• School Mathematics
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• v.11 no.4
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• pp.643-664
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• 2009

This study was aimed to understand the problems that students experience during the self--directed study of a mathematics digital textbook and to find the implications for the design of digital textbook. For this study, we analyzed the process of self-directed learning on 'division of fractions with same denominator' using digital textbook by eight 6th graders. Students asked to use think aloud method while they study the unit. Their learning process was videotaped and analyzed by researchers after the experiment. After the self-directed learning, students filled out a test items and participated interview with a researcher. The result showed that students experienced several misconceptions and errors while using a digital textbook. The types of misconceptions and errors were cataegorized as "misconceptions and errors caused by a mathematics textbook" and "misconceptions and errors caused by a digital textbook". Especially, students showed several important misconceptions and errors because of the design factors. This implies we need to consider the causes of misconceptions for the design of a digital textbook.

• Journal of Korean Society for Atmospheric Environment
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• v.8 no.4
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• pp.247-256
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• 1992

Airborne suspended particulates were collected at Shinchon by a high volume cascade impactor from Sep. 1990 to Aug. 1991. Organic matter was extracted from particulates and fractionated by liquid-liquid extraction and thin layer chromatography. Substances in the PAHs and nitroarenes'subfraction of neutral fraction were determined by capillary gas chromatography. Based on unit risk estimates by multi-stage model of benzo[a]pyrene and the results of exposure estimates, cancer risk was assessed. The annual average concentration of total suspended particulates was 201.77g/$m^3$. The percentage of fine particulates was 57.40. The concentration of total suspended particulates showed seasonal variations and was high in winter and spring. The average concentration of extractable organic matter was 8.12g/$m^3$. In all, 21 PAHs were identified and quantified. The annual concentration of fluoranthene was 2.38ng/$m^3$, and that was the highest value of all PAHs. A carcinogenic compound, benzo[a]pyrene, was at a concentration of 1.84ng/$m^3$. All the 10 nitroarenes were also identified and quantified. The major nitroarene in the Shinchon area was 2,7-dinitrofluorene. The annual concentration of 1-nitropyrene was 1.56ng/$m^3$. Concentrations of PAHs and nitroarenes were high in winter and low in summer. The life time excess risk estimates of benzo[a]pyrene was calculated as 0.96 persons/a million population in this experiment. In the rank of relative potenties, carcinogenic effects of the other PAHs were calculated as 0.004-0.108 persons/a million population.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.1
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• pp.91-99
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• 2007

It is well-known that the presence of NOM (natural organic matter) in water has a negative effect on removing taste and odor compounds by activated carbon adsorption. Therefore, various means such as enhanced coagulation are applied to reduce the NOM. The presence of taste & odor compounds in drinking water even parts per trillion, is enough to generate customer dissatisfaction. Therefore, the aim of this study was to evaluate carbon usage rate (CUR) for conventional coagulation (CC) and enhanced coagulation (EC) in order to improve the efficiency of adsorption of taste and odor compounds. Also, Effect of CC and EC on molecular weight fraction and the early stage breakthrough of 2-MIB and Geosmin are evaluated. When the enhanced coagulation was adapted for pretreatment for activated carbon adsorption the operation period could be prolonged by 3.5~4 times. CUR for CC was about 2 times greater than CUR for EC and this means that EC has more adsorption capacity than CC. To analyze effect of EC and CC on breakthrough of 2-MIB quantitatively, adsorbed NOM mass was calculated based on unit mass of activated carbon. In the early stage breakthrough of 2-MIB, total adsorbed NOM was 23.72mg/g for CC and 34.56mg/g for EC. Therefore, it is shown that the early breakthrough term of 2-MIB and Geosmin was improved due to increased adsorbability. The low-molecular-weight NOM (500~2000Da) compounds were the most competitive, participating in direct competition with 2-MIB for adsorption site.

• Food Science of Animal Resources
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• v.33 no.4
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• pp.501-507
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• 2013

Lysozyme was trapped from $2{\times}$ diluted egg white using Amberlite FPC 3500 ion exchange resin (1 g/10mL of egg white). The lysozyme bound to the resin was recovered using 0.1 N glycine-NaOH buffers, pH 9.0, containing 0.5 M NaCl. After separating lysozyme, the pH of the egg white solution was adjusted to 4.75 and centrifuged to remove interfering proteins. The supernatant was collected, added with 2.5% citric acid and 5.0% ammonium sulfate combination to precipitate egg white proteins, except for ovalbumin. After centrifugation, both supernatant (S1) and precipitant were collected. The precipitant was dissolved with 4 volumes of distilled water, and then 2.0% ammonium sulfate and 1.5% citric acid combinations added, stirred overnight in a cold room, and centrifuged. The resulting supernatant (S2) was pooled with the first supernatant (S1), desalted using an ultrafiltration unit, heat-treated at $70^{\circ}C$ for 15 min, and then centrifuged. The supernatant was collected as an ovalbumin fraction and lyophilized. The separated proteins were confirmed using Western blotting. The yield of lysozyme and ovalbumin was > 88.9% and > 97.7%, respectively, and the purity of lysozyme and ovalbumin was > 97% and 87%, respectively. The results indicated that the protocol was simple, and separated lysozyme and ovalbumin effectively.

