• Molecules and Cells
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• 제45권2호
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• pp.65-75
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• 2022

Hypothalamus is a brain region that controls food intake and energy expenditure while sensing signals that convey information about energy status. Within the hypothalamus, molecularly and functionally distinct neurons work in concert under physiological conditions. However, under pathological conditions such as in diet-induced obesity (DIO) model, these neurons show dysfunctional firing patterns and distorted regulation by neurotransmitters and neurohormones. Concurrently, resident glial cells including astrocytes dramatically transform into reactive states. In particular, it has been reported that reactive astrogliosis is observed in the hypothalamus, along with various neuroinflammatory signals. However, how the reactive astrocytes control and modulate DIO by influencing neighboring neurons is not well understood. Recently, new lines of evidence have emerged indicating that these reactive astrocytes directly contribute to the pathology of obesity by synthesizing and tonically releasing the major inhibitory transmitter GABA. The released GABA strongly inhibits the neighboring neurons that control energy expenditure. These surprising findings shed light on the interplay between reactive astrocytes and neighboring neurons in the hypothalamus. This review summarizes recent discoveries related to the functions of hypothalamic reactive astrocytes in obesity and raises new potential therapeutic targets against obesity.

• 한국과학교육학회지
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• 제37권2호
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• pp.313-322
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• 2017

본 연구에서는 2012년부터 2015년까지 개발되어 공개된 233개의 초등학교 프로그램들을 대상으로, 과학기술과 인문학 융합의 내용적 측면과 방법적 측면의 융합 실태를 분석함으로써, 추후 STEAM 프로그램 개발이나 정책 개발, 기 개발된 프로그램의 현장 적용을 위한 수정 보완 등에 기초자료와 시사점을 제공하고자 하였다. 분석 결과, STEAM 프로그램 내에서 Liberal Arts로 구분된 국어, 사회, 도덕 교과의 융합 빈도 중 도덕 교과의 융합이 상대적으로 낮게 나타났다. 이는 그동안의 STEAM 교육에 있어 과학기술과 인문학 융합이 구체적 목적 아래 이루어진 내용적 융합보다는 다양한 학문간의 융합만이 상대적으로 강조되었기 때문으로 보인다. 과학기술과 인문학 융합의 방법적 측면의 분석에서는 기술적 차원의 인문학 융합에 비해 규범적 차원의 인문학 융합이 상대적으로 적게 이루어졌다. 단순히 두 가지 방법의 정량적 비교가 의미를 가지는 것은 아니나, 일부 윤리적, 규범적 정향이나 고민이 필요한 프로그램들이 발견됨에도 불구하고 단순히 기술적 인문학 융합만 이루어져 과학기술의 양면성에 대한 학생들의 인식 부재가 염려된다. 또한 STEAM 프로그램에서 분석된 과학기술과 규범적 차원의 인문학 융합이 이루어진 경우도 '과학기술의 활용에 있어서의 인문학 보정'과 '과학기술 연구와 발전 그 자체에 대한 인문학 보정' 으로 나누어짐을 알 수 있었다. 이러한 연구 결과들을 바탕으로 STEAM 프로그램 개발이나 정책 개발, 교육현장에서의 프로그램 수정 보완 등과 관련된 시사점을 논의하였다.

• 한국기술혁신학회:학술대회논문집
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• 한국기술혁신학회 2014년도 추계 학술대회 논문집
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• pp.218-237
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• 2014

• Journal of Mechanical Science and Technology
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• 제20권1호
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• pp.66-75
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• 2006

A modeling method for the modal analysis of rotating beam structures having complex configurations employing multi-reference frames is presented in the present study. In most structural analysis methods, single reference frame is employed for the modal analysis. For simple structures such as single beam or single plate, the method of employing single reference frame usually provides rapidly converging accurate results. However, for general structures having complex configurations, such a method provides slowly converging, and often erroneous, results. In the present study, the effects of employing multi-reference frames on the convergence and the accuracy of the modal analysis of rotating beam structures having complex configurations are investigated.

