• Title/Summary/Keyword: foundation failure

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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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Characteristics of Bearing Capacity for SCP Composite Ground reinforced by the Sheet piles Restraining Deformation (변위억제형 Sheet pile 설치에 따른 SCP복합지반의 지지력 특성)

  • Park, Byung-Soo
    • Journal of Navigation and Port Research
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    • v.30 no.8 s.114
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    • pp.711-719
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    • 2006
  • A series of geotechnical centrifuge model tests and numerical modelling have been performed to study engineering characteristics of the composite ground reinforced by both the Sand Compaction Piles(SCPs) and the deformation-reducing sheet piles. The research has covered several key issues such as the load-settlement relation, the stress concentration ratio and the final water content of the ground Totally three centrifuge tests have been conducted by changing configuration of the sheet piles, i.e., a test without the sheet pile, a test with the sheet pile at a single side and a test with the sheet piles at the both sides. In the model tests, a vertical load was applied in-flight on the ground surface. On the other hand, class-C type numerical modelling has been performed by using the SAGE-CRISP to compare the centrifuge test results using an elasto-plastic model for SCPs and the Modified Cam Clay model for the soft clay. It has been found that the sheet piles can restraint failure of foundation, thereby increasing yield stress of the ground. The stress concentration ratio was in the range of $2{\sim}4$. In addition, numerical analysis results showed reductions both in the ground heave($20{\sim}30%$) and in the horizontal movement($28{\sim}43%$), demonstrating the deformation-reducing effect of the sheet piles.

Analyses of Widely Used Design Codes for Pile Foundation Using the t-z Method (t-z 방법을 이용한 말뚝기초 설계기준별 비교분석)

  • Park, Sungwon;Misra, Anil
    • Journal of the Korean GEO-environmental Society
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    • v.13 no.10
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    • pp.33-42
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    • 2012
  • The efficiency of the current design methods for computing pile resistances is analyzed using field load-settlement tests results. Twelve load-settlement test data for drilled shafts and bored piles were obtained from the literature. These load-test data were fitted using the t-z method. Subsequently, the ultimate resistances were evaluated based upon the failure criteria from following methods: (1) the Davisson's approach and (2) settlement corresponding to 5% or 10% shaft diameter approach. The ultimate resistances for these drilled shafts and bored piles were also predicted using methods based on the design code from North America (United States, Canada), Europe, and Asia (Japan). The pile resistances determined from field load-settlement tests were compared with those calculated using the design codes. The comparisons show that most design codes predict a conservative resistance for drilled shafts and bored piles. However, in the case of drilled shafts, we find that some of the design codes can over-predict the resistance and, therefore, should be applied cautiously. This research also shows that the t-z method can be successfully used to predict the ultimate resistance and the load transfer mechanism for a single pile.

Behaviors of Pile Croup Installed Near Inclined Ground (경사지반에 인접하여 설치된 무리말뚝의 거동연구)

  • Chae, Kwang-Seok;Ugai, Keizo;Yoon, Gil-Lim
    • Journal of the Korean Geotechnical Society
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    • v.19 no.3
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    • pp.53-64
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    • 2003
  • Many transmission towers, high-rise buildings and bridges are constructed near steep slopes and are supported by large-diameter piles. These structures may be subjected to large lateral loads, such as violent winds and earthquakes. Widely used types of foundations for these structures are pier foundations, which have large-diameters with high stiffness. The behavior of a pier foundation subjected to lateral loads is similar to that of a short rigid pile because both elements seem to fail by rotation developing passive resistance on opposite faces above and below the rotation point, unlike the behavior of a long flexible pile. This paper describes the results of several numerical studies performed with a three-dimensional finite element method (FEM) of model tests of a laterally loaded short pile located near slopes, respectively. In this paper, the results of model tests of single piles and pile groups subjected to lateral loading, in homogeneous sand with 30$^{\circ}$ slopes and horizontal ground were analyzed by the 3-D FE analyses. The pile was assumed to be linearly elastic. The sand was assumed to have non-associative characteristics, following the MC-DP model. The failure criterion is governed by the Mohr-Coulomb equation and the plastic potential is given by the Drucker-Prager equation. The main purpose of this paper is the validation of the 3-D elasto-plastic FEM by comparisons with the experimental data.

