• Fibers and Polymers
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• 제2권2호
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• pp.81-85
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• 2001

The effects of rate of phase separation to ester interchange reactions and the repulsive pair interaction energy on the phase behavior in a phase-separated immiscible polyester blend are investigated using a Monte Carlo simulation method. The time evolution of structure factor and the degree of randomness are monitored as a function of homogenization time. When the phase separation is dominant over ester interchange reactions, the domain size slowly increases with homogenization time. However, when the pair interaction becomes less repulsive, the domain size does not significantly change with homogenization time. On the other hand, when ester interchange reactions are dominant over the phase separation, the homogenization proceeds without a change in the domain size. The higher the extent of phase separation, the lower the increasing rate of the DR. However, when the phase separation is sufficiently dominant, the effect of the extent of phase separation on the increasing rate of the degree of randomness become less significant.

• 반도체디스플레이기술학회지
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• 제3권1호
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• pp.35-39
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• 2004

Statistical design of experiments was successfully employed to investigate the effect of alternating magnetic field on activation of polycrystalline Si (p-Si) doped as n-type using $\textrm{PH}_3$, by full factorial design of three factors with two levels. In this design, the input variables are graphite size, alternating current, and activation time. The output parameter, sheet resistance, is analyzed in terms of the primary effects and multi-factor interactions. Notably, the three-factor interaction is calculated to be a dominant interaction. The interaction between graphite size and activation time and the main effect of current are important effects compared to the other variables and relevant interactions. Alternating magnetic flux activation is proved a significantly beneficial processing technique.

• 한국환경보건학회지
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• 제41권6호
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• pp.438-448
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• 2015

Objectives: This study was performed to examine the effects of storage time and temperature and their interaction on the hygienic quality parameters of shell eggs. Methods: Eggs from 40-week-old Hy-Line Brown hens were sampled immediately after being laid and subjected to storage periods of four weeks at a refrigerated temperature ($4-5^{\circ}C$) or room temperature ($13.0-19.7^{\circ}C$). Interior/exterior qualities were examined every one week. Results: Weight loss was 2.4-3.1%. The initial specific gravity of the eggs was maintained until one week at both temperatures. Air cell size exceeded 4 mm when stored for one week at room temperature, and two weeks at refrigerated temperature. Albumen index and Haugh unit were significantly decreased at both temperatures after one week (p<0.001). Rapidly increased pH of the albumen with one week of storage was observed, regardless of temperature (p<0.001). Extension of the storage for up to four weeks at room temperature resulted in remarkable deterioration of eggshell quality and instrumental color as redness (a). Air cell size, albumen and yolk indices, Haugh unit, pH of albumen and yolk were found to be influenced by storage time and temperature (p<0.001). Interaction effects between storage time and temperature were also significant for air cell size, pH of albumen and yolk (p<0.001). Conclusion: The results suggest that air cell size and pH of albumen and yolk were important parameters influenced by storage time and temperature in shell eggs. Storage time was more influential for air cell size, and temperature for the pH of yolk. Both variables almost equally influenced the pH of albumen.

• 한국생활과학회지
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• 제22권3호
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• pp.485-492
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• 2013

The temperature changes of dumpling(mandu) during cooking process were examined and the effects of time-temperature and/or time-size interactions on internal temperature were studied. Mandu was purchased from local markets and classified by its weight(small, medium, and large). Boiling, steaming, pan frying, and deep fat frying were adopted. Internal temperature was measured with a food thermometer in every one minute. The internal temperature of mandu increased over time in every cooking process(p<0.05). After three minutes the internal temperature of mandu in boiling, pan frying, and deep fat frying reached over at $74^{\circ}C$, which is high enough temperature to kill the harmful bacteria, but not in steaming. The internal temperature of mandu was significantly affected by cooking time, size, and both in boiling, steaming, and deep fat frying(p<0.05). There were significant differences between the internal and surface temperatures of mandu in the cooking processes except pan frying in three minutes(p<0.05). The results of this study indicate three minutes' cooking of the mandu by boiling, pan frying, and deep fat frying is safe enough to eat. However, longer steaming time is needed in order to reach safe temperature. This study also indicates the cooking time and size of mandu appear to be major factors in determining the internal temperature achieved at $74^{\circ}C$. More research is needed to check time to reach a safe temperature in the cooking process of mandu by steaming.

• Structural Engineering and Mechanics
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• 제58권6호
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• pp.1045-1075
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• 2016

