• Journal of Satellite, Information and Communications
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• v.9 no.2
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• pp.18-22
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• 2014

Satellite communications consist of communications between base stations of the ground and satellites. For efficient satellite communications, ground networks should be organically utilized. Grid networks are frequently used in and outside the country for wireless communications. The performance of wireless communications is determined by mobility, topography, and jamming signals. Therefore, continuous studies of grid networks are necessary for the utilization of next period satellite networks. Since military communications are used based on wireless systems, they can be considered as a sample of utilization of grid networks. Therefore, this paper presented the results of simulations conducted for the improvement of the performance of the grid networks used in military communications that employing the OSPF, a popular routing protocol for military applications. First we investigate the effects of changing the bit error rate (BER) and number of routers. Then we discuss the effects of maximum segment size (MSS) on network behavior and stability. In this way, we can determine the appropriate MSS for a grid network under various values of BER and number of routers. Such results can be also applied to commercial grid network evaluations.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.632-636
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• 2006

It is needed to use the beam scanning to control the cell coverage of the base station considering operation conditions, season, time period, radiation character and mobility of customers and vehicles for varied wireless communication service and quality improvement. This paper proposes a mobile antenna system which can obtain the characteristics of the beam scanning by controlling the directivity depending on the operation condition. Radiation block is made of 2 sub-array of $1\times3$ patched antennas for ITS of 5.8GHZ bandwidth with the gain of 13dBi, and of 2 sub-array of single patched antenna for WiBro of 2.3GHZ bandwidth with the gain of 12dBi. RF module is made of a switch, an amplifier, a PAD, a 3-Bit phase shifter, and a power divider. The system is able to control the beam tilting with electronic methode by using 3-bit phase shifter$(45^{\circ},\;90^{\circ},\;180^{\circ})$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.402-405
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• 2006

Mobile IP has been designed to have mobile host users move from place to plate without changing their IP address. Ad-hoc network is a provisional network whose mobile host users construct networks by themselves without any assistance of infra structure network, using wireless interface. In this paper we discuss the scheme with which Ad-hoc network users ran access the Internet freely, using mobile IP protocol, and Ad-hot networks are access networks in the spotlight. In this paper we propose algorithm that support enhanced mobility between two Ad-hoc networks applying mobile IP at Ad-hoc routing protocol.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.3
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• pp.55-70
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• 2016

The most critical research issue in MANET environment is on supporting reliable communication between various devices. Various Multi-Hop Routing Protocol studies have proceeded. However, some problems you might have found when you use the existing link state routing technique are that it increases Control Message Overhead and it is unstable when node moves in CR circumstance which has transformation of using channel and MIMC circumstance which uses a number of interfaces. This essay offers a technique which is based on On-Demand Hello and the other technique which used Broadcast Interface of optimization as a solution to decrease Control Message Overhead. Also it proposes Quick Route Restoration technique which is utilized by GPS and MPR Selection technique which consider mobility as a solution of stable communication when node moves. Those offered Routing Protocol and OPNET based simulator result will be expected to be an excellent comparison in related research fields.

• The KIPS Transactions:PartC
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• v.9C no.2
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• pp.267-276
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• 2002

By using wireless terminal, User that want to transmit multimedia traffic as well as simple text and voice have a tendency to increase. This paper proposes a fast handoff protocol that is suitable transmission for real-tim of multimedia traffic by using modified local registration. The proposed protocol solves the Triangle Routing Protocol that is one of existing opened issues without modifying protocol of CN, and we propose the method that MN is able to received a packet by real-time, even if MN is being handoff. We compare fast handoff protocol proposed in this paper with existing method n the registration cost and data packet transmission cost. As a result, we showed that fast handoff protocol proposed in this paper outperforms existing method.

• International Journal of Highway Engineering
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• v.16 no.1
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• pp.99-109
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• 2014

PURPOSES : Climbing lanes on expressways managed by the Korea Expressway Corporation (KEC) have been hot potatoes due to conflicts between slow-moving vehicles such as trucks and other vehicles at the merging section as well as the less popularity with the slow-moving vehicles. In order to resolve such problems, KEC has altered existing climbing lanes to passing-type climbing lanes in 1999. The new type of climbing lanes showed an apparent improvement in mobility. For example, the speeds of vehicles using both climbing lane and other lanes improved a lot. However, there has been no clear evidence about improved safety. METHODS : This research effort was initiated to evaluate the safety of the new passing-type climbing lanes using the comparison-group(CG) method based on three-year-long traffic accident data sets before and after the change, respectively. RESULTS : The passing-type climbing lanes showed twice increased traffic accidents even though the traffic accidents on old type climbing lanes increased 1.1% during the same periods. In addition, in-depth study, the merging area of the passing-type climbing lanes was found out to be the weakest section where 43.8% traffic accidents out of total traffic accidents happened. It is noted that the merging area of the old type climbing showed only 25.0% traffic accidents. CONCLUSIONS : The new passing-type climbing lanes were found to be weak in terms of safety when compared with the old type climbing lanes. Especially, the merging area should be improved to reduce the risk of traffic conflicts between slow-moving vehicles and other vehicles.

