• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.933-934
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• 2006

The present study examines the sintering behaviour and effect of manganese addition both mechanically-blended and mechanically alloyed on Cr-Mo low alloyed steels to enhance the mechanical properties. Mn sublimation during sintering provides some specific phenomena which facilitate the sintering of alloying elements with high oxygen affinity. First step is the optimization of milling time to attain a master alloy with 50% of Mn which is diluted in Fe-1.5Cr-0.2Mo water atomized prealloyed powder by normal mixing. These mixtures are pressed to a green density of $7.1g/cm^3$ and sintered at $1120^{\circ}C$ in $90N_2-10H_2$ atmosphere.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1999년도 춘계 학술대회논문집
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• pp.162-170
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• 1999

Numerical study has been peformed to develop a computer code for the design & optimal operating condition of SNCR(Selective Noncatalytic Reactor) for NOx reduction together with the analysis of the performance of vortex tube. Especially for the SNCR of the scale of industrial boiler, the required mixing and residence time of $NH_3$ solution was successfully tested numerically by the implementation of some baffle setups in a combustor. The introduction of interesting phenomena of vortex tube and similar system is made together with a theoretical hypothesis and simple cold flow simulation for the flow field analysis.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.460-465
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• 2004

ESPR project started in 1999 with METI and NEDO support as five-years program in order to develop necessary technologies for the next-generation SST engine. In ESPR program, jet noise reduction technologies are focused as environmentally compatible technologies, which are critical to realize next-generation SST. In designing a lobed mixer nozzle which is a jet noise suppression system, there are many difficulties to understand the detailed flow phenomena occurred in the system because of its complexity. Large Eddy Simulation (LES) was applied to the lobed mixer nozzle flow analysis in ESPR project. The results demonstrated that LES approach was capable of predicting mixing characteristics of a complicated flow.

• E2M - 전기 전자와 첨단 소재
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• 제8권6호
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• pp.759-767
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• 1995

This paper examines the electrical properties according to a curing time and a corona degradation in epoxy composites which are used for transformers. To consider these phenomena, the electrets were formed by appling high voltages to five kinds of specimens designed according to a constant mixing rate and then TSC(Thermally Stimulated Current) values at the temperature range of -160-200[>$^{\circ}C$] were measured from a series of experiments. The behaviour of carrier and its possible origins in epoxy composites were studied. Various effects of curing time and electric field on epoxy composites were also investigated.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.602-606
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• 2006

The electrostatic is well known phenomena. The fires and explosions caused by electrostatic occur often in the coating mechanical system. This paper presents various cases of electrostatic hazards, reasons why electrostatic hazards are happened, and methods for preventing electrostatic hazards. Generally the electrostatic can be lead to corona discharging, streaming electrification, and impinging electrification in the coating process. Corona discharging happens at electrostatic spray gun with 70 kV. Streaming electrification occurs at mixing process between paint and thinner, and transportation process with thinner. Impinging electrification is shown when the thinner are sprayed to drums. For the purpose of preventing the electrostatic discharge and damage, conductors should be ground, surface electric potential of should be decreased in using electrostatic shielding and ground, and flow of thinner should be controlled acceptable velocity.

• 한국가시화정보학회지
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• 제17권2호
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• pp.67-72
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• 2019

In this study, we investigate the non-reacting and reacting performance of single nozzle for post H class gas turbine by using commercial CFD tool, CONVERGE, based on adaptive mesh refinement. By varying swirl number and mixing length of base nozzle design. Through the numerical analysis, basic phenomena can be well described with respect to fuel concentration for non-reacting flow, temperature distribution, velocity vector and combustion outlet temperature distribution for reacting flow. However, there are rooms for improvements in model accuracy by comparing test results. Comparison between numerical analysis are planning for further study.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(2)
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• pp.199-204
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• 1996

In the present the mean temperature and the temperature fluctuation of non-isothermal parallel liquid sodium jets were measured and analyzed changing the temperature difference and mean velocity of the hot and cold sodium. The sampling frequency and sampling time were 420Hz and three seconds, respectively. The wave-form characteristics were discussed in regard to the peak-to-peak amplitudes and the periods provided by a wave analysis. And also the correlations of the temperature fluctuation in rms value and the peak amplitude are derived. The overall mean accuracy ratios of the correlations are 1.07 and 1.08 with a standard deviation of 0.17 and 0.15, respectively.

