• Current Research on Agriculture and Life Sciences
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• v.32 no.3
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• pp.159-163
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• 2014

Agricultural unmanned helicopters have become a new paradigm for aerial application. Yet, such agricultural helicopters require easy and affordable attitude control systems. Therefore, this study presents an affordable attitude measurement system using a DCM (direction cosine matrix) algorithm that would be applied to agricultural unmanned helicopters. An IMU using a low-cost MEMS and an algorithm to estimate the attitude of the helicopter were applied in a gimbals structure to evaluate the accuracy of the attitude measurements. The estimation errors in the attitude were determined in comparison with the true angles determined by absolute position encoders. The DCM algorithm and sensors showed an accuracy of about 1.1% for the roll and pitch angle estimation. However, the accuracy of the yaw angle estimation at 3.7% was relatively larger. Such errors may be due to the magnetic field of the stepping motor and encoder system. Notwithstanding, since the intrinsic behavior of the agricultural helicopter remains steady, the determination of attitude would be reliable and practical.

• International Journal of Aeronautical and Space Sciences
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• v.10 no.2
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• pp.1-11
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• 2009

In this paper, two algorithms to solve the path planning problem with constraints from obstacles are presented. One proposed Algorithm is "Grid point-based path planning". The first step of this algorithm is to set points which can be the waypoints around the field. These points can be located inside or outside of the field or the obstacles. Therefore, we should determine whether those points are located in the field or not. Using the equations of boundary lines for a region that we are interested in is an effective approach to handle. The other algorithm is based on the boundary lines of the agricultural field, and the concept of this algorithm is well known as "boustrophedon method". These proposed algorithms are simple but powerful for complex cases since it can generate a plausible path for the complex shape which cannot be represented by using geometrical approaches efficiently and for the case that some obstacles or forbidden regions are located on the field by using a skill of discriminants about set points. As will be presented, this proposed algorithm could exhibit a reasonable accuracy to perform an agricultural mission.

• Current Research on Agriculture and Life Sciences
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• v.32 no.2
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• pp.79-84
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• 2014

The precision aerial application of agricultural unmanned helicopters has become a new paradigm for small farms with orchards, paddy, and upland fields. The needs of agricultural applications require easy and affordable control systems. Recent developments of MEMS technology based on inertial sensors and high speed DSP have enabled the fabrication of low-cost attitude system. Therefore, this study evaluates inertial MEMS sensors for estimating the attitude of an agricultural unmanned helicopter. The accuracies and errors of gyro and acceleration sensors were verified using a pendulum system. The true motion values were calculated using a theoretical estimation and absolute encoder measurement of the pendulum, and then the sensor output was compared with reference values. When comparing the sensor measurements and true values, the errors were determined to be 4.32~5.72%, 3.53~6.74%, and 3.91~4.16% for the gyro rate and x-, z- accelerations, respectively. Thus, the measurement results confirmed that the inertial sensors are effective for establishing an attitude and heading reference system (AHRES). The sensors would be constructed in gimbals for the estimating and proving attitude measurements in the following paper.

• Journal of Biosystems Engineering
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• v.33 no.1
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• pp.14-20
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• 2008

An agricultural unmanned helicopter was suggested for an alternative to current pesticide application methods to solve such problems as high cost, low efficiency, shirking task and unsafe work. To pursuit this trend, researches on the development of unmanned helicopters have been accelerated in Korea as well. In this research, a guide type centrifugal clutch that plays an important role in the unmanned helicopter was studied. Theoretical analyses and experimental tests were conducted for designing an optimal clutches. Main design factors of the guide type centrifugal clutch were found to be spring constant, free length of spring, mass of friction sector, contact area, allowable pressure, number of friction sector, friction coefficient, radius of drum, and clutch arrangement. And these design factors could be the functions of engaging engine speed and desired power transfer capacity. The result of the single clutch test showed the power transfer capacity of 14.1 PS at 5,800 rpm and the result of the dual clutch test showed that the capacity of 17.7 PS at 5,600 rpm. These experimental results agreed well the theoretical simulations.

