• Journal of the Korea Society for Simulation
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• v.18 no.4
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• pp.165-173
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• 2009

Recent portable devices are so versatile that they have multiple communication channels and play several multimedia formats. Especially, many services are under development for users who connect Internet or nearby devices via WWAN (Wireless Wide Area Network) and/or WLAN (Wireless LAN). In case of paying the telecommunication cost proportional to the amount of data downloaded, it is necessary to reduce the cost by constructing a special ad hoc network in which each participating peer downloads a specific portion of the want-to-be-shared content over the payable WWAN channel and exchanges the remaining portion with other peers using the cost-free WLAN channel. If all peers participate in forwarding packets, some transmissions are redundant which results in the unnecessary consumption of bandwidth as well as the delayed content distribution time. In order to reduce the redundant transmission, this paper proposes both the excluding method which discourages some peers not to forward redundant packets, and the minimum cover set method in which only the minimum number of peers are in charge of forwarding packets. These two methods obviate redundant packet forwarding, and result in reduction of content distribution time by up to around 29%.

• Journal of the Korean Association of Geographic Information Studies
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• v.21 no.3
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• pp.176-188
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• 2018

Modern urban problems are increasingly becoming a market mix that can not be solved by the power of a single department and the necessity of establishing a cooperation system based on data communication between departments is increasing. Therefore, this study analyzed Busan metropolitan city's IT projects from 2014 to 2018 in order to understand the utilization and sharing status of departmental data from the viewpoint that cooperation between departments can start from the sharing of data with high common utilization. In addition, based on the results of the FGI(Focus Group Interview) conducted for the officials of the department responsible for the informatization project, we verified the results of data status analysis. At the same time, we figured out the necessity of data link between departments through SNA(Social Network Analysis) and presented data that should be shared first in the future. As a result, most of the information systems currently use limited data only within the department that produced the data. Most of the linked data was concentrated in the information department. Therefore, this study suggested the following solutions. First, in order to prevent overlapping investments caused by the operation of individual departments and share information, it is necessary to build a small platform to tie the departments, which have high connectivity with each other, into small blocks. Second, a local level process is needed to develop data standards as an extension of national standards in order to expand the information to be used in various fields. Third, as another solution, we proposed a system that can integrate various types of information based on address and location information through application of cloud-based GIS platform. The results of this study are expected to contribute to build a cooperation system between departments through expansion of information sharing with cost reduction.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.17 no.5
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• pp.29-41
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• 2014

Ecosystem services provide various benefits to human beings, but are considered to be free of cost. To protect ecosystems in an economically sustainable way, several developing countries have adopted a policy known as the Payment for Ecosystem Services (PES) that compensates upstream services with monetary incentives collected from service users. Vietnam is one of the countries that have enacted a nationwide PES policy. However, the policy in Vietnam requires further development in order to evaluate the spatial priority zones based on the quantification of ecosystem services. To obtain a recent and high-quality land cover map, we first classified the land cover in the Da River basin, in northern Vietnam, using Landsat dataset. We then applied a water balance theory and an USLE equation to assess hydrological ecosystem services concerning water supply and sediment retention. Following the assessment, we identified the priority areas for hydrological ecosystem services exclusively for forest environments. We found that the quantity and distribution of services from forests varied, due to the topography, climate, and land cover. According to a quantile distribution, Mt. Phu Luong, Mt. Fansipan, and Hoang Lien National Park were evaluated as high service areas in terms of both water yield and sediment retention. As a result, this assessment method can help construct spatial priority zones concerning ecosystem service distribution, and can also contribute to benefit sharing by indicating which forest and landowners require compensation.

