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  • Title/Summary/Keyword: Pulse-on duration

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Measuring and Generation the speed of reaction wheel for Spacecraft Dynamic Simulator using the T-Method (위성동역학 시뮬레이터용 T-방식을 이용한 반작용휠 속도 측정 및 펄스 생성)

  • Kim, Yong-Bok;Oh, Si-Hwan;Lee, Seon-Ho;Yong, Ki-Lyok;Rhee, Seung-Wu
    • Aerospace Engineering and Technology
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    • v.6 no.1
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    • pp.74-82
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    • 2007
  • The M-Method that measures the speed of actuator with counting the number of Reaction wheel Tacho Pulse has the many advantages such that a realization is simple and measuring time is uniform, but it also has the disadvantage that measuring speed becomes worse as the wheel speed goes lower. On the contrary, the T-Method that measures the time duration between the pulses is more accurate at lower-speed and its time delay is smaller than M-Method, but its realization is more difficult than M-Method because measuring time is varying with wheel speed variation. Thought M/T Method mixing M-Method with T-Method is widely used in order to measure the speed in the motor industrial area, one of two methods has been used in the spacecraft design area. Therefore, we try to apply both methods together to measuring the speed of Reaction Wheel, the core actuator for low earth orbit satellite. This paper provides the Reaction Wheel simulation board located in the Spacecraft Dynamic Simulator, ground support test set.

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Evaluation of Multi-Level Memory Characteristics in Ge2Sb2Te5/TiN/W-Doped Ge2Sb2Te5 Cell Structure (Ge2Sb2Te5/TiN/W-Doped Ge2Sb2Te5 셀 구조의 다중준위 메모리 특성 평가 )

  • Jun-Hyeok Jo;Jun-Young Seo;Ju-Hee Lee;Ju-Yeong Park;Hyun-Yong Lee
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.37 no.1
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    • pp.88-93
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    • 2024
  • To evaluate the possibility as a multi-level memory medium for the Ge2Sb2Te5/TiN/W-doped Ge2Sb2Te5 cell structure, the crystallization rate and stabilization characteristics according to voltage (V)- and current (I)- pulse sweeping were investigated. In the cell structures prepared by a magnetron sputtering system on a p-type Si (100) substrate, the Ge2Sb2Te5 and W-doped Ge2Sb2Te5 thin films were separated by a barrier metal, TiN, and the individual thicknesses were varied, but the total thickness was fixed at 200 nm. All cell structures exhibited relatively stable multi-level states of high-middle-low resistance (HR-MR-LR), which guarantee the reliability of the multilevel phase-change random access memory (PRAM). The amorphousto-multilevel crystallization rate was evaluated from a graph of resistance (R) vs. pulse duration (T) obtained by the nanoscaled pulse sweeping at a fixed applied voltage (12 V). For all structures, the phase-change rates of HR→MR and MR→LR were estimated to be approximately t<20 ns and t<40 ns, respectively, and the states were relatively stable. We believe that the doublestack structure of an appropriate Ge-Sb-Te film separated by barrier metal (TiN) can be optimized for high-speed and stable multilevel PRAM.

The Prognosis of Focal Segmental Glomerulosclerosis Patients with Methylprednisolone Pulse Therapy Alone (Methylprednisolone 충격 요법만 받은 국소성 분절성 사구체 경화증 환아의 예후)

  • Kim, Joung-A;Park, Kwang-Sik;Shin, Jae-Il;Jeong, Il-Cheon;Kim, Ji-Hong;Kim, Pyung-Kil;Jeong, Hyun-Joo;Lee, Jae-Seung
    • Childhood Kidney Diseases
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    • v.11 no.2
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    • pp.178-184
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    • 2007
  • Purpose : Since the first report by Mendoza in 1990, there have been several studies reporting that long-term intravenous methylprednisolone(MP) pulse therapy combined with cyclosporin A(CsA) or cyclophosphamide might be beneficial for the treatment of steroid resistant focal segmental glometulosclerosis(FSGS). We investigated the therapeutic effect of long-term MP pulse therapy without CsA or cyclophosphamide on steroid resistant FSGS. Methods : The medical records of the 10 steroid resistant FSGS patients who were treated with MP pulse therapy by the Mendoza protocol without CsA or cyclophosphamide in our hospital were retrospectively reviewed. Results : The median age at onset was 2.6 years(range 1.1-10.6 years) and the median age at the initiation of therapy was 5.7 years(range 1.8-20 years). The median duration of follow-up was 35 months(range 4-132 months). At the end of therapy, 5 patients achieved complete remission(50%) and 2 partial remission(20%), one of whom relapsed after the therapy. Three patients did not respond to the therapy, two of whom progressed to end-stage renal failure during the therapy eventually requiring kidney transplantation. Conclusion : Intravenous long-term MP pulse therapy without CsA or cyclophosphamide by the Mendoza protocol may be effective in a subset of patients with steroid-resistant FSGS.

