• Advanced Industrial SCIence
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• v.1 no.2
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• pp.9-16
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• 2022

This study was a randomized before-and-after design of 17 subjects in the experimental group and 17 subjects in the control group to investigate the effects of listening to relaxing music on the mood state and autonomic nervous system, that is, heart rate of hospitalized patients with mental illness. The collected data were analyzed with SPSS V15.0. There was a statistically significant difference between the two groups in mood state and autonomic nervous system, that is heart rate and the effect of listening to relaxation music was objectively verified(<.05). among the subdomains of mood states, tension(<.00), depression (<.00), vitality (<.03), fatigue () <.01), excluding anger (>.39) and confusion (>.33) showed a significant difference, proving that it is an effective intervention method applied to hospitalized mentally ill patients. In the future, we would like to suggest long-term intervention research and development and application, and research on the effect of mood change and heart rate using individual preferred music.

• Investigative Magnetic Resonance Imaging
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• v.26 no.2
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• pp.117-124
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• 2022

Purpose: In this study, we provide a way to assess even a slight effect of exercise on trunk-muscle activity. Materials and Methods: Seven healthy male participants (mean age, 24.7 ± 3.2 years; height, 171.2 ± 9.8 cm; and weight, 63.8 ± 11.9 kg) performed 15 sets of an exercise with 20 repetitions of 90° hip and right-knee flexion while lying supine. The exercise intensity was measured using the 10-point Rating of Perceived Exertion Scale after the first and 15th sets of exercises. Although cross-sectional areas and functional T2 mapping using ultrafast imaging (fast-acquired muscle functional magnetic resonance imaging, fast-mfMRI) have been proposed for imaging to evaluate exercise-induced muscle activity in real time, no previous studies have reported on the evaluation of trunk-muscle activity using functional T2 mapping. As a method for assessing trunk-muscle activity, we compared functional T2 mapping using ultrafast imaging (fast-mfMRI) with cross-sectional areas. Results: Although the muscle cross-sectional areas were increased by the exercise, there was no significant difference at rest. On the other hand, for all sets, the changes in T2 were significant compared with those at rest (P < 0.01). These results demonstrate that T2, calculated from fast-mfMRI images can be used to detect even a small amount of muscle activity induced by acute exercise, which was impossible to do with cross-sectional areas. Conclusion: Fast-mfMRI, which can also display functional information with detailed forms, enabled non-invasive real-time imaging for identifying and evaluating the degree of deep trunk-muscle activity induced by exercise.

• Journal of People, Plants, and Environment
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• v.23 no.6
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• pp.667-681
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• 2020

Background and objective: Recently, there has been an increasing need for relaxation and familiarity with nature in residential and living spaces faced daily by urban residents, leading to a growing social interest in urban gardens. The aim of this study was to determine how gardens in a city provide physical and social benefits, comparing cases in Korea and overseas. Methods: We used the keywords "garden" and "city" for Korea, and "urban," "garden," and "green" for overseas. We then determined the Korean and overseas research trends in urban gardens by analyzing 63 Korean and 90 overseas articles deemed suitable for this study. Results: As to the types of urban gardens, the most significant type was community gardens, both in Korea and overseas (30.2% and 48.6%, respectively), followed by rooftop gardens in Korea (22.2%) and kitchen gardens overseas (22.2%). Due to the narrow and complex urban structure in Korea, people focus on using rooftop, wall, and alley spaces, and tend to arrange container-type flexible gardens. Overseas there has been a focus on promoting health and reducing food inequality through allotment and kitchen gardens, and a tendency to use a larger area as a fixed form than Korea. In addition, it was found that gardens in urban areas had a positive effect on urban biodiversity. Conclusion: To sum up, gardens in Korea are close to living spaces, and gardens overseas influence the ecosystem with an emphasis on food production. Therefore, creating urban gardens is a method of urban regeneration with a high utility that goes beyond mere food production, both in Korea and overseas, providing comprehensive benefits for the environment (37.73%) and society (62.27%). As such, continuous research on this area of study is needed to create policy guidelines for Korea.

• Tribology and Lubricants
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• v.37 no.6
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• pp.224-231
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• 2021

Recently, the waterproofing performance of high-voltage connectors in automotive vehicles has attracted increased interest. In this study, an optimal cross-sectional shape was derived to obtain uniform contact pressure and strain by considering stress relaxation problems caused by initial tension when mounting a seal. A high strain of 52.1 was distributed in the round region, owing to excessive initial tension. The finite element method (FEM) analysis indicated that the strain corresponding to the optimal initial tensile was 11. We adopted six design factors to optimize the seal cross-section and three factors as the main design factors. An orthogonal arrangement table was prepared using Minitab. FEM analyses of 16 study models were conducted to determine the optimized model. The contact pressure of the optimization model is the most evenly distributed while satisfying the waterproof performance of 0.47 MPa. Compared to the initial model, the difference in strain decreases from 35.5% to 19.6%. Finally, the derived cross-sectional shape can reduce the strain of the round region by 33.8% and the differences in the contact pressure at the upper and lower surfaces by 42% and 76%, respectively.

