미세 골절 진달을 위한 초음파 C-scan의 활용 가능성

박원근,최민주,이원흠,이윤준,이헌주,강창익,박전홍 제주대학교 공과대학 첨단기술연구소 2001 尖端技術硏究所論文集 Vol.12 No.2

The study examines the medical potential of an ultrasonic C-scanning technique and for diagnosis of the fatigue induced micro-fractures of the bone. In general, it is not easy to detect the micro­fracture by a simple radiological technique. In the study, the micro­fractures were made on the tibia taken from pigs using a three point bending. Comparison was made between the ultrasonic C-scan images (25 MHz) and X-ray images of the bones with the micro-fractures, It was found that the micro-fractures invisible on the X-ray images were observed on the ultrasonic images. It is proposed further in-vitro and in-vivo studies making the ultrasonic C-scan technique clinically useful for the diagnosis of the fatigued induced micro-fractures of the bone which are not possible to detect by the conventional radiological method.

그리드 연관성을 이용한 지능로봇용 환경 지도 형상의 신뢰성 향상에 관한 연구

임종환,이세진,강철웅 제주대학교 공과대학 첨단기술연구소 2005 尖端技術硏究所論文集 Vol.16 No.2

This paper addresses a new feature map building method that can minimizes the appearance of phantom features by using only sparse sonar data. The approach is composed of extraction of features and building a probability grid map using only the footprint of sparse sonar data, estimation of position uncertainty of the feature, and evaluation of the reliable features. A virtual circle association frame model has been developed, which associates two sonar footprints into a virtual circle frame. Using this model, geometric primitives such as line, point, or arc features are separately extracted. While extracting the feature, a grid map is also built using the orientation probability approach. Position uncertainty of each extracted feature is, then, estimated by considering both the position uncertainty of the robot and the measurement uncertainty of the sonar sensor. Finally, the reliable features among all extracted ones are evaluated from grid association method. The proposed methods have been tested in a real home environment with a mobile robot.

주택형 태양광발전시설의 전압품질 분석

김세호,김철성 제주대학교 공과대학 첨단기술연구소 2005 尖端技術硏究所論文集 Vol.16 No.2

According to the economy growth and altitude of industrial society life, demands for the electricity enlarge We are faced with serious situation lacking of energy and changes surrounding the earth environment. Related experts commonly have agreed that strong measures must be taken to reserve long-term stability of electricity supply. Meanwhile, solar photovoltatic power generation is drawing most attention from the experts. Because this system uses unlimited and unpolluted solar energy, It doesn't need costs of fuel and doesn't have no air pollution and no waste matter. The paper investigates the influences of Solar photovoltatic power generation system on voltage and harmonics

고온가스냉각로(HTGR) 열전달 연구를 위한 상사실험 방법론 개발

문덕원,고상혁,정범진 제주대학교 공과대학 첨단기술연구소 2005 尖端技術硏究所論文集 Vol.16 No.2

Increasing interests on hydrogen, as a future alternative energy source, have led activities concerning the production, transportation, and use of hydrogen. As an activity to produce hydrogen using the nuclear heat, the development of HTGR(High Temperature Gas-cooled Reactor) are in progress. The gas phase coolant in the HTGR results in the coupling of buoyancy effect and increased radiation effect to most of heat transfer phenomena. In order to overcome those difficulties in the heat transfer study of gas phase coolant, an analogy experiment methodology was developed using analogy concept between heat transfer and mass transfer. The electroplating system with the limiting current technique is adopted to simulate heat transfer systems. Two typical heat transfer problems of Poiseuille flow and laminar and turbulent natural convections with well-known heat transfer correlations, were simulated. The test results show close agreements between heat transfer and mass transfer, which is encouraging indication of the validity of the analogy experiment methodology.

최적배치를 위한 워드모델 및 비트연산자 개발

김영근,조경호 제주대학교 공과대학 첨단기술연구소 2006 尖端技術硏究所論文集 Vol.17 No.1

In this paper, a new nesting method based upon the 'word representation' of parts and raw sheets is proposed to improve the performance of pixel-based nesting. In this new representation, the pixel patterns of parts and sheets are converted to proper word-sets. And all the usual nesting processes such as part allocations, de-allocations, overlap testings and etc. can be performed through the 'bit operations' between words of the parts and sheets. The proposed method shows some possibilities to overcome the shortcomings of the traditional pixel-based nesting. In addition, a new efficient gap searching method based upon the quad-tree is presented to locate proper allocation positions of the parts.

