• International Journal of Precision Engineering and Manufacturing-Green Technology
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• v.5 no.5
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• pp.623-630
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• 2018

The renewable energy systems have been in the spotlight as an alternative for environmental issues. Therefore, the governmental policies are being implemented to spread of promote power generation system using renewable energy in various countries around the world. In addition, Korea has also developed a policy called the power trading contract which can profit from electricity produced from renewable power generation system through Korea Electric Power Corporation (KEPCO) and Korea Power Exchange (KPX). As a result, the power trading contracts can trade power after self-consuming in-house by using small-scale renewable power system for residential customers as well as electricity retailers. The power trading contracts applicable as a small-scale power system have a 'Net metering (NM)' and a 'Power Purchase Agreement (PPA)', and these two types of power trading contracts trade surplus power, but payment method of each power trading is different. The microgrid proposed in this paper is based on grid connected microgrid using Photovoltaic (PV) system and Energy Storage System (ESS), that supplied power to residential demand, we evaluate the operation cost of microgrid by power demand in each power trading contracts and propose the appropriate power trading contracts according to electricity demand.

• Journal of muscle and joint health
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• v.16 no.2
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• pp.165-173
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• 2009

Purpose: The aim of this study was to examine the effects of sling exercise on fall risk score, ankle dorsiflexion and balance in community-dwelling elderly women. Method: A 6-week prospective study was conducted to examine the effects of sling exercise. Participants were required to attend their assigned exercise classes three times a week for 6 weeks. Result: After the 6 week study period, PPA fall-risk scores were reduced by 0.90 for the exercise group, which was a significant change (p<.001). Dorsiflexion strength increased significantly (p<.01) by 1.56 kg after the sling exercise. There was a 2.0 cm-increase (p<.05) in FRT and 0.38 second-improvement (p<.01) in TUGT. A 7.88 second-increase in One-leg standing with Eyes Open and a 3.12 second-increase in One-leg standing with Eyes Closed were reported during the 6-week intervention period. Conclusion: The 6-week sling exercise reduced falls risk score significantly (p<=.001) in community-dwelling elderly women by improving fall risk related factors such as reaction time, balance and strength.

• Bulletin of the Korean Chemical Society
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• v.33 no.10
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• pp.3279-3284
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• 2012

Poly(benzimidazole-co-benzoxazole)s (PBI-co-PBO) are synthesized by polycondensation reaction with 3,3'-diaminobenzidine, terephthalic acid and 3,3'-dihydroxybenzidine or 4,6-diaminoresorcinol in polyphosphoric acid (PPA). All polymer membranes are prepared by the direct casting method (in-situ fabrication). The introduction of benzoxazole units (BO units) into a polymer backbone lowers the basic property and $H_3PO_4$ doping level of the copolymer membranes, resulting in the improvement of mechanical strength. The proton conductivity of $H_3PO_4$ doped PBI-co-PBO membranes decrease as a result of adding amounts of BO units. The maximum tensile strength reaches 4.1 MPa with a 10% molar ratio of BO units in the copolymer. As a result, the $H_3PO_4$ doped PBI-co-PBO membranes could be utilized as alternative proton exchange membranes in high temperature polymer electrolyte fuel cells.

• Computers and Concrete
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• v.19 no.1
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• pp.59-68
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• 2017

