• Title/Summary/Keyword: J$_{}$ c/degradation

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A Study of Corona Discharge in Polymer Insulators by Artificial UV Radiation (인위적인 자외선 조사량에 따른 폴리머애자에서의 코로나 방전 특성)

  • Kim, Y.S.;Choi, M.I.;Kim, C.M.;Bang, S.B.;Shong, K.M.;Kwag, D.S.
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.5
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    • pp.643-648
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    • 2013
  • In this study, degradation was observed by irradiating UV rays to the polymer insulators which have been widely used in outdoor electric power facilities. For an indoor accelerated UV test, 0.55 w/m2 of UV rays were applied using a xenon-arc method. A UV detection system with 65 ${\phi}mm$ in diameter, 100 mm in length and 1.0 of brightness (F/#) has been designed. Even though efflorescence on the surface of polymer insulators wasn't observed according to the accelerated UV test. UV rays were detected at around 50% and 40% of insulation breakdown in EPDM and silicone-type insulators respectively. As degradation continued because of an indoor accelerated UV test, breakdown voltage with which UV rays can be detected in an early stage decreased as well. A silicone polymer insulator would be severer than EPDM polymer insulator in terms of surface degradation because of UV strength against $V_m/V_{BD}$ was high in silicone polymer insulators. UV strength in silicone-type insulators increased at 1,000 $kJ/m^2$ because contact angle at the intial stage sharply decreased to from $113^{\circ}$ to $92.1^{\circ}$.

A Study on Thermal Analytical Model for a Dry Dual Clutch (건식 듀얼 클러치의 열해석 모델에 대한 연구)

  • Liu, Hao;Lee, J.C.;Noh, Y.J.;Cho, J.H.;Lee, H.R.;Koh, J.E.;Kang, J.W.
    • Journal of Drive and Control
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    • v.12 no.1
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    • pp.1-8
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    • 2015
  • The stability of friction characteristics and thermal management for a dry type dual clutch transmission (DCT) are inferior to those of a wet clutch. Too high temperature resulting from frequent engagement of DCT speeds up degradation or serious wear of the pressure plate or burning of the clutch disk lining. Even though it is significantly important to estimate the temperature of a dry double clutch (DDC) in real-time, few meaningful study of the thermal model of DDC has been known yet. This study presented a thermal analytical model of lumped parameters for a DDC by analyzing its each component firstly. Then a series of experimental test was carried out on the test bench with a patented temperature telemetry system to validate the proposed thermal model. The thermal model, whose optimal parameter values were found by optimization algorithm, was also simulated on the experimental test conditions. The simulation results of DDC temperature show consistency with the experiment, which validates the proposed thermal model of DDC.

Synergetic effect of soluble whey protein hydrolysate and Panax ginseng berry extract on muscle atrophy in hindlimb-immobilized C57BL/6 mice

  • Han, Min Ji;Shin, Ji Eun;Park, Seok Jun;Choung, Se-Young
    • Journal of Ginseng Research
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    • v.46 no.2
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    • pp.283-289
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    • 2022
  • Background: Sarcopenia, defined as loss of muscle mass and strength with age, becomes a public health concern as the elderly population increases. This study aimed to determine whether the mixture of soluble whey protein hydrolysate (WPH) and Panax ginseng berry extract (GBE) has a synergetic effect on sarcopenia and, if so, to identify the relevant mechanisms and optimal mixing ratio. Methods: In the first experiment, C57BL/6 mice were hindlimb immobilized for one-week and then administered WPH 800 mg/kg, GBE 100 mg/kg, WPH 800 mg/kg+ GBE 100 mg/kg mixture, and Fructus Schisandrae extract (SFE) 200 mg/kg for two weeks. In the second experiment, experimental design was same, but mice were administered three different doses of WPH and GBE mixture (WPH 800 mg/kg+ GBE 100 mg/kg, WPH 800 mg/kg+ GBE 90 mg/kg, WPH 1000 mg/kg+ GBE 75 mg/kg). Results: In the first experiment, we confirmed the synergetic effect of WPH and GBE on muscle mass and identified that GBE was more effective on the protein synthesis side, and WPH tended to be slightly more effective for protein degradation. In the second experiment, among three different ratios, the WPH 800 mg/kg+ GBE 100 mg/kg was most effective for muscle mass and strength. The mixtures activated muscle protein synthesis via PI3K/Akt/mTORc1 pathway and inhibited muscle protein degradation via suppressing ubiquitin-proteasome system (UPS) and autophagy-lysosome system (ALS), and these effects were more GBE dose-dependent than WPH. Conclusion: The WPH and GBE mixture having a synergetic effect is a potential agent to prevent sarcopenia.

The Study on Properties of Surface Degradation of Silicone Rubber for Outdoor Use (옥외용 실리콘 고무의 표면 열화 특성 연구)

  • Seo, K.S.;Kim, J.H.;Song, W.C.;Moon, J.S.;Park, Y.K.;You, Y.S.
    • Proceedings of the KIEE Conference
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    • 1999.07e
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    • pp.2302-2304
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    • 1999
  • The application of polymeric insulators for outdoor use has been increasing as a new replacement of overhead line in abroad. In domestic case, it is actively going on the research of polymeric insulators. The Silicone rubber among polymeric insulators have a good electrical properties, due to surface hydrophobicity. This paper is concentrated on the recovery of surface hydrophobicity and the change of surface construction after electrical stress. The feature of silicone rubber, a good hydrophobicity, is demanded the improvement method as the estimation of the non-ceramic insulators like it.

