• 한국연소학회:학술대회논문집
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• 2001.06a
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• pp.187-192
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• 2001

A homogeneous premixed charge compression ignition engine is experimentally investigated for the reduction of exhaust emissions in diesel engines. In this study, the premixed fuel is injected into the intake manifold to form homogeneous pre-mixture in the combustion chamber and then this pre-mixture is ignited by small amount of diesel fuel directly injected into the cylinder. In the premixed charge compression ignition engine, NOx and smoke concentration of the exhaust emissions were reduced simultaneously as compared with the conventional diesel engine. But HC and CO emissions were increased with the increase of premixed ratio. The combustion characteristics of premixed charged diesel engine such as the power output, the rate of heat release, and the other characteristics are discussed.

• English Language & Literature Teaching
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• v.16 no.4
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• pp.321-346
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• 2010

This study was performed to develop a task-based English lesson plan. The study reviewed the background theories needed to accomplish the study purpose; types of learning, current trends in English teaching, and the task-based teaching. A frame for the task-based English lesson was developed as the result of this study. An actual task-based lesson plan was made after the frame for the task-based English lesson. The author presented task-based English lesson plans at English education conferences, and applied them to pre-teacher training and in-service trainings for English teachers. It is concluded that the task-based English lesson plan was very effective in enhancing English communicative competence and that the pre-teachers and teachers were satisfied with the lesson plans. It is hoped that more teaching material will be developed based on this task-based English lesson plan.

• Korean Journal of Child Studies
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• v.33 no.5
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• pp.221-246
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• 2012

This study was conducted in order to develop an aptitude test for child care teachers (ATCCT) and to analyze it in terms of both validity and reliability. The main participants in this study consisted of 710 pre-service child care teachers. The results of factor analysis identified 7 factors and 56 items which were selected from 121 items in the original scale. The seven factors were as follows; interpersonal relationship management abilities, receptiveness and responsiveness to children, creativity and personal development, the ability to form close relationships with children, the ability to supervise child safety, the sense of duty, and positive emotions. The four factors were related to social relationship. Criterion-related validity was established by using correlations between the ATCCT and the TSES (Teacher Self-efficacy Scale). The internal consistency was found to be relatively high (Cronbach's ${\alpha}$ = .94) and test-retest reliability was also established (r = .53). In addition, there were differences among pre-service child care teacher groups according to both relative levels of education and courses taught.

• Korea journal of population studies
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• v.12 no.2
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• pp.56-68
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• 1989

The methodology in historical demography comprises the three core areas the family reconstitution method at the Institut National d' Ftudes Demographiques(I.N.E.D), the back projection at the Cambridge Group for the History of PopuJation and Social Struc-ture(HPSS). and the household-pattern analysis at the Cambridge Group and at the California Institute of Technology. The paper presents an outline of the family reconstitu-tion method and discusses the problems, both theoretical and methodological, arising from the problematic back projection vis-a-vis the usual inverse projection developed by Ronald D. Lee at Berkeley. Recent developments in the tield of the generalized inverse projection method designed 10 supplement the defects in the back projection and the inverse projection are presented. and for ease of explanation of the parish register data for the family reconstitution form (FRE). pre-modern Korean household register data are presented along with the parish register data of England and Wales that constitute the backbone of historical demography in pre-modern Europe. Possibilities of exploring the household pattern analysis method based on the Laslett-Hammel classification scheme for the mid-eighteenth-century Korean household register data are suggested.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.13 no.2
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• pp.73-86
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• 2009

The problem of thermal stability of an exothermic reactive viscous fluid between two parallel walls in the plane Poiseuille and Couette flow configurations is investigated for different thermal boundary conditions. Neglecting reactant consumption, the closed-form solutions obtained from the momentum equation was inserted into the energy equation due to dissipative effect of viscosity. The resulting energy equation was analyzed for criticality using the variational method technique. The problem is characterized by two parameters: the Nusselt number(N) and the dynamic parameter($\Lambda$). We observed that the thermal and dynamical boundary conditions of the wall have led to a significant departure from known results. The influence of the variable pre-exponential factor, due to the numerical exponent m, also give further insight into the behavior of the system and the results expressed graphically and in tabular forms.

