• The Mathematical Education
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• v.16 no.2
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• pp.22-26
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• 1978

It is shown that a map having an extension to an open map between the Alex-androff base compactifications of its domain and range has a unique such extension. J.S. Wasileski has introduced the Alexandroff base compactifications of Hausdorff spaces endowed with Alexandroff bases. We introduce a definition of morphism between such spaces to obtain a category which we denote by ABC. We prove that the Alexandroff base compactification on objects can be extended to a functor on ABC and that the compact objects give an epireflective subcategory of ABC. For each topological space X there exists a completely regular space $\alpha$X and a surjective continuous function $\alpha$$_{x}$ : Xlongrightarrow$\alpha$X such that for each completely regular space Z and g$\in$C (X, Z) there exists a unique g$\in$C($\alpha$X, 2) with g=g$^{\circ}$$\beta$$_{x}$. Such a pair ($\alpha$$_{x}$, $\alpha$X) is called a completely regularization of X. Let TOP be the category of topological spaces and continuous functions and let CREG be the category of completely regular spaces and continuous functions. The functor $\alpha$ : TOPlongrightarrowCREG is a completely regular reflection functor. For each topological space X there exists a compact Hausdorff space $\beta$X and a dense continuous function $\beta$x : Xlongrightarrow$\beta$X such that for each compact Hausdorff space K and g$\in$C (X, K) there exists a uniqueg$\in$C($\beta$X, K) with g=g$^{\circ}$$\beta$$_{x}$. Such a pair ($\beta$$_{x}$, $\beta$X) is called a Stone-Cech compactification of X. Let COMPT$_2$ be the category of compact Hausdorff spaces and continuous functions. The functor $\beta$ : TOPlongrightarrowCOMPT$_2$ is a compact reflection functor. For each topological space X there exists a realcompact space (equation omitted) and a dense continuous function (equation omitted) such that for each realcompact space Z and g$\in$C(X, 2) there exists a unique g$\in$C (equation omitted) with g=g$^{\circ}$(equation omitted). Such a pair (equation omitted) is called a Hewitt's realcompactification of X. Let RCOM be the category of realcompact spaces and continuous functions. The functor (equation omitted) : TOPlongrightarrowRCOM is a realcompact refection functor. In [2], D. Harris established the existence of a category of spaces and maps on which the Wallman compactification is an epirefiective functor. H. L. Bentley and S. A. Naimpally [1] generalized the result of Harris concerning the functorial properties of the Wallman compactification of a T$_1$-space. J. S. Wasileski [5] constructed a new compactification called Alexandroff base compactification. In order to fix our notations and for the sake of convenience. we begin with recalling reflection and Alexandroff base compactification.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.4
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• pp.349-360
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• 2009

Purpose: As the esthetic demands of dental implant patients are increased, the demands of zirconia as implant abutment material are also increased. It has non-metalic color, good biocompatibility, high strength and high toughness. Even thought the advatage of zirconia abutment, there are a few studies about mechanical properties of zirconia abutment. This study evaluated the mecanical strength with compressive bending strength and endurance limit of implant-zirconia abutment assembly. Materials and Methods: Static and cyclic loading of implant-Zirconia abutment assembly were simulated under worst case condition according to ISO. Test groups were implants of external butt joint with straight regular diameter and angled regular diameter zirconia abutment, implant of external butt joint with narrow straight diameter zirconia abutment and implant of internal conical joint with straight narrow diameter zirconia abutment. All test group were evaluated the mecanical strength with compressive bending strength and endurance limit. After fatique testing, fracture surface were examined by SEM. Results: The compressive bending strengths exceed 927N. Regular diameter zirconia abutment were stronger than narrow diameter zirconia abutment(P<.05). The endurance limits ranged from 503N to 868N. Conclusion: Within the limitation of this study, zirconia implant abutment exceeded the estabilished values for maximum incisal biting forces reported in the literature.

• Journal of Life Science
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• v.21 no.7
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• pp.997-1003
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• 2011

Menopause and obesity are associated with metabolism. The purpose of this study was to examine the changes of PPAR${\gamma}$, PGC-1(${\alpha},\;{\beta}$), NRf-1 and TFAM mRNA and mitochondria biogenesis in adipocytes and investigate the effect of swimming exercise for 6weeks on ovariectomized rats. Rats were randomly assigned to 3 groups: (1) ovariectomized rats fed with a control diet (C, n=4), (2) ovariectomized rats fed with high fat diet (H, n=4), and (3) ovariectomized rats trained to exercise and fed with high fat diet (H+EX, n=4). Exercise was performed by swimming for 5 days/wk, with a progressive increase in exercise over the course of 6 weeks. Results showed that the fat tissue weight in the H group was markedly increased (p<0.01) compared to other groups, however, regular exercise significantly decreased fat weight. The PPAR-${\gamma}$ (p<0.05), PGC-$1{\alpha}$ (p<0.01), -$1{\beta}$ (p<0.05), NRf-1 (p<0.01) and TFAM (p<0.05) mRNA expression in the adipocytes of H+EX were higher than in the H group. These results suggest that regular exercise for 6 weeks might exert positive effects by increasing PPAR-${\gamma}$, PGC-1 (${\alpha},\;{\beta}$), NRf-1 and TFAM mRNA expression and mitochondria in adipocytes. Thus, regular exercise may be helpful in the improvement of mitochondria biogenesis function in obese, ovariectomized rats.

