• Journal of Ocean Engineering and Technology
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• v.23 no.4
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• pp.69-77
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• 2009

Structural analysis of a brake shoe for commercial vehicle was performed using finite element method. Since the strength of a brake shoe is affected by the magnitude and distribution shape of the contact pressure with the drum, the contact pressure between the shoe friction material and drum was calculated using a 2-Dimensional non-linear contact analysis in a state. And the brake was actuated by input air pressure and the drum of it was calculated both stationary and dynamic based on forced torque applied to the drum during the static state analysis. The results of the above analysis were then used as the load boundary conditions for a 3-Dimensional shoe model analysis to determine the maximum strain on the shoes. In the analysis model, the values of tensile test were used for the material properties of the brake shoes and drum, while the values of compression test were used for the friction material. We assumed it as linear variation, even though the properties of friction material were actually non-linear. The experiments were carried out under the same analysis conditions used for fatigue test and under the same brake system which equipped with a brake drum based on the actual axle state in a vehicle. The strains were measured at the same locations where the analysis was performed on the shoes. The obtained results of the experiment matched well with those from the analysis. Consequently, the model used in this study was able to determine the stress at the maximum air pressure at the braking system, thereby a modified shoe model in facilitating was satisfied with the required endurance strength in the vehicle.

• YAKHAK HOEJI
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• v.58 no.3
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• pp.181-189
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• 2014

The aim of this was to evaluate the effects of Rhus Verniciflua Stoke (RVS) extract powder on the endurance capacity for the forced swimming mice. Thirty mice were divided into 3 groups including negative control, 250 (RVS-250) and 500 (RVS-500) mg/kg RVS extract powder groups for 4-times swimming exercises. The swimming times to exhaustion in RVS-250 and RVS-500 mice were prolonged 1.6- and 2.0-fold at 4 weeks compared with negative control mice, respectively. Blood biochemical parameters for AST, ALT, T-CHO and TG were not significantly different between RVS fed or negative control mice. However, blood concentration of creatinine was significantly increased in RVS-250 mice, but not in RVS-500 mice. During the longer swimming exercise in RVS group, blood glucose and lactate levels were significantly decreased, but free fatty acid not changed. And also LDH levels were significantly decreased in RVS groups compared to negative control mice. Hepatic lipid peroxidation was not affected by RVS, but SOD and catalase activity were significantly increased in RVS groups. Interestingly, the levels of testosterone and free testosterone were significantly increased in RVS groups before swimming exercise, but they were not significantly changed among groups after swimming exercise. The present results suggest that RVS extract powders may enhance swimming exercise performance by recovering the exercise-fatigue via reduction of blood LDH activity and by burning blood glucose as an energy source. These results imply that RVS-produced testosterone may act as an energy buster to enhance physical activity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.521-528
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• 2018

Military vehicles use run-flat wheels for emergency situations. Run-flat wheels can run required distance in a defined duration with the pressure loss tire. For the application of a run-flat system, wheels are designed in 2 pieces, including an inner rim and outer rim. These rims are assembled using clamping bolts. Clamping bolts determine the durability of military vehicle wheels because fracture of clamping bolts account for most wheel failures. For improving wheel durability, clamping bolt durability must be improved. In this study, wheel test conditions and bolt design were investigated. Existing test standards are not sufficient to conduct endurance tests. Supplementary conditions were investigated. Using these modified test conditions, the durability of wheels including clamping bolts was tested and verified. Results found the durability of wheels improved more than 168%. This study also proposes improvements in the design process of clamping bolts.

• The Journal of Internal Korean Medicine
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• v.43 no.3
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• pp.423-435
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• 2022

Purpose: The purpose of this study was to confirm the clinical efficacy of Gyeongok-go. Methods: Public/Publisher MEDLINE (PubMed), Cochrane Central Register of Controlled Trials (CENTRAL), Excerpta Medica dataBASE (EMBASE), Research Information Sharing Service (RISS), ScienceON, Korean Traditional Knowledge Portal (KTKP), and China National Knowledge Infrastructure (CNKI) were searched for randomized controlled clinical trials administering Gyeongok-go as an intervention, published from inception to December 31, 2021. The risk-of-bias of the included trials was assessed with the Cochrane risk-of-bias tool for randomized trials version 2. From the experimental and control groups of the selected trials, the mean value (or rate) of each outcome was extracted and statistically compared. Results: Statistically significant mean differences were in VO₂max (MD 6.82), post-exercise heart rate (MD -8.76 at 5 min, -11.58 at 30 min, -14.6 at 60 min), senescence scale (MD -6.52), Th1 cells and Th2 cells in pulmonary tuberculosis (MD 2.79 and -1.64), yin-deficient and qi-deficient score (MD -9.64 and -9.76), and phlegm-dampness score (MD 5.56). Overall risk-of-bias was 20% low risk, 80% some concerns, and 0% high risk. There were no reports of adverse events. Conclusions: Gyeongok-go is likely to have the effect of improving cardiorespiratory endurance, increasing fatigue recovery ability, reducing senescence, and enhancing immune function in tuberculosis patients. Also, it is more suitable for those who are yin-deficient or qi-deficient, and those with phlegm-dampness probably need caution.

