• Journal of Korea Multimedia Society
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• v.18 no.5
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• pp.631-640
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• 2015

Recently CCTV system is installed widely purpose to enhanced physical security, gathering criminal evidence and management of facilities. In spite of supporting strong management function, CCTV system has weak security function. Therefore high security management function is required. Generally it's not easy to control the devices under NAT using a NMS(Network Management System). So we design and implement alive check algorithm of CCTV devices under NAT using DVRNS address resolution and TCP session check. We evaluated and analyzed of developed system on real environment which includes about 100 DVRs under NAT. As a result of test, it showed that device alive check and DVRNS address resolution were well performed without any error.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.6
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• pp.257-262
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• 2001

In this paper, a linear ultrasonic motor using piezoelectric ceramics was fabricated, and its operation characteristics were investigated. A linear ultrasonic motor using L$_1$-B$_4$model was composed of a stator and a rotor, and a stator was composed of piezoelectric ceramics and a elastic body. When applied frequency and voltage were 58.4kHz and 56V respectively, the feeding speed of the motor was 19.8 cm/s. A linear ultrasonic motor could be moved in left and right directions by the phase difference. Feeding speed and feeding force of a linear ultrasonic motor could be controlled by applied voltage. A linear ultrasonic motor had a droping torque-speed characteristic. The maximum efficiency of linear ultrasonic motor was 2.14%. Therefore, this linear ultrasonic motor can be expected to be used for a card-forwarding device, such as a card reader device and so on.

• International Journal of Railway
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• v.3 no.2
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• pp.39-45
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• 2010

The RF-CBTC (Radio Frequency-Communication Based Train Control) System is a communication system in railroad systems. The communication method of RF-CBTC system is the wireless between the wayside device and on-board device. The wayside device collects its location and speed from each train and transmits the distance from the forwarding train to the speed-limit position to it. The on-board device controlling device controls the speed optimum for the train. In the case of the RF-CBTC system used in Korea, transmission frequency is 2.4 [GHz]. It is the range of ISM(Industrial Scientific and Medical equipment) band and transmission of voice and data is performed by CDMA (Code Division Multiple Access) method. So noises are made in the AWGN (Additive White Gaussian Noise) and fading environment. Currently, the SNR (Signal to Noise Ratio) is about 20 [dB], so due to bit errors made by noises, transmission of reliable information to the train is not easy. Also, in the case that two tracks are put to a single direction, it is needed that two trains transmit reliable voice and data to a wayside device. But, by noises, it is not easy that just a train transmits reliable information. In this paper, we estimated the BER (Bit Error Rate) related to the SNR of voice and data transmission in the environment such as AWGN and fading from the RF-CBTC system using the CDMA method. Also, we supposed the SNR which is required to meet the BER standard for voice and data transmission. By increasing the processing gain that is a ratio of chip transmission to voice and data transmission, we made possible voice and data transmission from maximally two trains to a wayside device, and demonstrated it by using Matlab program.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.4
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• pp.43-50
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• 2010

Vehicle-to-Vehicle (V2V) is a special type of vehicle ad-hoc network (VANET), and known as a solution to provide communication among vehicles and reduce vehicle accidents. Geographical routing protocols as Greedy Perimeter Sateless Routing (GPSR) are very suitable for the V2V communication due to special characters of highway and device for vehicles. However, the GPSR has problem that appears local maximum by some stale neighbor nodes in the greedy mode of the GPSR. It can lose transmission data in recovery mode, even if the problem is can be solved by the recovery mode of the GPSR. We therefore propose a Greedy Perimeter Reliable Routing (GPRR), can provide more reliable data transmission, to resolve the GPSR problem in the V2V environment. Simulation results using ns-2 shown that the GPRR reveals much better performance than the GPSR by remarkably reducing the local maximum rate in the greedy mode.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.4B
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• pp.298-305
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• 2003

