• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1992.04a
• /
• pp.268-273
• /
• 1992

Thin walled tubular specimens of 0.45% structural carbon steel were used in the bizxial tests. Biaxial fatigue tosts were conducted on strain control including fully reversed tension-compression and in phase tension torsion loadings. The predictions of the biaxial fatigue life were based upon the uniaxial low cycle fatigue test results. Fatigue lives were ranged from 10$\^$2/to 10$\^$5/cycles. Four multiaxial strain based theories have been developed to correlate biaxial fatigue experimdntal results. These theories showed good correlatins except for maximum shear strain theory. In uniaxial tests, crack behavior was observed that crack initiated in the maximum shear strain direction and propagated in the direction perpendicular to principal stross. But, in biaxial tests, both crack initiation and growth occured on the maximum shear strain direction only.

• Proceedings of the KWS Conference
• /
• 2010.05a
• /
• pp.57-57
• /
• 2010

For thin panel welded structure, the various welding distortions were found due to the low resistance against welding deformation. Especially, buckling distortion induced in the thin panel welded structure produce severe problems related to cost in production stage and safety in service life. So, many researches including mechanical and thermal tensioning method for preventing the occurrence of buckling distortion in the production stage have been performed. The purpose of this study is to identify the behavior of longitudinal residual stress at the SA butt weldment with thin plate of 6mm thickness under tension load by 3 dimensional FEA. For it, mesh design for 3D FEA was constructed with 20 nodes brick element for butt weldment and 8 nodes shell element for base metal. According to FEA results, the longitudinal compressive strain inducing tensile residual stress at the butt weldment decreased. It was because the compressive thermal strain in way of weldment was reduced by tension load. The control effect of residual stress increased with an increase in tension load. So, if the amount of tension load applied to the weldment exceeds 1.5 times of longitudinal shrinkage force, the amount of longitudinal residual stress decreased below the critical value inducing the buckling distortion at the SA butt weldment. Its validity was verified by experiment.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.20 no.9
• /
• pp.749-755
• /
• 2007

Recently, novel MEMS probe cards can support reliable wafer level chip test with high density probing capacity. However, manufacturing cost and process complexity are crucial weak points for low cost mass production. To overcome these limitations, we have developed micro spring structured MEMS probe card. For fabrication of micro spring module, a wire bonder and electrolytic polished gold wires are used. In this case, stringent tension force control is essential to guarantee the low level contact resistance of micro spring for reliable probing performance. For this, relation between tension force of fabricated probe card and contact resistance is characterized. Compare to conventional probe cards, developed MEMS probe card requires fewer fabrication steps and it can be manufactured with lower cost than other MEMS probe cards. Also, due to the small contact scratch patterns, we expect that it can be applied to bumping types chip test which require higher probing density.

• Journal of Korean Neurosurgical Society
• /
• v.29 no.4
• /
• pp.451-460
• /
• 2000

Objective : This experiment is aimed at clarifying the characteristics of spasmodic basilar arteries in the rabbits of subarachnoid hemorrhage(SAH) with observation of vascular response to nitric oxide(NO) and endothelin-1. Material and Methods : Seventy-nine New Zealand white rabbits were divided into 4 groups : control(n=17), sham operation(n=13), postictal-2-day(n=25), and postictal-7-day group(n=24). Rabbits in the postictal-2-day group and postictal-7-day group underwent transfemoral vertebral angiography 2 days and 7 days after SAH respectively. A vascular ring of spasmodic basilar artery was harvested and suspended in organ chamber($37^{\circ}C$) to observe isometric tension changes in response to NO and endothelin-1 under both high(95% $O_2$/5% $CO_2$) and low(95% $N_2$/5% $CO_2$) $O_2$ tension. To investigate the vascular response to NO, acetylcholine from $10^{-7}M$ to $3{\times}10^{-4}M$ concentration was applied to basilar artery ring precontracted with histamine $10^{-6}-10^{-5}M$ in the organ chamber. The vascular response to endothelin-1 was observed by applying endothelin-1 from $10^{-11}M$ to $3{\times}10^{-8}M$ concentration into organ chamber. Results : Seven of 15 live rabbits which underwent angiography 2 days after SAH, were confirmed to develop vasospasm($64.3{\pm}11.2%$) whereas seven of 13 live rabbits which underwent angiography 7 days after SAH, were confirmed to develop vasospasm($64.9{\pm}10.9%$). In all groups, hypoxia significantly reduced the vascular relaxation of basilar arteries to NO. However, hypoxia made no influence on the vascular contraction of basilar arteries to endothelin-1 in all groups. In vascular relaxation of basilar arteries to NO under high $O_2$ tension between groups, the maximum relaxation of basilar arteries in the postictal-7-day group was significantly reduced compared to the postictal-2-day group. In vascular contraction of basilar arteries to endothelin-1 under high $O_2$ tension between groups, the maximum contraction of basilar arteries in the postictal-7-day group was significantly reduced compared to the postictal-2-day group. Conclusions : This experiment suggests that the characteristics of vascular response to NO and endothelin-1 in the spasmodic basilar arteries of rabbits observed 2 days after SAH is different from those observed 7 days after SAH.

