• Journal of Korean Society of Transportation
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• v.1 no.1
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• pp.43-47
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• 1983

Within the conventional transportation planning process, "trip distribution" has a significant role to play. The most widely applied trip distribution model is the gravity model, for which Wilson provided the theoretical basis in 1967. The concept of the gravity model, however, still remains ambiguous if we analyze the "trip distribution" with a disaggregate data set. Thus, this paper hypothesizes that the gravity technique is still valid even with the disaggregate data set, by proving that the estimated coefficients of the gravity model, which is derived under the principle of entropy maximization, are identical with those of the multinomial logit model, which is derived under the principle of individual utility maximization.tility maximization.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.276-278
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• 1998

This paper introduce an algorithm for service restoration in electric power distribution systems. Power utility performs service restoration in order to restore out-of-service areas at fault. Developing effective service restoration program is a cost-effective approach to improve service reliability and to enhance customer satisfaction. The main objective in service restoration program is to restore as much load as possible by transferring de-energized loads via network reconfigurations to other supporting distribution feeders without violating operating and engineering constrains.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.3
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• pp.27-34
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• 2024

The direct and indirect damages caused by fires in underground utility tunnels have a great impact on society as a whole, so efforts are needed to prevent and manage them in advance. To this end, research is ongoing to prevent disasters such as fire flooding by applying digital twin technology to underground utility tunnels. A network is required to transmit the sensed signals from each sensor to the platform. In essence, it is necessary to analyze the application of wireless networks in the underground utility tunnel environments because the tunnel lacks the reception range of external wireless communication systems. Within the underground utility tunnels, electromagnetic interference caused by transmission and distribution cables, and diffuse reflection of signals from internal structures, obstacles, and metallic pipes such as water pipes can cause distortion or size reduction of wireless signals. To ensure real-time connectivity for remote surveillance and monitoring tasks through sensing, it is necessary to measure and analyze the wireless coverage in underground utility tunnels. Therefore, in order to build a wireless network environment in the underground utility tunnels. this study minimized the shaded area and measured the actual cavity environment so that there is no problem in connecting to the wireless environment inside the underground utility tunnels. We analyzed the data transmission rate, signal strength, and signal-to-noise ratio for each section of the terrain of the underground utility tunnels. The obtained results provide an appropriate wireless planning approach for installing wireless networks in underground utility tunnels.

• Journal of Korean Institute of Industrial Engineers
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• v.28 no.1
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• pp.112-127
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• 2002

A useful pattern is a pattern that contributes much to learning. For a classification problem those patterns near the class boundary surfaces carry more information to the classifier. For a regression problem the ones near the estimated surface carry more information. In both cases, the usefulness is defined only for those patterns either without error or with negligible error. Using only the useful patterns gives several benefits. First, computational complexity in memory and time for learning is decreased. Second, overfitting is avoided even when the learner is over-sized. Third, learning results in more stable learners. In this paper, we propose a pattern 'utility index' that measures the utility of an individual pattern. The utility index is based on the bias and variance of a pattern trained by a network ensemble. In classification, the pattern with a low bias and a high variance gets a high score. In regression, on the other hand, the one with a low bias and a low variance gets a high score. Based on the distribution of the utility index, the original training set is divided into a high-score group and a low-score group. Only the high-score group is then used for training. The proposed method is tested on synthetic and real-world benchmark datasets. The proposed approach gives a better or at least similar performance.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.7
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• pp.91-101
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• 2021

The paper examines the impact of the COVID-19 pandemic on the stock market prices. The vector autoregression model (VAR) has been used in this analysis to survey 341 stocks on the Ho Chi Minh City Stock Exchange (HOSE) for the period from January 23, 2020 to December 31, 2020. The empirical results obtained from the analysis of 11 economic sectors suggest that there is a statistically significant impact relationship between COVID-19 and the healthcare and utility industries. Additional findings show a statistically significant negative impact of COVID-19 on the utility share price at lag 1. Analysis of impulse response function (IRF) and forecast error variance decomposition (FEVD) show an inverse reaction of utility stock prices to the impact of COVID-19 and a gradual disappearing shock after two steps. Major findings show that there is a clear negative effect of the COVID-19 pandemic on share prices, and the daily increase in the number of confirmed cases, indicate that, in future disease outbreaks, early containment measures and positive responses are necessary conditions for governments and nations to protect stock markets from excessive depreciation. Utility stocks are among the most severely impacted shares on financial exchanges during a pandemic due to the high risk of immediate or irreversible closure of manufacturing lines and poor demand for basic amenities.

