• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.619-622
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• 2002

It has been recognized that the flow in the blade passage of an axial turbomachinery rotor is very complex and is influenced by various flow phenomena, of which the tip leakage flow passing through the gap between rotor blade tip and casing plays a significant role. The losses produced due to the existence of the clearance have been known to be a large contributor of the rotor overall losses. Despite several experimental studies on non-rotating blade in the cascade configuration, and on actual rotating blades, the detailed nature of the complex flow phenomena associated with tip leakage, however, remains largely unresolved. Thus, a single-stage compressor test rig was built and measurements were taken at upstream and downstream of the rotor of this compressor at the aerodynamics laboratory of University of New South Wales. A five-hole probe and a hot-wire probe were used to measure mean and fluctuating flow parameters. The results show that tip leakage losses rise rapidly beyond tip gap of 0.01 Furthermore, the present project also identifies the regions in the wake behind the rotor of the axial compressor where such losses are concentrated. These results should be useful in the better design of rotors for improved performance of axial compressor.

• Progress in Superconductivity
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• 제3권1호
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• pp.31-35
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• 2001

We investigated the temperature and magnetic field dependent optical properties of a$ MgB_2$ thin film in the far-infrared region. In the superconducting state, i.e. 5 K, we obtained the values of superconducting gap $2\Delta$ ~ 5.2 meV and $2\Delta$ $_{k}$ $B/T_{c}$ ~1.8. Although the value of$ 2\Delta$$B/T_{c}$ was nearly half of the BCS value, the $2\Delta$ seemed to follow the temperature dependence of the BCS formula. Under the magnetic field (H), the superconducting state became suppressed. Interestingly, we found that the normal state area fraction abruptly increased at low field but slowly increased at high field. It did not follow the H-dependences predicted for a s-wave superconductor (i.e. a linear dependence) nor for a s-wave one (i.e. $H^{1}$2/ dependence). We discussed the complex gap nature of $MgB_2$ in comparison with two gap and anisotropic s-wave scenarios.ios.

• 한국건축시공학회지
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• 제24권3호
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• pp.355-362
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• 2024

본 연구의 주요 목표는 아파트 단지 수선유지 비용을 예측하기 위해 딥러닝 기법을 적용한 예측 모델 구축 프레임워크를 제안하는 것이다. 아파트 건물을 이상적인 상태로 관리하기 위해서는 지속적인 유지 및 시의적절한 수리가 필수적이다. 아파트 단지는 광범위한 면적, 공동 시설, 다수의 주거 동, 서비스 지역 등으로 인해 유지관리가 복잡하다. 또한, 아파트의 안전성 보장, 가치 유지 및 경제적 효율성 때문에 경제적이고 합리적인 유지보수의 중요성이 점점 커지고 있다. 그러나 아파트 단지 수선유지는 다양한 외부 요인의 영향을 받고 데이터 수집이 어려워 연구가 부족한 상황이다. 따라서 본 연구는 실제 아파트 단지 유지보수 비용 데이터를 기반으로 딥러닝 기법을 활용해 유지보수 비용을 예측하는 모델 개발 프레임워크를 제시하고자 한다. 본 연구의 프레임워크 및 결과는 실질적으로 아파트 단지의 유지보수 비용 예측에 활용될 수 있으며, 궁극적으로 아파트 단지의 시설 관리 향상에 기여할 것이다.

• 한국시뮬레이션학회논문지
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• 제3권1호
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• pp.55-63
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• 1994

FMS is two or more computer controlled units interconnected with automated workhandling equipment and supervised by an executive computer having random scheduling capabilities. The complex nature of a FMS, coupled with the need to maximize its performance, means that such a system can be effectly designed only by iterative computer simulation methods. At the operational level, simulation had a reduced role to evaluate the performance of planned FMS under a variety of operating strategies. This is probably due to the fact that few simulation models are able to access the current status data of the system. This study reviews the role of simulation for design/operation of FMS and suggests an interface scheme for incorporating a simulation package with a FMS operational database. This scheme can be used for reducing the performance gap between design and real operation of a FMS.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2001년도 High Temperature Superconductivity Vol.XI
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• pp.19-19
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• 2001

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.883-886
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• 2008

In optical information technology, an electro-controllable Photonic Band Gap (PBG) in a photonic crystal (PC) material is potentially useful for the manipulation of light. Despite a great deal of research on PBGs, the reliable use of electro-active PBG material systems is restricted to only a few cases because of the complex and limiting nature of the structures involved. Here, we propose a PBG system that uses a liquid crystal (LC) polymer composite. The composite is made of nematic LCs (NLCs) embedded in polymeric helical networks of photo-polymerized cholesteric LCs (CLCs). The composite film shows a large field-induced reversible color shift over 150 nm of the reflection band, due to the reorientational undulation of the helical axis, similar to the Helfrich effect.

