• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.7
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• pp.1638-1656
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• 2013

The demand for multimedia streaming services is increasing rapidly. To meet this demand, there has been much research and many practical developments for providing multimedia services. A push-to-talk (PTT) service is one of the multimedia streaming services that have been deployed not only over IP multimedia subsystem (IMS) but also in peer-to-peer (P2P) overlay networks. The benefit of PTT has been demonstrated in the literature. However, the need for using PTT service in communication can be arbitrary among users, regardless what kind of PTT services they use. This demand does not support current PTT systems, so an expansion of PTT services still be limited. Moreover, the combination of PTT services in IMS and P2P networks will help operators to provide more scalable PTT services. Therefore, in this paper, we proposed a model to support PTT service interworking between IMS and P2P overlay networks. We also introduced our system design and some interworking service scenarios. We confirmed our architecture through implementation and testing.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 1999.12a
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• pp.21-25
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• 1999

Planning support systems(PSS) add more advanced spatial analysis functions than Geographic information systems(GIS) and intertemporal functions to the functions of spatial decision support systems(SDSS). This paper reports the continuing development of a PSS providing a framework that facilitates urban planners and civil engineers in conducting coherent deliberations about planning, design and operation & maintenance(O&M) of water-distribution networks for urban growth management. The PSS using dynamic optimization model, modeling-to-generate-alternatives, value engineering(VE) and life-cycle cost(LCC) can generate network alternatives in consideration of initial cost and O&H cost. Users can define alternatives by the direct manipulation of networks or by the manipulation of parameters in the models. The water-distribution network analysis model evaluates the performance of the user-defined alternatives. The PSS can be extended to include the functions of generating sewer network alternatives, combining water-distribution and sewer networks, eventually the function of planning, design and O&H of housing sites. Capacity expansion by the dynamic water-distribution network optimization model using MINLP includes three advantages over capacity expansion using optimal control theory(Kim and Hopkins 1996): 1) finds expansion alternatives including future capacity expansion times, sizes, locations, and pipe types of a water-distribution network provided, 2) has the capabilities to do the capacity expansion of each link spatially and intertemporally, and 3) requires less interaction between models. The modeling using MINLP is limited in addressing the relationship between cost, price, and demand, which the optimal control approach can consider. Strictly speaking, the construction and O&M costs of water-distribution networks influence the price charged for the served water, which in turn influence the. This limitation can be justified in rather small area because price per unit water in the area must be same as that of neighboring area, i.e., the price is determined administratively. Planners and engineers can put emphasis on capacity expansion without consideration of the relationship between cost, price, and demand.

• The KIPS Transactions:PartD
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• v.15D no.1
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• pp.87-98
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• 2008

In company with the demand of powerful processing units for embedded systems, the method to develop embedded software is also required to support the demand in new approach. In order to improve the resource utilization and system performance, software modeling techniques have to consider the features of hardware architecture. This paper proposes a partitioning technique of UML-based software models, which focus the generation of the allocatable software components into multiprocessor architecture. Our partitioning technique, at first, transforms UML models to CBCFGs(Constraint-Based Control Flow Graphs), and then slices the CBCFGs with consideration of parallelism and data dependency. We believe that our proposition gives practical applicability in the areas of platform specific modeling and performance estimation in model-driven embedded software development.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.16 no.2
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• pp.153-161
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• 2021

This study analyzed the ripple effect of the demand-side support for start-up venture companies on the macro economy using Dynamic General Equilibrium model. In the model, start-up venture companies were expressed in a manner that distinguished between workers and entrepreneurs by applying the span of control in the Lucas(1978). As a result of the analysis, when the share of public procurement of start-up venture companies was increased from 5.7% to 10%, the actual production of start-up venture companies increased by about 46.17% and the number of venture companies increased by about 150%. In addition, it was analyzed that the number of jobs through venture companies increased by about 61.56%. In addition, it was found that the economic effect was greatly reduced when the start-up venture company was supported as a subsidy for the supply sector with the same amount as the public procurement support. This is interpreted as the fact that if the government implements the supply-side support policy, the expansion of supply causes the price of start-up venture companies to fall, reducing the effect of the support policy in half. Therefore, when supporting start-up venture companies, the government should make efforts to maximize the policy effect by expanding the demand-side support through public procurement and reducing the payment of simple subsidies to start-up venture companies.

• Korean Journal of Agricultural Science
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• v.46 no.4
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• pp.813-825
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• 2019

This paper investigated the effects of a government production and shipment stabilization policy and the improvement plan for vegetables in Korea. In this study, a simulation focused on the changes in farm income for Chinese cabbages & radishes using scenarios. The result shows an increase in farm income according to the government policy. In the short-term, demand and supply are fixed, and the policy effect is positive due to the price support effect of the project. However, for mid- to long-term, the price decreases due to the expansion of supply by business beneficiaries, which is likely to be adversely affected by an unstable supply and demand. This increases the burden of government and local government subsidies. This phenomenon is expected to be amplified as the ratio of production and shipbuilding stabilization programs and items expand. When expanding items and adjusting and setting the percentage of participation in the project, it is desirable to set and operate the appropriate business ratio taking into consideration the demand. To improve the effectiveness of the policy, the following remedies were suggested. First, national supply and demand guidelines should be set up, and the autonomous supply and demand control of the producers should be guided by the different preservation according to the implementation of the supply and demand control obligation. As for detailed equipment, it is necessary to establish the reproduction price for each item, set the base price for each wholesale market, increase the incentive for the producers to participate, and fund a business budget to secure business stability.

