• 한국과학교육학회지
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• 제22권3호
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• pp.432-443
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• 2002

본 연구는 제 7차 교육과정에 따른 7학년 과학 교과서 생물 및 물질 영역에 제시된 과학 개념을 구체적 개념 수준과 형식적 개념 수준으로 나누어 비교 분석 하였다. 분석 교과서는 검정되어 현재 학교에서 사용되고 있는 6종을 대상으로 하였으며, 생명 영역의 '생물의 구성', '소화와 순환', '호흡과 배설', 물질 영역의 '물질의 세 가지 상태', '분자의 운동', '상태변화와 에너지' 단원 등 총 6개 단원의 과학 개념을 분석하였다. 7학년 과학교과서에 제시된 총 개념의 수는 생명 영역에서 305개, 물질 영역이 73개로 물질 영역 보다 생명에서 훨씬 많은 개념이 제시된 것으로 조사되었다. 교과서별로는 제시된 개념의 수가 다소 차이를 보였는데, 생명 역역에서는 179${\sim}$201개, 물질 영역은 33${\sim}$39개로 나타났다. 각 영역별로 구체적 개념과 형식적 개념의 비율을 살펴보면, 생명 영역은 각각 58%, 42%, 물질 영역은 각가 14%, 86%로 영역에 따라 극명한 차이를 나타내는 것으로 조사되었다. 이는 교육과정 및 교과서 개발 시 학습자의 인지 수준을 고려한 과학 개념의 제시 또는 교과 영역의 특서엥 따라 단원 구성에 있어서 차별화 해야함을 시사한다고 하겠다.

• 한국과학교육학회지
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• 제27권9호
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• pp.778-786
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• 2007

이 연구에서는 비유를 사용한 화학 개념 학습에서 대응 오류 분석 활동의 효과를 개념 이해도,대응 관계 이해도,수업에 대한 인식 측면에서 조사하였다. 2개 중학교의 1학년 121명을 비교 집단과 처치 집단으로 배치한 후,'물질의 상태와 분자 배열'에 대하여 수업을 실시하였다. 비교 집단에서는 TWA 모형에 기초한 비유 수업을 하였고,처치 집단에서는 TWA 모형의 '유사성 대응' 및 '차이점 지적'을 '대응 오류 분석 활동'으로 대체한 수업을 하였다. 연구 결과,학생들의 장의존성 장독립성에 관계없이 개념 이해도 검사와 대응 관계 이해도 검사에서 처치 집단의 점수가 비교 집단보다 높았으며,그 차이가 통계적으로 유의미하였다. 수업에 대한 인식 검사 결과에서는 대부분의 학생들이 비유를 사용하는 수업에 대해 긍정적으로 인식하였으나,처치 집단의 학생들은 대응 오류 분석 활동을 어려워하는 것으로 나타났다. 이에 대한 교육적 함의를 논의하였다.

• 한국과학교육학회지
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• 제25권7호
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• pp.721-727
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• 2005

이 연구에서는 물질의 입자성에 대한 개념 학습에서 소집단 그림 그리기의 효과를 조사하였다. 경기도에 소재한 남녀공학 중학교 1학년 126명을 2인 1조의 소집단 그림 그리기 집단, 개별 그림 그리기 집단, 통제 집단으로 배치한 후,'물질의 세 가지 상태'와 '분자의 운동' 단원에 대하여 8차시 동안 수업을 실시하였다. 사전 검사로 자아효능감, 학습 동기, 과학 수업에 대한 즐거움 검사를 실시하였고, 사후 검사로 학업 성취도, 개념 이해도, 학습 동기, 과학 수업에 대한 즐거움 검사를 실시하였다. 이원 공변량 분석 결과, 소집단 그림 그리기 집단의 학업 성취도와 개념 이해도 검사 점수가 통제 집단보다 유의미하게 높았다. 그러나 학습 동기와 과학 수업에 대한 즐거움 검사 점수에서는 집단간에 유의미한 차이가 없었다. 모든 종속 변인에 대하여 수업 처치와 자아효능감 수준 사이의 상호작용 효과는 없었다.

• 에너지공학
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• 제26권4호
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• pp.45-56
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• 2017

Coal power plants produce electricity for the nation's power grid, but they also produce more hazardous air emissions than any other industrial pollution sources. The quantity is staggering, over 386,000 tons of 84 separate hazardous air pollutants spew from over 400 plants in 46 states. In South Korea also, annual coal ash generation from coal-fired power plants were about 6 million tons in 2015. Pollutants containing particulate matter 10, 2.5 (PM10, PM2.5), heavy metals and dioxins from coal-fired power plant. The emissions threaten the health of people who live near these power plants, as well as those who live hundreds of miles away. These pollutants that have long-term impacts on the environment because they accumulate in soil, water and animals. The present study is to investigate the physical and chemical characteristics of coal-fired power plant fly ash and bottom ash contains particulate matter, whose particulate sizes are lower than $PM_{10}$ and $PM_{2.5}$ and heavy metals. There are wide commercial technologies were available for monitoring the PM 2.5 and ultra-fine particles, among those carbonation technology is a good tool for stabilizing the alkaline waste materials. We collected the coal ash samples from different coal power plants and the chemical composition of coal fly ash was characterized by XRF. In the present laboratory research approach reveals that potential application of carbonation technology for particulate matter $PM_{10}$, $PM_{2.5}$ and stabilization of heavy metals. The significance of this emerging carbonation technology was improving the chemical and physical properties of fly ash and bottom ash samples can facilitate wide re use in construction applications.

