• The Mathematical Education
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• v.53 no.1
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• pp.41-55
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• 2014

In recent years, there has been increasing interest in the pedagogical importance of counter-examples that contradict statements about mathematics education research and the curriculum revision process for high school mathematics courses. Using a literature research method, this study analyzed views about counter-examples according to a method of approach to statements and the classification of counter-examples and their criteria. The study also described the learnability of the content of counter-examples presented in Korean secondary school mathematics textbooks. The results showed that generating many counter-examples enables learners to understand mathematical concepts exactly, construct links between mathematical contents, and have flexible thoughts about mathematical objects. Considering the learnability of counter-examples, the contents of counter-examples in school mathematics textbooks are needed for mathematics teachers and students to generate numerous counter-examples and verify the justification of generating counter-examples in various manners.

• Transactions on Electrical and Electronic Materials
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• v.6 no.4
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• pp.140-143
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• 2005

Carbon Nanotube(CNTs) counter electrode is a promising alternative to Platinum counter electrode for dye sensitized solar cells (DSSCs). In this study, CNT counter electrodes having different visible light transmittance were prepared on fluorine-doped tin oxide (FTO) glass surface by spray coating method. Microstructural images show that there are CNT-tangled region coated on FTO glass counter electrodes. Using such CNT counter electrodes and screen printed $TiO_2$ electrodes, DSSCs were assembled and its I-V characteristics have been studied and compared. Light energy conversion efficiency of DSSCs increased with decreasing in light transmittance of CNT counter electrode. Efficiency of DSSCs having CNT counter electrode is compatible to that of Pt counter electrode.

• Korean Journal of Clinical Pharmacy
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• v.28 no.3
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• pp.230-237
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• 2018

Objective: To compare adverse event reporting patterns between ethical-the-counter and over-the-counter drugs from community pharmacies and outpatient settings. Methods: We conducted a descriptive study using the adverse event reporting database, wherein data were collected from the regional pharmacovigilance centers of the Korean Pharmaceutical Association between January 1, 2016 and December 31, 2016. The reported drugs were classified into either ethical-the-counter or over-the-counter drugs, and we compared the distribution of patient age and gender, frequent adverse events and medications, serious adverse events, and causality assessment results, where causality assessments were performed according to the World Health Organization-The Uppsala Monitoring Centre's system. Results: We included 17,570 reports (75,451 drug-adverse event pairs). Ethical-the-counter and over-the-counter drugs accounted for 81.4% and 18.6% of the total adverse event reports, respectively. The use of over-the-counter drugs was higher in females and patients aged <18 years, whereas the use of ethical-the-counter drugs was higher in those aged >65 years. Alimentary tract and metabolism drugs, and respiratory system drugs were the most frequent ethical-the-counter and over-the-counter drugs, respectively. From causality assessment results, "possible" (75.4%) was the most commonly assigned category for ethical-the-counter drugs, while "possible" (44.0%) and "unlikely" (47.7%) were the most common categories for over-the-counter drugs. The distribution of serious adverse events were similar for both ethical-the-counter and over-the-counter drugs. Conclusion: Differences were observed in age, gender, reported medications, and symptoms for both ethical-the-counter and over-the-counter drugs. Further pharmacovigilance activities considering the adverse event characteristics of over-the-counter drugs, which are comparable to ethical-the-counter drugs, should be performed.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.428-430
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• 2008

Dye-sensitized solar cell has many internal resistant components such as Pt counter electrode, $TiO_2$/dye/electrolyte, charge diffusion, sheet resistance of TCO. Among these, the resistance about the counter electrode can be reduced by increasing the roughness factor of Pt counter electrode. This causes the increase of fill factor and improvement of efficiency. And the amount of light reflection on the counter electrode also increases as the roughness factor goes up. In our experiment, we suggest a new deposition structure of Pt thin film that is a stepped-type structure. The more step lines are in the counter electrode, the more roughness factor is. As a result, we get the improvement of fill factor and efficiency by controlling the roughness factor of counter electrode.

• Journal for History of Mathematics
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• v.26 no.5_6
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• pp.401-416
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• 2013

There has been increasing interest in recent years in the pedagogical importance of counter-examples that focuses on pedagogical perspectives. But there is no research that undergraduate students' generating counter-examples and proposing the true statements. This study analyze 6 undergraduate students' response to interview tasks and the process of their generating counter-examples and proposing true statements. The results of interviews are that the more undergraduate students generate various counter-examples, the more valid they propose true statements. If undergraduate students have invalid understanding of logical implication and generate only one counter-example, they would not propose true statements that modify the given statement, preserving the antecedent. In pre-service teacher's education and school mathematics class, we need to develop materials and textbooks about counter-examples and false statements.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1712-1714
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• 1997

This paper deals with the surge counter drived by lightning and switching currents. In order to install the effective surge protective devices, it is important to find the parameters of incident surges. In this paper, for the purpose of protecting the electronic circuits and counting the occuring frequency, the current driving type surge counter is designed and fabricated. The surge counter consists of surge protective divices, current detector, metal oxide varistor(MOV), rectifier, capacitor, and electromagnetic counter. This surge counter is able to count the occuring frequency of surges and to clamp lightning surge current. To evaluate the performance of the surge counter, impulse voltage and current were applied at the surge counter by the surge generator. As a result, applied surges were exactly counted and clamped.

