• Journal of Forest and Environmental Science
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• 제39권4호
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• pp.254-260
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• 2023

A sensor system has been developed that uses an ultrasonic sensor to detect the downhill slope on the side of a forest road and prevents a vehicle-type forest machine from rolling down a mountainside. A specular reflection of ultrasonic wave might cause severe issues in measuring distances to targets. By investigating the installation angle of the sensor to minimize the negative effects of specular reflection, the installation angle of lateral monitoring ultrasonic sensor could be determined based on the width of road shoulder. Obstacles such as small rocks or piece of log in a forest road may cause the forest machine to be overturned while the machine riding over due to excessive its posture change. It was determined that the laser sensor could be a part of a sensor system capable of specifying the location and size of small obstacles. Not only this sensor system including ultrasonic and laser sensors can issue a warning of dangerous sections to drivers in forest forwarders currently in use, but also it can be used as a driving safety sensor in autonomous forest machine or remote-control forest machine in the future.

• Journal of information and communication convergence engineering
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• 제6권1호
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• pp.10-14
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• 2008

The robot localization problem is a key problem in making truly autonomous robots. In this work we provide thorough discussions of Ultrasonic Positioning System can be applied to the localization problem. First, we look at the use of Kalman filters and basic concept and the equation involved in Kalman filters. Secondly, we create understanding of how the Kalman filters can be implemented in robot localization. We show our discussion and experiments how Kalman filters applied to the localization problem. Lastly, we perform simulations using Usat Wheel Chair robot in our own general Kalman filters robot monitoring software.

• 한국압력기기공학회 논문집
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• 제9권1호
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• pp.25-30
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• 2013

The periodic inspection of piping and pressure vessels welds in nuclear power plant has to provide reliable result related to weld flaws, such as location, maximum amplitude response, ultrasonic length, height and finally the nature or flaw pattern. The founded flaw in ultrasonic inspection is accepted or rejected based on these data. Specially, the amplitude of flaw response is used as basic parameter for flaw sizing and it may cause some deviation in length sizing result. Currently the ultrasonic inspections in nuclear power plant components are performed by specific inspection procedure which describing inspection technique include inspection system, calibration methodology and flaw characterizing. To perform ultrasonic inspection during in-service inspection, reference gain should be established before starting ultrasonic inspection by the requirement of ASME code. This reference gain used as basic criteria to evaluate flaw sizing. Sometimes, a little difference in establishing reference gain between calibration and field condition can lead to deviation in flaw sizing. Due to this difference, the inspection result may cause flaw sizing error. Therefore, the objective of this study is to compare and evaluate the ultrasonic amplitude difference between air filled and water filled pipe in nuclear power plant. Additionally, the accuracy of flaw sizing is estimated by comparing both conditions.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.286-288
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• 2005

If we are to realize the everyday benefits promised by pervasive computing and context-aware applications, we must first develop the infrastructure to provide contextual location and orientation information through pervasive computing elements. We have implement indoor positioning system to supply orientation information. We have used ultrasound in indoor positioning system for distance and orientation measurements, then propose a set of methods to calculate orientation from an array of well placed ultrasonic sensors operating in the indoor positioning system. We have design and implement a indoor positioning system using a combination of hardware and software and demonstrate end-to-end functionality of the system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 추계학술대회 논문집 학회본부
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• pp.252-257
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• 1988

This paper discribes an improved technique for locating partial discharge sites within operating transformers by ultrasonic method which utilizes the different travel times of the electrical and ultrasonic signals produced by partial discharges to determine the location of the sources. The technique was to develope the measurement system based on the enhancement of the acoustic emission signals using signal square, circuit to improve the detectable sensitivity and reliability. Also an ultrasonic pulse generator was designed and made to transmit periodically pulses equivalent to pratial discharges and to check the good performance of the system, echo effects and self-diagnosis. Through the laboratory work, it was confirmed that the system and the generator can be used satisfactorily for diagnosing power transformers and for studying echo effects and self-diagnosis of the system.

