• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.847-851
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• 2011

Photovoltaic System is increasing install capacity based on environmental-friendly characteristics. It have been actively studied to improve the efficiency. In order to design highly efficient system, it is important to understand the output characteristics of solar panels. The single diode model can represent the physical characteristics of solar panel. But it needs complex process such as mutli-step measurement and numerical analysis to get the exact parameters. In this paper, The method for extracting characteristic parameters of the single diode model based on the I-V characteristic curves in the panel manufacturer's data-sheet is presented. To verify the proposed method, solar cell model constructed in simulink. Simulink model output compared with output graph in datasheet.

• Journal of Conservation Science
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• v.34 no.1
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• pp.31-37
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• 2018

It was estimated that wooden warehouses excavated from Bongseon-ri site in Seocheon were built around the 5th century according to the soil layers and construction methods of earthen structures. In order to identify the exact date, three wooden materials (BSMG 01, 06, and 12) from wooden warehouses were analyzed through radiocarbon dating using wiggle match. The outermost ring of BSMG 01 produced a radiocarbon date (95.4% confidence interval) of AD 431~551, BSMG 06 produced a date of AD 460~570, and BSMG 12 produced dates of either AD 240~430 or AD 490~510. The common age of the three wooden materials was identified as AD 490-510 and coincided with the original estimated archaeological age. Therefore, this study proved the accuracy of radiocarbon dating using wiggle match.

• Environmental Analysis Health and Toxicology
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• v.26
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• pp.12.1-12.7
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• 2011

Objectives: Perchlorate is an emerging contaminant that is found everywhere, including various foods. Perchlorate is known to disturb the production of thyroid hormones and leads to mental disorders in fetuses and infants, as well as metabolic problems in adults. In this study, we attempted to establish an LC-MS/MS method for measuring perchlorate in dairy products and used this developed method to investigate perchlorate levels in Korean milk and yogurt samples. Methods: The developed method of perchlorate analysis requires a shaker and 1% acetic acid/acetonitrile as the extracting solvent. Briefly, the samples were extracted and then centrifuged (4000 rpm, 1hour), and the supernatant was then passed through a $Envi^{TM}$ Carb SPE cartridge that had been prewashed sequentially with 6 mL of acetonitrile and 6 mL of 1% acetic acid in water. The final volume of the sample extract was adjusted to 40 mL with reagent water and the final sample was filtered through a 0.20-${\mu}m$ pore size PTFE (Polytetrafluoroethylene) syringe filter prior to LC-MS/MS. Results: The average levels of perchlorate in milk and yogurt samples were $5.63{\pm}3.49\;{\mu}g/L$ and $3.65{\pm}2.42\;{\mu}g/L$, respectively. The perchlorate levels observed in milk samples in this study were similar to those reported from China, Japan, and the United States. Conclusions: The exposure of Koreans to perchlorate through the consumption of dairy products was calculated based on the results of this study. For all age groups, the calculated exposure to perchlorate was below the reference of dose (0.7 ${\mu}g/kg$-day) proposed by the National Academy of Science, USA, but the perchlorate exposure of children was higher than that of adults. Therefore, further investigation of perchlorate in other food samples is needed to enable a more exact assessment of exposure of children to perchlorate.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.1
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• pp.81-87
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• 2008

This study is about the back analysis to optimize the uncertain parameters of geotechnical properties used in stability analysis of cut and cover tunnel. The Simplex algorithm, Powell algorithm, Rosenbrock algorithm, and Levenberg-Marquardt algorithm are applied for artificial problems of ground excavation. Furthermore, results are compared in the matter of the reliability of optimal solutions with a certain accuracy and the computation speed for evaluations of variables. As shown in results of numerical analysis, all of four algorithms are converged to exact solution satisfying the allowable criteria. And Levenberg-Marquardt's and Rosenbrock's algorithms are identified to be the more efficient methods in the evaluations of functions. After the back analysis for Poisson ratio and Young's modulus for cut and cover tunnel has been performed, design parameters have been correctly estimated and computation time has been improved while the number of measure points is increased.

