• Fire Science and Engineering
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• v.32 no.2
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• pp.7-16
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• 2018

In this study, the previous design fire curve for fire simulation was modified and re-suggested. Numerical simulations with the FDS and CFAST were performed for the n-heptane and n-octane pool fires in the ISO 9705 compartment to evaluate the prediction performances of the previous 1-stage and modified 2-stage design fire curves. The numerical results were compared with the experimental temperature and concentrations of $O_2$ and $CO_2$. The FDS and CFAST simulations with the 2-stage design fire curve showed better prediction performance for the variation of temperature and major species concentration than the simulations with 1-stage design fire curve. Especially, the simulations with the 2-stage design fire curve agreed with the experimental temperature more reasonably than the results with the 1-stage design fire curve. The FDS and CFAST simulations showed good prediction performance for the temperature in the upper layer of compartment and the results with the FDS and CFAST were similar to each other. However, the FDS and CFAST showed poor and different prediction performance for the temperature in the lower layer of compartment.

• Ecology and Resilient Infrastructure
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• v.4 no.3
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• pp.130-141
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• 2017

We evaluated the field application feasibility that biologically derived substances (Naphthoquinone derivate: NQ 2-0) can be used for the eco-friendly mitigation of natural harmful cyanobacterial blooms in freshwater. We conducted a 30 ton scale mesocosm experiment to investigate the effects of NQ 2-0 on biotic and abiotic factors in water collected from Gi-heung reservoir. In the mesocosm experiments, the abundance of Microcystis sp. was continuously increased in the control. However, the Microcystis sp. cell density was sharply decreased on the $10^{th}$ day. In the treatment, NQ 2-0 showed the strong and selective algicidal activity toward the target cyanobacteria (Microcystis sp.). Accordingly, the algicidal activity of NQ 2-0 compound increased gradually until $10^{th}$, $15^{th}$ days and algal biomass was decreased to 99.4 and 100 %, respectively. NQ 2-0 compound was not only selective algicidal activity but also the growth of other phytoplankton and increased the Shannon-Wiener diversity index of phytoplankton. In the mesocosm experiments, the dynamics of biotic (bacteria, heterotrophic nanoflagellate, ciliates, zooplankton) and abiotic (water temperature, dissolved oxygen, pH, conductivity, nutrients) factors remained unaffected. These results suggest that NQ 2-0 could be a selective and ecologically safe algicide to mitigate harmful cyanobacterial blooms. In addition, it is believed that NQ 2-0 will play a major role in forming a healthy aquatic ecosystem by facilitating habitat and food supply of aquatic organisms.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.12
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• pp.7438-7442
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• 2014

An assessment of flocculation was performed by measuring the distribution of the floc size during sedimentation in water works. The size and number of flocs have a greater effect on an evaluation of the efficiency of flocculation rather than the turbidity. The data was collected in situ using particle image velocimetry and image analysis. The measurements were carried out at a water depth of 1m. The removal efficiency of the total organic compounds, UV absorbance and turbidity depended on the size and floc size distribution in flocculation as the G value. The G value of 50 sec-1, 30 sec-1 and 10 sec-1 showed the highest degree of efficiency in the case of an inlet water turbidity of 5 NTU, and the highest degree of efficiency was observed at a G value of 65 sec-1, 40 sec-1 and 10 sec-1 when the inlet water turbidity was 263 NTU. The number of flocs with a distribution of above $1,200{\mu}m$ was 14. The dynamics between two important growth mechanisms were investigated as the energy input changed. This is a certain method that makes use of the size and number of flocs as an efficiency assessment.

• Journal of Technology Innovation
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• v.17 no.1
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• pp.119-148
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• 2009

The paper presents and empirically tests a model of the digital contents(DC) innovation systems that enables us to study interactions between users, service providers, contents developers and network providers, and to examine the relationship between manufacturing innovation and service innovation as well as patterns of innovation in the DC industry. The framework of Gallouj and Weinstein(1997) and Gallouj(2002) is modified into the DC innovation model according to characteristics of the DC industry, that is, user involvement and network externalities. The model is applied to a case analysis that traces the growth of the online game industry in Korea since its introduction. The model offers several advantages over other approaches in understanding the dynamics in the DC industry. Most importantly, it provides a single unified basis within which both service innovation resulting from users and service providers and manufacturing innovation induced by contents developers, platform holders and network providers are analyzed. The distinction between service and manufacturing innovation is important in many ways, for instance in selecting proper government policy tools for promotion or regulation of the DC industry. Second, the Korean online game industry has experienced both radical innovation during the beginning period and non-radical innovation throughout the maturation period. The model developed herein helps to illustrate several types of non-radical innovations such as recombinative innovation that are crucial to sustainable development of the DC industry. Third, the model clarifies impacts of network externalities that are characteristics of the DC industry.

