• Journal of the Korean Operations Research and Management Science Society
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• v.13 no.2
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• pp.18-24
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• 1988

We consider sensitivity analysis sequencing problems, in which sequence of a finite set of expansion projects is sought to meet a deterministic demand projection in minimum discounted cost. In particular, by characterizing the underlying network structure, we find analytically the sensitivity range for a project cost such that the optimal sequencing policy remains unchanged for any value in the range. A numerical example is presented.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.64.3-64.3
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• 2017

For the detection of transient sources in optical wide field surveys like KMTNet Supernova Project, difference imaging technique is commonly used. As this method produces a fair amount of false positives, it is also common to utilize machine learning algorithms to screen likely true positives. While deep learning methods such as a convolutional neural network has been successfully applied recently, its application can be limited if the size of the training sample is small. I will discuss a variation of more conventional method that adopts the wavelet transform for feature engineering and its performance.

• Atmosphere
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• v.30 no.2
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• pp.169-181
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• 2020

We conducted a study on the impact of observation station density; this was done in order to enable the accurate estimation of spatial meteorological variables. The purpose of this study is to help operate an efficient observation network by examining distributions of temperature, relative humidity, and wind speed in a test area of a three-dimensional meteorological observation project in the Yeongdong region in 2019. For our analysis, we grouped the observation stations as follows: 41 stations (for Step 4), 34 stations (for Step 3), 17 stations (for Step 2), and 10 stations (for Step 1). Grid values were interpolated using the kriging method. We compared the spatial accuracy of the estimated meteorological grid by using station density. The effect of increased observation network density varied and was dependent on meteorological variables and weather conditions. The temperature is sufficient for the current weather observation network (featuring an average distance about 9.30 km between stations), and the relative humidity is sufficient when the average distance between stations is about 5.04 km. However, it is recommended that all observation networks, with an average distance of approximately 4.59 km between stations, be utilized for monitoring wind speed. In addition, this also enables the operation of an effective observation network through the classification of outliers.

• Korean Journal of Social Welfare
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• v.63 no.1
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• pp.57-84
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• 2011

This study aims to analyze a whole network effectiveness by expanding the unit of analysis beyond individual organizations in a network into network-level collaborative relations. Data for the analysis were drawn from the evaluation reports and surveys of leaders, mid-level managers, and staff members of the organizations participating in 'Community Network Building' project which was funded by Community Chest of Korea and carried out by the Academy of Korean Social Welfare Administration from November 2006 to November 2009. For the analysis, three out of the 10 networks established in diverse local communities were selected. Based on the survey conducted on the participating organizations and the center organization of each network, we analyzed the structural characteristics of interorganizational network at a network-level. Second, to analyze effectiveness of the whole network, we employed a multiple stakeholders perspective and examined the relations between the whole network's structure and its effectiveness. The findings showed that the whole network effectiveness is higher when the network is more centralized around the hub organization and more stable. The significance of this study is that it is provided and tested a new framework for network effectiveness evaluation by combining the two network effectiveness evaluation framework of Provan and Milward's with evolutionary organizational theory.

• Proceedings of the KSR Conference
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• 2008.06b
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• pp.27-41
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• 2008

Construction of metro transportation infra is a large-scale project requiring tremendous financial resources. This study suggests operation method to use for rapid transit line existing infra such as Gyeongbu line and spare line capacity following second phase KTX construction. Reviewing various constraints of metro rapid transit operation, we found that the conditions for metro rapid transit operation are already satisfied in Daegu area, just like the case of Gyeongbu line in Seoul Metro area. Also, the evaluation of the economic feasibility of metro rapid transit operation in Daegu area shows that B/C is about 2.4, which implies that there is sufficient economic feasibility. According to the result of sensitivity analysis, the project is economically feasible unless the passenger demand decreases 15% and construction costs increases more than 70%. B/C is evaluated large because the utilization of already exiting infra lowers the initial cost. As one of mass transportation system of large capacity, metro rapid transit can generate significant spillover effect: It will strengthen competitiveness of metro area by connecting cities within the area and by extending one-day life zone of the area, to say nothing of the benefit of improving traffic condition. The construction of metro rapid transit network is necessary for the mass transportation system of Yeongnam area as well as Daegu area, and it may work as a starting point for uniting Daegu and Gyeongbuk and strengthening regional competitiveness.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.4
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• pp.465-472
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• 1998

Korean Administration has launched the KIT(Korean Information Infrastructure) project to strengthen national competitiveness and to improve people's quality of life in preparations for the coming information society in the 21s1 century. It is estimated of 3.19 trillion won for the KII construction starting from 1995 by 2010. The KII is to be implemented in three major stages: deployment such as Network test bed, Government network, and Public network. This paper shows overall trends of domestic and foreign information and telecommunication market, and achievements and issues of the 1st stage trials. This paper suggests some considering points for the successful deployment of the KII project.

