• Journal of The Korean Association of Information Education
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• v.18 no.4
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• pp.559-566
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• 2014

This is to understand the neurological dynamic cognitive processes of math learning based on the abstract mappings( level A2), abstract systems(level A3), and single principles(level A4), which are principles of Fischer's cognitive development theory. Math learning requires flexibility to adapt existing brain function in selecting new neurophysiological activities to learn desired knowledge. This study suggests a general statistical framework for the identification of neurological patterns in different abstract learning change with optimal support. We expected that functional brain networks derived from a simple math learning would change dynamically during the supportive learning associated with different abstract levels. Task based patterns of the brain structure and function on representations of underlying connectivity suggests the possible prediction for the success of the supportive learning.

• Journal of Korean Society of Steel Construction
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• v.18 no.1
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• pp.113-122
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• 2006

The purpose of this paper is to evaluate the fire resistance of the TSC beam, a composite beam composed of a concrete beam enclosed by steel plates. Since a discrepancy was observed between the structural mechanisms of TSC and typical composite beams, the fire performances of the two beams are likewise believed to be partially dissimilar. In this experiment, small and medium-sized TSC beams were tested under given conditions in the laboratory, with/without one of the most widely used spray-on fire protections in Korea. Furthermore, based on the steel and concrete properties under elevated temperatures that were obtained from Eurocode, temperature development across the section was suggested, analyses. To determine the capacity of a modified plastic section, th e fire performance of the model was also examined.

• The KIPS Transactions:PartC
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• v.13C no.6 s.109
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• pp.749-756
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• 2006

Broadcast nature of wireless medium and path-loss reduction create a favourable condition for collaborative communications (CC) among single-antenna users to gain the powerful benefits of multi-antenna system without the demand for physical arrays. This paper proposes a CC strategy adapting to the propagation environment changes by optimizing the transmit signal amplification factors to simplify the structure of maximum likelihood (ML) detector and to obtain the minimum error probability as well. The closed-form BER expression was also derived and compared to the simulation results to evaluate the performance of the suggested solution. A variety of numerical results revealed the cooperation significantly outperforms non-cooperative counterpart under flat Rayleigh fading channel plus AWGN (Additive White Gaussian Noise).

• Proceedings of the Korea Information Processing Society Conference
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• 2004.05a
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• pp.741-744
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• 2004

본 연구는 손의 형상을 복잡한 배경환경에서 손 영역을 안정적으로 검출, 인식하여 윈도우 플레이어의 기능을 제어하는 시스템을 제안하였다. 손은 형상이 매우 복잡하기 때문에 2차원 형상의 불변량에 해당하는 에지의 방향성 히스토그램을 이용하여 인식을 행한다. 이 방법은 복잡한 배경에서 피부색을 지닌 손 영역이 정확히 추출되며 손 형상을 인식하는데 있어서 수행속도가 빠르고 조명변화에 덜 민감하기 때문에 실시간 손 형상 인식에 적합하다. 본 논문에서 제안한 방법을 윈도우 플레이어 제어에 적용한 결과 안정적으로 제어 할 수 있었다.

• Communications of Mathematical Education
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• v.37 no.1
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• pp.85-104
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• 2023

The purpose of this study is to analyze the types of mathematics journals of elementary school students and to understand how they change in mathematics journals as the grade goes up, and to obtain implications in mathematics education. To this end, 170 of the 222 parish mathematics data submitted to the "Math Journal Contest" were analyzed with the consent of both minors and their parents. As for the framework for analyzing math journal types, 12 types were derived through independent analysis between three researchers. The research results showed that first, the type of math journal written by elementary school students is a variety of journals, such as observation, problem making, concept organization, and review. In addition, as a learning area, it was found that math journal showed a noticeable increase in experimental observation, problem making, and concept journal as the grades progressed, while a small number of idea journal and explanatory journals appeared. However, game (winning) strategy building and types declined. It can be seen that this is evolving from a type that requires activity-oriented or simple descriptions to a type that actively applies mathematical concepts. As such, there are 12-type of math journals, but it is necessary to actively use the teaching materials in writing that can be freely expressed in the school setting.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.1
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• pp.79-89
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• 2006

Particularly the photovoltaic systems are preferred because the output is extracted to the useful electric energy. However, the output characteristics of photovoltaic(PV) systems using solar cell or array depend on the weather conditions. The assistant equipment which emulates the solar cell characteristics that can be controlled arbitrarily by researcher is required to the researchers for reliable experimental data. To solve these problems, it is necessary to research a solar cell model of which output characteristics varied by setting the weather conditions such as insolation levels and temperatures. Therefore, this paper was presented that improved model which is based on interpolation model. To verified the improved model, it is confirmed using the simulation of MATLAB. Also, the experiment was performed by the characteristics of virtual implemented solar cell(VISC) system with the proposed solar cell model. It could be confirmed that there exists actual ewer within 5% between actual solar cell and VISC system.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.984-984
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• 2012

