• Journal of Technologic Dentistry
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• v.46 no.1
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• pp.15-19
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• 2024

An ideal post material should have physical properties similar to those of dentin. Post materials with high elastic moduli may cause root fractures. This clinical report describes the treatment of a severely damaged tooth using a recently introduced material. Polyetherketoneketone (PEKK) is a semicrystalline high-performance thermoplastic polymer. PEKK is a promising material for custom post-and-core fabrication because of its elasticity close to that of dentin, good shock absorbance, machinability, and low cost. A laboratory scanner was used to digitize the conventional impression of a severely damaged maxillary right first molar. A custom PEKK post-and-core was designed and milled using computer-aided design and computer-aided manufacturing technology. Using the proposed technique, a custom PEKK post-and-core was fabricated accurately and human error was reduced. Restoration was luted with resin cement. Custom PEKK post-and-core restorations are a viable alternative for treating severely damaged teeth.

• The KIPS Transactions:PartD
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• v.10D no.7
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• pp.1127-1136
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• 2003

Estimation of software project cost, effort and duration in the early stage of software development cycle is a difficult and key problem in software engineering. Most of models estimate the development effort using the function point that is measured from the requirement specification. This paper presents optimal team size and duration prediction based on function point in order to provide information that can be used as a guide in selecting the most Practical and productive team size for a software development project. We introduce to productive metrics and cost for decision criteria of ideal team size and duration. The experimental is based on the analysis of 300 development and enhancement software project data. These data sets are divide in two subgroups. One is a development project; the other is a maintenance project. As a result of evaluation by productivity and cost measured criteria in two subgroups, we come to the conclusion that the most successful projects has small teams and minimum duration. Also, I proposed that predictive model for team sire and duration according to function point size based on experimental results. The presented models gives a criteria for necessary team site and duration according to the software size.

• Journal of the Korea Safety Management & Science
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• v.20 no.3
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• pp.27-36
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• 2018

The steel pipe manufacturing industry deals with facilities and materials. Especially thermal facilities are close to vapor cloud explosion (VCE) and may cause secondary damage to facilities because they deal with corrosive substances such as hydrofluoric acid, sulfuric acid and acid, fire, explosion, leakage etc. It is in danger. In this study, hazard identification method was conducted using HAZOP techniques and quantitative risk analysis was conducted using e-CA, a program that supports accident impact analysis. Equipment in the influence range of ERPG - 3 was determined to be a facility requiring replacement. It was decided that neutralization is necessary using slaked lime. Based on the cost of loss, We presented the proper replacement which is the timing of the dangerous facility. As a result, It was ideal to replace the facilities with 20 years of heat treatment facilities, one year of hydrofluoric acid storage tank, 20 years of sulfuric acid storage tank, and 5 years of hydrochloric acid storage tank.

• Journal of Power Electronics
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• v.17 no.2
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• pp.346-357
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• 2017

The Modular Multilevel Converter (MMC) is particularly attractive for medium and high power applications such as High-Voltage Direct Current (HVDC) systems. In order to reach a high voltage, the number of cascaded submodules (SMs) is generally very large. Thus, in the applications with hundreds or even thousands of SMs such as MMC-HVDCs, the sorting algorithm of the conventional voltage balancing strategy is extremely slow. This complicates the controller design and increases the hardware cost tremendously. This paper presents a Two-Way Merge Sort (TWMS) strategy based on the prediction of the capacitor voltages under ideal conditions. It also proposes an innovative Insertion Sort Correction for the TWMS (ISC-TWMS) to solve issues in practical engineering under non-ideal conditions. The proposed sorting methods are combined with the features of the MMC-HVDC control strategy, which significantly accelerates the sorting process and reduces the implementation efforts. In comparison with the commonly used quicksort algorithm, it saves at least two-thirds of the sorting execution time in one arm with 100 SMs, and saves more with a higher number of SMs. A 501-level MMC-HVDC simulation model in PSCAD/EMTDC has been built to verify the validity of the proposed strategies. The fast speed and high efficiency of the algorithms are demonstrated by experiments with a DSP controller (TMS320F28335).

• Smart Structures and Systems
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• v.22 no.5
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• pp.561-574
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• 2018

In this paper, for efficiently reducing the computational cost of the model updating during the optimization process of damage detection, the structural response is evaluated using properly trained surrogate model. Furthermore, in practice uncertainties in the FE model parameters and modelling errors are inevitable. Hence, an efficient approach based on Monte Carlo simulation is proposed to take into account the effect of uncertainties in developing a surrogate model. The probability of damage existence (PDE) is calculated based on the probability density function of the existence of undamaged and damaged states. The current work builds a framework for Probability Based Damage Detection (PBDD) of structures based on the best combination of metaheuristic optimization algorithm and surrogate models. To reach this goal, three popular metamodeling techniques including Cascade Feed Forward Neural Network (CFNN), Least Square Support Vector Machines (LS-SVMs) and Kriging are constructed, trained and tested in order to inspect features and faults of each algorithm. Furthermore, three wellknown optimization algorithms including Ideal Gas Molecular Movement (IGMM), Particle Swarm Optimization (PSO) and Bat Algorithm (BA) are utilized and the comparative results are presented accordingly. Furthermore, efficient schemes are implemented on these algorithms to improve their performance in handling problems with a large number of variables. By considering various indices for measuring the accuracy and computational time of PBDD process, the results indicate that combination of LS-SVM surrogate model by IGMM optimization algorithm have better performance in predicting the of damage compared with other methods.

