Seismic Vulnerability Evaluation of the Korean River Levees (액상화 가능 지수의 국내 하천제방 지진취약도 평가 적용성 검토)

  • Ha, Iksoo;Moon, Injong;Yun, Jungwon;Han, Jintae
    • Journal of the Korean GEO-environmental Society
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    • v.18 no.4
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    • pp.31-40
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    • 2017
  • In this study, a simple method to evaluate the seismic vulnerability of river levees was examined considering the structural characteristic of river levee, that is long, and the functional characteristic of river levee that performs temporary function against flood but is a permanent structure in the ordinary way. Considering the fact that one of the main failure modes of the levee during the earthquake are the settlement due to the strength reduction of the ground caused by the increase of the excess pore pressure in the levee body and foundation and the settlement due to liquefaction, the 2-dimensional section of the levee was regarded as the 1-dimensional section and the liquefaction potential index (LPI) for the regarded section was estimated. The estimated LPI was correlated with the seismic vulnerability of river levees. The relationship between the displacement of the levee crest caused by the earthquake and the seismic vulnerability of the levees was obtained from the results of previous researches and the correlation between the displacements of the levee crest computed by 2-dimensional dynamic coupled analyses and LPIs based on the results of 1-dimensional seismic response analyses was investigated. In connection with this correlation, as a result of examination of the correlation between LPI and the seismic vulnerability of the levee, it was concluded that the method for evaluation of the seismic vulnerability of the Korean river levee using LPI is applicable.

Suggestion of the Settlement Estimation Method for Granular Compaction files Considering Lateral Deformations (횡방향 변형을 고려한 조립토 다짐말뚝의 침하량 평가기법 제안)

  • Hwang Jung-Soon;Kim Hong-Taek;Kim Seung-Wook;Koh Yong-Il
    • Journal of the Korean Geotechnical Society
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    • v.21 no.3
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    • pp.149-157
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    • 2005
  • In cases of the loosely accumulated ground and soft clayey soils, the settlement criterion usually governs in evaluating the stability of structures. The settlement is also a dominant factor to control the design of granular compaction piles mainly applied to the reinforcement of foundation structures in soft ground. In the previous studies, settlement behaviors of granular compaction piles have generally been analyzed with an evaluation of the settlement reduction factor based on the load-sharing ratio and the replacement ratio. In this approach, however, since the reinforced ground with granular compaction piles is simplified as the composite ground, only the difference of a relative vertical strength between piles and soils is taken into account without reflecting lateral behaviors of granular compaction piles. In the present study, the method of estimating the settlement of granular compaction piles is proposed by synthetically considering a vertical strength of the ground, lateral behaviors of granular compaction piles, the strength of pile materials, a pile diameter, and an installation distance of the pile. Further, far the verification of a validity of the proposed method, predicted settlements are compared with results from previous studies. In addition, parametric studies are performed together with detailed analyses of relevant design parameters.

A Study on Prediction of Nugget Diameter by Resistance Spot Welding Finite Element Analysis of High Tensile Steel (SGAFC 780) (고장력 강판(SGAFC780)의 저항 점 용접의 유한요소해석을 통한 너깃 직경 예측)

  • Lee, Cheal-Ho;Kim, Won Seop;Lee, Jong-Hun;Park, Sang-Heup
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.11
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    • pp.144-150
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    • 2019
  • In this study, resistance spot welding was performed using a high tensile steel plate SGAFC 780. The shear tensile strength, fracture profile, nugget diameter, and simulation were compared according to the conditions. After the nugget diameter calibration, the minimum diameter of welding was more than 4.3mm when the welding current was 8kVA or more. At 9kVA and above 10kVA, the minimum nugget diameter of 4.3mm was satisfied. On the other hand, due to the high current and time, the fly phenomenon occurred and the deep indentation remained. An evaluation of the weldability confirmed that there was an interval that was evaluated as weld failure due to the creep phenomenon, which satisfied the tensile shear strength and minimum nugget diameter. On the other hand, areas that have sufficient load bearing capacity even when drift has occurred were also identified. The simulation results show that the error rate was less than 4.2% when comparing the nugget diameter in the simulation and the experimental results in the appropriate weld zone, and confirmed the reliability of the simulation.

