• Title/Summary/Keyword: current decay

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Coastally Trapped Waves over a Double Shelf Topography(III) : Forced Waves and Circulations Driven by Winds in the Yellow Sea (양향성 대륙붕의 대륙붕파 (III): 강제파와 황해에서의 바람에 의한 해수순환)

  • PANG Ig-Chan
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.25 no.6
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    • pp.457-473
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    • 1992
  • The first order wave equation over a double shelf has wind stresses on both coastal boundaries and wind stress curl forcing across the shelf. In the Yellow Sea, the effect of wind stress curl can be neglected as a forcing of shelf waves. The decay distance of Kelvin waves is much greater than that of continental shelf waves so that Kelvin waves are transmitted nearly intact through the northern embayment. The numerical method of characteristics has been modified to accomodate wave propagation of opposite directions. Using a little more realistic coastline, the wave model hindcast has been improved for current velocity, but hardly for sea level. It means that Kelvin waves, which mainly determine sea levels, are affected little by the change of bottom slope. For a better hindcast of sea level, input energy of Kelvin waves transmitted from the East China Sea is needed. The basic structure of downwind flows along the coasts and upwind flows along the trough supports the seasonal circulations driven by monsoon winds in the Yellow Sea.

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Blockade of Kv1.5 by paroxetine, an antidepressant drug

  • Lee, Hyang Mi;Hahn, Sang June;Choi, Bok Hee
    • The Korean Journal of Physiology and Pharmacology
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    • v.20 no.1
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    • pp.75-82
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    • 2016
  • Paroxetine, a selective serotonin reuptake inhibitor (SSRI), has been reported to have an effect on several ion channels including human ether-a-go-go-related gene in a SSRI-independent manner. These results suggest that paroxetine may cause side effects on cardiac system. In this study, we investigated the effect of paroxetine on Kv1.5, which is one of cardiac ion channels. The action of paroxetine on the cloned neuronal rat Kv1.5 channels stably expressed in Chinese hamster ovary cells was investigated using the whole-cell patch-clamp technique. Paroxetine reduced Kv1.5 whole-cell currents in a reversible concentration-dependent manner, with an $IC_{50}$ value and a Hill coefficient of $4.11{\mu}M$ and 0.98, respectively. Paroxetine accelerated the decay rate of inactivation of Kv1.5 currents without modifying the kinetics of current activation. The inhibition increased steeply between -30 and 0 mV, which corresponded with the voltage range for channel opening. In the voltage range positive to 0 mV, inhibition displayed a weak voltage dependence, consistent with an electrical distance ${\delta}$ of 0.32. The binding ($k_{+1}$) and unbinding ($k_{-1}$) rate constants for paroxetine-induced block of Kv1.5 were $4.9{\mu}M^{-1}s^{-1}$ and $16.1s^{-1}$, respectively. The theoretical $K_D$ value derived by $k_{-1}/k_{+1}$ yielded $3.3{\mu}M$. Paroxetine slowed the deactivation time course, resulting in a tail crossover phenomenon when the tail currents, recorded in the presence and absence of paroxetine, were superimposed. Inhibition of Kv1.5 by paroxetine was use-dependent. The present results suggest that paroxetine acts on Kv1.5 currents as an open-channel blocker.

Modem Leadership Wisdoms from Tasan's Ideology-Centered Upon the Connection between Leadership of Generals and MokMinShimSuh (다산 사상에서 찾는 현대 리더십의 지혜-고급제대 리더십과 목민심서의 연계를 중심으로)

