• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.290-296
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• 2019

Head-up displays for vehicles play an important role in displaying various information about the safety and convenience of driving on the windshield of the vehicle. In this study, ultra-precision machining was performed and evaluated as a method for machining a large-area aspheric free-form mirror that is applicable to augmented reality technology. Precision diamond cutting is highly accurate and suitable for the production of advanced parts with excellent surface integrity, low surface roughness, and low residual stress. By using an aspheric free-form mold, it is possible to improve the optical transfer function, reduce the distortion path, and realize a special image field curvature. To make such a mold, the diamond cutting method was used, and the result was evaluated using an aspherical shape-measuring machine. As a result, it was possible to the mold with shape accuracy (PV) below $1{\mu}m$ and surface roughness (Ra) below $0.02{\mu}m$.

• Structural Engineering and Mechanics
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• v.86 no.3
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• pp.291-309
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• 2023

This paper addresses the finite element modeling of functionally graded porous (FGP) beams for free vibration and buckling behaviour cases. The formulated finite element is based on simple and efficient higher order shear deformation theory. The key feature of this formulation is that it deals with Euler-Bernoulli beam theory with only three unknowns without requiring any shear correction factor. In fact, the presented two-noded beam element has three degrees of freedom per node, and the discrete model guarantees the interelement continuity by using both C⁰ and C¹ continuities for the displacement field and its first derivative shape functions, respectively. The weak form of the governing equations is obtained from the Hamilton principle of FGP beams to generate the elementary stiffness, geometric, and mass matrices. By deploying the isoparametric coordinate system, the derived elementary matrices are computed using the Gauss quadrature rule. To overcome the shear-locking phenomenon, the reduced integration technique is used for the shear strain energy. Furthermore, the effect of porosity distribution patterns on the free vibration and buckling behaviours of porous functionally graded beams in various parameters is investigated. The obtained results extend and improve those predicted previously by alternative existing theories, in which significant parameters such as material distribution, geometrical configuration, boundary conditions, and porosity distributions are considered and discussed in detailed numerical comparisons. Determining the impacts of these parameters on natural frequencies and critical buckling loads play an essential role in the manufacturing process of such materials and their related mechanical modeling in aerospace, nuclear, civil, and other structures.

• Journal of Families and Better Life
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• v.25 no.5
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• pp.167-183
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• 2007

The purpose of this study was to investigate the changes in infant-mother interactions and to measure infant-mother interaction, mutuality, and reciprocity at the 2nd and 6th postnatal monthperiods. Infant-mother interaction was assessed in the mornings, afternoons, and evenings in the 2nd and 6th postnatal months, by filming unstructured free play in the home and analyzing 28 of these infant-mother film recordingsusing two trained observers. This study can be summarized in five points. First, the separate frequency distribution of each category in MIIBR's maternal behavior was as follows: the frequencies of vocalization category, the kinesthetic exercise & physical contact category, the physical caregiving category, and theuse of play tool category. These all showed changes in the 6th postnatal month compared to the 2nd postnatal month. Second, the separate frequency distribution of each category in MIIBR's infant behavior was as follows: the frequencies of physical behavior category, the vocalization category, and the play behavior category. These also all showed changes in the 6th postnatal month compared to the 2nd postnatal month. Third, the mutuality and reciprocity of mother interaction decreased in the 2nd postnatal month compared to the 6th postnatal month. Fourth, mutuality and reciprocity in the infant interaction increased in 2nd postnatal month compared to the 6th postnatal month. Fifth, mutuality and reciprocity in the infant-mother interaction increased in 2nd postnatal month compared to the 6th postnatal month. In conclusion, it is evident that infant-mother interactions change over time. This study bears particular significance in setting a foundation for the theoretical basis of the interaction between infant and mother by observation.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.7
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• pp.949-956
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• 2002

There are several physiological and pharmacological evidences indicating that opening of voltage dependent $Ca^{2+}$ channels play a critical role in induction of acrosome reaction in mammalian sperm. We determined the intracellular free $Ca^{2+}$ concentration in ejaculated goat sperm using a fluorescent, $Ca^{2+}$-specific probe, Fura2/AM, after the suspension of sperm in KRB medium, capable of sustaining capacitation and the acrosome reaction. We used nifedipine, D-600 and diltiazem, the $Ca^{2+}$ channel antagonists belonging to the classes of dihydropyridines, phenylalkylamines and benzothiazepines, to investigate the possibility that L-type voltage gated $Ca^{2+}$ channels play a role in the progesterone-stimulated exocytotic response. Progesterone promoted a rise in intracellular $Ca^{2+}$ in goat sperm and addition of nifedipine (100 nM) just prior to progesterone induction, significantly inhibited both intracellular $Ca^{2+}$ rise and exocytosis suggesting that $Ca^{2+}$ channels are involved in the process. However, the intracellular $Ca^{2+}$ increase during the process of capacitation was not affected with the addition of nifedipine suggesting a role of focal channel for $Ca^{2+}$ during capacitation. Studies using monensin and nigericin, two monovalent cation ionophores showed that an influx of $Na^+$ also may play a role in the opening of $Ca^{2+}$ channels. These results strongly suggests that the entry of $Ca^{2+}$ channels with characteristics similar to those of L-type, voltage-sensitive $Ca^{2+}$ channels found in cardiac and skeletal muscle, is a crucial step in the sequence of events leading to progesterone induced acrosome reaction in goat sperm.

