• Korean Journal of Environment and Ecology
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• v.34 no.5
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• pp.358-371
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• 2020

As climate change is expected to lead to a severe reduction of biodiversity, studies to investigate the reasons for habitat loss, growth decline, and death of Korean fir (Abies koreana Wilson), endangered alpine/subalpine species in Korea, have been conducted for years but found no clear answer yet. This study reviewed previous studies on Korean fir published in the journals in the past 40 years, 1980 through 2020, into 10-year units, examined the study trend by period, region, and subject with a focus on ecological studies, and analyzed the study results. The ecological studies were categorized into evolutionary ecology, physiological ecology, population ecology, and landscape ecology. Based on the results, we suggested the required research fields in the future. We found a total of 73 papers published in the past 40 years and 48 (65.8%) of them published in the past 10 years. In terms of region, Mt. Halla accounted for the most as 41 papers were on it. In terms of ecological subjects, the physiological ecology accounted for the most with 38, and the evolutionary ecology accounted for the least with 10. The review of the study results showed that many studies identified water stress caused by the water resource imbalance due to temperature increase and spring precipitation reduction following climate change as the main reason for the decline and habitat loss of Korean fir. However, recent studies suggested other factors, such as soil environment, disturbing organisms, and climatic events. The cause of the decline and death of the Korean fir not yet being clearly identified is that most of the studies dealt with the basic content, were carried out intermittently, and were concentrated in some regions. Therefore, we need long-term studies with advanced technology in each study subject at a local scale to find the cause of Korean fir decline and present sustainable management and conservation. Moreover, it is necessary to extend our study subjects to ecosystem ecology and systems ecology to integrate the results from various study subjects for a comprehensive understanding of the reason for Korean fir declines. The results of comprehensive studies could provide clearer answers for Korean fir's declines and the alternatives of conservation management and practices.

• Journal of Wetlands Research
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• v.25 no.4
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• pp.306-314
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• 2023

Stream sediments are an important component of water quality management because they are receptors of various pollutants such as heavy metals and organic matters emitted from upland sources and can be secondary pollution sources, adversely affecting water environment. To effectively manage the stream sediments, identification of primary sources of sediment contamination and source-associated control strategies will be required. We evaluated the performance of machine learning models in identifying primary sources of sediment contamination based on the physico-chemical properties of stream sediments. A total of 356 stream sediment data sets of 18 quality parameters including 10 heavy metal species(Cd, Cu, Pb, Ni, As, Zn, Cr, Hg, Li, and Al), 3 soil parameters(clay, silt, and sand fractions), and 5 water quality parameters(water content, loss on ignition, total organic carbon, total nitrogen, and total phosphorous) were collected near abandoned metal mines and industrial complexes across the four major river basins in Korea. Two machine learning algorithms, linear discriminant analysis (LDA) and support vector machine (SVM) classifiers were used to classify the sediments into four cases of different combinations of the sampling period and locations (i.e., mine in dry season, mine in wet season, industrial complex in dry season, and　industrial complex in wet season). Both models showed good performance in the classification, with SVM outperformed LDA; the accuracy values of LDA and SVM were 79.5% and 88.1%, respectively. An SVM ensemble model was used for multi-label classification of the multiple contamination sources inlcuding landuses in the upland areas within 1 km radius from the sampling sites. The results showed that the multi-label classifier was comparable performance with sinlgle-label SVM in classifying mines and industrial complexes, but was less accurate in classifying dominant land uses (50~60%). The poor performance of the multi-label SVM is likely due to the overfitting caused by small data sets compared to the complexity of the model. A larger data set might increase the performance of the machine learning models in identifying contamination sources.

