• The Korean Journal of Ecology
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• v.28 no.6
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• pp.365-373
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• 2005

Understanding the relation of water environmental factors and vegetation is critical to restoration and management of wetlands. To reveal relationships between representative plant groups and water environments, we measured cover and abundance of plant species, water depth, temperature, pH, conductivity, dissolved oxygen, $NH_4$-N, $NO_3$-N, and $PO_4-P$ concentration in water in Wangsuk stream (WS) and Gwarim reservoir (GR). This study was conducted monthly from May to October, 2004. Six vegetation groups $(W1{\sim}W6)$ in WS and five vegetation groups $(G1{\sim}G5)$ in GR were identified using TWINSPAN. WS was characterized by Phragmites japonica, Digitaria sanguinalis, Phalaris arundinacea, Beckmannia xyzigachne and Persicara hydropiper, Persicaria thunbergii, Typha angustifolia. GR was characterized by T. angustifolia, Scirpus tabernaemontani, P. thunbergii, Humulus japonicus and Scirpus fluviatilis, Typha orientalis, Zizania latifolia. The vegetation in WS experienced greater seasonal changes than in GR. A correspondence analysis suggests that water depth was the major environmental factor influencing the distribution of most plants communities in both wetlands.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.267-273
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• 2018

Hydrothermal liquefaction of Chlorella vulgaris feedstock containing 80% (w/w) water was conducted in a batch reactor as a function of temperature (300, 325 and $350^{\circ}C$) and reaction times (5, 10 and 30 min). The biocrude yield, elemental composition and higher heating value obtained for various reaction conditions helped to predict the optimum conditions for maximizing energy recovery. To optimize the recovery of inorganic nutrients, we further investigated the effect of reaction conditions on the ammonium ($NH_4{^+}$), phosphate ($PO_4{^{3-}}$), nitrate ($NO_3{^-}$) and nitrite ($NO_2{^-}$) concentrations in the aqueous phase. A maximum energy recovery of 78% was obtained at $350^{\circ}C$ and 5 min, with a high energy density of 34.3 MJ/kg and lower contents of oxygen. For the recovery of inorganic nutrients, shorter reaction times achieved higher phosphorus recovery, with maximum recovery being 53% at $350^{\circ}C$ and 5 min. Our results indicate that the reaction condition of $350^{\circ}C$ for 5 min was optimal for maximizing energy recovery with improved quality, at the same time achieving a high phosphorus recovery.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.120-120
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• 2009

Ga doped ZnO (GZO) transparent conductive films were deposited on the glass substrates at room temperature by facing target sputtering (FTS) method. The sputtering targets were 100 mm diameter disks of GZO($Ga_2O_3$ 3.w.t%) and Zn metal. The GZO thin films were deposited as a various $PO_2$ (oxygen gas content). Base pressure was $2{\times}10^{-6}torr$, and a working pressure was 1mTorr. The properties of thin films on the electrical and optical properties of the deposited films were investigated by using a four-point probe (Chang-min), a Hall Effect measurement (Ecopia) and an UV/VIS spectrometer (HP). The minimum resistivity of film was $6.5{\times}10^{-4}[{\Omega}-cm]$ and the average transmittance of over 80% was seen in the visible range

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.337-340
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• 2008

포항공과대학교의 포항풍력에너지연구소(PoWER Center)가 개발에 참여했던 750 kW급 직결형 국산화 풍력발전 시스템의 상용화를 추진하기 위한 출력성능 및 하중 측정을 통한 실증연구가 대관령의 풍력실증단지에서 수행되었다. IEC 61400-13의 규격을 기준으로 수행된 하중 측정의 일환으로 스트레인 게이지의 기계적 하중에 대한 외부 하중부가에 의한 기계적 보정이 추진되었다. 기계적 보정의 수행 중 일부스트레인 게이지가 단락되는 사고가 발생하였으나 비교보정을 통하여 기계적 보정작업을 완수할 수 있었다. 본 논문에서는 외부 하중부가에 의한 기계적 하중의 보정절차를 소개하고, 수행된 기계적 보정시험 과정에 대해 상세히 설명하며 기계적 보정의 결과를 보고한다.

