• Bulletin of the Korean Chemical Society
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• 제33권12호
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• pp.4145-4149
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• 2012

A novel and simple method of luminescence enhancement effect for the determination of trace amounts of bile acid was proposed. The procedure was based on the luminescence intensity of the balofloxacin-europium(III) complex that could be strongly enhanced by bile acid in the presence of sodium dodecyl benzene sulfonate (SDBS). Under the optimum conditions, the enhanced luminescence intensity of the system exhibited a good linear relationship with the bile acid concentration in the range $5.0{\times}10^{-9}-7.0{\times}10^{-7}\;mol\;L^{-1}$ with a detection limit of $1.3{\times}10^{-9}\;mol\;L^{-1}$ ($3{\sigma}$). The relative standard deviation (RSD) was 1.7% (n = 11) for $5.0{\times}10^{-8}\;mol\;L^{-1}$ bile acid. The applicability of the method to the determination of bile acid was demonstrated by investigating the effect of potential interferences and by analyzing human serum and urine samples. The possible enhancement mechanism of luminescence intensity in balofloxacin-europium(III)-bile acid-SDBS system was also discussed briefly.

• 응용화학
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• 제15권1호
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• pp.37-40
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• 2011

A chemiluminescent method with silver nanoparticles for determination of L-alanine has been presented. The chemilumiscence intensity was further enhanced by silver nanoparticles in the luminol system by its catalytic role. The silver nanoparticles enhanced chemiluminescent method is applicable for the determination of an amino acid such as alanine. When alanine was introduced to the luminol system with silver nanoparticles, chemiluminescence intensity was reduced with the concentration of the added alanine. The effects of pH, concentrations of luminol, hydrogen peroxide and silver nanoparticles on the chemiluminescence intensity were investigated. The calibration curve for L-alanine was linear over the range from 6.60×10^-8 M to 4.00×10^-7 M, coefficient of correlation was 0.996 and detection limit was 3.5×10^-9 M under the optimal conditions of 4.0×10^-3 M, 4.0×10^-2 M, 4.0×10^-4 M, 12.8 for the concentration of luminol, H₂O₂, silver nanoparticles and pH, respectively.

• 한국도로학회논문집
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• 제13권1호
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• pp.157-168
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• 2011

최근 국내 콘크리트포장의 동결융해 파손에 대한 사례들이 주기적으로 보고가 되고 있으며, 이에 공기량 기준과 더불어 간격계수에 대한 기준마련 필요성이 대두되고 있다. 간격계수를 산정하기 위한 실험방법은 국내에 규정되어 있지 않아 ASTM C 457기준을 따라야 하며, 특히 이 실험결과 분석 시 연구자의 주관적 판단에 기인하는 경우가 많아 이에 대한 철저한 보정작업이 수반되어야 한다. 콘크리트의 공극구조 특성을 분석하기 위해 사용되고 있는 화상분석프로그램은 색상의 구분을 통해 공극을 인식하는데, 분석 시 사용되어지는 pixel intensity values에 따라 분석결과는 크게 변할 수 있다. 이에 본 연구에서는 pixel intensity values의 적정범위를 산정하기 위해서, pixel intensity values 변화에 따라 측정된 공극수와 연구자들이 측정한 공극수를 비교하였으며, 이를 통해 pixel intensity values의 적정 범위를 결정하였다. 또한 결정된 pixel intensity values를 이용하여, 8가지 콘크리트 혼합물에 대한 콘크리트 공극구조 특성을 분석하였다. 연구자들이 공극수를 직접 측정한 round robin test 결과, 사람에 따른 공극 인식정도가 약 10% 정도로 변동될 수 있음을 확인할 수 있었으며, 이를 통해 pixel intensity values의 적정 범위가 약 80~90 정도로 나타났다. 8가지 콘크리트 혼합물에 대한 화상분석결과, 전반적으로 AE제 첨가량이 증가함에 따라 전체 공기량은 증가하고 간격계수는 감소하는 경향을 나타내었으나, 일부 혼합물에서 공기량은 크게 변동하지 않은 가운데 간격계수가 AE제 증가에 따라 감소하는 추이를 나타내었다. 이는 추가된 AE제에 의해 발생된 미세한 크기의 연행공극이 전체 공기량에 미치는 영향보다 간격계수에 미치는 영향이 더 크기 때문이다. 또한 동일한 시편에서 절단면 위치에 따른 간격계수의 편차는 약 30~100${\mu}m$ 정도를 나타내었다. 이는 2차원 분석의 한계로 인해 발생된 편차인 것으로 사료되며, 시편절단면 위치에 따른 변동성 분석을 위한 추가적인 연구가 수행되어야 할 것으로 판단된다.

• 한국산림과학회지
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• 제85권3호
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• pp.396-408
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• 1996