How does Welfare State Colonize the Private Spheres : Political Fragmentation and Depoliticization (복지국가는 사적 공간을 어떻게 식민화하는가 : 정치의 분절화와 탈정치화)

  • Han, Dongwoo;Choi, Hyeji
    • Korean Journal of Social Welfare
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    • v.67 no.2
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    • pp.161-181
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    • 2015
  • This article tries to identify the regulating mechanism of the welfare states on the private spheres of individuals and families. When the welfare state is to be understood as an institutional arrangement which is based upon the 'modernity', the reflectivity on the welfare state is about to be on the modernity and on the institutions as well. Authors assume the welfare state as an historical and developmental type of modern states. The critical components of modernity embedded in birth and growth of modern welfare states projected to their institutions are identified. Welfare states dissociates the political dynamics which have built the foundation of the welfare state itself, and faces against the new political dynamics of the individualized society. Finally, welfare state confronts the institution failure due to its intrinsic characteristics, and consequently individuals and families come across the institution dependency. Individuals in the overly rationalized spheres are being depoliticized, and they are identified themselves as the subjects of status-struggles of the institutions other than the subjects of the political dynamics of welfare states.

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The Effects of Entrepreneurial Characteristics and Entrepreneurial Intentions : Focusing on Entrepreneurship Education completed Prefounders (창업가 특성이 창업의지에 미치는 영향에 관한 연구 : 창업교육을 이수한 예비창업자를 중심으로)

  • Park, Ji Yu;Yang, Hae Sool
    • Asia-Pacific Journal of Business Venturing and Entrepreneurship
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    • v.9 no.2
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    • pp.97-107
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    • 2014
  • Intensive studies have been focused on conditions for business foundation and the entrepreneurship in light of management, economy, and social psychometrics. This study focused on potential effect of entrepreneurial characteristics on environment for entrepreneurial intentions in establishment of orientation of entrepreneurial intentions. Among various factors affecting on starting small and medium size enterprises, how entrepreneur's personal characteristics is related on entrepreneurial intentions was investigated. Manifest questionnaire was distributed among Venture to the professional graduate students, graduate entrepreneurship, and small business start-educated founders in order to deduce the relationship between the entrepreneurial characteristics and the environment of entrepreneurial Intentions. Previous studies and the literature survey were carried out to support for statistics of the questionnaire. 550 answers were collected and analyzed to find that propensity for achievement, innovation, enterprising, risk taking and creativity are key factors influencing inauguration of an enterprise. We have found that among these, risk taking, creativity, and innovation are analyzed to be as a regression coefficient but enterprising a side regression coefficient. Since this study can find its limitation in that comprehensive fields of entrepreneurship were analyzed in general, the result of this study should be used with caution, until more is known about its accessibility for predicting of success or failure of Start-up Company.

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Reliability Based Pile Bearing Capacity Evaluation (신뢰도에 근거한 말뚝의 지지력 평가)

  • Lee, In-Mo;Jo, Guk-Hwan;Lee, Jeong-Hak
    • Geotechnical Engineering
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    • v.11 no.1
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    • pp.9-22
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    • 1995
  • The purpose of this study is to propose safety factors of pile bearing capacity based on the reliability analysis. Each prediction method involves various degrees of uncertainties. To account for these uncertainties in a systematic way, the ratios of the measured bearing capacity from pile load tests to the predicted bearing capacity are represented in the form of a probability density function. The safety factor for each design method is obtained so that the probability of pile foundation failure is less than 10-3. The Bayesian theorem is applied in a way that the distribution using static formulae is assumed to be the A-prior and the distribution using dynamic formulae or wave equation based methods is assumed to be the likelihood, and these two are combined to obtain the posterior which has the reduced uncertainty. The results of this study show that static formulae of the pile bearing capacity using the 5.p.7. N-value as well as dynamic formulae are highly unreliable and have to have the safety factor more than 7.4 : the wave equation analysis using PDA(Pile Driving Analyzer) system the most reliable with the safety factor close to 2.7. The safety factor could be reduced certain amount by adoption the Bayes methodology in pile design.

