• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.2
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• pp.346-351
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• 1997

The creep characteristics of an Al-5wt.% Ag alloy including the stress exponent, the activation energy for creep and the shape of the creep curve were investigated at a normalized shear stress extending from $ 10^{-5}{\;}to{\;}3{\times}10^{-4}$ and in the temperature range of 640-873 K, where silver is in solid solution. The experimental results shows that the stress exponent is 4.6, the activation energy is 141 kJ/mole, and the stacking fault energy is $180{\;}mJ/m^2$, suggesting that the creep behavior of Al-5 wt.% Ag is similiar to that reported for pure aluminum, and that under the current experimental conditions, the alloy behaves as a class II(metal class). The above creep characteristics obtained for Al-5 wt.% Ag are discussed in the light of prediction regarding deformation mechanisms in solid solution alloys.

• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.4
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• pp.446-454
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• 2017

Recently, there have been many studies on bulk-fill resin composites. However, studies on the proper materials for pediatric patients are rare. The aim of this study was to compare the cavity wall adaptation of bulk-fill resin composites with conventional resin composite in class II cavities of primary molars using microcomputed tomography (micro-CT). Standardized class II slot cavities were prepared in 80 exfoliated primary molars and randomly divided into 4 groups. The control group was restored with conventional resin composite, Filtek Z-350 XT (FZ), and the three groups were restored with bulk-fill resin composites, Filtek bulk-fill posterior (FB), Tetric N-Ceram Bulk Fill (TNC), Filtek bulk-fill flowable (FBF). All specimens were thermocycled and then immersed in 50% silver nitrate ($AgNO_3$) solution. Micro-CT was used to measure the penetration volume of the total silver nitrate and the degree of cervical marginal leakage and the number, size, and position of the voids were evaluated. The results revealed that the volume of silver nitrate were significantly different between FB and FZ (p < 0.05). The results also revealed that the penetration length of silver nitrate FBF showed statistically lower than the FZ and FB (p < 0.05). There was no significant difference between the groups in number and size of voids. In conventional resin composite, most of the voids were present inside the restoration (83.3%), but the voids in the bulk-fill resin composites incidence were higher in the gingivoaxial angle. The cavity wall adaptation demonstrated in class II restorations of primary molar by new bulk fill resin composites was similar to conventional incremental technique. Bulk-fill resin composites might be an clinical option for a faster restoration in deciduous teeth.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2009.11a
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• pp.115-118
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• 2009

고령화 사회를 맞이하여 다양한 실버제품들이 이들을 위해 출시되고 있으나, 이들이 느끼는 실버 제품의 거부감에 대한 연구는 부족한 실정이다. 이를 위해 사전에 연구된 실버 제품의 거부감에 대한 연구를 바탕으로 그 가설을 검증하도록 한다.

• Journal of Fashion Business
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• v.19 no.1
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• pp.95-105
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• 2015

This study investigated the color culture in the Japanese Medieval Age. The Japanese Medieval Age included the Kamakura period (1180-1333) and Muromachi period (1336-1573), and the leading group transitioned from the Kuge families to the Buke families. The taboos about colors from ancient times became nominal, and forbidden colors, such as purple, celadon, and red, became the colors of the samurai, leading to beautiful soldier gears that were unparalleled in history. In the Kamakura period, colors that conveyed a strong impression were created and preferred with the combination of a samurai's reasonable spirit and zen thoughts. The period was also called "the era of hari", and cross dyeing based on basic colors such as suou (red), ai (blue), and kuchinasi (yellow) was popular. In both the Kamakura and Muromachi periods, conspicuous and strong colors were sought for costumes, and embroidery was used with gold leaf, silver leaf, gold threads, silver threads, and background color. The colors of costume preferred by Buke men in the period included green, blue, and brown. In the characteristics of the kosode, the sugan and hitadare were used for men's formal dress, while kosode was used for the grooming of the working class. In these periods, additionally, the working class began to be socially engaged in actively wearing the one-layer kosode, which became popular, and the characteristics of the Japanese Medieval Age, during which functionality and practicality was valued, were also reflected in the dressing.

