• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.2
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• pp.189-195
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• 2003

The objective of this study is to improve the optical sensitivity of laser fluorescence for detection of incipient enamel caries. An incipient carious lesion was formed in various stages by placing an enamel specimen of a bovine tooth in STPP demineralization solution. After measuring the optical density of the lesion surface by laser fluorescence induced by argon laser and various alter of yellow(500-520nm), amber(520-540nm), orange(540-560nm), and red(560-580nm), the specimen was cut vertically to measure the depth of the lesion using a polarizing microscope. SAS statistical program was used to analyze the relationship between the optical density of the lesion suface and the depth of the lesion. The results were as follows: 1. The optical density of early carious lesion, measured by laser fluorescence with amber and orange filter, and lesion depth observed by polarizing microscope, were increased as demineralization time increased. 2. The correlation coefficient between optical density of the lesion surface and the histological depth of the lesion was the highest in orange filter(r=0.49), followed by amber(r=0.32), yellow(r=0.13) and red(0.01). 3. Regression analysis showed that the most linear relationship between the optical density and the lesion depth was existed in orange filter group. In regard above results, laser fluorescence could be considered to be reliable for optical diagnosis of dental caries.

• Journal of Radiation Protection and Research
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• v.45 no.3
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• pp.117-129
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• 2020

Background: Radiation portal monitors (RPMs) involving plastic scintillators installed at the border inspection sites can detect illicit trafficking of radioactive sources in cargo containers within seconds. However, RPMs may generate false alarms because of the naturally occurring radioactive materials. To manage these false alarms, we previously suggested an energy-weighted algorithm that emphasizes the Compton-edge area as an outstanding peak. This study intends to evaluate the identification of radioactive sources using an improved energy-weighted algorithm. Materials and Methods: The algorithm was modified by increasing the energy weighting factor, and different peak combinations of the energy-weighted spectra were tested for source identification. A commercialized RPM system was used to measure the energy-weighted spectra. The RPM comprised two large plastic scintillators with dimensions of 174 × 29 × 7 ㎤ facing each other at a distance of 4.6 m. In addition, the in-house-fabricated signal processing boards were connected to collect the signal converted into a spectrum. Further, the spectra from eight radioactive sources, including special nuclear materials (SNMs), which were set in motion using a linear motion system (LMS) and a cargo truck, were estimated to identify the source identification rate. Results and Discussion: Each energy-weighted spectrum exhibited a specific peak location, although high statistical fluctuation errors could be observed in the spectrum with the increasing source speed. In particular, ¹³⁷Cs and ⁶⁰Co in motion were identified completely (100%) at speeds of 5 and 10 km/hr. Further, SNMs, which trigger the RPM alarm, were identified approximately 80% of the time at both the aforementioned speeds. Conclusion: Using the modified energy-weighted algorithm, several characteristics of the energy weighted spectra could be observed when the used sources were in motion and when the geometric efficiency was low. In particular, the discrimination between ⁶⁰Co and ⁴⁰K, which triggers false alarms at the primary inspection sites, can be improved using the proposed algorithm.

• Progress in Medical Physics
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• v.29 no.2
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• pp.59-65
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• 2018

This paper describes the clinical use of the dose verification of multileaf collimator (MLC)-based CyberKnife plans by combining the Octavius 1000SRS detector and water-equivalent RW3 slab phantom. The slab phantom consists of 14 plates, each with a thickness of 10 mm. One plate was modified to support tracking by inserting 14 custom-made fiducials on surface holes positioned at the outer region of $10{\times}10cm^2$. The fiducial-inserted plate was placed on the 1000SRS detector and three plates were additionally stacked up to build the reference depth. Below the detector, 10 plates were placed to avoid longer delivery times caused by proximity detection program alerts. The cross-calibration factor prior to phantom delivery was obtained by performing with 200 monitor units (MU) on the field size of $95{\times}92.5mm^2$. After irradiation, the measured dose distribution of the coronal plane was compared with the dose distribution calculated by the MultiPlan treatment planning system. The results were assessed by comparing the absolute dose at the center point of 1000SRS and the 3-D Gamma (${\gamma}$) index using 220 patient-specific quality assurance (QA). The discrepancy between measured and calculated doses at the center point of 1000SRS detector ranged from -3.9% to 8.2%. In the dosimetric comparison using 3-D ${\gamma}$-function (3%/3 mm criteria), the mean passing rates with ${\gamma}$-parameter ${\leq}1$ were $97.4%{\pm}2.4%$. The combination of the 1000SRS detector and RW3 slab phantom can be utilized for dosimetry validation of patient-specific QA in the CyberKnife MLC system, which made it possible to measure absolute dose distributions regardless of tracking mode.