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Degradation rate of several types of Calcium Polyphosphate;Long term results (다양한 형태의 다공질 Calcium Polyphosphate의 생분해성에 관한 장기적인 연구)

  • Yang, S.M.;Seol, Y.J.;Kye, S.B.;Lee, I.K.;Lee, C.W.;Kim, S.Y.;Lee, Yong-Mu;Ku, Y.;Han, S.B.;Chung, C.P.;Choi, S.M.;Rhyu, I.C.
    • Journal of Periodontal and Implant Science
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    • v.33 no.2
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    • pp.301-310
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    • 2003
  • The purpose of this study is to evaluate the biocompatibility and the biorsorbability of several types of calcium polyphosphate made through change of manufacturing process for 12 month. To solve limitation of calcium phosphate, we developed a new ceramic, Calcium Polyphosphate(CPP), and report the biologic response to CPP in extraction sites of beagle dog. Porous CPP blocks were prepared by condensation of anhydrous $Ca(H_2PO_4)_2$ to form non-crystalline $Ca(PO_3)_2$ and then milled to produce CPP powder. CPP powder, CPP block, and CPP granules added with $Na_2O$ were implanted in extraction sockets and histologic observation were performed at 12 months later. Like 3 months results, histologic observation at 12 months revealed that CPP matrix were mingled with and directly apposed to new bone without any adverse tissue reaction, CPP powder show direct bony contact, but new bone formation and fibrous tissue encapsulation showed in CPP block. 10% $Na_2O$ CPP granules show more inflammatory cells infiltration around graft materials compared at 3 month, but 15% $Na_2O$ CPP granules show less. This result revealed that regardless of addition of $Na_2O$, CPP had a high affinity for bone and had been resorbed slowly. From this results, it was suggested that CPP is promising ceramic as a bone substitute and addition of $Na_2O$ help biodegradation but optimal concentration of $Na_2O$ and other additive component to increase degradation rate should be determined in further study.

Uniformity Optimization of TFTs Fabricated on 2-shot SLS-Processed Si Films

  • Turk, Brandon A.;Wilt, P.C. Van Der;Crowder, M.A.;Voutsas, A.T.;Limanov, A.B.;Chung, U.J.;Im, James S.
    • 한국정보디스플레이학회:학술대회논문집
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    • 2006.08a
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    • pp.1750-1755
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    • 2006
  • Nonoptimal placement of short-channel-length TFTs in large-grained polycrystalline Si films with a periodic microstructure, as for instance obtained via 2-shot SLS, can potentially lead to degradation in the overall uniformity of the resultant devices. In this paper, we explain and demonstrate that by simply introducing a well-defined misorientation between the devices and the periodic microstructure, it is possible to significantly reduce (and potentially entirely eliminate) the device nonuniformity problem that can arise from such a cause.

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An Improvement of Sensorless Driving Performance for Brushless DC Motor Using Variable PWM Switching Frequency (가변 PWM 스위칭 주파수를 이용한 브러시리스 직류전동기의 센서리스구동 특성개선)

  • Woo, Hyuk-J.;Song, Myung-H.;Park, Kyu-N.;Yeo, Hyeong-G.;Kim, Kyoung-M.
    • Proceedings of the KIEE Conference
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    • 1999.07f
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    • pp.2534-2536
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    • 1999
  • This paper suggested a new sensorless driving strategy for brushless de motor which can improve the conventional degradation of highspeed operating performances, lowspeed operating performances and starting performances caused by applying general single pwm switching frequency. By varying PWM switching frequency during operating time, the proposed method can get some desired upper performances. For confirming the validity of the proposed method, the sensorless driving system is implemented with an rPM module and 87c196MC micro controller.

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Identification of a Deoxyribonuclease I Inhibitor from a Phage-Peptide Library

  • Choi, Suk-Jung;Sperinde, Jeffrey J.;Szoka, Francis C. Jr.
    • Molecules and Cells
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    • v.19 no.1
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    • pp.54-59
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    • 2005
  • Deoxyribonuclease I (DNase I) is a divalent cation dependent endonuclease and thought to be a significant barrier to effective gene delivery. The only known DNase I-specific inhibitor is monomeric actin which acts by forming a 1:1 complex with DNase I. Its use, however, is restricted because of tendency to polymerize under certain conditions. We screened two random phage peptide libraries of complexity $10^8$ and $10^9$ for DNase I binders as candidates for DNase I inhibitors. A number of DNase I-binding peptide sequences were identified. When these peptides were expressed as fusion proteins with Escherichia coli maltose binding protein, they inhibited the actin-DNase I interaction ($IC_{50}=0.1-0.7{\mu}M$) and DNA degradation by DNase I ($IC_{50}=0.8-8{\mu}M$). Plasmid protection activity in the presence of DNase I was also observed with the fusion proteins. These peptides have the potential to be a useful adjuvant for gene therapy using naked DNA.

Identification of Two-Component Regulatory Genes Involved in o-Xylene Degradation by Rhodococcus sp. Strain DK17

  • Kim, Doc-Kyu;Chae Jong-Chan;Zylstra Gerben J.;Sohn Ho-Yong;Kwon, Gi-Seok;Kim, Eung-Bin
    • Journal of Microbiology
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    • v.43 no.1
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    • pp.49-53
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    • 2005
  • Putative genes for a two-component signal transduction system (akbS and akbT) were detected near the alkylbenzene-degrading operon of Rhodococcus sp. DK17. Sequence analysis indicates that AkbS possesses potential ATP-binding and histidine autophosphorylation sites in the N- and C-terminal regions, respectively, and that AkbT has a typical response regulator domain. Mutant analysis combined with RT-PCR experiments further shows that AkbS is required to induce the expression of o-xylene dioxygenase in DK17.