• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.1882-1887
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• 2007

In the present experimental study, the effect of interfacial tensions on pressure drop of air-water two-phase flow in round mini-channels was investigated. A glass (highly wettable) tube and a Teflon (poorly wettable) tube, both in 350 mm length but 1.8 mm and 1.59 mm in inner diameters each, were used for the tests. All the experiments were performed only in the plug flow regime, confirmed by visualization. In the glass tube, the gas plugs were surrounded by the liquid film along the inner periphery. On the other hand, the inner wall remained dry at the gas portion in the Teflon tube. The pressure drop of the plug flow in the Teflon tube without the liquid film) appeared much larger than in the glass tube (with the liquid film) due to dissipation of energy by movement of the wetting lines. In this paper, various correlations on the two-phase pressure drop of plug flows were compared and a modified correlation was proposed, taking account of the surface wettability.

• Nuclear Engineering and Technology
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• 제41권7호
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• pp.929-944
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• 2009

The present study is concerned with the extension of the Effective Convectivity Model (ECM) to the phase-change problem to simulate the dynamics of the melt pool formation in a Light Water Reactor (LWR) lower plenum during hypothetical severe accident progression. The ECM uses heat transfer characteristic velocities to describe turbulent natural convection of a melt pool. The simple approach of the ECM method allows implementing different models of the characteristic velocity in a mushy zone for non-eutectic mixtures. The Phase-change ECM (PECM) was examined using three models of the characteristic velocities in a mushy zone and its performance was compared. The PECM was validated using a dual-tier approach, namely validations against existing experimental data (the SIMECO experiment) and validations against results obtained from Computational Fluid Dynamics (CFD) simulations. The results predicted by the PECM implementing the linear dependency of mushy-zone characteristic velocity on fluid fraction are well agreed with the experimental correlation and CFD simulation results. The PECM was applied to simulation of melt pool formation heat transfer in a Pressurized Water Reactor (PWR) and Boiling Water Reactor (BWR) lower plenum. The study suggests that the PECM is an adequate and effective tool to compute the dynamics of core melt pool formation.

• 전력전자학회논문지
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• 제25권1호
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• pp.13-20
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• 2020

Accurate parameters based on equivalent circuit are required for high-performance field-oriented control in a three-phase induction motor. In a normal case, stator resistance can be accurately measured using a measuring equipment. Except for stator resistance, all machine parameters on the equivalent circuit should be estimated with particular algorithms. In the viewpoint of traditional regions, the parameters of an induction motor can be identified through the no-load and standstill test. This study proposes an identification method that uses the d-axis model of the induction motor in a stationary frame with the predefined information on stator resistance. Mutual inductance is estimated on the rotational dq coordination similar to that in the traditional no-load experiment test. The leakage inductance and rotor resistance can be estimated simply by applying different voltages and frequencies in the d-axis model of the induction motor. The proposed method is verified through simulation and experimental results.

• 자원환경지질
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• 제4권2호
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• pp.59-75
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• 1971

Orogenic cycle is closely related with sedimentary cycle, and a sedimentary cycle involves the birth, development and disappearance of a sedimentary basin. Paleontological studies have indicated that birth or disappearance of sedimentary basins of separated regions frequently coincided in time. In this paper, the writer presents his assumption on the East Asian analogy of the Hercynian orogenic cycle in accord to the above mentioned generalities. Previous studies, including mine have a corollary that Korea and Southern China, which had been uplifted by the Caledonian movement, changed into low-lying region with subsiding areas in the Givetian time. The writer, thus, thinks that the Hercynian orogenic cycle started in Givetian, and that the Mongolian geosyncline in China, the Gangweon Basin in Korea and the Honshu geosyncline in Japan disappeared in the Ladinian. The writer, therefore, thinks that the Ladinian marks the end of the Hercynian orogenic cycle, but this assumption will have to be rechecked in consideration with the Alpine orogenic cycle. The Late Namurian-Early Bashkirian time, the dividing period between the early and late Hercynian orogenic cycle, is thought to correspond the time of the Hongjeom Series deposition. The writer is also of the view that the Akiyoshi orogenic cycle(T. Kobayashi) corresponds the late Hercynian phase, and that the Abenian movements(M. Minato) corresponds to the range from the late Caledonian phase to the former part of late Hercynian phase.

