• 대한전자공학회논문지SP
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• 제43권5호
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• pp.52-61
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• 2006

영상 및 신호 처리 분야에 일반적으로 사용되는 직교 웨이블릿 변환은 천이에 대한 민감성과 방향성에 대한 선택도가 떨어지기 때문에 성능에 한계를 가지고 있다. 이러한 단점을 극복하기 위해 복소수 웨이블릿 변환이 사용되고 있다. 본 논문에서는 이중 트리 복소수 웨이블릿과 베르누이-가우스 사전 확률분포를 이용한 효과적인 영상 잡음 제거 방법을 제안하고자 한다. 베르누이-가우스 모델에 대한 파라미터를 추정하기 위해 본 논문에서는 두 가지의 간단하고 반복적이지 않은 방법을 제안한다. 베르누이 랜덤 변수로 표현되는 혼합 파라미터를 추정하기 위해서는 가설-검증 기법을 사용한다. 추정된 혼합 파라미터를 이용하여 신호의 분산은 MGML(maximum generalized marginal likelihood) 추정기를 통하여 추정된다. 복소수 웨이블릿 변환을 사용하여 제안 방법과 알려진 잡음 제거 기법과 비교 실험을 수행하였다. 실험결과를 통해 제안 방법이 적은 계산량으로 고주파 성분이 많은 영상에 대하여 우수한 잡음 제거 결과를 나타냄을 알 수 있다.

• Korean Chemical Engineering Research
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• 제60권2호
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• pp.300-307
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• 2022

매우 짧은 펄스 폭의 X선 자유전자 레이저(XFEL)를 이용한 시간 분해능 연속 펨토초 결정학(time-resolved serial femtosecond crystallography, TR-SFX)기법에서 반응 물질과 생체분자 결정 샘플간의 혼합률(mixing rate)과 결정 샘플과 X선 레이저 간의 충돌률(hit rate)은 생체분자의 시분해 구조 변화에 대한 정확한 이미지 획득 및 효율적인 샘플소비와 같은 TR-SFX의 분석 성능을 결정짓는 핵심인자이다. 본 연구에서는 극초단 내 일어나는 생체분자의 시분해 구조 변화 해석을 위해 초고속 믹싱 기능을 가짐과 동시에 공압 기반의 주문형 액적 젯팅이 가능한 두 가지 다른 방식의 샘플 전달시스템을 고안하였다. 한 방식은 이중 노즐을 통해 토출된 액적의 고속 충돌에 유발된 관성 믹싱을 기반으로 하고 있으며, 다른 방식은 마이크로믹서가 내장된 공압 젯팅을 기반으로 하고 있다. 먼저, 이중 노즐을 통해 토출된 액적의 충돌에 대한 동적 거동 및 액적 내부 관성 유동에 대한 믹싱에 대한 실험 및 수치해석적 연구를 수행하였다. 다음으로 마이크로믹서가 내장된 공압 젯팅 시스템의 성능을 유사한 방법을 통해 평가하였다. 본 연구에서 개발한 샘플 전달시스템은 질환을 유발하는 특정 단백질들의 기작을 규명하거나, 항체 의약품과 신약 후보 물질 탐색하는 데 있어 필수적인 3차원 생체 분자 구조분석 연구에 매우 유용하게 활용될 수 있을 것이다.

• 제어로봇시스템학회논문지
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• 제8권7호
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• pp.589-598
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• 2002

The color measuring/matching expert system is implemented with a new color measuring method that combines intelligent algorithms with image processing techniques. Color measuring part of the proposed system preprocesses the scanned original color input images to eliminate their distorted components by means of the image histogram technique of image pixels, and then extracts RGB(Red, Green, Blue)data among color information from preprocessed color input images. If the extracted RGB color data does not exist on the matching recipe databases, we can measure the colors for the user who want to implement the model that can search the rules for the color mixing information, using the intelligent modeling techniques such as fuzzy inference system and adaptive neuro-fuzzy inference system. Color matching part can easily choose images close to the original color for the user by comparing information of preprocessed color real input images with data-based measuring recipe information of the expert, from the viewpoint of the delta Eformula used in practical process.