A study on the current status and improvement suggestions of cultural heritage education in primary school Focused on curriculum analysis and teachers' cultural heritage education experiences (초등학교 문화유산 교육 현황과 방향 제언 - 교육 과정 분석 및 교사의 문화유산 교육 경험을 중심으로 -)

  • HAN, Geonsoo;KIM, Dawon
    • Korean Journal of Heritage: History & Science
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    • v.54 no.4
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    • pp.132-151
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    • 2021
  • The purpose of this study is to analyze the current status of and suggest future improvement practices for cultural heritage education in primary school. We analyzed a primary school textbook for each of five subjects (Korean, social studies, music, art, physical education), surveyed ten teachers with cultural heritage education experience, and analyzed the results. Based on the results, we made the following five suggestions: First, the goal of cultural heritage education should be expanded to foster citizenship. Second, in cultural heritage education, it is necessary to discuss what should be included in the educational content and to organize the content systematically in connection with the student environment, local community environment, and subject content. Third, cultural heritage education should be linked with sustainable development so that cultural heritage can be passed on from the present generation to future generations. Cultural heritage has characteristics, such as universal values of humanity, that transcend national boundaries, regional identities, dialogue and understanding between civilizations, and sources of creativity, and thus serves as the foundation for sustainable development. Fourth, for the effective implementation of cultural heritage education in schools, it is necessary to develop step-by-step teacher training programs. The success or failure of cultural heritage education in schools depends on teacher training. Fifth, the degree to which cultural heritage education is integrated into the curriculum should be strengthened, allowing learners to be educated so that they can cultivate knowledge and critical thinking about cultural heritage, enjoy and protect it, and connect with a sustainable society.

Enterprise Competitiveness and Corporate Performance Creation Strategies by Stage of Growth on Firm (벤처기업의 성장단계별 기업경쟁력 및 기업 성과 창출 전략)

  • Park, DaIn;Park, ChanHi
    • Asia-Pacific Journal of Business Venturing and Entrepreneurship
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    • v.13 no.6
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    • pp.177-189
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    • 2018
  • Business environment is always full of challenges. Despite various strategic efforts, there are so many failure cases of misfit. With the weaker resource base and institutional foundation, startup firms find it more difficult to find the right spot in the stiff competition. In the middle of evolutionary process, the startup firms need proper strategies meeting the differential challenges along the multiple stages of growth. Following the idea of product life cycle, this study applies the four stages of growth-startup, initial growth, accelerated growth, matured, and decliing. The next step for the startup manager is meeting each stage of growth with proper strategic efforts, including strategy, structure, decision-making pattern, and control method. When the knowledge factor is introduced, there is a potential for higher performance. Based on the 'Detailed Survey on Startup Ventures in 2017,' this study explores the impact of the government subsidy program on the firm competitiveness and performance-along the four stages of growth. In each stage, the strategy factors showed differential impact.

An Experimental Study on Reinforcement Method for Reuse of Onshore Wind Turbine Spread Footing Foundations (육상풍력터빈 확대기초의 재사용을 위한 보강방법에 관한 실험적 연구)

  • Song, Sung Hoon;Jeong, Youn Ju;Park, Min Su;Kim, Jeong Soo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.41 no.1
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    • pp.1-11
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    • 2021
  • In order to reuse existing onshore turbine foundations, it is important to redesign and reinforce the existing foundations according to the upgraded tower diameter and turbine load. In the present study, a slab extension reinforcement method and structure details of an anchorage part were examined in consideration of the reuse of spread footings, which are the most widely used foundation type in onshore wind turbine foundations. Experiments were conducted to evaluate the load resistance performance of a reinforced spread footing according to structure details of an anchorage part. The results showed that (1) the strength of an anchorage part could be increased by more than 30 % by adding reinforcement bars in the anchorage part, (2) pile-sleeves attached to an anchor ring contributed to an increase in rotational stiffness by preventing shear slip behavior between the anchor ring and the concrete, and (3) slab connectors contributed to an increase in the strength and deformation capacity by preventing the separation of new and old concrete slabs.