• 한국과학교육학회지
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• 제29권7호
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• pp.759-766
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• 2009

This study was conducted to examine 10 Belizean teachers' conceptions about the causes of seasonal change. This research was conducted with an integrated method using a open ended written test and an interview which included a drawing. There are four categories, explained by the teachers, as the causes of seasonal changes. They are; climate, rotation of the earth on its axis, revolution of the earth around the sun, and the tilting of earth's axis as it revolves. Most teachers misunderstood that the first of three categories was responsible for seasonal change. Second, it is more effective to use the integrated method shown in this research than to use only a written test when seriously investigating the causes and understanding of seasonal change. Third, 8 out of 10 teachers could not correctly explain the causes of seasonal change. The reasons for seasonal change seemed to be hard for the informants to understand even though it was taught in elementary, middle, high school, and college elective classes.

• 대한지구과학교육학회지
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• 제7권1호
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• pp.43-53
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• 2014

이 연구의 목적은 계절의 변화 원인을 설명하는 과정에서 초등학생들의 개념 시뮬레이션을 분석함으로써 학생들이 어떻게 계절의 변화 원인에 대한 설명을 어떻게 생성하고 있는지를 알아보고, 계절의 변화와 관련된 교육에 시사점을 주는 데 있다. 이를 위해 문헌 연구를 기반으로 개념 시뮬레이션 과정 및 전략 분석틀을 개발하였으며, 과학교육 전문가 4인의 내용타당도를 확인 받았다. 연구의 결과는 다음과 같다. 첫째, 계절의 변화 원인 설명 과정에서 초등학생들은 주로 과학수업에서 모형 실험을 통해 학습한 지각적 경험을 이용하여 설명을 만들고 있었으며, 친숙한 대상을 이용하여 사고실험 사례를 고안하거나, 친숙한 지각적 경험을 유추하여 설명을 확고히 하는 것을 돕고 있었다. 둘째, 개념 시뮬레이션 사례의 실수는 초기표상의 진술, 심상 시뮬레이션의 실행 과정에서 나타났으며, 참여자들의 초기표상 진술이 불완전하거나, 심상 시뮬레이션 실행에서 부적절한 상황을 떠올린 경우였다. 셋째, 초등학생들의 개념 시뮬레이션 과정에서 남중고도의 개념과 관련된 정신모델을 확고히 하기 위해 제거, 대체의 시뮬레이션 전략을 사용하는 것을 확인하였다.

• 통합자연과학논문집
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• 제14권2호
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• pp.41-49
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• 2021

The causes of climate change are natural and artificial. Natural causes include changes in temperature and sunspot activities caused by changes in solar radiation due to large-scale volcanic activities, while artificial causes include increased greenhouse gas concentrations and land use changes. Studies have shown that excessive carbon use among artificial causes has accelerated global warming. Climate change is rapidly under way because of this. Due to climate change, the frequency and cycle of infectious disease viruses are greater and faster than before. Currently, the world is suffering greatly from coronavirus infection-19 (COVID-19). Korea is no exception. The first confirmed case occurred on January 20, 2020, and the number of infected people has steadily increased due to several waves since then, and many confirmed cases are occurring in 2021. In this study, we conduct a study on climate change before and after COVID-19 using weather data from Korea to determine whether climate change affects infectious disease viruses through logistic regression analysis. Based on this, we want to classify before and after COVID-19 through a logistic regression model to see how much classification rate we have. In addition, we compare monthly classification rates to see if there are seasonal classification differences.

• 대한지구과학교육학회지
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• 제15권2호
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• pp.249-262
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• 2022

본 연구는 초등예비교사들의 계절변화에 대한 대안 개념에 대한 연구로 2021년 5월부터 2022년 6월까지 P교육대학교 초등예비교사 60명을 대상으로 수행되었다. 본 연구의 결론은 다음과 같다. 첫째, 초등예비교사들은 계절변화 원인을 설명하는데 60명의 초등예비교사 중에서 22명(36%)만이 과학적 개념을 가지고 있었고, 나머지 38명(64%)의 학생들이 대안개념을 가지고 있었다. 둘째, 초등예비교사들은 지구의 자전축의 경사가 어떻게 계절변화를 일으키는데 관련되어 있는가를 설명하는데 있어서 60명의 초등예비교사 중에서 16명(27%)만이 과학적 개념을 가지고 있었고, 나머지 44명(73%)은 대안개념을 가지고 있었다. 셋째, 초등예비교사들은 태양의 남중고도의 변화와 계절변화와의 관련성을 설명하는데 초등예비교사 60명 중에서 12명(20%)이 과학적 개념을 가지고 있었고, 나머지 48명(80%)가 대안개념을 가지고 있었다. 넷째, 계절변화에 대한 초등예비교사들이 대안개념의 종합적인 유형을 살펴보면 계절변화의 원인을 전체적으로 과학개념을 사용하여 설명하는 유형으로 분류되는 aS-bS-cS 유형은 60명의 초등예비교사 중에서 8명(13%)에 불과했으며, 나머지 52명(87%)는 계절변화를 설명하는데 모두 하나 이상의 대안 개념을 소지하고 있었다. 이상에서 살펴 본 결과 초등예비교사들은 계절변화의 원인에 대한 일반적 개념, 자전축의 경사와 계절변화, 남중고도의 변화에 따른 계절변화를 설명할 때 다양한 대안개념을 사용하고 있다고 판단된다.

