• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.4
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• pp.610-619
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• 2022

Hydrogen is emerging as an alternative fuel for eco-friendly ships because it reacts with oxygen to produce electrical energy and only water as a by-product. However, unlike regular fossil fuels, hydrogen has a material with a high risk of explosion due to its low ignition point and high flammability range. In order to safely use hydrogen in ships, it is an essential task to study the flow characteristics of hydrogen leakage and diffusion need to be studied. In this study, a numerical analysis was performed on the effect of leakage, ventilation, etc. on ventilation performance when hydrogen leaks in an enclosed space such as inside a ship. ANSYS CFX ver 18.1, a commercial CFD software, was used for numerical analysis. The leakage rate was changed to 1 q, 2 q, and 3 q at 1 q = 1 g/s, the ventilation rate was changed to 1 Q, 2 Q and 3 Q at 1 Q = 0.91 m/s, and the ventilation method was changed to type I, type II, type III to analyze the ventilation performance was analyzed. As the amount of leakage increased from 1 q to 3 q, the HMF in the storage room was about 2.4 to 3.0 times higher. Furthermore, the amount of ventilation to reduce the risk of explosion should be at least 2 Q, and it was established that type III was the most suitable method for the formation of negative pressure inside the hydrogen tank storage room.

• Journal of Korea Entertainment Industry Association
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• v.14 no.3
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• pp.403-410
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• 2020

The purpose of this study was to determine whether olfactory stimulation would improve spasticity, balance ability and quality of life in stroke patients. Twenty-one stroke patients were recruited and were randomly divided into two groups: olfactory stimulation group (n=10) and sham stimulation group (n=11). Participants in both groups received conventional physical therapy for 30 minutes before the intervention. Additionally, subject in the olfactory stimulation group performed olfactory stimulation using lavender oil for 6 minutes (2 minx3 set), five times a week for two weeks, while the sham stimulation group conducted olfactory stimulation using water for the same amount of time. Composite-Spasticity-Score was used to assess spasticity level of ankle plantar-flexors. Dynamic balance was measured using a TUG. Postural-sway distance was measured using a force platform. Quality of life were measured by SF-36. There was no significant difference within group and between the groups in the spasticity. Significant improvement in postural-sway and TUG were observed in the olfactory stimulation group compared to the sham stimulation group (p<0.05). The Mental Componnt Summary of the SF 36 in the olfactory stimulation group improved significantly greater than the sham stimulation group (p<0.05). Our findings indicate that olfactory stimulation is beneficial and effective to improve balance ability and quality of life in stroke patients.

• Journal of Industrial Convergence
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• v.20 no.1
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• pp.23-33
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• 2022

The study was conducted to develop an implementation model for digital transformation (DX) of manufacturing companies. To this end, previous studies on the process of management innovation and digital transformation were reviewed. The DX process model was derived based on the NEBIC theory and innovation theory applied in the innovation process of the Internet business. In addition, a research model including the factors of the will of the top management class (TMT) was constructed and confirmed through empirical data. The research hypothesis were verified based on data collected from members of mid-sized manufacturing companies promoting digital transformation. Through regression analysis, the influence relationship of each stage of the research model (technical knowledge, TK → opportunity perception, OR → performace expectation, PE and → Intention to execute, IE) was confirmed. Hierarchical regression analysis was conducted to understand the mediating effect of the members' perception of the top management's willingness to promote DX in the process. As a result of checking the Sobel test, it was confirmed that the management's perception of DX promotion partially mediated the relationship at each stage. This study is meaningful in that it presented a model applicable to the digital transformation of the mid-sized manufacturing industry. It is also valuable in providing an empirical basis for innovative research and NEBIC expansion. Longitudinal studies are required to overcome the limitations of empirical data for process models with dynamic characteristics whereas extended empirical studies are required in various fields other than manufacturing to generalize research results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.40-47
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• 2021

