• 항공우주시스템공학회지
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• 제18권2호
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• pp.47-55
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• 2024

공중 무인 이동체(UAV)인 드론을 해상 무인 이동체(USV)와 자율 협력하여 임무를 수행하기 위해선 자동 착륙 시스템이 필요하다. 본 논문에서는 피라미드 형상의 착륙 장치와 패드를 기반으로 한 도킹 방식의 자동 착륙 시스템을 제안하였다. 파도, 바람 등 해상 환경에 의해 영향을 받더라도 드론이 착지할 수 있도록 유도하고, 결합(Docking) 장치를 통해 순간적으로 고정할 수 있다. 3-DoF 모션 플랫폼으로 함상의 거동을 모사하여 착륙 시험을 수행하였으며, 도킹 방식 자동 착륙 시스템의 운용·활용 가능성을 확인하였다.

• International Journal of Automotive Technology
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• 제3권2호
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• pp.57-62
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• 2002

It is well known that the entrained air in oil causes appreciable reduction in the stiffness of hydraulic systems. It makes the response delay of the systems and sometimes destroys the stability. Because the hydraulic systems of automatic transmissions are operated in relatively low pressure and high temperature, it is very important to analyze the effects of the air included in automatic transmission fluid. However, it is difficult to derive the generalized model to describe the effective bulk modulus theoretically or measure it in actual operating conditions of automatic transmissions. This paper reviews previous studies of the air effects in hydraulic systems and the measurement techniques of the effective bulk modulus in operating conditions. Based on this work, the theoretical model with moderate complexity and the measurement technique of the effective bulk modulus considering entrained air effect at real operating conditions are suggested. Our paper also shows that the quantity of the entrained air in the automatic transmission fluid can be estimated from the experimental results.

• 대한의용생체공학회:의공학회지
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• 제30권2호
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• pp.153-161
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• 2009

Mammogram is one of the important techniques for mass detection, which is the early diagnosis stage of a breast cancer. Especially, the CAD(Computer Aided Diagnosis) using mammogram improves the working performance of radiologists as it offers an effective mass detection. There are two types of CAD systems using mammogram; automatic and semi-automatic CAD systems. However, the automatic segmentation is limited in performance due to the difficulty of obtaining an accurate segmentation since mass occurs in the dense areas of the breast tissue and has smoother boundaries. Semi-automatic CAD systems overcome these limitations, however, they also have problems including high FP (False Positive) rate and a large amount of training data required for training a classifier. The proposed system which overcomes the aforementioned problems to detect mass is composed of the suspected area selection, the level set segmentation and SVM (Support Vector Machine) classification. To assess the efficacy of the system, 60 test images from the FFDM (Full-Field Digital Mammography) are analyzed and compared with the previous semi-automatic system, which uses the ANN classifier. The experimental results of the proposed system indicate higher accuracy of detecting mass in comparison to the previous systems.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.541-545
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• 1996

In this paper, The performance and functions of automatic flatness control system installed on the 4 hi-reversing mill and has been investigated under actualconditions. A new automatic flatness control system incorporates a measuring roll for measurement and correction calculations, hydraulic roll benders, selective roll cooling, and a programmable controller for interface and data logging. The test results are as following. The more the exit steel strip thickness is thick, the smaller the I value, and the more it is thin, the larger the I value. And, a complex distribution of strip tension was controlled, for example, not only a quarter buckle but also a simple center wave and edge wave. Because the tension deviation is larger at acceleration speed and deceleration speed than steady speed, so automatic flatness control system of contact type is better to adopt over 450 m/min, automatic flatness control system reduces rapidly large flatness deviation. The maximum I value of strip has been decreased to 13 I, and defects caused by poor flatness have been drastically decreased. And coolant temperature for work roll cooling system on the automatic flatness control system is better to adopt about 50-55 .deg. C.