• Korean Journal of Applied Biomechanics
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• v.33 no.1
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• pp.1-9
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• 2023

Objective: This study identifies the difference among the heights of a chair's backrest (High, Mid, No), the biomechanical changes chair users undergo over time, and the variables that can measure musculoskeletal disorders, eventually providing information on the appropriate type of backrest. Method: Eleven healthy subjects in their 20s and 30s who had no experience with musculoskeletal disorders or surgical operations within the last 6 months participated in this study. Computer typing tasks were randomly designated and performed according to the type of chair backrest, and evaluation was performed for Flexion-Relaxation Ratio (FRR) analysis after the computer typing tasks. This study used eight infrared cameras (sampling rate: 100 Hz) and nine-channel electromyography (sampling rate: 1,000 Hz). ANOVA with repeated measures was conducted to verify the results, with the statistical significance level being α = .05. Results: Although there was no significant difference in craniovertebral angle (CVA), this study showed time and interaction effects depending on the height of the backrest (p<.05). When working without the backrest, the head-spine angle was lower compared to the chairs with backrest, based on the computer work. As for the head angle, the higher the back of the chair was, the less the head flexion and the body angle became, whereas the body flexion became less when there was a backrest. In addition, the body flexion increased over time in all types of backrests (p<.05). The muscle activity of the upper body tended to be high in the high backrest chair. On the other hand, a lower muscle activity was found with a low backrest. Conclusion: These results show that a chair is more ergonomic when the body angle is correctly set without bending and when it is supported by a low backrest. Accordingly, this study determines that the backrest affects shoulder and neck musculoskeletal disorders during typing and that medium-height backrest chairs can help prevent musculoskeletal disorders, contrary to the expectation that high-backrest chairs are preferable.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2A
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• pp.261-271
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• 2006

Many uncertainties affecting to the structural behavior of prestressed concrete (PSC) bridges reinforced with the un bonded external tendons are analyzed on the basis of the analytical method introduced in the companion paper. Many design parameters, which must be considered in design procedure, such as friction slip at the deviators, number of deviators, time-dependent deformations of concrete, relaxation of tendon and influence of loading history in PSC bridges are reviewed, and a lot of valuable results are obtained through this parametric study. In advance, the structural responses according to the external tendon profiles are analyzed to grasp if an optimum tendon profile depends on the applied loading type, and the obtained results show that the most stable structural response is revealed when the locations of deviators are coincident with the loading points.

• Journal of the Health Care and Life Science
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• v.10 no.2
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• pp.393-401
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• 2022

The purpose of this study was to investigate how the virtual reality stimulation of conscious movement affects stress after inducing stress with fear stimulation through virtual reality for university students. The control group (n=26) was to applied visual and auditory of virtual reality, and the experimental group (n=29) was to applied visual, auditory and conscious movement together. As a result, in brain waves, it was confirmed that the experimental group induced relaxation better than the control group, and the stress response was more reduced to be more effective in regressing to baseline value, in heart rate variation, it was confirmed that the experimental group was more concentrated and more flow in virtual reality. Therefore, virtual reality stimulation applying conscious movement is considered to be a comfortable intervention method that can be applied to various stresses.

• Applied Chemistry for Engineering
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• v.9 no.6
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• pp.822-828
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• 1998