• Journal of applied mathematics & informatics
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• 제32권1_2호
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• pp.61-74
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• 2014

This paper describes an iterative method for orthogonal projections $AA^+$ and $A^+A$ of an arbitrary matrix A, where $A^+$ represents the Moore-Penrose inverse. Convergence analysis along with the first and second order error estimates of the method are investigated. Three numerical examples are worked out to show the efficacy of our work. The first example is on a full rank matrix, whereas the other two are on full rank and rank deficient randomly generated matrices. The results obtained by the method are compared with those obtained by another iterative method. The performance measures in terms of mean CPU time (MCT) and the error bounds for computing orthogonal projections are listed in tables. If $Z_k$, k = 0,1,2,... represents the k-th iterate obtained by our method then the sequence of the traces {trace($Z_k$)} is a monotonically increasing sequence converging to the rank of (A). Also, the sequence of traces {trace($I-Z_k$)} is a monotonically decreasing sequence converging to the nullity of $A^*$.

• 한국전산유체공학회지
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• 제10권1호
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• pp.31-38
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• 2005

Three-dimensional flow over the sand dunes have been studied numerically by using Large-Eddy Simulation (LES) method. In the direction of initial flow and span direction cyclic boundary conditions are imposed for velocity and pressure. The movement of the sand dune which is formed by converging wind direction has been investigated. The numerical method employed in this study can be divided into three parts: (i) calculation of the air flow over the sand dune using standard MAC method with a generalized coordinate system; (ii) estimation of the sand transfer caused by the flow through the friction; (iii) determination of the shape of the sand surface. Since the computational area has been changed due to step (iii), (i)-(iii) are repeated. The simulated dune, which has initially elliptic cross section, extends at the converging direction, which is known as linear dunes.

• 한국정밀공학회지
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• 제9권1호
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• pp.82-95
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• 1992

There is the high interest for sensing of tool wear with the aim of controlling machine tools productivity from the point of view of qualitity. Difficulties in this measurement are also known. This study is on the development of measurement setup for crater wear by CCD image inturning. In this study, the crater wear measurement system consists of the He-Ne gas laser, diffraction grating. CCD camera, noise filter, slit, microcomputer, diverging lens, converging lens and so on. He-Ne laser beam passes through a diverging lens and a diffraction grating is positioned properly. A converging lens focuses so that the interference fringes can be obtained on the crater wear. Performance test revealed that the developed image technique provides precise, absolute tool-wear quantification and reduces human measurement errors. The results obtained are as follows 1. The digitizing of one image requires less than 2ses. 2. It can give detailed information on crater wear with limited times and errors 3. All parameters required by specification are easily obtained for several points of the cutting edge.

• 한국자동차공학회논문집
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• 제7권6호
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• pp.17-31
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• 1999

This paper is a review of the results of examining the flow characteristics of gas and particles with regards to pipe-type nozzle and converging nozzles depending on nozzle geometry. The nozzles used in this experiment are the pipe-type nozzle which can sufficiently mix the gas and particles, and the converging nozzle which can rapidly accelerate fluid . The particles used at the time of this experiment each measured 0.8, 30, 60 and 80${\mu}{\textrm}{m}$ in the diameter. The Phase Doppler Particle Analyzer was used to measure the velocity of each particle, and the Hot-wire probe was used to measure the spectrum in order to analyze the flow near the nozzle exit of the 0.8${\mu}{\textrm}{m}$ particle.

• 대한수학회지
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• 제39권6호
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• pp.963-973
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• 2002

We study torsion phenomena in the integral cohomology of finite if-spaces X through the Eilenberg-Moore spectral sequence converging to H＊($\Omega$X; Z$_{p}$). We also investigate how the difference between the Z$_{p}$-filtration length f$_{p}$(X) and the Z$_{p}$-cup length c$_{p}$(X) on a simply connected finite H-space X is reflected in the Eilenberg-Moore spectral sequence converging to H＊($\Omega$X;Z$_{p}$). Finally we get the following result: Let p be an odd prime and X an n-connected finite H-space with dim QH＊ (X;Z$_{p}$) $\leq$ m. Then H＊(X;Z) is p-torsion free if (equation omitted).tion omitted).

• 한국멀티미디어학회논문지
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• 제18권10호
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• pp.1251-1260
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• 2015

The measurement and evaluation of an audience's visual attention are crucial processes for the scientific production of various contents and services. It has been alleged that a vector exists between objects on a screen, but this has not been explored empirically. This study tested whether or not there are any positive correlations between screen vectors and viewers' eye movements. Participants were exposed to four groups of pictures representing an independent vector, continuing vector, converging vector, and diverging vector. The results showed that vectors on screens induced viewers' eye movements to the vector object by the directivity of the visual stimuli.