• Korean Journal of Acupuncture
• /
• v.25 no.3
• /
• pp.29-41
• /
• 2008

Objectives : The aim of this study is to examine the effects of SSP(silver-spike point) therapy, applied to acupuncture points, on the middle cerebral arteries blood flows of sample group(tention-type headache patients, n=12) and control group(non tension-type headache patients, n=12), and on the reduction of their headaches, when applied to acupuncture points. Methods : We stimulated 6 acupuncture points for headache with the SSP(three times a week for three weeks), and measured VAS(visual analogue scale) and the blood flow of the middle cerebral arteries with TCD(transcranial doppler ultrasonography). Results : The blood flow of the middle cerebral artery and VAS of the sample group and the control group were compared four times(initial, 1weeks, 2weeks, 3weeks) and significant differences in the measurements were found at 3 weeks(p<.05). The blood flow of the middle cerebral artery of the sample group was significantly increased, and VAS was significantly decreased in both groups. Conclusions : The silver-spike-point low-frequency electrical-stimulation treatment, applied to acupuncture points, can significantly increase the blood flow of the middle cerebral arteries in headache patients and can thus alleviate their headaches.

• 제어로봇시스템학회:학술대회논문집
• /
• 1987.10b
• /
• pp.713-716
• /
• 1987

A new approach to the real-time measurement of muscle fatigue by using adaptive filtering algorithm is proposed. Unlike previously reported methods, it can estimate the muscle fatigue at every sample as the EMG signal statistics change. As a result, the muscle conduction velocity ranged between 4.2-5m/s at low tension and 3-4m/s at fatigue state.

• Journal of Bio-Environment Control
• /
• v.9 no.3
• /
• pp.151-155
• /
• 2000

In order to investigate the optimum irrigation point by soil water tension in oriental melon grown in plastic greenhouse during low temperature season, irrigation points from 10 days before fruiting to 10 days before harvesting were examined with 10, 20, 30 and 50 kPa, respectively. Total amount of water applied was 92.5mm at 10kPa but not irrigated at 50kPa due to the unreach of irrigation point. Fruit weight increased with increased soil water content; it was 456g at 10kPa but 324g at 50kPa. While marketable yield of fruit was lowest at 10 kPa due to increased fermented fruit. Sugar content in fruit was highest at 30 or 50 kPa but lowest at 10kPa. As a result, for higher sugar content and marketable yield, the recommended irrigation point is 30kPa of soil water tension.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.25.4-25
• /
• 2001

In this paper, a five degree-of-freedom haptic device is proposed. The proposed haptic device has a pen which is suspended by tensioned six strings. Human operator handles the pen. Six DC motors are used as actuators to generate tensions in six strings to make resultant force feedback at the pen to the human operator Six encoders are used for calculating the movement of the pen. A digital controller is used for generate control signals for the suitable tension in the six strings. A current amplifiers is used for amplifying the control signals. Cable-suspended system has advantages of structure simplicity (only with several strings driven by motors without using other tensioning mechanisms), low inertia, and high force-to-weight ratio. Pen-based system has advantages of compactness and ...

