• Title/Summary/Keyword: 2DEG

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Purification and characterization of an extracellular protease from culture filtrate of salmonella schttmulleri

  • Na, Byoung-Kuk;Song, Chul-Yong
    • Journal of Microbiology
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    • v.33 no.3
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    • pp.244-251
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    • 1995
  • An extracellular protease of Salmonella schottmulleri was purified from culture filtrate by using 0-75% ammonium sulfate precipitation, DEAE Sepharose Fast Flow ion exchange chromatography, Ultrogel HA chromatography and Sephacryl S-200 HR molecular sieve chromatography. To measure enzyme activity, synthetic dipeptide substrate (CBZ-arg-arg-AFC) with low molecular weight was employed as substrate. The molecular weight of the purified enzyme was approximately 80 kDa when determined by gel filtration on Sephacryl S-200 HR and 73 kDa when estimated by SDS-PAGE. The isoelectric point was 5.45. The activity of the purified enzyme was inhibited by metal chelating agesnts such as EDTA and 1.10-phenanthroline. The divalent cations, such as Ca$\^$2+/, Zn$\^$2+/, Fe$\^$2+/, Mg$\^$2+/ enhanced its activity. These results suggested that it was a metalloprotease. It had a narrow pH optimum of 6.5-7.5 with a maximum at pH 7.0 and a temperature optimum of 40.deg.C. It was stable at least for 1 week at 40.deg.C and maintained its activity for 24 hours at 50.deg.C, but it was rapidly inactivated at 65.deg.C. This protease was shown to be sensitive to sodium 50.deg.C, but it was rapidly inactivated at 65.deg.C. This protease was shown to be sensitive to sodium 50.deg.C, but it was rapidly inactivated at 65.deg.C. This protease was shown to be sensitive to sodium 50.deg.C, but it was rapidly inactivated at 65.deg.C. This protease was shown to be sensitive to sodium dodecyl sulfate (SDS) and was inactivated in a dose-dependent manner. However, it was resistant to Triton X-100 and the activity was enhanced to 32.3% with treatment of 0.025% Triton X-100.

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2DEG Transport Analysis in AlGaAs/GaAs Interface by MONTE-CARLO Method (MONTE-CARLO 방법에 의한 AlGaAs/GaAs 계면의 전자 전달특성 분석)

  • Nam, Seung-Hun;Jung, Hak-Ki;Kim, Bong-Ryul
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.26 no.2
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    • pp.94-101
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    • 1989
  • Transport properties of 2DEG at AlGaAs/GaAs interface such as average electron energy, flight distance, each valley occupancy ratio, average electron velocity for various fields are investigated by MONTE-CARLO method. As the electric field increases, more electrons transit drastically from (000) valley to (000) upper valley. This phenomenon shows the nonstationary effect such as velocity overshoot. The duration of the transient decreases from about 1.4 psec for electric field E = 7KV/cm to about 0.7 psec for 12KV/cm. The average electron velocity during transient transport in 2DEG is about 8 times the steady-state velocity for E = 12KV/cm at room temperature. In comparison with bulk GaAs the peak velocity in the 2DEG is higher than that in even pure bulk GaAs at electric field E = 7 KV/cm. On the basis of the fact that the electrons in the 2DEG have larger peak velocity and shorter transient time of velocity than those in the bulk GaAs, it is suggested that the device with 2DEG may obtain higher mobility than that with bulk GaAs.

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Quantum Mechanical Analysis for the Numerical Calculation of Two-Dimensional Electron Gas(2DEG) (2 차원 전자개스(2DEG)의 수치적 연산을 위한 양자역학적 분석)

  • 황광철;김진욱;류세환;안형근;한득영
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1999.11a
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    • pp.441-444
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    • 1999
  • This paper analyzed arbitrary Energy band profile heterostructures by solving Schrodinger\`s equation the Poisson's equation self-consistently. Four different concentrations positively ionized donors holes in the valence band free electrons in the conduction band and 2DEG are taken to account for the whole system. 2DEG from both of the structures are obtained and compared with the data available in the literatures. Differential capacitances are also calculated from the concentration profiles obtained. Finally theoretical predictions for both of 2DEGs and the capacitances show good agreement with the experimental data referred in this study.