Cage-Link and the Effect of Cross-Link Breakdown

Oh, Teresa,Kim, Kyung-Sik 제주대학교 공과대학 첨단기술연구소 2006 尖端技術硏究所論文集 Vol.17 No.2

Organosilicate films are promising porous low-dielectric materials, which can replace the silicon dioxide films. It was researched that organosilicate films have two different chemical shifts according to the increase of the flow rate ratio. There are the red shift due to the electron deficient substitution group, and the blue shift of the electron rich substitution group. Among these chemical shifts, the blue shift from 1000 cm^(-1) to 1250 cm^(-1) was related with the formation of pores. The methyl radicals of the electron rich substitution group terminate easily the Si-O-Si cross-link, and the Si-O-C cage-link near 1057 cm^(-1) is originated from the cross-link breakdown due to much methyl radicals.

Kinematic Models for Non-stationary Elliptic Region Boundaries in Electrical Impedance Tomography

Ijaz, Umer Zeeshan,Kim, Kyung-Youn 제주대학교 공과대학 첨단기술연구소 2006 尖端技術硏究所論文集 Vol.17 No.2

In this study, we propose kinematic models for dynamic electrical impedance tomography (EIT) shape estimation of regions of known resistivities based on extended Kalman filter(EKF). The EIT inverse problem is formulated as a state estimation problem in which the system is modeled with the state equation and the observation equation. We are especially interested in the estimation of shape of air bubbles and conductive liquid in the industrial process pipelines. The proposed kinematic models are tested with computer simulations. From the simulations, we achieve a promising performance of this approach.

태양광 발전효율 향상을 위한 태양 추적 제어에 관한 연구

송도성,임종환 제주대학교 공과대학 첨단기술연구소 2006 尖端技術硏究所論文集 Vol.17 No.1

The photovoltaic(PV) power generation system transforms unlimited and pollution-free solar energy directly into electronic energy by using solar cells of semi-conductor devices. The PV power is globally attractive renewable energy in relation to problem of environmental pollution, and will be an important future energy sources. In this study the solar tracking system have been developed that can trace the direction of sun to keep the PV array perpendicular to the sun lay. The system is able to localize by itself using GPS, and it do not need a brake system. It uses very low power DC motors, so that it does not need external power. Furthermore, it has an ability to judge whether it is possible to generate or not depending on the light intensity. Also it can maintain the PV array horizontally to prevent from demage when the wind is strong.

유전체 배리어 방전 플라즈마를 이용한 애시드레드 27 수용액의 색도 제거

조진오,김병남,목영선 제주대학교 공과대학 첨단기술연구소 2006 尖端技術硏究所論文集 Vol.17 No.2

The physicochemical processes of dielectric barrier discharge (DBD) such as in-situ formation of chemically active species and emission of UV light were utilized for the decolorization of an aqueous solution formed with distilled water and an azo dye Acid Red 27. The DBD reactor consisted of two coaxial dielectric tubes with different diameters. Aqueous electrolyte solution was filled in the inner tube, which acted as the discharging electrode. The DBD reactor was submerged in the Acid Red 27 solution that was grounded. In this case, the Acid Red 27 solution acted not only as the counter electrode but also as the cooling medium of the DBD reactor. The DBD reactor with the aqueous discharging electrode was found to be more energy-efficient for the generation of ozone than that with typical metal electrode. The chemically active species (mostly ozone) produced in the DBD reactor were well dispersed in the Acid Red 27 solution using a porous gas diffuser, thereby increasing the gas-liquid contact area available for the decolorization. The results have clearly shown that the DBD reactor system was very effective for decolorizing the Acid Red 27 solution. For the purpose of improving the performance of the DBD reactor system, MnO_(2) catalyst was added to the Acid Red 27 solution. It was found that the catalyst significantly enhanced the decolorization.

3상 유도전동기 운전에 대한 고조파 위상각 영향의 분석

고성필,좌종근 제주대학교 공과대학 첨단기술연구소 2005 尖端技術硏究所論文集 Vol.16 No.2

This paper describes an analysis of the effect of low harmonic orders and phase angles on the operation performance of a three-phase induction motor. In the analysis, the voltage harmonic orders from 2 to 7, with the three different voltage distortion factors were chosen except the triple harmonics, and each harmonic order was designed into four kinds of waveforms whose phase angles are divided one cycle into four parts. The analyzed data includes current distortion factor, voltage form factor, current form factor, input voltage, input current, and efficiency. From the analyzed result, it is found that the operation performance of a three-phase induction motor does not vary by phase angle of each individual harmonic order. But both voltage and current form factors related to the waveforms are affected by the harmonic phase angle in odd harmonics.