• 수완나부미
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• 제7권2호
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• pp.57-78
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• 2015

Southeast Asia has been a showcase for democratic transitions in the past 30 years. This paper proposes a conceptual lens for studying political shifts in the Southeast Asian region. The argumentative storyline follows two fundamental propositions about democratic transitions. My first proposition is that during democratic transitions, human phenomena arise on nested analytical layers namely the global arena, the state, prodemocracy movements, and individuals. Each layer is conventionally studied by international relations, political science, sociology, and psychology respectively. I propose a multidisciplinary lens that transverses all these analytical layers. A second proposition is that during political shifts, social conditions are historically-situated. Historicity is anchored on stages of democratization, namely the authoritarian regime, toppling the regime, power shift, state building, and nation building. This paper describes a 4 × 5 matrix (analytical layer × historical stage) that may guide a regional agenda on the empirical study of democratic transitions in the Southeast Asian region. It likewise gives examples of research findings in Philippine-based studies that have already begun to provide empirical data about segments of this research matrix.

• 대한화학회지
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• 제48권4호
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• pp.399-413
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• 2004

이 연구에서는 용해와 관련된 현상에 대해서 초등학교 학생에서부터 대학생에 이르기까지 학교급에 따라 학생들이 가지는 개념유형을 알아보고, 초${\cdot}$중등학교 교사들의 용해 현상에 대한 지도 실태를 알아보았다. 연구 결과, 초등학생 때 형성된 구멍 개념에 의한 용해 현상의 이해가 고등학생 때까지 유지되고 있었으며, 인력 개념에 의해 용해 현상을 학습하는 시기인 고등학교 2, 3학년과 대학생들은 인력 개념으로 용해 현상을 이해하는 비율이 상대적으로 높게 나타났다. 그러나 용해 현상을 설명할 때는 초등학생에서부터 대학생에 이르기까지 많은 학생들이 인력 개념보다는 구멍 개념을 선호하는 것으로 나타났고, 개념의 이해와 설명에 커다란 차이를 나타냄으로써 학생들의 용해 현상에 대한 이해 정도가 전반적으로 낮음을 알 수 있었다. 교사들의 설문 응답 분석 결과, 초등학교 교사의 90% 정도가 소금이 물에 녹는 현상을 콩 사이로 좁쌀이 들어가는 것과 같은 현상으로 이해하고 있었으며, 실제 학생들에게 소금이 물에 녹는 현상을 콩 사이로 좁쌀이 들어가는 모형을 이용하여 지도한다고 응답하였다. 중등학교 교사들 역시 약 절반 정도는 용해 현상을 구멍 개념으로 이해하고 있었으며, 인력 개념으로 바르게 이해하고 있는 교사는 20% 정도에 지나지 않았다. 또한, 인력 개념으로 이해하고 있는 교사들도 실제 학생들을 지도할 때는 구멍 개념으로 설명하는 경우가 많아 교사들의 개념 이해와 지도에는 차이가 있음을 알 수 있었다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권6호
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• pp.273-284
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• 2002

In this paper, computer simulations of the physical Phenomena occurring in the arc region before and after current zero were carried out to evaluate the dielectric recovery characteristics of two types of double-flow nozzles. A commercial CFD Program "PHOENICS" is used for the simulation and the user-coded subroutines to consider the arcing phenomena were added to this program by the authors. The computed results were verified by the comparison with the test results presented by the research group of BBC. In order to investigate the state of the arc region after current zero, the simulation was carried out with four steps. They are cold gas flow analysis, steady state arc simulation, transient arc simulation before current zero, transient hot gas flow simulation after current zero. The semi-experimental arc radiation model is adapted to consider the radiation energy transport and Prandtl′s mixing length model is employed as the turbulence model. The electric field and the magnetic field were calculated with the same grid structure used for the simulation of the flow field. The streamer criterion was introduced to evaluate the dielectric recovery characteristics after current zero. Compared with the results obtained by assuming the current zero state in the former studies, it has been found that the results obtained by considering the state before current zerowere more accurate.