• Journal of Korea Water Resources Association
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• v.48 no.7
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• pp.535-543
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• 2015

Measurements of multiphase flows containing bubbles have been limited because most existing methods target one phase flows. Especially, multiphase flows with a high void ratio have been rarely successful in measurements due to the sudden change of density and thick interfaces between air and water. This study introduces two methods that are capable of measuring flow fields regardless of bubble void ratio, named bubble image velocimetry and bundle fiber optic flow meter. The calculation of the depth of field is suggested to reduce and estimate errors by perspective image velocimetry. The bundle fiber optic flow meter is designed to increase a measurement rate using many optical fibers with a thin diameter. The two methods measured bubble plumes to test reliability and the velocity measurements show good agreement. In addition a hydraulic jump, one of the multiple flows in rivers was measured to test applicability of the methods.

• Journal of Sensor Science and Technology
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• v.26 no.1
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• pp.15-23
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• 2017

In this study, bioelectrical impedance analysis, which has been used to assess an alteration in intracellular fluid (ICF) of the body, was applied to detect intravenous infiltration. The experimental results are described as follows. Firstly, when infiltration occurred, the resistance gradually decreased with time and frequency i.e., the resistance decreased with increasing time, proportional to the amount of infiltrated intravenous (IV) solution. At each frequency, the resistance gradually decreased with time, indicating the IV solution (also blood) accumulated in the extracellular fluid (ECF) (including interstitial fluid). Secondly, the resistance ratio started to increase at infiltration, showing the highest value after 1.4 min of infiltration, and gradually decreased thereafter. Thirdly, the impedance ($Z_C$) of cell membrane decreased significantly (especially at 50 kHz) during infiltration and gradually decreased thereafter. Fourthly, Cole-Cole plot indicated that the positions of (R, $X_C$) shifted toward left owing to infiltration, reflecting the IV solution accumulated in the ECF. The resistance ($R_0$) at zero frequency decreased continuously over time, indicating that it is a vital impedance parameter capable of detecting early infiltration during IV infusion. Finally, the mechanism of the current flowing through the ECF, cell membrane, and ICF in the subcutaneous tissues was analyzed as a function of time before and after infiltration, using an equivalent circuit model of the human cell. In conclusion, it was confirmed that the infiltration could be detected early using these impedance parameters during the infusion of IV solution.

• Journal of KIISE
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• v.43 no.12
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• pp.1365-1375
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• 2016

One of the most important capabilities for autonomous service robots working in living environments is to recognize and understand the correct context in dynamically changing environment. To generate high-level context knowledge for decision-making from multiple sensory data streams, many technical problems such as multi-modal sensory data fusion, uncertainty handling, symbolic knowledge grounding, time dependency, dynamics, and time-constrained spatio-temporal reasoning should be solved. Considering these problems, this paper proposes an effective dynamic context management and spatio-temporal reasoning method for intelligent service robots. In order to guarantee efficient context management and reasoning, our algorithm was designed to generate low-level context knowledge reactively for every input sensory or perception data, while postponing high-level context knowledge generation until it was demanded by the decision-making module. When high-level context knowledge is demanded, it is derived through backward spatio-temporal reasoning. In experiments with Turtlebot using Kinect visual sensor, the dynamic context management and spatio-temporal reasoning system based on the proposed method showed high performance.

• Journal of Drive and Control
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• v.17 no.1
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• pp.37-43
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• 2020

An intelligent excavator can be divided into Machine Guidance (MG), semi-automatic, and unmanned by technology. The MG technology excavator is equipped with a tilt sensor on each link of the excavator and a GPS is installed on the excavator body to inform the user of the position of the excavator bucket end. Machine control (MC) technology that assists the user's work can be divided into semi-automatic and fully automatic technology. The semi-automatic MC equipment has already been commercialized by Komatsu and Caterpillar. The MC excavator is equipped with an electro-hydraulic system, sensors and controllers to control the excavator bucket end according to the user's needs. In this study, the semi-automated excavator modified based on manual excavator, is equipped with an electro-hydraulic system, a controller system, multi-sensors and a control algorithm is developed to assist in excavation work such as leveling and grading. By applying the developed technology, it was possible to confirm productivity improvement compared to manual digging and leveling work. In the future, further research to improve the accuracy of the hydraulic precision control and collaborative work with heterogeneous construction equipment such as dump truck and automated collaboration tasks technology could be developed.