• Quality Improvement in Health Care
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• v.18 no.1
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• pp.71-78
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• 2012

Background : The objective of this study was to examine the effect of management system for the appropriate prophylactic use of antibiotics in surgical patients at a tertiary hospital from 2007 to 2010. Methods : We collected clinical data of three different surgical procedures(colectomy, heart surgery, hysterectomy) for three months of 2007 and 2010, respectively. The number of total cases was 245(137, 54, 54) in 2007, 240(133, 42, 65) in 2010. We measured the rate of use of inappropriate prophylactic antibiotics, administration within 1 hour prior to the incision and the antibiotics prescription days after surgery. To evaluate the effectiveness of the management system, the results of the two groups(Group1=2007, Group2=2010) were compared by t-test, chi-square test or Fisher's exact test. Result : The rate of Aminoglycoside uses decreased drastically from 11.4% to 0.8%(P<.001). The selection of 3rd/4th Cephalosporin dropped from 11.8% to 5.8%(P=.020). The combination of antibiotics decreased from 27.8% to 11.7%(P<.001). The antibiotic prescription rate on discharge declined from 11.8% to 2.5%(P<.001) and the number of antibiotics prescription days after surgery was shortened from 4.2 days to 2.3 days(P<.001). No significant difference in the rate of administration within 1 hour between two groups was found. Through 3-year management, 5 out of 6 measures were significantly improved(except the administration within 1 hour). The rate of surgical site infection decreased from 2.4% to 1.3%(P=.504). Conclusion : The findings demonstrate that the management system for the prophylactic use of antibiotics in surgical patients was effective in decreasing the rate of surgical site infection during 3 years.

• Journal of Astronomy and Space Sciences
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• v.32 no.1
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• pp.51-62
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• 2015

I investigated a method for drawing the star chart in the planisphere Cheonsang-yeolcha-bunyajido. The outline of the star chart can be constructed by considering the astronomical information given in the planisphere alone and the drawing method described in Xin-Tangshu; further the chart can be completed by using additional information on the shape and linking method of asterisms out of an inherited star chart. The circles of perpetual visibility, the equator, and the circle of perpetual invisibility are concentric, and their common center locates the Tianshu-xing, which was defined to be a pole star in the Han dynasty. The radius of the circle of perpetual visibility was modified in accordance with the latitude of Seoul, whereas the other circles were drawn for the latitude of $35^{\circ}$, which had been the reference latitude in ancient Chinese astronomy. The ecliptic was drawn as an exact circle by parallel transference of the equator circle to fix the location of the equinoxes at the positions recorded in the epitaph of the planisphere. The positions of equinoxes originated from the Han dynasty. The 365 ticks around the boundary of the circle of perpetual invisibility were possibly drawn by segmenting the circumference with an arc length instead of a chord length with the ratio of the circumference of a circle to its diameter as accurate as 3.14 presumed. The 12 equatorial sectors were drawn on the boundary of the star-chart in accordance with the beginning and ending lodge angles given in the epitaph that originated from the Han dynasty. The determinative lines for the 28 lunar lodges were drawn to intersect their determinative stars, but seven determinative stars are deviated. According to the treatises of the Tang dynasty, these anomalies were inherited from charts of the period earlier than the Tang dynasty. Thus, the star chart in Cheonsang-yeolcha-bunyajido preserves the old tradition that had existed before the present Chinese tradition reformed in approximately 700 CE. In conclusion, the star chart in Cheonsang-yeolcha-bunyajido shows the sky of the former Han dynasty with the equator modified to the latitude of Seoul.

• Restorative Dentistry and Endodontics
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• v.40 no.2
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• pp.155-160
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• 2015

Objectives: Achieving adequate anesthesia with inferior alveolar nerve blocks (IANB) is of great importance during dental procedures. The aim of the present study was to assess the success rate of two anesthetic agents (bupivacaine and lidocaine) for IANB when treating teeth with irreversible pulpitis. Materials and Methods: Sixty volunteer male and female patients who required root canal treatment of a mandibular molar due to caries participated in the present study. The inclusion criteria included prolonged pain to thermal stimulus but no spontaneous pain. The patients were randomly allocated to receive either 2% lidocaine with 1:80,000 epinephrine or 0.5% bupivacaine with 1:200,000 epinephrine as an IANB injection. The sensitivity of the teeth to a cold test as well as the amount of pain during access cavity preparation and root canal instrumentation were recorded. Results were statistically analyzed with the Chi-Square and Fischer's exact tests. Results: At the final step, fifty-nine patients were included in the study. The success rate for bupivacaine and lidocaine groups were 20.0% and 24.1%, respectively. There was no significant difference between the two groups at any stage of the treatment procedure. Conclusions: There was no difference in success rates of anesthesia when bupivacaine and lidocaine were used for IANB injections to treat mandibular molar teeth with irreversible pulpitis. Neither agent was able to completely anesthetize the teeth effectively. Therefore, practitioners should be prepared to administer supplemental anesthesia to overcome pain during root canal treatment.

