• Journal of Advanced Marine Engineering and Technology
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• v.39 no.2
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• pp.195-200
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• 2015

It is envisaged that the effect of increasingly stricter air emissions legislation implemented through IMO Annex VI and other local air quality controls, together with favorable financial conditions for the use of natural gas instead of liquid fuel oil as a bunker fuel, will see an increasing number of DF engine and single gas fuel engine applications to LNG carriers and other vessel types. As part of provision for the current international movements in the shipping industry to reduce GHG emission in air, new design concepts using natural gas as an alternative fuel source for propulsion of large commercial vessels, have been developed by shipyards and research institutes. In this study, an explosion analysis for a gas supply machinery room of LNG-fuelled container ship is presented. The gas fuel concept is employed for the high pressure ME-GI where a leakage in the natural gas double supply pipe to the engines is the subject of the present analysis. The consequences of a leak are simulated with computational fluid dynamics (CFD) tools to predict typical leak scenarios, gas cloud sizes and possible explosion pressures. In addition, capacity of the structure which is subject to explosion loads has been assessed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.8
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• pp.525-531
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• 2015

Driving sound is an effective element to promote the product identity of a vehicle by providing customers with attractive sound which reflects the concept of a vehicle. Recently, major automakers are focusing on the target sound setting so that the sound can represent the brand image as well as the unique concept of a vehicle. In this study, a new method of target setting for the driving sound will be introduced based on using formant filter and musical harmonics characteristics. In addition, a target sound suggested from this method will be realized and verified by using active noise control in vehicle.

• Nuclear Engineering and Technology
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• v.47 no.6
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• pp.678-699
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• 2015

Although the harsh space environment imposes many severe challenges to space pioneers, space exploration is a realistic and profitable goal for long-term humanity survival. One of the viable and promising options to overcome the harsh environment of space is nuclear propulsion. Particularly, the Nuclear Thermal Rocket (NTR) is a leading candidate for nearterm human missions to Mars and beyond due to its relatively high thrust and efficiency. Traditional NTR designs use typically high power reactors with fast or epithermal neutron spectrums to simplify core design and to maximize thrust. In parallel there are a series of new NTR designs with lower thrust and higher efficiency, designed to enhance mission versatility and safety through the use of redundant engines (when used in a clustered engine arrangement) for future commercialization. This paper proposes a new NTR design of the second design philosophy, Korea Advanced NUclear Thermal Engine Rocket (KANUTER), for future space applications. The KANUTER consists of an Extremely High Temperature Gas cooled Reactor (EHTGR) utilizing hydrogen propellant, a propulsion system, and an optional electricity generation system to provide propulsion as well as electricity generation. The innovatively small engine has the characteristics of high efficiency, being compact and lightweight, and bimodal capability. The notable characteristics result from the moderated EHTGR design, uniquely utilizing the integrated fuel element with an ultra heat-resistant carbide fuel, an efficient metal hydride moderator, protectively cooling channels and an individual pressure tube in an all-in-one package. The EHTGR can be bimodally operated in a propulsion mode of $100MW_{th}$ and an electricity generation mode of $100MW_{th}$, equipped with a dynamic energy conversion system. To investigate the design features of the new reactor and to estimate referential engine performance, a preliminary design study in terms of neutronics and thermohydraulics was carried out. The result indicates that the innovative design has great potential for high propellant efficiency and thrust-to-weight of engine ratio, compared with the existing NTR designs. However, the build-up of fission products in fuel has a significant impact on the bimodal operation of the moderated reactor such as xenon-induced dead time. This issue can be overcome by building in excess reactivity and control margin for the reactor design.

• Korean Journal of Cognitive Science
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• v.13 no.1
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• pp.1-11
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• 2002

In this paper, a test was performed to determine whether words in Anchor Text were appropriate as key words. As a result of the test. there were proper words of high weighting factor, while some others did not even appear in the text. therefore, were not appropriate as key words. In order to resolve this problem. a new method was proposed to extract key words. Using the proposed method, inappropriate key words can be removed so that new key words be set, and then, ranking becomes possible with the TFIDF value as a weighting factor of the key word. It was verified that the new method has higher accuracy compared to the previous methods.

