• Title/Summary/Keyword: Discharge current

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The Electrochemical Properties on the Silver Doped Vanadium Oxide Xerogel (미량의 은이 첨가된 바나듐산화물 전극)

  • Park Heai-Ku;Kim, Gun-Tae;Lee, Man-Ho
    • Journal of the Korean Electrochemical Society
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    • v.5 no.1
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    • pp.1-6
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    • 2002
  • Silver doped vanadium pentoxides with a doping ratio Ag/V ranging from 0.03 to 0.11 were synthesized by sol-gel process, and $Li/Ag_xV_2O_5$ cell was investigated by the electrochemical methods. It appears to be amorphous layered material and entangled fibrous textures has been grown to form anisotropic corrugated fibrils. NMR measurements revealed that several different kinds of $Li^+$ ions exist in the lithium intercalated xerogel electrodes and the average cell potential was about 3.0V vs. $Li/Li^+$. The cell capacity of the silver doped $Ag_xV_2O_5$ xerogel cathodes was more than 359 mAh/g at discharge current 10mA/g and cycle efficiency $94\%$ was achieved.

Mixing Zone Analysis of Wastewater Effluent Discharged from Sokcho Ocean Outfall (속초 해양방류 하.폐수의 혼합구역에 대한 특성분석)

  • 강시환;박연숙;김상익;이호진
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.13 no.3
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    • pp.245-253
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    • 2001
  • Mixing zone characteristics of the wastewater effluents discharged from Sokcho ocean outfall have been investigated using an outfall mixing zone model which was developed on the basis of Huang et al.'s(1996) analysis method. The model was applied to Sokcho ocean outfall case and was used to simulate the concentration distribution of wastewater effluents using winter season's data, ie. daily effluent flowrate, ocean current and density stratification data which were measure for two months in the outfall area. Hourly concentration distribution of outfall effluent discharges was calculated and they were averaged for the period of 15 days which covers the ambient flow variability of the neap and the spring tidal currents. The results show that near-field dilution was relatively high with the minimum dilution of 130 for the winter season. The mixing zone was extended to the coastal beach area rather than offshore because of major direction of coastal currents. This may cause a deteriorating impact on coastal water quality, especially to the adjacent swimming beach area.

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Characteristics of Seasonal Variation to Sedimentary Environment at the Estuary area of the Nakdong (낙동강 하구역의 계절적인 퇴적환경 변화특성)

  • Yoon, Eun-Chan;Lee, Jong-Sup
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.20 no.4
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    • pp.372-389
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    • 2008
  • In this study, we formed a detailed grid at the estuary area of the Nakdong and collected the surface sediments. Particle size analysis and comparison with existing data were conducted to investigate the characteristics of seasonal and long-term changes in the sediments. As a result of investigation, the distribution of the sediments showed a great change per season and was greatly influenced by the quantity of outfall discharge at the Nakdong estuary barrier and the incident wave climate. The sandy sediments showed dominant movement toward the front of Jinwoodo west of the estuary area of the Nakdong due to the influence of the ENE wave, the annually-dominant wave. And the muddy sediments showed deposition by being moved toward the deep open sea along with a current. The present conditions of the sediments at the estuary area of the Nakdong showed great differences from the results of previous studies.

Operation Status and Improvement Plan of Continuing Hospitalization Judgement System in Mental Health Review Board (정신보건심판위원회 계속입원치료 심사제도 운영현황 및 개선방안)

  • Park, Sun Joo;Nam, Yoon Young;Hwang, Tae Yeon;Joe, Keun Ho;Yong, Jun Jin;Kim, Eun Jin;Kim, Chul Eung
    • Health Policy and Management
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    • v.27 no.4
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    • pp.347-358
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    • 2017
  • Background: The recent revision of South Korea's Mental Health Law emphasizes the role of the Mental Health Review Board. For this study, we examined the current status of continuing hospitalization judgement in Mental Health Review Board at the national level and aimed to determine the directions of improvement. Methods: Using a qualitative case study as the research method, we interviewed 30 Mental Health Review Board members and analyzed the results. Results: Each municipality had very different continuing hospitalization judgement methods. In our systematic review, which consisted of document inspection, we identified reliability problems due to limitations in Mental Health Review Board's operating systems, discharge orders, etc. Additionally, continuing hospitalization judgement needs to improve the objectivity, fairness, and effectiveness of their screening examinations. Conclusion: Based on the results of this study, we suggest policy proposals to improve these systems, such as standardizing examination processes, strengthening on-site inspections, increasing the independence and neutrality of judgment in Mental Health Review Board, building community mental health infrastructures, and establishing integrated management systems.