• Horticultural Science & Technology
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• v.33 no.1
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• pp.47-54
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• 2015

This research was conducted to investigate the changes in moisture retention capacities of expanded rice-hull (ERH)-based root media and their influences on the growth of mother and daughter plants in vegetative propagation of 'Seolhyang' strawberry. The proportion of water at the container capacity of ERH medium was in the range of 20 to 23%. This range was lower than the 60 to 66% of strawberry-specialized medium, the 30 to 34% of soil mother material (SMM) and the 30 to 35% of loamy sand. The moisture content of ERH was reduced to 10 to 12% at 8 hours after irrigation, and there were large variations among replications of ERH medium. Among four kinds of root media formulated to contain ERH, the medium of ERH + coir dust (CD) (55 + 45%, v/v) had 26.5 and 32.5% water contents at 20 and 40 days after irrigation to daughter plants, respectively. The m edia o f ERH + sandy loam (S L) and E RH + S MM showed similar trends i n moisture r etention. The pH and EC i n the all root media tested were in the range of 6.7 to 7.1 and 0.03 to $0.08dS{\cdot}m^{-1}$, respectively. The pHs and ECs measured at 20 and 40 days after irrigation were not significantly different in each root medium. Among the root media formulated to contain ERH, the growth of daughter plants was the highest in the treatment of ERH + SL (55 + 45%, v/v). As the blending rate of coir dust was elevated in the ERH + CD media, moisture retention capacity increased gradually, but the growth of daughter plants became worse even though the medium showed higher moisture retention capacity than other root media tested. The growth of roots and aboveground tissues of daughter plants deteriorated in the root media formulated by blending ERH + perlite (PE) at various ratios. The results of this research suggest the optimum formulations of root media and management of moisture content in raising of strawberry daughter plants when ERH is a component of root media.

• Current Research on Agriculture and Life Sciences
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• v.4
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• pp.87-94
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• 1986

This study was performed in order to contemplate their correlations between physical and mechanical properties of the marine clays which were collected from main harbors in Korea. The results obtained are as follows: 1. Most of the soils in experimental districts consist of CH. CL. and ML. and they are considered to be still proceeding. 2. The equations of the relationship between compression index and liquid limit are as, follows: CH : $C_c=0.0137$ (LL-22.60) CL : $C_c=0.0123$ (LL-14.64) 3. The relationship between compression index and initial void ratio appears that the higher the plasticity, the easier the slope of the regression line. The equations are as follows : CH : $C_c=0.431$ ($e_o-0.504$) CH : $C_c=0.471$ ($e_o-0.235$) ML : $C_c=0.641$ ($e_o-0.393$) 4. The equations of the relationship between compression index and natural water content are as follows: CH : $C_c=0.0133$ ($W_n-28.27$) CL : $C_c=0.0225$ ($W_n-23.56$) ML : $C_c=0.0106$ ($W_n-16.42$) 5. The relationship between initial void ratio and natural water content, and compression index is highly positive correlation and the equations are as follows : CH : $C_c=0.301$ ($e_o+0.017W_n-1.05$) CL : $C_c=0.141$ ($e_o+0.0567W_n-1.054$) ML : $C_c=0.421$ ($e_o+0.0214W_n-1.121$) 6. The equations of the relationship between initial void ratio and liquid limit, and compression index are as follows : CH : $C_c=0.36$ ($e_o+0.08LL-0.819$) CL : $C_c=0.269$ ($e_o+0.026LL-0.929$) 7. The cohesion of marine clays is no concerned with the increment of depth. The equations of relationship between cohesion and unconfined compression strength are as follows. CH : qu=1.896C+0.0107 CL : qu=1.849C+0.04.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.4
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• pp.346-352
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• 2020

