• Title/Summary/Keyword: Gradient of Temperature

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An Experimental Study on the Characteristics of Moxa Combustion (II) - On the Density of Moxa Material - (애구(艾灸)의 연소(燃燒) 특성(特性)에 관한 실험적(實驗的) 연구(硏究)(II) - 애주(艾炷)의 밀도(密度)를 중심(中心)으로 -)

  • Park, Young-Bae;Kang, Sung-Keel;Huh, Wung
    • Journal of The Association for Neo Medicine
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    • v.1 no.1
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    • pp.103-113
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    • 1996
  • It is thought that the quantity and quality of the heat stimulation and the mechanism of heating process are important to understand the moxa-combustion. In order to get the basic data on the effective moxa-combustion method, combustion temperature changes (average temperature, peak temperature, average gradient temperature and maximum gradient temperature) of the heating period were measured respectively by the density of moxa material. For the experiment, samples of $300mg/0.26cm^3$ , $400mg/0.26cm^3$ and $500mg/0.26cm^3$ of moxa material were molded in a conical mold with each 10mm in diameter and height. 1. The average temperature and peak temperature of heating period on the moxa-combustion showed higher in the $400mg/0.26cm^3$ and $300mg/0.26cm^3$ than in the $500mg/0.26cm^3$ sample respectively. 2. The average gradient temperature of heating period on the moxa-combustion rose quickly in the $300mg/0.26cm^3$, $400mg/0.26cm^3$ and $500mg/0.26cm^3$ in that order and the maximum gradient temperature rose more quickly in the $300mg/0.26cm^3$ and $400mg/0.26cm^3$ than in the $500mg/0.26cm^3$ sample respectively. According to the above results, it is concluded that the density of moxa material is (the) more important (factor) than the weight or volume of moxa material on the combustion temperature changes of the heating period for the evaluation of the quality and quantity of moxa-combustion.

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Effect of Temperature Gradient on the Characteristics of GaN Nanorods Grown on R-plane Sapphire Substrates (기판 주변 반응 기체와 기판 사이의 온도 차이에 따른 r-면 사파이어 기판에 성장된 길화갈륨 나노 막대의 특성 변화 연구)

  • Shin, Bo-A;Kim, Chin-Kyo
    • Journal of the Korean Vacuum Society
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    • v.18 no.1
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    • pp.44-48
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    • 2009
  • The effect of temperature gradient between the substrate and ambient gas on the structural characteristics of GaN nanorods grown on r-plane sapphire substrates by hydride vapor phase epitaxy was investigated. The density, diameter, and length strongly depended on the tempearture gradient. In addition, the cross-sectional shape of the nanorrods at the end of growth was found to be more dependedent on the temperature of a substrate itself than the temperature gradient.

A Basic Study for the Propagation Characteristics Due to the Horizontal Water Temperature Variations in the Sea (해양에서의 수평적 수온변화가 음파전달에 미치는 영향에 대한 기초적 연구)

  • Ha, Kang-Lyeol;Kim, Moo-Joon
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.32 no.4
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    • pp.395-401
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    • 1996
  • In this paper, the propagation characteristics due to the horizontal water temperature variations in the sea such as thermal fronts is analyzed by the ray theory. Two models for the temperature anomaly layer are chosen. One is a plane type and the other is a cylindrical type. In the plane type, the temperature increases linearly from a isothermal region to 5km with the gradient of about $2^{\circ}C.$/km, and decreases with the same gradient in next 5km. In the cylindrical type, water temperature increases only with the same gradient from a half cylindrical thermal boundary surface. The result showed that the gradient of acoustic rays decreases in the temperature increasing region and vice versa in temperature decreasing region. And, the transmission loss due to the temperature variation was less than O.2dB in the plane type model as well as in the cylindrical one.

