• Journal of the Korea Institute of Building Construction
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• v.14 no.5
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• pp.477-485
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• 2014

Standard production unit system and historical cost data are the most typical data base for calculating budget price in construction. However, these construction cost estimation methods are difficult to calculate proper construction cost because definition, additional allowance or modification criteria is not clear in construction within one day. Therefore, this study identifies problems for standard production unit system and historical cost data and suggests the improvements for them. For the objectives, this study analyzes frequency after implementing survey for 44 specialty contractors in placing at kyeonggi-province. As the results of the study, labor costs in standard production unit system and equipment costs in historical cost data and in construction of pavement and maintenance by project type was exceeded at most high rate against construction cost estimation methods. Based on this result, standard production unit system and historical cost data need to be modified by three improvements such as classification by project scale. These will be baseline data for improvement of construction cost estimation methods for less than one day workload.

• Transactions of The Korea Fluid Power Systems Society
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• v.4 no.1
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• pp.7-12
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• 2007

It is strongly requested to reduce fuel consumption because of high oil price and exhaust gases of road vehicles for environmental preservation. To solve these problems, several types of hybrid vehicles have been developed. Among them, flywheel hybrid vehicle using variable displacement pump/motor was already proposed as one of the feasible hybrid systems in place of hybrid vehicle by the conventional storage battery. The proposed flywheel hybrid vehicle is to keep constant pressure of high pressure line by the control of swash plate angle of flywheel pump/motor as pressure compensator. The efficiency of the overall system depends severely on the efficiency of hydraulic pump/motor in the energy saving hydraulic control system by simulation. According to the control methods of swash plate angle of piston pump/motor, there remain several problems to be solved. In this paper, experimental setup for energy saving is fabricated and the efficiency of energy saving is investigated by experiments with respect to various experimental conditions.

• Plant Journal
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• v.16 no.3
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• pp.37-41
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• 2020

Lately old LNG carriers increased and ship price is getting down. So Interest for reuse and modification of used LNG carriers is growing. Also the needs for replacement of old power plant is increasing. Additionally eco friendly fuel such as LNG become attractive. Consequently gas power plant is getting much more popular than before. So in this research planning, we consider the floating power plant by modifying LNG carriers. This plant has the various function including storage, power plant and bunkering fuction etc. Through this multifunctional plant, we are ready for the old power plant shutdown and energy crisis in the future when we can supply the urgent mobile floating power plant quickly in time.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.11
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• pp.1907-1912
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• 2016

In fact, in order to obtain good performances and low torque ripple, a high-resolution sensor is needed, which is costly and usually needs a special construction for the machine. So researchers are becoming aware of their cost and are exploring the possibility of cost reduction. Information of rotor position is necessary to drive Linear Switched Reluctance Motor(LSRM). Therefore, linear optical encoder is used to detect a mover position. Normally, since the price of encoder, which is used for linear motor is relatively higher than the one used for rotory motor and the cost of additional equipment increases with the length of motor. This is not always appropriate, considering economical efficiency in case of using the linear optical encoder. As a results, LSRM has a great part for the total cost. Therefore, in this paper, we propose LSRM position detecting modeling with reflective type photo-sensor. Additionally, we have investigated the possibility of the reduced position sensor for LSRM drives with advanced control technique. To certify the overall characteristics of the proposed method, a simulation using PSIM software has been carried out and the informative results are displayed.

• Plant Journal
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• v.10 no.4
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• pp.29-34
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• 2014

In this consideration, this research investigated the piping design items and drew out key design items through interview with experts and surveys to apply them to actual project examples and look into piping design item-specific significance and cost variation ranges. Based on this investigation, the Monte-Carlo simulation was employed herein to analyze the cost variation range for the entire piping design costs with a view to presenting a way to calculate a reasonable bidding price for any similar project and verify the appropriateness of joining a bid.