• Archives of Pharmacal Research
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• 제28권12호
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• pp.1400-1404
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• 2005

The aim of the present study was to develop the aqueous parenteral formulation containing propofol using o/w microemulsion systems. Propofol itself was chosen as the oil phase and its content was fixed to 1$\%$, w/w. Pseudoternary phase diagrams were constructed to obtain the concentration range of surfactant and cosurfacatnt and the optimum ratio between them for microemulsion formation. Consequently, the suitability of the chosen microemulsion system as a parenteral formulation was evaluated from the stability and hemolysis tests on that. Among the surfactants and cosurfactants screened, the mixture of Solutol HS 15-ethyl alcohol (5/1) showed the largest o/w mocroemulsion region in the phase diagram. When 1 $\%$ (w/w) of propofol was solubilized with 8$\%$ (w/w) of Solutol $HS^{circledR}$??? 15-ethyl alcohol (5/1), the average droplet size (150 nm) and the content of propofol in the systems were not significantly changed at 40$^{circ}C$ for 8 weeks. The hemolysis test showed that this formulation was nontoxic to red blood cells. In conclusion, propofol was successfully solubilized with the o/w microemulsion systems.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 추계학술대회 논문집
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• pp.49-53
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• 1996

Crystal structures of N $a_{x}$W $O_3$(0.5$\leq$x$\leq$1.0) were investigated. Transmission electron microscopy (TEM) studies indicate that there is an ordering of sodium ions when x=0.75. The direction of ordering is [110] and the wavelength of ordering is twice of the interplanar distance of (110) plane. It has been confirmed that a superlattice containing eight N $a_{0.75}$W $O_3$is the unit cell of ordered structure. In this unit cell, Na sites at (100) and ($\frac{1}{2}$$\frac{1}{2}$$\frac{1}{2}$) are vacant. The ordered phase was preserved after the annealing at $600^{\circ}C$ in the air. In reduced N $a_{x}$W $O_3$with x=0.5 and 1.0, extra phases were found to coexist with the partially ordered perovskite phase. After annealing at $600^{\circ}C$, theses phases were transformed into the phases found in calcined specimens.ens.s.

• International Journal of Advanced Culture Technology
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• 제10권3호
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• pp.184-191
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• 2022

Unity Painting is a concept that the researcher put forward to locate his own creative style in his creation. Unity Painting, with a clue of reflecting the characteristics of contemporary oriental visual culture, combines the contemporary painting features of a variety of western painting languages. It aims to link the painting system formed in the context of oriental culture with the world's contemporary art and try to present a new contemporary painting with oriental genes. According to the Chinese literature, the researcher sorted out the five main colors (五正色), ten colors for Heavenly Stems (十天干色彩), five intermediate colors (五间色), and five colors as the expression of the Chi of Thriving and Fading and the Chi of Birth and Death, and deduced the summary and stipulation of the color of yin-yang and five elements under the concept of Unity Painting. Based on this, the researcher drew the color-phase and its variation stipulation diagram of ten colors for Heavenly Stems, the orientation of Heavenly Stems (天干方位), color-phase variation diagram (色相变化图), as well as the stipulation system diagram of the five elements (五行), Heavenly Stems and Earthly Branches (干支), energy, time and colors. Through the research and collation of the literature, the researcher took the stipulated five elements color (五行色彩) as the basis of the color concept of creation to complete the work. This paper discusses how to find the starting point of contemporary art creation in the context of traditional oriental culture, sorts out the practical creation logic, and provides ideas for subsequent researchers, with a view to better establishing the identity of the creator and providing research significance and value in the context of the study of oriental art.

