• Journal of Biosystems Engineering
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• 제34권6호
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• pp.404-410
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• 2009

This study was carried out to develop a self-propelled type explosive subsoiler for improving the root zone soil conditions in orchard and other forest fields. Prototype was designed to be able to inject air and other soil improving material such as lime into soil at the same time, and thus improve the air permeability and drainage of orchard soils to promote the root growth of tree for high quality fruit production. Soil penetration device of explosive subsoiler is composed of air hammer, penetration rob and air injection nozzle. To support the soil penetration device of explosive subsoiler to penetrate vertically, modified Scott-Russel mechanism was used. Timing control device for simultaneous injection of soil improving material with air was attached to the out side wall of air cylinder and as the cylinder move, the soil improving material was injected into soil at the same time. Turning radius of prototype was 2.2-2.3 m with good mobility in sloped land. It took approximately 1 minute for lime injection system to reach the optimum pressure of 9.9 kg/$cm^2$, average 10-20 seconds were required to rupture soil with the depth of 50 cm and 2-3 seconds were required for explosion, so all in all about 1 minute and 20 seconds were required for one cycle of explosion. Maximum soil rupture depth and diameter were 50 cm and 3-4 m respectively depending on the soil type and soil moisture content. For final design of explosive subsoiler inclination angle of lime hopper was increased from 60 degree to 70 degree and the shape of hopper was changed from rectangular cone to circular cone to solve the clogging problem of lime at out let. Agitating system operated by compressed air was attached to the metering device of the prototype, thus more than 90 cc of lime was discharged per cycle from metering device without clogging problems.

• 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.

• 한국산학기술학회논문지
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• 제19권9호
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• pp.62-68
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• 2018

본 연구는 군 포병 전력의 핵심 장비인 자주포의 급속장전장치에 장착된 밀대 시스템 개선을 통해 탄의 장전 안정성향상을 목표로 하는 것이다. 종래의 자주포에는 수동 장전장치가 적용되어 있었다. 군에서 운용하는 장비의 현대화와 연속사격 속도 향상을 위해 급속 장전장치를 설치하였으며, 이러한 급속 장전장치를 통해 탄이 장전되는 과정에서 약실 내부와 간섭되는 현상을 줄이고, 비행시간을 감소하도록 설계되었다. 그러나 기본적으로 밀대를 통해 탄의 급속장전이 이루어지는 슈팅 방식의 장전시스템에서는 탄 흐름(fall-back) 현상이 간헐적으로 발생할 수 있다고 보고되고 있다. 그래서 이러한 문제를 해결하기 위해서 장전 과정의 실제 조건을 반영한 전산모사(C.A.E.)를 통해 탄이 장전되는 과정에서 비행 거리를 감소시키면 탄 흐름 현상을 방지할 수 있는 것을 이론적으로 확인 하였고, 탄의 비행거리를 줄이는 최적의 설계 방안을 도출하였다. 최종적으로 이러한 결과를 바탕으로 야전에 배치된 자주포에 장착하여 시험한 결과 개선효과가 있음을 확인하였다.

• 드라이브 ㆍ 컨트롤
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• 제21권2호
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• pp.23-29
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• 2024

Potatoes are one of the world's four major crops, and domestic consumption is currently increasing in Korea. However, the mechanization rate of potatoes is very low, and especially, harvesting is the most labor-intensive task in potato production. In Korea, potato-collecting work depends on manpower, so it is necessary to develop a gathering-type harvester that can be used for processes from digging to harvesting. Therefore, in this study, a self-propelled-type potato harvester was developed, and its performance was analyzed to mechanize harvesting. The potato harvester was developed to have a crawler-type driving part with a 60 hp diesel engine and consisted of a digging part that digs potatoes from the ground, a vertical transporting part that transfers the dug potatoes to the height of the collection bag, a separating part that separates debris, such as stones and soil, and a collecting part that loads the collection box. A field test of the potato harvester was conducted, and performance was evaluated by the damage, loss, and debris mixing proportions, which were 2.5%, 2.8%, and 2.6%, respectively. The working capacity was 1.2 h/10 a. The economic analysis results showed that the cost of harvesting work could be reduced by 12.7% compared to manual harvesting.

