• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.481-486
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• 2002

Automation of Field Robot has many advantages for efficiency and convenience. In this paper, mathematical equation of field robot is established and automation system is constructed. Hydraulic and Dynamic equation of field robot are constructed in this paper. Inputs of system are angle data from each link (boom, arm, bucket, swing) and pressure data from in, out port of each cylinder. Outputs of system are voltage into electo-proportional valve.

• Journal of Biosystems Engineering
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• v.28 no.5
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• pp.403-410
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• 2003

To enhance the performance of a rice seed pelleting machine and the quality of rice-seed pellets made, improvement of the rice seed pelleting machine developed previously(Park, 2002) was tried and its performance was evaluated. As compared with the previous pelleting machine, a feeding mechanism of pellet materials to the forming rolls was changed from screw conveyor to hydraulic cylinder for proper feeding, rings were installed among rows of semi-spherical forming grooves on the forming rolls for reducing pellet materials loss and seeds damage, and discharging air nozzles were added for complete discharging of the pellets made. Through performance tests, capacity, pelleting ratio, and seed loss ratio of the pelleting machine were investigated at the mixing ratios of soil to rice seed of 6 : 1, 7 : 1, and 8 : 1, and rotating speeds of the forming rolls of 7 rpm, 10 rpm, and 13 rpm. As results of performance evaluation, pelleting ratios were in the range of 77 ∼ 89 ％, and maximum pelleting ratio increased by 18 % in comparison with that of the previous machine. Maximum capacity was about 110 kg/h(about 63,000 pellets/h), which was increased by 70 % in comparison with that of the previous machine. But, ratios of seed loss were in the range of 24 - 49 ％, which were not improved.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.423-427
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• 2003

In this paper, it is to development of brake system with ABS function for aircraft. The test of brake system is required before applying on aircraft. The real-time dynamic simulator with 5-D.O.F. aircraft dynamic model is developed for braking performance test of ABS (Anti-skid Brake System) control h/w with anti-skid brake functions. The dynamic simulator is real-time interface system that is composed of dynamic simulation parts, master control parts, digital and analog in/out interface parts, and user interface parts. The 5-D.O.F. aircraft dynamic model is composed of a big contour and a little contour by simulation s/w. The big contour represents the interactions of forces in airframe, nose and main landing gear, and engines on the center of gravity. The little contour represents interactions of wheel, braking units, hydraulic units and a control unit. ABS control h/w unit with ABS control algorithm is also developed and is tested with simulator under the some conditions of gripping coefficient. We have known that ABS control h/w unit on wet or snowy runway as well as dry runway very well protects wheel skid.

• Nuclear Engineering and Technology
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• v.55 no.11
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• pp.4102-4111
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• 2023

In order to better perform thermal hydraulic calculation and analysis of supercritical water reactor, based on the experimental data of supercritical water, the model training and predictive analysis of the heat transfer coefficient of supercritical water were carried out by using the support vector machine (SVM) algorithm. The changes in the prediction accuracy of the supercritical water heat transfer coefficient are analyzed by the changes of the regularization penalty parameter C, the slack variable epsilon and the Gaussian kernel function parameter gamma. The predicted value of the SVM model obtained after parameter optimization and the actual experimental test data are analyzed for data verification. The research results show that: the normalization of the data has a great influence on the prediction results. The slack variable has a relatively small influence on the accuracy change range of the predicted heat transfer coefficient. The change of gamma has the greatest impact on the accuracy of the heat transfer coefficient. Compared with the calculation results of traditional empirical formula methods, the trained algorithm model using SVM has smaller average error and standard deviations. Using the SVM trained algorithm model, the heat transfer coefficient of supercritical water can be effectively predicted and analyzed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.2
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• pp.106-113
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• 1987

