• Journal of The Korean Association For Science Education
• /
• v.30 no.4
• /
• pp.498-518
• /
• 2010

This study analyzed the characteristics of organization scheme and the levels of core concepts in science textbooks used in Korea, Singapore, and Taiwan, which have shown superior achievement according to the TIMSS 2007. Science textbooks in Korea clearly divide the fields of Energy, Matter, Biology, and Earth, presenting the fields in nearly equal proportion in each grade. In the case of Singapore, science textbooks take an integrated content approach, combining concepts from several fields under a single theme. Science textbooks in Taiwan present a single content field in each unit. Also, because each grade engages in a specific field intensively, there are many cases in which concepts related to a single field are studied in a single grade. In view of levels of core concepts, Singapore or Taiwan showed higher achievement than Korea in themes of 'Cell and their Functions', 'Ecosystems', and 'Human Health' under the TIMSS 2007 biology field. Singapore introduces core concepts for these themes in lower grades compared to Korea and presents them repeatedly in several grades. In Taiwan, there are many cases in which these core concepts are taught only once during the course of $3^{rd}$ to $8^{th}$ grade, but the explanations are presented at a level that is suitable to TIMSS 2007 assessment objectives. Considering the results of this analysis, there is a need to reconsider the division of content fields and methods of presenting core concepts in the science textbooks of Korea.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.2 no.1
• /
• pp.102-112
• /
• 1999

The purpose of this study is to evaluate the effects of design criteria and environmental conditions of the site of created tidal flats on the structure and function of man-made ecosystem. Seven constructed tidal flats and three natural tidal flats were studied taking the difference in the location (wave height and tidal current), inflow of river water, slope of tidal flat and age after the construction completed into consideration. Parameters studied were physico-chemical and biological characteristics of soils and rate of respiration. The natural tidal flats had higher contents of silt, nitrogen and organic matter compared with the constructed ones. The natural ones had reductive zone below 2cm, whereas the constructed ones had aerobic zone from the surface to below 20cm. The bacterial population in the soil of the constructed tidal flats was one to two orders of magnitude lower than that in the natural ones. Both biomass of macrobenthos and microbial respiration rate, however, were not different significantly between the natural and the constructed tidal flats. There was an exceptional constructed tidal flat with similar physico-chemical and biological characteristics to the natural ones. It is most probable that sufficient conditions to have similar tidal flats to natural ones are the location in enclosed bay or calm coastal area. Thus, to make man-made tidal flats with the same characteristics as those in natural ones, man-made tidal flats should be designed and/or located to enhance the accumulation of silt on tidal flat. It is important to select a place having low water motion for construction of tidal flat.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.26 no.6
• /
• pp.689-697
• /
• 2020

Hazardous and noxious substances (HNS) may cause maritime incidents during marine transportation, which are liable to lead to a large amount of spillage or discharge into the sea. The damage to the marine environment caused by the HNS spill or discharge is known to be much greater than the damage caused by oil spill. Particularly dangerous is HNS, which is deposited or buried in the seabed, as it can damage the organisms that live on, in, and near the bottom of the sea, the so-called "benthos," forming the benthic ecosystem. Therefore, it is vital that the HNS deposited on the seabed be recovered. In order to do so, procedures and equipment are required for accurate detection, stabilization treatment, and recovery of HNS in subsea sediment. Thus, when developing a mechanical recovery system, the performance requirements should be selected using performance indices, and the conceptual design of the mechanical recovery system should be based on performance requirements decided upon and selected in advance. Therefore, this study was conducted to arrive at a conceptual design for a mechanical recovery system for the recovery of HNS deposited on the seabed. In the design of the system, based on the fundamental scenario, the method of suction foundation with the function of self enclosing was adopted for recovering the HNS sediment in the subsea sediment. The mechanical recovery system comprises the suction foundation, pollution prevention, a pump system, control system, monitoring device, location information device, transfer device, and tanks. This conceptual design is expected to be reflected and used in the basic design of the components and shapes of the mechanical recovery system.

