• 콘크리트학회논문집
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• 제11권4호
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• pp.129-136
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• 1999

For the prediction of concrete-steel bond ability in reinforced concrete, many countries establish specifications for the pullout test. But these methods hardly to consider many parameters such as strength, shape, diameter and location of steel, concrete restrict condition by loading plate, strength of concrete and cover depth etc, and it is difficult to solve concentration and disturbance of stress. The purpose of this study is to propose a New Ring Test method which can be rational quantity evaluations of bond splitting mechanism. For this purpose, pullout test was carried out to assess the effect of several variables on bond splitting properties between reinforcing bar and concrete. Key variables are concrete compressive strength, concrete cover, bar diameter and rib spacing. Failure mode was examined and maximum bond stress-slip relationships were presented to show the effect of above variables. As the result, it appropriately expressed general characteristics of bond splitting mechanism, and it proved capability for standard test method.

• 한국항해항만학회지
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• 제33권2호
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• pp.153-159
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• 2009

The awareness of the high-value industry for container terminal leads competitiveness of container terminals to keep high fiercely. In regards to competitive factors of container terminal, the most important point among several factors is seemed to be the speed of container loading and unloading on quayside. In container terminals in Korea, the productivity shows big difference even though its condition is similar to each terminal. The objective of this paper is to find the critical factors of container terminal productivity, which is dependant upon the capability, quantity of quay crane, transfer vehicle, and so on. For this purpose, we have researched related literatures, and collected data about container terminals in South Korea. Furthermore, we tested sensitive analysis to evaluate the extent of productivity by changing independent variable. And then we established the regression model to evaluate which factor has had the biggest impact on productivity. The results of this paper can give terminal operators guideline to improve productivity.

• International Journal of Aerospace System Engineering
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• 제2권2호
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• pp.87-91
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• 2015

KT-1P for the Peru Air Force will be used as a utility aircraft with upgraded avionics equipment and arming capability based on KT-1 and KA-1. KT-1P should be shown for compatibility of new store loading configurations loaded with dispenser, bomb, and rocket based on aircraft-store compatibility test and evaluation procedures before KT-1P is operated as a light attack aircraft. The weapon system ground test for installation and flight test for envelope expansion including store separation are described in this paper, which was performed referring 'seek eagle program' under MIL-HDBK-1763 and MIL-HDBK-244A.

• 한국전산구조공학회논문집
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• 제23권6호
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• pp.593-606
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• 2010

This paper presents a formulation to include the prestressing effects in available numerical models for the nonlinear material, instantaneous and long-term analysis of prestressed concrete shell structures, based on the displacement formulation of the finite element method. A four-node flat shell element is adopted for nonlinear analysis of prestressed concrete shells. This element was incorporated into an existing general-purpose finite element analysis program. A distinctive characteristic of the element is its capability to simulate the behavior of shells subjected to a variety of types of loading and drilling rotational stiffness. Consequently, the response of prestressed concrete shell structures can be predicted accurately using the proposed nonlinear finite element procedure.

• Earthquakes and Structures
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• 제8권3호
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• pp.639-663
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• 2015

Time history dynamic structural analysis is a time consuming procedure when used for large-scale structures or iterative analysis in structural optimization. This article proposes a new methodology for approximate prediction of extremum point of the response history via wavelets. The method changes original record into a reduced record, decreasing the computational time of the analysis. This reduced record can be utilized in iterative structural dynamic analysis of optimization and hence significantly reduces the overall computational effort. Design examples are included to demonstrate the capability and efficiency of the Reduced Record Method (RRM) when utilized in optimal design of frame structures using meta-heuristic algorithms.

• 한국항만학회지
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• 제14권4호
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• pp.395-406
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• 2000

In this paper, an improved high efficiency gantry crane for container transportation is designed. The basic concept of the designed crane can be used with modification of the classical gantry crane instead of changing lots of them. This crane can reduce the cycle time more than the classical gantry carne. The high efficiency gantry crane can improve the productivity of the container transportation job because of reducing cycle time. The loading and unloading capability are compared with classical crane. The result show that show that the proposed crane has better performances than classical type.

