• 대한기계학회논문집
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• 제19권5호
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• pp.1176-1181
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• 1995

Microdrilling is one of the most difficult operations because of the poor chip discharge and the weakness of tool. This study is concerned about the development of a microdrilling monitoring system that is useful for minimizing the tool breakage and enhancing the machinability in the air spindle based microdrilling. The system is composed of a drilling state detection unit and an adaptive step-feed control unit that controls the micro-stepping motor driven spindle axis. Drilling states such as overload, tood breakage are recognized by the change of the air spindle speed which is measured via the reflective photo sensor. Based on the monitoring results, the adaptive step-feed control algorithm adjusts the step increment to keep the decrease of spindle speed within a specified range. The results of evaluation tests have shown that the developed system is very effective to prevent the breakage of microdrill and improves the productivity in comparison with the conventional microdrilling.

• 한국정보통신학회논문지
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• 제12권3호
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• pp.590-595
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• 2008

본 논문에서는 적응형 TMS(굴뚝배출가스 감시시스템) 면적식 유량계를 제안하였다. 이 유량계는 투명한 재질의 유리 테이퍼관 내부에 흐르는 유량의 증감에 따라 상하로 움직이는 플로트의 위치를 테이퍼관을 따라 일직선상으로 배열된 광센서로 검지하고, 설정한 값에 대응한 가스 유량이 가스 분석기에 인입되도록 실시간으로 서보모터 구동회로를 최적 제어하는 방법을 채택하였다. 제안한 유량계는 테이퍼 관에 흐르는 유량을 단계별로 검지할 수 있을 뿐만 아니라 연속적으로 유량을 제어하기 때문에 튜브라인의 막힘 현상이 발생할 가능성을 미연에 방지할 수 있다.

• 터널과지하공간
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• 제20권3호
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• pp.207-216
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• 2010

국내에서 현재까지 개발되어 적용된 낙석감지 시스템은 주로 낙석방지망에 와이어나 광섬유, 또는 경사계를 설치하여 와이어의 장력을 측정하거나 낙석 발생에 의해 와이어 단락이나 낙석방지망의 변형 또는 기울어지는 것을 감지하여 낙석을 확인하는 시스템들이다. 이러한 방법들은 낙석방지망이 먼저 설치되어 있어야 하며 낙석이 발생하면 일반적으로 관련 센서와 와이어 등에 대하여 재정비를 해야 다시 원래의 기능을 수행할 수 있게 된다. 이러한 단점을 해결하기 위하여 본 연구에서는 장력이나 변위 측정방식이 아니라 광센서와 카메라가 설치된 구역에서 낙석 통과 여부를 비접촉 방식으로 실시간 감지가 가능하도록 하는 방법을 제시하고 이를 구현하였다. 개발된 시스템을 실내실험 및 현장 적용을 한 결과 낙석 관련 정보를 효과적으로 수집하고 분석할 수 있었다. 또한 낙석 감지 전후 획득한 2장의 사진에 대하여 lighten 또는 difference 연산을 적용할 경우 낙석의 크기와 이동 방향에 대한 개략적 평가가 가능하였다.

• Bulletin of the Korean Chemical Society
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• 제31권11호
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• pp.3128-3132
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• 2010

A disposable solid-state pH sensor was realized by utilizing two nanoporous Pt (npPt) electrodes and a copolyelectrolytic junction. One nanoporous Pt electrode was to measure the pH as an indicating electrode (pH-IE) and the other assembled with copolyelectrolytic junction was to maintain constant open circuit potential ($E_{oc}$) as a solid-state reference electrode (SSRE). The copolyelectrolytic junction was composed of cationic and anionic polymers immobilized by photo-polymerization of N,N'-methylenebisacrylamide, making buffered electrolytic environment on the SSRE. It was expected to make. The nanoporous Pt surrounded by a constant pH excellently worked as a solid state reference electrode so as to stabilize the system within 30 s and retain the electrochemical environment regardless of unknown sample solutions. Combination between the SSRE and the pH-IE commonly based on nanoporous Pt yielded a complete solid-state pH sensor that requires no internal filling solution. The solid state pH sensing chip is simple and easy to fabricate so that it could be practically used for disposable purposes. Moreover, the solid-state pH sensor successfully functions in calibration-free mode in a variety of buffers and surfactant samples.

• 한국정밀공학회지
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• 제21권6호
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• pp.94-101
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• 2004

From the Beckmann's reflection model of wave incident, reflected light from a surface is known to have not only specular but also diffuse components. The specular component dominant a surface for a mirror-like surface is distributed on the almost the same area as the spot on the surface, but the diffuse component region dominant f3r a rough surface spreads scattered on the larger areas than the spot. Therefore, statistic parameters from the scattered light distribution are more meaningful in the diffuse region, while the magnitude of rather meaning in the specular region. In usual, there need two sensors to acquire two kinds of information: Photo-detector for light intensity magnitude and image sensor for light intensity distribution. But dual sensor scheme requires a beam splitter usually to feed light to each sensor, and moreover there is not a combination rule to relieve the different sensor characteristics. In this study a new method is proposed for acquisition of the dual information using only an image sensor. Specular region is established on an image area being distinguished from a diffuse component, and laser power is adjusted so that no pixel of the image sensor in the specular region is saturated. Simulation based on the light reflection theory and the experimental results are quite well matched, and thus the proposed method was proved to be very useful for mirror-like surface measurement.