• Knowledge Management Research
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• v.18 no.4
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• pp.287-306
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• 2017

This research focus on the effect of developers' participation structure in knowledge creation and knowledge sharing activities in open source software development projects. Based on preferential selection theory, hypotheses of relationship between a developers' concentration of knowledge creation/sharing activities and collaboration performance was derived. To verify the hypotheses, we use the Gini coefficient in the commit contribution of the developers (knowledge creation) and the centralization index in the repository issue network (knowledge sharing network). Using social network analysis, this paper calculates centralization index from developers in the issue boards in each repository based on data from 837 repositories in GitHub, a leading open source software development platform. As a result, instead of all developers creating and sharing knowledge equally, only a few of developers creating and sharing knowledge intensively further improve the performance of the open collaboration. In other words, a few developers predominantly providing commit and actively responding to issues raised from other developers enhance the project performance. The results of this study are expected to be used by developers who manage open source software project as a governance strategy, which could improve the performance of open collaboration.

• Journal of Science and Technology Studies
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• v.9 no.2
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• pp.51-78
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• 2009

Usually, Technological failures have been recognized as a mundane and inevitable process of trial and error for finally achieving success, or pathological technologies clearly different from success. These approaches easily ignore that a failed technology also constructed complex technological networks with various actors for some times. Consequently, failed technologies failed not only technological realization, but also got a proper evaluation. This paper explore the emergence and decline of the city phone project (CT-2 technology), the very typical failure cases in the telecommunications industry at Korea. This story shows that the city phone project with low-price and low-technology could constructed a stable network at agreement the result from interaction between various actors, and then, changed because various actors gave technologies different meaning and desire. Finally, it suggests that collapse of its technological network was attributed to uncertain future and contingent, rather than technological limits.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.489-491
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• 2002

The need for video diagnosis in medicine has been increased and real-time transfer of digital video will be an important component in PACS and telemedicine. But, Network environment has certain limitations that the required throughput can not satisfy quality of service (QoS). MPEG-4 ratified as a moving video standard by the ISO/IEC provides very efficient video coding covering the various ranges of low bit-rate in network environment. We implemented MPEG-4 CODEC (coder/decoder) and applied various compression ratios to moving ultrasound images. These images were displayed in random order on a client monitor passed through network. Radiologists determined subjective opinion scores for evaluating clinically acceptable image quality and then these were statistically processed in the t-Test method. Moreover the MPEG-4 decoded images were quantitatively analyzed by computing peak signal-to-noise ratio (PSNR) to objectively evaluate image quality. The bit-rate to maintain clinically acceptable image quality was up to 0.8Mbps. We successfully implemented the adaptive throughput or bit-rate relative to the image quality of ultrasound sequences used MPEG-4 that can be applied for diagnostic performance in real-time.

• Korean Journal of Construction Engineering and Management
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• v.7 no.4 s.32
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• pp.91-99
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• 2006

The purpose of this study is propose an Artificial Neural Network(ANN) model for the construction estimate of the public educational facility at conceptual stage. The current method for the preliminary cost estimate of the public educational facility uses a single-parameter which is based on basic criteria such as a gross floor area. However, its accuracy is low due to the nature of the method. When the difference between the conceptual estimate and detailed estimate is huge, the project has to be modified to meet the established budget. Thus, the ANN model is developed by using multi-parameters in order to estimate the project budget cost more accurately. The result of the research shows 6.82% of the testing error rates when the developed model was tested. The error rates and the error range of the developed model are smaller than those of the general preliminary estimating model at conceptual stage. Since the proposed ANN model was trained using the detailed estimate information of the past 5 years' school construction data, it is expected to forecast the school project cost accurately.