• International Journal of High-Rise Buildings
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• v.11 no.3
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• pp.207-219
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• 2022

During the structural design of urban over-track high-rise buildings, two problems are most likely encountered: the abrupt change of story stiffness between the podium and the upper towers, as well as the demand for train-induced vibration control. Traditional earthquake-resistant structures have to be particularly designed with transfer stories to meet the requirement of seismic control under earthquakes, and thus horizontal seismic isolation techniques are recommended to solve the transfer problem. The function of mitigating the vertical subway-induced vibration can be integrated into the isolation system including thick rubber bearings and 3D composite vibration control devices. Engineering project cases are presented in this paper for a more comprehensive understanding of the engineering practice and research frontiers of urban over-track high-rise buildings in China.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.252-255
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• 2005

The effort to realize the concept of stratospheric airship, which can fly at about 20km altitude, has been persevered since late 1980's. Referring to the feasibility study of ensuring the flight duration of the airship over 1year, total weight is about 30 tons, the length is about 200m. There are lots of key technologies to be solved to develop the system, and one of the essential prerequisite technologies is regenerative fuel cell system. In this paper, design requirement of regenerative fuel cell system is introduced with the feasibility study results of the challenging stratospheric airship.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.435-435
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• 2000

Light Rail Transit (LRT) system is a complex and large system in which there are many subsystems, interfaces, functions and demanding performance requirements. Because many contractors participate in the development, it is necessary to apply methods of sharing common objectives and communicating effectively among all of the stakeholders. This paper shows not only the methodology and the results of computer-aided systems engineering including requirement management, functional analysis and architecting LRT system, but also propose a tool to help manage a project by linking WBS (Work Breakdown Structure), work organization and PBS (Product Breakdown Structure). The application of computer-aided tool RDD-100 provides the capability to model product design knowledge and decisions about important issues such as architecting the top-level system. The product design knowledge will be essential in integrating the following life-cycle phase activities over the life of the LRT system. Additionally, when a new generation train system is required, the reuse of the database can increase the system design productivity and effectiveness significantly.

• Journal of The Korean Society of Agricultural Engineers
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• v.50 no.4
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• pp.59-66
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• 2008

Anaerobic digestion system is getting more attractive in that it produces biogas in the process of organic waste stabilization. Net energy production is important when biogas production is concerned. In this study, net energy production was evaluated with respect to biogas production and heat losses in a hypothetical digester. Under the condition of digester operation with slurry inflow of 5% of TS, additional fuel is required to maintain digester temperature during the winder season. Substrate therefore, needs to have higher VS contents through co-digestion of silage or food waste that has greater values of methane production rate. Heating input slurry is important in cold season, which covers over 80% of heating requirement. Heat recovery from digestate is valuable to reduce the use of biogas for heating. It seems desirable to minimize slurry inflow when temperature is very low. Psychrophilic digestion may be a feasible option for reducing heating requirement.

• Proceedings of the KSR Conference
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• 2002.10b
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• pp.857-862
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• 2002

The bogie, when run on the twist track develops the wheel off-loading factor. This will be comfirmed by testing under different loading conditions and air springs inflated and deflated in all conditions. Under the most extreme twist track condition, EMU (Electrical Multiple Unit) shall not over the wheel off-loading requirement 60% defined on UIC / ORE report. This paper describes the wheel off-loading test procedure according to UIC / ORE and test result of DMRC EMU of INDIA carried out to find out to meet the requirement defined in UIC / ORE.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.3
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• pp.1599-1610
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• 2019

Intelligent services have expanded as Internet of Things (IoT) technology has evolved and new requirements emerge to accommodate various services. One new requirement is transmitting data over long distances with low-power. Researchers have developed low power wide area (LPWA) network technology to satisfy the requirement; this can improve IoT network infrastructure and increase the range of services. However, network coverage expansion causes several problems. The traffic load is concentrated at a specific gateway, which causes network congestion and leads to decreased transmission efficiency. Therefore, the approach proposed in this paper attempts to recognize and then avoid congestion through gateway channel hopping. The LPWA network employs multiple channels, so wireless channel hopping is available in a gateway. Devices that are not delay sensitive wait for the gateway to reappear on their wireless channel; delay sensitive devices change the wireless channel along the hopping gateway. Thus, the traffic load and congestion in each wireless channel can be reduced improving transmission efficiency. The proposed approach's performance is evaluated by computer simulation and verified in terms of transmission efficiency.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.1
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• pp.107-113
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• 2010

