• Proceedings of the Korea Water Resources Association Conference
• /
• 2015.05a
• /
• pp.168-168
• /
• 2015

자연하천의 주요한 특징 중 하나인 하천의 사행은 직선수로에서 예측되는 유속분포를 왜곡시키며 매우 복잡한 흐름구조를 형성한다. 이는 하상 경계면에서 발생하는 전단응력 분포의 변화를 야기하는데 하상 경계면에서의 전단응력은 다양한 경험적 관계에 의존하는 유사이동의 한계 소류력 산정 및 오염물질 거동해석의 분산계수 산정에 많은 영향을 미치게 된다. 물리적인 관측을 통한 하상 경계면에서의 전단응력의 관측은 다소 제한적이며 많은 비용을 요구한다. 따라서 하상 경계면에서 발생하는 전단응력의 경우 수심의 20% 이하의 연직 유속분포를 벽법칙에 적용하여 추정하는 방법이 주로 이루어지고 있다. 벽법칙을 이용한 하상 경계면의 전단응력을 계산하는 경우 대수중복층의 유속 분포 $u/u^*=(1/{\kappa})ln(zu^*/{\nu})+B$에서 무차원상수 ${\kappa}$와 B의 적절한 추정이 요구되어 진다. 일반적으로 무차원상수 ${\kappa}$와 B는 수리학적으로 매끄러운 벽면에서 대략 ${\kappa}=0.4$, B=5.5로서 경험적으로 이용되고 있다. 본 연구에서는 직선수로 및 다양한 사행수로의 3차원 흐름장 모의를 수행하여 벽법칙의 대수 중복층을 따르는 주흐름 방향 유속의 연직분포를 비교하였다. 수치모의 소프트웨어로서 Linux 기반의 OpenFOAM이 사용되었으며 모델의 검증을 위해 Chang(1971)에 의해 수행 된 사행수로에서의 유속장 관측 결과와 비교하였고 수치모의 결과가 실험 관측치와 잘 일치하는 것으로 판단되었다. 수치모의에 적용 된 사행수로의 형상은 Hey(1976)에 의해 제안 된 사행하천의 지형학적 인자들 간에 관계를 이용하여 사행도 1.03에서 2.42까지 총 7개의 사행수로 지형을 생성하였다. 사행도의 변화에 따라 만곡부 정점에서 대수중복층 구간의 주흐름 방향 유속의 연직분포를 비교한 결과, 본 연구에서 생성 된 모든 사행수로에서 대수중복층 구간의 무차원 유속 $u^+$와 무차원 거리 $z^+$가 로그 분포를 따르는 것으로 나타났으나 경험적으로 사용되었던 무차원상수 B의 경우 사행도가 증가 할수록 대수적으로 감소하는 경향이 나타났다. 본 연구에서는 이러한 관계가 무차원 상수 B값에 미치는 영향을 반영하여 수리학적으로 매끄러운 벽면에서 적용이 가능한 수정된 대수중복층 식을 제시하고자 한다.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.36S no.2
• /
• pp.63-68
• /
• 1999

We propose a new method which can solve the difficulty of separation the character strings from the interconnected lines and the distortions of vectorization at the crossing points and the junction points for the digitized maps at the same time. After the image is thinned, the crossing points and the junction points are detected with their neighbors, which we call the uncertain areas. And then the broken lines are connected each other, and the character strings are separated at the same time. The proposed method is applied to Korean cadastral map. Usually, Korean cadastral map consists of straight lines and character strings. The experimental results show that the method is effective in separating the character strings and getting high quality vectorization for the Korean cadastral map.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.11 no.2
• /
• pp.231-236
• /
• 2011

In recent years, LBS(Location Based Service) is applied in many different fields. Therefore, various location-aware schemes have been studied. In the location awareness system using time dependent algorithm, TOA(Time of Arrival) or TDOA(Time Difference of Arrival) algorithm, distortion of a signal by AWGN(Additive White Gaussian Noise) and multi-path effects cause the degradation of location awareness performance. In this paper, the unexpected noise is eliminated by averaging multiple pulses in order to overcome the degradation of performance. Also, we research the technique for improving the performance of the location awareness by detecting direct-path signal with adjusting threshold.

