• Communications of Mathematical Education
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• v.38 no.1
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• pp.27-48
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• 2024

In order to prepare for changes in future society, cross-curricular learning is emphasized, and the need to link cross-curricular learning topics and subjects is increasing. However, there are few studies on how to deal with cross-curricular learning in mathematics education. This study analyzed the contents and methods of cross-curricular learning topics in subject-specific curriculum and mathematics textbooks. As a result of the study, the curriculum can be categorized into four types according to the variety of cross-curricular learning topics applied and the presence or absence of a main cross-curricular learning topic, and the mathematics curriculum belongs to the type where some cross-curricular learning topics are dealt with passively and there is no main topic. On the other hand, the analysis of 10 math textbooks for grades 5 and 6 according to the 2015 revised curriculum showed that, unlike the curriculum, various cross-curricular learning topics were applied in the textbooks, mainly environment and sustainable development education, safety and health education, career education, character education, and economic and financial education. In addition, in mathematics textbooks, cross-curricular learning topics appeared in various types such as materials, questions, explanations, illustrations, and in many cases, they appeared mainly as materials or illustrations. Based on these findings, implications were explored and suggested on how to integrate and apply cross-curricular learning topics in mathematics.

• Korean Journal of Organic Agriculture
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• v.13 no.3
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• pp.315-332
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• 2005

This study was conducted to assess the nutritional value and the safety of the fermented food wastes (FFW) made by adding lactobacillus spp. and bacillus spp. at the ratio of 3:7, respectively to food wastes collected everywhere, and also to determine effects on the performances, carcass characteristics and economical profitability when FFW was fed to pigs. For swine trial, FFW was formulate to pellet by utilizing different feed ingredients, and its formulated FFW pellet was used in this feeding trial. Treatments were consisted of different ratios (T1: $100+0\%$, T2: $75+25\%$, T3: $50+50\%$, T4: $25+75\%$, T5: $0+100\%$) of FFW pellet to commercial diet. A total of 20 male pigs were allotted to treatments of five groups of four pigs per pen. Experimental period lasted for 4 months. The nutritional composition of FFW was 56.7, 19.5 and $19.5\%$ for moisture, crude protein and ether extract, respectively. Salt content was $0.39\%$. Noxious microorganisms such as salmonella and E. coli were not detected in FFW, and contents of heavy metal and aflatoxin B1 were lower than the standard. Nutritional values of FFW pellet satisfied over $100\%$ of requirements presented in official Korean feeding standard for swine. Feeding trial for pigs showed that feed intakes were significantly (P<0.05) decreased with increasing levels of FFW pellet. T2 treatment was ideal ratio under the consideration of economical value of feeds and body weight gain of pigs. For carcass characteristics, dressing rate ($\%$) was highest in T3, and carcass grades for T2, T3 and T4 treatments were estimated as 'A'. Feed cost for FFW per kg was ${\won}167.95$, which implies $52\%$ of commercial feed cost (${\won}350/kg$). Thus, this result implied the decreased feed cost in the swine farm. Conclusively, the utilization of food wastes as feed source may lead to the reduced environmental pollution and the practice of organic livestock farming. However, our results showed that excessive amount of fermented food wastes supplementation to pigs might give rise to their reduced palatability and delayed growth.

• Journal of Food Hygiene and Safety
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• v.33 no.4
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• pp.272-279
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• 2018