• Imaging Science in Dentistry
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• v.47 no.1
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• pp.25-31
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• 2017

Purpose: The aim of this study was to compare the diagnostic accuracy of previously trained endodontists in the detection of artificially created periapical lesions using cone-beam computed tomography (CBCT) and digital periapical radiography (DPR). Materials and Methods: An ex vivo model using dry skulls was used, in which simulated apical lesions were created and then progressively enlarged using #1/2, #2, #4, and #6 round burs. A total of 11 teeth were included in the study, and 110 images were obtained with CBCT and with an intraoral digital periapical radiographic sensor (Instrumentarium dental, Tuusula, Finland) initially and after each bur was used. Specificity and sensitivity were calculated. All images were evaluated by 10 previously trained, certified endodontists. Agreement was calculated using the kappa coefficient. The accuracy of each method in detecting apical lesions was calculated using the chisquare test. Results: The kappa coefficient between examiners showed low agreement (range, 0.17-0.64). No statistical difference was found between CBCT and DPR in teeth without apical lesions (P=.15). The accuracy for CBCT was significantly higher than for DPR in all corresponding simulated lesions(P<.001). The correct diagnostic rate for CBCT ranged between 56.9% and 73.6%. The greatest difference between CBCT and DPR was seen in the maxillary teeth (CBCT, 71.4%; DPR, 28.6%; P<.01) and multi-rooted teeth (CBCT, 83.3%; DPR, 33.3%; P<.01). Conclusion: CBCT allowed higher accuracy than DPR in detecting simulated lesions for all simulated lesions tested. Endodontists need to be properly trained in interpreting CBCT scans to achieve higher diagnostic accuracy.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.12
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• pp.1128-1139
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• 2013

KOMPSAT-5(KOrea Multi-Purpose SATellite-5) has a benefit of continuously conducting its mission in all weather and even night by loading SAR(Synthetic Aperture Radar) payload, which is different from optical sensor of KOMPSAT-2 satellite. During IOT(In-Orbit Test) periods, SAR image calibration should be conducted through ground target of which location and RCS is pre-determined. Differently from the conventional corner reflector, active transponder has a capability to change its internal transfer gain and delay, which allows active transponder to be shown in a pixel of SAR image with very high radiance and virtual location. In this paper, the development of active transponder is presented from design to I&T(Integration and Test).

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.74-78
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• 2003

Multi-channel images of 11-MUA and 11-MUOH self-assembled monolayers were obtained by using two-dimensional surface plasmon resonance (SPR) absorption. Patterning process was simplified by exploiting direct photo-oxidation of thiol bonding (photolysis) instead of conventional photolithography. Sharper images were resolved by using a white light source in combination with a narrow bandpass filter in the visible region, minimizing the diffraction patterns on the images. The line profile calibration of the image contrast caused by different resonance conditions at each points on the sensor surface (at a fixed incident angle) enables us to discriminate the monolayer thickness in sub-nanometer scale. Furthermore, there is no signal degradation such as photo bleaching or quenching which are common in the detection methods based on the fluorescence.

• 한국공간정보시스템학회:학술대회논문집
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• 2007.06a
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• pp.147-155
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• 2007