• Journal of Drive and Control
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• v.11 no.4
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• pp.46-52
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• 2014

This study suggests a small-sized screw decanter specialized for dredging sites. Generally, conventional screw decanters are composed of a cylinder and a cone. However, the suggested screw decanter simply has a cone based on a cone-type bowl structure. In this research, a commercial analysis tool is used to establish an optimal design for the bowl and the screw conveyor. Moreover, the base frame, where the main bearings that support the spindle of the bowl and the screw conveyor are installed, is optimally designed considering the weight of the rotating body and the deflection caused by the high centrifugal force. Furthermore, the natural frequency range of the spinning body, the bowl and the screw conveyor, is applied to this base frame; it is designed not to correspond to the resonance frequency range and achieves stability as a result. This study suggests an optimal design for the rotating body and the base frame of a screw decanter considering its vibration characteristics. Such a design will prevent overuse of materials and help to reduce the weight and volume-and the price-of a screw decanter.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.6
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• pp.641-647
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• 2014

Stand-alone PV systems and grid-connected distribution lines operating independently with out the advantage that it is simple, and construction equipment, but the advantage of less expensive MPPT converter and production, including the energy stored in the battery charging circuit and battery for managing circuitry is required. The use of existing alternative energy in the form of combined-cycle power generation than the one adopted by the form, but primarily solar / wind power system to optimize complex to design and improve the ability to install a battery that canrationalize the price you need an integrated control system be.

• Journal of Drive and Control
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• v.21 no.1
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• pp.16-21
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• 2024

The yaw gearbox is a key device in a wind power generator that improves power generation efficiency by rotating hundreds of tons (400 to 600 tons) of nacelle so that the blade reaches 90 degrees in the wind direction. Recently, installation sites have been advancing from land to sea as they have become super-large at (8-12) MW to increase the economic feasibility of wind power generators and utilize excellent wind resources, and the target life of large wind power generators is 25 to 30 years. The yaw gearbox of 6 to 12 sets is installed in a very complex place inside the nacelle on the tower with parallels, and it is important to secure the reliability of the yaw gearbox because if a failure occurs after installation, it costs tens to hundreds of times the price of a new product to restore. In this study, equivalent loads were calculated by analyzing failure mode and field data, accelerated life test conditions were established, and a test device was constructed to perform the accelerated life tests and performance tests to ensure the reliability of the gearbox.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.1
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• pp.106-113
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• 1997

In this paper, we introduce the design method using CAE(Computer Aided Engineering) which is profitable in the compatibility and standardization of the developed product and in the reduction of construction time and price to develop and design a machine equipment. Particularly, we select the standard model to design ot develop from the large machinery to the super precision one, extract the peculiar characters of the model by the close analysis of the physical and technical part, can predict the previous result of experimental characteristics on objective dimensions through the analogical mathematical analysis, and can induce the design model demanded by user investigating optimal data in advance. We present the analogical algorithms and process method of design factors and restriction factors in the systematization design with computer. Then we analyze step functions for each systematization equipment and induce the process of technical data with actuator model.

• Journal of the Korean Institute of Landscape Architecture
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• v.50 no.4
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• pp.20-36
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• 2022

This study aims to provide basic data for high-quality street tree management by setting reasonable management items and appropriate unit prices by reviewing the adequacy of current street tree management. Currently, street tree management items, except for street tree pruning, use general landscape tree quantity per unit for the street tree management quantity per unit. KEPCO (Korea Electric Power Corporation) applied pruning items from standard electric production infrastructure and carried out the activities at an average unit price of 51% lower for heavy pruning and 39% lower for light pruning than the standard estimate. This was judged to be a level that could not maintain or increase the quality of street tree management. It was determined that an appropriate standard unit price for street tree management was necessary. To improve the quantity per unit for the proper management of street trees, it was necessary to review costs in the field. However, due to the absence of data on actual construction costs in the domestic landscape field, detailed items of the US RSMeans Building Construction Cost Data (RSMeans) were reviewed, and the actual construction costs were calculated by applying personal domestic expenses. As a result, the standard of the estimated unit showed a good ratio of 107% for heavy pruning of street tree pruning compared to the actual construction cost, but light pruning was underestimated with a 59% ratio. Shrub pruning was 82%, weeding was 92%, tree fertilization was 87%, and windbreak wall installation was 91% under-engineered. In addition, it was also confirmed that the watering by sprinkler trucks and chemical spraying were over-designed compared to the actual construction cost at the rates of 118% and 124%, respectively. Due to the specificity of the street trees, the increase in personal expenses and the input cost of equipment, such as road safety controls, were judged to be the main cause of the underestimation of items. Therefore, it is necessary to add items related to street trees and general landscape trees to the landscape maintenance items of the standard of the estimated unit.