• Journal of Korean Academy of Nursing
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• v.26 no.4
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• pp.833-852
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• 1996

Regular long term dance movement could be one of ways to induce improvement of psychophysiological variables, resulting in improvement of quality of life. However, there have been few studies to evaluate the effect of dance movement training on both physiological and psychological variables in the elderly. This study was focused to determine the effect of Korean traditional dance movement training on psychophysiological variables-body weight, body fat, lean body mass, muscle strength, muscle endurance, flexibility, agility, resting heart rate and blood pressure, depression and life satisfaction-in Korean elderly women. Thirty four subjects, aged between 65 and 75years who have normal cognition, sensory function, cerebellum function, cardiovascular function, participated in this study. Seventeen experimental group subjects were selected from E-elderly university in Kyung Gi province, and Seventeen control group subjects were selected from N-welfare facility in Seoul City. Seventeen experimental group subjects participated for 12weeks dance movement program. Korean traditional dance movement program was developed on the basis of Korean traditional dance and music by the author. The program consisted of approximately 50minutes of dance, 3times a week for 12weeks. During 50minutes workout, there were 15minutes of warm-up dancing, 25minutes of conditioning dance and 10minutes of cool-down dancing. The intensity for the conditioning phase was at between 60% and 65% of age-adjusted maximum heart rates. The body weight, body fat, lean body mass, muscle strength(grip strength, leg strength), muscle endurance, flexibility, agility, resting heart rate and blood pressure, depression and life satis-faction were measured prior to and following the experimental treatment. The participants in dance movement were interviewed focusing on subjective feeling following 12 week's regular dance movement. Data were analyzed with mean, standard deviation, percentage of change, X²-test, t-test, and ANCOVA test using SPSS PC/sup +/ program. Subjective feeling was categorized into cognitopsy-chological and physiological responses. Results were obtained as follows : 1) The body weight (F=15.52, p=.000), body fat (F=18.33, p=.000) and lean body mass (F=7.28, p=.011) of the experimental group were significantly lower than those of the control group following the dance movement training. 2) The leg strength (F=30.96, p=.000), muscle endurance (F=9.06, p=.005), agility(F=44.92, 000), flexibility(F=6.84, p=.014) of the experimental group were significantly higher than those of the control group following the dance movement training. There was no significant difference of grip strength(F=.43, p=.515) between experimental and control groups. 3) The heart rate(F=26.96, p=.000), systolic (F=10.40, p=.000) and diastolic(F=3.99, p=.005) blood pressure at rest of the experimental group were significantly lower than those of the control group following the dance movement training. 4) No significant difference of score of depression (F=3.49, p=.071) was observed between experimental and control groups. 5) Score of life satisfaction of experimental group was remarkably higher than that of control group following 12weeks of dance movement training (p<0.05). 6) Thematic responses about the dance movement following the training were positive. "I feel good" was the most frequent among cognitopsychological responses and "I feel lightness of body" was the most frequent among physiological responses. The results suggest that Korean traditional dance movement training can improve psychophysiological variables of Korean elderly.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.5
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• pp.437-444
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• 2020

This study was focused on the stabilization of surge motions of a moored vessel under irregular head seas. A two-point moored vessel shows strong non-linearity even in regular sea, owing to its inherent non-linear restoring force. A long-crested irregular wave is subjected to the vessel system, resulting in more complex nonlinear behavior of the displacement and velocities than in the case of regular waves. Sliding mode control (SMC) is implemented in the moored vessel to control both surge displacement and surge velocity. The SMC can provide a closed-loop system with performance and robustness against parameter uncertainties and disturbances; however, chattering is the main drawback for implementing SMC. The goal of minimizing the chattering and state convergence with accuracy is achieved using a quasi-sliding mode that approximates the discontinuous function via a continuous sigmoid function. Numerical simulations were conducted to validate the effectiveness of the proposed control algorithm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.2002-2011
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• 2015

This study was performed to determine the levels of physical function (ADL, IADL) and to reveal its association with the related factors in the elderly people. The study subjects were 1,756 (male 872, female 884) people aged over 70 who received medical check-ups and long-term care services between 2009 and 2012 from the National Health Insurance Corporation. As a result, the distribution of impaired ADL and IADL increased significantly with age. Logistic regression showed that the risk ratio of impaired ADL was increased significantly in the following groups: female, urban, low weight, stroke history group, smoking, alcohol drinking, and not regular exercise group. The risk ratio of an impaired IADL were increased significantly in the group of females, low weight, smoking, alcohol drinking. On the other hand the risk ratio of an impaired ADL and IADL was similar in each age group. As above results, the levels of ADL and IADL in the study subjects are closely related to the socio-demographic characteristics and health related behaviors. In particular, they suggested that the levels of ADL and IADL were lower in the poor group of the health-related behaviors, such as smoking, alcohol drinking, and regular exercise.

