• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.37 no.4
• /
• pp.243-251
• /
• 2019

The road sign location information installed on national roads is continuously updated using MMS (Mobile Mapping System) technology. It is possible to map accurate road facilities by MMS, but the equipment is very expensive and requires specialized technology. Also, the accuracy of the position of the object greatly depends on the GPS (Global Positioning System) accuracy. In the case of road facility mapping, the advantage of drone is more remarkable than that of field survey or conventional aerial photogrammetry. In particular, it is more efficient than field surveying and it is possible to acquire high resolution images with low budget compared to conventional aerial photogrammetry. In this study, the accuracy of the location information measured by the existing MMS is compared with the GPS survey result and the accuracy analysis is performed by the drone aerial photogrammetry. In order to confirm the space accuracy that can be obtained when conducting drone aerial photogrammetry, the accuracy of the change in the number of ground control points and the degree of overlap was evaluated. As a result of the experiment, it was possible to obtain sufficient accuracy with two ground control points distributed at both ends of the road and 60% overlap.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.7
• /
• pp.630-637
• /
• 2019

The scientific, economical and industrial values of the Moon have been increased, as massive ice-water and rare resource were founded from the lunar exploration missions. Korea and other major space agencies in the world are competitively developing the ISRU (In Situ Resource Utilization) technology to secure future lunar resource as well as to construct the lunar base. To prepare for the lunar construction, it is essential to develop the rover based construction spatial information technology to provide a decision-making aided information during the lunar construction process. Thus, this research presented the construction spatial information technology based upon rover's camera system. Specifically, the conceptual design of rover based camera system was designed for acquisition of a rover's navigation image, and lunar terrain and construction images around the rover. The reference architecture of the rover operation system was designed for computation of the lunar construction spatial information. Also, rover's localization and terrain reconstruction methods were introduced considering the characteristics of lunar surface environments. It is necessary to test and validate the conceptual design of the construction spatial information technology. Thus, in the future study, the developed rover and rover operation system will be applied to the lunar terrestrial analogue site for further improvements.

• Journal of Korean Neurosurgical Society
• /
• v.62 no.4
• /
• pp.432-441
• /
• 2019

Objective : Few studies have reported direct comparative data of lumbar spine angles between direct lateral interbody fusion (DLIF) and oblique lateral interbody fusion (OLIF). The purpose of this study was to investigate the clinical and radiological outcomes of DLIF and OLIF, and determine influential factors. Methods : The same surgeon performed DLIF from May 2011 to August 2014 (n=201) and OLIF from September 2014 to September 2016 (n=142). Radiological parameters, cage height, cage angle (CA), cage width (CW), and cage location were assessed. We checked the cage location as the distance (mm) from the anterior margin of the disc space to the anterior metallic indicator of the cage in lateral images. Results : There were significant differences in intervertebral foramen height (FH; $22.0{\pm}2.4$ vs. $21.0{\pm}2.1mm$, p<0.001) and sagittal disc angle (SDA; $8.7{\pm}3.3$ vs. $11.3{\pm}3.2^{\circ}$, p<0.001) between the DLIF and OLIF groups at 7 days postoperatively. CA ($9.6{\pm}3.0$ vs. $8.1{\pm}2.9^{\circ}$, p<0.001) and CW ($21.2{\pm}1.6$ vs. $19.2{\pm}1.9mm$, p<0.001) were significantly larger in the OLIF group compared to the DLIF group. The cage location of the OLIF group was significantly more anterior than the DLIF group ($6.7{\pm}3.0$ vs. $9.1{\pm}3.6mm$, p<0.001). Cage subsidence at 1 year postoperatively was significantly worse in the DLIF group compared to the OLIF group ($1.0{\pm}1.5$ vs. $0.4{\pm}1.1mm$, p=0.001). Cage location was significantly correlated with postoperative FH (${\beta}=0.273$, p<0.001) and postoperative SDA (${\beta}=-0.358$, p<0.001). CA was significantly correlated with postoperative FH (${\beta}=-0.139$, p=0.044) and postoperative SDA (${\beta}=0.236$, p=0.001). Cage location (${\beta}=0.293$, p<0.001) and CW (${\beta}=-0.225$, p<0.001) were significantly correlated with cage subsidence. Conclusion : The cage location, CA, and CW seem to be important factors which result in the different-radiological outcomes between DLIF and OLIF.

