• Journal of KIISE:Computing Practices and Letters
• /
• v.16 no.3
• /
• pp.341-345
• /
• 2010

WMN is one of efficient solutions to provide Internet services for users by forming wireless backbone networks with wireless links. The dominant technology for WMNs is the IEEE 802.11, which provides multi-channel and multi-rate capabilities. One of important issues in WMNs is the network capacity and it is essential to design a multi-channel protocol that leverages the network capacity. However, when wireless links that use different data rates operate on the common channel, the performance of high-rate links is severely degraded by the presence of the low-rate links, which is often referred as performance anomaly. In this paper, we propose a Tree-based Channel Assignment (TreeCA) protocol to mitigate the performance anomaly problem by distributing data rates over multiple channels. TreeCA performs channel assignments based on the tree WMN architecture to accommodate the Internet traffics efficiently. Parent nodes on the tree distribute their child nodes over multiple channels so that the performance anomaly is reduced. Through simulations, we observed that the proposed TreeCA outperforms the existing multi-channel protocols for WMNs.

• Journal of the Korea Society for Simulation
• /
• v.18 no.2
• /
• pp.9-17
• /
• 2009

A face database has contained a large amount of facial information data since face recognition was widely used. With the increase of facial information data, the face recognition based on distributed processing method has been noticed as a major topic. In existing studies, there were lack of discussion about the transferring method for large data. So, we proposed a fuzzy logic-based bit compression rate selection method for distributed face recognition. The proposed method selects an effective bit compression rate by fuzzy inference based on face recognition rate, processing time for recognition, and transferred bit length. And, we compared the facial recognition rate and the recognition time of the proposed method to those of facial information data with no compression and fixed bit compression rates. Experimental results demonstrates that the proposed method can reduce processing time for face recognition with a reasonable recognition rate.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.7
• /
• pp.1920-1926
• /
• 2010

Yoon et $al.^1$ presented an approximate mathmatical model to describe ammonia removal from an experimental batch reactor system with gaseous headspace. The development of the model was initially based on assuming instantaneous equilibrium between ammonia in the aqueous and gas phases. In the model, a "saturation factor, $\beta$" was defined as a constant and used to check whether the equilibrium assumption was appropriate. The authors used the trends established by the estimated $\beta$ values to conclude that the equilibrium assumption was not valid. The authors presented valuable experimental results obtained using a carefully designed system and the model used to analyze the results accounted for the following effects: speciation of ammonia between $NH_3$ and $NH^+_4$ as a function of pH; temperature dependence of the reactions constants; and air flow rate. In this article, an alternative model based on the exact solution of the governing mass-balance differential equations was developed and used to describe ammonia removal without relying on the use of the saturation factor. The modified model was also extended to mathematically describe the pH dependence of the ammonia removal rate, in addition to accounting for the speciation of ammonia, temperature dependence of reactions constants, and air flow rate. The modified model was used to extend the analysis of the original experimental data presented by Yoon et $al.^1$ and the results matched the theory in an excellent manner.

• Fashion & Textile Research Journal
• /
• v.19 no.6
• /
• pp.692-700
• /
• 2017

The number of elderly citizens has risen in Korea and resulted in an aging society. Correspondingly, the social interest in the aging population has escalated immensely; however, research or product development on the quality of life for seniors has shortcomings. Healthcare smart clothing is required to help the elderly with changes and weaknesses that follow aging; however, there is unfortunately insufficient amounts available. This study explores the feasibilities of smart clothing for seniors based on a universal design. Based on previous research, we analyzed the universal design theory, body shape characteristics and design requirements for seniors, and heart rate measurement method. The design is different according to body shape and body shape is different between sex, age, and body race; therefore, subjects were limited to 70-74 year old Korean males in this study. This study proposes a guideline for heart rate sensing clothing that satisfies the 'universal design' aspects as well as the functionality of heart sensing, senior's physical characteristics and needs. It has broadened the range of smart clothing, which was once limited to the younger generation and provided a foundation for the development of specialized smart clothing for seniors.

• Journal of the East Asian Society of Dietary Life
• /
• v.16 no.4
• /
• pp.481-487
• /
• 2006

Coupons that restaurants are competitively issuing have considerable effects on company profits, depending on the performance of redemption rate. The purpose of the study is to identify the coupon type that consumers most prefer, among coupon types the most frequently issued restaurants, and to investigate consumers' coupon redemption rate and revisit intention based on brand familiarity. In this study, freshmen and sophomores in the 2-year colleges and the universities located in Seoul and Kyoungi province were sampled by convenience sampling, and surveyed about 3 coupon types (free meal coupon, discount rate coupon, discount price coupon) with 150 copies of questionnaire for each type, totally 450 copies randomly distributed. As a result, relationship between coupon redemption intention and revisit intention based on brand familiarity was that, the higher brand familiarity was, the higher coupon redemption intention and revisit intention were, regardless of coupon types. This study lies in that it approached to discount method, one of the coupon types, by further subdividing into discount rate and discount price, and that redemption intention and revisit intention were studied by taking account of coupon familiarity.

