• Journal of Korea Foundry Society
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• v.43 no.3
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• pp.107-136
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• 2023

Natural silica sand was commonly used for sand casting of cast steel products, and chromites sand was used to suppress seizure defects due to the lack of thermal properties of silica sand. However there are disadvantages such as deterioration by repeated use, system sand mixing problem, difficulty separating and removing, increased during mold according to high density and to being waste containing chrome. Recently, industrial waste reduction and atmospheric environment improvement have been highlighted as important tasks in the casting industry. In order to solve the problems that occur when using foundry Sand and to improve the environment of casting factories, various artificial sands that can be applied instead of natural silica sand have been developed and introduced. Artificial sands can be classified into artificial sand manufactured by the electric arc atomization or gas flame atomization, artificial sand manufactured by the spray drying & sintering process, artificial sand manufactured by the sintering & crushing process and exhibit different physical properties depending on the type of raw-minerals and manufacturing method. In this study, comparative evaluation tests were conducted on the physical properties of various foundry sands, mold strength, physical durability, thermal durability, and casting test pieces. When comprehensively considering the actual amount of molding sand used according to density, the mold strength according to the shape of sand, the physical and thermal durability of foundry sand, and the heat resistance characteristics of foundry sand, 'Molten artificial sand A1' or 'Molten artificial sand B' is judged to be the most suitable spherical artificial sand for casting of heavy steel castings.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.31 no.4
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• pp.391-402
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• 1986

A total of 16 varieties from Korea and Indonesia were tested in Suwon, Korea (126$^{\circ}$9'E, 37$^{\circ}$16'N, 37m amsl) and Bali, Indonesia (115$^{\circ}$ 14'E, 8$^{\circ}$42' and 10m amsl). Most varieties of Indica and India/Japonica types showed adaptability to both areas. Generally Indica-type showed more number of panicles per hill than that of Indica/Japonica, while Indica/Japonica showed better performance in spike let number per panicle and 1,000 grain weight than Indica-type varieties.

• Journal of Korean Home Economics Education Association
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• v.19 no.3
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• pp.149-168
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• 2007

The purpose of this study was to analyze the home economics education items in the teacher recruitment examination for secondary school. To achieve the purpose, all the home economics education items, which were carried out for seven times from the school year 2001 to the most recent year 2007, were compared and analyzed. The form of items was analyzed by frequency and rate. Behavioral domain of items was analyzed by content analysis. In this study, some recommendations were suggested for the quality of home economics education items through discussion of science education and society education items, which were abstracted from the school year 2001 to the most recent year 2007. The results of this study were as follows. First, the score ratio of home economics education items was fluid as 20-30% from the school year 2001 to 2004 but it fixed as 30-35% since the school year 2005. In subcategory of home economics education, curriculum items accounted for highest ratio(43%). In the next thing, items of teaching-learning method(35%), evaluation(19%) and philosophy(3%) related to home economics education were followed in order. Second, the form of home economics education items was coexistent form of single item and subordinate item from the school year 2001 to 2004. But it was changed into form of single item by 100% since the school year 2005. Third, regarding the content of home economics education items, most of the curriculum items were related to the content of the 7th National Curriculum. Teaching-learning method items were taken mostly from model of teaching-learning. Evaluation items were taken mostly from performance assessment. Philosophy items related to home economics education were taken only from Habermas's three systems of action on the school year 2005. Fourth, about behavioral domain of home economics education items, most of the curriculum items were level of 'simple knowledge or memory'. Therefore, it was suggested that behavioral domain of curriculum items had to be changed into 'complex knowledge or comprehension and application'. The behavioral domain of teaching-learning method items and education evaluation items was mostly 'complex knowledge or comprehension and application'. However, to bettering the items it was suggested that the behavioral domain of them has to be changed 'comprehension' into more 'application'. Fifth, regarding the coverage of home economics education items, curriculum items were limited only superficial content of the 7th National Curriculum. Therefore, it was suggested that coverage of curriculum items had to be extended to theoretical content, which was philosophical background and various principles of curriculum. It was suggested that coverage of teaching-learning method items had to be extended to the content including various teaching-learning theories and the practical reasoning home economics instruction proved effective as home economics instruction recently. Evaluation items were taken mostly from performance assessment. Therefore, it was suggested that coverage of evaluation items had to be extended to analysis of evaluation result, item validity and reliability, and evaluator's philosophical perspective.

