• Journal of Korean Society of Transportation
• /
• v.27 no.2
• /
• pp.15-22
• /
• 2009

There exist some limits when we forecast urban railway demand by traditional 4 step model. The first reason is that the model based on socioeconomic data by an administrative unit, 'Dong', yields a 'Dong' unit trip matrix. But a 'Dong' often has two or more stations. The second reason is that urban railway demand by station would be affected rather by station access area on foot than by a 'Dong' unit. So the model based on 'Dong' characteristic data have some inaccuracies in itself. Owing to the limits of the model based on 'Dong' unit data, there exits some difficulty in forecasting urban railway demand by station. So this paper studied two alternatives. The first is to forecast the demand by using the data of station access area on foot rather than 'Dong' unit data. This needs too much time and effort to collect data and analyse them, while the accuracy of the model didn't improve a lot. The second is to adjust the location of 'Dong' centroid and the length of centroid connector link. By this way we can reflect the characteristics of station access area on foot under traditional 4 step model. Comparing the expected demand to the observed data for each station, the result looks like very similar.

• Journal of the Korean housing association
• /
• v.23 no.2
• /
• pp.25-36
• /
• 2012

The purpose of this study is to find out the commercialization characteristics of 2nd class residential district in innercity railway station area as basic research to protect urban residential area against the pressure of commercialization. Through the research that are based on literature, field survey and urban planning map, it analysed the commercialization characteristic of selected three sites under similar urban condition; to be a nearby subway station and to be a famous commercial street in site, etc. The consequences of this study are summarized as follows; First it finds the commercialized lots in all blocks that adjoin blocks of upper class zoning. Second it is in inverse proportion between the commercialization of lots and the distance from subway station to residential block. Third, the corner lot of a block and the access road directly connected collector road are very important factors to spread commercialization to residential area. Finally, it finds the difference of the commercialization degree of 2nd class residential zone according to arrange main commercial street and the 2nd class residential block; vertical arrangement and horizontal arrangement.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.3B
• /
• pp.138-143
• /
• 2005

This paper aims to optimize an access probe algorithm for the CDMA 2000 system. The incremental value of PWR_STEP increases as NUM_STEP as 1dBm±0.2 for access probe of the area with good receiving sensitivity when the mobile station transmits via access channel and does not receive any ACK message. However, for the area with weak receiving sensitivity, according to the algorithm of open-loop power control, the transmitting power amplifier becomes saturated and PWR_STEP incremental value keeps performing access probe to 0dBm±0.2. Therefore interference and battery consumption increases according to the transmission of the mobile station. We have optimized the access probe algorithm according to the receiving sensitivity. We transmit the incremental value of access probe power, with delaying as much RT slot value as indicated by IS-95C standard in case of good receiving sensitivity and with delaying RT+l slot value in case of weak receiving sensitivity. Simulation results showed that the proposed algorithm contributes to decrease of the interference and battery consumption according to the transmitting power of the mobile station and improves the call duration.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.4D
• /
• pp.565-571
• /
• 2006

This study aimed to analyze access mode choice behavior for KTX Passengers. To fulfill the aims of this study, Dong-Daegu Station was selected as a station for a case study. This study takes place in two stages. These are (i) descriptive statistical analysis of transportation status before and after introduction of the KTX, (ii) empirical model estimation for analyzing access mode choice behavior. This study makes use of the data from travel survey from Daegu metropolitan area. The main part of the survey was carried out in the KTX Dong-Daegu station. The data was collected from a sample of 1,800 individuals. The survey data includes the information on travel from Dong-Daegu station to Seoul. From descriptive statistical analysis of transportation status before and after introduction of the KTX, it is found that revealed demand of the KTX is lower than that expected. Moreover, it is found that the low demand of the KTX stems from high cost for the KTX itself and inconvenience( including travel time and cost) of access mode. In order to analyze mode choice behavior for accessing Dong-Daegu station, multinomial logit model structure is used. For the model specification, a variety of behavioral assumptions about the factors which affect the access mode choice, were considered. From the empirical model estimation, it si found that access travel time and access travel cost are significant in choosing access mode. Given the empirical evidence, we see that improvement of access transportation system for Dong-Daegu station is very important for enhancing the use of KTX.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.32 no.5D
• /
• pp.519-525
• /
• 2012

This study suggests 3 different elements to develop a rail station-influenced area effectively. Above all, several typical models of TOD (Transit Oriented Development)are suggested. They consider the land use types around a rail station, characteristics of a rail station whether it serves a single line or multiple lines. a method of developing a rail station-influenced area. Secondly, the optimal level of service is suggested for connection facility and access modes. Finally, the allocation criteria of on-and-off facility to provide convenient transfer activity.