본 연구는 우리나라 간벌림 벌채작업에서 작업강도를 구명하여 산림작업을 성력화하며, 아울러 작업방법의 개선과 생산성 향상을 도모하는데 그 목적이 있다. 이를 구명하기 위하여 침엽수 간벌림에서 벌채작업을 요소작업으로 구분하여 순수작업시간과 맥박수를 측정 분석하였으며, 그 결과는 다음과 같다. 1. 맥박수 측정 분석에서 전체 순수작업시간에서의 1분당 평균맥박수는 작업원 A의 경우 108로 나타났으며, 작업원 B의 경우 130, 작업원 C는 119, 그리고 작업원 D는 125로 나타났다. 2. 요소작업 구분별로 맥박수를 분석한 결과에서는 1분당 맥박수가 가장 높을 때는 작업원 A의 경우 주위정리에서 115였고, 작업원 B는 이동에서 131, 작업원 C는 지타작업에서 122, 작업원 D는 현목처리에서 128로 나타났다. 3. 작업원별로 기준맥박을 100%로 보았을 때 작업강도는 작업원 A(기본맥박 61=100%)가 전체 작업강도 160%, 요소작업 구분중에서는 주위정리가 188%로 가장 높게 나타났다. 작업원 B(기본맥박 57=100%)의 전체 작업강도는 220%, 요소작업중에서는 이동이 229%로 가장 높았으며, 작업원 C(기본맥박 73=100%)의 경우에는 전체 강도는 159%, 요소작업중에서는 지타작업이 168%로 가장 높았고, 작업원 D(기본맥박 70=100%)는 전체 작업강도 156%, 요소작업중에서는 현목처리가 182%로 가장 높게 나타났다. 4. 전체 작업강도를 나다내는 작업원에 따른 노동이행능력 한계점에서의 1분당 초과맥박수는 작업원 A의 경우 30, 작업원 B의 경우 207, 작업원 C는 14이며, 작업원 D는 67로 작업원 B가 가장 작업강도가 높아 신체적인 부담을 크게 받는 것으로 나타났다.

• Structural Engineering and Mechanics
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• 제22권3호
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• pp.293-310
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• 2006

In seismic prone areas it is possible to meet very different objects (equipment components, on shelf artefacts, simple architectural elements) that can be modelled as a rigid body rocking on a rigid foundation. The interest in their behaviour can have different reasons: seismological, in order to estimate the ground motion intensity, or more strictly mechanical, in order to limit the response severity and to avoid overturning. The behaviour of many rigid bodies subjected to twenty wide ranging acceleration recordings is studied here. The response of the blocks is described using kinematic and energy parameters. A condition under which a so called scale effect is tangible is highlighted. The capacity of the signals to produce overturning is compared to different ground motion parameters, and a good correlation with the Peak Ground Velocity is unveiled.

• 세라미스트
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• 제10권3호
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• pp.91-97
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• 2007

Femtosecond laser micro-processing received much attention in the past decade. The nature of ultra-short light-matter interaction permits femtosecond laser to overcome the diffraction limit and realize precise micro-processing. The ultrahigh light intensity of the femtosecond laser allows sapece-selective microscopic modifications to materials based on multiphoton processes. In this paper, we review our recent research development on space-selective precipitation and control of functional crystals in glasses by an infrared femtosecond laser. The technique will open new possibilities in the fabrication of micro-optical components with various optical functions.

• 오토저널
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• 제3권3호
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• pp.30-38
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• 1981

The fatigue characteristics of Si-Mn spring steel (AISI 9260-H, JIS SUP-6) were investigated on several heat treatment conditions. Repeated impact loads of 10kg-cm and 15kg-cm energy were applied with a cam roller drop hammer type impact fatigue testing machine. Specimens were oil-quenched, and tempered at 350.deg. C, 450.deg. C and 500.deg. C, respectively. Results obtained in these experiments are summarized as follows.; 1) The fatigue life of the specimen is decreased as the magnitude of constant impact energy is increased, regardless of heat treatment. 2) Generally, the fatigue life of the specimen is decreased as the tensile strength of the materials is increased. 3) Within the limit of these experiments, the fatigue life showed abrupt decrease at the tempering temperature of about 400.deg. C 4) The fatigue life is increased as the initial value of applied stress intensity factor(K$_{1}$) is decreased. This tendency is apparent for the low tensile strength materials.

• 한국해양공학회지
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• 제5권2호
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• pp.58-66
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• 1991

Not only difference of fatigue crack growth and propagation behavior resulted from the grain size, the hardness ratio and volume fraction in M.E.F. dual phase steel composed of martensite in hard phase and ferrite in soft phase, but also the effects of the plastic constraint were investigated by fracture mechanics and microstructural method. The main results obtained are as follows: 1) The fatigue endurance of M.E.F. steel increases with decreasing the grain size, increasing the ratio of hardness and volume fraction. 2) The initiation of slip and crack occures faster as the stress level goes higher. These phenomena result from the plastic constraint effect of the second phase. 3) The crack propagation rate in the constant stress level is faster as the grain size gets larger, the ratio of hardness lower and volume fraction smaller.

• 한국자동차공학회논문집
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• 제7권6호
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• pp.42-48
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• 1999

Engine misfire causes of the negative effect on exhaust emission such as HC, CO, and NOX . Moreover, it causes damage to the three-way-catalyst(TWC) system permanently. The crankshaft velocity fluctuation(CVF) method has been applied for the real cars as misfire detection system usually, which utilizes the crank angle sensor input to calculate the variation of the crankshaft rotational speed. But this approach has the limit due to the fact that three could be problem under certain engine condition like as deceleration or high speed condition . Therefore the development of new methods are requested today. This study introduced the new method of misfire detection using breakdown voltage(BDV) characteristics between spark plug electrouds.

• 한국대기환경학회지
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• 제14권5호
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• pp.421-432
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• 1998

Deposition processes limit the life time of pollutants in the atmosphere and control the distance travelled before deposition. Thus the understanding about atmospheric deposition processes is essential for a proper assessment of the environmental impacts due to the anthropogenic pollutants. The dry deposition velocities are related to surface types, atmospheric stabilities, friction velocities, air pollutants and so on. In this study we simulated the dry deposition velocities of O3 in Pusan region. The calculated deposition velocities compared to the observed O3 data obtained during the summer of 1988 over a deciduous forest in Canada. The comparison showed that the model somewhat overpredicted deposition velocities for the average diurnal variations with maxima in daytime and minima in nighttime mostly due to the turbulence intensity.