• Journal of the Korean Society of Visualization
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• v.15 no.3
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• pp.47-51
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• 2017

In this study, we investigate the wake characteristics in laminar inflow and two different turbulent inflow cases. To solve the flow with wind turbines and its wake, we use large eddy simulation (LES) technique with actuator line method (ALM) and turbulent inflow of Turbsim. We perform the quantitative analysis of velocity deficit and turbulent intensity in laminar inflow case and turbulent inflow case with different turbulent intensity. In turbulent inflow, unsteady strong wake recovery which is highly fluctuated in time. Normalized power in turbulent inflow case is also highly fluctuated with unsteady wake recovery, while that in laminar inflow has quasi steady characteristic in power generation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.6
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• pp.732-738
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• 2004

One of the main degradation mechanisms in steam generator tubes is stress corrosion cracking induced by residual stress. The resulting damages can cause tube bursting or leakage of the primary water which contains radioactivity. Shot peening technique has been used to prevent stress corrosion crack growth in steam generator tubes. In order to investigate the shot peening effect on stress corrosion cracking stress intensity factors are calculated for the semi-elliptical surface crack which is located in residual stress region. The residual stress distribution in steam generator tubes is obtained from the simple model proposed by Frederick et al.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.8
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• pp.303-313
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• 2001

The identification of power flow in dynamically loaded structures Is essential in the analysis of structure-borne noise. However there are no general purpose tools to estimate powers flow. To make matters worse. It is very difficult to measure it. The power flow can be formulated in terms of balance forces(ELFORCE) at each element and velocities at the associated node obtained with MSC/NASTHAN. In this paper the procedure which is consist of the computations of the balance forces of al1 elements and the velocities at all nodes using MSC/NASTRAN. The calculations of the power f1ow at each element using PCL(PATRAN Command Language) and the Preparation of post -processes is set UP.

• 한국공간정보시스템학회:학술대회논문집
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• 2005.05a
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• pp.459-462
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• 2005

위성화상 또는 항공사진을 이용하여 산화지를 탐지하고 정량화하기 위한 여러 가지 방법적인 시도가 있었다. 보다 정확한 산화지 탐지를 위해, 본 연구에서는 기존의 고해상도 범색화상과 중 저해상도 다중분광 화상의 융합(fusion)에 주로 이용되었던 IHS(Intensity, Hue, Saturation) 색채변환을 산화지 탐지와 정량화에 적용하였다. IHS 색채변환을 이용한 Hue 조합화상의 산화지 최대우도분류 결과는 Landsat-7 ETM+ 7:4:1 조합화상보다 놀은 사용자분류 정확도를 나타냈으며 색상(Hue)과 채도(Saturation)가 명도(Intensity)에 비해 ETM+ 화상의 분광특성을 잘 반영하였다.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.411-414
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• 2001

목표물 인식(Target Recognition)에 사용되는 대표적인 특징 정보에는 밝기 (Intensity) 정보와 윤곽선(Boundary) 등의 모양(Shape) 정보가 있다. 그러나, 일반적으로 영상에서 바로 추출한 밝기 정보나 윤곽선 정보는 환경 변화에 의한 많은 오차 요인들을 포함하고 있기 때문에, 이들 특징 정보를 개별적으로 인식에 사용하는 것은 높은 인식 성능을 기대하기 어렵다. 따라서, 밝기 정보와 모양 정보를 인식에 함께 사용하는 기법이 요구된다. 본 논문에서는 밝기 정보와 윤곽선 기반의 모양 정보를 합성하여 동시에 인식에 사용하는 3단계 기법을 제안한다. 제안하는 기법에서 밝기 정보 추출에 는 PCA (Principal Component Analysis)기법을 사용하고 , 윤곽선 정보 추출에는 PDM(Point Distribution Model) 에 기반한 영역 분할(Segmentation) 기법과 Algebraic Curve Fitting기법을 사용하였다 추출된 밝기 정보와 윤곽선 정보는 FLD(Fisher Linear Discriminant) 기법을 통해 결합(integration)되어 인식에 사용 된다. 제안한 기법을 적외선 자동차 영상을 인식하는 실험에 적용한 결과, 기존기법에 비해 인식 성능이 개선됨을 확인할 수 있었다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.4
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• pp.483-494
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• 1998

