• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권1호
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• pp.404-421
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• 2020

A reversible data hiding scheme in JPEG compressed bitstreams is proposed, which could avoid decoding failure and file expansion by means of removing of bitstreams corresponding to high frequency coefficients and embedding of secret data in file header as comment part. We decode original JPEG images to quantified 8×8 DCT blocks, and search for a high frequency as an optimal termination point, beyond which the coefficients are set to zero. These blocks are separated into two parts so that termination point in the latter part is slightly smaller to make the whole blocks available in substitution. Then spare space is reserved to insert secret data after comment marker so that data extraction is independent of recovery in receiver. Marked images can be displayed normally such that it is difficult to distinguish deviation by human eyes. Termination point is adaptive for variation in secret size. A secret size below 500 bits produces a negligible distortion and a PSNR of approximately 50 dB, while PSNR is also mostly larger than 30 dB for a secret size up to 25000 bits. The experimental results show that the proposed technique exhibits significant advantages in computational complexity and preservation of file size for small hiding capacity, compared to previous methods.

• 한국정보통신학회논문지
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• 제14권11호
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• pp.2478-2484
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• 2010

본 논문은 실시간 파노라마를 위한 영상의 특징점 검출 방법을 제안한다. 파노라마 연구는 최근 실시간 지역탐색이나 DVR 등에 적용하는 연구가 최근 활발히 진행되고 있다. 특히 특징점 검출은 파노라마를 이루는 가장 중요한 요소이다. 특징점 검출을 위해서는 어떠한 명암 변화에도 특징점은 불변이어야 하며 이미지의 크기와 회전이 변화하더라도 불변의 점을 찾아야 한다. 기존 연구방법은 고차원적인 벡터와 많은 후보점을 선점하기 때문에 연산량이 많고 수행시간이 길어 실시간에 활용하기에는 어려운 점이 있다. 따라서 본 논문은 보다 빠른 실시간 특징점 검출을 위해 LOG 방법을 비트 단위로 분할 후 결합하는 BLOG 방법을 제안하고 다양한 실험을 통하여 속도와 연산량 그리고 검출 성능에 대하여 비교한다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.257-258
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• 2006

In this paper, we address several issues in the real time implementation of MPEG-1 Layer II decoder on a fixed-point digital signal processor (DSP), especially TMS320C6416. There is a trade-off between processing speed and the size of program/data memory for the optimal implementation. In a view of the speed optimization, we first convert the floating point operations into fixed point ones with little degradation in audio quality, and then the look-up tables used for the inverse quantization of the audio codec are forced to be located into the internal memory of the DSP. And then, window functions and filter coefficients in the decoder are precalculated and stored as constant, which makes the decoder faster even larger memory size is required. It is shown from the real-time experiments that the fixed-point implementation enables us to make the decoder with a sampling rate of 48 kHz operate with 3 times faster than real-time on TMS320C6416 at a clock rate of 600 MHz.

• 한국건설관리학회논문집
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• 제25권3호
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• pp.37-46
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• 2024

최근 스마트 건설기술 중 현상에 대한 정확하고 빠른 정보수집이 가능한 3D 레이저 스캐닝 기술이 주목받고 있다. 3D 레이저 스캐닝 기술은 건설현장에서 현실과 가장 유사한 정보를 획득할 수 있다. 본 연구에서는 3D 레이저 스캐닝 기술을 활용하여 수집할 수 있는 포인트 클라우드 데이터를 건설현장 진도측정에 적용 가능성에 대하여 새로운 부재 식별방법을 실제 건물에 적용하여 제시하고자 한다. 연구 수행을 위해 BIM으로부터 부재 식별을 위한 위치 정보를 수집, 수집된 위치 정보의 인식 여유 범위를 설정하여 포인트 클라우드 데이터로부터 건물을 구성하고 있는 부재 식별을 진행하였다. 연구결과 포인트 클라우드 데이터로부터 건물을 구성하고 있는 기둥, 보, 벽 그리고 슬라브를 식별할 수 있음을 확인하였다. 식별결과는 실제 건물에 시공이 완료된 부재를 모두 확인할 수 있었으며, 이를 프로젝트 BOQ의 부재별 단가와 연동하여 기성 산출에 활용할 수 있다. 또한, 연구를 통해 획득한 포인트 클라우드 데이터는 건설현장의 품질관리 모니터링 및 건물의 유지관리를 위한 정확한 자료로써 활용될 수 있다. 연구결과는 추후 프로젝트 활용을 위해 사용되는 건설 정보의 적시성 및 정확성 향상에 기여할 수 있을 것으로 사료된다.

