• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2008년도 정기학술발표대회 논문집
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• pp.628-633
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• 2008

건축물에 있어서 고층화 대형화의 변화는 인력과 자재의 양중부하를 증가시키는 동시에 수직양중작업의 이동거리를 증가시킨다. 이로 인해 고층으로의 운반정체는 물론 대기상태증가로 인한 생산성 감소의 문제를 발생시킨다. 이에 고층 건물 공사초기의 양중계획은 건설현장의 특성을 면밀히 고려하고 효과적으로 계획수립에 반영될 필요성이 있다. 하지만 현재 건설현장에서 가설리프트 계획수립은 사이클 주기(Cycle Time)를 바탕으로 한 단순계산식을 사용하고 있다. 이 방법은 쉽고 간단하지만, 복잡하고 유기적인 현장의 현실을 제대로 고려하지 못한다는 한계가 있다. 따라서 본 연구에서는 이러한 한계점을 극복하기 위한 방안으로, 확률적 대기행렬의 큐잉이론(Queueing Theory)을 이용한 시뮬레이션모델의 적용 가능성에 대해 알아보고자 한다.

• Journal of Biosystems Engineering
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• 제18권4호
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• pp.344-350
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• 1993

The purpose of this study is to develop design equations to calculate optimum specifications and dimensions such as weight, engine horsepower, etc. of the tractor necessary to perform stable rotary tillage. The main results of this study are as follows. 1. A wheel-lug ought to receive a special resistance in downward direction which resists the lug's upward motion on wet sticky soil surface. The authors introduce a new academic name of the "lift resistance(上昇抵抗力, 상승저항력)" for such a force which resists retraction of a wheel lug from the soil in the upward trochoidal motion. This force is composed of the frictional force acting on the trailing and the leading lug side, and the "perpendicular adhesion(鉛直付着力, 연직부착력)" acting on the lug face and the undertread face on adhesive soil. 2. The "lift resistance ratio(上昇抵抗力係數, 상승저항력계수)" and the "perpendicular adhesion ratio(鉛直付着力係數, 연직부착력계수)" were defined, which are something similar to the definition of the motion resistance ratio, the traction coefficient, etc. 3. The design equation of the optimum weight of a rotary tiller mounted on the tractor derived by calaulating the forces acting on the rotary blades. 4. The design equations to calculate optimum specifications and dimensions such as weight, engine horsepower, etc. of the tractor necessary to perform stable rotary tillage were derived. It becomes clear that the optimum weight of a rotary tiller and a tractor can be estimated in planning design by means of putting about 21 design factors of the target into the equation. These equations are useful for planning design to estimate the optimum dimensions and specifications of a rotary tiller as well as a tractor by the use of known and/or unknown design parameters.

• 한국건설관리학회논문집
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• 제13권5호
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• pp.135-143
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• 2012

초고층 건축물은 일반적 건축물에 비해, 구조, 환경적 분야 뿐 아니라 시공 분야에서도 골조공사와 마감공사의 시공방법, 재료, 공사관리 등에서 차이점이 있다. 특히 초고층 건축물 시공에서 요구되는 다양한 관리기법 중 양중계획 및 관리는 핵심적인 분야이며, 건설공사에 필요한 인원 및 자재와 같은 자원을 리프트카와 같은 양중기계장비를 이용하여 효율적으로 수직이동하여야 한다. 그러나 리프트카의 경우 초기 수립된 계획과 실제 운영에 차이가 발생하는 경우가 많고 이러한 비효율성으로 인해 문제가 발생하는 경우가 많다. 본 연구에서는 양중작업에 사용되는 리프트카를 대상으로 건축마감공사의 자원물량에 근거한 양중부하 산정 방법 및 예측 모델을 제시하고자 한다. 그 결과 리프트카 운행시간 및 사이클타임을 계산하여 총 양중장비 가동시간 및 양중가능 물량을 산출할 수 있을 것이다. 이를 양중장비조합을 위한 의사결정 지원 모델 구축을 위한 연구로 발전시켜 나갈 것이다.

• 로봇학회논문지
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• 제17권4호
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• pp.500-507
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• 2022

In this study, a motion planning method based on the integer representation of contact status between wheels and the ground is proposed for planning swing motion of a 6×6 wheel-legged robot to cross large obstacles and gaps. Wheel-legged robots can drive on a flat road by wheels and overcome large obstacles by legs. Autonomously crossing large obstacles requires the robot to perform complex motion planning of multi-contacts and wheel-rolling at the same time. The lift-off and touch-down status of wheels and the trajectories of legs should be carefully planned to avoid collision between the robot body and the obstacle. To address this issue, we propose a planning method for swing motion of robot legs. It combines an integer representation of discrete contact status and a trajectory optimization based on the direct collocation method, which results in a mixed-integer nonlinear programming (MINLP) problem. The planned motion is used to control the joint angles of the articulated legs. The proposed method is verified by the MuJoCo simulation and shows that over 95% and 83% success rate when the height of vertical obstacles and the length of gaps are equal to or less than 1.68 times of the wheel radius and 1.44 times of the wheel diameter, respectively.

