• Journal of Korean Society of Transportation
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• v.21 no.1
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• pp.127-136
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• 2003

Road safety is defined under the minimum design standard and design examination process is consisted of the standard according to current road design. However, road safety in practical way is correlative to not only all element of roads but also road shape, such as, between straight line and curved line and between curved lines. Also. it is related to alignments such as horizontal alignment and vertical alignment, and cross section. That is, the practical road design should be examined in both sides of 3 dimension and consecutiveness (consistency) as the actual road is a 3 - dimensional successive object. The paper presents a concept for acceleration to evaluate consistency of road considering actual road shape on 3-dimension. Acceleration of vehicle is influential to road consistency based on running state of vehicles and state of drivers. The magnitude of acceleration. especially, is a quite influential element to drivers. Based on above, the acceleration on each point on 3-D road can be calculated and then displacement can be done. Computation of acceleration means total calculation on each axis. Speed profile refers to “Development of a safety evaluation model for highway horizontal alignment based on running speed(Jeong, Jun-Hwa, 2001)” and then acceleration can be calculated by using the speed pronto. According to literature review, definition of acceleration on 3-D and g-g-g diagram are established. For example, as a result of the evaluation, if the acceleration is out of range, the road is out of consistency. The paper shows calculation for change of acceleration on imaginary road under minimum design standard and the change tried to be applied to consistency. However accurate acceleration is not shown because the speed forecasting model is limited and the paper did not consider state of vehicles (suspension, tires and model of vehicles). If speed pronto is defined exactly, acceleration is calculated on all road shapes, such as. compound curve and clothoid curve. and then it is appled to consistency evaluation. Unfortunately, speed forecasting model on 3 -D road and on compound curves have rarely presented. Speed forecasting model and speed profile model need to be established and standard of consistency evaluation need to developed and verified by experimental vehicles.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.132-137
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• 2011

Many studies are being conducted to improve high speed, light weight and safety of passenger. To improve safety of rolling stock, safety of running performance is most important, and optimizing flow lubrication in driving gear is essential. This study simulates lubricant flow change in driving gear casing which is splashed by the surface of low speed gear teeth following rotational direction of driving gear unit for EMU by using CFD analysis, and based on analysis detail, non-load actual test is conducted for similar driving condition to find out suitability of analysis, selection of lubricate and stability of driving gear.

• Preventive Nutrition and Food Science
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• v.21 no.1
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• pp.44-51
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• 2016

The objective of this study was to determine the factors responsible for the changed physiochemical properties of unpeeled shrimp treated in cold phosphate solution ($2{\sim}4^{\circ}C$) with the intervention of 4 factors: phosphate concentration, dipping time, rotation speed, and volume of brine solution. Response surface analysis was used to characterize the effect of the phosphate treatment on shrimps by running 33 treatments for optimizing the experiment. For each treatment, phosphate amount, moisture content, and weight gain were measured. The results showed that phosphate concentration is the most important factor than other factors for facilitating phosphate penetration in the meat of the shrimp and for getting the best result. The optimum condition of phosphate-treated shrimp in this study was 110 to 120 min dipping time, 500 to 550 mL brine solution for 100 g shrimp sample, and 190 to 210 rpm agitation speed. The studied conditions can be applied in fisheries and other food industries for good phosphate treatments.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.66.1-66.1
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• 2015

We present the first observational detection of radial and azimuthal oscillations in full halo coronal mass ejections (HCMEs). We analyze nine HCMEs well-observed by LASCO from Feb 2011 to Jun 2011. Using the LASCO C3 running difference images, we estimated the instantaneous apparent speeds of the HCMEs in different radial directions from the solar disk center. We find that the development of all these HCMEs is accompanied with quasi-periodic variations of the instantaneous radial velocity with the periods ranging from 24 to 48 mins. The amplitudes of the instant speed variations reach about a half of the projected speeds. The amplitudes are found to anti-correlate with the periods and correlate with the HCME speed, indicating the nonlinear nature of the process. The oscillations have a clear azimuthal structure in the heliocentric polar coordinate system. The oscillations in seven events are found to be associated with distinct azimuthal wave modes with the azimuthal wave number m=1 for six events and m=2 for one event. The polarization of the oscillations in these seven HCMEs is broadly consistent with those of their position angles with the mean difference of $42.5^{\circ}$. The oscillations may be connected with natural oscillations of the plasmoids around a dynamical equilibrium, or self-oscillatory processes, e.g. the periodic shedding of Alfvenic vortices. Our results indicate the need for advanced theory of oscillatory processes in CMEs.

