• The KIPS Transactions:PartD
• /
• v.10D no.2
• /
• pp.195-210
• /
• 2003

In this paper, we propose an enhanced concurrency control algorithm that maximizes the concurrency of multi-dimensional index structures. The factors that deteriorate the concurrency of index structures are node splits and minimum bounding region (MBR) updates in multi-dimensional index structures. The proposed concurrency control algorithm introduces PLC(Partial Lock Coupling) technique to avoid lock coupling during MBR updates. Also, a new MBR update method that allows searchers to access nodes where MBR updates are being performed is proposed. To reduce the performance degradation by node splits the proposed algorithm holds exclusive latches not during whole split time but only during physical node split time that occupies the small part of a whole split process. For performance evaluation, we implement the proposed concurrency control algorithm and one of the existing link technique-based algorithms on MIDAS-3 that is a storage system of a BADA-4 DBMS. We show through various experiments that our proposed algorithm outperforms the existing algorithm in terms of throughput and response time. Also, we propose a recovery protocol for our proposed concurrency control algorithm. The recovery protocol is designed to assure high concurrency and fast recovery.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.2
• /
• pp.775-782
• /
• 2011

This study was designed to clarify the morphometrical change of lymph node, deep cortex and lymph follicles in draining lymph nodes of young mice in response to local injection of lipopolysaccharide(LPS). 1. In the group stimulated with LPS, aged 0 day and 3 days, the number of lymph follicles were not significantly different from those of control group. 2. In the group two to four weeks after injection with LPS, aged five days and one week, the number of lymph follicles were significantly increased from those of control group. 3. In the group one to four weeks after injection with LPS, aged 0 day, three days, five days and one week, the area of lymph node and deep cortex increased about 1.5-3 times more than that of the control group. 4. In the group two to four weeks after injection with LPS, aged three days, five days and one week, the lymph follicles(the area: larger than 0.1 mm2) were increased from those of control group. 5. In the group two to four weeks after injection with LPS, aged five days and one week, the lymph follicles(the area: smaller than 0.01 mm2) were increased from those of control group. In view of these experimental findings, the formation of lymph follicles were induced by LPS stimulation from 5 days to one week after birth. The newley formed lymph follicles area in response to LPS may be less than $0.01mm^2$.

• The Journal of the Korea Contents Association
• /
• v.11 no.7
• /
• pp.38-50
• /
• 2011

For energy-efficiency in Wireless Sensor Networks (WSNs), when a sensor node detects events, the sensing period for collecting the detailed information is likely to be short. The lifetime of WSNs decreases because communication modules are used excessively on a specific sensor node. To solve this problem, the TARP decentralized network packets to neighbor nodes. It considered the average data transmission rate as well as the data distribution. However, since the existing scheme did not consider the energy consumption of a node in WSNs, its network lifetime is reduced. The proposed scheme considers the remaining amount of energy and the transmission rate on a single node in fitness evaluation. Since the proposed scheme performs an efficient congestion control it extends the network lifetime. The simulation result shows that our scheme enhances the data fairness and improves the network lifetime by about 27% on average over the existing scheme.

• The KIPS Transactions:PartD
• /
• v.11D no.4
• /
• pp.809-822
• /
• 2004

In this paper, we propose a concurrency control algorithm based on R-tree for spatial database management system. The previous proposed algorithms can't prevent problem that search operation is to be blocking during update operations. In case of multidimensional indexes like R-tree, locking of update operations may be locked to several nodes, and splitting of nodes have to lock a splitting node for a long time. Therefore search operations have to waiting a long time until update operations unlock. In this paper we propose new algorithms for lock-free search operation. First, we develop a new technique using a linked-list technique on the node. The linked-list enable lock-free search when search operations search a node. Next, we propose a new technique using a version technique. The version technique enable lock-free search on the node that update operations is to be splitting.

• Journal of Internet of Things and Convergence
• /
• v.6 no.3
• /
• pp.7-13
• /
• 2020

In this paper, we propose a system that monitors and controls the environment of a server room in real-time based on IoT. Recently, as the information society has been maximized, the damage has been significant when the computer system is down. In particular, damage such as a fire in the server room leads to loss of data and data recovery becomes impossible. In order to reduce such damage, a node capable of real-time monitoring using an IoT system was proposed. In addition, we proposed a coordinator node that can collect and monitor node information. In order to verify that the proposed system works, we have developed software that can control node monitoring and air conditioning. As a result of the experiment, we confirmed that the proposed system detects fire and controls the air conditioner.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.6B
• /
• pp.387-395
• /
• 2005