• Tunnel and Underground Space
• /
• v.31 no.1
• /
• pp.41-51
• /
• 2021

The hydraulic fracturing developed to improve permeability of tight reservoir is one of key stimulation technologies for developing unconventional resources such as shale gas and deep geothermal energy. The experimental study was conducted to improve disadvantage of hydraulic fracturing which has simple fracture pattern and poor fracturing efficiency. The fracturing experiments was conducted for tight rock using various fracturing fluids, water, N2, and CO2 and the created fracture pattern and fracturing efficiency was analyzed depending on fracturing fluids. The borehole pressure increased rapidly and then made fractures for hydraulic fracturing with constant injection rate, however, gas fracturing shows slowly increased pressure and less fracture pressure. The 3D tomography technic was used to generate images of induced fracture using hydraulic and gas fracturing. The stimulated reservoir volume (SRV) was estimated increment of 5.71% (water), 12.72% (N2), and 43.82% (CO2) respectively compared to initial pore volume. In addition, permeability measurement was carried out before and after fracturing experiments and the enhanced permeability by gas fracturing showed higher than hydraulic fracturing. The fracture conductivity was measured by increasing confining stress to consider newly creating fracture and closing induced fracture right after fracturing. When the confining stress was increased from 2MPa to 10MPa, the initial permeability was decreased by 89% (N2) and 50% (CO2) respectively. This study shows that the gas fracturing makes more permeability enhancement and less reduction of induced fracture conductivity than hydraulic fracturing.

• (The)Study of the Eastern Classic
• /
• no.70
• /
• pp.33-58
• /
• 2018

The purpose of this paper is to clarify the life and poetry of Dokshok Hwang Hyok. In Chapter 2, we looked at the life of Hwang Hyok. There are two characteristics in the life of Hwang Hyok. First, Hwang Hyok had excellent literary talent. Secondly, Hwang Hyok wrote in an attempt to surrender during the Japanese Invasion of Japan. That is why he lived a 21 year detained life. In Chapter 3, we looked at poetry based on the life of Hwang Hyok. The features of poetry are as follows. First, the image of Somu and reality of Tiger and Dhole go around. Hwang Hyok lived a confined life because of the Japanese Invasion of Korea. Because of that, Hwang Hyok recognized the Japanese invasion of the Imperial Japan as a world where Dhole and tigers travel around. It symbolized the image of Sommu that he did not surrender. Second, Changsha, is the world and Gulwon images. Changsha is Gulwon the space of self-destruction. Hwang Hyok likened his dark life to Gulwon dead. This is because Hwang Hyok's life is similar to Gulwon's life. In other words, Hwang Hyok was most appropriate to compare his tough life to Gulwon, who drowned in Myeoglasu.

• Journal of the Korea Computer Graphics Society
• /
• v.27 no.5
• /
• pp.63-71
• /
• 2021

Among drone autonomous flight technologies, obstacle avoidance is a very important technology that can prevent damage to drones or surrounding environments and prevent danger. Although the LiDAR sensor-based obstacle avoidance method shows relatively high accuracy and is widely used in recent studies, it has disadvantages of high unit price and limited processing capacity for visual information. Therefore, this paper proposes an obstacle avoidance algorithm for drones using camera-based PPO(Proximal Policy Optimization) reinforcement learning, which is relatively inexpensive and highly scalable using visual information. Drone, obstacles, target points, etc. are randomly located in a learning environment in the three-dimensional space, stereo images are obtained using a Unity camera, and then YOLov4Tiny object detection is performed. Next, the distance between the drone and the detected object is measured through triangulation of the stereo camera. Based on this distance, the presence or absence of obstacles is determined. Penalties are set if they are obstacles and rewards are given if they are target points. The experimennt of this method shows that a camera-based obstacle avoidance algorithm can be a sufficiently similar level of accuracy and average target point arrival time compared to a LiDAR-based obstacle avoidance algorithm, so it is highly likely to be used.

