• Journal of the Korean Institute of Landscape Architecture
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• v.38 no.3
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• pp.1-14
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• 2010

Areas with negative images in cities can degrade the image of the city as a whole and slow the city's efforts to improve its image. The identification of such areas and the development of a city contour that charts the images of various areas in advance can help urban planners establish relevant strategies to ameliorate detrimental images of the city. This study intends to draw a contour of Seongnam City according to citizen's cognition levels of and preference for city area images and aim to shift the strategy of urban image planning from being results-oriented to being process-oriented. The results of this study are as follows: First, an analysis of the level of cognition of and preferences for Seongnam City's landmarks shows that the degree of cognition varies in different areas, whereas that of preferences remains similar; Second, the cognition and preference contour makes it easy to assess and diagnose city images; Third, the image management map, which merges the cognition contour with the preference contour, divides the city into four different areas. In order to manage city images, it follows that those areas with a high degree of cognition but low preference need to be classified and dealt with first. Further, this study shows that those areas with high cognition are the most populated and visited. Areas with high preference can become a strong candidate for being a landscape control point of a city, which adds to the usefulness of this study. The contour of Seongnam will contribute to networking sightseeing areas for visitors centered upon those places of high preference. It would appear that this type of networking will inspire a better image for the city.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.6
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• pp.1283-1293
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• 2014

In ubiquitous environment, data are changing rapidly and new data is coming as times passes. And sometimes all of the past data will be lost if there is not sufficient space in memory. Therefore, there is a need to make rules and combine it with new data not to lose all the past data or to deal with large amounts of data. In making decision trees and extracting rules, the weight of each of rules is generally determined by the total number of the class at leaf. The computational problem of finding a minimum finite state acceptor compatible with given data is NP-hard. We assume that rules extracted are not correct and may have the loss of some information. Because of this precondition. this paper presents a new approach for refining rules. It controls their weight of rules of previous knowledge or data. In solving rule refinement, this paper tries to make a variety of rules with pruning method with majority and minority properties, control weight of each of rules and observe the change of performances. In this paper, the decision tree classifier with extended data expression having static weight is used for this proposed study. Experiments show that performances conducted with a new policy of refining rules may get better.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.590-592
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• 2018

Taxis that are illegally parked on the road to catch customer can cause traffic congestion and sometimes cause traffic accidents. Stop position of taxis is determined by the long term experience of taxi drivers. In this study, We provide information to taxi drivers and customer who visit in first time through finding stop position of taxis by time. To do this, we used the Internet of Vehicle (IoV) data collected from sensors installed in 40 taxis. Previous studies attempted by forming a cluster around a taxi. Since this method is centered on a taxi, the position of the cluster changes depending on the location of the taxi. In this study, we use a road segmentation algorithm to solve these problems. Unlike the previous studies, since the cluster is formed around the road, the position of the cluster is fixed and it is not affected by the number of taxis, so it is possible to grasp the stop position in real time. The road segmentation is made up of 30m units, and map the taxi location data divided into hourly, weekday, and weekend to the nearest point. As a result of the mapping, it was difficult to see a big difference in the time of week because there were few taxis to operate on weekends, but in case of weekdays, the difference of stop position between the commute time zone and the night time zone was confirmed. The results of this study suggest that it will be possible to propose the prevention of taxi illegally driving taxi and the location of the taxi stand.

• The KIPS Transactions:PartA
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• v.11A no.2
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• pp.195-202
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• 2004

This paper introduces the design or parallel Pipeline high-speed analog-to-digital converter(ADC) for the high-resolution video applications which require very precise sampling. The overall architecture of the ADC consists of 4-channel parallel time-interleaved 10-bit pipeline ADC structure a]lowing 200MSample/s sampling speed which corresponds to 4-times improvement in sampling speed per channel. Key building blocks are composed of the front-end sample-and-hold amplifier(SHA), the dynamic comparator and the 2-stage full differential operational amplifier. The 1-bit DAC, comparator and gain-2 amplifier are used internally in each stage and they were integrated into single switched capacitor architecture allowing high speed operation as well as low power consumption. In this work, the gain of operational amplifier was enhanced significantly using negative resistance element. In the ADC, a delay line Is designed for each stage using D-flip flops to align the bit signals and minimize the timing error in the conversion. The converter has the power dissipation of 280㎽ at 3.3V power supply. Measured performance includes DNL and INL of +0.7/-0.6LSB, +0.9/-0.3LSB.

• The Transactions of the Korea Information Processing Society
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• v.5 no.12
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• pp.3047-3062
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• 1998

This paper deseribes the desihn and the implementation of the Realtime Transport Protocol(RTP)/ Rdaltime Control Protocol(RTCP) (RFC 1889,1890) that is used to transmit the audio/video data to any destination and to feedback the Quality of Service (QoS) information of the received media data to the sender, in the teleconferencing systems proposed by ITU-T. These protocols are implemented with multi thead technique and run on top of UDP/IP-Multicast through the socket interface as the underlying protocol. The upper layer is impelmented such that in can be accessed by the H245 comference control protocol. The RTP packetizes the digitized audio/video data from the encoder info a fixed format, and multieast to the participants. The RTCP monitors RTP packets and extracts the QoS values from it such as round-trip delay, jiter and packet loss to form RTCP packets and non periokically sends them to the sender site. In this Paper, we also descritx the study of measurement and analysis for QoS factors that observed on performing teleconferencing system over Internet. The results from this experiment is indicate that RTT and Jitter value are acceptable even entwork load is high. However, it appears that packet loss rate is high in daytime and most losses periods have length one or two.