• The Korean Journal of Quaternary Research
• /
• v.17 no.2
• /
• pp.163-163
• /
• 2003

The study area, Kwangneung Experiment Forest (KEF) is located on the west-central portion of Korean peninsula and belongs to a cool-temperate broadleaved forest zone. At the old-growth deciduous forest near Soribong-peak (533.1m) in KEF, we have established a permanent plot and a flux tower, and the site was registered as a KLTER site and also a KoFlux site. In this study, we aimed to present basic ecological characteristics and synthetic data of carbon budgets and flows, and some monitoring data which are essential for providing important parameters and validation data for the forest dynamics models or biogeochemical dynamics models to predict or interpolate spatially the changes in forest ecosystem structure and function. We made a stemmap of trees in 1 ha plot and analyzed forest stand structure and physical and chemical soil characteristics, and estimated carbon budgets by forest components (tree biomass, soils, litter and so on). Dominant tree species were Quercus serrata and Carpinus laxiflora, and accompanied by Q. aliena, Carpinus cordata, and so on. As a result of a field survey of the plot, density of the trees larger than 2cm in DBH was 1,473 trees per ha, total biomass 261.2 tons/ha, and basal area 28.0 m2/ha. Parent rock type is granite gneiss. Soil type is brown forest soil (alfisols in USDA system), and the depth is from 38 to 66cm. Soil texture is loam or sandy loam, and its pH was from 4.2 to 5.0 in the surface layer, and from 4.8 to 5.2 in the subsurface layer. Seasonal changes in LAI were measured by hemispherical photography at the l.2m height, and the maximum was 3.65. And the spatial distributions of volumetric soil moisture contents and LAIs of the plot were measured. Litterfall was collected in circular littertraps (collecting area： 0.25m2) and mass loss rates and nutrient release patterns in decomposing litter were estimated using the litterbag technique employing 30cm30cm nylon bags with l.5mm mesh size. Total annual litterfall was 5,627 kg/ha/year and leaf litter accounted for 61% of the litterfall. The leaf litter quantity was highest in Quercus serrata, followed by Carpinus laxiflora and C. cordata, etc. Mass loss from decomposing leaf litter was more rapid in C. laxiflora and C. cordata than in Q. serrata litter. About 77% of C. laxiflora and 84% of C. cordata litter disappeared, while about 48% in Q. serrata litter lost over two years. The carbon pool in living tree biomass including below ground biomass was 136 tons C/ha, and 5.6 tons C/ha is stored in the litter layer, and about 92.0 tons C/ha in the soil to the 30cm in depth. Totally more than about 233.6 tons C/ha was stored in DK site. And then we have drawn a schematic diagram of carbon budgets and flows in each compartment of the KEF site.

• Fisheries and Aquatic Sciences
• /
• v.22 no.12
• /
• pp.31.1-31.12
• /
• 2019

Background: The black-chinned tilapia, Sarotherodon melanotheron, is the most abundant fish species in the Nakwa (an open lagoon) and Brenu (a closed lagoon) in the Central Region of Ghana. Aspects of the life history characteristics and the ecology of the fish populations in both lagoons were studied to assess the bio-ecological status of this important resource. Methods: Fish samples were obtained from fishermen that fish on the Nakwa and Brenu lagoons using cast, drag and gill nets. The age of the fish was assessed from otoliths analysis and its growth modelled following the von Bertalanffy growth function. Morphometric characteristics of the fish populations were analysed using power regression and ANOVA for parameters comparisons, and Student's t test to determine whether species grew isometrically. The percentage occurrence method was used to analyse the stomach contents of the fish. Results: A total of 382 fish samples from both lagoons were measured, comprising 209 from Nakwa lagoon and 176 from Brenu lagoon. The size and weight of fish samples ranged between 3.9-11.5 cm total length and 1.0-27.3 g for Nakwa Lagoon and 5.6-12.8 cm total length and 3.2-29.8 g for the Brenu Lagoon. The estimated von Bertalanffy growth parameters were L∞ = 12.04 cm and K = 2.76/year for the Nakwa Lagoon samples and L∞ = 13.44 cm and K = 3.27/year for Brenu Lagoon samples. Daily otolith incremental rate ranged from 0.01-0.03 mm per day to 0.01-0.02 mm per day for Nakwa and Brenu lagoons, respectively. Stomach content analysis of the fish samples revealed that the species are planktivorous and the range of food varied between the lagoons. Green algae were the most prevalent food item in the stomachs of the fish samples from Nakwa with the frequency of 69% whilst diatoms (80.5%) were most prevalent phytoplanktonic food item for the fish in Brenu lagoon. Conclusions: The estimates of asymptotic length for the species in both lagoons are close to known values of the species length at first sexual maturity and points to intensive fishing pressure. As a consequence, a comprehensive sample-based survey is required in both lagoons to derive estimates of management reference points. The results of the stomach content analysis are beneficial to the construction of diet matrix for ecosystem models of the two systems.

