• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.3
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• pp.193-201
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• 2023

In this study, a nonlinear truss finite element is developed to analyze structures with negative Poisson effect-induced tensile buckling. In general, the well-known buckling phenomenon is a stability problem under a compressive load, whereas tensile buckling occurs because of local compression caused by tension. It is not as well-known as classical buckling because it is a recent study. The mechanism of tensile buckling can be briefly explained from an energy standpoint. The nonlinear truss finite element with a torsional spring is formulated because the finite element has not been reported in the literature yet. The post-buckling analysis is then performed using the generalized displacement control method, which reveals that the torsional spring plays an important role in tensile buckling. Structures that mimic a negative Poisson effect can be constructed using such post-buckling behaviors, and one of the possible applications is a mechanical switch. The results obtained are compared to those of analytical solutions and commercial finite element analysis to assess the validity of the proposed finite element model. The numerical results show that the developed finite element model could be a viable option for the basic design of nonlinear structures with a negative Poisson effect.

• Journal of Korea Entertainment Industry Association
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• v.14 no.7
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• pp.539-548
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• 2020

TTH(tension-type headache) is the most common primary headache among adults. Long-term headaches cause chronic headaches and have a better impact on daily life. The purpose of this study is to compare the contributions to TTH through AVE(audio-visual entertainment) and STM(soft tissue mobilization) suitable for management of pathogenic and psychogenic factors of TTH. The participants of this study were from 30 people who complained of intermittent or persistent headaches for more than 6 months, and 10 participants each in the AVE group, STM group, and AVE plus STM group. In the assigned group, a total of 12 sessions were performed three times a week for 4 weeks after the baseline, followed by post-test. Outcome measures measured PPTs(pressure pain thresholds), psychophysiological parameters, and EEG(electroencephalogram). The measured results were analyzed for interaction between time and group through a two way rmANOVA(repeated measurement variance analysis). As a result of the PPTs, interaction was found in the results of the right trapezius (p<.05), and the more improvement was observed in the AVE group. Therefore, through AVE based on psychological factors rather than direct access to the muscles of pathogenic factors, a positive impact on the PPTs was shown, but the average value of the psychophysiological parameters and brain waves that were not statistically significant. The amount of change was observed. Through this, it is suggested that audio-visual stimulation could be considered in the management of TTH.

• Journal of the Korean Society of Physical Medicine
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• v.19 no.1
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• pp.53-60
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• 2024

PURPOSE: The study aimed to analyze the effect of pillow height on upper trapezius and sternocleidomastoid (SCM) muscle activity and overall human body comfort to determine the optimal pillow height. METHODS: The study included 32 healthy college students, of both genders, who provided prior consent. It examined three pillow heights (flat, 6cm, 12cm) and measured the upper trapezius and SCM muscles using ultrasonography, myotone, and electromyography(EMG). Muscle activation, thickness, and fatigue were assessed. RESULTS: The study found significant differences in muscle thickness and muscle tone based on the pillow heights (flat, 6cm, and 12cm) with a p < .05. The SCM and upper trapezius muscles were thinnest at a pillow height of 6cm. Muscle tone in the SCM was lower at both 6cm and 12cm pillow heights. Post-hoc measurements showed significant differences in both the SCM and upper trapezius muscles thickness at the 6cm pillow height (p < .05). Also, significant differences in muscle tone were observed only in the SCM, particularly between the 6cm and 12cm pillow heights. CONCLUSION: The ultrasonography and myotone measurements showed a significant difference in muscle thickness and muscle tension, both of which were above 6cm, while there was no difference in muscle activation. Based on the strong correlation between muscle tension and muscle thickness with pillow height, this study concluded that the human body feels comfortable with a 6cm pillow height. Therefore, it is recommended to use a pillow height of 6cm when lying in a supine position.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.4
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• pp.130-137
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• 1997

The demand for wire-cut EDM is increasing rapidly in the die and tool making industry. In this study machining characteristics such as machining rate, surface roughness, hand drum form and hardness of machined material are investigated experimentally under the conditions varing pulse on time, pulse off time, peak voltage, wire tension after fixing other conditions in SKD 11 and brass and brass workpiece. It was found that various operating conditions had significant influences on machining characteristics. But the hardness of workpiece was uneffected by operating conditions. Also it was obtained experimentally that brass workpeice had better machinability than SKD 11 one.dition according to the current(Ip) in an electric spark machine : 1) Electrode is utilized Cu and Graphite. 2) Work piece is used the material of carbon steel. The condition of experiment is : 1) Current is varied 0.7(A) to 50(A) and the time of electric discharging to work piece in each time is 30(min) to 60(min). 2) After the upper side of work piece was measured in radius(5$\mu$m) of stylus analyzed the surface roughness to ade the table and graph of Rmax by yielding data. 3) Electro wear ratio is : \circled1Cooper was measured ex-machining and post-machining by the electronic balance. \circled2The ex-machining of graphite measured by it, the post-machining was found the data from volume $\times$specific gravity and analyzed to made its table and graph on ground the data. 4) In order to keep the accuracy of voltage affected to the work piece was equipped with the A.V. R and the memory scope was sticked to the electric spark machine. 5) In order to preserve the precision of current, to get rid of the noise occured by internal resistance of electric spark machine and to force injecting for the discharge fluid , it made the fixed table for a work piece to minimize the work error by means of one's failure during the electric discharging.