• Journal of the Korean Association of Geographic Information Studies
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• v.17 no.2
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• pp.32-43
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• 2014

To identify major causes of the global environment changes arising from extreme and unusual weather patterns occurring these days, and to foresee future environmental changes, it is highly important to shed light on the correlation between climate changes and global environment system. To investigate the correlation between climate changes and global environment system, it calls for establishing an integrated climate-environment DB for analyzing comparatively the data on climatic changes and global environment system. In the preceding studies, we researched an XML-based integrated climate-environment DB and developed a management system for the DB. However, the existing integrated climate-environment DB, designed and installed only for individual PCs, does not allow multiple users 'simultaneous access. Accordingly, it fails to systematically update and sharing data which is being generated continuingly. Hence, this study aims to develop an easy-to-use GIS-based integrated DB management system by improving the existing integrated climate-environment DB through the adoption of the client/server model. For this, this study collected and analyzed climate and environment data prior to designing and building a DBMS-based integrated DB. In addition, in order for multidisciplinary researchers to easily get access and apply the integrated DB, this study designed and developed a GIS-based integrated DB management system using a client/server model which facilitates connections with multiple PCs. The GIS-based integrated climate-environment DB management system makes it easier to efficiently manage and locate scattered climate-environment data. It is also expected that the DB system will bring the effects in saving time and cost by avoiding the overlapping generation of data in the areas of integrated climate-environment research.

• The KIPS Transactions:PartB
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• v.9B no.6
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• pp.835-844
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• 2002

The number of channels available to a video server is limited since the number of channels a video server can support is determined by its communication bandwidth. Several approaches such as batching, piggybacking and patching have been proposed to reduce I/O demand on the video server by sharing multicast data. Patching has been shown to be efficient in the matter of the cost for VOD systems. Unlike conventional multicast techniques, patching is a dynamic multicast scheme which enables a new request to join an ongoing multicast. In addition, true VOD can be achieved since a new request can be served immediately without having to wait for the next multicast. In this paper. we propose two types of channel reservation patching algorithm : a fixed channel reservation patching and a variable channel reservation patching. To immediately schedule the requests for popular videos, these algorithms reserve the channels of video server for the fixed number of popular videos or for the variable number of popular videos which is determined dynamically according to the load of video server. The performance of the proposed algorithms is evaluated through simulations, and compared with that of simple patching. Our performance measures are average defection rate, average latency, service fairness and the amount of buffered data according to video server loads. Simulation results show that the proposed channel reservation patching algorithms provide better performance compared to simple patching algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7B
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• pp.685-696
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• 2004

Real-time multimedia applications that require large amount of bandwidth need resource reservation before starting service for providing the QoS(i.e., Quality of Service). To reserve resources in advance, each reservation request has to notify its expectation on the required amount of resources and service duration. Using this information, a resource manager can schedule advance reservations. However, most existing resource management systems are adopting straightforward call admission control process (i.e., only immediate reservation) by checking currently available resources without considering the service duration. Hence, the resource management system that supports advance reservation has to manage confliction caused by indefinite service duration of immediate reservation. Even though the separation of resource pool according to type of reservation can prevent the confliction, it causes low resource utilization. In this paper, we propose an effective resource management scheme that supports both immediate and advance reservations by sharing resources dynamically. Using network cost function, the proposed scheme determines and adaptively adjusts resource boundary according to the confliction rate by varying weight parameters. And also, we define user utility function to quantify user satisfaction based on how well the reserved resource is guaranteed during service time. Simulation results using NS-2 network simulator show that the proposed scheme can achieve better resource utilization with preferable QoS than other schemes like static resource partitioning.

• KDI Journal of Economic Policy
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• v.14 no.4
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• pp.79-106
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• 1992

This study analyzes the determinants of wage premium, defined as the excess of actual wage rate over opportunity wage, for the average worker in a Korean bargaining unit. Average wage premium of a firm is decomposed into quasi-rent per worker and rent-sharing rule. Per capita quasi-rent, representing a firm's ability to pay, is defined as the difference between sales revenue and the opportunity cost of mobile factors, divided by the number of employees. Rent-sharing rule, a measure of workers' bargaining power, is defined as the average wage premium divided by the per capita quasi-rent. Empirical results show that the differences in wage premium among Korean bargaining units are much better explained by the differences in quasi-rent than by the differences in bargaining power. Also, comparing the results of 1986 with those of 1988 show that the wage settlement mechanism in 1988 was not quite different from that of 1986, in spite of the drastic change in industrial relation system in 1987. It may simply yield higher opportunity wages, by raising the bargaining power of overall workers. The tendency of Korean labor market in 1988 to show a dual structure of high & low wage premium sectors, is not due to the fact that the differences in bargaing powers across firms tend to expand, but to the fact that unions tend to reduce the wage differences among the workers within an enterprise by pursuing more equal distribution of total wage premium. Hence, the policies for reducing the wage differentials across firms should focus on rent-regulating industrial policies, e.g. eliminating monopoly rents by deregulation.

