• Journal of Bio-Environment Control
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• v.30 no.4
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• pp.367-376
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• 2021

Strawberry cultivation in Korea is grown in greenhouse, but most farms manage their water supply using a timer control method based on the experience of growers. The timer control has problems in that it is difficult to consider the weather condition, the growth stage of crops, and the moisture content of the substrate, so that the crops cannot be managed at an optimal level, and the accuracy of cultivation management are lacking. The watering methods using integrated solar irradiance and substrate moisture contents are control systems that provide eco-friendly and precise water supply considering the growth conditions of crops. The purpose of this study was to compare the combined water supply control with integrated solar irradiance and substrate moisture contents and timer control method in hydroponic cultivation of strawberries using coir, and to set the optimal integrated solar irradiance level for complex water supply control. The irrigation system was automatically watered when it reached 100, 150, 250 J·cm^-2 based on the external solar irradiance, and forced irrigation was performed at a substrate moisture content of less than 60% in all treatments. The amount of irrigation at once was 50 mL. The timer treatment was applied as a control. The smaller the level of integrated radiation to start watering, the greater the daily amount of irrigation. Both the fresh weight and dry weight per plant were higher in the complex irrigation control method than the timer control, and the 100 and 150 J·cm^-2 treatment had the highest fresh weight, and the 100 J·cm^-2 treatment showed a significantly higher dry weight. The yield was also significantly higher in the complex control method than in the timer, and the early yield increased as the level of integrated solar irradiance was smaller. The fresh weight of fruit was the lowest in the timer-controlled irrigation. As a result of this study, the possibility of combined control irrigation method using integrated solar irradiance and substrate moisture content was confirmed for precise water supply management of strawberries in hydroponics.

• Korean Journal of Environment and Ecology
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• v.33 no.3
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• pp.266-279
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• 2019

We investigated the characteristics of fish communities and habitat status of endangered species Rhodeus pseudosericeus in Heuk Stream, a tributary of the Han River, from April to October 2018. During this period, we collected 47 species of 14 families from 10 survey stations using kick nets, cast nets, and long bag set nets. The dominant and subdominant species were Zacco platypus (37.6%) and Z. koreanus (13.8%), respectively. The next most abundant species were Squalidus gracilis majimae (11.1%), Pungtungia herzi (7.7%), Rhodeus pseudosericeus (5.0%), Microphysogobio yaluensis (4.3%), and Hemibarbus longirostris (3.0%). Among the fish collected, 19 species (40.4%) were Korean endemic species. Endangered species were R. pseudosericeus and Acheilognathus signifer while exotic species were Micropterus salmoides and Oncorhynchus mykiss, and land-locked species were Plecoglossus altivelis and Rhinogobius brunneus. The community analysis showed that the dominance and evenness indexes were mostly low and that the diversity and richness indexes were high. Moreover, the river health (index of biological integrity) was mostly excllent (1 site is good, 9 sites are very good). R. pseudosericeus inhabited widely from St. 3 to St. 9 in Heuk Stream, and its population size was large. Age groups for R. pseudosericeus estimated by the frequency distribution of total length in spawning season (April) indicated the 32~45 mm group as 1-year old, the 46~59 mm group as 2-years old, 60~69 mm group as 3-years old, and the 70~89 mm group as 4-years or older. Total length range of male and female was similar, and the sex ratio of female (426) to male (394) was 1 : 0.95. A. signifer, which had been released in Heuk Stream, inhabited from St. 4 to St. 5, but its population size was small. Lastly, this paper discusses a conservation plan for fish in Heuk Stream.