• Computers and Concrete
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• v.29 no.2
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• pp.69-79
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• 2022

For long underground box utility tunnels, post-tensioned precast concrete is often used. Between precast tunnel segments, sealed waterproof flexible joints are often specified. Fault displacement can lead to excessive deformation of the joints, which can lead to reduction in waterproofing due to diminished contact pressure between the sealant strip and the tunnel segment. This paper authenticates utilization of a finite element model for a prefabricated tunnel fault-crossing founded on ABAQUS software. In addition, material parameter selection, contact setting and boundary condition are reviewed. Analyzed under normal fault action are: the influence of fault displacement; buried depth; soil friction coefficient, and angle of crossing at the fault plane. In addition, distribution characteristics of the utility tunnel structure for vertical and longitudinal/horizontal relative displacement at segmented interface for the top and bottom slab are analyzed. It is found that the effect of increase in fault displacement on the splice joint deformation is significant, whereas the effects of changes in burial depth, pipe-soil friction coefficient and fault-crossing angle on the overall tunnel and joint deformations were not so significant.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.44
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• pp.129-134
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• 1997

The purpose of this study is to estimate the distribution rate of R&D input on R&D output in major manufacturing industrial sector. The distribution rate is estimated on time-series data for the period 1980 to 1996. The data used in this study can be divided into the two categories. 1) R&D output data (Patent, Utility) 2) R&D input data (R&D expenditure, R&D workers) The raw data of R&D expenditure is transformed into R&D stock. And the specific production function is used to represent the interaction between R&D input and output. The production function shows the maximum rate of R&D output that can be achieved by certain given, technologically possible, R&D input combinations. The main findings can be summarized as follows. 1) There was a diminishing return between R&D input and output$(\alpha+\beta<1). 2) R&D output growth was more affected by R&D expenditures than R&D workers. 3) R&D workers were more contributed highly to Patent granted than Utility model.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.365-369
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• 2006

It is concentrated on a methodology to establish a scheme of investment on power distribution systems of components. This paper provides a methodology to estimate the scheme as using a customer interruption cost regarding reliability indices in power distribution systems. The proposed method basically uses the failure rate depending on time for explaining the deterioration of a component. Therefore, the theory of the sensitivity is used for deciding the precedence of the investment to consider an effect of each component's failure rate on the system reliability. After Estimating the sensitivity on component investment cost making incremental reliability level is produced by component's investment cost accumulated according to the precedence of the sensitivity. After that, the failure rate corresponding with reliability level on the curve of investment cost is used as producing the curve of customer interruption cost. Two curves have the crossing point that is proposed to acceptable reliability level for customer and utility. In this paper, the acceptable reliability level for customer with the utility is assessed to analyze customer interruption cost and sensitivity of reliability indices. In conclusion the result of investment based on this method is shown to the reliability level with two cost.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.6
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• pp.903-911
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• 2019

The multi-utility tunnel is one of the essential social infrastructures, but it is difficult to establish the multi-utility tunnel due to the scale of the National Land Planning and Utilization Act (2 million square meters). In this paper, we analyze the feasibility of establishing the multi-utility tunnel in the existing city in order to activate the multi-utility tunnel installation. For the feasibility analysis, the scale was classified into four categories based on related laws, and related indicators were selected and evaluated using feasibility and economic analysis. Three kinds/four kinds of suitable multi-utility tunnel for the scale of the existing city were shown, and five kinds of multi-utility tunnel were considered suitable for the new city over 2 million square meters. The results of the overall score evaluation of the tunnel type of the existing city and the open type of the new city of 2 million square meters or more, which is the obligation to install the multi-utility tunnel, do not show much difference and suggest the validity of the installation of the multi-utility tunnel in various scale of the existing city.

• The korean journal of orthodontics
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• v.27 no.3 s.62
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• pp.401-409
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• 1997

The purpose of this study was to analize the initial stress distribution around apex and the alveolar bone of the upper anterior teeth when applying intrusive force by the use of utility arthwire, Burstono 3-piece infusion archwire, and 'J' hook headgear which is usually used in clinital practice. By the use of the polarization plate, initial stresses were analized when 80g and 150g forte applied. The results were as follows. 1. With the utility archwire, moderate levels of stress were evenly distributed on the apical areas of the anterior teeth and concentrated on the apical areas of the first molars. 2. With the Burstone's 3-piece intrusion archwire, moderate levels of stress were evenly distributed on the apical areas of the anterior and posterior teeth. 3. With the 'J' hook headgear, severe levels oi stress were widely distributed on the alveolar bone and apical areas of the upper anterior teeth, and concentrated on the apical area between the central and the lateral incisors. Especially, weak levels of stress appeared along the periodontal ligament space of all teeth.