• Journal of the Korean GEO-environmental Society
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• v.13 no.9
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• pp.17-29
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• 2012

To investigate the characteristics of shear strength and soil deformation in soft grounds, in which various vertical drains were placed, two hundreds field monitoring data of embankments performed in thirteen road construction sites at west and south coastal areas of the Korean Peninsula were collected. At first, the relationship between settlement and lateral displacement was investigated into three stages, in which embankment construction works were divided into initial filling stage, final filling stage and stage after complete filling. And then, the relationship of surcharge pressures and embankment heights with undrained shear strength of soft grounds were investigated. The investigation on settlement and lateral displacement illustrated that the increment of lateral flow to the increment of settlement was low during initial filling stage, but increased gradually with filling and showed largest during final filling stage. After complete filling, the lateral displacement was converged, even though the settlement was increased continuously. Therefore, most of lateral flow was occurred during embankment filling. The ratio of the lateral displacement increment to the settlement increment was 20% for initial filling stage, which coincided with the one presented by Tavenas et al.(1979), but became 50% for final filling stage, which was half of the one presented by Tavenas et al.(1979). However, the ratio reduced to 1% to 9%, which was quite lower than the one presented by Tavenas et al.(1979). Shear deformations, even shear failures, were predicted in soft grounds under initial undrained shear strength, since the design heights of embankments were higher than the yield height in all the sites. However, embankment construction would be possible since the yield height became higher than the design height due to improvement of shear strength of soft grounds with application of the vertical drains. In order to perform safely embankments for road constructions, the embankment loads should be designed not to be exceed 5.14 times the initial undrained shear strength of soft grounds and to be less than 3.0 times the undrained shear strength improved with application of vertical drains in soft grounds.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.1
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• pp.30-39
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• 2020

A new silicate coating technology was developed which reduces the impact of dust and loosening during seeding compared to existing silicate-coatings (Seed/Si/Zeolite), and therefore can lower the production costs of rice cultivation. In this method, 100 g of rice seed is coated with 18 mL of liquid silicic acid and then dressed with a mixture containing 80 g of dolomite and 5 g of iron. To determine the most effective method of application and ensure that seedlings developed healthily, a series of experiments were carried out. Infected seeds scattered in seedling boxes and pots (soil and hydroponic) were coated dry, without disinfection. In comparison to the seed which were not treated with the silicate-coating, the new seed (A) were 1.84 times heavier in weight, and were also improved in terms of coating strength and coating color. Compared to the seedlings grown from the non-coated seed, those grown from the new silicate-coated seed were of significantly higher quality (weight/length) and had erect, dark greenish leaves, which are ideal plant characteristics. This was most likely due to increased silicate uptake. The symptoms of bakanae disease in the non-coated seed peaked after 38 days to 54.2%, whereas the control value was 68.8% in the new silicate-coated seed (A). In the infected seedlings grown from the new silicate-coated rice seed, subnormal macro-conidia, namely, a sickle shape spore without a septum; a straight oblong shape spore without a septum and with a thick cell wall; and inter-septal necrosis of a normal spore were detected. It is believed that the strong alkalinity of silicic acid have acted as unfavorable conditions for pathogenicity. In seedlings grown from the new silicate coated rice seed under hydroponic conditions without nutrients, normal root activity and growth was maintained without leaf senescence. Therefore, it was possible to reduce the rate of fertilization. In the future, a new silicate-coated rice seed was required for the study of minimal nutrition for anti-aging of seedlings.

• Journal of Bio-Environment Control
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• v.27 no.3
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• pp.253-259
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• 2018

This study set out to select a system to realize an optimal environment for strawberry cultivation greenhouses based on data about the growth and development of strawberry and its environment and to provide basic data for the research of its improved productivity. For these purposes, the investigator conducted a field survey with greenhouses for strawberry cultivation in western Gyeongnam. The findings show that farmers in their fifties and sixties accounted for the biggest part in the age groups of strawberry farmers. While those who were under 50 were accounted for approximately 67.5%, those who were 60 or older accounted for 32.5%. As for cultivation experiences, the majority of the farmers had ten years of cultivation experiences or less with some having 30 years of cultivation experiences or more. All the farmers built an arch type single span greenhouse. Those who used nutrient solutions were about 75.0%, being more than those who used soil. All of the farmers that used a nutrient solution adopted an elevated hydroponic system. The single span greenhouses were in the range of 7.5~8.5m, 1.3~1.8m and 2.5~3.5m for width, eaves, and ridge height, respectively, regardless of survey areas. The rafters interval was about 0.7~0.8m. In elevated hydroponic cultivation, the width, height, and interval of the beds were about 0.25m, 1.2m and 1.0m, respectively. As for the strawberry varieties, the domestic ones accounted for approximately 97.5% with Seolhyang being the most favorite one at about 65.0%. As for the internal environment factors of greenhouses, 38 farmers measured only temperature and relatively humidity. As for hydroponics, the farmers used a hydroponics control system. Except for the farmers that introduced a smart farm system for temperature and humidity control, approximately 85.0% controlled temperature and humidity only with a control panel for side windows and ventilation fans. As for heating and heat insulation, all of the farmers were using water curtains with many farmers using an oil or electric boiler, radiating lamp or non-woven fabric, as well, when necessary.

