• Title/Summary/Keyword: depth test

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An Experimental Study on the Flexural Performance of Modular Slab Connections with Loop Joints (루프이음을 가진 모듈식 슬래브 연결부의 휨성능에 관한 실험적 연구)

  • Kim, Dong-Woan;Shin, Jeong Ryol
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.1
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    • pp.459-467
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    • 2016
  • Recently, new open-cut modular construction method, which is built within a 5~7m depth below the road, was proposed for the near-surface transit system to ensure the economic feasibility of underground structures. In this paper, the precast modular construction method was developed for the low-cost and rapid construction of underground structures. For the experiment on the flexural performance of the modular slab connections, a total of eleven specimens were fabricated according to the test variables; section shape, joint type, lap length, and transverse reinforcement. The test results were compared with those of the specimens without loop joints. To verify the performance of the slab connections, the 4-point loading tests of precast RC members with loop joints were conducted. As a result of the test, the flexural performance of the half-depth specimens with a 200mm lap length of loop joints were confirmed to be similar to those of the specimens without joints.

A Fundamental Study on the Pullout Strength Equation of High Strength Anchor for Asphalt Pavement (아스팔트용 고강도 앵커시스템의 인발강도식 검토에 관한 기초적 연구)

  • Choi, Jaemin;Lee, Seungyong;Sung, Kitae;Han, Youngdoo
    • Journal of the Society of Disaster Information
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    • v.13 no.3
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    • pp.313-321
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    • 2017
  • In order to investigate the basic performance of the high strength anchor for asphalt road subjected to tensile load, the static pullout test was carried out and the pullout strength of the asphalt anchor was analyzed. In the pullout test, the depth of anchor, depth of pavement, diameter of anchor, type of anchor, experimental temperature, epoxy type and amount of anchor were used as test variables. As a result, the steel strength of asphalt anchor was 1.08 times higher than that of conventional concrete anchor, therefore it is considered appropriate to use the steel strength formula of concrete anchor for asphalt anchor. Compared with the proposed formula, the pullout load obtained from the test of the asphalt anchor was within ${\pm}10%$. The ratio of the projected area of the asphalt anchor is similar as that of the concrete anchor.

Analysis on Effect of Debris Flow Energy Mitigation by Arrangement of Cylindrical Countermeasures (원통형 토석류 대책구조물의 배치조건에 따른 에너지 저감효과 분석)

  • Kim, Beomjun;Cho, Heungseok;Han, Kwangdo;Choi, Clarence E.;Yune, Chanyoung
    • Journal of the Korean GEO-environmental Society
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    • v.20 no.10
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    • pp.15-27
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    • 2019
  • In this study, in order to analyze the effect of cylindrical baffles on the debris flow energy, small-scale tests were conducted using a flume with cylindrical baffles. Various row numbers of installed baffles were considered as a test condition. To investigate the scale effect of debris flow and cylindrical baffles on flow characteristics, large-scale tests were also performed according to varying row numbers of baffle for same baffle configuration with small-scale tests. Both small- and large-scale test results showed that the increase of row number of baffle increase the energy dissipation effect due to reduction of the velocity and flow depth of debris flow.

A Study on the p-y Curves by Small-Scale Model Tests (모형실험을 통한 말뚝의 p-y 곡선에 관한 연구)

  • Kim, Tae-Sik;Jeong, Sang-Seom;Kim, Young-Ho
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.1C
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    • pp.41-51
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    • 2008
  • The load distribution and deformation of single piles which is embedded in Jumunjin sand and Kimhae clay are investigated, based on small scale model tests. Special attention is given to the consideration of flexural rigidity in laterally loaded piles. To consider the flexural rigidity of the pile, tests are performed with the aluminium piles of three different length under different relative densities and undrained shear strength. The test results indicate that the initial slope from the results of tests is proportional to the depth and pile-soil rigidity in both soils. But the increasing rate of the initial slope in the clay is less than in the sand. In addition, the soil resistance is more related to the depth and soil condition than the pile rigidity. Base on the test results, an empirical formula is proposed, which is good agreement with previously published small scale model test and field lateral load test.

