• 지질공학
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• 제24권2호
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• pp.191-199
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• 2014

We describe a method for detecting slope instability in flume tests using pore pressure and water content data in conjunction with a statistical control chart analysis. Specifically, we conducted univariate statistical analysis on x-MR control chart data (pore pressure and water content) collected at several points along the flume slope, which we separated into three parts: upper, middle, and lower. To assess our results in the context of landslide forecasting and warning systems, we applied control limit lines at $1{\sigma}$, $2{\sigma}$, and $3{\sigma}$ levels of uncertainty. In doing so, we observed that dispersion time varies depending on the control limit line used. Moreover, the detection of instabilities is highly dependent on the position and type of sensor. Our findings indicate that different characteristics of the data on various factors predict slope failure differently and these characteristics can be identified by univariate statistical analysis. Therefore, we suggest that a univariate statistical approach is an effective method for the early detection of slope instability.

• 대한수의학회지
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• 제48권1호
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• pp.9-16
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• 2008

A method for the quantification of eugenol in the medicinal herb Clove was developed and validated. For preparation of sample solutions clove was dried at $60^{\circ}C$ for 2h and ground by mixer and extracted with 95% ethanol for shaking extraction. The elutes were analyzed by HPLC system included a reversed phase column, a isocratic mobile phase of 60% methanol and PDA detector set at 280 nm. Calibration graphs were linear with very good correlation coefficients ($r^2>0.9999$) from $0.0125~1{\mu}g/ml$. The limit of detection per sample injection ($20{\mu}l$) was $0.81ng/{\mu}l$ and limit of quantification was $2.47ng/{\mu}l$. The method showed good intra-day precision (%RSD 0.08 ~ 0.27%) and inter-day precision (%RSD 0.32 ~ 1.19%).

• 분석과학
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• 제8권3호
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• pp.237-248
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• 1995

미국 환경청이 지정한 129종의 priority pollutants 중 16종의 유기살충제를 포함한 토양시료를 제조하여 표준분석방법인 기체크로마토그래프-전자포획법과 기체크로마토그래프/질량분석기-SIM (selected ion monitoring)법을 이용하여 동시분석의 효율성을 실험하였다. 토양시료의 추출 및 농축방법으로는 EPA의 SW-846 방법을 조금 수정한 초음파추출법(sonication extraction)과 Soxhlet 추출법(Soxhlet extraction)을 비교 연구하였다. 각 화합물의 회수율, 상대표준편차 및 method detection limit를 측정하여 그 결과들을 보고하였다.

• 약학회지
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• 제42권2호
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• pp.149-152
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• 1998

A high performance liquid chromatographic method was developed for the determination of DA-6034 in biological fluids using internal standard. Plasma containing DA-6034 and inter nal standard was extracted by liquid-liquid extraction at an acidic pH. After evaporation of the organic layer, the drug and internal standard were reconstituted with mobile phase and injected into the column. They were separated by high performance liquid chromatography on inertsil ODS II column at 334 nm. The detection limit of DA-6034 in plasma was 0.02 ${\mu}$g/ml. In this method, the range of recovery and coefficients of variation were 96-110% and 0.40-3.78%, respectively. There was no interference from endogenous substances. Urine and bile were analysed using the deproteinization method and the detection limit of DA-6034 was 1${\mu}$g/l.

• 대한화학회지
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• 제57권5호
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• pp.568-573
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• 2013

A selective and sensitive method for simultaneous determination of copper in blood by adsorptive differential pulse cathodic stripping voltammetry is presented. The procedure involves an adsorptive accumulation of Cu(II)-ETSC (4- ethyl-3-thiosemicarbazide) on a hanging mercury drop electrode, followed by a stripping voltammetry measurement of reduction current of adsorbed complex at about -715 mV. The optimum conditions for the analysis of copper (II) ion are : pH 10.3, concentration of 4-ethyl-3-thiosemicarbazide $3.25{\times}10^{-6}$ M and an accumulation potential of -100 mV. The peak current is proportional to the concentration of copper over the range 0.003-125 ng/mL with a detection limit of 0.001 ng/mL and an accumulation time of 60 s. Moreover, with the use of the proposed method, there is a considerable improvement in the detection limit, the linear dynamic range and the deposition time, compared with the methods of adsorptive stripping voltammetry for the determination of copper. The developed method was validated by analysis of whole blood certified reference materials.

• 대한본초학회지
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• 제23권4호
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• pp.171-177
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• 2008

Objectives: This study presents a reversed-phase high-performance liquid chromatography- pulsed amperometric detection(RP-HPLC-PAD) method for the determination of puerarin and daidzin in Puerariae Radix extract and Chinese medicinal preparations. Methods: Chromatographic separation was performed using a 10% acetonitrile with a reversed-phase column(Unison UK-C18, $100mm{\times}2.0mm$ I.D.; $3{\mu}m$). The analyses were detected by pulsed amperometric detector(PAD) in alkaline conditions by combining with post-column NaOH solution. Geniposide was used as an internal standard. Results: The limit of detection(S/N=3) and the limit of quantification(S/N=10) were 0.025 ng, 0.075 ng for puerarin, and 0.05 ng, 0.15 ng for daidzin, respectively. The intra- and inter-day precisions(RSDs) were less than 6.5% and average recoveries of puerarin were 99.7-101.3% and those of daidzin were 101.0-102.8%. Conclusions: According to above results, we developed a determination method for puerarin and daidzin in Puerariae Radix with high sensitivity and selectivitely.

