• Title/Summary/Keyword: heat needle

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The Effects of Homogenization, Hot-Forging, and Annealing Condition on Microstructure and Hardness of a Modified STD61 Hot-Work Tool Steel (균질화, 열간단조, 어닐링 조건이 개량된 STD61 열간 금형강의 미세조직과 경도에 미치는 영향)

  • Park, Gyujin;Kang, Min-Woo;Jung, Jae-Gil;Lee, Young-Kook;Kim, Byung-Hoon
    • Journal of the Korean Society for Heat Treatment
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    • v.26 no.2
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    • pp.72-79
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    • 2013
  • The effects of homogenization, hot-forging, and annealing condition on microstructure and hardness of a modified STD61 hot-work tool steel were investigated. The ingot specimen had a dendritic structure consisting of bainite and martensite. Spherical VC particles of approximately 50 nm and cuboidal (V,Ti)C particles of about 100 nm were observed in the ingot specimen. After homogenization, the dendritic structure was blurred, and the difference in hardness between martensite and bainite became narrow, resulting in the more homogeneous microstructure. Needle-shaped non-equilibrium $(Fe,Cr)_3C$ particles were additionally observed in the homogenized specimen. The hot-forged specimen had bainite single phase with spherical VC, cuboidal (V,Ti)C, and needle-shaped $(Fe,Cr)_3C$ particles. After annealing at $860^{\circ}C$, the microstructures of specimens were ferrite single phase with various carbides such as VC, $(Fe,Cr)_7C_3$, and $(Fe,Cr)_{23}C_6$ because of relatively slow cooling rates. The size of carbides in annealed specimens decreased with increasing cooling rate, resulting in the increase of hardness.

A Study on the Bubble Deformation and Departure Under DC Electric Field (직류전기장에 의한 기포의 변형과 이탈에 관한 연구)

  • 권영철;김무환;강인석;김석준
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.6
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    • pp.1518-1528
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    • 1995
  • The deformation and departure processes of a bubble attached to the wall are studied experimentally and numerically to understand the phenomena of the nucleate boiling heat transfer enhancement under DC electric field. An air-bubble is injected in a dielectric liquid with different electric fields generated by changing three types of electrode system (Type 1,2 and 3) in the bubble generator. Experimental variables are the electric field strength and the distance and the shape of the electrodes under DC electric field. From experimental results, it is observed that the bubble under Dc electric field is elongated in the same direction as the electric field and the contact angle increases. For the parallel plate electrode which generates a uniform electric field, bubble departure volume doesn't seem to decrease within our experimental range. However, when a needle is raised a few millimeters from the lower electrode to make a nonuniform electric field around the needle, bubble departure volume decreases continuously with the increase of an applied voltage. The reduction effect of bubble departure volume is the most effective under a strong nonuniform electric field generated with Type 3. As the nonuniformity of the electric field due to the shape of a electrode increases, the terminal velocity and the acceleration of a bubble increase largely. For the comparison with visualization results, the deformation of a bubble attached to the electrode is carried out by a numerical method. Numerical results show good agreement qualitatively with experimental results.

A Philological Study on the Pathology, Acupuncture and Moxibustion of Alopecia (탈발(脫髮)의 병인병기(病因病機) 및 침구치료(鍼灸治療)에 관한 문헌고찰)

  • Lee, Sang Hyun;Cho, Myoung Rae
    • Journal of Acupuncture Research
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    • v.32 no.2
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    • pp.35-57
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    • 2015
  • Objectives : The purpose of this study is to analyze literature on oriental medicine to investigate the pathology, acupuncture, and moxibustion therapy applicable to alopecia Methods : We searched for the causes of alopecia in the bibliographic data from 41 sources of literature and the acupunctural treatments for alopecia in the bibliographic data from 49 sources of Chinese and Korean literature and from the journals of the acupunctural treatments for alopecia which have been published since 2000. Results : 1. The main causes of alopecia are blood deficiency, blood heat, static blood, depletion of kidney's water, wind excess, seven emotional damage, dietary damage, etc. 2. The acupuncture points frequently used are $GV_{20}$, $GB_{20}$, $ST_{36}$, $SP_6$, $SP_{10}$, $BL_{17}$, $BL_{18}$, $BL_{23}$, $GV_{23}$, $GV_{14}$, $CV_6$, $ST_8$, $KI_3$, $LR_3$, $HT_7$, $LI_{11}$, EX-$HN_1$, and ouch point. 3. New acupuncture therapies, including herbal acupuncture therapy, ear acupuncture therapy, dermal needle therapy, needle-embedding therapy and scalp acupuncture therapy are frequently used to treat alopecia. Conclusions : The acupuncture points frequently used for treating alopecia have characteristics such as tonifying blood, tonifying the liver and kidney, extinguishing wind, activating blood, clearing heat and draining dampness, so they are highly associated with the causes and the mechanisms of alopecia.

