• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.219-222
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• 2004

The effects of short fiber and particle hybrid reinforcement on fatigue crack propagation behaviors in aluminum matrix composites have been investigated. Single and hybrid reinforced 6061 aluminum containing same 20 $Al_2O_3\;volume\%$ with four different constituent ratios of short fibers and particles were prepared by squeeze casting method and tested to check the near-threshold and stable crack growth behavior. The fatigue threshold of the composites increased with portion of particle contents and showed the improved crack resistance especially in low stress intensity range. Addition of particle instead of short fiber also increased fracture toughness due to increase of inter-reinforcement distance. These increase in both fatigue threshold and fracture toughness eventually affected the fatigue crack growth behavior such that the crack growth curve shift low to high stress intensity factor value. Overall experimental results were shown that particle reinforcement was enhanced the fatigue crack resistance over the whole stress intensity factor range.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.695-698
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• 2009

Three-dimensional (3D) shape recognition and distance recognition methods utilizing monocular camera systems have been required for field of virtual-reality, computer graphics, measurement technology and robot technology. There have been many studies regarding 3D shape and distance recognition based on geometric and optical information, and it is now possible to accurately measure the geometric information of an object at short range distances. However, these methods cannot currently be applied to long range objects. In the field of virtual-reality, all visual objects must be presented at widely varying ranges, even though some objects will be hazed over. In order to achieve distance recognition from a landscape image, we focused on the use of aerial perspective to simulate a type of depth perception and investigated the relationship between distance and color perception. The applicability of our proposed method was demonstrated in experimental results.

• Journal of Distribution Science
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• v.18 no.3
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• pp.99-106
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• 2020

Purpose: The purpose of this study is to investigate the influence of perceived risk and psychological distance on purchase intention when purchasing a gift. It focuses on social distances and temporal distances, and aims to identify the interactions between these psychological distances and perceived risk. Data were collected through experiments. Research design, data and methodology: The experiment was carried out through the design of 2 (perceived risk: high/low) × 2 (social distance: far / near) × 2 (temporal distance: far / near) between-subjects design. Participants were 241 undergraduates from two universities in Chungnam and Gangwon, and randomly assigned to one of eight groups. Results: It was confirmed that there is a difference in purchase intention according to the risk perceived by consumers when purchasing a gift. In particular, the difference in purchase intention based on the risk perceived by the buyer was found to be greater as the social distance between the gift giver and the recipient is shorter. In addition, it was confirmed that the intention to purchase a gift was simultaneously influenced by three factors: social distance, perceived risk, and time remaining to purchase a gift. In other words, when both temporal distance and social distance were short, the difference in purchase intention according to perceived risk was greatest. Conclusions: The purpose of this study was to examine how the relationship between perceived risk and purchase intention when purchasing a gift varies with psychological distance. This study found that the closer the relationship between the gift purchaser and the beneficiary and the shorter the time remaining before the gift purchase, the greater the difference in the willingness to purchase due to the perceptual risk. In practice, the results of this study can be used to establish sales promotion strategies for various gift products. Above all, the closer the relationship between the gift buyer and the person receiving the gift, the more differentially there should be a guarantee program that can reduce or eliminate the risk perceived by the buyer. There is also a need to use step-by-step product recommendation programs that can reduce perceptual risk depending on the time remaining until a particular season, such as graduation or Christmas.

• The Journal of the Korea Contents Association
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• v.10 no.1
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• pp.192-201
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• 2010

This research deals with expressive definition of visual contents by using the distance between a subject and a screen resolution, and what changes affect the emotion of those looking at the expressive definition. A visual image captured from a HDTV screen was shown to the 61 students attending a university in the Busan area and SAM evaluation method was used to measure 3 different emotions such as pleasant, arousal, and dominance. While comparing different resolution, looking at high resolution contents rather than low resolution resulted in a direction of pleasant, arousal, and dominance. Also showing a different resolution than consistently showing the same resolution had a more volatile emotional effect. Aftermath multiple comparison resulted in a tendency for emotions to become unpleasant and un-arousal when high resolution contents were shown and then switched to a low resolution contents. There was no result of any significance in the control variables. Also on the aftermath multiple comparison on short, medium and long distance between the subject and the screen resolution, short distance had a bigger pleasant, arousal, and dominance emotional numbers than the rest. In a multiple variable verification result, a resolution and the distance of happiness and excitement showed a positive correlation.

• Journal of Korean Society of Transportation
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• v.21 no.3
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• pp.7-14
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• 2003

Statistics shows that 80% of freeway users travel less than 50km, and only 8% of them do over 100km. It means that the freeway is used for commuting. As a result, the freeway is not used efficiently and social cost is high. The current toll system aims for the efficient usage of the freeway by restraining short-distance trips and inducing long-distance ones. Thus, policies such as minimum toll system and discount for long-distance trips have been carried out. However. these two policies take no account of demand management between the freeway and alternative roads. They merely consider the compensation for charge on users, so the assessment of discount rate and distinction of distance are not reasonable. Consequently, not only the effective demand management but also the evaluation of those policies has been difficult to be achieved. The objective of this paper is to analyze those problematic policies and to establish a reasonable and improved toll system. In addition, this study presents the methodology to minimize social cost, which can be achieved by reducing short trips and encouraging long ones on the freeway. A new methodology of freeway toll system is applied and the results are presented.

