• Title/Summary/Keyword: shallow depth

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Studies on Growth Characteristics and Shallow Green-Roof Systems of Sedum album L. Introduced in Korea (국내에 도입된 Sedum album L.의 생육 특성 및 저토심 옥상 녹화 시스템에 관한 연구)

  • Kim In-Hye;Huh Moo-Ryong;Huh Keun-Young
    • Journal of the Korean Institute of Landscape Architecture
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    • v.33 no.5 s.112
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    • pp.69-82
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    • 2005
  • These studies were carried out (1) to investigate the growth characteristics of Sedum album L. in the field, (2) to propose a suitable shallow peen roof system for this plant, and (3) to evaluate plant growth in the proposed system over the long term. The growth characteristics, such as morphological properties, growth habit, shade tolerance, and flowering, were surveyed. In experimental shallow green-roof systems, the effects of drainage type, substrate type, and soil depth on plant growth were investigated. Then drought tolerance was investigated. After planting Sedum album L. in the proposed system survival rate, cover, and resistance to insects, heal and cold were evaluated for about 2 years. The results of these studies are summarized below. 1. In the field, the aboveground part of Sedum album L. did not die back during the winter. Plant height was 4$\sim$7 cm. Roots were distributed to a depth of 5$\sim$7 cm. Sedum album L. is a compact ground-cover plant that spreads vigorously. Shading condition of less than $30\%$ of full sunlight didn't cause any trouble, but shading conditions above $87\%$ made the shape of the shoots and leaves abnormal. The plant bloomed from June to August and had a rather large compound umbel of white, star-shaped flowers. 2. Two systems, a drainage-blend-10 cm soil depth and a reservoir$\cdot$drainage-blend-15 cm soil depth, performed best in terms of cover, fresh weight, and dry weight. The first has an advantage for green roofs because it is lighter than the latter. 3. In drainage-blend-10 m soil depth and modified reservoir · drainage-blend-10 cm soil depth system no plants died for about 4 months after stopping the irrigation. The visual quality of the latter system was above 5 for 4 months and that of the former was under 5 after 2 months. In the field, however, the drought tolerance of Sedum album L. grown in the former would be enough to withstand the dry season. Considering the urban ecosystem and the importance of healthy growth the modified reservoir $\cdot$ drainage-blend-10 cm soil depth system was finally recommended. This system was composed of a 4 cm thick drainage layer and drain outlets placed at a height of 2.5 cm. 4. In the proposed system, the survival rate was $100\%$, and there was no injury induced by insects and heat. The leaf density decreased a little in winter. Cover increased throughout the year. Sedum album L. was planted with a cover of 72$cm^{2}$ on 3 April 2003; on 16 June 2003 and 15 June 2004, cover was $132.66\pm$5.87 $cm^{2}$(1.8 times) and $886.98\pm$63.51 $cm^{2}$(12.3 times), respectively.

A study on Gap Parameter and Influence Area of Ground Settlement Using Back Analysis Constructed by Shield TBM with Shallow Depth (천층터널 쉴드TBM에서 역해석을 이용한 Gap Parameter 및 지표침하 영향범위에 대한 연구)

  • Koh, Sung-Yil;Kwon, Sung-Ju;Hwang, Chang-Hee;Kim, Sang-In;Choo, Seok-Yeon
    • Proceedings of the KSR Conference
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    • 2011.05a
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    • pp.1509-1518
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    • 2011
  • Shield TBM tunneling method has been getting the spotlight for urban tunneling. It can be minimized the civil complaint during construction and possible safe tunneling. But the settlement has occurred inevitably due to characteristics of shield TBM equipment. For this reason, the civil complaint can occur in urban areas when tunnel with shallow depth passes through neighboring building or residential area. In this study, the occurrence factors of settlement according to shield TBM tunneling and the tendency of ground settlement by strata condition had analyzed. It is suggested that the practical settlement estimation method and minimizing method of ground settlement under simultaneous backfill grouting condition through measurement results and back analysis data using gap parameter.

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Control of the Lateral Displacement Restoring Force of IRWs for Sharp Curved Driving

  • Ahn, Hanwoong;Lee, Hyungwoo;Go, Sungchul;Cho, Yonho;Lee, Ju
    • Journal of Electrical Engineering and Technology
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    • v.11 no.4
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    • pp.1042-1048
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    • 2016
  • This paper presents a lateral displacement restoring force control for the independently rotating wheelsets (IRWs) of shallow-depth subway systems. In the case of the near surface transit, which has recently been introduced, sharp curved driving performance is required for the city center service. It is possible to decrease the curve radius and to improve the performance of the straight running with the individual torque control. Therefore, the individual torque control performance of the motor is the most important point of the near surface transit. This paper deals with a lateral displacement restoring force control for sharp curved driving. The validity and usefulness of the proposed control algorithm is verified by experimental results using a small-scale bogie system.

