• Title/Summary/Keyword: 조기파괴

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Behavior of Precast Concrete Shear Walls with C-Type Connections (C형 접합부를 이용한 프리캐스트 콘크리트 전단벽의 거동)

  • Lim, Woo-Young;Hong, Sung-Gul
    • Journal of the Korea Concrete Institute
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    • v.22 no.4
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    • pp.461-472
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    • 2010
  • This paper investigates the behavior of precast concrete (PC) shear walls with a new vertical connections for a fast remodeling construction. The C-type vertical connections for the PC wall systems are proposed for transfer of bending moment between top and bottom walls in the vertical direction while a shear key in the center of wall is prepared to transfer shear forces by bearing action. The proposed vertical connections allows easy fabrication thanks to slots at the edges of wall in opposite directions. The plane PC wall systems subject to lateral load are compared with ordinary wall systems by investigating the effects of connection on the stiffness, strength, ductility, and failure modes of whole systems. The load-displacement relationship and influence of premature failure of connections are examined. The experimental test showed that the longitudinal reinforcing steel bars placed at the edges of walls yielded first and the ultimate deformation were terminated due to premature failure of connections. The diagonal reinforcements for efficient shear transfer in the walls were not effective. The strength and deformation obtained through the section analysis were generally in agreement with the experimental data, and indicated that. Gap opening contributed to the deformation behavior more than any other factors.

Epithelial origin의 악성종양

  • Go, Gwang-Jun
    • The Journal of the Korean dental association
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    • v.27 no.8 s.243
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    • pp.697-702
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    • 1989
  • 악성종양은 상피성의 암종(carcinoma)과 결체직성의 육종(sarcoma)으로 분류된다. 최근 암환자의 발생은 점차 증가되는 추세이며, 우리나라에서도 사망원인 중 뇌졸증 다음으로 암이 차지하는 비율이 높다. 이러한 암은 침윤성(infiltrative)인 성장으로 인하여 인접 정상조직을 급격히 파괴시키며, 해당 임파절을 따라 신체 다른 부위로 전이(metastasis)된다. 임파절에 전이되기 전에 조기발견된 암은 70%의 5년 생존률을 보이는 반면, 임파절에 전이된 후에 발견된 암은 30%의 5년 생존률을 보인다. 따라서 암의 성공적인 치료를 위해서는 이의 조기발견이 매우 중요하다고 할수 있다. 그러나 불행하게도 많은 환자가 이미 병소가 상당히 진행된 상태에서 내원하기 때문에 이의 근치가 어려우며, 예후 또한 좋지 않다. 이러한 암을 조기발견하기 위해서는 환자 자신의 관심뿐만 아니라 치과의사의 세심한 검진이 필요하리라 생각된다.

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원자력 발전시설에서의 조기경보용 연기감지

  • Yu, Hyeon-Jong
    • 방재와보험
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    • s.108
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    • pp.47-51
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    • 2005
  • 원전에서의 화재사고는 사람은 물론 주변 환경에도 막대한 영향과 피해를 가져오는 파괴적 재난이 될 수 있다. 오늘날 원자력 발전소를 위한 화재안전 프로그램들은 화재 발생 확률과 피해를 최소화하는 것을 우선 과제로 삼고 있는 실정이다. 따라서 어떠한 화재라도 안전작동 차단기능을 방해하지 않으며, 원전 주위에 방사능 유포 위험을 늘리지 않는다는 것을 목표로 화재안전 프로그램이 운영되고 작동중인 원자로의 넓은 적용 범위에서 초기 탐지능력을 강화하는 것이 중요하다고 할 수 있다.

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Rip-off Failure Mechanism of Reinforced Concrete Beams Strengthened with CFRP Plate (CFRP로 성능향상된 철근콘크리트 보의 Rip-off 파괴메커니즘 고찰)

  • Sim Jong-Sung;Moon Do-Young;Park Cheol-Woo;Park Sung-Jae;Choi Kwang-Min
    • Journal of the Korea Concrete Institute
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    • v.17 no.6 s.90
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    • pp.993-1000
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    • 2005
  • Various types of FRP materials have been applied for structural strengthening of RC beams in various forms. When CFRP plates are used, a premature failure used to occur before enough strengthening effect appears. This is primarily due to the rip-off of CFRP Plate attached on RC beams. Despite of numerous studies on the rip-off failure of externally strengthened RC beams, its failure mechanism is not definitely clarified yet. Investigations from literatures have shown that the rip-off failure is dependant on the vertical and shear stresses at the level of main reinforcements in RC beams. This study suggests an analytical model to Investigate the rip-off failure load based on the stress states at the level of main reinforcements. The proposed model is relatively simple and produces very comparable results to the test data. It is believed that the proposed model can be successfully used to provide more information on the rip-off failure mechanisms and its prevention.

Fracture Characteristics of RC Beams Reinforced with GFSP (유리섬유-강 복합판으로 보강된 RC 보의 파괴 특성)

  • Kim, Chung Ho;Jang, Hee Suk;Ko, Sin Woong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.11 no.5
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    • pp.153-159
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    • 2007
  • This paper is experimental investigation for failure characteristics and performance of a RC beams strengthened with GFSP which were developed for improvement of the early debonding problems in the externally bonded FRP systems. To represent damages and load conditions of the existing beam, pre-cracks and repeating loads are adopted for experimental parameters. In this experiment, it is confirmed that strengthening with GFSP is a very effective strengthening method for an increase in strength, a decrease in deflection, a control of the crack. But it shown that the design of the beams to be strengthened with GFSP should be consider a brittle behavior of the grass fiber on the flexural capacity.

