• Asia pacific journal of information systems
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• v.17 no.3
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• pp.55-78
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• 2007

Increasingly the information technology (IT) outsourcing phenomenon has been a subject of much academic research. Scholars have argued that knowledge complementarities playa crucial role in forming successful IT outsourcing relationships. However, notwithstanding the fast growth of IT outsourcing, prior studies on IT outsourcing have not included knowledge complementarities in their research design as a determining factor for IT outsourcing effectiveness. Further, the understanding of knowledge complementarities itself remains ambiguous. In this study, the concept of knowledge complementarities is explored in the IT outsourcing context at the firm level. Specifically, it addresses the following questions: what is knowledge complementarities? How does it affect IT outsourcing effectiveness? Is the relationship between knowledge complementarities and IT outsourcing effectiveness influenced by organizational trust between the client and the vendor? Grounded in the relevant theories to knowledge management and IT outsourcing, we develop a research model in which both the main effects of knowledge complementarities and organizational trust and the moderating effect of organizational trust on the relationships between knowledge complementarities and IT outsourcing effectiveness are tested. Within this research model, we develop a second order construct of knowledge complementarities, consisting of complementary business knowledge and complementary IT knowledge as the first order constructs. We have used data from a field study of 103 firms in Korea to test the proposed model. Controlling the effects of conflict resolution efforts, our empirical analysis found significant main effects of knowledge complementarities and organizational trust on IT outsourcing effectiveness. The results suggest that knowledge complementarities between the client and vendor positively contribute to IT outsourcing effectiveness. Specifically, the client needs to have enough IT knowledge to assess the quality of IT outsourcing services provided by the vendor. Meanwhile, the vendor should understand the client's business well enough to provide IT services, Contrary to our expectations, the moderating effect of trust on the relationship between knowledge complementarities and IT outsourcing effectiveness was not supported in this study. The results also show that organizational trust between client and vendor significantly influences IT outsourcing effectiveness. As for contributions of this study, we have not only clarified the concept of knowledge complementarities, but also developed an instrument to measure the concept and empirically validated it. Further, we have tested the idea that knowledge complementarities and trust directly influence IT outsourcing effectiveness and trust moderates the relationship between knowledge complementarities and IT outsourcing effectiveness. Out results prescribe the knowledge complementarities of client and vendor as a useful path to IT outsourcing effectiveness. These findings have important theoretical and practical implications, which are discussed in the paper.

• Journal of Internet Computing and Services
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• v.16 no.5
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• pp.19-27
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• 2015

Due to the advantages of fast read/write operation and low power consumption, SSD(Solid State Drive) is now widely adopted as storage device of smart phone, laptop computer, server, etc. However, the shortcomings of SSD such as limited number of write operations and asymmetric read/write operation lead to the problem of shortened life span of SSD. Therefore, the block replacement policy of SSD used as cache for HDD is very important. The existing solutions for improving the lifespan of SSD including the LARC scheme typically employ the LRU algorithm to manage the SSD blocks, which may increase the miss rate in SSD due to the replacement of frequently used block instead of rarely used block. In this paper we propose a novel block replacement scheme which considers the block reuse interval to effectively handle various data read/write patterns. The proposed scheme replaces the block in SSD based on the recency decided by reuse interval and age along with hit ratio. Computer simulation using workload trace files reveals that the proposed scheme consistently improves the performance and lifespan of SSD by increasing the hit ratio and decreasing the number of write operations compared to the existing schemes including LARC.

• Korean Journal of Food Science and Technology
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• v.48 no.5
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• pp.437-444
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• 2016

Rapid and reliable identification of microorganisms is important to maintain food quality and to control safety. MALDI-TOF MS-based identification methods are relatively fast and simple compared to other conventional methods including gram staining and biochemical characterization. A colony on subcultured media can be directly prepared on the analysis plate without further complex treatments. In this study, we confirmed the applicability of MALDI-TOF MS-based identification of foodborne pathogens such as Salmonella Enteritidis/Typhimurium, Staphylococcus aureus, Vibrio parahaemolyticus, Clostridium perfringens, Listeria monocytogenes, Yersinia enterocolitica, Bacillus cereus, Campylobacter jejuni, Campylobacter coli, and Cronobacter sakazakii on the Korea Food Standard Codex. MALDI-TOF MS data of the pathogenic reference strains were incorporated into a commercial MicroID (ASTA Inc.) database. Other pathogenic reference strains and seven isolates from various food samples were correctly identified to the species level by using the MicroID database. In conclusion, MALDI-TOF MS is comparable with commercial biochemical identification.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.6 s.58
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• pp.176-182
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• 2009