• 한국인터넷방송통신학회논문지
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• 제15권6호
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• pp.291-296
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• 2015

주행 중인 차량의 타이어와 노면 사이에서 발생하는 랜덤성 초음파신호의 주기성을 검출하여 타이어의 손상을 분별하는 방법에 대하여 연구하였다. 잡음으로부터 타이어손상에 의한 유효한 펄스를 검출하기 위해 적응 임계치를 설정하는 방법을 제안하였고, 이를 위한 전처리로서 신호의 랜덤성을 감소시키는 저역통과필터를 사용하였다. 자동차의 속도에 따라 검출된 펄스의 시간간격을 밀도함수화하고 피크점의 시간을 측정하여 타이어 손상물질을 검출하는 방법을 제안하였다. 손상물질이 한 개이고, 주행속도가 50km/h, 80km/h, 100km/h 일 때, 시간밀도함수의 제 1 피크시간 측정결과는 각각 169.8ms, 97.9ms, 81.8ms로 주행속도에 따라 계산한 타이어 회전주기의 오차범위내로 측정되었으며, 한개 이상의 손상물질의 경우에는 각 피크시간의 합이 타이어 회전주기의 오차범위내로 측정되는 결과를 얻을 수 있었다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 추계학술대회 논문집
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• pp.60-65
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• 1998

Recently, It is gradually raised necessity that thickness of thin film is measured accuracy and managed in industrial circles and medical world. Ultrasonic Signal processing method is likely to become a very powerful method for NDE method of detection of microdefects and thickness measurement of thin film below the limit of Ultrasonic distance resolution in the opaque materials, provides useful information that cannot be obtained by a conventional measuring system. In the present research, considering a thin film below the limit of Ultrasonic distance resolution sandwiched between three substances as acoustical analysis model, demonstrated the usefulness of ultrasonic Signal processing technique using information of ultrasonic frequency for NDE of measurements of thin film thickness, sound velocity, and step height, regardless of interference phenomenon

• 상하수도학회지
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• 제27권6호
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• pp.827-836
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• 2013

Due to the stringent drinking water quality, formaldehyde will be included in Korean drinking water standard from year 2014. However, its standard analytical method has not yet been established. This study compares two analytical methods, DNPH-LC and ACFAS with respect to their analysis principles, Method Detection Limit (MDL), Limit Of Quantitation(LOQ), precision, accuracy, reproducibility, convenience, number of samples analyzed per hour and analysis cost. These methods measure absorption intensity at 360 nm by using HPLC after DNPH-derivatization (DNPH-LC) and at 410 nm by using Automated Continuous Flow Absorption Spectrophotometer (ACFAS), respectively. Reproducibility was tested by repeating the analysis 7 times using a standard solution for each method. For DNPH-LC method, MDL was $0.5{\mu}g/L$, LOQ was $1.58{\mu}g/L$ with standard deviation of $0.16{\mu}g/L$. For ACFAS method, they were $0.27{\mu}g/L$, $0.85{\mu}g/L$L with standard deviation of $0.09{\mu}g/L$, respectively. Both methods satisfied the requirement set by the Korean drinking water quality standard. Complexity of sample pretreatment procedure for DNPH-LC method may cause large error and, consequently, the analytical result will depend on the level of skill of analyst. In contrast, ACFAS method which used only one reagent equipped with an automated injection device showed little analytical error. It costs about $5.00 and $1.00 for one sample to analyze by the DNPH-LC method and the ACFAS method, respectively. Compared to the DNPH-LC method, ACFAS method provided more reliable analytical results. In terms of convenience, easiness and analytical cost, ACFAS method was demonstrated to be superior to the DNPH-LC method. The results of this study suggested that the ACFAS method could be adapted as a proper method for determining formaldehyde content in drinking water.

• International Journal of Oral Biology
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• 제42권4호
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• pp.197-201
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• 2017

A novel method for the detection of hydrogen peroxide in aqueous solution was developed via reaction between $H_2O_2$, trivalent titanium ion ($Ti^{3+}$) and 4-(2-thiazolylazo) resorcinol (TAR), resulting in a ternary complex with a maximum UV absorbance at 530 nm. The CE detection of $H_2O_2$ was fast, sensitive and cost-effective without pretreatment procedures. $H_2O_2$ was detected within 15 min at 1 to $100{\mu}M$ range with the lowest detection limit at $1.0{\mu}M$. Under the optimized CE conditions, the concentration of $H_2O_2$ in coffee or tea extract was quantitatively determined. Our results show that CE detection of the ternary complex of $H_2O_2-Ti^{3+}$-TAR has potential applications for the detection of $H_2O_2$ in aqueous sources.