• Journal of Biosystems Engineering
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• 제21권1호
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• pp.34-43
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• 1996

The present pesticide application technology widely used with a power sprayer in Korea is assessed as the problem awaiting solution in the point of view of its ineffectiveness, inefficiency, and environmental contamination. As one approach to get rid of these problems, the boom spraying with ultra-low volume and precision application technology has been recommended. The study was undertaken to investigate plants damages incurred by the self-propelled boom-sprayer vehicle, to develop the design criteria of vehicle wheel, and to compare plant damages caused by the front wheel steering vehicle, the 4-wheel drive vehicle and the articulated vehicle, by the computer simulation. The experiment showed that the amount of damaged plants incurred by the self-propelled boom sprayer were about 0.29% in average in the field size of 100m$\times$50m(0.5ha), about 60~80% of which recovering while growing. The recommandable wheel size was analyzed to be 70~100cm in diameter, 8~15cm in width from the vehicle-plant-soil relationship. The simulation on damaged plants anticipated to be incurred by various steering vehicles showed that the smaller the turning radius, the lesser the damaged plants within its range of 3~5m. Average plant damage rate by the front wheel steering vehicle, the 4-wheel drive vehicle and articulated vehicle was relatively assessed to be 2 : 1.8 : 1.

• 한국건설순환자원학회논문집
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• 제8권3호
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• pp.372-378
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• 2020

본 연구에서는 콘크리트 하수관로의 결함부를 보수하기 위한 자주차의 개발 및 성능평가에 관한 연구를 수행하였다. 비굴착 방식인 자주차를 활용한 하수관로 보수를 위하여 구동 시스템, 보수 유닛 설계 및 보수재료 압송에 관한 성능을 고려하여 자주차를 개발하였다. 개발된 자주차의 성능평가를 하기 위하여 직경 500mm 콘크리트 하수관로에 결함부를 모사하여 보수실험을 수행하였다. 이후, 보수가 완료된 하수관로를 양쪽 끝단과 결함부에 플러그를 삽입하여 고정하고, 물을 주입하여 보수부위에서 누수 여부를 통한 수밀성능을 평가하였다. 누수량은 0.07L/㎡으로 허용 누수량 0.2L/㎡ 이하의 값을 나타내며 우수한 수밀성능을 나타내었다. 따라서 본 연구에서 개발한 자주차는 우수한 보수성능을 나타내는 것으로 판단된다.

• 한국기계기술학회지
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• 제20권6호
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• pp.836-843
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• 2018

In this paper, dynamic model of 120mm self-propelled mortar is developed, and multi flexible body dynamics analysis is performed to analyze stresses occurring in the mount during mortar fire. For this, vehicle dynamic system, mortar dynamic system, and finite element mount model are proposed. The commercial program Recurdyn is used in the analysis. As a result of the analysis, the maximum stress(146.9MPa) occurred at the mount side plate. In order to analyze the validity of the analysis results, we performed strain measurement tests by selecting three major points, and the errors of results were 7.91%, 11.15%, and 18.23%, respectively. It is confirmed that the tendency of analysis and test is similar.

• 한국해양공학회지
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• 제20권3호
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• pp.54-60
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• 2006

For optimal design of a deep-sea ocean mining collector system, based on self-propelled mining vehicle, it is imperative to develop and validate the dynamic model of a tracked vehicle traveling on soft deep seabed. The purpose of this paper is to evaluate the fidelity of the dynamic simulation model by means of response surface methodology. Various statistical techniques related to response surface methodology, such as outlier analysis, detection of interaction effect, analysis of variance, inference of the significance of design variables, and global sensitivity analysis, are examined. To obtain a plausible response surface model, maximum entropy sampling is adopted. From statistical analysis and prediction for dynamic responses of the tracked vehicle, conclusions will be drawn about the accuracy of the dynamic model and the performance of the response surface model.

• 농업과학연구
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• 제49권4호
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• pp.897-907
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• 2022

The purpose of this study is to develop a self-propelled underground crop harvester and its performance was evaluated by measuring the load during actual potato harvesting operations. This study was conducted at a constant working speed of 1 km·h^-1. A load measurement system was installed to measure the actual load and the required working power was analyzed. A hydraulic pressure sensor was also installed to measure the hydraulic pressure. The required hydraulic power was calculated using the hydraulic pressure and flow rate. The results showed that the engine speed, torque, and power during harvesting operation were in the range of 845 - 1,423 rpm, 95 - 228 Nm, and 9 - 31 kW, respectively. Traction power, excluding the hydraulic pump of the tractor and power take-off (PTO) output, was in the range of 9 - 28 kW, and it was confirmed that it occupies a ratio of 16.2 to 50% of the engine rated output. The engine can supply the minimum required traction power to move the vehicle. This means that the engine used in this study could be down-sized to be suitable for an underground crop harvester. In this study, the gear stages of the tractor were not considered. This research thus shows the possibility of developing a self-propelled underground crop harvester.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2006년 창립20주년기념 정기학술대회 및 국제워크샵
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• pp.311-314
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• 2006

