• 한국철도학회논문집
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• 제19권2호
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• pp.213-223
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• 2016

도시에 밀집된 인구에 의하여 교통 혼잡이 빈번하게 일어나고 있으며 그에 따른 도시민의 불편이 증대 되었다. 이러한 교통 불편을 최소화 하는 방안으로 저심도 철도와 같은 다양한 교통시스템이 제안되고 있다. 본 논문에서는 경제적인 저심도 철도시스템 구축을 위하여 개발중인 트렌치쉴드의 설계와 더불어 소형 트렌치 쉴드 장비를 제작하여 트렌치 쉴드의 적용성에 대한 검토가 이루어졌다. 본 논문에서 도출한 트렌치 쉴드는 굴착부와 쉴드부, 추진부로 구성되어있다. 이렇게 검토 및 설계된 트렌치쉴드의 적용성을 검토하기 위하여 실내실험을 추진하였으며 이를 통하여 트렌치 쉴드를 통한 개착시공현장의 급속시공이 가능함을 확인하였다. 비록 실내실험이고 상대적으로 소규모의 실험이지만 트렌치 쉴드를 이용할 경우 3m/일의 시공속도 확보가 가능할 것으로 판단된다.

• 드라이브 ㆍ 컨트롤
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• 제17권3호
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• pp.15-25
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• 2020

The cycle time and power saving effect of a hydraulic hybrid injection molding machine using a servo motor are considered in this paper. In order to verify control characteristics, such as pressure and speed, experiments were performed with the hydraulic hybrid injection molding machine, clamping force of 110 ton. The power consumption and production cycle time of a conventional hydraulic injection molding machine were measured to compare its performances with the hydraulic hybrid injection molding machine. An injection molding machine with a clamping force of 1300 ton was used as the conventional machine, the hybrid machine was implemented by replacing its induction motors with servo motors. In the remodeled hybrid machine, experiments were performed to investigate how the displacement of the mold clamping pump affects the power consumption and production cycle time. The results showed that the production cycle time of the hybrid injection molding is similar to a conventional hydraulic injection molding machine but with a significant energy saving of about 40%.

• 드라이브 ㆍ 컨트롤
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• 제19권4호
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• pp.62-69
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• 2022

Construction machinery is exposed to accidents such as collisions, narrowness, and overturns during operation. In particular, mobile crane is operated only with the driver's vision and limited information of the assistant worker. Thus, there is a high risk of an accident. Recently, some collision avoidance device using sensors such as cameras and LiDAR have been applied. However, they are still insufficient to prevent collisions in the omnidirectional 3D space. In this study, a rotating LiDAR device was developed and applied to a 250-ton crane to obtain a full-space point cloud. An algorithm that could provide distance information and safety status to the driver was developed. Also, deep-learning segmentation algorithm was used to classify human-worker. The developed device could recognize obstacles within 100m of a 360-degree range. In the experiment, a safety distance was calculated with an error of 10.3cm at 30m to give the operator an accurate distance and collision alarm.

• Steel and Composite Structures
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• 제25권3호
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• pp.327-335
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• 2017

To gain more knowledge of aluminum foam sandwich structure and promote the engineering application, aluminum foam sandwich consisting of 7050 matrix aluminum foam core and 304 stainless steel face-sheets was studied under three-point bending by WDW-T100 electronic universal tensile testing machine in this work. Results showed that when aluminum foam core was reinforced by 304 steel face-sheets, its load carrying capacity improved dramatically. The maximum load of AFS in three-point bending increased with the foam core density or face-sheet thickness monotonically. And also when foam core was reinforced by 304 steel panels, the energy absorption ability of foam came into play effectively. There was a clear plastic platform in the load-displacement curve of AFS in three-point bending. No crack of 304 steel happened in the present tests. Two collapse modes appeared, mode A comprised plastic hinge formation at the mid-span of the sandwich beam, with shear yielding of the core. Mode B consisted of plastic hinge formation both at mid-span and at the outer supports.

• 대한인간공학회지
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• 제29권2호
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• pp.249-255
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• 2010

The visibility evaluation is significant for the development of construction equipment. The visibility evaluation follows the standards of ISO 5006, ISO 14401-1, and ISO 14401-2. The evaluation contains the operator's visibility and the visibility of rear-view mirrors. The operator's visibility includes the visibility test which requires the recognition of the rectangular line surrounding the machine by one meter and the circle with a 12 meter radius. This study describes the two evaluation processes for the development of the wheel loader. The first process is the light bulb shadow test by using a prototype wheel loader. The second process is based on computer simulation in virtual space. The advantages and disadvantages of computer simulation process are investigated.

• 드라이브 ㆍ 컨트롤
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• 제9권4호
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• pp.26-31
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• 2012

Friction reduction between sliding hydraulic machine components is required to improve efficiency and reliability of hydraulic machineries. It is recently reported that surface texturing on sliding bearing surfaces can reduce the friction force highly. In this paper, numerical analysis is carried out to investigate the effect of dimple numbers and inlet boundary pressures on the lubrication characteristics of a parallel sliding bearing using a commercial computational fluid dynamics (CFD) code, FLUENT. The results show that the pressure distribution, load capacity, dimensionless friction force and leakage with dimple number and their locations, and inlet pressures. The overall lubrication characteristics are highly affected by dimple numbers and boundary pressure. The numerical method adopted and results can be used in design of efficient hydraulic machine components.