• 한국과학교육학회지
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• 제33권5호
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• pp.893-910
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• 2013

이 연구의 목적은 계절 변화의 원인에 대한 초등학생의 멘탈 모델의 변화 과정을 파악하는 것이다. 미시 발생적 연구 방법을 사용하여 총 8회기 동안 초등학교 6학년생 8명에게 계절 변화의 원인을 그림과 글, 사고 발성을 통해 설명하게 함으로써 멘탈 모델의 변화를 파악하였다. 연구 진행 시 연구 참여자의 언어적, 행동적 요소 및 면담 내용을 모두 비디오 녹화하였으며, 연구자의 현장 관찰 기록지와 학생이 작성한 멘탈 모델 기록지 등 다각적 자료를 함께 수집하였다. 수집한 결과를 통합하여 프로토콜을 작성하고, 이를 반복적으로 읽으며 귀납적으로 범주화하였다. 연구 결과는 다음과 같다. 첫째, 계절 변화의 원인에 대한 학습자의 멘탈 모델은 회기 내 및 회기 간에 걸쳐 개인마다 다양한 경로로 변화하였으며, 다양한 변화를 일으킨 학습자의 멘탈 모델이 과학적 모델에 더 근접하였다. 또한 자전이나 공전처럼, 계절의 변화와 관련된 선행 지식이 바르게 정착된 학생들은 새로운 정보에 기초하여 과학적 개념과 일치하는 멘탈 모델을 형성하였다. 반면에, 선행 지식이 바르게 정착되지 않은 경우에는 변형된 멘탈 모델에서 벗어나지 못하였다. 둘째, 멘탈 모델이 변화하는 데에는 학습자의 선행지식과 경험 및 정보, 선행 지식의 정확성, 새로운 지식과 기존 멘탈 모델 사이의 불일치 해결, 모형 조작을 통한 멘탈 모델 활성화, 그림으로 그려보기와 같은 요인들이 영향을 미쳤다. 교사는 학습자의 과학적 개념 형성을 위하여 그들에게 다양한 멘탈 모델을 구성할 수 있는 경험을 충분히 제공하고, 기존 멘탈 모델과 불일치하는 새로운 수업자료 제시를 통해 학습자가 의문을 느끼게 하고, 이를 해결하도록 할 필요가 있다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2021년도 학술발표회
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• pp.372-372
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• 2021

The agriculture sector plays a vital role in the economy of Pakistan by contributing about 20% of the GDP and 42% of the labor force. Rivers from the top of Himalayas are the major water resources for this agriculture sector. Recent reports have found that Pakistan is one of the most vulnerable country to climate change that can cause water scarcity which is a big challenge to the communities. Previous studies have investigated the impact of climate change on the trend of streamflow, but the understanding of seasonal change in the regional hydrologic regimes remained limited. Therefore, a better understanding of the seasonal hydrologic change will help cope with the future water scarcity issue. In this study, we used the daily stream flow data for four major river basins of Pakistan (Chenab, Indus, Jhelum and Kabul) over 1962 - 2019. Utilizing these daily river discharge data, we calculated the winter-spring center time and the summer-autumn center times. In this study Winter-spring center time (WSCT) is defined as the day of the calendar year during which half of the total six months (Jan-Jun) discharge volume was exceeded. Results show that the four river basins experienced a statistically significant decreasing trend of WSCT, that is the center time keeps coming earlier compared to the past. We further used the Climate Research Unit (CRU) climate data comprising of the average temperature and precipitation for the four basins and found that the increasing average temperature value causes the early melting of the snow covers and glaciers that resulted in the decreasing of 1^st center time value by 4 to 8 days. The findings of this study informs an alarming situation for the agriculture sector specifically.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
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• pp.188-191
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• 2008