• Korean Chemical Engineering Research
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• v.51 no.5
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• pp.561-567
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• 2013

Mixed hardwood chips were pre-pulping extracted with green liquor prior to kraft pulping in order to recover hemicelluloses for use as biofuels. This green liquor solution containing mainly sodium sulfide and sodium carbonate was applied at different alkali charges (expressed as $Na_2O$) of 0, 1, 3, and 5% on dry wood weight. The extractions were performed at $160^{\circ}C$ for residence times ranging from about 1-2 h to determine the effect of extraction severity on composition of the pre-pulping extract. The severity of hemicellulose extraction time and green liquor charge controls the concentration of acetic acid and monosaccharide sugars available for downstream processing, the accumulation of degradation products such as organic acids and furans in the extract. As the alkali charge was increased, the amount of acetate side chains on the hemicelluloses and the dissolved lignin in the extract increased but the carbohydrate and sugars in the extract decreased appreciably. Hot water extraction (0% alkali addition) released the greatest amount of carbohydrates, up to 29.80 g/L measured as component sugars, but resulted in the greatest decrease in pulp yield. Meanwhile, pre-pulping extraction with 3% green liquor increased the pulp yield while greatly reducing the component sugars to 7.08 g/L. Fundamental data obtained in this study will allow selection of optimum hemicellulose extraction conditions for integrating the extraction operation into the Kraft pulping process.

• Korean Chemical Engineering Research
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• v.51 no.5
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• pp.622-627
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• 2013

Colloidal silica is used in various industrial products such as chemical mechanical polishing slurry for planarization of silicon and sapphire wafer, organic-inorganic hybrid coatings, binder of investment casting, etc. An accurate determination of particle size and dispersion stability of silica sol is demanded because it has a strong influence on surface of wafer, film of coatings or bulks having mechanical, chemical and optical properties. The study herein is discussed on the effect of measurement results of average particle size, sol viscosity and electrophoretic mobility of particle according to the volume fraction of eight types of silica sol with different size and surface properties of silica particles which are presented by the manufacturer. The measured particle size and the mobility of these sol were changed by volume fraction or particle size due to highly active surface of silica particle and change of concentration of counter ion by dilution of silica sol. While in case the measured sizes of small particles less than 60 nm are increased with increasing volume fraction, the measured sizes of larger particles than 60 nm are slightly decreased. The mobility of small particle such as 12 nm are decreased with increase of viscosity. However, the mobility of 100 nm particles under 0.048 volume fraction are increased with increasing volume fraction and then decreased over higher volume fraction.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.12B
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• pp.1022-1036
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• 2004

In mobile cellular network the ever-changing location of a mobile host necessitates the continuous tracking of its current position and efficient management of location information. A database called Home Location Register(HLR) plays a major role in location management in this distributed environment, providing table management, index management, and backup management facilities. The objectives of this paper are to identify the p개blems of the current HLR system through rigorous analysis, to suggest solutions to them, and to propose a new architecture for the HLR system. In the HLR system, a main memory database system is used to provide real-time accesses and updates of subscriber's information. Thus it is suggested that the improvement bemade to support better real-time facilities, to manage subscriber's information more reliably, and to accommodate more subscribers. In this paper, I propose an efficient backup method that takes into account the characteristics of HLR database transactions. The retrieval speed and the memory usage of the two-level index method are better than those of the T-tree index method. Insertion md deletion overhead of the chained bucket hashing method is less than that of modified linear hashing method. In the proposed backup method, I use two kinds of dirty flags in order to solve the performance degradation problem caused by frequent registration-location operations. Performance analysis has been performed to evaluate the proposed techniques based on a system with subscribers. The results show that, in comparison with the current techniques, the memory requirement is reduced by more than 62%,directory operations, and backup operation by more than 80%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.5
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• pp.938-943
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• 2015

The proposed circular patch antenna was designed to include relative bandwidth of above 25% as designed by the FCC in the FCC in the 3.1 ~ 10.6 GHz band. The antenna was induced to have a wide band characteristic through two structures of the usual microstrip line and a microstrip line with a linear change in impedance. The proposed finally antenna was designed using an FR4_epoxy substrate with 4.7% permittivity, 0.02 of loss tangent, and 1.6 mm of thickness, and was simulated with the use of HFSS made by Ansys. Return loss at frequency, VSWR, radiation pattern and the gain of the antenna were analysed. As a result, if satisfied a return loss of -10 dB and $VSWR{\leq}2$ from 2.28 ~ 13.35 GHz, showing about the bandwidth of 11.89 GHz, and the radiation pattern was unidirectional in all bands. The antenna gain gradually increased from 2 ~ 8 GHz and had the highest gain of 7.92 dBi at 8 GHz. and the gain gradually decreased in the 9 ~ 12 GHz band.

• The KIPS Transactions:PartC
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• v.19C no.2
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• pp.135-144
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• 2012

All the servers in a traditional server cluster environment are kept On. If the request load reaches to the maximum, we exploit its maximum possible performance, otherwise, we exploit only some portion of maximum possible performance so that the efficiency of server power consumption becomes low. We can improve the efficiency of power consumption by controlling power mode of servers according to load situation, that is, by making On only minimum number of servers needed to handle current load while making Off the remaining servers. In the existing power mode control method, they used a static policy to decide server power mode at a fixed time interval so that it cannot adapt well to the dynamically changing load situation. In order to improve the existing method, we propose a dynamic server power control algorithm. In the proposed method, we keep the history of server power consumption and, based on it, predict whether power consumption increases in the near future. Based on this prediction, we dynamically change the time interval to decide server power mode. We performed experiments with a cluster of 30 PCs. Experimental results show that our proposed method keeps the same performance while reducing 29% of power consumption compared to the existing method. In addition, our proposed method allows to increase the average CPU utilization by 66%.