• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.3
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• pp.51-61
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• 2023

Travel demand estimation of E-Scooter is the start point of solving the regional demand-supply imbalance problem and plays pivotal role in a linked transportation system such as Mobility-as-a-Service (a.k.a. MaaS). Most focuses on developing trip generation model of shared E-Scooter but it is no study on selection of an appropriate zone scale when it comes to estimating travel demand of E-Scooter. This paper aimed for selecting an optimal TAZ scale for developing trip distribution model for shared E-Scooter. The TAZ scale candidates were selected in 250m, 500m, 750m, 1,000m square grid. The shared E-Scooter usage historical data were utilized for calculating trip distance and time, and then applying to developing gravity model. Mean Squared Error (MSE) is applied for the verification step to select the best suitable gravity model by TAZ scale. As a result, 250m of TAZ scale is the best for describing practical trip distribution of shared E-Scooter among the candidates.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.1
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• pp.77-85
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• 1988

A stochchastic analysis procedure of generating floor response spectra for proportionally damped linear systems subject to earthquake loading is presented. Theories of random vibration and mode acceleration method are used in the formulation of governing equations. The structure-oscillator interaction is not considered. It is assumed that the input motions and oscillator responses are stationary Gaussian processes with mean zero. The nonstationary characteristics of earthquake motion are incorporated in the peak factor which is based on Vanmarcke's theory. Floor response spectra for both resonance and non-resonance cases are calculated under the assumption that the peak factors for structure and oscillator are equal to that for ground response spectrum. The validity of this method is demonstrated by comparing the results obtained by proposed method with those by time history analyses. The results obtained by this method are conservative and accurate with tolerable precision. This method saves much computing time compared with time history analysis method.

• Korean journal of food and cookery science
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• v.23 no.3 s.99
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• pp.327-336
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• 2007

Life-style factors often include social relationships as well as consumption, entertainment and dress patterns. They also typically reflect an individual's attitudes, values and worldview. Life-style types have become and an important factor for segmenting customer markets ever since significant relationships between life-style and customers' behavior was proven. This study examined the relationships between the life-styles of young customers' and the important attributes of foodservice encounters. Factors analysis with VARIMAX and K-means cluster analysis were conducted to group the subjects by life-style. According to the factors analysis, four underlying dimensions were identified and labeled: (1) 'actively fashioned', (2) 'luxury picky', (3) 'healthy toward', and (4) 'utilitarian leisure'. Based on the factor scores derived from the factors analysis, the K-means cluster analysis classified three groups as statistically significant using ANOVA(p<0.05). The overall mean score for the 3rd cluster 'trendy-active picky' was higher than the other two clusters, and represented very picky attitudes about foodservice attributes. The 3rd cluster also seemed to apply higher standards to all of the foodservice attributes. By order of importance, the most important attributes of the 2nd cluster 'pursue-utilitarian leisure' were food serving time, automation systems, server's hygienes, employee kindness, time in line, and menu variety. In spite of low concerns for the life-style attributes, the first cluster 'passively indifferent' recognized menu variety, food sanitation, food serving time, server's hygiene, menu price, air circulation, and room temperature as important. These results suggest that young diners in Korea could be classified by their diverse life-styles that are represented as trendy, utilitarian, and indifferent and will hopefully contribute to the foodservice industry's ability to segment customer characteristics by different life-styles in Korea.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.1
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• pp.98-105
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• 2007

In this paper, we propose a timing detector using suboptimal maximum likelihood method. The proposed method has an simple reference signal generator. Additionally, timing detector's gain of the proposed method is the same to Early-Late gate and ML method. We reveal that tracking range of time tracker is narrow because of using data-decision, that is, tracking range is ${\pm}0.06ns$ for the 4-order Gaussian monocycle with 0.7ns pulse width. Therefore we can find that searcher must have very accurate acquisition procedure. When estimating a performance of time tracker, we consider a jitter in transmitter and receiver's pulse generation process as well as background noise. By using computer simulation, we propose mean/variance of timing detector and tracking process. Also we consider a mobility in tracking process, i.e., timing error modeled ramp function. In order to propose a performance of time tracker, we consider only one correlation demodulator.