Other damage can occur due to the preexisting dull structure and installation of nonenvironmental-friendly concrete structure, lack of function for preventing coastal erosion. Increase of personal income and fast spread of the concept of waterfront casued the initiation of many project to improve aging coastal ports. However, none of environment-friendly structure has been developed and pre-existing solid block, igloo block, tunnel block are used commonly. In piers and lighter's wharf where the ships are mooring, resonance by the generation of a reflected wave caused by penetration wave in the port and port wave increases wave heights in the port and makes difficult to maintain the temperature, causes problems in mooring ships and cargo-working, and eventually increase the occurance of damages of the small ships by the collision. Therefore, development of new types of blcok is necessary. To apply Coastal Environments block developed for this reason, it requires allowable bearing capacity evaluation of shear key. For this study, we made test specimen for connecting part of C.E. Block, and conducted friction test of boundary surface. Data obtained by the experiment was analyzed by finite element analysis and assessed the coefficient of friction between C.E. Block and boundary surface.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.6
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• pp.706-714
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• 2012

The Korea Meteorological Administration provided the recent four-years records of weather dataset for our very short-term heavy rainfall prediction. We divided the dataset into three parts: train, validation and test set. Through feature selection, we select only important features among 72 features to avoid significant increase of solution space that arises when growing exponentially with the dimensionality. We used a differential evolution algorithm and two classifiers as the fitness function of evolutionary computation to select more accurate feature subset. One of the classifiers is Support Vector Machine (SVM) that shows high performance, and the other is k-Nearest Neighbor (k-NN) that is fast in general. The test results of SVM were more prominent than those of k-NN in our experiments. Also we processed the weather data using undersampling and normalization techniques. The test results of our differential evolution algorithm performed about five times better than those using all features and about 1.36 times better than those using a genetic algorithm, which is the best known. Running times when using a genetic algorithm were about twenty times longer than those when using a differential evolution algorithm.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.17-17
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• 2011

As a method of countermeasure to bed degradation and armoring phenomena of bed material in the downstream area of dam reservoirs, sediment augmentation (replenished sediment) has been carried out in many Japanese rivers. In general, bed of the replenished sediment site is composed of rocks, because the site is located in the downstream area of the dams and sediment supply is very small. Bed deformation process has been researched by many researchers. As a method of countermeasure to bed degradation and armoring phenomena of bed material in the downstream area of dam reservoirs, sediment augmentation (replenished sediment) has been carried out in many Japanese rivers. In general, bed of the replenished sediment site is composed of rocks, because the site is located in the downstream area of the dams and sediment supply is very small. Bed deformation process has been researched by many researchers. However, most of them can treat movable bed only and cannot be applied to the bed deformation process of sediment on rocks. If the friction angle between the sediment and the bed surface is assumed to be the same as the friction angle between the sediment and the sediment, sediment transport rate must be smaller without sediment deposition layer on the rocks. As a result, the reproduced bed geometry is affected very well. In this study, non-equilibrium transport process of non-cohesive sediment on rigid bed is introduced into the horizontal two dimensional bed deformation model and the model is applied to the erosion process of replenished sediment on rock in the Nakagawa, Japan. Here, the Japanese largest scale sediment augmentation has been performed in the Nakagawa. The results show that the amounts of the eroded sediment and the remained sediment reproduced by the developed numerical model are $56300m^3$ and $26800m^3$, respectively. On the other hand, the amounts of the eroded sediment and the remained sediment measured in the field after the floods are $56600m^3$ and $26500m^3$, respectively. The difference between the model and field data is very small. Furthermore, the bed geometry of the replenished sediment after the floods reproduced by the developed model has a good agreement with the measured bed geometry after the floods. These results indicate that the developed model is able to simulate the erosion process of replenished sediment on rocks very well. Furthermore, the erosion speed of the replenished sediment during the decreasing process of the water discharge is faster than that during the increasing process of the water discharge. The replenished sediment is eroded well, when the top of the replenished sediment is covered by the water. In general, water surface level is kept to be high during the decreasing process of the discharge during floods, because water surface level at the downstream end is high. Hence, it is considered that the high water surface level during the decreasing process of the water discharge affects on the fast erosion of the replenished sediment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.4
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• pp.772-780
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• 2008