• Korean Journal of Social Welfare
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• v.60 no.3
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• pp.201-230
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• 2008

While the constitutional states emerged in the period of the constitutional monarchies to protect freedom and property of citizens from a illegal trespass of monarchs, the passive role of the constitutional states to protect them was changed in the modern parliamentary democracy in which the state is to play an active role to realize the basic rights. Today the state giving chances and social benefits to citizens plays a very important role so that the people may to enjoy a free life as a citizen. In the modern parliamentary democracy the role of the state, therefore, is transformed form passive roles to active ones realizing the basic rights for citizens. The active role of the state to embody the basic rights asks the parliament to bear more the responsibility for making laws than ever before. In the modern welfare state social rights are also recognized as a basic right. In this sense the parliament should play a active role to realize the social rights. But the Korean parliament excessively turns over his legislative right on the basis of a delegated legislation to the Administration. It does not fulfill its responsibility for which the modern parliamentary democracy asks. To realize the social rights the Korean parliament should play a more active role.

• The Journal of the Convergence on Culture Technology
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• v.8 no.5
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• pp.385-392
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• 2022

Our society, which has arrived in the 4th industrial revolution, emphasizes covergence education to cultivate creative convergence talents. Therefore, this study is to develop a convergence education program consistent with the direction of the 2019 revised Nuri course and to help teachers who want to implement convergence education. In order to achieve this purpose, in this study, voluntary questions that occurred in play using the educational robot 'Turtle' were classified as STEAM elements. After that, frequency analysis and correlation analysis were conducted. Therefore, this study is meaningful in collecting children's questions about the same robot by age, and it is valuable in establishing future convergence education directions by analyzing the correlation by STEAM elements.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.12
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• pp.1695-1699
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• 2004

The antioxidant enzymes, lipid peroxidation and free radicals assessment were made of the effects of selenium, copper and magnesium on bovine endemic fluorosis under high fluoride, low selenium and low copper productive conditions. Thirty-two beef cattle were selected from high fluoride area, and randomly divided into four groups with eight cattle each as follows: (1) high fluoride control group (HFC); (2) supplemented group with 0.25 mg/kg selenium (HFSe); (3) supplemented group with 15 mg/kg copper (HFCu) and (4) supplemented group with 0.25 mg/kg selenium+15 mg/kg copper+1 mg/kg magnesium (HFSeCuMg) per day for 83 days. Moreover, eight beef cattle were selected from non-high fluoride area as normal control group. Blood samples were collected from cattle on 0 d, 30 d and 83 d respectively, to analyze the enzyme activities and concentration of GSH-px, CAT, SOD, MDA and free radicals. The results showed that the contents of free radicals and MDA in HFC group were significantly higher, and the whole blood GSH-px, CAT, erythrocyte SOD activities were lower than the normal control group. Free radicals, metabolic imbalance and antioxidant disorder therefore, play an important role in fluorosis. However, GSH-px, CAT and SOD activities in HFSe group and HFSeCuMg group at 30 d and 83 d were markedly higher than the same groups at the 0 d and the HFC group at the same time. Likewise, there was a corresponding reduction in the contents of free radicals and MDA. These findings indicated that supplementation with selenium, copper and magnesium elevated high fluoride bovine antioxidant enzymes, and decreased MDA and free radicals contents. But, the activities of supplementation selenium group did not increase until day 83. These results demonstrated that fluorosis was associated with lower serum Se and Cu levels than in the control, and it was therefore concluded that fluorosis is associated with decreased serum levels of these minerals. Long-term high fluoride intake under productive condition enhances oxidative stress in the blood, thereby disturbing the antioxidant defense of cattle. Increased oxidative stress could be one of the mediating factors in the pathogenesis of toxic manifestations of fluoride. It is benefical for high fluoride cattle supplemented with proper selenium, copper and magnesium to increase fluoride excretion and obtain the protective impact of the activity of oxidative enzymes, and to decrease lipid peroxidation and free radicals contents.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.10 no.1
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• pp.76-90
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• 1999