• Journal of Korean Society of Environmental Engineers
• /
• v.34 no.12
• /
• pp.855-862
• /
• 2012

Caenorhabditis elegans, a free-living nematode mainly found in the soil pore water, roles the critical function in trophic levels, energy flow, and decomposition in soil ecosystem. C. elegans is commonly used species to test soil toxicity. Recently, they are employed broadly as a test organism in nanotoxicology. In this study, a review of the toxicity of nanomaterials for C. elegans was presented based on SCI (E) papers. The nanotoxicity studies using C. elegans have been reported in 20 instances including the mechanism of toxicity. Most studies used K-medium, S-medium, and NGM (Nematode Growth Medium) plate as an exposure medium to test toxicity of nanoparticles. The effects observed include anti aging, phototoxicity, genotoxicity, and dermal effects on C. elegans exposed to nanoparticles. We found that the toxic mechanisms were related with various aspects such as lifespan abnormality, oxidative stress, distribution of particles on inter-organisms, and stress-related gene analysis. C. elegans has advantage to test toxicity of nanoparticles due to various cellular activities, full genome information, and easy observation of transparent body. C. elegans was considered to be a good test species to evaluate the nanotoxicity.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
• /
• v.15 no.1
• /
• pp.31-44
• /
• 2020

Accelerators that invest in early startups, as well as nursery and overall management, have recently emerged as "key players" in the startup ecosystem. This can be proved by the case where the number of domestic accelerators registered in the Korean Ministry of SMEs and Startups has recently reached 208. Accelerators provide the necessary education for early-stage companies, including guidance for a certain period of time, and support startups in ways such as demo days to attract subsequent investment after the seed investment. There is not much research in academia about what factors impact on these accelerators when making investment decisions at the time of seed investment. In this study, we checked the meaning and function of the accelerator and tried to analyze what factors affect on accelerators when making a decision to invest in startups. The research method is based on a literature survey of previous studies on investment decision-making factors of venture capital and angel investors, and a lens model and judgment analysis method through empirical research targeting 43 accelerator investment decision-makers. Empirical analysis shows that accelerators have three of the key factors to consider when choosing the first startup to invest and educate; entrepreneurs' entrepreneurial traits, their product and service expertise and a potential return on success. This will provide an opportunity for early startups to gain strategic access to accelerators when they need money or need a structured educational program. Also, the results obtained through this research will be a kind of guideline for startups to attract accelerators' investment. The significance of this study is that discriminatory evidence was presented on the accelerator determinants of investment, and it would be highly suggestive to startups and related public institutions.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.26 no.4
• /
• pp.207-216
• /
• 2014

