• Journal of Korean Society of Forest Science
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• v.110 no.3
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• pp.341-354
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• 2021

A large part of Gapyeong is occupied by Korean pine (Pinus koraiensis) and Japanese larch (Larix kaempferi) plantations. Abies holophylla stands are scattered throughout Gapyeong, but little information on their distribution is available. This study explored the potential of succession from planted species to native A. holophylla in plantations. Trees were inventoried and regeneration of A. holoplhylla and stand management history were examined in Korean pine, Japanese larch, and A. holophylla-dominated stands. The importance percentage of A. holophylla was the highest among species with a range of 36.1% to 79.1% in all stands and the density of A. holophylla in understory (DBH <2 cm or <1.3 m height) ranged from 50 to 5,820 trees ha^-1. Non-metric multidimensional scaling classified stands into four types, AN, AP, AM, and P. The AN type showed a reverse J-shape DBH distribution, which was similar to that in natural A. holophylla stands. Both AP and AM types included Korean pine plantations with A. holophylla seed trees within stands. For AP, A. holophylla competed with planted species in overstory and deciduous broadleaved species in understory. The AM type was once thinned from below, thus stem density in the mid DBH classes was lower than upper or lower DBH classes. The P type consisted of plantations without A. holophylla seed trees. However, understory regeneration of A. holophylla was abundant through seed supply from A. holophylla in adjacent stands. Plantations with A. holophylla seed trees within or in adjacent stands showed vigorous natural regeneration of A. holophylla, highlighting the potential for succession from planted species to native A. holophylla in the Gapyeong area. Further studies can help develop techniques to restore plantations to native species-dominated natural stands using ecological succession.

• Korean Journal of Remote Sensing
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• v.37 no.6_1
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• pp.1631-1645
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• 2021

This research aims to provide the characteristics of the world's first active lidar sensor Atmospheric Laser Doppler Instrument (ALADIN) wind data and Geostationary Korea Multi Purpose Satellite 2A (GK2A) Atmospheric Motion Vector (AMV) data by comparing two wind data. As a result of comparing the data from September 2019 to August 1, 2020, The total number of collocated data for the AMV (using IR channel) and Mie channel ALADIN data is 177,681 which gives the Root Mean Square Error (RMSE) of 3.73 m/s and the correlation coefficient is 0.98. For a more detailed analysis, Comparison result considering altitude and latitude, the Normalized Root Mean Squared Error (NRMSE) is 0.2-0.3 at most latitude bands. However, the upper and middle layers in the lower latitudes and the lower layer in the southern hemispheric are larger than 0.4 at specific latitudes. These results are the same for the water vapor channel and the visible channel regardless of the season, and the channel-specific and seasonal characteristics do not appear prominently. Furthermore, as a result of analyzing the distribution of clouds in the latitude band with a large difference between the two wind data, Cirrus or cumulus clouds, which can lower the accuracy of height assignment of AMV, are distributed more than at other latitude bands. Accordingly, it is suggested that ALADIN wind data in the southern hemisphere and low latitude band, where the error of the AMV is large, can have a positive effect on the numerical forecast model.

• Korean journal of applied entomology
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• v.57 no.4
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• pp.347-354
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• 2018

