• Journal of the Korean Chemical Society
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• v.46 no.4
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• pp.309-317
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• 2002

A spectrofluorimetric method for the simultaneous determination of amino acids (tryptophan and tyrosine) based on the application of multivariate calibration method such as principal component regression and partial least squares (PLS) to luminescence measurements has been studied. Emission spectra of synthetic mixtures of two amino acids were obtained at excitation wavelength of 257 ㎚. The calibration model in PCR and PLS was obtained from the spectral data in the range of 280-500 ㎚ for each standard of a calibration set of 32 standards, each containing different amounts of two amino acids. The relative standard error of prediction ($RSEP_a$) was obtained to assess the model goodness in quantifying each analyte in a validation set. The overall relative standard error of prediction ($RSEP_m$) for the mixture obtained from the results of a validation set, formed by 6 independent mixtures was also used to validate the present method.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.1
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• pp.95-102
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• 2007

It needs to Prevent damage as aging shotcrete itself exists as a dangerous component to comuting vehicles or infrastructure due to scaling, spaling, and loosening. However, it is hard to make an approach owing to a steep slope and high work, and there has been indicated a limit that it is difficult to grasp the internal condition of shotcrete on the surface. This study aimed to research internal defects that cannot be observed from the surface, by measuring a subtle thermal transfer on the shotcrete surface by using infrared thermography for overcoming such a technical limit. As a result of conducting an inspection through an analysis on measured data and fieldwork using an endoscope camera, it was impossible to accurately determine the wet part because of an excessive coating of shotcrete, yet, This study is proposed effictively extract a void part of the inside with non-destructive and non-touching method.

• Journal of the Korean Chemical Society
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• v.46 no.2
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• pp.145-150
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• 2002

A Method to determine Cr(III)ion in aqueous solution by chemiluminescence method using a stopped flow system has been studied. The method is based on the increased chemiluminescence intensity with the addition of Cr(III) to a solution of lucigenin a nd hyrogen peroxide. The effects of pH, injection volumes of reagent and sample, and concentration of lucigenin and hyrogen peroxide on the chemiluminescence intensity have been investigated. The calibration curve for Cr(III) ion was linear over the range from 1.0${\times}$$10^{-6}$ to 1.0${\times}$$10^{-3}$M and the detection limit was 5.2${\times}$$10^{-8}$M under the optimal experimental condition of 437nm, 12.8,and 1.0${\times}$$10^{-6}$ and 2.0M for emission wavelength, pH, and concentration of lucigenin and hyrogen peroxide, respectively.

• Journal of the Korean Chemical Society
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• v.44 no.6
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• pp.573-580
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• 2000

MPT, which has been developed recently, is very tolerant to aqueous samples. Several types of MPT have been investigated and is found that the double concentric tube could sustain a stable plasma at a low plasma gas flow rate. However, the tip of torch is easily ruined. Triple concentric torch has shown the best stability and the plasma shape, much like that of ICP, especially when the central channel is quartz. The plasma is exposed and mixed with air as is suggested from the background spectrum, which leads to quenching of He MPT. Sensitivity of helium MPT equipped with a membrane desolvator has shown 10 times lower than that of Argon MPT for most of elements except for the ones with relatively high excitation energy. He MPT requires small plasma flow rate (about 1.6 L/min), stable and simple to use. Excitational temperature and electron number density measured are 4950 K and 3.28 ${\times}$ $10^{14}cm^{-3}$, respectively.

• Journal of Convergence for Information Technology
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• v.10 no.3
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• pp.217-226
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• 2020

The study was conducted to investigate the improvement nail health in middle-aged women aged 40~60 years who intake soybean koji by incubating Aspergillus oryzae(황국균), and utilized non-fermented soybeans as a control group and soybean koji as an experiment group for eight weeks. After clinical trials, the lifting and cracking conditions of the nails in the experiment group were improved, The moisture content increased 5.1 times compared to the control group, The water loss was 1.4 times less the reduction to the control group. and nail thickness increased by 1.9 times compared to controls. Wrinkles on the surface improved by about 2.4 times compared to the control group. In conclusion, consumption of this soybean koji of A. oryzae's has been shown to have an impact on improving nail is expected to be used Therefore, I propose this soybean koji of A. oryzae's as an inner beauty for improving nail is in middle-aged women aged 40~60 years.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.9
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• pp.789-795
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• 2016

