• Title/Summary/Keyword: 안정계수

Search Result 18, Processing Time 0.133 seconds

Experimental Study on Hydraulic Characteristics of Wave Dissipating Modified- Tribar (Modified- Tribar의 수리특성에 관한 실험적 연구)

  • KIM IN-CHUL;PARK YOUNG-WOO;KWEON HYUCK-MIN
    • Journal of Ocean Engineering and Technology
    • /
    • v.18 no.4
    • /
    • pp.23-32
    • /
    • 2004
  • Specially shaped concrete blocks are used for the armor layer of rubble structure for breakers, seawalls, or other shore protection work. In this study, the hydraulic characteristics of the Modified-Tribar(MTB), which addresses the shortcomings of the Arch-Tribar, and the most widely used Tetrapod(TTP) in Korea are examined through hydraulic model tests. The MTB are much more stable than the TTP, as shown through the stability model tests under non-breaking and non-overtopping condition. The value of the stability coefficient(KD) was obtained at around 30. The model tests show that the TTP random two layers and MTB uniform 1.5 layers have similar effects, but the MTB one layer shows slightly low effects in dissipating wave energy. The TTP random two layer model is the most effective in reducing wave overtopping rate, under overtopping condition, while the MTB uniform one layer and the MTB uniform 1.5 layer models follow respectively.

Evaluation for Lateral Movements of Bridge Abutment on Soft Ground (연약지반상 교대측방이동에 대한 판정)

  • 홍원표;송영석;조용량
    • Journal of the Korean Geotechnical Society
    • /
    • v.17 no.4
    • /
    • pp.269-278
    • /
    • 2001
  • 국내 30개의 교대측방이동 사례현장에 대하여 교대기초말뚝의 사면안정효과와 교대의 실측측방변위를 고려한 사면안정해석을 실시하였다. 해석결과 사면안전율은 말뚝의 효과를 무시한 경우 1.5이상, 말뚤의 효과를 고려한 경우 1.8이상 되어야 안전함을 알 수 있다. 그리고, 교대의 실측측방변위와 사면안전율과의 상관관계로부터 교대의 허용측방변위 설계기준은 5cm보다 1.5cm로 함이 더 합리적임을 알 수 있다. 사면안정해석결과와 교대의 실측측방변위를 토대로 기존에 제안된 교대측방이동 판정기준의 국내 적용여부를 검토한다. 이를 위하여 교대의 사면안정해석결과 및 실측측방변위와 교대측방이동 관련지수와의 상관관계를 조사한다. 그 결과 실측된 교대의 측방변위와 이를 고려한 사면안전율은 교대의 측방유동지수, 측방이동판정지수 및 지반의 안정계수와 무관한 경우도 많이 존재하는 것으로 나타났다. 이는 결국 이들 경험적인 지수만으로 교대측방이동을 판정하는 것은 불충분함을 의미한다. 따라서, 교대측방이동을 판정할 경우에는 반드시 교대의 측방변위를 고려한 사면안정해석이 실시되어야 한다.

  • PDF

A Study on Hydrophilic Protection Block Development for Reduction of coastal disaster (연안재해 저감을 위한 친수형 호안 블록개발에 관한 연구)

  • Kim, Jong-Gil
    • Journal of Digital Convergence
    • /
    • v.15 no.3
    • /
    • pp.211-219
    • /
    • 2017
  • Among government projects for reduction of coastal disaster, coastal maintenance project stage 1(2000~2009) and stage 2(2010~2019) to reduce coastal erosion and sedimentation are currently under process. In performing the coastal maintenance projects, it is necessary to install artificial concrete armor units for coastal protection. Presently in Korea, products manufactured in Japan are applied to the site, or blocks self-developed by the construction firms are installed. However, there is a lack of technical reviews such as verification of hydraulic characteristics, securing the stability and design techniques. This study is intended to develop waterfront shore protection blocks with good accessibility of people and excellent coastal disaster reduction and protection capability. Through this study, hydraulic characteristics and stability coefficients of shore protection blocks could be drawn.

Experiments for Amour Stability of Low Crested Structure Covered by Tetrapods (저 마루높이 구조물의 피복재 안정성 실험: Tetrapod 피복 조건)

  • Lee, Jong-In;Bae, Il Rho;Moon, Gang Il
    • KSCE Journal of Civil and Environmental Engineering Research
    • /
    • v.39 no.6
    • /
    • pp.769-777
    • /
    • 2019
  • Low crested coastal structures such as detached breakwaters and submerged breakwaters (artificial reefs) have been commonly used as coastal protection measures. The armour units of these structures are unstable than those in non-overtopped structure cases. The stability of low crested structures armoured by rock has been suggested in existing studies. In this study, the stability of Tetrapods armour units on theses structures has been investigated using two-dimensional hydraulic model tests. The effect of wave steepness and freeboard on the armour stability on crest, front, and the rear slope has been investigated. Armour units were mostly damaged near the upper part of the seaward slope and the crest of the seaward side. From the experimental data, the new empirical formula for the stability coefficients of the Tetrapods was proposed.

