• Korean Journal of Dental Materials
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• v.45 no.4
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• pp.257-274
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• 2018

The purpose of this study was to evaluate the effect of acid-treatment conditions on the surface properties of the RBM (Resorbable Blast Media) treated titanium. Disk typed cp-titanium specimens were prepared and RBM treatments was performed with calcium phosphate ceramic powder. Acid solution was mixed using HCl, $H_2SO_4$ and deionized water with 4 different volume fraction. The RBM treated titanium was acid treated with different acid solutions at 3 different temperatures and for 3 different periods. After acid-treatments, samples were cleaned with 1 % Solujet solution for 30 min and deionized water for 30 min using ultrasonic cleanser, then dried in the electrical oven ($37^{\circ}C$). Weight of samples before and after acid-treatment were measured using electric balance. Surface roughness was estimated using a confocal laser scanning microscopy, crystal phase in the surface of sample was analyzed using X-ray diffractometer. Surface morphology and components were evaluated using Scanning Electron Microscope (SEM) with Energy Dispersive X-ray spectroscopy (EDX) and X-ray Photoemission Spectroscopy (XPS). Values of the weight changes and surface roughness were statistically analyzed using Tukey-multiple comparison test (p=0.05). Weight change after acid treatments were significantly increased with increasing the concentration of $H_2SO_4$ and temperature of acid-solution. Acid-treatment conditions (concentration of $H_2SO_4$, temperature and time) did not produce consistent effects on the surface roughness, it showed the scattered results. From XRD analysis, formation of titanium hydrides in the titanium surface were observed in all specimens treated with acid-solutions. From XPS analysis, thin titanium oxide layer in the acid-treated specimens could be evaluated. Acid solution with $90^{\circ}C$ showed the strong effect on the titanium surface, it should be treated with caution to avoid the over-etching process.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.2
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• pp.110-116
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• 2010

Purpose: The X-ray attenuation coefficient based on CT images is used for attenuation correction in PET/CT. The polychromatic X-ray beam can introduce beam-hardening artifact on CT images. The aims of the study were to evaluate the effect of dental metal prostheses in phantom and patients on apparent tracer activity measured with PET/CT when using CT attenuation correction. Materials and Methods: 40 normal patients (mean age $54{\pm}12$) was scanned between Jan and Feb 2010. NEMA(National Electrical Manufactures Association) PET $Phantom^{TM}$ (NU2-1994) was filled with $^{18}F$-FDG injected into the water that insert implant and metal prostheses dental cast. Region of interest were drawn in non-artifact region, bright steak artifact region and dark streak artifact region on the same transaxial CT and PET slices. Patients and phantom with dental metal prostheses and dental implant were evaluated the change rate of CT Number and $SUV_{mean}$ in PET/CT. A paired t-test was performed to compare the ratio and the difference of the calculated values. Results: In patients with dental metal prostheses, $SUV_{mean}$ was reduced 19.64% (p<0.05) in the non-steak artifact region than the brightstreak artifact region whereas was increased 90.1% (p>0.05) in the non-steak artifact region than the dark streak artifact region. In phantom with dental metal prostheses, $SUV_{mean}$ was reduced 18.1% (p<0.05) in the non-steak artifact region than the bright streak artifact region whereas was increased 18.0% (p>0.05) in the non-steak artifact region than the dark streak artifact region. In patients with dental implant, $SUV_{mean}$ was increased 19.1% (p<0.05) in the non-steak artifact region than the bright streak artifact region whereas was increased 96.62% (p>0.05) in the non-steak artifact region than the dark streak artifact region. In phantom with dental implant, $SUV_{mean}$ was increased 14.4% (p<0.05) in the non-steak artifact region than the bright streak artifact region whereas was increased 7.0% (p>0.05) in the non-steak artifact region than the dark streak artifact region. Conclusion: When CT is used for attenuation correction in patients with dental metal prostheses, 19.1% reduced $SUV_{mean}$ is anticipated in the dark streak artifact region on CT images. The dark streak artifacts of CT by dental metal prostheses may cause false negative finding in PET/CT. We recommend that the non-attenuation corrected PET images also be evaluated for clinical use.