The Effect of Solution Heat Treatment and Aging Treatment on the Mechanical Properties of Backward Extruded A6061 Alloy for Pressure Vessels (고압용기로 사용되는 후방압출된 알루미늄 6061합금의 기계적 특성에 미치는 용체화처리 및 시효처리의 영향)

  • Kwon, Eui Pyo;Woo, Kee Do;Moon, Min Seok;Kang, Duck Soo;Nam, Gung Cheon;Yoo, Gye Hyoung
    • Korean Journal of Metals and Materials
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    • v.47 no.3
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    • pp.175-181
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    • 2009
  • Mechanical properties and precipitation behavior of backward extruded 6061 Al alloy for pressure vessel were investigated using tensile test, transmission electron microscopy (TEM) and differential scanning calorimeter (DSC). In this study, solution heat treatment (SHT) was performed at $535^{\circ}C$ for 30~90 min and aging treatment was conducted at 177 and $190^{\circ}C$ for 1~7 h. Maximum tensile strength of $36.6kgf/mm^2$ and yield strength of $33.29kgf/mm^2$ were achieved at the aging time of 5 h at $190^{\circ}C$. TEM observation showed that fine needle-like ${\beta}^{{\prime}{\prime}}$ phase which has 35~45 nm of length was uniformly distributed in the aged 6061 Al alloy specimen. From tensile test, TEM and DSC analysis, it is expected that aging time of 2~5 h at $190^{\circ}C$ is suitable for the extruded A6061 used as pressure vessels.

Effect of Heat-treatment on Microstructure and Tensile Properties in Cast Alloy 718 (주조 합금 Alloy 718에서 미세조직과 인장특성에 미치는 열처리의 영향)

  • Do, Jeong-Hyeon;Kim, In-Soo;Choi, Baig-Gyu;Jung, Joong-Eun;Jung, In-Yong;Jo, Chang-Yong
    • Journal of Korea Foundry Society
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    • v.36 no.5
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    • pp.167-173
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    • 2016
  • The effect of various types of heat-treatment on the mechanical properties of cast Alloy 718 has been investigated. Cast Alloy 718 bars were subjected to 'standard heat-treatment'_(SHT), 'HIP (Hot Isostatic Pressing) heat-treatment'_(HHT), and 'HIP-simulated heat-treatment'_(HS). In the absence of long time high temperature heat-treatment, a small amount of Laves phase remained in the 'SHT' specimen, and needle shaped ${\delta}$ precipitated in the vicinity of the Laves phase. Due to the formation of the Laves and ${\delta}$ phases in the 'SHT' specimen, it exhibited lower tensile properties than those of the others_specimens. On the other hand, the Laves phase was completely dissolved into the matrix after 'HHT' and 'HS' treatments. It is known that isostatic pressure reduces the self-diffusion coefficient, because of the lower self-diffusivity under HIP conditions in the interdendritic region, Nb segregation and the high amount of ${\gamma}^{{\prime}{\prime}}$ precipitation that occurs. Due to the higher fraction of coarse ${\gamma}^{{\prime}{\prime}}$ phases, the 'HHT' treated Alloy 718 showed excellent tensile strength.

Anticariogenic Activity and Glucosyltransferase Inhibitory Effects of Extracts from Pine Needle and Twig (솔잎 및 소나무 가지 추출물의 항충치 활성 및 glucosyltransferase 억제 효과)

  • Choi, Hee-Don;Koh, Yoon-Jeoung;Choi, In-Wook;Kim, Yun-Sook;Park, Yong-Kon
    • Korean Journal of Food Science and Technology
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    • v.39 no.3
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    • pp.336-341
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    • 2007
  • To investigate anticariogenic effects of extracts from pine needles and twigs, we measured the extracts' antimicrobial activities against Streptococcus mutans, their glucosyltransferase (GTase) inhibitory effects and their stabilities under various conditions of heat and pH. The 70% ethanol extracts of pine needles and twigs showed greater antimicrobial activities against S. mutans than the hot water extracts, and the pine twig extracts showed greater antimicrobial activity than the pine needle extracts. More specifically, the n-hexane fractions of the pine needles and twigs had the greatest effects against S. mutans, and their minimal inhibition concentration (MIC) was 0.6 mg/mL. The results of the extracts' GTase inhibitory effects indicated that the 70% ethanol extracts had greater effects than hot water extracts, and the pine twig extracts showed greater effects than the pine needle extracts. The antimicrobial activity against S. mutans for the pine needle n-hexane traction was greatly reduced as temperature increased, and was also largely affected by changes in pH. These results suggest that extracts from pine needles and twigs have anticariogenic effects and could be used as anticariogenic food additives.

