• Proceedings of the Korea Water Resources Association Conference
• /
• 2019.05a
• /
• pp.152-152
• /
• 2019

This study demonstrates a novel approach of remotely sensed estimates of stream flow at fifteen hydrological station in the Han River Basin, Korea. Multi-temporal data of the European Space Agency's Sentinel-1 SAR satellite from 19 January, 2015 to 25 August, 2018 is used to develop and validate the flow estimation model for each station. The flow estimation model is based on a power law relationship established between the remotely sensed surface area of water at a selected reach of the stream and the observed discharge. The satellite images were pre-processed for thermal noise, radiometric, speckle and terrain correction. The difference in SAR image brightness caused by the differences in SAR satellite look angle and atmospheric condition are corrected using the histogram matching technique. Selective area filtering is applied to identify the extent of the selected stream reach where the change in water surface area is highly sensitive to the change in stream discharge. Following this, an iterative procedure called the Optimum Threshold Classification Algorithm (OTC) is applied to the multi-temporal selective areas to extract a series of water surface areas. It is observed that the extracted water surface area and the stream discharge are related by the power law equation. A strong correlation coefficient ranging from 0.68 to 0.98 (mean=0.89) was observed for thirteen hydrological stations, while at two stations the relationship was highly affected by the hydraulic structures such as dam. It is further identified that the availability of remotely sensed data for a range of discharge conditions and the geometric properties of the selected stream reach such as the stream width and side slope influence the accuracy of the flow estimation model.

• YAKHAK HOEJI
• /
• v.56 no.6
• /
• pp.401-406
• /
• 2012

Previously, we identified that Cirsium japonicum (CJ) extract posses antidepressant properties. In order to look for the optimal hebal preparation, CJ extracts collected from Koheung, Yesan, Cheju, Pyungchang and Pocheon were compared. The psychopharmacological activities of each extract were investigated using the open field test, the rota-rod test and the forced swimming test. Effect of each extract on $Cl^-$ influx in neuroblastoma cells were also identified. All of the extracts were orally administered at dosages of 50, 100, 200, 400 mg/kg of body weight. Supplementation of CJ did not significantly alter psychomotor behaviors such as movement, rearing frequency and total turn angle on the open field. Supplementation of CJ's extract from Pyungchang (100 mg/kg, p.o.), Cheju (200 and 400 mg/kg p.o.) and Yesan (100 and 200 mg/kg, p.o.) significantly decreased immobile duration and increased mobile duration in the forced swimming test. All of extracts have no influence on NE uptake in HEK-293 cells, but increased $Cl^-$ influx in neuroblastoma cell. The extract from Yesan demonstrated the most potent effect on $Cl^-$ influx. These results indicate that CJ's extracts from Pyungchang, Cheju and Yesan may alleviate depression, and the extract from Yesan may be the most effective preparation.

• Korean Journal of Optics and Photonics
• /
• v.29 no.6
• /
• pp.253-261
• /
• 2018

In this paper, we study a method of designing a reflector for LED light sources with an asymmetric light distribution. In a sports game, lighting with a symmetric distribution makes the athlete and spectators look directly at the light source, so it can cause glare. We derive the optimal tilt angle and design a reflector with asymmetric light distribution to solve these problems. Afterward, performance is analyzed according to the tennis-court lighting standard, and is confirmed to meet the class 1 European standard.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.49 no.2
• /
• pp.121-128
• /
• 2021

In this paper, we propose a path generation and tracking algorithm of an unmanned air vehicle in a two-dimensional plane given the initial and final points. The path generation algorithm using the Dubins curve proposed in this work has the advantage that it can be applied in real time to an unmanned air vehicle. The path tracking algorithm is an algorithm similar to the line-of-sight induction algorithm. In order to efficiently control the direction angle, a gain related to the look ahead distance concept is introduced. Most of UAVs have the limited maximum curvature due to the structural constraints. A numerical simulation is conducted to follow the path generated by the sliding mode controller considering the angular velocity limit. The path generation and tracking performance is verified by comparing the suggested controller with conventional control techniques.