• Biomedical Science Letters
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• v.3 no.1
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• pp.29-35
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• 1997

Cardiovascular disease has been the leading cause of death among patients with chronic renal failure. Many reports have been described that homocysteine is one of the independent risk factor to the occulsive vascular disease. In this study, HPLC/FLD (high performance liquid chromatography-fluorescence detector) technique was used to measure homocysteine level in patients with chronic renal failure and normal control group. The detection limit and recovery of total plasma homocysteine using HPLC/FLD were 98.6$\pm$5.8% and 0.2 nmol/ml, respectively. The linearity of this method was established in concentration range of 2~50 nmol/ml (correlation coefficient=0.9997). The concentrations of total plasma homocysteine were 6.81$\pm$1.54 nmol/ml and 27.28$\pm$14.94 nmol/ml in normal control (n=20) and patient group (n=90), respectively (p<0.05). In this study, the HPLC/FLD method showed high sensitivity and reproducibility for a routine clinical laboratory testing. Moreover determination of homocysteine level in plasma might be useful for a biochemical marker for predicting the cardiovascular diseases and for monitoring of therapeutic effect of lowering homocysteine in patients with chronic renal failure.

• KSBB Journal
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• v.24 no.5
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• pp.432-438
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• 2009

Here, we demonstrated simple nucleic acid, RNA, concentration method using polymer micro chip containing glass bead ($100\;{\mu}m$). Polymer micro chip was fabricated by PDMS ($1.5\;cm\;{\times}\;1.5\;cm$, $100\;{\mu}m$ in the height) including pillar structure ($160\;{\mu}m\;(I)\;{\times}\;80\;{\mu}m\;(w)\;{\times}\;100\;{\mu}m\;(h)$, gap size $50\;{\mu}m$) for blocking micro bead. RNA could be adsorbed on micro glass bead at low pH by hydrogen bonding whereas RNA was released at high pH by electrostatic force between silica surface and RNA. Amount of glass beads and flow rate were optimized in aspects of adsorption and desorption of RNA. Adsorption and desorption rate was measured with real time PCR. This concentrated RNA was applied to amplification micro chip in which NASBA (Nucleic Acid Sequence Based Amplification) was performed. As a result, E.coli O157 : H7 in the concentration of 10 c.f.u./10 mL was successfully detected by these serial processes (concentration and amplification) with polymer micro chips. It implies this simple concentration method using polymer micro chip can be directly applied to ultra sensitive method to measure viable bacteria and virus in clinical samples as well as environmental samples.

• Analytical Science and Technology
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• v.25 no.3
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• pp.190-196
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• 2012

The human exposure of lead has usually detected the amount of lead in the whole blood, however, this method has a shortcoming to give the information on the short-term exposure to lead. In that sense, it is desirable to estimates the level of lead in plasma to draw the chronic bio-marker of lead exposure even though it is difficult to measure lead of several ng/L. An inductively coupled plasma-mass spectrometry (ICP-MS) method was developed for determining lead in plasma as the chronic bio-marker of lead of workers. To minimize the contamination of lead from the environment, we constructed class 1,000 clean room and compared the amount of floating dust before and after the operation of the clean room. The limit of detection (LOD) and the limit of quantification (LOQ) of lead in fetal bovine serum were 4.3 ng/L and 12.2 ng/L by NIOSH method (statistical calculation method) and 7.0 ng/L and 22.1 ng/L by signal/noise ratio, respectively. The accuracy was in a range of 92.3-101.3%, and the precision of the assay was less than 4% in the samples spiked in the concentration of 20 ng/L and 2,000 ng/L. The method was simple, reproducible and sensitive enough to permit reliable analysis of lead to the ng/L level in plasma and/or serum. The method was also useful for the biological monitoring of chronic exposure to lead.

• Journal of Sensor Science and Technology
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• v.9 no.6
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• pp.404-415
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• 2000

This paper describes several performances and nondestructive inspection for deterioration due to forest fires in overhead transmission lines. After discussing corrosion mechanism such as atmospheric and galvanic corrosion for aged ACSR conductors and its detection for them are presented. Through impedance analysis of a solenoid coil, it is shown that the eddy current sensor may be available to inspect severe fault or local corrosion. As the solenoid coil changes its impedance when the test conductor is inserted into the coil, it can be possible to measure deterioration degree caused by forest fires. Tensile strength, extension rate and sensor impedance are tested for some samples degraded by artificial fire. As increasing blazed period to some extent, the strength of aluminum strand begins to be reduced remarkably, while galvanized steel strand holds the similar strength to the initial value, despite of appearing a little loss of zinc layer. In general, it is shown that the sensor impedance would be increased while the tension load of conductor is reduced and the extension rate is contrarily increased. Therefore, the sensor output could exhibit the changes of mechanical performances, and would be used to detect such deterioration caused by forest fire in ACSR conductors built on the ridge of mountains. Finally, it was verified that the solenoid coil could be applicable to obtain any crucial inform for serious deterioration due to forest fires.

