• 한국자동차공학회논문집
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• 제25권2호
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• pp.190-200
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• 2017

In general, an assessment of the benefits and costs with regard to vehicle safety standards are validated before regulations are implemented. This paper performs this validation for the mandatory automobile safety devices requirement for new micro-mobility. The reviewed car safety standards involved the installation of seat belts, airbags, ABS, crash speed standards, and pedestrian warning system. The benefit was estimated as the cost of accident reduction due to the installation of vehicle safety standards. As a result, the safety belt showed a B / C of 4.0 or higher, and it was found that the seat belt should be installed from 2017. After the seatbelt regulation in 2017, the results of the scenarios with the airbag, ABS, crash speed of 40 km/h, and the pedestrian warning system showed B / C of 1.0 or more according to the year of regulation. This study can be useful as a tool in the decision-making process with regard to the timing and type of vehicle safety standards requirement of micro-mobility in the future.

• International Journal of Naval Architecture and Ocean Engineering
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• 제6권4호
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• pp.826-839
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• 2014

Fire is a continuous threat to FPSO topside modules as large amounts of oil and gas are passing through the modules. As a conventional measure to mitigate structural failure under fire, passive fire protection (PFP) coatings are widely used on main structural members. However, an excessive use of PFP coatings can cause considerable cost for material purchase, installation, inspection and maintenance. Long installation time can be a risk since the work should be done nearly at the last fabrication stage. Thus, the minimal use of PFP can be beneficial to the reduction of construction cost and the avoidance of schedule delay. This paper presents a few case studies on how different applications of PFP have influence on collapse time of a FPSO module structure. A series of heat analysis and thermal elasto-plastic FE analysis are performed for different PFP coatings and the resultant collapse time and the amount of PFP coatings are compared with each other.

• 조명전기설비학회논문지
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• 제12권2호
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• pp.69-76
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• 1998

본 논문에서는 배압터빈과 추기복수터빈으로 이루어진 열병합 발전플랜트의 최전운전을 결정할 수 있는 새로운 알고리즘을 제시한다. 제시한 알고리즘은 플랜트가 운전중에 직접 온 라인으로 취할 수 있는 증가량만을 파라메타로 하여 보일러와 터빈-발전기의 최적부하를 결정할 수 있다. 본 알고리즘은 비선형 경비함수와 해당 제한사항들로 이루어져 있으며 실제 운전중인 열병합 발전플랜트와 비교 시뮬레이션을 실시한 결과 만족할만한 결과를 얻었다. 즉 실제 운전 데이터와 비교해본 결과 공정의 증기 부하량에 따라 1.2∼4.5[%]의 운전경비 절감효과를 얻을 수 있었다. 또한 본 알고리즘은 필요한 입력 데이터를 공정으로부터 쉽게 온 라인으로 취할 수 있어 프로세스 컴퓨터로 용이하게 구현할 수 있다.

• 조명전기설비학회논문지
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• 제28권11호
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• pp.58-67
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• 2014

A grid-connected inverter used for renewable energy resources produces harmonic components in the switching frequency. To effectively reduce switching harmonic components, several types of filter are generally used in the output stage of the grid-connected inverter. Many research works on LCL filter design have been done to maintain the performance with low cost. However, it is not easy to make the filter design be economical and optimal due to the varying characteristic of magnetic core and redundancy design by experience. In this paper, a design method for a LCL filter is presented through the inductor optimization scheme in view of the size and cost when the inductor is manufactured using the magnetic core. The effectiveness is verified through tests using a 3kW grid-connected inverter by simulations and experiments.

• 조명전기설비학회논문지
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• 제28권5호
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• pp.106-114
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• 2014

The interior permanent-magnet synchronous motor (IPMSM) is often used for the traction motor of hybrid electric vehicles (HEVs) and electric vehicles (EVs) due to its high power density and wide speed range. This paper introduces the 120kW class IPMSM for traction motors in military trucks. This system, as a SHEV (series hybrid electric vehicle), requires a traction motor that can generate high torque. This study introduces a way to reduce costs by proposing a design approach that creates reluctance torque that can be maximized by varying the dq-axis inductance. If a model designed by a design approach meets the desired torque, the magnetic torque can be reduced by an amount equal to the increase in reluctance torque and consequently the amount of permanent magnets can be reduced. A reduction gear and high speed operation of motors are necessary for the miniaturization of the motor. Thus, a fairly large centrifugal force is generated due to the high speed rotation. This force causes mechanical interference between the rotor and the stator, and a design approach for adding an iron bridge is explained to solve the interference. In this study, the initial model and the improved model that reduces cost and improves mechanical durability are compared by FEA, and the models are produced. Finally, the FEM results were verified experimentally.

