• Macromolecular Research
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• v.17 no.12
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• pp.1003-1009
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• 2009

Copolymers of N-vinylpyrrolidone (NVP) comonomer with styrene (St), hydroxypropyl methacrylate (HPMA) and carboxyphenyl maleimide (CPMI) were synthesized by free radical polymerization using 2,2'-azobisisobutyronitrile (AIBN) initiator in 1,4-dioxane solvent. The copolymers formed were characterized by FTIR, $^1H$ NMR and $^{13}C$ NMR techniques and their thermal properties were studied by DSC and TGA. Copolymer composition was determined by $^1H$ NMR and/or by elemental analysis and monomer reactivity ratios (MRR) were estimated by the linear methods of Kelen-Tudos (K-T) and extended Kelen-Tudos (EK-T) and the non-linear approach. Copolymers of St and HPMA with NVP formed blocks of one of the monomer units, whereas alternating copolymers were obtained in CPMI-NVP, depending upon the side chain substitution. The MRR values are discussed in terms of monomer structural properties such as electronegativity and electron delocalization. The sequence distribution of monomers in the copolymers was studied by statistical method based on the average reactivity ratios obtained by EK-T method.

• Restorative Dentistry and Endodontics
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• v.46 no.1
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• pp.13.1-13.9
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• 2021

Objectives: This study aimed to evaluate and compare the efficacy of the S1 reciprocating system and the D-Race retreatment rotary system for filling material removal and the apical extrusion of debris. Materials and Methods: Sixty-four freshly extracted maxillary canines were shaped with size 10 and size 15 K-files, instrumented using ProTaper Gold under irrigation with 2.5% sodium hypochlorite (NaOCl), obturated according to the principle of thermo-mechanical condensation with gutta-percha and zinc oxide eugenol sealer, and allowed to set for 3 weeks at 37℃. Subsequently, the teeth were divided into a control group (n = 4), the D-Race rotary instrument group (n = 30), and the S1 reciprocating instrument group (n = 30). After classical retreatment, the canals were subjected to a complementary approach with the XP-Endo Shaper. Desocclusol was used as a solvent, and irrigation with 2.5% NaOCl was performed. Each group was divided into subgroups according to the timing of radiographic readings. The images were imported into a software program to measure the remaining filling material, the apical extrusion, and the root canal space. The data were statistically analyzed using the Z-test and JASP graphics software. Results: No significant differences were found between the D-Race and S1 groups for primary retreatment; however, using a complementary cleaning method increased the removal of remnant filling (p < 0.05). Conclusions: Classical removal of canal filling material may not be sufficient for root canal disinfection, although a complementary finishing approach improved the results. Nevertheless, all systems left some debris and caused apical extrusion.

• Journal of the Korean Mathematical Society
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• v.44 no.5
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• pp.1051-1063
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• 2007

The aim of this note is to advertise a method which turns out to be powerful enough to be used successfully in problems which are apparently unrelated. It is based on a modification of a construction that we first introduced in [2].

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.420-424
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• 1993

New conditions for the exponential stability for both linear nonautnomous finite and a class of infinite dimensional systems described by parabolic partial differential equations (PDE's) are derived. The results for the parabolic systems are derived via semigroup approach.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.19 no.38
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• pp.207-215
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• 1996

Concurrent Engineering is a concept to aim at product development lead-time in order to satisfy customer's changing tastes in n timely manner. This approach is concurrently integrating all participants and aspects of product design, development and manufacture. In this paper the concepts, framework, and success factor-teamwork- of concurrent engineering is presented.

• THE INDUSTRY AND TECHNOLOGY OF GAS
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• v.2 no.1
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• pp.101-110
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• 1998

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.7
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• pp.2455-2475
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• 2021

Patient Navigation Program (PNP) is considered as an important implementation of health care systems that can assist in patient's treatment. Due to the feasibility of PNP implementation, a systematic reuse is needed for a wide adoption of PNP computerized system. SPL is one of the promising systematic reuse approaches for creating a reusable architecture to enabled reuse in several similar applications of PNP systems which has its own variations with other applications. However, stakeholder decision making which result from the imprecise, uncertain, and subjective nature of architecture selection based on quality attributes (QA) further hinders the development of the product line architecture. Therefore, this study aims to propose a quality-driven approach using Multi-Criteria Decision Analysis (MCDA) techniques for Software Product Line Architecture (SPLA) to have an objective selection based on the QA of stakeholders in the domain of PNP. There are two steps proposed to this approach. First, a clear representation of quality is proposed by extending feature model (FM) with QA feature to determine the QA in the early phase of architecture selection. Second, MCDA techniques were applied for architecture selection based on objective preference for certain QA in the domain of PNP. The result of the proposed approach is the implementation of the PNP system with SPLA that had been selected using MCDA techniques. Evaluation for the approach is done by checking the approach's applicability in a case study and stakeholder validation. Evaluation on ease of use and usefulness of the approach with selected stakeholders have shown positive responses. The evaluation results proved that the proposed approach assisted in the implementation of PNP systems.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2001.11a
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• pp.63-63
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• 2001

As a new approach to substitute for a hard alloy of stellite 6B containing Co which is radioactive in nuclear system, a hard-phase coating of CrN will be applicable to protect 12Cr steel from erosion at leading edge on steam turbine blade. The CrN coating was prepared by arc ion plating on 12 Cr steel and was undertaken in liquid impact test at the velocity of 35Om/sec, which simulate the environment in the last stage of blade. The erosion resistance of coating was evaluated by optical observation on damaged surface. The threshold number of impact was closely related with surface hardness. And thus, it was confirmed that surface hardening improves the life time of steam turbine blade.

• Journal of applied mathematics & informatics
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• v.23 no.1_2
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• pp.215-228
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• 2007

By using the variational calculus of fractional order, one derives a Hamilton-Jacobi equation and a Lagrangian variational approach to the optimal control of one-dimensional fractional dynamics with fractional cost function. It is shown that these two methods are equivalent, as a result of the Lagrange's characteristics method (a new approach) for solving non linear fractional partial differential equations. The key of this results is the fractional Taylor's series $f(x+h)=E_{\alpha}(h^{\alpha}D^{\alpha})f(x)$ where $E_{\alpha}(.)$ is the Mittag-Leffler function.

• Journal of the military operations research society of Korea
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• v.27 no.1
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• pp.73-88
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• 2001

Designing high quality products and processes at a low cost is central technological and economic challenge to the engineer. The combination of engineering concepts and statistical implementations offered by Taguchi\`s off-line design technique has proven t be invaluable. By examining some deficiencies in designs from the Taguchi\`s highly fractional, orthogonal main effect plan based on orthogonal arrays, alternative method is proposed. The maximum resolution or the minimum aberration criterion is commonly used for selecting 2$^{n-m}$ fractional designs. We present new high resolution (low aberration) linear graphs to simplify the complexity of selecting designs with desirable statistical properties. The new linear graphs approach shows a substantial improvement over Taguchi\`s linear graphs and other related graphical methods for planning experiment. The new set of linear graphs will allow the experimenter to maintain the simple approach suggested by Taguchi while obtaining the best statistical properties of the resulting design such as minimum aberration as a by-product without dependency on complicated computational algorithm or additional statistical training.g.