• Restorative Dentistry and Endodontics
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• v.42 no.1
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• pp.19-26
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• 2017

Objectives: Recently, bioceramic sealers like EndoSequence BC Sealer (BC Sealer) have been introduced and are being used in endodontic practice. However, this sealer has limited research related to its retreatability. Hence, the aim of this study was to evaluate the retreatability of two sealers, BC Sealer as compared with AH Plus using micro-computed tomographic (micro-CT) analysis. Materials and Methods: Fifty-six extracted human maxillary incisors were instrumented and randomly divided into 4 groups of 14 teeth: 1A, gutta-percha, AH Plus retreated with chloroform; 1B, gutta-percha, AH Plus retreated without chloroform; 2A, gutta-percha, EndoSequence BC Sealer retreated with chloroform; 2B, gutta-percha, EndoSequence BC Sealer retreated without chloroform. Micro-CT scans were taken before and after obturation and retreatment and analyzed for the volume of residual material. The specimens were longitudinally sectioned and digitized images were taken with the dental operating microscope. Data was analyzed using an ANOVA and a post-hoc Tukey test. Fisher exact tests were performed to analyze the ability to regain patency. Results: There was significantly less residual root canal filling material in the AH Plus groups retreated with chloroform as compared to the others. The BC Sealer samples retreated with chloroform had better results than those retreated without chloroform. Furthermore, patency could be re-established in only 14% of teeth in the BC Sealer without chloroform group. Conclusion: The results of this study demonstrate that the BC Sealer group had significantly more residual filling material than the AH Plus group regardless of whether or not both sealers were retreated with chloroform.

• Journal of Korean Society of Steel Construction
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• v.10 no.1 s.34
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• pp.73-83
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• 1998

Considering dynamic behaviors according to initial tension forces, geometric nonlinearity and the effect of higher eigen modes to participate in dynamic behaviors increase as initial tension forces decrease, and from phase portrait we can realize that period attractors are produced in many area with complexity. If initial tension forxes increase, difference between linear and nonlinear solutions will decrease and the first eigen mode dominate the dynamic behaviors and observing phase portrait, period attractors appear in certain area regularly. These results may offer meaningful informations to nonlinear dynamic analysis using modal reduction methods such as Lanczos modal analysis. And actually nonlinear dynamic analysis needs very large computational efforts. So, if we determine the number of eigen modes to take part in modal analysis corresponding to initial tension forces we will get more accurate data close to exact nonlinear dynamic solutions.

• The Journal of Internal Korean Medicine
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• v.27 no.3
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• pp.698-705
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• 2006

Objectives : This study was designed to investigate the effect of PC6 and SP4 on autonomic nerve system in healthy adults. Methods : 22 healthy adults were recruited and randomized into the study group or control group. The study group (real acupuncture group) was acupuncturcd on PC6 and SP4. The control group (sham acupuncture group) was acupunctured superficially near PC6 and SP4 but not the exact points. The subjects rested for 10 minutes, and were then acupunctured. After 15 minutes, acupuncture needles were removed and the subjects rested for another 15 minutes. Heart rate variability(HRV) was continuously measured during the study period by FM-150 (digital Holter ECG recorder). Results : In the real acupuncture group. LF(low frequency) significantly decreased during the acupuncture period(p<0.05). LF/HF ratio also had a significant decrease during acupuncture period and the decrease was maintained during the post-treatment period as compared with the pre-treatment period. In the sham acupuncture group. LF significantly increased during the acupuncture period but LF/HF ratio had no significant changes. Conclusions : The results suggest that acupuncture on PC6 and SP4 can increase parasympathetic activity and balance autonomic nervous system.