• KIPS Transactions on Computer and Communication Systems
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• v.8 no.6
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• pp.139-150
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• 2019

IoT(Internet of Things) security is becoming increasingly important because IoT potentially has a variety of security threats, including limited hardware specifications and physical attacks. This paper is a study on the certification technology suitable for the lightened IoT environment, and we propose a system in which many gateways share authentication information and issue authentication tokens for mutual authentication using blockchain. The IoT node can be issued an authentication token from one gateway to continuously perform authentication with a gateway in the block-chain network using an existing issued token without performing re-authentication from another gateway participating in the block-chain network. Since we do not perform re-authentication for other devices in a blockchain network with only one authentication, we proposed multi phase authentication consisting of device authentication and message authentication in order to enhance the authentication function. By sharing the authentication information on the blockchain network, it is possible to guarantee the integrity and reliability of the authentication token.

• The Journal of the Korea Contents Association
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• v.18 no.12
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• pp.35-45
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• 2018

Motion Estimation(ME) has been developed to reduce the redundant data in digital video signal. ME is an important part of video encoding system, However, it requires huge computational complexity of the encoder part, and fast motion search methods have been proposed to reduce huge complexity. Multi- view video is obtained by capturing on a three-dimensional scene with many cameras at different positions and its complexity increases in proportion to the number of cameras. In this paper, we proposed an efficient motion method which chooses a search pattern adaptively by using the temporal-spatial correlation of the block and the characteristics of the block. Experiment results show that the computational complexity reduction of the proposed method over TZ search method and FS method can be up to 70~75% and 99% respectively while keeping similar image quality and bit rates.

• Geomechanics and Engineering
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• v.29 no.2
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• pp.145-154
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• 2022

Complex geological conditions have a great influence on the mining of coalbed methane (CBM), which affects the extraction efficiency of CBM. This investigation analyzed the complicated geological conditions in the Liujia CBM block of Fuxin. A geological model of heterogeneities CBM reservoirs was established to study the influence of strike direction of igneous rocks and fault structures on horizontal well layout. Subsequently, the dual-porosity and dual-permeability mathematical model was established, which considers the dynamic changes of porosity and permeability caused by gas adsorption, desorption, pressure change. The results show that the production curve is in good agreement with the actual by considering gas seepage in matrix pores in the model. Complicated geological structures affect the pressure expansion of horizontal wells, especially, the closer to the fault structure, the more significant the effect, the slower the pressure drop, and the smaller the desorption area. When the wellbore extends to the fault, the pressure expansion is blocked by the fault and the productivity is reduced. In the study area, the optimal distance to the fault is 70 m. When the horizontal wellbore is perpendicular to the direction of coal seam igneous rock, the productivity is higher than that of parallel igneous rock, and the horizontal well bore should be perpendicular to the cleat direction. However, the well length is limited due to the dense distribution of igneous rocks in the Liujia CBM block. Therefore, the horizontal well pumping in the study area should be arranged along the direction of igneous rock and parallel plane cleats. It is found that the larger the area surrounded by igneous rock, the more favorable the productivity. In summary, the reasonable layout of horizontal wells should make full use of the advantages of igneous rock, faults and other complex geological conditions to achieve the goal of high and stable production.

• Journal of the Korean Geotechnical Society
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• v.23 no.6
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• pp.5-21
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• 2007

Despite a number of advantages of reinforced earth walls over conventional concrete retaining walls, there exit concerns over long-term residual deformation when they are subjected to repeated and/or cyclic loads, especially when used as part of permanent structures. In view of these concerns, in this paper time-dependant deformation characteristics of geosynthetic reinforced modular block walls under sustained anuor repeated loads were investigated using reduced-scale model tests. The results indicated that a sustained or repeated load can yield appreciable magnitude of residual deformation, and that the residual deformations are influenced not only by the loading characteristics but by the mechanical properties of geogrid. It is also found that the preloading technique can be effectively used in controlling residual deformations of reinforced soils subjected to sustained and/or repeated loads.

• Journal of Chest Surgery
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• v.40 no.11
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• pp.752-758
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• 2007

Background: Thoracic sympathetic block surgery is a safe and effective procedure for palmar hyperhydrosis, and this maintains sufficient moisture and prevents compensatory hyperhidrosis. To avoid compensatory hyperhidrosis, the authors performed sympathetic block surgery just above the R4 level to maintain sympathetic tone affecting the caudal area. Material and Method: A total of 71 subjects (45 males and 26 females) were categorized into two groups. Group 1 (31 patients, mean age: 25.5 years) had clips placed both on the upper and lower part of R4 sympathetic ganglion, and group 2 (40 patients, mean age: 25.9 years) underwent clipping of the upper part of R4. Telephone surveys were done to collect data on 8 categories, and the average follow up interval was 24.9 months (group 1) and 18.9 months (group 2). Result: For group 1, 41.9% experienced no sweating and 48.4% re-plied they experienced some sweating depending on the surrounding conditions. Group 2 showed that 60% experienced no sweating and 35% replied they experienced some sweating depending on the surrounding conditions, 58.1% in group 1 experienced sweating right after the surgery, and 40.0% in group 2 experienced the same. Group 1 (38.1%) and group 2 (37.5%) replied they experienced no hand dryness and more patients in group 2 than in group 1 had hand dryness, but without uncomfortable symptoms. 71.0% (group 1) and 62.5% (group 2) replied they had no compensatory hyperhidrosis or related symptoms. One patient in group 1 and two in group 2 reported they regretted undergoing the procedure. The regions of compensatory hyperhidrosis were the back, thigh and chest in group 1 and the group 2 reported the back, chest, and abdomen in the order of frequency. Fewer incidences of the gustatory hyperhidrosis were noted in group 2. Most of the patients were satisfied with their treatment. Conclusion: Clipping the upper part of the R4 ganglion or R4 sympathetic block are both effective for treating palmar hyperhidrosis and these treatments decrease the occurrence or symptoms of compensatory hyperhidrosis. The upper R4 sympathetic block procedure is easier and safer with fewer incidences of gustatory hyperhidrosis and a higher percentage of patient satisfaction.