In this study, the structural behavior by the details of the lap region with the headed bar was estimated through finite element analysis. To solve the finite element analysis of the anchorage region with complex contact conditions and nonlinear behavior, a quasi-static analysis technique by explicit dynamic analysis was performed. The accuracy of the finite element model was verified by comparing the experimental results with the finite element analysis results. It was confirmed that the quasi-static analysis technique well reflected the behavior of enlarged headed bar connection. As a result of performing numerical analysis using 21 finite element models with various development lengths and transverse reinforcement indexes, it was confirmed that the increase of development length and transverse reinforcement index improved the maximum strength and ductility. However, to satisfy the structural performance, it should be confirmed that both design variables(development length and transverse reinforcement index) must be enough at the design criteria. In the recently revised design standard(KDS 14 20 52 :2021), a design formula of headed bar that considers both the development length and the transverse reinforcing bar index is presented. Also the results of this study confirmed that not only the development length but also transverse reinforcing bars have a very important effect.

• Journal of Korea Entertainment Industry Association
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• v.14 no.2
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• pp.141-153
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• 2020

The purpose of study is to examine the role of the Professor's friendly behavior as a parameters in the course of Paralanguage Utilization Training using pronunciation, stress, voice tone, speed, pause and expression of feelings affecting of Audiobook text shaping. the results of this study will be a reference to training on the use of Paralanguage for dynamic shaping of Audiobook text and recognizing the need and influence of professors' friendly behavior as a parameters. The results of the study are as follows. First, training in the use of Paralanguage was shown to have a positive effect on the Shaping of Audiobook text and served as a key factor in conveying the original meaning of text. Therefore, if we look at the significance and content of training using Paralanguage and continue training using Paralanguage, it will actually help to shape Audiobook text. Second, the professor's friendly behavior partially acted as a parameters role between training in the use of Paralanguage and shaping Audiobook text. The professor's friendly behavior has helped form Audiobook text by providing a sense of trust and will increase the level of completion for training in the use of Paralanguage. Thus, training in the use of Paralanguage Utilization Training could result in more effective Audiobook text shaping when conducted in conjunction with the professors' friendly actions. Therefore, it was shown that the ability to use Paralanguage and the professor's caring and friendly behavior to help them perform better were more effective when they simultaneously affected Audiobook text shaping.

• Journal of the Korea Institute of Building Construction
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• v.22 no.6
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• pp.553-564
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• 2022

Concrete is a representative composite material that shows excellent performance in the construction field. However, it is a brittle and nonhomogeneous material and exhibits weak behavior against bending and tensile forces. To compensate for such weakens, fiber reinforcement has been utilized, and steel fiber has been recognized as one of the best material for such purpose. However, steel fiber can seriously affect the durability of concrete exposed to the marine environment due to the corrosion caused by chlorine ions. This study intended to evaluate the mechanical performance of steel fiber reinforce concrete during and after repeated wet/dry cycles in salt solution. According to the experimental results, there was no reduction in the relative dynamic modulus of concrete during the repeated wet/dry cycles in salt solution for 37 weeks. Flexural strength was not decreased after completion of repeated wet/dry cycles in salt solution. There was no sign of corrosion in steel fibers after visual observation of fractured surface. However, the flexural toughness was decreased, and this is because about half of the concrete specimen showed failure before reaching the maximum displacement of 3 mm. Although repeated wet/dry cycles in salt solution did not cause cracks in concrete through corrosion of steel fibers, specific attention is required because it can reduce flexural toughness of steel fiber reinforced concrete.

• Journal of the Korean Society of Radiology
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• v.16 no.7
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• pp.975-984
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• 2022

Since a linear transducer has an area of interest equal to the length of the transducer, the area of interest can be expanded using the virtual convex function installed in the device.However, it was thought that the change in the direction of the ultrasonic sound velocity according to the change in the visual area of interest would affect the image quality, so this was objectively confirmed. For this study, image evaluation and SNR·CNR of the phantom for ultrasound quality control were measured. As a result, in the phantom image evaluation, both images were able to identify structures in functional resolution, grayscale, and dynamic range. However, it was confirmed that the standard image was excellent in the reproducibility of the size and shape of the structure. As a result of SNR·CNR evaluation, SNR·CNR of most trapezoidal images was low, except for structures at specific locations. In addition, through the statistical analysis graph, it was further confirmed that the SNR and CNR for each depth decreased as the size of the cystic structure decreased. Through this study, it was confirmed that the use of the function has the advantage of providing a wide visual area of interest, but it has an effect on the image quality. Therefore, when using the virtual convex function, it is judged that the examiner should use it in an appropriate situation and conduct various studies to acquire high-quality images and to improve the understanding and proficiency of the equipment.