This study focused on modeling the behavior of the compressive stress using the average strain and ultrasonic test results in concrete. Feed-forward backpropagation artificial neural network (ANN) models were used to compare four types of concrete mixtures with varying water cement ratio (WC), ordinary concrete (ORC) and concrete with short steel fiber-reinforcement (FRC). Sixteen (16) $150mm{\times}150mm{\times}150mm$ concrete cubes were used; each contained eighteen (18) data sets. Ultrasonic test with pitch-catch configuration was conducted at each loading state to record linear and nonlinear test response with multiple step loads. Statistical Spearman's rank correlation was used to reduce the input parameters. Different types of concrete produced similar top five input parameters that had high correlation to compressive stress: average strain (${\varepsilon}$), fundamental harmonic amplitude (A1), $2^{nd}$ harmonic amplitude (A2), $3^{rd}$ harmonic amplitude (A3), and peak to peak amplitude (PPA). Twenty-eight ANN models were trained, validated and tested. A model was chosen for each WC with the highest Pearson correlation coefficient (R) in testing, and the soundness of the behavior for the input parameters in relation to the compressive stress. The ANN model showed increasing WC produced delayed response to stress at initial stages, abruptly responding after 40%. This was due to the presence of more voids for high water cement ratio that activated Contact Acoustic Nonlinearity (CAN) at the latter stage of the loading path. FRC showed slow response to stress than ORC, indicating the resistance of short steel fiber that delayed stress increase against the loading path.

• Korean Journal of Bronchoesophagology
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• v.9 no.1
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• pp.67-74
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• 2003

Larygopharyngeal reflux(LPR) is one form of the Gastroesophageal Reflux Diseases(GERD). It is known to cause various kinds of otolaryngologic symptoms such as hoarseness, globus sensation in throat, chronic throat clearing, and chronic cough, Disease entities diagnosed by otolaryngologists as posterior laryngitis, globus pharyngeus and reflux laryngitis should be suspected as LPR-related diseases. The nizatidine(AXID), as a Histamine H2-receptor antagonist, reduces gastric acid secretion and improves gastric motility function. Objectives : The effect of nizatidine using 150mg b.i.d was evaluated for symptom relief and improvement of laryngoscopic findings in patients with LPR. Materials and Methods : In 30 multicenter, observational trial performed nationalwidely in Korea. 308 patients with LPR symptom were observed to evaluate their symptoms and larygnoscopic findings after 4weeks, 8weeks, 12weeks of treatment with nizatidine. Results : The symptoms of LPR including globus sensation, chronic throat clearing and hoarseness, are reduced significantly after 4 weeks, 8weeks, and 12weeks of treatment(p<0.05). The laryngoscopic findings including diffuse erythema, edema and granulation are improved after nizatidine treatment(p<0.05). and the efficacy of nizatidine on LPR-related sympoms after 4 weeks is 88.6%, and those of after 8 weeks and 12weeks were 92.6%, and 99.1% in ITT(Intent To Treatment) group(p<0.05). And PPA(Per Protocol Analysis)group showed 93.7%, 97.3%, and 99.1% of efficacy after 4, 8, and 12 weeks of nizatidine treatment(p<0.05). Conclusion : These results indicate that in patient with LPR, nizatidine 150mg b.i.d treatment very effectively reduces LPR symptoms and improves laryngoscopic findings as well as reduces gastric acid secretion and improves gastric motility function.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.11
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• pp.787-797
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• 2015

In this paper, a cochlea-inspired artificial filter bank(CAFB) was developed in order to efficiently acquire dynamic response of structure, and it was also evaluated via dynamic response experiments. To sort out signals containing significant modal information from all the dynamic responses of structure, it was made to adopt a band-pass filter optimizing algorithm(BOA) and a peak-picking algorithm (PPA). Optimally designed on the basis of El-centro and Kobe earthquake signals, it was then embedded into the wireless multi-measurement system(WiMMS). In order to evaluate the performance of the developed CAFB, a vibration test was conducted using the El-centro and Kobe earthquake signals, and structural responses of a two-span bridge were obtained and analyzed simultaneously by both a wired measurement system and a CAFB-based WiMMS. The test results showed that the compressed dynamic responses acquired by the CAFB-based WiMMS matched with those of the wired system, and they included significant modal information of the two-span bridge. Therefore this study showed that the developed CAFB could be used as a new, economic, and efficient measurement device for wireless sensor networks(WSNs) based real time structural health monitoring because it could reconstruct the whole dynamic response using the compressed dynamic response with significant modal information.