Binary system of water and polyoxyethylene dodecyl ether, $C_{12}H_{25}(OCH_2CH_2)nOH$, have been studied by $^1H$ NMR techniques. For n=5($C_{12}EO_5$) and n=8($C_{12}EO_8$), the self-diffusion coefficients of nonionic surfactants in the isotropic phase($L_1$) have been measured by using pulsed field gradient technique for a range of temperature and concentrations. In addition the line widths of the different proton signals have been monitored, and samples of some liquid crystalline characteristic were also studied. Dramatic Broadening of the methylene signals of the alkyl($C_{12}H_{25}$) chain is observed as the hexagonal liquid crystalline phase is approached in the $C_{12}EO_5-$water system, while only small broadening is observed in the $C_{12}EO_8-$water system. It was shown that there was a growth of $C_{12}EO_5$ micelles to rods with increasing concentrations, while the $C_{12}EO_8-$ micelles at low temperature remain small in the concentration range. The self-diffusion coefficients of the surfactants decrease rapidly with increasing concentration until a minimum is reached after which there is slow increase. The location of the minimum point occurs at lower concentrations the temperature is close to the cloud point, where the system separate into two isotropic phase. In the line width studies, broadening is found at a certain temperature interval when the concentration is increased in the $C_{12}EO_5$ system. The results indicate that the surfactant aggregates grow in size at the cloud point is approached. The aggregates seem to be flexible and probably not to be of a definite shape close to the cloud point. In the $C_{12}EO_8$ system, the micelles are much less affected by an increase in temperature and micellar growth can't be unambiguously established. The methylene signals of the ethylene oxide moieties consistantly show narrower $^1H$ signals, showing that in the aggregates they are less ordered than the chain methylenes. The various changes in aggregate size and shape are correlated with the stability ranges of the isotropic and liquid crystalline phases according to phase diagrams from the literature. Both aggregate size and phase structure are in qualitative agreement with concentration based on the effective shape of the molecules at different temperature and concentration.

• Korean Journal of Heritage: History & Science
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• v.38
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• pp.329-358
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• 2005

The Three storied Stone pagoda in Gameunsa Temple site, one of the early staged stone pagodas, has been known as a standard for Silla stone pagodas. A stone pagoda is not only a stone art work and but also a stone structure. Most studies and investigation of the stone pagoda has done mainly based on style and chronological research according to an art historical view. However, there is not an attempt to research the stone pagoda as a stone architecture. Most Korean experts at the stone pagoda has art history in their background. Engineers who can understand the structure of the stone pagoda are very limited. More architectural and engineering approach is need to research not only art historial understanding but also safety as a structure. We can find many technical know-how from our ancestors who made stone pagodas. 1. To reduce any deformation such as relaxation and sinking of BuJae which is caused by a heavy load, the BuJae (consist of a foundation stone and lower stereobates) should be enlarged. 2. A special construction method for connection between Myonsuk and Tangjoo was invented. This unique method is not used any longer after the Three storied Stone pagoda in Gameunsa Temple site. 3. The upper BuJae and the lower BuJae are missed each other by making a difference of Okgaesuk and Okgaebatchim in size. It is done for a distribution of perpendicular load and a prevention for relaxation of BuJae. 4. The center of gravity in the BuJae is located to the center of the stone pagoda by trimming the upper surface of the Okgaebatchim into a convex shape. The man who made stone pagodas had excellent knowledge on the engineering and techniques to understand the structure of the stone pagodas. We can confirm it as follows: the enlarged BuJae, dislocated connection between upper Bujae and lower BuJae, and moving the center of gravity close to the center of the stone pagoda.

• Journal of Oral Medicine and Pain
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• v.18 no.2
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• pp.121-130
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• 1993

Mandibular rest position is very essential position because in that position, masticatory muscularture can be reciprocally coordinative and unstrained. So obtaining a good ability to establish and maintain rest position in non-functioning state is mandatory for treatment of patient with craniomandibular disorders. In general, many types of mandibulr movement exercise start from rest position and use the sense of muscle relearning, that is, muscle smoothness and relaxation, throughout the exercise period. In this study, 44 normal subjects for control group and 37 patients with craniomandibular disorders for experimental group participated and they were classified into 3 subgroups, respectively. One method to guide mandibular rest position was used for one subgroup, so theree methods were used for this study, 1)self-guided rest position without any education, 2) guided by Rocabado's tongue rest position, 3) guided through swallowing after Dawson's centric relation. To record electromyographic activity, Bioelectric processor EM2 (Myotronics, U.S.A.) was used. The numbers of sessions from start to stable resting electromyographic level and muscle activities in stable state were recorded and two recordings which were first and second, 3 days after first recording, were done, The data were processed with SPSS/PC+package. The obtained results were as follows : 1. Mean number of sessions in second recording were fewer than those in first recording in both groups. In comparison among 3 subgroups, mean number of sessions of subgroup guided through Dawson's method were fewer than those of other groups though it is not statistically significant. 2. There was a difference of mean number of sessions between control and experimental group in first recording, but in second recording there was no difference in any cases. 3. Mean value of muscle activity were generally not different without regard to group and method if once come to stable resting position level. Mean value of muscle activity of guided subgroups showed a tendency of decreasing in second recording than in first recording. However, in self-guided subgroup there was a inconsistent pattern. 4. The amounts of change in session number from first to second recording in control group were fewer than those in experimental group.