• 한국측량학회지
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• 제23권3호
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• pp.323-330
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• 2005

현재 Direct Georeferencing은 지난 10여년 적용되어오던 GPS-항측의 단점인 항공사진의 6개 외부표정요소중 단지 투영중심의 위치만 제공하던 약점을 극복하고 실무에 보편적으로 적용되고 있는 실정이다. 이의 가장 큰 장점은 지상기준점 측량작업의 절감내지는 이를 완전히 생략할 수 있다는 점이다. 본 본문은 상용의 GPS/IMU 를 이용하여 외부표정요소 결정에 대한 실힘 결과를 소개하였다. 실힘을 위하여 사진축척 1:5,000의 대축척과 1:20,000의 중축척으로 촬영한 관측자료를 처리하여 사진축척의 변화를 고려한 외부표정요소 결정의 정확도 및 결합블럭조정의 특성 등 다양하고 의미 있는 결과들을 도출하였다.

• 제어로봇시스템학회논문지
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• 제6권8호
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• pp.682-688
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• 2000

To improve the performance of a flexible robot arm one of the important things is the vibration displacement measurement of a flexible arm. Many types of sensors have been used to measure it, The most popular has been strain gauges which measures the deflection of the beam,. Photo sensors have also been for detecting beam displacement and accelerometers are often used to measure the beam vibration. But the vibration displacement can be obtained indirectly from these sensors. In this article a vision sensor is used as a displacement sensor to measure the vibration displacement of a flexible robot arm. Several schemes are proposed to reduce the image processing time and increase its accuracy. From the experimental results it is seen that the vision sensor can be an alternative sensor for measuring the vibration displacement and has a potential for on-line tip position control of flexible robot systems.

• 조명전기설비학회논문지
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• 제20권9호
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• pp.103-109
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• 2006

This research is contents about output characteristic of optic current sensor that use faraday effect. optic current sensor used in an experiment is consisted of three parts.(1) Source of light used laser diode of 1310[nm].(2) Sensor section manufactured circularly according to gas insulated switchgear. And $9/125[{\mu}m]$ standard single mode optical fiber for communication was installed winding 20 [turn] on sensor section core surroundings of diameter 31 [cm].(3) Electrical signal of PD(Photo detector) is collected using NI company's 16bit DAQ board via terminal block. Collected data analyzed by different three signal processing methods. NI company's $Labview^{TM}$ was used to signal processing software. As a result, In signal processing of optic current sensor, we could know that noise greatly more influences the error generation than fluctuation of light intensity. also, 1 class CT(current transformer) manufacture that have error rate less than 1[%] was available by removing these

• 한국측량학회지
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• 제25권6_1호
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• pp.529-536
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• 2007

Registration between image and object space is a fundamental step in photogrammetry and computer vision. Along with rapid development of sensors - multi/hyper spectral sensor, laser scanning sensor, radar sensor etc., the needs for registration between different sensors are ever increasing. There are two important considerations on different sensor registration. They are sensor invariant feature extraction and correspondence between them. Since point to point correspondence does not exist in image and laser scanning data, it is necessary to have higher entities for extraction and correspondence. This leads to modify first, existing mathematical and geometrical model which was suitable for point measurement to line measurements, second, matching scheme. In this research, linear feature is selected for sensor invariant features and matching entity. Linear features are incorporated into mathematical equation in the form of extended collinearity equation for registration problem known as photo resection which calculates exterior orientation parameters. The other emphasis is on the scheme of finding matched entities in the aide of RANSAC (RANdom SAmple Consensus) in the absence of correspondences. To relieve computational load which is a common problem in sampling theorem, deterministic sampling technique and selecting 4 line features from 4 sectors are applied.

• 센서학회지
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• 제17권6호
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• pp.447-453
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• 2008

Respiration rate is one of the important vital signs. Photo-plethysmography (PPG) measurement especially on a finger has been widely used in pulse oximetry and also used in estimating respiration rate. It is well known that PPG contains respiration-induced intensity variation (RIIV) signal. However, the accuracy of finger PPG method has been controversial. We introduced a new technique of enhancing motion artifact by respiration. This was achieved simply by measuring PPG on the thorax. We examined the accuracy of these two PPG methods by comparing with two existing methods based on thoracic volume and nostril temperature changes. PPG sensing on finger tip, which is the most common site of measurement, produced 6.1 % error. On the other hand, our method of PPG sensing on the thorax achieved 0.4 % error which was a significant improvement. Finger PPG is sensitive to motion artifact and it is difficult to recover fully small respiratory signal buried in waveform dominated by absorption due to blood volume changes. Thorax PPG is poor to represent blood volumes changes since it contains substantial motion artifact due to respiration. Ironically, this inferior quality ensures higher accuracy in terms of respiration measurement. Extreme low-cost and small-sized LED/silicon detector and non-constrained reflection measurement provide a great candidate for respiration estimation in ubiquitous or personal health monitoring.