• 한국산림과학회지
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• 제90권2호
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• pp.217-226
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• 2001

이 연구는 건축허가면적의 변화가 임산물수입량에 마치는 영향을 우리나라 시장을 대상으로 분석하였다. 첫번째 목적은 건축허가면적의 변화가 임산물수입량 변화의 원인이 되는지, 즉 인과관계를 파악하는 것이고, 두번째 목적은 건축허가면적의 변화가 임산물수입량에 얼마만큼 얼마동안 영향을 미치는지, 즉 동태적 영향을 추정하는 것이다. 건축허가면적과 임산물수입량의 관계는 자기회귀모형이나 오차수정모형에 의해 만들어졌다. 인과관계 파악은 Granger가 고안한 인과성검정을 이용하였고, 동태분석은 분산분해분석과 충격반응분석을 이용하였다. 결과에 의하면 건축허가면적의 변화는 임산물 중에서 고밀도섬유판수입량 변화의 원인이 되었다. 고밀도섬유판의 경우에 어느 시기의 수입량은 그 시기 이전의 건축허가면적에 의해 10%, 그 시기 이전의 수입량에 의해 90% 가량 설명되었다. 또한 건축허가면적의 변화는 고밀도섬유판수입량에 6개월까지 영향을 미쳤다. 즉 건축허가면적의 변화가 고밀도섬유판수입량에 영향을 미쳤더라도 단기간에 불과했다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2011년도 학술발표회
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• pp.18-18
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• 2011

Climate change is impacting and will increasingly impact both the quantity and quality of the world's water resources in a variety of ways. In some areas warming climate results in increased rainfall, surface runoff, and groundwater recharge while in others there may be declines in all of these. Water quality is described by a number of variables. Some are directly impacted by climate change. Temperature is an obvious example. Notably, increased atmospheric concentrations of $CO_2$ triggering climate change increase the $CO_2$ dissolving into water. This has manifold consequences including decreased pH and increased alkalinity, with resultant increases in dissolved concentrations of the minerals in geologic materials contacted by such water. Climate change is also expected to increase the number and intensity of extreme climate events, with related hydrologic changes. A simple framework has been developed in New Zealand for assessing and predicting climate change impacts on water resources. Assessment is largely based on trend analysis of historic data using the non-parametric Mann-Kendall method. Trend analysis requires long-term, regular monitoring data for both climate and hydrologic variables. Data quality is of primary importance and data gaps must be avoided. Quantitative prediction of climate change impacts on the quantity of water resources can be accomplished by computer modelling. This requires the serial coupling of various models. For example, regional downscaling of results from a world-wide general circulation model (GCM) can be used to forecast temperatures and precipitation for various emissions scenarios in specific catchments. Mechanistic or artificial intelligence modelling can then be used with these inputs to simulate climate change impacts over time, such as changes in streamflow, groundwater-surface water interactions, and changes in groundwater levels. The Waimea Plains catchment in New Zealand was selected for a test application of these assessment and prediction methods. This catchment is predicted to undergo relatively minor impacts due to climate change. All available climate and hydrologic databases were obtained and analyzed. These included climate (temperature, precipitation, solar radiation and sunshine hours, evapotranspiration, humidity, and cloud cover) and hydrologic (streamflow and quality and groundwater levels and quality) records. Results varied but there were indications of atmospheric temperature increasing, rainfall decreasing, streamflow decreasing, and groundwater level decreasing trends. Artificial intelligence modelling was applied to predict water usage, rainfall recharge of groundwater, and upstream flow for two regionally downscaled climate change scenarios (A1B and A2). The AI methods used were multi-layer perceptron (MLP) with extended Kalman filtering (EKF), genetic programming (GP), and a dynamic neuro-fuzzy local modelling system (DNFLMS), respectively. These were then used as inputs to a mechanistic groundwater flow-surface water interaction model (MODFLOW). A DNFLMS was also used to simulate downstream flow and groundwater levels for comparison with MODFLOW outputs. MODFLOW and DNFLMS outputs were consistent. They indicated declines in streamflow on the order of 21 to 23% for MODFLOW and DNFLMS (A1B scenario), respectively, and 27% in both cases for the A2 scenario under severe drought conditions by 2058-2059, with little if any change in groundwater levels.

• 한국산림과학회지
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• 제90권5호
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• pp.663-671
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• 2001

이 연구는 이자율의 변화가 임산물수입량에 미치는 영향을 우리나라 시장을 대상으로 분석하였다. 첫번째 목적은 이자율의 변화가 임산물수입량 변화의 원인이 되는지, 즉 인과관계를 파악하는 것이고, 두번째 목적은 이자율의 변화가 임산물수입량에 얼마만큼 얼마동안 영향을 미치는지, 즉 동태적 영향을 추정하는 것이다. 이자율과 임산물수입량의 관계는 자기회귀모형에 의해 만들어졌다. 인과관계 파악은 인과성검정을 이용하였고, 동태분석은 분산분해분석과 충격반응분석을 이용하였다. 결과에 의하면 이자율의 변화는 임산물 중에서 합판수입량 변화의 원인이 되었다. 합판의 경우에 어느 시기의 수입량은 그 시기 이전의 이자율에 의해 20%, 그 시기 이전의 수입량에 의해 80% 가량 설명되었다. 또한 이자율의 변화는 합판수입량에 6개월까지 영향을 미쳤다. 즉 이자율의 변화가 합판수입량에 영향을 미쳤더라도 단기간에 불과했다.

