• Korean Journal of Soil Science and Fertilizer
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• v.18 no.4
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• pp.325-335
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• 1985

Biogas production from agricultural wastes were summarized as follows: 1. Biogas Generation Characteristics of Various Manures and Residues a. Gas yield from crop residues like rice straw, rice hull, corn stalk and coconut husk can be improved by addition of animal manures. b. Gas yield from coconut husk can be improved through aerobic fermentation for at least one week before loading in the digester. c. Gas yield from fresh rice straw is better than from pre-fermented one, whether alone or in combination with animal manures. d. Initial study has shown that fresh azolla can be substituted for animal manures in manurerice straw combinations and gas yield derived based on unit volatile solids loaded is actually better than for manure-residue combinations. e. Gas production is highly sensitive to substrate pH and becomes almost nil at a pH of below 6. 2. Effect of ambient conditions and other factors on biogas production in a house hold-size digester. a. Results showed that compaction of rice straw in straw-manure combination can reduce gas yield compared with loosely mixed straw. b. The effective gas production period extended to 70 days using freshly threshed rice straw and fresh cattle manure as feed material. c. Underground and above ground digesters with shade have relatively more stable substrate temperature than aboveground exposed digesters. This relative temperature instability may likely be the reason for lower gas yield for the exposed aboveground digester loaded with loose straw-cattle manure substrate, compared with the underground digester with the same substrate. 3. Economic Analysis a. Based on prevailing costs of fuel, materials, and labor in the Philippines, biogas produced from the household size system is cheaper than either LPG or kerosene. b. If other benefits like organic fertilizer, pollution control and convenience are considered, biogas will surely be the best alternative fuel source.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.3
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• pp.193-204
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• 2000

In order to get some basic data on environmental friendly function by Korean organic farming, the chemical characteristics of soil were determined on 100 farm cultivating site in Paldang watershed area of Great Seoul. The EC and content of $NO_3-N$ and Av. $P_2O_5$ in topsoil(0~30cm) showed $2.30dS\;m^{-1}$, $82mg\;kg^{-1}$, $918mg\;kg^{-1}$ in the soil cultivated chinese cabbage. $2.29dS\;m^{-1}$, $86mg\;kg^{-1}$, $954mg\;kg^{-1}$ in the soil of lettuce, $1.83dS\;m^{-1}$, $66mg\;kg^{-1}$, $1114mg\;kg^{-1}$ in the soil of crown daisy. These salt accumulation(EC) and the high concentration of mineral content in topsoil such as nitrate and phosphate showed the soils of organic farming were contaminated by practice of organic farming for the maintenance strategy of soil fertility. The $NO_3-N$ and Av. $P_2O_5$ in the subsoil(30~60cm) showed $75mg\;kg^{-1}$ and $641mg\;kg^{-1}$, $72mg\;kg^{-1}$ and $466mg\;kg^{-1}$, $42mg\;kg^{-1}$ and $873mg\;kg^{-1}$ in soil cultivated chinese cabbage, lettuce and crown daisy respectively. It indicates eventually the high concentration of nitrate and phosphate in topsoil caused penetration to subsoil, and the high concentration of mineral contents in subsoil indicate the potential risk of leaching of ground water by Korean organic farming. The positive correlation at 1% between EC and $NO_3-N$, $K_2O$, T-C, $P_2O_5$ and T-N show the salt accumulation in the both soil depth of Korean organic farming were caused by minerals such as $NO_3-N$, $K_2O$, T-C, $P_2O_5$ and T-N by overuse of organic fertilizer.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.3
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• pp.119-126
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• 2003