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MODIFICATION OF METAL MATERIALS BY HIGH TEMPERATURE PULSED PLASMA FLUXES IRRADIATION

  • Vladimir L. Yakushin;Boris A. Kalin;Serguei S. Tserevitionov
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2000.05a
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    • pp.1-1
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    • 2000
  • The results of the modification of metal materials treated by high temperature pulst:d plasma fluxes (HTlPPF) with a specific power of incident flux changing in the (3...100)105]W/cm2 range and a pulse duration lying from 15 to 50μs have been presented. The results of HTPPF action were studied on the stainless steels of 18Cr-l0Ni, 16Cr- 15Ni, 13Cr-2Mo types; on the structural carbon steels of (13...35)Cr, St. 3, St. 20, St. 45 types; on the tool steels of U8, 65G, ShHI5 types, and others; on nickel and high nickel alloy of 20Cr-45Ni type; on zirconium- and vanadium-base alloys and other materials. The microstructure and properties (mechanical, tribological, erosion, and other properties) of modified materials and surface alloying of metals exposed to HTPPF action have been investigated. It was found that the modification of materials by HTPPF resulted in a simultaneous increase of several properties of the treated articles: microhardness of the surface and layers of 40...60 μm in depth, tribological characteristics (friction coefficient, wear resistance), mechanical properties ({\sigma_y}, {\;}{\sigma_{0.2}}.{\;}{\sigma_r}) on retention of the initial plasticity (δ), corrosion resistance, radistanation erosion under ion irradiation, and others. The determining factor of the changes observed is the structural-phase modification of the near-surface layers, in particular, the formation of the fine cellular structure in the near-surface layers at a depth of 20μm with dimension of cells changing in the range from 0.1 to 1.,5μm, depending on the kind of material, its preliminary treatment, and the parameters of plasma fluxes. The remits obtained have shown the possibility of purposeful surface alloying of metals exposed to HTPPF action over a depth up to 20...45 μm and the concentration of alloying element (Ni, Cr, V) up to 20 wt.%. Possible industrial brunches for using the treatment have been also considered, as well as some results on modifying the serial industrial articles by HTPPF.

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Antispastic Effects of Electroacupuncture, TENS and NMEs in Stroke Patient (중풍경직에 전침, TENS 및 신경근 자극기의 효과에 대한 연구)

  • Kim, Yong-suk
    • Journal of Acupuncture Research
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    • v.17 no.2
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    • pp.209-220
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    • 2000
  • Spasticity, an abnormal increase in resting muscle tone, is one of the most common symptoms of stroke, and its management is becoming a major issue in rehabilitation. The aims of this study are to determine the effects of electroacupuncture(EA), TENS and neuromuscular electric stimulation(NMES) on spasticity, as well as the possibility of tissue comliance method as a spasticity scale. 45 stroke patients participated in a study of the effects on hemiplegic spasticity of EA, TENS and NMES. Spasticity was measured by modified Ashworth scale on the upper extremity and tissue compliance measurement, penetration mm/kg, on Susamni(LI10) area at just before and after stimulation, and 30 minutes, 1 hour, 2 hours and 24 hours after stimulation. The acupuncture points were applied to Kokchi(LI11), Susamni(LI10), Hapkok(LI4) and Oegwan(TE5) of the affected limb. The electrodes were placed unilaterally on LI11 to LI10 and TE5 to LI4. EA with biphasic wave, 60Hz, 0.4 msec pulse duration and low intensity was applied continuously for 20 minutes. TENS with high frequency, low intensity was applied. NMES was applied with spasticity program for 20 minutes. Each electric stimulation was done on extensor muscles group of forearm for 20 minutes. EA and NMES groups were found to produce a statistically significant decrease(p〈0.05) of spasticity and these effects lasted up to 30 minutes after stimulation. There was no definite correlation between the modified Ashworth scale and tissue compliance measurement. But tissure compliance method was found to be possible as a quantitative measurement on spasticity. There was no significant correlation between the effects of EA and NMES and the characteristics of patient, but significant correlation between the effects of EA and NMES and the modified Ashworth scale.