The high pressure processing (HPP) is a technology which can preserve the quality of foods, such as the fresh taste, incense, texture, vitamin content, and so on, by minimizing the heating process. It does so by applying an instantaneous and uniform pressure that is the same as the water pressure that is 60 km deep in the sea. HPP is a technology that can inhibit food poisoning and spoilage caused by microorganisms and is currently an actively studied area. In this study, we investigated the effects of a high pressure treatment (0, 4, 6 min) on sliced ham, which is a typical meat product, at 600 MP a were tested for their effect on freshness. Moisture contents varied from 48 to 69%, salinity varied from 1.07 to 1.11%, and the pH decreased from 6.4~6.5 to 6.1~5.15. However, there was no difference between the control and treatment groups. General bacteria stored at $20^{\circ}C$ after hyper-pressure treatment were found to have no significant microorganisms in all groups until 4 weeks. but exceeded $10^5$ in control group and HPP 6 min treatment group from 5 weeks, At week 7, it was found to exceed $10^6$. The results indicate it was not possible to ingest food in the 4-and 6 minute treatment groups. Coliform was not observed in all groups despite observing for a total of 7 weeks at $20^{\circ}C$ weight test. VBN, a method used to determine the protein freshness of meat, showed a VBN value of less than 1 mg% until the fourth week and a value of 1 to 2 mg% after 5 weeks. The TBA was used as an index of the degree of fat acidosis in the meat tissues. The results showed it was below 0.18 mgMA / kg until the end of 7 weeks; this value was within the range for fresh meat, and there was no difference in treatment group. In this experiment, deformation of the packaging material did not occur and no swelling occurred due to the generation of gas. It is believed that the basic preservation effect was achieved only by blocking with the air due to the close contact of the packaging material.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.3
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• pp.423-430
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• 2003

The teeth bleaching with bleaching agent is widely used at recent times. Until yet the exact mechanism of the bleaching agent isn't known but it is thought that is by the complex reduction-oxidation reaction of the decomposed free radical from bleaching agent through various ways. In other words, it is supposed that the teeth are whitened by agent's changing chemical structures of stain-causing materials. The purpose of this study is to exam the change of the dentinal character by bleaching agent and to evaluate the safety of this agent. For this study, after applying 10% carbamide peroxide to enamel of human premolar for 6 hours a day for 2 weeks we examined changes of surface morphology, microhardness, composition and contents of minirals in human dentin using SEM, microhardness tester, FT-Raman spectrometer and EPMA and got following results. There was no significant difference in surface morphologic change when we examined the effect of 10% carbamide peroxide which penetrated into dentin after applied on enamel surface comparing with result from specimen in distilled water No change was shown on the surface of peritubular and intertubular dentin within the nanometeric range. The microhardness between bleached teeth and teeth stored in distilled water showed no statistically significant difference FT-Raman spectra of dentin exhibited no change of the component in human dentin. Only the least change in peaks of organic and inorganic materials were detected in Raman intencity. The total content of mineral elements in dentin with no treatment, stored only in distilled water and stored in distilled water after bleaching were $98.73{\pm}1.89,\;98.56{\pm}2.11\;and\;97.47{\pm}2.51$ respectively. Also they showed no statistically significant difference. From above results, the effect of 10% carbamide peroxide bleaching on structure of dentin is very low and the results may confirm the safety of this bleaching agent.

• Journal of Food Hygiene and Safety
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• v.21 no.2
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• pp.82-91
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• 2006

Standard and lead limit test in general test method of Korea, Japan, Joint FAO/WHO Expert Committee of Food Additives (JECFA), USA, and EU on synthetic and natural food additives were compared. There were found that the general test methods in 'Korea Food Additives Code' were different from standards of various institutes on lead limit test. For the lead limit test of food additives, Korea used dithizone method, Japan used atomic absorption spectrophotometry, and USA used dithizone method, flame atomic absorption spectrophotometric method, atomic absorption spectrophotometric graphite furnace method, and APDC extraction method. In addition, JECFA and EU used dithizone method and atomic absorption spectrophotometric method. The dithizone methods of Korea, USA, and JECFA were nearly identical. In the case of USA, JECFA, and EU, the analytical methods for lead limit test were shown in individual monograph. Lead limit test against 13 synthetic, such as magnesium stearate and L-cystine, and 12 natural, such as gua gum and diatomaceous earth, food additives distributed in Korea were performed by the analytical method of each institute. Although all institutes use various methods for analysis of lead, contents of lead in food additives tested fell into the standard of each institute.