• Applied Biological Chemistry
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• v.50 no.4
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• pp.245-252
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• 2007

FTA (fault tree analysis), an analytical method for system failure management, was employed in the management of faults in running PCR analysis. PCR is executed through several processes, in which the process of PCR machine operation was selected for the analysis by FTA. The reason for choosing the simplest process in the PCR analysis was to adopt it as a first trial to test a feasibility of the FTA approach. First, fault events-top event, intermediate event, basic events-were identified by survey on expert knowledge of PCR. Then those events were correlated deductively to build a fault tree in hierarchical structure. The fault tree was evaluated qualitatively and quantitatively, yielding minimal cut sets, structural importance, common cause vulnerability, simulation of probability of occurrence of top event, cut set importance, item importance and sensitivity. The top event was 'errors in the step of PCR machine operation in running PCR analysis'. The major intermediate events were 'failures in instrument' and 'errors in actions in experiment'. The basic events were four events, one event and one event based on human errors, instrument failure and energy source failure, respectively. Those events were combined with Boolean logic gates-AND or OR, constructing a fault tree. In the qualitative evaluation of the tree, the basic events-'errors in preparing the reaction mixture', 'errors in setting temperature and time of PCR machine', 'failure of electrical power during running PCR machine', 'errors in selecting adequate PCR machine'-proved the most critical in the occurrence of the fault of the top event. In the quantitative evaluation, the list of the critical events were not the same as that from the qualitative evaluation. It was because the probability value of PCR machine failure, not on the list above though, increased with used time, and the probability of the events of electricity failure and defective of PCR machine were given zero due to rare likelihood of the events in general. It was concluded that this feasibility study is worth being a means to introduce the novel technique, FTA, to the management of faults in running PCR analysis.

• Korean Journal of Environmental Agriculture
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• v.33 no.4
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• pp.254-261
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• 2014

BACKGROUND: This study was conducted to investigate effects of silicate fertilizer application on red pepper (Capsicum annuum L.) productivity with improving soil chemistry under plastic film house in paddy field. METHODS AND RESULTS: The silicate fertilizer was applied as 0, 100, 200, and 300 kg/10a as basal dressing before transplanting pepper plant seedlings. Cultivar of the pepper plant was Cheon-Ha-Dae-Se. Amounts of inorganic fertilizer applied as $N-P_2O_5-K_2O$=19.0-6.4-10.1kg/10a was estimated depending on soil test values. After applying 50% of nitrogen, 100% of phosphorus, and 60% of potassium fertilizers as basal dressing, the seedlings of pepper plant were transplanted. The rests of nitrogen and potassium fertilizers were applied as side-dressing after the first, second, and fourth harvests of red pepper. When comparing selected chemical properties of soils between before transplanting and after final(the fifth) harvest, soil pH, available $P_2O_5$, and exchangeable $Ca^{2+}$ increased with increasing the applications of silicate fertilizer, whereas electrical conductivity(EC) decreased. However, exchangeable $K^+$ was higher with the treatments of 100 and 200 kg/10a, and exchangeable $Mg^{2+}$ was higher with 300 kg/10a application. In addition, nitrogen and phosphorus concentrations of red pepper collected from the first harvesting stage decreased with increasing the applications of silicate fertilizer, but potassium, calcium, and magnesium concentrations in red pepper were highest with 300 kg/10a application. Yield of red pepper increased between 9.0 and 11.8% with the applications of silicate fertilizer. Marketable fruit rate of res pepper was highest(97.3%) with 200 kg/10a application. CONCLUSION: The application of silicate fertilizer as basal dressing in paddy-converted fields improved soil chemistry and increased red pepper productivity.

