• 디지털산업정보학회논문지
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• 제8권2호
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• pp.95-104
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• 2012

In this paper, an estimation of person height and 3D location of a moving person by using the pan/tilt-embedded stereo tracking system is suggested and implemented. In the proposed system, face coordinates of a target person is detected from the sequential input stereo image pairs by using the YCbCr color model and phase-type correlation methods and then, using this data as well as the geometric information of the stereo tracking system, distance to the target from the stereo camera and 3-dimensional location information of a target person are extracted. Basing on these extracted data the pan/tilt system embedded in the stereo camera is controlled to adaptively track a moving person and as a result, moving trajectory of a target person can be obtained. From some experiments using 780 frames of the sequential stereo image pairs, it is analyzed that standard deviation of the position displacement of the target in the horizontal and vertical directions after tracking is kept to be very low value of 1.5, 0.42 for 780 frames on average, and error ratio between the measured and computed 3D coordinate values of the target is also kept to be very low value of 0.5% on average. These good experimental results suggest a possibility of implementation of a new stereo target tracking system having a high degree of accuracy and a very fast response time with this proposed algorithm.

• 한국해안·해양공학회논문집
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• 제23권4호
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• pp.265-275
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• 2011

방파제 등 항만 외곽시설의 설계에 있어서 파랑은 구조물의 단면을 결정하는 가장 중요한 요소이다. 본 연구에서는 Holland(1980)의 파라미터 모델을 이용하여 태풍시의 해상풍을 구축하고, WAM 모형을 이용하여 태풍에 의한 파랑을 수치 계산하였다. 남해안의 부산, 목포, 여수, 서귀포 지역에 영향을 미친 태풍을 선정하고 가상의 태풍을 추가하여 training set을 구성하고, 남향 계열의 7개 파향에 대해서 경험모의기법을 적용하여 재현기간별 설계 파고를 산정하였다. 또한, 이를 POT 방법과 한국해양연구원(2005)의 결과와 비교, 분석하였다.

• International Journal of CAD/CAM
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• 제7권1호
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• pp.31-40
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• 2007

Reverse engineering of reliefs aims to turn an existing relief superimposed on an underlying surface into a geometric model which may be applied to a different base surface. Steps in this process include segmenting the relief from the background, and describing it as an offset height field relative to the underlying surface. We have previously considered relief segmentation using a geometric snake. Here, we show how to use this initial segmentation to estimate the background surface lying under the relief, which can be used (i) to refine the segmentation and (ii) to express the relief as an offset field. Our approach fits a B-spline surface patch to the measured background data surrounding the relief, while tension terms ensure this background surface smoothly continues underneath the relief where there are no measured background data points to fit. After making an initial estimate of relief offset height everywhere within the patch, we use a support vector machine to refine the segmentation. Tests demonstrate that this approach can accurately model the background surface where it underlies the relief, providing more accurate segmentation, as well as relief height field estimation. In particular, this approach provides significant improvements for relief concavities with narrow mouths and can segment reliefs with small internal holes.

• 대한원격탐사학회지
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• 제18권5호
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• pp.255-261
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• 2002

Strong and coherent radar backscattering signals are observed over oyster sea farms that consist of artificial structures installed on the bottom. We successfully obtained 21 coherent interferograms from 11 JERS-1 SAR data sets even though orbital baselines (up to 2 km) or temporal baselines (up to 1 year) were relatively large. The coherent phases preserved in the sea farms are probably formed by double bouncing from sea surface and the sea farming structures, and consequently they are correlated with tide height (or instantaneous sea level). Phase unwrapping is required to restore the absolute sea level. We show that radar backscattering intensity is roughly correlated with the sea surface height, and utilize the fact to determine the wrapping counts. While the SAR image intensity gives a rough range of absolute sea level, the interferometric phases provide the detailed relative height variations within a limit of $2{\pi}$ (or 15.3 cm) with respect to the sea level at the moment of the master data acquisition. A combined estimation results in an instantaneous sea level. The radar measurements were verified using tide gauge records, and the results yielded a correlation coefficient of 0.96 with an r.m.s. error of 6.0 cm. The results demonstrate that radar interferometry is a promising approach to sea level measurement in the near coastal regions.

