• Journal of KIISE
• /
• 제43권11호
• /
• pp.1233-1244
• /
• 2016

In the IoT network environments for LLNs(Low power and Lossy networks), IPv6 Routing Protocol for Low Power and Lossy networks(RPL) has been proposed by IETF(Internet Engineering Task Force). The goal of RPL is to create a directed acyclic graph, without loops. As recommended by the IETF standard, RPL route recovery mechanisms in the event of a failure of a node should avoid loop, loop detection, DIO Poisoning. In this process, route recovery time and control message might be increased in the sub-tree because of the repeated route search. In this paper, we suggested RPL route recovery method to solve the routing overhead problem in the sub-tree during a loss of a link in the RPL routing protocol based on IoT wireless networks. The proposed method improved local repair process by utilizing a route that could not be selected as the preferred existing parents. This reduced the traffic control packet, especially in the disconnected node's sub tree. It also resulted in a quick recovery. Our simulation results showed that the proposed RPL local repair reduced the recovery time and the traffic of control packets of RPL. According to our experiment results, the proposed method improved the recovery performance of RPL.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• 제21권4호
• /
• pp.268-275
• /
• 2020

In domestic mountain resort areas, a catenary system cannot be installed for the protection of the natural environment and view. Therefore, mountain trams must be operated wireless. In this study, a local ground pantograph, which supplies electricity to the battery on board, was developed for this purpose, and its performance was verified by tests. The system is installed on ground at stops or repair shops. While a bogie goes to the pantograph, the arms and collection shoes are raised by a spring force to make contact with the collection bar under the bogie so electric power can be supplied to the battery. Because it is a local ground type, it does not require a roof pantograph and catenary system. The system enables the mountain tram to run wireless. In addition, there is no separation and arc because it collects current while standing at stops or shops. The system has a long life because moving contact, which generates wear and damage to shoes, is avoided. The insulation resistance was above the criteria of 10 ㏁, and there was no abnormal temperature increase when a current of 335A was supplied for one hour.

• Journal of architectural history
• /
• 제12권3호
• /
• pp.87-100
• /
• 2003

This study is on the construction of government office of Dongnaebu through researching the construction reports and historical documents in 19century. Especially it focuses on the local construction system and operation for the government office. Main contents of the study are 1) Scope and process of construction, 2) Architectural administration and official notes, 3) Organization of participants and the feature, 4) Felling trees and transport, 5) Monetary of construction The results are summarized as follows. 1) Repair office customary were the courtesy new provincial man. Government building were inspected and repaired periodically. 2) Administrative system of construction have been operated. There are official notes which are about application, permition and order, concerned works such as logging at the bongsan, means of transport, paying wages and progressing works. 3) Organization of construction was made up of an officer and sangnee to supervise and supply. 4) Due to financial difficulty, local government reserved and appropriated funds with moneylending for building office.

• Archives of Reconstructive Microsurgery
• /
• 제11권1호
• /
• pp.47-52
• /
• 2002

One of the most common problems in cord injury is pressure sores. In the early stage of pressure sores, the wound can be covered by advancing or transpositioning a local myocutaneous flap. However, it can be a great challenge to treat end-stage paraplegic patient who underwent multiple prior flaps, where continuous treatment is needed to prevent recurrent pressure sore due to infection and metabolic drain. In these patients, a local myocutaneous flap may be very difficult for coverage of the wounds. Therefore, hemipelvectomy may be considered. The authors performed a hemipelvectomy on a 33 year-old male paraplegic patient who presented with multiple, large wounds seen in end-stage pressure sores. He had a compression fracture of the lumber spine 9 years ago during a motor vehicle accident. After a wide exicision of the wound, the anterior flap was used as a fillet-flap for reconstruction. On the sixth day postoperatively, secondary repair was done due to wound dehiscence and the postoperative results have been satisfactory thus far.

• Archives of Reconstructive Microsurgery
• /
• 제9권2호
• /
• pp.158-163
• /
• 2000

Over the past several years, countless patients have benefitted from the use of leeches in microsurgery. As we know, leeches are used to overcome the problem of venous congestion by creating prolonged localized bleeding uniquely characteristics of leech bite. Venous congestion, a common complication of digital replantation, often has been treated through surgical repair like arteriovenous anastomosis. The leech produces a number of important substances which contribute to the special property of the bite, including an anticoagulant, a local vasodilator and local anesthetics. The bite usually bleeds for 1 to 2 hours and under special circumstances may bleed for up to 24 hours. So venous congestion is relieved. However, leeches increase the possibility of infection through their gut content. Infection associated medical leech application is significant risk. Other risk include allergic reaction, adverse psychologic reaction and blood loss requiring transfusion. The 65 cases of medical leech application were performed between August, 1997 and May, 2000 according to an established protocol. The complication were 18 cases ; infection (13 cases), hemorrhage (2 cases), allergic reaction (1 case), psychologic problem (1 case) and hypochromic anemia (1 case). Then our study was performed on the base of indication. As a result, Aeromonas hydrophilia was cultured from gut of medical leech and Klebsiella, Staphylococcus and Pseudomonas were cultured from media. We present the clinical risk-benefit of the medical leech therapy through several cases following digital replantation.