• 정보저장시스템학회논문집
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• 제3권3호
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• pp.135-138
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• 2007

Using a Shack-Hartmann sensor and sub-wavelength sized pinhole point source, we develope an optical testing system that measures the wavefront error of high numerical aperture and small sized optical components. The subwavelength sized pinhole generates perfect spherical waves with large diffraction angle and this makes possible to test high numerical aperture optics. The Shack-Hartmann sensor reconstructs the wavefront and calculates the aberrations. We make a home-made reference plane wave source which generates nearly perfect plane waves and the calibration with this plane source gives the overall uncertainty of the optical testing system 0.010 $\lambda$ rms.

• 한국CDE학회논문집
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• 제12권1호
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• pp.58-73
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• 2007

This paper described a method for the construction of a surface through a set of nonuniform scattered points. When the shift vectors of some points as constraints on the original surface are given, those of the other points should be computed to make the new surface. To keep up the look-see and smoothness with the original surfaces, the proper relationship should be formulated between the shifts of the constraint points and those of the other points. Vector fields for 3 dimensional shift of a point on the surface are made based in the constraint shifts. Vector fields for 3 dimensional shift of a point on the surface are made based on the constraint shifts. Multilevel B-spline approximation technique was used to construct the vector field. The technique uses coarse-to-fine hierarchy of control lattices. The developed method was applied to shoe sole design system especially for grading. Using this system, a shoe sole can be modified effectively.

• International Journal of Precision Engineering and Manufacturing
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• 제9권3호
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• pp.82-84
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• 2008

A surface encoder based on the Half-shaded square pattern (HSSP) is presented. The HSSP working as reference grid is composed of the straight lines which are easy to be fabricated and make measuring time short. Since the periodic cell is separated in ON/OFF by the $45^{\circ}$ straight line, the duration from the starting point of scanning to the first rising edge and the duty cycle of the pulse train vary with respect to the position of the starting point. And the relationship between X and Y position and the duration, and duty cycle is described in the simple linear equation. Therefore, it is possible to measure X and Y position with the measured duration and duty cycle without calculating load. Through the test set-up, the feasibility of the proposed surface encoder was verified. Also the future works for improvement of performance were suggested.

• 산업공학
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• 제14권2호
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• pp.190-197
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• 2001

Growth curves including Logistic and Gompertz functions are widely used in forecasting the market demand. To estimated the parameters of those functions, we use the non-linear least square method. However, it is difficult to set up the starting points for each parameter. If a wrong starting point is selected, the result reveals the local optimum or does not converge to a certain value. The purpose of this paper is to resolve the problem of selecting a starting point. Especially, rescaling the market data using the national economic index make it possible to figure out the range of parameters and to utilize the grid search method. Applications to some real data are also included.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.927-929
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• 2003

The rib in synchronous reluctance motor(SynRM), which has segment type rotor, is mechanical weak Point. To make up for the weak point, a web has inserted in the flux barrier. However, the inductance in the q-axis is increased and then the motor performance has been decreased because of the inserted web. This paper presents a model, which has permanent magnets on the both side of the web, to decrease the inductance in the q-axis. The finite element method is applied to analyze the characteristics.

• 한국의상디자인학회지
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• 제3권1호
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• pp.117-127
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• 2001

In the 1980's discuss in the postmodernism and at the 1990's that is globalization. Globalization is the compression of time and space. That is the products of modernism and postmodernism. Global trends are the multiculturalism, localism, tribuism, etc. These trends have a important effect modern fashion. 20th fashion have a modernity -variation, functionalism and popularity, postmodernity-uncertainty, multiculturalism, post structuralism, etc. If Korean fashion have the globality, open to the world other country and culture, deep study of that, and view point of intercultureity. This Study Suggest to achieve globalize of Korean costume. 1. Plon up base on the scholastic study of giobalization. 2. Promote global project of Korean collection. 3. Collect of ethnic, culture, information of fashion America, Europe, etc. and make high up our a sense of disorimination. 4. Manifold studing abroad 5. Strergthening of globalization and ethnic curriculum on Educational course