• Tuberculosis and Respiratory Diseases
• /
• v.86 no.2
• /
• pp.71-81
• /
• 2023

Chronic obstructive pulmonary disease (COPD) affects close to 400 million people worldwide. COPD is characterized by significant airflow limitation on spirometry. Most patients with COPD are diagnosed in their fifth or sixth decades of life. However, the disease begins much earlier. By the time airflow limitation is detected on spirometry, patients with COPD have lost close to 50% of their small airways. Thus, identification of patients with early COPD, defined as persons with preserved spirometry, who demonstrate pathologic or functional hallmarks of COPD, is essential for disease modification and ultimately disease elimination. This paper provides an up-to-date overview of the current case definition of early COPD, its importance, the novel technologies required for its detection in young adults and future directions in therapeutics for treatment.

• Journal of Communications and Networks
• /
• v.17 no.2
• /
• pp.203-209
• /
• 2015

Although mobile applications are an essential characteristic of wireless sensor networks, most existing media access control (MAC) protocols focus primarily on static networks. In these protocols, fixed periodic neighbor discovery and schedule updating are used to connect and synchronize neighbors to provide successful data transmission; however, they cannot adapt to mobile speed variation and degrade the network performance dramatically. In this paper, we propose a mobile-supporting mechanism for MAC protocols, in which the decision to update the neighbors of a mobile node is made adaptively according to the mobile speed. Analysis and simulation results demonstrate that the mechanism efficiently avoids the disconnection of amobile node from its neighbors and achieves a better performance as compared with fixed periodic neighbor discovery.

• Journal of Fisheries and Marine Sciences Education
• /
• v.24 no.3
• /
• pp.459-467
• /
• 2012

Marine aquariums are excellent venues for accomplishing the purpose of marine education, and school field trips conducted at non-formal settings continue to be an important part of K-12 education. The purpose of this study is to provide quantitative data regarding the extent and quality of marine aquarium field trips conducted by elementary school teachers in Seoul. A web survey designed to explore elementary school teachers' experiences and perspectives on aquarium field trips identified several concerns regarding Korean marine aquarium education. Discussions for both Korean aquaria's educational roles and Korean elementary schools' successful field trips to aquaria are presented with the goal of improving the quality of Korean marine aquarium education.

• Animal Systematics, Evolution and Diversity
• /
• v.30 no.1
• /
• pp.39-43
• /
• 2014

In this brief report, alternative time-varying diversification rate models were fitted onto the phylogeny of global amphibians by considering one-constant-rate (OCR), one-continuous-shift (OCS) and multiple-discrete- shifts (MDS) situations. The OCS diversification model was rejected by ${\gamma}$ statistic (${\gamma}=-5.556$, p<0.001), implying the existence of shifting diversification rates for global amphibian phylogeny. Through model selection, MDS diversification model outperformed OCS and OCR models using "laser" package under R environment. Moreover, MDS models, implemented using another R package "MEDUSA", indicated that there were sixteen shifts over the internal nodes for amphibian phylogeny. Conclusively, both OCS and MDS models are recommended to compare so as to better quantify rate-shifting trends of species diversification. MDS diversification models should be preferential for large phylogenies using "MEDUSA" package in which any arbitrary numbers of shifts are allowed to model.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2006.11a
• /
• pp.74-79
• /
• 2006

General formula are presented for the maximum power available from the tidal head in a closed basin and from the tidal currents in a channel connecting two large bodies of water. In the latter case, the available energy cannot be estimated from the kinetic energy flux in the undisturbed state, but can be obtained from knowledge of the tidal head between the ends of the channel and the maximum volume flux in the undisturbed state. The results are supported by detailed calculations for Johnstone Strait, British Columbia, using a two-dimensional finite element model. The model also allows an extension to the case of multiple channels. More work is needed to allow for partial tidal fences which do not occupy the whole cross-section of a channel.