• Journal of Korean Society of Forest Science
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• v.101 no.4
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• pp.626-634
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• 2012

The purpose of this study was to investigate the potential of persimmon vinegar as a functional beverage by analyzing the effects of persimmon vinegar ingestion on the energy substrate during endurance exercise. The healthy male adolescents (n=8) drunk persimmon vinegar ingested trial (PSV) or purified water ingested trial as the control trial (CON) 1 h prior to the exercise with the 60% of maximal oxygen uptake ($\dot{V}O_{2max}$) for 1 h. The exercise intensity was increased to the 80% of $\dot{V}O_{2max}$ and remained until exhaustion. And, the physiological variables, blood components, and amounts of energy oxidation were analyzed. There was no significant difference between trials in physiological variables, and the heart rates after exhaustion were higher in PSV compared to CON. There was no significant difference between trials in blood glucose level, while the blood lactic acids decreased significantly in PSV 30 and 60 minutes after onset of exercise. The free fatty acids concentration increased significantly in PSV from 15 minutes to 60 minutes after onset of exercise. The carbohydrate oxidation decreased significantly in PSV from 45 minutes after exercise and, on the contrary, the fatty acids oxidation increased significantly for the same period. And, fatty acids oxidation was higher in PSV compared to CON even after exhaustion. The respiratory exchange ratio was lower significantly in PSV compared to CON from 30 minutes to 60 minutes after exercise, whereas lower in CON after total exhaustion. The exercise time to exhaustion was 41% longer in PSV compared to CON. These results showed that the persimmon vinegar increase the level of lipids metabolism and decrease sense of fatigue by inhibiting carbohydrate oxidation during moderate intensity exercise, suggesting the possibility of using of persimmon vinegar as exercise functional beverage when ingested 1 h prior to the endurance exercise performance.

• Journal of Korean Academy of Nursing
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• v.29 no.4
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• pp.766-779
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• 1999

The purpose of this study was to investigate the relationship between the burden on families who live with an elderly person suffering from senile dementia, and the degree of their depression. There were 400 participants in this study, staying in the Seoul and Kyonggi areas from August 1, 1997 to February 28, 1998. Among the group, 100 participants took care of their patient at home, and another 300 participants left 100 patient at a day-care center, 100 sanatorium for senile dementia(asylum for helpless elderly people), 100 an infirmary for elderly people. Eventually 242 subjects out of the 400 were selected for the data analysis. The Zarit (1980) tool was employed to measure the degree of burden and Zung's(1965) “Self-Rating Depression Scale” was employed for the data analysis. The data was analyzed, and the percentage, t-test, ANOVA and Person's Correlation Coefficient were calculated. The results are as follows : 1. The average degree of burden that care-giving families felt was 49.13, which is somewhat high. 2. The average degree of depression that care -giving families felt was 51.95, which is relatively high. 3. The degree of burden was directly affected by the relation with the patient(F＝2.48, P＜.05), and the socio-economic status of the family(F＝5.17, P＜.05). Its also affected by the patient's educational status(F＝2.17, P＜.05). 4. The degree of depression of the family was significantly dependent on sex(t＝-2.05, P＜.05), age (F＝2.99, P＜.05), the relationship with the patient(F＝3.65, P＜.01), socio-economic status (F＝7.74, P＜.001), occupation(t＝2.82, P＜.01), health status(F＝4.42, P＜.01), and the place of residence(F＝4.30, P＜.01), The patient characteristics was significantly dependent on his/her educational status(F＝3.85, P＜.01), the period of suffering from senile dementia(F＝2.47, P＜.05), and smoking habit(F＝6.17, P＜.001). 5. The relationship between the degree of burden and that of depression reads r＝0.43, which is statistically positive correlation in the high significant level. Upon analyzing the entire summation, most care-givers for elderly patients suffering from senile dementia lack time in caring for themselves. They also experience chronic fatigue and mental discomfort caused by the isolation from society, curtailment of certain activities, a sense of responsibility for their patients, and limits of their endurance in taking care of their patients over time. In conclusion, this study emphasizes the necessity for the following propositions : 1. In order to measure the degree of burden that Korean care-giving families undergo, a new tool must be developed on the basis of Korean culture. 2. An educational program based on the demands that care-giving families undergo must be developed, and its clinical effect also has to be examined.

