• Honam Mathematical Journal
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• v.43 no.2
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• pp.259-267
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• 2021

Given 𝛽 > 1, we consider real numbers whose 𝛽-expansions are Sturmian words. When the slope of Sturmian words varies, their behaviors have been well studied from analytical point of view. The regularity enables us to find the Fourier series expansion, while the singularity at rational slopes yields a new kind of trigonometric series representing 𝜋.

• The Korean Journal of Physiology
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• v.21 no.2
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• pp.157-167
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• 1987

Benzyl alcohol is known to have dual effect on the red blood cell shape change. At low concentration up to 50 mM benzyl alcohol transformed the shape from discocyte to stomatocyte by preferent binding to the inner hemileaflet, however, at higher concentratransformed the shape from discocyte to stomatocyte by preferential binding to the inner monolayer, however, at higher concentration above 50 mM benzyl alcohol transformed to echinocyte by affecting both monolayers. These results suggest that the effect of benzyl alcohol on the red blood cell shape and $Ca^{++}$ transport across cardiac cell membranes to assess the effects of the drug on the structures and functions of the biological cell membranes. The results are as follows: 1) Benzyl alcohol up to 40 mM caused progressive stomatocytic shap change of the red blood cell but above 50 mM benzyl alcohol caused echinocytic shape change. 2) Benzyl alcohol up to 40 mM inhibited both osmotic hemolysis and osmotic volume change of the red blood cell in hypotonic and hypertonic NaCl solutions, respectively. 3) Benzyl alcohol inhibited both Bowditch Staircase and Wood-worth Staircase phenomena at rat left auricle. 4) Benzyl alcohol at concentration of 5 mM increased $Ca^{++}-ATPase$ activity of red blood cell ghosts slightly but above S mM benzyl alcohol inhibited the $Ca^{++}-ATPase$ activity. 5) Benzyl alcohol at concentrations of 5 mM and 10 mM increased $Ca^{++}-ATPase$ activity slightly at rat gastrocnemius muscle S.R. but above 10 mM benzyl alcohol inhibited the $Ca^{++}-ATPase$ activity. Above results indicate that benzyl alcohol inhibit water permeability and $Ca^{++}$ transport across cell membranes in part via effects on the fluidity and transition temperatures of the bulk lipid by preferential intercalation into cytoplasmic monolayer and in part via other effect on the conformational change of active sites of the $Ca^{++}-ATPase$ molecule extended in cytoplasmic face.

• Journal of Korean Neurosurgical Society
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• v.40 no.3
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• pp.180-185
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• 2006

Objective : Middle cerebral artery occlusion[MCAO] has widely been used to produce ischemic brain lesions. The lesions induced by MCAO tend to be variable in size because of the variance in the collateral blood supply found in the mouse brain. To establish a less invasive and reproducible focal ischemia model in mice, we modified the technique used for rat photo thrombosis model. Methods : Male C57BL/6 mice were subjected to focal cerebral ischemia by photothrombosis of cortical microvessels. Cerebral infarction was produced by intraperitoneal injection of Rose Bengal, a photosensitive dye and by focal illumination through the skull. Motor impairment was assessed by the accelerating rotarod and staircase tests. The brain was perfusion-fixed for histological determination of infarct volume four weeks after stroke. Results : The lesion was located in the frontal and parietal cortex and the underlying white matter was partly affected. A relatively constant infarct volume was achieved one month after photothrombosis. The presence of the photothrombotic lesion was associated with severe impairment of the motor performance measured by the rotarod and staircase tests. Conclusion : Photothrombotic infarction in mice is highly reproducible in size and location. This procedure can provide a simple method to produce cerebral infarction in a unilateral motor cortex lesion. In addition, it can provide a suitable model for study of potential neuroprotective and therapeutic agents in human stroke.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.3
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• pp.298-306
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• 2008

STATEMENT OF PROBLEM: Effect of surface treatment of ceramic under loading does not appear to have been investigated. PURPOSE: The aim of this study was to investigate the effect of surface treatment of esthetic ceramic, which is performed to increase the bonding strength, on the fracture stress under controlled cyclic loading condition. MATERIAL AND METHODS: Sixty 1.0 mm-thick specimens were made from Mark II Vitablocs (Vita Zahnfabrik, Germany) and divided into 3 groups: polished (control), sandblasted, and etched. Specimens of each group were bonded to a dentin analog material base including micro-channels to facilitate the flow of water to the bonding interface. Bonded ceramics were cyclically loaded with a flat-end piston in the water (500,000 cycles, 15Hz). Following completion of cyclic loading, specimens were examined for subsurface crack formation and subsequent stress was determined and loaded to next specimen by the staircase method according to the crack existence. RESULTS: There were significant differences of mean fatigue limit in the sandblasted (222.86 ${\pm}$ 23.42 N) and etched group (222.86 ${\pm}$ 14.16 N) when compared to polished group (251.43 ${\pm}$ 10.6 N) (P<.05; Wald-type pair-wise comparison and post hoc Bonferroni test). Of cracked specimens, surface treated group showed longer crack propagation after 24 hours. All failures originated from the radial cracking without cone crack. Fracture resistance of this study was very low and comparable to failure load in the oral cavity. CONCLUSION: Well controlled cyclic loading could induce clinically relevant cracks and fracture resistance of Mark II ceramic was relatively low applicable only to anterior restorations. Surface treatment of inner surface of feldspathic porcelain in the matsicatory area could influence lifetime of restorations.

