• ETRI Journal
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• v.37 no.2
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• pp.380-386
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• 2015

Guaranteeing quality of service over a multihop wireless network is difficult because end-to-end (ETE) delay is accumulated at each hop in a multihop flow. Recently, research has been conducted on network coding (NC) schemes as an alternative mechanism to significantly increase the utilization of valuable resources in multihop wireless networks. This paper proposes a new section-based joint NC and scheduling scheme that can reduce ETE delay and enhance resource efficiency in a multihop wireless network. Next, this paper derives the average ETE delay of the proposed scheme and simulates a TDMA network where the proposed scheme is deployed. Finally, this paper compares the performance of the proposed scheme with that of the conventional sequential scheduling scheme. From the performance analysis and simulation results, the proposed scheme gives more delay-and energy-efficient slot assignments even if the NC operation is applied, resulting in a use of fewer network resources and a reduction in ETE delay.

• Journal of KIISE
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• v.42 no.10
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• pp.1268-1279
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• 2015

In order to manage a large number of devices connected to the Internet of Things (IoT), the Internet Engineering Task Force (IETF) proposed the IPv6 Routing Protocol for Low Power and Lossy Networks (RPL). The route of the RPL network is generated through the use of an Objective Function (OF) that is suitable for the service that is required for the IoT network. Since the route of the RPL network is conventionally simply chosen only by considering the link quality between the nodes, it is sensible to seek an OF that can also provide better Quality of Service (QoS). In previous studies, the end-to-end delay might possibly be sub-optimal because they only deal with problems related to the reduction of energy consumption and not to the link quality on the path to the sink node. In this study, we propose a scheme that reduces the end-to-end delay but also gives full consideration to both the quality on the entire route to the destination and to the expected lifetime of nodes with bottlenecks from heaped traffic. Weighting factors for the proposed scheme are chosen by experiments and the proposed scheme can reduce the end-to-end delay and the energy consumption of previous studies by 20.8% and 10.5%, respectively.

• Korean Journal of Construction Engineering and Management
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• v.16 no.3
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• pp.123-131
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• 2015

There are a number of policies that have been established to reduce greenhouse gases emissions and reduce energy consumption. These polices, however, only reflect the building energy consumption saving rate without considering building energy consumption characteristic. If building that already use less energy apply the same saving rate to reduce energy consumption, it is less effective. Therefore, this study classified building energy consumption characteristics and investigated approaches to adopt individual reduction rates according to energy consumption. Analysis results showed that there are differences in energy consumption depending on building use, and therefore, we classified buildings by use. We also proposed a formula to set a reduction goal for rate of energy consumption according to energy consumption. We verified our approach in a top-end neighborhood facility in Seoul. The energy consumption savings goal of this study can be applied individually, but determining whether a building can reduce energy consumption towards a saving goal requires a closer look at each building.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.6
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• pp.908-914
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• 2008

The world is facing a serious energy problem which destroying the environment. In addition, fossil fuel such as oil and coal that caused global warming and the environmental problems due to acid rain had been gradually exhausted. To solve this problem that has crisis of energy, it is necessary time and effort for research and development of renewable energy in the future. As alternative energy, small hydropower generation which has output of less or equal to 100kW is attracting considerable attention. This is because of its small, simple, renewable, and large amount of energy resources. By using a small hydropower generator of which main concept is based on using the different water pressure levels in pipe lines, energy which was initially wasted by use reducing of a valve at the end of the pipeline, is collected by turbine in the small hydropower generator. In this study, we investigated the influence of the number of runner vanes on the characteristics of tubular-type hydroturbine.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.119-120
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• 2022

As the seriousness of the climate crisis is emphasized, movements to solve it are becoming active. In Korea, efforts to reduce environmental impacts across all industries are being strengthened through the Framework Act on Low Carbon Green Growth. The construction industry predicts the environmental impact of buildings during the entire life cycle, but in the construction process, there is a difference in energy usage depending on the amount of input, and it is difficult to predict the environmental impact if data cannot be collected. Therefore, this study evaluated the environmental impact of energy usage in the apartment construction process as part of the study on predicting and reducing the environmental impact of the construction process of the construction site. To this end, the environmental effects of buildings were set as global warming, resource consumption, and ozone layer effects, and the environmental effects of the actual energy use in the case were evaluated. In addition, based on the evaluation results, the characteristics of the input energy usage were compared and analyzed.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.5
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• pp.419-428
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• 2015

Multipath routing technique is recognized as one of the effective approaches to improve the reliability of data forwarding. However, the traditional multipath routing focuses only on how many paths are needed to ensure a desired reliability. For this purpose, the protocols construct additional paths and thus cause significant energy consumption. These problems have motivated the study for the energy-efficient and reliable data forwarding. Thus, this paper proposes an energy-efficient cooperative multipath routing protocol with a small number of paths based on an inter path communication. The inter path communication (namely, cooperative multipath routing) in the proposed protocol helps to reinforce the multipath reliability and reduce the use of network resources. In addition, the proposed protocol provides a reliable end-to-end transmission time by using a transmission recovery method based on the local decision for the path or transmission failures.

