• Communications of Mathematical Education
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• v.25 no.2
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• pp.403-430
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• 2011

The purpose of the study was to investigate how the use of graphing calculators influence on forming students' mathematical concept of algebra, students' mathematical connection, and attitude toward mathematics. First, graphing calculators give instant feedback to students as they make students compare their written answers with the results, which helps students learn equations and linear inequalities for themselves. In respect of quadratic inequalities they help students to correct wrong concepts and understand fundamental concepts, and with regard to functions students can draw graphs more easily using graphing calculators, which means that the difficulty of drawing graphs can not be hindrance to student's learning functions. Moreover students could understand functions intuitively by using graphing calculators and explored math problems volunteerly. As a result, students were able to perceive faster the concepts of functions that they considered difficult and remain the concepts in their mind for a long time. Second, most of students could not think of connection among equations, equalities and functions. However, they could understand the connection among equations, equalities and functions more easily. Additionally students could focus on changing the real life into the algebraic expression by modeling without the fear of calculating, which made students relieve the burden of calculating and realize the usefulness of mathematics through the experience of solving the real-life problems. Third, we identified the change of six students' attitude through preliminary and an ex post facto attitude test. Five of six students came to have positive attitude toward mathematics, but only one student came to have negative attitude. However, all of the students showed positive attitude toward using graphing calculators in math class. That's because they could have more interest in mathematics by the strengthened and visualization of graphing calculators which helped them understand difficult algebraic concepts, which gave them a sense of achievement. Also, students could relieve the burden of calculating and have confidence. In a conclusion, using graphing calculators in algebra and function class has many advantages : formulating mathematics concepts, mathematical connection, and enhancing positive attitude toward mathematics. Therefore we need more research of the effect of using calculators, practical classroom materials, instruction models and assessment tools for graphing calculators. Lastly We need to make the classroom environment more adequate for using graphing calculators in math classes.

• Horticultural Science & Technology
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• v.30 no.6
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• pp.725-733
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• 2012

Effects of postharvest 1-methylcyclopropene (1-MCP) treatment, controlled atmosphere (CA) storage, and shelf temperature on quality of 'Gamhong' apples were analyzed during export simulation. Fruits were harvested at the optimum maturity for long-term storage, treated with $1{\mu}L{\cdot}L^{-1}$ 1-MCP for 16 hours, and then stored for 6 months under air and CA conditions at $0^{\circ}C$. Poststorage export procedure was performed by applying additional 2-week refrigerated storage and 7-day shelf-life test at 7 and $20^{\circ}C$, which simulated container shipment and local distribution, respectively. After storage and during export simulation, rates of respiration and ethylene evolution were significantly lower in 1-MCP treated and CA-stored apples. For the reduction of respiration, CA storage was more effective than 1-MCP treatment. Soluble solids content was maintained higher in 1-MCP treated apples, while titratable acidity was maintained better both in the 1-MCP treated and CA-stored apples. Effects of 1-MCP treatment and CA storage were highly significant in maintaining flesh firmness and sensory texture ratings. Additive effects from combined application of 1-MCP treatment and CA storage were occasionally observed. Shelf temperature during the local distribution simulation seemed not to significantly influence quality changes only showing limited effects on flesh firmness. Overall results suggest that storage potential of 'Gamhong' apples is shorter than 4 months in control fruit under refrigerated air conditions, whereas the potential can be extended to longer than 6 months by 1-MCP treatment and CA storage. Postharvest program should be provided considering the time of export, i.e. period of storage, and duration of local distribution.

