• The Journal of the Korean dental association
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• v.12 no.8
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• pp.613-617
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• 1974

The authors have studied the marginal leakage of various dental cements; Fynal cement (Caulk), Zinc cement (S.S. White) Carbo cement (Shofu, Poly-carboxylate cement), EBA cement (Opotow alumina cement), Propac (G-C's zinc oxide euginol cement), and Super cement (Shofu oxyphosphate zinc cement), by means of penetration of 2% methylene blue solution between orden crown restorations and human teeth in 150 cases. The result revealed as follow 1. None of the cements tested were free from dye penetration. 2. There was a wide difference in dye penetration among the trade brands of dental cement when immersed in dye solution before setting of cements. 3. EBA cement and Carbo cement showed comparatively low grade of dye penetration at the restorative margins.

• Journal of applied mathematics & informatics
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• v.6 no.1
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• pp.79-88
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• 1999

This work aims to establish an algorithm for solving the problem of convex programming with several objective-functions with linear constraints. Starting from the idea of Rosen's algorithm for solving the problem of convex programming with linear con-straints and taking into account the solution concept from multi-dimensional programming represented by a program which reaches "the best compromise" we are extending this method in the case of multidimensional programming. The concept of direction of min-imization is introduced and a necessary and sufficient condition is given for a s∈Rn direction to be a direction is min-imal. The two numerical examples presented at the end validate the algorithm.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.109-117
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• 2015

This paper proposes the comparison results of various optimal power flow algorithms (OPF) to calculate the locational marginal prices (LMP) of the unreduced full scale Korean transmission system. Five different types of optimal power flow models are employed: Full AC OPF, Cubic AC OPF, Quadratic AC OPF, Linear AC OPF and DC OPF. As the results, full AC OPF and cubic AC OPF model provides LMP calculation results very similar to each other while the calculation time of cubic AC OPF model is faster than that of the Full AC OPF. Other simplified OPF models, quadratic AC OPF, linear AC OPF and DC OPF offer erroneous results even though the calculation times are much faster than the Full AC OPF and the Cubic AC OPF. Given the condition that the OPF models sometimes fail to find the optimal solution due to the severe complexity of the Korean transmission power system, the Full AC OPF should be used as the primary OPF model while the Cubic AC OPF can be a promising backup OPF model for the LMP calculations and/or real-time operation.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.57
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• pp.111-135
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• 2013

This study analyzes some important spin-off effects of the provision, UCP600 Article 14(6), through the methodology of the expected utility maximization theory based on the state-contingent commodities model. Some technical implications of this study are as follows. First, the risk-averse beneficiary will choose to present his documents more than 5 days before expiry date by paying a higher risk premium (so-called cure period) for full assurance to cure documentary discrepancies, if expressed economically, he pursues loss reducing activities to the point where the expected marginal product of his activities is less than its marginal cost. Secondly, where the effectiveness of securing cure period is uncertain, the risk-averse beneficiary will choose to present documents just on the expiry date without securing any cure period by paying no risk premium. This study finally suggests the safe harbor standard should be optimal solution only if it is supplemented by the hidden reasonableness standard for balancing the conflicts of interest between beneficiaries and banks.

• Journal of the Korean Operations Research and Management Science Society
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• v.34 no.4
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• pp.123-138
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• 2009

This study examined the first- and second-best pricing by stable dynamics in congested transportation networks. Stable dynamics, suggested by Nesterov and de Palma (2003), is a new model which describes and provides a stable state of congestion in urban transportation networks. The first-best pricing in user equilibrium models introduces user-equilibrium in the system-equilibrium by tolling the difference between the marginal social cost and the marginal private cost on each link. Nevertheless, the second-best pricing, which levies the toll on some, but not all, links, is relevant from the practical point of view. In comparison with the user equilibrium model, the stable dynamic model provides a solution equivalent to system-equilibrium if it is focused on link flows. Therefore the toll interval on each link, which keeps up the system-equilibrium, is more meaningful than the first-best pricing. In addition, the second-best pricing in stable dynamic models is the same as the first-best pricing since the toll interval is separately given by each link. As an effect of congestion pricing in stable dynamic models, we can remove the inefficiency of the network with inefficient Braess links by levying a toll on the Braess link. We present a numerical example applied to the network with 6 nodes and 9 links, including 2 Braess links.