• 한국과학교육학회지
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• 제26권1호
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• pp.9-15
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• 2006

학생들은 화학에서 입자 개념의 중요성에도 불구하고 이를 어려워한다. 이에 여러 연구자들이 이 개념에 대한 효과적인 교수 방법을 제안하였으나, 체계적인 연구는 거의 이루어지지 않았다. 따라서 이 연구에서는 학생들이 입자 개념을 학습할 때 그림 그리기와 그림 분석하기 방법을 도입한 수업의 효과를 조사하였다. 서울시 남녀 공학 중학교 1학년 세 학급을 통제 집단과 그림 그리기 집단, 그림 분석하기 집단으로 선정하여 물질의 세 가지 상태와 분자의 운동 단원에 대하여 총 8차시 동안 수업을 실시하였다. 학생들의 시각적 학습양식에 따라 개념 이해도, 학업 성취도, 과학 학습 동기에 대한 교수 방법의 효과를 조사하였다. 연구 결과, 그리기 집단과 그림 분석하기 집단의 개념 이해도, 과학 학습 동기 점수가 통제 집단에 비해 높았다. 또한 시각적 학습양식 선호 학생들의 과학학습 동기 점수가 비선호 학생들보다 높았다.

• 터널과지하공간
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• 제20권2호
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• pp.119-124
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• 2010

암석의 인장강도에 미치는 변형률 속도 및 수분포화의 영향을 파악하기 위하여 건조상태 및 포화상태 3종류의 암석에 대해서 여러 가지 변형률 속도에서의 홉킨슨효과를 이용한 인장파괴실험을 실시하였다. 실험결과 건조상태뿐만 아니라 포화상태에서도 변형률 속도가 증가할수록 암석의 인장강도는 증가하였다. 특히, 건조 상태에 있어서 암석의 동적인장강도는 암석의 종류와는 상관없이 변형률 속도의 약 1/3승에 비례하는 경향을 나타내었다. 또한, 수분포화의 영향으로 공극률이 높은 사암과 응회암은 건조상태와 비교하여 인장강도가 감소하였으나, 공극률이 0.49%로 낮은 화강암은 건조상태와 포화상태와의 사이에 유의한 차이는 없었다.

• The Journal of Asian Finance, Economics and Business
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• 제7권2호
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• pp.9-20
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• 2020

The study investigates a recent surge of cash literature by using a sample of hospitality firms to gain a new understanding of corporate cash holdings. Past literature states that there is a substantial variation of liquidity across industry groups. Existing literature predominantly refers to US-listed firms and focus on either hotels or restaurants and not the hospitality industry as a whole. Therefore, we provide a comparative study of cash holdings behaviour between hospitality and non-hospitality firms from an emerging market context. Using a sample of public listed hospitality firms from 2002 to 2013, dynamic panel regression techniques are used to study the relationships between firm characteristics and cash levels. Also, the non-parametric Wilcoxon-Mann-Whitney test was carried out to examine the time and sectoral differences in cash holdings. In addition, the panel regression techniques are used to investigate the relationships between firm characteristics and level of corporate cash holdings. The results reveal that firm characteristics do matter in hospitality firms. We find that firm size, capital expenditures, and liquid assets substitutes are negatively related to cash level. The results support trade-off theory and the pecking order theory. This study incrementally explains the cash holdings behaviour of hospitality firms in emerging market.

• 한국항해학회지
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• 제16권2호
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• pp.41-52
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• 1992

It is, as everyone knows, very important for human beings to protect and conserve marine environment. We has believed the ocean is so wide and deep that it cannot be polluted. But it has begun to doubt the capacity of self-purification of the ocean due to pollution arising from marine casualities. It has proved that semi-enclosed sea is likely to be polluted and cannot be restored easily once pollution occurs. Therefore, first of all it is important to take preventive measures for prevention of marine pollution in the semi-enclosed sea like the Yellow Sea. Many of regional conventions for prevention of marine pollution have come into existence. this dissertation was set out for the fact that the Yellow Sea is semi-enclosed sea which is vulnerable to marine pollution. It is desirable not to deal with marine preservation of the Yellow Sea by a single exclusively but to deal with it by cooperation of all coastal states under the present circumstances. I proposed a program of regional cooperation to protect and conserve the Yellow Sea. This program must be progressed with gradual arrangements. First, they must establist a basic cooperation committee to work basic affairs on the protection of marine environment within the Yellow Sea. The Committee Mainly play parts of study and research concerned with pollution of the Yellow Sea in the non-governmental side and consist of legal and scientific experts. Second, they must establish the control Committee to prevent marine pollution of the Yellow Sea substantially. There is a reason that regional cooperation cannot be directly concluded with the regional tready. Because there is a problem of Recognition of States left. In principle, a subject of tready must be a state in the International Law. But they have not made Recognition of State which is demanded by International Law between North and South Koreas. Therefore, the Control committee must play a substantial part of prevention from pollution instead of the treaty. Finally, we concluded tentatively named $\ulcorner$Convention on Regional Cooperation for Protection of Marine Environment of the Yellow Sea from Pollution$\lrcorner$ if the matter is settled which is related to Recognition of States in the International Law.