• Journal of Advanced Marine Engineering and Technology
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• 제21권5호
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• pp.557-563
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• 1997

The unsteady flow in three-dimensional cubic cavity with narrow channel at upper region is investigated experimentally for three kinds of Reynolds number, 1*10/sup 4/, 3*10/sup 4/ and 5*10/sup 4/ based on the cavity width and cavity inlet mean flow velocity. Instant velocity vectors are obtained simultaneously at whole field by PIV(Particle Image Velocimetry). Wall pressure distributions are estimated using Poisson equation from the velocity data. Results of PIV reveal that severe unsteady flow fluctuation within the cavity are remarkable at all Reynolds numbers and sheared mixing layer phenomena are also found at the region where inlet driving flow is collided with the clock-wise rotating main primary vortex. Instant velocity profiles reveal that deformed forced vortex formation is observed throughout the entire region and spanwise kinetic energy migration is conspicuous.

• Journal of Mechanical Science and Technology
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• 제15권12호
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• pp.1853-1859
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• 2001

An experimental study is presented for a flow field in a two dimensional wavy channels by PIV. This flow has two major applications such as a blood flow simulation and the enhancement of heat transfer in a heat exchanger. While the numerical flow visualization results have been limited to the fully developed cases, existing experimental results of this flow were simple qualitative ones by smoke or dye streak test. Therefore, the main purpose of this study is to produce quantitative flow data for fully developed and developing flow regimes by the Correlation Based Correction PIV (CBC PIV) and to conjecture the analogy between flow characteristics and heat transfer enhancement with low pumping power. Another purpose of this paper is to examine the onset position of the transition and the global mixing, which results in transfer enhancement. PIV results on the Fully developed and developing flow in a wavy channel at Re=500, 1000 and 2000 are obtained. for the case Reynolds Number equals 500, the PIV results are compared with the finite difference numerical solution.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(I)
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• pp.90-93
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• 1987

Phase conjugate wavefront generation via real-time holography in degenerate four-wave mixing experiments in photo-refractive crystal $Bi_{12}$ Si $O_{20}$ is presented. Depending on the respective values of applied field $E_o$ and fringe spacing, drift or diffusion of the photecarriers dominates the space-charge buildup and affects the Phasa- Conjugate Wavefront intensity. The experimental results for wavefront reflectivity as a function of the intensity ratio of the writing beams agree with the theoretical predictions.

• 한국수소및신에너지학회논문집
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• 제23권4호
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• pp.364-372
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• 2012

Transient mixing states of two different fuel oils, dimethylformamide (DMF) oil and JetA1 oil, were investigated by using a color image processing and a neural network. A tank ($D{\times}H$, $310{\times}370mm$) was filled with JetA1 oil. The DMF oil was filled at a top tank, and was mixed with the JetA1 oil in the tank mixing tank via a sudden opening which was performed by nitrogen gas with 1.9 bar. An impeller was rotated with 700 rpm for mixing enhancements of the two fuel oils. To visualize the mixing state of the DMF oil with the JetA1 oil, the DMF oil was coated with Rhodamine B whose color was red. A LCD monitor was used for uniform illumination. The color changes of the DMF oil were captured by a camcoder and the images were transferred to a host computer for quantifying the information of color changes. The color images of two mixed oils were captured with the camcoder. The R, G, B color information of the captured images was used to quantify the concentration of the DMF oil. To quantify the concentration of the DMF oil in the JetA1 oil, a calibration of color-to-concentration was carried out before the main experiment was done. Transient mixing states of DMF oil with the JetA1 oil since after the sudden infiltration were quantified and characterized with the constructed visualization technique.

