• Proceedings of the Korea Water Resources Association Conference
• /
• 2018.05a
• /
• pp.76-76
• /
• 2018

하천에서의 유사이송과 하상변동을 분석하는 대표적인 방법으로는 현장에서 유사량이나 하상고를 측정하여 분석하는 실측에 의한 방법, 수리모형 실험과 수치모형을 이용하는 방법이 있다. 이 중에서 실측에 의한 방법은 시간과 비용의 한계로 수치해석모형을 이용한 연구가 많이 이루어 지고 있다. 현재까지 개발된 다양한 하상변동 수치모형들은 유사이송 상태를 평형 유사이송 상태를 가정하고 개발되어 왔다. 평형 유사이송은 흐름과 하상재료 등의 조건이 발생시킬 수 있는 유사이송능력과 실제 유사이송률이 동일하다고 가정하는 것이다. 그러나, 실제 유사이송에서는 흐름 및 지형 등의 변화에 따라서 지속적으로 새롭게 형성되는 유사이송능력에 실제 유사이송률이 빠르게 도달하지 못하면서 유사이송능력과 유사이송률 사이에 시 공간의 격차가 발생하게 된다. 이러한 상황을 비평형 유사이송이라고 하며 지속적인 하상 상승 및 저하가 발생하는 구간, 댐과 같은 구조물에 의해서 유사의 연속성이 차단되는 구간, 하상재료가 불연속한 구간 등에서 주로 발생하는 것으로 알려져 있다. 비평형 유사이송을 수학적으로 모의하기 위한 대표적인 방법에는 적응거리계수와 회복계수를 이용하는 방법이 있다. 위의 계수들은 흐름 및 하상 특성을 이용하여 공간에 대한 유사이송의 지체현상을 고려하는 방법으로 이를 산정하기 위한 다양한 공식들이 제시되고 있다. 그러나, 각 공식들에 의해서 제시되는 값에 많은 차이가 있는 것으로 알려져 있다. 본 연구에서는 실내실험과 수치실험을 통해서 평형/비평형 유사이송 및 집중형/분포형 적응거리계수를 고려한 모의 결과를 비교하였으며, 적응거리계수 산정공식에 따른 비평형 유사이송 모의 결과를 비교하였다. 본 연구에서 적용한 실내실험에 대해서는 평형 유사이송보다는 비평형 유사이송을 고려한 경우와 비평형 유사이송 공식을 이용하여 적응거리계수를 분포형 매개변수로 이용하는 경우가 실제 하상변동 모의 결과에 더 근접한 수치실험 결과를 제공하는 것으로 나타났다.

• Journal of The Korean Association of Information Education
• /
• v.16 no.2
• /
• pp.173-180
• /
• 2012

This study looks for the requirements for adaptive courseware and provides background for developing effective adaptive courseware. Most adaptive courseware does not adequately reflect the requirements of learners. If it properly reflected learners' requirements well, it could be used more effectively. therefore, this study analyzes and suggests the requirements of an adaptive courseware for pre-service teachers who are majoring in computer education. The study methods were factor analysis and frequency analysis through survey. The results show that the important elements of an adaptive courseware are a learning style designed according to individual differences as well as an instruction model appropriate to the subject domain. The study examined adaption by learner level, by learning objective, by learning style, by method of learning content, and by learning history in that order. Therefore while the most of adaptive courseware support learning style; we propose that the adaptive courseware will support learning objects and instruction model as well.

• (The)Korea Educational Review
• /
• v.23 no.1
• /
• pp.205-230
• /
• 2017

Drawing on third to fifth wave data from the Longitudinal Study of North Korean Migrant Youths' Education, we examined the longitudinal relationship between social capital of North Korean Migrant Youths and school adjustment using latent growth modeling(LGM). Specifically, we sought to answer the following research questions: Do social capital and school adjustment among North Korean Migrant Youths change over time? Is there a relationship between the changes in social capital and school adjustment among these students? Our LGM results showed that trends in social capital and school adjustment among these students were not fixed but changed over time. While the social capital developed by these students was found to influence school adjustment at the time of its development, it did not continue to influence changes in school adjustment over time. Changes in school adjustment of North Korean migrant youths were affected by changes in social capital. These results suggest that there is room for gradual improvement of school adjustment level by strengthening social capital of North Korean migrant youths.

• Journal of Korean Society of Transportation
• /
• v.22 no.4 s.75
• /
• pp.159-173
• /
• 2004

This study utilizes the fuzzy logic and genetic algorithm to improve the existing incident detection models by addressing the problems associated with "crisp" thresholds and model transferability (applicability). The model's major components were designed to be a set of the fuzzy inference engines, and for the self-adaptation capability the genetic algorithm was introduced in optimization(or training) of the fuzzy membership functions. This approach is often called "the hybrid of fuzzy-genetic algorithm" The model performance was tested and found to be compatible with that of the existing well-recognized models in terms of performance measures such as detection rate, false alarm rate, and detection time. This study was not an effort for simple improvement of the model performance, but an experimental attempt to incorporate new characteristics essential for the incident detection model to be universally applicable for various roadway and traffic conditions. The study results prove that the initial objective of the study was satisfied, and suggest a direction that the future research work in this area must follow.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2003.05a
• /
• pp.307-310
• /
• 2003