Bearing capacity of shallow footing under combined loading

  • Kusakabe, Osamu;Takeyama, Tomohide
    • Proceedings of the Korean Geotechical Society Conference
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    • 2010.09a
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    • pp.3-25
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    • 2010
  • The paper deals with two bearing capacity problems of shallow footing under combined loading. The first is a FEM study of shallow strip footing on two-layer clay deposits subjected to a vertical, horizontal and moment combined loading, while the second is a centrifuge study of shallow rectangular footing on dry sand under double eccentricity. The FEM results revealed that the existence of top soft layer sensitively affects more on horizontal and moment capacity than vertical capacity for cases of footing on soft clay overlying stiff clay. Practical design charts are presented to evaluate bearing capacities of footing for various combinations of the ratio of the depth of the upper layer to the footing width and the ratio of undrained strength of the upper layer to that of the lower. The centrifuge tests indicated that current design practice of calculating failure load of rectangular surface footing under double eccentricity underestimates the centrifuge loading test data. This trend is more marked when the eccentricity becomes larger. The decreasing trend in failure load with an increase of double eccentricity is rather uniquely expressed by a single curve, using a newly defined resultant eccentricity and the diagonal length of the footing base.

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Estimation of ultimate bearing capacity of shallow foundations resting on cohesionless soils using a new hybrid M5'-GP model

  • Khorrami, Rouhollah;Derakhshani, Ali
    • Geomechanics and Engineering
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    • v.19 no.2
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    • pp.127-139
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    • 2019
  • Available methods to determine the ultimate bearing capacity of shallow foundations may not be accurate enough owing to the complicated failure mechanism and diversity of the underlying soils. Accordingly, applying new methods of artificial intelligence can improve the prediction of the ultimate bearing capacity. The M5' model tree and the genetic programming are two robust artificial intelligence methods used for prediction purposes. The model tree is able to categorize the data and present linear models while genetic programming can give nonlinear models. In this study, a combination of these methods, called the M5'-GP approach, is employed to predict the ultimate bearing capacity of the shallow foundations, so that the advantages of both methods are exploited, simultaneously. Factors governing the bearing capacity of the shallow foundations, including width of the foundation (B), embedment depth of the foundation (D), length of the foundation (L), effective unit weight of the soil (${\gamma}$) and internal friction angle of the soil (${\varphi}$) are considered for modeling. To develop the new model, experimental data of large and small-scale tests were collected from the literature. Evaluation of the new model by statistical indices reveals its better performance in contrast to both traditional and recent approaches. Moreover, sensitivity analysis of the proposed model indicates the significance of various predictors. Additionally, it is inferred that the new model compares favorably with different models presented by various researchers based on a comprehensive ranking system.

A study on the turning-motion of T/S SAEBADA in shallow water (실습선 새바다호의 천수역 선회운동에 관한 연구)

  • KIM, Su-Hyung;LEE, Chun-Ki
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.55 no.3
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    • pp.273-283
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    • 2019
  • The authors has predicted the maneuvering characteristics of a fishing vessel in deep water using Kijima's empirical formula in a previous study. Since the Kijima's empirical formula was developed by a regression analysis of merchant vessels which have dimensions ($C_b$, L/B, etc.) that are different from those of fishing vessels, it was possible to make a prediction approximately even with inaccurate estimation. In this study, the authors estimated the turning-motion characteristics of a model ship of fisheries training ship in shallow water based on the results of its previous study. The turning-motion characteristics of the model ship in shallow water was found out through quantitative analysis according to the water depth to ship draft ratio (H/d). In conclusion, the turning-motion characteristics of the model ship had significant changes immediately after an H/d 1.5, and this result will be helpful for sailing in shallow water.

Characteristics of Transistors and Isolation as Trench Depth (트렌치 깊이에 따른 트랜지스터와 소자분리 특성)

  • 박상원;김선순;최준기;이상희;김용해;장성근;한대희;김형덕
    • Proceedings of the IEEK Conference
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    • 1999.06a
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    • pp.911-913
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    • 1999
  • Shallow Trench Isolation (STI) has become the most promising isolation scheme for ULSI applications. The stress of STI structure is one of several factors to degrade characteristics of a device. The stress contours or STI structure vary with the trench depth. Isolation characteristics of STI was analyzed as the depth of trench varied. And transistor characteristics was compared. Isolation punch-through voltage for n$^{+}$ to pwell and p$^{+}$ to nwell increased as trench depth increased. n$^{+}$ to pwell leakage current had nothing to do with trench depth but n$^{+}$ to pwell leakage current decreased as trench depth increased. In the case of transistor characteristics, short channel effect was independent on trench depth and inverse narrow width effect was greater for deeper trenches. Therefore in order to achieve stable device, it is important to minimize stress by optimizing trench depth.

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