• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.1
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• pp.31-45
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• 2015

Existing link-based Frank-Wolfe algorithm has been widely used, thanks to its ease of simulation and stable results; however, it comes with low convergence issue towards near the optimum value. Such issue was not considered as a major drawback in the past. However, in the present, some arguments have occurred over the method's stability, analysis time, and other limits as the size and details of the fundamental data for traffic analysis have vastly improved. Therefore, this paper compared the theoretical attributes and the pros and cons between the Frank-Wolfe algorithm and the Origin-based algorithm and Path-based algorithm newly being developed. As a result of this paper, there is possibility that a problem of stability may arise depending on the convergence and exit criteria. Thus, In practice, this effort to derive the appropriate level of convergence is required to secure and stable results.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.6
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• pp.1155-1160
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• 2018

Presently in 2018, the security market is requiring progressive development and innovation in the area of security on account of new changes and technologies. This means the rapid and prompt development of the service platforms and service-based information systems. Here, this study is going to examine the process of operating a number of services and obtaining security, not the criteria for selecting particular service in online environment where the various services exist. Within a series of flows to protect the manager's authority about the platforms operated by information systems, and to provide and destroy services, this author limits the entire service platforms of the optimized balance module into four categories maximum for the security of the area apt for illegal invasion and access, and the proper area. Also, about the area with limited security, this researcher again applies subordinate security policy and technology respectively. This author here will suggest a method to provide and to extend safety and security for the information system and also propose the process of applying it as well.

• Physical Therapy Korea
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• v.26 no.1
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• pp.51-59
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• 2019

Background: Chronic low back pain (CLBP) causes morphological changes in muscles, reduces muscle strength, endurance and flexibility, negatively affects lumbar stability, and limits functional activity. Plank exercise strengthens core muscles, activates abdominal muscles, and improves intra-abdominal pressure to stabilize the trunk in patients with CLBP. Objects: We investigated the effect of plank exercise on abdominal muscle thickness and disability in patients with CLBP. Methods: We classified 33 subjects into 2 groups: An experimental (n1=17) and a control group (n2=16). Patients in the experimental group participated in plank exercise and those in the control group participated in stretching exercise. Patients in both groups attended 20-minute exercise sessions thrice a week for 4 weeks. Abdominal muscle thickness in each subject was evaluated ultrasonographically, and disabilities were assessed using the Oswestry disability index (ODI). Results: Four weeks later, abdominal muscle thickness showed a significant increase over baseline values in both groups (p<.05). Patients in the experimental group reported a more significant increase in the thickness of the external oblique muscle than that in the control group (p<.05). ODI scores in the experimental group were significantly lower after intervention than before intervention (p<.05). Conclusion: Plank exercise increases the thickness of the external oblique muscle and reduces disability secondary to mild CLBP. Therefore, plank exercise is needed to improve lumbar stability and functional activity in patients with mild CLBP.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.27 no.2
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• pp.69-76
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• 2021

Background: Degenerative arthritis accounts for a large portion of the elderly, causing a lot of inconvenience in daily life. Total knee replacement (TKR) are performed to relieve pain in the knee joint. The purpose of this study was to determine whether knee joint stabilization exercises are effective in improving balance and walking ability in degenerative arthritis patients who have undergone TKR. Methods: A total of 30 TKR patients participated in this study. They were assigned to two groups. The experimental group, the group that underwent knee stabilization exercises, joint mobilization and general physical therapy. On the other hand, and the controlled group, the group that underwent joint mobilization and general physical therapy. All exercises were conducted thrice a week, for four weeks. The main balance outcomes were evaluated using the posture balance training system, while walking ability was assessed using a wireless 3-axis accelerometer. Results: The experimental group had significantly higher scores in postural stability testing (PST), limits stability testing, and waling ability. The post-intervention evaluation, there were significant differences in all variables between the two groups. However, no significant difference was noted in the foam eyes closed test in PST. Conclusion: This study suggests that knee joint stabilization exercises effectively improve the balance and walking ability of TKR patients. Thus, it could be presented as useful in clinical practice.

• Tribology and Lubricants
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• v.38 no.5
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• pp.185-190
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• 2022

Among the operating limits of a heat pipe, the capillary limit is significantly affected by the characteristics of the wick, which is determined by the capillary performance. The major parameters for determining capillary performance are the maximum capillary pressure and the spreading characteristics that can be expected through the wick. A well-designed wick structure improves capillary performance and helps improve the stability of the heat pipe by enhancing the capillary limit. The capillary performance can be improved by forming a porous microstructure on the surface of the wick structure through surface modification techniques. In this study, a microstructure is formed on the surface of the wick by using a surface modification method (i.e., an electrochemical etching process). In the experiment, specimens are prepared using stainless-steel screen mesh wicks with various fabrication conditions. In addition, the spreading and capillary rise performances are observed with low-surface-tension fluid to quantify the capillary performance. In the experiments, the capillary performance, such as spreading characteristics, maximum capillary pressure, and capillary rise rate, improves in the specimens with microstructures formed through surface modification compared with the specimens without microstructures on the surface. The improved capillary performance can have a positive effect on the capillary limit of the heat pipe. It is believed that the surface microstructures can enhance the operational stability of heat pipes.

