• The Journal of the Korea Contents Association
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• v.6 no.12
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• pp.21-28
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• 2006

In a face detection system based on template matching, histogram equalization or log transform is applied to an input image for the intensity normalization and the image improvement. It is known that they are noneffective in improving an image with intensity distortion by illumination variation. In this paper, we propose an efficient image improvement method using a simple regression analysis combined with a bilateral symmetry average for images with intensity distortion by illumination variation. Experimental results show that our method delivers the detection performance better than previous methods and also remarkably reduces the number of face candidates.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.8-8
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• 2008

Two-dimensional photonic quasicrystal (PQCs) template patterns have been fabricated on a $1.1{\mu}m$-thick DMI-150 photoresist using a multiple-exposure holographic method. A 442-nm HeCd laser was utilized as a light source and the holographic exposure was carried out at a fixed angle of $\theta=6^{\circ}$. After the first holographic exposure, the sample was rotated to a proper angle and the second exposure was performed to the same manner. This exposure process was repeated n/2 times to obtain n-fold symmetric PQC patterns and then the sample was developed. The fabricated PQCs exhibited 8, 10 and 12-fold rotational symmetry and the diffraction patterns using a 632.8-nm HeNe laser were observed for n-rotation symmetry corresponding n-fold PQCs. The fabricated PQC template patterns were examined using scanning electron microscopy(SEM). Transmission spectra were measured fourier transform infrared(FTIR) spectrometer.

• Journal of the Korea Society of Computer and Information
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• v.21 no.6
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• pp.21-28
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• 2016

Circle detection has long been studied as one of fundamental image processing applications. It is used in divers areas including industrial inspection, medial image analysis, radio astronomy data analysis, and other object recognition applications. The most widely used class of circle detection techniques is the circle Hough transform and its variants. Management of 3 dimensional parameter histogram used in these methods brings about spatial and temporal overheads, and a lot of studies have dealt the problem. This paper proposes a robust circle detection method using maximal symmetry property of circle. The basic idea is that if perpendicular bisectors of pairs of edges are accumulated in image space, center of circle is determined to be the location of highest accumulation. However, directly implementing the idea in image space requires a lot of calculations. The method of this paper reduces the number of calculations by mapping the perpendicular bisectors into parameter space, selecting small number of parameters, and mapping them inversely into image space. Test on 22 images shows the calculations of the proposed method is 0.056% calculations of the basic idea. The test images include simple circles, multiple circles with various sizes, concentric circles, and partially occluded circles. The proposed method detected circles in various situations successfully.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.891-894
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• 2001

본 논문에서는 NTGST (noise·tolerant generalized symmetry transform)와 snake를 이용하여 복잡배경으로부터 여러 물체의 윤곽선을 동시에 검출하는 방법을 제안하였다. 먼저 NTCST의 대칭도 맵(symmetry map)을 이용하여 복잡한 배경에 혼재하는 여러 물체들의 위치를 찾은 다음, 이들 각 물체에 snake의 초기 윤곽들을 자동 설정해 줌으로써 기존 snake 알고리즘의 초기 윤곽 설정의 어려움과 다중 물체 윤곽선 검출의 어려움을 동시에 해결하였다. 이때 NTGST의 대칭도 맵으로부터 설정된 snake의 초기 윤곽은 실제 물체의 윤곽선 가까이에 위치할 뿐만 아니라 물체의 형태를 잘 반영하므로 요철이 있는 물체의 윤곽선도 기존의 방법보다 적은 반복횟수로 정확하게 검출 할 수 있다. 다양한 합성 영상과 실영상에 적용한 결과 복잡배경으로부터도 다중 물체의 윤곽선을 효과적으로 추출함을 확인하였다.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.35C no.5
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• pp.50-58
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• 1998

We propose an efficient face recognition system for controllinng the access to the restricted zone using both the face region detectors based on facial symmetry and the extended self-organizing maps (ESOM) which have sensory synapses and descriptive synapses. Based on the visual cues of the facial symmetry, we apply horizontal and vertical projections on elliptic regions detected by GHT(generalized hough transform) to identify all the face regions from the complex background.And we propose an ESOM which can exploit principal components and imitate an elastic similarity matching, to authenticate faces of the enlisted member. In order to cope with changes of facial experession or glasses wearing, etc, the facial descriptions of each member at the time of authentication are simultaneously updated on the discriptive synapses online using the incremental learning of the proposed ESOM. Experimental results prove the feasibility of our approach.