• 유기물자원화
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• 제25권2호
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• pp.49-57
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• 2017

한국인이 가장 좋아하는 음식인 김치의 소비가 증가하면서 김치공장부산물(KWF)도 증가하였다. 본 연구는 KWF를 처리한 아주까리유박의 퇴비화에서 이화학적 특성의 변화와 시비에 따른 상추의 생육을 평가하였다. 처리구는 아주까리유박(60%)과 톱밥(40%)을 혼합한 대조구, KWF 35% 처리구(K-1), KWF 50% 처리구(K-2) 및 KWF 65% 처리구(K-3)로 설정하였다. KWF처리 후 pH, 유기물 및 미생물상은 처리구별 차이를 나타내지 않았으며, 대조구와 비교할 때, KWF처리구의 질소함량은 증가하였고, 유기물대 질소비는 감소하였다. 퇴비화 종료 후 KWF처리구는 비료공정규격에 적합하였으나 K-3의 염분은 1.91%로 다른 처리구들 보다 높았다. K-1처리구와 K-3처리구에서 상추의 생물중과 건물중은 대조구와 비슷하였다. 이러한 결과들은 김치공장 부산물이 퇴비원료로 사용이 가능하지만 작물에 안전한 아주까리유박퇴비의 생산을 위해서는 35% 이하로 사용하는 것이 적절함을 나타내었다.

• 청정기술
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• 제12권2호
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• pp.101-106
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• 2006

본 연구에서는 수산화물 전구체로부터 HT-$LiCoO_2$ 분말을 제조하였다. 사용된 $Co(OH)_2$는 ${\alpha}$상 및, 또는 ${\beta}$ 상의 수산화물이며 여러 조건에서 침전법으로 제조되었다. 제조시에 $[OH^-]/[CO^{2+}]$ 농도 비와 숙성시간을 조절함으로써 원하는 특성을 지닌 $Co(OH)_2$ 제조가 가능하였다. 침전법으로 합성한 $Co(OH)_2$와 LiOH를 메탄올 수용액을 이용하여 혼합한 후 이어서 증발, 건조 그리고 숙성 조작에 의하여 HT-$LiCoO_2$의 전구체를 합성하였다. 숙성기간에 tailor-made ${\beta}$-phase $Co(OH)_2$는 CoOOH로 변환되면서 고용체를 형성한다. 이 같은 결과로 HT-$LiCoO_2$가 낮은 온도($600^{\circ}C$), 짧은 시간(10분)에 합성이 가능하게 된다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제17권3호
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• pp.411-424
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• 2017

An all-digital delay-locked loop (DLL) for a mobile memory interface, which runs at 0.11-2.5 GHz with a phase-shift capability of $180^{\circ}$, has two internal DLLs: a global DLL which uses a time-to-digital converter to assist fast locking, and shuts down after locking to save power; and a local DLL which uses a phase detector with an adaptive phase sampling window (WPD) to reduce jitter accumulation. The WPD in the local DLL adjusts the width of its sampling window adaptively to control the loop bandwidth, thus reducing jitter induced by UP/DN dithering, input clock jitter, and supply/ground noise. Implemented in a 65 nm CMOS process, the DLL operates over 0.11-2.5 GHz. It locks within 6 clock cycles at 0.11 GHz, and within 17 clock cycles at 2.5 GHz. At 2.5 GHz, the integrated jitter is $954fs_{rms}$, and the long-term jitter is $2.33ps_{rms}/23.10ps_{pp}$. The ratio of the RMS jitter at the output to that at the input is about 1.17 at 2.5 GHz, when the sampling window of the WPD is being adjusted adaptively. The DLL consumes 1.77 mW/GHz and occupies $0.075mm^2$.