• 한국자동차공학회논문집
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• 제16권2호
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• pp.66-73
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• 2008

In this paper, ultrasonic range system which detects parking lot in parking area is studied. The important part for detecting parking lot accurately is to detect the first and second corners of possible parking lot, and for that, new method using multiple echo function is introduced in this paper. Many probabilistic methods have been used to reduce uncertainties of ultrasonic sensor for distance and location of objects. Method using multiple echo, however, gives accurates results as well as simple algorithm. For experiments in parking space, ultrasonic range system was attached to a Pioneer AT-2 and final parking space map was created in a fusion with position information from wheels of a Pioneer AT-2. We will show the results are compared with error of another methods.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.83-88
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• 2006

Many applications in the area of location-based services and personal navigation require nowadays the location determination of a user not only in outdoor environment but also indoor. To locate a person or object in a building, systems that use either infrared, ultrasonic or radio signals, and visible light for optical tracking have been developed. The use of WiFi for location determination has the advantage that no transmitters or receivers have to be installed in the building like in the case of infrared and ultrasonic based location systems. WiFi positioning technology adopts IEEE802.11x standard, by observing the radio signals from access points installed inside a building. These access points can be found nowadays in our daily environment, e.g. in many office buildings, public spaces and in urban areas. The principle of operation of location determination using WiFi signals is based on the measurement of the signal strengths to the surrounding available access points at a mobile terminal (e.g. PDA, notebook PC). An estimate of the location of the terminal is then obtained on the basis of these measurements and a signal propagation model inside the building. The signal propagation model can be obtained using simulations or with prior calibration measurements at known locations in an offline phase. The most common location determination approach is based on signal propagation patterns, namely WiFi fingerprinting. In this paper the underlying technology is briefly reviewed followed by an investigation of two WiFi positioning systems. Testing of the system is performed in two localization test beds, one at the Vienna University of Technology and the second at the Hong Kong Polytechnic University. First test showed that the trajectory of a moving user could be obtained with a standard deviation of about ${\pm}$ 3 m.

• 정보과학회 컴퓨팅의 실제 논문지
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• 제22권6호
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• pp.268-277
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• 2016

사물인터넷이 대중화되면서 주차장에도 사물인터넷 환경을 구축해 이용객이 주차한 차량의 위치 식별 및 주차 위치 안내 서비스를 제공하려는 연구가 진행되고 있다. 기존 시스템들은 차량을 식별하기 위해 식별 장치를 차량에 부착하거나 이용객이 소지하는 방법 또는 고화질 카메라를 이용하여 주차된 차량의 번호판을 인식하는 방법 등을 이용하고 있다. 하지만 이 방법들은 이용 방법과 비용 측면에서 아쉬운 면을 보였다. 본 논문에서는 초음파 센서와 블루투스 통신을 이용한 스마트 실내 주차장 관리 시스템을 제안한다. 제안하는 시스템은 각 주차공간에 설치된 주차장 센서 모트의 초음파센서를 이용하여 차량의 점령을 판단하고 블루투스의 RSSI를 이용하여 주차된 차량의 위치 식별이 가능하다. 또한 블루투스 RSSI를 이용한 실시간 실내 위치 인식을 통해 주차된 차량까지의 길 안내 서비스가 가능하다. 시스템의 성능평가를 위해 주차된 차량의 위치 인식률과 RSSI를 변환해 얻은 거리의 정확도를 측정하였다.

• 비파괴검사학회지
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• 제10권2호
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• pp.32-37
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• 1990

A computer controlled 5 axis ultrasonic testing system is developed in order to detect flaws in special parts with complex shape. The various kinds of ultrasonic test can be performed automatically using computer program which was developed by DHI(Daewoo Heavy Industries Ltd.). By use of this computer program, the detector location can be programed and the amplitude signal of echo can be processed digitally. The test results can be plotted graphically on a high resolution display monitor in real time base. The test data can be also saved in magnetic memory devices(HDD or FDD) as well as in the form of hard copy through color printer. The computer software contains c- scan, c+a scan processing programs as well as statistical analysis for test data.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.588-590
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• 1993

This paper presents a diagnostic technique using ultrasonic for operating power transformer. Two methods are used as a base for detecting a partial discharge. One is a analysis of PD trend using counted ultrasonic signal, the other is a estimation of PD location source using cross-correlation. In this paper we implement detection equipment of partial discharge in power transformer. The desired system is utilized to two methods for PD detection and operated by graphical user interface(GUI). The results of test showed that the system can be adopted to real power transformer.