• International Journal of Highway Engineering
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• v.8 no.1 s.27
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• pp.15-23
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• 2006

Criteria of the current asphalt mix design, Marshall method, includes the stability and flow which are not related with field performance of HMA mixture, together with the air void, Void filled with asphalt (VFA) and/or Void of mineral Aggregate(VMA). In addition, the limits of stability and flow are satisfied in most cases, the Optimum asphalt content (OAC) is determined based on volumetric properties, such as the air void and/or VFA and/of VMA. Therefore, many researchers have sought mechanistic properties which can replace the stability and flow, making the designed mixture having potential for better field performance. This study initiated to develope a mix design by introducing two performance-related mechanistic properties, the deformation strengh and fracture energy, in place of the stability and flow of the Marshall method. The deformation strength $(S_D)$ from the Kim Test has a high correlation with rutting property and the fracture energy(FE) from the indirect tensile test represents the fatigue cracking property of asphalt mixture. Four types of asphalt mixture were prepared for examining possibility of using the suggested mix design method in comparison with current methods. The results showed that mechanical properties were reflected in determination of OAC with this suggested mix design, unlike the existing Marshall method.

• 한국연소학회:학술대회논문집
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• 2006.10a
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• pp.60-64
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• 2006

Propagation rates ($U_{edge}$) of various premixed, twin edge-flames were measured as a function of global strain rate ($\sigma$), mixture strength, and Lewis number (Le). Using a counterflow slot-jet burner with electrical heaters at each end, both advancing (positive $U_{edge}$) and retreating (negative $U_{edge}$) edge-flames can be studied as they propagate along the long dimension of the burner. Experimental results are presented for premixed methane/air twin flames in terms of the effects of $\sigma$ on $U_{edge}$. Both low-$\sigma$ and high-$\sigma$ extinction limits were discovered for all mixtures tested. As a result, the domain of edge-flame stability was obtained in terms of heat loss factor and normalized flame thickness, and comparison with the numerical result of other researchers was also made. For low ($CH_4/O_2/CO_2$) and high ($C_3H_8$/air) Lewis number cases, propagation rates clearly show a strong dependence on Le.

• The Journal of the Korean dental association
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• v.51 no.12
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• pp.650-657
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• 2013

The aim of this study was to achieve healing of Peri-implantitis defects and hard tissue augmentation using a bovine-derived bone mineral on the defect site. Two patients were treated with the surgical approach. With a full muco-periosteal flap elevation, the implant surfaces were exposed and granulation tissue removed around the implant and between the threads. Each surface of the contaminated implant was prepared with the air-abrasive device(PerioFlow$^{(R)}$) for decontamination. Bovine-derived bone mineral(Bio-Oss collagen$^{(R)}$) was then used to fill the defects and muco-periosteal flaps sutured to achieve transmucosal healing. Radiographs and clinical photographs were taken before and after 6 months of healing and an estimate of bone fill was assessed. Within the limits of the present case report, a surgical approach in treatment of peri-implantitis defects using a collagen form of bovine bone mineral was visited. Although limited, the two cases showed the stability and biocompatibility of a bovine-derived bone mineral and effectiveness of air-abrasive device(PerioFlow$^{(R)}$) as a decontamination method.

• The Journal of Korean Physical Therapy
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• v.29 no.4
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• pp.201-206
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• 2017

Purpose: The aim of this study was to identify the effects of Pilates mat exercise may improve trunk muscle thickness and balance in healthy adults. Methods: Eighteen healthy adults participated in this study. They were randomly assigned to one of two groups: Pilates mat exercise group (n=9) and the control group (n=9). Subjects in Pilates mat exercise group performed the exercises three days per week for 6 weeks, which consisted of warm up, main workout, and cool down. Trunk muscle thickness of the rectus abdominis (RA), internal oblique (IO), external oblique (EO), transverse abdominis (TrA), multifidus (MF), and erector spine (ES) were measured using an ultrasonography. Balance ability was evaluated using Romberg test and limits of stability (LOS). Measurements were performed before training, 3 weeks after training, and 6 weeks after training. Results: There was a significant difference of RA, EO, IO, MF, and ES according to the main effect of time (p<0.05). There was a significant difference of EO, MF, ES, Romberg, and LOS according to interaction effect between the time and group (p<0.05). There was a significant difference only for LOS according to the main effect of the group (p<0.05). Conclusion: Pilates mat exercise did increase trunk muscle thickness and balance. However, the effect with respect to trunk thickness was limited. Pilates mat exercise appears to be more effective in improving muscles related to trunk extension and balance.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.4
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• pp.595-599
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• 2018

Interruption system with the transformer type superconducting fault current limiter(TSFCL) is proposed in this paper. The interruption system with a TSFCL is a technology that it maximizes the interruption function of a mechanical DC circuit breaker using a transformer and a superconducting fault current limiter. By a TSFCL, the system limits the fault current till the breakable current range in the fault state. Therefore, the fault current could be cut off by a mechanical DC circuit breaker. The Interruption system with a TSFCL were designed using PSCAD/EMTDC. In addition, the Interruption system with a TSFCL was applied to the DC test circuit to analyze characteristics of a current-limiting and a interruption operation. The simulation results showed that the Interruption system with a TSFCL interrupted the fault current in a stable when a fault occurred. Also, The current-limiting rate of the Interruption system with a TSFCL was approximately 69.55%, and the interruption time was less than 8 ms.