• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.5
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• pp.502-515
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• 2020

To identify the dynamic characteristics of the Auto-leveling system applied to the Tractor-Trailer type Transporter for mounting a large scale precision equipment, Dynamics Modeling & Simulation were performed using general Dynamics Analysis Program - RecurDyn(V9R2). The axial load data, transverse load data and pad trace data of leveling actuators were obtained from M&S. And they were analyzed and compared with each other by parameters, i.e. friction coefficients on the ground, landing ram speed of actuators, and direction & quantity of ground slope. It was observed that ground contact friction coefficients affected to transverse load and pad trace; the landing ram speed of actuators to both amplitude of axial & transverse load, and this phenomena was able to explain from the frequency analysis of the axial load data; the direction of ground slope to driving sequence of landing ram of actuators. But the dynamic behaviors on the two-directional slope were very different from them on the one-directional slope and more complex.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.6
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• pp.659-665
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• 2010

This paper proposes a control algorithm for quadruped robots moving on irregularly sloped uneven surfaces. Since the body balance of a quadruped robot is controlled by the forces acting on its feet during touchdown, the ground reaction force (GRF) is controlled for stable running. The desired GRF for each foot is generated on the basis of the desired galloping pattern; this GRF is then compared with the actual contact force. The difference between the two forces is used to modify the foot trajectory. The desired force is realized by considering a combination of the rate change of the angular and linear momenta at flight. Then, the amplitude of the GRF to be applied at each foot in order to achieve the desired linear and angular momenta is determined by fuzzy logic. Dynamic simulations of galloping motion were performed using RecurDyn; these simulations show that the proposed control method can be used to achieve stable galloping for a quadruped robot on irregularly sloped uneven surfaces.

• Journal of Biosystems Engineering
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• v.40 no.1
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• pp.35-46
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• 2015

Purpose: To present a flexible and accurate autonomous solution for creating any desired row spacing value between the hydroponic gullies in multilayer growing units, and evaluate the capabilities and performance of the relevant automated system through the use of virtual prototyping technique. Methods: To build the virtual prototype of the system, CAD models of its different parts, including an autonomous vehicle and the mechanical mechanisms embedded in the multilayer growing unit, were developed and imported into the RecurDyn simulation software. In order to implement the automated row spacing operation, three spacing modes with different loading cycles and working steps were defined, and the operation of the system was simulated to obtain the target row spacing values specified for each of these modes. Results: Motion profiles related to the horizontal displacement of: 1) the lower and upper sliding bars installed in the cultivation layers, and 2) the hydroponic gullies, during the simulation of the system operation, were generated and analyzed. No deviation from the specified target spacing values was observed at the end of simulations for all spacing modes. Conclusions: The results of the motion analysis obtained by simulating the system operation confirm the effectiveness of the control scheme proposed for automated row spacing of gullies. It was also found that proper sequencing of the loading cycles and the precision of the working strokes of the upper bars are the critical factors for establishing a certain row spacing value. Based on the simulation results, precise control of the back and forth motions of the upper bars is highly necessary for sound operation of the real system.

• Journal of Biosystems Engineering
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• v.30 no.2 s.109
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• pp.81-88
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• 2005

Manual transplanting Chinese cabbage needs 184 hours per ha in Korea. Mechanization of Chinese cabbage transplanting operation has been highly required because it needs highly intensive labor during peak season. This study was conducted to developed walking-type Chinese cabbage transplanter. In order to find out design factor of the transplanter, a kinematic analysis software, RecurDyn, was used. The prototype was tested in the circular soil bin and its operating motion was captured and analyzed using high speed camera system. Prototype was one row type which utilized original parts of engine, transmission and etc. from walking-type rice transplanter in order to save the manufacturing cost. Success ratio of pick-up device of hole-pin type and latch type were $96.0\%$ and $99.2\%$, respectively. which was highly affected by feeding accuracy of feeding device of seedling. Transplanting device of the prototype produced a elliptic loci which were coincident with those produced by the computer simulation. Prototype proved good performance in transplanting with mulching and without mulching operation, either. Working performance of prototype was 22 hours per ha and operation cost of the prototype was 961,757 won per ha. So, it would reduce $88\%$ of the labor and $29\%$ of operation cost.

