• Title/Summary/Keyword: impact 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.

Acceptance of Classical Text in Interdisciplinarity - A case study of Nosongchwibyoung - (학제 간 연구에서 고전 텍스트의 수용 문제 - '노송취병(老松翠屛)'을 중심으로 -)

  • Jin, Gyoung-Hwan
    • Journal of the Korean Institute of Traditional Landscape Architecture
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    • v.33 no.4
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    • pp.77-86
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    • 2015
  • The Koreanology as well as a study of the classics should start from the correct understanding of certain words or concepts. Inaccurate or even misinterpreted explanation is bound to lead to failure. If you read a classic text, if the object does not come up to indicate clearly what the bar often. Bout, are seen refer to the translation or commentary, sometimes encounter cases of very serious misunderstanding. If a simple mistake or error, and if you recognize and fix it, but eopget a big problem, described by early to conclude identified by the fact that the amount of problem becomes serious. Besides, if the trend will spread to quote it, the situation is not out of control. One sample is "Nodongchwibyeong(老松翠屛)" in "Kyoungdojapji(京都雜誌)" "Poonsock(風俗)" "Jetaek(第宅). In some places, it is called "Booyeon(附椽), it has been described elsewhere as a kind of "chwibyeong(翠屛)". This short manuscript clarified by reviewing the old literature closely, it was "songcheom", "songboong(松棚), another expression of Bungga(棚架). More precisely, it was a nickname of Hanyang Yangban in the 18th and 19th century. However, the historical research is just not as having a meaning only one explanation for the particular word. Dare to be confident that these study are meaningful. In the extremely weak division in the understanding of the original text, the cases of applying blindly without a reflection occurs frequently. This short manuscript is to give warning to recent trends. Humanities and classical field researchers made very carefully, taking into account the impact of translation and annotations, and the other branch to accommodate the research of classical humanities disciplines should try to see this information must be verified meets the facts.

Decomposition Analysis of Regional Governments in Foreign Direct Investment Increase or Decrease (우리나라 지방자치단체의 외국인직접투자 증감요인 분해 분석)

  • Lee, Sang-Chun;Kim, Yoon-Sun
    • International Commerce and Information Review
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    • v.14 no.3
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    • pp.159-183
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    • 2012
  • Promoted in places like Korea, the central government and the local governments that can provide information on which to base investment policy to attract foreign direct mutation-specific gravity model (Shift-Share Model) In this study, the decrease of foreign direct investment performance using factors looked up in the industry. The sample period of 2009, 2010, 2011 nationwide (metropolitan and non-metropolitan separated) of foreign direct investment performance for Industry Standard Industrial Classification (Division) was conducted. Factors to look at the results of the National Growth Effect(NS), the industrial structure effect (IM), local allocation effect(RS) to decrease foreign direct investment in 2010 and 2011 non-metropolitan, metropolitan national growth effect(RS) is negative(-) has a value. Because it appears to be the aftermath of the global recession, the impact on the domestic economy Metropolitan area and the Industrial Mix Effect(IM) to the development of education, culture, business, and transportation, etc. in the development of service industries than in non-metropolitan valid environment. In the sector of services (food accommodation, business services, entertainment), We did it, was able to find the function. However, the Regional Share Effect(RS) be competitive in the manufacturing sector in metropolitan areas in the metal and chemical sectors have been identified. These results seems to enhance the competitiveness of the region, such as the metropolitan area's excellent workforce. Shift-Share analysis technique based on competitive factors of the region, to find the failure has limitations.

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Development of Green Cement Type Grouting Materials with High Toughness and Non-Shrinkage Including Powder of Waste Tire and Resin (분말 폐타이어와 분말 수지를 함유한 환경친화적 고인성 시멘트계 무수축 그라우트재의 개발)

  • Park, Seok-Kyun
    • Journal of the Korea Concrete Institute
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    • v.19 no.5
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    • pp.623-630
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    • 2007
  • Grouting materials are used for the unification of superstructural and substructural body like bridge seat (shoe) or machinery pedestal and e.t.c by filling their intercalary voids. Accordingly, grouting materials have been developed and used mainly with products of high strength because those materials are constructed specially in a part receiving large or impact load. In this situation, the structural body constructed by grouting materials with high stiffness-centered (caused by high strength) products is apt to cause brittle failure when receiving over a limit stress and to cause cracks according to cumulative fatigue by continuous and cyclic load. In addition, grouting materials are apt to cause cracks by using too much rapid hardening agents that give rise to high heat of hydration to maintain high strength at early age. In this study, to overcome these problems, cement type grouting materials including powder of waste tire and resin as elastic materials which aim to be more stable construction and to be improvement of mother-body's unification are developed and endowed with properties of high toughness and high durability add to existing properties of high flowability, non-shrinkage and high strength. Besides, this study contribute to of for green construction materials for being possible recycling industrial waste like waste tire and flyash. On the whole, seven type mixing conditions are tested and investigated to choose the best mixing condition.

