• Journal of Biosystems Engineering
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• v.40 no.1
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• pp.1-9
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• 2015

Purpose: The objective of this study was to understand the operating mechanism of the rock-drill drifter, to explain how to setup an experimental test system and measure the strain of the drifter's rod, and to evaluate the drifter's performance with respect to the impact energy and blow frequency. Methods: The structure of the rock-drill drifter and its operating principle regarding the impact process were analyzed. Static calibration was carried out to calculate the correction factor using a drifter rod as the first step of the experimental test. The impact energy and blow frequency were then calculated based on strain measurements of the drifter's rod. Results: Experimental results showed that the tested drifter elicited a blow frequency of 3330 BPM (Blows Per Minute) and generated impact energy of 170 J/blow. This indicates that the drifter elicits a higher percussion speed and results in a lower impact energy compared to the hydraulic breaker at the same input power. Conclusions: The study proposed methodologies that deal with the experimental setup and the evaluation of the performance of the rock-drill drifter. These methodologies can be extensively used for validating and improving the percussion performance of the drilling equipment.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.16 no.4
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• pp.235-242
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• 2012

In this paper, we investigate a nonlocal semilinear heat equation with homogeneous Dirichlet boundary condition in a bounded domain, and prove that there exist solutions with positive initial energy that blow up in finite time.

• Bulletin of the Korean Mathematical Society
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• v.56 no.5
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• pp.1285-1296
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• 2019

This paper deals with the blow-up phenomenon of solutions to a pseudo-parabolic equation with logarithmic nonlinearity, which was studied extensively in recent years. The previous result depends on the mountain-pass level d (see (1.6) for its definition). In this paper, we obtain two blow-up conditions which do not depend on d. Moreover, the upper bound of the blow-up time is obtained.

• Journal of the Korean Mathematical Society
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• v.58 no.3
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• pp.633-642
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• 2021

In this paper we consider the following strongly damped wave equation with variable-exponent nonlinearity u_tt(x, t) - ∆u(x, t) - ∆u_t(x, t) = |u(x, t)|^p(x)-2u(x, t), where the exponent p(·) of nonlinearity is a given measurable function. We establish finite time blow-up results for the solutions with non-positive initial energy and for certain solutions with positive initial energy. We extend the previous results for strongly damped wave equations with constant exponent nonlinearity to the equations with variable-exponent nonlinearity.

• Journal of the Chungcheong Mathematical Society
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• v.35 no.2
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• pp.137-147
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• 2022

In this paper, we considered the Dirichlet initial boundary value problem of a nonlinear viscoelastic wave equation with nonlinear damping and source terms, and investigated finite time blow-up phenomena of the solutions to the equation with arbitrary positive initial data, under suitable conditions.

• East Asian mathematical journal
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• v.39 no.3
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• pp.319-329
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• 2023

In this paper, we consider a stochastic higher-order Kirchhoff-type equation with nonlinear damping and source terms. We prove the blow-up of solution for a stochastic higher-order Kirchhoff-type equation with positive probability or explosive in energy sense.

• Bulletin of the Korean Mathematical Society
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• v.59 no.6
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• pp.1495-1510
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• 2022

This paper aims to investigate the initial boundary value problem of the nonlinear viscoelastic Petrovsky type equation with nonlinear damping and logarithmic source term. We derive the blow-up results by the combination of the perturbation energy method, concavity method, and differential-integral inequality technique.

• Bulletin of the Korean Mathematical Society
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• v.55 no.4
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• pp.1161-1178
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• 2018

In this paper, we consider the Cauchy problem for a class of nonlinear sixth-order wave equation. The global existence and the finite time blow-up for the problem are proved by the potential well method at both low and critical initial energy levels. Furthermore, we present some sufficient conditions on initial data such that the weak solution exists globally at supercritical initial energy level by introducing a new stable set.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.28-35
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• 2004

Driven pile has the excellent bearing characteristics and good economics, so it is known as the comparative piling method. To use the advantages of driven pile fully, it is necessary to perform the proper construction management. Engineers must drive pile to the proper bearing layer with proper blow energy and measure the blow count and penetration per certain depth to analyze the bearing capacity and driveability. In conventional method, these parameters have been measured manually so it was difficult to get good accuracy. After PIR-D(Pile Installation Recorder-Driven Pile) was attached to the driving equipment, the hammer efficiency, blow count and penetration in blow/10cm were measured automatically. In this paper, to givethe rational judgement criteria of bearing layer, driveability, blow/10cm according to pile depth during pile driving, the some relationship between the driving resistance and ground layer distribution was analyzed. The ground investigation during piles (PHC ${\Phi}450,\;{\Phi}400\;&\;Steel\;Pile\;{\Phi}609{\ast}16t$) installation in the marine clay layer in Incheon, the sandy soil layer in Yongin and the tuff layer in Pusan was done. And measuring hammer efficiency not doing recently, we could compare hammer efficiency(Eh) by PIR-D and energy transfer ratio(ETR) by Pile Dynamic Analyzer(PDA).

• Bulletin of the Korean Mathematical Society
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• v.51 no.6
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• pp.1697-1710
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• 2014

The initial-boundary value problem for a class of nonlinear higher-order wave equations system with a damping and source terms in bounded domain is studied. We prove the existence of global solutions. Meanwhile, under the condition of the positive initial energy, it is showed that the solutions blow up in the finite time and the lifespan estimate of solutions is also given.