• 국제학술발표논문집
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• The 5th International Conference on Construction Engineering and Project Management
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• pp.513-516
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• 2013

Earthmoving equipment's haul-route has a great influence on the productivity of the earth work operation. Haul-route grade is a critical factor in selecting the haul-route. The route that has low grade resistance contributes to increase machine travel speed and production. This study presents a mathematical model called "Hauling-Unit Optimal Routes Selecting system" (HUORS). The system identifies optimal path that maximize the earth-work productivity. It consists of 3 modules, i.e., (1) Module 1 which inputs site characteristic data and computes site location and elevation using GIS(Geographical Information System); (2) Module 2 which calculates haul time; (3) Module 3 which displays an optimum haul-route by considering the haul-route's gradient resistances (i.e., from the departure to the destination) and hauling time. This paper presents the system prototype in detail. A case study is presented to demonstrate the system and verifies the validity of the model.

• Tribology and Lubricants
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• 제36권6호
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• pp.307-314
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• 2020

In this paper, studies on application cases of machine condition monitoring using oil sensors are reviewed. Owing to rapid industrial advancements, maintenance strategies play a crucial role in reducing the cost of downtime and improving system reliability. Consequently, machine condition monitoring plays an important role in maintaining operation stability and extending the period of usage for various machines. Machine condition monitoring through oil analysis is an effective method for assessing a machine's condition and providing early warnings regarding a machine's breakdown or failure. Among the three prevalent methods, the online analysis method is predominantly employed because this method incorporates oil sensors in real-time and has several advantages (such as prevention of human errors). Wear debris sensors are widely employed for implementing machine condition monitoring through oil sensors. Furthermore, various types of oil sensors are used in different machines and systems. Integrated oil sensors that can measure various oil attributes by incorporating a single sensor are becoming popular. By monitoring wear debris, machine condition monitoring using oil sensors is implemented for engines, automotive transmission, tanks, armored vehicles, and construction equipment. Additionally, such monitoring systems are incorporated in aircrafts such as passenger airplanes, fighter airplanes, and helicopters. Such monitoring systems are also employed in chemical plants and power plants for managing overall safety. Furthermore, widespread application of oil condition diagnosis requires the development of diagnostic programs.

• International Journal of Control, Automation, and Systems
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• 제1권4호
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• pp.484-494
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• 2003

In this paper, we describe a hydraulic system design and vehicle dynamic modeling for development of tire roller traction, an essential aspect in the system analysis of tire rollers. Generally, tire rollers are one of the most useful types of machines employed in road construction, technically applied to many construction fields. We also conceptualize a new hydraulic and driving system as well as define the motion equations for dynamic and hydraulic analysis. First, we design the hydraulic circuit of the steering control and driving machine system, which can be employed to advance the performance of the lateral control, creating a prototype of construction equipment. Second, we formulate the hydraulic steering system model and hydraulic driving system model through tire roller system development technology. Finally, we validate the acquired performance results in actual tire roller equipment using the data acquisition system. These results may perhaps facilitate the establishment of priorities and design strategies for incremental introduction of tire roller technology into the vehicle and construction field.

• 한국건설관리학회논문집
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• 제21권2호
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• pp.15-21
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• 2020

국토교통부가 2017년 12월에 발표한 제6차 건설기술진흥기본계획에 따르면, 건설기술혁신 등을 통해 2022년까지 건설 노동생산성을 40% 향상하는 것을 주요 목표로 하고 있다. 또한, 건설업계 및 학계에서는 건설 생산성 향상을 위해 지속적으로 다양한 연구 및 개발을 해오고 있다. 본 연구에서는 과거 15년간 대한토목학회 영문논문집에 발표된 생산성(Productivity) 관련 논문을 대상으로 어 프라이오리(A Priori) 알고리즘을 활용하여 키워드(Keyword) 간의 상관관계를 분석하였다. 분석 결과, 생산성 연구 키워드는 '작업(Work)' 및 '노무 인력(Labor)' 단어와 연관성이 매우 높은 것으로 나타났으며 생산성 영향요소, 생산성 모델과 시뮬레이션, 그리고 작업 시간에 따른 생산성 등이 키워드로 주로 연구되고 있음이 밝혀졌다. 또한, 건설기계(Machine) 혹은 장비(Equipment)와의 상관성은 낮은 것으로 분석되었다. 본 연구는 텍스트 마이닝(Text Mining)을 활용하여 국내 토목 분야에서 이루어진 생산성 관련 연구들의 개략적인 상관성과 경향을 분석하였으며, 특정 분야에서 이루어지고 있는 연구 동향 분석의 새로운 방안을 제시하였다.