• Journal of Animal Science and Technology
• /
• v.63 no.6
• /
• pp.1453-1463
• /
• 2021

Feeding is the most important behavior that represents the health and welfare of weanling pigs. The early detection of feed refusal is crucial for the control of disease in the initial stages and the detection of empty feeders for adding feed in a timely manner. This paper proposes a real-time technique for the detection and recognition of small pigs using a deep-leaning-based method. The proposed model focuses on detecting pigs on a feeder in a feeding position. Conventional methods detect pigs and then classify them into different behavior gestures. In contrast, in the proposed method, these two tasks are combined into a single process to detect only feeding behavior to increase the speed of detection. Considering the significant differences between pig behaviors at different sizes, adaptive adjustments are introduced into a you-only-look-once (YOLO) model, including an angle optimization strategy between the head and body for detecting a head in a feeder. According to experimental results, this method can detect the feeding behavior of pigs and screen non-feeding positions with 95.66%, 94.22%, and 96.56% average precision (AP) at an intersection over union (IoU) threshold of 0.5 for YOLOv3, YOLOv4, and an additional layer and with the proposed activation function, respectively. Drinking behavior was detected with 86.86%, 89.16%, and 86.41% AP at a 0.5 IoU threshold for YOLOv3, YOLOv4, and the proposed activation function, respectively. In terms of detection and classification, the results of our study demonstrate that the proposed method yields higher precision and recall compared to conventional methods.

• The Journal of Korea Robotics Society
• /
• v.17 no.2
• /
• pp.142-151
• /
• 2022

With the advent of the 4th industrial revolution, autonomous driving technology is being commercialized in various industries. However, research on autonomous driving so far has focused on platforms with wheel-type platform. Research on a tracked platform is at a relatively inadequate step. Since the tracked platform has a different driving and steering method from the wheel-type platform, the existing research cannot be applied as it is. Therefore, a path-tracking algorithm suitable for a tracked platform is required. In this paper, we studied a path-tracking algorithm for a tracked platform based on a GPS sensor. The existing Pure Pursuit algorithm was applied in consideration of the characteristics of the tracked platform. And to compensate for "Cutting Corner", which is a disadvantage of the existing Pure Pursuit algorithm, an algorithm that changes the LAD according to the curvature of the path was developed. In the existing pure pursuit algorithm that used a tracked platform to drive a path including a right-angle turn, the RMS path error in the straight section was 0.1034 m and the RMS error in the turning section was measured to be 0.2787 m. On the other hand, in the variable LAD algorithm, the RMS path error in the straight section was 0.0987 m, and the RMS path error in the turning section was measured to be 0.1396 m. In the turning section, the RMS path error was reduced by 48.8971%. The validity of the algorithm was verified by measuring the path error by tracking the path using a tracked robot platform.

• School Mathematics
• /
• v.9 no.2
• /
• pp.277-289
• /
• 2007

This research aims to look into the mathematically gifted 6th and 7th graders spatial visualization ability of solid figures. The subjects of the research was six male elementary school students in the 6th grade and one male middle school student in the 1th grade receiving special education for the mathematically gifted students supported by the government. The task used in this research was the problems that compares the side lengths and the angle sizes in 4 pictures of its two dimensional representation of a regular icosahedron. The data collected included the activity sheets of the students and in-depth interviews on the problem solving. Data analysis was made based on McGee's theory about spatial visualization ability with referring to Duval's and Del Grande's. According to the results of analysis of subjects' spatial visualization ability, the spatial visualization abilities mainly found in the students' problem-solving process were the ability to visualize a partial configuration of the whole object, the ability to manipulate an object in imagination, the ability to imagine the rotation of a depicted object and the ability to transform a depicted object into a different form. Though most subjects displayed excellent spatial visualization abilities carrying out the tasks in this research, but some of them had a little difficulty in mentally imagining three dimensional objects from its two dimensional representation of a solid figure.

• Korean Journal of Remote Sensing
• /
• v.29 no.1
• /
• pp.11-20
• /
• 2013

Space-borne Synthetic Aperture Radar(SAR) has been one of the most effective tools for monitoring quantitative oceanographic physical parameters. The Doppler information recorded in single-channel SAR raw data can be useful in estimating moving velocity of water mass in ocean. The Doppler shift is caused by the relative motion between SAR sensor and the water mass of ocean surface. Thus, the moving velocity can be extracted by measuring the Doppler anomaly between extracted Doppler centroid and predicted Doppler centroid. The predicted Doppler centroid, defined as the Doppler centroid assuming that the target is not moving, is calculated based on the geometric parameters of a satellite, such as the satellite's orbit, look angle, and attitude with regard to the rotating Earth. While the estimated Doppler shift, corresponding to the actual Doppler centroid in the situation of real SAR data acquisition, can be extracted directly from raw SAR signal data, which usually calculated by applying the Average Cross Correlation Coefficient(ACCC). The moving velocity was further refined to obtain ocean surface current by subtracting the phase velocity of Bragg-resonant capillary waves. These methods were applied to Envisat ASAR raw data acquired in the East Sea, and the extracted ocean surface currents were compared with the current measured by HF-radar.

