• Korean Journal of Cognitive Science
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• v.11 no.3_4
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• pp.73-81
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• 2000

This study was conducted to investigate some characteristics of representation of category knowledge and script knowledge. Using primed lexical decision task with higher level primers in the representation structure, Experiment 1 examined the interaction effects between knowledge type and concept typicality. It was found that the concept typicality has some effects in category representation, while it has no significant effect in script representation. In Experiment 2, primers of the lower hierarchy in the representation structure were employed. The results showed that the main effect of knowledge type was significant: the response time for category knowledge was faster than that for script knowledge. Typicality effect did not show in this experiment. The results of t the two experiments suggest that category knowledge is represented in hierarchy and typicality. while script knowledge may lack in that characteristics. Other aspects of the differences in characteristics of category- and script- knowledge representation were discussed,

• Korean Journal of Cognitive Science
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• v.15 no.1
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• pp.35-41
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• 2004

The letter delay task using monosyllabic words has been employed in order to investigate whether Korean word is processed by the phonological route, and to investigate which stage this phonological information affects word recognition. Two main conditions were delaying a sounding letter( $\rightarrow$향), and delaying a silent letter( $\rightarrow$양). Experiment 1 was the naming task with the SOAs of 150㎳ and 250㎳ in order to investigate whether the phonological information affects the early stages, or the later stages of word recognition. The results showed that the interaction between the phonological value condition and the presence/absence of the prime was significant under the 150㎳ SOA, but not under 250㎳ SOA. Experiment 2 was conducted in order to generalize the results of Experiment 1 in the lexical decision task. The results showed the similar pattern as the Experiment 1. These experiments indicate that Korean words are processed by the phonological route, and the phonological information plays roles in the early stages of word recognition.

• Journal of Energy Engineering
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• v.18 no.3
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• pp.163-168
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• 2009

This paper describes the homogeneous charge compression ignition (HCCI) engine for a new concept. HCCI engines are being considered as a future alternative for diesel and gasoline engines. HCCI engines have the potential for high indicated thermal efficiency under part load and very low NOx emissions. The objective of this paper is to clear the effects of exhaust gas recirculation (EGR) rate on the HCCI. For this purpose, a 4-cylinder, compression ignition engine was converted into a HCCI engine This work has been run with propane and butane fuels at a constant speed.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.3
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• pp.1-8
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• 2008

We present a model for simulating high energy laser heating of metal for ignition of energetic materials. The model considers effect of ablation of steel plate with long laser pulses and continuous lasers of several kilowatts and the thermal response of well-characterized high explosives for ignition. Since there is enough time for the thermal wave to propagate into the target and to create a region of hot spot in the high explosives, electron thermal diffusion of ultra-short (femto- and pico-second) lasing is ignored; instead, heat diffusion of absorbed laser energy in the solid target is modeled with thermal decomposition kinetic models of high explosives. Numerically simulated pulsed-laser heating of solid target and thermal explosion of RDX, TATB, and HMX are compared to experimental results. The experimental and numerical results are in good agreement.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.451-455
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• 2017

The reactive Eulerian-Lagrangian code is utilized to simulate combustion of ZPP/THPP in a closed vessel. In the paper, ignition delay of THPP is mainly studied since ZPP and THPP are isolated by a boron nitride wall. Only a numerical case study is conducted as experimental observation is inaccessible. Results showed THPP ignition delay affects initial shock strength thus not only the first peak become weak, but also the frequency of a pressure oscillation is slowed.

• Fire Science and Engineering
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• v.27 no.6
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• pp.50-56
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• 2013

The radiation effects on the auto-ignition and extinction characteristics of a non-premixed fuel-air counterflow field were numerically investigated. A detailed reaction mechanism of GRI-v3.0 was used for the calculation of chemical reactions and the optically-thin radiation model was adopted in the simulations. The flame-controlling continuation method was also used in the simulation to predict the auto-ignition point and extinction limits precisely. As a result, it was found that the maximum H radical concentration, $(Y_H)_{max}$, rather than the maximum temperature was suitable to understand the ignition and extinction behaviors. S-, C- and O-curves, which were well known from the previous theory, were identified by investigating the $(Y_H)_{max}$. The radiative heat loss fraction ($f_r$) and spatially-integrated heat release rate (IHRR) were introduced to grasp each extinction mechanism. It was also found that the $f_r$ was the highest at the radiative extinction limit. At the flame stretch extinction limit, the flame was extinguished due to the conductive heat loss which attributed to the high strain rate although the heat release rate was the highest. The radiation affected on the radiative extinction limit and auto-ignition point considerably, however the effect on the flame stretch extinction limit was negligible. A stable flame regime defined by the region between each extinction limit became wide with increasing the fuel temperature.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.1
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• pp.175-179
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• 1992

Generally speaking, natural gas possesses several characteristics that make it desirable as an engine fuel : for example (1) lower production cost, (2) abundant commodity and (3) cleaner energy source than gasoline. Due to the physical characteristics of natural gas, the volumetric efficiency and flame speed of a natural gas engine are lower than those of a gasoline engine, which results in a power loss of 10-20% when compared to a convensional gasoline engine. This paper describes the results of a research to improve the performance of a natural gas engine through the modification and controls of air/fuel ratio, spark timing advance and supercharging effect by forced air supply method.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.3
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• pp.569-577
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• 1992

The effect of combustion promotion in a constant volume combustion chamber with sub- chamber located in the vicinity of spark plug, was analyzed for variables such as sub- chamber volume and diameter of orifice, and was also compared and evaluated with that of the chamber with sub-chamber which spark plug was located in the sub-chamber. Consequently, it was shown that decrease of duration of combustion in the latter case was larger than in the former case, but comparing by rate of overall combustion promotion that duration of combustion and pressure were both considered, the optimum configuration factor and the effect of combustion promotion were almost same in both cases.

• Proceedings of the Korea Society of Design Studies Conference
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• 2003.05a
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• pp.238-239
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• 2003

• Journal of Digital Convergence
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• v.18 no.5
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• pp.411-416
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• 2020

This study is an empirical study to see if the existing media effects have an effect on the perception of the audience in the media such as newspapers, TV, movies, etc., and whether the viewing of YouTube, an internet-based new media without gatekeeper, can affect the perception of the audience. For this study, 76 university students were divided into two groups, one group was asked to watch YouTube videos about no-buy campaign of Japanese products, and the other group was asked to watch short films for four weeks each, and then the perception and attitude of the issue were measured and analyzed through a survey. The results of the analysis showed that the audience who watched YouTube videos thought that no-buy campaign was more important than the audience who did not watch YouTube videos, and that they would participate more actively in no-buy campaign. The results of this study can be meaningful in that it confirmed the effects of the agenda setting effect and the priming effect of YouTube. It is expected that the theory of the media effect of YouTube will be established as the study on the audience effect in various fields such as politics, economy, society, culture of YouTube continues.