• Title/Summary/Keyword: hardness reduced rate

Search Result 102, Processing Time 0.022 seconds

The Effect of Disintegrants on the Properties of Salicylamide Tablets (수종의 붕해제가 살리실아미드정제의 제제특성에 미치는 영향)

  • Hwang, Sung-Joo;Rhee, Gye-Ju;Jee, Ung-Kil;Kwak, Hyo-Sung;Kim, Chong-Kook
    • Journal of Pharmaceutical Investigation
    • /
    • v.22 no.1
    • /
    • pp.41-48
    • /
    • 1992
  • Six common tablet disintegrants (corn starch, Avicel PH102, calcium carboxymethylcellulose, Primojel, Kollidon CL and Ac-Di-Sol) were used at the concentration of 0, 2, 4 and 6% (w/w) in salicylamide tablets made with wet granulation method. Certain physical parameters of the disintegrants (moisture sorption, hydration capacity and bulk density) were determined to evaluate their relative efficiency. The disintegration time and dissolution rate of the tablets were correlated well with the ranks of initial rate of moisture sorption for each disintegrant as follows; Ac-Di-Sol, Kollidon CL, primojel, calcium CMC, corn starch and Avicel PH102. The initial rate of moisture sorption was important for the disintegration capacity as well as hydration capacity. The effect of storage at different temperatures and relative humidity upon the tablets containing various disintegrants was evaluated in terms of tablet hardness and disintegration time. Storage at high temperature reduced the hardness substantially and retarded the disintegration of the all tablets studied. Especially, the hardness of tablets containing Kollidon CL was significantly reduced. Although the tablet hardness was decreased and the disintegration time was increased under a moderate humid condition, both of them were decreased under the severely high humid condition of 80 or 90% RH, which was due to the breakrupture of tablet matrix bonds by the excessive uptake of moisture. Therefore, the stability caused by moisture sorption should be considered, when disintegrants having high moisture sorption such as Kollidon CL, Ac-Di-Sol and Primojel were employed in the tablets containing water-labile or hygroscopic drugs.

  • PDF

A Study on the Dielectric Properties of Silicone Rubber due to Hardness Variation (경도 변화에 따른 실리콘 고무의 유전 특성에 관한 연구)

  • Lee, Sung-Ill
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.25 no.11
    • /
    • pp.916-921
    • /
    • 2012
  • This research measured the dielectric properties of silicone rubber with various hardness in 100 Hz~3 MHz, $30{\sim}170^{\circ}C$ conditions. When the hardness increases from 65 degree to 75 degree, the dielectric loss increased within frequency range of 100 kHz~3 MHz and was a little change in dielectric loss within temperature range of $90^{\circ}C{\sim}170^{\circ}C$. Thermogravimetric Analysis (TGA) showed the weight change rate increased a little while heated until $800^{\circ}C$. Scanning Electron Microscope (SEM) measurement showed that Aluminium Trihydroxide($AlOH_3$) which acts as a reinforcement agent reduced the size of the particles as the hardness increased.

Study of Warm Forging Process for Non-Heat-Treated Steel (비조질강 온간단조를 위한 공정검토)

  • Park, J.S.;Kang, J.D.;Lee, Y.S.;Lee, J.H.
    • Proceedings of the KSME Conference
    • /
    • 2001.06c
    • /
    • pp.525-530
    • /
    • 2001
  • As a part of efforts to examine feasibility of warm forging near-net-shape process for non-heat-treated steel to replace quenched and tempered S45C steel, the optimized process condition has been determined to be $820^{\circ}C$ for heating, 10/sec for strain rate of forging and approximately 250MPa for flow stress from observed results such as the $A_{3}$ transformation temperature of about $790^{\circ}C$, the fully dynamic recrystallized behavior between $800^{\circ}C\;and\;850^{\circ}C$ when compressed up to 63% engineering strain at 10/sec strain rate, and the high temperature microsturctural stability. Also, controlled cooling rate of $6.3^{\circ}C/sec$ by water-spraying at a rate of $0.10cc/sec-cm^{2}$ for 60seconds followed by air-cooling right after forging process has been considered in this study as a feasible approach based on examination of the microsturcture of mixed ${\alpha}-ferrite$ and pearlite, the hardness and tensile properties meeting specification, and the reduced total cooling time to room temperature. Successive works would be carried out for the impact strength, machinalility, and forgeability at this process in the near future.

