• Title/Summary/Keyword: H-R diagram

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Prediction of the Forming Limit Diagram for AZ31B Sheet at Elevated Temperatures Considering the Strain-rate Effect - II (변형률속도 효과를 고려한 AZ31B 판재의 온간 성형한계도 예측 - II)

  • Choi, S.C.;Kim, H.Y.;Kim, H.J.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2009.10a
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    • pp.285-288
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    • 2009
  • The purpose of this study is to predict the forming limit diagram (FLD) of strain-rate sensitive materials on the basis of the Marciniak and Kuczynski (M-K) theory. The strain-rate effect is taken into consideration in such a way that the stress-strain curves for various strain-rates are inputted into the formulation as point data, not as curve-fitted models such as power function. Tensile tests and R-value tests were carried out at several levels of temperature and strain-rate from $25^{\circ}C$ to $300^{\circ}C$ and 0.16 to 0.00016/s, respectively to obtain the mechanical properties of AZ31B magnesium alloy sheet. The FLD of this material was experimentally obtained by limit dome height tests with the punch velocity of 0.1 and 1.0 mm/s at $250^{\circ}C$. The M-K theory-based FLD predicted using Yld2000-2d yield criterion was compared with the experimental results.

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Comparing the Whole Body Impedance of the Young and the Elderly using BIMS

  • Kim, J.H.;Kim, S.S.;Kim, S.H.;Baik, S.W.;Jeon, G.R.
    • Journal of Sensor Science and Technology
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    • v.25 no.1
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    • pp.20-26
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    • 2016
  • The bioelectrical impedance (BI) for the young and the elderly was measured using bioelectrical impedance spectroscopy (BIS). First, while applying a current of $600{\mu}A$ to the foot and hand, BI was measured at 50 frequencies ranging from 5 to 1000 kHz. The BI for young subjects was considerably lower than that for old subjects since young subjects have more lean mass (hydration). The prediction marker was 0.74 for young subjects and 0.78 for old subjects. Second, a Cole-Cole diagram was obtained for young subjects and old subjects, indicating the different characteristic frequencies. At 50 kHz, the average phase angle was $7.8^{\circ}$ for young subjects whereas that was $6.1^{\circ}$ for old subjects. Third, BIVA was analyzed for young subjects and old subjects. The vector length was 210.89 [${\Omega}/m$] for young subjects and 326.12 [${\Omega}/m$] for old subjects. At 50 kHz, the resistance (R/H) and the reactance ($X_C/H$) divided by height were 208.94 [${\Omega}/m$] and 28.68 [${\Omega}/m$] for young subject, and 324.33 [${\Omega}/m$] and 34.09 [${\Omega}/m$] for old subjects.

Thermodynamic analysis on the chemical vapor deposition process of Ta-C-H-Cl system

  • Kim, Hyun-Mi;Shim, Kwang Bo;Lee, Jung-Min;Lee, Hyung-Ik;Choi, Kyoon
    • Journal of Ceramic Processing Research
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    • v.19 no.6
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    • pp.519-524
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    • 2018
  • Carbon/carbon composites (C/C) have been widely studied in the aerospace field because of their excellent thermal shock resistance and specific strength at high temperature. However, they have the problems that is easily oxidized and deteriorated under atmospheric environment. In order to overcome these shortcomings, the CVD coating of ultra-high-temperature ceramics to C/C has become an important technical issue. In this study, thermodynamic calculations were performed to TaC CVD coating on C/C by FactSage 6.2 program. The Ta-C phase diagrams were constructed with the results of thermodynamic calculations in the Ta-C-H-Cl system. Based on the Ta-C phase diagram, the experimental conditions were designed to confirm the deposition of various phases such as TaC single phase, TaC + C and $TaC+Ta_2C$ by varying the composition of Ta/C ratio. The deposited films were found to be in good agreement with the predicted phases.

Development of Lecithin Organogel to Improve Solubility of Genistein (레시틴 오가노겔을 이용한 난용성 제니스테인의 용해도 향상)

  • Lee, Su Jin;Kim, Jung A;Kang, Nae Gyu;Park, Sun Gyoo;Lee, Cheon Koo
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.41 no.3
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    • pp.201-208
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    • 2015
  • Organogels are semi-solid systems that consist of an apolar solvent as the liquid phase within a three-dimensional networked structure. In this study, we developed a stable and skin penetration-enhanced Lecithin Organogel (LO) containing genistein, which is one of the poorly soluble active ingredients in both polar and apolar phase. After screening of various components (type of gelators, organic and aqueous phase), hydrogenated lecithin (HL), sunflower oil (SO), dipropylene glycol (DPG), and polyethylene glycol (PEG) were mainly used in this formulation. Phase ternary diagram was employed for optimization of the composition in the LO. The formulated LO were evaluated for its organoleptic characteristics, stability, pH, rheology, phase transition temperatures, microscopic analysis and skin penetration. The optimized stable LO system can be utilized as an effective and stable cosmetic formulation that can carry poorly soluble active ingredients at high concentration for topical dermal delivery.

Analyses of Leakage Magnetic Field and Leakage Inductance in Current Transformers by 3-D Integral Methods (3차원 적분법을 이용한 변류기의 누설 자계 및 누설 인덕턴스 해석)

  • 이희갑;박용필;이준웅;박우현;이기식
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.07a
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    • pp.503-506
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    • 2001
  • This paper presents leakage magnetic field and leakage inductance calculations in current transformer by means of 3-D Integral methods. From the distribution diagram of leakage magnetic flux to be analyzed using program called TRACAL3, it confirms a parallel to the winding axis direction of the leakage flux lines in the air gap between the windings. The leakage inductances L$\sub$r1/ and L$\sub$R2/ of the primary and secondary windings were calculated, their values are 4.23 mH and 0.49 mH, respectively. They are also similar to the measured values of the leakage inductances for the experimental verification, 4.06 mH and 0.47 mH.

