• Korean Chemical Engineering Research
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• v.55 no.1
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• pp.54-59
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• 2017

A study for process design to curtail the utility consumption during residual styrene monomer recovery in an ABS polymerization process was carried out. Among different techniques for residual monomer recovery, the steam stripping is dominantly employed in industries. The existing process, however, consumes a large amount of utility (steam and cooling water), and this study focused on the design of a new process that can substantially spare the utility consumption. A new process was configured to utilize the latent heat of the stripping steam, which is condensed with the monomer using cooling water after exiting the stripper. The condenser was modified to use vacuum state water as coolant and to generate vacuum state steam using the latent heat of the stripping steam. The steam is injected to the stripper as the stripping steam after upgrading using a compressor. Through this modification, consumption of steam and also cooling water could be significantly reduced at some expense of electricity for compressor operation.

• Journal of the Chungcheong Mathematical Society
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• v.27 no.1
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• pp.145-149
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• 2014

I consider the optimal consumption and portfolio selection problem with nonnegative wealth constraints using the dynamic programming approach. I use the constant relative risk aversion (CRRA) utility function and disutility to derive the closed-form solutions.

• Journal of the Chungcheong Mathematical Society
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• v.25 no.2
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• pp.277-281
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• 2012

I study an optimal consumption and portfolio selection problem with regime-switching using a dynamic programming method. With constant relative risk aversion (CRRA) utility I obtain optimal solutions in closed-form.

• Earthquakes and Structures
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• v.17 no.2
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• pp.233-244
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• 2019

In this work, we have studied the effects of different soil thicknesses, haunch heights, reinforcement forms and construction technologies on the seismic performance of a composite precast fabricated utility tunnel by pseudo-static tests. Five concrete specimens were designed and fabricated for low-cycle reciprocating load tests. The hysteretic behavior of composite precast fabricated utility tunnel under simulated seismic waves and the strain law of steel bars were analyzed. Test results showed that composite precast fabricated utility tunnel met the requirements of current codes and had good anti-seismic performance. The use of a closed integral arrangement of steel bars inside utility tunnel structure as well as diagonal reinforcement bars at its haunches improved the integrity of the whole structure and increased the bearing capacity of the structure by about 1.5%. Increasing the thickness of covering soil within a certain range was beneficial to the earthquake resistance of the structure, and the energy consumption was increased by 10%. Increasing haunch height within a certain range increased the bearing capacity of the structure by up to about 19% and energy consumption by up to 30%. The specimen with the lowest haunch height showed strong structural deformation with ductility coefficient of 4.93. It was found that the interfaces of haunches, post-casting self-compacting concrete, and prefabricated parts were the weak points of utility tunnel structures. Combining the failure phenomena of test structures with their related codes, we proposed improvement measures for construction technology, which could provide a reference for the construction and design of practical projects.

• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1251-1260
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• 2013

This paper presents the optimal scheduling of hourly consumption in a residential community (community, neighborhood, etc.) based on real-time electricity price. The residential community encompasses individual residential loads, communal (shared) loads, and local generation. Community-aggregated loads, which include residential and communal loads, are modeled as fixed, adjustable, shiftable, and storage loads. The objective of the optimal load scheduling problem is to minimize the community-aggregated electricity payment considering the convenience of individual residents and hourly community load characteristics. Limitations are included on the hourly utility load (defined as community-aggregated load minus the local generation) that is imported from the utility grid. Lagrangian relaxation (LR) is applied to decouple the utility constraint and provide tractable subproblems. The decomposed subproblems are formulated as mixed-integer programming (MIP) problems. The proposed model would be used by community master controllers to optimize the utility load schedule and minimize the community-aggregated electricity payment. Illustrative optimal load scheduling examples of a single resident as well as an aggregated community including 200 residents are presented to show the efficiency of the proposed method based on real-time electricity price.

• Management Science and Financial Engineering
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• v.20 no.2
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• pp.13-25
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• 2014

We investigate an optimal retirement time and consumption/investment policy of a wage earner who expects to find a better investment opportunity after retirement by being freed from other work and participating fully in the financial market. We obtain a closed form solution to the optimization problem by using a dynamic programming method under general time-separable von Neumann-Morgenstern utility. It is optimal for the wage earner to retire from work if and only if his wealth exceeds a certain critical level which is obtained from a free boundary value problem. The wage earner consumes less and takes more risk than he would without anticipation of a better investment opportunity.

