• Journal of Korea Water Resources Association
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• v.47 no.11
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• pp.985-996
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• 2014

When designing hydraulic structures, the chosen method of time distribution in a hyetograph is highly significant. There are several methods used for measuring time distribution. In the case of Huff (1967), which is widely used in Korea, the Ministry of Construction and Transportation (MOCT, 2000), and the Ministry of Land, Transport and Maritime Affairs (MOLTMA, 2011) have long been increasing their use of this method. The MOLTMA uses the conventional Huff method's measurement of 1 inch (25.4 mm) as the threshold. Many researchers have pointed out that this method often leads to underestimation, because of the excessive flatness. Therefore, for this study, a new time distribution method was developed to analyze only extreme rainfall events-those over the standard of severe rainstorms (that is, more than 30 mm per hour or 80 mm per day)-and that was verified using a rainfall-runoff model and applying it to a real basin.

• Journal of Information Technology Services
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• v.14 no.3
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• pp.1-18
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• 2015

Recent trends of mobile convergence has already brought about many changes in our digitally-powered society. Especially, taking advantage of strengths of existing mobile devices and smart phones have already been established as a primary standard in the business intelligence world. Such high-powered digital devices equipped with mobile convergence functions are getting more momentum as app stores are prevailing. Basically, the app stores are administered by smart phone manufacturers, creating a new business ecosystem among app developers and end-users. However, there are paucity of studies tackling an issue about how users' repurchase intention of the apps is influenced by the service qualities of the app stores. In this respect, this study aims to investigate the effect of app store service quality on users' satisfaction and repurchase intention. As the value of loyal customers is incomparably high in app commerce, winning customers' loyalty is vital to the success of app stores. In this study, a customer is defined as one who has purchased goods or services at least once from the app stores. The proposed research model includes a number of constructs such as app perceptions, customer service, perceived ease of use, design, promotion, perceived consumer risk and connectivity. Empirical results revealed that perceived consumer risk has a negative relationship with consumer's perceived repurchase intention. All the other variables-app perceptions, customer service, perceived ease of use, design, promotion, connectivity- are found to be positively related with the repurchase intentions.

• Analytical Science and Technology
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• v.16 no.3
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• pp.226-231
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• 2003

We analyzed the concentrations of heavy metals associated airbone particles by using AAS made by both a domestic manufacturer and one of the foreign manufacturer. One model developed by a domestic manufacture showed excellent results in the selected wavelength with an excellent performance of a monochromator. It abandons a big drop except a fine drop to improve reproduction in atomizer, so that no remains should leave. Using the low pass filter we were able to reduce a noise of detection signal. The performance of our equipment was found to be highly compatible with that of a foreign company as we achieved the detection limit of about $0.015{\mu}g/L$ using a standard solution of Au. The PM samples had been collected from by main observation points in 7 areas of Seoul city from 2001 to the spring in 2002. with these PM sample we analyzed the concentrations of Pb, Cu, Mn, Cd, Ni, Fe, Cr, Co, Mg and Al.

• Journal of KIISE:Computing Practices and Letters
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• v.8 no.5
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• pp.510-519
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• 2002

The OpenGIS Consortium has proposed a new web-mapping technology to support interoperability in web GIS environment by developing the specifications of MapServer and GML. In this environment, the MapServer transforms legacy spatial data into GML data, and clients display them on standard web browsers. This web-mapping testbed proposes methods for discovering, accessing, integrating and displaying GIS information except processing of spatial operations which are essential services in GIS environment. This paper proposes the method for executing spatial operations on GML data which are overlays of different map layers in legacy data servers. To support spatial operations on GML data in web GIS environment, this paper designs and implements GDOM based on the W3C's DOM Specifications and OGC's Simple Features Specifications. This paper shows the specifications and implementation of GDOM and the process of spatial operations in web-mapping testbed environment.

• Nuclear Engineering and Technology
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• v.39 no.3
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• pp.215-220
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• 2007

The existing flooding Probabilistic Safety Analysis(PSA) was updated to reflect the Korean plant specific operating experience data into the flooding frequency to improve the PSA quality. Both the Nuclear Power Experience(NPE) database and the Korea Nuclear Pipe Failure Database(NuPIPE) databases were used in this study, and from these databases, only the Pressurized Water Reactor(PWR) data were used for the flooding frequencies of the flooding areas in the primary auxiliary building. With these databases and a Bayesian method, the flooding frequencies for the flooding areas were estimated. Subsequently, the Core Damage Frequency(CDF) for the flooding PSA of the Ulchin(UCN) unit 3 and 4 plants based on the Korean Standard Nuclear Power Plant(KSNP) internal full-power PSA model was recalculated. The evaluation results showed that sixteen flooding events are potentially significant according to the screening criterion, while there were two flooding events exceeding the screening criterion of the existing UCN 3 and 4 flooding PSA. The result was compared with two kinds of cases: (1) the flooding frequency and CDF from the method of the existing flooding PSA with the PWR and Boiled Water Reactor(BWR) data of the NPE database and the Maximum Likelihood Estimate(MLE) method and (2) the flooding frequency and CDF with the NPE database(PWR and BWR data), NuPIPE database, and a Bayesian method. From the comparison, a difference in CDF results was revealed more clearly between the CDF from this study and case (2) than between case (1) and case (2). That is, the number of flooding events exceeding the screen criterion further increased when only the PWR data were used for the primary auxiliary building than when the Korean specific data were used.