This study describes the characteristics on impeller discharge flow of a centrifugal compressor with vaneless diffuser. Distorted flow at impeller exit was investigated by measuring of unsteady velocity fluctuation using hot-wire anemometer. As a result, a wake region appears near shroud side and moves to suction side and also to hub side as flow rate decreases. Jet, wake, and their boundary region which can be defined in jet-wake flow model are clearly observed at a high flow rate for the flow coefficient of 0.64, however, as flow rate decreases to the flow coefficient of 0.19, the classification of their regions disappears. Turbulence intensity also increases as flow rate decreases. Measurement error from uncertainty analysis is estimated about 4% at the flow coefficient of 0.19

• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.147-152
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• 1999

Distribution of fracture system is an important factor to analyse instability of jointed rock slope. In the most case of rock slopes, joint distribution properties are related to potential, shape, size and locality of slope failure. The purpose of this paper is to present an application of fracture characterization related to rock slope failure. Fracture data used in this study are collected by scanline survey. Two aspects of fracture characterization for rock slope are handled in this study First, In order to determine the potential and shape of slope failure, trace length of joints is considered as the weighting factor about collected orientation data. Second, Relationship between trace length and spacing is analysed to estimate failure location and size. The distribution of fracture system is directly influenced on wedge failure. It is effective to analyse the orientation of fractures by using weighting factors associated with the trace length of fractures rather than to analyse only that of fractures. It gives a conclusion that the wedge failure occurred along the peak of fracture density(or intensity) cycles.

• The Journal of Korean Academy of Prosthodontics
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• v.31 no.1
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• pp.51-61
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• 1993

The purpose of this study was to evaluate a possible occlusal contributing factor on the pathogenesis of temporomandibular joint sound by a new computer aided method for analysis of occlusal contact. 20 subjects without temporomandibular joint sound as control group and 20 subjects with temporomandibular joint sound as experimental group in the TMJ clinic, dental infirmary, School of Dentistry, Chosun University were selected so as to investigate the distribution and intensity of the bilateral occlusal contacts on silicone rubber bites in habitual intercusal position through a computer aided system. The following results were obtained : 1. The distribution and intensity of the occlusal contact could be analyzed and expressed as color density value per levels by this computer aided method. 2. There was not statistical significance between control and experimental group in total occlusal contacts. 3. There was statistical significance between control and experimental group In the total difference of right and left occlusal contacts.(P<0.05).

• Journal of Advanced Marine Engineering and Technology
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• v.15 no.5
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• pp.23-29
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• 1991

Uncertainty is studied in the measurements of average packing density, thickness of packed spheres and transmittance in the experiments to study the effect of the bed height and the existence of the bed side walls on the transmittance of radiative energy through packed spheres. The packing density of the bed is obtained by counting the number of the spheres packed in three pipes with different heights. The bed height of the packed spheres is estimated from the number of spheres contained in the bed by using the relation between the bed height and the sphere number. The transmittance is obtained by dividing the intensity of the transmitted laser beam by the incoming-beam intensity. From the analysis, the uncertainity in the measurements of transmittance is shown to be less than 10.2%(95% coverage).

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.6
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• pp.49-56
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• 1998

Super precision working technique and machine tool have been continually developed thanks to advanced electronic field. To obtain good result. it is necessary to investigate surface in grinding with $mu extrm{m}$ level. There were quite many researches to satisfy these demands by using non-contact methods through the computer vision. In this study, the texture of working surface was analyzed. co-occurrence matrices was obtained from the surface roughness. Texture parameter was obtained using position operator composed of $ heta$, d according to variation of angle direction and distance. As a result, it was found that surface texture was more affected by direction($\theta$) than distance(d).