• Journal of Korea Spatial Information System Society
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• v.5 no.2 s.10
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• pp.55-68
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• 2003

NGIS projects have been widely proceeded by the central and municipal governments, and the higher cost for proceeding the NGIS projects emphasizes the importance of the data sharing among related agencies. For supporting data sharing, effective data generation, and management. 'THE GUIDELINE FOR MANAGING AND DOCUMENTING GEOGRAPHIC INFORMATION CATALOGUES' has been established and enforced since the year 2002. Although metadata for distributing geographic information through the NGIS distribution network has already been installed, this needs to be complimented to maximize the data utilization. Based on such requirements, a draft standard of the national metadata which is compliant with the ISO 19115 has been proposed from this study. All components of the metadata for distributing geographic information have been included and related metadata items for the management purpose have been derived from domestic and foreign studies. Based on this, draft national metadata standards comprised of 13 sections have been made. The metadata standards from this study could contribute to building basic standards to access and to utilize geographic information in various application field. This would also be fundamental base for activating GIS in public and private sectors.

• Tuberculosis and Respiratory Diseases
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• v.59 no.5
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• pp.480-486
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• 2005

Since the year 2000, lung cancer has become the leading cause of cancer death in South Korea as in many other parts of the world. The current multidisciplinary approach for lung cancer includes a wide range of modalities, not only surgery, radiotherapy, medical drug therapy but also pain control, as well as social and psychological support. Therefore, thoracic surgeons, radiologists, nuclear medicine specialists, anesthetists, psychologist, nurses and social workers as well as medical doctors care for lung cancer patients. Sharing a common treatment protocol and optimal communication are vital aspects of shared care both from a medical and cost-effectiveness point of view. We developed a shared electronic medical record (SEMR) for treating patients with lung cancer in a university hospital to facilitate the sharing protocols and communications between doctors involved in a lung cancer clinic. A SEMR system was developed within a order communication system(OCS) for a lung cancer clinic. The records of radiological, laboratory and pathological studies as well as the records of surgery, chemotherapy, and radiotherapy were stored and presented to all doctors who treat the same patient. Every doctor was allowed to change his/her own records. They could review other doctor s records but could not alter them. With the SEMR, it was expected that the time to complete the medical records for one patient could be reduced because it was easy to review all the data from the other doctors who share the same patient. In addition, the confidence of the doctors who share a common treatment protocol would be higher. Therefore, a shared electronic medical record is expected to improve the quality of patient care.

• Management & Information Systems Review
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• v.35 no.2
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• pp.45-66
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• 2016

Firms can make scale of economy and scope of economy by internalizing and using new advanced technology and knowledge from technology cooperation network, decrease risk and cost with partner firm of technology cooperation network, and increase market advantage of product & strengthen firms' position in the market. Due to the advantages of technology cooperation network, the related studies have focused on the positive effect of technology cooperation network. However, the related studies investigating the relationship between technology cooperation network and firm performance have only examined the role of technology cooperation network. Safeguarding mechanism, relationship learning, and relationship performance are categorized into the process of technology cooperation network, and this categorization is applied as resources, capability, and performance by resource based view. The empirical results are reported as belows. First, relationship specific investment and relationship capital positively affect on relationship learning as capability. Second, information sharing, common information understanding, and relationship specific memory development positively affect on long-term orientation, but information sharing has no impact on efficiency and effectiveness. Third, relationship specific investment positively affects on relationship capital and efficiency and effectiveness have positive effects on long-term orientation. Applying technology cooperation network in asymmetric technology dependency with resource based theory, this study suggested the importance of both safeguarding and relationship learning by investigating the relationship among safeguarding, relationship learning, and relationship performance. And it is worthy that this study investigated how firms' behavior change affects relationship performance in the relationship of technology cooperation partner.