• Steel and Composite Structures
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• v.25 no.3
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• pp.271-286
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• 2017

The use of Hollow Structural Sections (HSS) provides an alternative for steel buildings in seismic zones, with the advantage over WF columns that the HSS columns have similar resistance along both axes and enhanced performance under flexure, compression and torsion with respect to other columns sections. The HSS columns have shown satisfactory performance under seismic loads, such as observed in buildings with steel moment frames in the Honshu earthquake (2011). The purpose of this research is to propose a new moment connection, EP-HSS ("End-plate to Hollow Structural Section"), using a wide flange beam and HSS column where the end plate falls outside the range of prequalification established in the ANSI/AISC 358-10 Specification, as an alternative to the traditional configuration of steel moment frames established in current codes. The connection was researched through analytical, numerical (FEM), and experimental studies. The results showed that the EP-HSS allowed the development of inelastic action on the beam only, avoiding stress concentrations in the column and developing significant energy dissipation. The experiments followed the qualification protocols established in the ANSI/AISC 341-10 Specification satisfying the required performance for highly ductile connections in seismic zones, thereby ensuring satisfactory performance under seismic actions without brittle failure mechanisms.

• Clinical and Experimental Pediatrics
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• v.65 no.5
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• pp.254-261
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• 2022

Background: The use of systemic steroids for 6+ weeks in children is associated with decreased bone mineral content (BMC) and density (BMD). However, the effects of a shorter duration of use on BMD are unknown. Purpose: To determine the effect of the use of systemic steroids for 2-6 weeks on BMD and BMC in pediatric patients. Methods: Twenty-five pediatric patients (21 with tuberculosis, 2 with systemic juvenile idiopathic arthritis, 1 with inflammatory bowel disease, 1 with autoimmune hemolytic anemia) who received systemic steroids for 2-6 weeks and 25 age- and sex-matched controls were enrolled. BMC, BMD, and z scores of the whole body (WB), lumbar spine (LS), nondominant distal radius (DR), and total body less the head (TBLH) were determined by dual-energy x-ray absorptiometry at baseline, the end of steroid therapy or 6 weeks (whichever was earlier; first follow-up), and at the end of 3 months from baseline (second follow-up) in patients and at baseline in controls. The values were adjusted for confounding variables. Continuous and categorical variables were compared using Student t test and the chi-square test or Fisher exact test, respectively. Pairwise comparisons employed Bonferroni correction. Results: Statistically significant decreases in BMC, BMD, and all z scores were observed. BMC declined by 5.37%, 2.08%, 1.82%, and 2.27%, and 11.42%, 3.75%, 3.34%, and 4.17% for WB, LS, DR, and TBLH, respectively, at the first and second follow-ups, respectively. Similarly, BMD declined by 2.01%, 2.31%, 2.18%, and 1.70% and 4.59%, 3.76%, 3.14%, and 3.50% for the WB, LS, DR, and TBLH, respectively, at the first and second follow-ups, respectively. A significant negative correlation was found among bone densitometric parameters, duration, and cumulative dose. Conclusion: The use of systemic steroids for 2-6 weeks in pediatric patients decreased the BMD and BMC of trabecular and cortical bones, an effect that persisted after discontinuation.

• The Journal of the Korea Contents Association
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• v.16 no.3
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• pp.667-675
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• 2016

The aim of this study is to predict use behavior for social welfare service of the elderly mentally ill through means-end chain theory. Means-end chain theory explains cognitive structure related to the consumer's preference to various products and services. Although the elderly mentally ill begin to emerge as new client population, social welfare services for them do not seem to be enough in the community. Based on this awareness, this study tried to analyse service use behavior of the elderly mentally ill through means-end chain theory to develop new social welfare services. The data were collected from 15 elderly mentally ill and found 5 attributes, 10 consequences, and 11 values. Hierarchical Value Map was composed of 'disease management, rehabilitation preparation, hobby leisure ${\rightarrow}$ health maintenance, energy of life ${\rightarrow}$ social reintegration, life satisfaction, harmonious family life'. To activate the social service for the elderly mentally ill, it should be developed various programs such as disease management, rehabilitation preparation, hobby leisure for the elderly mentally ill. The ultimate value of these programs will be improve life satisfaction and integrated into society.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.5
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• pp.507-511
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• 2019

The use of regenerative energy in AC drive systems has been an issue since the system became an industry standard in the 1990s. According to the quantity of the regenerative energy, the braking resistor in the case of low capacity was common. However the use of such low amount of energy is actively discussed, and the method of mounting the regenerative converter is becoming popular. In this paper, an isolated regenerative converter for reducing the circulating current which is mentioned as the biggest disadvantage of the conventional power regenerative converter system is proposed. In order to save energy, employing a power regenerative converter system for utilizing regenerative energy in an AC drive system is common. However due to the structure of the system, a circulating current is generated, which inevitably causes a decrease in efficiency. In this paper, an isolated regenerative power converter system is proposed to solve the circulating current and computer simulation to verify the possibility. The simulation results show that 20% of the circulating current of the conventional system does not appear in the proposed system, and the validity of the proposed system is confirmed.