• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.16 no.5
• /
• pp.1540-1560
• /
• 2022

Latest technological innovation in the development of compact lower power radios has led to the explosion of Internet of Things. With Wi-Fi, Zigbee and other physical layer protocols offering short coverage area there was a need for a RF protocol that had a larger coverage area with low power consumption. LoRa offers Long Range with lower power consumption. LoRa offers point to point and point to multipoint connections. with Single hop communication in place the need for routing protocols are eliminated. LoRa Wide Area Network stack can accommodate thousands of nodes under a single LoRa gateway with a single hop communication between the end nodes and LoRaWAN gateway. This paper takes an experimental approach to analyze the basic physical layer parameters of LoRa and the practical coverage offered by a LoRaWAN under highly dense urban conditions with variable topography. The insights gained from the practical deployment of the LoRaWAN network, and the subsequent performance analysis is used to design a novel public utility monitoring platform. The second half of the papers is designing a robust platform to integrate both existing wired sensor water meters, current and future generation wireless water meters. The Common Automated Metering Platform is designed to integrate both wired sensors and wireless (LoRaWAN and Wi-Fi) supported water meters. This integrated platform reduces the number of nodes under each LoRaWAN gateway and thus improves the scalability of the network. This architecture is currently designed to accommodate one utility application but can be modified to integrate multi-utility applications.

• 제어로봇시스템학회:학술대회논문집
• /
• 2004.08a
• /
• pp.377-382
• /
• 2004

This paper presents a novel optimization method for the air- and gas-supplying network comprised of several air compression systems and air and gas streams in an industrial chemical plant. The optimization is based on the hybrid model developed by Han and $Han^1$ for predicting the power consumption of a compression system. A constrained optimization problem was formulated to minimize the total electric power consumption of all the compression systems in the air- and gas-supplying network under various operating constraints and was solved using a successive quadratic optimization algorithm. The optimization approach was applied to an industrial terephthalic acid manufacturing plant to achieve about 10% reduction in the total electric power consumption under varying ambient conditions.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• v.18 no.4
• /
• pp.283-294
• /
• 2014

In this paper we study consumption-labor supply decision of an agent who prepares for retirement at a known time in the future. The agent is assumed to have a preference which is represented by the von Neumann-Morgenstern utility function in which the felicity function has constant relative risk aversion over the composite of consumption and leisure. The composite is obtained by the Cobb-Douglas function. A general problem has been studied by Bodie et al. (2004). We contribute to the literature by deriving the Slutsky equations and conducting comparative statics. In particular, we show that wealth effect can exhibit an interesting property depending upon the time until retirement, as the interest rate increases.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• v.19 no.4
• /
• pp.429-441
• /
• 2015

We study optimal consumption/investment and life insurance purchase rules for a wage earner with mortality risk under regime-switching financial market conditions, in a continuous time-horizon. We apply the Markov chain approximation method and suggest an efficient algorithm using parallel computing to solve the simultaneous Hamilton-Jaccobi-Bellman equations arising from the optimization problem. We provide numerical results under the utility functions of the constant relative risk aversion type, with which we illustrate the effects of regime switching on the optimal policies by comparing them with those in the absence of regime switching.

• Journal of the Korean Home Economics Association
• /
• v.45 no.2
• /
• pp.77-90
• /
• 2007

Using 2004 Household Income & Expenditure Survey, this study investigated difference in consumption pattern among the households with the different number of children, and estimated the monetary cost of rearing children. The findings were as following. First, the major consumption categories for raising children included the expenditures for education, food materials, utility, health, and communication. Second, the potential consumption needs for clothing & foot ware and culture & entertainment were not fully satisfied for the households with children compared to the households without children. Third, in the households with one child, the level of consumption was about two thirds of that in the households without children. It was slightly above half in the households with two children. Lower consumption level of the households with children was mainly due to the burden of the educational expenditure. Forth, the average monthly cost of raising children was estimated by 680 thousands Won for one child, and 104 thousand Won for two children. Lastly, the implications for the fertility policy and the methods for the estimation of the child cost were suggested based on the results.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.15 no.9
• /
• pp.3151-3168
• /
• 2021

Internet of Things (IoT) connects several objects with embedded sensors and they are capable of exchanging information between devices to create a smart environment. IoT smart devices have limited resources, such as batteries, computing power, and bandwidth, but comprehensive sensing causes severe energy restrictions, lowering data quality. The main objective of the proposal is to build a hybrid protocol which provides high data quality and reduced energy consumption in IoT sensor network. The hybrid protocol gives a flexible and complete solution for sensor selection problem. It selects a subset of active sensor nodes in the network which will increase the data quality and optimize the energy consumption. Since the unused sensor nodes switch off during the sensing phase, the energy consumption is greatly reduced. The hybrid protocol uses Dijkstra's algorithm for determining the shortest path for sensing data and Ant colony inspired variable path selection algorithm for selecting active nodes in the network. The missing data due to inactive sensor nodes is reconstructed using enhanced belief propagation algorithm. The proposed hybrid method is evaluated using real sensor data and the demonstrated results show significant improvement in energy consumption, data utility and data reconstruction rate compared to other existing methods.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.12 no.11
• /
• pp.5357-5381
• /
• 2018