• Journal of Fashion Business
• /
• v.11 no.5
• /
• pp.35-50
• /
• 2007

The purpose of this study was to investigate the result of a market research on men's jacket in their age of 25 to 35, who wear fitted jackets most, and to examine the comparative analysis of pattern and the wearing evaluation between classic jacket and fitted jacket. The results are as follows; Firstly, according to the results of a market research, 32.0% of the target owned fitted jackets, and 28.7% expressed their desire to buy only fitted jackets. This means their concern and preference for fitted jacket with which they could show up young, fresh and slim look are as high as those for classic jacket. Secondly, classic jacket showed the higher value than fitted jacket in such items as chest girth, waist girth, hip girth, sleeve's hem girth, jacket length, shoulder length, side seam length, and across shoulder point length. On the other hand, fitted jacket showed the higher value than classic jacket in back armhole length, front length, collar point length and sleeve's vent length. Thirdly, classic jacket was larger than fitted jacket in 1/2 chest girth(1.0cm), 1/2 waist girth(2.0cm), 1/2 hip girth(1.0cm), back width(0.5cm), front width(0.5cm) and side width(1.0cm). However, fitted jacket was higher than classic jacket in the armhole depth(0.5). Fourthly, the results of appearance evaluation revealed that there was a significant difference in 6 items. In other words, classic jacket was evaluated more appropriate than fitted jacket in such items as back width, back length, back neck depth, chest girth, waist girth and hip girth. And the fitted jacket had a higher value than the classic jacket in shoulder angle item. Fifthly, In the functional evaluation, fitted jacket was evaluated more uncomfortable than classic jacket. And this means that fitted jacket doesn't have a proper ease amount in each part and it has a high armhole depth compared to classic jacket. Therefore, for more comfortable patternmaking of fitted jackets, it would be required a pattern design which reflect men's own shoulder lines and women designers' flexibility that will satisfy both appearance and function.

• The Journal of the Korea Contents Association
• /
• v.10 no.6
• /
• pp.329-335
• /
• 2010

Digital imaging detectors can use a variety of detection materials to convert X-ray radiation either to light or directly to electron charge. Many detectors such as amorphous silicon flat panels, CCDs, and CMOS photodiode arrays incorporate a scintillator screen to convert x-ray to light. The digital radiography systems based on semiconductor detectors, commonly referred to as flat panel detectors, are gaining popularity in the clinical & hospital. The X-ray detectors are described between a-Silicon based indirect type and a-Selenium based direct type. The DRS of detectors is used to convert the x-ray to electron hole pairs. Image processing is described by specific image features: Latitude compression, Contrast enhancement, Edge enhancement, Look up table, Noise suppression. The image features are tuned independently. The final enhancement result is a combination of all image features. The parameters are altered by using specific image features in the different several hospitals. The image in a radiological report consists of two image evaluation processes: Clinical image parameters and MTF is a descriptor of the spatial resolution of a digital imaging system. We used the edge test phantom and exposure procedure described in the IEC 61267 to obtain an edge spread function from which the MTF is calculated. We can compare image in the processing parameters to change between original and processed image data. The angle of the edge with respect to the axes of detector was varied in order to determine the MTF as a function of direction. Each MTF is integrated within the spatial resolution interval of 1.35-11.70 cycles/mm at the 50% MTF point. Each image enhancement parameters consists of edge, frequency, contrast, LUT, noise, sensitometry curve, threshold level, windows. The digital device is also shown to have good uniformity of MTF and image parameters across its modality. The measurements reported here represent a comprehensive evaluation of digital radiography system designed for use in the DRS. The results indicate that the parameter enables very good image quality in the digital radiography. Of course, the quality of image from a parameter is determined by other digital devices in addition to the proper clinical image.