• Title/Summary/Keyword: Rate-capability

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Evaluation of Optimal Transfer Capability in the Haenam-Jeju HVDC System Based on Cost Optimization

  • Son Hyun-Il;Kim Jin-O;Lee Hyo-Sang;Shin Dong-Joon
    • KIEE International Transactions on Power Engineering
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    • v.5A no.3
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    • pp.303-308
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    • 2005
  • The restructure of the electrical power industry is accompanied by the extension of the electrical power exchange. One of the key pieces of information used to determine how much power can be transferred through the network is known as available transfer capability (ATC). The traditional ATC deterministic approach is based on the severest case and it involves a complex procedure. Therefore, a novel approach for A TC calculation is proposed using cost optimization in this paper. The Jeju Island interconnected HVDC system has inland KEPCO (Korean Electric Power Corporation) systems, and its demand is increasing at the rate of about $\10[%]$ annually. To supply this increasing demand, the capability of the HVDC system must be enlarged. This paper proposes the optimal transfer capability of the HVDC system between Haenam in the inland and Jeju in Cheju Island through cost optimization. The cost optimization is based on generating cost in Jeju Island, transfer cost through Jeju-Haenam HVDC system and outage cost with one depth (N-1 contingency).

Ambidexterity and Leadership Agility in Micro, Small and Medium Enterprises (MSME)'s Performance: An Empirical Study in Indonesia

  • KUSTYADJI, Gatot;WINDIJARTO, Windijarto;WIJAYANI, Ari
    • The Journal of Asian Finance, Economics and Business
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    • v.8 no.7
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    • pp.303-311
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    • 2021
  • Ambidexterity and leadership agility have become the most researched topics to analyze their application in companies, especially in this dynamic era. Several researchers have analyzed it in large companies. However, only a few have discussed the two topics simultaneously and at the MSME level. This study aims to analyze the relationship between ambidexterity and leadership agility and innovation capability and performance at MSMEs in Yogyakarta and East Java, Indonesia. This study is analyzed by using quantitative methods with SEM (Structural Equation Model) methods. The data in this study is primary data that is obtained through distributing 230 questionnaires to MSME managers in Yogyakarta and East Java, Indonesia. From 230 questionnaires distributed, 200 questionnaires are returned and completed, so the response rate in this study is 86%. The results in this study indicate that ambidexterity and leadership agility have a significant effect on innovation capability and MSME performance. This study also proved that innovation capability has a significant effect on MSME performance. Therefore, it is recommended for MSME managers to develop ambidexterity and leadership agility so they can create innovation and good performance. In the end, this study has provided findings related to the combination of ambidexterity and leadership agility variables.

Improved Rate Capability of Li/Li3V2(PO4)3 Cell for Advanced Lithium Secondary Battery

  • Lim, Hyun-He;Cho, A-Ra;Sivakumar, Nagarajan;Kim, Woo-Seong;Yoon, Won-Sub;Lee, Yun-Sung
    • Bulletin of the Korean Chemical Society
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    • v.32 no.5
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    • pp.1491-1494
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    • 2011
  • Lithium vanadium phosphate, $Li_3V_2(PO_4)_3$ was prepared by a simple solid state route. It was found that making a fine powder of $Li_3V_2(PO_4)_3$ by the mechanical milling is very effective for increasing the insertion/extraction of lithium from $Li_3V_2(PO_4)_3$ structure. In charge/discharge test, the ball-milled $Li_3V_2(PO_4)_3$ sample exhibited a higher initial discharge capacity of 174 mAh/g in the voltage range of 3.0-4.8 V, compared with pure $Li_3V_2(PO_4)_3$ sample (152 mAh/g). Furthermore, the ball-milled $Li_3V_2(PO_4)_3$ presented not only higher cycle retention rate after 50 cycles, but also better rate capability compared with pure sample in the whole region (0.1-7 C).