Cloud computing offers a wide range of on-demand resources over the internet. Utility-based resource allocation in cloud data centers significantly increases the number of cloud users. Heavy usage of cloud data center encounters many problems such as sacrificing system performance, increasing operational cost and high-energy consumption. Therefore, the result of the system damages the environment extremely due to heavy carbon (CO2) emission. However, dynamic allocation of energy-efficient resources in cloud data centers overcomes these problems. In this paper, we have proposed Energy and Service Level Agreement (SLA) Aware Resource Allocation Heuristic Algorithms. These algorithms are essential for reducing power consumption and SLA violation without diminishing the performance and Quality-of-Service (QoS) in cloud data centers. Our proposed model is organized as follows: a) SLA violation detection model is used to prevent Virtual Machines (VMs) from overloaded and underloaded host usage; b) for reducing power consumption of VMs, we have introduced Enhanced minPower and maxUtilization (EMPMU) VM migration policy; and c) efficient utilization of cloud resources and VM placement are achieved using SLA-aware Modified Best Fit Decreasing (MBFD) algorithm. We have validated our test results using CloudSim toolkit 3.0.3. Finally, experimental results have shown better resource utilization, reduced energy consumption and SLA violation in heterogeneous dynamic cloud environment.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39C no.4
• /
• pp.400-406
• /
• 2014

In this paper, we propose an approach to minimizing total power consumption by deploying multiple clean-up robots simultaneously in a given area. For this, we propose to use the cooperative game theoretic approaches (i.e., Nash bargaining solution (NBS)) such that the robots can optimally and fairly negotiate the area division based on available resources and characteristics of the area, thereby leading to the minimum total power consumption. We define a utility function that includes power consumptions for characteristics of areas and the robots can agree on a utility pair based on the NBS. Simulation results show that the proposed approach can reduce the total average power consumption by 15-30% compared to a random area division approach.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.21 no.1
• /
• pp.104-118
• /
• 1997

Consumers experience various cognitive and emotional contents of clothing through postpurchase process. These experiences may affect consumer satisfaction as well as brand attitude toward clothing products. The purpose of this study was to examine the effects of consumption experiences on the brand attitude toward clothing products. The research questions for accomplishing the purpose of this study were to investigate 1) the dimension of consumption experiences, 2) relationships among consumption experience, satisfaction and brand attitude toward clothing. The sample of this study was consisted of 431 females. The survey method, and factor analysis and regression were utilized for this study. The results were as follows; First, it was found out the consumption was composed of two dimensions such as cognitive and emotional experiences. According to the result of factor analysis, the cognitive experiences through consumption process were composed of 6 factors, that is, the suitability, fitness, utility/economy, sewing, deformation, and management. And emotional experiences were composed of 5 factors, that is, unpleasure, activeycomfort, inter-oriented pleasure, extra- oriented pleasure, tension. Also emotional experiences could be composed of two dimensions, that is, positive and negative emotion. The positive emotions were included pleasure and active/comfort. The negative emotions were included unpleasure and tension. Second, the result of path analysis showed that consumption experiences were related to satisfaction and brand attitude. A satisfaction influenced on brand attitude more strongly than others. And sewing, activejcomfort, extra-oriented pleasure out of cognitive and emotional experience factors affected to brand attitude directly. Satisfaction was also influenced by cognitive and emotional factors, and was the important mediator in forming brand attitude toward clothing through consumption experience. Above results imply that consumer experience multidimensional cognitive and emotional aspects of clothing through consumption process. The cognitive and emotional aspects consisting of consumption experiences, satisfaction, and brand attitude are interrelated causally. Therefore, experience related variables could be the antecedents of satisfaction and brand attitude. The satisfaction and positive emotion could be also important factors in brand attitude toward clothing.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.46 no.5
• /
• pp.848-867
• /
• 2022

As an emerging market with rapid economic growth, while being a key region of the K-culture expansion, Vietnam draws increasing scientific attention. This study focuses on the MZ generation, Vietnam's leading consumer group, revealing their consumption value structure. An online survey was used for data collection purposes, investigating 368 Vietnamese consumers between 18-37 years of age. Six value dimensions were derived as results of the present analysis: functional, emotional, social, ethical, self-expression, and autonomy-oriented value. Among them, functional value includes two sub-dimensions of utility and price, while emotional value entails three sub-dimensions, namely hedonism, novelty, and aesthetics. 'Self-expression value' and 'autonomy-oriented value', reflecting the characteristics of the MZ generation, who actively express themselves and respect proactive decision-making, are becoming important standards of the consumption attitude of young Vietnamese. Moreover, the pursuit of 'novelty' was derived as a factor reflecting emotional values, revealing an association between hedonic consumption, and seeking for newness and difference. Furthermore, the relationships between each consumption value dimension, respective demographic characteristics, and global consumption propensity were investigated. The present findings aim to provide insights into young Vietnamese consumers' attitudes and intend to serve as a foundation for future research.