본 논문에서는 대표적인 비선형 동특성을 가지는 실제 헬리콥터의 회전 띤 자세 운동을 근사화한 모형 헬리콥터의 시스템을 소개하고 이 시스템의 정지 자세 제어를 목표로 직접 적응 웨이브렛 신경회로망 제어기를 다음의 과정에 의해 만든다. 우선 상태 공간에 적용할 웨이브렛 기준 함수를 정의하고 나서 제어기로 들어오는 입력 값의 대략적인 범위와 특성을 파악해서 웨이브렛 이론에 근거해 신축(dilation)과 이동(traslation) 변수 값을 선택하여 초기 적응 웨이브렛 신경회로망 제어기를 건설한다. 마지막으로 시스템의 안정화 제어를 위하여 선택, 교배, 돌연변이의 진화연산자에 의해 일시에 최적의 구조와 결합가중치로 진화시켜 가는 새로운 형태의 ENNC를 제안하여 연결 가중치(weight)를 조정한다. 이 직접 적응 웨이브렛 신경회로망 제어기를 비선형 시스템인 모형 헬리콥터 시뮬레이터에 적용하여 제안한 제어기의 견실성 및 그 우수성을 입증하고자 한다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.13 no.1
• /
• pp.119-127
• /
• 1999

In this paper, a robust direct adaptive contrdler is presented in a linear time-invariant. Continuous systems with unmodeded dynamics and bounded disturbance using a rmdified control law and the adaptive law to Compensate for the drawback of ${\sigma}$-modification algorithm. The proposed algorithm is awlied to a plant with unrmdeled dynamics represented as a singular perturbation. Boundness of all signals in overall system is guaranteed with mathematical analysis. simulation results are presented the effectiveness foc the first-order plant even in the presence of unmodelled dynamics or bounded disturbance simulatneousIy.eousIy.

• Korean Journal of Culture and Social Issue
• /
• v.28 no.3
• /
• pp.331-352
• /
• 2022

This study used a latent growth curve models(LGCM) to examine longitudinal changes in youth's game usage, self-control and the longitudinal mediation effect of adaptive game use in the relationship between game usage and self-control. A four-year longitudinal data of 863 adolescents from the Game User Panel Survey, provided through participation in the 2019 Game User Panel Research Conference hosted by the Korea Creative Contents Agency, was used to verify the longitudinal mediation effect of adaptive game use. SPSS 21 was used to verify the normality of variables from each wave, and to conduct correlation analysis. Mplus 6.12 was used to verify the longitudinal mediation effect. The results are as follows. First, game usage, self-control and adaptive game yielded linear temporal growth. Second, latent growth curve models showed that the direct effect of game usage on self-control was insignificant, but game usage had a significant indirect effect on self-control through adaptive game use. Continuous adaptive gaming increased self-control. Third, sobel test results showed that both the initial value and change rate of adaptive game use had a full-mediation effect, confirming the longitudinal mediation effect. This study verified the longitudinal change of self-control affected by change in game usage and adaptive game use.

• Korean Journal of Remote Sensing
• /
• v.25 no.2
• /
• pp.95-105
• /
• 2009

Irregular temporal sampling is a common feature of geophysical and biological time series in remote sensing. This study proposes an on-line system for reconstructing observation image series including bad or missing observation that result from mechanical problems or sensing environmental condition. The surface parameters associated with the land are usually dependent on the climate, and many physical processes that are displayed in the image sensed from the land then exhibit temporal variation with seasonal periodicity. An adaptive feedback system proposed in this study reconstructs a sequence of images remotely sensed from the land surface having the physical processes with seasonal periodicity. The harmonic model is used to track seasonal variation through time, and a Gibbs random field (GRF) is used to represent the spatial dependency of digital image processes. In this study, the Normalized Difference Vegetation Index (NDVI) image was computed for one week composites of the Advanced Very High Resolution Radiometer (AVHRR) imagery over the Korean peninsula, and the adaptive reconstruction of harmonic model was then applied to the NDVI time series from 1996 to 2000 for tracking changes on the ground vegetation. The results show that the adaptive approach is potentially very effective for continuously monitoring changes on near-real time.

• Journal of the Korean Geographical Society
• /
• v.43 no.1
• /
• pp.104-116
• /
• 2008

Overheated speculation areas which have high potential of becoming speculative are the target of many real estate policies. This paper proposes a model for spatial patterns of house price volatility and suggests a spatial pattern of overheated speculation areas. House prices are determined by economic behaviors of sellers and buyers who have rational or adaptive expectations. Spatial patterns of house price volatility are formed by tendencies of their economic behavior. If there is a majority of adaptive sellers and buyers in an area, it may appear as a "hotspot" by showing high volatility of house prices and simultaneous price increases. Overheated speculation areas are formed by adaptive sellers and buyers who want to realize maximum expectation profit, therefore these areas patterns are defined as hotspot patterns of price volatility.

• Journal of the Korean Data and Information Science Society
• /
• v.26 no.6
• /
• pp.1439-1452
• /
• 2015

Purpose: The purpose of this study was to construct a SEM that would further explain the college adaptation for nursing students. Methods: Model construction was based on the variables; mother attachment, self concept, stress, stress of clinical practice, psychological well-being, coping, and college adaptation. The analysis of data was done with both SPSS 20.0 for descriptive statistics and AMOS 20.0 for SEM. Results: The psychological well-being and coping was found to have a significantly direct effect in predicting college adaptation. In addition, mother attachment, self concept, and stress were found to have a significantly direct effect in predicting college adaptation. The final modified model yielded ${\chi}^2=231.1$ (p <.001), ${\chi}^2/df=2.36$, GFI=.91, AGFI=.86, NFI=.91, PNFI=.73 RMSEA=.07, and CFI=.95. Conclusion: To improve adjustment to college life, it is recommended to have a direct method of developing psychological well-being and coping improvement program to improve mother attachment.