• Journal of Advanced Navigation Technology
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• v.21 no.4
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• pp.347-352
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• 2017

In this paper, we propose a method that reduces mobile user's handover call dropping probability by using cognitive radio technology(CR) in cellular - based wireless cognitive radio networks. The proposed method predicts a cell to visit by Ziv-Lempel algorithm, and then supports mobile user with prediction of spectrum holes based on CR technology when allocated channels are short in the cell. We make neural network predict spectrum hole resources, and make handover calls use the resources before initial calls. Simulation results show CR technology has the capability to reduce mobile user handover call dropping probability in cellular mobile communication networks.

• Journal of Sensor Science and Technology
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• v.3 no.1
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• pp.26-31
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• 1994

A SIMOX SOI Hall sensor has been fabricated and its characteristics were measured at temperatures between $20^{\circ}C$ and $260^{\circ}C$. Output Hall voltage varied linearly with supplied current, showing good linearity. The Hall voltage and the offset voltage initially increased slightly and then decreased with temperature due possibly to the electron mobility variation with temperature. Nearly constant product sensitivity throughout the temperature range indicates that this Hall sensor could be used for high temperature applications.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.2
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• pp.120-127
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• 2008

This paper proposes a new vector control method using two rectangular hall sensors instead of using the expensive encoder and resolver. The proposed method estimates the speed and motor position by using the quadruple of two hall sensors signals instead of encoder signal. The proposed new speed estimation method is stable under the rated speed range. This algorithm will be able to moderate prices of the whole system and apply to the condition unfitted with encoder and resolver.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.5
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• pp.315-321
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• 2009

Remote water meter monitoring is essential in U-city applications, whoγe digital water meter is a key component. While there are several kinds of water meters, the way to use has sensors has the merit of better preciseness, but the drawback of more power consumption. In this paper, we suggest an advanced sensing algorithm to diminish the power consumption while keeping the quality of preciseness. Our approach is to use less precise hall sensor for detecting the start of water impeller rotation with lower power consumption. During the rotation, a high precision hall sensor is used to meter the amount of water consumption. Our algorithm is analyzed to get 2 times lower power consumption than the previous algorithm.

• Journal of the Korean Magnetics Society
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• v.21 no.3
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• pp.104-107
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• 2011

We measured signals at the "Guan" region of a radially arterial pulse using the prototype of a clamping pulsimeter equipped with a Hall effect device, which is passed signals through the voltage detecting hard ware system. The important four different measuring times of the period, systolic, reflective, and notch peaks for a temporally pulse signal are obtained and compared each other from the analysis for an arbitrary pulse wave of one position of small size permanent magnet. It is possible to measure the reproducible pulse rate and blood pressure by using the cuffless clip type pulsimeter without an unpleasant oppressive feeling due to the use of pressurization.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.125-128
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• 2008

In the recent construction industry, external tendon method has been widely used for strengthening and repair of civil structures. This paper presents the strengthening effectiveness and application of the proposed external tendons using lifting hole anchorage system. Based on the experimental results of the previous external tendons using lifting hole anchorage systems, two types of modified systems were proposed. In order to verify the strengthening effectiveness of the two systems, six beams were built and a series of experiments was carried out. To compare and analyze the behaviors of the proposed systems, deflections and strains were measured. Additionally, yield load, ultimate load and failure modes were compared and analyzed.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.8
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• pp.19-24
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• 2012

In this paper, we analyze the maximum throughput of opportunistic routing along a long-haul multi-hop wireless network path for a single data stream, while considering link-level interference among the network nodes. Surprisingly, we find out that opportunistic routing does not provide much improvement in throughput for long-haul paths. The results of this research show that when we compare the extra cost for the complex implementation of the opportunistic routing scheme to the performance improvement obtained from it, opportunistic routing scheme needs to be applied to only short-haul multi-hop wireless network paths.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.5 s.248
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• pp.528-532
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• 2006

In the aerospace industry, Cold expansion has been used the most important method that is retarded of crack initiation from fastener hole surface. Cold expansion method(CEM) is that a oversized tapered mandrel goes through the hole in order to develop a compressive residual stress as the passing of the mandrel around the hole. Therefore, because of characteristic of mandrel inserting, Residual Stress Distributions (RSD) are differently generated form Entry, Mid and Exit position of the plate. Also, it is respected that RSD are changed as distances between holes. In this paper, It is performed a FE analysis of RSD by CEM and it is respectively shown RSD in the Entry, Mid and Exit position. It is compared residual stress results form the cold expansion in these two cases: the concurrent CEM and the sequential CEM. From this research, it has been found that compressive residual stress of Entry position is lower than other positions. Also, the concurrent CE of adjacent holes leads to much higher compressive residual stress than the sequential CE. In addition, in the sequential CE case, a compressive RSD of 1 step's hole around is lower than compressive RSD of 2 step's hole around.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.11
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• pp.1077-1082
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• 2016

IDS can be used as a countermeasure for malicious attacks which cause degrade of network transmission performance by disturbing of MANET routing function. In this paper, effects of IDS for transmission performance on MANET under grayhole attacks which has intrusion objects for a part of transmissions packets, some suggestion for effective IDS will be considered. Computer simulation based on NS-2 is used for performance analysis, performance is measured with VoIP(: Voice over Internet Protocol) as an application service. MOS(: Mean Opinion Score), CCR(: Call Connection Rate) and end-to-end delay is used for performance parameter as standard transmission quality factor for voice transmission.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.245.2-245.2
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• 2014

홀 방식 이온빔 소스는 방전 채널 내부에 중성기체 및 전자를 주입하여 플라즈마를 생성하며, 생성된 이온들은 자기장에 의해 구속된 전자들과 양극이 만드는 전기장에 의해 가속되어 이온 빔을 발생시킨다. 홀 방식 이온빔 소스에는 고리형 소스와 원통형 소스가 있으며, 기하학적 구조 및 자기장 구조가 달라 발생되는 이온전류, 가속효율, 연료효율, 이온화 비율 등 플라즈마 특성이 다르다. 특히, 플라즈마의 이온화 비율은 이온빔 소스의 방전 전류 및 연료효율에 영향을 미치며, 다중전하를 띤 이온의 높은 에너지는 채널벽의 침식 문제를 야기하는 등 이온빔의 전하량 분석 연구는 물리적 연구측면 뿐만 아니라 실용적인 측면에서도 매우 중요하다. 원통형 소스의 경우 연료효율이 100% 이상으로, 이온화 효율이 매우 높아 발생되는 이온의 가속효율도 높게 나타난다. 본 연구에서는, 이를 통해 다중이온을 진단할 수 있는 ExB 탐침을 개발하여, 다중이온의 생성 비율과 연료 효율과의 관계를 살펴보았다. 이온전위지연 탐침과 패러데이 탐침을 이용하여 채널 및 자기장 구조에 따른 전류 분포 및 이온에너지분포를 측정하였으며, 이온 빔의 효율 및 플라즈마 특성을 분석하였다.