• Korean Journal of English Language and Linguistics
• /
• v.3 no.3
• /
• pp.309-339
• /
• 2003

This paper provides an overview of second language (L2) socialization research, some examples of recent studies addressing this topic, and finally a theoretical reconceptualization of L2 socialization. The three studies to be presented include secondary schools in an English-as-a-foreign-language context in Central Europe, mainstream classes in an English-as-a second-language school in Western Canada, and programs for English language and nursing skills for immigrant Canadians. This empirical, qualitative research does not support a linear, deterministic view of L2 socialization; such a view assumes, erroneously, that students or other novices are fully willing and able to adopt stable, monolingual, local target L2 norms and that members of the target culture are both competent and receptive to the newcomers. Some consequences and implications of these findings are discussed.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 1993.06a
• /
• pp.1137-1140
• /
• 1993

A dynamic-structure system is one that has the flexibility to change the system configuration automatically so as to operate in an optimal manner. A conceptural model for a dynamic-structure system is presented in this paper. In this model, the interchangeable components of the overall system are grouped together. Their activity levels are evaluated by an intelligent preprocessor that is associated with the group. A knowledge-based task distribution system evaluates the activity levels and makes decisions as to how the components operating below capacity should be shared with workcells that have similar components that are overloaded. Associated decision making can be effected through fuzzy logic and particularly the compositional rule of inference. A simulation example is given to illustrate the application of dynamic structuring.

• Bulletin of the Korean Mathematical Society
• /
• v.60 no.4
• /
• pp.1035-1059
• /
• 2023

Let p be an odd prime. Let E be an elliptic curve defined over a quadratic imaginary field, where p splits completely. Suppose E has supersingular reduction at primes above p. Under appropriate hypotheses, we extend the results of [17] to ℤ²_p-extensions. We define and study the fine double-signed residual Selmer groups in these settings. We prove that for two residually isomorphic elliptic curves, the vanishing of the signed 𝜇-invariants of one elliptic curve implies the vanishing of the signed 𝜇-invariants of the other. Finally, we show that the Pontryagin dual of the Selmer group and the double-signed Selmer groups have no non-trivial pseudo-null submodules for these extensions.

• Journal of information and communication convergence engineering
• /
• v.15 no.1
• /
• pp.21-27
• /
• 2017

In this research, we study the outage probability for distributed space-time coding-based cooperative (DSTC) systems with amplify-and-forward relaying over Rayleigh fading channels with a high temporal correlation where the direct link between the source and the destination is available. In particular, we derive the upper and lower bounds of the outage probability as well as their corresponding asymptotic expressions. In addition, using only the average channel powers for the source-to-relay and relay-to-destination links, we propose an efficient power allocation scheme between the source and the relay to minimize the asymptotic upper bound of the outage probability. Through a numerical investigation, we verify the analytical expressions as well as the effectiveness of the proposed efficient power allocation. The numerical results show that the lower and upper bounds tightly correspond to the exact outage probability, and the proposed efficient power allocation scheme provides an outage probability similar to that of the optimal power allocation scheme that minimizes the exact outage probability.

• Proceedings of the Korean Environmental Sciences Society Conference
• /
• 2003.11a
• /
• pp.139-144
• /
• 2003

1, 4-dioxane is a recalcitrant pollutant found in contaminated ground waters and industrial effluents. Conventional water treatment techniques are limited to treat this compound effectively. In this study, $O_3$／$H_2O_2$ oxidation process was used to eliminate 1, 4-dioxane in water and to enhance the biodegradability. Several factors affecting biodegradability enhancement were investigated. The relationship between initial oxidation rate of 1 A-dioxane and BOD enhancement rate has been determined, a kinetic model has been proposed. $H_2O_2$ concentration and pH had a proportional relation with biodegradability of 1, 4-dioxane, but in case of ozone, there was no relationship with biodegradability. 1, 4-Dioxane removal efficiencies had good agreement with the biodegradability.