• Restorative Dentistry and Endodontics
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• v.15 no.1
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• pp.97-105
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• 1990

When conventional root canal treatment is failed or contraindicated, retrograde root canal filling following apicoectomy is a valuable procedure, aimed at hermetically sealing the root canal against leakage of irritants from the canal into the periapical tissue. In this in vitro investigation, to analyze apical microleakage electrochemically in teeth with different retrograde filling materials and preparation types, single - rooted tooth was cut 2mm from the apex and each Class I and Slot preparation was prepared. Experimental groups : Group 1. Amalgam filling with cavity varnish in Class I preparation Group 2. Scotchbond 2+Silux filling in Class I preparation Group 3. Gutta percha filling with ZOE cement in Class I preparation Group 4. Amalgam filling with cavity varnish in Slot preparation Group 5. Scotchbond 2+Silux filling in Slot preparation Each specimens was immersed in 1% solution of KCl, and applied a potential of 9V external power supply. Measurements of the current flow were obtained at 1, 2, 3, 7, 9, 12, 14, 18, 21, 25 and 28 day after immerson. Marginal microleakage were compared and evaluated. The results were as follows ; 1. The group filled with composite resin with dentin bonding agent shows lower apical microleakage value than the group filled with amalgam following varnish application (P<0.01). 2. In the group filled with gutta percha, apical microleakage value was the hightest 3. There was no significant difference between Class I cavity and Slot type cavity regardless of the used materials.

• Restorative Dentistry and Endodontics
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• v.12 no.2
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• pp.17-23
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• 1987

The purpose of this study was to evaluate the sealing properties of endodontic cavity filling materials according to the time intervals after filling. Access cavities were prepared in extracted human premolar or molar teeth and filled with caviton, zinc oxide eugenol cement, zinc oxide eugenol cement with a base of gutta percha stopping and gutta percha stopping. After filling at the intervals of immediate, 2 days and 2 weeks the teeth were immersed for 2 weeks in 1% methylene blue solutions. Longitudinal sections were obtained from approximately center of teeth and the depth of dye penetration into the access cavities were observed by 10${\times}$macrolens. The following results were obtained. I. All the materials experimented showed varying depth of dye penetration. 2. Of the material tested, caviton showed the best marginal sealing qualities regardless of the time intervals after filling and the sealing properties of the gutta percha stopping was the worst. 3. Both in zinc oxide eugenol cement and zinc oxide eugenol cement with a base of gutta percha stopping, the fillings allowed to mature for 2 days in normal saline solution showed the best sealing properties and those with no maturing time revealed the worst sealing qualities. 4. The sealing qualities of zinc oxide eugenol cement with a base of gutta percha stopping revealed slightly lower depth of dye penetration than that of zinc oxide eugenol cements.

• Journal of Korea Society of Industrial Information Systems
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• v.27 no.2
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• pp.61-69
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• 2022

A multi-agent system is a system that aims at achieving the best-coordinated decision based on each agent's local decision. In this paper, we consider a multi agent-multi task assignment problem. Each agent is assigned to only one task and there is a completion probability for performing. The objective is to determine an assignment that maximizes the sum of the completion probabilities for all tasks. The problem, expressed as a non-linear objective function and combinatorial optimization, is NP-hard. It is necessary to design an effective and efficient solution methodology. This paper presents an approximation algorithm using submodularity, which means a marginal gain diminishing, and demonstrates the scalability and robustness of the algorithm in theoretical and experimental ways.