• 한국건설순환자원학회논문집
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• 제11권2호
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• pp.130-137
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• 2023

이 연구는 다중벽 탄소나노튜브(MWCNTs) 혼입 PVA 섬유보강 시멘트 복합체에서 배합 순서에 따른 영향을 분석하기 위해 배합 순서를 변수로 고려한 실험을 통해 유동성, 압축 및 휨인장 성능을 분석하였다. 실험 결과, CNT 혼입으로 인하여 유동성이 크게 감소하였으며, CNT가 혼입된 경우 배합 순서에 따라 유동성이 크게 영향을 받는 것으로 나타났다. 압축 강도는 물과 CNT 수용액을 미리 섞어 혼입한 후 PVA 섬유를 혼입하는 순서가 가장 강도 증진 효과가 뛰어난 것으로 나타났으며, 휨인장강도는 건비빔 후 물과 CNT 수용액, PVA 섬유를 미리 섞은 후 배합한 방식이 가장 높은 것으로 나타났다. 다만, 휨인장 거동에서 연성도는 배합 순서와의 연관성이 명확하게 나타나지 않았다. 또한, 미세구조에의 영향을 분석하기 위해 주사전자현미경(SEM) 이미지 분석을 수행하였다. SEM 이미지 분석 결과, 모든 시편에서 CNT가 골고루 분산되어 분포하고 있는 것으로 나타나 CNT가 강도 증진 효과에 기여하고 있는 것을 확인할 수 있었으나, 배합방식으로 인한 차이는 명확하게 나타나지 않았다. 이 연구의 주요 결과는 향후 CNT 혼입 PVA 섬유보강 시멘트 복합체의 작업성 및 재료성능 평가 관련 연구에 유용할 것으로 기대된다.

• 대한기계학회논문집B
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• 제28권7호
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• pp.818-825
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• 2004

In this paper, the study of effects of flow parameters on flame structure and NOx emission concentration was performed in co-axial. laminar partially premixed methane/air flames. Such (low parameters as equivalence ratio(${\Phi}$), fuel split percentage($\sigma$), and mixing distance(x/D$\_$i/) were defined as a premixing degree and varied within ${\Phi}$=1.36∼9.52, $\sigma$=50∼100, and x/D$\_$i/=5∼20. The image of OH$\^$*/ and NOx concentration were obtained with an ICCD camera and a NOx analyzer. The flame structure observations show a categorization of partially premixed flames into three distinct flame regimes corresponding to ${\Phi}$<1.7(premixed flame structure), 1.7<${\Phi}$<3.3(hybrid structure), and ${\Phi}$>3.3(diffusion flame structure existing a luminous sooting region) at $\sigma$=75%, and x/D$\_$i/=10. As o decreases from 100% to 50%, and x/D$\_$i/ decreases, nonpremixed flame structure appear at low equivalence ratio relatively. In addition, the measured emissions for NOx rise steeply from ${\Phi}$=1.7, to ${\Phi}$=3.3, then constants ${\Phi}$>4.76. NOx emissions decrease with increase the level of premixing level. In conclusion, the main effect on flame structure and NOx production was at first equivalence ratio(${\Phi}$), and next fuel split percentage($\sigma$), and finally mixing distance(x/D$\_$i/).

• 대한가정학회지
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• 제44권9호
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• pp.41-50
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• 2006

This study examines the characteristics of the military look in modern fashion. The materials for the study are mainly precedent studies and related literature, although fashion portfolios and magazines, domestic and international, are used for the exploratory study. The results of the study are as follows. First, the military look for women dismantles the sexual symbolism endowed with the clothes by expressing a neutral charm out of dichotomy image between genders. The neutral expression of the military look, different from the military look of the 20th century, provides a chance to feature a new image by pursuing more individual freedom than human itself. Second, the military-look emphasizes feminine sensual charm through exposing, concealing, or decorating with ornaments which are transformed from the elements of the military clothes, This is different from the past military look that expressed masculine rigidity through simplifying the details and emphasizing the male body silhouette. Third, the military look produces a deconstruction image instead of just showing its intrinsic thoughts or symbolic message through combining design elements or symbolic details of the military look with other images, transforming and exaggerating the shapes, or mixing the time point of views reinterpreting the present or the future image.