• 한국세라믹학회지
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• 제40권3호
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• pp.286-292
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• 2003

본 연구에서는 나노기술을 이용하여 에너지 감쇄 기능을 활용한 감쇄기 개발에 대한 기초적인 연구를 하였다. 기계 구조물에 사용되는 기존의 유체 감쇄기를 대체할 수 있는 무기재료를 이용한 새로운 감쇄기에 대한 기초연구를 수행하여 감쇄기 설계와 실용화에 적용하고자 하였다. 완충역할을 하는 입자로는 미로구조를 가지는 실리카겔을 사용하였고, 입자에 관련한 작동 유체로는 물을 사용하여 실험적으로 그 효과를 검증하였다. 콜로이드 감쇄기를 구현하기 위해서는 형성된 실리카겔 입자의 표면을 유기 실리콘 매질을 이용한 소수화 코팅 처리를 하였다. 콜로이드 감쇄기의 에너지 감쇄량과 효율을 작동 유체에 대하여 각각 구하여 유효한 감쇄 효과를 입증하여 설계에 반영할 수 있게 되었다. 또한 압축해제에 걸리는 시간을 조사하여 기존의 유압 감쇄기와 비교한 결과 본 논문에서 제안된 감쇄기의 기능이 우수함이 입증되었다.

• 정보처리학회논문지B
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• 제10B권3호
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• pp.311-320
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• 2003

고유의 텍스쳐 성분에만 최적 반응을 하는 최적 필터(optimal filter)는 다중 텍스쳐 영상으로부터 원하는 텍스쳐 성분을 추출하기 위한 가장 뛰어난 기술이다. 그러나 기존의 최적필터 설계 방법들은 영상에 내재된 텍스쳐 정보가 사전에 주어지는 교사적 방법이 대부분이며, 내재된 텍스쳐 인식을 기반으로 하는 완전 비교사적인 방법에 관한 연구는 거의 이루어지고 있지 않은 실정이다. 따라서 본 논문에서는 효율적인 텍스쳐 분석을 위한 비교사 학습 방법과 가버필터의 주파수 대역 통과형 특징을 이용한 새로운 최적 필터 설계 방법을 제안한다. 제안한 방법은 자기조직형 신경회로망에 의해서 영상에 내재된 텍스쳐 영역을 블록 단위로 군화(clustering)하며, 가버필터의 최적 주파수는 인식된 텍스쳐 오브젝트(texture objects)의 공간 주파수를 분석한 최적 주파수에 동조(turning)한다. 그리고 설계된 최적 가버필터의 성능 평가를 위해서는 다양한 형태의 다중 텍스쳐 영상을 생성하여 내재된 텍스쳐 오브젝트를 추출함으로써 성공적인 결과를 보인다.

• Journal of Power Electronics
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• 제14권3호
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• pp.444-457
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• 2014

This paper presents the design and realization of a digital PV simulator with a Push-Pull Forward (PPF) circuit based on the principle of modular hardware and configurable software. A PPF circuit is chosen as the main circuit to restrain the magnetic biasing of the core for a DC-DC converter and to reduce the spike of the turn-off voltage across every switch. Control and I/O interface based on a personal computer (PC) and multifunction data acquisition card, can conveniently achieve the data acquisition and configuration of the control algorithm and interface due to the abundant software resources of computers. In addition, the control program developed in Matlab/Simulink can conveniently construct and adjust both the models and parameters. It can also run in real-time under the external mode of Simulink by loading the modules of the Real-Time Windows Target. The mathematic models of the Push-Pull Forward circuit and the digital PV simulator are established in this paper by the state-space averaging method. The pole-zero cancellation technique is employed and then its controller parameters are systematically designed based on the performance analysis of the root loci of the closed current loop with $k_i$ and $R_L$ as variables. A fuzzy PI controller based on the Takagi-Sugeno fuzzy model is applied to regulate the controller parameters self-adaptively according to the change of $R_L$ and the operating point of the PV simulator to match the controller parameters with $R_L$. The stationary and dynamic performances of the PV simulator are tested by experiments, and the experimental results show that the PV simulator has the merits of a wide effective working range, high steady-state accuracy and good dynamic performances.