• Korean Journal of Applied Biomechanics
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• v.20 no.3
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• pp.267-275
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• 2010

The purpose of this study was to investigate the effects of balance ability improvement exercise program which applied to the elderly people for increasing balance, stability and range of motion. Ten elderly people and ten university students were recruited as the subjects. Kinematic data were collected by seven real-time infrared cameras while subjects walk stair descent as a pre-test. Korean folk dance exercise program was applied to the elderly for 12 weeks. Same experiment on stair descent walk was performed as post-test. Results indicated that CM movement and selected joint angle patterns of elderly group after treatment changed to the similar patterns of young group. However, ankle joint angle and vertical GRF of elderly group after treatment also increased compared to those of the elderly group before treatment. This might be explained by the fact that elderly used a different walking strategy which maximize support base for increasing stability. Overall, these results indicated that the exercise treatment may affect to adapt and improve the gait pattern of stair descent of elderly people.

• Journal of the Korean housing association
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• v.26 no.5
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• pp.123-131
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• 2015

The purpose of this study is to suggest an optimum guide line of the unit plan design in national housing (less than $85m^2$ of exclusive floor area in a dwelling unit). The unit plan of apartment have been improved diversely for the residents, and the family members per household have been decreased for decades comparing with the past. In contrast, the living space per household has been increased steadily, it is because of the improvement of the living standard. The unit plan have been improved from 2-bay corridor access type and 2~3 and 4-bay staircase type. In december 2005, the balcony was permitted to be used as exclusive living area without the increase of the original living area by law. So the apartment residents have been able to use more spacious area exclusively in a dwelling unit. On the other hand, the legalization on permitting balcony area into a exclusive area resulted in a distorted wide and enlarged plan only for the business profit improvement lately. The living environment has been changed differently unlike at the time of the legislation of the national housing. The family member per household has been decreased and the related law and the institution has also been changed. Moreover It has passed 40 years since the legislation of national housing ($85m^2$). So, The size of national housing should be reviewed according to the current trend in terms of the decrease of household and the utilization of balcony area.

• Journal of Oral Medicine and Pain
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• v.26 no.4
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• pp.309-318
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• 2001

The purposes of the study were (1) to evaluate the olfactory identification ability in those who have bad breath, (2) to determine the olfactory detection threshold for methyl mercaptan in normal subjects and those who have bad breath, and (3) to evaluate the effect of oral hygiene care on the olfactory detection threshold for methyl mercaptan. Sixteen male subjects with bad breath (male odor group), 9 male subjects without bad breath (male non-odor group), and 10 female subjects without bad breath (female non-odor group) were included for the study. Olfactory identification ability was assessed by administrating the Cross-Cultural Smell Identification Test (CC-SIT), and the olfactory detection threshold for methyl mercaptan was measured by two-alternative forced-choice single-staircase detection threshold procedure in a double-blinded condition. The geometric mean of the last four staircase reversal points of a total of seven reversals is used as the threshold. For the male odor group, after 1 month of intensive oral hygiene care for reducing oral volatile sulfur compounds (VSC) concentration, the olfactory detection threshold for methyl mercaptan was measured again and compared to the initial value. The ANOVA was used to test the group difference of olfactory threshold and olfactory identification ability and the paired t-test was used to test the difference of olfactory threshold between before and after reduction of oral VSC in male odor group. The results were as follows : 1. There was no significant difference in olfactory identification ability among those who have bad breath and normal male or female subjects. 2. The olfactory detection threshold for methyl mercaptan was about 8.4 ppb in normal male and female. 3. There was a tendency that male subjects with bad breath showed a higher olfactory detection threshold for methyl mercaptan when compared to those of no bad breath. 4. The olfactory detection threshold for methyl mercaptan returned to a normal level after 1 month of intensive oral hygiene care for reducing oral VSC.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.8
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• pp.638-644
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• 2010

We have carry out numerical simulation of the electric-optical characteristics of organic light emitting diodes with gradient-doped emitting layer which were reported to be effective in improving luminous efficiency and lifetime. In this paper, the basic structure is comprised of ITO/NPB/$Alq_3$:C545T[%]/$Alq_3$/LiF/Al, six devices by separating the emitting layer of $Alq_3$:C545T[%] were studied. As the result, the uniformly-doped devices exhibited superior luminous efficiency-current density characteristics over conventional undoped device. In the case of gradient-doped devices, electric-optical characteristics were improved similar to uniformed-doped devices, unusually the distribution of traped-charge density in the OLED devices was shown as the staircase.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.269-272
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• 2002

This work describes the use of neural networks (NNs) for interpreting voltammetric data, i.e., current-voltage spectra that obtained from the electrochemical reaction of analyte species at a gold electrode. Current-voltage spectra of glucose, fructose and ascorbic acid in mixtures obtained from dual-pulse staircase voltammetry (DPSV) was in the form of the mixed responses contain characteristics of the individual analytes approximately in proportion to their concentration. Extraction of individual analyte concentration from combined data was subsequently achieved using NNs. The combination of DPSV and NNs opens a possibility for simultaneous determination of mixtures of the species for fruit juices quality monitoring.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.640-644
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• 2007

The purpose of the present research is to provide a plan for an effective evacuation of residents and people who's in need of evacuation (such as children, the handicapped, and the old) and for the situation when staircase is not available for evacuation, by means of analyzing the evacuation behavioral characteristics of the residents or the evacuators and suggesting an evacuation plan using an emergency elevator in order to minimize casualties in case when fire broke out in a skyscraper.