• International Journal of Automotive Technology
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• v.7 no.5
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• pp.609-618
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• 2006

This paper presents the lateral control of an autonomous vehicle by using a look-ahead sensing system. In look-ahead sensing by an absolute positioning system, a reference lane, constructed by straight lanes or circular lanes, was switched by a segment switching algorithm. To cope with sensor noise and modeling uncertainty, a robust LMI-based $H_{\infty}$ lateral controller was designed by the feedback of lateral offset and yaw angle error at the vehicle look-ahead. In order to verify the safety and the performance of lateral control, a scaled-down vehicle was developed and the location of the vehicle was detected by using an ultrasonic local positioning system. In the mechatronic scaled-down vehicle, the lateral model and parameters are verified and estimated by a J-turn test. For the lane change and reference lane tracking, the lateral controllers are used experimentally. The experimental results show that the $H_{\infty}$ controller is robust and has better performance compared with look-down sensing.

• Journal of Distribution Science
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• v.16 no.5
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• pp.45-59
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• 2018

Purpose - This paper aims to analyze the distinct pattern of clustering of imported automobile distributors and provide evidence for the phenomenon using Korean data. Research design, data, and methodology - In this paper, we use data from Korea Automobile Importers & Distributors Association of 23 foreign automobile brands to evaluate the degree of concentration of showrooms using locational Gini index. We identify possible causes for the high level of clustering from two perspectives; 1) on the distributors' side and 2) on the customers' side. Results - We find a very strong locational concentration of imported automobile showrooms within close vicinity in the major cities and districts in Korea. Locational Gini coefficients are 0.1024 at the national level, 0.1836~0.3763 at city level, and 0.3941~0.4311 at district level on a [0,0.5] scale. Conclusions - Luxury foreign automobile customers tend to shop extensively around multiple brands prior to their ideal model selection. Accordingly, the imported automobile distributors cluster together close to their direct competitors in order to give a good comparison opportunity for the potential customers. This will maximize the probability of the visits of potential customers and lead to successful sales performance.

• Computers and Concrete
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• v.22 no.3
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• pp.319-326
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• 2018

RC (Reinforced Concrete) members are always subjected to loading conditions and have construction joints when constructed on a big scale. Service life for RC structure exposed to chloride attack is usually estimated through chloride diffusion test in sound concrete, however the test is performed without consideration of effect of loading and joint. In the present work, chloride diffusion coefficient is measured in concrete cured for 1 year. In order to evaluate the effect of applied load, cold joint, and mineral admixtures, OPC (Ordinary Portland Cement) and 40%-replaced GGBFS (Ground Granulated Blast Furnace Slag) concrete are prepared. The diffusion test is performed under loading conditions for concrete containing cold joint. Investigating the previous test results for 91 days-cured condition and the present work, changing diffusion coefficients with applied stress are normalized considering material type and cold joint. For evaluation of service life in RC continuous beam with 2 spans, non-linear analytical model is adopted, and service life in each location is evaluated considering the effects of applied stress, cold joint, and GGBFS. From the work, varying service life is simulated under various loading conditions, and the reduced results due to cold joint and tensile zone are quantitatively evaluated. The effect of various conditions on diffusion can provide more quantitative evaluation of chloride behavior and the related service life.

• Wind and Structures
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• v.30 no.3
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• pp.219-229
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• 2020

Net pressures on roofs and walls of buildings are dependent on the internal and external pressure fluctuations. The variation of internal and external pressures are influenced by the size and location of the openings. The correlation of external and internal pressure influences the net pressures acting on cladding on different parts of the roof and walls. The peak internal and peak external pressures do not occur simultaneously, therefore, a reduction can be applied to the peak internal and external pressures to obtain a peak net pressure for cladding design. A 1:200 scale wind tunnel model study was conducted to determine the correlations of external and internal pressures and effective reduction to net pressures (i.e., net pressure factors, F_C) for roof and wall cladding. The results show that external and internal pressures on the windward roof and wall edges are well correlated. The largest ${\mathcal{C}}_{{\check{p},net}$, highest correlation coefficient and the highest F_C are obtained for different wind directions within 90° ≤ θ ≤ 135°, where the large openings are on the windward wall. The study also gives net pressure factors F_C for areas on the roof and wall cladding for nominally sealed buildings and the buildings with a large windward wall opening. These factors indicate that a 5% to 10% reduction to the action combination factor, K_C specified in AS/NZS 1170.2(2011) is possible for some critical design scenarios.