This paper concerns about total dynamic analysis of integrated mining system. This system consists of vertical steel pipe, intermediate buffer station, flexible pipe and self-propelled miner. The self-propelled miner and buffer are assumed as rigid-body of 6-dof. Discrete models of vertical steel pipe and flexible pipe are adopted, which are obtained by means of lumped-parameter method. The motion of mining vessel is not considered. Instead, the motion of mining vessel is taken into account in form of various boundary conditions (e.g. forced excitation in slow motion and/or fast oscillation and so on). A terramechanics model of extremely soft cohesive soil is applied to the self-propelled miner. The hydrodynamic forces and moments are included in the dynamic models of vehicle and lifting pipe system. Hinged and fixed constraints are used to define the connections between sub-systems (vertical steel pipe, buffer, flexible pipe, miner). Equations of motion of the coupled model are derived with respect to the each local coordinates system. Four Euler parameters are used to express the orientations of the sub-systems. To solve the equations of motion of the total dynamic model, an incremental-iterative formulation is employed. Newmark-b method is used for time-domain integration. The total dynamic responses of integrated mining system are investigated.

• 대한조선학회논문집
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• 제57권5호
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• pp.287-296
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• 2020

The present study aims to improve the accuracy of the maneuvering simulations based on captive model test results. To derive the hydrodynamic coefficients in a self-propelled condition, a mathematical maneuvering model using a whole vehicle model was established. Captive model tests were carried out using the Vertical Planar Motion Mechanism (VPMM) equipment. A motor controller was used to control the constant propeller revolution rate during pure motion tests. The resistance tests, self-propulsion tests, static drift tests, and VPMM tests were performed in the towing tank of Seoul National University. When the vertical drift angle changes, the gravity load on the sensors were changed. The hydrodynamic forces were deduced by subtracting the gravity load from the measured forces. The hydrodynamic coefficients were calculated using the least-square method. The simulation of the turning circle test was compared with the free-running model test result, and the error of the turning radius was 8.3 % compared to the free-running model test.

• 품질경영학회지
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• 제47권3호
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• pp.453-465
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• 2019

Purpose: A main purpose is to increase the operational rate and reduce operating maintenance costs by Improving the durability of Blower of Military Armored Vehicle and Self-propelled Artillery. As a result, it is expected to improve the service quality of customers. Methods: After analyzing the cause of the stop of the blower, the improvement plans were established and the effectiveness of each improvement plans were verified by testing. Results: Mechanical, electrical and environmental factors affecting brush wear were reviewed, but it was difficult to specify the cause, which necessitated a review of the application of the BLDC motor. Conclusion: After applying the BLDC motor to the blower, tests proved that the existing blower can be replaced. It is expected that this study will help improve the durability life of similar equipment that is applied with Brushed DC motors as well as blowers.

• 비파괴검사학회지
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• 제35권5호
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• pp.358-366
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• 2015

본 논문에서는 자주포, 전차 및 장갑차 등 지상궤도전투장비에 적용되는 비파괴검사 방안 검토 및 설계방안에 대해서 연구하였다. 비파괴검사 방안 중에서 지상궤도전투장비 비파괴검사자의 기량검증 요건은 미군규격에서 최초로 언급 되었으며, 이후 국내 지상궤도전투장비 무기 개발시 국방규격에도 적용되었다. 그러나 민 군 규격통일화사업을 통해 방산용 비파괴검사자의 자격은 기존 항공분야에서 적용중이던 NAS410이 항공/방산 공용규격으로 통합화 되었다. 본 연구에 대한 설계방안의 검증은 자주포에 사용되는 Al 단조품에 대해 최적설계된 액체침투탐상검사 방법을 적용하여 제품의 신뢰성 및 건전성을 확인하였다.

• 한국군사과학기술학회지
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• 제24권1호
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• pp.84-98
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• 2021

The hydrodynamic characteristics of amphibious assault vehicles are investigated using commercial CFD code, STAR-CCM+. Resistance performances of a displacement-type vehicle and a semi-planing type vehicle are analyzed in calm water. The self-propelled model is also computed for the semi-planing type vehicle. All computations are performed using an overset mesh system and a RANS based flow-solver coupled with a two-degree of freedom equations of motion. A moving reference frame is applied to simulate revolutions of impeller blades for a waterjet propulsion system. Grid dependency tests are performed to evaluate discretization errors for the mesh systems. The numerical analysis results are compared with the experimental results obtained from model tests. It is shown that RANS is capable of investigating the resistance and self-propulsion characteristics of high-speed amphibious assault vehicles. It is also found that a fully covered side skirt, which is covering tracks, reduces resistance and stern trim, besides increasing propulsive efficiency.