• Korean Journal of Environmental Agriculture
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• v.27 no.3
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• pp.225-230
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• 2008

Objective of this study was to access the environmental impacts of the use of discharge water from municipal waste water treatment plant as alternative irrigation resources during drought season for rice cultivation. For the field experiments, it was observed that plant growth and yield characteristics at 20 days of alternative irrigation period with application of FAST (fertilizer application based on soil test) 50% were relatively the same as the control. For the surface water quality, it appeared that $EC_i$ (electrical conductivity of irrigation water) and SAR (sodium adsorption ratio) values of DMWT (discharge waters from municipal wastewater treatment plant) irrigation were twofold higher than those of ground water irrigation as the control regardless of fertilization levels. For the irrigation periods, there were not significantly difference between 10 and 20 days of treatments, but $EC_i$ and SAR values of surface water were highest at 30 days of irrigation periods at initial rice growing stages. Generally, $EC_i$ values of percolation water in all the treatments were gradually increasing until 30days after irrigation, and then decreasing to harvest stage. Overall, it might be considered that there was possibility to irrigate DMWT with application of FAST 50% for 20 days of drought periods at rice transplanting season. Furthermore, efficiency rate of alternative irrigation water for 20 days of drought period was 32.7% relative to the total annual irrigation water for rice cultivation.

• Journal of Bio-Environment Control
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• v.20 no.2
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• pp.93-100
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• 2011

Maintenance of adequate soil water potential during the period of crop growth is necessary to support optimum plant growth and yields. A better understanding of soil water movement within and below the rooting zone can facilitate optimal irrigation scheduling aimed at minimizing the adverse effects of water stress on crop growth and development and the leaching of water below the root zone which can have adverse environmental effects. The objective of this study was to evaluate the feasibility of using a portable irrigation controller with an Watermark sensor for the cultivation of drip-irrigated vegetable crops in a greenhouse. The control capability of the irrigation controller for a soil water potential of -20 kPa was evaluated under summer conditions by cultivating 45-day-old tomato plants grown in three differently textured soils (sandy loam, loam, and loamy sands). Water contents through each soil profile were continuously monitored using three Sentek probes, each consisting of three capacitance sensors at 10, 20, and 30 cm depths. Even though a repeatable cycling of soil water potential occurred for the potential treatment, the lower limit of the Watermark (about 0 kPa) obtained in this study presented a limitation of using the Watermark sensor for optimal irrigation of tomato plants where -20 kPa was used as a point for triggering irrigations. This problem might be related to the slow response time and inadequate soil-sensor interface of the Watermark sensor as compared to a porous and ceramic cup-based tensiometer with a sensitive pressure transducer. In addition, the irrigation time of 50 to 60 min at each of the irrigation operation gave a rapid drop of the potential to zero, resulting in over irrigation of tomatoes. There were differences in water content among the three different soil types under the variable rate irrigation, showing a range of water contents of 16 to 24%, 17 to 28%, and 24 to 32% for loamy sand, sandy loam, and loam soils, respectively. The greatest rate increase in water content was observed in the top of 10 cm depth of sandy loam soil within almost 60 min from the start of irrigation.

• Journal of Korea Soil Environment Society
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• v.4 no.1
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• pp.109-118
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• 1999

Recently, transport parameters of conservative solutes such as KCl in a porous medium have been successfully determined using time domain reflectometry (TDR) . This study was initiated to Investigate the applicability of TDR technique to monitoring the fate of a heavy metal ion in a sandy soil and the distribution of its concentration along travel distance with time. A column test was conducted in a laboratory that consists of monitoring both resident and flux concentrations of $ZnCl_2$in a sandy soil under a breakthrough condition. A tracer of $ZnCl_2$(10 g/L) was injected onto the top surface of the sample as pulse type as soon as a steady-state condition was achieved. Time-series measurements of resistance and electrical conductivity were performed at 10 cm and 20 cm of distances from the inlet boundary by horizontal-positioning of parallel TDR metallic rods and using an EC-meter for the effluent exiting the bottom boundary respectively. In addition. Zn ions of the effluent were analyzed by ICP-AES. Since the mode and position of concentration detected by TDR and effluent were different, comparison between ICP analysis and TDR-detected concentration was made by predicting flux concentration using CDE model accommodating a decay constant with the transport parameters obtained from the resident concentrations. The experimental results showed that the resident concentration resulted in earlier and higher peak than the flux concentration obtained by EC-meter, implying the homogeneity of the packed sandy soil. A close agreement was found between the predicted from the transport parameters obtained by TDR and the measured $ZnCl_2$concentration. This indicates that TDR technique can also be applied to monitoring heavy metal concentrations in the soil once that a decay constant is obtained for a given soil.

