• 상하수도학회지
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• 제31권6호
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• pp.577-586
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• 2017

One of the major sources causing eutrophication and algal blooms of lakes or streams is phosphorus which comes from point and nonpoint pollution sources. HAP (hydroxyapatite) crystallization using granular alkaline materials can achieve the decrease of phosphorus load from wastewater treatment plants and nonpoint pollution control facilities. In order to induce HAP crystal formation, continuous supply of calcium and hydroxyl ions is required. In this research, considering HAP crystallization, several types of lime-based granular alkaline materials were prepared, and the elution characteristics of calcium and hydroxyl ions of each were analyzed. Also, column tests were performed to verify phosphorus removal efficiencies of granular alkaline materials. Material_1 (gypsum+cement mixed material) achieved the highest pH values in the column tests consistently, also, Material_2 (gypsum+slag mixed material) and Material_3 (calcined limestone material) achieved over pH 9.0 for 240 hours (10 days) and proved the efficiencies of long-term ion supplier for HAP crystallization. In the column tests using Material_3, considerable pH increase and phosphorus removal were carried out according to each linear velocity and filtration depth. T-P removal efficiencies were 87.0, 84.0, 68.0% and those of PO4-P 100.0, 97.0, 80.0% for linear velocity of 1.0, 2.5, 5.0 m/hr respectively. Based on the column test results, the applicability of phosphorus removal processes for small-scale wastewater treatment plants and nonpoint pollution control facilities was found out.

• 약학회지
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• 제54권4호
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• pp.295-299
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• 2010

The aim of this study was to develop and validate for determination of alibendol in human plasma by HPLC method. After precipitation of 500 ${\mu}l$ plasma samples by 50% methanol 50 ${\mu}l$ and 60% perchloric acid 30 ${\mu}l$ and the supernatant 50 ${\mu}l$ was injected into HPLC. The assay was performed isocratically using 10 mM potassium phosphate (pH 3.0) and acetonitrile (80 : 20, v/v) as mobile phase. The $C_{18}$ column (particle size $3.5{\mu}m$, $4.6{\times}50$ mm, Zorbax Eclipse) was used as a solid phase. The mobile phase was delivered at a flow-rate of 1.7 ml/min, detection was by ultraviolet absorption at 232 nm and concentrations were calculated on the basis of peak areas. In these conditions, alibendol can be separated from ethylparaben, the internal standard, and endogenous substances. The retention times of alibendol and ethylparaben were just about 2.6 and 3.5 minutes, respectively. This rapid HPLC method was validated by examining the precision and accuracy for inter- and intra-day analysis. The standard curve was linear ($R^2$=1.0000) over the concentration range of 0.05~20 ${\mu}g$/ml. The inter-day relative standard deviation (R.S.D.) and accuracy were 0.2~12.2% and 94.4~101.2% (82.7% at the lower limit of quatitation). The intra-day R.S.D. and accuracy were 0.1~11.8% and 98.8~102.5%, respectively. The method was successfully applied to the determination of alibendol in plasma for a pharmacokinetic study.

• Steel and Composite Structures
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• 제2권1호
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• pp.1-20
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• 2002

Fiber-Reinforced Plastics (FRP) have received significant attention for use in civil infrastructure due to their unique properties, such as the high strength-to-weight ratio and stiffness-to-weight ratio, corrosion and fatigue resistance, and tailorability. It is well known that FRP wraps increase the load-carrying capacity and the ductility of reinforced concrete columns. A number of researchers have explored their use for seismic components. The application of concern in the present research is on the use of FRP for corrosion protection of reinforced concrete columns, which is very important in cold-weather and coastal regions. More specifically, this work is intended to give practicing engineers with a more practical procedure for estimating the strength of a deficient column rehabilitated using FRP wrapped columns than those currently available. To achieve this goal, a stress-strain model for FRP wrapped concrete is proposed, which is subsequently used in the development of the moment-curvature relations for FRP wrapped reinforced concrete column sections. A comparison of the proposed stress-strain model to the test results shows good agreement. It has also been found that based on the moment-curvature relations, the balanced moment is no longer a critical moment in the interaction diagram. Besides, the enhancement in the loading capacity in terms of the interaction diagram due to the confinement provided by FRP wraps is also confirmed in this work.