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Experimental Study on the Stimulating Effect of Commercial Moxa Combustion through the Measurement of Temperature - Focused on ascending temperature gradient and effective stimulating period - (온도 측정을 통한 상용 쑥뜸의 자극효과에 대한 실험적 연구 - 승온속도 및 유효자극기를 중심으로 -)

  • Lee, Geon-Mok;Lee, Gun-Hyee;Lee, Seung-Hoon;Yang, Myung-Bok;Go, Gi-Deok;Seo, Eun-Mi;Jang, Jong-Deok;Hwang, Byung-Chan
    • Journal of Acupuncture Research
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    • v.19 no.3
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    • pp.64-76
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    • 2002
  • Objective : The purpose of this study is to investigate the mechanism and effect of moxibustion objectively and to be used as the quantitative data for developing the new thermal stimulating treatment by observing the combustion characteristics of commercial moxaes. Methods : We have selected two types(large-size moxa A(LMA), large-size moxa B(LMB)) among large moxaes used widely in the clinic. We examined combustion times, temperatures, temperature gradients in each period during a combustion of moxa. Results : 1. The ascending temperature gradient measured in the central point of non-contacted surface was fastest, the average ascending temperature gradient of both moxaes was $0.0384^{\circ}C/sec$, $0.0123^{\circ}C/sec$ respectively, 3.1 times faster in LMA. The maximum ascending temperature gradient was also about 2.9 times faster in LMA. The time required for the maximum ascending temperature gradient from ignition was 254sec, 411sec respectively. 2. The minimum descending temperature gradient in the retaining period was $-0.0250^{\circ}C/sec$, $-0.0090^{\circ}C/sec$ respectively and the average descending temperature gradient was $-0.0160^{\circ}C/sec$, $-0.0037^{\circ}C/sec$ respectively on the non-contact surface. 3. On the basis of the non-contact surface($A_I$), the time at which the effective stimulus period began to occur was about 264sec, 796sec respectively after an ignition, the time at which the maximum temperature began to occur was about 373sec, 1323sec respectively after an ignition, and the maximum temperature was $0.9^{\circ}C$ higher in LMA. The maximum ascending temperature gradient was also about 4.2 times faster in LMA. Conclusion : It was thought that not only the figure of moxicombustion device, but also the form and size of moxa had influence on the combustion characteristics deciding the performance of stimulus seriously.

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An efficient numerical model for free vibration of temperature-dependent porous FG nano-scale beams using a nonlocal strain gradient theory

  • Tarek Merzouki;Mohammed SidAhmed Houari
    • Structural Engineering and Mechanics
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    • v.90 no.1
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    • pp.1-18
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    • 2024
  • The present study conducts a thorough analysis of thermal vibrations in functionally graded porous nanocomposite beams within a thermal setting. Investigating the temperature-dependent material properties of these beams, which continuously vary across their thickness in accordance with a power-law function, a finite element approach is developed. This approach utilizes a nonlocal strain gradient theory and accounts for a linear temperature rise. The analysis employs four different patterns of porosity distribution to characterize the functionally graded porous materials. A novel two-variable shear deformation beam nonlocal strain gradient theory, based on trigonometric functions, is introduced to examine the combined effects of nonlocal stress and strain gradient on these beams. The derived governing equations are solved through a 3-nodes beam element. A comprehensive parametric study delves into the influence of structural parameters, such as thicknessratio, beam length, nonlocal scale parameter, and strain gradient parameter. Furthermore, the study explores the impact of thermal effects, porosity distribution forms, and material distribution profiles on the free vibration of temperature-dependent FG nanobeams. The results reveal the substantial influence of these effects on the vibration behavior of functionally graded nanobeams under thermal conditions. This research presents a finite element approach to examine the thermo-mechanical behavior of nonlocal temperature-dependent FG nanobeams, filling the gap where analytical results are unavailable.