• Journal of Animal Science and Technology
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• 제63권4호
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• pp.799-814
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• 2021

Information is lacking about the effect of date of a fall cut of alfalfa (Medicago sativa L.) on dry matter yield (DMY), forage nutritive value, and stands persistence. The objective of this study was to determine the effect of timing of a fall cut on DMY, forage nutritive value and stand persistence of three alfalfa varieties: low-lignin Hi-Gest 360, Roundup Ready Tonica, and conventional Gunner in Northeastern Kansas in the United States. The field study was carried out by splitting plot in randomized complete block design with four replications. The harvesting data of different maturity stages were collected in each year from 2015 to 2018. Three cuts were harvested based on the stage of maturity, and the last (fourth) cut was done on September 15, September 30, October 15, and October 30 of each year. The persistence of the alfalfa stands was determined each fall after the last cut, and each spring after the first cut, by counting the number of live plants in a randomly placed quadrat in each plot. Alfalfa cut on September 15 and September 30 had a higher stand persistence compared to alfalfa cut on October 15 and October 30. The DMY of the first cut in 2016 was significantly higher in roundup ready than the low-lignin alfalfa variety. In the second cut, DMY was significantly higher in conventional alfalfa than the roundup ready. There were no significant differences in DMY between alfalfa varieties in the rest of seasonal cuttings in 2016 and 2017 and annual total yield in both years. In general, low lignin alfalfa variety had higher crude protein and relative feed value and lower acid detergent fiber and neutral detergent fiber contents than those in roundup ready and conventional alfalfa varieties. On average, nutritive value of alfalfa was generally affected by last cutting dates in 2017. Based on 3-year data the last cutting of alfalfa in the fall could be done by September 30-October 15 without harmful effect on DMY.

• 한국산림과학회지
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• 제76권3호
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• pp.249-255
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• 1987

Forestry as with all land matters, under the Constitution, is a State matter. Thus the States, numbering 14, have considerable autonomy in decisions on forestry and related matters. However, the Federal Government, having jurisdiction over such issues as defence, education and research, endeavours to coordinate, standardise and advise the States on matters where the States have jurisdiction. However, forestry being a major revenue earner, is jealously guarded by the States. Under such circumstances and recognising the interdependencies of impacts of decisions at the State level, the institutional organisations play an important role in coordinating state activities to ensure that the benefits to the country as a whole are not sacrificed in favour of interests of individual state. Various legislative mechanisms have been established to ensure this coordinated effort. A National Forestry Council forms the apex of national political coordination. The Federal Forestry Department is responsible for coordination of developmental activities at the State level, which are implemented be the State Forestry Departments within Peninsular Malaysia. Research is carried out centrally by the Forest Research Institute of Malaysia(FRIM), a statutory body formed in 1985 from a research division of the Forestry Department. The Stares of Sabah and Sarawak have their own Forestry Departments, independent of the Federal Department, and each with its own research unit independent of FRIM. Tertiary education in forestry is the sole responsibility of the Agricultural University at Serdang with a campus for Diploma level training in Sarawak. In the developmental area in the State of Sabah, institutions have been formed to focus on specific areas of activities. The Sabah Foundation is responsible for the long term development of the State forests with a concession of about one million ha. Sabah Forest Development Authority(SAFODA) was formed to carry out reforestation of denuded areas. Sabah Forest Industries Ltd.(SFI) is responsible for the country's only integrated pulp and paper industry with its own afforestation program to support its resource supply. In Peninsular Malaysia various states have established State Corporations to manage large "sustained yield" concessions. While wildlife and state parks are managed by the respective forestry departments in Sabah and Sarawak, it is the responsibility of a separate department in Peninsula Malaysia called the Department of Wildlife and National Parks(under the Ministry of Science, Technology and Environment). Timber trade legislation and promotion in the Peninsular is the responsibility of the Malaysian Timber Industries Board(MTIB) for Peninsular Malaysia and the Sarawak Timber Industries Development Corporation(STIDC) in Sarawak. In the area of NGOs ; the Institute of Foresters Malaysia, is the professional body of forestry in the country. A Malaysian Forestry Society caters for the public participation and interest. Other environmentally related NGOs such as the Malayan Nature Society, the Environmental Protection Society, World Wildlife Fund, Friends of the Earth and the Consumers Associations also involve themselves in specific forestry activities. A number of timber trade associations are also formed by the private sector to assist the industries.