• Journal of the Korean Society of Marine Environment & Safety
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• v.1 no.1
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• pp.27-38
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• 1995

In this paper, a program for the calculation of GZ curve for a ship in waves is developed and GZ curves for a ferry in the still water and in waves are calculated. And the added mass, damping, restoring forces and wave exciting forces are calculated by using the strip theory given by Salvesen, Tuck, Faltinsen. Capsizing simulations are perfoned in consideration if the nonlinear restoring forces of the ship in waves by using the Runge-Kutta 4-th method.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.116.3-116
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• 2001

A diagnosis methodology for thickness quality in hot finishing mill is proposed based on multivariate statistical analysis. The thickness of hot strip is a key quality factor that is measured by x-ray thickness gauge. Currently, the thickness quality is guaranteed by upper and lower limit of thickness deviation from target thickness. But if any over-limit is occurred, there is no in-line method to identify the causes. In this paper, many parameters are extracted from the thickness deviation signal such as mean deviation(top, middle, tail), rms deviation(top, middle, tail) and peak deviation(top, middle, tail) as time domain parameters ...

• Geotechnical Engineering
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• v.12 no.5
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• pp.137-154
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• 1996

Pull-out tests for three different types of strip reinforcements are performed to investigate variation of the apparent coefficient of friction which occurs between the reinforcements and the weathered granite soils with different contents of fine materials. The contents of fine materials for the soil sample are varied from 7% to 36% and the reinforcements used for the pullout tests are smooth, ribbed steel strips and a textured shape Paraweb 1 Friction tie. Test results show that the apparent coefficient of friction tends to decrease with the increase of the content of fine meterials. It is known, however, that the minimum apparent coefficient of friction required to the design of reinforced earth structures can be achieved even at 35% fine contents by using appropriate reinforcements. The ribbed strip reinforcement is found to be the most effective in mobilizing the apparent friction when interacting to finer weathered granite soils. The textured reinforcement is also useful for 35% fine con tents if the textured depth is increased.

• Journal of the Korean Geosynthetics Society
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• v.13 no.3
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• pp.11-19
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• 2014

This paper describes interference effect analysis of transverse member based on large-scale pullout test results of steel strip reinforcement with '${\sqcap}$' type transverse member. The maximum passive resistance has a difference according to the installed location of transverse member, and the total pullout resistance is increased, when transverse member was closed to the wall facing. The degree of interference confirmed that the install location of transverse member cannot reflect the pullout force differential, if S/B is equal. However, The interference factor based on maximum passive resistance reflected the differential of maximum passive resistance and install location of transverse member.

• Bulletin of the Korean Mathematical Society
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• v.52 no.1
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• pp.105-123
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• 2015

Let $f_{\beta}=h_{\beta}+\bar{g}_{\beta}$ and $F_a=H_a+\bar{G}_a$ be harmonic mappings obtained by shearing of analytic mappings $h_{\beta}+g_{\beta}=1/(2isin{\beta})log\((1+ze^{i{\beta}})/(1+ze^{-i{\beta}})\)$, 0 < ${\beta}$ < ${\pi}$ and $H_a+G_a=z/(1-z)$, respectively. Kumar et al. [7] conjectured that if ${\omega}(z)=e^{i{\theta}}z^n({\theta}{\in}\mathbb{R},n{\in}\mathbb{N})$ and ${\omega}_a(z)=(a-z)/(1-az)$, $a{\in}(-1,1)$ are dilatations of $f_{\beta}$ and $F_a$, respectively, then $F_a\tilde{\ast}f_{\beta}{\in}S^0_H$ and is convex in the direction of the real axis, provided $a{\in}[(n-2)/(n+2),1)$. They claimed to have verified the result for n = 1, 2, 3 and 4 only. In the present paper, we settle the above conjecture, in the affirmative, for ${\beta}={\pi}/2$ and for all $n{\in}\mathbb{N}$.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.332-335
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• 2014

Applying damping sheets or dampers (dynamic or mass) can reduce noise from vibrating structure as well as vibration. However, this approach requires increases of weight and cost. If one can reduce structural noise by only modifying the structural shape, which would be the best practice. It is natural that the noise characteristics change when the structure is modified, but the recent experiment on the sunroof frame showed that the modification of the frame beads results in change of the structural damping, so that the corresponding noise can be reduced. In this context, the reason why the structural damping and the related noise upon an impact excitation is changed is theoretically investigated. The change of dynamic and damping characteristics of the strip panels when their shapes are modified is experimentally found and it is shown that such behaviours can be predicted by computer simulation. Some experimental specimen, mainly strip-type panels, are examined for the numerical verification, and especially damping ratios are investigated.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.29 no.4
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• pp.45-51
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• 2021