A Study on Heat and Mass Transfer in a Vertical Tube Absorber Using LiBr Family Solutions (LiBr계 용액을 사용한 수직관 흡수기의 열 및 물질 전달에 관한 연구)

  • Cho, H.C.;Kim, C.B.;Jeong, S.Y.;Kang, S.W.;Lee, C.S.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.7 no.2
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    • pp.196-206
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    • 1995
  • Experimental investigations on heat and mass transfer characteristics in a vertical tube absorber have been carried out. Three different copper tubes with a length of 1.5m have been tested using LiBr solution and LiBr-$CaCl_2$ solution. The effects of solution flow rate, cooling water temperature, solution inlet temperature and evaporation temperature have been investigated in detail. It is found that heat transfer coefficient increases gradually with the increase of solution flow rate, but decreases rapidly for the flow rates less than 0.02kg/ms. The grooved tube generally shows better heat transfer performances than the smooth tube. LiBr solution shows almost no absorption capability for the cooling water temperatures over $40^{\circ}C$. LiBr-$CaCl_2$ gives less decreasing rate in absorption capability at these temperatures and the heat transfer coefficient becomes less dependent on the types of tubes in use. Considering heat and mass transfer rates, LiBr-$CaCl_2$ solution is found to be more suitable than LiBr solution for air cooled absorber, which operates at higher temperature than water cooled absorber.

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A Study on Optimization of Manufacturing Condition for LiNi1/3Mn1/3Co1/3O2-based Cathode Electrode (LiNi1/3Mn1/3Co1/3O2계 정극활물질을 적용한 전극 제조조건 최적화 연구)

  • Kim Hyun-Soo;Kim Sung-Il;Lee Chang-Woo;Moon Seong-In;Kim Woo-Seong
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.2
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    • pp.139-144
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    • 2006
  • A fabrication condition of the cathode electrode was optimized in a lithium secondary battery. The $LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ powders were used as a cathode material. The $LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$/Li cells were prepared with a certain formulation and their cycleability and rate-capability were evaluated. Optimum electrode composition simulated from the evaluated value was 86.3: 5.6: 8.1 in mass $\%$ of active material: binder: conducting material. Discharge capacity decreased markedly as the press ratio exceeded $30\%$ during preparation of the electrode. Discharge performance at a high current rate deteriorated abruptly as the electrode thickness was over $120{\mu}m$.

The Effects of Functional Electrical Stimulation on Forced Vital Capacity and Phonation Capabilities in Children with Spastic Cerebral Palsy

  • Ju, Joung-Youl;Kang, Kwon-Young;Shin, Hee-Joon
    • Journal of International Academy of Physical Therapy Research
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    • v.2 no.2
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    • pp.339-343
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    • 2011
  • The purpose of this study is to see the effect of functional electrical stimulation on forced vital capacity and alternating motion rate in children with spastic cerebral palsy. This study divided 20 children with spastic cerebral palsy into two groups; functional electrical stimulation treatment group and control group. Functional electrical stimulation treatment group had 20min per day treatment three times a week for four weeks and the control group did not have any treatment. Before and after intervention, this study measured forced vital capacity and alternate motion rate(/peo/,/teo/) for all children. Forced vital capacity showed statistically significant increase for the group with functional electrical stimulation(p<.05) while the control group did not show any significant increase(p>.05). Alternate motion rate showed statistically significant increase for the group with functional electrical stimulation(p<.05) while the control group did not show any significant increase(p>.05). This result shows that functional electrical stimulation affected the ability of the children with spastic cerebral palsy who have decreased breathing and phonation capability.