Nitrate-N concentrations and the corresponding ${\delta}^{15}N$ values were determined with water samples collected periodically from artesian wells (3 and 6 m deep), underdrainage and gushout waters in a Welsh onion cultivated area in the Kushibiki Fan, Saitama Prefecture, Japan. Average $NO_3-N$ concentrations in waters from 3 and 6 m wells were 25.7 and $2.8mg\;L^{-1}$, whereas ${\delta}^{15}N$ values were 3.6 and 4.7‰, respectively. The $NO_3-N$ concentration and ${\delta}^{15}N$ value of the underdrainge water were $35.5mg\;L^{-1}$ and 6.6‰, reflecting rapid input of chemical fertilizers and farmyard manure. The mean values of $NO_3-N$ concentration and ${\delta}^{15}N$ in the gushout water flown out of the edge of Kushibiki Fan were $19.4mg\;L^{-1}$ and 7.9‰, respectively. As a results the ${\delta}^{15}N$ values of the gushout water were higher than those of the artesian wells and underdrinage water. The ${\delta}^{15}N$ values of total-N and $NO_3-N$ of the soils were 6.1 and 5.10‰, respectively, while those for nitrification-inhibitor containing fertilizer and slow-release fertilizers were -6.1 and -2.2‰, respectively.

• Journal of Korean Society of Forest Science
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• v.110 no.4
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• pp.601-609
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• 2021

The fructification characteristics, fruit quality, and yield of the 'Hwangsil' jujube tree were analyzed at various stages of growth age (3-8 years old) to obtain basic data for developing high-quality jujube production technology. The average height, crown area, stem diameter near the root, stem clear length, the number of the main branches, and the distance between any two main branches were 230.8 cm (224.4~247.2 cm), 3.0 m² (2.1~3.8m²), 4.8 cm (2.4~6.2 cm), 69.1 cm (46.6~78.0 cm), 12.9 (8.6~19.6), and 8.1 cm (7.4~9.0 cm), respectively. Tree age was positively correlated with the crown area, stem diameter near the root, but stem clear length negatively correlated with the number of main branches. The average number of fruits per mother bearing shoot and tree was 20.0 (14.3~26.3) and 302.8 (257.3~373.5), respectively. There was no correlation between tree age and fructification characteristics, such as the number of fruit-bearing mother shoots per the main branch, the number of fruit-bearing shoots per fruit-bearing mother shoot, and the number of fruits per fruit-bearing shoot. Since the shape of the jujube tree is constantly managed based onthe growing area and type of greenhouse where the tree grown. The average fruit weight, fruit hardness, and soluble solid content were 24.2 g (22.4~26.8 g), 28.4 N (27.3~30.0 N), and 19.0% (17.1~19.8%), respectively, with no correlation between the tree age and fruit quality. The average yield was 7.4 kg per tree (5.7~9.1 kg), with significantly high quantities were produced in six and seven years old trees.

• Korean Journal of Heritage: History & Science
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• v.54 no.4
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• pp.260-285
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• 2021

This article deals with the current status of investigation of the royal tombs of Baekje (Gongju Songsan-ri Tomb, Buyeo Neungsan-ri Tomb, Iksan Ssangneung) from the Japanese colonial period to the present. A review of the maintenance status is also conducted to see if the survey content was actually reflected in the restoration maintenance of the ruins. First, the structure scale and characteristics of the royal tombs of Baekje during the Woongjin and Sabi periods were identified by examining the survey content organized by period and feature. Through the recent re-excavation survey, it was confirmed that the results of the research during the Japanese colonial period were being verified. Next, before examining the maintenance status of the Baekje royal tombs, related content about maintenance of laws and regulations were extracted to establish the maintenance standards. It was confirmed that the most importance part of maintenance is 'maintenance of the original form' without compromising the authenticity of cultural properties. Based on these criteria, the maintenance status was reviewed. The main part of the burial tomb is located underground, so maintenance is mainly made around the tomb, which is the upper structure. However, most of the original burial mounds have been lost or damaged, so it is difficult to determine their original form. In fact, constant changes in the size and location of tombs from the Japanese colonial period to the present were confirmed in the Songsan-ri and Neungsan-ri tombs, meaning that the current maintenance status is problematic. On the other hand, in the case of Ssangneung, not only are the tombs relatively intact, but there are also few changes in the records, so it seems that maintenance was carried out that preserved the original form of the tombs. Therefore, the maintenance of tombs in the future should be based on 'maintaining the original form', but it is recommended that the 'education and utilization' plan be prepared after determining whether or not to restore the tomb and the degree of restoration.