Currently, many studies are being conducted to cope with climate changes due to global warming and abnormal weather. The objective of this study was to investigate the effects of weather on the growth, yield components, and quality of soybeans using weather data from 2017 and 2018. The average temperature in 2018 was higher than that in 2017 from R1 to R5 of the growth stage for all cultivars. On the other hand, precipitation in 2018 was reduced compared to that in 2017 for Daewon and Daepung-2ho. It was observed that the flowering date in 2018 was earlier than that in 2017 for Daewon and Daepung-2ho, but the flowering date for Pungsannamul in 2018 was similar to that in 2017. Simulating soil water content with the estimation model (AFKAE0.5) determined that there were fewer drought dates in 2017 than those in 2018, and drought lasted from R1 to early R5 of the growth stage in 2018. Soybean growth in 2017 was better than that in 2018, and seed yield and 100-seed weight of soybean were higher in 2017 than those in 2018 for all cultivars. The seed size in 2017 was larger than that in 2018 for all cultivars. Oil content in 2017 was higher than that in 2018; in particular, the difference between both years was observed for Daewon and Daepung-2ho. Protein content was higher in 2018 than that in 2017; however, there were different levels for each cultivar. Thus, these results indicate that the yield component and quality of soybeans are affected by high temperature and drought.

• Geotechnical Engineering
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• v.8 no.1
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• pp.81-102
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• 1992

Landslides on hillside slopes with shallow soil cover over a sloping bedrock are frequently caused by increases in porewater pressures following of heavy rainfall and it is one of the most important factors of assessing the risk of landslide to predict the groundwater level fluctuations in hillslopes. This paper presents the comparative study of three unsaturated flow models developed by Sloan et al., Reddi, L.N., and Thomas, H.A., Jr., respectively, which are used to predict the increase of groundwater levels in hillside slopes. The parametric study for each of models is also presented. The Kinematic Storage Model(KSM) developed by Sloan et at. is utilized to predict the saturated groundwater flow. They are applied to the two sites in Korea so as to examine the possibility of use in the groundwater flow model. The results show that two unsaturated models developed by Sloan et al. and Reddi, L. N. are largely affected by the uncertain parameters like saturated permeability and saturated water content : the abed model has the potential of use in unsaturated flow model with the optimal estimates of model parameters utilizing available optimization techniques. And it is also found that the KSM must be modified to account for the time delay effect in the saturated zone. The results of this paper are able to be utilized in developing the predictive model of groan dwater level fluctuations in a hillslope.

• Journal of the Korea Concrete Institute
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• v.21 no.3
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• pp.283-290
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• 2009

Differently from fly ash, the bottom ash produced from thermoelectric power plant has been treated as an industrial waste matter, and almost reclaimed a tract from the sea. If this waste material is applicable to foam concrete as an aggregate owing to its light-weight, however, it may be worthy of environmental preservation by recycling of waste material as well as reducing self-weight of high-rising structure and horizontal forces and deformations of retaining wall subject to soil pressure. This study has an objective of evaluating the effects of application of bottom ash on the mechanical properties of foam concrete. Thus, the ratio of bottom ash to cement was selected as a variable for experiment and the effect was measured in terms of unit weight of concrete, air content, water-cement ratio and compressive strength. It can be observed from experiments that the application ratios have different effects on the material parameters considered in this experiment, thus major relationships between application ratio and each material parameter were finally introduced. The result of this study can be applied to decide a mix design proportion of foam concrete while bottom ash is used as an aggregate of the concrete.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.3
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• pp.136-144
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• 2013

In this study, in order to establish a plan that will enable safe use of renewable resources such as diverse industrial by-products and urban recycled materials, we conducted experiments that focused on flow, bleeding, compressive strength and environmental pollution evaluation to evaluate the material properties of low strength concrete using BFS and SS. In the case of low strength concrete using BFS and SS, blending of at least BFS 6000 within a 30% range regardless of the type of sand used was found to be the most effective approach for improving the workability by securing the minimum unit quantity of water, restraining the bleeding ratio and establishing compressive strength by taking account of the applicability at the work site. In particular, in view of the efficient use of SS, the optimal mixing condition was found to be the mixing of BFS 8000 with in the 30% range, not only for improving the workability restraining the bleeding ratio and establishing the compressive strength but also for application to the work site. Further, the results of tests on hazardous substance content and those of elution tests conducted on soil cement using SS indicated that all values satisfied the environmental standards without any harmful effects on the surrounding environment.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.156-156
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• 2017