• Journal of the Korean Solar Energy Society
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• v.32 no.6
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• pp.37-43
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• 2012

Long-term variations in wind speed and capacity factor(CF) on Seongsan wind farm of Jeju Island, South Korea were derived statistically. The selected areas for this study were Subji, having a year wind data at 30m above ground level, Sinsan, having 30-year wind data at 10m above ground level and Seongsan wind farm, where long-term CF was predicted. The Measure-Correlate-Predict module of WindPRO was used to predict long-tem wind characteristics at Seongsan wind farm. Eachyear's CF was derived from the estimated 30-year time series wind data by running WAsP module. As a result, for the 30-year CFs, Seongsan wind farm was estimated to have 8.3% for the coefficien to fvariation, CV, and-16.5% ~ 13.2% for the range of variation, RV. It was predicted that the annual CF at Seongsan wind farm varied within about ${\pm}4%$.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.4
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• pp.68-76
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• 2006

The minimization of maximum DPF wall temperature and the fast Light-off during regeneration are the targets for the high durability of the DPF system and the high efficiency of regeneration. In order to predict transient thermal response of DPF, one-channel numerical modeling has been adopted. The effect of the ratio of length to diameter(L/D), cell density, the amount of soot loading on temporal thermal response and regeneration characteristics has been numerically investigated under two different running conditions: city driving mode and high speed mode. The results indicate that the maximum wall temperature of DPF increase with increasing 'L/D' in 'High speed mode'. For 'City driving mode', the maximum wall temperature decreases with increasing 'L/D' in the range of $'L/D{\geq}0.6'$. The maximum temperature decreases with increasing cell density because heat conduction and heat capacity are increased. It is also found that the effect of amount of soot loading on light-off time is negligible.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.1
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• pp.63-73
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• 1987

This study is a part of the research on the coupled vibration of train wheel with the stepped thickness and rail. The research was conducted for the purpose of examining the dynamic characteristics of train wheel at the running state and preventing the vibrations of the high speed railway. The stress at the boundary surface of web and rim, .sigma.$_{c}$, was analyzed in consideration of the uniform In-plane compressive stress depending on the conditions of rolling and the In-plane compressive stress depending on the rotation of train wheel. Then the equation of transverse vibration of the annular plate with the stepped thickness was analyzed by Rayleigh-Ritz's method. As a result of study, it was known that the rotational speed increase the natural frequency slightly and the acceleration level highly while the reaction force between train wheel and rail decrease the natural frequency linearly and the critical buckling is generated at n=1.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.12 s.243
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• pp.1597-1604
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• 2005

The identification of a moving noise source is important in reducing the source power of the transport systems such as airplanes or high speed trains. However, the direct measurement using a microphone running with noise source is usually difficult due to wind noise, white the source motion distorts the frequency characteristics of the pass-by sound measured at a fixed point. In this study the relationship between the spectra of the source and the pass-by sound signal is analyzed for an acoustic source moving at a constant velocity. Spectrum of the sound signal measured at a fixed point has an integral relationship with the source spectrum. Nevertheless direct conversion of the measured spectrum to the source spectrum is ill-posed due to the singularity of the integral kernel. Alternatively a differential equation approach is proposed, where the source characteristics can be recovered by solving a differential equation relating the source signal to the distorted measurement in time domain. The parameters such as the source speed and the time origin, required beforehand, are also determined only from the frequency-phase relationship using an auxiliary measurement. With the help of the regularization method, the source signal is successfully recovered. The effects of the parameter errors to the estimated frequency characteristics of the source are investigated through numerical simulations.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.309-312
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• 2003

Though a legged robot has high terrain adaptability as compared with a wheeled vehicle, its moving speed is considerably low in general. For attaining a high moving speed with a legged robot, a dynamically stable walking, such as running for a biped robot and a trot gait or a bound gait for a quadruped robot, is a promising solution. However, energy efficiency of a dynamically stable walking is generally lower than the efficiency of a stable gait such as a crawl gait. In this paper, we present an experimental study on the energy efficiency of a quadruped walking vehicle. Energy consumption of two walking patterns for a trot gait is investigated though experiments using a TITAN-VIII.

• Bulletin of the Korean Space Science Society
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• 2003.10a
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• pp.26-26
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• 2003

During fabrication process for the large space optical surfaces, the traditional bound abrasive grinding with bronze bond cupped diamond wheel tools leaves the machine marks and the subsurface damage to be removed by subsequent loose abrasive lapping. We explored a new grinding technique for efficient quantitative control of precision CNC grinding for space optics materials such as Zerodur. The facility used is a NANOFORM-600 diamond turning machine with a custom grinding module and a range of resin bond diamond tools. The machining parameters such as grit number, tool rotation speed, work-piece rotation speed, depth of cut and feed rate were altered while grinding the work-piece surfaces of 20-100 mm in diameter. The input grinding variables and the resulting surface quality data were used to build grinding prediction models using empirical and multi-variable regression analysis methods. The effectiveness of the grinding prediction model was then examined by running a series of precision CNC grinding operation with a set of controlled input variables and predicted output surface quality indicators. The experiment details, the results and implications are presented.