• Korean Journal of Environment and Ecology
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• v.28 no.4
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• pp.385-392
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• 2014

Quercus gilva Blume is an evergreen-leaved tree that belongs to Facaceae and grows in tropical and warm-temperate regions, such as Japan, Taiwan, China and Korea. This study was carried out to analyze the distribution and growth characteristics of Q. gilva in the native range. In Korea, this species was distributed in Jeju Island between 80 and 350 meter above sea level, and mainly in the south-western regions of the island from 100 to 200 meter above sea level. The average height of Q. gilva was $9.8{\pm}1.9$ meter, with most trees 9 and 12 meter tall. The average diameter at breast height was $22.6{\pm}6.8$ centimeter, with the majority between 20 and 30 centimeter. Several coppice shoots ($3.8{\pm}2.1$ pieces) were formed from stumps and inferred by frequent cuttings for use. Almost Q. gilva individuals(96.2%) were covered with kinds of vines(18 species), and evergreen Trachelospermim asiaticum (Siebold et Zucc.) Nakai was major species. The analysis of damage of vines revealed that the most dead branches were found with 9 to 12 meter height of Q. gilva, and the more vines attached, the larger damage to Q. gilva individuals. A continuous monitoring and investigation would be required to preserve this species in their habitats.

• KDI Journal of Economic Policy
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• v.12 no.4
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• pp.3-20
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• 1990

The multisector model is designed to analyze and forecast structural change in industrial output, employment, capital and relative price as well as macroeconomic change in aggregate income, interest rate, etc. This model has 25 industrial sectors, containing about 1,300 equations. Therefore, this model is characterized by detailed structural disaggregation at the sectoral level. Individual industries are based on many of the economic relationships in the model. This is what distinguishes a multisector model from a macroeconomic model. Each industry is a behavioral agent in the model for industrial investment, employment, prices, wages, and intermediate demand. The strength of the model lies in the simulating the interactions between different industries. The result of its simulation will be introduced in the next paper. In this paper, we only introduce the structure of the multisector model and the coefficients of the equations. The multisector model is a dynamic model-that is, it solves year by year into the future using its own solutions for earlier years. The development of a dynamic, year-by-year solution allows us to combine the change in structure with a consideration of the dynamic adjustment required. These dynamics have obvious advantages in the use of the multisector model for industrial planning. The multisector model is a medium-term and long-term model. Whereas a short-term model can taken the labor supply and capital stock as given, a long-term model must acknowledge that these are determined endogenously. Changes in the medium-term can be analyzed in the context of long-term structural changes. The structure of this model can be summarized as follow. The difference in domestic and world prices affects industrial structure and the pattern of international trade; domestic output and factor price affect factor demand; factor demand and factor price affect industrial income; industrial income and relative price affect industrial consumption. Technical progress, as measured in terms of total factor productivity and relative price affect input-output coefficients; input-output coefficients and relative price determine the industrial input cost; input cost and import price determine domestic price. The differences in productivity and wage growth among different industries affect the relative price.

• Journal of the Korean Geographical Society
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• v.47 no.2
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• pp.193-207
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• 2012

This study discussed characteristics of Shindu Coastal Dune as habitat, and relationship between geodiversity and biodiversity. It was identified spatio-temporal variation of incoming nutrients depended on geomorphic differences of foredunes. The main incoming path of nutrients into coastal dune was considered as influx with movement of wind blown sands from the beach and tidal f lat. Concentrations of Na, Mg, K, Ca, and P in blown sands were compared. Concentrations of Na, Mg, and K showed high and irregular pattern in favorable condition of influx of blown sand. So these nutrients were related with geomorphic characteristics of foredunes. However, Na was also influenced by other factor such as salt spray. P was independent from effects of sea water and blown sands. In the case of Ca, a large coastal dune system rather than localized forms of foredunes made differences in the variation. Due to differences in spatio-temporal variation of nutrients, patterns of major vegetation could be inferred to appear differently. This study shows geomorphic dynamics of coastal dunes as habitat, and will provide information for coastal dune management and for understanding biological distribution and growth pattern in coastal dune.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.20 no.4
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• pp.199-205
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• 2015