• Economic and Environmental Geology
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• v.44 no.1
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• pp.37-48
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• 2011

Some industrial minerals used in domestic industries such as monazite, apatite, bauxite, and ilmenite belong to NORM (Naturally Occurring Radioactive Materials) because they show a high radioactivity. Products, semi-products, wastes, and by-products which show higher radioactivity than NORM belong to TENORM (Technologically Enhanced Naturally Occurring Radioactive Materials). Apatite used for manufacturing phosphate fertilizer in Namhae Chemical company belongs to NORM, and its by-product, phospo-gypsum, belongs to TENORM. A geological investigation is needed for the future environmental impact assessment of the Namhae Chemical company's site. According to survey results of the Namhae Chemical company's site, soil mineral composition indicated the mixture of minerals derived from the country rock (quartz, feldspar, mica, $l4{\AA}$ mineral, kaolin and amphibole) and minerals from the gypsum open-air storage yard (gypsum and apatite). Soil samples showed average content of U 4.6 ppm and Th 10 ppm, which are similar to average crustal abundances. They also show average contents of $^{40}K$ 191-1,166 Bq/kg, $^{226}Ra$ 15.6-710 Bq/kg, and $^{232}Th$ 17.4-72.7 Bq/kg, which indicate moderate levels of radio nuclide. But $^{226}Ra$ anomaly in the gypsum open storage yard is clearly confirmed and $^{232}Th$ anomaly is also confirmed in the east road side of the factory and nearby mountain areas. Soil external hazard indices ranged 0.24-2.01 with the average 0.54. Although most external hazard indices were lower than 1, which means radiation hazard index to be negligible, 5 samples out of total 40 samples showed higher values than 1, and further detailed investigation is needed.

• Journal of Food Hygiene and Safety
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• v.21 no.3
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• pp.189-195
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• 2006

This research was designed to evaluate the nutritional an microbiol quality assessment of Chungmukimbab purchased from market in Tongyeoung area. Contents of calories, calcium, iron, thiamin and riboflavin in ordinary kimbab and Chungmukimbab were lower than the recommended levels of Korean adult men. So, We suggested that a fruit, beverage and ffod stuff were supplemented to maintain nutritional balance. Total aerobic bacteria and coliform group of just prepared ordinary kimbab and Chungmukimbab samples from market were not significantly different, showing approximately $5.50{\pm}0.38 log_{10} CFU/g,\;2.10{\pm}0.47log_{10}MPN/100g$ in ordinary kimbab, $5.61{\pm}0.42log_{10}CFU/g,\;1.75{\pm}0.34 log_{10} MPN/100g$ in Chungmukimbab, respectively. Total aerobic bacteria of law ingredients of chungmukimbab sample were 3 to $4 log_{10}CFU/g$ in kimbab, seasoning squid and radish roots kimchi, 4 to $5 log_{10}CFU/g$ in boiled fish paste. The coliform groups were 1 to $2 log_{10}$ MPN/100 g in kimbab, seasoning squid and radish roots kimchi, 2 to $3 log_{10}$ MPN/100g in boiled fish paste. Detection rate of E. coli and Staphylococcus aureus counts were 10.0, 12.5% in Chungmu-kimbab, 15.0, 10.0% in seasoning squid, 0, 10.0% in radish roots kimchi respectively, not detected in boiled fish paste samples. During storage at $15^{\circ}C$ for 24 hours, total aerobic counts and coliform groups in ordinary kimbab and Chungmukimbab were increased by the 1.94, $0.97log_{10}CFU/g$, 0.60, 0.72 log10 MPN/100g respectively. Total aerobic counts of Chungmukimbab ingredients increased $0.83{\sim}l.33 log_{10}CFU/g$ at different time

• Journal of the Mineralogical Society of Korea
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• v.21 no.2
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• pp.139-159
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• 2008

Geochemical analysis of the various kinds of water including observation borehole groundwater was carried out for the assessment of the hydrological safety of the underground oil storage cavern and the potentiality of mineralogical and microbiological clogging was estimated. Most of water samples belonged to $Ca-HCO_3$ and $Ca-HCO_3-SO_4$ types. There was no distinct chemical difference in the various kinds of water. All kinds of water are undersaturated with the calcite which is the major clogging mineral. Most water samples have low Fe and Mn concentrations. However, they are saturated or oversaturated with the iron-oxide/hydroxide minerals and have high dissolved oxygen contents which suggests the possibility of clogging by the iron-oxide/hydroxide minerals as a long-term aspect. Several water samples from the ground observation borehole also show the high saturation indices far the clay minerals, which can fill up the fractures, indicating the possibility of clogging by the clay minerals. Statistical analysis shows the degree of mineral precipitation or dissolution is mainly controlled by pH, Eh and DO of water samples. According to the microbial analysis, the aerobic microbes and slime forming bacteria are dominant in most water samples and anaerobic microbes including sulfate reducing bacteria are very low or not detected. Although the slime forming bacteria which are known as a main microbial cause of the clogging is lower than $10^5\;CFUs/mL$ in all water samples, because the slime forming bacteria are dominant microbe in several observation boreholes, the clogging can be caused by it as a long-term aspect. In addition, the possibility of clogging can be increased if the microbial effect is combined with the mineralogical effect such as iron oxide/hydroxide minerals for the possibility of clogging. Therefore, the systematic and long-term program for the assessment of clogging is required for the safe operation of underground oil storage cavern.