• 한국초등과학교육학회지:초등과학교육
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• 제27권2호
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• pp.102-116
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• 2008

In their teaching practice, teachers encounter multi-dimensions of pedagogical challenges. The recognition and reflection on these challenges is crucial to advance our science teaching. This study looked into science teachers' dilemmas of their teaching practical work through their written cases. Dilemma cases are teachers' narratives organized around important events of teaching and learning. It can reveal teachers' situated cognition and be used as lens to investigate complex realities of science teaching and learning. 26 pre- and in-service elementary teachers' dilemma cases of science practical work were carefully collected and analysed to interpret what constitute tensions in elementary science practical works. They were largely grouped into three: Curriculum and Institutional Relevance, Students Relevance, Nature of School Experiments Relevance and divided into 7 subheadings: 'Authority of Curriculum(textbook)', 'Disappointment at external support', 'Students' interests and safety', 'Students' unscientific and inert attitude', 'Difficulty of showing expected results', 'Generalization through experiment', 'Knowledge acquisition and authentic inquiry'. Each dilemma was interpreted in terms of the tensions which constitute contradictory beliefs, values, expectation and realities. These dilemmas enabled to expose actual conditions of elementary science practical work and teachers' challenges otherwise can not be seen easily. Science teacher educators also can get some implications to overcome the gap between theory and practice in their teacher education.

• Structural Engineering and Mechanics
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• 제84권1호
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• pp.101-111
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• 2022

It is widely known that axially loaded fiber-reinforced polymer (FRP) confined concrete presents significant and enhanced mechanical properties with reference to the unconfined concrete. Therefore, to predict the mechanical behavior of FRP-confined concrete two quantities-peak strength and ultimate strain are required. Despite the significant advances, the determination of the ultimate strain of FRP-confined concrete is one of the most challenging problems to be resolved. This is often attributed to our persistence in desiring the conventional methods as the sole technique to examine this phenomenon and the complex nature of the ultimate strain of FRP-confined concrete. To bridge the research gap, this study adopted two machine learning (ML) techniques-artificial neural network (ANN) and Gaussian process regression (GPR)-to analyze observations obtained from 627 datasets of FRP-confined concrete circular and non-circular sections under axial loading test. Besides, the techniques are also used to predict the ultimate strain of FRP-confined concrete. Seven parameters namely width/diameter of the specimens, corner radius ratio, the strength of concrete, FRP elastic modulus, FRP thickness, FRP tensile rupture strain, and the axial strain of unconfined concrete-are the input parameters used to predict the ultimate strain of FRP-confined concrete. The results of the current study highlight the merit of using AI techniques in structural engineering applications given their extraordinary ability to comprehend multidimensional phenomena of FRP-confined concrete structures with ease, low computational cost, and high performance over the existing empirical models.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권4호
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• pp.1543-1561
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• 2020

Taxonomy of human brain activity is a complicated rather challenging procedure. Due to its multifaceted aspects, including experiment design, stimuli selection and presentation of images other than feature extraction and selection techniques, foster its challenging nature. Although, researchers have focused various methods to create taxonomy of human brain activity, however use of multivariate pattern analysis (MVPA) for image recognition to catalog the human brain activities is scarce. Moreover, experiment design is a complex procedure and selection of image type, color and order is challenging too. Thus, this research bridge the gap by using MVPA to create taxonomy of human brain activity for different categories of images, both colored and gray scale. In this regard, experiment is conducted through EEG testing technique, with feature extraction, selection and classification approaches to collect data from prequalified criteria of 25 graduates of University Technology PETRONAS (UTP). These participants are shown both colored and gray scale images to record accuracy and reaction time. The results showed that colored images produces better end result in terms of accuracy and response time using wavelet transform, t-test and support vector machine. This research resulted that MVPA is a better approach for the analysis of EEG data as more useful information can be extracted from the brain using colored images. This research discusses a detail behavior of human brain based on the color and gray scale images for the specific and unique task. This research contributes to further improve the decoding of human brain with increased accuracy. Besides, such experiment settings can be implemented and contribute to other areas of medical, military, business, lie detection and many others.

• 한국언론정보학보
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• 제17권
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• pp.61-84
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• 2001

근래에 들어 각급 교육기관의 언론관련 학과가 급격하게 증설되고 등록학생수가 증가하면서 우리나라에서도 언론학 교육에 대한 논의와 논란이 활발하게 진행되고 있다. 이러한 언론학 교육의 양적 확대에도 불구하고 제기되고 있는 논의는 언론학 교육의 내용에 대한 언론계와 전공학생들의 비판과 함께 급속하게 발전, 확산되고 있는 새로운 커뮤니케이션 기술이 초래한 변화들의 수용에 있어서의 학문적 한계 등으로 무엇을 왜 가르치고 어떻게 가르쳐야 하는가에 대해 근본적으로 다시 생각하도록 하는 계기가 되고 있다. 그러나 언론학의 이러한 문제점들에 대한 논의에 일관하고 있는 몇 가지 대립되는 개념들, 예를 들면 기능 대 지식, 훈련 대 교육, 어떻게 대 왜, 전문적 대 학문적, 그리고 이론 대 실제 등의 구분은 이성적인 학문적 분석에 의거한 구분이라기보다는 전 시대적인 사회계층 구분이나 집단적 이해의 투영이라는 측면이 더 강하게 작용한 결과로 분석할 수 있다. 따라서 학문 중심적이며 이론 지향적 성격이 강한 우리나라 언론학 연구와 교육이 안고 있는 과제는 이론 체계의 구축과 교육 목표, 교육 내용, 그리고 교육 방법의 구현에 있어서 이 한계를 어떻게 극복하느냐가 관건이 될 것이다.