Nitrogen and phosphorus are the limiting elements for growth of phytoplankton, which is a major primary producer of marine ecosystem. Incidentally the stoichiometry of N/P of ocean waters, measured by the (nitrate + nitrite)/phosphate ratio converges to a constant of 16. This characteristic ratio has been used widely for the understanding the ecosystem dynamics and biogeochemical cycles in the ocean. In the East Sea, several key papers were issued in recent years regarding the climate change and its impact on ecosystem dynamic and biogeochemical cycles using N/P ratio because the East Sea is a "miniature ocean" having her own meridional overturning circulation with the appropriate responding time and excellent accessibility. However, cited N/P values are different by authors that we tried to propose a single representative value by reanalyzing the historical nutrient data. We present N/P of the East Sea as $12.7{\pm}0.1$ for the year 2000. The ratio reveals a remarkable consistency for waters exceeding 300m depth (below the seasonal thermocline). We recommend to use this value in the future studies and hope to minimize confusion for understanding ecosystem response and biogeochemical cycles in relation to future climate change until new N/P value is established from future studies.

• Korean Journal of Ecology and Environment
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• v.35 no.1 s.97
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• pp.1-9
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• 2002

In order to understand the relationship between succession of phytoplankton community structure and inorganic nutrients and particulate organic matters, a one station in Kyungan stream in Korea during the dry season was chosen. Water samplings were carried out once a week from 18 August to 13 November 1993. The DIN concentration distributed always abundantly, however, phosphate and silicate gradually reduced during the period. Phytoplankton community had a peak chlorophyll a concentration of $90.6\;{\mu}g/l$ in late summer (21 August 1993) and a second peak of $29.7\;{\mu}g/l$ in autumn (2 October 1993). After then late autumn was characterined by relatively low chlorophyll a concentration of $15{\sim}16\;{\mu}g/l$. Seasonal fluctuation of chlorophyll a concentrations were correlated with measured POC and PON concentrations: phytoplankton blooming may be a major factor controlling POC and PON concentrations in this ecosystem. Phosphate plays an most important role as a limiting factor of phytoplankton growth. However, when Si/P ratio low, silicate may be a more critical limiting factor than phosphate. Shifts of P-limitation to Si- limitation the succession of dominant phytoplankton can in duce: diatom to cyanobacteria such as Anabaena, Microcystis and Oscillatoria.

• Korean Journal of Environmental Biology
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• v.31 no.3
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• pp.213-224
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• 2013

Between May 2006 and November 2009, we investigated the relationship between fluctuations in environmental factors and phytoplankton communities in Saemangeum Artificial Lake, South Korea. Nutrient concentrations in the lake increased because of the inflow of water from Mankyung and Dongjin Rivers during the summer rainy season; in particular, high concentrations were detected at an inner zone close to the estuaries. During the summer rainy season, salinity at the inner zone reduced more rapidly than that at the other zones, and it was similar to the changes in nutrient concentrations. Variations in phytoplankton communities were caused by fluctuations in environmental factors: the abundance of phytoplankton at the inner zone was higher than that at the other zones. Diatoms were the dominant species in the phytoplankton communities. A small centric diatom, Skeletonema costatum like species, was predominant, with a mean abundance of 19.5% in Saemangeum lake. Because of accelerated eutrophication in the lake, phytoplankton abundance increased continuously and the total number of species present in the community decreased. In particular, some dinoflagellates could intermittently cause red tides during low temperature and salinity conditions (at the inner zone). In 2006~2007, a red tide-forming dinoflagellate, Prorocentrum minimum, was the predominant species, while Heterocapsa triquetra, Karlodinium veneficum, and Heterocapsa rotundata were the newly recorded species in late 2008 to early 2009. Therefore, the dynamics of phytoplankton communities under the perennially eutrophic conditions in Saemangeum lake appear to be primarily affected by changes in water temperature and salinity. In particular, the growth of harmful algae may have been accelerated by the low salinity and temperature conditions during the spring season at the inner zone.