An experimental study on the characteristic times of viscoelastic fluids by falling ball viscometer (낙구식 점도계를 이용한 점탄성 유체의 특성시간에 관한 실험적 연구)

  • 전찬열;유상신
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.1
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    • pp.241-250
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    • 1990
  • Characteristic relaxation time and characteristic diffusion time of viscoelastic fluids are determined experimentally by measuring the zero-shear-rate viscosity by falling ball viscometer and the infinite-shear-rate viscosity by capillary tube viscometer. Fluids used in experiments are aqueous solutions of polyacrylamide Separan AP-273 and the polymer concentrations range from 300 to 2000 wppm. A newly designed laser beam and timer system is employed to overcome the difficulty in measuring terminal velocities of the low concentration solutions. Ball removal device is prepared to remove the dropped ball from the bottom of cylinder without disturbing the testing fluid. In order to measure the zero-shear-rate viscosity, densities of hollow aluminium balls are adjusted very close to the densities of testing fluids. Characteristic diffusion time, which is ball viscometer. However, terminal velocity of a needle by falling ball viscometer is not affected by the time interval of dropping needles and characteristic diffusion time is not measured with a dropping needle. Powell-Eyring model predicts the highest values of the characteristic relaxation times among models used for heat transfer experimental works for a given polymer solution. As degradation of a polymer solution continues, the zero-shear-rate viscosity decreases more seriously than the infinite-shear-rate viscosity. Characteristic relaxation times of polymer solutions decreases as degradation continues.

Principal Components of Thermal Stimulation while the Warm Needling: Diameter of the Acupuncture Needle and Distance from the Skin (온침 표준화를 위한 열자극 요소 연구: 침 두께 및 피부-뜸 거리를 중심으로)

  • Yang, Seung-Bum;Kwon, O Sang
    • Korean Journal of Acupuncture
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    • v.36 no.4
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    • pp.210-220
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    • 2019
  • Objectives : Warm needling is a combined treatment technique of acupuncture and moxibustion. In this study, we aimed to find out the components related with the thermal stimulation of the warm needling and to provide basic data for the guideline of the warm needling technique in the clinic. Methods : In this study, we measured thermal change of 3% agarose phantom embedding K-type thermocouples in depths of 0, 1, 2, 4, 8 and 16 mm. The warm needling was performed with acupuncture needles of various specifications (0.50×30, 0.50×40, 0.30×30, 0.30×40, 0.20×30 and 0.20×40 mm). A linear regression analysis was performed to find out the major component and quantify the effectiveness of the thermal stimulation during warm needling. Results : As a result of the measurement of temperature change, we could observe the thermal change pattern from the surface of the phantom to the 16mm deep part of the phantom. The thermal pattern was similar among the needles of different specifications. The regression analysis pointed the distance between the moxa cautery and the skin surface as the main component for the thermal stimulation of the warm needling. Conclusions : The authors suggest considering the distance between moxa cautery and the skin rather than the diameter of the acupuncture needle in accordance to the result of the study.

Analysis of Vertical Combustion and Carbonization Patterns of Floor Materials When Using a Needle Flame (니들 플레임에 의한 바닥재의 수직 연소 및 탄화 패턴의 해석에 관한 연구)

  • Park, Min-Su;Choi, Chung-Seog
    • Fire Science and Engineering
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    • v.34 no.4
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    • pp.101-106
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    • 2020
  • This study analyzed flame growth characteristics and carbonization patterns when floor materials were burned vertically using a needle flame produced for this study. It was found that PVC flooring was fire retardant and the area under direct flame contracted inward. Vertical combustion causes solidification in the form of a lump at the bottom and also generates soot in a pattern that progresses upwards. This study found that laminated flooring exhibited no fire retarding characteristics and that the laminated layer of its upper surface was destroyed by fire, causing irregular delamination. The carbonization ranges at the left and right sides were determined to be symmetrical. A vertical combustion test of a sample carpet showed that it exhibited no fire-retarding characteristics. It was observed that if heat accumulated in the carpet, the flame formed an ascending air current, and that when flammable materials were present around the flame, they further accelerated the diffusion of the flame. The carbonization pattern at the carpet surface exposed to direct flame revealed that the carpet surface had melted and had flown downwards and that many tiny holes formed on it.

Case Report of Polyarteritis Nodosa Treated with Oriental Treatments Including Acupotomy (침도침 시술을 가미한 복합한방치료를 시행한 결절성 다발 동맥염의 치험례)

  • Lee, Eun-Sol;Kam, Chul-Woo;Youn, Hyoun-Min;Jang, Kyung-Jeon;Song, Chun-Ho;Kim, Young-Kyun;Kim, Cheol-Hong
    • Journal of Acupuncture Research
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    • v.29 no.3
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    • pp.129-137
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    • 2012
  • Objectives : Polyarteritis nodosa is a progressive disease of connective tissue that is characterized by nodules along arteries; nodules may block the artery and result in inadequate circulation to the particular area. This report is intended to estimate the efficacy using oriental complex treatment on a patient with Polyarteritis nodosa. Materials and Methods : From 19th March, 2012 to 12th May, 2012, One male inpatient diagnosed with polyarteritis nodosa was treated with general oriental medicine therapy : needle-embedding therapy ; acupuncture ; pharmacopuncture ; acupotomy therapy and herbal medication. VAS(visual analogue scale) was used for evaluation of both leg pain. Other subjective symptoms including night sweat, tinnitus, upper heat were evaluated by percentage comparing the symtoms before and after treatment. Results : The patient showed a certain degree of improvement in both leg pain and other subjective symtoms. Conclusions : Oriental treatments such as needle-Embedding therapy, acupuncture and moxibustion therapy, pharmacopuncture therapy, acupotomy therapy and herbal medication can be effective for controlling pain and other accompanied symtoms due to polyarteritis nodosa.