• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.3
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• pp.808-814
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• 2010

In this paper we executed a SBL(Short Baseline) underwater acoustic positioning system that is a kind of underwater position estimation system to estimates the 3-dimensional position of ROV(Remotely Operated Vehicle) using hydrophones and DAQ(Data Acquisition) system in the basin which dimensions are $3{\times}3{\times}1.7(m)$. For this experiment, we let 4 hydrophones in different positions of the basin for receiver and 1 hydrophone is fixed on the underwater vehicle for transmitting sensor(pinger). These five hydrophones are communicated with each other to find the 3-D positions of the moving ROV in the basin. The measured signals are collected by DAQ system and the positions of the ROV are plotted by LabView program in real-time. To estimate the position of the ROV we used a trigonometric method. In X and Y plane the estimated data has a small errors but in Z plane the estimated data has large errors so we cannot use this data for position control. One solution of this problem is using depth sensor that implemented of the underwater vehicle. Hereafter, we will test in the ocean using designed SBL system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.609-617
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• 2016

In general, Personal Navigation Systems (PNSs) can be defined systems to acquire pedestrian positional information. GPS is an example of PNS. However, GPS can only be used where the GPS signal can be received. Pedestrian Dead Reckoning (PDR) can estimate the positional information of pedestrians using Inertial Measurement Unit (IMU). Therefore, PDR can be used for GPS-disabled areas. This paper proposes a PDR scheme considering various movement types over GPS-disabled areas as combat environments. We propose a movement distance estimation scheme and movement direction estimation scheme as pedestrian's various movement types such as walking, running and crawling using IMU. Also, we propose a fusion algorithm between GPS and PDR to mitigate the lack of accuracy of positional information at the entrance to the building. The proposed algorithm has been tested in a real test bed. In the experimental results, the proposed algorithms exhibited an average position error distance of 5.64m and position error rate in goal point of 3.41% as a pedestrian traveled 0.6km.

• Journal of the Korean Institute of Gas
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• v.23 no.3
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• pp.1-6
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• 2019

The purpose of the present study is to elucidate flue gas recirculation device for reduction of nitrogen oxides using coanda nozzle without adopting additional power driving fan in a waste incinerator. The characteristics of the exhaust gas recirculation flow rate and the average temperature change at the outlet of the mixed gas were investigated according to the change of air supply nozzle gap and the position of air supply nozzle. When the gap of the air supply nozzle was changed to 3.22, 4.03, and 4.84 mm, the largest recirculation flow ratio, which is the ratio of exhaust gas recirculation flow rate and air supply flow rate, was 2.227 for the case with 3.22 mm and its mean temperature at outlet was $594.8^{\circ}C$. When the position of the air supply nozzle changes to the front position, neck position, and expansion position of the coanda nozzle neck, the recirculation flow ratios at the forward position and the neck position were nearly almost the same value, 1.843, and 1.696 at the expansion position, their mean temperatures were $559.8^{\circ}C$ and $544.3^{\circ}C$, respectively.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.3
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• pp.123-128
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• 2021

For accurate speed and current control in industrial applications, SRM (Switched Reluctance Motor) is very important to synchronize the stator phase excitation and rotor position in the drive due to its nature. In general, position sensors such as encoder and resolver are used to generate rotational force by exciting the stator winding according to the rotor position and to control the motor by using speed and position information. However, for these sensors, 1) the cost of the sensors is quite large in terms of price, so the proportion of the motor system to the total system cost is high. 2) In terms of mechanical, position sensors such as encoders and resolvers are attached to the stator to increase the size and weight. In conclusion, in order to drive the SRM, control based on the rotor position information should be basically performed, and it is important to design the SRM driving system according to the environment in consideration of the application field. Therefore, in this paper, we intend to study the driving and control characteristics of SRM through variable switching duty control by designing a low-cost analog driving device, deviating from the general control system using the conventional encoder and resolver.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.149-153
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• 2003

AC 부하를 갖는 동기전동기에 있어서, 동기전동기의 속도리플을 저감시키기 위한 문제를 풀기위해 3가지 제어기법에 대해 비교를 한 후 가장 강인한 제어기법에 대해 분석하였다. AC 부하를 갖는 특별한 제어 대상으로 엑스선 전산화 단층촬영 장치(CT)용 겐트리를 선정하였으며 시스템이 갖는 특별한 구조에 의해 이러한 시스템 특성을 갖는다. 동기전동기의 출력 축에 링(Fing) 모양의 원판 프레임을 갖으며, 이 원판 표면에 무게가 서로 다른 여러 장치(X_선 튜브, X-선 검출기, 고압발생장치, DAS 장치, 온도조절장치 등)를 부착하여 영상 획득 시스템의 회전부를 구축하기 때문이다. 이러한 시스템에서는 무게 평형을 갖지 못하는 편심 무게가 존재하게 되며 이로써 전동기 관점에서는 AC 부하처럼 인식되는 제어 조건으로 인식 될 수 있다. AC 부하를 갖는 동기전동기에 대해 일반적인 벡터제어 알고리즘으로 제어를 수행하면 정상상태에서도 속도 오차가 "0" 으로 줄어들지 않고 AC 형태의 오차 성분이 존재하며 편심 무게의 크기에 비례하여 진폭이 커지는 특성을 갖는다. 이러한 문제점을 해결하기 위하여 Sine파 보상전류를 갖는 속도제어기법, 펀심부하토크 관측기를 이용한 속도제어기법, 그리고 기준모델제어기법을 소개하였다. 각 방법에 대한 실험 결과로부터 편심무게의 변동과 편심 위치의 변동 조건에서 기준모델제어기법이 강인한 제어 특성과 리플저감 측면에서 가장 우수함을 검증하였다. 이로써 AC 부하 조건에서 고정도 속도 제어기가 요구되는 경우 좋은 선택의 지침이 될 수 있다고 본다.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1998.11a
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• pp.60-63
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• 1998