• International Journal of Highway Engineering
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• v.16 no.4
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• pp.63-74
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• 2014

PURPOSES: This research is to evaluate the mechanical performance of different types of Hot Mix Asphalt (HMA) pavement cells prepared for MN/Road field testing section through an extensive experimental analysis of air voids and simple statistical evaluation tools (i.e. hypothesis test). METHODS: An extensive experimental work was performed to measure air voids in 82 asphalt mixture cores (238 samples in total) obtained from nine different types of road cell located in MN/Road testing field. In order to numerically and quantitatively address the differences in air voids among the different test Cells built in MN/Road, a simple statistical test method (i.e. t-test) with 5% significance was used. RESULTS: Similar trends in air voids content were found among the mixtures including conventional HMA, Reclaimed Asphalt Pavement (RAP) and Warm Mix Asphalt (WMA) combined with taconite aggregate this provides support to the use of RAP and WMA technology in the constructions of asphalt pavement. However, in case of acid modified HMA mixtures, significant differences in air void content were observed between on the wheel path and between wheel path location, which implies negative performances in rutting and thermal cracking resistances. Conclusions : It can be concluded that use of RAP and WMA technology in the construction of conventional asphalt pavement and the use of PPA (Poly Phosphoric Acid) in combinations with SBS (Styrene Butadiene Styrene) in asphalt binder production provide satisfactory performance and, therefore, are highly recommended.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.4
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• pp.1443-1448
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• 2015

To investigate the significance of FOXO3a and Ki67 in human lung adenocarcinomas. Envision immunohistochemical staining and Western blotting were used to examine the protein expression of FOXO3a in 127 cases of human lung adenocarcinoma specimens. The positive rate in lung adenocarcinoma (55.9%) was lower than that in normal tissues (80%). We found that the expression of FOXO3a was closely related with the degree of differentiation, TNM staging, lymph node metastasis and survival. In addition, significant differences in the different pathological types of lung adenocarcinoma cases (P<0.01). The FOXO3a positive rate of the acini as the main type (APA) (86.7%) and the lepidic as the main type (LPA) (82.4%) was higher than the solid as the main type (SPA) (50.0%), the papilla as the main type (PPA) (42.9%) and the micropapilla as the main type (MPA) (9.4%). Moreover, the expression of FOXO3a was negatively related with Ki67 expression. Our results suggested that the expression of FOXO3a is closely correlated with the aggressiveness of lung adenocarcinoma. It was indicated that disregulation of FOXO3a might play key roles in the occurrence and development of lung a denocarcinoma and joint detection of the two markers might play an important role in diagnosing tumors.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.1
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• pp.92-95
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• 2016

In this paper, an UHF-band 1 kW solid-state pulsed power amplifier was designed and implemented for the thermoacoustic imaging(TAI) at 900 MHz. The designed power amplifier has a pulse width of $80{\mu}s$ and a duty cycle of 1 % for short-pulse operation. The overall amplifier was implemented by combining of 16 single-power amplifiers adopting MRFE6P9220HR3 LDMOSFET using wilkinson power dividers. The solid-state pulsed power amplifier shows 25 % drain efficiency with a gain of 76.2 dB when the output power is 60.2 dBm for a -16 dBm input power at center frequency.

• The Journal of the Korea Contents Association
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• v.17 no.5
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• pp.574-590
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• 2017

The purpose of this paper is the provision of a decision-making tool for developers to identify the project risks for under-consideration overseas independent power projects (IPPs), and to analyze the priority and importance weights of the risks through the employment of a fuzzy multi-criteria decision-making (MCDM) approach. A fuzzy MCDM is the calculation method for which the imprecision of each respondent's unique opinion is considered. Through the extensive literature surveys that were conducted for this paper, eight major project finance (PF) risks have been derived credit risk, completion risk, market risk, fuel risk, operating risk, financial risk, environmental risk, and force majeure. The empirical results show that the market risk is the most important risk factor in terms of overseas IPPs, thereby confirming that the long-term power purchase agreement (PPA) guarantee of the host country is one of the most important corresponding factors for the PF.