• Journal of the Korean Operations Research and Management Science Society
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• v.28 no.2
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• pp.75-89
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• 2003

Media Access Control (MAC) Protocol in IEEE 802.11 Wireless LAN standard supports two types of services, synchronous and asynchronous. Synchronous real-time traffic is served by Point Coordination Function (PCF) that implements polling access method. Asynchronous nonreal-time traffic is provided by Distributed Coordination Function (DCF) based on Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol. Since real-time traffic is sensitive to delay, and nonreal-time traffic to error and throughput, proper traffic scheduling algorithm needs to be designed. But it is known that the standard IEEE 802.11 scheme is insufficient to serve real-time traffic. In this paper, real-time traffic scheduling and admission control algorithm is proposed. To satisfy the deadline violation probability of the real time traffic the downlink traffic is scheduled before the uplink by Earliest Due Date (EDD) rule. Admission of real-time connection is controlled to satisfy the minimum throughput of nonreal-time traffic which is estimated by exponential smoothing. Simulation is performed to have proper system capacity that satisfies the Quality of Service (QoS) requirement. Tradeoff between real-time and nonreal-time stations is demonstrated. The admission control and the EDD with downlink-first scheduling are illustrated to be effective for the real-time traffic in the wireless LAN.

• Electronics and Telecommunications Trends
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• v.19 no.5 s.89
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• pp.114-124
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• 2004

유선 네트워크, 무선 이동통신 네트워크, 인터넷 등을 통합하는 유무선 통합 네트워크(BcN)에서는 VoIP기술을 사용하게 될 것이다. TTA 표준으로 2004년 7월에 제정된 VoIP 계층형 광대역 고품질 음성 코덱은 핵심계층에 G.711, G.723.1, G.729를 사용하므로 10종의 PT 를 설정하여 코덱을 협상한다. 이로 인하여 자기자신의 코덱 이외에도 G.711, G.723.1, G.729 등과 상호 호환이 되는 장점을 갖는다. 본 고는신규로 제정된 VoIP 계층형 광대역 고품질 음성 코덱을 네트워크에서 사용할 수 있도록 호 처리에 대한표준화를 추진하여야 하는데 이를 위한 표준 기술을 설명하고, 코덱과 호처리 관계 및 표준화 기술을 근거로 한 코덱 협상 처리 기술을 설명한다. 코덱 협상 처리 기술로서 PSTN/MSC 연동 코덱 협상 방안과All IP 코덱 협상 방안으로 구분하였다. All IP 코덱 협상 방안에서는 발신, 착신, MGC, 착신서버에서 호환성을 위한 호 처리 기능을 제공한다. 본 고의 호 처리 기술을 적용하면, VoIP 계층형 광대역 고품질 음성코덱은 기존 네트워크 장치 기능을 수정하지 않고 사용할 수 있다.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.25 no.3
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• pp.16-27
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• 2002

This paper is mainly interested in customer's(fan's) royalty to professional sports in sports industry. The royalty is studied with the royalty to several products and a service, so that we can obtain the comparison between both the former and the latter royalty. Interested professional sports, products and service are baseball, basketball, soccer, beer, cu, cola/cider, etc, and we will call each of them 'item'. The seven related hypotheses are considered. In hypotheses the dependent variable is royalty to nine items, and the independent variables are rune items, and customer's sex and major. For testing hypotheses, a questionaire is used, and reliability is checked with Cronbach's Alpha and correlation coefficients. For some items the royalty is significantly strong. Rather, even if some item has bad quality, it is found that customers can be royal to that item. We can identify some of those items through the results of this study. The strong significant results will be useful for the customer management. Additional studies are required for nonsignificant results which seems to be useful, and they are noted in the final part of the paper.

• The Transactions of the Korea Information Processing Society
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• v.7 no.10
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• pp.3218-3225
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• 2000

In this paper, the performance of the MMSE multiauser deteclor was analyzed with the SNR from the standpoint of the exproient, according to the multiuser, In was analyzed not only at the AWGN channel, but at the fading channel also. With the result of this test, the MMSE multiuser detector showed better performance of multi-connection interference in comparison with comon deterctors. However, its disadvantageis that the hardware turns out to be too complicated and that it requires too many calculations. Because of multi-connectioninterference that happens as a result of spreading code horizontally, the DS/CDMA system, which contatins the same frequency and time, turns out to thve interference according to the quality of the call and the number of users. In order to solve these problems, an adaptive MMSE multiuser detector is suggested. To increase the system's processing gain, the hardware's complexity can be reduced by establishing the number of taps wirhin the detector.