• Journal of Korean Society of Forest Science
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• v.99 no.4
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• pp.611-617
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• 2010

The current studies aim is to analyze the production cost of walnut tree cultivation and its object was targeted at walnut tree cultivating household region 163. The analysis is as follows. Our domestic walnut tree cultivating households averagely have cultivated about 0.7ha, and planting number per ha was averagely 204, and it showed that compared to the standard planting number (100), the plantation was done close planted. The most cultivar cultivated according to regions were Chungbuk region: sangchon 65.7%, Chungnam region: kwangduk 68.6%, Jeonbuk region: sangchon 98.0%, Gyeongbuk region: daeboo 61.2%. The production cost for cultivating walnuts can be classified into the followings; management cost(4436 thousand won/ha) such as manufacturing cost(292 thousand won/ha), intermediate material cost(3682 thousand won/ha), rent(103 thousand won/ha), employment cost(653 thousand won/ha) etc, and self-serviced expenses such as self-laboring cost(5,834 thousand won/ha), land security cost(490 thousand won/ha), fixed capital cost(834 thousand won/ha), circulating capital cost(234 thousand won/ha) etc. 11,820 thousand won were invested for the production cost of walnut and it made 11,586 thousand won/ha(rate of investment 72.3%) profit, and the net income was 4,196 thousand won/ha(net income rate 26.2%), showing high amount of income. The manufactured walnuts were marketed in Nong-hyup 39.8%, wholesalers 20.8%, dealers 19.8% and recently, as the amount of goods marketed directly to consumers themselves have increased, the income has reached up to 18.9%. At the basis of making most of idle soil, walnut tree's cultivated regions are fairly small, and due to the characteristics of sideline management, it has its limits in searching for production policy locally and promotion strategy of industries. Therefore, if the basic database can be established, subjected only to full-time cultivating households, then not only would the differences between the imported walnuts be reinforced, it would also be possible to transfer into the new and improved distribution system. Furthermore, through establishment of the database, it can be anticipated that it would contribute greatly in the increase of the household income.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.3
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• pp.183-192
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• 1982

The variability of rice productivity during last 2 decades (1961-1980) of ten years before and after the introduction of"Tongil" was reviewed from the epochal, regional and varietal points of view. During that period the cultivated area of paddy rice have remained almost unchanged, while the total rice production have got elevated from 3, 463 million metric tons in 1961 to 6.006 million metric tons in 1977, recording 73.4% increase. This remarkable increase in rice production is considered to be attributable much to the development and release of new high yielding variety, "Tongil", coupled with the amelioration of cultural techniques. However, in 1978 Tongil type varieties experienced the epidemic outbreak of blast disease due to the shifted race population of blast fungus and in 1980 recorded poor rice production as low as in 1960's due to the unfavorable weather stress throughout the rice growing season, giving rise to many problems awaiting solutions for securing the stabilized high production of rice. The rice yield has continued the gradual increase during last two decades but its difference between farmer and research organization have got wider from 79kg/10a during 1960 to 1971 to 101kg/l0a during 1972 to 1980, and also the inter-regional differences have been increased from 50-60kg/10a to 80kg/10a during those periods. Therefore, this proves that we have raised the upper boundary of rice yield by increasing the yield potential of rice variety but have not changed those absolute deviations. Estimates indicate that the increased rice production during that period was indebted 40 percent to the varietal improvement and 13 percent to the ameliorated agro-technologies, and the rest, 47 percent, could be ascribed to the other factors besides varieties and cultural technologies such as the improved agricultural environments, etc. Of course, even though it cannot be expected to unify the cultural environments and the cultural technologies, provided that much efforts are to be endeavored to minimize the yield difference of 20 percent between farmer and research organizations and the inter-regional yield difference of 20 percent, much increased rice production can be expected to be achieved with the current level of cultural technology and the yielding potential of the present rice varieties. In order to expedite the above effects on rice production the followings are to be put into practices consitently and steadfastly. 1. Reinforcement of breeding for varieties with high yielding potential and less susceptible to climatic-stress and pests, and of basic physicoecological studies of rice plant for improving the cultural technologies. 2. Continuous endeavor to secure the stabilized cultural environments by improving the soil fertility and increasing the drainage and irrigation facilities. 3. Political back-up to encourage the farmers' incentives for production 4. Precise surveys for agricultural statistics to facilitate the long-term planninge long-term planning.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.4
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• pp.459-468
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• 2019