• Journal of the Korean Vacuum Society
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• v.7 no.s1
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• pp.50-56
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• 1998

Ion beam assisted deposition (IBAD) was successfully used to produce a dense and ultra-adherent Hydroxyapatite (HA) film on titanium alloy and alumina. Recently it is also proved that the HA coatings on alumina substrate treated with 20 ppm $AgNO_3$ had the structure of $(Ag, Ca)_10(PO_4)6(OH)_2$, which exhibited excellent antimicrobial effects. The present paper aims to morphlogically characterize the adhesion of macrophages on newly developed Ag-HA coated alumina and Ti6A14V substrates and to evaluate the biocompatibility of the coatings in vitro. It can be found that the cell number on alumina of the concentration of $AgNO_3$ in the treatment, the cell number on Ag-HA coatings decreased. Up to 20 ppm $AgNO_3$ by Ag-treatment, the morphological development of the cells on Ag-HA coating was similar to that of the cells on HA coating, suggesting the biotolerance of the Ag-HA coatings.

• Journal of Pharmaceutical Investigation
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• v.25 no.2
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• pp.145-152
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• 1995

The superoxide dismutase (SOD) mimetic activity of copper complex of 3,5-disopropylsalicylic acid (Cu(II)-DIPS) was tested and compared to those of human recombinant SOD (hrSOD) and its conjugate form with polyethyleneglycol (PEG) using fer- ricytochrome c reduction assay. Stability constant of Cu(II)-DIPS was measured po- tentiometrically using SCOGS2 program. In the presence of 10 g/L albumin, Cu(II)-DIPS lost most of its SOD mimetic activity. HrSOD was modified with polyethylene glycol (PEG) of M.W. 5000. These conjugates have markedly prolonged plasma half-lives of enzymatic activity (15.5 hr) compared to native hrSOD (5 min). In summary, efficient SOD mimetics should be stable enough not to dissociate in blood by serum protein. HrSOD could have longer half-life by conjugation with inert PEG for sustained SOD effect.

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.193-195
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• 1988

The native oxide films were thermally and anodically formed on the n-GaP substrates grown by SSD method and measured this oxide thickness and the chemical composition and the electrical properties with formation condition. The chemical composition of themally oxidized GaP film was composed of mostly $GaPO_4$ at temperature below $800^{\circ}C$ and mostly $\beta-Ga_{2}O_{3}$ above $800^{\circ}C$. But The chemical composition of anodically oxidized GaPfilm was composed of the mixture of $Ga_{2}O_{3}$ and $P_{2}O_{5}$. The barrier height of Al/oxide/n-Gap which was formed at $700^{\circ}C$ by thermal oxidation method were 1.10eV, 1.03eV in Current-Voltage measurement. Interface charge density were $4{\times}10^{12}q(C/cm^2)$ and $3{\times}10^{12}q(C/cm^2)$ in Capacitance-Voltage measurement respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.336-336
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• 2010

Ga doped ZnO (GZO) transparent conductive films were deposited on the glass substrates at room temperature by facing target sputtering (FTS) method. The sputtering targets were 100 mm diameter disks of GZO($Ga_2O_3$ 3.w.t%) and Zn metal. The GZO thin films were deposited as a various $PO_2$ (oxygen gas content). Base pressure was $2{\times}10^{-6}$torr, and a working pressure was 1mTorr. The properties of thin films on the electrical and optical properties of the deposited films were investigated by using a four-point probe, a Hall Effect measurement and an UV/VIS spectrometer. The minimum resistivity of film was $6.5{\times}10^{-4}$[$\Omega$-cm] and the average transmittance of over 80% was seen in the visible range.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.10 s.181
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• pp.2529-2534
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• 2000

Torsional vibration analysis in a large two -stroke low speed diesel engine and generator system for stationary power plants is performed to verify that the vibration characteristics of shafting system meet design requirements. Our own developed S/W is employed for the analysis, whose results are evaluated comparing with measurements. Vibration analysis results of the system are presented according to the change of loading(unload, 100%load, 110% load) and operating(mis-firing, uneven firing) conditions of the stationary power plants.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.162-168
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• 2007

The critical speed above which the vehicle become unstable should be fundamentally verified in the development of new train. In case of high speed tilting train, which require both higher critical speed and higher curving speed, the critical speed should be more carefully treated because the both requirements are conflicting each other in the conventional train design. This research has been performed to estimate the linear and non-linear critical speed of 200km/h Korean Tilting Train which has been developing. The newly developed self-steering mechanism was attached to the tilting train to secure critical speed under the lower yaw stiffness which was inevitable to secure higher curving performance. The simulation to predict critical speed was done by commercial vehicle dynamic S/W. Full scale roller rig test was carried out for the validation of numerical results and effectiveness of self-steering mechanism.