• Journal of the Korean Vacuum Society
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• v.17 no.1
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• pp.28-33
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• 2008

Lanthanum modified lead zirconate titanate ($Pb_{1.1}La_{0.08}Zr_{0.65}Ti_{0.35}O_3$) thin films were fabricated on indium doped tin oxide (ITO)-coated glass substrate by R.F magnetron sputtering method. The thin films were deposited at $500^{\circ}C$ and post-annealed with various temperature ($550-750^{\circ}C$) by rapid thermal annealing technique. The structure and morphology of the films were characterized with X-ray diffraction (XRD) and atomic force microscopy (AFM) respectively. The hysteresis loops and fatigue properties of thin films were measured by precision material analyzer. As the annealing temperature was increased, the remnant polarization value was increased from $10.6{\mu}C/cm^2$ to $31.4{\mu}C/cm^2$, and coercive field was reduced from 79.9 kV/cm to 60.9 kV/cm. As a result of polarization endurance analysis, the remnant polarization of PLZT thin films annealed at $700^{\circ}C$ was decreased 15% after $10^9$ switching cycles using 1MHz square wave form at ${\pm}5V$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.236-236
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• 2008

(Bi,La)$Ti_3O_{12}$(BLT) thin film is one of the most attractive materials for ferroelectric random access memory (FRAM) applications due to its some excellent properties such as high fatigue endurance, low processing temperature, and large remanent polarization [1-2]. The authors firstly investigated and reported the damascene process of chemical mechanical polishing (CMP) for BLT thin film capacitor on behalf of plasma etching process for fabrication of FRAM [3]. CMP process could prepare the BLT capacitors with the superior process efficiency to the plasma etching process without the well-known problems such as plasma damages and sloped sidewall, which was enough to apply to the fabrication of FRAM [2]. BLT-CMP characteristics showed the typical oxide-CMP characteristics which were related in both pressure and velocity according to Preston's equation and Hernandez's power law [2-4]. Good surface roughness was also obtained for the densification of multilevel memory structure by CMP process [3]. The well prepared BLT capacitors fabricated by CMP process should have the sufficient ferroelectric properties for FRAM; therefore, in this study the electrical properties of the BLT capacitor fabricated by CMP process were analyzed with the process parameters. Especially, the effects of CMP pressure, which had mainly affected the removal rate of BLT thin films [2], on the electrical properties were investigated. In order to check the influences of the pressure in eMP process on the ferroelectric properties of BLT thin films, the electrical test of the BLT capacitors was performed. The polarization-voltage (P-V) characteristics show a decreased the remanent polarization (Pr) value when CMP process was performed with the high pressure. The shape of the hysteresis loop is close to typical loop of BLT thin films in case of the specimen after CMP process with the pressures of 4.9 kPa; however, the shape of the hysteresis loop is not saturated due to high leakage current caused by structural and/or chemical damages in case of the specimen after CMP process with the pressures of 29.4 kPa. The leakage current density obtained with positive bias is one order lower than that with negative bias in case of 29.4 kPa, which was one or two order higher than in case of 4.9 kPa. The high pressure condition was not suitable for the damascene process of BLT thin films due to the defects in electrical properties although the better efficiency of process. by higher removal rate of BLT thin films was obtained with the high pressure of 29.4 kPa in the previous study [2].

• Korean Journal of Food Science and Technology
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• v.37 no.2
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• pp.214-220
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• 2005

Effect of terrapin or snake extract on forced-swimming capacity and related biochemical parameters of SD rats was evaluated. Treatment groups were fed diet supplemented with 5% terrapin extract or 1% snake extract for 4 weeks. After adaptation for 1 week, each group was divided into two subgroups: one group swam for 90 min (90-min subgroups), and the other swam until exhaustion (all-out subgroups). No significant difference was observed in swimming time until exhaustion among the groups. After swimming for 90 min, contents of fatigue factors of serum such as lactate, inorganic phosphate, creatine kinase, and ammonia were not significantly different (p < 0.05) between control and treatment groups, including all-out subgroups, except for lactate concentration. These results indicated that terrapin or snake extract had little effect on forced-swimming capacity of rats.

• Journal of Life Science
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• v.28 no.5
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• pp.621-626
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• 2018

We introduced the physiological responses of aging, active aging and also suggest the impact of physical exercise on body health status and elderly immunity. In this purpose, we searched the Pub Med data base for the articles (include our experimental papers) and review papers having the terms 'Aging', 'Active aging' and 'Physical activity and elderly' in the title, published from 1999 until 2018. The results were as follows: Exercise training has been extensively studied about the reduction of inflammation, oxidative stress, disease, and aging in syndrome X patients and elderly. Combined and aerobic or resistance exercise training could reduce obesity, insulin resistance, type 2 diabetes and hypertension. Exercise training has been extensively studied in cancer settings as part of prevention or treatment strategies. From this research, regular exercise has the potential to target tumor growth through regulation of inflammation and immune responses such as lactate clearance, NK cell activation (innate immunity), activation of cytotoxic immune cells, T cell activation (adaptive immunity), and immune surveillance. However, Endurance physical activity not only induces thermogenesis and diverse sports injuries but also elicits mobilization and functional enhancement of monocytes, neutrophils (which is caused by the cytokine changes such as TNF-alpha, IL-1) whereas it suppresses cell mediated immunity causing to increased susceptibility to inflammation and infections like cough and URTIs (upper respiratory track infections) in young and especially in elderly people. Therefore, Strategies to prevent physical fatigue, sports injuries include avoid overtraining, Adequate recovery and various type of rest during and after physical activity and assuring adequate nutrition supplementation such as glutamine, vitamin B, vitamin C, carbohydrate, ion or berry-contain sports beverages is helpful in physically active elderly.