• Natural Product Sciences
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• 제22권2호
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• pp.93-101
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• 2016

For efficient quality control of the Samryeongbaekchul-san decoction, a powerful and accurate an ultra-performance liquid chromatography (UPLC) coupled with electrospray ionization (ESI) tandem mass spectrometry (MS) method was developed for quantitative analysis of the thirteen constituents: allantoin (1), spinosin (2), liquiritin (3), ginsenoside Rg1 (4), liquiritigenin (5), platycodin D2 (6), platycodin D (7), ginsenoside Rb1 (8), glycyrrhizin (9), 6-gingerol (10), atractylenolide III (11), atractylenolide II (12), and atractylenolide I (13). Separation of the compounds 1 - 13 was performed on a UPLC BEH $C_{18}$ column ($2.1{\times}100mm$, $1.7{\mu}m$) at a column temperature of $40^{\circ}C$ with a gradient solvent system of 0.1% (v/v) formic acid aqueous-acetonitrile. The flow rate and injection volume were 0.3 mL/min and $2.0{\mu}L$. Calibration curves of all compounds were showed good linearity with values of the correlation coefficient ${\geq}0.9920$ within the test ranges. The values of limits of detection and quantification for all analytes were 0.04 - 4.53 ng/mL and 0.13 - 13.60 ng/mL. The result of an experiment, compounds 2, 6, 12, and 13 were not detected while compounds 1, 3 - 5, and 7 - 11 were detected with 1,570.42, 5,239.85, 299.35, 318.88, 562.27, 340.87, 12,253.69, 73.80, and $115.01{\mu}g/g$, respectively.

• 콘크리트학회논문집
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• 제15권1호
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• pp.11-16
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• 2003

현재 국내에서 설계 및 시공되고 있는 비내진상세를 가진 RC구조물의 이력거동특성과 내진성능이 밝혀져 있지 않다. 따라서, 본 연구에서는 일반적인 10층 철근콘크리트 구조물의 외부 보-기둥접합부를 선정하여 슬래브의 유무, 보하부 주근의 접합부내로의 정착방항, 접합부내 보강근의 유무에 따라 6개의 1/3축소 실험체를 만들어 반복횡하중 실험을 수행하였다. 실험결과 슬래브가 있는 실험체가 없는 실험체에 비해 정모멘트일 때 25%, 부모멘트일 때62%의 큰 강도를 나타냈고, 보하부 주근이 상부로 정착된 것이 하부로 정착된 경우보다 정모멘트일 때 8 %, 부모멘트일 때 11% 강도 증가효과가 있었다. 그리고 접합부내에 전단보강근이 보 주근의 뽑힘을 억제하는 것으로 나타났다.

• 대한본초학회지
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• 제30권3호
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• pp.19-24
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• 2015

Objectives : HPL-1, a novel herbal medicine which is composed of five herbs such as Kalopanacis Cortex, Chaenomelis Fructus, Raphani Semen, Atractylodis Rhizoma and Pulvis Aconiti Tuberis Purificatum, was developed for treatment of osteoarthritis. This study is aimed to develop analytical method for consistent quality control of HPL-1 and validate chromatographic method. Methods : Chromatographic analysis was performed using ultra-high performance liquid chromatography - diode array detector (UHPLC-DAD) equipped with RP-amide column, column oven, and auto sampler. Marker compounds [protocatechuic acid, chlorogenic acid, liriodendrin, 3,5-dicaffeoylquinic acid, ${\beta}$-D-(3-O-sinapoyl)-fructofuranosyl-$\alpha$-D-(6-O-sinapoyl)glucopyranoside and benzoylmesaconine] were separated by step gradient elution of acetonitrile and 0.1% phosphoric acid/water. The method validation was evaluated by quantitative validation parameters of linearity, accuracy, precision, limit of detection (LOD) and limit of quantification (LOQ) according to KFDA guideline.Results : An optimized method for six marker compounds in HPL-1 was established by UHPLC-DAD. The correlation coefficient (R²) with each calibration curve was greater than 0.99. The LOD and LOQ were within the range of 0.008-0.090 and $0.023-0.274{\mu}g/mL$, respectively. The relative standard deviation (RSD) of intra- and inter-day variability were less than 4.0%. The result of recovery test was range from 93.3-106.3% with RSD < 4.0%.Conclusions : These results suggest that the quantitative UHPLC method is precise, accurate, effective for quality evaluation of HPL-1. The method may also contribute to improve quality of crude drug preparations used for treatment of various diseases.

