• Journal of Educational Research in Mathematics
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• v.24 no.2
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• pp.181-204
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• 2014

This research aims to have some implications for revision of curriculum and textbooks by analysing connections between the 2009 revised national curriculum and its textbooks in elementary school mathematics. The results of analyses for 3~4 grades can be summarized in four aspects: Firstly, we noticed that the reconstructed achievement criteria were reflected properly in the textbooks except for use of calculators in 'Numbers and Operations'. Secondly, the analysis of connections between unit objectives of textbooks and the reconstructed achievement criteria suggests that 10 units must receive attention. Especially, the range of decimal numbers for adding and subtracting needs to be corrected. Thirdly, mathematical terms and symbols excluding 'unit fraction' were found in the textbooks. Finally, mathematical processes were also fully reflected in the textbooks. However 'simplifying' as a strategy for problem solving was only missing. This result shows good or poor connections between the curriculum and its textbooks, therefore it is expected to be used effectively to revise the national curriculum for mathematics and its textbooks.

• Korean Journal of Food Science and Technology
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• v.33 no.1
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• pp.117-121
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• 2001

White kidney bean, Phaseolus vulgaris, contains proteinaceous inhibitors of ${\alpha}-amylase$. Two inhibitors have been purified by conventional protein fractionation methods such as ethanol precipitation, ammonium sulfate fractionation, DEAE-Sephadex ion exchange chromatography and Sephadex G-100 gel chromatography. The inhibitors were purified as I-1 and I-2 based on their elution order from the DEAE-Sephadex column. The overall purification ratio were about 15.0 and 14.8 for I-1 and I-2, respectively. The molecular weights of purified ${\alpha}-amylase$ inhibitors were 50,000 and 45,000 determined by Sephadex G-100 gel filtration and SDS-polyacrylamide gel electrophoresis. They contain $17.6{\sim}17%$ of carbohydrate, $70{\sim}80%$ of protein. The carbohydrates were composed of glucose : xylose : mannose : N-acetylglucosamine (5 : 3 : 50 : 42).

• Tuberculosis and Respiratory Diseases
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• v.78 no.4
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• pp.336-340
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• 2015

Background: Potentially harmful unplanned extubation (UE) may occur in patients on mechanical ventilation (MV) in an intensive care unit (ICU) setting. This study aimed to evaluate the clinical characteristics of UE and its impact on clinical outcomes in patients with MV in a medical ICU (MICU). Methods: We retrospectively evaluated MICU data prospectively collected between December 2011 and May 2014. Results: A total of 468 patients were admitted to the MICU, of whom 450 were on MV. Of the patients on MV, 30 (6.7%) experienced UE; 13 (43.3%) required reintubation after UE, whereas 17 (56.7%) did not require reintubation. Patients who required reintubation had a significantly longer MV duration and ICU stay than did those not requiring reintubation ($19.4{\pm}15.1days$ vs. $5.9{\pm}5.9days$ days and $18.1{\pm}14.2days$ vs. $7.1{\pm}6.5days$, respectively; p<0.05). In addition, mortality rate was significantly higher among patients requiring reintubation than among those not requiring reintubation (54.5% vs. 5.9%; p=0.007). These two groups of patients exhibited no significant differences, within 2 hours after UE, in the fraction of inspired oxygen, blood pressure, heart rate, respiratory rate, and pH. Conclusion: Although reintubation may not always be required in patients with UE, it is associated with a poor outcome after UE.

• Journal of Ginseng Research
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• v.17 no.1
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• pp.52-60
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• 1993

