• Journal of Periodontal and Implant Science
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• v.45 no.1
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• pp.2-7
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• 2015

A fundamental problem in analyzing complex multilevel-structured periodontal data is the violation of independency among the observations, which is an assumption in traditional statistical models (e.g., analysis of variance and ordinary least squares regression). In many cases, aggregation (i.e., mean or sum scores) has been employed to overcome this problem. However, the aggregation approach still exhibits certain limitations, such as a loss of power and detailed information, no cross-level relationship analysis, and the potential for creating an ecological fallacy. In order to handle multilevel-structured data appropriately, mixed effects models have been introduced and employed in dental research using periodontal data. The use of mixed effects models might account for the potential bias due to the violation of the independency assumption as well as provide accurate estimates.

• Journal of the Korean Ceramic Society
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• v.55 no.1
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• pp.1-20
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• 2018

Semiconducting nanomaterials have attracted considerable interest in recent years due to their high sensitivity, selectivity, and fast response time. In addition, for portable applications, they have low power consumption, lightweight, simple in operation, a low maintenance cost. Furthermore, it is easy to manufacture microelectronic sensor structures with metallic oxide sensitive thin layers. The use of semiconducting metal oxides to develop highly sensitive chemiresistive sensing systems remains an important scientific challenge in the field of gas sensing. According to the sensing mechanisms of gas sensors, the overall sensor conductance is determined by surface reactions and the charge transfer processes between the adsorbed species and the sensing material. The primary goal of the present study is to explore the possibility of using semiconducting mixed metal oxide nanostructure as a potential sensor material for selective gases.

• 한국데이터정보과학회:학술대회논문집
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• 2001.10a
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• pp.25-33
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• 2001

This paper suggests a generalized logit model with mixed effects for analysing frequency data in multi-contingency table. In this model nominal response variable is assumed to be polychotomous. When some factors are fixed but condisered as ordinal and others are random, this paper shows how to use baseline-category logits to incoporate the mixed-effects of those factors into the model. A numerical algorithm was used to estimate model parameters by using marginal log-likelihood.

• Structural Engineering and Mechanics
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• v.13 no.2
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• pp.155-170
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• 2002

In this study, a new functional is obtained for folded plates with geometric (kinematic) and dynamic (natural) boundary conditions. This functional is the combination of two different functionals. Both functionals are obtained for thick plates which carry in-plane and lateral forces. A new mixed finite element is developed with $4{\times}13$ nodal parameters for folded plates (REC52). Forces and moments which are the necessary unknowns in engineering problems are obtained directly using the technique suggested here. The use of the global co-ordinate system causes time consuming operations and therefore the Lagrange multiplier method is used to relate the components of the parameters on the fold line. Numerical results are presented for folded plates and compared with experimental results.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.95.3-95
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• 2001

This paper investigates the simultaneous use of mixed H2/H_inf and mu-synthesis design methodology to design a robust controller for flexible link. We adopt four steps to design control system as follows: Step 1 : Generally, there are differences between the nominal and real model, so we consider the plant as a combination of parametric model uncertainty and unstructured uncertainty represents real structural uncertainties associated with the damping ratios of the flexible modes retained in the nominal model without payload. denotes the uncertainty which is due to the payload added at the tip. Step 2 : We adopt the mixed H2/H_inf theory to design a feedback controller K(s) by using the model uncertainty ...

• Journal of Ocean Engineering and Technology
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• v.38 no.5
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• pp.245-256
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• 2024

As the importance of carbon capture and storage (CCS) technology increases for greenhouse gas reduction, CO2 transportation technology is also becoming crucial. Efficiently handling boil-off gas (BOG) generated during voyages is particularly important. This paper proposes a process incorporating two-stage separation and mixed refrigerants to reliquefy CO2 BOG containing nitrogen efficiently. This process was optimized based on specific power consumption (SPC) criteria and compared with the conventional single-stage separation using an ammonia refrigerant. The two-stage separation allows the removal of non-condensable gases, such as nitrogen, before expansion, and the use of mixed refrigerants enables more efficient heat exchange than ammonia refrigerants, improving the reliquefaction rate. As a result, the proposed process reduced SPC by up to 8.8 % with a nitrogen content of 5 mol% and up to 74.7 % with a nitrogen content of 15 mol%. In addition, the proposed process achieved a reliquefaction rate of over 74.2 % across all nitrogen content ranges of 5-15 mol%.