The Tonle Sap, Cambodia, is a huge lake and periodically flooded due to monsoon climate. The incoming water causes intensive flooding that expands the lake over vast floodplain and wetland consisting mainly of forests and shrubs. Monitoring the water-level change over the floodplain is essential for flood prediction and water resource management. A main objective of this study is flood monitoring over Tonle Sap area using ALOS PALSAR. To study double-bounce effects in the lake, backscattering effect using ALOS PALSAR dual-polarization (HH, HV) data was examined. InSAR technique was applied for detection of water-level change. HH-polarization interferometric pairs between wet and dry seasons were best to measure water level change around northwestern parts of Tonle Sap. The seasonal pattern of water-level variations in Tonle Sap studied by InSAR method is similar to the past and altimeter data. However, water level variation measured by SAR was much smaller than that by altimeter because the DInSAR measurement only represents water level change at a given region of floodplain while altimeter provides water level variation at the central parts of the lake.

• 한국농공학회논문집
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• 제61권1호
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• pp.21-29
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• 2019

This study analyzed the variability of drought risk based on trend analysis of dry-seasonal dam inflow located in upper river basins. To this, we used areal averaged precipitation and dam inflow of three upper river dams such as Soyang dam, Chungju dam, and Andong dam. We employed Mann-Kendall trend analysis and change point detection method to identify the significant trends and changing point in time series. Our results showed that significant decreasing trends (95% confidence interval) in dry-seasonal runoff rates (= dam inflow/precipitation) in three-dam basins. We investigated potential causes of decreasing runoff rates trends using changes in potential evapotranspiration (PET) and precipitation indices. However, there were no clear relation among changes in runoff rates, PET, and precipitation indices. Runoff rate reduction in the three dams may increase the risk of dam operational management and long-term water resource planning. Therefore, it will be necessary to perform a multilateral analysis to better understand decreasing runoff rates.

• 생태와환경
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• 제38권4호통권114호
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• pp.439-444
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• 2005

The environmental quality of the middle-reach of the Yahagi River has deteriorated in recent years. The nutrient dynamics within the reach were investigated to explain the changes. Seasonal pattern of $NO_3\;^--N$ concentration tended to stay low from April or May through July or August and then increased till winter or early spring, although there were peaks during high flow periods in mid-September, 2000 and late-August, 2001. No clear seasonal changes were observed in $PO_4\;^{3-}-P$ concentration. In the bimonthly records from 1980-2002, the DIN concentrations on January and March were higher than other months whereas the average daily flows on January and March were lower than they were in other months. The mean DIN concentration showed a high negative correlation with the median of average daily flow. In the past 50 years, the average concentration of DIN (excluding nitrite) was 0.21 mg $L^{-1}$ in 1952-1953. The concentration was about twice this high around 1980, and it is about three times this high at present. On the other hand, the average concentration of $PO_4\;^{3-}-P$ was below the limit of detection in 1952-53. However, it increased to almost 0.03 mg $L^{-1}$ around 1980, then decreased to approximately 0.016mg $L^{-1}$ at present. Our results suggest that the increasing DIN concentration is one of the causes of environmental change in the Yahagi River. We conclude that controlling the DIN concentration is essential for improving the river environment.

• KIEAE Journal
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• 제16권3호
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• pp.25-34
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• 2016

Purpose: The temperature in Seoul has risen 3 times more than the average global temperature increase for the past 100 years. Today, summer starts 15 days earlier than the early 20th century and is 32 days longer. This tendency causes rapid increase of cooling energy demand. Following this effect, seawater heat resources are to be used as an countermeasure for global warming. Incheon Port near the Western Sea has the lowest water temperature in the winter in South Korea in which it is suitable to use seawater cold heat resources. Method: The cold heat resource is gained from seawater when the water temperature is the lowest in the winter time and saved in a seasonal thermal storage. This can be used as cold heat resource in the summer time. A heat exchanger is essential to gain seawater cold energy. Due to this necessity, sea water heat resource heat exchangers are modeled by heat transfer equations and the fluid characteristics are analyzed. Also, a CFD (computational fluid dynamics) program is used to conduct simulation on the fluid characteristics of heat exchangers. The analyzed data of deducted from this process are comprehensively analyzed and discussed. Result: Regarding the performance of the heat exchanger, the heat exchanger was operated following the prediction within the range of heat transfer rate of minimum 3.3KW to maximum 33.6KW per device. In the temperature change analysis of the heat exchanger, fluid analysis by heat transfer equations almost corresponded to the temperature change by CFD simulation. Therefore, it is considered that the results of this study can be used as design data of heat exchangers.