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Quantum Mechanical Analysis for the Numerical Calculation of Two-Diemensional Electron Gas(2DEG) in Single-Heterojunction Structures (단일 이종접합 구조에서의 2차원 전자개스(2DEG)의 수치적 연산을 위한 양자역학적 분석)

  • Hwang, Kwang-Chuel;Kim, Jin-Wook;Won, Chang-Sub;Ahn, Hyung-Keun;Han, Deuk-Young
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.49 no.10
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    • pp.564-569
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    • 2000
  • This paper analyzed single AlGaAs/GaAa heterojunction energy band structures by solving Schr dinger's equation and Poisson's equation self-consistently. Four different concentrations, positively ionized donors, holes in the valence band, free electrons in the conduction band and 2DEG are taken into account for the whole system. 2DEG from both of the structures are obtained and compared with the date available in the literatures. Differential capacitances are also calculated from the concentration profiles obtained to prove the validity of the single AlGaAs/GaAs system. Finally, theoretical predictions for both of 2DEGs and the capacitances show good agreement with the experimental data referred in this study. It has only an error of les than 10 percent.

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POLAROGRAPHIC STUDIES ON METAL COMPLEXES OF IMIDAZOLE, 2-METHYL-IMIDAZOLE and 2-(1-NAPHTHYLMETHYL)-IMIDAZOLE (Imidazole및 그 유도체의 금속착염에 관한 Polarograph연구)

  • 김준용;류경수;백남호
    • YAKHAK HOEJI
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    • v.14 no.1_2
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    • pp.36-43
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    • 1970
  • Imidazole및 유사화합물과 천이원소간의 착염형성은 생화학적으로도 중요한 문제다. 본 논문은 Cd, Ni, Mn, Co등과 착염형성을 polarograph법으로 구명하였으며 착염형성 상수는 deford및 Hume의 수학적방법을 적용하여 계산하였다. 착염형성에서의 enthalpy 변화, .DELTA.H$^{.deg.}$ , 및 entropy변화, .DELTA.S$^{.deg.}$ 를 25.deg.C와 35.deg.C의 실험에서 얻은 결과로부터 구하였다.

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Fabrication of Barium Oxide Ferrite Magnet-II (바리움 훼라이트 자석의 시작 - II)

  • 백용현
    • 전기의세계
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    • v.21 no.6
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    • pp.17-20
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    • 1972
  • The magnetic properties of Ba-Ferrite ( $M^{+2}$O.nF $e_{2}$ $O_{3}$ is highly improved under the condition of composition ratio n=4.4 when B $i_{2}$ $O_{3}$ is added to Ferrite, the adding amount and sintering temperature which affect the magnetic properties were investigated and the following results; were obtained; 1. Magnetic properties are varied with B $i_{2}$ $O_{3}$ content and singering temperature, and coercive force and residual induction can be improved with B $i_{2}$ $O_{3}$. 2. The optimal content of B $i_{2}$ $O_{3}$ amount is about 4 mol %, 3. Without the addition of B $i_{2}$ $O_{3}$, the optimal sintering temperature is about 1300.deg. C, but when 4 mol % of B $i_{2}$ $O_{3}$ is added, the optimal sintering temperature falls to the range of 900.deg. C to 1100.deg. C and it also improves magnetic properties. 4. Residual induction increases as the singering temperature is raised to 1100.deg. C. Coercive force also increased as the sintering temperature is raised to 1000.deg. C, but it rapidly decreases when sintering temperature goes beyond 1000.deg. C. 5. Only a negligible change may be noticed in the decrease of Curie temperature by the addition of about 4 mol % of B $i_{2}$ $O_{3}$.