• 대한수학교육학회지:학교수학
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• 제4권3호
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• pp.495-511
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• 2002

In this paper, we deal with the teaching of parameter in the school mathematics. The roles of letters become different according to the letters-used context. That is, the meaning of letters may change in the course of being used. But specifying the roles of letters without understanding the distinction between the roles is not enough for students to learn the meaning of variables, specifically that of parameters. Therefore, the parameter-learning should focus on the dynamic change of roles. That implies flexible thinking and changing of perspectives.

• 한국응급구조학회지
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• 제28권1호
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• pp.21-34
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• 2024

Purpose: This study aimed to observe change in factors over time in the first cohort of the 2018 Children and Adolescent Panel Middle School. In addition, this study attempted to examine the causal relationship and influence between variables by setting a time gap between independent and dependent variables. Methods: Frequency and descriptive statistical analyses were conducted to determine the general characteristics of the study participants. Hierarchical regression analysis was conducted to analyze the effects of smartphone dependence on health, sleep quality, and depression. After inputting the control variables (Model 2), the influence of the variables was identified based on the input model. Results: Smartphone dependence positively impacted depression in both male and female students and negatively impacted sleep and health. Conclusion: Smartphones are closely associated with teenagers' lives. Additionally, as adolescents experience various psychological anxieties owing to rapid physical changes, there are concerns that psychological dependence may increase, considering that adolescence is the most emotionally unstable period. Therefore, the results of this study consistently prove that smartphone dependence has a causal relationship with emotion-related variables, such as emotional stress, depression, and anxiety.

• 한국과학교육학회지
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• 제21권4호
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• pp.658-667
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• 2001

본 연구에서는 학습자의 인지적 정의적 변인, 변칙 사례에 의한 인지 갈등, 개념 변화 사이의 관계에 대해 조사하였다. 배경 지식, 장의존성 독립성 학습 전략, 논리적 사고력, 목표 지향, 선개념 및 능력에 대한 자아효능감, 통제 신념 등을 조사하였고, 선개념 검사, 변칙 사례에 대한 반응 검사, 직후 개념 및 개념 파지 검사를 실시하였다. 학습자의 인지적 정의적 변인과 변칙 사례에 의한 인지 갈등 사이에는 유의미한 상관이 없었다. 분자 운동에 대한 배경 지식, 장의존성, 독립성, 학습 전략은 학생들의 직후 개념 및 개념 파지와 유의미한 상관이 있었으며, 논리적 사고력과 직후 개념의 상관이 유의미하였다. 중다 회귀 분석 결과, 학습 전략이 학생들의 직후 개념과 개념 파지를 유의미하게 예측하였다. 정의적 변인의 경우, 능력에 대한 자아효능감은 직후 개념 및 개념 파지와, 목표지향은 직후 개념과 유의미한 상관이 있었다. 능력에 대한 자아효능감은 직후 개념과 개념 파지에 대한 유의미한 예언 변인이었으며, 목표 지향은 직후 개념에 대한 유의미한 예측 변인이었다.

• 한국환경과학회지
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• 제8권4호
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• pp.533-538
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• 1999

Fuzzy algorithm of automatic control for dissolved oxygen(DO) concentration in the aeration tank of an activated sludge process is proposed. Among variables repirometry and air flowrate are selected as significant input factors and the relationship with DO is estimated using a multiple regression model. The DO concentration and the amount of repirometry are fuzzified and the fuzzy rule base are determined. Using the fuzzy algorithm, the change of amount of air flowrate are determined and the change of amount of DO is derived.

• Journal of Electrical Engineering and information Science
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• 제1권2호
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• pp.101-108
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• 1996

A new speed controller based on the fuzzy algorithm with hierarchical structure is presented. The input variables of the controller are speed error and its derivative(change of error), where the output variable is the change of torque current command. Several comparisons were performed with conventional PI (proportional plus integral) controller and proposed controller. These controllers are applied to the laboratory model drive system with 2.2kW induction motor. Some simulation and experimental results show that the speed controller using fuzzy algorithm is more robust than the conventional PI controller.

• Journal of the Korean Data and Information Science Society
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• 제18권2호
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• pp.345-356
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• 2007

This study deals with an early detection problem of structural change in won/dollar exchange market. A CUSUM algorithm is developed to monitor relevant economic variables indicating structural change in won/dollar exchange market. We applied the CUSUM algorithm to examine whether or not it was possible to alarm the 1997 economic crisis of Korea in advance.

• 한국운동역학회지
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• 제17권1호
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• pp.17-27
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• 2007

It is essential for gait analysis to know the distance information. The purpose of this study was to investigate the effects of start and finish distance on the gait variable during walking. Six adolescent participated in this study. Start condition was given by six conditions.: walking forward from (1) one step, (2) three steps, (3) five steps, (4) ten steps, (5) one step after standing walk, and (6) three steps after standing walk, before contacting the force plate. Stop condition was given by four conditions. : stop after (1) one step, (2) two steps, (3) three steps, and (4) ten steps, passing force plate. Repeated measured one-way ANOVA was utilized for data analysis, and the significant level was set at .05. The largest change from the difference of gait velocity exists between the variables of ground reaction force. There were no significant differences in spatio-temporal and posture(angle) variables, as well as ground reaction force variables with walking over the three steps. There were significant differences in gait velocity, knee angle at heel contact, vertical impulse and ankle angle at toe off in short distance.