• The KIPS Transactions:PartC
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• v.9C no.1
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• pp.9-16
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• 2002

As existing analog video surveillance systems could save and retrieve data only in a limited space within short distance, it had many constraints in developing into various application systems. However, on the back of development of the Internet and computer technologies, digital video surveillance systems can be controlled from a remote location by web browser without space limits. Moreover, data compression and management technologies with Index Search algorithm make it possible to efficiently handling, storing, and retrieving a large amount of data and further motion detection algorithm enhances a recording speed and efficiency for a practical application, that is, a practical remote recordable video surveillance system using our efficient algorithms as mentioned, called WebCam. The WebCam server system can intelligently record and save video images digitized through efficient database management, monitor and control cameras in a remote place through user authentication, and search logs.

• Economic and Environmental Geology
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• v.49 no.1
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• pp.23-30
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• 2016

Powder samples of natural lawsonite (Ca-lawsonite, $CaAl_2Si_2O_7(OH)_2{\cdot}H_2O$) was studied structurally up to 8 GPa at room temperature using monochromatic synchrotron X-ray powder diffraction and a diamond anvil cell (DAC) with a methanol : ethanol : water (16 : 3 : 1 by volume) mixture solution as a penetrating pressure transmitting medium (PTM). Upon pressure increase, lawsonite does not show any apparent pressure induced expansion (PIE) or phase transition. Pressure-volume data were fitted to a second-order Birch-Murnaghan equation of state using a fixed pressure derivative of 4 leading to a bulk modulus ($B_0$) of 146(6) GPa. This compression is further characterized to be isotropic with calculated linear compressibilities of ${\beta}^a=0.0022GPa^{-1}$, ${\beta}^b=0.0024GPa^{-1}$, and ${\beta}^c=0.0020GPa^{-1}$.

• Geomechanics and Engineering
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• v.22 no.5
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• pp.385-396
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• 2020

A uniaxial compression test was performed to analyse the mechanical properties and macroscale and mesoscale failure mechanisms of sandstone with pyrite concretions. The effect of the pyrite concretions on the evolution of macroscale cracks in the sandstone was further investigated through numerical simulations with Particle Flow Code in 2D (PFC2D). The results revealed that pyrite concretions substantially influence the mechanical properties and macroscale and mesoscale failure characteristics of sandstone. During the initial loading stage, significant stress concentrations occurred around the edges of the pyrite concretion accompanied by the preferential generation of cracks. Meanwhile, the events and cumulative energy counts of the acoustic emission (AE) signal increased rapidly because of friction sliding between the concretion and sandstone matrix. As the axial stress increased, the degree of the stress concentration remained relatively unchanged around the edges of the concretions. The cracks continued growing rapidly around the edges of the concretions and gradually expanded toward the centre of the sample. During this stage, the AE events and cumulative energy counts increased quite slowly. As the axial stress approached the peak strength of the sandstone, the cracks that developed around the edges of the concretion started to merge with cracks that propagated at the top-left and bottom-right corners of the sample. This crack evolution ultimately resulted in the shear failure of the sandstone sample around the edges of the pyrite concretions.

• Geomechanics and Engineering
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• v.19 no.1
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• pp.49-60
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• 2019

Crack instability propagation during coal and rock mass failure is the main reason for electromagnetic radiation (EMR) generation. However, original cracks on coal and rock mass are hard to study, making it complex to reveal EMR laws and mechanisms. In this paper, we prefabricated cracks of different inclinations in coal and rock samples as the analogues of the native cracks, carried out uniaxial compression experiments using these coal and rock samples, explored, the effects of the prefabricated cracks on EMR laws, and verified these laws by measuring the surface potential signals. The results show that prefabricated cracks are the main factor leading to the failure of coal and rock samples. When the inclination between the prefabricated crack and axial stress is smaller, the wing cracks occur first from the two tips of the prefabricated crack and expand to shear cracks or coplanar secondary cracks whose advance directions are coplanar or nearly coplanar with the prefabricated crack's direction. The sample failure is mainly due to the composited tensile and shear destructions of the wing cracks. When the inclination becomes bigger, the wing cracks appear at the early stage, extend to the direction of the maximum principal stress, and eventually run through both ends of the sample, resulting in the sample's tensile failure. The effect of prefabricated cracks of different inclinations on electromagnetic (EM) signals is different. For samples with prefabricated cracks of smaller inclination, EMR is mainly generated due to the variable motion of free charges generated due to crushing, friction, and slippage between the crack walls. For samples with larger inclination, EMR is generated due to friction and slippage in between the crack walls as well as the charge separation caused by tensile extension at the cracks' tips before sample failure. These conclusions are further verified by the surface potential distribution during the loading process.