• Journal of the Korean Operations Research and Management Science Society
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• v.38 no.4
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• pp.11-33
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• 2013

We analyzed the structures and properties of the global financial market networks using social network analysis approach. The Minimum Spanning Tree (MST) lengths and networks of the global financial markets based on the correlation coefficients have been analyzed. Firstly, similar to the previous studies on the global stock indices using MST length, the diversification effects in the global multi-asset portfolio can disappear during the crisis as the correlations among the asset class and within the asset class increase due to the system risks. Second, through the network visualization, we found the clustering of the asset class in the global financial markets network, which confirms the possible diversification effect in the global multi-asset portfolio. Meanwhile, we found the changes in the structure of the network during the crisis. For the last one, in terms of the degree centrality, the stock indices were the most influential to other assets in the global financial markets network, while in terms of the betweenness centrality, Gold, Silver and AUD. In the practical perspective, we propose the methods such as MST length and network visualization to monitor the change of the correlation risk for the risk management of the multi-asset portfolio.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.270-273
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• 2008

The point of the meaning, this study selects population which is aged over 65 and new silver generation who is aged between 55 to 64. The objects were selected by purposeful sampling method and the 933 objects who participated in leisure sports age over 55 were used for this thesis's analysis. The results of the study were as follow; First, the weekly participation frequency was physical psychological burden, facilities, information technology, interpersonal relations, concern lack, time lack, bear. there was statistically significant difference. Second, the daily workout time was physical psychological burden, facilities, information technology, interpersonal relations, concern lack, time lack, bear. there was statistically significant difference. Third, the participant experience was physical psychological burden, facilities, information technology, interpersonal relations, concern lack, time lack, bear. there was statistically significant difference.

• Journal of KIISE:Information Networking
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• v.31 no.4
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• pp.414-428
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• 2004

Many portable devices are coming to be commercially successful and provide useful services to mobile users. Mobile devices may request a variety of data types, including text and multimedia data, thanks to the rich content of the Internet. Different types of data and/or different classes of users may need to be treated with different qualities of service. The implementation of service differentiation in wireless networks is very difficult because of device mobility and wireless channel contention when the backoff algorithm is used to resolve contention. Modification of the t)mary exponential backoff algorithm is one possibility to allow the design of several classes of data traffic flows. We present a study of modifications to the backoff algorithm to support three classes of flows: sold, silver, and bronze. For example, the gold c]ass flows are the highest priority and should satisfy their required target bandwidth, whereas the silver class flows should receive reasonably high bandwidth compared to the bronze class flows. The mixture of the two different transport protocols, UDP and TCP, in ad hoc networks raises significant challenges when defining backoff algorithm modifications. Due to the different characteristics of UDP and TCP, different backoff algorithm modifications are applied to each class of packets from the two transport protocols. Nevertheless, we show by means of simulation that our approach of backoff algorithm modification clearly differentiates service between different flows of classes regardless of the type of transport protocol.

• Culinary science and hospitality research
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• v.14 no.4
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• pp.257-268
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• 2008

The purpose of this study was to conduct factor analysis on Foodservice consumers' lifestyle patterns in dietary life, classify lifestyle patterns, and identify how lifestyle patterns influence the 5 stages of decision making process for purchase. Among 300 copies of the distributed questionnaire, 259 copies were collected for this study. It used a total of 283 copies as the effective samples for empirical analysis except 12 copies with false entries among them. For data analysis, it conducted frequency analysis, validity and reliability analysis, factor analysis, and multiple regression analysis using SPSS 12.0. As a result, Hypothesis 1 was significant while Hypothesis 2, 3, and 5 were partially significant. On the contrary, Hypothesis 4 was not significant. Therefore, lifestyle patterns had partially significant effects on decision making process for dining-out purchase. This study subdivided dining-out consumers' lifestyles which were limited to dietary life, and also subdivided decision making process for dining-out consumers' dining-out purchase into five stages. It is significant and very suggestive that this study identified what lifestyle patterns concretely had significant effects on the specific decision making stage. In the future, the researches on adolescent class and silver class should be executed continuously.

