• The Journal of Information Systems
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• v.31 no.2
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• pp.111-136
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• 2022

Purpose The purpose of this study is to examine the effect that insecurity and autonomy of platform work have an influence on work-life balance and psychological well-being in an era of platform economy based on two characteristics of online platform work and self-determination theory. Design/methodology/approach This study suggested the structural equation model integrating two antecedents, insecurity and autonomy, work-life balance, and psychological well-being and proposed five hypotheses driven from the research model. A total of 334 valid samples were collected from platform workers by employing questionnaire including 24 question items of four constructs. Findings Three hypotheses were supported and one hypothesis was not supported at the significance level of 0.05. Insecurity of platform work has a negative influence on work-life balance at the significance level of 0.01, whereas insecurity of platform work has no a significant influence on psychological well-being. Autonomy of platform work has a positive influence on both work-life balance and psychological well-being at the significance level of 0.01. Work-life balance has a positive impact on psychological well-being at the significance level of 0.001. Insecurity have an influence on psychological well-being indirectly through mediation of work-life balance. Implications for academicians and practitioners were suggested.

• Journal of Families and Better Life
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• v.32 no.2
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• pp.117-130
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• 2014

Since 1992, with the beginning of trade between Korea and China, their commercial relationship has become closer than before. As a result of better quality of life, the consumers of the two countries value well-being more the before. Thus, this paper examined the information search, awareness, purchasing motivation, and purchasing intention of well-being food of Korean and Chinese consumers, and identified the dominant factors influencing the purchasing intentions of well-being food. Firstly, the information searches of well-being food showed significant differences between the Korean and Chinese consumers. Secondly, the awareness of well-being food between the consumers of the two countries did not show significant differences. Thirdly, the results about the purchasing motivation of well-being food showed that the Chinese consumers had stronger purchasing motivation related to 'social responsibility' than that of Korean consumers, and the differences were significant. Fourthly, the results on the purchasing intentions of well-being food indicated that the Chinese consumers had greater intentions than Korean consumers. Fifthly, for the Korean consumers, the variables influencing the purchasing intentions of well-being food were the considerations of health care, purchasing motivation ('personal desire'), and the awareness of well-being food. For the Chinese consumers, the awareness of well-being food, gender (female), information search of well-being food, and education were formed the main variables.

• Nuclear Engineering and Technology
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• v.54 no.11
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• pp.4322-4328
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• 2022

The two-fluid model is widely used to describe two-phase flows in complex systems such as nuclear reactors. Although the two-phase flow was successfully simulated, the standard two-fluid model suffers from an ill-posed nature. There are several remedies for the ill-posedness of the one-dimensional (1D) two-fluid model; among those, artificial viscosity is the focus of this study. Some previous works added artificial diffusion terms to both mass and momentum equations to render the two-fluid model well-posed and demonstrated that this method provided a numerically converging model. However, they did not consider mass conservation, which is crucial for analyzing a closed reactor system. In fact, the total mass is not conserved in the previous models. This study improves the artificial viscosity model such that the 1D incompressible two-fluid model is well-posed, and the total mass is conserved. The water faucet and Kelvin-Helmholtz instability flows were simulated to test the effect of the proposed artificial viscosity model. The results indicate that the proposed artificial viscosity model effectively remedies the ill-posedness of the two-fluid model while maintaining a negligible total mass error.

• Journal of the Korean Operations Research and Management Science Society
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• v.31 no.1
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• pp.1-13
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• 2006

In this paper we consider a design problem of a cyclic queueing network with two stages, each with a local buffer of limited capacity. Based on the theory of reversibility and product-form solution, we derive the throughput function of the network as a key performance measure to maximize. Two cases are considered. In case each stage consists of a single server, an optimal allocation policy of a given buffer capacity and work load between stages as well as the optimal number of customers is identified by exploiting the properties of the throughput function. In case each stage consists of multiple servers, the optimal policy developed for the single server case doesn't hold any more and an algorithm is developed to allocate with a small number of computations a given number of servers, buffer capacity as well as total work load and the total number of customers. The differences of the optimal policies between two cases and the implications of the results are also discussed. The results can be applied to support the design of certain manufacturing and computer/communication systems.

• Proceedings of the KSR Conference
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• 2002.10a
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• pp.690-695
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• 2002

Two plate girders bridge has an advantage for execution of works and quality control because of its simplicity of super-structure caused by decreasing in amount of members and also is distinguished as aesthetic bridge type. Recently this has been adopted for structure of highway as well railway and introduced into domestic. In order to plan or design two plate girders bridge more rationably, it is necessary to comprehend its structural behavior as well as to consider the critical resign factors. Thus, in this study the formulation of optimum design for two plate girders bridge is proposed and the critical resign variables ani restraints are considered and founded by caring out optimum design. The objective function of optimization is formulated as a minimum cost design problem. And the thickness and length of I-shaped section are decided as resign variables. The design constraints are formulated based on Design Criteria for Railroad(Bridges). By comparing the optimum results with those of the conventional resign, the effectiveness of proposed optimum design formulation is investigated. From the results, the way to do optimum design of two plate girders bridge is suggested.