• Journal of Biosystems Engineering
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• v.30 no.6 s.113
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• pp.366-372
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• 2005

The objective of this study was to evaluate the bump crossing and loading stability of a proto-type mini-forwarder under development. The evaluation was performed by computer simulation using a multi-body dynamic analysis program, Recur- Dyn 5.21. The proto-type was modeled and its properties such as mass, mass center, and mass moment of inertia were determined using 3D CAD modeler, Solid Edge 8.0. The $\%$ errors of masses, mass center, mass moment of inertia, and vertical motion of the model were within less than $10\%$ and the model's behavior agreed relatively well with those of the proto-type when traversing over a rectangular bump. Using the validated model, bump crossing of the proto-type was simulated and the loading limit was determined. It was found that effects of the shapes of bump on the bump crossing performance was insignificant within the practical heights of bumps. Stability of bump crossing increased with loading. However, loading of longer logs than 2.7 m made the crossing unstable because the ends of logs contacted ground when traversing over the bump. The maximum loading capacity of the proto-type was estimated to be 7.8 kN of 2.7 m long logs.

• Journal of Biosystems Engineering
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• v.42 no.4
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• pp.235-241
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• 2017

Purpose: It is to develop an agricultural three-directional dumping vehicle that can help farmers reduce intensive labor when carrying heavy loads and for easy dumping. In addition, a novel mechanism was applied for controlling the direction of the tilting cargo box by using a single hydraulic cylinder and simple apparatus. The overturning safety was analyzed to provide safe-use ground slope region of the vehicle to be used at upland fields and orchards. Methods: The developed three-directional dumping vehicle was constructed using a cargo box, vehicle frame, driving components, lifting components, and controller. The novel mechanism of controlling the dumping direction involves the operation of two latching bars, which selectively release or collapse the connecting edge between the vehicle frame and cargo box. A multibody dynamics analysis software (RecurDynV8R5) was used to determine the safe-use ground slope area when tilting the cargo box at slopes. A computer analysis was conducted by increasing the ground slope while rotating the vehicle when the cargo box comprised loads of 300 and 500 kg and stacking heights of 40 and 80 cm, respectively. Results: The three-directional dumping vehicle was successfully manufactured, and the cargo box was tilted at $37^{\circ}$ and $35^{\circ}$ for dumping forward and sideways. The latching bars were manually and selectively collapsed with the vehicle frame to control the dumping direction. When forward dumping, the safe-use ground slope was over $20^{\circ}$ in all vehicle directions and loaded conditions. Conclusions: A three-directional dumping vehicle was developed to reduce labor-intensive work in the farming environment. The user can easily control the dumping direction by using the control panel. The vehicle was safe to be used in most of the Korean upland fields and orchards (area over 96%) for the forward dumping.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.2
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• pp.211-222
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• 2011

In this paper a structural analysis of the PWR(pressurized water reactor) canister with 102cm diameter is carried out to evaluate the structural safety of the canister for the impact force occurring at the moment of collision with the ground in the falling plumb down accident from the carriage vehicle which may happen during the canister handling at the spent nuclear fuel disposal repository. For this, a rigid body dynamic analysis of the canister is executed to compute the impact force using the commercial CAE system, RecurDyn, and a nonlinear structural analysis is performed to compute stresses and deformations occurring inside the canister for this computed impact force using the commercial FEM code, NISA. From these analysis results, the structural safety of the canister is evaluated for the falling plumb down accident from the carriage vehicle due to the inattention during the canister handling at the repository. The rigid body dynamic analysis performed assuming the canister as a rigid body shows that the canister falls plumb down to the ground in two types. And also it shows that early collision impact force is the biggest one and following impact forces decrease gradually. The height of the carriage vehicle in the repository is assumed as 5m in order to obtain the stable structural safety evaluation result. The nonlinear structural analysis of the canister is executed for the biggest early impact force. The structural analysis result of the canister shows that the structural safety of the PWR canister is not secured for the falling plumb down accident from the moving carriage vehicle because the maximum stresses occurring in the cast iron insert of canister are bigger than the yield stress of the cast iron.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.86-86
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• 2017