• Annual Conference on Human and Language Technology
• /
• 1989.10a
• /
• pp.142-147
• /
• 1989

필기체 문자는 인쇄체 문자와는 달리, 복잡한 변형이 따르므로, 인식 하는데 많은 문제점이 따른다. 그렇기 때문에 일반적인 필기체 인식에 있어서는 필기 자체에 대한 제한을 두어 변형을 적게한 문자를 인식 대상으로 삼고 있다. 이러한 문자는, 설정된 조건만 확실하게 만족한다면, 비교적 간단하게 인식 할 수 있다. 반면에, 자유 필기체 문자는, 제한 필기체 문자와는 달리 변형이 크기 때문에, 그 인식에는 많은 연구가 필요하다. 본 연구에서는, 자유 필기체 한글의 자모를 추출하는데 있어 두개의 parameter space method를 이용했다. 화상내에서의 혼합은, 기본적으로 5 개의 element ($\mid,\;\setminus,\;/,\;-,\;o$)로 구성되어 있고, 이 element를 정의하는데는 최소한 4 개의 parameter, 즉 element의 위치 [x, y], 크기 [1] 및 type [T] 등이 필요하다. 입력 화상에서 추출된 직선 및 원의 성분은 [x, y, l] 과 [x, y, T]의 2 개의 3-D parameter space 에 누적되고, parameter space 상에서의 병합 분할 과정을 거쳐, element 가 형성된다. 추출된 element 들은, parameter space 상에서의 방향성 및 상호 위치 관계에 의한 조합 형태로서, 미리 기술되어진 자모 모델과 비교되어 인식된다. 본 방법의 특정은, 문자의 크기에 무관하고, 해석방법에 의해서는, 끊어진 element나 불필요한 element 등의 왜곡된 element 들의 처리가 가능한 점, 4 차원 parameter space를 두개의 3 차원 parameter space로 분리, 처리시간과 기억용량의 절약을 기한점 등을 들 수 있다.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.9 no.5
• /
• pp.19-26
• /
• 1972

A newly developed quartz frequency modulator utili3ing a V. V. C. diode is briefly described. Its electrical characteristics-including modulation linearity, modulation distortion, and carrier frequency stability depending upon the variation of the environmental temperature and the applied power voltage, etc.-are suitable for the modulator of a mobile or a portable F.M. transmitter according to the experimental results. The excellent over-all electrical characteristics were proved from the experimental development of the two kinds of transceivers. One is the single channal transceiver which contains a direct frequency modulator at the carrier frequency of 52.750 MHg. The other is the dual channel transceiver (the frequencies are selected from about 40 channels without tuning adjustment) whose operational frequency is composed of a modulated frequency of 10.7 MHz and the frequency generated at a channel control oscillator, As mentioned above, it is realized that the electrical characteristics of this modulation method are suitable for portable F. M. transceivers.

• Journal of Broadcast Engineering
• /
• v.17 no.5
• /
• pp.838-850
• /
• 2012

In this paper, we propose a novel algorithm that generates multi-view images by using various image features obtained from the given stereoscopic images. In the proposed algorithm, we first create an intensity gradient saliency map from the given stereo images. And then we calculate a block-based optical flow that represents the relative movement(disparity) of each block with certain size between left and right images. And we also obtain the disparities of feature points that are extracted by SIFT(scale-invariant We then create a disparity saliency map by combining these extracted disparity features. Disparity saliency map is refined through the occlusion detection and removal of false disparities. Thirdly, we extract straight line segments in order to minimize the distortion of straight lines during the image warping. Finally, we generate multi-view images by grid mesh-based image warping algorithm. Extracted image features are used as constraints during grid mesh-based image warping. The experimental results show that the proposed algorithm performs better than the conventional DIBR algorithm in terms of visual quality.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.33 no.5
• /
• pp.465-471
• /
• 2013