• 한국실내디자인학회논문집
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• 제25권3호
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• pp.51-59
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• 2016

The technique for Eye-tracking is to trace the movements of pupils so that the eye's exploration response to be digitized. The procedure of Observation Experiment shows a mutual environmental characteristics between men and measuring devices. In order to improve the reliability and to secure the objectivity of the data acquired from eye-tracking, it is very important to analyze the procedures for the experiment to be prepared and the test data to be saved. Based on this viewpoint, the convergent exploration activities at the observation experiment with the objects of sport images were examined to find out what influences the context effect given by experimental environments have on this experiment. In addition, the starting time of attention affecting the reliability of observation data has been estimated. When the observation time is to be subdivided by the unit of second. The attention disperses for the individual characteristics to be appreciated. However, in case of analysis by the overall average, there was the problem that the section of attention dispersed to make it difficult to analyze the subjects' observation features. The study results made it possible to understand the physiological characteristics which were near unconsciousness, when there was an intensive attention for the first 3 seconds and the observation data were shown to be in ordinary range after 4 seconds. The analysis of observation with the focus of the intensive attention enabled the analysis with the first 3 seconds excepted so that it might approach the ordinary range of observation data. The distribution of attention for the first 3 seconds showed the intensive attention, which was on the center. The emergence of intensive attention and the overlapping of the centers can be considered as a context effect due to the correction for the preparing process of experiment. Accordingly, it is thought to be helpful to the security of objectivity and the construction of reliability of eye-tracking data to analyze the observation features shown after the deletion of the data for the first 3 seconds.

• 한국실내디자인학회논문집
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• 제18권6호
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• pp.44-51
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• 2009

Various and complex cultural phenomena have led to many changes in the space. The concept of unconsciousness, among others, and experimental expression technique and the concepts from surrealism that rather attaches great importance to contingency than intentional attempt have been employed in the space. The abstract expression as expressional characteristics of surrealism makes the space ambiguous through the concept of automatism using the approach of indeterminism and double image expression, and represents the space providing diversity through the dualism. In contrast, objective expression, which was based on depaysement, generates the tension and expresses the dramatic situation in such a way and manner which are intentional, distorted transformed, together with heterogenous meanings aligned through the reversal appeared in the techniques of collage and paranoiac-critical method. However if such space accommodating the expressional characteristics of surrealism is approached as superficial concept in analyzing the human's inner consciousness and imaginary society, expression of the ultimate concept contained in the expressional characteristics of surrealism can hardly be achieved. Hence, the spatial analysis from the semiotic approach, instead of unilateral method aimed to convey the meaning only, which creates the signification, was adopted. The study, as effective approach to the space accommodating the expressional characteristics of surrealism, was intended systematically evaluate the concreteness of understanding and generation of meaning through the semiotic method. Greimas' semiotic square analysis to the space plays the important role in generating the spatial meaning, as well as is needed for objective analysis of the importance of various characteristics and methodology which the space contains through the expressional characteristics of surrealism.

• 전력전자학회논문지
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• 제19권4호
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• pp.364-375
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• 2014

Parametric array transducers are used for long-range and highly directional communication in an underwater environments. The power amplifiers for parametric array transducers should have sufficient linear output characteristic and high efficiency to avoid communication errors, system heating, and fuel problems. But the conventional power amplifier with fixed source voltage is very low efficient due to large power loss by the big difference between the fixed source voltage and the amplifier output voltage. Thus to solve the problems this paper proposes the high efficiency power amplifier for parametric array transducers. The proposed power amplifier ensures high linearity of output characteristic by utilizing the push-pull class B type amplifier and furthermore gets high efficiency by applying the envelope tracking technique that variable source voltage tracks the envelope of the amplified signal. Also the paper suggests the detailed circuit topology and design guideline of class B push-pull type amplifier and variable output voltage AC/DC converter. Its characteristics are verified by the detailed simulation and experimental results.

• 한국소음진동공학회논문집
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• 제16권8호
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• pp.848-856
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• 2006

This paper describes the aeroelastic stability test of the small-scaled 'Next-generation Blade(NRSB)' with NRSH (next-generation hub system) and HCTH hingeless hub system in hover and forward flight conditions. Excitation tests of rotor system installed in GSRTS (general small-scale rotor test system) at KARI (Korea Aerospace Research Institute) were carried out to get lead-lag damping ratio of blades with flexures as hub flexure. MBA(moving block analysis) technique was used for the estimation of lead-lag damping ratio. First, NRSB-1F blades with HCTH hub system, then NRSB- 1F with NRSH hub system were tested. Second, NRSB-2F blades with NRSH hub system were tested. Tests were done on the ground and in the wind tunnel according to the test conditions of hover and forward flight, respectively. Non-rotating natural frequencies, non-rotating damping ratios and rotating natural frequencies were showed similar level for each cases. Estimated damping ratios of NRSB-1F, NRSB-2F with HCTH and NRSH were above 0.5%, and damping ratio increased by collective pitch angle increasement. Furthermore damping ratios of NRSB-2F were higher than damping ratios of NRSB-1F in high Pitch angle. It was confirmed that the blade design for noise reduction would give observable improvement in aeroelastic stability compared to paddle blade and NRSB-1F design.