• Journal of Ocean Engineering and Technology
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• v.36 no.5
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• pp.340-352
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• 2022

This article presents a modeling method for the uncorrelated measurement error of the ultra-short baseline (USBL) acoustic positioning system for aiding navigation of underwater vehicles. The Mahalanobis distance (MD) and principal component analysis are applied to decorrelate the errors of USBL measurements, which are correlated in the x- and y-directions and vary according to the relative direction and distance between a reference station and the underwater vehicles. The proposed method can decouple the radial-direction error and angular direction error from each USBL measurement, where the former and latter are independent and dependent, respectively, of the distance between the reference station and the vehicle. With the decorrelation of the USBL errors along the trajectory of the vehicles in every time step, the proposed method can reduce the threshold of the outlier decision level. To demonstrate the effectiveness of the proposed method, simulation studies were performed with motion data obtained from a field experiment involving an autonomous underwater vehicle and USBL signals generated numerically by matching the specifications of a specific USBL with the data of a global positioning system. The simulations indicated that the navigation system is more robust in rejecting outliers of the USBL measurements than conventional ones. In addition, it was shown that the erroneous estimation of the navigation system after a long USBL blackout can converge to the true states using the MD of the USBL measurements. The navigation systems using the uncorrelated error model of the USBL, therefore, can effectively eliminate USBL outliers without loss of uncontaminated signals.

• Journal of Distribution Science
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• v.7 no.2
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• pp.63-87
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• 2009

The conclusions shown by this study are as follows: Firstly, Despite the similarity of the objective distance caused by the geographic distance and cultural similarities. it is found that the psychic distance factor still exists. Secondly, a new affective factor of psychic distance has been noted. As to the shaping method, even though culture and psychic distance involve homeogenic factors, psychic distance is more complex in that it is affected not only by cultural changes but also by other affective factors. Culture is a very significant factor, which can have an effect on forming psychic distance, but it is short of being a measurement variable for measuring psychic distance. Thirdly, psychic distance can have a direct effect on customers' buying response. If it is just a belief shared among the people of a nation, it can't become an important notion.

• IEMEK Journal of Embedded Systems and Applications
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• v.7 no.2
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• pp.71-78
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• 2012

Based on the Zigbee-based wireless sensor network, I suggest the way to reduce errors between the short distance, improving the accuracy of the presumed distance by revising the deviation of RSSI(Received Signal Strength Indication) values is to estimate the distance using only the RF signal power without the additional hardware. In general, the graph measured by RSSI values shows the proximity values which are ideally reduced in proportion to the distance under the free outdoor space in which LOS(Line-Of-Sight) is guaranteed. However, if the result of the received RSSI values are each substituted to the formula, it can produce a larger margin of error and less accurate measurement since it is based upon the premise that this free space is not affected by reflected waves or obstacles caused by the ground and electronic jamming engendered by the environment. Therefore, the purpose of this study is to reduce the margin of errors between the distances and to measure the proximity values with the ideal type of graph by suggesting the way to revise the received RSSI values in the light of these reflected waves or obstacles and the electronic jamming. In conclusion, this study proves that errors are reduced by comparing the proposed deviation correction method to the revised RSSI value.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.4
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• pp.737-742
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• 2013

The surveillance system has been developed to be intelligent which can judge and cope by itself using human recognition technique. The existing face recognition is excellent at a short distance but recognition rate is reduced at a long distance. In this paper, we analyze the performance of face recognition according to interpolation and face recognition algorithm in face recognition using the multiple distance face images to training. we use the nearest neighbor, bilinear, bicubic, Lanczos3 interpolations to interpolate face image and PCA and LDA to face recognition. The experimental results show that LDA-based face recognition with bilinear interpolation provides performance in face recognition.

• Korean Journal of Applied Biomechanics
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• v.17 no.1
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• pp.17-27
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• 2007

It is essential for gait analysis to know the distance information. The purpose of this study was to investigate the effects of start and finish distance on the gait variable during walking. Six adolescent participated in this study. Start condition was given by six conditions.: walking forward from (1) one step, (2) three steps, (3) five steps, (4) ten steps, (5) one step after standing walk, and (6) three steps after standing walk, before contacting the force plate. Stop condition was given by four conditions. : stop after (1) one step, (2) two steps, (3) three steps, and (4) ten steps, passing force plate. Repeated measured one-way ANOVA was utilized for data analysis, and the significant level was set at .05. The largest change from the difference of gait velocity exists between the variables of ground reaction force. There were no significant differences in spatio-temporal and posture(angle) variables, as well as ground reaction force variables with walking over the three steps. There were significant differences in gait velocity, knee angle at heel contact, vertical impulse and ankle angle at toe off in short distance.