In this paper, we proposed a high performance lookup controller for IP packet forwarding engine of ATM based label edge routers. The lookup controller is designed to provide services such as MPLS, VPN, ELL, and RT services as well as the best effort. For high speed searching for IP addresses, we employed a TCAM based hardware search device not using traditional algorithmic approaches. We also implement lookup control functions into FPGA for fast processing of packet header and lookup control. The proposed lookup controller is designed to support differenciated services for users and to process in pipelined mechanism for performance improvement. A two-step search scheme is also applied to perform lookup for the key combined with multi-field of packet header. We found that the proposed lookup controller provides the performance of about 16M packets per second through simulations.

• Journal of the Korea Society of Computer and Information
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• v.21 no.5
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• pp.49-56
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• 2016

Increasing Internet traffic and forwarding table size need high performance IP address lookup engine which is a crucial function of routers. For finding the longest matching prefix, trie-based or its variant schemes have been widely researched in software-based IP lookup. As a software router, we enhance the IP address lookup engine using GPU which is a device widely used in high performance applications. We propose a data structure for multibit trie to exploit GPU hardware efficiently. Also, we devise a novel scheme that the root subtrie is loaded on Shared Memory which is specialized for fast access in GPU. Since the root subtrie is accessed on every IP address lookup, its fast access improves the lookup performance. By means of the performance evaluation, our implemented GPU-based lookup engine shows 17~23 times better performance than CPU-based engine. Also, the fast access technique for the root subtrie gives 10% more improvement.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06b
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• pp.370-372
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• 2011

기존에 연구된 사이버 물리 시스텀을 위한 동적 제어 미들웨어에서는 구성요소인 제어 장치 (Controller)가 동일한 지역망 내에 위치한 Controller를 검색하고자 할 때, 검색 하고자 하는 Controller카 자신의 상위 제어 및 관리 장치 (C&A, Controller & Administrator) 와 다른 C&A의 하위 노드인 경우, 전역의 C&A에게 모두 검색 메시지를 전송하는 심각한 문제가 존재 하였다. 본 논문에서는 이러한 비효율적인 문제를 해결하고자 같은 지역망 내의 C&A간 검색 메시지를 전달 (Forwarding) 하는 방식을 도입한다. 이를 통해 같은 지역망 내에 존재하는 Controller 검색을 위한 네트워크 트래픽을 크게 감소시킬 수 있다.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1534-1536
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• 1998

We designed and fabricated plate-type linear ultrasonic motor. It used multi-vibration mode, 1st Longitudinal and 4th Bending mode. To analyze vibration mode and find maximum displacement point, we simulated using FEM(Finite Element Method). The plate-type linear ultrasonic motor was fabricated by the simulation results. Also, to confirm application to card-forwarding device, frequency and load characteristics were measured. Its resonance frequency was 49.6 kHz, and its maximum speed was about 0.6m/s when no load. Also, its maximum efficiency was 1.2 % and in that time, speed and torque was 0.3 m/s and 0.7 mNm, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.29-32
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• 1998

A plate-type ultrasonic linear motor using longitudinal and bending multi-vibration mode was designed and fabricated for card-forwarding device. The rotor consisted of piezoelectric ceramic plate and elastic materials. The performances of the motor were measured. As the experimental results, no-load speed of the motor was 0.6 m/s at 80 V in applied voltage. Starting torque was 1.4 mNm and maximum efficiency was 1.2 %.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.10
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• pp.861-865
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• 1998

A plate-type linear ultrasonic motor using logitudinal and bending multi-vibration mode was designed and fabricated for the application to card-forwarding device. The stator consisted of PZ-PT-PMS piezoelectric ceramic plate and stainless steel. The performances of the motor were measured. As the experimental results, no-load speed of the motor was 0.6m/s when applied voltage was $80\textrm{V}_{rms}$ in resonance frequency. Starting torque was 1.4 mNm and maximum efficiency was 1.2%.