• Journal of Korea Water Resources Association
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• v.51 no.8
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• pp.677-686
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• 2018

There remain numerous ungauged watersheds in Korea owing to limited spatial and temporal streamflow data with which to estimate hydrological model parameters. To deal with this problem, various regionalization approaches have been proposed over the last several decades. However, the results of the regionalization models differ according to climatic conditions and regional physical characteristics, and the results of the regionalization models in previous studies are generally inconclusive. Thus, to improve the performance of the regionalization methods, this study attaches hydrological model parameters obtained using a spatial proximity model to the explanatory variables of a regional regression model and defines it as a hybrid regionalization model (hybrid model). The performance results of the hybrid model are compared with those of existing methods for 37 test watersheds in South Korea. The GR4J model parameters in the gauged watersheds are estimated using a shuffled complex evolution algorithm. The variation inflation factor is used to consider the multicollinearity of watershed characteristics, and then stepwise regression is performed to select the optimum explanatory variables for the regression model. Analysis of the results reveals that the highest modeling accuracy is achieved using the hybrid model on RMSE overall the test watersheds. Consequently, it can be concluded that the hybrid model can be used as an alternative approach for modeling ungauged watersheds.

• Korean Journal of Medicinal Crop Science
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• v.8 no.3
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• pp.266-273
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• 2000

The optimal conditions of PCR components for the random amplification of genomic DNA were $20\;ng/20{\mu}l$ in template DNAs, 250 mM in dNTP, 10 pM in primer $1.0unit/20{\mu}l$ in Taq DNA polymerase respectively with the annealing temperature at $36^{\circ}C$, respectively. Twelve local lines were divided into 3 groups by the coefficients of 107 polymophic bands by Jaccard and Nei. The coefficients value of group I including Chongup # 1, Seochon # 1, Andong # 1, Chinan # 1, and Danyang # 1 ranged from 0.27 to 0.05 and those of group II including Suwon # 2, Chunchon # 1, Japan # 3, Danyang#2 and $F_1$ (Variety Jihwang $1{\times}$ Seohchon) ranged from 0.29 to 0.11. While, Jihwang 1 originated from China and Japan # 1 in group III showed a distant genetic relationship to Korean local lines.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.6
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• pp.252-255
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• 2014

Indium tin oxide (ITO) films with various oxygen partial pressure from 0 to $6{\times}10^{-5}$ Pa were prepared onto polyethylene terephthalate (PET) using RF magnetron sputtering at room temperature. The structural, electrical and optical properties of the grown ITO films were investigated as a function of the oxygen partial pressure. The amorphous nature of the ITO films was dominant at the partial pressure below $1{\times}10^{-5}$ Pa and the degree of crystallinity increased as the oxygen concentration increased further. This structural change comes with the increased carrier concentration and reduction of the electrical resistivity down to $9.8{\times}10^{-4}{\Omega}{\cdot}cm$. The average transmittance (at 400~800 nm) of the ITO deposited on the PET substrates increased as the oxygen partial pressure increased and transmittance above 80 % was achieved with the partial pressure of $4{\times}10^{-5}$ Pa. The results show that the choice of optimal oxygen partial pressure can present improved film crystallinity, the increased carrier concentration, and the enhancement in the electrical conductivity.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.2
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• pp.1-12
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• 2017

The Seoul metropolitan transportation card's high value lies in its recording of total population movements of the public transit system. In case of recorded information on transit by bus, even though route information utilized by each passenger is accurate, the lack of passenger transfer information of the urban railway makes it difficult to estimate correct routes taken by each passenger. Therefore, pinpointing passenger path selection patterns arising in the metropolitan railway network and using this as part of a path movement estimation model is essential. This research seeks to determine that features of passenger movement routes in the urban railway system is comprised of M-similar routes with increasing number of transfer reflected as additional costs. In order to construct the path finding conditions, an M-similar route searching method is proposed, embedded with non additive path cost which appears through inclusion of the stepwise transportation parameter. As well, sensitivity of the M-similar route method based on transportation card records is evaluated and a stochastic trip assignment model using M-similar path finding is constructed. From these, link trip and transfer trip results between lines of the Seoul metropolitan railway are presented.

• Management & Information Systems Review
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• v.35 no.3
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• pp.231-247
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• 2016

This study, according to the amendment of the Act on External Audit, on the basis of the number of input auditors, the content of auditing, and audit times as additional informations, calculates the average of the samples listed companies with assets of one hundred billion KRW. However, since the actual number of the subject corporations of which asset is 100 billion KRW is small, it is difficult to extract data with reference to this asset size. Therefore, the samples were extended to 50 corporations of which asset is 10% less than 100 billion KRW and other 50 more corporations of which asset is 10% more than 100 billion KRW. As a result, a total of 100 corporations were included as samples. To calculate the average of the audit times, a t-test was performed between the two groups. The result of the t-test showed that there is not a significant difference between the two groups. According to the analytical results of the t-test, the average of the number of input auditors and the average of audit times were calculated with respect to all the 100 samples. A further analysis showed that the average of audit content in the present study was compared with the estimated values in the study of Mun (2016). Although the results of this study may not be the optimal number, they may be used as a fundamental index which may be compared with the audit times and the audit fees in the current audit market where there is not an available reference. In addition, the amendment of the Act on External Audit may enhance the independence of auditors and the transparency of accounting system when compared with the previous system where only the total audit times were disclosed.