• Journal of the Society of Disaster Information
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• v.17 no.1
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• pp.10-24
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• 2021

Purpose: The purpose of this study is to determine the dangers of biodiesel and general diesel mixtures currently used as alternative fuels by equipment (tag method and penski Marten method) and to determine the difference between flash point and combustion point (closed, open) according to test methods. It is intended to be used as a reference material for identification and evaluation of firecausing substances by confirming the risk of mixtures by comparative analysis and measurement, and establishing a risk assessment method for chemical substances. Method: Flash point test method and result treatment were tested based on ASTM and KS M mode, which are tag sealing and pen schematense test methods used as flash point and combustion point test methods for crude oil and petroleum products. The manufacturer of the equipment used in this experiment was a test equipment that satisfies the test standards of KS M 2010 with equipment produced by TANAKA of Japan. The flash point and combustion point were measured, and the flash point according to the test method of biodiesel and general diesel mixture ( Closed, open), and the ignition point of a mixture of biodiesel and general diesel was compared and analyzed for ignition risk compared with conventional diesel. Results: Looking at the experimental results, first, as an analysis of the risk of flammability of the mixture, the flash point of a substance containing 70% biodiesel was found to be about 92℃ based on general diesel with a flash point of 64.5℃, and gasoline and biodiesel or When the biodiesel mixture was synthesized, it was confirmed that the flash point tends to decrease. In addition, the difference between the flash point and the combustion point was analyzed as about 20 ~ 30℃, and when a small amount of gasoline or methanol was mixed, the flash point was lowered, but it was confirmed that the combustion point was similar to that of the existing mixture. Conclusion: In this study, in order to secure the effectiveness of the details of the criteria for judging dangerous materials in the existing Dangerous Materials Safety Management Act, and to secure the reliability and reproducibility of the judgment of dangerous materials, we confirm the criteria for judging the risk of the mixture through an experimental study on flammable mixtures. It will be able to provide reference data for experimental criteria for flammable liquids that are regulated in the field. In addition, if this study accumulates know-how on experiment by test method, it is expected that it can be used as a basis for research on risk assessment and research on dangerous goods.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.21 no.1
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• pp.97-124
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• 1976

To find out the most effective method of treatments for the induction of sprouting of dormant seed potato pieces for the fall crop production of Irish cobbler, this experiment was carried out with sprout inducing bed and field performance trial. In GA treatments, about 10 days were required to sprout and resulted uniform and thin 3-4 sprouts per tuber piece, but sprouts were slender and rooting was not observed. In Ethrel treatments, 20-25 days were required, and sprouts were inferior than that of GA treatment in uniformity of sprouting, and percentage of rotten pieces and of healthy sprouted tuber pieces, but number of sprouts per tuber pieces was low, being 1-2, and sprouts were short, thick, and healthy, and showed good rooting. In GA and Ethrel mixture treatments, 1-2 more days were required to sprout than GA treatments, but sprouts were relatively healthy, and other sprouting pattern were like that of GA treatments. In Ethylene chlorohydrin and 6-Benzyl-adenine treatments, sprouting was like that of Ethrel treatments, but much more days were required than Ethrel treatments and tendency of severe rotting was observed. Optimum treating methods of promising chemicals found to be 1-2 and 2-5 ppm GA solution, 500 and 1000-2000 ppm Ethrel solution, and 1-2＋250-500 and 5＋250-500 ppm GA and Ethrel mixture solution for 60 min. treatment of tuber piece and whole-tuber, respectively. Induction of sprouting in dry and hot time resulted severer rotting of tuber pieces during the induction of sprouting and with the advancement of dormancy, being delayed in date of treatment, tendency of promotion of sprouting and rooting was observed. When sprouted tuber piece was transplanted at the same date, yields were in order of Ethrel, GA and Ethrel mixture, and GA treatment, indicating the correlation between yield and healthiness of sprout and rooting status of sprouted tuber piece. In all treatments, earlier transplanting resulted higher yields.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.3
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• pp.319-325
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• 2015

High-strength steel has replaced mild steel as the material of choice for truck decks or frames, owing to the growing demand for lightweight vehicles. Although studies on the weld fatigue characteristics of mild steel are available, studies on high-strength steels have been seldom conducted. In this study, firstly, we surveyed a chosen number of approaches and selected the Radaj method, which uses the notch factor approach, as the one suitable for evaluating the fatigue life of commercial vehicles. Secondly, we obtained the S-N curves of HARDOX and ATOS60 steel welds, and the F-N curves of the T-weld and overlapped-weld structures. Thirdly, we acquired a general S-N curve of welded structures made of high-strength steel from the F-N curve, using the notch factor approach. Fourthly, we extracted the weld fatigue characteristics of high-strength steel and incorporated the results in the database of a commercial fatigue program. Finally, we compared the results of the fatigue test and the CAE prediction of the example case, which demonstrated sufficiently good agreement.