• Nuclear Engineering and Technology
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• v.43 no.6
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• pp.583-592
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• 2011

The radiological characteristics for waste classification were assessed for neutron-activated decommissioning wastes from a CANDU reactor. The MCNP/ORIGEN2 code system was used for the source term analysis. The neutron flux and activation cross-section library for each structural component generated by MCNP simulation were used in the radionuclide buildup calculation in ORIGEN2. The specific activities of the relevant radionuclides in the activated metal waste were compared with the specified limits of the specific activities listed in the Korean standard and 10 CFR 61. The time-average full-core model of Wolsong Unit 1 was used as the neutron source for activation of in-core and ex-core structural components. The approximated levels of the neutron flux and cross-section, irradiated fuel composition, and a geometry simplification revealing good reliability in a previous study were used in the source term calculation as well. The results revealed the radioactivity, decay heat, hazard index, mass, and solid volume for the activated decommissioning waste to be $1.04{\times}10^{16}$ Bq, $2.09{\times}10^3$ W, $5.31{\times}10^{14}\;m^3$-water, $4.69{\times}10^5$ kg, and $7.38{\times}10^1\;m^3$, respectively. According to both Korean and US standards, the activated waste of the pressure tubes, calandria tubes, reactivity devices, and reactivity device supporters was greater than Class C, which should be disposed of in a deep geological disposal repository, whereas the side structural components were classified as low- and intermediate-level waste, which can be disposed of in a land disposal repository. Finally, this study confirmed that, regardless of the cooling time of the waste, 15% of the decommissioning waste cannot be disposed of in a land disposal repository. It is expected that the source terms and waste classification evaluated through this study can be widely used to establish a decommissioning/disposal strategy and fuel cycle analysis for CANDU reactors.

• Journal of Welding and Joining
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• v.27 no.6
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• pp.31-35
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• 2009

When conducting CTOD test, especially in thick welded steel plate, fatigue pre-cracking occasionally failed to satisfy the requirements of standards thus making the test result invalid. Internally accumulated residual stress of test piece has been thought as one of the main reasons. The propagation of fatigue crack, started from the tip of machined notch, which might have propagated irregularly due to residual stress field. To overcome this kind of difficulty three methods to modify the residual stress are suggested in standard i.e. local compression, reverse bending and stepwise high-R ratio method. In this paper not only multi pass welding but also local pre-compressing process of thick steel plate has been simulated using finite element method for clarifying variation of internal welding residual stress. The simulated results show that welding residual stress is compressive in the middle section of the model and it is predominantly increased after machining the specimen. Comparing as-welded state all component of the welding residual stress changing to compressive in the tip of machine notch whereas residual stress of the outer area remain as tensile condition relatively. Analysis results also show that this irregular residual stress distribution is improved to be more uniformly by applying local compression.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.4718-4725
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• 2011

Intake-air flow and distribution characteristics of the 1600cc gasoline engine intake manifold have been studied using the computer simulation. Simulation has been conducted using both one-dimensional performance simulation and three-dimensional CFD software. Steady state flow simulation result of the intake manifold shows good distribution characteristics that the standard deviation of flow coefficients is below 1.0 percentage for both one- and three-dimensional simulation. Even though one-dimensional simulation result slightly overestimates compared with three-dimensional simulation result, both results show very good agreement in flow coefficient trend. Also, unsteady state simulation result shows consistent distribution characteristics with that of steady state. It is shown that unsteady state distribution characteristics might be able to be predicted through the steady state mass distribution result.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.2567-2572
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• 2014

In the present study, we aimed to obtain multi jig that PCB sheet with several PCB component can cut in a short time as to the Separation of PCB component. PCB supporter designed safely at the base frame and each model can be separable. it completed the neodium magnet for the fixing of the upper part laser transmission hole of the both. One of the development, the cutting working with one base frame which PCB component of various standard, fixing of module and bridge connected to PCB component could be possible. and it reduced the inconvenience which has to replace the base frame and PCB sheet fixed member. It compared to other press up about 70% of accuracy and a reduction in investment cost was about 400%.

• Journal of Information Management
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• v.35 no.4
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• pp.81-105
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• 2004

In this study, the way of the automatic text categorization on web-based query was implemented. X2 methods based on the Supported Vector Machine were used to test the efficiency of text categorization on queries. This test is carried out by the model using the Synonymy List. 713 synonyms were extracted manually from the tested documents. As the result of this test, the precision ratio and the recall ratio were decreased by -0.01% and by 8.53%, respectively whether the synonyms were assigned or not. It also shows that the Value of F1 Measure was increased by 4.58%. The standard deviation between the recall and precision ratio was improve by 18.39%.