In order to setting the control standard of Chinese cabbage pests using a drone, the downward wind speed, spraying width, and the number of falling particles and particle size were examined using a water sensitive paper with spray different heights (3, 4, 5 m) and flying speeds (3, 4 m/sec). Fore kinds of pesticides for aviation control were used to test the perfect lethal concentration and dose for major pests of Chinese cabbage such as Plutella xylostella, Spodoptera exigua and Spodoptera litura. The number of falling particles in spraying pesticides with drones was 80.5% on the upper side, 14.8% on the vertical side, and 4.7% on the back side. The number of falling particles as different spray heights were 3 m = 53, 4 m = 40 and $5m=39particles\;cm^{-2}$. The number of falling particles as different flying speeds were $3m\;sec^{-1}=62$ and $4m\;sec^{-1}=25particles\;cm^{-2}$. In the laboratory test, the perfect lethal concentration and dose of Plutella xylostella was chlorfenapyr SC (20 times, $0.5{\mu}l$) and bistrifluron chlorfenapyr SC (25 times, $0.5{\mu}l$). The perfect lethal concentration and dose of Spodoptera exigua was chlorfenapyr SC (20 times, $1{\mu}l$), bistrifluron chlorfenapyr SC (20 times, $1{\mu}l$), and chlorfenapyr SC (20 times, $1{\mu}l$) and bistrifluron chlorfenapyr SC (20 times, $0.5{\mu}l$) for Spodoptera litura. Therefore, the main pest control method of Chinese cabbage using drones is 20 times diluted chlorphenapyr SC or bistrifluoruron-chlorphenapyr SC, sprayed at 3 m height by $3msec^{-1}$ of going speed. This spraying method will be effective for control of Chinese cabbage pest.

• Korean Journal of Heritage: History & Science
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• v.38
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• pp.305-327
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• 2005

Although the stone pagoda in Mireuk Temple site, Iksan, Cholla Province has been collapsed long time ago, few historical record has clearly explained the reason why the pagoda was collapsed and when. The west side of the pagoda have been destroyed from top to the sixth floor and the broken or damaged stone materials have been piled up in disorder. the lower part in the west was reinforced and enclosed by a stone embankment levelled to the height of the first storey of the pagoda. With no record informing the historical fact when it was made and by whom, it is only presumed that the embankment may have been built long time ago in order to prevent remains from further destruction. In the second chapter of the study, it has been tried to restore a reasonable historical background of the pagoda based on records or comments found in literatures such as traditional poetry and essays in chronological order. The collapsed slope in the west side, just above the embankment surrounding the lower part of the pagoda, was concreted in 1915 during the Japanese colonial period. Then in 1998, the Jeollabukdo has examined the structural safety of the pagoda. The Cultural Properties Committee has decided have the concrete layer removed and moreover to take apart the whole pagoda. It is also included that the disassembled stone materials should be given proper conservation treatments before being put into the place where they were in the reassembling process. The front view of the collapsed phase of the pagoda was revealed when the concrete-covered layer was removed. A hypothesis was built that there may be as many different appearances of collapsed pagoda depending on natural causes such as earthquake, sunken foundation, flood and typhoon. In chapter three, characteristic features were classified by examining various images of pagodas destroyed by different natural reasons mentioned in historical records. The chapter four dealt with comparison and analysis on the conditions shown in the stone pagoda in Mireuk Temple site and other examples studied in advance. The result of the study revealed that though having been made higher than the ground surface, the podium or the base of the pagoda actually has been eroded by rain and water. The erosion is supposed not only to have been proceeded for a long time without break but also to have caused the first storey body stone in the west inclined to outward. It has come to a conclusion that the pagoda may have been lead to collapse when the first storey body stone, supporting the whole weight from the upper storeys, became out of upright position and lost its balance. However, no such distinctive features of structural changes shown in pagodas collapsed by natural causes like earthquake, typhoon or sunken basement, have been found in the stone pagoda in Mireuk Temple site.

• Journal of Bio-Environment Control
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• v.31 no.4
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• pp.468-475
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• 2022

