• Journal of the Korean Society for Railway
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• v.14 no.4
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• pp.320-326
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• 2011

This paper proposes a baseline-free SHM technique in which the time-reversal process of Lamb waves and the imaging method are used. The proposed SHM technique has three distinct features when compared with the authors' previously proposed one: (1) It use the reconstructed signal for damage diagnosis, without need to extract the damage signal as the difference between reconstructed signal and initial input signal; (2) It use the imaging method based on the time-offlight information from the reconstructed signal, instead of using a pattern comparison method; (3) In order to make the damage image more clear, the modified mathematical definition of damage image in a pixel is used. The proposed SHM technique is evaluated through the damage detection experiment for an aluminum plate with damage at different locations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.3
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• pp.556-560
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• 2013

Recently, solutions to accommodate explosively growing mobile data traffic have attracted intensive attentions since the emergence of high-performance smartphones. Spectrum which can be exploited for mobile communications is very limited. Thus, femto cell is considered as an alternative because it can efficiently offload mobile data traffic from macro cells without using additional spectrum. In this paper, we mathematically analyzed the coverage of femto cell when it is deployed in an area where there exists signals from existing macro base stations. Our numerical results indicate that the coverage of femto cell increases as the total power of femto cell increases or the ratio of power allocated to pilot channel increases. However, it is also shown that the coverage of femto cell is very limited despite its high power when interference signals from macro base stations are strong.

• Journal of the Korean Society for Railway
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• v.14 no.6
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• pp.575-583
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• 2011

In order to minimize the maintenance cost at local lines, Information & Communication Technology based onboard train control system is being developed. Unlike the central traffic control based fixed block system, this system use a moving block method and railway driver direct control switch and railway crossing. The purpose of this paper is to analyze the concerned main operational issues are as follows: the preparation of train operation, drivability, the role of driver and controller, block system and cost. We defined the role of driver and driver's input data for train service, and we designed the business process of driver using UML tool. We considered the aspect of drivability, DMI is needed to support the braking moment for the driver and driver training simulator. We designed the driver business process for control of switch and railway crossing. We analyzed the fixed block system and moving block system to confirm the difference with the existing operational method. The cost analysis structure is also needed for the operation cost comparison.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.3
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• pp.477-483
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• 2016

In this paper, we propose a distributed user scheduling with interference-aware power control (IAPC) to maximize signal to generating interference plus noise ratio (SGINR) in uplink multi-cell networks. Assuming that the channel reciprocity time-division duplexing (TDD) system is used, the channel state information (CSI) can be obtained at each user from pilot signals from other BSs. In the proposed scheduling, to be specific, each user reduces the transmit power if its generating interference to other BSs is larger than a predetermined threshold. Each BS selects the user with the largest SGINR among users. Simulation results show that the proposed technique significantly outperforms the existing user scheduling algorithms. It is worth noting that the proposed technique operates with distributed manner without information exchange among cells. Hence, it can be easily applied to the practical wireless systems like 3GPP LTE without significant modifications of the specification.

• Journal of Sensor Science and Technology
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• v.12 no.4
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• pp.164-169
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• 2003

Recently, as the road capacity reaches the limit and environmental problems becomes serious, there is gradually increased a need for railroad vehicles that are environment-friendly and have time regularity, reliability and safety. Accordingly, in addition to conventional railroad vehicles, lots of vehicles are being newly developed. We developed the hardware and software of the measurement system for on-line test and evaluation of korean high speed train. The software controls the hardware of the mesurement data and acts as interface between users and the system hardware. In this paper, we is studied for electric apparatus performance of railway vehicle using sensor. In order to this test is developed signal conversion system. Using this system, we obtained important result for pantograph voltage, battery voltage, axle speed, and inverter current.