Changes in growing periods and productivities of crops under double cropping of potato-rice, potato-soybean and potato-maize, were investigated at the Paddy Experimental Fields in Miryang City from 2015 to 2018. Spring potatoes planted in early March showed a yield of 2.1-2.3 ton/10a and a period of 90 days. In double cropping, growing period of rice, soybean, and maize was about 130, 125 and 115 days, respectively. The potato yield obtained was as much as 616, 330 and 815 kg/10a under double cropping with rice, soybean and maize, respectively. It is beneficial to sow the spring potatoes as early as possible to increase the yield and to secure the growing period of sequential crops. The introduction of summer medium-late variety grain crops into double cropping of spring potato and rice as well as into double cropping of spring potato and soybean/maize, was possible because of no sowing in the fall and plants were able to reach the heading growth stage before the safe heading limit of rice in particular. In the case of maize, the growth period was different according to the change in temperature over the year. The introduction of upland crops such as soybeans and maize instead of rice improved soil physicochemical properties in a short period of time, contributing to the increase of spring potato yields, but there was also a risk of damage by successive cropping for more than three years. Spring potato-maize showed higher yield in terms of starch production, and spring potato-soybean was found to be advantageous for net income.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.30 no.1
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• pp.125-134
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• 2012

This study is determined by tree vigor of analyzing of each object's growth condition in Locational Characteristics and compare the result with impediment extent rate in crown area to provide the management Study about the influence of man-made structures in numbers of protected trees. 68 places where are in the list of Kimpo protected trees were researched in Natural environments, vital degree of trees, number of trees. Crown area was calculated surveying it around the directions of North, East, South and West branching out. Impediment in the area was analyzed after classified into artificial impediment like paved surface(ascon, concrete, block, etc.), a building and a breast wall and natural impediment like soil, stonework and gravel and conclusions are as follow. In analyzing of natural environments, he ground where protected trees have located is consist of 72.05 of manmade structure and artificial in all. There are many protected trees which have less space than crown area for growth suggested by Woo-kyung Sim and Se-kyun Shin in 1992. And it was analyzed that making growth space for protected trees and management of impediment are urgently needed because of that the proportion of impediment covering the crown area has increased as cities are becoming more urbanized results in transforming of trees and weakness of tree vigor. This research shows that under 20% of in crown area is tree vigor determination 1-2 grade 21-50% under is 2-3 grade, higher than 50% is 3-5 grade. More impediment have more difficulty for growing, with the management of root system of protected trees need to be under 20% of rate of land is necessary was improved. As follows are suggested about the standard of management in artificial impediment which influence the number of trees. Firstly, impediment in crown area must be restricted under 20%, but in case outside of the area is not artificial the rate could be higher considerable. Secondly, protected trees growth space secured as much as crown area and impediment must be installed outside the crown area. Thirdly, to move the protected trees, condition of growth space secure must be considered. Fourthly, to develope land, the area around protected trees should be utilized in a park, the area of impediment installation in crown area should be limited as well. Fifthly, As many shown in previous research, for the improvement of old big trees and protected trees, need the tax favor of landowner and purchase of around land, to manage, it needs the budget of local government and advice of expert. Also the study on how various kind of impediment nearby protected trees influence on them has to be continued.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.28 no.2
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• pp.127-136
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• 2010