• PNF and Movement
• /
• v.21 no.2
• /
• pp.185-192
• /
• 2023

Purpose: This study aimed to confirm the effectiveness of the diaphragm stretching technique as a treatment method for low back pain by evaluating maximum inspiratory pressure, maximum expiratory pressure, and changes in back mobility in patients with low back pain. Methods: Thirty-four patients with low back pain were randomly divided into two groups: an experimental group and a control group. The diaphragm stretching technique was conducted in the experimental group, and the placebo intervention was conducted in the control group. The diaphragm stretching technique was conducted once, maintaining tension for 7 min. The placebo intervention was conducted in the same position as the diaphragm stretching technique, but with only light contact maintained without pressure. Maximum inspiratory pressure, maximum expiratory pressure, and back mobility were measured before and after the intervention, and the changes were compared and analyzed. A paired sample t-test was used to compare measurements within the group before and after the intervention. An independent t-test was used to compare the experimental and control groups. Statistical significance (α) was set at 0.05. Results: In the experimental group, maximum inspiratory pressure, maximum expiratory pressure, and back mobility increased significantly after the intervention (p < 0.05). However, there was no significant difference in the changes in all areas of the control (p > 0.05). As a result of comparative analysis of changes before and after the intervention, there were significant differences in maximum inspiratory pressure, maximum expiratory pressure, and back mobility only in the experimental group (p < 0.05). Conclusion: The diaphragm stretching technique improved maximum inspiratory pressure, maximum expiratory pressure, and back mobility compared to the placebo intervention. Therefore, the diaphragm stretching technique can be recommended as a physical therapy intervention to improve pain in patients with LBP.

• 한국생물공학회:학술대회논문집
• /
• 2003.04a
• /
• pp.40-44
• /
• 2003

Soil-borne infectious disease including Pythium aphanidermatum and Rhizoctonia solani causes severe damage to plants, such as cucumber. This soil-borne infectious disease was not controlled effectively by chemical pesticide. Since these diseases spread through the soil, chemical agents are usually ineffective. Instead, biological control, including antagonistic microbe can be used as a preferred control method. An efficient method was developed to select an antagonistic strain to be used as a biological control agent strain. In this new method, surface tension reduction potential of an isolate was included in the ‘decision factor’ in addition to the other factors, such as growth rate, and pathogen inhibition rate. Considering these 3 decision factors by a statistical method, an isolate from soil was selected and was identified as Bacillus sp. GB16. In the pot test, this strain showed the best performance among the isolated strains. The lowest disease incidence rate and fastest seed growth was observed when Bacillus sp. GB16 was used. Therefore this strain was considered as plant growth promoting rhizobacteria (PGPR). The action of surface tension reducing component was deduced as the enhancement of wetting, spreading, and residing of antagonistic strain in the rhizosphere. This result showed that new selection method was significantly effective in selecting the best antagonistic strain for biological control of soil-borne infectious plant pathogen. The antifungal substances against P. aphanidermatum and R. solani were partially purified from the culture filtrates of Bacillus sp. GB16. In this study, lipopeptide possessing antifungal activity was isolated from Bacillus sp. GB16 cultures by various purification procedures and was identified as a surfactin-like lipopeptide based on the Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), high performance liquid chromatography mass spectroscopy (HPLC-MS), and quadrupole time-of-flight (Q-TOF) ESI-MS/MS data. The lipopeptide, named GB16-BS, completely inhibited the growth of Pythium aphanidermatum, Rhizoctonia solani, Penicillium sp., and Botrytis cineria at concentrations of 10 and 50 mg/L, respectively. A novel method to prevent the foaming and to provide oxygen was developed. During the production of surface active agent, such as lipopeptide (surfactin), large amount of foam was produced by aeration. This resulted in the carryover of cells to the outside of the fermentor, which leads to the significant loss of cells. Instead of using cell-toxic antifoaming agents, low amount of hydrogen peroxide was added. Catalase produced by cells converted hydrogen peroxide into oxygen and water. Also addition of corn oil as an oxygen vector as well as antifoaming agent was attempted. In addition, Ca-stearate, a metal soap, was added to enhance the antifoam activity of com oil. These methods could prevent the foaming significantly and maintained high dissolved oxygen in spite of lower aeration and agitation. Using these methods, high cell density, could be achieved with increased lipopeptide productivity. In conclusion to produce an effective biological control agent for soil-borne infectious disease, following strategies were attempted i) effective screening of antagonist by including surface tension as an important decision factor ii) identification of antifungal compound produced from the isolated strain iii) novel oxygenation by $H_2O_2-catalase$ with vegetable oil for antifungal lipopeptide production.