• Current Research on Agriculture and Life Sciences
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• v.31 no.2
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• pp.131-138
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• 2013

The precision aerial application of small farms, such as paddy, upland and orchard fields using agricultural unmanned helicopters became a new paradigm. The objective of this study was to evaluate the performance of a GPS module and algorithm, controlling drift of agricultural helicopter by the crosswind and maintaining the position for emergency landing. Purpose of the drift control, of which an algorithm works while hovering is related with the emergency sequence that coping with abnormal conditions of rotorcraft system. However, the inertial attitude control cannot detect a drifting motion of fuselage moving at the constant velocity, thus the crosswind takes the helicopter away from the landing position. Performance of the drift control module, based on the GPS that a hovering position did not deviate within 5m in diameter, were tested and evaluated. Initially, the reaction against a disturbing gust wind was sensitive, soon the helicopter maintained its locking position and azimuth within 5m in diameter. It was, however, difficult for the helicopter to recognize the swaying and nodding, the some deviation was expected due to the discrepancy characteristics of the GPS signal. The performance of the drift control proved the effectiveness of the module to maintain the position against an unintended drift during the emergency landing or hovering.

• Journal of agricultural medicine and community health
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• v.27 no.1
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• pp.115-123
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• 2002

Objective: The aim of this study was to evaluate the patterns of helicopter emergency medical services (HEMS) in Ullung Island. Methods : The authors reviewed the records from emergency room diaries and the lists of helicopter transfers in the Ullung Public Health Medical Center over the 5-year period from Jan 1, 1997 to Dec 31, 2001. Results : One hundred thirteen cases were transferred by helicopters in 88 flights. According to year, the number of flights was 13(14.8%) and the number of cases was 15(13.3%) in 1997; 17(19.3%) and 21(18.6%) in 1998; 18(20.5%) and 20(17.7%) in 1999; 17(19.3%) and 20(17.7%) in 2000; and 23(26.1%) and 37(32.7%) in 2001. According to the kind of helicopter, the number of flights was 46(52.3%) and the number of cases was 60(53.1%) by Maritime police; and 19(21.6%) and 28(25.1%) by 119 rescue. According to time zone, there were no night flights. According to sex and age, there were 75 male cases(66.4%) and 28 cases(28.3%) of patients aged sixty years and over. The number of flights was 11(12.5%) and the number of cases was 15(13.3%) in November; 10 flights(11.4%) and 14 cases(12.4%) in March; and 7 cases(8.0%) in each of September, October and April. The most common season of helicopter transfer cases was autumn. According to transfer area, there were 48 cases (42.5%) in Pohang city, Gyeonsangbukdo; 35(31.0%) in Gangnung city, Gangwondo; and 17(15.0%) in Daegu metropolitan city. According to condition, there were 27 cases(23.9%) of cerebro-vascular accident, 13(11.5%) of fracture and 11(9.7%) of head injury. According to admission department, there were 42 cases(37.2%) in Neurosurgery, 21(18.6%) in Internal Medicine and 13(11.5%) in Orthopedic Surgery. According tothe Korea Standard Classification of Disease(3-KSCD), circulatory systemic disease(IX) and injury, intoxication and others (XIX) were the two most frequent categories with 34 cases(30.1%) each, followed by digestive system disease (XI) with 23 cases(20.4%). Conclusions : HEMS in Ullung Island leave much to be desired. Helicopters cannot make a night flight and are not equipped with medical facilities. HEMS in islands such as Ullung Island are essential. We hope that night flights, equipment-monitoring systems for emergency patients in the helicopters, and a law related to HEMS in the island will all be established.

• Journal of agricultural medicine and community health
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• v.30 no.3
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• pp.255-262
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• 2005

Purpose: In Ulleung island, emergency medical transport by helicopter is very important. So, we analysized our experience with emergency medical transport by helicopter for 4 years and we were compared our data with other data for 1997-2001. Therefore we need to research public health development direction. Method: We analysized patient's medical record for 4 years. Result: During 4 years, 104 transports were done and 130 patients were trasported to tertiary hospital center, there was more increased than that from 1997 to 2001. Helicopters from Pohang coast guard, Donghae coast guard, Navy, and 119 rescue etc. were used, but 119 rescue transport was decreased more and more. The 60's patients was most, 22.3% and teenager's and 80's patients was lowest. The male was 65% but the female was increased more and more annually. In addition, the older patients was the more portion of female patient. The transport was concentrated in daytime. The traumatic patient was much in winter period. The cerebrovascular accident was 1st cause of patient and fracture was many also. Conclusioon: Except Fire service's helicopter, the other helicopter was not apt to emergency medical tansport. But Fire service's helicopter was not used commonly because Fire service's helicopter was in Daegu, so distant and time consumed. As a result, emergency medical transport helicopter is needed in east coast like Fire service's helicopter. In addition, trauma prevention education and public health education for hypertension and diabetes will be essential and public health system in Ulleung island will be prepared for aging society.