알케인류 상변화물질의 열적 특성 해석

崔恩洙,鄭東柱 明知大學校 産業技術硏究所 2003 産業技術硏究所論文集 Vol.22 No.-

Abstract - The objective of the present study is to reveal thermal characteristics of various alkane phase-change-material which have high latent heat during phase change from solid to liquid. In order to analysis thermal characteristics of various phase-change-material, phase-change temperature and energy of various phase-change-material were measured by using differential scanning calorimeter. The phase-change-material slurries which are used in this study were paraffin particle, microcapsulated octadecane and microcapsulated lauric acid. The heating rate of differential scanning calorimeter and the size of phase-change-material were changed during phase-change temperature and energy measurement.

A Single Element Phase Change Memory

LEE, Sang-Hyeon,KIM, Moonkyung,CHEONG, Byung-ki,KIM, Jooyeon,LEE, Jo-Won,TIWARI, Sandip The Institute of Electronics, Information and Comm 2011 IEICE transactions on electronics Vol.94e.c No.5

<P>We report a fast single element nonvolatile memory that employs amorphous to crystalline phase change. Temperature change is induced within a single electronic element in confined geometry transistors to cause the phase change. This novel phase change memory (PCM) operates without the need for charge transport through insulator films for charge storage in a floating gate. GeSbTe (GST) was employed to the phase change material undergoing transition below 200°C. The phase change, causing conductivity and permittivity change of the film, results in the threshold voltage shift observed in transistors and capacitors.</P>

상경계면에서의 열유속 정보를 활용하는 상변화 모델을 이용한 상변 화열전달 수치해석 연구

손종현(Jong Hyeon Son),박일석(Il Seouk Park) 대한기계학회 2019 대한기계학회 춘추학술대회 Vol.2019 No.11

A phase-change is a phenomenon in which the phase of a material is changed through the mass and heat transfer caused by the latent heat at the phase interface. But there are various difficulties in performing numerical analysis using the discrete grid system because of sudden changes in thermodynamic properties and complex convective flows. In this study, the numerical phase-change model based on the finite volume method using the thermal information around the phase interface is developed and the phase-change heat transfer problems are numerically investigated. To validate the new phase-change model, the one-dimensional Stefan condensation, the two-dimensional infinite corner solidification and the bubble growth problems that has the exact solution are solved. The results of temperature changed, and the interface shape obtained from the present phase-change model are more consistent with the exact solution than that of the existing phase-change models.

이터븀 첨가된 광섬유 기반 위상 천이 간섭계의 위상 제어 조건 분석

김은선,강희원,마혜진,최은서 한국물리학회 2020 새물리 Vol.70 No.9

In this research, the optimum phase control condition was analyzed by calculating the change in the nonlinear refractive index induced in a ytterbium-doped optical fiber by using 980-nm pump light. Simulations were performed to obtain the characteristic of the refractive index change while varying the optical power of the pump light and the length of the optical fiber. By investigating this characteristic, we were able to determine the optimal optical fiber length at a specific pump light power and calculate the amount of phase change. As a result of the simulation on the 10-cm-long ytterbium-doped optical fiber, the pump light power required to induce the rad phase change of the 1330-nm signal light was calculated to be 8.5 mW. The pump light power applied to induce a rad phase change in the fiber optic Michelson interferometer experiment was 9.5 mW, which was very similar to the simulation result. Thus, we confirmed that the phase control required by the phase-shifting interferometer could be sufficiently achieved by using a low pump-light power and an optical fiber of several tens of cm in length. 본 논문에서는 980 nm 펌프광에 의해 이터븀 도핑된 광섬유에서 유도되는 비선형 굴절률의 변화를계산하여 최적 위상 제어 조건을 분석하였다. 펌프광의 광출력과 광섬유의 길이를 변화시키면서 굴절률변화의 특성에 대한 시뮬레이션을 수행하였다. 이 특성을 조사함으로써 특정 광출력에서의 최적 광섬유길이를 결정하고 위상 변화량을 계산할 수 있었다. 10 cm 길이의 이터븀 도핑된 광섬유를 대상으로시뮬레이션을 수행한 결과 1330 nm 신호광에 rad 만큼의 위상 변화를 유도하기 위해서 필요한 펌프광의광출력은 8.5 mW로 계산되었다. 광섬유 마이켈슨 간섭계에 실험에서 rad 위상 변화를 유도하기위해서 인가한 펌프광은 9.5 mW로 시뮬레이션 결과와 매우 유사한 결과를 보였다. 이 결과로부터 저출력펌프광과 수십 cm 길이의 광섬유를 이용함으로써 위상 천이 간섭계에서 요구되는 위상 제어가 충분히가능함을 확인할 수 있었다.

Age-hardening behavior and phase transformation process in a dental casting Ag-Au-Cu-Pd alloy

Mi-Hyang Cho(조미향),Joo-Hee Park(박주희),Yong-Hoon Kwon(권용훈),Hyung-Il Kim(김형일),Hyo-joung Seol(설효정) 대한치과재료학회 2009 대한치과재료학회지 Vol.36 No.3

Aging behavior and phase transformation process in a crown and bridge alloy composed of 44.9 wt% Ag-41.0 wt% Au-11.0 wt% Cu-1.7 wt% Pd-1.0 wt% Zn-0.4 wt% Pt were investigated and the following results were obtained. 1. The hardness of the solution-treated specimen began to increase and reached the maximum value, and further aging caused continous hardness decrease. 2. By aging, the Ag-Au-Cu-based α₀ phase, the Ag-Au-rich α₁ phase and the Cu-Au-rich α₂ phase were transformed into the α₁’ phase and the ordered Cu₃Au phase through the dis-ordered α₂’ phase. 3. The hardness increased by the lattice strains formation during the phase decomposition of the α₀ phase into the α₁’ phase and the α₂’ phase. 4. The grain boundary precititation and the coarsening of the Cu₃Au precipitates released the lattice strains by reducing the interface between the Ag-Au-rich α₁’ matrix and the Cu₃Au precipitates, which resulted in the hardness decrease. 5. The matrix layer of the lamellar structure con-sisted of the Ag-Au-based α₁’ phase contain-ing Cu, and the precipitates layer of the la-mellar structure consisted of the Cu₃Au phase containing Ag.

