• Proceedings of the KSR Conference
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• 2008.06a
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• pp.489-494
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• 2008

The measurement of magnetic field is performed about DC and AC magnetic field in electric railway line. The test point is cap, on the converter/inverter box, on the traction motor and on the SIV, the height of measurement is bottom and 60 cm height. In case of AC magnetic field, the selected specific frequency is measured on the converter/inverter box. The AC magnetic field is checked and analysis through BNC output, DAQ cad and notebook PC.

• Journal of the Korea Society of Computer and Information
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• v.20 no.2
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• pp.89-97
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• 2015

In this paper, we propose a handoff method supporting LBS (Location Based Services) Information in mobile clouding environment. In mobile clouding computing, handoff delay and re-authentication is occurred. A mobile node needs re-authentication procedure from cloud server whenever it arrives new AP. But Using of location information of node enables to reduce delay time due to re-authentication. To reduce re-authentication delay time, proposed method stores location information of APs on WiFi based location server to complement. GPS-based technology which can't receive satellite signal in indoor and then node collects location information of AP at handoff time. And also enables to process LBS without increasing handoff delay by splitting the process of handoff from process of requesting location information. For analysis of proposed method, We analyze handoff delay and location information process time and have compared previous handoff method in cloud environment. We confirmed that proposed method shows lower delay time without increasing LBS process time than previous method because node receives location information from location information server when handoff is occurred.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.9
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• pp.614-619
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• 2014

In WSN (Wireless Sensor Networks) based surveillance system, it needs to know the occurrence of events or objects and their locations, because the data have no meaning without location information. Using traditional 2D localization mechanisms provide good accuracy where altitude is fixed. But the mapping the position estimated by 2D localization to the real world can cause an error. Even though 3D localization mechanisms provide better accuracy than 2D localization, they need four reference nodes at least and high processing overhead. In our surveillance system, it is needed to estimate the height of the detected object in order to determine if the object is human. In this paper, we propose a height estimation mechanism which does not require many reference nodes and high complexity. Finally, we verify the performance of our proposed mechanism through various experiments.

• Journal of Advanced Navigation Technology
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• v.9 no.1
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• pp.1-8
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• 2005

In this paper, an impulse generator for UWB(Ultra Wide-band) technique with great possibility to be adopted as a next generation indoor WLAN(Wireless Local Area Network) has been designed by using SRD(Step Recovery Diode). Design goal is to design an impulse generator with simple structure, low cost, small size, and high performance. The impulse generator satisfied by FCC's regulation ( frequency range: 3.1~10.6 GHz, limit of power level: -41.25 dBm ) has been simulated by using ADS(Advanced Design System) which is the trade name of the Agilent Technologies. The output power of the impulse generator has been explained separately for single and multi band purposes, respectively.

• KIEAE Journal
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• v.11 no.5
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• pp.137-143
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• 2011

An atrium space, unlike ordinary office rooms, accommodates variety of activities such as moving and resting of people and usually houses variety of vegitation to improve amenity and indoor environment. Many atrium buildings in Korea have been designed by considering the environmental criteria for human beings, not for the vegitation in the atrium space. Especially the daylighting designs are mostly focused on the required illuminances for various visual tasks of the occupants and glare controls. As a result, some atrium spaces do not provide sufficient light to the interior plants. Consequently, these atrium spaces require a high level of electric lighting to compensate the deficit of natural light for the photosynthesis of the vegitation. The purpose of this study was to suggest design guidelines for 4-sided atrium spaces having different well indices (WI), plan aspect ratio (PAR), and cardinal orientation. The findings from this study might be referenced by building designers when designing or selecting canopy systems by considering the daylight performances of the uncovered atrium spaces. In the study, the daylight performance was evaluated in terms of daylight autonomy (DA).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.11
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• pp.2488-2492
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• 2011