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.2
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• pp.135-142
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• 2010

Purpose: This study was aimed to compare the margin and internal fitness of single anterior all-ceramic crown zirconia core made by three deferent CAD/CAM systems. Material and methods: Five single zirconia cores were manufactured by three deferent CAD/CAM systems($Cerasys^{(R)}$system, KaVo $Everest^{(R)}$system, $LAVA^{TM}$system). The manufactured zirconia cores were duplicated through the use of replica technique, and a replicated sample was sectioned in the center of bucolingual and mesiodistal direction to measure the marginal and internal gap. Measurement was carried out by using measuring microscope ($AXIO^{(R)}$) and $I-Solution^{(R)}$ and analysed through the use of ANOVA. Results: As for the mean marginal fitness of the zirconia core, it was $84.74{\pm}27.57{\mu}m$, in $Cerasys^{(R)}$, $80.23{\pm}21.07{\mu}m$ in KaVo $Everest^{(R)}$ and $96.37 {\pm}11.45{\mu}m$ in $LAVA^{TM}$, and as for the mean internal gap, it was $94.11{\pm}30.07{\mu}m$ in $Cerasys^{(R)}$, $92.31{\pm}25.18{\mu}m$ in KaVo $Everest^{(R)}$, and $94.99{\pm}18.74 {\mu}m$ in $LAVA^{TM}$. There was no significant statistically deference among the total average gap of three systems. The internal gap in KaVo $Everest^{(R)}$ seemed to be smaller than $LAVA^{TM}$ (P < .05). The internal gap in the incisal area was larger in all of the three systems. Conclusion: There was no difference in marginal fitness in $Cerasys^{(R)}$, KaVo $Everest^{(R)}$ and $LAVA^{TM}$. As for the internal fitness, it was smaller in KaVo $Everest^{(R)}$ system than $LAVA^{TM}$ system. In all of the three systems, there was a larger gap in incisal area. The marginal and internal gap was within the clinically allowed range in all of the three systems.

• The Journal of the Korean dental association
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• v.48 no.8
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• pp.615-620
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• 2010

Purpose: The short dental implant is considered as possible solution in the alveolar bone height deficient cases. The aim of this study was to evaluate clinical availability of short implants by measuring the marginal bone loss of short length implants and comparing with that of conventional length implants. Materials and Methods: The groups were composed of patients who had received at least one implant. The samples of this study were selected from patients who with functional loading after prosthetic treatment for 1 year follow up period. The implants with a length of 5.7 mm and 6mm were considered short. (Bicon Dental implants, USA). The experiment group was composed of $4.5{\times}6mm$, $5{\times}6mm$, $6{\times}5.7mm$ implants (total 18 implants were placed in 14 patients, 8 on maxilla, 10 on mandible). The control group was composed of $4.5{\times}8mm$, $5{\times}8mm$, $4.5{\times}11mm$, $5{\times}11mm$. All implants were selected only by implants placed on molar area. We evaluated marginal bone loss in radiographic images at baseline (implant loading) and 3, 6, 12 months after loading. Additionally, crown-to-implant ratio was evaluated, and marginal bone loss according to crown-to-implant ratio after functional loading was analyzed. Results: The short implant group had a mean marginal bone level of $-0.52{\pm}0.69mm$; the 8mm group, $-0.22{\pm}0.82mm$; and the II mm group, $-0.10{\pm}1.09mm$ after I year of functional loading. But significant differences were not detected between three groups at every follow-up period. Crown-to-implant ratio in short implant group was $1.55{\pm}0.23$; 8mm group was $1.15{\pm}0.18$; and 11mm group was $0.92{\pm}0.15$. Additionally, significant differences between three groups were founded. (P<.0001) The greatest marginal bone loss after 1 year follow-up was founded at crown-to-implant ratio 1~1.49 range in short implant. Conclusion: The marginal bone loss of short implants was comparable to that of long implants. So, the short implants can be a clinically acceptable option.