• Journal of the Korean Society of Safety
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• v.30 no.3
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• pp.38-44
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• 2015

For this study, fire tests were performed targeting household items (Sofa, Drawer, Refrigerator, Washing machine) using a large cone calorimeter (Large Scale Cone Calorimeter, LSC). The data were obtained focusing on the fire characteristic of the data when the actual fire occurs. The study results showed the following mean HRR of the household items; drawer 2843 KW, sofa 2939 KW, washing machine 719 KW, refrigerator 2907 KW, and THR is found in sofa 2202 MJ, drawer 1559 MJ, refrigerator 1193 MJ, washing machine 627 MJ. From the result, it could be found that the sofa can cause significant heat generation when the fire occurs, and the flashover tendency was found relatively high in compartment fire. In addition, a weight of the four our household items was reduced sharply in a similar time (20min before and after) degree after ignition. The drawer and sofa which has a high heat release can be considered to speed up the fire spread as their weight decrease rapidly and showed relatively weak to the fire compared to the refrigerator and washing machine.

• Microbiology and Biotechnology Letters
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• v.9 no.4
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• pp.231-236
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• 1981

Studies were made on the optimal conditions of sterilization for Streptococcus pyogenes treated with heat. The results were as follows: The optimal temperature on growth of Streptococcus pyogenes was 37$^{\circ}C$ and mean generation time was 20 minutes in the logarithmic growth phase. The suspension of Streptococcus pyogenes, adjusted to pH 6-9 and treated with heat at 5$0^{\circ}C$, showed logarithmic death rate. Specific death rate constant(k) values at pH 6-9 were 0.1448, 0.1194. 0.1273 and 0.1707 minute$^{-1}$ , respectively.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.4
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• pp.328-333
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• 2013

Since a slight malfunction of control systems in a nuclear power plant may cause huge catastrophes, such control systems usually have multiple redundancy and reliable features, and their reliability and availability should be analyzed and verified thoroughly. This paper performed the reliability analysis of the SPLC (Safety Programmable Logic Controller) that is under developed as the control systems for the next generation nuclear power plant. One of the key features of SPLC is that it has multiple redundancy modes as faults happen, which means the reliability analysis for one fixed redundant model is not enough to analyze the reliability of SPLC. With considering this reconfigurable concept, FTA (Fault Tree Analysis) was used to capture fault-relationship among sub-modules. The analysis results show that MTTF (Mean Time to Fault) of SPLC is 45,080 hours, which is a about 4.5 times longer than the regulation, 10,000 hours.

• Journal of the Korea Society of Computer and Information
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• v.10 no.5 s.37
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• pp.115-122
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• 2005

W These days, Ubiquitous is coming a more popular tool in mass communications and in advanced countries ubiquitous computing is commercialized. In Korea, we have studied the business models of the ubiquitous computing generation as well. Ubiquitous computing is the environment in which humans and computers coexist and properly work together. I would like to present a service infrastructure for a more efficient context-awareness than computing home networking system in this monograph. In the mean time, they have focused the context-awareness system on identifying users in the designated space and recognition. But I would like to focus on the middleware system structure for more efficient recognition.

• Journal of Navigation and Port Research
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• v.34 no.6
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• pp.429-434
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• 2010

The experimental study of the hull surface roughness on a developing turbulent boundary layer which exposed to a variety of operating environments were investigated by performing particle image velocimetry(PIV) in a circulating water channel. The Reynolds number based on the width of roughness was about Re=1000. the roughness elements used were periodically arranged two-dimensionally. the flow visualization, time-mean velocity fields and vorticity fields to measure the flow characteristics were obtained. The investigation shows that the vortex generation and its progress inside the walls. And the center of the vortex was located at the middle of the height of the surface roughness.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.425-428
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• 2009

We have researched and developed the caricature generation system PICASSO. PICASSO outputs the deformed facial caricature by comparing input face with prepared mean face. We specialized it as PICASSO-2 for exhibiting a robot at Aichi EXPO2005. This robot enforced by PICASSO-2 drew a facial caricature on the shrimp rice cracker with the laser pen. We have been recently exhibiting another revised robot characterized by a brush drawing. This system takes a couple of facial images with CCD camera, extracts the facial features from the images, and generates the facial caricature in real time. We experimentally evaluated the performance of the caricatures using a lot of data taken in Aichi EXPO2005. As a result it was obvious that this system were not sufficient in accuracy of eyebrow region extraction and mouth detection. In this paper, we propose the improved methods for eyebrow region extraction and mouth detection.