• 생약학회지
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• 제41권3호
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• pp.180-184
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• 2010

The antioxidant activity of Desmodium oldhami (Leguminosae) was determined by measuring the radical scavenging effect on DPPH (1,1-diphenyl-2-picrylhydrazyl). The methanolic extract of D. oldhami showed the strong antioxidant activity. Five compounds, kaempferol-3-O-rhamnopyranoside (afzeline) (1), quercetin-3-O-[$\alpha$-L-rhamnopyranosyl($1{\rightarrow}6$)-$\beta$-Dglucopyranoside] (rutin) (2), kaempferol-3-O-glucopyranoside (astragalin) (3), genistein-7-O-$\beta$-D-glucopyranoside (genistin) (4), kaempferol-3-O-rutinoside (5) were isolated from the active ethyl acetate soluble fraction of D. oldhami through repeated silica gel and Sephadex LH-20 column chromatography. Among them, compound 2 showed the most significant antioxidative effect on DPPH free radical scavenging test. Compounds 1-5 are reported for the first time from this plant.

• 한국해양공학회지
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• 제32권1호
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• pp.9-20
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• 2018

The present study deals with the conceptual design of a motion reduction device for a floating wave-offshore wind hybrid power generation platform. A damping plate attached to the bottom of a column of a large semi-submersible is introduced to reduce the motion of the platform. Performance analyses on various shapes and configurations of damping plates were performed using the potential flow solver, and the appropriate configuration and size of the damping plate were selected based on the numerical results. In order to see the effect of viscous damping, a small scale model test was performed in a 2D wave flume. The performances of five different damping plates were measured and discussed based on the results of free decay tests and regular wave tests.

• International Journal of Concrete Structures and Materials
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• 제18권2E호
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• pp.79-87
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• 2006

The main objective of this research is to examine the behavior of high-strength concrete(HSC) columns. Eight test columns in one-third scale were tested under the conditions of cyclic lateral force and a constant axial load equal to 30% of the column axial load capacity. The $200{\times}200mm$ square columns were reinforced with eight DB bars constituting a longitudinal steel ratio of 2.54% of the column cross-sectional area. The main experimental parameters were volumetric ratio of transverse reinforcement(${\rho}_s$=1.58, 2.25 percent), tie configuration(Type H, Type C, Type D) and tie yield strength($f_{yh}$=548.8 and 779.1 MPa). It was found that the hysteretic behaviour and ultimate deformability of HSC columns were influenced by the amount and details of transverse reinforcement in the potential plastic hinge regions. Columns of transverse reinforcement in the amount 42 percent higher than that required by seismic provisions of ACI 318-02 showed ductile behavior. At 30% of the axial load capacity, it is recommended that the yield strength of transverse reinforcement be held equal to or below 548.8 MPa. Correlations between the calculated damage index and the damage progress are proposed.

• Architectural research
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• 제7권1호
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• pp.39-48
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• 2005

Main objective of this research is to evaluate performance of high-strength concrete (HSC) columns for ductility and strength. Eight one-third scale columns with compressive strength of 69 MPa were subjected to a constant axial load corresponding to 30 % of the column axial load capacity and a cyclic horizontal load-inducing reversed bending moment. The variables studied in this research are the volumetric ratio of transverse reinforcement (${\rho}_s=1.58$, 2.25 %), tie configuration (Type H, Type C and Type D) and tie yield strength ($f_{yh}=549$ and 779 MPa). Test results show that the flexural strength of every column exceeds the calculated flexural capacity based on the equivalent concrete stress block used in the current design code. Columns with 42 % higher amounts of transverse reinforcement than that required by seismic provisions of ACI 318-02 showed ductile behaviour, showing a displacement ductility factor (${\mu}_{{\Delta}u}$) of 3.69 to 4.85, and a curvature ductility factor (${\mu}_{{\varphi}u}$) of over 10.0. With an axial load of 30 % of the axial load capacity, it is recommended that the yield strength of transverse reinforcement be held equal to or below 549 MPa.