• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.12
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• pp.116-124
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• 2003

According to the convenience and efficiency, IEEE 802.11 WLAN(Wireless LAN) has became rapidly wide-spread on the market. However, QoS support is needed for various multimedia service. In this paper, we consider both MAC method of IEEE 802.11 and IEEE 802.11e and Traffic Category differentiated service by QoS support method. In addition, we study currently existing back-off algorithms in view of comparative analysis. As a result we propose a new back-off algorithm called Collision Rate Based-EDCF. The proposed back-off algorithm confirms the performance by computer simulations in terms of Throughput, and QoS support.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.6
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• pp.28-39
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• 2010

The study aims at offering a solution to the problems of transmission delay and data throughput decrease as the number of contending On-Board Units (OBU) increases by applying CSMA medium access control protocol based upon IEEE 802.11p. In a competition-based medium, contention probability becomes high as OBU increases. In order to improve the performance of this medium access layer, the author proposes EDCA which a adaptive adjustment of the Contention Windows (CW) considering traffic density and data type. EDCA applies fixed values of Minimum Contention Window (CWmin) and Maximum Contention Window (CWmax) for each of four kinds of Access Categories (AC) for channel-specific service differentiation. EDCA does not guarantee the channel-specific features and network state whereas it guarantees inter-AC differentiation by classifying into traffic features. Thus it is not possible to actively respond to a contention caused by network congestion occurring in a short moment in channel. As a solution, CWminAS(CWmin Adaptation Scheme) and ACATICT(Adaptive Contention window Adjustment Technique based on Individual Class Traffic) are proposed as active CW control techniques. In previous researches, the contention probabilities for each value of AC were not examined or a single channel based AC value was considered. And the channel-specific demands of IEEE 802.11p and the corresponding contention probabilities were not reflected in the studies. The study considers the collision number of a previous service section and the current network congestion proposes a dynamic control technique ACCW(Adaptive Control of Contention windows in considering the WAVE situation) for CW of the next channel.

• Journal of Distribution Research
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• v.3 no.1
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• pp.145-158
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• 1998

The selection of proposed sites for the general logistic center of agriculture products would be made the most suitable place by considering the spread of population as real consumers, the prospect of the demand, the expansion of traffic system, the regional, hourly and carring traffic volume and the use of land based urban planning, etc. As the preconsideration, the possible occupant companies have to be selected on the category of business and the district. After posing questions and having interview, several selected regions would be compared and analysed for deciding the most suitable place. The model for the general logistic center of agricultural products must be selected taking key factors approach for choosing key factors at first and referring to many documentary records. And the more, cooperating with the specialists for location selection and making objective questions to concerned companies, the most suitable place is selected by marking high score for the moderate land cost, the low traffic jam, the connection with the back cities and the possible expansion as the general logistic center of agriculture products.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.5
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• pp.38-48
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• 2010

Adverse weather (e.g. strong winds, snow and ice) will probably appear as a more serious and frequent threat to road traffic than in clear climate. Another consequence of climate change with a natural disastrous on road traffic is respond to traffic accident more the large and high-rise bridge zone, tunnel zone, inclined plane zone and de-icing zone than any other zone, which in turn calls for continuous adaption of monitoring procedures. Accident mitigating measures against this accident category may consist of intense winter maintenance, the use of road weather information systems for data collection and early warnings, road surveillance and traffic control. While hazard from reduced road friction due to snow and ice may be eliminated by snow removal and de-icing measures, the effect of strong winds on road traffic are not easily avoided. The purpose of the study described here, was to design of amber information the relationship between traffic safety, weather, user information on road weather and driving conditions in local-scale Geographic. The most applications are the optimization of the amber information definition, improvements to road surveillance, road weather monitoring and improved accuracy of user information delivery. Also, statistics on wind gust, surface condition, vehicle category and other relevant parameters for wind induced accidents provide basis for traffic control, early warning policies and driver education for improved road safety at bad weather-exposed locations.

• Journal of Auto-vehicle Safety Association
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• v.13 no.4
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• pp.53-59
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• 2021

According to the Korean Traffic Accident Analysis System (TAAS), more than 200,000 traffic accidents occur every year. Also, the statistics including auto insurance companies data show 1.3 million traffic accidents. In the case of TAAS, the types of traffic accidents are simply divided into four; frontal collision, side collision, rear collision, and rollover. However, more detailed information is needed to assess for advanced driver assist systems at intersections. For example, directional information is needed, such as whether the vehicle in the car accident way in a straight or a left turn, etc. This study intends to redefine the type of accident with the more clear driving direction and path by referring to the Negligence standards used in automobile insurance accidents. The standards largely divide five categories of car-to-car/motorcycle /pedestrian/cyclist, and highway, and the each category is classified into dozens of types by status of the traffic signal, conflict situations. In order to present more various accident types for auto insurance accidents, the standards are reclassified driving direction and path of vehicles from crash situations. In results, the car-to-car accidents are classified into 33 accident types, car-to-pedestrian accidents have 19 accident types, car-to-motorcycle accidents have 38 accident types, and car-to-cyclist accidents are derived into 26 types.