  • PDF

Electroplating on the Lead Frames Fabricated from Domestic Copper Plate (국산동판을 사용한 리드프레임 도금기술에 관한 연구)

  • Jang, Hyeon-Gu;Lee, Dae-Seung
    • Journal of the Korean institute of surface engineering
    • /
    • v.19 no.3
    • /
    • pp.92-108
    • /
    • 1986
  • An electroplating on the lead frame fabricated from domestic copper plate was studied experimentally. In this study, nickel was plated on the thin copper lead frame and silver layer was coated on the nickel film in the cyanide electrolyte. The effect of process variables such as current density, plating time, coating thickness and flow rate of electrolytic solution on the properties of coating was investigated. Some samples on each step were fabricated during electroplating. The results obtained from polarization measurement, observation of SEM photograph, adhesion test of coating and microhardness test are as follows. On silver plating, polarization resistance of potentiostatic cathodic polarization curve is reduced as the flow rate of Ag electrolytic solution increases. And above resistance is also reduced when the minor chemicals of sodium cyanide and sodium carbonate are added in potassium silver cyanide bath. The reduced polarization resistance makes silver deposition on the cathode easy. An increase in the current density and the coating thickness causes the particle size of deposit to coarsen, and consequently the Knoop microhardness of the coating decreases. On selective plating an increase in the flow rate of plating solution lead to do high speed plating with high current density. In this case, the surface morphology of deposit is of fine microstructure with high Knoop hardness. An increasing trend of the adhesion of coating was shown with increasing the current density and flow rate of electrolytic solution.

  • PDF

Changes in Some Physical Properties of Kimchi during Salting and Fermentation (김치의 절임 및 숙성과정중 물리적 성질의 변화)

  • Kim, Woo-Jung;Ku, Kyung-Hyung;Cho, Han-Ok
    • Korean Journal of Food Science and Technology
    • /
    • v.20 no.4
    • /
    • pp.483-487
    • /
    • 1988
  • The viscosity of salt solution and Kimchi juice and salt penetration and hardness of Chinese cabbage were investigated during brining and fermentation at $4-35^{\circ}C$. The rate of salt penetration during brining increased as the temperature and salt concentration increased from 5% to 15% while the effect of temperature on the salt penetration rates(%/hr) was rather reduced as salt concentration increased. The hardness of the cabbage measured by puncture test showed a rapid initial decrease during salting and the viscosity of brine changed little. Fermentation of Kimchi resulted a little increase in viscosity of Kimchi juice while the hardness of the cabbage decreased rapidly as pH reduced to pH 4.2-4.3 and then increased a little thereafter.

  • PDF

Changes in Quality Characteristics of Jeungpyun containing different Levels of Malt Extract during Storage (엿기름 추출액의 첨가량에 따른 증편의 저장 중 품질 특성 변화)

  • Jung, Kyoung-Wan;Kim, Yoo-Kyung;Lee, Gui-Chu
    • Journal of the Korean Society of Food Culture
    • /
    • v.26 no.5
    • /
    • pp.521-529
    • /
    • 2011
  • This study evaluated the effects of different levels of malt extract on the hardness, moisture, water soluble starch (WSS) contents, and in vitro starch digestibility (IVSD) of Jeungpyun during storage at room temperature ($25{\pm}1^{\circ}C$) and refrigeration temperature ($4{\pm}1^{\circ}C$). Resistant starch (RS) and soluble starch (non-RS) contents were also evaluated. During storage at both temperatures, hardness increased in Jeungpyuns with the malt extract-added Jeungpyun groups (malt-added Jeungpyuns) exhibiting lower hardness than the control. The rate of retrogradation was faster upon storage at refrigeration temperature. Moisture and WSS contents as well as IVSD of Jeungpyuns decreased, whereas these levels were higher in malt-added Jeungpyuns compared to control. Storage increased RS contents in Jeungpyuns stored for up to 4 days, particularly at $4^{\circ}C$, whereas there was a decrease in RS content after 7 days of storage. However, RS content was lower in malt-added Jeungpyuns compared to control. Soluble starch (SS) contents of Jeungpyuns decreased. However, SS content was higher in malt-added Jeungpyuns than that of control. The reduced hardness and RS content as well as the rate of increase in other parameters of malt-added Jeungpyuns were dependent on the concentration of malt extract. These results reveal that addition of malt extract delayed retrogradation of Jeungpyun, whereas retrogradation possibly increased the content of RS during storage at both temperatures, however, that of RS decreased with increasing level of malt extract, suggesting that the level of malt extract as well as the storage conditions are important for obtaining acceptable texture and retaining the RS content of Jeungpyun, which is known to possess physiological activity.

Study on the tensile restraint crack characteristics in underwater welds of marine steel plates (선용 강판 수중용접부의 인장 구속 균열 특성에 관한 연구)