• Korea journal of population studies
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• v.11 no.1
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• pp.159-184
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• 1988

Race and ethnicity are important factors which influence the elderIy's residential adjustment behaviors, although it is unclear whether this reflects influences unrelated to race and ethnlcity. Culturally, the norm of family supportoften obseved among various minority ethnic groups is likely to provide flexible family suppof for the elderIy. Economically, the life-long hardship ofminority groups is likely to force them to maintain extended family living arrangements simply to reduce expenses via economies of scale. Thecontroversy about the economic need versus the cultural prescription forextended living arrangements remains unresoIved because it fails to articulatethe meaning of family supports among many disadvantaged groups.This study aims to test previous economic and cultural arguments, byexamining ethnic differences iu the eiderIy's responsiveness to their health andeconomic problems. Two hypotheses about cultural influences on the elderly's resideutiai adjustment are examined. First, do elderly minorities receive famiiysupporis for longer periods when they are poor if economic and health status\ulcorner Second, do elderiy minorities receive family supports more often when their health status declines\ulcorner Using the Longitudinal Suvey on Aging from 1984 to 1990. this study employs Markovian multi-state life tables, and discrete and contonuous competing hazard analyses for the transition in living arrangements. The main results provide substantial evidence against the cultural resource thesis. Elderly minorities experience more frequent transition between living alone and living with relatives than white elderly persons when group differences in the extent of mortality and insititutionalization are controlled. The shorter timf of living alone among elderly monorities stems from their greater likehood of joining relatives as well as greater mortality and attrition rates than elderly whites. Coresidence of elderly whites with their relatives is more likely to occur in response to their needs for health care than of elderly whites. it implies that instability. not flezibility. characterrizes elderly minorities living arrangements.

• The Journal of the Korea Contents Association
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• v.16 no.8
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• pp.292-309
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• 2016

The purpose of the present paper is to investigate the effects of stress and depression experienced by the first (1955-1964) and second (1968-1974) generations of baby boomers on their psychological well-being as well as the moderation effects of social supports for them. For this purpose, 369 who come under the category of the first- and second-generation baby boomers were selected by convenient sampling from among the participants in the programs of the life-long educational institutes in Seoul metropolitan area and questionnaires of self-administered type were distributed to them. Frequency analysis, t-test, ANOVA, correlation analysis and hierarchial regression analysis which used input of mean-centered variables and interaction term were conducted to determine the moderating effects of social supports based on the replies to the questionnaires. The major outcomes of the analyses could be summed up as follows: first, the stress and depression suffered by the first and second generations of baby boomers turned out to have negative (-) influence upon their psychological well-being; second, the social supports for those two generations were found to exercise positive (+) effects upon their psychological well-being; and third, a survey of difference in the moderating effects of social supports between the first- and second-generation baby boomers showed that, in case of the first generation, the worse their economic status and the higher their stress and depression were, the lower their psychological well-being tended to be and that social supports functioned to hike their psychological well-being but had moderating effects only in connection with stress. In case of the second generation, however, it was shown that the higher their stress and depression got, the lower their psychological well-being developed and that social supports might increase their psychological well-being but without any moderating effects on the part of relationship with their stress and depression. A practical and political method was discussed to improve baby boomers mental health.

• 한국유가공학회:학술대회논문집
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• 2002.11a
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• pp.23-40
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• 2002

