• Journal of Environmental Impact Assessment
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• v.21 no.3
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• pp.461-468
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• 2012

In general, long-term changes of ecological factors take a pulse form in which they interact with other factors and go through a repeated increasing and decreasing cycle. The coupling of the two approaches the grid model and the box model in ecological modeling can lead to an in-depth understanding of the environment. The study analyzes temporal variations of major storages with an energy system model that formulizes effectively the relationships among nutrients, phytoplankton, and zooplankton in the Yellow Sea and the East China Sea. An increase of light intensity and standing stock of nutrient increase the magnitude and frequency of pulsing. Also, an immense reduction of nutrient concentration can cause extinction of the pulsing and bring about a steady state. It is concluded that the nutrient loads in freshwater discharge from the Yangtze affect the cycles of major ecological components as well as water quality variables and play an important role in the marine ecosystem.

• Journal of the Korean Operations Research and Management Science Society
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• v.27 no.2
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• pp.63-79
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• 2002

During the last decade many enterprises spent a huge amount of money for investment on Information Technology (IT) & Information System (IS) to attain competitive advantage and to maximize their business performance by satisfying the various requirements of customers. Under such circumstances, methodologies for evaluating IT impact on business performance are very important issues for strategic decision making on investment. In this study, we propose a performance evaluation model that adopts the concept of the Balanced Scorecard (BSC) and the Value Chain to analyze the financial impact and non-financial impact of IT & IS at each critical work area. This model combines the 4 evaluation areas from BSC and 6 critical work areas from Value Chain and measures the Key Performance Indicator (HPI) and the effect of KPI. Also, we present a case study of which the evaluation model has been conducted on a major manufacturing company. finally. we address some important notes to improve the IT & IS performances in the real-world.

• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.3
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• pp.62-73
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• 2003

The characteristics of constitutive equations, for hydrocodes, were Investigated by the comparison between the smoothed particle hydrodynamcis simulation and the experiment of rod impact test which resulted in a deformation history of impacting front where high strain and high strain rate dominate. The constitutive equations used in the simulation Is J-C(Johnson-Cook) model, Z-A(Zerilli-Armstrong) model, and S-C-G(Steinberg-Cochran-Guinan) model. The modification of Z-A model, based on the increased effect of strain-rate hardening, showed better correlation with expriment.

• Steel and Composite Structures
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• v.17 no.2
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• pp.159-172
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• 2014

A finite element model with the consideration of damage initiation and evolution has been developed for the analysis of the dynamic response of a composite sandwich panel subject to low velocity impact. Typical damage modes including fiber breakage, matrix crushing and cracking, delamination and core crushing are considered in this model. Strain-based Hashin failure criteria with stiffness degradation mechanism are used in predicting the initiation and evolution of intra-laminar damage modes by self-developed VUMAT subroutine. Zero-thickness cohesive elements are adopted along the interface regions between the facesheets and the foam core to simulate the initiation and propagation of delamination. A crushable foam core model with volumetric hardening rule is used to simulate the mechanical behavior of foam core material at the plastic state. The time history curves of contact force and the core collapse area are obtained. They all show a good correlation with the experimental data.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.55-58
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• 2005

This study was Performed to grasp of the problem and improvement in traffic noise environmental impact assessment(EIA). National institute of environmental research(NIER) traffic noise prediction model is in general use in internal EIA. In this study, NIER noise prediction model need to improve in that the predicted results lower than the measured results. The other predict model(KLC KEI) is more accurate. Also the volume and speed of traffic is need to standardize in traffic noise prediction.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.05a
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• pp.389-393
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• 1999

The exact model of impact ionization events in which has influence on device efficiency, is to be necessary element for device simulation. Recently, a modified Keldysh formula with two set of power exponent of 7.8 and 5.6 is used to simulate carrier transport. This model is, however, not suitable as impact ionization model in low energy range since this ignore direction dependent properties of impact ionization. The impact ionization rate is highly anisotropic at low energy, while it becomes isotropic at higher energy range. Note that impact ionization events frequently occur in high energy range. For calculating impart ionization rate, we use full energy band structure derived from Fermi's golden rule and empirical pseudopotential method. We compare with calculated and experimental value, and investigate direction dependent conduction energy band structure along the direction of <100>, <110> and <111>. We know that the threshold energy of impact ionization is anisotropic and impact ionization rate is very deviated from modified Keldish formula, in relatively low energy range.