The criteria of tugboat requirement in domestic trading ports have been determined by the administrator of regional maritime affairs and port office on the basis of the regulations for the tugboat operations and management. But, there is a little confusion that the criteria of tugboat requirement and method for calculation of them are different from port to port and total power calculated on the basis of power per tugboat requirements by the number of tugs is not in accordance with total required power for the use of tug in several ports. The comparison of tugboat requirements among domestic major ports showed that it should be necessary for the criteria to be made in unified form. Because the current criteria are only on the basis q the ordinary condition with wind velocity under 10m/s, the criteria on the condition of the wind velocity over 10m/s are suggested to be necessary for the precautions against a disaster such as unexpected strong winds or typhoon.

• Journal of information and communication convergence engineering
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• v.16 no.1
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• pp.1-5
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• 2018

In radio-over-fiber (RoF) systems, nonlinear compensation is very important to meet the error vector magnitude (EVM) requirement of the mobile network standards. In this study, a nonlinear compensation technique based on an artificial neural network (ANN) is proposed for RoF systems. This technique is based on a backpropagation neural network (BPNN) with one hidden layer and three neuron units in this study. The BPNN obtains the inverse response of the system to compensate for nonlinearities. The EVM of the signal is measured by changing the number of neurons and the hidden layers in a RoF system modeled by a measured data. Based on our simulation results, it is concluded that one hidden layer and three neuron units are adequate for the RoF system. Our results showed that the EVMs were improved from 4.027% to 2.605% by using the proposed ANN compensator.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.19 no.3
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• pp.33-42
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• 2011

This study focused to find the main factors causing job stress to ROKAF pilots and of which factors affects to turnover intention. As a results, the factors of job stress are job characteristics, over loaded ground work, payment, promotion and employee benefits & service system. All of these 5 factors are positively related to the causes of a pilot stress. Among the job stress factors, payment, promotion and over loaded ground work are positively related as the same order. But, job characteristics and employee benefits & service system are not. Even though ROKAF pilots are stressed by annual requirement and night flying, and also are stressed by unfulfilled welfare, those two stress factors are not related to the turnover intention.

• Journal of Biosystems Engineering
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• v.36 no.4
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• pp.243-251
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• 2011

Purpose of this study was to analyze power requirement of an agricultural tractor for baler operation. First, a power measurement system was developed and installed in a 75 kW agricultural tractor. Strain-gages with a telemetry system were used to measure torques of transmission and PTO input shafts. An engine tachometer was used to measure rotational speed of transmission and PTO input shafts. The measurement system also included pressure sensors to measure pressure of hydraulic pumps, an I/O interface to acquire the sensor signals, and an embedded system to determine power requirements. Second, field experiments were conducted at two PTO speed levels, and proportion of utilization ratio of rated engine power and power consumption of major parts (transmission input shaft, PTO input shaft, main hydraulic pump, and auxiliary hydraulic pump) were analyzed. Results of usage proportion of engine power for PTO speed level 1 and 2 were 4.1 and 2.2%, 31.5 and 16.3%, 49.6 and 59.7%, 14.4 and 20.8%, and 0.4 and 1.0%, respectively, for ratio of measured engine power to rated engine power of less than 25%, 25 ~ 50%, 50 ~ 75%, 75 ~ 100%, and greater than 100%. The results showed that the usage proportion increased in the range with the ratio of power requirement to rated engine power of over than 50% when the PTO gear was shifted from P1 to P2. Averaged engine power requirement for baling operation, tying and discharging operation, and total operation were 43.3, 37.3, and 42.0 kW and 49.0, 37.0, and 47.4 kW, respectively, for PTO speed level 1 and 2. Paired t-test showed significant difference in power consumption of engine, transmission input shaft, and PTO input shaft for different PTO speed levels. Therefore, the power consumption of engine for baler operation increased when the PTO gear was shifted from P1 to P2. It was indicated that the power requirement of tractor was affected by the PTO rotational speed for baler operation.