• 전자공학회논문지 IE
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• v.44 no.4
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• pp.48-54
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• 2007

Due to the diverse utilization of multimedia, interests are increasing towards processing (saving, editing, searching, etc) three dimensional object data. This paper proposes and realizes a retrieval system for three dimensional objects using reflective symmetry. For the retrieval method, a reflective symmetric axis with a projector is used. The symmetric plane is calculated by the reflection symmetry, and the depth buffer is calculated for the symmetric plane. Then, by applying the Fourier Transform to the depth buffer, the feature vector for the object is generated and retrieved. For the sample of inquiry, the model of similar symmetry was extracted using the benchmark data from Konstantz University. Considering that most of the objects have symmetrical characteristics, the proposed method of retrieving three dimensional objects using a reflective symmetric surface is an outstanding retrieval system.

• Proceedings of the IEEK Conference
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• 2001.06d
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• pp.127-130
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• 2001

본 논문에서는 SIMD (Single Instruction stream and Multiple Data stream)형 병렬 구조의 다중 프로세서를 이용하여 NTGST (noise-tolerant generalized symmetry transform)를 병렬 고속화하였다. 먼저 NTGST의 화소 및 영상 영역간의 계산 독립성을 이용하여 영상을 분할하여 P개의 프로세서에 할당하고, 이들 각각을 N개의 데이터를 한번에 처리하는 SIMD 구조로 병렬화하여 NP에 비례하는 속도 향상을 얻었다. 실험에서 MMX 기술의 펜티엄 Ⅲ 프로세서를 2개 사용하여 제안한 알고리즘이 기존의 NTGST 보다 8배 가까이 고속으로 처리됨을 확인하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10b
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• pp.347-349
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• 2000

Reisfeld 등이 제안한 일반화 대칭 변환의 대칭 기여도를 구하는 방법은 물체의 윤곽선의 방향과 거리를 이용하여 물체의 내부에 누적시키는 것으로써, 물체의 검출이나, 얼굴 검출 등의 많은 분야에서 이용되고 있다. 본 논문에서는 대칭 변환 기여도의 모양은 물체의 외곽 모양에 따라 달라지는 것을 이용하여 대칭 변환 기여도의 모양을 분석하여 특정 모양의 물체를 인식하는 방법을 제안한다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.10a
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• pp.88-95
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• 1997

In this paper, we present an efficient method for finite element vibration analysis of constantly rotating blade disks which are deformed to some considerable extent by centrifugal force, Coriolis force and operating load, and vibrate due to several types of exciting forces. A blade disk which is a structure with cyclic symmetry is divided into substructures with the same geometry. Only one substructure is modeled and can be analysed rapidly and exactly using discrete Fourier transform by means of a computer with small memory.

• Korea-Australia Rheology Journal
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• v.18 no.2
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• pp.91-98
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• 2006

We compare FT (Fourier Transform) and SD (Stress Decomposition), the interpretation methods for LAOS (Large Amplitude Oscillatory Shear). Although the two methods are equivalent in mathematics. they are significantly different in numerical procedures. Precision of FT greatly depends on sampling rate and length of data because FT of experimental data is the discrete version of Fourier integral theorem. FT inevitably involves unnecessary frequencies which must not appear in LAOS. On the other hand, SD is free from the problems from which FT suffers, because SD involves only odd harmonics of primary frequency. SD is based on two axioms on shear stress: [1] shear stress is a sufficiently smooth function of strain and its time derivatives; [2] shear stress satisfies macroscopic time-reversal symmetry. In this paper, we compared numerical aspects of the two interpretation methods for LAOS.