지구온난화와 기후변화의 영향으로 전 지구적으로 이상홍수, 이상가뭄, 한파와 같은 이상기상 현상이 빈번하게 발생하고 있다. 국내에서는 2010년 추석 광화문 침수사태와 2011년 우면산 산사태와 같은 국지성 집중호우로 인한 인적 물적 피해가 속출하고 있다. 전통적으로 시기나 양적인 측면에서 대부분 장마기간에 국한되었던 강우집중현상이 과거와 달리 특정기간에 상관없이 발생하고 단기성, 국지성을 지닌 호우의 발생빈도가 높아지는 등 국내 강우의 특성이 변하고 있다. 이러한 변화에 대응하기 위해서 강우예측과 유출량예측의 정확도를 높이기 위한 시도가 다양하게 이루어지고 있다. 강우예측의 정확성을 높이기 위해 기상청에서는 단기예보를 목적으로 전지구 통합모델과 지역 통합모델을 연계한 동네예보를 수행하고 있으며, 초단기 예보를 위한 목적으로 VSRF, SCAN, VDRAS, MAPLE 등의 예보를 수행하고 있다. 홍수량 예측에서는 일반적으로 사용하고 있는 물리적 기반의 모형에 레이더강우와 같은 격자형 강우자료를 사용하여 정확성을 높이거나, 기존의 집중형 모형을 분포형 모형으로 대체하기 위한 연구 등이 이루어지고 있으며, 모형 구축이 간편하고 예측 정확도가 우수하다는 장점으로 인해 신경회로망이나 퍼지추론기법 등을 사용한 연구도 지속적으로 이루어지고 있다. 본 연구에서는 수자원분야에 산재한 불확실성을 적극적으로 인정하고 수학적으로 해석하기 위한 이론인 퍼지이론에 신경망 이론을 도입한 neuro-fuzzy 기법을 사용하여 홍수량을 예측하였다. 모형의 입력자료로는 관측된 강우자료와 유출량자료 및 기상청에서 제공하는 MAPLE(McGill Algorithm for Precipitation Nowcasting by Lagrangian Extrapolation) 강우예측자료를 사용하여 적용성을 평가해보았다. 모형의 적용성을 평가하기 위해 시험유역을 충주댐 상류 유역으로 선정하였으며, 2010년 2011년 홍수기의 충주댐 유입량을 예측하였다. 모형의 입력자료를 변경하여 입력자료의 변화에 따른 결과를 비교하였고, clustering 반경의 변화에 따른 정확도를 비교하였다. 모형의 정확도는 평균제곱근오차와 첨두수위오차를 통해 비교하였으며, 비교결과 전반적으로 lead time이 길어질수록 MAPLE 사용 시 예측 정확도가 우수하였고, clustering 반경은 0.5일 때 가장 우수한 결과를 보였다.

• Journal of Educational Research in Mathematics
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• v.17 no.1
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• pp.51-66
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• 2007

The purpose of this study is to analyse the cases of the posed problems while the mathematically gifted students are playing the NIM game. The findings of a qualitative case study have led to the conclusions as follows. Most of all mathematically gifted students in the elementary school are not intend to suggest the solutions of the posed problem unless the teacher or the 'problem is requested. But a higher level of promising children were changing each data components of a problem in a consistent way and restructuring the problems while controlling their cognitive process. This is compared to that a relatively lower level of promising children tends to modify one or two data components instantly without trying to look at the whole structure. And we gave 2 suggestions to teach the mathematically gifted students in the problem posing.

• Communications of Mathematical Education
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• v.28 no.2
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• pp.255-279
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• 2014

This study is to investigate the change of intelligent and affective domains through the student self-evaluation to identify causes of wrong answers. Through this evaluation, students could have opportunities to solve the given mathematical problems basically and to reflect their problem-solving process, and further to recognize which mathematical content(concepts or expressions, symbols, etc.) led them to solve the problems incorrectly or wrong. Through this process, they would correct their wrong process and answers and to reinforce the prerequisite knowledges relevant to the problems, and furthermore, to enhance problem-solving abilities. To accomplish this, this study was executed as a case study on the subject of four tenth graders. The subject consisted of two boys and two girls. In this study, three essay types of mathematical problems in tenth grade level were chosen from several domestic tests in Korea. Based on the original three essay type of problems, three types of similar problems, namely equivalent problem, similar problem, and isomorphic problems were reconstructed, respectively by the researchers. The subjects were guided to solve the original three problems, and they corrected their wrong parts of the first problem of the three problems. They solved an equivalent problem of the first problem and executed self evaluation and also corrected wrong parts. Next, they dealt with a similar problem of the first problem and executed self evaluation and also corrected wrong parts. Next, while dealing with an isomorphic problem of the first problem, the subjects did the same things. Thus, for the second and third original problems, the study was implemented in the same way. To explore their intelligent and affective domains through student self-evaluation in-depth, the subjects were interviewed formally before and after conducting the experiment and interviewed informally two times, and the recordings were audio-typed.

• Journal of the KSME
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• v.26 no.5
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• pp.375-381
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• 1986

De-Laval 노즐에서 경계층 배제두께의 음수현상에 대하여 수학적 모델을 통한 수치 고찰 한 결과 배제두께 뿐만 아니라 다음과 같은 경계층의 특성을 알 수 있었다. (1)온도비($T_w/T_0$)가 작아질수록 경계층 두께가 상대적으로 커진다. (2)운동량두께의 변화도 단열 벽면이 아닌 경우에는, 비압축성(${\rho}=const$) 유체 보다. 온도비가 작을수록 항상 커진다. (3) 경계층 배제두께는 온도비가 작은 경우 음(―)의 값을 나타내고 있어, 유효유동 단면적의 확대 현상을 보이고 있다.