• Journal of Bio-Environment Control
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• v.31 no.1
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• pp.22-27
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• 2022

The attraction effects of light emitting diode (LED) trap to Spodoptera exigua and Spodoptera litura adults were evaluated in greenhouse and compared with those of no light trap, which is typical used in commercial trap. At this time, in order to attract these two species of moths, sex pheromone traps were installed at the top side according to the degree of tomato growth inside the tomato cultivation greenhouse around the LED trap. In addition, two types of light-emitting traps (420 nm, 470 nm) were installed in the greenhouse at 1/40 m², respectively. Also two sex pheromone were installed inside of the greenhouse according to the height of the tomato plants. 10 days later, Blue-light trap(BLB, 470 nm wavelength) was 3.1-3.5 times more attractive than Violet-light trap(VLB, 420 nm wavelength) in S. exigua (105.6 ± 7.3) and S. litura (42.0 ± 3.1) respectively, whereas the no-light trap was little attractive to S. exigua (33.7 ± 2.8) and S. litura (12.0 ± 1.5). On the other hand, after the installation of the sex pheromone trap and the LED trap, there was no damage to S. litura (Fabricius) and S. exigua in the pesticide-free area, indicating a high possibility of control. At this time, the operating cost of the two types of LED traps was 80 won/m² per unit area, and it was confirmed that both types of moths could be controlled. In addition, as a result of confirming the number of two types of moths caught in the sexual pheromone trap and two types of LED traps after 4 months, it was judged that eco-friendly control was possible as more than 373 moths/trap were attracted to the two types of moths.

• Korean Journal of Ecology and Environment
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• v.55 no.1
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• pp.60-75
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• 2022

The Bayesian algorithm model is a model algorithm that calculates probabilities based on input data and is mainly used for complex disasters, water quality management, the ecological structure between living things or living-non-living factors. In this study, we analyzed the main factors affected Korean Estuary Trophic Diatom Index (KETDI) change based on the Bayesian network analysis using the diatom community and physicochemical factors in the domestic estuarine aquatic ecosystem. For Bayesian analysis, estuarine diatom habitat data and estuarine aquatic diatom health (2008~2019) data were used. Data were classified into habitat, physical, chemical, and biological factors. Each data was input to the Bayesian network model (GeNIE model) and performed estuary aquatic network analysis along with the nationwide and each coast. From 2008 to 2019, a total of 625 taxa of diatoms were identified, consisting of 2 orders, 5 suborders, 18 families, 141 genera, 595 species, 29 varieties, and 1 species. Nitzschia inconspicua had the highest cumulative cell density, followed by Nitzschia palea, Pseudostaurosira elliptica and Achnanthidium minutissimum. As a result of analyzing the ecological network of diatom health assessment in the estuary ecosystem using the Bayesian network model, the biological factor was the most sensitive factor influencing the health assessment score was. In contrast, the habitat and physicochemical factors had relatively low sensitivity. The most sensitive taxa of diatoms to the assessment of estuarine aquatic health were Nitzschia inconspicua, N. fonticola, Achnanthes convergens, and Pseudostaurosira elliptica. In addition, the ratio of industrial area and cattle shed near the habitat was sensitively linked to the health assessment. The major taxa sensitive to diatom health evaluation differed according to coast. Bayesian network analysis was useful to identify major variables including diatom taxa affecting aquatic health even in complex ecological structures such as estuary ecosystems. In addition, it is possible to identify the restoration target accurately when restoring the consequently damaged estuary aquatic ecosystem.

• Korean Journal of Ecology and Environment
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• v.55 no.1
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• pp.84-98
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• 2022

Estuary is important in terms of biodiversity because it has the characteristics of transition waters, created by the mixing of fresh- and seawater. The estuarine water circulation provides a variety of habitats with different environments by inducing gradients in the chemical and physical environment, such as water quality and river bed structure, which are ultimately the main factors influencing biological community composition. If the water circulation is interrupted, the loss of brackish areas and the interception of migration of biological communities will lead to changes in the spatial distribution of biodiversity. In this study, among the sites covered by the Estuary Aquatic Ecosystem Health Assessment, we selected study sites where changes in biodiversity can be assessed by spatial gradient from the upper reaches of the river to the lower estuarine area. The α-, γ- and β-diversity of diatom, benthic macroinvertebrates, and fish communities were calculated, and they were divided into open and closed estuary data and compared to determine the trends in biodiversity variation due to estuarine circulation. As results, all communities showed higher γ-diversity at open estuary sites. The benthic macroinvertebrate community showed a clear difference between open and closed estuaries in β-diversity, consequently the estuarine transects were considered as a factor that decreases spatial heterogeneity of their diversity among sites. The biodiversity trends analyzed in this study will be used to identify estuaries with low γ- and β-diversity by community, providing a useful resource for further mornitoring and management to maintain estuarine health.