  • Kim, Jong-Du
    • Journal of National Security and Military Science
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    • s.4
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    • pp.45-82
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    • 2006
  • This paper seeks to search for wisdoms that may be applied to modern leadership through Tasan Jeong Yakyong's ideology, ShilHak, from the Chosun Dynasty. The present period is referred as the period of transformation and innovation or the period of knowledge information The leadership appropriate for the current period is thus called revolutionary leadership. This leadership accomplishes its goals by influencing the constituent's values, ethics, behavioral norms, and visions based on the leader's moral values, knowledge, and information. Thus, the essence of this paper is in acquiring wisdoms of leadership by company revolutionary leadership with Tasan's life. Tasan pursued change and innovation in a time where Chosun was in a state of decay by following the flow of world powers towards the concept of studying truth based upon facts such as changing the system of thought, reforming legislation, and developing technology. Moreover, he gave courage and hope to the people by demonstrating such leadership in practice. In addition, despite false accusations and spending 18 years in exile, he showed revolutionary life as an active intellectual by leaving 542 volumes of writing through his 'value innovation' that he "pursue things only for the people and the state." Consequently, the paper first deals with what kind of leadership is required for a leader in the position of a general and examines the kind of leadership capacity demanded. Subsequently, Tasan 's revolutionary life and hints of leadership messages in MokMinSimSuh are examined. Thus, this paper is centered upon the leadership of generals regarding how MokMinShimSuh may be applicable to modern leadership.

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Improving the Standoff Compensation in a Density Log (밀도검층 이격보정에 있어서의 기법 개선에 관한 연구)

  • Kim, Jongman;Park, Sung Geun;Jung, Dabin;Kim, Yeonghwa
    • The Journal of Engineering Geology
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    • v.25 no.4
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    • pp.525-532
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    • 2015
  • After comparing the effectiveness of standoff compensation between current techniques using data obtained from a series of borehole model experiments for standoff compensation in 2007, 2008, and 2009, a follow-up study was conducted to find a more effective standoff compensation algorithm, Comparing the results of the application of the conventional spine and ribs technique, and the spine and ribs technique in terms of apparent density shows that the standoff compensation error obtained from the latter method is more than twice that obtained from the former. The larger size of the compensation error from the spine and ribs plot using the radioactive decay equation indicates that there are no benefits in using this equation in standoff compensation. Based on these results, we propose a reverse transform spine and ribs technique by essentially combining the conventional spine and ribs technique and the spine and ribs technique in terms of apparent density.

Analysis of oral health-related smartphone applications (구강건강 관련 스마트폰 애플리케이션 분석)

  • Jung, Jae-Yeon;Kim, Soo-Hwa
    • Journal of Korean society of Dental Hygiene
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    • v.19 no.4
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    • pp.493-502
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    • 2019
  • Objectives: This study aimed to investigate the current status of oral health applications developed for smartphones because they can be used as a new educational medium to manage and improve oral health. Methods: This study examined 60 basic oral health applications provided by Google Play Store and Apple App Store as of May 2019 and examined delivery contents, delivery methods, application types, and other information. Results: Apple included 65.4% of oral apps in the game category whereas Android included 64.3% in the education category (p>0.05). All Apple's apps and 71.4% of Android apps were developed overseas (p<0.01). The delivery contents were 61.5% for Brushing + tooth decay in Apple, and 78.6% for others (oral care products and gum diseases) in Android (p>0.05). For the delivery method, game + video was 65.4% in Apple, and game and other methods (text, image, augmented reality) was 42.9% in Android (p>0.05). In the case of application type, play type was the most common with 88.5% in Apple, and 46.4% play type and 39.3% other type (text, appreciation, problem-solving types) in Android (p<0.01). In addition, play type was high in both education (53.8%) and game (90.0%) categories (p>0.05). The average review score was 4.30 in the education category, 4.34 in the case of brushing and care (delivery contents), 4.37 in the case of using game + video (delivery methods), and 4.57 in the case of Play + other types (application type) (p>0.05). Conclusions: The use of healthcare apps is expected to increase owing to improved lifestyles, an increase in the elderly population, cost-effectiveness, and convenience that is not affected by time and place. Effective use of oral health apps will require the participation of dental professionals in the development process to identify the exact status, expand subjects, and provide appropriate information.