• Journal of Korean Society of Forest Science
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• v.100 no.2
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• pp.218-225
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• 2011

The purpose of this study is to estimate the economic impacts of National Natural Recreation Forests using a regional input-output (I-O) model. Based on the regional I-O transactions tables developed by Bank of Korea (2009), National Natural Recreation Forests related sectional multipliers were derived with respect to output, income, employment, and value-added. Furthermore, surveys questioned National Natural Recreation Forests visitors in order to estimate per capita expenditures. The result shows that one National Natural Recreation Forests generated 3,380 million Won of output impact, 328 million Won of income impact, 1,017 million Won of value-added impact, and 22 full-time jobs within local effect, respectively. Also, one National Natural Recreation Forests generated 687 million Won of output impact, 85 million Won of income impact, 245 million Won of value-added impact, and 6 full-time jobs outside local effect, respectively.

• Journal of Environmental Impact Assessment
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• v.9 no.4
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• pp.277-290
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• 2000

The purpose of this study is to identify the problems of environmental impact assessment(EIA) and to suggest new EIA technology. The problems of EIA in Korea can be summarized as follows. First, the EIA does not reflect the impact of policy, plan and program on environment. Second, the project EIA does not consider the cumulative impacts such as additive impacts, synergistic impacts, threshold/saturation impacts, induced and indirect impacts, time-crowded impacts, and space-crowded impacts. Third, the EIA techniques in Korea are not standardized. Finally, the present EIA suggests only alternatives to reduce adverse impacts. To solve above-mentioned problems, the development of new EIA technology is essential. First, the new EIA technology should be developed toward pollution prevention technology and comprehensive and integrated environmental management technology. Second, new fields of EIA for pollution prevention contain strategic environmental assessment, cumulative impacts assessment, socio-economic impact assessment, cyber EIA and EIA technology necessary after the reunification of Korean Peninsula. Third, EIA technology for integrated environmental management contains the development of integated environment assessment system and the development of packaged EIA technology. The EIA technology for integrated environmental assessment system contains (1) development of integrated impact assessment technology combining air/water quality model, GIS and remote sensing, (2) integrated impact assessment of EIA, traffic impact assessment, population impact assessment and disaster impact assessment. (3) development of integrated technology combining risk assessment and EIA (4) development of integrated technology of life cycle assessment and EIA, (5) development of integrated technology of spatial planning and EIA, (6) EIA technology for biodiversity towards sustainable development, (7) mathematical model and GIS based location decision techniques, and (8) environmental monitoring and audit. Furthermore, there are some fields which need packaged EIA technology. In case of dam development, urban or industrial complex development, tourist development, landfill or combustion facilities construction, electric power plant development, development of port, road/rail/air port, is necessary the standardized and packaged EIA technology which considers the common characteristics of the same kind of development project.

• International Journal of Automotive Technology
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• v.4 no.1
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• pp.31-40
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• 2003

W-beam guardrail system has been the most popular roadside safety device around the world. Through large plastic deformation and corresponding energy dissipation, a W-beam guardrail system contains and re-directs out-of-control vehicles so as to reduce the impact damage on the vehicle occupants and the vehicles themselves. In this paper, our recent experiments on 1 : 3.75 downscaled W-beam and the beam-post system are reported. The static and impact test results on the load characteristics, the global response and the local cross-sectional distortion are reveled. The effects of three different end-boundary conditions for the beam-only testing are examined. It is found that the load characteristics are much dependent on the combined contribution of the local cross-sectional distortion and the end-supporting conditions. The energy Partitioning between the beam and the supporting Posts in the beam-Post-system testing were also examined. The results showed that the energy dissipation partitioning changed with the input impact energy. Finally, a simple mass-spring model is developed to assess the dynamic response of a W-beam guardrail system in response to an impact loading. The model's prediction agrees well with the experimental results.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.12
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• pp.657-664
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• 2020

We investigate the impact of roads and highways within the provinces on the regional trade of China using the augmented Gravity Model and theory of modeling trade. We take a panel data covering 31 provinces of China over 20 years period (1998-2017) for the estimations. We apply ARMA-OLS model, fixed and random effects, and robust findings by Hausman test. The results imply that road and highway lengths within the provinces have a significantly positive impact on the value of the province-wise exports. The positive impact is due to the fact the increased coverage of roads and highways increase accessibility to resources and mobility of goods and services within the regions. Moreover, employment in the transportation sector, per capita GDP and population of the provinces also illustrate positive and significant influence on regional exports and trade. The impact of China's WTO accession on regional exports has been positive, while the financial crisis has had a negative impact. The year dummies show that, in the years following the financial crisis, China was able to regress from the external shock as trade within the provinces increased. The increase in exports after financial crisis is mainly due to the government policies and support to every province.