• 농업과학연구
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• 제47권2호
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• pp.315-326
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• 2020

In this study, a real-time crop recognition system was developed for an unmanned farm machine for upland farming. The crop recognition system was developed based on a stereo camera, and an image processing framework was proposed that consists of disparity matching, localization of crop area, and estimation of crop height with coordinate transformations. The performance was evaluated by attaching the crop recognition system to a tractor for five representative crops (cabbage, potato, sesame, radish, and soybean). The test condition was set at 3 levels of distances to the crop (100, 150, and 200 cm) and 5 levels of camera height (42, 44, 46, 48, and 50 cm). The mean relative error (MRE) was used to compare the height between the measured and estimated results. As a result, the MRE of Chinese cabbage was the lowest at 1.70%, and the MRE of soybean was the highest at 4.97%. It is considered that the MRE of the crop which has more similar distribution lower. the results showed that all crop height was estimated with less than 5% MRE. The developed crop recognition system can be applied to various agricultural machinery which enhances the accuracy of crop detection and its performance in various illumination conditions.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.361-364
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• 2002

This paper discusses the influencing factors such as coring position, height to diameter ratio of core specimen(h/d) and coring torque on the strength estimation of concrete by small site coring method in order to verify the validities of small size core method. According to results, as for the influence of drilling position, when core specimens are obtained from the place parallel to placing direction, compressive strength of core specimens are higher than those perpendicular to placing direction. This is due to the loss of the area of core specimen perpendicular to plating direction by bleeding. And in case of $\phi$ 24mm core specimen, when vertical drilling against placing direction is taken. compressive strength of core specimen obtained at the bottom of the structure is higher than that at the top of the structure. As for the influence of height to depth ratio, as h/d ratio increases compressive strength shows to be decreased. As for the influences of rotation speed of drilling machine, as its speed goes up, compressive strength decreases, regardless of core diameter.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2006년도 춘계학술발표회 논문집
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• pp.305-309
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• 2006

SAR (Synthetic Aperture Radar) technology, which is not influenced by cloud cover because of using electromagnetic wave of long wavelength, has an advantage in mapping the earth. NASA, recognizing these strong points of SAR, launched SRTM (Shuttle Radar Topography klission), and acquired the topographic information of the earth. SRTM and NED (National Elevation Data) of USGS were used for the research and vegetation height map was produced through differentiating the two data. Correlation between SRTM-NED and planting year was analyzed to see the relationship. Strong correlation was detected and it shows the feasibility of estimating timber age and eventually creating timber age map from SRTM-NED. Additional analyses were conducted to check if the linearity is influenced by regional characteristics and forest uniformity. As results, the correlation between SRTM-NED and timber age is influenced by roughness of the terrain. Overall, this paper shows that timber age estimation using SRTM and NED can be sufficiently practical.

• 한국화재소방학회논문지
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• 제30권2호
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• pp.92-97
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• 2016

본 연구는 필드모델에서 소모된 연료에 기초하여 화학적 화염높이를 산정하기 위한 방법을 검토하고자 한다. 높이 방향으로 HRRPUL의 누적값과 연료농도에 따른 계산 알고리즘을 FDS 해석결과에 적용하였으며 평균화학적 화염높이는 알고리즘을 적용한 순간화염높이의 시간평균을 통해 산정하였다. 연료농도에 기초한 평균화염높이는 HRRPUL의 누적값에 의해 계산된 화염높이와 10% 이내의 상향예측범위에서 일치된 결과를 보였다. 이러한 연구는 전산화재해석모델에서 정량적인 화염높이를 산정하고 보다 상세한 화재거동특성을 이해하는데 기여하고자 한다.

• 노동경제논집
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• 제37권2호
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• pp.79-103
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• 2014

신장이 노동시장 성과에 미치는 영향을 분석한 문헌은 신장 프리미엄이 존재함을 보이면서도 능력을 통제하면 신장 프리미엄이 줄어든다고 하였다. 이는 신장 효과 추정 시 능력 변수를 적절히 통제하지 않으면 신장 효과가 과대 추정될 수 있음을 의미한다. 본고는 문헌 최초로 개인고정효과(FE) 모델을 사용하여 신장 효과를 추정한다. 최소자승법(OLS)으로 분석 시 키가 큰 남학생이 리더 포지션을 획득할 확률이 유의적으로 높으나, 개인고정효과를 통제하면 둘의 관계는 유의하지 않다. 여학생은 OLS, FE 모두 신장 프리미엄이 나타나지 않는다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.168-177
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• 2020

Many coastal engineering designs utilize empirical formulas containing the Equivalent Deep-water Wave Height (EDWH), which is normally given a priori. However, no studies have explicitly discussed a method for determining the EDWH and the resulting design wave heights (DEWH) under irregular wave conditions. Unfortunately, it has been the case in many design practices that the EDWH is incorrectly estimated by dividing the Shallow-water Wave Height (SWH) at the structural position with its corresponding shoaling coefficient of regular wave. The present study reexamines the relationship between the Shallow-water Wave Height (SWH) at the structural position and its corresponding EDWH. Then, a new procedure is proposed to facilitate the correct estimation of EDWH. In this procedure, the EDWH and DEWH are determined differently according to the wave propagation model used to estimate the SWH. For this, Goda's original method for nonlinear irregular wave deformation is extended to produce values for linear shoaling. Finally, exemplary calculations are performed to assess the possible errors caused by a misuse of the wave height calculation procedure. The relative errors with respect to the correct values could exceed 20%, potentially leading to a significant under-design of coastal or harbor structures in some cases.