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A Model Curriculum Development for Clinical Nurse Specialist Training Program in Organ Transplant (장기이식 전문간호사를 위한 교육과정 연구)

  • Kim, Jung-Soon
    • The Journal of Korean Academic Society of Nursing Education
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    • v.6 no.2
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    • pp.171-185
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    • 2000
  • The twenty-first century may be said to be entering into a specialized qualification age to meet the needs of new technical innovations such as environmental changes, demographical changes, changes in the constitution of diseases, changes in the needs of the national health, reforms of information and knowledge, etc., which requires the provision of competitive services that can fulfill the high level needs of consumers. In consequence, it is needed to apply a practical nursing model that can serve as a guide for healthy society and to secure the sphere that can affect nursing policy-making by keeping pace with the changing environment. Furthermore, it is also urgent to expand more the activity sphere of nurse specialists with authority and autonomy, establish their legal foundation, establish a qualification accreditation system for nurse specialists, and develop educational programs. In Korea, the law relative to organ transplant past the national assembly on February 9, 2000, legally acknowledged brain death, which indicated to us the emergence of an age of organ transplant. Therefore, it necessitates to find out those of brain death from whom organ transplant is feasible in clinical practices, with their families' consent link to those terminal organ failure patients who are in need of an organ, and mediate both parties so that smooth transplant can be accomplished. A series of these complicated procedures require systematically trained specialists with high level techniques of organic management. With this in mind, this study was conducted on 69 clinical nurse specialists for organ transplant, accredited by the hospital, who are in active service in clinical practices. The resultant findings were revealed, as follows: 1. The qualifications of clinical nurse specialists for organ transplant should be accredited by Ministry of Health and Welfare or Korea Nurses Association. 2. The validity of qualifications should be for three years, and their renewal should be based on marks of a supplemental training or an education course for more than 12 hours a year. 3. The qualification of the clinical nurse specialist necessitates theoretical lectures and practices on those nurses who have had clinical experience in the pertinent field. 4. The course of training is required to be one year in the length of training and take more than 20 credits (320 hours) and 5 credits (240 hours).

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A Study on Performance Improvement of Fruit Vegetables Automatic Grafting System (과채류 접목시스템 개선 연구)

  • Kang, Dong Hyeon;Lee, Si Young;Kim, Jong Koo;Park, Min Jung;Son, Jin Kwan;Yun, Sung-Wook;An, Se Woong;Jung, In Kyu
    • Journal of Bio-Environment Control
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    • v.26 no.3
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    • pp.215-220
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    • 2017
  • This study was conducted to improve the insufficiency of fruit vegetable grafting system developed by National Institute of Agricultural Sciences, Rural Development Administration. When the rotary blade cut the stem of scions and rootstocks, the grafting failure at curved cutting surfaces happened. The cutting depth of a tomato seedling by a rotated cutter was calculated 0.11 mm even when the cutting arm length and the maximum stem diameter were 50 mm and 5 mm, respectively. Mathematical analysis and high-speed photography showed that there was no problem by cutting in straight the stem of scions and rootstocks. The compression test of seedling stems to design the optimal shape of gripper showed that stems were not completely restored when they were compressed above 0.8 mm and 0.6 mm in case of rootstocks and scion, respectively. This study found that the bending angle of stem of tomato seedlings at the grafting period was 10 degree on average. The optimal gripper finger was the edge finger type which could be precisely set center point by adjusting the distance between fingers. In addition, it was found that most of seedling could be grasped without damage when the finger-to-finger distances is set to 2.5 mm for scion and 3.0 mm for rootstocks and finger are coated by 1 mm-thick flexible material.

Global Market Entry Strategies of Korea-Japan Discount Stores (한.일 대형할인마트 해외진출 전략)

  • Kim, Young;Yoshimoto, Koji;Kim, Jang-Hyun;Ryu, Sung-Yong
    • Journal of Distribution Research
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    • v.15 no.5
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    • pp.195-215
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    • 2010
  • Large-scale discount stores, that were in charge of leading role up to recently, reach the limit of growth because of increasing competition, saturation of domestic market, and shortened product life-cycle. As per the limit of domestic market, large-scale discount stores are trying to various global market entry strategy and global marketing strategy like new store entry, takeover of foreign distribution chain, and global sourcing strategy. In the past, global companies of advanced country have been entering to Asian market with leading position. But, as per the rapid growth of Asian economy in the late 1980's, East Asian distribution companies like Japanese company were trying to enter the Asian market. In Asian market, starting with China, that was relatively not advanced in comparison with economic development, not only western advanced countries but also East Asian countries like Japan and Korea are entering actively for overcome their limitations of domestic market. Many of distribution companies experienced success and failure for various reason already. Korean large-scale discount stores are relatively late starters in Asian market. So, this paper purposed to review global market entry strategy of Japanese large-scale discount stores, and find out strategic implications for successful global market entry strategy of Korean large-scale discount stores.

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