• Journal of Science Education
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• v.41 no.1
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• pp.111-134
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• 2017

The purpose of this study was to develop 'Silver Care Expert' STEAM Program for the elementary students and investigate the effects of the program on creative thinking activity, scientific attitude and leadership. Participants were 110 elementary school students. Before and after the program, the participants were asked to take the test about future time perspective, career awareness and scientific attitude. The major results of this study were as follows. First, the total score of experimental group's future time perspective and all 2 sub-domains was significantly improved than those of comparative group(p<.05). Second, total score of experimental groups' career awareness and all 4 sub-domains were significantly increased than those of comparative group after the STEAM program(p<.05). Third, the total score of experimental groups' scientific attitude and all 7 sub-domains were significantly improved than those of comparative group(p<.05). Fourth, according to students' post-program opinions, experimental group students showed very positive perception like that science class was very interesting and they became interested in science and technology. In conclusion, 'Silver Care Expert' STEAM Program was very effective to improve elementary students' future time perspective, career awareness, scientific attitudes.

• Journal of the korean academy of Pediatric Dentistry
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• v.23 no.3
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• pp.746-763
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• 1996

An alternative design to conventional class II cavity preparation for proximal carious lesions is the tunnel preparation. It preserves the marginal ridge intact, thus making it possible to maintain the natural contact relationship with the adjacent tooth and minimize tooth reduction. This in vitro study was purposed to evaluate the effect of the materials' elastic constants and shear-bond strength on the marginal ridge fracture resistance of teeth restored by the tunnel technique, and to find the materials of choice for tunnel restorations. $Resinomer^{(R)}$, $Ketac-silver^{(R)}$, $Miracle-Mix^{(R)}$, and Tytin were used as restorative material. The elastic constants of each restorative material were evaluated by ultrasonic pulse measurement. Young's modulus and bulk modulus of the restorative materials were evaluated in three specimens for each material type. The shear-bond strength of the restorative materials to the dentin surface was measured after thermocycling 400 times between 6 and $60^{\circ}C$, using ten specimens for each material type. For measuring marginal ridge strength, 60 sound extracted molar teeth were distributed into six groups by size. Sound molar teeth were used as a Control group and unfilled prepared teeth were grouped as Unrestored. Another four groups were named Resinomer group, Ketac-Silver group, Miracle Mix group, and Tytin group by type of restorative material. Tunnel cavity preparation was done with ' 1/2, 2, and 4 round burs in sequence. Initial access to proximal surface was made through an occlusal access preparation started at least 2mm from the marginal ridge, and the proximal opening was formed about 2.5mm below the marginal ridge. After restoration and thermocycling, marginal ridge strength was measured using a universal testing machine. The results were as follows: 1. The Young's modulus of $Tytin^{(R)}$ was 63.95 GPa, followed by $Ketac-Silver^{(R)}$ 27.60 GPa, $Miracle-mix^{(R)}$ 18.48 GPa, and $Resinomer^{(R)}$ 10.74 GPa showing significant differences between the groups(P<0.05). The bulk modulus of the materials showed the same order as Young's modulus. The value of $Tytin^{(R)}$ showed 59.57 GPa indicating that it will deform less than other materials under the same stress. It was followed by $Ketac-Silver^{(R)}$ 23.57 GPa, Miracle $Mix^{(R)}$ 12.50 GPa, and $Resinomer^{(R)}$ 11.60 GPa. 2. The Resinomer group had a shear-bond strength of 7.41 MPa which was significantly higher than those of the Ketac-Silver group (1.80 MPa) and the Miracle Mix group (2.84 MPa) (P<0.01). All the specimens of Tytin group detatched from the dentin surface during thermocycling. 3. The mean marginal ridge strength of the Unrestored group(46.14 kgf) was significantly lower than that of the Control group (84.24 kgf) (P<0.01). The marginal ridge strength of teeth restored by the tunnel technique was, in order, Ketac-Silver group 74.06 kgf, Miracle Mix group 73.36 kgf, Resinomer group 63.47 kgf, and Tytin group 58.76 kgf. The Ketac-Silver, Miracle Mix, and Resinomer groups showed no significant difference with the Control group (P>0.05), but the Tytin group showed significantly lower strength compared to the Control group(P<0.05). The results showed that the marginal ridge strength of the teeth restored by the tunnel technique was not significantly lower than that of sound teeth. They also demonstrated that the bonding strength of the restorative material to the tooth surface should be high and the modulus of elasticity should not be lower than that of the tooth in order to restore the marginal ridge strength to its natural condition.