• Journal of Korea Water Resources Association
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• v.30 no.5
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• pp.459-465
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• 1997

The possibility of NAPL removal from contaminated soil was studied using the steam injection technique. Both single (octane, toluene and xylene) and composite NAPL (gasoline) were used as contaminant. Soils used in this study were Chumunjin fine sand and weathered granitic soil, both of which are commonly found in Korea. Experimental results showed that with 1 pore volume steam injection, the NAPL removal rate was in the range of 66∼78% for sand and 45∼73% for weathered granitic soil. The steam injection technique seems to have high potential for soil remediation with advantages of relatively short operating time and no side-effect. Rise in the background temperature led to the delay of steam condensation and the increase of NAPL mobility, which resulted in the improvement of removal efficiency. In addition, water flooding after steam injection turned out to be a very efficient way of removing NAPL residual in the soil pores.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.9
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• pp.4133-4137
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• 2011

Reliable Multi-Reader RFID identification is one of issues in Multi-Reader RFID realization program in recent. And the Multi-Reader RFID reader has difficulty to obtain reliable data in data capture layer. The reason is that unreliable readings such as a false positive reading and a false negative reading and missed readings can happen by reader collision problems, noise, or the mobility of tagged objects. We introduce performance metrics to solve these reader problems. We propose three solutions the Minimum Overlapped Read Zone (MORZ) with Received Signal Strength Indicator (RSSI), the Spatial-Temporal Division Access (STDA) method, and double bigger size of tags attached on the object. To show the improvement of the proposed methods, we calculate tag's successful read rates in a smart office, which consists of Multi-Reader RFID systems.

• Journal of International Academy of Physical Therapy Research
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• v.10 no.4
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• pp.1897-1902
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• 2019

Background: Tension-type headaches, which make up the highest proportion of headaches, are prone to develop into chronic tension-type headaches (CTTH). The characteristic of CTTH in patients is that the active myofascial trigger point (ATrP) which causes pain in the muscles of the back of the head is increased, compared to the normal headache and moves the head position forward. Objective: The aim of this study was to investigate the effects of myofascial release (MFR) and posture correction in effectively improving neck function and sleep quality in the symptoms of CTTH patients. Design: Observer-blind study Methods: To reduce ATrP, MFR was applied and exercise was also applied to correct posture. The subjects of this study were 48 individuals randomly divided into three groups; The MFR group using the MFR technique; The MFR with exercise group subject to both the MFR technique and forward head position correction exercises (MFREx), and the control group. MFR and MFREx groups were given the relevant interventions twice a week for four consecutive weeks, and went through the number ATrPs, range of motion (ROM) of neck, Neck Disability Index (NDI) and the Pittsburgh Sleep Quality Index (PSQI) before and after the intervention. A physical therapist, who was fully familiar with the measuring methods of the equipment, was the measurer and not aware of the target's condition was blinded to take measurements only before and after intervention. Results: There was a significant improvement in the ATrP, Neck ROM, NDI and PSQI in the group of patients to whom the MFR technique and MFREx were applied. MFREx was more effective in increasing neck mobility. Conclusions: According to this study, the application of MFR is effective in improving neck movement and sleep quality in chronic tension headache patients.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.9
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• pp.1764-1770
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• 2007

The binding update of MIPv6 which basically makes a route optimization lets MN bring about high signaling traffic, packet loss and delay. HMIPv6, which introduces the MAP protocol, makes the signaling traffic low, thereby reducing the packet losses and delay. However, it still has the same problem in MIPv6 in the case of macro mobility. This paper proposes HMIPv6 with the address insurance policy. It makes MAP prepare LCoA and RCoA before the macro handover happens. When it happens, MN is able to use them after the registration is done in the foreign network. The perormance can be improved because MAP is composed to assure the address in advance. In addition the MAP sends the BU message during the handover, thereby making the proposed scheme better. The simulation shows that the proposed scheme is about 33% shorter than HMIPv6 in the handover delay and about 22% less than FMIPv6 in the packet loss.