This study was conducted to find out the efficiency of heating initiative temperature and carbon dioxide fertilization in summer squash (Cucurbita moschata D.). The heating start temperature experiment was performed at 9℃, 12℃, and 15℃ using an electric heater and operated when the temperature was lower than the target temperature. The CO₂ fertilization concentration experiment was performed from 7 to 12 with the control, 500 µmol·mol^-1, and 800 µmol·mol^-1 using liquefied carbon dioxide. Investigation items were plant height, stem diameter, number of leaves, leaf area, fresh weight, dry weight, also economic analysis was conducted by surveying only fruits exceeding 100 g. Photosynthesis was measured for the upper leaf position to calculate the saturation point according to the control. The photo saturation point was 587 µmol·m^-2·s^-1, and the CO₂ saturation point was 702 µmol·mol^-1. A_max values by carbon dioxide were 13.4, 17.8, 17.2, 19.6, and 17.5 µmolCO₂·m^-2·s^-1 in the order of 9℃, 12℃, 15℃, 500 µmol·mol^-1, and 800 µmol·mol^-1. In the temperature experiment, 9℃ in growth did not grow normally and no fruiting was performed. 12℃ and 15℃ were higher than 9℃, but there was no significant difference in growth and production. The CO₂ fertilization experiment showed no significant difference between the treatment in growth, but the productivity of 800 µmol·mol^-1 was the best. Comprehensively, the heating initiative temperature of 15℃ was good for crop growth and production, but there is no significant difference from 12℃, so it is good to set the heating start temperature to 12℃ economically, and maintaining of 800 µmol·mol^-1 is effective in increasing production.

• Journal of Bio-Environment Control
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• v.32 no.1
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• pp.48-56
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• 2023

High-pressure sodium (HPS) lamps have been widely used as a useful supplemental light source to emit sufficient photosynthetically active radiation and provide a radiant heat, which contribute the heat requirement in greenhouses. The objective of this study to analyze the thermal characteristics of HPS lamp and thermal behavior in supplemented greenhouse, and evaluate the performance of a horizontal leaf temperature of sweet pepper plants using computational fluid dynamics (CFD) simulation. We simulated horizontal leaf temperature on upper canopy according to three growth stage scenarios, which represented 1.0, 1.6, and 2.2 plant height, respectively. We also measured vertical leaf and air temperature accompanied by heat generation of HPS lamps. There was large leaf to air temperature differential due to non-uniformity in temperature. In our numerical calculation, thermal energy of HPS lamps contributed of 50.1% the total heat requirement on Dec. 2022. The CFD model was validated by comparing measured and simulated data at the same operating condition. Mean absolute error and root mean square error were below 0.5, which means the CFD simulation values were highly accurate. Our result about vertical leaf and air temperature can be used in decision making for efficient thermal energy management and crop growth.

• Journal of Korea Water Resources Association
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• v.56 no.11
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• pp.775-784
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• 2023

With the increasing trend of extreme rainfall that exceeds the design frequency of man-made structures due to extreme weather, it is necessary to review the safety of agricultural reservoirs designed in the past. However, there are no local government-managed reservoirs (13,685) that can be discharged in an emergency, except for reservoirs over a certain size under the jurisdiction of the Korea Rural Affairs Corporation. In this case, it is important to quickly deploy a mobile siphon to the site for preliminary discharge, and this study evaluated the applicability of a mobile siphon with a diameter of 200 mm, a minimum water level difference of 6 m, 420 (m²/h), and 10,000 (m²/day), which can perform both preliminary and emergency discharge functions, to the Yugum Reservoir in Gyeongju City. The test bed, Yugum Reservoir, is a facility that was completed in 1945 and has been in use for about 78 years. According to the hydrological stability analysis, the lowest height of the current dam crest section is 27.15 (EL.m), which is 0.29m lower than the reviewed flood level of 27.44 (EL.m), indicating that there is a possibility of lunar flow through the embankment, and the headroom is insufficient by 1.72 m, so it was reviewed as not securing hydrological safety. The water level-volume curve was arbitrarily derived because it was difficult to clearly establish the water level-flow relationship curve of the reservoir since the water level-flow measurement was not carried out regularly, and based on the derived curve, the algorithm for operating small and medium-sized old reservoirs was developed to consider the pre-discharge time, the amount of spillway discharge, and to predict the reservoir lunar flow time according to the flood volume by frequency, thereby securing evacuation time in advance and reducing the risk of collapse. Based on one row of 200 mm diameter mobile siphons, the optimal pre-discharge time to secure evacuation time (about 1 hour) while maintaining 80% of the upper limit water level (about 30,000 m²) during a 30-year flood was analyzed to be 12 hours earlier. If the pre-discharge technology utilizing siphons for small and medium-sized old reservoirs and the algorithm for reservoir operation are implemented in advance in case of abnormal weather and the decision-making of managers is supported, it is possible to secure the safety of residents in the risk area of reservoir collapse, resolve the anxiety of residents through the establishment of a support system for evacuating residents, and reduce risk factors by providing risk avoidance measures in the event of a reservoir risk situation.