• Korean Journal of Environmental Agriculture
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• v.32 no.4
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• pp.355-358
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• 2013

BACKGROUND: Water-born pollution loads by agricultural non-point source (NPS) pollution are expected to become intensified due to ongoing precipitation change. Therefore, it is essential to develop a best management practice (BMP) that is suitable to agricultural environments in Korea. This study aimed to develop an environmental-friendly BMP to reduce NPS pollution load by agricultural activities. An eco-friendly way, small drainage pond, was suggested in this study to avoid direct drainage of agricultural runoffs and eventually reduce the amount of pollutants discharged into the surrounding aqua-environment. METHODS AND RESULTS: A small pond ($12m^2$) was constructed at the corner of a rice paddy field ($1,715m^2$) located in Suwon, Korea. Water was allowed to drain only via a small drainage pond. Sampling was repeatedly made at two locations, one from an entrance and the other from an exit of a pond, during the rice cultivation period (May to October, 2012). Generally, sampling was made only when runoff water drained through a pond, such as during and/or after rain (irrigation). The water quality analysis showed that all quality parameters (SS, $COD_{Mn}$, T-N, and T-P) were improved as water passed through the pond. The amount of runoff water was reduced by 96~100%. Suspended solids and COD concentrations was reduced by 79.3% and 45.6%, respectively. In case of T-N and T-P concentrations, the reduction rates were 52.2% and 60.5%, respectively and the amount of T-N and T-P were reduced by 16.3~73.0% and 15.4~70.1%, respectively. CONCLUSION(S): Our data implies that agricultural NPS pollution from rice paddy fields can be effectively managed when an appropriate drainage water management practice is imposed. In this paper, it was suggested that an installation of a small drainage pond can be effective to prevent not only the nutrient loss from rice fields but also pollutant discharge to surrounding water environments.

• Journal of the Korean Association of Geographic Information Studies
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• v.15 no.4
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• pp.65-77
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• 2012

This study examined changes in land cover for the past 25 years in Busan and subsequently evaluated heat island potential by using land surface temperature and observation temperature data. The results were as below. The urban area of Busan increased by more than 2.5 times for the past 25 years from 1975 to 2000. It was believed that an increase in the pavement area of city within such a short period of time was an unprecedented phenomenon unique to our country. It could be assumed that urban heat island would be worsened through this process. After analyzing the land temperature according to the land cover, it was shown that there were noticeable changes in the temperature of urban & built-up and mountain & forest areas. In particular, the temperature rose to $36{\sim}39^{\circ}C$ in industrial areas during the summer, whereas it went down to $22{\sim}24^{\circ}C$ in the urban areas at whose center there were mountains. It was found that heat island potential according to the level of land cover had various values depending on the conditions of land cover. Among the areas of urbanization, the industrial area's heat island potential is 6 to $8^{\circ}C$, and the residential and commercial area's is $0{\sim}5^{\circ}C$, so it has been found that there is high possibility to induce urban heat islands. Meanwhile, in the forest or agricultural area or the waterside, the heat island potential is $-6{\sim}-3^{\circ}C$. With this study result, it is possible to evaluate the effects of temperature increase according to the urban land use, and it can be used as foundational data to improve urban thermal environment and plan eco-friendly urban development.

• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.1
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• pp.73-87
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• 2018

A variety of micro meteorological variables such as air temperature, wind, solar radiation and latent heat at Gwangneung forests (conifer and broadleaved forests) and AWS (Automated Weather Station) of Pocheon urban area were used to quantify the air temperature reduction effect of forests, which is considered to be an eco-friendly solution for reducing the urban heat island intensity during summer. In June, July and August of 2016 and 2017, the average maximum air temperature differences between above and below canopy of forests, and between the forests and urban areas were $-1.9^{\circ}C$ and $-3.4^{\circ}C$ respectively, and they occurred at 17:00. However, there was no difference between conifer and broadleaved forests. The effect of air temperature reduction by the forests was positively correlated with accumulated evapotranspiration and solar radiation from 14:00 to 17:00 and showed a negative correlation with wind speed. We have developed a model to quantify the effect of air temperature reduction by forests using these variables. The nighttime air temperature reduction effect by forests was due to the generation of cold air from radiative cooling and the air temperature inversion phenomenon that occurs when the generated cold air moves down the side of mountain. The model was evaluated in Seoul by using 28 AWSs. The evaluation shows that the air temperature of each district in Seoul was negatively correlated with the area and size of the surrounding tall vegetation that drives vegetation evapotranspiration during the day. During the night, however, the size of the surrounding tall vegetation and the elevations of nearby mountains were the main influencing factors on the air temperature. Our research emphasizes the importance of the establishment and management of urban forests and the composition of wind roads from mountains for urban air temperature reduction.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.11 no.3
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• pp.97-109
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• 2016