The Alaska pollack longline operations, which consist of baiting, shooting, hauling and arrangement of hooks, are dependant on manual labour up to the present. The automation against this traditional way is necessary to eliminate the manual operations and to reduce crew. We have developed a prototype longline system suitable for Alaska pollack longline gear, which is composed of an automatic baiting machine, an automatic line hauler, a hook cleaner and storage rails. The automatic bailing machine driven by hydraulic power is precise baiting method controlled sequentially, and the automatic line hauler is to haul up the mainline by means of hydraulic power and at the same time to split every hook and to carry it onto storage rail automatically. A series functioning tests on shooting and hauling apparatus were carried out in the laboratory and at sea. The results obtained are as follows ; 1. As for the baiting machine, the exciting time of solenoid which operates a directional valve, bait feeding and cutting time, is shortened according to the increase of pressure, and also, after cutting the bait, the over-rotated angle of the blade increased in accordance with the increase of pressure. 2. The baiting efficiency is about $90\%$ when using sand lance (Hypoptychus dybowskii), and the most proper pressure of the hydraulic circuit in feeding and cutting the bait is between $13\;kgf/cm^2\;and\;20\;kgf/cm^2$. 3. The hook splitting rate of the automatic line hauler is about $95.5\%$ regardless of hauling speed and materials of snood. 4. The case of unseparating hook is appeared when the snood gets entangled or the hook is sticked in the mainline.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.36 no.2
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• pp.37-49
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• 2024

To date, numerous empirical formulas have been proposed through hydraulic model experiments to predict the wave breaker index, including wave height and depth of wave breaking, due to the inherent complexity of generation mechanisms. Unfortunately, research on the characteristics of wave breaking and the prediction of the wave breaker index for gravel beaches has been limited. This study aims to forecast the wave breaker index for gravel beaches using representative linear-based machine learning techniques known for their high predictive performance in regression or classification problems across various research fields. Initially, the applicability of existing empirical formulas for wave breaker indices to gravel seabeds was assessed. Various linear-based machine learning algorithms were then employed to build prediction models, aiming to overcome the limitations of existing empirical formulas in predicting wave breaker indices for gravel seabeds. Among the developed machine learning models, a new calculation formula for easily computable wave breaker indices based on the model was proposed, demonstrating high predictive performance for wave height and depth of wave breaking on gravel beaches. The study validated the predictive capabilities of the proposed wave breaker indices through hydraulic model experiments and compared them with existing empirical formulas. Despite its simplicity as a polynomial, the newly proposed empirical formula for wave breaking indices in this study exhibited exceptional predictive performance for gravel beaches.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.475-480
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• 2002

The Field Robot means the machinery applied for outdoor tasks in construction, agriculture and undersea etc. In this study, to field-robotize a hydraulic excavator that is mostly used in construction working, we developed an interfacing hardware part of stroke sensing cylinder using magnetic sensor and estimated its performance. It is illustrated by experiment that the proposed control system by stroke sensing cylinder gives good performances in the position control

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.383-387
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• 2001

A mechanism of hovering flight of small insects which is called the Weis-Fogh mechanism is applied to ship propulsion. A model of the propulsion mechanism is based on a two-dimensional model of the Weis-Fogh mechanism and consists of one or two wings in a square channel. A model ship equipped with this propulsion mechanism was made, and working tests were performed in a sea. The model ship sailed very smoothly and the moving speed of the wing was small compared with the advancing speed of the ship.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2741-2743
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• 2000

내구시험기의 기본적인 구조를 해석하고 분석하여 각종 기구부의 내구성 시험에서 적용대상물에 관계없이 전기유압서보장치의 용량과 적합한 센서들을 조합하여 구성 가능하도록 시험기를 구성하였으며, 본 연구에서 개발된 제어장치와 데이터 수집 소프트웨어는 내구시험 대상물에 관계없이 범용 적으로 사용할 수 있도록 개발하였다.

• Journal of Mechanical Science and Technology
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• v.15 no.11
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• pp.1548-1554
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• 2001

Flow patterns and dynamic properties of two-stage Weis-Fogh type ship propulsion mechanism are studied by a discrete vortex method. To study mutual interference between two wings, two cases are con sidered - wing motions with the same and reverse phases. The predicted flow patterns correspond to the available flow visualization results. Time histories of thrust and drag coefficients are also calculated, and the interference between the two wings are numerically clarified.