• Structural Engineering and Mechanics
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• v.69 no.5
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• pp.537-545
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• 2019

Stress analysis of bottom-hole rock has to be considered with much care to further understand rock fragmentation mechanism and high penetration rate. This original study establishes a fully coupled simulation model and explores the effects of overburden pressure, horizontal in-situ stresses, drilling mud pressure, pore pressure and temperature on the stress distribution in bottom-hole rock. The research finds that in air drilling, as the well depth increases, the more easily the bottom-hole rock is to be broken. Moreover, the mud pressure has a great effect on the bottom-hole rock. The bigger the mud pressure is, the more difficult to break the bottom-hole rock is. Furthermore, the maximum principal stress of the bottom-hole increases as the mud pressure, well depth and temperature difference increase. The bottom-hole rock can be divided into three main regions according to the stress state, namely a) three directions tensile area, b) two directions compression areas and c) three directions compression area, which are classified as a) easy, b) normal and c) hard, respectively, for the corresponding fragmentation degree of difficulty. The main contribution of this paper is that it presents for the first time a thorough study of the effect of related factors, including stress distribution and temperature, on the bottom-hole rock fracture rather than the well wall, using a thermo-poroelastoplasticity model.

• Asia-Pacific Journal of Business
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• v.10 no.3
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• pp.125-142
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• 2019

The study wanted to verify the effect of emotional sub-compression, a negative variable of emotional labor, on job performance, on security personnel working at private security companies, and further to verify how the impact on emotional sub-compression can affect job performance through the first draft of regulation. Empirical analysis through the study model showed that emotional edema was not a significant effect, but a negative effect on job performance, and that it did not affect the control focus itself. This revealed that emotional harmony has been shown to have a negative impact on performance due to the present state and conflicting situations in one's emotions, which means that emotional harmony does not affect negative or positive effects depending on a person's attributes. It also showed that the temperamental control focus on job performance had a positive impact on employees with an improvement focus and had a negative impact on employees with a preventive focus, and that a temperamental control focus between emotional dissonance and job performance had an effect. This indicated that job performance was affected by a temperamental control focus and that employees with an improvement focus had a positive effect and had a positive effect on performance. The implications of the study in this study are that it can have target differentiation in the areas where the study was conducted on guard workers, a social issue related to the study of emotional labor, and it can be meaningful that the study of emotional labor had a control focus and measured both positive and negative tendencies. It is also believed that there will be contributions to the verification of differences in performance resulting from employee propensity and by linking it with a variable called emotional instability. However, the data collected have the limitations of the subject and region, and the emphasis on cross-sectional analysis and the representative of the various emotions to verify the negative effects of emotional labor, and the problem of securing reliability related to the adjustment focus verification are the limitations of the research.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.6
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• pp.850-858
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• 2022

To deploy Gate Recurrent Units (GRU) on resource-constrained embedded devices, this paper presents a reconfigurable FPGA-based GRU accelerator that enables structured compression. Firstly, a dense GRU model is significantly reduced in size by hybrid quantization and structured top-k pruning. Secondly, the energy consumption on external memory access is greatly reduced by the proposed reuse computing pattern. Finally, the accelerator can handle a structured sparse model that benefits from the algorithm-hardware co-design workflows. Moreover, inference tasks can be flexibly performed using all functional dimensions, sequence length, and number of layers. Implemented on the Intel DE1-SoC FPGA, the proposed accelerator achieves 45.01 GOPs in a structured sparse GRU network without batching. Compared to the implementation of CPU and GPU, low-cost FPGA accelerator achieves 57 and 30x improvements in latency, 300 and 23.44x improvements in energy efficiency, respectively. Thus, the proposed accelerator is utilized as an early study of real-time embedded applications, demonstrating the potential for further development in the future.