A Study on the Design Improvement to prevent the stoppage phenomenon of Launch Support Device for Self-Propelled Artillery (자주포용 발사지지대의 멈춤현상 방지를 위한 설계개선 연구)

  • Kim, Sung Hoon;Park, Young Min;Noh, Sang Wan;Park, Dae Hoon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.5
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    • pp.443-450
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    • 2020
  • This paper reports a design improvement study to solve the stoppage phenomenon caused by the launch-support device applied to K105A1. The K105A1 is a weapon system equipped with an old 105 mm towed howitzer in a wheeled vehicle, which provides superior maneuverability compared to track equipment. The launch support device serves to withstand fire impact and load. In this way, this device is fixed firmly to the ground in preparation for the shooting mission and is responsible for the critical performance, such as fixing the position of the vehicle. On the other hand, during the field test, a temporary stoppage of the launch support occurred, which caused a problem of not being fixed to the ground. To solve this problem, the cause of failure was analyzed by a replay test and parts inspection. In addition, the operating concept, method, and design were analyzed to derive the cause and solve the problem by changing the parts design. Finally, the performance and firing missions were performed normally by applying the changed design to K105A1. The performance stability and reliability of the launch support device were confirmed, which are expected to be of great assistance in the development of military equipment in the future.

A prospective study on early English education and Korean children's English proficiency: When cognitive, personality and parental factors are controlled (조기영어학습이 유아의 영어능력에 미치는 영향: 인지, 성격, 부모요인을 통제한 전향적 연구)

  • Kim, Geunyoung;Kim, Yoo Ree;Park, Hyekyung;Kim, Gahee
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.11
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    • pp.552-562
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    • 2016
  • Although a number of studies have been conducted in Korea since 2000 on the impact of early English education, their interpretation is still not conclusive, due to their lack of control groups and failure to control for third factors and use valid measurements. The present study was designed to examine the effect of an English education program on young children's English proficiency after 8 months using the most well-known official English proficiency measure, the WIDA for kindergarteners. In addition, the children's Korean language proficiency, cognitive abilities, personality, parents' SES, and parents' attitudinal variables before the education were measured and controlled. The results indicated that the intervention group performed better than the control group in both listening and speaking skills, even when all relevant factors were considered. This effect, however, was only found in the item-level analyses.

Epidemiological Observation on Recent Outbreaks of Canine Distemper in Korea (최근 국내발병 개 디스템퍼에 대한 역학적 조사)

  • Doo, Kim;Ji-young, Park;So-jeo, Ahn;Seok-young, Jeoung;Son-il, Pak
    • Journal of Veterinary Clinics
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    • v.21 no.3
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    • pp.229-235
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    • 2004
  • To characterize the recent outbreaks of canine distemper (CD) in Korea, we carried out epidemiological investigations by clinical observations, serum neutralizing (SN) antibody titer determination and RT-PCR on the 315 dogs which were clinically suspected as canine distemper virus (CDV) infection. One hundred and sixty two of 315 dogs were infected with CDV. Breed or gender did not seem to have effects on the prevalence of CD. The major part of dogs were in young age from 6 weeks to 18 weeks of age, and were not vaccinated or incompletely vaccinated. Clinical signs of dogs with CD were multi systemic and extremely variable. Dogs died from CD had significantly more ocular signs and neurologic signs than those of dogs survived (p<0.05). The SN titers against CDV of 157 (96.9%) dogs were under 1:16, which is less than protective level. One possible explanation for recent outbreaks of CD in Korea might be low antibody titers against CDV because of vaccination failure. Therefore, to reduce the impact of virulent infection in the dog population, dogs should be vaccinated adequately and prophylactic measures should include isolation of young dogs from the dog population until vaccination can be expected to provide protection.