상변화 냉각시스템의 정량적 성능지수 연구

장명언,송혜은 한국군사과학기술학회 2020 한국군사과학기술학회지 Vol.23 No.3

In this paper, I introduce Phase-Change Cooling for thermal management of high power devices that can be applied to High Power Laser and Electric Propulsion Systems which are composed of multiple distributed superheat sources. Phase-Change Cooling can be good used to efficient cooling of their heat sources. Phase-Change Cooling has extremely high efficiency of two-phase heat transport by utilizing heat of vaporization, relatively low flow rates and reduced pumps power. And I suggest TPI(Thermal Performance Index) which is a quantitative performance index of Phase-Change Cooling for thermal management. I quantify the performance of Phase-Change Cooling by introducing TPI. I present the test results of TPI’s changing refrigerant, heat sink and flow rate of the Phase-Change Cooling system through the experiments and analyze these results.

여러 가지 상변화물질 슬러리의 원형관내 대류 열전달에 관한 연구

崔恩洙,鄭東柱 明知大學校 産業技術硏究所 2003 産業技術硏究所論文集 Vol.22 No.-

To investigate convective heat transfer of various the phase-change-material slurries in a circular tube, paraffin slurry, MC-lauric acid slurry, MC-octadecane slurry and ice slurry were tested in two kinds of heat transfer experimental apparatus with constant heat flux test section. Nusslet numbers of the phase-change-material slurries were found to increase when the phase-change- material melted. Nusselt number of the phase-change material slurry increased, as the size and fraction of the phase-change material increased. The effective thermal capacities of the phase-change-material slurries were higher than those of water. As fraction and fusion energy of the phase-change-material increased, the effective thermal capacity increased.

Self-Assembled Incorporation of Modulated Block Copolymer Nanostructures in Phase-Change Memory for Switching Power Reduction

Park, Woon Ik,You, Byoung Kuk,Mun, Beom Ho,Seo, Hyeon Kook,Lee, Jeong Yong,Hosaka, Sumio,Yin, You,Ross, C. A.,Lee, Keon Jae,Jung, Yeon Sik American Chemical Society 2013 ACS NANO Vol.7 No.3

<P>Phase change memory (PCM), which exploits the phase change behavior of chalcogenide materials, affords tremendous advantages over conventional solid-state memory due to its nonvolatility, high speed, and scalability. However, high power consumption of PCM poses a critical challenge and has been the most significant obstacle to its widespread commercialization. Here, we present a novel approach based on the self-assembly of a block copolymer (BCP) to form a thin nanostructured SiO<SUB><I>x</I></SUB> layer that locally blocks the contact between a heater electrode and a phase change material. The writing current is decreased 5-fold (corresponding to a power reduction by 1/20) as the occupying area fraction of SiO<SUB><I>x</I></SUB> nanostructures is increased from a fill factor of 9.1% to 63.6%. Simulation results theoretically explain the current reduction mechanism by localized switching of BCP-blocked phase change materials.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2013/ancac3.2013.7.issue-3/nn4000176/production/images/medium/nn-2013-000176_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn4000176'>ACS Electronic Supporting Info</A></P>

GeSbTe계 이중층의 상변화 특성에 미치는 열처리 온도 효과

윤회진,방기수,이승윤,Yoon, Hoi Jin,Bang, Ki Su,Lee, Seung-Yun 한국전기전자재료학회 2017 전기전자재료학회논문지 Vol.30 No.2

This work reports the phase-change behavior and thermal stability of doped GeSbTe/GeSbTe bilayers. We prepared the bilayers using RF sputtering, and annealed them at annealing temperature ranging from $100^{\circ}C$ to $400^{\circ}C$. The sheet resistance of the bilayer decreased and saturated with increasing annealing temperature, and the saturated value was close to that of pure GeSbTe film. The surface of the bilayer roughened at $400^{\circ}C$, which corresponds to the surface roughening of doped GeSbTe film. Mixed phases of face-centered cubic and hexagonal close-packed crystalline structures were identified in the bilayers annealed at elevated temperature. These results indicate that the phase-change behavior of the bilayer depends on the concurrent phase-transitions of the two GeSbTe-based films. The dopants in the doped GeSbTe film were diffused out at annealing temperatures of $300^{\circ}C$ or higher, which implies that the thermal stability of the bilayer should be considered for its application in phase-change electronic devices.

기포 구동 흐름과 이산화티타늄 나노파티클이 융합된 상변화물질의 열전달 강화 연구

최성호(Sung Ho Choi),장수진(Jang Su Jin),손동기(Dong Kee Sohn),고한서(Han Seo Ko) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11

Phase-change materials using latent heat energy and isothermal characteristics in phase change period are applied to thermal energy storage devices, thermal management devices, etc. However, low heat transfer performance of phase change materials is evaluated as a disadvantage for various applications. To overcome these shortcomings, various studies have been conducted to enhance the heat transfer performance of phase change materials. In this study, we propose the convergence of bubble-driven flow and TiO2 nanoparticles to enhance the heat transfer of phase-change materials. Physical properties of phase change materials and heat transfer mechanisms are analyzed using visualization experiments.