Shallow footings are one of the most common types of foundations used to support mid-rise buildings in high risk seismic zones. Recent findings have revealed that the dynamic interaction between the soil, foundation, and the superstructure can influence the seismic response of the building during earthquakes. Accordingly, the properties of a foundation can alter the dynamic characteristics (natural frequency and damping) of the soil-foundation-structure system. In this paper the influence that shallow foundations have on the seismic response of a mid-rise moment resisting building is investigated. For this purpose, a fifteen storey moment resisting frame sitting on shallow footings with different sizes was simulated numerically using ABAQUS software. By adopting a direct calculation method, the numerical model can perform a fully nonlinear time history dynamic analysis to realistically simulate the dynamic behaviour of soil, foundation, and structure under seismic excitations. This three-dimensional numerical model accounts for the nonlinear behaviour of the soil medium and structural elements. Infinite boundary conditions were assigned to the numerical model to simulate free field boundaries, and appropriate contact elements capable of modelling sliding and separation between the foundation and soil elements are also considered. The influence of foundation size on the natural frequency of the system and structural response spectrum was also studied. The numerical results for cases of soil-foundation-structure systems with different sized foundations and fixed base conditions (excluding soil-foundation-structure interaction) in terms of lateral deformations, inter-storey drifts, rocking, and shear force distribution of the structure were then compared. Due to natural period lengthening, there was a significant reduction in the base shears when the size of the foundation was reduced. It was concluded that the size of a shallow foundation influences the dynamic characteristics and the seismic response of the building due to interaction between the soil, foundation, and structure, and therefore design engineer should carefully consider these parameters in order to ensure a safe and cost effective seismic design.

• 대한인간공학회지
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• 제24권3호
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• pp.1-10
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• 2005

The primary objective of this study is to design input methods for assisting button selection tasks on a PDA screen. Familiar methods in the existing computing environments were investigated to develop aiding methods. Factors manipulated in the experiment included aiding method, button size, and users' prior experience with PDAs. A total of sixteen participants examined the usability of button selection tasks. Two types of button selection tasks were used as experimental tasks; one was selecting a target button, and the other was selecting multiple target buttons consecutively. The results showed that the aiding method and the button size had significant effects on the subjective satisfaction as well as the performance. In addition, users' prior experience with PDAs affected the performance significantly. The interaction between the aiding method and the button size was found to have significant effects on the performance. However, the interaction effect between the button size and the PDA experience was significant on the task performance time only for the multiple button selection tasks. Design considerations were proposed based on the experimental results. These can be applied to the PDA interaction design to make the PDAs more usable.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.191-196
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• 2005

In this study, to describe vehicle-track-bridge dynamic interaction phenomena with 1/4 vehicle model, nonlinear Hertzian contact spring and nonlinear contact damper are introduced. In this approach external loads acting on 1/4 vehicle model are self weight of vehicle and geometry information of running surface. The constraint equation on contact surface is implemented by Penalty method. Also, to improve the numerical stability and to maintain accuracy of solution, the artificial damper and the reaction from constraint violation are introduced. A nonlinear time integration method, in this study, Newmark method is adopted for both equations of vehicles and structure. And to reduce the error caused by inadequate time step size, adaptive time-stepping technique is partially introduced. As the nonlinear Hertzian contact spring has no resistance to tensile force, the bouncing phenomena of wheelset can be described. Thus, it is expected that more versatile dynamic interaction phenomena can be described by this approach and it can be applied to various railway dynamic problems.

• 산업경영시스템학회지
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• 제21권45호
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• pp.357-364
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• 1998

This study deals with the performance evaluation of writing for designing handwriting instruments ergonomically. Experimental tests were executed on ballpoint pen., felt-tip pen, pencil, sharp-pencil, and fountain pen for ease of use and reduction of the muscles fatigue. The writing time and the degree of comfort of writing by subjects were measured on the diameters of five writing instruments. The results indicated that the ballpoint pen was rated significantly superior to the others in writing speed attribute and the instrument with the least fatigue was the fountain pen. There was a significant interaction effect between the types of instruments and their size in diameters. The diameter of instruments for considering time and comfort together was verified that the size of 9.5mm was efficient for ballpoint pen, the size of 8.1mm for felt-tip pen, the size of 7.5mm for pencil, the size of 8.2mm for sharp-pencil, and the size of 9.1mm for fountain pen.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.1441-1446
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• 2009

Numerical analysis is a powerful method in evaluating the soil-pile-structure interaction under the dynamic loading, and this approach has been applied to the practical area due to the development of computer technology. Finite Difference Method, one of the most popular numerical methods, is sensitive to the shape and the number of mesh. However, the trial and error approach is conducted to obtain the accurate results and the reasonable simulation time because of the lack of researches about mesh size and the number. In this study, FLAC 3D v3.1 program(FDM) is used to simulate the dynamic pile model tests, and the numerical results are compared with the 1G shaking table tests results. With the different size and shape of mesh, the responses of pile behavior and the simulation time are estimated, and the optimum mesh sizes in dynamic analysis of single pile is studied.

• The Journal of the Acoustical Society of Korea
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• 제25권2E호
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• pp.85-88
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• 2006

Blade-vortex interaction (BVI) is one of the most important phenomena in rotor flow since it causes undesirable intense vibration and noise. Since three dimensional Euler or Navier-Stokes solutions to BVI require very high computational cost, BVI has been approximated by airfoil-vortex interaction (AVI) in chordwise planes. To describe more realistic situations with AVI, three dimensional vortex informations such as position, core size and strength are embedded artificially to Computational Aeroacoustics (CAA) calculation at each computational time step. To implement this requirement, in this paper, a technique called free vortex embedded method was used. And the solution by this method was compared with the solution by conventional method for interaction between freely convected vortex and airfoil. For the application to three dimensional free vortex embedded CAA, two dimensional free vortex embedded CAA method was validated in advance.