• Composites Research
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• v.33 no.3
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• pp.169-175
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• 2020

The compression and tension test were performed to evaluate the stiffnesses of the conical composite lattice structures and results of test were compared with finite element analysis results. Because of difficulty to perform simple tension and compression test due to conical shape, suitable specimens and jig for test were made. Subelements extracted from the structure were prepared for compression test. Compression test of subelement was performed and compressive strains in fiber direction were measured. Compressive stiffness of the helical rib was verified by finite element analysis results. For stiffness of hoop rib, hoop ring specimens were extracted from the structure. Tension test of hoop ring specimen was performed to apply bending deformation to hoop rib. Stiffness of hoop rib was verified by finite element model considering various fiber volume fraction in thickness direction.

• Journal of Ginseng Research
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• v.8 no.2
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• pp.153-166
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• 1984

The anticancer activities of petroleum ether extract of Panax ginseng root(crude GX) and its partially purified fraction from silicic acid column chromatography (7:3 GX) were studied with Sarcoma 180(S-180) or Walker carcinosarcoma 256 (Walker 256) in vivo and with L1210 leukemic lympocyte in vitro. Potential cytotoxic activities of the crude GX and against L1210 cells were compared with those of 5-Fluorouracil (5-FU) and saponin derivatives (Panax-diol, Panax-triol, Diol saponin, Triol saponin) in vitro. In order to observe the physiological effects of the crude GX and 7:3 GX on the animals with cancer, hemoglobin(Hb), red blood cell(R.B.C) and white blood cell after treatment with each GX in comparison with corresponding control groups, respectively. The anticancer effects of the crude GX and 7:3 GX were estimated by measuring the survival time of S-180 bearing mice after treatment with them. The experimental results obtained are summarized as follows; 1. The one unit of cytotoxic activity against L1210 cells was equivalent to 2.54$\mu\textrm{g}$ and 0.88$\mu\textrm{g}$of the crude GX and 7:3 GX per ml of culture medium, respectively. 2. The cytotoxic activities of Panax-diol, Panax=triol, Diol saponin and triol saponin against L1210 cells were not detected. 3. The anticancer activities of 5-FU against L1210, S-180 and Walker 256 were very effective in vivo and vitro tests. 4. The significantly increased W.B.C values of mice after inoculation with S-180 cells were reduced to normal range by the crude GX treatment. 5. The significantly decreased Hb values of rats after inoculation with Walker 256 were recovered to normal range by oral administration of the crude GX. 6. The survival times of mice inoculated with S-180 cells were extended about 1.5 to 2 times by the 7:3 GX treatment compared with their control group.

• Korean Journal of Food Science and Technology
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• v.10 no.1
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• pp.57-62
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• 1978

The morphology and chemical properties of bracken (Pteridium aquilinum) root starch were investigated. The starch granules were mainly sphere and cocoon with the diameter of $5-12\mu$. Polarized micrograph indicated that the starch granule had a hilum at the center of granule, showing a crossed-birefringence. X-ray diffraction pattern demonstrated that the granules showed B-type. The density of the starch was 1.49 and the amylose content was 22%. The ferricyanide number and alkali number were 0.292 and 11.03, respectively. Proximate analysis showed that the starch contained 0.52% lipid, 0.63% ash and 150ppm phosphorus of which over 80% were found in the amylopectin fraction. The iodine affinity and molecular weight of amylose were 16.1 and 83,000 respectively. The degree of branching and glucose units per segment of amylopectin were 3.7% and 27, respectively.