This study was conducted to investigate the quality changes of the UHT(ultra-high temperature), LTLT(law temperature long time) and HTST(high temperature short time) treated milk samples by storage conditions for 6 months from August 2000 to February 2001. The UHT treated milk samples collected from 3 plants(A, B and C) were stored at l0$^{\circ}$C and room temperature(dark and light exposure) for 6 months, and the LTLT and HTST treated milk samples(D and E) were also stored for 30 days. The UHT pasteurized milk of A, B and C plant was treated at 130$^{\circ}$C for 2-3s, 133$^{\circ}$C for 2-3s and 135$^{\circ}$C for 4s, respectively. The UHT sterilized milk of A and B plant was treated at 140$^{\circ}$C for 2-3s and 145$^{\circ}$C for 3-4s, respectively. The LTLT milk of D plant was treated at 63$^{\circ}$C for 30 mins, and the HTST milk of E plant was treated at 72$^{\circ}$C for 15s. All of the raw milk samples collected from storage tank in 5 milk plants were showed less than 4.0 X 10$^5$cfu/ml in standard plate count, and normal level in acidity, specific gravity, and component of milk. Preservatives, antibiotics, sulfonamides and available chloride were not detected in both raw and heat treated milk samples obtained from 5 plants. One(10%) of 10 UHT pasteurized milk samples obtained from B plant and 2 (20%) of 10 from C were not detected in bacterial count after storage at 37$^{\circ}$C for 14 days, but all of the 10 milk samples from A were detected. No coliforms were detected in all samples tested. No bacteria were also detected in carton, polyethylene and tetra packs collected from the milk plants. A total of 300 UHT pasteurized milk samples collected from 3 plants were stored at room(3$^{\circ}$C ${\sim}$ 30$^{\circ}$C) for 3 and 6 months, 11.3%(34/300) were kept normal in sensory test, and 10.7%(32/300)were negative in bacterial count. The UHT pasteurized milk from A deteriorated faster than the UHT pasteurized milk from B and C. The bacterial counts in the UHT pasteurized milk samples stored at 10$^{\circ}$C were kept less than standard limit(2 ${\times}$ 10$^4$ cfu/ml) of bacteria for 5 days, and bacterial counts in some milk samples were a slightly increased more than the standard limit as time elapsed for 6 months. When the milk samples were stored at room(3$^{\circ}$C ${\sim}$ 30$^{\circ}$C), the bacterial counts in most of the milk samples from A plant were more than the standard limit after 3 days of storage, but in the 20%${\sim}$30%(4${\sim}$6/20) of the milk samples from B and C were less than the standard limit after 6 months of storage. The bacterial counts in the LTLT and HTST pasteurized milk samples were about 4.0 ${\times}$ 10$^3$ and 1.5 ${\times}$ 101CFU/ml at the production day, respectively. The bacterial counts in the samples were rapidly increased to more than 10$^7$ CFU/ml at room temperature(12$^{\circ}$C ${\sim}$ 30$^{\circ}$C) for 3 days, but were kept less than 2 ${\times}$ 10$^3$ CFU/ml at refrigerator(l0$^{\circ}$C) for 7 days of storage. The sensory quality and acidity of pasteurized milk were gradually changed in proportion to bacterial counts during storage at room temperature and 10$^{\circ}$C for 30 days or 6 months. The standard limit of bacteria in whole market milk was more sensitive than those of sensory and chemical test as standards to determine the unaccepted milk. No significant correlation was found in keeping quality of the milk samples between dark and light exposure at room for 30 days or 6 months. The compositions of fat, solids not fat, protein and lactose in milk samples were not significantly changed according to the storage conditions and time for 30 days or 6 months. The UHT sterilized milk samples(A plant ; 20 samples, B plant ; 110 samples) collected from 2 plants were not changed sensory, chemical and microbiological quality by storage conditions for 6 months, but only one sample from B was detected the bacteria after 60 days of storage. The shelflife of UHT pasteurized milk in this study was a little longer than that reported by previous surveys. Although the shelflife of UHT pasteurized milk made a significant difference among three milk plants, the results indicated that some UHT pasteurized milk in polyethylene coated carton pack could be stored at room temperature for 6 months. The LTLT and HTST pasteurized milk should be sanitarily handled, kept and transported under refrigerated condition(below 7$^{\circ}$C) in order to supply wholesome milk to consumers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.237-245
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• 2017

This cross-sectional descriptive study was conducted to determine the health conditions and health behaviors of merchants at traditional markets and compare them with members of the general population[ED highlight - do you mean "members of the general population"?]. The data were collected from 307 merchants at N traditional market in C City from 1-20 June 2015 at D Health Center of C City after physical measurement and blood collection and then analyzed using SPSS WIN 21.0. The male, female, and overall smoking rates of merchants at the traditional market were 34.2%, 3.5% and 11.1%, the annual drinking rates were 68.4%, 38.5%, and 45.9%, and the rates of subjects under stress and the rates of experiencing depression were 23.7%, 28.5%, and 27.4% and 5.3%, 6.1%, and 5.9%, respectively, which were all relatively lower than members of the general population[ED highlight - please ensure that my changes here are in keeping with your intended meaning.]. The male, female and overall rates of medium-level physical activities and walking were 32.9%, 19.9%, and 23.1% and 85.5%, 79.2%, and 80.8%, respectively, to have relatively good health behaviors, and the mental health is relatively fine than members of the general population[ED highlight - please clarify this, I cannot infer your intended meaning.]. However, test group[ED highlight - the test group? Please specify.] had high prevalence rates of hypertension, diabetes, hypercholesterolemia, and metabolic syndrome. Moreover, as the duration of work increased, the abdominal circumference as well as the prevalence rates of low HDL-cholesterol, hypertension, metabolic syndrome, and arthritis increased. Therefore, the specific causes of these shall be determined, and the long-term daily life improvement program shall be prepared and applied continuously for merchants at traditional markets.[ED highlight - please specify what these refer to; however, the entire sentence can probably be deleted.