• Applied Microscopy
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• v.34 no.4
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• pp.231-239
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• 2004

Cerebral microvessel endothelial cells that form blood-brain barrier (BBB) have tight junction for maintaining brain homeostasis. Occludin, one of tight junction protein, is crucial for BBB function. $H_2O_2$ induced occludin changes and effects in bovine brain BBB endothelial cells were examined in this study. The decrease of transendothelial electrical resistance (TEER) by $H_2O_2$ was due to disruption of occludin localization. Cytotoxicity test revealed that $H_2O_2$ did not cause cell death below 1 mM $H_2O_2$ within 4 hr. $H_2O_2$ caused intermittent disruption and loss of occludin at tight junctions and occludin disappeared with dose dependent manner from tight junction in confocal laser microscopy. But Western blot revealed that the total amounts of occludin increased by $H_2O_2$ administration. Transmission electron microscopy revealed that the ultrastructure of tight junction was not changed by $H_2O_2$. These data suggest that functional disruption of BBB by $H_2O_2$ was due to the localized loss of occludin in tight junction, but the expression of occludin increased in order to compensate the disrupted function in BBB.

• Journal of the Korean Society of Radiology
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• v.5 no.2
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• pp.93-96
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• 2011

Currently, the development of direct conversion radiation detector using photoconductor materials is progressing in widely. Among of theses photoconductor materials, mercuric iodide compound than amorphous selenium has excellent absorption and sensitivity of high energy radiation. Also, the detection efficiency of signal generated in photoconductor film varies by electric filed and geometric distribution according to top-bottom electrode size. Therefore, in this work, the x-ray detection characteristics are investigated about the size of top electrode in $HgI_2$ photoconductor film. For sample fabrication, to solve the problem that is difficult to make a large area film, we used the spatial paste screen-print method. And the sample thickness is $150{\mu}m$ and an film area size is $3cm{\times}3cm$ on ITO-coated glass substrate. ITO(Indium-Tin-Oxide) electrode was used as top electrode using a magnetron sputtering system and each area is $3cm{\times}3cm$, $2cm{\times}2cm$ and $1cm{\times}1cm$. From experimental measurement, the dark current, sensitivity and SNR of the $HgI_2$ film are obtained from I-V test. From the experimental results, it shows that the sensitivity increases in accordance with the area of the electrode but the SNR is decreased because of the high dark current. Therefore, the optimized size of electrode is importance for the development of photoconductor based x-ray imaging detector.

• Tuberculosis and Respiratory Diseases
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• v.66 no.2
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• pp.110-115
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• 2009

Background: A forceps-biopsy is performed to acquire tissue from patients with an endobronchial carcinoma using a flexible bronchoscope. Recently, a cryo-biopsy has also been used to acquire tissue samples. Cryo-biopsy is the diagnostic application of extreme cold for the local destruction of abnormal living tissue. This technique is safe, with no radiation danger, no risk of electrical accidents, and a little risk of bleeding. This study compared a forceps-biopsy with a cryo-biopsy using a flexible bronchoscope, and examined the chemosensitivity and level of VEGF (vascular endothelial growth factor) in the specimens obtained from the cryo-biopsy. Methods: We present a prospective study of 30 consecutive patients who underwent a forceps-biopsy between January 2007 and October 2007 with a mean age of 62.1 years and a male:female ratio of 5 : 1. A flexible bronchoscope was inserted to the area of the abnormal lesions, and a cryo-probe was then applied through the working channel of the flexible bronchoscope. A temperature of approximately -h80 was delivered to the tumor site for 8 seconds. The cryo-biopsy was performed after destroying the tumor mass. Results: The mean size of the tissue from the forceps-biopsy and cryo-biopsy were 2.0${\pm}$1.2 mm and 6.0${\pm}$3.0 mm. A chemosensitivity test was performed on 5 specimens obtained using cryo-biopsy and the level of VEGF was examined in 2 specimens obtained from a cryo-biopsy. There were no side effects in either group. Conclusion: Cryo-biopsy using a flexible bronchoscope is a safe and effective technique for acquiring tissue samples.