• Journal of Environmental Science International
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• v.24 no.3
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• pp.303-316
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• 2015

The relationship between urban spatial structures and GHG-AP integrated emissions was investigated by statistically analyzing those from 25 administrative districts of Seoul. Urban spatial structures, of which data were obtained from Seoul statistics yearbook, were classified into five categories of city development, residence, environment, traffic and economy. They were further classified into 10 components of local area, population, number of households, residential area, forest area, park area, registered vehicles, road area, number of businesses and total local taxes. GHG-AP integrated emissions were estimated based on IPCC(intergovernmental panel on climate change) 2006 guidelines, guideline for government greenhouse inventories, EPA AP-42(compilation of air pollutant emission factors) and preliminary studies. The result of statistical analysis indicated that GHG-AP integrated emissions were significantly correlated with urban spatial structures. The correlation analysis results showed that registered vehicles for GHG (r=0.803, p<0.01), forest area for AP (r=0.996, p<0.01), and park area for AP (r=0.889, p<0.01) were highly significant. From the factor analysis, three groups such as city and traffic categories, economy category and environment category were identified to be the governing factors controlling GHG-AP emissions. The multiple regression analysis also represented that the most influencing factors on GHG-AP emissions were categories of traffic and environment. 25 administrative districts of Seoul were clustered into six groups, of which each has similar characteristics of urban spatial structures and GHG-AP integrated emissions.

• The Journal of Korean Medicine
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• v.40 no.2
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• pp.72-88
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• 2019

Objectives: The purpose of this study is to understand the experience of traffic accident patients with serious injury treated with Traditional Korean Medicine (TKM). Methods: This study was conducted on the basis of grounded theory. We recruited 10 participants who had been hospitalized in Dongguk University Bundang Oriental Hospital after traffic accident. Raw data was collected by in-depth interview, and analyzed by using constant comparison. The coding(open-axial-selective) was performed in order to create paradigm and theoretical model, which can explain main theme of this study. Results: Core phenomenon of this study was 'Experiencing TKM treatment as an alternative' and core category was 'Searching for the answer to the management of traffic accident sequela through TKM treatment' Conclusions: For patients with serious injury, 'Experiencing TKM treatment as an alternative' has meaning as the following: First, The absence of accurate radiography and surgical management makes it hard for patients to choose Korean medicine hospital immediately after traffic accident. Second, Effectiveness of TKM treatment should be evaluated in the long term. Third, TKM treatment is superior to Western medicine treatment in managing long-term patients who suffered from serious injury involved in traffic accident. Finally, Cooperative service of the Western medicine and TKM will provide more satisfactory medical care for traffic accident patients.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.4D
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• pp.335-343
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• 2012

In the study, evaluation indicators that should be considered in applying traffic calming schemes were developed, and it was intended to analyze the importance of indicators that should most considered in evaluation traffic calming scheme through AHP analysis on the basis of it. The result of the study is summarized as follows. The result of evaluation indicators may be summarized by dividing into residential area and commercial area. In category, the safety is shown to be more important than other indicators in the analysis when evaluation (residential area is 0.514 and commercial area is 0.439). Importance of evaluation indicators was analyzed in order Average Vehicle Speed, Traffic Accident Severity, and Pedestrian Separation. Residential areas to help keep the safety of pedestrians 'Average Vehicle Speed' as the major indices were derived. In commercial areas were analyzed as an important indicator Pedestrian Separation. Because there are so many pedestrians. When applying the effect of Traffic Calming, residential is greater than the commercial area.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.12
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• pp.520-528
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• 2002

The ATM Forum recently introduced the Guaranteed Frame Rate(GFR) service category GFR service has been designed to support classical best effort traffic such as TCP/IP based traffic. The GFR service not only guarantees a minimum throughput, but also supports fair distribution of available bandwidth to completing VCs. In this paper, we proposed a new buffer management algorithm based on leaky bucket to provide minimum cell rate guarantee and improve fairness. The proposed algorithm reduces complexity and processing overhead of leaky-bucket algorithm to implement easily.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.11a
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• pp.765-768
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• 2004

IEEE 802.110e는 실시간 트래픽의 QoS를 보장하기 위해 제안되었으나 cellular ip network 망에서 발생하는 route update packet과 같은 signaling traffic에 대해서는 아무런 언급을 하고 있지 않다. 따라서 본 논문에서는 IEEE 802.11e draft가 제안하고 있는 4가지의 AC(Access Category)에 따라 signaling traffic 에 대해서도 높은 우선 순위를 할당 함으로서 handoff시 발생하는 packet drop 이 얼마 만큼 줄어드는지를 분석하였다.