• 한국항해항만학회지
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• 제30권4호
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• pp.285-290
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• 2006

Shipping companies consider most of the ship turnaround time as a critical factor when selecting a rolling port for reducing costs. So, many researchers have been studying for the optimization of preplanning and high~performance of the Gantry Cranes (GCs) in container terminals for faster loading and unloading. Therefore, in this paper, we propose an RFID (Radio Frequency Identification) based RTLS (Real-Time Location System) for reducing the ship turnaround time in ubiquitous port environment. In addition, pre-planning based on ubiquitous computing environment will support the GC and Yard Tractors (YTs), and reduce ship turnaround time more effectively. Especially, the proposed method enormously enhances the productivity of loading for the twin-lift system It will reduce the whole lead-time in the process of port logistics.

• 산업경영시스템학회지
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• 제35권1호
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• pp.39-46
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• 2012

An unmanned aerial vehicle (UAV) is a powered aerial vehicle that does not carry a human operator, uses aerodynamic forces to provide vehicle lift, can fly autonomously or be piloted remotely, can be expendable or recoverable, and can carry a lethal or non-lethal payload. An UAV is very important weapon system and is currently being employed in many military missions (surveillance, reconnaissance, communication relay, targeting, strike, etc.) in the war. To accomplish UAV's missions, guarantee of survivability should be preceded. The main objective of this study is a local path planning to maximize survivability for UAV on the battlefield of dynamic threats (obstacles, surface-to-air missiles, radar etc.). A local path planning is capable of producing a new path in response to environmental changes. This study suggests a $Smart$ $A^*$ (Smart A-star) algorithm for local path planning. The local path planned by $Smart$ $A^*$ algorithm is compared with the results of existing algorithms ($A^*$ $Replanner$, $D^*$) and evaluated performance of $Smart$ $A^*$ algorithm. The result of suggested algorithm gives the better solutions when compared with existing algorithms.

• 농촌계획
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• 제10권3호
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• pp.53-58
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• 2004

In this study the effect caused by limited storage lift of agricultural products for determining shipping amount can be analyzed by $l^{st}$ order autoregressive model based on cobweb theorem. Carrying capacity and auction price of upland-grown cabbage and garlic from 2000 to 2003 in wholesale markets were used for analysis. In result regression models of cabbage can not be used in verification periods although those of garlic approximately predicted shipping amounts in verification periods. It can be inferred that it is hard to control shipping amounts depending on price fluctuation for agricultural products which have limited storage life so cultivated areas and meteorological risk should be managed for stable price.

• Advances in aircraft and spacecraft science
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• 제5권5호
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• pp.551-579
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• 2018

This work is concerned with the motion of propeller driven airplanes, flying at constant velocity on ascending or descending rectilinear trajectories. Its purpose is to provide important features of rectilinear flights that are required for airplane trajectory planning but that cannot be found already published. It presents a method for calculating the amount of fuel used, the restrictions on the trajectory parameters, as inclination and speed, which result from the load factor, the lift coefficient, the positivity and upper boundedness of the power available. It presents a complete discussion of both ascending and descending flights, including gliding. Some original remarks are made about the parameters of gliding. It shows how to construct tables of parameters allowing to identify rapidly flyable trajectories. Sample calculations are shown for the Cessna 182 and a Silver Fox like unmanned aerial vehicle.

• International Journal of Control, Automation, and Systems
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• 제3권1호
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• pp.87-99
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• 2005

We present in this paper the stabilization (tracking) with motion planning of the six independent configurations of a mini unmanned areal vehicle equipped with four streamlined rotors. Naturally, the yaw-dynamic can be stabilized without difficulties and independently of other motions. The remaining dynamics are linearly approximated around a small roll and pitch angles. It will be shown that the system presents a flat output that is likely to be useful in the motion generation problem. The tracking feedback controller is based on receding horizon point to point steering. The resulting controller involves the lift (collective) time derivative for what flatness and feedback linearization are used. Simulation tests are performed to progress in a region with approximatively ten-meter-buildings.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.250-256
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• 2009

This paper presents a robotic tower-crane system using encoder and gyroscope sensors as path tracking devices. Tower crane work is often associated with falling accidents and industrial disasters. Such problems often incur a loss of time and money for the contractor. For this reason, many studies have been done on an automatic tower crane. As a part of 5-year 23-million-dollar research project in Korea, we are developing a robotic tower crane which aims to improve the safety level and productivity. We selected a luffing tower crane, which is commonly used in urban construction projects today, as a platform for the robotic tower crane system. This system comprises two modules: the automated path planning module and the path tracking module. The automated path planning system uses the 3D Cartesian coordinates. When the robotic tower crane lifts construction material, the algorithm creates a line, which represents a lifting path, in virtual space. This algorithm seeks and generates the best route to lift construction material while avoiding known obstacles from real construction site. The path tracking system detects the location of a lifted material in terms of the 3D coordinate values using various types of sensors including adopts encoder and gyroscope sensors. We are testing various sensors as a candidate for the path tracking device. This specific study focuses on how to employ encoder and gyroscope sensors in the robotic crane These sensors measure a movement and rotary motion of the robotic tower crane. Finally, the movement of the robotic tower crane is displayed in a virtual space that synthesizes the data from two modules: the automatically planned path and the tracked paths. We are currently field-testing the feasibility of the proposed system using an actual tower crane. In the next step, the robotic tower crane will be applied to actual construction sites with a following analysis of the crane's productivity in order to ascertain its economic efficiency.