• 대한건축학회논문집:구조계
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• 제34권3호
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• pp.87-93
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• 2018

Ground source heat pump(GSHP) system is one of the high efficiency heat source systems which utilizes the constant geothermal energy of a underground water or soil. However, the design of conventional GSHP system in the domestic market is dependent on the experience of the designer and the installer, and it causes increase of initial installation cost or degradation of system performance. Therefore, it is necessary to develop a guideline and the optimal design method to maintain stable performance of the system and reduce installation cost. In this study, in order to optimize the GSHP system, design factors according to ground heat exchanger(GHX) type have been examine by simulation tool. Furthermore, the design factors and the correlation of a single U-tube and a double U-tube were analyzed quantitatively through sensitivity analysis. Results indicated that, the length of the ground heat exchanger was greatly influenced by grout thermal conductivity for single U-tube and pipe spacing for double U-tube.

• 국제학술발표논문집
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• The 5th International Conference on Construction Engineering and Project Management
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• pp.367-374
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• 2013

Underground infrastructure systems provide essential public services and goods through buried structures including water and sewer, gas and petroleum, power and communication pipelines. The majority of existing underground infrastructure systems was installed in green field areas prior to development of complex urban built environments. Currently, there is a global trend to escalate major demand for underground infrastructure system renewal and new installation while minimizing disruption and maintaining functions of existing superstructures. Therefore, Engineers and utility owners are rigorously seeking technologies that minimize environmental, social, and economic impact during the renewal and installation process. Trenchless technologies have proven to be socially less disruptive, more environmentally friendly, energy conservative and economically viable alternative methods. All of those benefits are adequate to enhance overall sustainability. This paper describes effective sustainable solutions using trenchless technologies. Sustainability is assessed by a comparison between conventional open cut and trenchless technology methods. Sustainability analysis is based on a broad perspective combining the three main aspects of sustainability: economic; environmental; and social. Economic includes construction cost, benefit, and social cost analysis. Environmental includes emission estimation and environmental quality impact study. Social includes various social impacts on an urban area. This paper summarizes sustainable trenchless technology solutions and presents a sustainable construction method selection process in a proposed framework to be used in urban underground infrastructure capital improvement projects.

• 전기학회논문지
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• 제63권9호
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• pp.1199-1205
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• 2014

A power system configuration has been increasingly advanced with a number of generating units. In particular, renewable energy resources are widely introduced due to the environmental issues. When applying the renewable energy sources with the ESS (Energy Storage System), the ESS is the role of a potential generating resource in the power system while mitigating the output volatility of renewable energy resources. Thus, for applications of the ESS, the surrounding environment of it should be considered, which means that capacity and energy of the ESS can be affected. Moreover, operation strategy of the ESS should be proposed according to the installation purpose as well as the surrounding environment. In the paper, operation strategy of the ESS is proposed considering load demand and the output of renewable energy resources on a hourly basis. Then, the cost of electrical energy is minimized based on the economic model that consists of capital cost, operation cost, fuel cost, and grid cost for a year. It is sure that peak-shaving effects can be achieved while satisfying the minimum cost of electrical energy.

• Earthquakes and Structures
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• 제9권1호
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• pp.73-91
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• 2015

The effectiveness of tuned mass dampers (TMDs) in reducing the seismic response of civil structures is still a debated issue. The few studies regarding TMDs on inelastic structures indicate that they would perform well under moderate earthquake loading, when the structure remains linear or weakly nonlinear, while tending to fail under severe ground shaking, when the structure experiences strong nonlinearities. TMD seismic efficiency should be therefore rationally assessed by considering to which extent moderate and severe earthquakes respectively contribute to the expected cost of damages and losses over the lifespan of the structure. In this paper, a method for evaluating, in a life-cycle cost (LCC) perspective, the seismic effectiveness of TMDs on inelastic building structures is presented and exemplified on the SAC LA 9-storey steel moment-resisting frame benchmark building. Results show that the LCC concept may provide an appropriate alternative to traditional performance criteria for the evaluation of the effectiveness of TMDs and that TMD installation on typical existing middle-rise buildings in high seismic hazard regions may significantly reduce building lifetime cost despite the poor control performance observed under the most severe seismic events.

• ETRI Journal
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• 제40권5호
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• pp.664-676
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• 2018

Given the rapidly increasing market penetration of photovoltaic (PV) systems in many fields, including construction and housing, the effective maintenance of PV systems through remote monitoring at the panel level has attracted attention to quickly detect faults that cause reductions in yearly PV energy production, and which can reduce the whole-life cost. A key point of PV monitoring at the panel level is cost-effectiveness, as the installation of the massive PV panels that comprise PV systems is showing rapid growth in the market. This paper proposes an implementation method that involves the use of a panel-level wireless PV monitoring module (WPMM), and which assesses the cost-effectiveness of this approach. To maximize the cost-effectiveness, the designed WPMM uses a voltage-divider scheme for voltage metering and a shunt-resistor scheme for current metering. In addition, the proposed method offsets the effect of element errors by extracting calibration parameters. Furthermore, a design method is presented for portable and user-friendly PV monitoring, and demonstration results using a commercial 30-kW PV system are described.