본 연구는 기술개발 자체의 효과성을 개발된 기술의 시장성, 확대 보급가능성, 민간분야의 기술 로드맵과의 관계성을 도출하는 것으로 실제로 업계에서 다양한 인맥과 프로젝트의 경험을 가지고 있는 자에 의한 심층인터뷰를 근거로 한 정성적 판단과 시장조사를 통한 정량적 판단을 결합하여 멀티센서의 기술개발의 가치를 평가하는 후속 조치에 해당되는 연구이다. 직접적 측면의 산업적 파급효과는 2006년에는 시범적인 수준에서 적용된 사례를 중심으로 정리해 본 결과, 다음과 같이 요약될 수 있다. 첫째, 전문화된 기업의 경우 각자의 강점에 기반을 두어 멀티센서의 적용시장을 바라보고 있다는 점이다. 모든 소프트웨어의 생산을 서버 부분부터 웹 버전, 모바일 버전까지 모두 보유하고 있는 벡터 부분의 GIS 수준과는 달리 위성영상 및 멀티센서 분야의 소프트웨어는 대용량으로 인한 한계로, 서버중심, 웹 중심의 개발이 이루어지고 있으나 모바일 분야까지 확장되지는 않고, 차량항법장치와의 연계를 통한 확장을 꾀하는 수준이라고 요약할 수 있다. 둘째, 전문기업이 아닌 대기업의 시장분석 및 전략에 관한 부분을 요약하자면, 멀티센서와 직접적인 연관을 갖는 회사는 많지 않으나 대체로 U-city 사업 발굴 시 멀티센서가 융합기술이 요소기술로서 기여할 수 있을 것이라는 기대는 하고 있으며, 규모도 1,000억 원 대를 상회할 것으로 바라보고 있다. 셋째, 멀티센서 개발기술의 상용화 및 산업화를 위한 제거 요소 및 감소 요소, 증가 요소 및 새로이 만들어야 할 요소 등을 다차원 전략으로 제시하였으나, 전략을 구사할 기관이 산재되어 있어 제도적 차원의 뒷받침이 기술개발과 더불어 진행되어야 한다는 결론에 이르게 된다. 넷째, 개발된 4개의 기술에 대하여 KVA에서 산출한 기업평가 방식을 변형하여 적용하였는데, 위성영상과 DEM 개발기술이 87% 이상의 점수를 받아 가장 시장성 및 활용성이 높은 기술로 평가되었으며, 초다분광영상에 대한 기술은 70%를 겨우 넘는 수준에서 평가가 되었다. 멀티센서 공간영상정보 통합처리 기술 개발은 다목적 실용위성의 보유, 국가 NGIS 사업의 결과물이 상당히 축척이 되어 있고, 라이다(LiDAR) 기술의 도입을 위한 환경이 조성되었기에 다른 국가에 비해 멀티센서 기술의 적용과 산업화가 가시화 될 수 있을 것으로 기대된다. 그러나 멀티센서 자료의 수급이 용이하지 못하고, 법 제도적인 한계, 시장의 성숙도가 기대이하라는 점 등의 한계를 노정하고 있다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.35 no.6
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• pp.485-494
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• 2017

This study focuses on automatic image registration between multiple IR images using simple preprocessing method and modified local feature extraction algorithm. The input images were preprocessed by using the median and absolute value after histogram equalization, and it could be effectively applied to reduce the brightness difference value between images by applying the similarity of extracted features to the concept of angle instead of distance. The results were evaluated using visual and inverse RMSE methods. The features that could not be achieved by the existing local feature extraction technique showed high image matching reliability and application convenience. It is expected that this method can be used as one of the automatic registration methods between multi-sensor images under specific conditions.

• Korean Journal of Remote Sensing
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• v.31 no.3
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• pp.245-253
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• 2015

According to wide civilian utilization of multi sensor satellite information, practical needs for fusion processing and interoperable operation with multiple remote sensing imageries within distributed remote server are being increased. For this task, OGC standards with respect to satellite images and its derived products are crucial factors. This study is to present an applicability of WPS through testing implementation of image processing algorithm. Open sources such as Geoserver and OTB were used linked to WPS application for implementation. WPS can be solely used for web service supporting geoprocessing algorithm, but technical consideration compromising with other important standard protocols including WMS, WFS, WCS, or WMTS is necessary to build full featured geo web for remote sensing imageries. It is expected that application of these international standards for geo-spatial information is an important approach to produce value-added results by interoperable processing between interorganizations or information dissemination containing practical satellite image processing functionalities.