Panax ginseng has been extensively used in the traditional oriental medicine as a restorative, tonic and Prophylactic agent. Recently, several reports regarding to anticancer effects of Panax ginseng has accumulated. These studies emphasized the fact that the anticancer activities might be due to a glycoside group called ginsenoside or pan.u saponin which has a water soluble characteristic. However, the authors and collaborates demonstrated that a highly lipid soluble component in extract of Panax ginseng roots contains a considerable cytotoxic activities against marine leukemic cells (L1210, P388) and human censer cells (HRT-18, HT-29, HCT48). This study was devised to observe the cytotoxic activities of Petroleum-ether extract of Panax giuseng roots (crude GBD and its Partially Purified fraction from silicic acid column chromatography (7 : 3 GX) against sarcoma-180 (5-180) and Walker carcinosar- coma 256 (Walker 256) in vivo, and murine leukemic Lymphocytes (L1210) and human rectal cancer cells (HRT-18) and human colon cancer cells (HT-29 and HCT48) in vitro. Each cell-line was cultured in medium containing serial concentration of the crude GX or 7 : 3 GX in vitro. A highly lipid soluble compound in the extract of Panax ginseng root was cytocidal to murine leukemic cells and human colon and rectal cancer cells in vitro. In the meantime, ginseng saponin derivatives did not have cytotoxic effects at its corresponding concentration. The growth rates of the cancer cells in medium containing ginseng extracts were inhibited gradually to a significant degree roughly in proportion to the increase of the extract concentration. The cytotoxic activity of 7 : 3 GX was about 3 times more potent than that of crude GX, one unit of cytotoxic activity against L1210 cells being equivalent to 2.54 Ug and 058 Ug for the crude GX and 7 : 3 GX, respectively. The Ri value of the active compound on silica- gel thin layer chromatography with petroleum-ether/ethyl ether/acetic acid mixture (90 : 10 : 1, v/v/v) as a developing so lvent was 053. While, the Panaxydol and Panaxynol as active compounds were purified from Petroleum-ether extract of Panax ginseng root by Drs. Ahn and Kim, and author found out that the one unit of cytotoxic activity of the Panaxydol and Panaxynol against L1210 cells being equivalent to 056 Ug and 0.3918 respectively. 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. The significantly decreased hemoglobin values of rats after inoculation with Walker 256 were recovered to normal range by oral administration of the crude Gt The synthetic levels of protein, DNA and RNA in human colon and rectal cancer cells were significantly diminished by treatment with the crude GX, which can explain a part of the origin of its anticancer activity.

• Journal of Elementary Mathematics Education in Korea
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• v.12 no.1
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• pp.79-100
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• 2008

Freudenthal has advocated the reinvention method. In that method, the pupils start with a meaningful context, not ready-made concepts, and invent informative method through which he could arrive at the formative concepts progressively. In many face the reinvention method is contrary to the traditional method. In traditional method, which was named as 'concretization method' by Freudenthal, the pupils start with ready-made concepts, and applicate this concepts to various instances through which he could arrive at the understanding progressively. Through analysis, it turns out that Korea's seventh elementary mathematics textbook is based on concretization method. In this thesis, first of all, I will reconstruct probability unit of seventh elementary textbook according to Freudenthal's reinvention method. Next, I will perform teaching experiment which is ruled by new lesson design. Lastly, I analysed the effects of teaching experiment. Through this study, I obtained the following results and suggestions. First, the reinvention method is effective on the teaching of probability concept and algorithm. Second, in comparison with current textbook strand, my strand which made probability concept go ahead and combinatorics concept let behind is not deficiency. Third, tree diagram is effective matrix which contribute to formalization of combinatorics calculation. Lastly, except for fraction, diverse representation of probability, for example percentage or informal ratio expression must be introduced in teaching process.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.6
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• pp.483-491
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• 2014

In this study, a thermodynamic analysis was carried out for a combined power generation system using a low-temperature heat source in the form of sensitive energy and liquefied natural gas cold energy. An ammonia-water mixture, which is a zeotropic mixture, was used as the working fluid, and systems with and without a regenerator were comparatively analyzed. The effects of the mass fraction of ammonia and the condensation temperature of the working fluid on the system variables, including the net work production, exergy destruction, and thermal and exergy efficiencies, are analyzed and discussed. The results show that the performance characteristics of the system varied sensitively with the ammonia concentration or condensation temperature of the working fluid. The system without regeneration was found to be better in relation to the net work per unit mass of the source fluid, whereas the system with regeneration was better in relation to the thermal or exergy efficiency.