• The Mathematical Education
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• v.40 no.2
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• pp.195-215
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• 2001

The purpose of this paper is to present a specific set of home teaching methods in hopes to prevent slow learner of the elementary mathematics. This paper deals with the number and operations, one of five topics in the elementary mathematics A survey of two hundred elementary school teachers was made to see the teacher's opinions of the role of home studying and to concretize the contents of the research topics. There were asked which is the most essential contents for the concrete loaming and which is the most difficult monad that might cause slow leaner. And those were found to be; counting, and arithmetic operations(addition and subtraction) of one or two-digit numbers and multiplication and their concepts representations and operations(addition and subtraction) of fractions. The home teaching methods are based on the situated learning about problem solving in real life situations and on the active teaming which induces children's participation in the process of teaching and learning. Those activities in teaching each contents are designed to deal with real objects and situations. Most teaching methods are presented in the order of school curriculum. To teach the concepts of numbers and the place value, useful activities using manipulative materials (Base ten blocks, Unifix, etc.) or real objects are also proposed. Natural number's operations such as addition, subtraction and multiplication are subdivided into small steps depending upon current curriculum, then for understanding of operational meaning and generalization, games and activities related to the calculation of changes are suggested. For fractions, this paper suggest 10 learning steps, say equivalent partition, fractional pattern, fractional size, relationship between the mixed fractions and the improper fraction, identifying fractions on the number line, 1 as a unit, discrete view point of fractions, comparison of fractional sizes, addition and subtraction, quantitative concepts. This research basically centers on the informal activities of kids under the real-life situation because such experiences are believed to be useful to prevent slow learner. All activities and learnings in this paper assume children's active participation and we believe that such active and informal learning would be more effective for learning transfer and generalization.

• Journal of Yeungnam Medical Science
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• v.35 no.1
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• pp.84-88
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• 2018

A 33-year-old woman visited the emergency department presenting with fever and dyspnea. She was pregnant with gestational age of 31 weeks and 6 days. She had dysuria for 7 days, and fever and dyspnea for 1 day. The vital signs were as follows: blood pressure 110/70 mmHg, heart rate 118 beats/minute, respiratory rate 28/minute, body temperature $38.7^{\circ}C$, and oxygen saturation by pulse oximetry 84% during inhalation of 5 liters of oxygen by nasal prongs. Crackles were heard over both lung fields. There were no signs of uterine contractions. Chest X-ray and chest computed tomography scan showed multiple consolidations and air bronchograms in both lungs. According to urinalysis, there was pyuria and microscopic hematuria. She was diagnosed with community-acquired pneumonia and urinary tract infection (UTI) that progressed to severe sepsis and acute respiratory failure. We found extended-spectrum beta-lactamase producing Escherichia coli in the blood culture and methicillin-resistant Staphylococcus aureus in the sputum culture. The patient was transferred to the intensive care unit with administration of antibiotics and supplementation of high-flow oxygen. On hospital day 2, hypoxemia was aggravated. She underwent endotracheal intubation and mechanical ventilation. After 3 hours, fetal distress was suspected. Under 100% fraction of inspired oxygen, her oxygen partial pressure was 87 mmHg in the arterial blood. She developed acute kidney injury and thrombocytopenia. We diagnosed her with multi-organ failure due to severe sepsis. After an emergent cesarean section, pneumonia, UTI, and other organ failures gradually recovered. The patient and baby were discharged soon thereafter.

• Cross-Cultural Studies
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• v.38
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• pp.433-459
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• 2015

This paper aims at a better understanding of the concept of korean separable syntactic atom, of which inner parts is separable in syntax, and at examining whether or not this concept can apply to derivatives, functional complex constructions, idiomatic expressions in korean. I defined a syntactic atom as a minimum unit which is drawn directly from lexicon and then is applied to syntactic rules. And I insist that so-called 'lexical island constraint' has some problems and that the syntactic rules can be applied to inner parts of syntactic atom, if the syntactic rules is irrelevant to new syntactic atom formation. The greater part of derivatives is non-separable syntactic atoms. But the likes of '반짝거리다', '죄송스럽다', '칭얼대다' are the separable syntactic atoms. The degree of separability of them is different in the insertion of korean particles or negative adverbs and the omission of root of sytactic atom. The derivatives of 'X-적', of which roots is regular nominal roots, permit the syntactic link between roots and the syntactic combination of the root and its argument. These kinds of derivatives is separable syntactic atoms. Also the derivatives of 'bracket paradox' and 'X-답-' derivatives is separable syntactic atoms. All functional complex constructions are not separable syntactic atoms. According to the degree of grammaticalization, inner parts of some are separable, some is non-separable. Separable functional complex constructions only permit the switching of endings or Josas but not application of other syntactic rules. All idiomatic expressions which are composed of two or more syntactic atoms are separable syntactic atoms. Some of them have so strong separability to allow the insertion of syntactic atom, adverb or adnominal modification and the noun in idiomatic expression to become the head of the relative clause. And some idiomatic expressions which have weak separability only permit interrogative's substitution or form change in fraction of idiomatic expressions.