• Journal of Korea Spatial Information System Society
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• v.5 no.2 s.10
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• pp.69-82
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• 2003

Mobile transactions updating spatial objects are long transactions that update local objects of mobile clients during disconnection. Since a recovered transaction cannot read the write sets of other transactions committed before the recovery due to disconnection, the recovered transaction may conflicts with them. However, aborting of the recovered long transaction leads to the cancellation of all updates including the recovered updates. It is definitely unsuitable to cancel the recovered updates due to the conflicts. In this paper, we propose the recovery scheme to retrieve foreign conflictive objects from the write sets of other transactions for reducing aborting of a recovered transaction. The foreign conflictive objects are part of the data committed by other transactions and may conflict with the objects updated by the recovered transaction. In the scheme, since the recovered transaction can read both the foreign conflictive objects and the recently checkpoint read set, it is possible to reupdate properly the potentially conflicted objects.

• Journal of KIISE
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• v.42 no.5
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• pp.652-663
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• 2015

Due to the popularity of location-based services, the amount of generated spatial data in daily life has been dramatically increasing. Therefore, spatial database outsourcing has become popular for data owners to reduce the spatial database management cost. The most important consideration in database outsourcing is meeting the privacy requirements and guarantying the integrity of the query result. However, most of existing database transformation techniques do not support both of the data privacy and integrity of the query result. To solve this problem, we propose a spatial data transformation scheme that utilizes the shearing transformation with rotation shifting. In addition, we described the attack models to measure the data privacy of database transformation schemes. Finally, we demonstrated through the experimental evaluations that our scheme provides high level of data protection against different kinds of attack models, compared to the existing schemes, while guaranteeing the integrity of the query result sets.

• Journal of the Korea Society of Computer and Information
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• v.26 no.1
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• pp.93-101
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• 2021

In this paper, a vehicle license plate detection scheme is proposed that uses the spatial attention areas to detect accurately the license plates in various real-road situations. First, the previous WPOD-NET was analyzed, and its detection accuracy is evaluated as lower due to the unnecessary noises in the wide detection candidate areas. To resolve this problem, a vehicle license plate detection model is proposed that uses the candidate area of the license plate as a spatial attention areas. And we compared its performance to that of the WPOD-NET, together with the case of using the optimal spatial attention areas using the ground truth data. The experimental results show that the proposed model has about 20% higher detection accuracy than the original WPOD-NET since the proposed scheme uses tight detection candidate areas.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.4
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• pp.637-645
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• 2015

Recently, a spatial modulation (SM) scheme achieving high throughput based on quaternary quasi-orthogonal sequences (Q-QOSs), referred to as Q-QOS-SM, is presented for $N_t=2^n(n=1,2,{\cdots})$ transmit antennas. In this paper, based on the design approach of the conventional Q-QOS-SM, new improved QO-SM (I-QO-SM) schemes are proposed for 8 transmit antennas. The new schemes employ Q-QOSs of length 4 or 2 unlike of 8 in the original one, which guarantees more information bits to be allocated for antenna index parts compared to the conventional Q-QOS-SM. By computer simulation results, the proposed scheme are shown to enjoy much higher throughputs compared to the conventional other SM schemes for all simulation environments. Finally, we also examine and compare analytically the performances of the new and conventional SM schemes by calculating upper-bounds on BER performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.5A
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• pp.394-401
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• 2007

MIMO transmission systems can have various transmission modes, which result from the various combinations of the antenna diversity with spatial multiplexing. In this paper, we find the optimal mode to maximize the capacity with the BER constraint and the optimal selection (diversity transmission or spatial multiplexing transmission) for transmission of each transmission antenna, if necessary. The computer simulation results show that the proposed scheme has more capacity than the conventional scheme.

• Journal of Environmental Science International
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• v.24 no.11
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• pp.1473-1483
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• 2015

In this study, a digital terrain analysis had been performed for a mountainous watershed having wetlands. In order to consider the impact for wetland in the flow determination algorithm, the Laplace equation is implemented into the upslope accounting algorithm of wetness computation scheme. The computational algorithm of wetland to spatial contribution of downslope area and wetness was also developed to evaluate spatially distributed runoff due to the presence of wetland. Developed schemes were applied to Wangpichun watershed located Chuncuk mountain at Ulzingun, South Korea. Both spatial distribution of wetness and its histogram indicate that the developed scheme provides feasible consideration of wetland impact in spatial hydrologic analysis. The impact of wetland to downslope propagation pattern is also useful to evaluate spatially distributed runoff distribution.

• Journal of Communications and Networks
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• v.13 no.4
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• pp.400-407
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• 2011

Various air indexing and data scheduling schemes for wireless broadcast of spatial data have been developed for energy efficient query processing. The existing schemes are not effective when the clients' data access patterns are skewed to some items. It is because the schemes are based on flat broadcast that does not take the popularity of the data items into consideration. In this paper, thus, we propose a data scheduling scheme letting the popular items appear more frequently on the channel, and grid-based distributed index for non-flat broadcast (GDIN) for window query processing. The proposed GDIN allows quick and energy efficient processing of window query, matching the clients' linear channel access pattern and letting the clients access only the queried data items. The simulation results show that the proposed GDIN significantly outperforms the existing schemes in terms of access time, tuning time, and energy efficiency.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.55 no.2
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• pp.103-109
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• 2006

In this paper, the detection scheme of the spatial coordinates based on stereo camera for a intelligent path planning of an automatic mobile robot is proposed. In the proposed system, face area of a moving person is detected from a left image among the stereo image pairs by using the YCbCr color model and its center coordinates are computed by using the centroid method and then using these data, the stereo camera embedded on the mobile robot can be controlled for tracking the moving target in real-time. Moreover, using the disparity mad obtained from the left and right images captured by the tracking-controlled stereo camera system and the perspective transformation between a 3-D scene. and an image plane, depth information can be detected. Finally, based-on the analysis of these calculated coordinates, a mobile robot system is derived as a intelligent path planning and a estimation.

• Journal of Korean Association for Spatial Structures
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• v.19 no.2
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• pp.17-25
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• 2019

In this study, we propose a new scheme of nonlinear analysis for Incheon International Airport Terminal-2 which was opened on January of 2018 for the Olympic Winter Games of PyeongChang in South Korea. The terminal was built by a single layered irregular space frame. It has hard problems for nonlinear analysis geometrically, because of a limitation of personal computer's ability by the number of rigid joints in the roof. Therefore we attempt easier approach to be chosen a center part of the roof instead of the whole structure, and to substitute the other boundary parts as springs. The scheme shows some merits for saving memory and calculation time and so on.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.33-36
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• 2007

Acoustic holography exhibits the spatial distribution of sound pressure in time or frequency domain. The obtained picture often contains far more than what we need in practice. For example, when we need to know only the locations and overall propagation pattern of sound sources, a method to show only what we need has to be introduced. One way of obtaining the necessary information is to use envelope in space. The spatial envelope is a spatially slowly-varying amplitude of acoustic waves which contains the information of sources' location. A spatial modulation method has been theoretically developed to get a spatial envelope. By applying the spatial envelope, not only the necessary information is obtained but also computation time is reduced during the process of holography. The spatial envelope is verified as an effective visualization scheme in time domain by being applied to complicated sound fields.