The Influence on the Voltage Distribution of Multi-Gates of IGFET by the Slow Wave (IGFET채널내의 Slow Wave가 복수 게이트상의 전압분포에 미치는 영향에 관한 연구)

  • 라극환
    • Journal of the Korean Institute of Telematics and Electronics
    • /
    • v.22 no.4
    • /
    • pp.66-71
    • /
    • 1985
  • A MOSFET with multigates arrayed in periodic structure is studied as a transit time device for microwave amplification. The interactions between the periodic metal gates and the slow wave on the surface of the semiconductor can be observed in the vicinity of synchronism. The stability and the reciprocity of the active quadrupole are shown depending on the frequency and velocity of the carriers.

  • PDF

A Study on the Durability and Running Stability Evaluation of the Korean PRT (한국형 소형궤도차량(PRT)의 내구성 및 주행안정성 평가 연구)

  • Cho, Jeonggil;Kim, Junwoo;Kim, Hyuntae;Koo, Jeongseo;Kang, Seokwon;Jeong, Raggyo
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.22 no.5
    • /
    • pp.50-58
    • /
    • 2014
  • The PRT(Personal Rapid Transit) system is highly interested to meet a need for demand-responsive transport service and increasing demands of traffic in Korea recently. And it is being spotlighted as an eco-friendly transportation system. For these reasons, researches on the PRT system are actively undergoing in Korea. In this study, we evaluated the static structural and fatigue strengths based on ASCE-APM standards and ERRI B 12/RP 17 by means of FE simulation. We also evaluate the running stability by multi-body dynamic analyses and the rollover safety by a theoretical static stability factor according to the road modeling scenarios for the PRT system. From the results of this study, we confirmed the durability and running stability of the Korean PRT under development.

Evaluation of GIS-based Landslide Hazard Mapping (GIS 기반 산사태 예측모형의 적용성 평가)

  • Oh, Kyoung-Doo;Hong, Il-Pyo;Jun, Byong-Ho;Ahn, Won-Sik;Lee, Mee-Young
    • Journal of Korea Water Resources Association
    • /
    • v.39 no.1
    • /
    • pp.23-33
    • /
    • 2006
  • In this study, application potential of SINMAP, a GIS-based landslide hazard mapping tool, is evaluated through a case study. Through the application to the severe landslide events occurred during a heavy storm in 1991 on the Mt. Dalbong area about 78 kilometers south from Seoul, SINMAP successfully spotted most landslide sites. The effects and proper ranges of three calibration parameters of SINMAP, i.e. the soil internal friction angle, the combined cohesion of tree roots and soil, and T/R, were examined through comparison of predicted landslides with the landslide inventory data. From the findings of this study, it seems that SINMAP could be used as an effective screening tool for landslide hazard mapping especially for mountain areas with fairly steep slopes and relatively thin soil layers.

Soybean Yield Performance and Growth Characteristics in Response to Underground Water Table Depth (지하수위에 따른 콩 품종의 생육특성 및 수량반응)

  • 윤광일;이홍석
    • KOREAN JOURNAL OF CROP SCIENCE
    • /
    • v.42 no.3
    • /
    • pp.367-372
    • /
    • 1997
  • Excessive water stress is one of major limiting factors affecting soybean yield, especially when soybean is grown in converted upland from paddy field. The present study was undertaken to know the genotypic variation in yield response of soybean to different environments in combination with soil texture and underground water table depth. Eight recommended soybean varieties in Korea and two supernodulating soybean mutants introduced from USA were planted in the lysimeter which was filled with two different soil types(sandy loam and clay loam). Of three underground water table depths(10, 30, and 50 cm) during whole growth stage, the lowest 10 cm was included to create excessive water stress. Yield was significantly different according to the underground water table depth and soybean genotypes, whereas soil type did not affect yield. There were significant interaction effects of soybean yield among soil type, soybean genotype, and underground water table depth. Yield of nts 1116 showed the highest across environments. Based on the regression analysis, the most stable variety was Sobaeknamulkong(bi=1.09). Jangsukong was fairly stable and high in yield, when compared to other soybean genotypes. However, nts 1116 was the most desirable ($D_i=228$) mainly due to the highest yield rather than the greater stability over environments. Multiple regression analysis revealed that shoot dry weight and nodule number were major factors affecting yield in the combined data over three water table depths and two soil types.

  • PDF