• Science of Emotion and Sensibility
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• v.18 no.2
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• pp.85-100
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• 2015

This study aimed at examining if the original memory remains after a misinformation is presented, using Event-Related Potential based Concealed Information Test (ERP-based CIT). In the first stage of the study, the participant was presented with either the original information or a misleading information after experiencing an event (Post-information). The second stage was to measure brain wave and reaction time on the original, misleading, and irrelevant information (CIT-Stimulus). P300 amplitude, P300 area, P300 latency, and reaction time were used as dependant variables. In the result, a significant Post-information ${\times}$ CIT-Stimulus interaction effect was found on the P300 area measured at Cz, Pz, and Oz area. This interaction effect implied the possibility that the original information could be partially impaired in memory by misleading information presented afterward. P300 amplitude at Pz area did not differ between the accurate and the misleading stimuli in the condition in which a misleading information was presented. This result can be explained by source monitoring error. In discussion, the limitations of this study and directions of future studies were discussed.

• Korean Journal of Remote Sensing
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• v.32 no.6
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• pp.617-627
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• 2016

Many kinds of OGC-based web standards have been utilized in the lots of geo-spatial application fields for sharing and interoperable processing of large volume of data sets containing satellite images. As well, the number of cloud-based application services by on-demand processing of virtual machines is increasing. However, remote sensing applications using these two huge trends are globally on the initial stage. This study presents a practical linkage case with both aspects of OGC-based standard and cloud computing. Performance test is performed with the implementation result for cloud detection processing. Test objects are WPS 2.0 and two types of geo-based service environment such as web server in a single core and multiple virtual servers implemented on OpenStack cloud computing environment. Performance test unit by JMeter is five requests of GetCapabilities, DescribeProcess, Execute, GetStatus, GetResult in WPS 2.0. As the results, the performance measurement time in a cloud-based environment is faster than that of single server. It is expected that expansion of processing algorithms by WPS 2.0 and virtual processing is possible to target-oriented applications in the practical level.

• Korean Journal of Veterinary Service
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• v.17 no.2
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• pp.95-113
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• 1994

To establish an effective diagnostic measure for detection of the antibodies against Actinobacillus pleuropneumoniae, the methods for tube agglutination test (TAT), plate agglutination test (PAT), micro-agglutination test(MAT) and agar-gel immunodiffusion test(ID) were improved and standarized, and the comparative studies were carried out. The results obtained through the experiments were summarized as follows. 1. The rabbit hyperimmune sera to reference serotypes 1 to 6 were cross-tested with TAT, PAT, MAT and ID. In the homologous systems, the range of antibody titers in TAT was 80 to 640, showing the cross-reaction in serotypes 3, 4, 5 and 6. The range of antibody titers in PAT was 4 to 64, showing the cross-reaction in serotypes 3, 4, 5 and 6. In ID, the range of antigen titers was 8 to 32, and cross-reaction was observed in serotype 5. 2. The optimal concentration of antigen in PAT and MAT were 100mg /ml and 1.25mg /ml respectively. The most sensitive reaction in MAT was observed in 52$^{\circ}C$ for 18hrs. 3. In ID, the most promising antigen and the buffer for agar-gel were EDTA-treated antigen and 0.05M tris buffer (pH 7.2), respectively. 4. By the tests for 200 swine sera, it was found that the frequency of positive reaction were 203 in TAT, 240 in PAT and 163 in ID. 5. When compared the titers of TAT with those of MAT for 200 swine sera, MAT showed the higher titer than TAT being increased by relative correlation. Int was found that the titer for positive readings were 20 in TAT and 40 in MAT. 6. when compared the results of ID with those of TAT for 200 swine sera, all sera with TAT titer under 10 were negative in ID. Of the sera with TAT titer 20 and 40, 55.1% nd 91.8% were positive in ID, respectively. All sera with TAT titer above 80 were positive in ID. In comparison of ID and MAT, all sera with MAT titer under 20 were negative in ID. Of the sera with MAT titer 40 and 80, 24.7% and 93.9% were positive in ID, respectively. All sera with MAT titer over 160 showed positive in ID. 7. In conclusion, the established MAT showed high sensitivity but low specificity, wherease ID revealed low sensitivity but high specificity.