• Journal of Food Hygiene and Safety
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• v.20 no.4
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• pp.244-252
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• 2005

This study was performed far development of new analytical method of beet red in foods. In this study, analysis of beet red in foods has been carried out by detection of betanine and isobetanine, the main color component of beet red as indicator compounds. The qualitative analysis technique consisted of clean-up of the colors with a $C_{18}$ cartridge, separation of the colors by cellulose TLC plate using acetone:3-methyl-1-butanol:distilled water (7:7:6) as a solvent system. Also, the quantitative analysis was performed using X-terra RP at wavelength 538 nm and $0.1\%$ phosphoric acid : methanol (90:10) as a solvent. The quantitative results of beet .ed were as follows:900.22$\∼$27701.60 $\mu$g/g for 60 item in nutrient supplement food, $21.95\∼713.40{\mu}g/g$ for 30 items and N.D. for 18 items in cindy, and $155.85{\∼}505.37{\mu}g/g$ for 12 items in ice creams, $43.52\∼64.75{\mu}g/g$ for 18 items and N.D. for 54 item in sauce, N.D. for 12 items in retort food.

• Journal of Food Hygiene and Safety
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• v.13 no.3
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• pp.221-231
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• 1998

The biosynthesis of galactolipid and the composition of fatty acid in chloroplast and thylakoid envelope isolated from C. ellipsoidea treated with antiseptics (potassium sorbate: PS, sodium benzoate:SB, calcium propionate:CP) were analyzed. The contents of monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG) and total lipid in treatment with antiseptics were lower to compared with the control. The major fatty acid utilized for biosynthesis of MGDG in chloroplast envelope were palmitoleic acid (ave. 15.55%), oleic acid (ave. 15.09%) in control. Otherwise, the major fatty acids in P.S treatment were utilized for oleic acid (ave. 13.71%), linolenic acid (ave. 14.36%), palmitoleic acid (ave. 18.26%), oleic acid (ave. 17.26%) in S.B treatment, and oleic acid (ave. 16.88%), palmitoleic acid (ave. 16.31%) in CP treatment. It was showed that the major fatty acids in chloroplast envelope DGDG were oleic acid (ave. 15.75%), linolenic acid (ave. 17.74%) in control, oleic acid (ave. 14.90%), palmitoleic acid (ave. 15.97%) in P.S treatment, palmitoleic acid (ave. 13.29%), oleic acid (ave. 15.74%) in S.B treatment, and oleic acid (ave. 14.52%), palmitoleic acid (ave. 14.03%) in C.P treatment. The major fatty acid utilized for biosynthesis of MGDG in thylakoid envelope were linolenic acid (ave. 14.78%), oleic acid (ave. 12.90%) in control. Otherwise, the major fatty acids were utilized for palmitoleic acid (ave. 13.00%), palmitic acid (ave. 13.00%) in P.S treatment, palmitoleic acid (ave. 12.94%), oleic acid (ave. 12.43%) in S.B treatment, and oleic acid (ave. 12.43%), palmitoleic acid (ave. 12.43%) in C.P treatment. It was showed that the major fatty acids in thylakoid envelope DGDG were linolenic acid (ave. 18.01 %), oleic acid (ave. 15.53%) in control, linolenic acid (ave. 19.20%), linoleic acid (ave. 14.14%) in P.S treatment, palmitoleic acid (ave. 9.03%), oleic acid (ave. 14.85%) in S.B treatment, oleic acid (ave. 13.90%), linolneic acid(ave. 12.66%) in C.P treatment.