• Journal of Advanced Marine Engineering and Technology
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• 제21권5호
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• pp.474-481
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• 1997

Waterjet propulsion generally refers to propulsion of ships by internally mounted pumps with proper ducting. This arrangement of the actuator component of the system leads to the fundamental differences with respects to screw propeller system. In this paper, the basic hydrodynamic characteristics of waterjet propulsion was outlined to clarify the application consideration and proposal for carrying out model self-propulsion tests with waterjet propelled models was presented. The results of model self-propulsion tests carried out in the Hyundai Maritime Research Institute towing tank with catamaran ship were presented.

• 한국방재학회 논문집
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• 제8권4호
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• pp.87-90
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• 2008

이 연구는 사찰의 화재 사례, 일본의 사찰 안전관리에 대하여 고찰 분석하였다. 그 결과를 토대로 사찰 화재예방시스템에 대한 개선방안 제안을 목적으로 하고 있다. 사찰 화재예방시스템의 개선방안으로는 첫째, 화재로 문화재 소실 등의 피해를 줄일 수 있도록 "문화재보호법"에 화재예방을 위한 규정 신설의 필요성 제기 둘째, 단독경보형 감지기 및 에어졸식 간이소화용구를 설치하여 화재의 조기발견 및 진화 그리고 인명피해를 최소화 방안 강구 셋째, 경미한 전기설비 설치공사에 있어서도 "국가기술자격법"에 의한 전기분야의 기술자격을 취득한 자가 시공할 수 있도록 "전기사업법령"상의 기준 마련 등이다.

• Ocean and Polar Research
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• 제32권4호
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• pp.463-473
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• 2010

Inshore tests were performed in order to verify the design concept of deep sea manganese nodule miner at a site near Hupo at East Sea of Korea in June of 2009. Total mining tests of the test miner, named 'Minero$^{(R)}$', together with flexible hose, lifting pump and lifting hose were accomplished. In this study, the performances of three subsystems of testminer (vehicle, pick-up device, and launch-and-recovery device) were analyzed for feasibility assessment of self-propelled remotely controlled miner, and also to compile basic data for designing a pilotminer. Performances of the test miner were defined based on the Functional Requirements of Axiomatic Design. The inshore tests revealed that the test miner generally satisfies the functional performances. Feasibility assessment and reflection on results are discussed within.

• Journal of Biosystems Engineering
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• 제22권2호
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• pp.137-150
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• 1997

To investigate the feasibility of a boom sprayer in the paddy field, an experimental boom sprayer for both broadcast and directed spraying to the lower part of rice plants was developed. The droplet deposition characteristics of the boom sprayers were experimentally compared to those of power sprayer. Water sensitive papers(WSP) and a machine vision system were used to evaluate the coverage rate and droplet density. It was shown that the broadcast application by the boom sprayer was the best coverage among the tested sprayers. Coverage tate and droplet density were affected by the distance between nozzles and the sprayer ground speed, The best result was obtained when the distance of 30cm and the speed of 1.7km/hr. The directed application showed inconsistency in overall droplet distribution. The inconsistency was judged to be caused by conflict between plants and boom extenders. The power sprayer showed a very wide range of droplet size distribution, relatively larger droplets and inconsistency in cove The power sprayer was judged to be inadequate for the low-volume precision application because of inconsistency in performance and difficulty in adjusting the spraying rate. Based on the droplet coverage characteristics, it was concluded that the self-propelled boom sprayer for the broadcast application was feasible for an alternative to the power sprayer in case of low volume, precision application in paddy condition.

• 대한기계학회논문집A
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• 제20권12호
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• pp.3767-3781
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• 1996

Generally, dynamic loads are applied to real structures. Since the analysis with the dynamic load is extremely difficult, static loads are utilized by proper conversions of the dynamic loads. The dynamic loads are usually converted ot static loads by safety foactors of experiences. However, it may increase weight and decrease reliability. In this study, a method is proposed for the conversion process. An equivalent static load is calculated ot generate a same maximum displacement. The method is verified through numerical tests on a spring-mass systems of one and multi degrees-of freedom. It has been found that the duration time of the loads and the natural frequencies of the structures are critical in the conversion process. A road arem is a self-propelled howizer is selected for the application of the proposed method. The shape of the road arm is optimized under the converted static loads.

• 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.