• 한국자동차공학회논문집
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• 제11권4호
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• pp.173-179
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• 2003

In this paper, a real-time multibody vehicle dynamics and control model has been developed for a virtual reality intelligent vehicle simulator. The simulator consists of low PCs for a virtual reality visualization system, vehicle dynamics and control analysis system a control loading system, and a network monitoring system. Virtual environment is created by 3D Studio Max graphic tool and OpenGVS real-time rendering library. A real-time vehicle dynamics and control model consists of a control module based on the sliding mode control for adaptive cruise control and a real-time multibody vehicle dynamics module based on the subsystem synthesis method. To verify the real-time capability of the model, cut-in, cut-out simulations have been carried out.

• Geomechanics and Engineering
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• 제13권5호
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• pp.743-756
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• 2017

Laboratory investigation reveals that rockfills exhibit significant stress-path-dependent behavior during shearing, therefore realistic prediction of deformation of rockfill structures requires suitable constitutive models to properly reproduce such behavior. This paper evaluates the capability of a strain hardening model proposed by the authors, by comparing simulation results with large-scale triaxial stress-path test results. Despite of its simplicity, the model can simulate essential aspects of the shear behavior of rockfills, including the non-linear stress-strain relationship, the stress-dependence of the stiffness, the non-linear strength behavior, and the shearing contraction and dilatancy. More importantly, the model is shown to predict the markedly different stress-strain and volumetric behavior along various loading paths with fair accuracy. All parameters required for the model can be derived entirely from the results of conventional large triaxial tests with constant confining pressures.

• Steel and Composite Structures
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• 제31권5호
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• pp.427-435
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• 2019

The estimation of moment and rotation in steel rack connections could be significantly helpful parameters for designers and constructors in the initial designing and construction phases. Accordingly, Extreme Learning Machine (ELM) has been optimized to estimate the moment and rotation in steel rack connection based on variable input characteristics as beam depth, column thickness, connector depth, moment and loading. The prediction and estimating of ELM has been juxtaposed with genetic programming (GP) and artificial neural networks (ANNs) methods. Test outcomes have indicated a surpass in accuracy predicting and the capability of generalization in ELM approach than GP or ANN. Therefore, the application of ELM has been basically promised as an alternative way to estimate the moment and rotation of steel rack connection. Further particulars are presented in details in results and discussion.

• 한국도로학회논문집
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• 제11권2호
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• pp.99-109
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• 2009

소입경 골재노출콘크리트포장은 콘크리트 타설 직후 포장표면에 응결지연제를 살포하여 표면으로부터 깊이 2$\sim$3mm 정도의 모르타르 경화를 늦추게 한 후 표면의 모르타르 제거를 통해 굵은골재를 포장표면에 노출시키는 공법이다. 소입경 골재노출콘크리트포장은 타이어-노면 소음이 일반 콘크리트포장보다 4$\sim$5dB(A)정도 작으면서도 적정한 미끄럼저항을 장기간 유지한다는 장점을 가지고 있다. 소입경 골재노출콘크리트포장이 적정 평균조직깊이, 노출도 및 미끄럼저항을 확보하여 강도, 소음저감효과 및 장기간 적정 미끄럼저항성을 유지 하는 것도 중요하지만 성공적인 소입경 골재노출콘크리트포장의 건설을 위해서는 온도, 습도 등의 요인으로 발생하는 환경하중에 대한 내구성이 요구된다. 콘크리트포장은 타설 후 경화과정에서 수분손실 및 초기건조로 인하여 필연적으로 체적변화가수반되며 과도한 체적변화는 콘크리트 균열발생에 주요한 원인이 될 수 있다. 동결융해를 받고 있는 지역에서 제설제를 사용할 경우 표면박리현상이 발생한다. 이러한 균열 및 스케일링은 포장체의 내구성을 저하시키고 미끄럼저항을 감소시켜 장기공용성을 단축시키는 직접적인 요인으로 작용하게 된다. 따라서 본 연구에서는 소입경 골재노출콘크리트포장에 대하여 수분증발로 인한 수축균열 제어 성능 및 제설제를 사용하였을 경우에 반복되는 동결융해작용으로 인한 스켈링에 대해 내구성을 평가하여 환경하중 저항성에 대해 고찰하였다.