• 제어로봇시스템학회논문지
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• 제12권4호
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• pp.389-394
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• 2006

Inaccurate localization exposes a robot to many dangerous conditions. It could make a robot be moved to wrong direction or damaged by collision with surrounding obstacles. There are numerous approaches to self-localization, and there are different modalities as well (vision, laser range finders, ultrasonic sonars). Since sensor information is generally uncertain and contains noise, there are many researches to reduce the noise. But, the correctness is limited because most researches are based on statistical approach. The goal of our research is to measure more exact robot location by matching between built VRML 3D model and real vision image. To determine the position of mobile robot, landmark-localization technique has been applied. Landmarks are any detectable structure in the physical environment. Some use vertical lines, others use specially designed markers, In this paper, specially designed markers are used as landmarks. Given known focal length and a single image of three landmarks it is possible to compute the angular separation between the lines of sight of the landmarks. The image-processing and neural network pattern matching techniques are employed to recognize landmarks placed in a robot working environment. After self-localization, the 2D scene of the vision is overlaid with the VRML scene.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1921-1926
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• 2003

We build a local minimum free motion planning for mobile robots considering dynamic environments by simple sensor fusion assuming that there are unknown obstacles which can be detected only partially at a time by proximity sensors and can be cleaned up or moved slowly (dynamic environments). Potential field is used as a basic platform for the motion planning. To clear local minimum problem, the partial information on the obstacles should be memorized and integrated effectively. Sets of linked line segments (SLLS) are proposed as the integration method. Then robot's target point is replaced by virtual target considering the integrated sensing information. As for the main proximity sensors, we use laser slit emission and simple web camera since the system gives more continuous data information. Also, we use ultrasonic sensors as the auxiliary sensors for simple sensor fusion considering the advantages in that they give exact information about the presence of any obstacle within certain range. By using this sensor fusion, the dynamic environments can be dealt easily. The performance of our algorithm is validated via simulations and experiments.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.434-438
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• 2003

The shearing process for the sheet metal is normally used in the precision elements such as semi-conductor components. In these precision elements, the burr formation brings a bad effect on the system assembly and demands the additional de-burring process. In this paper, we have developed the desktop-type precision punching system to investigate the burr formation mechanism and present kinematically Punch-die auto aligning methodology, for the purpose of burr unifomizing and minimizing, between the rectangular shaped punch and die. By using the scanning electron microscope, the aligned punching results are compared with the miss-aligned ones. Also, we measured the relative burr heights using the self-designed laser measuring device for insitu self aligning. Since it is hard to get the perfect, so called, burr-free edges during the shearing process, we introduced the ultrasonic do-burring machine. The de-burring operation was carried out by a novel do-burring method, the reversal flow resistance method, under different machining loads and abrasive types. The final do-burring results show the validity of our punching do-burring system pursuing the burr-free punched elements.

• Korean Journal of Acupuncture
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• 제28권3호
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• pp.113-126
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• 2011

Objectives : We have examined and analyzed patents regarding acupuncture point stimulating methods in order to understand the stimulation technology and research trends of acupuncture points. Methods : We searched and analyzed the total of 135 on-line DB based patents under time limit of Dec, 2010. Results : According to the analyzed results, non-invasive method is used more than invasive method. Electric stimulation is used more than any other method, such as magnetic, ionic, laser, light, ultrasonic, water, Far IR and thermal stimulation. There are numbers of cases such as rejected during screening procedure, waived before the screening, of failed to renew its registrational status which outnumber those patents registered and maintained. Conclusions : These data suggest that we need to move away from using one side method such as non-invasive and electrical method. Thus follow-up service is recommended.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제38권4호
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• pp.195-203
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• 2012

Dental implants using titanium have greatly advanced through the improvement of designs and surface treatments. Nonetheless, the anatomical limits and physiological changes of the patient are still regarded as obstacles in increasing the success rate of implants further, even with the enhancement of implant products. So there have been many efforts to overcome these limits. The intrinsic potential for bone regeneration can be stimulated through adjuvant treatments with the continuous improvement of implant properties, and this can play an important role in achieving optimum osseointegration toward peripheral bone tissue and securing ultimate long-term implant stability in standard surgical procedures. For this purpose, various chemical, biological, or biophysical measures were developed such as bone grafts, materials, pharmacological agents, growth factors, and bone formation proteins. The biophysical stimulation of bone union includes non-invasive and safe methods. In the beginning, it was developed as a method to enhance the healing of fractures, but later evolved into Pulsed Electromagnetic Field, Low-Intensity Pulsed Ultrasound, and Low-Level Laser Therapy. Their beneficial effects were confirmed in many studies. This study sought to examine bone-implant union and its latest trend as well as the biophysical stimulation method to enhance the union. In particular, this study suggested the enhancement of the function of cells and tissues under a disadvantageous bone metabolism environment through such adjunctive stimulation. This study is expected to serve as a treatment guideline for implant-bone union under unfavorable circumstances caused by systemic diseases hampering bone metabolism or the host environment.