Enhancement of Electrochemical Activity of Ni-rich LiNi0.8Mn0.1Co0.1O2 by Precisely Controlled Al2O3 Nanocoatings via Atomic Layer Deposition

  • Ramasamy, Hari Vignesh;Sinha, Soumyadeep;Park, Jooyeon;Gong, Minkyung;Aravindan, Vanchiappan;Heo, Jaeyeong;Lee, Yun-Sung
    • Journal of Electrochemical Science and Technology
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    • v.10 no.2
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    • pp.196-205
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    • 2019
  • Ni-rich layered oxides $Li(Ni_xCo_yMn_z)O_2$ (x + y + z = 1) have been extensively studied in recent times owing to their high capacity and low cost and can possibly replace $LiCoO_2$ in the near future. However, these layered oxides suffer from problems related to the capacity fading, thermal stability, and safety at high voltages. In this study, we use surface coating as a strategy to improve the thermal stability at higher voltages. The uniform and conformal $Al_2O_3$ coating on prefabricated electrodes using atomic layer deposition significantly prevented surface degradation over prolonged cycling. Initial capacity of 190, 199, 188 and $166mAh\;g^{-1}$ is obtained for pristine, 2, 5 and 10 cycles of ALD coated samples at 0.2C and maintains 145, 158, 151 and $130mAh\;g^{-1}$ for high current rate of 2C in room temperature. The two-cycle $Al_2O_3$ modified cathode retained 75% of its capacity after 500 cycles at 5C with 0.05% capacity decay per cycle, compared with 46.5% retention for a pristine electrode, at an elevated temperature. Despite the insulating nature of the $Al_2O_3$ coating, a thin layer is sufficient to improve the capacity retention at a high temperature. The $Al_2O_3$ coating can prevent the detrimental surface reactions at a high temperature. Thus, the morphology of the active material is well-maintained even after extensive cycling, whereas the bare electrode undergoes severe degradation.

Long-Term Shelf Lifetime of Polymer:Nonfullerene Solar Cells Stored under Dark and Indoor Light Environment

  • Lee, Sooyong;Kim, Hwajeong;Kim, Youngkyoo
    • Current Photovoltaic Research
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    • v.8 no.4
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    • pp.107-113
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    • 2020
  • Here we report the long-term stability of polymer:nonfullerene solar cells which were stored under dark and indoor light condition. The polymer:nonfullerene solar cells were fabricated using bulk heterojunction (BHJ) layers of poly[(2,6-(4,8-bis(5-(2-ethylhexyl) thiophen-2-yl)-benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione))] (PBDB-T) and 3,9-bis(6-methyl-2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3-d']-s-indaceno[1,2-b:5,6-b']dithiophene (IT-M). To investigate their long-term stability, the PBDB-T:IT-M solar cells were stored in an argon-filled glove box. One set of the fabricated solar cells was completely covered with an aluminum foil to prevent any effect of light, whereas another set was exposed to indoor light. The solar cells were subjected to a regular performance measurement for 40 weeks. Results revealed that the PBDB-T:IT-M solar cells underwent a gradual decay in performance irrespective of the storage condition. However, the PBDB-T:IT-M solar cells stored under indoor light condition exhibited relatively lower power conversion efficiency (PCE) than those stored under the dark. The inferior stability of the solar cells under indoor light was explained by the noticeably changed optical absorption spectra and dark spot generation, indicative of degradations in the BHJ layers.

