• 한국정밀공학회지
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• 제27권9호
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• pp.86-93
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• 2010

Any relative deformation between the cutting tool and the workpiece at the machining point, results directly in form and dimensional errors. The source of relative deformations between the cutting tool and the workpiece at the contact point may be due to thermal, weight, and cutting forces. Thermal and weight deformations can be measured at various positions of the machine tool and stored in the compensation registers of the CNC unit and compensated the errors during machining. However, the cutting force induced errors are difficult to compensate because estimation of cutting forces are difficult. To minimize the error induced by cutting forces, it is important to improve the machining accuracy. This paper presents the pre-calculated method of form error induced by cutting forces. In order to estimate cutting forces, Isakov method is used and the method is verified by comparing with the experimental results. In order to this, a cylindrical-outer-diameter turning experiments are carried out according to cutting conditions.

• 한국산학기술학회논문지
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• 제16권6호
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• pp.4201-4207
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• 2015

본 연구에서는 최근 뉴질랜드의 Christchurch 지역의 2011년 2월 22일의 지진규모(Mw) 6.2 지진발생 후 얻어진 데이터를 이용하여 지진에 의한 지하 상수도관 시스템의 성능에 주안점을 두고 연구를 수행하였다. 이 논문은 액상화로 인하여 발생된 영구지반변형지역과 서로 다른 재질의 상수도관에 따라 1 km 당 손상갯수로 산정되는 손상율을 액상화 지역에서의 지진발생 전후에 얻어진 높은 해상도의 라이다데이터로부터 계산된 부등침하와 횡방향 지반변형률의 관계를 통하여 산정하였다. 본 연구에서는 영구지반변형에 따른 매설된 상수도관의 지진성능을 요약하여 설명하였으며 연구결과 연성이 매우 큰 폴리에틸렌 상수도관이 매우 우수한 지진성능을 가지고 있음을 알 수 있다.

• 한국지반공학회논문집
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• 제38권1호
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• pp.35-45
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• 2022

개착공법으로 원형 수직구 건설 시, 가시설 흙막이 벽체는 일정 수준의 변위를 허용하는 연성벽체로 설계된다. 합리적이고 경제적인 연성벽체의 구조 설계를 위해서는 벽체에 작용하는 토압을 정확히 평가할 필요가 있다. 원형 수직구 벽체에 작용하는 토압은 주변 지반의 소성 변형과 밀접하게 연관되어 있으나, 이에 대한 연구는 부족한 상황이다. 본 연구는 원형 수직구의 단계 굴착을 원심모형시험을 통해 모사하고, 원심모형시험 중 촬영된 이미지에 이미지 해석 기법을 적용하여 원형 수직구 굴착 시 주변 지반에 발생하는 변형을 평가하였다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.199-202
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• 2008

In this study, we investigated the thermal properties of $Zr_{66.4}Nb_{6.4}Cu_{10.5}Ni_{8.7}Al_{8.0}$ by using a differential scanning calorimeter (DSC), and then analyzed the composition of dendrite phase by using X-ray diffraction (XRD). A series of uniaxial compression tests has been performed under the strain rates between $10^{-5}/s$ and $10^{-2}/s$ at room temperature and near SLR. This BMGC has higher high temperature strength than other Zr-based monolithic BMGs because in-situ formed crystalline phases hinder a feasible viscous flow of amorphous matrix. Warm formability is also estimated by laboratory-scale extrusion test within supercooled liquid region. It was found that BMGC has poor formability compared with nother Zr-based bulk metallic glass composite presumably due to large volume fraction of 'brittle' crystalline phases distributed within amorphous matrix.

• 한국지구과학회지
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• 제37권5호
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• pp.271-276
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• 2016

We present our estimate of pole shift caused by the recent 31 largest earthquakes of magnitude over 8.0. After reviewing theory of perturbation in the Earth's rotation, each co-seismic as well as post-seismic pole shifts by the earthquakes are acquired and illustrated. A total co-seismic excitation due to these earthquakes is ($x_1$, $x_2$)=(-3.35, 5.89) milliarcsec, which increased about twice the initial estimation when the post-seismic deformation is considered. The single largest co-seismic excitation by 2011 Japan earthquake was ($x_1$, $x_2$)=(-2.06, 2.36) milliarcsec, which corresponds to 9.7 cm pole shift on the surface of the Earth.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표논문집(II)
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• pp.559-564
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• 1998

The object of this thesis is an analytical study on shear deformation of reinforced concrete members using monte carlo method. Using the established experimental data that has been presented in various documents the stress-strain relationships curves of reinforced concrete (300kgf/$\textrm{cm}^2$~400kgf/$\textrm{cm}^2$) models are proposed. Finally, the theoretical values calculated using the analytical method developed in this study have been investigated in comparison with the experimental ones which were carried out earlier in order to prove its validity. From the results it has been shown that theoretical values agree quite well with experimental ones, and it could be pointed out that the presented analytical method is widely acceptable for the practical analysis of shear displacement of reinforced concrete members.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.23-26
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• 2003

This paper explains the die cooling method for improving tool life in the hot forging process. In continuous forming operation such as hot forging process, performed at high speeds, temperature increases of several hundred degrees may be involved. Die hardness was reduced due to thermal softening. Factor of die fracture are wear and plastic deformation of die due to hardness reduction by high temperature. Because die service life was reduced due to this phenomenon during hot forging, quantified data for optimal die cooling method is required. The new developed techniques for predicting tool life applied to estimate the production quantity for a spindle component and these techniques can be applied to improve the tool life in hot forging process

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권3호
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• pp.266-281
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• 2017

Hydroelastic interactions of a deformable floating body with random waves are investigated in time domain. Both hydroelastic motion and structural dynamics are solved by expansion of elastic modes and Fourier transform for the random waves. A direct and efficient structural analysis in time domain is developed. In particular, an efficient way of obtaining distributive loads for the hydrodynamic integral terms including convolution integral by using Fubini theory is explained. After confirming correctness of respective loading components, calculations of full distributions of loads in random waves are expedited by reformulating all the body loading terms into distributed forms. The method is validated by extensive convergence tests and comparisons against the counterparts of the frequency-domain analysis. Characteristics of motion/deformation responses and stress resultants are investigated through a parametric study with varying bending rigidity and types of random waves. Relative contributions of componential loads are identified. The consequence of elastic-mode resonance is underscored.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.792-802
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• 2008

If a tunnel is constructed below the groundwater level, the groundwater flow will occur inducing the seepage force toward the tunnel and will result in the increase of tunnel convergence. The longitudinal deformation during tunnel excavation will also be increased due to seepage pressure. A back-analysis methodology in underwater tunnel was proposed in this study based on the relative longitudinal deformation measured in-situ. Geotechnical parameters can be estimated utilizing the proposed method where the prior estimate as well as the measured convergence can be reasonably combined by adopting the Extend Bayesian Method.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.570-573
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• 2006

It is proposed that the electromechanical relation of the conductive materials with high electrical resistance may be used to estimate the current stress of prestressing tendons. To choose the best conductive material to this end, we studied the electromechanical relations of carbon fibers and metalic heat wires experimentally. It is found that the relation of carbon fibers can be modelled by a parabolic(or hyperbolic) function in the early stage of deformation. Metallic heat wires show a consistent linear relation during loading and unloading in the elastic deformation and are suitable for this purpose. We propose a new kind of prestressing tendons whose stress can be monitored.