• International Journal of Advanced Culture Technology
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• 제9권3호
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• pp.188-201
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• 2021

The purpose of this study is to analyze the effects of online home learning in connection with extracurricular activities for lifelong education for the disabled in university on the cooking aids skills of cafeterias for the job search persons with developmental disabilities. Three people with job search developmental disabilities who have been in a state of unemployment for three years after graduating from a special high school course participated in the experiment. In order to verify the meaningful functional relationship between independent variables and dependent variables, multiple probe design across subjects, one of the main techniques of a single object study, was used. The experimental conditions according to the research design consisted of the steps of baseline, intervention, maintenance, and generalization. The dependent variable of this study is the restaurant cooking aid skills in the cafeteria, and three subskills such as side dish arrangement, sink arrangement, and dish washing were combined by task analysis. And the independent variable of this study was composed of procedures and methods to teach the environment, tools and materials related to the performance of dependent variables to the developmental disabled people at home by using real-time image technique through zoom service, and the contents of the performance by stages of task analysis. In addition, independent variables were applied to the subjects in the course of the extracurricular activities with the theme and contents of lifelong education for the disabled at university. Students who completed the above extracurricular activities practiced the intervention scene of the researcher through the screen sharing of zoom service. As a result, the subjects with developmental disabilities effectively acquired and maintained the positive response performance of dependent variables through independent variables. The subjects also showed high positive responses to generalization tests conducted in kitchens in cafeterias located elsewhere in the same university.

• 한국항해항만학회지
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• 제45권3호
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• pp.165-172
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• 2021

쇄파는 연안류, 표사이동, 충격파압, 에너지소산 등과 같은 연안에서 발생하는 다양한 물리현상과 직접적인 관계가 있으므로 항만 구조물의 설계시 반드시 고려되어야 하는 중요한 설계인자 중 하나이다. 쇄파에 대한 연구들은 쇄파가 가진 고유의 복잡성으로 인해 주로 수리모형실험을 통해 쇄파파고와 쇄파수심 등과 같은 쇄파지표를 예측하기 위한 많은 경험식이 제안되어 왔다. 하지만, 기존의 쇄파지표에 대한 경험식은 일정한 방정식의 가정하에 자료의 통계적 분석을 통해 가정한 방정식의 계수들을 결정하고 있다. 본 연구에서는 회귀 혹은 분류문제와 관련된 다양한 연구분야에 있어서 높은 예측성능을 보여주는 대표적인 선형기반의 머신러닝 기법을 적용하여 천수변형에 의해 발생하는 쇄파의 한계파고를 산정하기 위한 새로운 Munk형식의 경험식을 제안하였다. 새롭게 제안된 쇄파지표식은 단순한 형태의 다항식에도 불구하고 기존의 경험공식과 유사한 예측성능을 보였다.

• 한국시뮬레이션학회논문지
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• 제19권2호
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• pp.1-8
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• 2010

최근 컴퓨터 하드웨어 및 3D 그래픽의 기술 발전으로 많은 사용자들이 실제와 유사한 3D 그래픽으로 표현되는 것에 관심을 가지고 있다. 이러한 사용자들의 요구가 증대됨에 따라 많은 분야에서 3D 시뮬레이션이 개발 보급되고 있다. 본 논문에서는 3D 그래픽 기술을 활용하여 화재시의 건물 내에서 사람들이 대피하는 시뮬레이션 시스템을 설계하고 구현한다. 본 논문에서는 사람이 화재 시 건물을 탈출할 때 인공지능을 갖기 위해 A* 알고리즘을 사용하였으며, 화재 시에 사람의 탈출에 영향을 미치는 열과 연기를 고려하여 각 사람의 탈출 속도를 계산한다. 본 논문에서 제안하는 대피 시뮬레이션의 효과를 입증하기 위해 실제 건물환경을 모델링하여 적용하였다. 실험결과들을 통해서 본 논문에서 제안한 방법을 통하여 연기의 농도가 짙어질수록 사람의 탈출속도가 감소하는 것과 온도와 연기 농도에 의해 사람이 피해를 입고 사망하는 것을 확인할 수 있다.