• Communications for Statistical Applications and Methods
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• v.30 no.2
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• pp.179-189
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• 2023

Hybrid sufficient dimension reduction (SDR) methods to a weighted mean of kernel matrices of two different SDR methods by Ye and Weiss (2003) require heavy computation and time consumption due to bootstrapping. To avoid this, Park et al. (2022) recently develop the so-called cross-distance selection (CDS) algorithm. In this paper, two variations of the original CDS algorithm are proposed depending on how well and equally the covk-SAVE is treated in the selection procedure. In one variation, which is called the larger CDS algorithm, the covk-SAVE is equally and fairly utilized with the other two candiates of SIR-SAVE and covk-DR. But, for the final selection, a random selection should be necessary. On the other hand, SIR-SAVE and covk-DR are utilized with completely ruling covk-SAVE out, which is called the smaller CDS algorithm. Numerical studies confirm that the original CDS algorithm is better than or compete quite well to the two proposed variations. A real data example is presented to compare and interpret the decisions by the three CDS algorithms in practice.

• The Pure and Applied Mathematics
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• v.10 no.3
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• pp.171-176
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• 2003

The purpose of this paper is to Show the relationships between three forms of the axiom of choice and well-ordering in an elementary topos.

• Korean Journal of Plant Taxonomy
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• v.41 no.3
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• pp.175-181
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• 2011

Traditionally, the Oleaceae has been divided into subfamilies Oleoideae and Jasminoideae. In the present paper, the taxonomical results so far made on the family were reviewed on the basis of palynology. The subfamilial classification is not well supported palynoligically, because both Myxopyrum of Jasminoideae and Comoranthus of Oleoideae having foveolate surface are well distinguished from the rest of the family having reticulate surface. The recent subfamily Nyctanthoideae (Takhtajan, 1977) including the monotypic Nyctanthus, was suggested to be included within the Jasminoideae although its closest relative on the palynological basis is different from that on the molecular basis. Tribal classification systems of the Jasminoideae are not well supported palynologically on the basis of surface character: presence or absence of bands on the mural ridge surface of the reticulum. On the basis of palynology, tribe Forsythiae including Abeliophyllum, Fontanesia, and Forsythia is monophyletic, and Fontanesia is well distinguished from the rest two. Korean species of Forsythia is divided into two: Forsythia koreana group and F. ovata-nakaii-saxatilis group. Recent discovery of F. saxatilis at a locality of F. ovata raised a question if the distinction between the two species on the basis of hairiness would be right. In the recent molecular studies, F. saxatilis var. lanceolata seems to be identified as F. saxatilis. Molecular studies showed that F. saxatilis (seemingly var. lanceolata or var. pilosa) is close to F. koreana. The fact in which the molecular result showed a close relationship between F. saxatilis varieties and F. koreana, is controversial to the result by floral and vegetative morphology. An intensive taxonomic study of these taxa would be needed.

• ETRI Journal
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• v.18 no.4
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• pp.315-338
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• 1997

We extend our previous theoretical analysis of electronic and optical properties of p-type quantum well structures based on the two heavy- and light-hole system to include all the three valence bands. These theories are then used to clarify the origin of the normal incidence absorption and photo current at photon wavelengths of 2 - 3 ${\mu}m$, which was observed in addition to the absorption around 8 ${\mu}m$ by a recent experimental investigation with heavily doped p-type GaAs/AlGaAs multi-quantum well (MQW) structures. In the theoretical analysis, the Hartree and exchange-correlation many-body interactions are taken into account within one-particle local density approximation, and it is shown that normal incidence absorption occurs in two wavelength regions over the transition energy range higher than barrier height for p-type GaAs/AlGaAs superlattices with well doping of $2{\times}10^{19}\;cm^{-3}$; one region has broad absorption peaks with coefficients of about 5000 $cm^{-1}$ around 8 ${\mu}m$, and the other has two rather sharp peaks at 2.7 ${\mu}m$ and 3.4 ${\mu}m$ with 1800 $cm^{-1}$ and 1300 $cm^{-1}$, respectively. The result indicates that the theory explains the experimental observation well, as the theoretical and experimental results are in close agreement in general absorption features.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.8
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• pp.468-474
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• 2009

Ground water source heat pump system is the oldest one of the ground source heat pump systems. Despite of this, little formal design information has been available until recently. The important design parameters for open system are the identification of optimum ground water flow, heat exchanger selection and well pump. In this study, the capacity of 50 RT system of two well type ground water heat pump system was used. As a result, static water level was -7 m and the level during the heating operation was -32 m, cooling operation was -40 m. The initial static water level recovered within 48 hrs. The temperature of ground water is $15.6^{\circ}C$ for heating season and $16.2^{\circ}C$ for cooling season and does not depend on the outdoor temperature. Operation efficiency of the system shows that, COP 3.1 for heating and COP 4.2 for cooling.