• Journal of Korean Society of Forest Science
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• v.83 no.2
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• pp.191-204
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• 1994

Due to its topographic complexities and various climatical condition, Korea exhibits diverse forest types. Dominant tree species in this zone are Quercus spp., Betula spp., Zelkova spp., Fraxinus spp., Pinus densiflora, Pinus koraiensis, and Pinus thunbergii ete. Genetic conservation in forest species in Korea there are three ways ; one is in situ, other is ex situ and third is in-facility conservation. In situ conservation include that are the present status of conservation of rare and endangered flora and ecosystem, the reserved forest, the national and provincial park, and the gene pool of natural forests. Ex situ conservation means to be established the new forest from in situ forest stands, progeny and provenance test populations, seed orchard and clone banks, and gene conservation in-facility. As a tool for low temperature storage, several aspects on in vitro system were studied ; (1) establishment of in vitro cultures from juvenile and/or rejuvenated tissues, (2) induction of multiple shoots from the individual micropropagules, (3) elongation of the proliferated shoots. Studies on cold storage for short-and long-term maintenance of in vitro cultures under $4^{\circ}C$ in the refrigerator were conducted. For the cryopreservation at $-196^{\circ}C$, various factors affecting survivability of the plant materials are being examined. The necessity of gene conservation of forest trees is enlarged not only to increase the adaptability for various environments but also to gain the breeding materials in the future. For effective gene conservation of forest trees, I would like to suggest followings ; 1. Forest stands reserved for other than the gene conservation purposes such as national parks should be investigated by botanical and gene-ecological studies for selecting bio-diversity and gene conservation stands. 2. Reserved forest for gene pool should be extented both economically important tree spp. and non-economical species. 3. Reserved forest for progeny test and clone bank should be systematically investigated for the use of Ex situ forest gene conservation. 4. We have to find out a new methodology of genetic analysis determining the proper and effective size of subpopulation for in situ gene conservation. 5. We should develop a new tree breeding systems for successful gene conservation and utilization of the genetic resources. 6. New method of in-facility gene conservation using advanced genetic engineering should be developed to save time and economic resources. 7. For the conservation of species with short-life span of seed or shortage of knowledge of seed physiology, tissue culture techniques will be played a great role for gene conservation of those species. 8. It is are very useful conservation not only of genes but of genotypes which were selected already by breeding program. 9. Institutional and administrative arrangements including legistlation must be necessarily taken for gene conservation of forest trees. 10. It is national problems for conservation of forest resources which have been rapidly destroyed because of degenerating environmental condition and of inexperienced management system of bio-diversity and gene conservation. 11. In order to international cooperation for exchanging data of bio-diversity and gene conservation, we should connect to international net works as soon as possible.

• The Korean Journal of Pesticide Science
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• v.16 no.2
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• pp.121-130
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• 2012

In analyzing pesticide residue, LLE (liquid liquid extraction) is generally applied as one of the existing methods, but needed quite a lot of organic solvents and analytical apparatuses for the sample pre-treatment. In addition to its long analysis time and complex analytical processes, it is required to develop a more rapid and efficient method at present. In order to establish an economic and simple pesticide residue analytical method, this study carried out a comparative experiment on the existing analytical method with a new sample pre-treatment method named QuEChERS (quick, easy, cheap, effective, rugged and safe), which extracts and refines pesticide components by directly adding solid powder into the sample. Both the two analytical methods showed favorable values of correlation coefficient ($R^2$ > 0.99) of calibration curves. In terms of the detection limit (identification limit), imidacloprid showed 0.02 mg/kg, while the rest of pesticides showed a level around 0.05 mg/kg. The results of this experiment revealed that the recovery of LLE was 92.8-100.9% and the RSD was below 2.5%. On the other hand, the recovery of QuEChERS was 92.2-101.6% and RSD was below 1.9%. As a result of comparing the amount of pesticide residue by the time between the two analytical methods by using Paired t-Test, there was no significant difference between the two analytical methods as the p-value ranged from 0.3148-0.9890. Considering the results of the two methods, the QuEChERS method had similar recovery, compared to the analytical method using the existing LLE, and the analytical time was shortened by about one fourth of that of the existing method. Moreover, since it excludes the use of harmful organic solvents like dichloromethane during the process of extraction, thus leading to protecting experimenters health and remarkably reducing the amount of disused solvents, it is judged as an echo-friendly and economic analytical method.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.6
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• pp.432-445
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• 2000