• Korean Journal of Ichthyology
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• v.36 no.3
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• pp.240-252
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• 2024

The distribution status of the nature monument species, Hemibarbus mylodon, was investigated from 2021 to 2024 in Geumgang River and Mujunamdae Stream (a tributary of the Geumgang River). In 2021 to 2023, five individuals from Gemgang River upstream were collected by Geumsan-gun, Chungchangnam-do. In 2021 to 2024, 1,592 induviduals juvenile from seven sites were collected by surveying 15 sites from Mujunamdae Stream. The main habitat of juvenile was about 0.3~1.5 meters water deep, 0.14~0.16 meters per second in the middle-upper stream of rock and sand bottom with slow rapids and pools. The age groups for H. mylodon estimated by the frequency distribution of total length in after spawning season (May) to October indicated the 10~65 mm is 0-year old, 75~90 mm is 1-year old group. In addition, over the 120 mm group is 2-years old, the 190~250 mm is more than 3-years old group. In 2024, we identified 35 spawning place from six sites were sites were collected by surveying 15 sites. Spawning place at the river bottom were top of the rapids, 30~60 cm (mean 48.2 cm) water deep, and the place was covered with stone and gravel, water velocity was 0.13~0.34 (mean 0.25 m/sec) meter per second. The spawning place size of the gravel piles was as follows: length 35~48 cm (mean 40.7 cm), width 25~37 cm (mean 34.5), and height 5~12 cm (mean 8.6 cm). Thus, H. mylodon reintroduced to Mujunamdae Stream has successfully settled down and increase in abundance within the natural habitat.

• Korean Journal of Agricultural Science
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• v.3 no.1
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• pp.39-51
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• 1976

As an accempt to increase thc efficiency of land use and the food production to achieve the national goal in the food self-sufficiency, nine cropping systems on the upper-land were examined in pure-stand and in mixtures of soybean, corn, potato and radish. The important conclusions of this study were summarized as follows; 1. The flowering date of soybean was two or three days earlier in pure-stand than in the mixture with corn. The maturing date two days earlier in the pure-stand than in the mixture with corn. The flowering and maturing dates were not different among various cropping systems in corn. 2. The stem length of soybean was significantly different among various cropping systems. Soybean in pure-stand was shorter in stem length than with corn. 3. The number of pods per soybean plant did not give any significant differences among various cultivation methods. 4. The length of internode and the number of nodes per soybean plant in the mixture with corn were greater than in the pure-stand. In the number of branches per plant this was reversed. 5. The average stem dry weight of soybean per 10a was not significantly different among various cultivation methods. 6. The soybean yield per 10a in the pure-stand was obviously greater than the mixture and there were significant differences among cultivation method within the mixture with corn in soybean yield. 7. The 1,000-grain weight of soybean was significantly different and those in the pure-stand was heavier than those in the mixture with corn. 8. Grain weight per soybean plant and the stem diameter in the pure-stand were significantly lesser than those in the mixture with corn. 9. In the comparisons of corn in the pure-stand and in the mixture with soybean, plant height, number of ear per 10a, mean ear weight and remember of grain per plant, 100-grain weight, ear length, ear girth and number of ear pel plant were not significantly different among various cultivation methods except for the grain yield per 10a. 10. In the economic analysis, the mixture with soybean and corn gave the greatest gross income. The combination 7 was the best which was 47.6% increase income comparing with the soybean pure-stand. 11. As it can be assumed, soybean plant was influenced greatly than corn by various cropping system. It is necessary to study more complex cropping system finding and giving more desirable multiple cropping system for the farmer.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.26 no.1
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• pp.69-89
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• 1981