A runway safety area (RSA) is defined as the surface surrounding the runway prepared or suitable for reducing the risk of damage to airplanes in the event of an undershoot, overshoot, or excursion from the runway. The Runway Stripe is a defined area including the runway stopway, if provided, intended firstly to reduce the risk of damage to aircraft running off a runway, and secondly, to protect aircraft flying over it during takeoff or landing operations. This study used 2 RSA analysis models; RSARA and LRSARA. The analysis utilizes historical data from the specific airport and allows to take into consideration specific operational conditions to which movements are subject, as well as the actual or planned RSA conditions in terms of dimensions, configuration, and boundaries defined by existing obstacles. This study applied the RSA and LRSA risk assessment models to a domestic airport that do not meet the criteria required by standards for aerodrome physical characteristics. The airport is considering a method to secure the runway strip standard through the displaced threshold. This study intends to confirm through quantitative risk estimation whether meeting facility standards through the runway displaced threshold leads to a positive change in risk mitigation.

• Corrosion Science and Technology
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• v.23 no.2
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• pp.83-92
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• 2024

A hot-dip simulator was utilized to replicate abnormal coating buildup observed during line stops at galvanize lines, assessing the influence of processing conditions on buildup (up to 14 mm/side). Steel samples from 19 coils (comprising IF, BH, LCAK, HSLA, DP600-DP1180, Si: 0.006 - 0.8 wt%, P: 0.009 - 0.045 wt%) were examined to explore the phenomenon of heavy coating growth. It was discovered that heavy coating buildup (~3 mm/h) and rapid strip dissolution (~0.17 mm/h) in a GA or GI pot can manifest with specific combinations of steel chemistry and processing conditions. The results reveal the formation of a unique coating microstructure, characterized by a blend of bulky Zeta crystals and free Zn pockets/networks due to the "Sandlin" growth mechanism. Key variables contributing to abnormal coating growth include steel Si content, anneal temperature, dew point in heating and soaking furnaces, Zn pot temperature, Zn bath Al%, and cold-rolling reduction%. At ArcelorMittal Dofasco galvanize lines, an automatic online warning system for operators and special scheduling for incoming Si-bearing steels have been implemented, effectively preventing further heavy buildup occurrences.

• Geomechanics and Engineering
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• v.13 no.2
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• pp.269-284
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• 2017

A new technique is proposed to obtain more effective screening efficiency against the ground vibration using intermittent geofoam (IF) in-filled trench. The numerical analysis is performed by employing two-dimensional finite element method under dynamic condition. Vertically oscillated strip foundation is considered as the vibration source. In presence of the ground vibration, the vertical displacements at different locations (pick-up points) along the ground surface are captured to determine the amplitude reduction factor (ARF), which helps to assess the efficiency of the vibration screening technique. The efficiency of IF over continuous geofoam (CF) in-filled vibration barriers is assessed by varying the geofoam density, the location of trench and the frequency of excitation. The results from this study indicate that a significant reduction in ARF can be achieved by using intermittent geofoam as compared to continuous geofoam. Further, it is noticed that the efficiency of IF increases with an increase in the frequency of the vibrating source. These encouraging results put forward the potential of utilising intermittent geofoam as a vibration screening material.

• Bulletin of the Society of Naval Architects of Korea
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• v.24 no.4
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• pp.9-18
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• 1987

The hydrodynamic radiation forces acting on a ship travelling in waves have been conventionally treated by strip theories or by direct three dimensional approaches, most of which have been formulated in frequency domain. If the forward speed of a ship varies with time, or if its path is not a straight line, conventional frequency domain analysis can no more be used, and for these cases time domain analysis may be used. In this paper, formulations are made in time domain with applications to some problems the results of which are known in frequency domain. And the results of both domains are compared to show the characteristics and validity of time domain solutions. The radiation forces acting on a three dimensional body within the framework of a linear theory. If the linearity of entire system is assumed, radiation forces due to arbitrary ship motions can be expressed by the convolution integral of the arbitrary motion velocity and the so called impulse response function. Numerical calculations are done for some bodies of simple shapes and Series-60[$C_B=0.7$] ship model. For all cases, integral equation techniques with transient Green's function are used, and velocity or acceleration potentials are obtained as the solution of the integral equations. In liner systems, time domain solutions are related with frequency domain solutions by Fourier transform. Therefore time domain solutions are Fourier transformed by suitable relations and the results are compared with various frequency domain solutions, which show good agreements.