• Journal of the Korean Geographical Society
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• v.38 no.5
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• pp.741-753
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• 2003

This study begins with paying attention to the agglomeration of 'Residential-Commercial Mixed Use Buildings(hereafter, R-C MU Buildings)', which tend to be a high grade and large sized building cluster at various neighboring areas in Seoul. The purpose of this study is to understand the relationship between emerging new housing type and residential area by analyzing the characteristics of residential neighborhood that is mainly created by R-C MU Buildings. For this purpose, the specialization and the regional characteristics(in connection with the hierarchy in urban spatial structure) of R-C MU Building's residential neighborhood were analyzed. In the end, the specific type of housing reveals the tendency to be differentiated in terms of income, education and occupation related with housing and residential area. And the residential characteristics also seem to be different according to the regions based on the central place hierarchical structure. It means that the social and class factors are important in choosing house, but the characteristics of the neighborhood area play an important role in the selection of resident area. Finally, the location of certain type of housing can influence the selecting process of residence and it can also determine the characteristics of the resident area in turn.

• Korean Journal of Construction Engineering and Management
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• v.12 no.1
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• pp.141-152
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• 2011

The market volume of urban regeneration projects has steadily increased, thereby mixed-use development also shows significant market growth. However, previous researches on urban regeneration mainly deduced suggestions and plans for institution improvement based on comparison between projects implemented the inside and outside of the country. Whereas, researches on project management closely related to project success were limited, particularly in performance management. Accordingly, this research aims at developing a program performance management framework for public clients so as to succeed mixed-use development projects. Through extensive literature review and expert interview, this research developed performance indices for diverse facilities, risk management framework and integrating method of program performance score. The proposed framework is able to consider total life cycle from basic planning to maintenance phase and to check real-time performance level. Moreover, risk management framework can periodically assess and control the level of inherent risks within performance indices. The results can contribute to improve existing performance management practices and be basis for a web-based system developed in future.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.1
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• pp.15-21
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• 2015

Recently, attempts of replacing some of natural aggregate with mix of low quality aggregate are carried out for stable supply of aggregate. However, low quality aggregate such as recycled aggregate produced during the disposal process of construction wastes and by-product aggregate produced by industrial activities has problem of failing to comply to KS Standards. Therefore, we have compared fundamental properties of concrete by using granite crushed aggregate, recycled aggregate, blast furnace and electric arc furnace slag aggregate for effective utilization of lacking aggregate resources. As the result, slump in case of mixed use of aggregate was increased 0~10% compared to single use. Therefore, it is judged to be economically advantageous as it can expect effects in unit quantity or reduction of SP agent. Compressive strength in case of mixed use of aggregate was increased 0~10% compared to single use as it filled internal crevice of concrete with continuous particle size distribution. Accordingly, if we utilize by satisfying standard particle scope through mix of aggregate with different cause of formation in proper ratio, it was possible to confirm utility of mixed aggregate with demonstration of effects of increases of fluidity and compressive strength of concrete.

• Economic and Environmental Geology
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• v.54 no.5
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• pp.505-513
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• 2021

Recently, housing prices in metropolitan areas is also increasing in the UK and Australia. Their governments are trying to solve this problem by the housing development in the quarry sites near cities. The cases reviewed in this study, Erith Hill Quarry (The Quarry), Plymstock Quarry, Lilydale Quarry (Kinley), and Bombo Quarry are the mixed-used development cases in the closed quarry sites through the urban planning system. In the UK, the local government uses the urban planning scheme such as the planning permit system, section 106. The local government permits the quarry site development on the condition that it provides necessary public facilities, such as schools and affordable housing for the local community. In Australia, local governments use up-zoning permission rights to convert land uses in quarries from industrial to mixed-use. Development plans have to include urban infrastructure and open space in addition to affordable housings. In the case of Australia, establishing a development plan in advance and filling the quarry pit with overburden through a phased development is expected to have the effect of reducing the project cost. Both countries think that developing brownfields, such as quarry sites, is a more sustainable and eco-friendly development from the perspective of future generations than developing new green fields. Such a perspective of the UK and Australia will be able to give policy implications for our slightly rigid urban development system.