In Korea, the survival rate of start-up of 5-year after foundation is as low as 29.6% of the country. This low survival rate is from because of insufficient resources in start-ups compared to those of mid-sized companies. Therefore, the marketing characteristics of entrepreneurship has emerged as a major cause. Therefore, In this study, because learning orientation, marketing experience, competition orientation and etc are differently owned in start-ups, marketing impact to marketing strategy in start-up companies are differently investigated. Therefore, the relationship of learning orientation, marketing experience, competition Orientation with marketing strategies was examined. Based on this, Business performance was examined to suggest contents related to eco-system of start-up companies to representative of start-up companies. For this study, Survey was conducted for 250 start-up entrepreneurs within 3 and half year since foundation from Nov. 20 to Dec. 20, 2015. In result of data-cleaning, 207 meaningful samples were gathered. Based on these, conclusion was obtained. Using SPSS 20.0 statistical program, frequency analysis, reliability analysis, correlation analysis and regression analysis were conducted. the following conclusions were drawn. First, in the impact of marketing environment of Phase 1 start-up companies on marketing strategy, product strategy, distribution strategy and promotion strategy were positively affected by learning orientation, marketing experience and competition orientation. Second, in the effect of 2nd phase marketing strategy to business performance, the financial performance and the non-financial performance. Were positively affected by product strategy, distribution strategy and promotion strategies. Third, The effect of learning orientation, marketing experience and competition orientation to financial performance was positively mediated by product strategy and distribution strategy among 3rd phase meditation strategies. the effect of learning orientation, marketing experience and competition orientation to non-financial performance was positively mediated by products strategy. In comprehensive summary, in order to increase business performance in start-up companies, marketing strategy should be applied in. Especially, the role of learning orientation and marketing experience is vital. In increasement of business performance to characteristics of star up marketing, financial performance can be increased by product strategy and distribution strategy. And, both of financial and non-financial performance can be increased by product strategy. Therefore, in conducting of marketing characteristics of start-up, to increase business performance, the apply of marketing strategy to marketing characteristics of start-up should be required.

• Korean Journal of Ecology and Environment
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• v.51 no.2
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• pp.149-159
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• 2018

Twenty-nine wetlands (20 river type and 9 lake type wetlands) in Gyeongsangnam-do were investigated to understand the characteristics of fish assemblages by the wetland type and to suggest management strategies. As a result, $10.3{\pm}4.8$ species were collected from river type wetlands on average (${\pm}SD$) and $9.1{\pm}4.1$ species from lake type wetlands. Thus, there was no significant difference in the number of species between them (Mann-Whitney U test, P>0.05). However, the species that constitute the fish assemblage showed statistically significant differences between the two wetland types (PERMANOVA, Pseudo-F=2.9555, P=0.007). Furthermore, the species that contribute the most to each type of fish assemblage were Zacco koreanus (river type, 28.51%) and Lepomis macrochirus (lake type, 23.21%), respectively (SIMPER). The results of the NMDS analysis using the fish assemblage by place classified the species into three groups (river type, lake type, and others). The current wetland management is only focused on endangered species, but this study shows a difference in fish assemblage by wetland type. Therefore, a management system based information on endemic species, exotic species and major contribution species should be provided. Furthermore, the classification of some types of wetlands based on the present topography was found to be ambiguous, and wetland classification using living creatures can be used as a complementary method. This study has limitations because only two types of wetlands were analyzed. Therefore, a detailed management method that can represent every type of wetland should be prepared through the research of all types of wetlands in the future.