• Korean Journal of Food Science and Technology
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• v.42 no.3
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• pp.257-262
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• 2010

Patulin, a secondary metabolite of mold, is commonly found in rotten apples. Many countries regulate patulin at levels ranging from 30 to $50\;{\mu}g/L$. Most analytical methods for removing patulin from apple juice include liquid-liquid extraction (LLE), which is time and labor intensive. To replace the LLE method, a solid-phase extraction (SPE) method has been developed for apple juice and unfiltered apple juice. A portion of the test sample was applied to a macroporous copolymer cartridge and washed with 5 mL of 1% sodium bicarbonate, followed by 5 mL of 1% acetic acid. Patulin was eluted with 5 mL of 2% acetonitrile in anhydrous ethyl ether. The mobile phase was tetrahydrofuran in water (0.8:99.2) and was detected with a UV detector at 276 nm. Recoveries ranged from 95 to 101% in test samples, and the minimum detectable level was 30 ppb. Because this SPE method is fast, easy, reliable, and inexpensive, it could be applicable for companies or analytical agencies to analyze patulin concentrations in apple juice.

• Journal of Energy Engineering
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• v.6 no.2
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• pp.129-136
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• 1997

This paper presents a new economic load dispatch considering atmospheric emissions such as NOx and SO$_2$caused by the operation of fossil-fueled thermal generation in power systems. The proposed method is described for scheduling their output of thermal power units so as to comply with total emission constraint, area emission constraint and the both of those constraints. Also, by using a trade-off curve, representing all dispatch alternatives and conflict between the emission and the fuel cost, the sensitivity analysis of the emission and the fuel cost is applied to this algorithm. By the way, this proposed method is analyzed how dispatch changes as a function of the total environmental cost, and as a function of the relative weighting of individual environmental insults, e.g, NOx and SO$_2$. By applying the proposed method to the system, the usefulness of this method is verified.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1131-1134
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• 2003

이 논문은 현재 국내에서 사용하고 있는 배전용 케이블 열화진단장치인 완화전류 측정장치의 진단기준 개선을 위한 것이다. 현재까지 사용되던 직류 고전압을 이용한 누설전류 측정법을 대체하기 위해 사용되는 완화전류 측정장치는 국내 배전선로에서 수년간 현장적용을 실시하여 많은 케이블을 교체하였다. 하지만 완화전류 측정을 통해 교체한 케이블의 상태에 대해서는 검증되지 않은 상태이므로 완화전류 측정을 통한 교체기준이 국내 케이블에 적절한지 확인할 필요가 있다. 이는 케이블 유지보수에 있어서 중요한 사항으로서 교체기준이 부적절할 경우 열화진단을 통한 고장방지 목적을 달성할 수 없거나 건전한 케이블을 교체하여 불필요한 예산을 낭비하는 원인이 된다. 본 논문에서는 현장운전중인 선로를 선택하고 열화된 케이블의 절연성능 향상을 위해 실리콘을 주입하였다. 그리고 실리콘 처리후 케이블의 운전시간에 따른 열화진단 결과와 케이블 절연파괴강도를 비교하여 진단장치의 신뢰성을 검증하고자 하였다. 이것은 1년 동안의 현장시험 결과를 정리한 것이다.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.44 no.4
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• pp.363-373
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• 2018

In recent years, parabens used as preservatives in cosmetics have become a problem of human safety. Therefore, in this study, we tried to evaluate the preservative efficacy of 1,3-butylene glycol, 1,2-hexanediol, and 1,2-pentanediol as a preservative system to replace parabens. 1,3-Butylene glycol was added to cosmetic creams at a concentration of between 5 and 25%. The preservative efficacy of 1,3-butylene glycol was determined using a M-3 challenge test, as recommended by the Personal Care Products Council (formally CTFA). The alkane diols, such as 1,2-hexanediol and 1,2-pentanediol, were assessed in a similar manner. An evaluation of the preservative efficacy of 1,3-butylene glycol revealed that it was effective against all tested microbial strains at a concentration of 25%. We also investigated the efficacy of combinations of 0.3% phenoxyethanol and 0.1% ethylhexylglycerin. Finally, we tested the alkane diols, including 1,2-hexanediol and 1,2-pentanediol, as an alternative to the preservative 0.3% phenoxyethanol. Both 1% 1,2-hexanediol and 1% 1,2-pentanediol demonstrated preservative efficacy. Taken together, our study demonstrated that the formulation of 25% 1,3-butylene glycol and 0.1% ethylhexylglycerin, 1% 1,2-hexanediol, and 1% 1,2-pentanediol had the best preservative efficacy of the compositions tested. Thus, this study suggests that the formulation is a possibility of substituting parabens preservatives, which has been used in cosmetics and has become a safety issue.