Currently, the importance of location-based services and location awareness has been grown due to the advancement of wireless communication technologies. Among several localization techniques, the trilateration localization is one of major localization techniques. However, distance estimation errors caused by obstacles and indoor environment changes lead to inaccurate localization. Although there are existing trilateration localization methods, they have focused on addressing a few problems of trilateration location approaches without detailed analysis. This paper analyzes existing trilateration location methods and evaluate their performance.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.2
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• pp.72-78
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• 2011

Localization information of an object can be a very useful element for many application areas. Presently, GPS is typically used for it, but many researches on the wireless localization technology are going on recently actively using mobile communication network, wireless sensor network, and ad hoc network in order to overcome the limitations of the GPS such as indoor, cost, power consumption, and etc. Therefore, this article surveys the most representative wireless localization techniques, which can be deployed in the wireless networks, and their principles and performances are analyzed based on the researched papers. In a conclusion, selection of a localization technique should consider the key design elements to a given application from the design elements such as localization environment, accuracy, time to fix, computation amount, implementation ease, and etc.

• Proceedings of the KIPE Conference
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• 2011.11a
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• pp.241-242
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• 2011

교통 약자 승객의 편의성 증대, 도심의 매연 감소 및 온실가스 저감 등 대중 교통 선진화를 위해 친환경 초저상 전기버스의 개발이 필요하다. 초저상 전기버스는 초저상 액슬 일체형 휠모터 구동시스템을 탑재한 형태로 구현이 가능하며, 초저상 액슬 일체형 휠모터 구동시스템은 구동 모터를 액슬 허브에 일체화 시킴으로써 기존 구동시스템 대비 무게 및 사이즈가 대폭 줄어들고, 동력 전달 매커니즘을 획기적으로 개선하여 효율 향상 및 차량 연비 개선이 가능하다. 특히 바퀴 중심과 액슬 출력 중심에 단차를 둠으로써 차량의 전방 바닥 뿐만 아니라 후방바닥을 평평하게 유지할 수 있어 실내 공간이 획기적으로 개선되어 교통 약자를 포함한 승객의 편의성을 향상시킬 수 있다. 또한, 액슬 일체형 휠모터 구동시스템은 각 휠의 분산 구동이 가능하므로 동특성 및 구동제어성이 뛰어나고, ESP(Electronic Stability Program), VDC(Vehicle Dynamic Control) 등과 연계하여 통합적인 지능형 시스템을 구현할 수 있다. 액슬 일체형 휠모터 구동시스템은 휠모터와 감속기 및 휠모터제어기 등으로 구성되며, 본 논문에서는 초저상 액슬 일체형 구동시스템용 120kW급 휠모터 및 휠모터제어기의 개발 및 다이나모 환경에서 T-N 특성 및 최대 출력 시험, 효율 시험을 통해 전기버스 등 대형 차량(Heavy Duty Vehicle)에 적용 가능한 전기동력시스템의 성능을 확인하였다.

• Journal of the Korean Geotechnical Society
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• v.21 no.3
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• pp.79-85
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• 2005

An experimental study was carried out to investigate the recycling possibility of waste oyster shells, which induce environmental pollutions by piling up out at the open or the temporary reclamation. The purpose of this study is to develope eco-friendly binder using waste oyster shells, and to reinforce dredged soils fur soft soil improvement. In this paper, a series of laboratory tests including compressive strength tests were performed to evaluate strength characteristics of soils treated by developed binder with different water content of dredged soils, mixing rates of binder, curing days. Based on test results, eco-friendly binders manufactured from waste oyster shells were estimated as good resource materials for soft soil improvements.

• Journal of Advanced Navigation Technology
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• v.15 no.5
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• pp.696-704
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• 2011

In this paper, we propose a mobile robot navigation algorithm using data fusion of a monocular camera and ultrasonic sensors. Threshold values for binary image processing are generated by a fuzzy inference method using image data and data of ultrasonic sensors. Threshold value variations improve obstacle detection for mobile robot to move to the goal under poor illumination environments. Obstacles detected by data fusion of camera and ultrasonic sensors are expressed on the grid map and avoided using the circular planning algorithm. The performance of the proposed method is evaluated by experiments on the Pioneer 2-DX mobile robot in the indoor room with poor lights and a narrow corridor.