Quadratic Parabolic Equation to Estimate the Vertical Velocity Distribution in the Natural Streamflow (자연하천의 연직방향 유속분포 추정을 위한 포물선식)

  • Park, Seung-Gi;Kim, Tae-Cheol
    • Journal of Korea Water Resources Association
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    • v.33 no.2
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    • pp.169-179
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    • 2000
  • The study was carried out to investigate the characteristics of vertical velocity distribution measured by current meter at Kangkyung station in Keum river during the period of 1995 to 1997. It suggests the quadratic parabola equation to estimate the vertical velocity profile only from the measurement data of surface velocity. The equation was found to be statistically very stable and showed high significance to express the surface velocity and bottom velocity. The vertical velocity profile was detennined by the relationships to the surface velocity, and a coefficient of the quadratic parabolic equation. The equation was verified to the reserved survey data, and the results were confirmed to be good for the estimation of the characteristics of the vertical velocity distribution. The vertical velocity profile can be applied to calculating the mean velocity and discharge, and to analyse the dispersion of pollutant materials in the streamflow.

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Improvement of Electrochemical Characteristics by Changing Morphologies of Carbon Electrode (탄소 전극 형상 변화에 따른 전기화학 커패시터 특성 향상)

  • Min, Hyung-Seob;Kim, Sang-Sig;Cheong, Deock-Soo;Choi, Won-Kook;Oh, Young-Jei;Lee, Jeon-Kook
    • Korean Journal of Materials Research
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    • v.19 no.10
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    • pp.544-549
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    • 2009
  • Activated carbon (AC) with very large surface area has high capacitance per weight. However, such activation methods tend to suffer from low yields, below 50%, and are low in electrode density and capacitance per volume. Carbon NanoFibers (CNFs) had high surface area polarizability, high electrical conductivity and chemical stability, as well as extremely high mechanical strength and modulus, which make them an important material for electrochemical capacitors. The electrochemical properties of immobilized CNF electrodes were studied for use as in electrical double layer capacitor (EDLC) applications. Immobilized CNFs on Ni foam grown by thermal chemical vapor deposition (CVD) were successfully fabricated. CNFs had a uniform diameter range from 50 to 60 nm. Surface area was 56 m$^2$/g. CNF electrodes were compared with AC and multi wall carbon nanotube (MWNT) electrodes. The electrochemical performance of the various electrodes was examined with aqueous electrolyte of 2M KOH. Equivalent series resistance (ESR) of the CNF electrodes was lower than that of AC and MWNT electrodes. The specific capacitance of 47.5 F/g of the CNF electrodes was achieved with discharge current density of 1 mA/cm$^2$.

High Stability and High Efficiency Power Amplifier with Switchable Damper for Plasma Applications (플라즈마 응용을 위한 선택적 감쇠기를 사용한 고안정 고효율 전력증폭기)

  • Kim, Ji-Yeon;Lee, Dong-Heon;Chun, Sang-Hyun;Yoo, Ho-Joon;Kim, Jong-Heon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.20 no.1
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    • pp.1-11
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    • 2009
  • In this paper, a new 1 kW power amplifier with high efficiency and high stability in a RF generator is designed and fabricated for plasma applications. The efficiency of power amplifier is improved by using class-E amplifier that consists of one push-pull MOSFET and high current drive IC instead of class-C amplifier composed of several single ended MOSFET. Switchable damper that allows selecting three different modes of amplifiers for considering efficiency and stability is added into the amplifier for plasma applications. Stable region of an early electronic discharge section is extended to VSWR of 4.5:1 compared to conventional VSWR of 3.8:1 through using switchable damper. The dimension of the amplifier is also reduced to 30 % of conventional amplifier. The 80 % efficiency of power amplifier with switchable damper is obtained the output power of 1 kW in operating frequency of 13.56 MHz. In comparison of conventional power amplifier for plasma applications, 13 % efficiency is improved.

Development of an Ultra-Violet Lamp and a Ballast for Ship's Ballast Water Treatment (선박평형수 처리용 자외선 램프 및 안정기 개발)

  • Cheon, Sang-Gyu;Park, Dae-Won;Kil, Gyung-Suk
    • Journal of Advanced Marine Engineering and Technology
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    • v.35 no.5
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    • pp.675-681
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    • 2011
  • In this paper, we dealt with the design and fabrication of a medium pressure ultra-violet (UV) lamp and a magnetic ballast which are main components for ballast water treatment systems (BWTS). To acquire an optimal discharge condition of UV lamp, electrical and optical characteristics depending on the argon gas volume and the amount of mercury were experimentally analyzed. Rated voltage, current and power consumption of a prototype lamp were 490 [V], 8.6 [A] and 4.0 [kW], respectively. UV intensity of the lamp was 15 [%] higher than that of an equivalent lamp which is used in a BWTS. The magnetic ballast was designed in a UI core type through theoretical analysis and simulation. The open voltage and the rated power consumption of the ballast were 920 [V] and 8.5 [kVA] respectively. The disinfection efficacy which is carried out in a BWTS equipped with the UV lamp and magnetic ballast was over 99.99 [%], and this satisfy the IMO regulations.