• Journal of Conservation Science
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• v.32 no.2
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• pp.203-213
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• 2016

Conservation treatment of modern cultural heritage rickshaw from National Museum of Korean Contemporary History were carried out. The Rickshaw is divided into three parts which are chair part, sun-block cover part, wheels part. Treatment was referred to analysis results of P-XRF, species identification, FT-IR and microscope observation on Rickshaw. Outer films of rickshaw were chipped off. Therefore, conservation and restoration treatment were carried out in the damaged area. Degradation in armrest, saddle and backside of chair may cause serious problem. Therefore, the reinforcement were carried out with similar materials. Dry and wet cleaning were performed in sun-block cover to remove white stain and corrosion contaminant. Furthermore, reinforcement and restoration were performed in damaged area. Rickshaw from National Museum of Korean Contemporary History was made with various materials. This research result expects to be a great example of conservation treatment for modern cultural heritage which is made of various materials and to be used as useful data for conservation and restoration in modern cultural heritage.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.6
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• pp.793-800
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• 2016

Most hinnies (female donkey${\times}$male horse) and mules (female horse${\times}$male donkey) are sterile with few reports of equine fertile hybrids. The main cause of this sterility is thought to be a meiotic block to spermatogenesis and oogenesis. This study compared the developmental features of the testes and a histological analyses of spermatogenesis in a male hinny with those of a normal, fertile stallion and Jack donkey. Hinny testes showed a thicker tunica albuginea, fewer blood vessels and more connective tissue in the testis parenchyma than those of the stallion and Jack donkey. Although the mean number of seminiferous tubules was significantly higher in stallion and hinny than Jack donkey (p<0.01), the mean proportion of seminiferous tubules was lower in the hinny (p<0.01) which resulted in a smaller diameter of seminiferous tubules. The mean number of spermatogonia and spermatocytes per unit area were significantly lower in hinny testis (p<0.01) and no spermatids or mature spermatozoa cells were found during immunofluorescent analyses. These results indicated that defects in seminiferous tubule development and structure occur in the testis of hinnies. Furthermore, most spermatogonia and spermatocytes cease development in synapsis during mid-meiosis of spermatocytes, which results in a block to spermatogenesis that prevents the formation of spermatids and matured spermatozoa during meiosis in male hinnies.

• Journal of KIISE:Software and Applications
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• v.31 no.9
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• pp.1142-1149
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• 2004

Motion Estimation(ME) has been developed to reduce temporal redundancy in digital video signals and increase data compression ratio. ME is an Important part of video encoding systems, since it can significantly affect the output quality of encoded sequences. However, ME requires high computational complexity, it is difficult to apply to real time video transmission. for this reason, motion estimation algorithms with low computational complexity are viable solutions. In this paper, we present an efficient method with low computational complexity based on spatial and temporal correlations of motion vectors. The proposed method uses temporally and spatially correlated motion information, the motion vector of the block with the same coordinate in the reference frame and the motion vectors of neighboring blocks around the current block in the current frame, to decide the search pattern and the location of search starting point adaptively. Experiments show that the image quality improvement of the proposed method over MVFAST (Motion Vector Field Adaptive Search Technique) and PMVFAST (Predictive Motion Vector Field Adaptive Search Technique) is 0.01～0.3(dB) better and the speedup improvement is about 1.12～l.33 times faster which resulted from lower computational complexity.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.2
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• pp.163-172
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• 2005

When tracking a human face in the moving pictures with complex background under irregular lighting conditions, the detected face can be larger including background or smaller including only a part of the face. Even background can be detected as a face area. To solve these problems, this paper proposes a new face tracking method using a block difference image and a Kalman estimator. The block difference image allows us to detect even a small motion of a human and the face area is selected using the skin color inside the detected motion area. If the pixels with skin color inside the detected motion area, the boundary of the area is represented by a code sequence using the 8-neighbor window and the head area is detected analysing this code. The pixels in the head area is segmented by colors and the region most similar with the skin color is considered as a face area. The detected face area is represented by a rectangle including the area and its four vertices are used as the states of the Kalman estimator to trace the motion of the face area. It is proved by the experiments that the proposed method increases the accuracy of face detection and reduces the fare detection time significantly.

• Journal of the Korean Geophysical Society
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• v.5 no.3
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• pp.199-209
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• 2002

We have carried out a nondestructive close examination for the purpose of the structural safety diagnosis of the Dabo Pagoda of Bulkuk temple located in Kyungju, Kyungbuk Korea. For estimating the mechanical properties of each rock block of the pagoda, ultrasonic measurements were conducted at 641 points of 255 blocks. The P-wave velocity ranges from 584m/sec through 5,169m/sec, and averages 2,901m/sec Based on this result, the uniaxial compressive strength was estimated to be $93{\sim}1,943kg/cm^2\;with\;396kg/cm^2$ of average, and the index of weathering is $0.07{\sim}0.88$ with 0.43 of average, which means the moderate degree of weathering. The comparison of the rock strength of each block with the overburden acting on the block reveals that the rock blocks related to the structure of the pagoda are relatively sound for uniform stress, but it is highly possible for a concentrated stress to lead to a partial failure. We suggest a monitoring of cracks due to the concentrated stress. The parapets of 1st and 2nd floors composed of small rock pieces are severely weathered. However, this is not directly related to the structural safety of the pagoda.