Stevia (Stevia rebaudiana Bertoni) is a perennial herb widely distributed in the mountainous area of Paraguay. It belongs to the family Compositae and contains 6 to 12 percent stevioside in the leaves. Stevioside is a glucoside having similar sweetening character to surgar and the degree of sweetness is approximately 300 times of sugar. Since Korea does not produce any sugar crops, and the synthetic sweetenings are potentially hazardous for health, it is rather urgent to develop an economical new sweetener. Consequently, the current experiments are conducted to establish cultural practices of stevia, a new sweetening herbs, introduced into Korea in 1973 and the results are summarized as followings: 1. Days from transplanting of cuttings to the flower bud formation of 6 stevia lines were similar among daylengths of 8, 10 and 12 hours, but it was much greater at daylengths of 14 or 24 hour and varietal differences were noticable. All lines were photosensitive, but a line, 77013, was the most sensitive and 77067 and Suweon 2 were less sensitive to daylength. 2. Critical daylength of all lines seemed to be approximately 12 hours. Growth of plants was severely retarded at daylengths less than 12 hours. 3. Cutting were responded to short daylength before rooting. Number of days from transplanting to flower bud formation of 40-day old cuttings in the nursery bed was 20 days and it was delayed as duration of nursery were shorter. 4. Number of days from emergence to flower bud formation was shortest at short day treatment from 20 days after emergence. It was became longer as initiation of short day treatment was earlier or later than 20 days. 5. Plant height, number of branches, and top dry weight of stevia were reduced as cutting date was delayed from March 20 to May 20. The highest yield of dry leaf was obtained at nursery duration of 40-50 days in march 20 cutting, 30-40 days in April 20 cutting, and 30 days in May 20 cutting. 6. An asymptotic relationship was observed between plant population and leaf dry weight. Yield of dry leaf increased rapidly as plant population increased from 5,000 to 10,000 plants/10a with a reduced increasing rate from 10,000 to 20,000 plants/l0a, and levelled off at the plant population higher than 20,000 plants/l0a. 7. Stevia was adaptable in Suweon, Chengju, Mokpo and Jeju and drought was one of the main factors reducing yield of dry leaf. Yield of dry leaf was reduced significantly (approximately 30%) at June 20 transplanting compared to optimum transplanting. 8. Yield of dry leaf was higher in a vinyl house compared to unprotected control at long daylength or natural daylength except at short day treatment at March 20. Higher temperature ill a vinyl house does not have benefital effects at April 20 transplanting. 9. The highest content of stevioside was noted at the upper leaves of the plant but the lowest was measured at the plant parts of 20cm above ground. Leaf dry weight and stevioside yield was mainly contributed by the plant parts of 60 to 120cm above ground but the varietal differences were also significant. 10. Delayed harvest by the time of flower bud formation increased leaf dry weight remarkably. However, there were insignificant changes of yield as harvests were made at any time after flower bud formation. Content of stevioside was highest at the time of flower bud formation and earlier or later harvest than this time was low in its content. The optimum harvesting time determined by leaf dry weight and stevioside content was the periods from flower bud formation to right before flowering that would be the period from September 10 to September 15 in Suweon area. 11. Stevioside and rebaudioside content in the leaves of Stevia varieties were ranged from 5.4% to 14.3% and 1.5% to 8.3% respectively. However, no definit relationships between stevioside and rebaudioside were observed in these particular experiments.