Total organic carbon (TOC) is an important indicator used as an direct biological index in the research field of the marine carbon cycle. It is possible to produce the sufficient TOC estimation data by using the Chemical Oxygen Demand(COD) data because the available TOC data is relatively poor than the COD data. The outlier detection and treatment (removal) should be carried out reasonably and objectively because the equation for a COD-TOC conversion is directly affected the TOC estimation. In this study, it aims to suggest the optimal regression model using the available salinity, COD, and TOC data observed in the Korean coastal zone. The optimal regression model is selected by the comparison and analysis on the changes of data numbers before and after removal, variation coefficients and root mean square (RMS) error of the diverse detection methods of the outlier and influential observations. According to research result, it is shown that a diagnostic case combining SIQR (Semi - Inter-Quartile Range) boxplot and Cook's distance method is most suitable for the outlier detection. The optimal regression function is estimated as the TOC(mg/L) = $0.44{\cdot}COD(mg/L)+1.53$, then determination coefficient is showed a value of 0.47 and RMS error is 0.85 mg/L. The RMS error and the variation coefficients of the leverage values are greatly reduced to the 31% and 80% of the value before the outlier removal condition. The method suggested in this study can provide more appropriate regression curve because the excessive impacts of the outlier frequently included in the COD and TOC monitoring data is removed.

• Korean Journal of Environmental Biology
• /
• v.21 no.2
• /
• pp.87-100
• /
• 2003

It is important to understand the potential human health implications of exposure to environmental chemicals that may act as hormonally active agents. It is necessary to have an understanding of how pharmaceutical and personal care products and other chemicals affect the ecosystem of our planet as well as human health. Endocrine disruption is defined as the ability of a chemical contaminating the workplace or the environment to interfere with homeostasis, development, reproduction, and/or behavior in a living organism or it's offspring. Certain classes of environmentally persistent chemicals such as polychlorinated biphenyls (PCBs), dioxins, furans, and some pesticides can adversely effect the endocrine systems of aquatic life and terrestrial wildlife. Research continues to support the theory of endocrine disruption. However, endocrine disruption researches have been applied to proteomics poorly. Proteomics can be defined as the systematic analysis of proteins for their identity, quantity and function. It could increase the predictability of early drug development and identify non-invasive biomarkers of tonicity or efficacy. Proteome analysis is most commonly accomplished by the combination of two-dimensional gel electrophoresis (2D/E) and MALDI-TOF mass spectrometry (MS) sr protein chip array and SELDI-TOF MS. Proteomics have an opportunity to play an important role in resolving the question of what role endocrine disruptors play in initiating human disease. Proteomics can also play an imfortant role in the evaluation of the risk assessment and use of risk management and risk communication tools required to address public health concerns related to notions of endocrine disruptors. Understanding the need for the proteomics and possessing knowledge of the developing biomakers used to abbess endocrine activity potential will he essential components relevant to the topic of endocrine disruptors.

• Ecology and Resilient Infrastructure
• /
• v.7 no.1
• /
• pp.26-42
• /
• 2020

Soils are the basis for plant rooting and ecosystem creation, the site of life for humankind, and require much time for their creation, so there will be no disagreement about the importance and necessity of soil conservation and management. Soil resilience is the ability of soils to maintain their original structure and function (resistance and recovery) from various kinds of disturbances, and is an indispensable field of study that prepares for a future with high uncertainty and unpredictability. Therefore, this study summarizes the concept and necessity of soil resilience, which is not yet widely known in Korea, and the contents of previous studies were reviewed. This study was carried out with the aim of contributing to lowering the threshold for entry into resilience research for domestic and foreign researchers who are new to soil resilience. In the first part of this study, we introduced resilience and soil resilience, and in the second part, we summarized the main causes of stress or disturbance that have been studied by many soil resilience researches. This makes it easy to find the references authors need. It is virtually impossible to find the same soil environment because there is no same area on the earth with all the same rock, climate, human activity, and culture, suggesting that each soil has its own uniqueness. Therefore, the researcher who wants to utilize the results of this study should take into consideration the specificity of the soil and the region to which the soil resilience is introduced, and modify it if necessary. In addition, efforts should be made to strengthen the network of soil resilience researchers to create a basis for sharing and actively utilizing the research results.