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A Study on the Leakage Inductance in Current Transformers by 3D Integral Methods (3차원 적분법을 이용한 변류기의 누설 인덕턴스에 대한 연구)

  • Lee, Hee-Kab;Park, Yong-Pil;Lee, Sung-Ill
    • Proceedings of the KIEE Conference
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    • 2002.11a
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    • pp.116-118
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    • 2002
  • This paper presents leakage magnetic field and leakage inductance calculations in current transformer by means of 3-D Integral methods. From the distribution diagram of leakage magnetic flux to be analyzed using program called TRACAL 3, it confirms a parallel to the winding axis direction of the leakage flux lines in the air gap between the windings. The leakage inductances $L_{r1}\;and\;L_{r2}$ of the primary and secondary windings were calculated, their values are 4.23 mH and 0.49 mH, respectively. They are also similar to the measured values of the leakage inductances for the experimental verification, 4.06 mH and 0.47 mH.

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A Study on the Magnetic Field Analysis and Leakage Inductance in Current Transformers by 3D Integral Methods (3차원 적분법을 이용한 변류기의 자계해석과 누설 인덕턴스에 대한 연구)

  • 이희갑;박용필
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.14 no.9
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    • pp.768-772
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    • 2001
  • This paper presents leakage magnetic field and leakage inductance calculations in current transformer by means of 3-D Integral methods. From the distribution diagram of leakage magnetic flux to be analyzed using program called TRACAL 3, ti confirms a parallel to the winding axis direction of the leakage flux lines in the air gap between the windings. The leakage inductances L$\sub$r1/ and L$\sub$r2/ of the primary and secondary winding were calculated, their values are 4.23 MH and 0.49 mH, respectively. They are also similar to the measured values of he leakage inductances of the experimental verification, 4.06 mH and 0.47 mH.

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Assessment of maximum liquefaction distance using soft computing approaches

  • Kishan Kumar;Pijush Samui;Shiva S. Choudhary
    • Geomechanics and Engineering
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    • v.37 no.4
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    • pp.395-418
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    • 2024
  • The epicentral region of earthquakes is typically where liquefaction-related damage takes place. To determine the maximum distance, such as maximum epicentral distance (Re), maximum fault distance (Rf), or maximum hypocentral distance (Rh), at which an earthquake can inflict damage, given its magnitude, this study, using a recently updated global liquefaction database, multiple ML models are built to predict the limiting distances (Re, Rf, or Rh) required for an earthquake of a given magnitude to cause damage. Four machine learning models LSTM (Long Short-Term Memory), BiLSTM (Bidirectional Long Short-Term Memory), CNN (Convolutional Neural Network), and XGB (Extreme Gradient Boosting) are developed using the Python programming language. All four proposed ML models performed better than empirical models for limiting distance assessment. Among these models, the XGB model outperformed all the models. In order to determine how well the suggested models can predict limiting distances, a number of statistical parameters have been studied. To compare the accuracy of the proposed models, rank analysis, error matrix, and Taylor diagram have been developed. The ML models proposed in this paper are more robust than other current models and may be used to assess the minimal energy of a liquefaction disaster caused by an earthquake or to estimate the maximum distance of a liquefied site provided an earthquake in rapid disaster mapping.

Optimum Stand Density Control Considering Stability in Larix kaempferi Forests (임분 안정성을 고려한 일본잎갈나무 임분밀도 관리의 적정 수준)

  • Park, Joon Hyung;Chung, Sang Hoon;Kim, Sun Hee;Lee, Sang Tae
    • Journal of Korean Society of Forest Science
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    • v.109 no.2
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    • pp.202-210
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    • 2020
  • This study investigated the optimal levels of stand density control considering the stability of Larix kaempferi stands. A stand density management diagram was developed from 259 sample plots. Based on these data, we determined an optimal level of the stand density control by identifying the relationship between the relative yield index (Ry) and height-to-diameter ratio. The estimated r-square (R2) of the stand density management diagram is 0.600. The analysis of the relationship between Ry and the slender tree incidence showed that when the stand density exceeded a certain threshold and the ratio of slender trees rapidly increased. The critical value of Ry was 0.63. The results of this study are expected to contribute to the establishment of stand management strategies that can reduce damage from natural causes, such as wind and snow, and to develop stand practice systems for the improved productivity of commercial forests.

THE C-M DIAGRAM OF THE GLOBULAR CLUSTER, NGC 6752

  • Lee, See-Woo;Cannon, R.D.
    • Journal of The Korean Astronomical Society
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    • v.13 no.1
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    • pp.15-26
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    • 1980
  • The BV-photographic photometry was made for 1714 stars (V<19.5) in NGC 6752. The C-M diagram of this cluster shows an unusually extended blue horizontal branch $(V=13.5{\sim}17.8)$ with a wide gap $(V=16{\sim}16.7)$ and the well defined giant branch with gaps at V=13.85 and 16.2. The turnoff point is defined at $V=17.25{\pm}0.15$ and (B-V) = $0.46{\pm}0.02$. If we take $V_{HB}=13.85$ for NGC 6752, then ${\Delta}V=2.80,\;(B-V)_{0,g}=0.76\;and\;{\Delta}V_{TO}=3.40$ and the chemical abundance is estimated to be [Fe/H]=-1.67 or $Z=4.3{\times}10^{-4}\;and\;Y=0.26$. Some other physical parameters of this cluster are derived and compared with those for the well observed clusters M 3, M 13, M 15 and M 92.

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