• Journal of the Korean Geotechnical Society
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• v.24 no.8
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• pp.53-60
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• 2008

In this study, various kinds of behavior characteristics such as deformation area zone of back ground, failure angle and rotation point are examined on the laterally loaded single pile in the homogeneous ground through a model test. The main obtained conclusions are summarized as follows; In the back ground of single pile to which the lateral load is applied, failure surface shows almost linear movement characteristics and it is inclined to converge to constant values no matter how the length of pile and the pile head displacement.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.1035-1040
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• 2001

The effects of polymer-binder ratio and slag content on the properties of combined wet/dry-cured polymer-modified mortars using granulated blast-furnace slag (slag) are examined. As a result, the flexural and compressive strengths of polymer-modified mortar using slag reaches a maximum at a slag content of 40%, and is inclined to increase with increasing polymer-binder ratio. The water absorption, carbonation depth and chloride ion penetration depth tend to decrease with increasing polymer-binder ratio and slag content.

• Journal of the Korean Geotechnical Society
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• v.32 no.4
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• pp.29-39
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• 2016

This paper presents the results of 2D and 3D finite element simulations conducted to analyze the effects of excavation depth (H), excavation width (L), and ground condition on the behavior of anchored earth retaining wall in inclined ground layers. The results of numerical analyses are compared with those of the site instrumentation analyses. Based on the results obtained, it appeared that 2D numerical analysis tends to overestimate the horizontal displacement of retaining wall compared to the 3D numerical analysis. When the excavation depth is deeper than 20m, it is found that 2D and 3D numerical analysis results of excavation work in soil ground condition are more different from the results in rock ground condition. For an accurate 3D numerical analysis, applying 3D mesh which has an excavation width twice longer than excavation depth is recommended. Consequently, 3D numerical analysis may be able to offer significantly better predictions of movement than 2D analysis.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.1090-1095
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• 2004

Umbrella Arch Method(UAM), among others. is commonly applied to increase the facial stability during tunnel excavation and, depending on the field condition, additional reinforcement techniques can be used simultaneously. UAM, together with grouting method, is normally used to reduce ground permeability and improve stability of the tunnel by inserting a series of steel pipes into the ground around the crown inclined to the longitudinal axis of the tunnel. However. there has not been much rigorous study on the effectiveness of UAM, and most of UAM installations depend on empirical judgement rather than on engineering calculation, .In this study, the effectiveness of UAM is demonstrated based on the constitutive relationship involving UAM derived from the mechanics of composite material, and the numerical investigation is compared with small scale experiments on the tunnel reinforcement.

• Journal of Korean Tunnelling and Underground Space Association
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• v.5 no.3
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• pp.261-268
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• 2003

Terzaghi's tunnel theory has been accepted to calculate tunnel loads conservatively in practical design until now. In this study, Terzaghi's tunnel theory was expanded to the inclined-layer ground with inclination of ground and stratification. Finally a new tunnel load equation was induced utilizing the original Terzaghi's tunnel theory and Terzaghi's tunnel theory was reviewed as well.

• Journal of Biosystems Engineering
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• v.22 no.2
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• pp.151-162
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• 1997

Chemical application is one of the most important field operation in rice production. Rolling of a boom due to local unevenness and softness in fields causes a local under/over-application of spray. In this study, the vertical movement of boom tips due to unevenness of ground in paddy fields was investigated, and an active pendulum suspension control system was designed and tested for compensating the movement and balancing the boom to the ground. The results for testing the performance of the control system showed that the system could balance the boom both in flat and inclined fields. The active pendulum control system developed in this study could be properly used for improving spraying performance of a boom sprayer.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.2
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• pp.121-129
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• 2002

The present paper describes a technique for installing an effective grounding grids, the major objective is forced on the experimental evaluation of the performance and characteristics with the arrangement and installation method for grounding grids consisting of the means to protect electric shock, electronics and computerized facilities against lightning, switching and ground fault surges. The study is oriented on two major areas: (1) the analysis of the ground surface potential gradient with the arrangement of grounding grids, (2) the control of the dangerous ground surface potential rise. The experiments wee carried out with the impulse currents as a function of the installation method or arrangement of grounding grids. An installation method of the inclined auxiliary grounding grid was proposed to overcome the drawbacks of equally spared grounding grids, i.e. an appropriate design concept far the installation of grounding grids was found out, It has been shown that the installation of the intwined auxiliary grounding grid can also result in a mere than 50% decrease in the maximum potential gradient on the ground surface and enhance the level of safety for persons and electronic equipments..

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.859-864
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• 2003

This paper presents a design for the novel suspension mechanism of a two-wheeled mobile robot having two casters which is used for indoor environment. Although the indoor environment is less rough than the outdoor one, the fixed caster mechanism has some problems such as causing the robot to be immovable because robot's driving wheels do not have contact with the ground. Therefore, we tried installing a spring-damper suspension mechanism to keep driving capability and to remove pitching phenomenon. However, this suspension mechanism also has the problem, which the robot body inclined by disturbances does not return to the initial position. To deal with above problems and to accomplish desired performances, we designed the Multilayered Suspension Mechanism, which has springs and dampers working partially according to the inclined angle and angular velocity of robot body concerned with pitching. To analyze design, the equations of motion describing their dynamics were developed. Using the equations, simulation results show the improved performance. We confirm the usefulness of the Multilayered Suspension Mechanism by construction and test of a actual prototype.

• Geomechanics and Engineering
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• v.33 no.1
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• pp.91-99
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• 2023

To test the effect of various pile tip shape series of model scale loading tests were carried out on test piles with special pile tips. Special pile tips were made using the 3D printer and were attached to the bottom end of the test pile for loading tests. The pile tips were made to have 30°, 45°, 60° inclined tips, as well as a rounded tip. The main objective of the test was to observe the effect of various pile tip shapes on settlement and penetrability of the pile. Moreover, a numerical model simulating the pile loading test carried out in this study was established and verified based on the loading test results. From this, the stress concentration around the pile tip was investigated. This will allow us to analyze the decrease of stress concentration around the pile tip which is the main cause of the pile tip damage during pile installation. However, modifying the pile tip shape will eventually increase the settlement of the pile. By estimating the degree of increase in pile settlement, the viability and the efficiency of the pile shape modification was judged. In addition, case studies on the effect of different pile tip shape and ground conditions on pile settlement and stress dispersion was conducted.

• Journal of the Korean Society of Propulsion Engineers
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• v.3 no.4
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• pp.67-74
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• 1999

Problems created by supersonic jet impinging on solid objects or ground arise in a variety of situations. For example multi-stage rocket separation, deep-space docking, V/STOL aircraft, jet-engine exhaust, gas-turbine blade, terrestrial rocket launch, and so on. These impinging jet flows generally contain a complex structures. (mixed subsonic and supersonic regions, interacting shocks and expansion waves, regions of turbulent shear layer) This paper describes experimental works on the phenomena (surface pressure distribution, flow visualization) when underexpanded supersonic jets impinge on the perpendicular, inclined plate using a supersonic cold-(low system. The used supersonic nozzle is convergent-divergent type, exit Mach number 2, The maximum on the plate when it was inclined was much larger than perpendicular plate, owing to high pressure recoveries through multiple shocks. Surface pressure distribution as to underexpanded ratio showed similar patterns together.