An In-depth Analysis of Head-on Collision Accidents for Frontal Crash Tests of Automated Driving Vehicles (자율주행자동차 정면충돌평가방안 마련을 위한 국내 정면충돌사고 심층분석 연구)

  • Yohan Park;Wonpil Park;Seungki Kim
    • Journal of Auto-vehicle Safety Association
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    • v.15 no.4
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    • pp.88-94
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    • 2023
  • The seating postures of passengers in the automated driving vehicle are possible in atypical forms such as rear-facing and lying down. It is necessary to improve devices such as airbags and seat belts to protect occupants from injury in accidents of the automated driving vehicle, and collision safety evaluation tests must be newly developed. The purpose of this study is to define representative types of head-on collision accidents to develop collision standards for autonomous vehicles that take into account changes in driving behavior and occupants' postures. 150 frontal collision cases remained by filtering (accident videos, images, AIS 2+, passenger car, etc…) and random sampling from approximately 320,000 accidents claimed by a major insurance company over the past 5 years. The most frequent accident type is a head-on collision between a vehicle going straight and a vehicle turning left from the opposite side, accounting for 54.7% of all accidents, and most of these accidents occur in permissive left turns. The next most common frontal collision is the center-lane violation by drowsy driving and careless driving, accounting for 21.3% of the total. For the two types above, data such as vehicle speed, contact point/area, and PDOF at the moment of impact are obtained through accident reconstruction using PC-Crash. As a result, two types of autonomous vehicle crash safety test scenarios are proposed: (1) a frontal oblique collision test based on the accident types between a straight vehicle and a left-turning vehicle, and (2) a small overlap collision test based on the head-on accidents of center-lane violation.

A Study on the Verification of an Indoor Test of a Portable Penetration Meter Using the Cone Penetration Test Method (자유낙하 콘관입시험법을 활용한 휴대용 다짐도 측정기의 실내시험을 통한 검증 연구)

  • Park, Geoun Hyun;Yang, An Seung
    • Journal of the Korean GEO-environmental Society
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    • v.20 no.2
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    • pp.41-48
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    • 2019
  • Soil compaction is one of the most important activities in the area of civil works, including road construction, airport construction, port construction and backfilling construction of structures. Soil compaction, particularly in road construction, can be categorized into subgrade compaction and roadbed compaction, and is significant work that when done poorly can serve as a factor causing poor construction due to a lack of compaction. Currently, there are many different types of compaction tests, and the plate bearing test and the unit weight of soil test based on the sand cone method are commonly used to measure the degree of compaction, but many other methods are under development as it is difficult to secure economic efficiency. For the purpose of this research, a portable penetration meter called the Free-Fall Penetration Test (FFPT) was developed and manufactured. In this study, a homogeneous sample was obtained from the construction site and soil was classified through a sieve analysis test in order to perform grain size analysis and a specific gravity test for an indoor test. The principle of FFPT is that the penetration needle installed at the tip of an object put into free fall using gravity is used to measure the depth of penetration into the road surface after subgrade or roadbed compaction has been completed; the degree of compaction is obtained through the unit weight of soil test according to the sand cone method and the relationship between the degree of compaction and the depth of the penetration needle is verified. The maximum allowable grain size of soil is 2.36 mm. For $A_1$ compaction, a trend line was developed using the result of the test performed from a drop height of 10 cm, and coefficient of determination of the trend line was $R^2=0.8677$, while for $D_2$ compaction, coefficient of determination of the trend line was $R^2=0.9815$ when testing at a drop height of 20 cm. Free fall test was carried out with the drop height adjusted from 10 cm to 50 cm at increments of 10 cm. This study intends to compare and analyze the correlation between the degree of compaction obtained from the unit weight of soil test based on the sand cone method and the depth of penetration of the penetration needle obtained from the FFPT meter. As such, it is expected that a portable penetration tester will make it easy to test the degree of compaction at many construction sites, and will lead to a reduction in time, equipment, and manpower which are the disadvantages of the current degree of compaction test, ultimately contributing to accurate and simple measurements of the degree of compaction as well as greater economic feasibility.

A Study on effectiveness of the relapse prevention program for adult substances abusers (성인 약물남용 재활 프로그램의 효과성 연구)

  • 장진경
    • Journal of Families and Better Life
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    • v.19 no.1
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    • pp.33-52
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    • 2001
  • The purpose of this study was to examine the effectiveness of using the relapse prevention program for adult substance addicts. Based on the results from the study of educational needs for the relapse prevention program among substance addicts the 10-session-relapse prevention program was developed. Then the researcher conducted the relapse prevention program for 15 adult methamphetamine addicts from Aug. 3 1999 to Sep. 4 1999 at the probation office in Suwon, South Korea. For examining the effectiveness of using that relapse prevention program the Social Adjustment Scale-Self Report(SAS-SR), McMullin Addiction Thought Scale(MAT), and Self Esteem Rating Scale(SERS) were used whether or not their social adjustment level, self-esteem level, and addiction thought level were improved. This study employed one group pre-post test research design as a quantitative purpose and in-depth interview as a qualitative purpose. For a qualitative purpose in-depth interview was conducted in not only between sessions but also after sessions dealing with their current life problems. For a quantitative purpose the analysis strategy employed here was frequency and t-test. Results shows that addicts who took the relapse prevention program consistently reported the improvement of their social adjustment level, self-esteem level, and addiction thought level although there were no statistically significant between pre and post tests. The implication of study findings will be discussed.