This study is aimed at reviewed and analyzed in order to suggest the improved plans related to natural monuments. The summary of this study is as followings; First, Replacing the current term 'cultural properties', which denotes the meaning of 'goods', we need to devise an new categorization that separates such properties into cultural heritage and natural heritage under the national heritage framework. Second, the designation criteria for natural monuments should be divided into the individual realm for animals and plants respectively, since they are not divided in the current Act. Third, the guidelines for naming of natural monuments should be established with the following new categories in accordance with the clear standards. Fourth, such imbalances require us to give priority to the relatively neglected types and areas. Fifth, as the big and old trees account for more than a half of the designated plants, it is necessary to search out new resources(wet plant communities, seashores, sand dune plant communities, etc.) such as geological resources, mineral springs, hot springs, and fossils that are in danger of completely being exploited and exhausted. While most of the designated animals are protected nationally, the existing designation system is required to protect habitats and breeding places for the systematic and efficient conservation. Sixth, as long as we need to preserve those historical and cultural resources for the future generations from national and global perspectives, we should enhance their values by designating them as natural monuments even though they are protected by other regulations such as the natural environment area. Seventh, as a result of the survey, we found that more budgets and experts in the local governments, more empowered organizations, more active public participation should be provided for the better Natural Monument management in Korea. Eighth, the Lap of Natural Heritage in the National Research Institute of Cultural Heritage needs to be developed to the Natural Heritage Institute to conduct the diverse activities such as researches, restoration, exhibition and education programs in a systematic and efficient way. Ninth and the last, major damages to natural monuments can be generally categorized into the artificial one and natural one, respectively. The artificial damages include toxics, soil covering, excessive humidity, fire, construction and management works, unlawful damages, fishing, oil spillage, etc, and the natural ones include lightning, storms(typhoons), heavy snowfalls, damage by insects and diseases, lack of prey, etc. This study will become meaningful in that it proposes specific measures for the improvement of the institutions, designation, and management of natural monuments on the basis of the comprehensive analysis on natural monuments. We wish to leave the other subjects related with this study to the future researches.

• Korean Journal of Remote Sensing
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• v.14 no.4
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• pp.353-365
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• 1998

Light absorption coefficient per unit mass of particles, i.e., specific absorption coefficient, is important as one of the main parameters in developing algorithms for ocean color remote sensing. Specific absorption coefficient of chlorophyll ($a^*_{ph}$) and suspended sediment ($a^*_{ss}$) were analyzed with a spectrophotometer using the "wet filter technique" and "Kishino method" for the seawater collected in the Yellow and Mediterranean Sea. An improved data-recovery method for the filter technique was also developed using spectrum slopes. This method recovered the baselines of spectrum that were often altered in the original methods. High $a^*_{ph}({lambda})$ values in the oligotrophic Mediterranean Sea and low values in the Yellow Sea were observed, ranging 0.01 to 0.12 $m^2$/mg at the chlorophyll maximum absorption wavelength of 440 nm. The empirical relationship between $a^*_{ph}$(440nm) and chlorophyll concentrations () was found to fit a power function ($a^*_{ph}$=0.039 $^{-0.369}$), which was similar to Bricaud et al. (1995). Absorption specific coefficients for suspended sediment ($a^*_{ss}$) did not show any relationship with concentrations of suspended sediment. However, an average value of $a^*_{ss}$ ranging 0.005 - 0.08 $m^2$/g at 440nm, was comparable to the specific absorption coefficient of soil (loess) measured by Ahn (1990). The morepronounced variability of $a^*_{ss}$ than $a^*_{ph}$ was determined from the variable mixing ratio values between particulate organic matter and mineral. It can also be explained by a wide size-distribution range for SS which were determined by their specific gravity, bottom state, depth and agitation of water mass by wind in the sea surface.

• Journal of Korean Society of Forest Science
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• v.110 no.3
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• pp.322-340
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• 2021

Due to climate change and its consequential spring temperature rise, flowering time of Robinia pseudoacacia has advanced and a simultaneous blooming phenomenon occurred in different regions in South Korea. These changes in flowering time became a major crisis in the domestic beekeeping industry and the demand for accurate prediction of flowering time for R. pseudoacacia is increasing. In this study, we developed and compared performance of four different models predicting flowering time of R. pseudoacacia for the entire country: a Single Model for the country (SM), Modified Single Model (MSM) using correction factors derived from SM, Group Model (GM) estimating parameters for each region, and Local Model (LM) estimating parameters for each site. To achieve this goal, the bloom date data observed at 26 points across the country for the past 12 years (2006-2017) and daily temperature data were used. As a result, bloom dates for the north central region, where spring temperature increase was more than two-fold higher than southern regions, have advanced and the differences compared with the southwest region decreased by 0.7098 days per year (p-value=0.0417). Model comparisons showed MSM and LM performed better than the other models, as shown by 24% and 15% lower RMSE than SM, respectively. Furthermore, validation with 16 additional sites for 4 years revealed co-krigging of LM showed better performance than expansion of MSM for the entire nation (RMSE: p-value=0.0118, Bias: p-value=0.0471). This study improved predictions of bloom dates for R. pseudoacacia and proposed methods for reliable expansion to the entire nation.