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The Therapeutic Effects of a Pulsed Nd:YAG Laser on Oral Lesions (구강병소에 대한 펄스형 Nd: YAG 레이저의 치료효과)

  • 신금백
    • Journal of Oral Medicine and Pain
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    • v.22 no.2
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    • pp.309-325
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    • 1997
  • In order to set the lasing variables and evaluate, clinically, the therapeutic effects of a pulsed Nd:YAG laser on oral lesion, the author applied the laser energy from a fiberoptic delivered, free running, pulsed Nd:YAG laser (wavelength 1064nm, Pulse duration 120μsec, fiber diameter 200μm/320μm) to 22 cases of oral soft tissue lesions and 6 cases of oral hard tissue lesions. The obtained results were as follows : 1. The effective excision with contact mode and the effective hemostasis of accompanied bleeding with noncontact mode were occurred by lasing on oral soft tissue lesions with fiber diameter of 320μm under the variables of 2.0~4.0W and 20~50Hz which were controlled into high power/low pulses for excision, low power/high pulses for hemostasis, low power in granulation tissue and high power in fibrous tissue according to therapeutic goals and tissue conditions. 2. About 50% of decreasing effect on hypersensitivity was occurred by lasing with non-contact and contact mode on cervical abrasion which caused dentinal hypersensitivity with fiber diameter of 320μm under the variables of 0.7 - 1.0W and 10Hz which were applied 2~3 times with 1 week interval. 3. The effective sterilization of infected root canal and lesion of periapical abscess was occurred by lasing with contact and spiral modes on wall of root canal and periapical abscess with fiber diameter of 200μm of which the tip was placed about 1mm shorter than root canal length under the variables of 1.OW and 10Hz.

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The Effect of Tourniquet Inflation on Neural Functions: A Volunteer Study (정상 성인에서 구혈대에 의한 신경기능의 변화)

  • Jun, Hee-Jeong;Choi, Yoon;Jung, Heon-Seok;Kim, Tae-Yop;Jung, Seong-Yang;Leem, Joong-Woo
    • The Korean Journal of Pain
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    • v.12 no.1
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    • pp.16-20
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    • 1999
  • Background: Tourniquet pain has important impacts on anesthesia. Tourniquet pain and accompanying cardiovascular changes are important factors that make patients in distress during anesthesia. As tourniquet pain may be modified by anesthesia, a study on the changes in the neural functions by tourniquet inflation in normal volunteers is important. Methods: Time-dependent changes in tourniquet pain, heart rate, phantom limb sensation, motor function, pain to pressure on upper extremity of 10 healthy and unpremedied volunteers were measured. Each parameter were measured every 5 minutes starting from 10 minutes before inflation to 15 minutes after deflation of tourniquet. Tourniquet was deflated when the subject felt unbearable pain (score 100 with visual analog scale). Results: Subjects manifested time-dependent pain responses to tourniquet inflation, characterized by increase in VAS, systolic and diastolic blood pressure. Mean duration of tourniquet inflation was 36.4 minutes, volunteers experienced motor paralysis at 27.6 minutes and sensory loss at 33.1 minutes. Pain to pressure decreased over time in both arms. The degree of decrease was greater in the arm on which tourniquet was applied than that in the non-applied arm. Phantom limb sensation occurred in 3 subjects. Conclusions: This study demonstrated dynamic changes in the neural functions during tourniquet inflation period. Tourniquet-induced pain and resultant hypertension occurred in all subjects. Appropriate anesthetic management is needed for the surgery using tourniquet.