• Journal of Information Technology Services
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• v.10 no.2
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• pp.119-139
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• 2011

The concept of ubiquitous is being applied on diverse industry fields as a new growth engine in Korea. With constructing u-City, new services which are called 'ubiquitous services' are developed actively. Even though there are active movement to develop u-service, there is no clear definition of what service can be defined as ubiquitous service. Given that this study proposes a u-service value classification framework focusing on services' characteristics. We conducted experts' group interviews to analyze new operating or developing services whether it can be ubiquitous. Study results show that some services are hard to be defined as u-service, so this study offers possible improvement alternative. The u-service value classification which offers clear definition of u-service can be used for the practitioners offering measurement framework of u-service level.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.6
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• pp.88-96
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• 2008

Currently, due to the serious world-wide air pollution by substances emitted from vehicles, emission control is enforced more firmly and it is expected that the regulation requirements for emission will become more severe. A new concept combustion technology that can reduce the NOx and PM in relation to combustion is urgently required. This study used a split injection method at a 4 cylinder common-rail direct injection diesel engine in order to apply the partially premixed charge compression ignition combustion method without significantly altering engine specifications And it is investigated that the effects of the injection ratio and SCV(swirl control valve) to emission characteristics. From these tests, soot(g) and NOx(g) emission could be reduced to 40% and 92% compared to base engine performance at specified engine driving conditions(6 points with weight factors) according to application of split injection and SCV(swirl control valve).

• Journal of Advanced Navigation Technology
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• v.24 no.5
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• pp.368-373
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• 2020

In order to systematically apply major technologies of the 4th Industrial Revolution to aerospace power development, an aerospace technology model is needed. The Propeller Model, which is an existing aerospace model, is a concept that operates a combination of altitude, speed, and distance, which are basic characteristics of aerospace. However, in the era of the 4th Industrial Revolution, a new model is needed because numerous technologies are used in convergence. In this paper, a jet engine model is proposed as a new aerospace technology model. Also, we propose a procedure for creating future aerospace weapon systems based on aerospace technology modeling, not on operational capability. The utilization of future battlefields and the study of the concept of advanced weapon systems in developed countries can create a new concept of weapon systems.

• Journal of Energy Engineering
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• v.20 no.3
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• pp.178-184
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• 2011

Compressed Air Energy Storage (CAES) is a combination of energy storage and generation by storing compressed air using off-peak power for generation at times of peak demand. In general, both charging and discharging of high-pressure vessel are unsteady processes, where the pressure is varying. These varying conditions result in low efficiencies of compression and expansion. In this paper, a new constant-pressure CAES system to overcome the current problem is proposed. An energy analysis of the system based on the concept of exergy was performed to evaluate the energy density and efficiency of the system in comparison with the conventional CAES system. The new constant-pressure CAES system combined with pumped hydro storage requires the smaller cavern with only half of the storage volume for variable-pressure CAES and has a higher efficiency of system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.4
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• pp.277-285
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• 2022

There has been significant increase in demand of launch opportunities from the small satellite sector that represents the new space era. Providing smallsat-dedicated launch service at an affordable price is a new business model many startup companies have pursued, which requires innovative solutions for cost reduction in combination of low cost components, volume production and optimized manufacturing. We set out a preceding study at KARI to develop a suite of critical and cost-cutting technologies in preparation for a two-staged small launch vehicle development, based on the liquid rocket engine technologies developed from the Nuri program in accordance with the 3^rd master plan for national space development. In this work, we introduce the concept of a two-staged small launch vehicle that aims to be innovative and cost competitive for small satellites, and describe mission design results including staging as well as overall vehicle configuration of the launch vehicle.

• Journal of the Korea Society for Simulation
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• v.17 no.2
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• pp.1-12
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• 2008

The major components of an engine are the cylinder block, cylinder head, crankshaft, connecting rod, and camshaft, which are more popularly known as the 5 C's. Thus, the engine shop usually consists of six sub-lines, including five machining lines and one assembly line. The flow line is the typical concept of the layout when the engineer designs the engine shop. This paper introduces a simulation study regarding the new crankshaft machining line in a Korean automotive factory. The major factors for designing the machining line are considered, and their effects on the system performance are evaluated with a three-dimensional(3D) simulation model that is developed with $QUEST^{(R)}$. The initial layout is analyzed using the simulation model, and we suggest some ideas for improvement.