• 제어로봇시스템학회논문지
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• 제10권2호
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• pp.131-138
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• 2004

Automatic flight control system (AFCS) for a low-cost unmanned aerial vehicle is described in this paper. Development process and block diagram of the AFCS are introduced. The flight control law for longitudinal and lateral channel autopilot is designed using optimization process. In this procedure, the performance index is composed of desired location of closed loop system poles and H$_2$norm of the resultant flight control system. This procedure is applied to the autopilot design of an unmanned target vehicle. Performance of the AFCS is evaluated by processor-in-the-loop simulation test and flight test. These results show that the AFCS has acceptable performance fur low cost UAV.

• 한국정밀공학회지
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• 제32권3호
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• pp.243-251
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• 2015

In order to develop an automatic system for welding thin steel plates with curvature such as the corrugated membranes of an LNG storage tank, a rotating mechanism should be firstly designed for the torch to easily follow the weld seam with a constant distance and angle. In this study, a torch rotating mechanism consisting of three circular links, two square-type links and a torch link was proposed for automation of the welding process. A weld-seam tracking system with two axis slides and the proposed rotating mechanism was successfully simulated with a dynamic simulation software. A prototype tracking system was manufactured and a tracking test with the system was then carried out. The test results with tracking system showed that the rotating mechanism could be implemented and it was feasible to be used in automatic tracking of weld seam with curvature.

• 한국항해항만학회지
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• 제33권10호
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• pp.709-713
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• 2009

근해의 수질오염은 수산양식 산업에 큰 영향을 미친다. 이러한 문제점을 해결하기 위하여 근해에서 외해로 양식장이 이동하고 있다. 외해 양식장의 구축을 위해서는 자동먹이 공급장치 및 원격 관리 시스템이 필요하다. 본 논문은 해상의 양식장에서의 자동 먹이 공급 시스템에 관하여 설명하고자 한다. 어류는 수온 및 어체 중량에 따라 먹이를 먹는 양이 변화하며, 해상 양식장의 경우 육상에 비하여 온도 변화가 크게 일어난다. 본 논문은 수온 및 어체 중량에 따라 먹이량을 계산하고 자동으로 먹이를 공급하는 시스템을 연구하였으며 모형 실험을 통하여 먹이 공급 장치의 성능을 검증하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.244-249
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• 1993

This paper proposes a method of automatic function test for parts mounted Printed Circuit Board. For this purpose, we designed a Data Acquisition Equipment, PC interface card and inspection software. The experiment was done for the coffee vending machine and its result was good.

• Journal of Information Processing Systems
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• 제18권5호
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• pp.599-613
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• 2022

Non-proliferative diabetic retinopathy is a representative complication of diabetic patients and is known to be a major cause of impaired vision and blindness. There has been ongoing research on automatic detection of diabetic retinopathy, however, there is also a growing need for research on an automatic severity classification system. This study proposes an automatic detection system for pathological symptoms of diabetic retinopathy such as microaneurysms, retinal hemorrhage, and hard exudate by applying the Faster R-CNN technique. An automatic severity classification system was devised by training and testing a Random Forest classifier based on the data obtained through preprocessing of detected features. An experiment of classifying 228 test fundus images with the proposed classification system showed 97.8% accuracy.

• 한국정밀공학회지
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• 제13권3호
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• pp.49-55
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• 1996

Recently, the necessity for more accurate automatic gauge control has increased of customers' requirement for cold rolled steel sheets with thinner gauge and better gauge quality. Therefore, many cold rolling mills replaced its electric screw down automatic gauge control system with a new hydraulic automatic gauge control system, to ensure closer gauge tolerance. In this paper, The performance of a hydraulic automatic gauge control system for cold rolling has been investigated under industrial conditions. It was investigated that variation of gauge deviation according to the final products thickness, cold rolling speed and pass number, in the actual rolling mill. As a result, it was found that the system enables strip thickness variation to be reduced substantially and caused by poor gauge deviation have been drastically decreased. The test results are as following. The more the exit steel strip thickness is thick, the smaller the aguge deviation rate is large, and the more it is thin, the large the gauge deviation rate is large. Because the gauge deviation is larger at accleration speed and deceleration speed than steady speed, so automatic gauge control system is better to adopt over 50m/min. automatic gauge control system reduces rapidly large thickness deviation.