  • 오세규;강문호;김민남
    • Journal of Advanced Marine Engineering and Technology
    • /
    • v.11 no.3
    • /
    • pp.45-52
    • /
    • 1987
  • Generally the factors affected largely by the cold cracking sensitivity of the weld are the quantity of the diffusible hydrogen, the brittleness and hardness of the bond area and the tensile restraint stress. These factors have relation each other, and if we can reduce one of these factors, it becomes instrumental to the root cracks prevention of weld. This study deals with the gravity type-underwater-welding of KR Grade A-3 marine steel plate using E4303 welding electrode in order to compare wet-underwater-welding with in-air- welding, resulting in obtaining the tensile restraint characteristics, the hardness distribution, the quantity of diffusible hydrogen and the macro- and micro-crack properties in both underwater and in-air welds. The main results obtained are as follows: 1) The quantity of diffusible hydrogen measured for 48 hours is about 18cc/100g-weld-metal for the in-air-weld of one pass and about 48cc/100g-weld-metal for the underwater-weld of one pass which is about 3 times penetration of diffusible hydrogen compairing with the case of the in-air-weld. However, it was experimentally confirmed that, by the multi-pass welding of 2 to 5 passes, the diffusible hydrogen in the underwater weld metal can be reduced as much as 27 to 49%. 2) The hardness of the weld metal indicates the highest value in the heat affected zones of underwater weld for more rapid cooling rate, resulting in the higher sensitivity of cold cracking. So, it is desirable to soften the higher hardness in the HAZ by tempering effect such as the multi-pass welding in the underwater welding. 3) At the bond vicinity of the underwater weld HAZ, micro cracks were found as resulted by both more rapid cooling rate and more diffusible hydrogen and also by the stress corrosion cracking under the tensile restraint stress in the underwater. But this could be prevented by the tempering effect of the following weld bead such as the multi-pass welding.

  • PDF

A study on the Cutting Force Variation Comparison between Low CBN and Coated Low CBN Tools in Turning of SCM440 (Low CBN 코팅공구의 SCM440 선삭시 절삭력변화에 관한 연구)

  • Bang, Hong-In;Kim, Tea-Young;Oh, Sung-Hoon
    • Journal of the Korean Society of Manufacturing Process Engineers
    • /
    • v.12 no.1
    • /
    • pp.9-14
    • /
    • 2013
  • In recent years, high hardness steel is used for most of the material in many areas including aircraft, nuclear power, space exploration and automotive parts. Low CBN tools are widely used in industrial field which can effectively process high hardness steel of HRC 45 or harder. The results of this study demonstrated, when high hardness steel, SCM440 is turned with Low CBN tools coated with TiN and TiAlN coatings respectively, that both the thrust force and cutting force tends to increase with more increase in cutting force than thrust force, as the feed rate increases at constant cutting speed. In addition, the size of the cutting force and thrust force does not change with the increased cutting speed at the same feed rate, but the tool life is reduced if the cutting speed is increased to shorten the machining time. Therefore, it is recommended to limit the cutting speed at 250 m/min maximum or less. Furthermore, comparing the cutting force of the three tools at the same cutting condition, Tin coating tool showed the smallest cutting force and Low CBN was the next, and the TiAlN coating tools showed the largest cutting force.

Effect of Bed Height on Ginseng Growth and Soil Physical Properties (인삼포 두둑높이가 인삼의 생육 및 토양물리성에 미치는 영향)

  • 이일호;박찬수
    • Journal of Ginseng Research
    • /
    • v.15 no.3
    • /
    • pp.197-199
    • /
    • 1991
  • Growth of ginseng and physical properties of soil were compared with bed height in experimental plots of sand loam for four year and clay loam soil for three year old ginseng plants, respectively. Field survey was also carried out to compare yield and soil physical properties with bed height in the same fold of six years old ginseng fields. High yield of ginseng root was observed at high bed both in the experimental plots and field survey as well. The rate of rusty root was significantly reduced at high bed. Soil porosity increased but soil hardness decreased at high bed.

  • PDF

Effects of Heat Treatments on Microstructure , Hardness and Abrasive Wear Resistance in 3%C-10%Cr-5%Mo-5%W White Cast Iron (3%C-10%Cr-5%Mo-5%W 백주철에 있어서 열처리가 현미경조직, 경도 및 내마모성에 미치는 영향)

  • Yu, Sung-Kon
    • Journal of Korea Foundry Society
    • /
    • v.19 no.1
    • /
    • pp.33-37
    • /
    • 1999
  • White cast iron of 3%C-10%Cr-5%Mo-5%W was casted, and then heat treated with three different methods such as homogenizing, austenitizing and tempering to observe its effects on the microstructure, hardness and abrasive wear resistance. In uni-directional soldification, bamboo tree-like $M_7C_3$ carbide grew along with the heat flow direction, and fishbone-like $M_6C$ carbide was dispersed randomly among $M_7C_3$ carbides. While almost pearlitic structures were observed in the as-cast specimen, those of the heat treated specimens consisted of secondary carbide, retained austenite and tempered martensite. In austenitized specimen, the amounts of retained austenite were 60.88% due to the higher cooling rate encountered in forced air cooling. On the other hand, the amounts of retained austenite were reduced from 60.88% to 23.85% in tempered specimen due to the transformation of austenite into tempered martensite. The hardness of tempered specimen showed the highest value, and then decreased in the order of austenitized, as-cast and homogenized specimens. But, the abrasive wear resistance of austenitized specimen was the highest, and then decreased in the order of tempered, as-cast and homogenized specimens.

  • PDF