• 제어로봇시스템학회논문지
• /
• 제14권8호
• /
• pp.818-823
• /
• 2008

In this paper, we propose a feature extraction method which extracts directional features of handwritten numerals by using the projection runlength. Our directional featrures are obtained from four directional images, each of which contains horizontal, vertical, right-diagonal and left-diagonal lines in entire numeral shape respectively. A conventional method which extracts directional features by using Kirsch masks generates edge-shaped double line directional images for four directions, whereas our method uses the projections and their runlengths for four directions to produces single line directional images for four directions. To obtain the directional projections for four directions from a numeral image, some preprocessing steps such as thinning and dilation are required, but the shapes of resultant directional lines are more similar to the numeral lines of input numerals. Four [$4{\times}4$] directional features of a numeral are obtained from four directional line images through a zoning method. By using a hybrid feature which is made by combining our feature with the conventional features of a mesh features, a kirsch directional feature and a concavity feature, higher recognition rates of the handwrittern numerals can be obtained. For recognition test with given features, we use a multi-layer perceptron neural network classifier which is trained with the back propagation algorithm. Through the experiments with the handwritten numeral database of Concordia University, we have achieved a recognition rate of 97.85%.

• 전자공학회논문지B
• /
• 제32B권6호
• /
• pp.909-921
• /
• 1995

The objective of this paper is to develop an algorithm for a real-time automatic fingerprint recognition system. The algorithm employs the Fast Fourier Transform (FFT) in determining the directions of ridges in fingerprint images, and utilizes statistical information in recognizing the fingerprints. The information used in fingerprint recognition is based on the dircetions along ridge curves and characteristic points such as core points and delta points. In order to find ridge directions, the algorithm applies the FFT to a small block of the size 8x8 pixels, and decides the directions by interpreting the resulted Fourier spectrum. By using the FFT, the algorithm does not require conventional preprocessing procedures such as smoothing, binarization, thinning, and restorationl. Finally, in matching two fingerprint images, the algorithm searches and compares two kinds of feature blocks, one as the blocks where the dircetions cannot be defined from the Fourier spectrum, and the other as the blocks where the changes of directions become abrupt. The proposed algorithm has been implemented on a SunSparc-2 workstation under the Open Window environment. In the experiment, the proposed algorithm has been applied to a set of fingerprint images obtained by a prism system. The result has shown that while the rate of Type II error - Incorrect recognition of two different fingerprints as the identical fingerprints - is held at 0.0%, the rate of Type I error - Incorrect recognition of two identical fingerprints as the different ones - is 2.2%.

• Wind and Structures
• /
• 제22권4호
• /
• pp.409-428
• /
• 2016

The mechanical and aerodynamic effect of building shape plays a dominate role in the pedestrian level wind environment. These effects have been presented in numerous studies and are available in many wind codes. However, most studies have focused on wind flow around conventional buildings and are limited to few wind directions. The present study investigated wind circulation in the re-entrant corners of cross-shaped high-rise buildings from various wind directions. The investigation focused on the pedestrian level wind environment in the re-entrant corners with different aspect ratios of building arrangements. Ninety cases of case study arrangements were evaluated using wind tunnel experimentation. The results show that for adequate wind circulation in the re-entrant corners, building orientations and separations play a critical role. Furthermore, in normal wind incident directions and at a high aspect ratio, poor wind flow was observed in the re-entrant corners. Moreover, it was noted that an optimized building orientation and aspect ratio significantly improved the wind flow in re-entrant corners and through passages. In addition, it was observed that oblique wind incident direction increased wind circulation in the re-entrant corners and through passages.

• 대한지리학회지
• /
• 제41권6호
• /
• pp.639-656
• /
• 2006

본 연구는 지식정보사회에서 신경제공간 형성의 메커니즘을 살펴보고 향후 지리학연구의 방향을 제시하고자 하였다. 정보화 사회에서 신경제공간의 형성 배경에 대해 개관하고, 그 메커니즘으로 네트워크, 착근성, 집적 및 분산에 대해서 설명하였다. 또한 한국에서 혁신활동이 활발한 서울의 강남지역과 낙후지역 중의 하나인 전북 순창지역에 대한 사례연구를 통하여 한국의 낙후지역에서도 신경제공간의 형성이 이루어지고 있음을 지적하였다. 이러한 이론적 논의와 사례연구를 바탕으로 앞으로 지리학연구의 방향을 크게 통합적 관점에서의 연구, 지리학연구 방법론 개발, 정책관련연구의 세 가지 측면에서 논의하였다.

• 한국공간구조학회논문집
• /
• 제16권1호
• /
• pp.65-72
• /
• 2016

Aerodynamic performance of solar wing system has been evaluated through wind tunnel test. The test model has 12 panels, each supported by 2 cables. The panels were installed horizontally flat, and gaps between panels were set constant. Sag ratios of 2% and 5%, and wind directions between $0^{\circ}$ and $90^{\circ}$ were considered. Mass of test model was determined considering the mass of full scale model, and Froude number and Elastic parameter were satisfied by adjusting the mean wind speed. From the wind tunnel test, it was found that the aerodynamic performance of the solar wing system is very dependent on the wind directions and sag ratios. When the sag was 2%, the fluctuating displacements between the wind directions of $0^{\circ}$ and $30^{\circ}$ increase proportionally to the square of the mean wind speed, implying buffeting-like vibration and a sudden increase in fluctuating displacement was found at large mean wind speed for the wind directions larger than $40^{\circ}$. When the wind direction was larger than $60^{\circ}$, a sudden increase was found both at low and large mean wind speed. When the sag ratio is 5%, distribution of mean displacements is different from that of sag ratio of 2%, and the fluctuating displacements show very different trend from that of sag ratio of 2%.