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A Study on the Impact-Induced Damage in CFRP Angle-ply Laminates (CFRP 사교적층판의 충격손상에 관한 연구)

  • 배태성;입야영;양동률
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.2
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    • pp.237-247
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    • 1993
  • Carbon fiber reinforced plastics(CFRP) have gained increased application in aerospace structures because of their specific strength and stiffness, but are sensitive to impact-induced damage. An experimental investigation was carried out to evaluate the impact resistance of CFRP according to the ply angle. The specimens of angle ply laminate composites were employed with [0.deg. $_{6}$/ .deg.$_{10}$/0.deg.$_{6}$], in which 6 kinds of ply angle such as .deg.=15.deg., 30.deg., 45.deg., 60.deg., 75.deg. and 90.deg. were selected. The impact tests were conducted using the air gun type impact testing machine by steel balls of diameter of 5 mm and 10 mm, and impact-induced damages were evaluated under same impact speed of V=60m/s. The impact damaged zones were observed through a scanning acoustic microscope (SAM). The obtained results were summarized as follows: (1) Delaminations on the interfacial boundaries showed th directional characteristics to the fiber directions. The delamination area on the impact side (interface A) was considerably smaller compared to that of the opposite side (interface B). (2) Cracks corresponding to other delaminations than those mentioned in SAM photographs were also seen on the impact damaged zone. (3) The delamination patterns were affected by the ply-angle, the dimensions of the specimen, and the boundary conditions. (4) The impact damaged zone showed zone showed the delamination on the interfacial boundaries, transverse shear cracks of the surface layer, and bending cracks of the bottom layer.r.r.r.

The Fabrication of PVDF Organic Thin Films by Physical Vapor Deposition Method and Their Electrical Conductivity Phenomena (진공증착법을 이용한 PVDF 유기박막의 제조와 전기전도현상)

  • 임응춘;이덕출
    • Electrical & Electronic Materials
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    • v.10 no.3
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    • pp.217-225
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    • 1997
  • In this study, the PVDF organic thin film was fabricated by the physical vapor deposition method to be dry-process. The distance of heat source and substrate was 5[cm] and the temperature of substrate was 30[.deg. C], when the pressure had reached 2.0 x 10$^{-5}$ [Torr], the temperature of heat source was reached to 285[.deg. C] to heat at 6-8[.deg. C/min] rate, the shutter was opened and deposition was started. TG-DTA(Thermogravimetric-Differential Thermal Analysis) spectrum of PVDF pellets showed that endothermic peak arose at 170[.deg. C] and exothermic peak at 524[.deg. C], but that of thin PVDF film showed that endothermic peak arose at 145[.deg. C] and exothermic peak at 443[.deg C]. The current density was increased linearly with increasing voltage but increased nonlinearly with higher electric field than 250[kV/cm] and activation energy was about 0.667[eV] at the temperature of 30-90[.deg. C].

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The Kinematical Analysis of Straddle Jump to Push up Motion on Sports Aerobics (스포츠 에어로빅스 Straddle Jump to Push up 동작의 운동학적 분석)

