• Journal of Drive and Control
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• v.11 no.4
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• pp.39-45
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• 2014

With recent oil price increases, the fuel efficiency of hydraulic excavators has become a serious issue. Researchers have considered weight lightening by high pressurization in order to improve the efficiency of the excavator and pump controlled actuation (PCA) and to reduce pressure loss of hybrid and valves using mechanical inertia. However, high pressurization is not very effective because the excavator operates at a low speed; a hybrid is inefficient because little accumulated inertial energy is accumulated; and PCA is ineffective because control precision and responsibility are low. In this study, a method to minimize air and gas in hydraulic oil has been presented as a simple and new way to increase hydraulic efficiency.

• Transactions of The Korea Fluid Power Systems Society
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• v.6 no.4
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• pp.9-15
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• 2009

Hydraulic excavators are the representative of field robot and have been used in various fields of construction. Since the excavator operates in the hazardous working environment, operators of excavator are exposed in harmful environment. Therefore, the hydraulic excavator automation and remote operation system has been investigated to protect from the hazardous working environment. In this paper, remote operation excavator system is developed using the mini hydraulic excavator and the tracking control system of each links of excavator is designed. To apply the tracking control system, the adaptive sliding mode control algorithm is proposed. It is found that the performance of the proposed control system is improved through experimental results of using the remote operation excavator system.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.100-101
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• 2018

Environmental problems caused by air pollution have been considered as serious critical issues in global perspectives. Controlling greenhouse gases has become one of the major environmental problems in construction fields as well. However, similar studies were mainly focused on suggestion of various methodologies for measuring CO₂ emissions of construction equipment and calculating emissions. This study aims to analyze the correlation between the CO₂ emissions and RPMs of equipment by the construction process based on row data collected from construction equipment actually operated in job sites. This study allows site personnels to determine the amount of emitted CO₂ under particular construction equipment under specific conditions during the targeted construction operations. The research findings expect to be used as fundamental informations for establishing environment-friendly construction operation planning.

• Journal of Applied Reliability
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• v.9 no.3
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• pp.177-193
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• 2009

Hydraulic breakers, the attachment devices of the excavators, refer to a machine that converts back and forth motions of pistons into energies to break objects down finely. As the use of hydraulic breakers has been steadily increasing world-wide, consumers have become more interested in not just the quality of hydraulic breakers but their reliability. This study show functions and usages of several main parts on hydraulic breakers. In addition, based on the effect of action of hydraulic breakers, FMEA was performed to figure out the major causes and manifestations of malfunctioning. As above mentioned, we analyzed reliability of hydraulic breakers by models, and the data that had been used for the analyses were obtained from malfunctioning data in the field.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05a
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• pp.205-206
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• 2011

Various studies on energy saving for construction sites have been carried out and some construction machines using motors have installed regenerative systems such as elevators and excavators. The construction lift also uses motors and generates more regenerative energy when the lifts descend because lifts convey many construction materials and workers. For this reason, it is possible to apply the regenerative system to the construction lift. However, if the system is applied without considering the lift's characteristics, the new development would fail; we therefore need to propose a performance requirement. Thus, the purpose of this study is to propose a performance requirement for the energy-regenerative lift prior to developing the energy-regenerative lift.

• Journal of Drive and Control
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• v.18 no.4
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• pp.65-71
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• 2021

In this paper, the development of a vibration reduction device for hydraulic breakers was studied. Generally, a hydraulic breaker generates shock vibrations while working. When using vibration-proof rubber, shock vibrations are reduced, but without this, shock vibrations are repeatedly generated. Such repeated shock vibrations not only lower the fatigue strength of hydraulic breakers and excavators equipped with them but also increase the fatigue of the workers. This paper proposes the possibility of reducing shock vibration by using a dynamic vibration absorber.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.06a
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• pp.107-108
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• 2020

The severity of the global climate crisis is increasing due to greenhouse gases caused by human activities. As a result, countries and industries are making efforts to reduce carbon dioxide emissions, the biggest cause of global warming. Many studies have been conducted to predict carbon emissions in the construction sector to reduce this, but they have not actually produced a highly usable formula in the field. Therefore, the two variables 'Curve Fitting' were performed based on the data of excavators and trucks measured at the field. As a result, we have obtained a carbon dioxide emission prediction model for construction equipment, and we would like to use it to help establish an eco-friendly process plan.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.06a
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• pp.16-17
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• 2020

In this paper, we intended to present a model for estimating carbon dioxide emissions by work of construction equipment using Artificial Neural Network(ANN) analysis. In this study, data of excavators and trucks are classified according to the work carried out, and carbon dioxide emissions are predicted through ANN based on equipment information and work information. As a result, the effect of each model was validated, and a carbon dioxide emission prediction model was derived for each work. This has the expected effect of establishig an eco-friendly process plan using this model from the construction planning stage.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.86-87
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• 2021

As non-road mobile pollutants such as construction equipment are emerging as the main cause of air pollutants emission, construction equipment regulations are gradually strengthening. Research was conducted by correcting the emission coefficient to calculate and predict air pollutant emissions of construction equipment, but it did not reflect site variables such as field and equipment conditions that affect actual emissions. This study derived an Artificial Neural Network emission prediction model based on the actual emission data of excavators and trucks measured at the site and proposed a platform to predict the emission of air pollutants at the site according to the working size and conditions. Through this, it is possible to establish an eco-friendly process plan using a model from the construction plan.

• Korean Journal of Construction Engineering and Management
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• v.23 no.2
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• pp.16-23
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• 2022

This study examined the trend of international competitiveness over the past 10 years (2011-2020), focusing on comparative analysis with China and the United States, targeting seven major export items of Korean construction machinery based on 6 units of HS code. To this end, the export similarity index and trade competitiveness index were calculated and analyzed using UN Comtrade and Korea International Trade Association trade statistics. As a result of the analysis, competition between Korea and China has intensified over the past decade, and competition with the United States has remained at a certain level. Korean forklifts (8427.20) are exporting to the world with strong competitiveness in the global market. Excavators (8429.52) and loaders (8429.51), which have the largest export share of Korean construction machinery, have a weight advantage, but they are exporting due to price inferiority. The rest of the items were found to be inferior in price and weight, and were not competitive in the global market. These analysis results suggest the following implications. First, it is necessary to strengthen efforts to expand exports of universal construction machinery items, which are expected to increase in demand in the future, by boosting the economy and expanding infrastructure investment in accordance with eco-friendly policies. Second, excavators, which have been shown to have a quality advantage and a price competitive advantage, need to further strengthen export marketing activities not only in China and the United States but also in emerging developing countries.