• 한국통신학회논문지
• /
• 제30권8C호
• /
• pp.801-809
• /
• 2005

본 논문에서는 디인터레이싱 방법 중에서 가장 중요한 요소인 공간 필터의 성능 개선을 위한 새로운 알고리즘을 제안한다. 기존의 에지 기반 알고리즘들은 보간의 성능을 좌우하는 정확한 에지 방향을 판단함에 있어서 만족스럽지 못하다. 제안하는 알고리즘은 에지 대신에 원 영상의 이진화 된 영상을 근간으로 에지의 방향과 기울기를 판단함으로써 효율성과 정확도를 증가시켰으며 보다 완만한 각에서의 방향판단을 위하여 탐색 윈도우 수평 크기를 IS로 증가시켰다. 기존의 에지를 이용한 방항 판단보다 이진화 된 이미지를 근간으로 에지의 방항과 기울기를 판단하여 보간 했을 때 판단의 오류를 최소화하여 차질을 향상시킬 수 있었다. 다양한 종류의 영상에 대한 컴퓨터 모의 실험 결과를 통하여 기존의 에지 기반의 보간 방법들에 비해 성능이 매우 우수함을 보였다.

• 대한인간공학회지
• /
• 제35권5호
• /
• pp.413-423
• /
• 2016

Objective:The aims of this study are to understand the effects of task (pushing, pulling, and clockwise and counter clockwise twisting) direction on the maximal output and their grip forces and to explore the relationship between the maximal output and the grip forces. Background: Knowing the normative maximal grip force is not enough to design a good hand tool. The industrial designers should understand the required grip forces in various motions toward a specific direction to make an effective and efficient hand tool. Method: Eighteen healthy volunteers participated in the series of isometric maximal output force tests. A custom-made force measuring equipment collected the output and the grip forces for three seconds. Force measurements along the vertical, coronal and sagittal axes were randomly repeated three times. Results: The pulling was strongest and the pushing was weakest in all directions. The effect of motion on the output forces varied in different directions. The corresponding grip force increased in the order of pushing, pulling, clockwise twisting, and counter clockwise twisting in all directions. The maximal output and their grip forces were highly correlated but the relationship was affected by motion and direction. The regression coefficient was greatest in pulling and smallest in clockwise twisting. Conclusion: The effect of motion on the output forces varied in different directions. The maximal output and their grip forces were correlated but the relationship was affected by motion and direction. Application: Findings of this study can be valuable information for industrial designers to develop more productive hand tools and work stations to help preventing the musculoskeletal disorders at work.

• Structural Engineering and Mechanics
• /
• 제26권6호
• /
• pp.687-707
• /
• 2007

High-tech facilities engaged in the production of semiconductors and optical microscopes are extremely expensive, which may require time-domain analysis for seismic resistant design in consideration of the most critical directions of seismic ground motions. This paper presents a framework for generating three-dimensional critical seismic ground acceleration time histories compatible with the response spectra specified in seismic design codes. The most critical directions of seismic ground motions associated with the maximum response of a high-tech facility are first identified. A new numerical method is then proposed to derive the power spectrum density functions of ground accelerations which are compatible with the response spectra specified in seismic design codes in critical directions. The ground acceleration time histories for the high-tech facility along the structural axes are generated by applying the spectral representation method to the power spectrum density function matrix and then multiplied by envelope functions to consider nonstationarity of ground motions. The proposed framework is finally applied to a typical three-story high-tech facility, and the numerical results demonstrate the feasibility of the proposed approach.

• 한국정밀공학회지
• /
• 제16권8호
• /
• pp.178-185
• /
• 1999

In tool condition monitoring systems, parameters should be set to a certain threshold. In many cases, however, the threshold is dependent on cutting conditions, especially the radial immersion ratio. In this presented is a method of on-line estimation of the radial immersion ratio in face milling. When a tooth finishes sweeping, a sudden drop of cutting force occurs. The force drop is equal to the cutting force that acting on a tooth at the swept angle of cut and can be acquired from cutting force signals in feed and cross-feed directions. Average cutting force per tooth period can also be calculated from cutting force signals in two directions. The ratio to cutting forces in two directions acting on a tooth at a certain swept angle of cut and the ratio of average cutting forces in two directions per tooth period are functions of the swept angle of cut and the ratio of radial to tangential cutting forces. Using these parameters, the radial immersion ratio is estimated. Various experiments are performed to verify the proposed method. The results show that the radial immersion ratio can be estimated by this method regardless of other cutting conditions.

• 수산해양교육연구
• /
• 제28권4호
• /
• pp.1014-1023
• /
• 2016

The purpose of this study is to suggest improvement directions and strategies for the minimization of ex-post damage and prevention of the generation of derelict fishing gear which lead to decreased fisheries resources and deteriorated marine ecosystem through ghost fishing and damaging spawning and growth grounds. Current problems related to derelict fishing gear in Korea are lack of reliable data on the generation amount of derelict fishing gear, absence of life-cycle monitoring and management system, insufficient supports for derelict fishing gear collection programs and R&D investment in environmentally friendly fishing gear, etc. Thus, this study suggests three basic improvement directions to prevent the generation and minimize the damage of derelict fishing gear. Such improvement directions contain more detailed strategies such as establishment of fishing gear management law and life-cycle management system, strengthening entry regulations on fisheries causing serious ghost fishing problems, increased supports for R&D investment and dissemination of bio-degradable fishing nets, and promotion of voluntary agreements among competing fishermen's groups.