  • Kim, Cha-Nam
    • Korean Journal of Applied Biomechanics
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    • v.12 no.2
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    • pp.77-90
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    • 2002
  • This study serves the purpose of understanding about correct jump and landing motion through Kinematical Analysis of Straddle Jump to Push up Motion at target by four elite sports aerobics athletes have more than four years career. And further more that make good assistance for coaches effective guidance through an offer basic data and correct diagnosis, evaluate of motions. It was picture-taked by two-video camera for Straddle Jump to Push up Motions. Camera speeds are 60 frame/sec. There are Kinematical Variation elements for analysis, the displacement of COG, each angle displacement left/right of shoulder-joint, each angle displacement left/right of knee-joint and each speed left/right of tip of the toes. Every each person accomplished severaly 3 times and we have acquired this conclusion. The conclusions were as follows; 1. Each situation for displacement of COG showed low height of COG by phase 1, 4, 5(79.05${\pm}9.07,\;46.41{\pm}3.65,\;18.66{\pm}0.54cm$) and It showed high height of COG by phase 2, 3($120.80{\pm}6.13,\;148.12{\pm}9.19cm$). 2. Each displacement left, right of shoulder-joint flexion by phase 1($91.07{\pm}8.30,\;90.77{\pm}5.72$deg/sec)and It showed maximal extension angles by phase 2($102.48{\pm}10.00,\;102.39{\pm}10.51$deg/sec). in part of phase 3, left of shoulder-joint angle($94.43{\pm}4.12$deg/sec) showed flexion phase 1, the other right shoulder-joint angle(88.38${\pm}$4.98deg/sec) showed more a little lower than phase 1, in last phase that showed most low by phase 4($70.58{\pm}13.72,\;54.24{\pm}11.58$deg/sec). 3. Each displacement left, right of hip joint showed maximal extent conditions by phase 2, 3($160.35{\pm}22.68,\;1534.77{\pm}5.40$deg/sec, $150.04{\pm}12.79,\;145.54{\pm}13.00$deg/sec) beside, ankle-joint showed minimal angle by phase 1, 4($93.59{\pm}18.92,\;85.37{\pm}13.23$deg/sec, $66.60{\pm}15.77,\;80.60{\pm}16.57$deg/sec). 4. Each displacement left, right of hip joint showed maximal extent conditions by phase 2($157.15{\pm}9.13,\;163.52{\pm}8.18$deg/sec), and right of hip joint showed minimal angle by phase 3($110.87{\pm}13.81,\;77.53{\pm}8.95$deg/sec) It showed alike condition of low angle by phase 1, 4($91.04{\pm}2.31,\;96.26{\pm}2.20$deg/sec). 5. Each displacement left, right of knee-joint showed maximal extent conditions by phase 1, 3, 4($173.46{\pm}2.95,\;171.51{\pm}5.44$deg/sec, $172.24{\pm}4.49,\;171.26{\pm}0.65$deg/sec, $162.78{\pm}2.13,\;164.10{\pm}5.97$deg/sec) but It showed flexion only left of knee-joint by phase 2($164.45{\pm}7.51,\;159.38{\pm}3.48$deg/sec). 6. Each speed left, right of the tip of the toes showed most fastest when someone jumped with lift up leges by phase 1, 2($321.32{\pm}67.91,\;316.90{\pm}41.97$cm/sec, $410.06{\pm}153.06,\;399.77{\pm}189.34$cm/sec), It showed more less speed than phase 1,2 by phase 3($169.74{\pm}67.17,\;150.00{\pm}63.80$cm/sec) and It showed most slow speed than phase 1,2,3 by phase 4($87.22{\pm}34.90,\;85.72{\pm}52.23$cm/sec).

An Experimental Study on the Melting of a Horizontal Cylindrical Ice-Bar Submerged in Water (물속에 水平으로 잠겨 있는 圓 形 얼음 棒 의 融解現象 에 관한 實驗的 硏究)

  • 이동욱;유상신
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.9 no.4
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    • pp.414-420
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    • 1985
  • The melting phenomenal of the horizontal cylindrical ice-bar submerged in water are experimentally investigated for the temperature range from 2.5.deg. C to 15.deg. C. The shapes of the melting ice-bar are recorded by the Photo-elasticity Apparatus with modification of the test section. The shadowgraphs of the melting ice-bar show that water adjacent to the bar flows upward for the temperature range from 2.5.deg. C to 5.6.deg. C while above the temperature of 5.6.deg. C the flow is downward direction. The local and average Nusselt numbers become minimum at 5.6.deg. C which is considered as a critical temperature and the Nusselt numbers increase as temperature difference from the critical temperature increase.