• The KIPS Transactions:PartC
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• v.13C no.7 s.110
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• pp.933-938
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• 2006

Different multimedia services over networks not only require different amounts of bandwidth but also have different Qualify of Service (QoS) requirements. For example, QoS guarantees for higher priority calls is an important issue in multimedia communication networks. In this paper, we develop an adaptive bandwidth management algorithm, which is able to provide QoS guarantees for higher priority calls while accommodating as many heterogeneous multimedia call connections as possible. Our scheme, based on reservation and bandwidth adaptation, manages bandwidth based on real time estimates of current network conditions. Simulation results indicate the superior performance of our scheme providing excellent trade off between contradictory requirements.

• The Korean Journal of Emergency Medical Services
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• v.22 no.3
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• pp.47-54
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• 2018

Purpose: The purpose of this study was to present evidence for quality management based on analysis of patient transportation and response intervals among emergency medical squads. Methods: The chi-square test was used to determine whether mental status and patient assessment affected direct medical control and hospital destination. One way analysis of variance was used to compare response intervals depending on mental status and patient assessment using data drawn from 1172 prehospital care reports. Results: There was a statistically significant relationship between mental status and direct medical control (p<.001); there was a statistically significant relationship between patient assessment and hospital destination (p=.011). However, there was no statistically significant relationship between mental status and hospital destination. The interval from arrival at the patient's side to departure from the scene showed a statistically significant difference (p<.001, p<.001), however, it took the longest time (16.8 minutes) in unresponsive patients. It showed a statistically significant difference (p<.001) in the interval from arrival at patient's side to departure from the scene depending on patient assessment; however, it took the longest time (9.6 minutes) in emergency patients. Conclusion: There was call for direct medical control based on patient assessment; however, patient transportation and response intervals were not appropriate.

• Journal of the Korea Safety Management & Science
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• v.22 no.1
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• pp.9-14
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• 2020

Artificial intelligence (AI) has been applied to most industries by enhancing automation and contributing greatly to efficient processes and high-quality production. This research analyzes the applications of AI-based automobile accident prevention systems. It deals with AI-based collision prevention systems that learn information from various sensors attached to cars and AI-based accident detection systems that automatically report accidents to the control center in the event of a collision. Based on the literature review, technological and institutional changes are taking place at the national levels, which recognize the effectiveness of the systems. In addition, start-ups at home and abroad as well as major car manufacturers are in the process of commercializing auto parts equipped with AI-based collision prevention technology.

• Journal of Smart Tourism
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• v.2 no.4
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• pp.5-10
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• 2022

CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) is everywhere. This research explores whether and how travelers' upfront exposure to a CAPTCHA influences their subsequent behaviors. In the travel decision-making context, we investigated the relationship between CAPTCHA and travelers' hotel preferences and intent to use cryptocurrency during the trip. In two experimental studies, we found that travelers exposed to a CAPTCHA (vs. not) preferred a robot-staffed to a human-staffed hotel (Study 1) and a pro-environmental to a quality hotel (Study 2). Exposure to a CAPTCHA also influences travelers' intent to use cryptocurrency during travel (Study 2). Preference for a pro-environmental hotel does not depend on the formats of CAPTCHA ("I am not a robot" or "I am human") while intent to use cryptocurrency is higher when travelers were exposed to the "I am not a robot" than "I am human" CAPTCHA. The results of two exploratory studies suggest several potential mechanisms by which CAPTCHAs affect travelers' behaviors and call for more research on this topic.

• The Journal of Asian Finance, Economics and Business
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• v.10 no.2
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• pp.223-233
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• 2023

Entrepreneurship brings countless values to each individual and practical benefits to society and the economy. Recently, the call for a better understanding of entrepreneurship from corporations and governments is regularly voiced the day, both in the academic literature and in public discussions. This study examines factors influencing the startup decision of young people in Vietnam. Primary data was collected from an online survey and then imported into an Excel file before being analyzed by SPSS 22. The total number of relevant observations for the study is 656, using numerous statistical approaches such as EFA and multiple regression analyses. This study contributes to the existing literature and current practice by suggesting six major determinants of startup intention: self-expectation, personal attitudes, self-competency, perceived feasibility, entrepreneurial orientation, and financial wealth. Among these factors, self-competency and entrepreneurial orientation are statistically significant, indicating that the capability of young people is the most important determinant of their startup intention. Additionally, the results indicate that self-expectation, attitude, perceived feasibility, and finance do not impact students' intention to pursue entrepreneurship. We suggest that by enhancing the training quality of universities, young people will be provided with much essential knowledge and technical skills for running a business.

• Journal of the Korea Society for Simulation
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• v.19 no.4
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• pp.89-98
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• 2010

In the heterogeneous system of various wired or wireless network with IP-based backbone, the continuities of agreedon QoS for multimedia services should be guaranteed regardless of network types and terminal mobility through seamless vertical handover. This paper proposes a QoS provisioning mechanism called D-ISHO which guarantees the continuities of agreed-on QoS and seamless for multimedia services by considering both such characteristics as delay, loss rate and jitter per each service and such status as available band-width, call arrival rate and data transmission rate during the vertical handover. Simulation is done for performance analysis with the measure of handover failure rate and packet loss rate.