Development of acoustic emission monitoring system for the safety of geotechnical structures (지반구조물 안전감시용 미소파괴음 계측시스템 개발)

  • Cheon, D.S.;Jung, Y.B.;Park, E.S.
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.16 no.5
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    • pp.471-485
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    • 2014
  • The monitoring method of geotechnical structures using acoustic emission(AE) and microseismicity(MS) is to detect the microscopic deformation and fracture behavior in the inner structures by measuring induced acoustics and vibrations. It can identify a pre-indication of failure by taking advantage of the characteristics that the amount and occurrence rates of AE and MS increase rapidly prior to large scale destruction of the target structures. The monitoring system consisting of high-quality sensors, high-speed data acquisition device and the operation program is required for the practical application of this method. Recently, the AE and MS monitoring systems have been localized. In particular, the developed operation software which can analyze and interpret the measured signals was demonstrated through a number of applications to domestic fields. This report introduces the configuration and features of developed monitoring system, then the challenges and future direction of AE monitoring in geotechnical structures are discussed.

Nerve Blocks of Cancer Pain in Palliative Care (암성 통증에 대한 신경블록요법)

  • Yoon, Duck-Mi
    • Journal of Hospice and Palliative Care
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    • v.12 no.2
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    • pp.56-60
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    • 2009
  • More than 80% of cancer-related pain is pharmacologically controllable, whereas $10{\sim}20%$ of patients require interventional treatments. Neurolytic nerve block can play a major role in cancer pain treatment, and it has been proposed to prevent the development of pain and improve the quality of life of patients with cancer. If the pain is well localized and restricted to certain peripheral parts of the body, spinal peripheral or sympathetic nerve blocks may result in excellent therapeutic effects. Neurolytic sympathetic block, especially Celiac plexsus block (CPB) performed in earlier stages, is effective with successful long term results. However, selection of patients is critical for succeful outcomes. Neurolytic plexus block significantly improves the quality of life of patients and reduces abdominal and pelvic cancer pain, analgesic consumption and adverse opioids-related side effects. Interventional pain management should be considered at earlier stages to provide patients with the best quality of life possible.

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STABLIZATION OF THE EARLY ERUPTED FIRST PREMOLAR WITH FIXED APPLIANCE (고정식 장치를 이용한 조기 맹출 소구치의 안정화)

  • Hwang, JI-Won;Kim, Seong-Oh;Choi, Hyung-Jun;Choi, Byung-Jai;Son, Heung-Kyu;Lee, Jae-Ho
    • Journal of the korean academy of Pediatric Dentistry
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    • v.38 no.1
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    • pp.62-67
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    • 2011
  • Early eruption refers to an accelerated eruption of a tooth beyond the normal eruption period. The clinical findings of an early erupted tooth with little formation of crown and/or root include severe mobility, pain on chewing, hypocalcification of the enamel, and inclination, displacement, and rotation of the tooth. The radiographic findings include underdeveloped root and insufficient bone support. Early eruption of a permanent tooth can cause several complications such as chronic trauma, pain, edema, an increased rate of premolar impaction and tooth displacement and/or rotation. Therefore, when a permanent tooth erupts earlier than its normal eruption period with accompanying symptoms, appropriate treatments should be done as soon as possible. A female patient of age 7 without any systemic disease was referred from a local dental clinic with chief complaint of severe mobilities and pain in both upper first premolars. According to the clinical and radiographic examinations, the permanent teeth erupted earlier with barely formed roots, severe mobilities, edema, and pain. This case is to report the successful accomplishment of root formations and stabilization of teeth after applying intraoral fixed appliances using bands and spurs for 14 months.

Suggestion for Non-Destructive Testing Equation to Estimate Compressive Strength of Early Strength Concrete (조기강도 콘크리트의 압축강도 추정을 위한 비파괴검사 실험식의 제안)

  • Lee, Tae-Gyu;Kang, Yeon-Woo;Choi, Hyeong-Gil;Choe, Gyeong-Choel;Kim, Gyu-Yong
    • Journal of the Korea Institute of Building Construction
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    • v.16 no.3
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    • pp.229-235
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    • 2016
  • In construction field, it used various technique for concrete formwork. Part of them, non-destructive test has been conducted to estimate a compressive strength of concrete easily such as rebound method and ultrasonic pulse velocity method etc. Former research has recommend proposed equation based on experimental data to investigate strength of concrete but it was sometimes deferent actual value of that from in field because of the few of data in case of early strength concrete. In this study, an experiment was conducted to analyze strength properties for early strength concrete using cylinder mold and $1,000mm{\times}1,000mm{\times}200mm$ rectangular specimen. And compressive strength of concrete was tested by non-destructive test, and calculated by the equation proposed former research. As a result, the non-destructive test results showed approximately 70 percent of the failure test value for all conditions, and worse reliability was obtained for high strength concrete samples when the ultrasonic pulse velocity method was used. Based on the scope of this study, the experimental equation for estimating compressive strength of early strength concrete from 24MPa to 60MPa was proposed.