K-means is one of the simplest unsupervised learning algorithms that solve the clustering problem. However K-means suffers the basic shortcoming: the number of clusters k has to be known in advance. In this paper, we propose extensions of X-means, which can estimate the number of clusters using Bayesian information criterion(BIC). We introduce two different versions of algorithm: modified X-means(MX-means) and generalized X-means(GX-means), which employ one full covariance matrix for one cluster and so can estimate the number of clusters efficiently without severe over-fitting which X-means suffers due to its spherical cluster assumption. The algorithms start with one cluster and try to split a cluster iteratively to maximize the BIC score. The former uses K-means algorithm to find a set of optimal clusters with current k, which makes it simple and fast. However it generates wrongly estimated centers when the clusters are overlapped. The latter uses EM algorithm to estimate the parameters and generates more stable clusters even when the clusters are overlapped. Experiments with synthetic data show that the purposed methods can provide a robust estimate of the number of clusters and cluster parameters compared to other existing top-down algorithms.

• Journal of the Geological Society of Korea
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• v.54 no.6
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• pp.631-640
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• 2018

To understand the formation and evolution of a sedimentary basin in basin analysis and modelling studies, it is important to analyze the thickness and age range of sedimentary layers infilling a basin. Because the compaction effect reduces the thickness of sedimentary layers during burial, basin modelling studies typically restore the reduced thickness using the relation of porosity and depth (compaction trend). Based on the compilation plots of published compaction trends of representative sedimentary rocks (sandstone, shale and carbonate), this study estimates the compaction trend ranges with exponential curves and equations. Numerical analysis of sedimentary compaction is performed to evaluate the variation of porosity and layer thickness with depth at key curves within the compaction trend ranges. In sandstone, initial porosity lies in a narrow range and decreases steadily with increasing depth, which results in relatively constant thickness variations. For shale, the porosity variation shows two phases which are fast reduction until ~2,000 m in depth and slow reduction at deeper burial, which corresponds to the thickness variation pattern of shale layers. Carbonate compaction is characterized by widely distributed porosity values, which results in highly varying layer thickness with depth. This numerical compaction analysis presents quantitatively the characteristics of porosity and layer thickness variation of each lithology, which influence on layer thickness reconstruction, subsidence and thermal effect analyses to understand the basin formation and evolution. This work demonstrates that the compaction trend is an important factor in basin modelling and underlines the need for appropriate application of porosity data to produce accurate analysis outcomes.

• Korean Journal of Social Welfare Studies
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• v.47 no.4
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• pp.333-360
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• 2016

Social Impact Bonds(SIBs) has emerged as a promising way to finance proven social services programs, fund what works, and drive government accountability and has increased fast. In this context, this study examines and classifies the structure of SIB focusing key criteria of the main steps through two-step cluster analysis. Analysis results are as follows. First, the main commissioners of SIB are the ministries of the central government. And in terms of the stage of invest, there are usually two or three investors mainly consisting of social finance organizations. Second, in terms of target and age of SIB beneficiaries, it focuses on the adolescent and youth. Third, in the outcome evaluation stage, the results show that in most cases outcome payments are determined by a validation of service provider or government administrative data. However, the rate of payments are based on the comparison of the program beneficiaries to other comparable groups is 23.8%. Finally, The results of two-step cluster analysis are as; 'mix of central government and social finance organization', 'multiple agent including private organization', and 'multiple social provider'. Among three types, 'multiple agent including private organization' shows the most active participation between agents and the most systematic outcome measurement and management. The results of this study imply that the importance of the method to manage and measure outcome in SIB structure. Moreover, the consist of commissioners or investors is needed to expanded more.

• Food Science and Preservation
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• v.12 no.4
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• pp.355-360
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• 2005

This study was carried out to research the use of tar colors in children's favorite foods such as candies, soft drinks, chewing gums, cereals, and ice bars in order to acquire basic data on food safety. The tar colors were simultaneously analyzed by high performance liquid chromatography (HPLC). The contents of tar colors in candies, soft drinks, gums, cereals, and ice bars were maximum 74.10 mg/100 g, 5.96 mg/100 g, 35.70 mg/100 g, 20.10 mg/100 g, and 4.93 mg/100 g, respectively. In addition, every tar colors except for Indigo carmine (B2) and Fast Green FCF (G3) among permitted tar colors were used in foods and more than two kinds of tar colors were used in most cases. From the results, only types of tar colors for foods were regulated, but the amount was not regulated.