• 한국정밀공학회지
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• 제13권2호
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• pp.68-75
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• 1996

More accurate inspection method for facilities of nuclear power plants is required to guarantee the continuous and stable energy supply. The portion of inspection for pipes and pressure vessels is relatively big in the power plants. Conventional inspection methods using ultrasonic wave, x-ray and eddy current for nondestructive testing in nuclear power plants have been performed as the method of contact with objects to be inspected. With this reason these methods have been taken relatively much time, money and manpower. And the area to be inspected is limited by the location of probe or film. These difficulties make the inspection into a time-consuming work. We propose an optical defect detection method using phase shifting realtime holographic interferometry. This method has an advantage that the inspection can be performed at a time for relatively wide area illuminated by the laser beam, a coherent light source and can help an inspector recognize not only defects but also the high stressed areas. In this paper we show that the quantitative measurement using holographic interferometry and image processing for defect in pressure vessels is possible.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.388-393
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• 2001

An experimental study is conducted to investigate the interaction of vortices over a delta wing with leading edge extension(LEX) through the off-surface flow visualization and the 5-hole probe measurements of the wing wake region. Especially, the application of a new visualization technique is employed by ultrasonic humidifier water droplet and laser beam sheet. The results, both the off-surface visualization and the 5-hole probe, show that LEX tends to stabilize the vortices of the delta wing up to the high angle of attack even though the model is yawed. With increasing yaw, the windward leading edge vortex moves inward, and closer to the wing surface, while the leeward vortex moves outwards and away from the wing surface. The vortex interaction is promoted in the windward side, and is delayed in the leeward side.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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• pp.136-136
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• 1999

박막의 탄성특성을 평가하는 방법으로 nano-indentation, Brillouin light scattering measurement, ultrasonic surface wave measurement, bulge test, vibration membrane method 등 여러 가지가 제시되어 왔다. 최근에는 탄성특성을 평가할 수 있는 간단한 방법으로 기판 식각 기법을 이용한 freehang, bridge 방법이 제시되었다. 이중에서 bridge 방법은 간단한 식각 기법을 이용하여 얇은 박막에서도 탄성 특성을 평가할 수 있는 방법으로 제시되었다. 그러나 식각 과정에서 발생하는 patch 부분의 under-cut으로 인해 정확한 bridge의 길이를 측정할 수 없게 되어 오차가 발생하고 있다. 본 연구에서는 bridge 방법에서 발생하는 오차를 줄이기 위한 방법으로, patch 부분에 etch-stop을 제작해 줌으로서 식각 과정에서 발생하는 under-cut을 효과적으로 제거시켰다. Etch-stop은 2장의 mask를 align key를 이용하여 제작하였다. 먼저 산화막이 형성되어 있는 Si 기판위에 mask 1을 이용하여 patch 부분을 lithography 작업하고, 습식 식각 공정을 한 뒤 DLC 필름을 증착시킨다. 다음으로 mask 2를 이용하여 bridge pattern을 제작하고, DLC 필름을 증착시킨 후 lift-off 기술과 산화막 등방식각 공정을 통해 bridge를 제작하였다. 이렇게 제작된 bridge를 통해 필름이 기판에 부착되기 위해 필요한 변형률을 측정하고, 독립적으로 측정된 필름의 잔류응력과 함께 박막의 응력-변형률 관계식에 적용시켜 biaxial elastic modulus, E/(1-v)를 구할 수 있었다. Sidl 첨가된 DLC 필름은 rf-PACVD 장비를 이용하여 증착하였다. 이때 전극과 플라즈마 사이의 바이어스 음전압은 -400V로 합성압력은 10mTorr로 고정하였다. 사용한 반응가스는 벤젠(C6H6)과 희석된 실렌(SiH4:2H=10:90)이며, 희석된 실렌의 첨가량을 조절하여 필름 내에 함유된 Si의 양을 조절하였다. 각각의 조건에서 증착시간을 조절하여 필름의 두께를 조절하였다. 필름의 잔류응력은 압축잔류 응력에 의해 발생한 필름/기판 복합체의 곡률을 laser 반사법을 이용하여 측정하고, 이 결과를 Brenner 등에 의해 유도된 식을 대입하여 계산하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 심포지엄 논문집 정보 및 제어부문
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• pp.318-320
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• 2006

Inaccurate localization exposes a robot to many dangerous conditions. It could make a robot be moved to wrong direction or damaged by collision with surrounding obstacles. There are numerous approaches to self-localization, and there are different modalities as well (vision, laser range finders, ultrasonic sonars). Since sensor information is generally uncertain and contains noise, there are many researches to reduce the noise. But, the correctness is limited because most researches are based on statistical approach. The goal of our research is to measure more exact robot location by matching between built VRML 3D model and real vision image. To determine the position of mobile robot, landmark-localitzation technique has been applied. Landmarks are any detectable structure in the physical environment. Some use vertical lines, others use specially designed markers, In this paper, specially designed markers are used as landmarks. Given known focal length and a single image of three landmarks it is possible to compute the angular separation between the lines of sight of the landmarks. The image-processing and neural network pattern matching techniques are employed to recognize landmarks placed in a robot working environment. After self-localization, the 2D scene of the vision is overlaid with the VRML scene.

• 제어로봇시스템학회논문지
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• 제12권10호
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• pp.968-974
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• 2006

We are moving into the era of ubiquitous computing. Ubiquitous Sensor Network (USN) is a base of such computing paradigm, where recognizing the identification and the position of objects is important. For the object identification, RFID tags are commonly used. For the object positioning, use of sensors such as laser and ultrasonic scanners is popular. Recently, there have been a few attempts to apply RFID technology in robot localization by replacing the sensors with RFID readers to achieve simpler and unified USN settings. However, RFID does not provide enough sensing accuracy for some USN applications such as robot navigation, mainly because of its inaccuracy in distance measurements. In this paper, we describe our approach on achieving accurate navigation using RFID. We solely rely on RFID mechanism for the localization by providing coordinate information through RFID tag installed floors. With the accurate positional information stored in the RFID tag, we complement coordinate errors accumulated during the wheel based robot navigation. We especially focus on how to distribute RFID tags (tag pattern) and how many to place (tag granularity) on the RFID tag-floor. To determine efficient tag granularities and tag patterns, we developed a simulation program. We define the error in navigation and use it to compare the effectiveness of the navigation. We analyze the simulation results to determine the efficient granularities and tag arrangement patterns that can improve the effectiveness of RFID navigation in general.