• Journal of the Korea Safety Management & Science
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• v.15 no.3
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• pp.151-161
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• 2013

This paper proposes a strategic model of linkage between productivity metrics and financial accounting metrics to properly evaluate the financial effect of TPM activities and the business performance. This linkage strategy provides a connection tool for clear communication between factory-level and headquarters that the metrics proposed by this paper ultimately improves a quality of support from the management by receiving the factors required for productivity activities in the practical field. This factor includes such as equipment, raw materials and labors. Here, we propose that chain reaction models using break down structure of productivity metrics and financial metrics enhance the knowledge sharing of KPI (Key Performance Indicator) which generally tend to create oversimplified communication between management in headquarters and employees in the practical fields. The productivity metrics include OEE(Overall Equipment Effectiveness) of TPM (Total Productive Maintenance), OLE (Overall Labor Effectiveness) of PAC(Performance and Analysis and Control) activities, and OYE (Overall Yield Effectiveness) of TMM(Total Material Management) activities. The financial accounting metrics include ROE(Return on Equity), ROA(Return on Asset), and AVR(Added-Value Rate). The suggested chain reaction model selects the financial metrics as initial stage and branch down until final stage of productivity metrics. When demand exceeds supply, an ideal speed rate, the lean OEE strategy can be initially applied to reduce the gap between the demand and supply, then apply variable costing to estimate correct amount of operating profit. In addition, the paper presents a new type of model for linkage between financial accounting metrics including CAPEX(Capital Expenditure), OPEX(Operating Expenditure), EVA(Economic Added Value), DCL(Degree of Combined Leverage), and TPM productivity activities including AM(Autonomous Maintenance), PM(Preventive Maintenance), MP(Maintenance Prevention) and QM(Quality Maintenance). In order to support the evidence of proposed linkage strategy, a case analysis on 52 projects from national TPM contest from 2011 to 2012 is analyzed. The case presents the classification of CAPEX and OPEX activities from TPM, and proposes the correct implementation of financial effect for TPM projects.

• Safety and Health at Work
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• v.1 no.1
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• pp.37-42
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• 2010

Over years it has been increasingly concerned with how upper extremity musculoskeletal disorders (UEMSDs) are attributed to psychosocial job stressors. A review study was conducted to examine associations between UEMSDs and psychosocial work factors, and to recommend what to consider for the associations. For studies in which the job demand-control-support (DCS) model or its variables were specifically employed, published papers were selected and reviewed. A number of studies have reported relationships between UEMSDs symptoms and psychosocial exposure variables. For example, the findings are: higher numbness in the upper extremity was significantly attributed to by less decision latitude at work; work demands were significantly associated with neck and shoulder symptoms while control over time was associated with neck symptoms; and the combination of high psychosocial demands and low decision latitude was a significant predictor for shoulder and neck pain in a female working population. Sources of bias, such as interaction or study design, were discussed. UEMSDs were shown to be associated with psychosocial work factors in various studies where the job DCS model was addressed. Nonetheless, this review suggests that further studies should be conducted to much more clarify the association between UEMSDs and psychosocial factors.

• Management & Information Systems Review
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• v.31 no.1
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• pp.167-182
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• 2012

Recently, interesting of u-city with ubiquitous computing technologies has increased. In this paper, we propose u-service model for urban facility management based on ubiquitous computing technologies. To propose the research purpose, we define business model for the service and u-service model. And, we propose service function, service process, and relationships between participants to give shape to u-service model. First, we present five service functions; remote monitoring, remote control and inquire, state information, field support, and facility history information. And, we propose overall service process and demand-supply relationship between participants.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.2
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• pp.168-174
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• 2021

According to the World Agricultural Productivity Report, the current annual average growth rate of agriculture is 1.63%, which is lower than 1.73% to support the world's 10 billion people, which is growing by 2050. The demand for food, feed, and bioenergy is not growing enough to continue to meet the demand, and it is predicting a future food shortage. The purpose of this study was to create a regional irrigation control model for the purpose of reducing the production cost of crops, increasing production, and improving quality, and presenting a model that can give advice to farmers who start farming in the region. The irrigation control modeling presented in this study means to represent the change of medium weight·supply liquid·drainage amount due to changes in the root zone environment according to the passage of time and climate in a graph model. For water control modeling, we collected data on the change in the amount of the root zone environment and the weight of the badge·supply amount·drainage amount from March to June in Nonsan, Buyeo, and Yesan regions in Chungnam Province through the measuring device of the Ministry of Environment in the root region. We set up the parameters for derivation and derived an irrigation control model that can confirm the change in weight·supply liquid·drainage amount over time through the parameters.

• Safety and Health at Work
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• v.6 no.3
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• pp.233-239
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• 2015

Background: The Job Content Questionnaire (JCQ), which is based on the Demand-Control-Support model, is designed to measure the psychosocial characteristics of the respondent's work, and has been identified to predict health and psychological outcomes. The purpose of this study was to investigate the psychometric properties of this instrument and the subsequent adaptation of its scales to the population of Greek health workers. Methods: The Greek version of the JCQ was developed by using forward- and back-translation in accordance with the JCQ policy. The reliability and validity of the measure were investigated in a sample of health workers working in a hospital in Athens, Greece. The internal consistency of the scales was examined based on Cronbach ${\alpha}$ coefficients, and the validity was evaluated subjecting the items of the three main scales of the JCQ (decision latitude, psychological job demands, and social support) to exploratory and confirmatory factor analysis. Results: The reliability of the scales was found to be acceptable for all the scales, except for the skill discretion subscale. Confirmatory factor analysis confirmed a slightly modified version of the original construct including several items to more than one factor. Conclusion: Our findings suggest that the Greek JCQ is reliable and valid for investigating psychosocial job characteristics among Greek health workers.