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An Experimental Study on the Behavior of Open-ended Pipe Piles Ggroup to the Simulated Seaquake (해진시 개단무리말뚝의 거동에 관한 모형실험 연구)

  • 남문석;최용규;김재현
    • Proceedings of the Korean Geotechical Society Conference
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    • 1999.03a
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    • pp.447-454
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    • 1999
  • The compressive capacity and the soil plugging resistance of single open-ended pipe pile were completely decreased in the previous study on the behavior of shorter single pile during simulated seaquake induced by the vertical component of earthquake. But the capacity of single open-ended pipe pile with greater penetration and the capacity of piles group with shorter penetration were expected to be stable after seaquake motion. In this study, first, 2-piles or 4-piles are driven into the calibration chamber included in saturated fine medium sand with several simulated penetrations, and the compressive load test for each piles group was performed. Then, about 95 % compressive load of the ultimate capacity was applied on the pile head during the simulated seaquake motion. Finally, In confirm the reduction of pile capacity during the simulated seaquake motion, the compressive load test for each single pile or piles group after seaquake motion was performed. During the simulated seaquake, the compressive capacity of open-ended pipe piles with greater penetration ( 〉about 27 m) was not degraded even in deep sea deeper than 220 m and soil plug within open-ended pipe pile installed in deep sea was stable after seaquake motion. Also, in the case of 2-piles or 4-pile groups, the compressive capacity after seaquake motion was not degraded at all regardless of pile penetration depth beneath seabed, sea water depth and seaquake frequency.

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Shear strength of reinforced concrete dapped-end beams

  • Lin, Ing-Jaung;Hwang, Shyh-Jiann;Lu, Wen-Yao;Tsai, Jiunn-Tyng
    • Structural Engineering and Mechanics
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    • v.16 no.3
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    • pp.275-294
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    • 2003
  • In this study, 24 high-strength concrete dapped-end beams were tested to study the effects of the amount of main dapped-end reinforcement, the nominal shear span-to-depth ratio, and the concrete strength on the shear strength of dapped-end beams. Test results indicate that the shear strength of dapped ends increases with the increase in the amount of main dapped-end reinforcement and the concrete strength. The shear strength of dapped-end beam increases with the decrease of nominal shear span-to-depth ratio. A simplified method for determining the shear strength of reinforced concrete dapped ends is also proposed in this paper. The shear strengths predicted by the proposed method and the approach of PCI Design Handbook are compared with test results. The comparison shows that the proposed method can more accurately predict the shear strength of reinforced concrete dapped-end beams than the approach of PCI Design Handbook.

Development of a Measurement of Stress for Hospitalized Schizophrenic Patient (조현병 환자의 입원 스트레스 측정도구 개발)

  • Park, Sun Ah;Sung, Kyung Mi
    • Journal of Korean Academy of Nursing
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    • v.44 no.3
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    • pp.339-349
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    • 2014
  • Purpose: This study was done to develop a measurement for stress experienced by patients with schizophrenia during hospitalization. Methods: The preliminary tool was developed through in-depth interviews and a validity verification test of content. For data collection, 15 inpatients with schizophrenia were selected as participants for in-depth interviews and 195 patients admitted to one of eight psychiatric hospitals in four provinces were recruited as participants to test reliability and validity of the preliminary tool. Results: The questionnaire was developed as a four-point Likert-type scale in a self-report form with 28 items. Factor analysis showed 28 items in six factors. Factors were named 'Unjust human rights infringement', 'Futureless life', 'Alienation from other family members', 'Infringement of basic needs', 'Infringement of personal preference' and 'Inconvenience of shared living'. The six factors explained 63.5% of the total variance. Cronbach's alpha for the total items was .93 and for the factors ranged from .65 to .87. Conclusion: A tool to measure stress in patients hospitalized with schizophrenic was developed based on identified hospitalization stress experiences. Study results indicate that this tool can be used to evaluate hospitalization stress in these patients and will contribute to establishing nursing interventions for relief of hospitalization stress.