• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.7
• /
• pp.475-486
• /
• 2020

The purpose of present study is to identify the regional tourism resources using Webometric network analysis. The study focuses on Suseong area in Daegu metropolitan city. Various kinds of web-based data, for example, hit counts, online news, and public comments, were used to discover hot places and people's responses. The research question is, 'First, what is the optimum level of the search engine for suseong? Second, what is the online appearance of tourist resources in suseong? Which region is the center of tourism with high levels of emergence? Third, what are the main contents of news articles and comments related to the Suseong pond?'. The results show that the search engine optimization level in Suseong is lower than that in other areas in Daegu. In other words, tourism information and contents regarding Suseong are not highly visible on cyber space. Importantly, Suseong pond had the highest online presence. A close analysis of both online news and users' comments on Suseong pond, however, revealed the biggest concern as calling for improving public accessibility to tourism infrastructure. The findings are expected to contribute to policy development and service operation related to tourism resources in Suseong.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.12
• /
• pp.5843-5848
• /
• 2011

To improve the efficiency of the channel spectrum and to reduce the power consumption of the system in EVRC, the voice signal is compressed and transmitted only when the user speaks to. In addition to this, voice frames are divided into three rates 1, 1/2 and 1/8 and each frame is handled differently. For example, we assumed that the input is silence region if the 1/8 rate is used. In this paper, the sections are firstly separated into the voiced speech signal region, unvoiced speech signal region, and silence region by using distribution characteristics of LSP parameters. Then the paper suggested to encode 1 rate for the voiced speech signal, 1/2 rate for the unvoiced speech signal region, 1/8 rate for the silence region. In other words, traditional way of transmission is used when sending full rate in the EVRC. However, when sending half rate, the voice is firstly distinguished between voiced and unvoiced. If the voice is distinguished as voiced, voice is converted into full rate before the transmission. If it is distinguished as silence, EVRC's basic rate is applied. In the experimental results with SNR, ASDM, transmission bit rate measurement, we have demonstrated that voice quality was improved by using the proposed algorithm.

• Journal of KIISE:Computer Systems and Theory
• /
• v.33 no.5
• /
• pp.282-296
• /
• 2006

In a wireless client server environment, data broadcasting is an efficient data dissemination method; a server broadcasts data, and some of broadcasted data are cached in a mobile client's cache to save the narrow communication bandwidth, limited resources, and data access time. A server also broadcasts invalidation reports to maintain the consistency between server data and a client's cached data. Most of existing works on the cache consistency problems simply purge the entire cache when the disconnection time is long enough to miss the certain amount(window size) of IRs. This paper presents a cache invalidation method to increase mobile clients' cache reusability in case of a long disconnection. Instead of simply dropping the entire cache regardless of its consistency, a client estimates the cost of purging all the data with the cost of selective purge. If the cost of dropping entire cache is higher, a client maintains the cache and selectively purge inconsistent data using uplink bandwidth for validation request. The simulation results show that this scheme increases the cache reusability since it effectively considers the update rates and the broadcast frequencies of cached data in estimating the cost of cache maintenance.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.2
• /
• pp.469-475
• /
• 2010

The railway signalling system plays an essential role in the safe and efficient train operation as serving control functions of train operation intervals and train routes. The reliability and safety of the system are very important because the failure of the railway signalling system can lead to train collision or derailment as well as train operation stop. Until now, in railway signalling system the conventional wayside signal mode has been used generally. There are, however, the risk of accidents such as human mistakes caused by that the driver identifies the signal lamp status and controls train speed with the naked eye. It is also necessary to refurbish the obsolete system. Thereby, It is being effective that the onboard signal mode has been recently introduced and applied in order to transmit the speed control information to train by using the computer and communication equipment. It is necessary to switch over the system in a way while providing passengers with an operation service to replace the obsolete signal system. In this paper, we verify the cases through trial assessment which are solved by the way of adding specific functionalities in the problems of interference among the procedure of switch-over processes and a serial of processes for system verification while a train is operated in the new system in parallel to the existing system.

• Journal of Korea Multimedia Society
• /
• v.11 no.5
• /
• pp.685-691
• /
• 2008

Recently with the rapid evolution of the mobile computing and communication technologies, mobile VOD service becomes increasingly important for wireless mobile users. The VOD service is being widely used in various areas of application, such as education, entertainment and business, because it provides users convenience in easily having access to video information at any time in any places. However, in reality, the mobile system has many difficulties in providing the smooth VOD service owing to frequent transfers and cutoffs of clients. The importance of a technique to transmit broadcasting is being stressed as a method for providing stabler mobile VOD service to a large number of clients. This paper is aimed at showing how to reduce demands for server bandwidth and delay of earlier service through performance analysis by suggesting an effective VOD broadcasting transmission technique through channel division in the mobile atmosphere. Many researches have been made about regular broadcasting techniques in particular. This study divides the methods used for assigning channels which have been decided by the size of segments into a group of regular channels and assistant channels using wireless gap-fillers to provide effective VOD services to a large number of clients at the mobile environment using small bandwidth resources. The regular channels transfer regular streams, while assistant channels repeatedly transfer the first segment to reduce early service delay time to receive regular streams. In this way, the study suggests a technique to reduce server bandwidth demand and early service delay time. Through the proposed technique, the server bandwidth demand could be reduced by more than 30 percent and the study continuously shows reduced early service delay time through conducting performance analysis.