The electrochemical properties of Zr-Ti-V-Ni-Mn hydrogen storage alloys with various compositions for an electrode of Ni-MH secondary battery (Ni-MH 2차 전기 전극용 Zr-Ti-V-Ni-Mn계 수소저장합금의 조성에 따른 전기화학적 특성)

  • Choi, Seung-Jun;Jung, So-Yi;Park, Choong-Nyeon
    • Transactions of the Korean hydrogen and new energy society
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    • v.10 no.4
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    • pp.219-224
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    • 1999
  • Effects of alloy modification for the $Zr_{0.7}Ti_{0.3}V_{0.4}Ni_{1.2}Mn_{0.4}$ alloy as an electrode materials have been investigated. When Ti in the alloy was partially substituted by Zr, the hydrogen storage capacity and subsequently the discharge capacity increased significantly, however, the activation characteristic and rate capability decreased. By substituting Mn with other elements (Cr, Co and Fe) in the alloy, discharge capacity decreased but the cycle life and rate capability were improved. Considering both the discharge capacity, the high rate discharge property and cycle life, the $Zr_{0.7}Ti_{0.3}V_{0.4}Ni_{1.2}Mn_{0.3}Cr_{0.1}$ alloy among the alloys subjected to the test was found to be a prominent alloy for a practical usage.

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The Electrochemical Performance of Li3V2(PO4)3/Graphene Nano-powder Composites as Cathode Material for Li-ion Batteries

  • Choi, Mansoo;Kim, Hyun-Soo;Lee, Young Moo;Jin, Bong-Soo
    • Journal of Electrochemical Science and Technology
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    • v.5 no.4
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    • pp.109-114
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    • 2014
  • The $Li_3V_2(PO_4)_3$/graphene nano-particles composite was successfully synthesized by a facile sol-gel method. The addition of a graphene in $Li_3V_2(PO_4)_3(LVP)$(LVP) showed the high crystallinity and influenced the morphology of the $Li_3V_2(PO_4)_3$ particles observed in X-ray diffraction (XRD) and scanning electron microscopy (SEM). The LVP/graphene samples were well connected, resulting in fast charge transfer. The effect of the addition graphene nano-particles on electrochemical performance of the materials was investigated. Compared with the pristine LVP, the LVP/graphene composite delivered a higher discharge capacity of $122mAh\;g^{-1}$ at 0.1 C-rate, better rate capability and cyclability in the potential range of 3.0-4.3 V. The electrochemical impedance spectra (EIS) measurement showed the improved electronic conductivity for the LVP/graphene composite, which can ensure the high specific capacity and rate capability.

Experimental Study of Air-cooled Condensation in Slightly Inclined Circular Tube (경사진 원형관에서의 공냉응축에 관한 실험적 연구)

  • Kim, Dong Eok;Kwon, Tae-Soon;Park, Hyun-Sik
    • The KSFM Journal of Fluid Machinery
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    • v.19 no.4
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    • pp.29-34
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    • 2016
  • In this study, the experimental investigation of air-cooled condensation in slightly inclined circular tubes with and without fins has been conducted. In order to assess the effects of the essential parameters, variable air velocities and steam mass flow rates were given to the test section. The heat transfer performance of air-cooled condensation were dominantly affected by the air velocity, however, the increase of the steam mass flow rate gave relatively weaker effects to total heat transfer capability. And in the experimental cases with the finned tube, the total heat transfer rate of the finned tube was significantly larger than that of the flat tube. From those results, it can be confirmed that the most important parameter for air-cooled condensation heat transfer is the convective heat transfer characteristics of air. Therefore, for the well-designed long-term cooling passive safety system, the consideration of the optimal design of the fin geometry is needed, and the experimental and numerical validations of the heat transfer capability of the finned tube would be required.

Effects of the composition and the pressing rate of electrode on the internal resistance and the battery characteristic (전극 조성 및 압착율에 의한 내부저항과 전지특성)

  • 정재국;진봉수;문성인;윤문수;남효덕
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.11a
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    • pp.421-424
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    • 2000
  • We have examined the impedance characteristics and the rate characteristics of LPB. As results, the impedance of LPB decreased with increased pressing rate of electrodes, adding amounts of PVdF and VGCF. And the rate characteristics of LPB increased with the a increase of pressure-rate, PVdF and VGCF contents. The rate characteristics of LPB was improved by pressing of electrode and adding of VGCF content. And specific capacity of anode was increased with adding amounts of PVdF. Higher pressing rate of electrodes, higher adding amounts of PVdF and VGCF was necessitated good rate characteristics for lithium polymer battery.

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