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Photoelectrochemical Characteristics for Cathodic Electrodeposited Cu2O Film on Indium Tin Oxide (음극전착법을 이용한 Cu2O 막의 광전기 화학적 특성)

  • 이은호;정광덕;주오심;최승철
    • Journal of the Korean Ceramic Society
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    • v.41 no.3
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    • pp.183-189
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    • 2004
  • Cuprous oxide (Cu2O) thin films are cathodically deposited on Indium Tin Oxide (ITO) substrate. The as-deposited films were heat-treated at 300C to obtain Cu2O. After the heat treatment, the film was changed from Cu metal into Cu2O phase. The phase, morphology and photocurrent density of the films were dependent on the preparation conditions of deposition time, applied voltage, and the duration of heat treatment. The Cu2O films were characterized by X-Ray Diffractometer (XRD) and Scanning Electron Microscope (SEM). The apparent grain size of the films formed by the normal method was larger than those grown by the pulse method. The CU2O film what was deposited at -0.7 V for 300 sec and then, calcined at 300C for 1 h showed the predominant photocurrent density of 1048 μA/cm2. And the stability of Cu2O electrodes were improved with chemically deposited TiO2 thin films on Cu2O.

Effects of Paroxetine on a Human Ether-a-go-go-related Gene (hERG) K+ Channel Expressed in Xenopus Oocytes and on Cardiac Action Potential

  • Hong, Hee-Kyung;Hwang, Soobeen;Jo, Su-Hyun
    • International Journal of Oral Biology
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    • v.43 no.1
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    • pp.43-51
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    • 2018
  • K+ channels are key components of the primary and secondary basolateral Cl pump systems, which are important for secretion from the salivary glands. Paroxetine is a selective serotonin reuptake inhibitor (SSRI) for psychiatric disorders that can induce QT prolongation, which may lead to torsades de pointes. We studied the effects of paroxetine on a human K+ channel, human ether-a-go-go-related gene (hERG), expressed in Xenopus oocytes and on action potential in guinea pig ventricular myocytes. The hERG encodes the pore-forming subunits of the rapidly-activating delayed rectifier K+ channel (IKr) in the heart. Mutations in hERG reduce IKr and cause type 2 long QT syndrome (LQT2), a disorder that predisposes individuals to life-threatening arrhythmias. Paroxetine induced concentration-dependent decreases in the current amplitude at the end of the voltage steps and hERG tail currents. The inhibition was concentration-dependent and time-dependent, but voltage-independent during each voltage pulse. In guinea pig ventricular myocytes held at 36C, treatment with 0.4μM paroxetine for 5 min decreased the action potential duration at 90% of repolarization (APD90) by 4.3%. Our results suggest that paroxetine is a blocker of the hERG channels, providing a molecular mechanism for the arrhythmogenic side effects of clinical administration of paroxetine.

Study on the Structural Stability and Charge Trapping Properties of High-k HfO2 and HFO2/Al2O3/HfO2 Stacks (High-k HfO2와 HfO2/Al2O3/HfO2 적층막의 구조 안정성 및 전하 트랩핑 특성 연구)

  • Ahn, Young-Soo;Huh, Min-Young;Kang, Hae-Yoon;Sohn, Hyunchul
    • Korean Journal of Metals and Materials
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    • v.48 no.3
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    • pp.256-261
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    • 2010
  • In this work, high-k dielectric stacks of HfO2 and HfO2/Al2O3/HfO2 (HAH) were deposited on SiO2/Si substrates by atomic layer deposition as charge trapping layers in charge trapping devices. The structural stability and the charge trapping characteristics of such stacks were investigated using Metal-Alumina-Hafnia-Oxide-Silicon (MAHOS) structure. The surface roughness of HfO2 was stable up to 11 nm with the insertion of 0.2 nm thick Al2O3. The effect of the thickness of the HAH stack and the thickness of intermediate Al2O3 on charge trapping characteristics were investigated for MAHOS structure under various gate bias pulse with duration of 100 ms. The threshold voltage shift after programming and erase showed that the memory window was increased with increasing bias on gate. However, the programming window was independent of the thickness of HAH charge trapping layers. When the thickness of Al2O3insertion increased from 0.2 nm to 1 nm, the erase window was decreased without change in the programming window.