• Journal of the Korean Institute of Gas
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• v.26 no.2
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• pp.49-55
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• 2022

According to reinforce environmental regulations, coal power plants have used selective catalytic reduction using ammonia as a reducing agent to reduce the amount of nitrogen oxide generation. The purpose of the present study was to derive a mixing device for effectively mixing dilute air and ammonia in the ammonia mixing pipe by performing computational fluid dynamic analysis. The mixing effect was compared by analysing the %RMS of ammonia concentration at the down stream cross section in the mixing pipe and the 16 outlets based on the case 1-1 shape, which is an existing mixing pipe without a mixing device. The mixing device was performed by changing the positions of a square plate on the downstream side of the ammonia supply pipe and an arc-shaped plate on the wall of the mixing pipe. In the case of the existing geometry(Case 1-1), the %RMS of ammonia concentration at the 16 outlets was 29.50%. The shape of the mixing device for Case 3-2 had a square plate on the downstream side of the ammonia supply pipe and an arc plate was installed adjacent to it. The %RMS of ammonia concentration for Case 3-2 was 2.08% at 16 outlets and it could be seen that the shape of Case 3-2 was the most effective mixing shape for ammonia mixing.

• PNF and Movement
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• v.20 no.2
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• pp.157-166
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• 2022

Purpose: The aim of this research was to investigate the effects of self-sit-to-stand training on balance ability and sit-to-stand ability in hemiplegic stroke patients using a multisensory feedback device. Methods: A total of 19 stroke patients participated in this study, and they were divided into two groups: 10 underwent self-sit-to-stand training using a multisensory feedback device, and 9 underwent sit-to-stand training with a physical therapist. In both groups, sit-to-stand training was performed for 30 min, 3 times a week, for 6 weeks. The subjects also underwent physical therapy twice a day for 30 min, 10 times a week, for a total of 60 sessions. Balance ability was evaluated using the AFA-50 and Berg Balance Scale. Sit-to-stand ability was evaluated using the five times sit-to-stand test. Results: Sway length, pressure, and total pressure all significantly increased in both groups, and there was no difference between the two groups. The Berg Balance Scale results showed that balance ability significantly increased in both groups, and there was no difference between the two groups. The five times sit-to-stand test results showed that sit-to-stand ability significantly increased in both groups, and there was no difference between the two groups. It was found that the self-sit-to-stand training using a multisensory feedback device had a positive effect on balance control and sit-to-stand ability. When the two groups were compared, no difference in balance ability or sit-to-stand ability was observed. Conclusion: The findings of this study indicate that self-sit-to-stand training using a multisensory feedback device is as effective as sit-to-stand training with a physical therapist. Hence, self-sit-to-stand training using a multisensory feedback device could be an effective home-based exercise protocol for hemiplegic stroke patients to improve their balance and sit-to-stand abilities.

• Bulletin of the Society of Naval Architects of Korea
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• v.26 no.4
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• pp.81-93
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• 1989

The present study attempts to develop the theoretical model for the damage estimation of offshore tubular members which are subjected to the accidental impact loads due to collision, falling objects and so on. For the reasons of the simplicity of the problem being considered, however, this paper postulates that the accidental load can be approximated to be the quasi-static one, in which dynamic effects are negelcted. Based upon the theoretical and experimental results which are obtained from the present study as well as the existing literature, the load-displacement relations taking the interaction effect between the local denting and the global bending deformation into account are presented in the explicit form when the concentrated lateral load acts on the tubular member whose end condition is supposed to be rotation ally free and axially restrained, in which membrane forces develop. Thus, the practical estimation of damage deformation for the local denting and the global bending damage of tubular members against the accidental loads is possible and also the collision absorption capability of the member can be calculated by performing the integration of the area below the given load-displacement curves, provided that all the energy is dissipated to the deforming the member itself.