• Journal of KIISE:Software and Applications
• /
• v.35 no.12
• /
• pp.789-799
• /
• 2008

For the communication between human and computer in an interactive computing environment, the gesture recognition has been studied vigorously. The algorithms which use the 2D features for the feature extraction and the feature comparison are faster, but there are some environmental limitations for the accurate recognition. The algorithms which use the 2.5D features provide higher accuracy than 2D features, but these are influenced by rotation of objects. And the algorithms which use the 3D features are slow for the recognition, because these algorithms need the 3d object reconstruction as the preprocessing for the feature extraction. In this paper, we propose a method to extract the 3D features combined with the 3D object reconstruction in real-time. This method generates three kinds of 3D projection maps using the modified GPU-based visual hull generation algorithm. This process only executes data generation parts only for the gesture recognition and calculates the Hu-moment which is corresponding to each projection map. In the section of experimental results, we compare the computational time of the proposed method with the previous methods. And the result shows that the proposed method can apply to real time gesture recognition environment.

• KIPS Transactions on Computer and Communication Systems
• /
• v.6 no.9
• /
• pp.397-406
• /
• 2017

In case of using the existing encrypted algorithm for massive data encryption service under the cloud environment, the problem that requires much time in data encryption come to the fore. To make up for this weakness, a partial encryption method is used generally. However, the existing partial encryption method has a disadvantage that the encrypted data can be inferred due to the remaining area that is not encrypted. This study proposes a partial encryption method of increasing the encryption speed and complying with the security standard in order to solve this demerit. The proposed method consists of 3 processes such as header formation, partial encryption and block shuffle. In step 1 Header formation process, header data necessary for the algorithm are generated. In step 2 Partial encryption process, a part of data is encrypted, using LEA (Lightweight Encryption Algorithm), and all data are transformed with XOR of data in the unencrypted part and the block generated in the encryption process. In step 3 Block shuffle process, the blocks are mixed, using the shuffle data stored with the random arrangement form in the header to carry out encryption by transforming the data into an unrecognizable form. As a result of the implementation of the proposed method, applying it to a mobile device, all the encrypted data were transformed into an unrecognizable form, so the data could not be inferred, and the data could not be restored without the encryption key. It was confirmed that the proposed method could make prompt treatment possible in encrypting mass data since the encryption speed is improved by approximately 273% or so compared to LEA which is Lightweight Encryption Algorithm.

• The Journal of the Acoustical Society of Korea
• /
• v.22 no.2
• /
• pp.121-128
• /
• 2003

Acoustic Echo Cancellation(m) is very active research topic having many applications like teleconference and hands-free communication and it employs Double Talk Detector(DTD) to indicate whether the near-end speaker is active or not. However. the DTD is very sensitive to the variation of acoustical environment and it sometimes provides wrong information about the near-end speaker. In this paper, we are focusing on the development of robust DTD algorithm which is a basic building block for reliable AEC system. The proposed AEC system consists of delayless subband AEC and narrow-band DTD. Delayless subband AEC has proven to have excellent performance of echo cancellation with a low complexity and high convergence speed. In addition, it solves the signal delay problem in the existing subband AEC. On the other hand, the proposed narrowband DTD is operating on low frequency subband. It can take most advantages from the narrow subband such as a low computational complexity due to the down-sampling and the reliable DTD decision making procedure because of the low-frequency nature of the subband signal. From the simulation results of the proposed narrowband DTD and wideband DTD, we confirm that the proposed DTD outperforms the wideband DTD in a sense of removing possible false decision making about the near-end speaker activity.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.40 no.4
• /
• pp.193-205
• /
• 2003

There has been so many research activities about robot soccer system in the many research fields, for example, intelligent control, communication, computer technology, sensor technology, image processing, mechatronics. Especially researchers research strategy for attacking in the field of strategy, and develop intelligent strategy. Then, soccer robots cannot defense completely and efficiently by using simple defense strategy. Therefore, intention extraction of attacker is needed for efficient defense. In this thesis, intention extractor of soccer robots is designed and developed based on FMMNN(Fuzzy Min-Max Neural networks ). First, intention for soccer robot system is defined, and intention extraction for soccer robot system is explained.. Next, FMMNN based intention extractor for soccer robot system is determined. FMMNN is one of the pattern classification method and have several advantages: on-line adaptation, short training time, soft decision. Therefore, FMMNN is suitable for soccer robot system having dynamic environment. Observer extracts attack intention of opponents by using this intention exactor, and this intention extractor is also used for analyzing strategy of opponent team. The capability of developed intention extractor is verified by simulation of 3 vs. 3 robot succor simulator. It was confirmed that the rates of intention extraction each experiment increase.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.3
• /
• pp.366-375
• /
• 2008

Generally a return current plane(RCP) of high speed digital and analog part is partitioned. This is achieved in order to decrease the noise interference between subsystem in PCBs(Printed Circuit Boards). However, when the connected signal line exists between each sub system, this partition will cause unwanted effects. In a circuital point of view, RCP partition has a bad influence upon signal integrity. In a EMI(Electromagnetic Interference) point of view, the partition of the return current plane becomes a primary factor to increase the radiated emission. Component bridge(CB) is usecl for the way of maintaining signal integrity, still specific user's guide doesn't give sufficient principle. In a view point of signal integrity, design principle of multi-CB using method will be analyzed by measurement and simulation. And design principle of noise mitigation will be provided. Generally interval of CB is ${\lambda}/20$ ferrite bead. In this study. When multi-CB connection is applied, design principle of ferrite bead and chip resistor is proved by measurement and simulation. Multi-connected chip resistance$(0{\Omega})$ is proved to be more effective design method in the point of signal integrity.