Impact Assessment of Climate Change on Extreme Rainfall and I-D-F Analysis (기후변화가 극한강우와 I-D-F 분석에 미치는 영향 평가)

  • Kim, Byung-Sik;Kim, Bo-Kyung;Kyung, Min-Soo;Kim, Hung-Soo
    • Journal of Korea Water Resources Association
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    • v.41 no.4
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    • pp.379-394
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    • 2008
  • Recently, extreme precipitation events beyond design capacity of hydraulic system have been occurred and this is the causes of failure of hydraulic structure for flood prevention and of severe flood damage. Therefore it is very important to understand temporal and spatial characteristics of extreme precipitation events as well as expected changes in extreme precipitation events and distributional characteristics during design period under future climate change. In this paper, climate change scenarios were used to assess the impacts of future climate change on extreme precipitation. Furthermore, analysis of future extreme precipitation characteristics and I-D-F analysis were carried out. This study used SRES B2 greenhouse gas scenario and YONU CGCM to simulate climatic conditions from 2031 to 2050 and statistical downscaling method was applied to establish weather data from each of observation sites operated by the Korean Meteorological Administration. Then quantile mapping of bias correction methods was carried out by comparing the simulated data with observations for bias correction. In addition Modified Bartlett Lewis Rectangular Pulse(MBLRP) model (Onof and Wheater, 1993; Onof 2000) and adjust method were applied to transform daily precipitation time series data into hourly time series data. Finally, rainfall intensity, duration, and frequency were calculated to draw I-D-F curve. Although there are 66 observation sites in Korea, we consider here the results from only Seoul, Daegu, Jeonju, and Gwangju sites in this paper. From the results we found that the rainfall intensity will be increased and the bigger intensity will be occurred for longer rainfall duration when we compare the climate conditions of 2030s with present conditions.

Data-driven event detection method for efficient management and recovery of water distribution system man-made disasters (상수도관망 재난관리 및 복구를 위한 데이터기반 이상탐지 방법론 개발)

  • Jung, Donghwi;Ahn, Jaehyun
    • Journal of Korea Water Resources Association
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    • v.51 no.8
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    • pp.703-711
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    • 2018
  • Water distribution system (WDS) pipe bursts are caused from excessive pressure, pipe aging, and ground shift from temperature change and earthquake. Prompt detection of and response to the failure event help prevent large-scale service interruption and catastrophic sinkhole generation. To that end, this study proposes a improved Western Electric Company (WECO) method to improve the detection effectiveness and efficiency of the original WECO method. The original WECO method is an univariate Statistical Process Control (SPC) technique used for identifying any non-random patterns in system output data. The improved WECO method multiples a threshold modifier (w) to each threshold of WECO sub-rules in order to control the sensitivity of anomaly detection in a water distribution network of interest. The Austin network was used to demonstrated the proposed method in which normal random and abnormal pipe flow data were generated. The best w value was identified from a sensitivity analysis, and the impact of measurement frequency (dt = 5, 10, 15 min etc.) was also investigated. The proposed method was compared to the original WECO method with respect to detection probability, false alarm rate, and averaged detection time. Finally, this study provides a set of guidelines on the use of the WECO method for real-life WDS pipe burst detection.

Seismic Behaviour of Exterior Joints in Post-Tensioned Flat Plate Systems (포스트 텐션 플랫 플레이트 외부 접합부의 내진 거동)

  • Han, Sang-Whan;Kee, Seong-Hoon;Kang, Tomas H.K.;Cho, Jong;Lee, Li-Hyung
    • Journal of the Korea Concrete Institute
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    • v.18 no.5 s.95
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    • pp.595-602
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    • 2006
  • An experimental study was conducted to investigate seismic behaviour of post-tensioned(PT) exterior slab-column connections used for the purpose to resist gravity loads only. For these, 2/3-scale, two PT post-tensioned exterior connections with two different tendon arrangement patterns and one conventional reinforced concrete(RC) exterior connection was tested under quasi-static, uni-directional reversed cyclic loading. During the lateral testing, gravity forces transferred to the column were kept constant to closely simulate a moment to shear ratio of a real building. One of the objectives of this study was to assess the necessity and/or the quantity of bottom bonded reinforcement needed to resist moment reversal which would occur under significant inelastic deformations of the adjacent lateral force resisting systems. The ACI 318 and 352 provisions for structural integrity were applied to provide the bottom reinforcement passing through the column for the specimens. Prior test results were also collected to conduct comparative studies for some design parameters such as the tendon arrangement pattern, the effect of post-tensioning forces and the use of bottom bonded reinforcement. Consequently, the impact of tendon arrangement on the seismic performance of the PT connection, that is lateral drift capacity and ductility, dissipated energy and failure mechanism, was considerable. Moreover, test results showed that the amount of bottom reinforcement specified by ACI 352. 1R-89 was sufficient for resisting positive moments arising from moment reversal under reversed cyclic loads. Shear strength of the tested specimens was more accurately predicted by the shear strength equation(ACI 318) considering the average compressive stress over the concrete($f_{pc}$) due to post-tensioning forces than that without considering $f_{pc}$.