A steam generator in nuclear power plant is a heatexchager which is used to convert water into steam from heat produced in a nuclear reactor core, and the steam produced in steam generator is delivered to the turbine to generate electricity. Because of damage to steam generator tubing may impair its ability to adequately perform required safety functions in terms of both structural integrity and leakage integrity, eddy current testing is periodically performed to evaluate the integrity of tubes in steam generator. This assessment is normally performed during a reactor refueling outage. Currently, the eddy current testing for steam generator of nuclear power plant in Korea is performed in accordance with KEPIC & ASME Code requirements, the eddy current testing system is consists of remote data acquisition unit and data analysis program to evaluate the acquired data. The KEPIC & ASME Code require that the electrical properties of remote data acquisition unit, such as total harmonic distortion, input & output impedance, amplifier linearity & stability, phase linearity, bandwidth & demodulation filter response, analog-to-digital conversion, and channel crosstalk shall be measured in accordance with the KEPIC & ASME Code requirements. In this paper, the measurement requirements of electrical properties for eddy current testing instrument described in KEPIC & ASME Code are presented, and the measurement results of newly developed eddy current testing instrument by KHNP(Korea Hydro & Nuclear Power Co., LTD) are presented.

• Proceedings of the KSR Conference
• /
• 2007.11a
• /
• pp.1141-1151
• /
• 2007

In this paper through Honam high-speed railroad which is planned with the north and south axis, we will verify the feasibility of the coordinate conversion using railroad control points after regarding current planned-railroad as the linear central axises. From analysis, distortion of Y axis varies 21cm to 40cm diminishing to a gentle straight line, distortion of X axis varies 14cm to 29cm. Through a revision, the deviation value between the coordinates were 6mm to 9mm and it satisfied the allowable error of national geographic information institute which is following ITRF (International Terrestrial Reference Frame) and cadastral boundary survey(10cm). consequently the coordinate conversion is possible using railroad control points as common control points.

• The Transactions of the Korea Information Processing Society
• /
• v.4 no.4
• /
• pp.1141-1151
• /
• 1997

In this paper the Maximum Block Method is suggested for the Feature Extraction of stokes of off-line Chinese characters.The Maximum Block Method is a technique which enlarges the block from the first found pixel that wxtracts the skeleton and features of the input characters.The maximum Block mthod is an adequate technique for the correct extraction of the features since the exsting thining methods have shortcomings of making the feature extraction difficult from the distoritions generated from the effiects of the parial noises,inflection points and blemishes. The printed outputs and chinese books of the middle and high school students,and other materials are used for the test.It was found that the Maxthod is also an effective technique for the extraction of skeleton line and features,which is the preoprocessing of the pattern recognition,for the Korean chracters and English as well as chinese chracters.

• Journal of the Institute of Convergence Signal Processing
• /
• v.8 no.1
• /
• pp.78-83
• /
• 2007

Robot collects surrounding information to recognize tile unknown environment by using various sensors such as visual, infrared ray and ultra sonic sensors. Although visual sensor is the most popular one, it has some difficulties in collecting data in dark or too bright environment due to sensitivity of the light. It also requests significant amount of calculation on collecting data from certain images with marked, straight and curved ones. As an alternative, ultra sonic sensor can simply overcome this visual sensing system's flaw and easily be used. It is easier than visual system, especially in case of collecting data on object and distance in dark environment. Ultra sonic sensor can replace the expensive visual sensing system not only in avoiding obstacles but also in reaching to the target area smoothly. The purpose of this paper is to develop the algorithm to optimize the environmental recognition, path planning and free-ranging by minimizing errors caused by inaccurate information and by considering characteristics of the ultra sonic rays such as refraction and diffusion. This paper also realizes the system that can recognize the environment and make the appropriate path planning by applying the algorithm on this moving robot.