• Tunnel and Underground Space
• /
• v.31 no.6
• /
• pp.400-414
• /
• 2021

Under high-level radioactive waste repository conditions, bentonite as an engineered barrier material undergoes thermal, hydrological, mechanical, and chemical processes. We report the applications of X-ray Computed Tomography (CT) imaging technique on the characterization and analysis of bentonite over the past decade to provide a reference of the utilization of this technique and the recent research trends. This overview of the X-ray CT technique applications includes the characterization of the bentonite either in pellets or powder form. X-ray imaging has provided a means to extract grain information at the microscale and identify crack networks responsible for the pellets' heterogeneity. Regarding samples of pellets-powder mixtures under hydration, X-ray CT allowed the identification and monitoring of heterogeneous zones throughout the test. Some results showed how zones with pellets only swell faster compared to others composed of pellets and powder. Moreover, the behavior of fissures between grains and bentonite matrix was observed to change under drying and hydrating conditions, tending to close during the former and open during the latter. The development of specializing software has allowed obtaining strain fields from a sequence of images. In more recent works, X-ray CT technique has served to estimate the dry density, water content, and particle displacement at different testing times. Also, when temperature was added to the hydration process of a sample, CT technology offered a way to observe localized and global density changes over time.

• Journal of the Korean Society of Floral Art and Design
• /
• no.42
• /
• pp.117-132
• /
• 2020

The study aimed at trying to contribute to domestic floral designers by analyzing colors' images of 60 floral designs of British floral designers, Shane Connolly and Paula Pryke, as the basis for color scheme of floral space design. The result of color analysis, Shane Connolly uses colors in the frequency of color order of the GY>Y>RP>YR>P>P>PB and Paula Pryke uses colors in the frequency of color order of the GY>RP>P>YR,Y>G>PB. The result of coordinate analysis of hue, value, chrome, Shane Connolly's works showed high frequency in the YtoGY color, the middle and high of value and the middle and high of chrome. Paula Pryke's works showed high frequency in the GY color and PtoRP color, the wide areas of the 3.8 ~9 stages of value, and the middle and high of chrome. The result of adjective image scale, Shane Connolly's works were found to be in between soft and static adjective zone, and Paula Pryke's works were distributed in between soft and active zone.

• Journal of Broadcast Engineering
• /
• v.26 no.6
• /
• pp.692-703
• /
• 2021

Recently, with the development of computer graphics technology, research on technology for expressing real objects as more realistic virtual graphics is being actively conducted. Point cloud is a technology that uses numerous points, including 2D spatial coordinates and color information, to represent 3D objects, and they require huge data storage and high-performance computing devices to provide various services. Video-based Point Cloud Compression (V-PCC) technology is currently being studied by the international standard organization MPEG, which is a projection based method that projects point cloud into 2D plane, and then compresses them using 2D video codecs. V-PCC technology compresses point cloud objects using 2D images such as Occupancy map, Geometry image, Attribute image, and other auxiliary information that includes the relationship between 2D plane and 3D space. When increasing the density of point cloud or expanding an object, 3D calculation is generally used, but there are limitations in that the calculation method is complicated, requires a lot of time, and it is difficult to determine the correct location of a new point. This paper proposes a method to generate additional points at more accurate locations with less computation by applying 2D interpolation to the image on which the point cloud is projected, in the V-PCC technology.

• Journal of the Korea Society of Computer and Information
• /
• v.27 no.2
• /
• pp.33-42
• /
• 2022

In this paper, we proposed a deep learning model based on multi-scale dilated convolution feature fusion for the segmentation of black ice region in road image to send black ice warning to drivers in real time. In the proposed multi-scale dilated convolution feature fusion network, different dilated ratio convolutions are connected in parallel in the encoder blocks, and different dilated ratios are used in different resolution feature maps, and multi-layer feature information are fused together. The multi-scale dilated convolution feature fusion improves the performance by diversifying and expending the receptive field of the network and by preserving detailed space information and enhancing the effectiveness of diated convolutions. The performance of the proposed network model was gradually improved with the increase of the number of dilated convolution branch. The mIoU value of the proposed method is 96.46%, which was higher than the existing networks such as U-Net, FCN, PSPNet, ENet, LinkNet. The parameter was 1,858K, which was 6 times smaller than the existing LinkNet model. From the experimental results of Jetson Nano, the FPS of the proposed method was 3.63, which can realize segmentation of black ice field in real time.