• Journal of Korea Society of Digital Industry and Information Management
• /
• v.8 no.2
• /
• pp.95-104
• /
• 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.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.23 no.4
• /
• pp.265-275
• /
• 2011

Estimation of wave height is the most important factor in the design of coastal structures such as breakwaters. In the present study, typhoon wind distribution was constructed by applying the parametric model of Holland (1980), and numerical simulations on the typhoon-generated waves were carried out using the WAM. The typhoons which affected the southern coast of the Korean Peninsula and several hypothetical typhoons were selected to construct the training sets. Design wave heights were estimated using the empirical simulation technique for various return periods and wave directions. The estimated design wave heights were compared with those by the peaks-over-threshold method and the results of KORDI(2005).

• International Journal of CAD/CAM
• /
• v.7 no.1
• /
• pp.31-40
• /
• 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.

• Korean Journal of Remote Sensing
• /
• v.18 no.5
• /
• pp.255-261
• /
• 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.

• Korean Journal of Agricultural Science
• /
• v.47 no.2
• /
• pp.315-326
• /
• 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.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2002.10a
• /
• pp.361-364
• /
• 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.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
• /
• 2006.04a
• /
• pp.305-309
• /
• 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.

• Fire Science and Engineering
• /
• v.30 no.2
• /
• pp.92-97
• /
• 2016

The present study has been conducted to estimate the chemical flame height based on fuel consumption in fire field model. The calculation algorithms based on cumulative fraction of HRRPUL and fuel concentration along the z axis were applied to the results predicted by Fire Dynamics Simulator (FDS) version 6.3.2 and the mean chemical flame height was obtained by time averaging of instantaneous flame height with the algorithms. The mean flame height calculated by fuel concentration was quite well matched with that of cumulative value of HRRPUL within 10% over-prediction. This study contribute to a more detailed understanding of fire behavior and quantitative evaluation of flame height in the computational fire model.

• Journal of Labour Economics
• /
• v.37 no.2
• /
• pp.79-103
• /
• 2014

Previous studies show that tall people have better labor market outcomes, but controlling for their abilities reduces the size of height effects. This implies that a failure to properly control for one's ability could overestimate the OLS estimate. This paper contributes to the literature by being the first to control for individual fixed effects (FE) and to examine height effects on the probability of one's attaining a leadership position. The data used are panel data of a cohort obtained during the cohort's middle and high school years. In OLS estimation, this paper finds positive height effects for boys. However, when controlling for individual fixed effects, the estimate is not statistically significant. For girls, the height effects are found on neither OLS nor FE model.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.12 no.1
• /
• pp.168-177
• /
• 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.