• Journal of Life Science
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• v.21 no.10
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• pp.1415-1421
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• 2011

The purpose of this study was to identify the effects of an L-arginine supplementation and regular exercise training on NF-${\kappa}B$, TNF-${\alpha}$, iNOS, Cav-1, eNOS and Ang II in the aortas of D-galactose (D-gal) induced aging rats. The male Strague-Dawley rats were treated with a D-galactose aging inducing agent; the D-gal injection (50 mg/kg) was given intraperitoneally for 12 wk. Experimental groups were divided into five groups: (1) Young control group (Y-Con, n=8), (2) Aging control group (A-Con, n=8), (3) Aging exercise group (A-Ex, n=8), (4) Aging exercise group with L-arginine supplementation group (A-Ex+A, n=8), and (5) Aging with L-arginine supplementation group (A-A, n=8). The exercise consisted of running on a treadmill for 60 min/day at 20 m/min for 6 day/wk, at 0% gradient for 12 wk. The L-arginine supplementation was given orally at a dose of 150 mg/kg/day for 12 wk. The findings of this study were as follows: 1. NF-${\kappa}B$, TNF-${\alpha}$, iNOS, Cav-1 and Ang II proteins in the aortas of D-gal induced rats were significantly increased, however, L-arginine supplementation and regular exercise resulted in a significant inhibition in the expression of NF-${\kappa}B$, TNF-${\alpha}$, iNOS, Cav-1 and Ang II proteins. 2. eNOS protein in the aortas of D-gal induced rats was significantly decreased, however, L-arginine supplementation and regular exercise resulted in a significant increase in the expression of eNOS proteins. In conclusion, the findings of the present study reveal that L-arginine supplementation alone or regular exercise alone or in combination with L-arginine supplementation for 12 wk increases anti-inflammatory effects by decreasing NF-${\kappa}B$, TNF-${\alpha}$, and iNOS protein expressions within the aortic tissue. In addition, L-arginine supplementation alone or regular exercise alone or in combination with L-arginine supplementation may prevent endothelial function by up-regulation of eNOS protein in the aortas of D-gal induced aging rats.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.1916-1922
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• 2014

This study focuses on observing the brain function characteristics of maladaptive soldiers, through EEG analysis. The number of subjects was 1,119 including 59 maladaptive soldiers, 60 normal soldiers and 1,000 civil youths. The EEG measurements were performed from Sep. 2013 to Jan. 2014. As a result of the study, first, the soldier group's BRQ, ATQ, EQ, ASQ and BQ values were significantly higher than civil youth's, on the contrary to SRQ, ACQ, CQ which were higher in civil youth group. Second, compared to normal soldiers, the values of EQ and BQ were meaningfully low in maladaptive soldiers group, as well as the average values of each 8 quotient. In conclusion, military service can be assumed to have a positive effect on brain function of all soldiers due to regular life cycle, usual physical activities and balanced nutrition, but less effect on maladaptive soldiers who are exempted from those strict life.

• Journal of Korean Academy of Nursing
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• v.45 no.3
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• pp.388-396
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• 2015

Purpose: The purpose of this study was to identify the effects on cognitive function, depression, and activities of daily living of Silver- Care-Robot Program for institutionalized elders. Methods: This study was a nonequivalent control group pretest-posttest design. The participants were 42 institutionalized elders (17 in the experimental group and 25 in the control group). The Silver-Care-Robot Program was provided as an intervention which was conducted twice a week for 5 weeks. The Silver-Care-Robot Program is an integrated entertainment program to help the mental, emotional, and physical health of elderly people. Pre-test was conducted on the two groups, and, in order to examine the effects of intervention, a post-test was conducted after 5 weeks. Results: There were significant differences in cognitive function and ADL (activities of daily living) between two groups after the program. But the difference in depression in the institutionalized elders was not statistically significant between the two groups. Conclusion: The Silver-Care-Robot Program should be considered as a regular program for cognitive function and activities of daily living for institutionalized elders.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.3
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• pp.291-305
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• 2010

A three-dimensional time-domain calculation method is of crucial importance in prediction of the motions and wave loads of a ship advancing in a severe irregular sea. The exact solution of the free surface wave-ship interaction problem is very complicated because of the essentially nonlinear boundary conditions. In this paper, an approximate body nonlinear approach based on the three-dimensional time-domain forward-speed free-surface Green function has been presented. The Froude-Krylov force and the hydrostatic restoring force are calculated over the instantaneous wetted surface of the ship while the forces due to the radiation and scattering potentials over the mean wetted surface. The time-domain radiation and scattering potentials have been obtained from a time invariant kernel of integral equations for the potentials which are discretized according to the second-order boundary element method (Hong and Hong 2008). The diffraction impulse-response functions of the Wigley seakeeping model advancing in transient head waves at various Froude numbers have been presented. A simulation of coupled heave-pitch motion of a long rectangular barge advancing in regular head waves of large amplitude has been carried out. Comparisons between the linear and the approximate body nonlinear numerical results of motions and wave loads of the barge at a nonzero Froude number have been made.