Laser-induced combustions and explosions generated by high laser irradiances were explored by Laser-Induced Breakdown Spectroscopy (LIBS). The laser used for target ablation is a Q-switched Nd:YAG laser with 7 ns pulse duration at wavelength of 1064 nm laser energies from 40 mJ to 2500 mJ ($6.88{\times}10^{10}-6.53{\times}10^{11}W/cm^2$). The plasma light source from aluminum detected by the echelle grating spectrometer and coupled to the gated ICCD(a resolution (${\lambda}/{\Delta}{\lambda}$) of 5000). This spectroscopic study has been investigated for obtaining both the atomic/molecular signals of aluminum-oxygen and the calculated ambient condition such as plasma temperature and electron density. The essence of the paper is observing specific electron density ratio which can support the processes of chemical reaction and combustion between ablated aluminum plume and oxygen from air by inducing high laser energy.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.6
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• pp.511-520
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• 2000

Ultrasonic pulse echo method comes to be difficult to apply to the multi-layered structure with very thin layer, because the echoes from the top and the bottom of the layer are superimposed. We can easily meet this problem when the silicon chip layer in the semiconductor is inspected by a SAM equipment using fairly low frequency lower than 20MHz by which severe attenuation in the epoxy mold compound of packaging material can be overcome. Conventionally, deconvolution technique has been used for the decomposition of superimposed UT signals, however it has disabilities when the waveform of the transmitted signal is distorted according to the propagation. In this paper, the wavelet transform based deconvolution(WTBD) technique is proposed as a new signal processing method that can decompose the superimposed echo signals with superior performances compared to the conventional deconvolution technique. WTBD method uses the wavelet transform in the pre-stage of deconvolution to extract out the common waveform from the transmitted and received signal with distortion. Performances of the proposed method we shown by through computer simulations using model signal with noise and we demonstrated by through experiments for the fabricated semiconductor sample with partial delamination at the top of silicon chip layer.

• The Journal of the Convergence on Culture Technology
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• v.8 no.6
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• pp.727-732
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• 2022

Applying the calculated cross-sectional reduction due to the corroded rebar investigated in the field to the numerical analysis model, the damage pattern and delamination of concrete in the field showed a tendency relatively similar to the numerical analysis results. It was analyzed that when the expansion pressure due to corrosion of the reinforcing bar is greater than the tensile stress of the concrete, cracks are generated and the concrete cover can be fracture. As a result of this study, the correlation between the corrosion rate of reinforcing bars and the crack occurrence of the concrete cover of the subway box structure was verified based on the numerical analysis and field test results. To prevent rebar corrosion, the corrosion rate can be reduced by applying rust prevention to the reinforcing bar and changing the material. In the case of exposed to a corrosive environment, the tensile strength of the concrete is improved by adjusting the concrete compressive strength to secure durability against the expansion pressure caused by the corroded rebar.

• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.3
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• pp.247-255
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• 2010

Bonding strength of shotcrete is a significant influential factor which plays the role of collapse prevention of tunnel crown and of debonding prevention of shotcrete induced by the blasting vibration. Thus, the evaluation of the shotcrete bonding state is one of the core components for shotcrete quality control. In this study, the peak particle velocities induced by blasting were measured on the shotcrete in a tunnel construction site and its effect on the bonding state of shotcrete is investigated. Drilling and blasting technique was used for the excavation of intersection tunnel connecting the main tunnel with the service tunnel. Blast-induced vibrations were monitored at some points of the main tunnel and the service tunnel. The shotcrete bonding state was evaluated by using impact-echo test coupled with the time-frequency domain analysis which is called short-time Fourier transformation. Analysis results of blast-induced vibrations and the time-frequency domain impact-echo signals showed that the blasting condition applied to the excavation of intersection tunnel hardly affects on the tunnel shotcrete bonding state. The general blasting practice in Korea was evaluated to have a minor negative impact on shotcrete quality.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.4
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• pp.177-186
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• 2005

The latest concrete structure has showed that the deterioration of durability has been increased by the damage from salt, carbonization, freezing & thawing and the others. Therefore, the measures for the concrete which has deteriorated durability have been taken. Among them, it has been often used that surface treatment which cuts off the deterioration factors of durability by protecting the surface of concrete. However, troubles such as fracture and rupture in the repair layer have been reported as time goes by due to the difference between the organic repair material like epoxy and concrete properties. Researchers have been developing the repair material which can cut off the deterioration factors of durability such as $CO_2$ gas, chloride ion and water by making the formation of concrete elaborate through the reaction with calcium ion when the surface improving agent is coated on the concrete. The main ingredient of that is inorganic substance which is the same as the concrete property. This study was evaluated the surface improving agent for permeability, watertightness, air-permeability, chemical resistance and elution resistance. As a result, it has been reported that the surface improving agent improves watertightness and air-permeability by penetration more than 10mm within concrete. Therefore, it is concluded that the surface improving agent developed in this research prevents deterioration of concrete durability when it is coated on the concrete structure.