• School Mathematics
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• v.14 no.1
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• pp.29-43
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• 2012

This paper investigated the conceptual schemes in which four children constructed a strategy representing the situation as a figure and partitioning it related to the work which they quantify the result of partitioning to various types of fractions when an equal sharing situation was given to them in contextual or an abstract symbolic form of division. Also, the paper researched how the relationship of factors and multiples between the numerator and denominator, or between the divisor and dividend affected the construction. The children's partitioning strategies were developed such as: repeated halving stage ${\rightarrow}$ consuming all quantity stage ${\rightarrow}$ whole number objects leftover stage ${\rightarrow}$ singleton object analysis/multiple objects analysis ${\rightarrow}$ direct mapping stage. When children connected the singleton object analysis with multiple object analysis, they finally became able to conceptualize division as fractions and fractions as division.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.3
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• pp.293-299
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• 2011

To study the flow characteristics of water-based $Al_2O_3$ nanofluids according to the shape of the nanoparticles, we measure the pressure drop in a fully developed laminar flow regime. Water-based $Al_2O_3$ nanofluids of 0.3 Vol.% with sphere-, rod-, platelet-, and brick-shaped nanoparticles are manufactured by the two-step method. Zeta potential is measured to examine the suspension and dispersion characteristics, and TEM image is considered to confirm the shape characteristics of the nanoparticles. The experimental results show that the pressure drop of $Al_2O_3$ nanofluids depends on the shape of the nanoparticles although the nanofluids has same volume fraction of nanoparticles. This is explained by the surface area per unit mass of the nanoparticles and the size of the nanoparticles suspended in the base fluids.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.479-482
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• 2008

Since late of 2000, KIER has developed a novel pyrolysis process for production of fuel oils from polymer wastes. It could have been possible due to large-scale funding of the Resource Recycling R&D Center. The target was to develop an uncatalyzed, continuous and automatic process producing oils that can be used as a fuel for small-scale industrial boilers. The process development has proceeded in three stages bench-scale unit, pilot plant and demonstration plant. As a result, the demonstration plant having capacity of 3,000 tons/year has been constructed and is currently under test operation for optimization of operation conditions. The process consisted of four parts ; feeding system, cracking reactor, refining system and others. Raw materials were pretreated via shredding and classifying to remove minerals, water, etc. There were 3 kind of products, oils(80%), gas(15%), carbonic residue(5%). The main products i.e. oils were gasoline and diesel. The calorific value of gas has been found to be about 18,000kcal/$m^3$ which is similar to petroleum gas and shows that it could be used as a process fuel. Key technologies adopted in the process are 1) Recirculation of feed for rapid melting and enhancement of fluidity for automatic control of system, 2) Tubular reactor specially-designed for heavy heat flux and prevention of coking, 3)Recirculation of heavy fraction for prevention of wax formation, and 4) continuous removal & re-reaction of sludge for high yield of main product (oil) and minimization of residue. The advantages of the process are full automation, continuous operation, no requirement of catalyst, minimization of coking and sludge problems, maximizing the product(fuel oil) yield and purity, low initial investment and operation costs and environment- friendly process. In this presentation, background of pyrolysis technology development, the details of KIER pyrolysis process flow, key technologies and the performances of the process will be discussed in detail.

• Journal of Soil and Groundwater Environment
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• v.25 no.3
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• pp.65-73
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• 2020

Exposure assessment methodology for outdoor air inhalation pathways (i.e., inhalation of volatile compounds and fugitive dust in outdoor air) was investigated. Default values of several parameters currently used in Korea (e.g., Q/C; inverse value of concentration per unit flux, and frs; soil fraction in PM10) may not be suitable and lack site-specificity, as they have been adopted from the risk assessment guidance of the United States or the Netherlands. Such limitation can be addressed to a certain degree by incorporating the volatilization factor (VF) and the particulate emission factor (PEF) with Box model. This approach was applied to an exposure assessment of a site contaminated with petroleum hydrocarbons in Korea. The result indicated that the suggested methodology led to more accurate site-specific exposure assessment for outdoor inhalation pathways. Further work to establish methodology to determine site-specific Q/C values in Korea needs to be done to secure the reliability of the exposure assessment for outdoor air inhalation pathways.