• Earthquakes and Structures
• /
• 제11권4호
• /
• pp.649-664
• /
• 2016

A seismic damaged bridge may be hit again by a strong aftershock or another earthquake in a short interval before the repair work has been done. However, discussions about the impact of the unrepaired damages on the residual earthquake resistance of a steel bridge are very scarce at present. In this paper, nonlinear time-history analysis of a steel arch bridge was performed using multi-scale hybrid model. Two strong historical records of main shock-aftershock sequences were taken as the input ground motions during the dynamic analysis. The strain response, local deformation and the accumulation of plasticity of the bridge with and without unrepaired seismic damage were compared. Moreover, the effect of earthquake sequence on crack initiation caused by low-cycle fatigue of the steel bridge was investigated. The results show that seismic damage has little impact on the overall structural displacement response during the aftershock. The residual local deformation, strain response and the cumulative equivalent plastic strain are affected to some extent by the unrepaired damage. Low-cycle fatigue of the steel arch bridge is not induced by the earthquake sequences. Damage indexes of low-cycle fatigue predicted based on different theories are not exactly the same.

• Journal of Information Processing Systems
• /
• 제11권1호
• /
• pp.148-164
• /
• 2015

The use of mobile agents for collaborative processing in wireless sensor network has gained considerable attention. This is when mobile agents are used for data aggregation to exploit redundant and correlated data. The efficiency of agent-based data aggregation depends on the agent migration scheme. However, in general, most of the proposed schemes are centralized approach-based schemes where the sink node determines the migration paths for the agents before dispatching them in the sensor network. The main limitations with such schemes are that they need global network topology information for deriving the migration paths of the agents, which incurs additional communication overhead, since each node has a very limited communication range. In addition, a centralized approach does not provide fault tolerant and adaptive migration paths. In order to solve such problems, we have proposed a distributed approach-based scheme for determining the migration path of the agents where at each hop, the local information is used to decide the migration of the agents. In addition, we also propose a local repair mechanism for dealing with the faulty nodes. The simulation results show that the proposed scheme performs better than existing schemes in the presence of faulty nodes within the networks, and manages to report the aggregated data to the sink faster.

• Journal of Korean Society of Rural Planning
• /
• 제19권1호
• /
• pp.43-54
• /
• 2013

School closings in rural area continue to occur due to drops in population in those areas. Many studies have been done in order to effectively utilize such closed schools. However, there is a lack of studies targeting operators of the closed facilities for revitalization. Therefore, the goal of this research is understanding the real operational status of and finding solutions for the closed schools after studying the current operational status of the closed schools by conducting surveys with their operators. The survey was performed with closed-school-operators in Chungcheongnam-Do as the target; and the analysis was conducted regarding the acquisition type of the closed schools (purchase, lease), building condition, repair and construction status, annual visitors, operational days, operational fees, seasonal ups and downs, operational profits, and satisfaction of local government support. The results showed that there were differences with visitors and operational days along acquisition types as well as low operational profits and seasonal ups and downs including dissatisfaction of local government support. In this study, institutional and political improvement measurements were suggested for the effective operation of the closed facilities based on the main results.

• Smart Structures and Systems
• /
• 제15권3호
• /
• pp.523-541
• /
• 2015

Structural health monitoring of steel truss bridge based on changes in modal properties was investigated in this study. Vibration measurements with five sensors were conducted at an existing Warren truss bridge with partial fractures in diagonal members before and after an emergency repair work. Modal properties identified by the Eigensystem Realization Algorithm showed evidences of increases in modal damping due to the damage in diagonal member. In order to understand the dynamic behavior of the bridge and possible mechanism of those increases in modal damping, theoretical modal analysis was conducted with three dimensional frame models. It was found that vibrations of the main truss could be coupled internally with local vibrations of diagonal members and the degree of coupling could change with structural changes in diagonal members. Additional vibration measurements with fifteen sensors were then conducted so as to understand the consistency of those theoretical findings with the actual dynamic behavior. Modal properties experimentally identified showed that the damping change caused by the damage in diagonal member described above could have occurred in a diagonal-coupled mode. The results in this study imply that damages in diagonal members could be detected from changes in modal damping of diagonal-coupled modes.

• Archives of Reconstructive Microsurgery
• /
• 제7권1호
• /
• pp.10-14
• /
• 1998

When covering a skin defect of the finger with a local flap is difficult, a vascular island flap is often used. For a palmar skin defect, it is desirable to add a sensory supply to the flap. This report describes a neurovascular island flap that was used to repair a palmar skin defect, the donor skin coming from the dorsal region of the middle phalanx. This flap is elevated with a vascular pedicle of the palmar digital artery and its dorsal skin branch, including the dorsal digital veins, palmar digital nerve and its cutaneous branches. The advantage of this flap are that it can be transferred with ease and without any tension. No special manipulation is required under a microscope and operation can be performed under a simple nerve-block. There if little possibility that the flap itself undergoes ischemic change or congestion. The disadvantage of this flap are that a skin graft is required at the donor skin site and one palmar digital aretery is lost. We think that this neurovascular island flap is one of the useful methods for skin defects that are difficult to cover with a local flap.