Characteristics of Frost Formed on Heat Exchanger Fins of Non-Uniform Temperature Distribution (불균일한 온도분포를 갖는 열교환기 휜에서의 착상 특성)

  • An, Won-Jun;Kim, Jung-Soo;Lee, Kwan-Soo
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.21 no.7
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    • pp.373-379
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    • 2009
  • In this study, frosting experiment was conducted to investigate the characteristics of frost formed on heat exchanger fins of non-uniform temperature distribution. Temperature distribution and frost characteristics of a 2-D fin surface were investigated in the airflow direction and the direction perpendicular to airflow. Temperature gradient was very small in the airflow direction, while it was large in the direction perpendicular to airflow due to fin heat conduction. The variations of the frost thickness gradient and the frost density gradient in the direction perpendicular to airflow were significant. On the other hand, the temperature gradient on frost surface in the direction perpendicular to airflow was significant at the early stage of frosting, while it decreased gradually as time elapsed.

Multi-junction thermocouple for temperature gradient measurements (온도구배 측정용 다중접점 열전대)

  • Kim, Yong-Gyoo;Gam, Kee-Sool
    • Journal of Sensor Science and Technology
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    • v.4 no.2
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    • pp.3-6
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    • 1995
  • Type K thermocouples having multi-junction for measuring the temperature gradient of the furnace were fabricated. The obtained results on the temperature gradient of the electric furnace maintained at $800^{\circ}C$ were consistent with those for the reference grade type S thermocouple, which was carefully calibrated, within the permitted error limit of the type K thermocouple. It was suggested that noble metal multi-junction thermocouples be suitable for more accurate temperature gradient measurements.

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DNA computing using a difference of melting temperature among DNA fragments

  • Lee, Ji-Yeon;Sin, Su-Yong;Jang, Byeong-Tak;Park, Tae-Hyeon
    • 한국생물공학회:학술대회논문집
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    • 2002.04a
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    • pp.539-542
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    • 2002
  • We propose new encoding method for numerical data in DNA using temperature gradient. To represent numerical values in DNA sequences, we introduce melting temperature. Since DNA strands representing smaller values have a lower Tm, they tend to denature with ease and also easily amplified by denaturation temperature gradient PCR. We also implement a local search molecular algorithm using temperature gradient, which is contrasted to conventional exhaustive search molecular algorithms. The proposed methods are verified by solving an instance of the travelling salesman problem. We could effectively amplify the correct solutions and the use of temperature gradient made the detection of solutions easier.

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A CONFIRMATION OF ELECTRON TEMPERATURE GRADIENT IN OUR GALAXY

  • Hong, Seung-Soo
    • Journal of The Korean Astronomical Society
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    • v.13 no.1
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    • pp.35-44
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    • 1980
  • Various assumptions used in interpreting the observations of hydrogen recombination lines are critically assessed to confirm the gradient of electron temperature with distance from the galactic center. The total temperature increase from 5 to 13 kpc is about 2,500 K. Among many suggestions, we have singled out the decrease of trace dement abundances with the galactoccntric distance as the most viable cause for the temperature gradient. This will impose an important constraint on evolutionary models of the Galaxy.

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THE EFFECT OF RADIAL TEMPERATURE GRADIENT ON THE CIRCULAR-COUETTE FLOW (반경방향으로의 온도구배가 Circular-Couette 유동에 미치는 영향)

  • Kang, Chang-Woo;Yang, Kyung-Soo;Mutabazi, Innocent
    • Journal of computational fluids engineering
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    • v.14 no.3
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    • pp.16-24
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    • 2009
  • Numerical simulation has been carried out to investigate the influence of radial temperature gradient on the Circular-Couette flow. Varying the Grashof number, we study the detailed flow and temperature fields. The current numerical results show good agreement with the analytical and experimental results currently available. It turns out that spiral vortices are generated by increasing temperature gradient. We classify the flow patterns for various Grashof number based on the characteristics of flow fields and spiral vortices. The correlation between Richardson number with wave number shows that the spiral angle and size of spiral vortices increase with increasing Richardson number.