본 연구에서는 유류 오염토양 복원을 위한 효율적인 세척공정을 구성하여 현장적용 가능성을 검토하였다. 토양세척공정은 co-current식 전세척장치와 counter -current식 세척조로 구성된다. 물이 주입되는 co-current식 전세척장치에서는 스크류 축의 회전력에 의한 토양 이송 및 스크류의 각 pitch 사이에 부착된 임펠러의 기계적 교반력에 의한 세척이 동시에 이루어진다. 전세척장치를 통과한 토양과 물은 세척조로 유입되어 세척용액과 반대방향으로 이동하게 된다. 세척조의 내벽에 부착된 나선형 웨어에 의해 적정 운전조건하에서 일정 크기를 기준으로 토양이 분리되며, 각 웨어 사이에 부착된 임펠러의 교반력에 의해 오염토양이 세척된다. 실험결과, 운전시 고려해야 할 주요 영향인자들은 전세척장치에서의 토양주입량은 1 kg/min, 진탕비는 1, 회전속도는 50 rpm에서 최대 세척효율(#4-, 83.6%)을 보였으며, 세척조에서는 토양.물 주입위치 15 cm, 회전속도 5 rpm, 경사각 6$^{\circ}$, 세척용액 주입유량이 0.8 L/min일 때 최대 세척효율인 97.9%(#4-)를 나타냈다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.6
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• pp.31-39
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• 2011

For rapid formed the ad hoc wireless backbone network in disaster scene, It is necessary for real-time deployment scheme of wireless ad hoc relay devices by first responders without pre-planning. However, in order to realize this scheme, redundant deployment should be minimized, as well as optimal location of relay devices should be selected to expand communication coverage. Therefore, in this paper, we propose a new deployment scheme of relay devices to optimize communication coverage and then through simulations showed that improved performance of algorithm.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.12
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• pp.1217-1222
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• 2012

A wall flow sensor has been used for feedback flow control and wall shear stress measurement. In this study, we developed a new wall flow sensor by combining the PIV algorithm and the micro image sensor used in an optical mouse. The feasibility of the wall flow sensor was investigated by using simulated fluid flow experiments. Compared with the quadrature signal from imaging devices, the accuracy of the wall flow velocity measurement was improved and the dynamic range increased. In addition, the depth information of particles was also measured by using the defocusing imaging technique.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.434.1-434.1
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• 2014

최근 자성 나노 입자를 이용한 온열치료가 주목을 받고 있다. 자성을 띄는 나노 입자를 암 세포에 보내, 교류 자기장을 걸어주어 회전에 의한 마찰손실로 인한 열을 이용하여 암 조직만을 국소 가열하는 원리이다. 본 실험은 유도 자기장을 사용한 자성 나노 파우더의 가열을 목적으로 시행하였다. 나선형 코일위에 세라믹, 유리 등 절연체 원판 위에 자기장이 발생되도록 휴대용 평판형 자기장 발생장치를 제작하였다. 자기장 발생 장치는 평판형 나선형 코일에 특정 주파수를 가진 전원을 인가하여 자기장을 발생시킨다. 평판형 나선형 코일은 내경 40 mm, 외경 140 mm, 2 mm 동선으로 제작하였다. 제작한 자기장 발생장치를 자기장 측정 센서(Hall sensor 등)을 원판 위에 설치하여 거리별 자기장의 크기를 측정하였다. 자기장은 나선형 코일 위 원판 중심에서 최대로 발생되어 중심에서 멀어질수록 크기가 감소하였다. 자기장 발생장치 위에 자성 나노 파우더($Fe_3O_4$와 $CoFe_2O_4$)를 혼합한 용액 시료를 위치시키고 자기 쌍극자 모멘트와 자기장간의 상호작용을 유도한다. 이때 자성 나노 파우더별로 발생하는 열을 열전쌍(TC)이나 Optical fiber를 사용한 Thermometer로 측정하여 비교분석하였다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.3
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• pp.14-21
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• 1989

In the digital transmission equipment, the input jitter tolerance is a function of input timing recovery circuit characteristics. Especially, in the asynchronous multiplexers, it is also a function of the frame format, the buffer sizes in the synchronizer and desynchronizer, the PLL transfer function, and operating range of VCO in PLL In this paper, a new algorithm for calculating the jitter tolerance of the saynchronous digital transmission equipment is presented. With the new algorithm, we analyzed how the above factors limit the jitter tolerance in the equipment. We also measured the input jitter tolerance for a 45M-140M multiplexing equipment, whose results show the same trend with calculated tolerance.