• Journal of Biosystems Engineering
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• v.5 no.2
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• pp.1-14
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• 1980

This study was carried out to investigate the effects of the counter-pressure setting and the roller speed of a rice whitening machine on the head rice recovery. milling capacity and milling efficiency, and also to find out the optimum operational conditions of the machine. The radial pressure inside the whitening chamber and the outlet axial pressure were measured to study their relationships with the head rice recovery, milling capacity and milling efficiency. The results of the study are summarized as follows. (1) The most important factor in rice whitening was the counter-pressure setting. It significantly affected the head rice recovery. (2) The roller speed significant affected the milling capacity and milling efficiency , but it did not affected the head rice recovery. (3) Both the radial pressure and the outlet axial pressure were affected by the counter-pressure setting but not by the roller speed. Both of them increased almost linearly with the counter-pressure setting. There was a significant correlation between the radial pressure and the outlet axial pressure. (4) The flow rate through the whitening chamber when the feed gate was fully opened increased with the roller speed, but it was not affected by the counter-pressure setting. (5) The head rice recovery decreased as the counter-pressure setting increased , but it was not affected by the roller speed. The reason could be explained by the fact that the radical pressure increased only with the counter-pressure setting. (6) The milling capacity increased with the counter-pressure setting and linearly with the roller speed. The milling efficiency generally increased with both the counter-pressure setting and the roller speed. However, the effect of roller speed was negligible at the higher counter-pressure setting. The temperature rise inside the whitening chamber was moderate with the mean of 11.3℃ (range 5.6-18.3℃) even though it increased slightly with the roller speed. Considering the head rice recovery and milling efficiency, the optimum operational conditions of the machine appeared to be the counter-pressure setting of 67g/㎠ and the roller speed of 1,050rpm. Neglecting the small difference in the head rice recovery , the greater milling capacity could be obtained at the counter-pressure setting of 85g/㎠ with the roller speed of 850-1050rpm.

• Applied Chemistry for Engineering
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• v.10 no.4
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• pp.608-614
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• 1999

The counter-diffusion of aromatic compounds such as coronene and tetra-phenylporphine by injection of acetone or tetra-phenylporphine solution was studied on aluminas and silica-alumina used widely as catalysts support. The counter-diffusivity was determined from simulation results by using the counter-diffusion model employing ideal adsorbed solution theory. The counter-diffusivities of aromatic compounds in the catalyst supports were ranged in ${\sim}10^{-15}m^2/sec$ in the desorption process by the injection of excess acetone. In the counter-diffusion process with tetra-phenylporphine solution which have similar concentration with adsorption solution, the counter-diffusivities of coronene were also ${\sim}10^{-15}m^2/sec$, and that of tetra-phenylporphine into pores were determined as ${\sim}10^{-11}m^2/sec$. The counter-diffusivities of coronene desobed from the adsorbent were significantly redyced in comparison with the effective diffusivities when there is counter-diffusion flux. The values mainly depended on the existence of counter-diffusion flux, but not concerned with the species and amount of desorbates.

• The Korean Society of Law and Medicine
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• v.12 no.2
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• pp.265-291
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• 2011

Changes in a drug's availability from prescription only to over-the-counter (OTC) status is of concern to physicians from both public health and individual patient perspectives. Government has generally been supportive of changes in medications from prescription(Rx) to over-the-counter (OTC) status in Korea, however, recognizing that there are both benefits and risks to any health care intervention, health care professionals are conservative in implementing changes to either the process or structure of health care. Changes in status of a drug from Rx to OTC can represent a change in both structure and process. Cost and convenience seem to be major factors in determining whether, given the choice, patients purchase a medicine over the counter or obtain it on prescription. With current arrangements, exemption from prescription charges provides an incentive to continue to obtain products on NHS prescription even when they are available over the counter. There is therefore no simple relation between the availability of over the counter medicines and the level of prescribing of deregulated products. The appropriate use of over the counter medicines-particularly those that have only recently been deregulated-places a burden of care on community pharmacists and calls for closer working relationships with general practitioners. In particular, systems for referral and for recording details of both prescribed and over the counter medicines need to be developed, and a direct route needs to be established for community pharmacists to report adverse drug reactions to over the counter products. Reclassification of prescription medicines-by making them available through pharmacies without a prescription-provides the opportunity for consumers to purchase a wider range of medicinal products without making a demand on NHS resources. There is, however, no simple relation between availability of over the counter medicines and demand for NHS prescriptions. In the late 1980s the UK government fuelled the over the counter market by making it easier to reclassify certain medicines from prescription only status to allow over the counter sale in pharmacies. To explore the influence of deregulation of medicines on NHS prescribing, this article presents analyses of consumer behaviour in using medicines and prescribers' attitudes to over the counter medication and collates findings from research. Policy makers should be aware that patients' expectations in relation to OTC medicines may be in conflict with evidence-based practice.

• Journal of the Korean Geosynthetics Society
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• v.14 no.1
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• pp.51-58
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• 2015

The counter weight filling is a technology to accumulate soils on the side of berm with a proper width and height for improving the stability of the embankment. This study aims to assess a feasibility of the counter weight filling in the construction of pavement roads for recovery of shear failure during the construction. An effective counter weight filling section was suggested using the numerical analysis. The results showed that the effective counter weight filling section is two-fold (x2) higher than the ratio of width in counter weight filling : embankment height and one third (1/3) to the ratio of height in counter weight filling : embankment height. Also a range of effective trench crossing the counter weight filling required when a trench crossing counter weight filling is installed was suggested by supplying a proper distance between the counter weight filling section and cross-sectional trench.