• Journal of the Korean Society for Railway
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• v.16 no.6
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• pp.510-518
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• 2013

These days, interest in radio networks for railways has increased both at home and abroad. In response to this trend, not only the existing radio networks which focus on railway control signals but also the next-generation integrated radio network that can send videos and manage mass storage data are actively being investigated. This paper proposes wireless communication methods to establish integrated radio networks for railways. The paper further suggests a candidate frequency band that could be allocated as the frequency band for railways among the frequency bands currently used in Korea. Based on this paper, we can expect that the domestic railroad will operate more efficiently and that security and convenience of the railroad will reach a superior level. In addition, the Korean integrated radio networks for railways, which cope with the changes in the global technology market, will be established.

• 전기의세계
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• v.38 no.9
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• pp.35-45
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• 1989

최근 정보 및 산업사회의 발달에 따라 전기에너지의 이용이 양적, 수적으로 증가되고 있는 가운데 모든 전기.전자기기 및 전력설비에 전기에너지를 전달하는 전력선로상에서 불요전기신호에 의한 전원방해현상이 발생되는 경우가 빈번해 지고 있다. 따라서 기기의 정상적인 동작에 장애를 주는 증 PLD현상이 심각해지고 있는 실정이다. 그러므로 PLD현상파악 및 이에 대한 방지대책의 수립은 EMI/EMC문제의 가장 기본적이라고 할 수 있다. 먼저 PLD에 대한 실태조사가 뒤따라야 할 것이다. 또는 국내 여러지역을 전력수요가별로 구분하여 PLD현상을 측정할 필요가 있다. 그리고 측정된 데이터의 분석에 의해 각종 전기.전자기기 등의 효율적 운용을 보장하기 위해서는 PLD현상에 대한 대책을 법적규제의 측면과 잡음대책방안의 측면에서 제시해야 할 것이다.

• Information and Communications Magazine
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• v.25 no.4
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• pp.11-15
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• 2008

제스처 인식은 로봇의 활용에 유용한 기능이지만 많은 계산 량이 요구되므로 보급형 u-로봇에는 탑재되기 어려운 단점이 있다. 따라서 u-로봇에서 일차적인 영상처리를 수행하고, 핵심 데이터만 u-로봇서버에 전송하여 다양한 응용을 수행하는 분산시스템을 구성할 필요가 있다. 본 연구에서는 스테레오 영상칩을 탑재한 ASIC과 임베디드 시스템을 활용하여 사용자의 상체 자세를 검출할 수 있는 알고리즘을 개발하고 성능을 검증하였다. 개발된 시스템은 사용자의 다양한 상체자세를 최대 30fps까지 실시간으로 검출할 수 있으며 80%전후의 검출률과 10cm전후의 손과 팔꿈치의 위치오차를 보였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.06a
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• pp.59-61
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• 2022

항로표지 시스템은 적은 양의 데이터를 간헐적으로 전송하고 넓은 지역에서 통신이 가능해야 하기 때문에 NB-IoT 시스템은 매우 적합한 기술이다. 본 연구에서는 LTE 시스템과 공존하는 inband-mode NB-IoT 시스템에서 상항링크 간섭을 분석하였다.

• Proceedings of the KAIS Fall Conference
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• 2010.11a
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• pp.367-369
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• 2010

본 논문은 열차제어시스템 유지보수업무의 최적화를 위한 정량적 주기산출방법에 관한 것으로, 특히 전장품과 같이 유지보수업무로 주로 교체업무가 선택되는 경우, 운영비용을 최적화하기 위한 교체주기를 정량적으로 산출하기위한 방법을 제시하고, 장치의 고장분포 데이터를 통해, 철도신호장치의 교체주기를 할당한다. 제시한 방법은 유지보수장치의 운영이력을 분석하여, 장치의 고장데이터를 바탕으로 고장분포를 확률적으로 모델링한 뒤, 정확한 LCC데이터가 적용될 때 새롭게 도입되는 장비 및 시스템의 유지보수업무주기를 할당이 가능하고, 이를 통해여 시스템의 운영안전을 보장하면서, 운용비용을 최적화 할 수 있다.