• Journal of Advanced Navigation Technology
• /
• v.11 no.3
• /
• pp.239-251
• /
• 2007

This thesis is about the reduction of the power consumption in GPS embedded terminals with periodic position fix to improve the time delay of position determination. In order to improve time delay of position determination during the wireless terminal is powered on, it needs to be set such that it can be periodically recalibrated by the GPS and those recalibrated values need to be saved in the terminal's memory so that it can reduce the time delay from the request of location. By using the trace of the information that's been saved in the terminal's memory, it can be set so that it'll be easier to determine whether the wireless terminal has gone into buildings and have the capability of checking if it has gone into a specific building. Likewise, while the terminal is turned on, in order calibrate the location, it needs to continuously work the GPS engine which leads to a rapid decrease in terminal's idle time. This thesis proposes some solutions regarding these issues - reducing 20 ~ 30% of the battery consumption for GPS visible situation that can occur when the wireless terminal periodically calibrates its location to determine the in-building status, and extending the idle time of the terminal by flexibly using the suggested GPS calibration time method according to wireless terminal's mobility.

• The KIPS Transactions:PartC
• /
• v.11C no.7 s.96
• /
• pp.889-894
• /
• 2004

Most ad-hoc routing protocols such as AODV(Ad Hoc On-Demand Distance Vector) and DSR(Dynamic Source Routing) do not try to search for new routes if the network topology does not change. Hence, with low node mobility, traffic may be concentrated on several nodes, which results in long end-to-end delay due to congestion at the nodes. Furthermore, since some specific nodes are continuously used for long duration, their battery power may be rapidly exhausted. Expiration of nodes causes connections traversing the nodes to be disrupted and makes many routing requests be generated at the same time. Therefore, we propose a load balancing approach called Simple Load-balancing Approach (SLA), which resolves the traffic concentration problem by allowing each node to drop RREQ (Route Request Packet) or to give up packet forwarding depending on its own traffic load. Meanwhile, mobile nodes nay deliberately give up forwarding packets to save their own energy. To make nodes volunteer in packet forwarding. we also suggest a payment scheme called Protocol-Independent Fairness Algorithm (PIEA) for packet forwarding. To evaluate the performance of SLA, we compare two cases where AODV employs SLA or not. Simulation results show that SLA can distribute traffic load well and improve performance of entire ad-hoc networks.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.6
• /
• pp.2604-2611
• /
• 2013

The Personal Rapid Transit(PRT) system has been highly interested in future transportation developments due to its on-demand and optimized door-to-door transport capability. However, the major impediments to the commercialization of PRT are the high cost for construction of infrastructures as opposed to the small transport capacity and difficulty in defining the role of PRT in building a balanced transportation system. In this study, the vertical transfer device for the PRT vehicle is developed to provide more flexible and better compatible urban mobility services between means of transportation, which is expected to meet particular demands in a particular environment. This apparatus was initially designed based on the basis of vertical circulating conveyors with steel chains, which is frequently used in logistics. Its advantages are capable of the non-stop loading and reduced head-way time. Most importantly, it was intensified by the additional idea to ensure the stable and reliable transfer of the PRT vehicle fully loaded with passengers. The 1/10-scale prototype was successfully tested to demonstrate a fundamental mechanism of vertical transfer and identify unexpected user requirements prior to a real manufacturing process.

• Journal of KIISE:Information Networking
• /
• v.32 no.3
• /
• pp.415-426
• /
• 2005

Wireless internet, which becomes a hot social issue, has limitations due to the following characteristics, as different from wired internet. It has low bandwidth, frequent disconnection, low computing power, and small screen in user terminal. Also, it has technical issues to Improve in terms of user mobility, network protocol, security, and etc. Wireless internet server should be scalable to handle a large scale traffic due to rapidly growing users. In this paper, wireless internet proxy server clusters are used for the wireless Internet because their caching, distillation, and clustering functions are helpful to overcome the above limitations and needs. TranSend was proposed as a clustering based wireless internet proxy server but it has disadvantages; 1) its scalability is difficult to achieve because there is no systematic way to do it and 2) its structure is complex because of the inefficient communication structure among modules. In our former research, we proposed the All-in-one structure which can be scalable in a systematic way but it also has disadvantages; 1) data sharing among cache servers is not allowed and 2) its communication structure among modules is complex. In this paper, we proposed its improved scheme which has an efficient communication structure among modules and allows data to be shared among cache servers. We performed experiments using 16 PCs and experimental results show 54.86$\%$ and 4.70$\%$ performance improvement of the proposed system compared to TranSend and All-in-one system respectively Due to data sharing amount cache servers, the proposed scheme has an advantage of keeping a fixed size of the total cache memory regardless of cache server numbers. On the contrary, in All-in-one, the total cache memory size increases proportional to the number of cache servers since each cache server should keep all cache data, respectively.

• The Journal of Korean Philosophical History
• /
• no.29
• /
• pp.179-202
• /
• 2010

In addition to the emphasis on filial piety ethics in everyday life, filial piety obtained a further significance in Confucianism which had the strong sense of ancestor worship. This paper focuses on filial piety as a mechanism of continuity within Confucianism and points out that it owed its development to its connection to agricultural culture. The sedentary life with less mobility forged a relative intimacy among people and filial piety was the actual expression of that kind of intimate affection. Yet, filial piety in Confucianism created a unique culture in terms that it not only stipulated material and emotional support for parents but also expected one's piety to the further ancestors through a memorial service and made its connection to the infinite posterity through sons. From the perspective of Confucianism that established filial piety at the turning point from life to death, the self existing in present was not an isolated self anymore. Yet, one can see another characteristic of Confucianism from that filial piety, based on blood bonds, could move beyond paternalism to broaden itself. It could be expanded to the care for strangers. The aged experience and wisdom through agricultural life begot the insight that the nature made its infinite connections with everything through circulation. As a stone thrown in a pond would enlarge its boundary by drawing larger and larger concentric circles, this thought enabled people to enlarge their affection to their parents to universal humanity. In this enlarged network, though it was natural to make distinctions between the closer and the farther, Confucianism sought to overcome it by establishing oneself upright. Confucianism emphasized the moral cultivation with its filial piety concept that contained the diachronic thought penetrating life and death and the broadened perspective relating everything around. In Confucianism, filial piety provided an important medium in forming a moral subject that penetrated life and death and related self and others. Inherent in it is the Confucius thought of continuity that searched for a paragon of a moral human being regardless of time and space.