• Korean Journal of Heritage: History & Science
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• v.52 no.1
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• pp.216-241
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• 2019

There are 35 cultural properties of fourteen kinds in the Demilitarized Zone known so far, but this number is expected to increase in the future. Among them, Cheolwon-Doseong and Jeongol-Chong of Gimhwa should be the first step toward conservation efforts by conducting a joint investigation through the collaboration of North and South Korea. In particular, the joint investigation of Cheolwon-Doseong will not only remind the North and South that they are the same people who have had common history and cultural traditions for a long time, but will also give symbolic meaning to convert the demilitarized zone into a stage for peace. Since Jeongol-Chong is a mass grave of the fallen soldiers of Pyeongan Province who fought against the invasion of the Qing of China, it should be managed as a national designated cultural asset through joint investigation. In addition, the Demilitarized Zone should become a World Heritage Site because of its importance to the legacy of the Korean War, an international war caused by an ideological confrontation. Furthermore, it has more than 6,000 kinds of temperate forests in addition to 100 species of endangered species and natural monuments. The DMZ is very qualified to be a World Natural Heritage Site, and should be included as a World Complex Cultural Heritage Site that qualifies as a World Heritage and World Natural Heritage Site. In the Demilitarized Zone, we can also find numerous highlands, tunnels and posts used during the Korean War, as well as surveillance posts, a military demarcation line, barbed wire fences, and Panmunjom, which were created by the armistice agreement. it would be desirable to select some of its sections and war facilities and to register them as modern cultural heritage assets. Finally, it is necessary to reconstruct the Dorasan Signal Fire Site, which was the communication facility of a traditional era which connected the South (Dorasan) and North (Gaesong). This would symbolize smooth communication between the two Koreas. In order to prepare for the reckless development of the Demilitarized Zone due to the upcoming cease-fire, the government and cultural asset experts will have to work hard to identify and preserve the cultural properties of the Demilitarized Zone, and they will also have to maintain consistent control over matters such as indiscriminate investigation and mine clearance.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.2
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• pp.109-126
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• 2019

Genetic resources of 84 species of Setaria italica BEAUVOIS, Sorghum bicolor, and Panicum miliaceum were collected to select the adaptable miscellaneous cereals in Saemangeum reclaimed land. The adaptability of Sorghum bicolor in reclaimed land was the highest among the three cereals cultivated on reclaimed land. The ratio of the average height of Sorghum bicolor plants cultivated in reclaimed land/normal field was 0.82, that of Panicum miliaceum was 0.61, and that of Setaria italica BEAUVOIS was 0.51. Three species of Sorghum bicolor, Satangdajuk, Kkamansusu, and Nampungcharl, were selected as potential genetic resources as they had excellent adaptability to reclaimed land. The yield of Satandaejuk on reclaimed land was 229.4 kg/10a, and the yield ratio of reclaimed land/normal field was 89.3%. The yield of Kkamansusu was 227.4 kg/10a, with reclaimed land/normal field ratio of 87.8%, and yield of Nampungcharl was 239.6 kg/10a, and reclaimed land/normal field ratio of 86%. In order to study the salt tolerance of selected genetic resources, we conducted salinity test. Salinity tolerance of Sorghum bicolor species-Satangdajuk, Kkamansusu, Nampungcharl was excellent compared to that of the other cereals. Among these, Satandaejuk had to highest salt tolerance level. Polyphenols, flavonoids, and detoxification of free radical were also studied. The anti-diabetic property of the cereals was also analyzed by ${\alpha}$-glucosidase inhibitory activity. We confirmed that the functionality of 3 lines in reclaimed land had improved in all the functional analysis categories when compared to that with yield in the normal field. Polyphenol, an antioxidant, increased in the range of 2~26% when cultivated in reclaimed land and the flavonoid content also increased from 8.5 to 55.6%. DPPH elimination capability, the ability to scavenge harmful reactive oxygen, also increased from 16.7 to 47% when cultivated in reclaimed land. The anti-diabetic activity and ${\alpha}$-glucosidase inhibition activity of selected Sorghum bicolor species-Satangdajuk, Kkamansusu, Nampungcharl also increased from 18.4 to 19.9% when cultivated on reclaimed land.