마늘파종기는 파종기구동부와 파종후 파종홀의 복토역할을 하는 파종기롤러, 지면과의 마찰을 통해 바퀴의 회전토크가 발생하며 발생된 토크는 파종기 내부 동력으로 전달되어 전체 파종시스템(배종, 호퍼캠, 파종부)을 동작 시키는 기능을 수행하는 파종바퀴, 마늘종구를 한알씩 집어올려 중간이송컵으로 이송하는 자세교정컵이 포함된 배종부와 자세교정컵에서 낙하된 마늘종구를 땅속으로 파종하는 파종장치로 구성된다. 배종율 95%, 2립 배종률 5% 성능을 확보할 수 있는 기술이 개발될 경우 세계적으로도 독보적인 기술 우위를 확보할 수 있다. 이와 같은 기본적인 기능을 구현할 수 있는 컨셉모델에 대한 설계를 수행하여 시제품개발 전 기구해석과 구조해석 등을 위한 기본설계를 수행하였다. 배종율 95% 이상을 확보하기 위해서는 기존의 현장경험의 의한 설계 방식으로는 한계가 있기 때문에 시뮬레이션 및 분석 개발이 필요한데, 프레임은 고정밀 마늘종구 배종부 장착을 위한 기본 구조물로써 작동시 동력을 얻기 위한 바퀴와 연계가 되도록 설계되었으며, 호퍼는 배종 수행을 위해 마늘을 저장해 두는 통으로써 배종부와 연결된다. 배종부의 배종판이 회전함에 따라서 배종판의 홈이 호퍼 내로 들어갔다 나오면서 마늘을 집게되며, 동력 전달부는 배종판을 회전시켜주고, 회전 속도 조절을 가능하게 한다. 파종부는 배종부에서 중간컵을 통해 하나씩 공급해준 마늘을 땅에 심는 부분으로서. 프레임의 바퀴 회전과 연동되어 회전하고 설계하였다. 배종판에서 중간컵으로 이송된 마늘을 파종부의 파종컵에 받아 회전하면서 땅속에 파종컵이 묻히면 파종컵이 열리면서 땅속에 마늘을 심는 원리이다. 조간조정은 7조식의 경우 초기설치시 고정되도록 설계되었으며 농촌진흥청 기계화 표준재배안에 따라 의성마늘 기준 $14{\times}14cm$(조간${\times}$주간)를 기준으로 개발하였다. 조간조정은 기계가 설치되면 조정하기 어려우므로 14cm로 설계하였으며, 주간조정은 원형배종장치의 구동기어부의 속도비로 간격을 조정할 수 있도록 기어장치를 설계하였다. 주간조정은 13에서 18cm의 범위에서 작동하도록 설계되었으며, 필요에 따라 간격조절이 가능함. 마늘은 그 크기가 다르고, 형상도 다르기 때문에 종자에 따른 개별적인 파종기술들이 개발되어야하기 때문에 개발 기간이 오래 걸리고, 수익에 비하여 개발비가 과다하게 요구되는 실정인데 축적된 시뮬레이션 툴을 이용한 파종기 분석 기술을 확보할 경우 다른 파종기의 연구 개발에도 크게 도움이 될 것으로 기대되며, 생육측정 실험과 동역학 해석 툴 RecurDyn을 통해 파종기의 기구학적 분석을 통한 설계반영 인자를 도출할 계획이다.