• Journal of Astronomy and Space Sciences
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• v.26 no.4
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• pp.693-702
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• 2009

A computational fluid analysis was performed on an LOx line system of a liquid rocket engine. The model was created with 3D CAD and imbedded to the 3D CFD program. Before the full scale analysis on the system was carried out, each components with simplified models was analyzed to save time and cost. As a result, the inlet pressure of the gas generator should be compensated with a certain device unless the inlet pressure of the line system is sufficiently high. The flow pattern of the exit of the system was dependant upon the location of the orifice as well as the size. As a whole the line system analyzed met the requirements, and will be tested and confirmed after being manufactured.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.11
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• pp.1098-1102
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• 2014

Localization of aerial vehicles and map building of flight environments are key technologies for the autonomous flight of small UAVs. In outdoor environments, an unmanned aircraft can easily use a GPS (Global Positioning System) for its localization with acceptable accuracy. However, as the GPS is not available for use in indoor environments, the development of a SLAM (Simultaneous Localization and Mapping) system that is suitable for small UAVs is therefore needed. In this paper, we suggest a vision-based SLAM system that uses vision sensors and an AHRS (Attitude Heading Reference System) sensor. Feature points in images captured from the vision sensor are obtained by using GPU (Graphics Process Unit) based SIFT (Scale-invariant Feature Transform) algorithm. Those feature points are then combined with attitude information obtained from the AHRS to estimate the position of the small UAV. Based on the location information and color distribution, a Gaussian process model is generated, which could be a map. The experimental results show that the position of a small unmanned aircraft is estimated properly and the map of the environment is constructed by using the proposed method. Finally, the reliability of the proposed method is verified by comparing the difference between the estimated values and the actual values.

• Journal of Agricultural Extension & Community Development
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• v.14 no.2
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• pp.301-328
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• 2007

The purposes of this study were to classify the silver farming types and to investigate proper crops for silver farmers. Data were collected from 408 farmers returned from the urban area. Descriptive statistics were employed using SPSS/PC windows program. After then, researchers discussed the silver farming patterns and their proper crops, and tried to analyze the silver farming model. Major results were as follows: The farming aims of retirees, urban residents as well as farmers returned from the urban area were various from hobby/ leisure to income generating activities. Fourteen types of silver farming were classified by farming aim and residential area of retirees. Retirees in the hobby/leisure-oriented silver farming type can select and enjoy the various plants, animals, and insects as well as crops due to their small scale. Silver farmers in the self-sufficiency type may select crops for their food. Income-oriented silver farmers may have difficulties in choosing the proper crop. They must consider their income needs, health status and field location. Profit-oriented silver farmers with venture mind can have some business opportunities in the agricultural sectors in spite of severe competition. As the aged silver farmers have poor health, they must keep work safety rules, use the proper work-aids, and utilize the labor-saving farming system.

• Wind and Structures
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• v.30 no.2
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• pp.199-210
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• 2020

Building wind pressure coefficient transiting test is a new method to test the building wind pressure coefficient by using the wind generated by a moving vehicle, which is susceptible to natural wind and other factors. In this paper, the Commonwealth Advisory Aeronautical Research Council standard model with a scale ratio of 1:300 is used as the test object, and the wind pressure coefficient transiting test is repeated under different natural wind conditions to study the influence of natural wind. Natural wind is measured by an ultrasonic anemometer at a fixed location. All building wind pressure coefficient transiting tests meet the test conditions, and the vehicle's driving speed is 72 km/h. The mean wind pressure coefficient, the fluctuating wind pressure coefficient, and the correlation coefficient of wind pressure are used to describe the influence of natural wind on the building wind pressure coefficient transiting test qualitatively and quantitatively. Some rules, which can also help subsequent transiting tests, are also summarized.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.356-361
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• 2003

The objective of this study is a qualitative comparison between line-integrated OH chemiluminescence ($OH{\ast}$) image and its Abel inversion image at different phase of the oscillating pressure field. PIV(Particle Image Velocimetry) measurements were conducted under non-reacting conditions to see the global flow structure. Also NOx emission was measured to investigate the effect of fuel-air premixing on combustion instability and emission characteristics. Experiments were carried out in an atmospheric pressure, laboratory-scale dump combustor operating on natural gas. Combustion instabilities in present study exhibited a longitudinal mode with a dominant frequency of ${\sim}341.8$ Hz, which corresponded to a quarter wave mode of combustor. Heat release and pressure waves were in-phase when instability occurred. Results gave an insight about the location where the strong coherence of pressure and heat release existed. Also an additional information on active control to suppress the combustion instabilities was obtained. For lean premixed combustion, strong correlation between $OH{\ast}$ and NOx emissions was expected largely due to the exponential dependence of thermal NOx mechanism on flame temperature.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.5
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• pp.185-194
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• 2020

The study aims to identify and measure factors affecting the perception of the selling price of luxury apartments in Hanoi. We conducted a questionnaire consisting of 29 observation variables with a 5-point Likert scale. Independent variables were measured from 1 "without effect" to 5 "strongly". Based on the desk review and results of interviews, a total of 500 questionnaires were sent to research participants for collection; 458 of them met standard and were subject to be analyzed. This study employs Cronbach's Alpha test, and regression model. The results of Exploratory Factor Analysis (EFA) and Multiple Regression Analysis (MRA) identify five main determinants influencing the perception of the selling price of luxury apartments in Hanoi, including Physical characteristics of a luxury apartment (PC); Location and position of an apartment (LP); Surrounding Area (SA); Quality of service provided by managers; (QS) and Demographics factor (DF). Based on the findings, some recommendations have been proposed to help the firm leaders design appropriate personnel policies for creating better price satisfaction for customers in the future. On this basis, the authors propose a number of recommendations to improve the quality of luxury apartments, thereby contributing to the development of the market for luxury apartments in Hanoi.