The Prevalence of Cardiovascular Disease Risk Factors and the Framingham Risk Score in Patients Undergoing Percutaneous Intervention Over the Last 17 Years by Gender: Time-trend Analysis From the Mayo Clinic PCI Registry

  • Lee, Moo-Sik;Flammer, Andreas J.;Kim, Hyun-Soo;Hong, Jee-Young;Li, Jing;Lennon, Ryan J.;Lerman, Amir
    • Journal of Preventive Medicine and Public Health
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    • v.47 no.4
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    • pp.216-229
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    • 2014
  • Objectives: This study aims to investigate trends of cardiovascular disease (CVD) risk factor profiles over 17 years in percutaneous coronary intervention (PCI) patients at the Mayo Clinic. Methods: We performed a time-trend analysis within the Mayo Clinic PCI Registry from 1994 to 2010. Results were the incidence and prevalence of CVD risk factors as estimate by the Framingham risk score. Results: Between 1994 and 2010, 25 519 patients underwent a PCI. During the time assessed, the mean age at PCI became older, but the gender distribution did not change. A significant trend towards higher body mass index and more prevalent hypercholesterolemia, hypertension, and diabetes was found over time. The prevalence of current smokers remained unchanged. The prevalence of ever-smokers decreased among males, but increased among females. However, overall CVD risk according to the Framingham risk score (FRS) and 10-year CVD risk significantly decreased. The use of most of medications elevated from 1994 to 2010, except for ${\beta}$-blockers and angiotensin converting enzyme inhibitors decreased after 2007 and 2006 in both baseline and discharge, respectively. Conclusions: Most of the major risk factors improved and the FRS and 10-year CVD risk declined in this population of PCI patients. However, obesity, history of hypercholesterolemia, hypertension, diabetes, and medication use increased substantially. Improvements to blood pressure and lipid profile management because of medication use may have influenced the positive trends.

Environmental Studies in the Lower Part of the Han River -VII. Long Term Variations and Prospect of the Phytoplankton Community- (한강하류의 환경학적 연구 -VII. 식물플랑크톤군집의 장기간 변화와 전망-)

  • Lee, Jin-Hwan;Jung, Seung-Won
    • ALGAE
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    • v.19 no.4
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    • pp.321-327
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    • 2004
  • The literature review on the dynamics of the phytoplankton communities in terms of species composition, standing crops, abundant species and dominant species in the lower part of the Han River from 1940s to 2000s was conducted for the prospective prediction of their succession patterns. Total of 326 taxa were identified and they belonged to 47 blue-green algae, 139 green algae, 12 euglenoids, 126 diatoms, 6 din flagellates and 2 silicoflagellates. Composition of phytoplankton communities were 83.6% diatoms, 10.5% blue-green algae and 5.3% green algae in the middle of 1960s, whereas those were 43.2% diatoms, 40.7% green algae and 13.6% blue-green algae in the 1990s. Before 1990s, Synedra ulna, Melosira varians, Cymbella tumida, Synedra acus, Cymbella ventricosa, Navicula cryptocephala, Nitzschia palea, Aulacoseira granulata, Gomphonema parvulum and Cymbella affinis were most frequent, while those after 1990 were Asterionella formosa, Asterionella gracillima, Aulacoseira granulate, Aulacoseira granulata var. angustissima, Chlorella vulgare, Fragilaria crotonensis and Synedra ulna. Phytoplankton blooms were frequent from winter to the late spring and rare in summer due to heavy rain and discharge. Seasonal variations of the dominant species were fairly obvious; Asterionella gracillima and Aulacoseira granulata in spring, Aulacoseira granulate and Aulacoseira granulate var. angustissima in summer and autumn, Asterionella gracillima and Stephan discus hantzschii in winter. Recently blue-green algae, Microcystis, Aphanocapsa, Dactylococcopsis have been more abundant than those of the previous reports. Based on the current situations, Stephan discus hantzschii f. tennis, Asterionella gracillima, Aulacoseira granulate and blue-green algae will be more abundant and blooms of those species will be more frequent.