• Korean Journal of Poultry Science
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• v.35 no.4
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• pp.327-333
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• 2009

In Korea chicken meat price is not determined in the auction markets, but it is artificially calculated using the live chicken price of one day before, transporting cost, converting rate of live chicken into carcass, and slaughtering cost. This calculated price is published through the mass media and used as the base for chicken meat transaction. By the way, since 85% of the Korean broiler industry is composed by the integrated system, the live chicken price is nothing to do with ex-factory price of chicken meat produced by the integrators. Under this pricing system, when we estimate the margin of the chicken meat through the marketing process, the margin of the integrator is fluctuated by the live chicken price of one day before, which is nothing to do with integrators; When the live chicken price is low, the margin of the integrators is low, but the margin of the selling agencies' is relatively high. On the contrast, when the live chicken price is high, the margin of the integrators is high, but the selling agencies' margin will be relatively low, because consumer's price could not be increased in parallel with increase of the live chicken price. Accordingly, the ex-factory price of chicken meat determined using the production cost of live chicken and slaughtering cost of the integrator by adding resonable margin of the integrator should be determined and published, so that it could be used for chicken meat transaction. In Japan the Zen-Noh Chicken Foods Corporation announce the ideal piece of chicken every morning, and all the transactions of the chicken meat will be determined based on this price. In Korea, it will be desirable to make bench marking from Japanese case, in other words the NH could announce the ideal price of chicken meat every morning, so that it would be the base price of chicken meat transaction. Even though the market share of the NH is less than 5%, its publicity should be accepted, since it is a subsidiary of the National Agricultural Cooperative Federation of Korea.

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.3
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• pp.257-262
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• 2009

The unified power flow controller(UPFC) is one of the most effective devices in the FACTS family. This paper concerns about a filtering technique for reducing the computer calculation to determine the optimal location of UPFC in a power system. The sensitivities of the power generation cost for UPFC control parameters are evaluated. This technique requires that only one optimal power flow is run to get UPFC sensitivities for all possible transmission lines. To find out a optimal locating of a single UPFC in power system, an ideal transformer model which consists of a complex turns ratio and a variable shunt admittance was used. In this model, the UPFC control variables do not depend on UPFC input and output currents and voltages. The sensitivity method was tested on a 5-bus system derived from the IEEE 14-bus system and IEEE 14-bus system to establish its effectiveness.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.1
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• pp.96-116
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• 2016

Sensing coverage is a fundamental issue for Wireless Sensor Networks (WSNs). Several coverage configuration protocols have been developed; most of them presume the availability of precise knowledge about each node location via GPS receivers. However, equipping each sensor node with a GPS is very expensive in terms of both energy and cost. On the other hand, several GPS-less localization algorithms that aim at obtaining nodes locations with a low cost have been proposed. Although their deep correlation, sensing coverage and localization have long been treated separately. In this paper, we analyze, design and evaluate a novel integrated framework providing both localization and coverage guarantees for WSNs. We integrate the well-known Coverage Configuration Protocol CCP with an improved version of the localization algorithm AT-Dist. We enhanced the original specification of AT-Dist in order to guarantee the necessary localization accuracy required by CCP. In our proposed framework, a few number of nodes are assumed to know their exact positions and dynamically vary their transmission ranges. The remaining sensors positions are derived, as accurately as possible, using this little initial location information. All nodes positions (exact and derived) are then used as an input for the coverage module. Extensive simulation results show that, even with a very low anchor density, our proposal reaches the same performance and efficiency as the ideal CCP based on complete and precise knowledge of sensors coordinates.

• Journal of The Korean Digital Architecture Interior Association
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• v.11 no.2
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• pp.71-81
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• 2011

This research explores about the construction process and provision of Japanese Wooden Houses. Even though Prefabricated Houses appeared during the 1960's and the Platform Construction System during the 1970's, there was still a high demand for Conventional Wooden House, with a high demand by households on their 30's. These features were found in the areas of Hokkaido, Kyushu, Tokyo, and Osaka. Tokyo and capital region accommodate large number of the head offices of companies that produce Platform Construction System houses, and thus supply the largest amount of Platform Construction System houses. In capital region, land prices are so high, that they build houses as 3-Floors or above, and also driven by high cost of house construction, house performances are excellent. The houses of Osaka and Kinki region demonstrate similar characteristics to those of capital region. Osaka is headquartered by a group of head offices of companies that produce prefabricated houses, and thus holds more amount of prefabricated house supply than other regions. This city also shows high cost of house construction no less than capital region, and thus offers outstanding performance of house. In Kyushu, whereas Japanese wooden house building systems are supplied the most, Platform Construction System houses are provided the least in the nation. As this region offers rich amount of forest resources owing to mild humid climate which is ideal for vegetations, the Japanese wooden building systems use the timbers from this region. Hokkaido, a cold region, requires houses that offer outstanding performance of heat insulation. Therefore, Hokkaido shows more supplies of Platform Construction System houses that offers outstanding heat insulation performance. They import the timbers that form the structure framework of Platform Construction System houses from North America.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.10
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• pp.752-757
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• 2018

This study presents the performance evaluation results of a 77-GHz waveguide slot array antenna that was fabricated by attaching a patterned printed circuit board(PCB) on a metal block. The 77-GHz waveguide was divided into a top plate and a bottom structure. The top plate was fabricated using a patterned PCB that can implement a fine slot at low cost. The top cover was then bonded to the bottom metal structure with a waveguide trough using anisotropic conductive film. For evaluating the antenna performance, a $1{\times}16$ slot array antenna was fabricated using our proposed method and the gain and pattern were measured and compared with the simulation results. Though the measurement results demonstrate a reduction in gain of around 2.3~3.5 dB compared to the simulation results assuming ideal bonding conditions, the pattern hardly changed and the slot antenna with a gain of approximately 17 dBi at 77 GHz can be easily manufactured at a low cost using the proposed method.