• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1998.11a
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• pp.83-88
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• 1998

방향족 화합물은 합성수지, 합성고무, 합성섬유 등의 석유화학제품의 원료와 2성분 또는 3성분 이상을 혼합한 도료공업에서 광범위하게 사용되고 있다. 그러나 이들 물질들은 공정상의 제조, 저장, 처리과정에서 고온, 고압의 조건에서 많이 노출되어 있을 뿐 아니라 취급과 사용 중에 부주의로 인한 폭발과 화재사고가 증가하고 있다. 그러므로 사고예방을 위해서는 취급하는 물질의 기본적인 위험 특성을 정확하게 파악하여 예방대책을 강구하여야 하므로, 인화성 액체의 경우에는 위험성의 지표인 인화점(Flash point)을 반드시 파악하여야 한다. (중략)

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2002.11a
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• pp.287-290
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• 2002

경제와 전력사용이 호전됨에 따라 냉장기술의 개발이 크게 촉진되면서 진공단열 기술개발을 통한 단열효과 등으로 가전제품의 기술이 세계수준에 도달하였고, 지속적인 기술의 발달로 사용량이 증가하고 있다. 이런 가전제품의 사용증가는 필연적으로 수명이 다한 폐가전 제품이 발생하게되고, 이들을 방치함으로서 환경오염을 일으키게 되었고 정부는 폐가전 제품을 재활용하고 폐기물을 최소화하는 방법을 기업에 요구함과 동시에 폐기물관리법과 자원의 절약과 재활용 촉진에 관한 법률을 제정 공포하게 되었다.(중략)

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2000.06a
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• pp.136-139
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• 2000

현대산업사회의 급속한 발전으로 사용이 편리하고, 깨끗한 연료인 도시가스의 사용량은 점점 더 증대될 뿐만 아니라 사용형태 또한 다양화되고 있어, 이에 따른 사고도 증가하고 있으며 사고의 규모도 대형화 되어가고 있다. 일반적으로 가스폭발의 경우 개방된 영역에서 보다 밀폐된 영역에서 발생할 경우 폭발압력에 의한 파괴효과는 더욱 증가한다. 이러한 부분에 대해 많은 학자들은 단일가스와 산화제를 혼합시킨 형태의 가스 폭발에 대한 특성을 연구하여 왔다. 그러나 산소농도의 변화에 따른 가연성가스의 폭발범위, 폭발시 초기압력의 변화, 최소점화에너지에 관한 연구는 거의 없는 실정이다. (중략)

• Bulletin of the Korean Institute for Industrial Safety
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• v.1 no.1
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• pp.1-6
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• 2001

생활양식의 변화와 정밀산업의 발달로 고체 덩어리나 입자를 분쇄하여 분체의 형태로 사용, 취급, 저장하는 빈도가 증가하고 있으며, 이들 중 분체가 가연성인 경우에는 공기 또는 산소와의 접촉면적이 커서 비교적 쉽게 착화할 뿐 아니라 급격한 연소를 일으켜 화재·폭발의 위험성이 항상 존재하고 있다고 할 수 있다. 이와 같은 위험성을 가지는 가연성 분진에는 소맥분, 전분, 사탕 등의 식료품을 비롯하여 가축용 사료분진, 각종금속, 플라스틱 및 화학제품 등의 가공용 분진, 약품, 연료로 사용되는 석탄 뿐 아니라 섬유부스러기, 연마시의 분진 등을 들 수 있다. 특히 최근에는 신소재로서의 기능성 물질과 전자재료의 개발이 활발하게 진행되어 이 분야에서 분체를 취급하는 공정도 증가하고 있는 실정이다.(중략)

• Education of Primary School Mathematics
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• v.22 no.3
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• pp.181-203
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• 2019

Even though the properties of operations in multiplication serve a fundamental basis of conceptual understanding the multiplication with whole numbers for elementary students, there has been lack of research in this field. Given this, the purpose of this study was to analyze instructional methods related to the properties of operations in multiplication (i.e., commutative property of multiplication, associative property of multiplication, distributive property of multiplication over addition) in a series of mathematics textbooks of Korea, Japan, and the US. The overall analysis was conducted in the following two aspects: (a) when and how to deal with the properties of multiplication in three instructional context (i.e., introduction, application, generalization), and (b) what models use to represent the properties of multiplication. The results of this showed that overall similarities in introducing the properties of multiplication .in (one digit) ${\times}$ (one digit) as well as emphasizing the divers representation. However, subtle but meaningful differences were analyzed in applying and generalizing the properties of multiplication. Based on these results, this paper closes with some implications on how to teach the properties of operations in multiplication properties in elementary mathematics.