• Journal of Korea Multimedia Society
• /
• v.20 no.3
• /
• pp.465-473
• /
• 2017

Electrocardiogram(ECG) signal is one of the unique bio-signals of individuals and is used for personal authentication. The existing studies on personal authentication method using ECG signals show a high detection rate for a small group of candidates, but a low detection rate and increased execution time for a large group of candidates. In this paper, we propose a hierarchical algorithm that extracts fiducial points based on curvature of ECG signals as feature values for grouping candidates ​and identifies candidates using waveform-based comparisons. As a result of experiments on 74 ECG signal records of QT-DB provided by Physionet, the detection rate was about 97% at 3-heartbeat input and about 99% at 5-heartbeat input. The average execution time was 22.4 milliseconds. In conclusion, the proposed method improves the detection rate by the hierarchical personal authentication process, and also shows reduced amount of computation which is plausible in real-time personal authentication usage in the future.

• Korean Journal of Veterinary Service
• /
• v.22 no.3
• /
• pp.213-220
• /
• 1999

In order to investigate the prevalence of Salmonella spp. from 1992 to 1997 in Inchon, 173 strains of Salmonella spp. were isolated from patients with diarrhea and analyzed them epidemiologically. The results obtained were as follows; 1. The yearly isolation rates were 34.68% (60 strains) in 1996, 20.80%(36 strains) in 1994, 18.50%(32strains) in 1997, 10.40%(18 strains) in 1992 and 9.83%(17 strains) in 1995 and 5.78%(10 strains) in 1993, in order. 2. The isolation rates based on specimen were 84.97%(147 strains) from feces, 14.45%(25 strains) from blood and 0.58%(1 strain) from pus. 3. The highest isolation rate based on age group was at twenties(25.43%) and four-ties(19.65%), fifties(19.08%), teens(15.03%) and thirties(10.98%), in order. 4. Based on the regional distribution, Nam-gu showed the highest isolation rate (20.80%) and followed by Namdong-gu(20.23%), Dong-gu(19.65%) and Yeansu-gu(0.58%), in order 5. Seasonally, the highest isolation rate was from May to September during the investigation. 6. The isolation rate in male(58.96%) was higher than that in female(41.04%).

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.5A
• /
• pp.474-481
• /
• 2010

In this paper, we present an effective cross layer-based video transmission algorithm over multi-hop mobile ad hoc networks. The proposed algorithm selects the most efficient PHY mode of wireless LAN multi-rate service at each node in a distributed way based on the available information at application, MAC, and physical layers in order to minimize end-to-end delay and maintain packet loss rate in tolerable range at the receiver. Finally, experimental results are provided to show superior performance of the proposed algorithm.

• The Journal of the Korea Contents Association
• /
• v.12 no.9
• /
• pp.1-8
• /
• 2012

In this paper, we propose a rate-distortion optimization method to improve the coding efficiency of the conventional 3D-DCT based compression method using adaptive block mode selection for integral images. In the conventional 3D-DCT based compression method, 3D-DCT blocks of variable block sizes are adaptively selected depending on the characteristics of integral images, and then 3D-DCT is performed. The proposed method applies a rate-distortion optimization to determine the optimal block mode. In addition, we suggest the optimal Lagrangian parameter for integral images. Experimental results show that the proposed method gives bit-rate reduction of about 5%.

• Journal of Korean Society of Water and Wastewater
• /
• v.33 no.6
• /
• pp.481-489
• /
• 2019

As aeration is an energy-intensive process, its control has become more important to save energy and to meet strict effluent limits. In this study, predictive aeration control based on the respirometric method has been applied to the sequencing batch reactor (SBR) process. The variation of the respiration rate by nitrification was great and obvious, so it could be a very useful parameter for the predictive aeration control. The maximum respiration rate due to nitrification was about 60 mg O₂/L·h and the maximum specific nitrification rate was about 7.5 mg N/g MLVSS·h. The aeration time of the following cycle of the SBR was daily adjusted in proportion to that which was previously determined based on the sudden decrease of respiration rate at the end of nitrification in the respirometer. The aeration time required for nitrification could be effectively predicted and it was closely related to influent nitrogen loadings. By the predictive aeration control the aerobic period of the SBR has been optimized, and energy saving and enhanced nitrogen removal could be obtained.