• Journal of The Korean Astronomical Society
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• v.40 no.4
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• pp.161-164
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• 2007

We calculate the evolution of multiple supernova (SN) explosions inside a pre-exiting bubble blown up by winds from massive stars, using one-dimensional hydrodynamic simulations including radiative cooling and thermal conduction effects. First, the development of the wind bubble driven by collective winds from multiple stars during the main sequence is calculated. Then multiple SN explosion is loaded at the center of the bubble and the evolution of the SN remnant is followed for $10^6$ years. We find the size and mass of the SN-driven shell depend on the structure of the pre-existing wind bubble as well as the total SN explosion energy. Most of the explosion energy is lost via radiative cooling, while about 10% remains as kinetic energy and less than 10% as thermal energy of the expanding bubble shell. Thus the photoionization and heating by diffuse radiation emitted by the shock heated gas is the most dominant form of SN feedback into the surrounding interstellar medium.

• Journal of Surface Science and Engineering
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• v.35 no.5
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• pp.279-288
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• 2002

Zinc phosphating for cold forming of steel was studied with emphasis on decreasing phosphating temperature. To lower phosphating temperature, some techniques, such as adding Cu ion into bath, using activator in the form of pre-dip, and aeration in bath, instead of using conventional accelerator, namely oxidizing agent, have been tried. It was revealed that phosphating, leading to coatings of Improved uniformity and fine crystal size, can be carried out using above techniques at lower temperature ($55^{\circ}C$) compared to conventional phosphating temperature ($80 ~ 90^{\circ}C$ ). Under present condition, it was seen that optimum concentrations of Cu ion in phosphating bath and activator in pre-dip are 0.015% (w/w) and 2.0 g/1, respectively. The coating weight was within the range of 15 ~ 20 g/$\m^2$. When lubricant was applied into phosphating coatings, the amount of lubricating component (total soap) was found to be 6 ~ 10 g/$\m^2$ and the lubricated panel revealed excellent lubricating properties.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.2 no.5
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• pp.222-238
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• 2008

In this paper, the random key pre-distribution scheme introduced in ACM CCS'02 by Eschenauer and Gligor is reexamined, and a generalized form of key establishment is introduced. As the communication overhead is one of the most critical constraints of any successful protocol design, we introduce an alternative scheme in which the connectivity is maintained at the same level as in the original work, while the communication overhead is reduced by about 40% of the original overhead, for various carefully chosen parameters. The main modification relies on the use of a two-level key pool design and two round assignment/key establishment phases. Further analysis demonstrates the efficiency of our modification.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.2
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• pp.66-72
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• 2002

A premixed charge compression ignition engine is experimentally investigated for the reduction of NOx and smoke emissions from diesel engines. In this study, the premixed fuel is injected into the intake manifold to form homogeneous pre-mixture in the combustion chamber and then this pre-mixture is ignited by small amount of diesel fuel directly injected into the cylinder. In the premixed charge compression ignition engine, NOx and smoke concentrations of the exhaust emissions were reduced simultaneously as compared with the conventional diesel engine. But HC emission was increased with the increase of premixed ratio. Also, when EGR system was applied to the PCCI diesel engine, the effect of EGR rate on the combustion characteristics and the exhaust gas emissions was discussed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.6
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• pp.1619-1626
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• 1998

In this paper, we made researches into considerations for the numbering plan for IMT-2000 that seems to be a unit system integrating cellular, satellite, PCS. The purposes of the numbering plane for IMT-2000 ARE SIMILAR TO IMT-2000 evolution form:constructing the numbering plane centering around UPT as a PRE-FPLMTS from and futhermore, adding terminal mobility to IMT-2000. For this paper, we established three numbering plans for IMT-2000 that accepts various considerations.