Most crop damages have been occurred by vermin(e.g., wild birds and herbivores) during the period between seeding and the cotyledon level. In this study, to minimize the damage by vermin and acquire the benefits such as protection against weeds and maintenance of water content in soil, immediately vinyl mulching after seeding was devised. Vinyl mulching has been generally covered with black color vinyl, that crop seeding locations cannot be detected by visible light range. Before punching vinyl, non-contact and non-destructive methods that can continuously determine the locations are necessary. In this study, a crop position detection method was studied that uses infrared thermal image sensor to determine the cotyledon position under vinyl mulch. The moving system for acquiring image arrays has been developed for continuously detecting crop locations under plastic mulching on the field. A sliding mechanical device was developed to move the sensor, which were arranged in the form of a linear array, perpendicular to the array using a micro-controller integrated with a stepping motor. The experiments were conducted while moving 4.00 cm/s speed of the IR sensor by the rotational speed of the stepping motor based on a digital pulse width modulation signal from the micro-controller. The acquired images were calibrated with the spatial image correlation. The collected data were processed using moving averaging on interpolation to determine the frame where the variance was the smallest in resolution units of 1.02 cm. For this study, the spline method was relatively faster than the other polynomial interpolation methods, because it has a lower maximum order of formulation when using a system such as the tridiagonal linear equation system which provided the capability of real-time processing. The temperature distribution corresponding to the distance between the crops was 10 cm, and the more clearly the leaf pattern of the crop was visually confirmed. The frequency difference was decreased, as the number of overlapped pixels was increased. Also the wave pattern of points where the crops were recognized were reduced.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.3
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• pp.359-366
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• 1993

Molds are eucaryotic, multicellular, multinucleate, filamentous organisms that reproduce by forming asexual and sexual spores. The spores are readily spread through the air and because they are very light-weight and tend to behave like dust particles, they are easily disseminated on air currents. Molds therefore are ubiquitous organisms that are found everywhere, throughout the environment. The natural habitat of most molds is the soil where they grow on and break down decaying vegetable matter. Thus, where there is decaying organic matter in an area, there are often high numbers of mold spores in the atmosphere of the environment. Molds are common contaminants of plant materials, including grains and seeds, and therefore readily contaminate human foods and animal feeds. Molds can tolerate relatively harsh environments and adapt to more severe stresses than most microorganisms. They require less available moisture for growth than bacteria and yeasts and can grow on substrates containing concentrations of sugar or salt that bacteria can not tolerate. Most molds are highly aerobic, requiring oxygen for growth. Molds grow over a wide temperature range, but few can grow at extremely high temperatures. Molds have simple nutritional requirements, requiring primarily a source of carbon and simple organic nitrogen. Because of this, molds can grow on many foods and feed materials and cause spoilage and deterioration. Some molds ran produce toxic substances known as mycotoxins, which are toxic to humans and animals. Mold growth in foods can be controlled by manipulating factors such as atmosphere, moisture content, water activity, relative humidity and temperature. The presence of other microorganisms tends to restrict mold growth, especially if conditions are favorable for growth of bacteria or yeasts. Certain chemicals in the substrate may also inhibit mold growth. These may be naturally occurring or added for the purpose of preservation. Only a relatively few of the approximately 100,000 different species of fungi are involved in the deterioration of food and agricultural commodities and production of mycotoxins. Deteriorative and toxic mold species are found primarily in the genera Aspergillus, Penicillium, Fusarium, Alternaria, Trichothecium, Trichoderma, Rhizopus, Mucor and Cladosporium. While many molds can be observed as surface growth on foods, they also often occur as internal contaminants of nuts, seeds and grains. Mold deterioration of foods and agricultural commodities is a serious problem world-wide. However, molds also pose hazards to human and animal health in the form of mycotoxins, as infectious agents and as respiratory irritants and allergens. Thus, molds are involved in a number of human and animal diseases with serious implication for health.