• The Journal of Korean Medical History
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• v.23 no.1
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• pp.23-41
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• 2010

Greater yang disease(太陽病) is a syndrome induced by peripheral obstruction. One of them is "wind stroke(中風)" with the obstruction in lymphatic system. The other obstruction appearing on circulatory system is called "cold damage(傷寒)." Kyejitang(桂枝湯) is the formula prescribed for greater yang wind stroke pattern(太陽中風證) which is caused by peripheral lymphatic duct obstruction. Ramulus Cinamoni acts as a vasodilator and Radix Paeoniae relieves the abdominal tension. They make blood move to the internal organ and this can remove the retention of peripheral lymphatic system. Covering the patient with a blanket and getting him/her to have hot and thin rice gruel causes slight Diaphoresis, contributing to relieving the retention of lymphatic system. Disharmony between nutrient and defense(營衛不和) means that pressure becomes different between lymphatic system and vascular system. Kyejitang(桂枝湯) is called releasing muscles formula(解肌劑) because it can resolve such pressure difference. Diaphoresis is not a means to eliminate pathogenic qi(邪氣) from the body. That is the syndrome proving that the body fluid has moved around when disordered fluid distribution is corrected. Therefore, diaphoresis should be induced weakly all the time. If diaphoresis is induced excessively, body fluid will move more than desired and then illness cannot be cured. In Sanghanlun(傷寒論), dispersing drugs aim at addressing the retention in the exterior field, but it actually applies to the entire exterior and interior to make body fluid move. Therefore, diaphoresis does not just act on exterior field, and freeing the stool does not only apply to interior field. Distribution of body fluid changed by pathogenic qi(邪氣) influences the whole body because the human body has a closed circulatory system. Sanghanlun(傷寒論) has included treatments for pathogenic disease. However, its value should not be limited to pathogenic disease. It is because controlling blood flow by sending body fluid to the place a doctor wants is certainly worth using for treatment of non-exogenous disease or chronic illnesses.

• Proceedings of the Korea Information Assurance Society Conference
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• 2004.05a
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• pp.219-225
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• 2004

There is increasing tension in the Korean Peninsula from the US' putting the NK's nuclear issue along the line of war in Iraq. However, there is worsening in ROK's field exercise condition from decresing defense financial supports, being difficlut to obtain enough space for volumable exercises, and securities and circumstances issues. With acknowleging those problems, CPX(Command Post Exercise), namely war game exercise which is more economical and scientific exercise has earned its attention as the best alternative measure of field exercise war game exercise has already been applyied to independent, joint, and combined exercises. However, the current war game system contains lots of problems in terms of security. Defense network uses dedicated line isolated with internet and secure data through network level encoding. It is vulerable to get attack during war game exercise or from credited network. System security is also subject to reinforced. This research is performed focusing on network and system level securities, and through it, the author will show the effective and optimized security solution for war game system.

• Journal of The Korean Association For Science Education
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• v.25 no.5
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• pp.583-594
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• 2005

This study examined 8th-graders' conceptions of force on a simple pendulum and investigated cognitive conflict and conceptual change through kinesthetic experience in swing. Participants of this study were guided to anticipate the direction of total force acting on a pendulum at three critical positions and observed it through swing experience. Having completed this, students read an article explaining the results they observed. Most of them considered gravity, tension, and motion-force to be the real forces acting on a pendulum in pre-test. Though they were interested in the activity and conceded their expectations to be different from observed results, the degrees of their cognitive conflict were not significantly high. In summation, 'interest' was the highest and 'anxiety' was the lowest. Most of the students memorized the direction of forces on a swing, but few could explain the reason behind the occurrence in an immediate post-test and delayed post-test.

• Earthquakes and Structures
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• v.3 no.6
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• pp.821-838
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• 2012

This paper proposes a new three-layer pillar-type hysteretic damper system for residential houses. The proposed vibration control system has braces, upper and lower frames and a damper unit including hysteretic dampers. The proposed vibration control system supplements the weaknesses of the previously proposed post-tensioning vibration control system in the damping efficiency and cumbersomeness of introducing a post-tension. The structural variables employed in the damper design are the stiffness ratio ${\kappa}$, the ductility ratio ${\mu}_a$, and the ratio ${\beta}$ of the damper's shear force to the maximum resistance. The hysteretic dampers are designed so that they exhibit the targeted damping capacity at a specified response amplitude. Element tests of hysteretic dampers are carried out to examine the mechanical property and to compare its restoring-force characteristic with that of the analytical model. Analytical studies using an equivalent linearization method and time-history response analysis are performed to investigate the damping performance of the proposed vibration control system. Free vibration tests using a full-scale model are conducted in order to verify the damping capacity and reliability of the proposed vibration control system. In this paper, the damping capacity of the proposed system is estimated by the logarithmic decrement method for the response amplitudes. The accuracy of the analytical models is evaluated through the comparison of the test results with those of analytical studies.

• Journal of the Korean Wood Science and Technology
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• v.42 no.1
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• pp.20-26
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• 2014

This paper represented the finite element analysis to estimate structural performance of stress-laminated deck, which is determined by deflection, stress, and aging characteristics of tensioning. After loading, the deflected shape showed plate behavior because pre-stressing make frictional force between each member. Compared between initial post-tension and the results, pre-stressing forces were decreased with deck deflection. This is because deflection occurred in the deck so that pre-stressing decreased due to load reduction. However, material plasticity was not considered so that advanced researches should be performed.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.4 no.1
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• pp.61-67
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• 2011

Influence of hexamethyldisilazane(HMDS) in post processing technique by using n-butanol azeotropic distillation on the luminescence properties of YAG:Ce nanophosphor were studied. The organic solvent(n-butanol) azeotropic distillation which prevent powders from conglobation since lager molecules decrease the surface tension and more complete replace the residual water in the precipitate. HMDS that had larger molecules than that of n-butanol was added in azeotropic distillation. The phosphor synthesized from n-butanol azeotropic distillation exhibited lower agglomerate and better photoluminescence properties than that from HMDS added heterogeneous azeotropic distillation.