• Progress in Superconductivity and Cryogenics
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• v.24 no.3
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• pp.57-61
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• 2022

One of the major applications of REBCO coated conductor (CC) tapes is in superconducting magnets or coils that are designed for high magnet fields. For such applications, the CC tapes were exposed to a high level of stresses which includes uniaxial tensile or transverse compressive stresses resulting from a large magnetic field. Thus, CC tapes should endure such mechanical load or deformation that can influence their electromechanical performance during manufacturing, cool-down, and operation. It has been reported that the main cause of critical current (I_c) degradation in CC tapes utilized in coil windings for superconducting magnets was the delamination due to transversely applied stresses. In most high-magnetic-field applications, the operating limits of the CC tapes will likely be imposed by the electromechanical properties together with its I_c dependence on temperature and magnetic field. In this study, we examined the influence of the transverse compressive stress on the I_c degradation behaviors in various commercially available CC tapes which is important for magnet design Four differently processed REBCO CC tapes were adopted to examine their I_c degradation behaviors under transverse compression using an anvil test method and a newly developed instantaneous I_c measurement system. As a result, all REBCO CC tapes adopted showed robustness against transverse compressive stresses for REBCO coils, notably at transverse compressive stresses until 250 MPa. When the applied stress further increased, different Ic degradation behaviors were observed depending on the sample. Among them, the one that was fabricated by the IBAD/MOCVD process showed the highest compressive stress tolerance.

• Journal of Korean Neurosurgical Society
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• v.66 no.3
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• pp.324-331
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• 2023

Objective : We aimed to analyze the effectiveness of external neurolysis on the common peroneal nerve (CPN) in patients with posture-induced compressive peroneal neuropathy (PICPNe). Further, we aimed to examine the utility of magnetic resonance imaging (MRI) in assessing the severity of denervation status and predicting the postoperative prognosis. Methods : We included 13 patients (eight males and five females) with foot drop who underwent CPN decompression between 2018 and 2020. We designed a grading system for assessing the postoperative functional outcome. Additionally, we performed MRI to evaluate the denervation status of the affected musculature and its effect on postoperative recovery. Results : The median time to surgery was 3 months. The median preoperative ankle dorsiflexion and eversion grades were both 3, while the average functional grade was 1. Posterior crural intermuscular septum was the most common cause of nerve compression, followed by deep tendinous fascia and anterior crural intermuscular septum. There was a significant postoperative improvement in the median postoperative ankle dorsiflexion and eversion grades and average postoperative functional (4, 5, and 2.38, respectively). Preoperative ankle eversion was significantly correlated with denervation status. Additionally, the devernation status on MRI was positively correlated with the outcome favorability. However, denervation atrophy led to a less favorable outcome. Conclusion : Among patients with intractable PICPNe despite conservative management, surgical intervention could clinically improve motor function and functional ability. Additionally, MRI examination of the affected muscle could help diagnose CPNe and assess the postoperative prognosis.

• Geomechanics and Engineering
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• v.32 no.3
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• pp.245-254
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• 2023

Through qualitative analysis and quantitative analysis, the contradictory conclusions about the stability of the settled goaf with two-layer coal seams subject to building load were obtained. Therefore, it is necessary to combine the additional stress method and numerical simulation to further analyze the foundation stability. Through borehole analysis and empirical formula analogy, the height of water-conducting fracture zone in No.4 coal and No.9 coal were obtained, providing the calculation range of water-conducting fracture zone for numerical simulation. To ensure the accuracy of the elastic modulus of broken gangue, the stress-strain curve were obtained by broken gangue compression test in dried state of No.4 coal seam and in soaking state of No.9 coal seam. To ensure the rationality of the numerical simulation results, the actual measured subsidence data were retrieved by numerical simulation. FISH language was used to analyze the maximum building load on the surface and determine the influence depth of building load on the foundation. The critical building load was 0.16 MPa of No.4 settled goaf and was 1.6 MPa of No.9 settled goaf. The additional stress affected the water-conducting fracture zone obviously, resulted in the subsidence of water-conducting fracture zone was greater than that of bending subsidence zone. In this paper, the additional stress method was analyzed by numerical simulation method, which can provide a new analysis method for the treatment and utilization of the settled goaf.