• Geophysics and Geophysical Exploration
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• v.18 no.3
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• pp.154-161
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• 2015

For efficiently designing neutron induced gamma spectroscopy sonde, Monte Carlo simulation is employed to understand a dominant location of thermal neutron and classify the formation elements from the energy peak of capture gamma spectrum. A pulsed neutron generator emitting 14 MeV neutron particles was used as a source, and flux of thermal neutron was calculated from the twelve detectors arranged at each 10 cm intervals from the source. Design for reducing borehole effects using shielding materials was also applied to numerical sonde model. Moreover, principal elements and quantities of numerical earth models were verified through the energy spectrum analysis of capture gamma detected from a gamma detector. These results can help to enhance the signal-to-noise ratio, and determine an optimal placement of capture gamma detectors of neutron induced gamma spectroscopy sonde.

• Journal of the Korea Concrete Institute
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• v.21 no.6
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• pp.705-712
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• 2009

HPFRCCs (high-performance fiber reinforced cementitious composites), which is relatively more ductile and has the characteristic of high toughness with high fiber volume fractions, can be used in structures subjected to extreme loads and exposed to durability problems. In the case of PVA (polyvinyl alcohol) fiber, it is noted by former studies that around 2% fiber volume fractions contributes to the most effective performance at HPFRCCs. In this study, flexural tests were carried out to evaluate the flexural behavior of HPFRCCs and to optimize mix proportions. Two sets of hybrid fiber reinforced high performance specimens with total fiber volume fraction of 2 % were tested: the first set prepared by addition of short and long PVA fibers at different combination of fiber volume fractions, and the second set by addition of steel. In addition, in order to assess the performances of the HPFRCCs against to high strain rates, drop weight tests were conducted. Lastly, the sprayed FRP was applied on the bottom surface of specimens to compare their impact responses with non-reinforcing specimens. The experimental results showed that the specimen prepared with 1.6% short fibers (REC 15) and 0.4% long fiber (RF4000) outperformed the other specimens under flexure, and impact loading.

• Journal of the Korea Concrete Institute
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• v.26 no.3
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• pp.277-285
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• 2014

The purpose of this study is to investigate experimentally the variation factors range having influence on the rheological properties of the combined self-compacting concrete according to materials quality, weighting error and site conditions. Two types cement (blast-furnace slag cement and belite cement), lime stone powder as binder and the optimum mix proportions in the preceded study are selected for this study. Also, variations for sensitivity test are as followings; (1) Concrete temperature 3 cases (2) Surface moisture of sand 5cases (3) Fineness modulus of sand 5cases (4) Specific surface of lime stone powder 3cases (5) Dosage of chemical admixture 5cases. Slump flow ($650{\pm}50mm$), 500 mm reaching time (($7{\pm}3sec$), V-type flowing time ($15{\pm}5sec$) and U-box height (min. 300 mm) are tested for sensitivity. As test results, the variations range for quality control are as followings. (1) Concrete temperature; $10{\sim}20^{\circ}C$(below $30^{\circ}C$) (2) Surface moisture of sand; $base{\pm}0.6%$ (3) Fineness modulus of sand; $2.6{\pm}0.2$ (4) Dosage of chemical admixture; $base{\pm}0.2%$ (5) Specific surface of lime stone powder $6000cm^2/g$. Compared with two types cement including based belite cement (binary type) and based slag cement (ternary type), the combined self-compacting concrete used belite cement type is most stable in the quality control because of high contents for lime stone powder and $C_2S$. It is to propose a control scheme of the combined self-compacting concrete in the actual construction work.

• Korean Journal of Construction Engineering and Management
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• v.14 no.1
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• pp.82-90
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• 2013

In the construction industry, there are so many qualitative factors affecting the performance of a project. So it is crucial to measure the factors in an effective way in order to analyze the interrelationship among the various factors. To improve the performance level of a project, it is also important to identify the most appropriate management practices which are inter-linked with the subject project. The purpose of this study is to develop a project performance management system (PPMS) to quantitatively analyze the variety of project performance data and identify the best management practice to increase the potential level of a particular performance area. Using a comparative statistical method, this study developed a quantification method and web-based computerized system to enhance the usage of the system. The system, however, is still under the validation stage because of the shortage of data set. In the future, when more and more completed project data are stored in the system, the system would play a crucial role in predicting the performance level and matching the best management practice for a subject project. In addition, the system can also be modified as a tool for a business- or industry-level system by incorporating the existing enterprise resource programs.

• Journal of the Korean Society of Food Science and Nutrition
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• v.25 no.6
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• pp.1080-1086
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• 1996

Monascus strains were isolated from Ang-Khak for the screening of antimicrobial activity. Two Monascus isolates, No.116 and No.481, were selected because they showed strong antimicrobial activity. Effect of various nutrients and incubation conditions on antimicrobial activity were different between two isolates. Strong antimicrobial activity of isolate No.116 was observed in the medium with 8% sucrose and $0.8%(NH_4)_2SO_4,$ 0.5% $KH_2PO_4and$ 0.5% $MgSO_4,$ while isolate No.481 required 8% sucrose, 1.6~2% $(NH_4)_2SO_4,$ 0.5% $MgSO_4and$ 0.5% $FeSO_4for$ the highest activity. The strong antimicroial activity was observed when both isolates were incubated on rice extract broth with initial pH of 5.3. The optiimum incubation temperature for the highest antimicrobial activity was $32.5^{\circ}C.$ With optimal conditions for the highest antimicrobial activity, isolate No.116 and No. 481 were both active for 51 hours or longer against test organisms Bacillus subtilis, Staphylococcus aureus, Listeria monocytogenes, and Enterococcus faecium.