• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.269-269
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• 2015

두산중공업이 국책과제로 개발 중인 한국형 대형 가스터빈의 연소기 개발현황 및 결과에 대해 기술하였다. 압력손실 5%, 연소효율 99.9%, 15ppm NOx 배출 성능을 가지는 14개의 캔형 연소기로 구성되었으며, 40% turn down ratio 운전, WI ${\pm}7%$의 fuel flexibility 성능 및 dual fuel 적용 가능한 운전 성능 목표를 가진다. 이를 위해 Dry Low NOx 형 연소기를 개발, 단일 노즐 연소시험을 수행 중이며, 2016년 상반기 중 상압연소리그시험을 거쳐 그 성능을 검증하고자 한다.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.2
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• pp.85-91
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• 1998

This paper describes an study electric injection system for diesel engines. It is needed effective fuel injection which controls the solenoid valve of fuel pump. To solve this, this paper proposes DCC-PWM method which can realize fast reply and low holding current for solenoid valve on/off. For the proposed design method, simulation tools of ACSL are used to analyze the system. And the single-chip microcomputer is used to reduce the size of controller and to improve flexibility. And the systems validity can be verified through the experimental results.

• Journal of Biosystems Engineering
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• v.14 no.2
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• pp.80-84
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• 1989

In order to improve the combustion efficiency of the agricultural engine, an ignition timing control system was developed and tested. The control system was composed of the CDI ignition circuit, the microcomputer and the interfacing devices. In this study, the simplicity of the control system and the flexibility of the control strategy were emphasized for the precision, the applicability and the economical efficiency. The hardware was consisted in almost the same compositions as those of the automobile engine. The softwares of the control algorithms were developed to three types depending on the combination of the quasi-adaptive control and the open loop control which had the different spark advance equations according to the input variables such as engine speed, exhaust gas temperature and brake torque. The test results were summarized as follows: 1. By using the computer control system, the fuel consumption efficiency could be improved and the fuel consumption could be reduced by 0 to 57% compared to that of the fixed spark advance system. 2. The fuel consumption of the control mode with the quasi-adaptive algorithm was reduced by average 0.8% compared to that of the control mode without quasi-adaptive algorithm. 3. It was found that the control mode with the quasi-adaptive algorithm adopting single input of engine speed had most applicability and economical efficiency among three types of the control algorithms.

• Nuclear Engineering and Technology
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• v.26 no.1
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• pp.119-125
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• 1994

Transient power level of the fuel rod is one of the key parameters for the transient fuel behavior. Through the analysis of the fuel performance data bases and sensitivity analyses of such parameters as rod power history, fast neutron flux, fuel enrichment and cycle length, which can affect the transient fuel behavior, a methodology generally applicable to find the allowable transient power level during the ANS Conditions I and II below which the mechanical integrity of the fuel rod is maintained was derived, and allowable transient power levels for the 17$\times$17 KOFA fuel rod have been determined as a function of the burnup. With the introduction of this methodology, design analysis of the transient fuel behavior currently being calculated every cycle can be replaced by the simple check of the peak transient power level achievable during the cycle, and an operational flexibility of the reactor can be obtained by allowing higher transient power level up to 689.5 w/cm at low burnup range than current maximum allowable transient power level, 591 w/cm for the 17$\times$17 KOFA fuel.

• Geomechanics and Engineering
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• v.14 no.1
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• pp.91-98
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• 2018

Length of a vehicle is an important variation to generate different variants of an automotive platform. This parameter is usually adjusted by embedding dimensional flexibility into different components of the Body in White (BIW) including the floor pan. Due to future uncertainties, it is not necessarily possible to define certain values of wheelbase for the future products of a platform. This work is performed to add flexibility into the design process of a length-variable floor pan. By means of this analysis, the cost and time consuming process of optimization is not necessary to be performed for designing the different variants of a product family. Stiffness and mass of the floor pan are two important functional requirements of this component which directly affect the occupant comfort, dynamic characteristics, fuel economy and environmental protection of the vehicle. A combination of Genetic algorithm, GMDH-type of artificial neural networks and TOPSIS methods is used to optimally design the floor pan associated with arbitrary length of the variant in the defined system range. The correlation between the optimal results shows that for a constant mass of the floor pan, the first natural frequency decreases by increasing the length of this component.