In this paper, we propose an end-to-end mobility management and TCP flow control scheme which considers different link characteristics for vertical handover environments. The end-to-end mobility management is performed by using SIP protocol. When a mobile node moves to a new network, it informs its movement of the correspondent node by sending SIP INFO message containing a new IP address which will be used in the new network. And then the corresponding node encapsulates all packets with the new IP address and sends them to the mobile node. in general, RTT of WLAN is shorter than RTT of cdma2000. when the MN moves from WLAN network to cdma2000 network, TCP retransmission timeout will be occurred in spite of non congestion situations. Thus, TCP congestion window size will be decreased and TCP throughput will be also decreased. To prevent this phenomenon, we propose a method using probe packets after handover to estimate a link delay of the new network. We also propose a method using bandwidth ratio of each network to update RTT. It is shown through NS-2 simulations that the proposed schemes can have better performance than the previous works.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39B no.3
• /
• pp.143-150
• /
• 2014

In this paper, we propose an energy efficient and delay guaranteed node scheduling scheme inspired by biological systems, which have gained considerable attention as a computing and problem solving technique. With the identification of analogies between cellular signaling systems and WSN systems, we formulate a new mathematical model that considers the networking challenges of WSNs. The proposed bio-inspired algorithm determines the state of the sensor node, as required by each application and as determined by the local environmental conditions and the states of the adjacent nodes. A control analysis shows that the proposed bio-inspired scheme guarantees the system stability by controlling the parameters of each node. Simulation results also indicate that the proposed scheme provides significant energy savings, as well as reliable delay guarantees by controlling the states of the sensor nodes.

• Journal of the Korea Convergence Society
• /
• v.10 no.1
• /
• pp.45-51
• /
• 2019

The use of the Internet of things plays a major role in the Fourth Industrial Revolution, and a series of tasks of accumulating, converging, analyzing and reusing various data and services becomes very important. Because the pace and scope if the paradigm shift in Fourth Industrial Revolution is so rapid and unpredictable, the development and utilization of a system to fulfill this role for IOT are urgently required. In this paper, we introduce the Web-based IOT management system, which connects the IOT with OKMindmap, which is a domestic open source software and service, and the Node-RED service. This system combines the advantages of OKMindmap with the advantages of Node-RED, which is capable of visual component based programming, so that it can easily and flexibly connect the IOT based on Web browsers, and various data and services can be integrated and linked. We developed a camera module, a temperature and humidity sensor module, and the motor control module in Raspberry PI basically, and tested the operation successfully. We plan to extend the IOT component gradually by using Arduino and System On Chip.

• Radiation Oncology Journal
• /
• v.32 no.3
• /
• pp.132-137
• /
• 2014

Purpose: To evaluate non-sentinel lymph node (LN) status after sentinel lymph node biopsy (SNB) in patients with breast cancer and to identify the predictive factors for disease failure. Materials and Methods: From January 2006 to December 2007, axillary lymph node (ALN) dissection after SNB was performed for patients with primary invasive breast cancer who had no clinical evidence of LN metastasis. A total of 320 patients were treated with breast-conserving surgery and radiotherapy. Results: The median age of patients was 48 years, and the median follow-up time was 72.8 months. Close resection margin (RM) was observed in 13 patients. The median number of dissected SNB was two, and that of total retrieved ALNs was 11. Sentinel node accuracy was 94.7%, and the overall false negative rate (FNR) was 5.3%. Eleven patients experienced treatment failure. Local recurrence, regional LN recurrence, and distant metastasis were identified in 0.9%, 1.9%, and 2.8% of these patients, respectively. Sentinel LN status were not associated with locoregional recurrence (p > 0.05). Close RM was the only significant factor for disease-free survival (DFS) in univariate and multivariate analysis. The 5-year overall survival, DFS, and locoregional DFS were 100%, 96.8%, and 98.1%, respectively. Conclusion: In this study, SNB was performed with high accuracy and low FNR and high locoregional control was achieved.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.34S no.11
• /
• pp.25-33
• /
• 1997

The end-to-end rate-based control mechanism is used for the flow control of the ABR service to allow much more flexibility in ATM switching system. To accommodate the ABR service effciently many algorithms such as EFCI, EPRCA, ERICA, and CAPC2 have been proposed for the switch algorithm. ABR cells and related RM cells are received at the ATM switch fabric transparently without any processing. And then cells received from the traffic source are queued in the ABR buffer of switching system. The ABR buffer usually has some thresholds for easy congestion control signal transmission. Whatever we use, therefore, these can be many ABR traffic control algorithms to implement the ABR transfer capability. The genertion of congestion indicate signal for ABR control algorithms is determined by ABR buffer satus. And ABR buffer status is determined by ABR cells transfer ratio in ATM switch fabrics. In this paper, we presented the functional structures for control of the ABR traffic capability, proposed the readout scheduling, cell slot allocation of output link and the buffer allocation model for effective ABR traffic guranteeing with considering CBR/VBR traffics in ATM switch. Since the proposed readout scheduling scheme can provide more avaliable space to ABR buffer than existing readout scheduling scheme, generation rate of a SEND signal, that is, BCN signal in destination node can be increased for ABR call connection. Therefore, the proposed scheme, in this paper, can be appropriate as algorithm for effective ABR traffic service on output link of ATM switching node.