This study was performed 1) to compare the nature of the synchronized behaviors in mother-child plays between autistic and normal groups quantitatively and qualitatively and 2) to identify the behavioral data to improve synchrony. The subjects were consisted of 20 mother-child pairs, 10 for each autistic group(AG) and normal group(NG). The developmental age of two groups was under 24 months old and equally matched. Data were collected by video-taped mother-child free play and analyzed with Wilcoxon Rank Sign(Sum) Test, Spearman Correlation Coefficient, Scheffe's Test, and Content Analysis. The score on synchronized behaviors of AG was significantly lower than that of NG(p<.05). As time progressed, the difference was much higher between the 2 groups. And the structure of motherchild plays in AG was poor and most of the interactions were discontinued as 1 or 2 episodes. On the other hand, mother-child plays in NG were enriched and became somewhat like game or play. The score of mother's growth-fostering nurturing behaviors showed positive relation to synchrony and much highly related to the group of 16 months-old or above. Mother's laughing and patting responses and pausing to get the child's initiative were especially related highly to synchronized behaviors. In conclusion, these mother's growth-fostering nurturing behaviors should be stressed at the mother-child interactions and also well structured therapeutic play with considering in children's developmental level should be given.

• Journal of Music and Human Behavior
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• v.21 no.2
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• pp.77-105
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• 2024

This study explored whether story-based interactive music activities improve play interactions between children with developmental disabilities (DD) and typically developing (TD) children at an integrated daycare center, and whether these activities influence TD children's attitudes towards their DD peers. The participants included six children with DD, aged 3-5 years, and 21 TD peers. They attended 10 sessions, each 30 minutes, twice a week. Play interactions were observed during free play after each session, and TD children's attitudes towards peers with DD were assessed before and after the intervention. The results showed that children with TD and DD in the integrated group showed significantly reduced disengagement, with notable improvements in joint action for TD children and joint attention for DD children. However, there were no significant changes in peer acceptance among TD children in the integrated group while there was a significant decrease in the non-integrated group. This study highlights that story-based interactive music activities effectively enhance interactions between TD and DD children. However, the limited impact on peer acceptance suggests the need for more long-term and systematic interventions, considering the children's developmental levels. The study also emphasizes the importance of tailored approaches that address the individual needs of both TD and DD children, providing valuable insights into the direction of systematic interventions at a time when the importance of social integration is increasingly recognized.

• The Korean Journal of Pharmacology
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• v.18 no.2
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• pp.89-102
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• 1982

The $Na^+-and\;K^+-induced\;Ca^{++}$ release was measured isotopically by millipore filter technique in pig heart mitochondria. With EGTA-quenching technique, the characteristics of mitochondrial $Ca^{++}-pool$ and the sources of $Ca^{++}$ released from mitochondria by $Na^+\;or\;K^+$ were analyzed. The mitochondrial $Ca^{++}-pool$ could be distinctly divided into two components: internal and external ones which were represented either by uptake through inner membrane, or by energy independent passive binding to external surface of mitochondria, respectively. In energized mitochondria, a large portion of $Ca^{++}$was transported into internal pool with little external binding, while in de-enerigzed state, a large portion of transported $Ca^{++}$ existed in the external pool with limited amount of $Ca^{++}$ in the internal pool which was possibly transported through the $Ca^{++}-carrier$ present in the inner membrane. $Na^+$ induced the $Ca^{++}$ release from both internal pool and external pool and external binding pool of mitochondria. In contrast, $K^+$ did not affect $Ca^{++}$ of the internal pool, but, displaced $Ca^{++}$ bound to external surface of the mitochondria. When the $Ca^{++}-reuptake$ was blocked by EGTA, the $Ca^{++}$ release from the internal pool by $Na^+$ was rapid; the rate of $Ca^{++}-efflux$ appeared to be a function of $[Na^+]^2$ and about 8mM $Na^+$ was required to elicit half-maximal velocity of $Ca^{++}-efflux$. So it was revealed that $Ca^{++}-efflux$ velocity was particulary sensitive to small changes of the $Na^+$ concentration in physiological range. Energy independent $Ca^{++}-binding$ sites of mitochondrial external surface showed unique characteristics. The total number of external $Ca^{++}-binding$ sites of pig heart mitochondria was 29 nmoles per mg protein and the dissociation constant(Kd) was $34{\mu}M$. The $Ca^{++}-binding$ to the external sites seemed to be competitively inhibited by $Na^+\;and\;K^+$; the inhibition constant(Ki) were 9.7 mM and 7.1 mM respectively. Considering the intracellular ion concentrations and large proportion of $Ca^{++}$ uptake in energized mitochondria, the external $Ca^{++}-binding$ pool of the mitochondria did not seem to play a significant role on the regulation of intracellular free $Ca^{++}$ concentration. From this experiment, it was suggested that a small change of intracellular free $Na^+$ concentration might play a role on regulation of free $Ca^{++}$ concentration in cardiac cell by influencing $Ca^{++}-efflux$ from the internal pool of mitochondria.