Spectral Inversion of Time-domain Induced Polarization Data (시간영역 유도분극 자료의 Cole-Cole 역산)

  • Kim, Yeon-Jung;Cho, In-Ky
    • Geophysics and Geophysical Exploration
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    • v.24 no.4
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    • pp.171-179
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    • 2021
  • We outline a process for estimating Cole-Cole parameters from time-domain induced polarization (IP) data. The IP transients are all inverted to 2D Cole-Cole earth models that include resistivity, chargeability, relaxation time, and the frequency exponent. Our inversion algorithm consists of two stages. We first convert the measured voltage decay curves into time series of current-on time apparent resistivity to circumvent the negative chargeability problem. As a first step, a 4D inversion recovers the resistivity model at each time channel that increases monotonically with time. The desired intrinsic Cole-Cole parameters are then recovered by inverting the resistivity time series of each inversion block. In the second step, the Cole-Cole parameters can be estimated readily by setting the initial model close to the true value through a grid search method. Finally, through inversion procedures applied to synthetic data sets, we demonstrate that our algorithm can image the Cole-Cole earth models effectively.

Impact of Oxygen Annealing on Deep-level Traps in Ga2O3/SiC Photodetectors (산소 후열처리에 따른 Ga2O3/SiC photodetector의 전기 광학적 특성)

  • Seung-Hwan Chung;Tae-Hee Lee;Soo-Young Moon;Se-Rim Park;Hyung-Jin Lee;Geon-Hee Lee;Sang-Mo Koo
    • Journal of IKEEE
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    • v.27 no.3
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    • pp.288-295
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    • 2023
  • In this work, we investigated the role of oxygen annealing on the performance of Metal-Semiconductor-Metal (MSM) UV photodetector (PD) fabricated by radio frequency (RF)-sputtered Ga2O3 films on SiC substrates. Oxygen-nnealed Ga2O3 films displayed a notable increase in photocurrent and a faster decay time, indicating a decrease in persistent photoconductivity. This improvement is attributed to the reduction of oxygen vacancies and variation of defects by oxygen post-annealing. Our findings provide valuable insights into enhancing PD performance through oxygen annealing.

Experimental Techniques for Surface Science with Synchrotron Radiation

  • Jonhnson, R.L.;Bunk, O.;Falkenberg, G.;Kosuch, R.;Zeysing, J.
    • Proceedings of the Korean Vacuum Society Conference
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    • 1998.02a
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    • pp.17-17
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    • 1998
  • Synchrotron radiation is produced when charged particles moving with relativistic velocities a are accelerated - for example, deflected by the bending magnets which guide the electron or p positrons in circular accelerators or storage rings. By using special focusing magnetic lattices i in the particle accelerators it is possible to make the dimensions of the particle beam very small with a hi맹 charge density which results in a light source with high b디lIiance. Synchrotron light h has important properties which make it ideal for a wide range of investigations in surface s science. The fact that the spectrum of electromagnetic radiation emitted in a bending magnet e extends in a continuum from the 얹r infra red region to hard x-rays means that it is id않I for a v variety of spectroscopic studies. Since there are no convenient lasers, or other really bright l light sources, in the vacuum ultraviolet and soft x-ray re.밍ons the development of synchrotron r radiation has enabled enormous advances to be made in this di펌C비t spectr따 re밍on. P Polarization-dependent measurements, for ex없nple ellipsometry or circular dichroism studies a are possible because the radiation has a well-defined polarization - linear in the plane of orbit w with additional right-circular, or left-circular, components for emission an생es above, or below, t the horizontal, respectively. Since the synchrotron light is emitted from a bunch of charge c circulating in a ring the light is emitted with a well-defined time structure with a short flash of l light every time a bunch passes an exit port. The time structure depends on the size of the ring a and the number and sequence of filling of the bunches. A pulsed light source enables time¬r resolved studies to be performed which provide direct information on the lifetimes and decay m modes of excited states and in addition opens up the possibility of using time of flight t techniques for spectroscopic studies. The fact that synchrotron radiation is produced in a clean u ultrahi야 vacuum environment is of gr않t importance for surce science studies. The current t비rd generation synchrotron light sources provide exceptionally high baliance and stability a and open up possibilities for experiments which would have been inconceivable only a short time ago.

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