• Journal of the Korean Home Economics Association
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• v.25 no.2
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• pp.1-11
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• 1987

The purpose of the study is to researdch clothing consumer behavior of men and women over age of 20 years and to find out the reasonable maximum utility on clothing behavior. The factors are eight distinguished parts such as sex, age, monthly income, occupation, floor space, number of room, number of family and place of residence. A common questionaire is introduced to survey the clothing consumption activity and the home background. Sources to measure them are gathered in the whole country including major cities. The questionaire of 915 correspondents of 368 males and 547 females is investigated for this research. Some of the data are analyzed by correlation, frequency, percentage, mean, and S.D. Others are investigated by ANOVA Test, x2-Test, and Multiple Range Test. The results from the survey are as followings: 1. Only four factors such as sex, monthly income, occupation, and floor space have a significance in the clothing consumption activity. 2. This survey reveals that many cloths have been kept in dead storage and concerns of utility have risen high. 3. This survey has shown that the correspondents have deep concerns about using colthing exchange store, clothing lending store, and trunk room to utilize dead storage clothing efficiently.

• Journal of Korean Society of Forest Science
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• v.81 no.3
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• pp.280-286
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• 1992

When the social cost-benefit analysis is applied for analyzing the public forestry investment, the choice of discount rate to be used in analysis is critical. In this paper, the social discount rate discussed in the public economics was introduced and the social time preference rate as a measure of that was estimated for Korea. The component parameters of the model used are : the elasticity of social marginal utility of consumption and the growth rate of real consumption. The results for the social time preference rate and the elasticity of social marginal utility of consumption are 6.2% and -1.38, respectively, which are plausible and thus can be used as a useful basis in establishing rational resource allocation policies.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.3
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• pp.1204-1227
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• 2020

The tradeoff between energy conservation and traffic balancing is a dilemma problem in Wireless Sensor Networks (WSNs). By analyzing the intrinsic relationship between cluster properties and long distance transmission energy consumption, we characterize three node sets of the cluster as a theoretical foundation to enhance high performance of WSNs, and propose optimal solutions by introducing rendezvous and Mobile Elements (MEs) to optimize energy consumption for prolonging the lifetime of WSNs. First, we exploit an approximate method based on the transmission distance from the different node to an ME to select suboptimal Rendezvous Point (RP) on the trajectory for ME to collect data. Then, we define data transmission routing sequence and model rendezvous planning for the cluster. In order to achieve optimization of energy consumption, we specifically apply the economic theory called Diminishing Marginal Utility Rule (DMUR) and create the utility function with regard to energy to develop an adaptive energy consumption optimization framework to achieve energy efficiency for data collection. At last, Rendezvous Transmission Algorithm (RTA) is proposed to better tradeoff between energy conservation and traffic balancing. Furthermore, via collaborations among multiple MEs, we design Two-Orbit Back-Propagation Algorithm (TOBPA) which concurrently handles load imbalance phenomenon to improve the efficiency of data collection. The simulation results show that our solutions can improve energy efficiency of the whole network and reduce the energy consumption of sensor nodes, which in turn prolong the lifetime of WSNs.

• Fashion & Textile Research Journal
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• v.17 no.3
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• pp.372-381
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• 2015

This study investigates differences in fashion products attributes, mobile shopping mall attributes, impulse buying behavior, and satisfaction according to mobile shoppingconsumption value. The findings provide new information on marketing strategy for mobile shopping malls. A total of 283 usable questionnaires were obtained from college students. Data were analyzed by frequency analysis, factor analysis, and ANOVA using SPSS 21.0 for Windows. The results were as follows. First, according to the consumption value, consumer were classified into 3 groups: social/functional oriented, indifference and epistemic/emotional oriented. Second, the conspicuous-functional pursuit group considered utility and exhibition more important in regards to fashion products attributes for the consumption value group, the personality pursuit group also considered aesthetics and utility more important than other groups. Third, conspicuous-functional pursuit group considered continuous management more importantin regards to the importance ofmobile shopping mall attributes for the consumption value group, the personality pursuit group considered informationexchange more important than the other groups. Fourth, the conspicuous-functional pursuit group and Personality pursuit group considered impulse purchase behavior more important than the emotionalpursuit group. The conspicuous-functional pursuit group considered satisfaction after impulse purchase behavior more important than other groups.