• Journal of the Korean Society of Earth Science Education
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• v.15 no.3
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• pp.322-334
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• 2022

This study attempted to understand the difficulties experienced in program development and class operation of instructors in the hands-on science class and the needs for training based on them. For this study, an online survey was conducted on 193 instructors in the hands-on science class in 2022, and interviews were conducted on 13 instructors. As a result, the difficulties of developing programs for hands-on science class instructors were due to lack of class content, lack of program development budget, lack of equipment necessary for class operation, and difficulty in applying various educational methods such as discussion and practice. The preferred training contents were in the order of the latest science and technology, reconstruction methods of existing programs, and regional specialization technology. In addition, it was found that the difficulties experienced by instructors in class management stemmed from the method of operating hands-on science classes using experience kits. Accordingly, instructor education should be provided in the direction of helping instructors to provide the best education in the situation of the hands-on science classroom.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.8
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• pp.791-797
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• 2010

The reliability of a water meter for measuring the water flow-rate and subsequent analysis of the measured water depends on the accuracy of measurement. The under registration of a water meter causes many problems for operators, such as loss in revenue and a decrease in the rate of measured water. The purpose of this study is to support and development core technology, such as efficient operations management and adoption of the best mechanism for providing different services by experimentally. In this study, experiments were conducted using water meters with different diameters, manufacturers, years of usage and the specific uses. On the basis of the results, the water meter confirmed that the error of minimum flow rate which will use long becomes larger more in the direction of minus.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.2
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• pp.68-75
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• 2015

This study established key factors causing deck slab deterioration based on GPR database of 747 highway bridges, and predicted deck slab damage rates with respect to bridge service life. To minimize the influence of bridge service life on deck slab deterioration, the deck slab damage rate database was corrected based on a linear regression model of bridge service life vs. deck slab damage rate. The corrected deck slab damage rates were analyzed to determine correlation considering the number of snowy days, the amount of snowfalls, the number of freeze-thaw days, average winter temperature, altitude, the amount of deicing chemicals and equivalent traffic volume, and then both the number of freeze-thaw days and the amount of deicing chemicals were determined to be key factors causing deck slab deterioration. The complex deterioration considering both key factors was represented deck slab damage rate charts, and the average deck slab life was derived. The results of this study will be used as a guideline for highway bridge maintenance to identify the progress of deck slab deterioration for a given bridge and predict the time required deck slab rehabilitation.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1B
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• pp.113-118
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• 2006

Cost estimation of an intermittent aerobic digestion technology was carried out in this study. Aeration ratio is one of the most important design factors and it affects installation and power consumption cost. For the purpose, digestion efficiency was fixed at 35% of SS reduction and the reactor type was assumed a 2-chamber sequencing batch reactor (SBR). Installation cost and power consumption cost were evaluated and converted in terms of present value that could reflect the rate of discount and the rate of economic growth. The lower aeration ratio needs higher installation cost but lower power consumption cost. From the point of only installation cost, conventional aerobic digestion is cheaper than intermittent aerobic digestion. But intermittent aerobic digestion is better economical for more than 10 years of estimated service life. The optimal aeration ratio was dependent on the service life and it was lower as the estimated service life increased. For the 45 years as the service life, the optimal aeration ratio was estimated 0.3 and the total cost was 64% of the conventional aerobic digestion.

• Korean journal of food and cookery science
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• v.5 no.2
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• pp.63-73
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• 1989

Family meals are very important for physical and mental health of family mebers. The purpose of this study is to contribute to change the habitual and unconscious cooking methods of housewives into more scientific moth(Ids. In order to achieve this purpose, this study tried to find out the degree to which housewives applied their knowledge of nutition and foods to actual behavior in purchasing. A special form of questionaire was prepared and distributed to 502 housewives in Seoul from Feb.8th to 22nd in 1989. The results were as follows: 1. Mean (score) of their nutritional knowledge was 14 7; if seems to be comparatively higher. 2. When they purchased food materials, their husbands' favor was the first consideration. Particularly, freshness was the first considered in purchasing meat, fishes, fruits, and vegetables. And Nutrition was so in case of seaweeds, oil, and fat. 3. For the most part, they cook three or four Subsidiary dishes for a meal. If they cooked one or two they chose to cook vegetables. If three or four they added meat and fishes. If more than four, they used various food materials.