• Clean Technology
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• v.15 no.1
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• pp.1-8
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• 2009

The adoption of compressed natural gas (CNG) as a vehicle fuel is a common phenomenon as it is accelerating worldwide. Increasing number of CNG driven vehicles around the world has jumped up from one million in 1996 to five million in 2006. CNG as a vehicle fuel is very popular to the end users because of its clean-burning properties and cost effective solution compared to other alternative fuels like diesel and gasoline. The use of CNG as a fuel reduces vehicular emission that is consisted of carbon monoxide (CO), hydrocarbons (HC), oxides of nitrogen ($NO_x$), carbon dioxide ($CO_2$) etc. This research highlights the characteristics of CNG vehicles, CNG arrangement in the vehicles, CNG fueling procedures and most importantly the environmental and economic factors that are highly considered as cost effective solution for the flexibility of using CNG in the automobiles.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.387-390
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• 2006

Conventional spinning, shear forming and flow forming techniques are being utilized increasingly due to the great flexibility provided for producing complicated parts, enabling customers to optimize designs and reduce weight and cost, all of which are vital, especially in automotive industries, space shuttle, a munitions industry. The deformation mechanism of conventional spinning and shear forming is studied in this paper through analysis. The forming loads of a spin formed dome in an Al launch vehicle fuel tank was studied analysis and a simple FE model to predict the forming loads of the dome was proposed. The analysis is carried out to study the effects of feed rates and thickness reduction on material flow.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.85.1-85.1
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• 2011

In this study, Grafoil$^{TM}$ which has comparable electric resistance and chemical stability but is flexible, fragile, and cheap material was adopted as bipolar plates for proton exchange membrane fuel cell(PEMFC) having only one straight line flow channel. Because of its flexibility, pressurizations of cell with various pressures showed different operating characteristics compared to ordinary graphite-used PEMFC. While performances of both cells decreased as these were pressurized, investigation of ohmic and faradaic resistance by electrochemical impedance measurement indicated different tendency of change. Ohmic resistance of graphite-used cell increased with increasing pressure, which is reversed in Grafoil$^{TM}$-used cell. It is speculated that effective chemical reaction area is decreased with increasing pressure in case of graphite-used one, but because of flexible property of Grafoil$^{TM}$, gas diffusion layer in Grafoil$^{TM}$-used cell was well-activated. Different rate of change of faradaic resistances in both cells support this supposition. However, although optimum point of pressurization is found, it is required to investigate other operating conditions because of low performance compared to graphite-used cell.

• Journal of the Korean Society of Combustion
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• v.22 no.1
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• pp.14-22
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• 2017

Co-firing of renewable fuel in coal fired boilers is an attractive option to mitigate $CO_2$ emissions, since it is a relatively low cost option for efficiently converting renewable fuel to electricity by adding biomass as partial substitute of coal. However, it would cause reducing plant efficiency and operational flexibility, and increasing operation and capital cost associated with handling and firing equipment of renewable fuels. The aim of this study is to investigate the effects of biomass co-firing on $CO_2$ emission and capital/operating cost. Wood pellet, PKS (palm kernel shell), EFB (empty fruit bunch) and sludge are considered as renewable fuels for co-firing with coal. Several approaches by the co-firing ratio are chosen from previous plant demonstrations and commercial co-firing operation, and they are evaluated and discussed for $CO_2$ reduction and cost estimation.

• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.1022-1028
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• 2024

A neutronics study of a supercritical CO₂-cooled fast reactor core for nuclear propulsion has been performed in this work. The thermal power of the reactor core is 30 MWth and a ceramic UO₂ fuel can be used to achieve a 20-year lifetime without refueling. In order to make a compact core with inherent safety features, the drum-type reactivity control system and folding-type shutdown system are adopted. In addition, we suggest a cold shutdown system using gadolinium as a spectral shift absorber (SSA) against flooding. Although there is a penalty of U-235 enrichment for the core embedded with the cold shutdown system, it effectively mitigates the increment of reactivity at the flooding of seawater. In this study, the neutronics analyses have been performed by using the continuous energy Monte Carlo Serpent 2 code with the evaluated nuclear data file ENDF/B-VII.1 Library. The supercritical CO₂-cooled fast reactor core is characterized in view of important safety parameters such as the reactivity worth of reactivity control systems, fuel temperature coefficient (FTC), coolant temperature coefficient (CTC), and coolant temperature-density coefficient (CTDC). We can say that the suggested core has inherent safety features and enough flexibility for load-following operation.