• Proceeding of Spring/Autumn Annual Conference of KHA
• /
• 2011.04a
• /
• pp.147-152
• /
• 2011

The purpose of this study is to find out the commercialization cause of 2nd class residential area in urban center as basic research to protect urban residential area against the pressure of commercialization. Through the research that are based on literature, field survey and urban planning map, it analysed the commercialization cause of selected two sites under similar urban condition ; to be a nearby subway station and to be a famous commercial street in site, etc. The consequences of this study are summarized as follows ; First the distance between subway station and residential block and residential commercialization are in inverse proportion each other. Second, the corner lot of a block and the access street directly connected collector street are very important factors to spread commercialization to residential area. Finally, nevertheless first and second results, there is square zone which is very high rate of commercialization within one regardless the distance between subway and residential block. the maximum range of square zone is assumed about 250 meter based on case study.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.43 no.5 s.347
• /
• pp.113-120
• /
• 2006

This thesis deals with solutions such as coverage area extension, reduction of the shadow region and performance enhancement of handover caused by structural modification of WiBro network. The More far the distance of RAS(Radio Access Station) and SS(Subscriber Station) is in micro cell, the more bad the quality of channel environment becomes owing to radio interference. Consequently, it causes the deterioration of the throughput and also the deterioration of communication quality in many sides. In fact, most users of WiBro are located in the region, the QPSK region which is bad in point of channel quality. It brings the service complaint by user. We select RS(relay station) to solve the matter caused by channel environment in this cell, and extend coverage and improve the performance of handover call blocking.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.7A
• /
• pp.776-785
• /
• 2008

Compared with the existing cellular base station whose radio parameters are configured manually, the small base station named as self-configurable base station configures its radio parameters automatically by the central controller. When installing the self-configurable base station, it should be considered primarily that the seamless coverage for the target area is secured while the signal interference to the existing cellular service area must to be minimized. In order to achieve this, it is very important to select the correct radio parameters, e.g., transmission power and working frequency. In this work, we formulate and solve the optimization problem by using mixed integer programming to optimize the air parameter for the self-configurable base stations.

• The KIPS Transactions:PartC
• /
• v.11C no.2
• /
• pp.219-228
• /
• 2004

Wireless LAN(wireless Local Area Network) is constructed network environment by radio in indoors or outdoors environment and that to use electric wave or light instead of wire to client such as PC(Personal Computer), notebook, PDA in hub(Hub) in technological side. Now, among IEEE 802.11 WG(Working Group), there is TGf(Task Group F) that develop standard protocol between AP's(Access Point). In this group, proposed IAPP(Inter Access Point Protocol) to secure interoperability between AP producing in different manufacturer, this offers seamless connectivity between STA by sharing Security Context information or Layer 2 forwarding information between AP without passing through re-authentication process when STAs(Station) move by protocol to secure mobility between AP that differ in equal serve network. In this paper, I wish to suggest method that change avenue of communication of message to block information leakage that can occur at security message or WEP Key transmission between above AP, and uses public key to offer wireless area security little more.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.9A
• /
• pp.837-843
• /
• 2006

IEEE802.15.3 and IEEE802.15.4 have defined the hybrid MAC protocols based on TDMA and CSMA where a multi-frame TDMA structure is employed so that multiple data frames can be transmitted within one timeslot to guarantee minimum delay bounds of isochroous traffic. However, TDMA has an intrinsic problem that cannot dynamically allocate optimal length of timeslot to each station. Therefore the idle timeslot can be produced by stations when each transmission queue is instantaneously empty during its timeslot, which would waste lots of timeslots especially in the multi-frame TDMA systems. In this paper, we propose a more flexible multiple-access scheme for the multi-frame TDMA system based on the concept of virtual slot which is accessible by every station with the highest priority for slot owner and lower priority for other stations. Finally, our simulation results from various environments show that proposed scheme can achieve magnitude improvement of total system throughput and average message delay by maximizing channel utilization.