The objective of this study was to determine the effects of various kinds of composts on the change of nutrition loss in upland soils. Field experiments were conducted in the loam and sandy loam soils, while the clay loam and sandy loam soils were used for laboratory experiments. Various kinds of composts such as poultry manure compost(PMC), cow manure compost(CMC), human excrement sludge(HES), and food industrial sludge compost(FISC) were applied annually at rates of 0, 40, and $80mg\;ha^{-1}$ to soils grown with soybean and maize plants for 4 years during 1994 to 1997. The results of this study were as follows : The loss of nutrients in the form of cation and anion by run-off water increased with the increase of compost application rate. Compared with bare soils, maize cultivation decreased the nutrient loss by run-off from soils by 43% in anionic form and 32% in cationic form. Amount of cation loss were ordered $K^+$ > $Ca^{2+}$ > $Na^+$ > $Mg^{2+}$ > $NH_4{^+} $ and that of anion loss were ordered $SO_4{^{2-}}$ > $NO_3{^-}$ > $Cl^-$ > $PO_4{^{3-}}$. Nutrient loss of sand loam soil in the cation and anion by percolation water increased 1.7 times compared with loam soil. $NO_3{^-}-N$ contents in percolated water were high at the initial stage after compost application, and the amounts were higher in sandy loam soil than loam soil. The maize cultivation also decreased the $NO_3{^-}-N$ contents in percolated water by 82% in loam soil, and 58% in sand loam soil. Soil pH of composts determined by laboratory incubation test increased pH 6.1~6.8 application with poultry and cow manure compost but application with human excrement sludge decreased pH 4.5~4.7. Soil EC were increased initially composts application and decreased up to 2 weeks, thereafter kept a certain level. Nitrogen mineralization rates of composts determined by laboratory incubation test at $25^{\circ}C$ were 39~76% in sandy loam soil, and 16~48% in clay loam soil.

• Tuberculosis and Respiratory Diseases
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• v.47 no.6
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• pp.807-816
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• 1999

Background: Sarcoidosis, uncommon in Korea, has variable clinical course, ranging from benign self-limited recovery to life-long disability regardless of corticosteroid therapy. The purpose of this study is to observe the clinical course of untreated sarcoidosis. Methods: Twenty four patients who were confirmed as sarcoidosis by tissue diagnosis were included. For average 12month follow-up periods, subjective symptoms, radiologic findings, and parameters of pulmonary function test(FVC, $FEV_1$, DLco) were evaluated every 3mooths compared between corticosteroid treated(n=5) and non-treated(n=19) patients. 'Deterioration' was defined if patients met more than one of followings (1) decrement in any parameters of pulmonary function test(2) worsening in the degree of dyspnea(3) increase in radiologic extents, and (4) newly developed extrapulmonary sarcoidosis. 'Stable' was defined as no significant interval changes in every parameters. 'Improvement' was defined as decrement of extension of the radiologic lesions without deterioration. Results: Among 19 untreated sarcoidosis patient, one deteriorated, 14 improved(13 of them showed complete resolution in radiology), and 4 were remained stable. On the other hand, five corticosteroid treated patients, uveitis was developed in one, 2 improved, and 2 remained stable. Conclusion : These findings suggest that patient with sarcoidosis, especially those without serious extrapulmonary disease, has stable clinical course and would not need corticosteroid therapy.