• Korean Journal of Remote Sensing
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• v.34 no.6_4
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• pp.1479-1488
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• 2018

On September 3rd 2017, strong artificial seismic signals from North Korea were detected in KMA (Korea Meteorological Administration) seismic network. The location of the epicenter was estimated to be Punggye-ri nuclear test site and it was the most powerful to date. The event was not studied well due to accessibility and geodetic measurements. Therefore, we used remote sensing data to analyze surface changes around Mt. Mantap area. First of all, we tried to detect surface deformation using InSAR method with Advanced Land Observation Satellite-2 (ALOS-2). Even though ALOS-2 data used L-band long wavelength, it was not working well for this particular case because of decorrelation on interferogram. The main reason would be large deformation near the Mt. Mantap area. To overcome this limitation of decorrelation, we applied offset tracking method to measure deformation. However, this method is affected by window kernel size. So we applied various window sizes from 32 to 224 in 16 steps. We could retrieve 2D surface deformation of about 3 m in maximum in the west side of Mt. Mantap. Second, we used Pleiadas-A/B high resolution satellite optical images which were acquired before and after the 6th nuclear test. We detected widespread surface damage around the top of Mt. Mantap such as landslide and suspected collapse area. This phenomenon may be caused by a very strong underground nuclear explosion test. High-resolution satellite images could be used to analyze non-accessible area.

• Tunnel and Underground Space
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• v.28 no.6
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• pp.670-691
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• 2018

This study presents the research results of the BMT(Benchmark Model Test) simulations of the DECOVALEX-2019 project Task B. Task B named 'Fault slip modelling' is aiming at developing a numerical method to predict fault reactivation and the coupled hydro-mechanical behavior of fault. BMT scenario simulations of Task B were conducted to improve each numerical model of participating group by demonstrating the feasibility of reproducing the fault behavior induced by water injection. The BMT simulations consist of seven different conditions depending on injection pressure, fault properties and the hydro-mechanical coupling relations. TOUGH-FLAC simulator was used to reproduce the coupled hydro-mechanical process of fault slip. A coupling module to update the changes in hydrological properties and geometric features of the numerical mesh in the present study. We made modifications to the numerical model developed in Task B Step 1 to consider the changes in compressibility, Permeability and geometric features with hydraulic aperture of fault due to mechanical deformation. The effects of the storativity and transmissivity of the fault on the hydro-mechanical behavior such as the pressure distribution, injection rate, displacement and stress of the fault were examined, and the results of the previous step 1 simulation were updated using the modified numerical model. The simulation results indicate that the developed model can provide a reasonable prediction of the hydro-mechanical behavior related to fault reactivation. The numerical model will be enhanced by continuing interaction and collaboration with other research teams of DECOVALEX-2019 Task B and validated using the field experiment data in a further study.

• Journal of Korean Society of Forest Science
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• v.107 no.4
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• pp.351-360
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• 2018

This study was conducted to analyze the responses of chlorophyll contents and growth of Pinus densiflora and Quercus variabilis seedlings on distance from the well and $CO_2$ flux after the artificial $CO_2$ release. From June 1 to 30, 2016, $CO_2$ gas was injected at the rate of $6L\;min^{-1}$ at the study site in Eumseong. Chlorophyll content was analyzed in the middle of July, 2016, and root collar diameter (RCD), height (H), and biomass were measured in May and December, 2016 after planting 2-year-old P. densiflora and 1-year-old Q. variabilis seedlings in May, 2015. The chlorophyll content of P. densiflora seedlings did not show a significant correlation with $CO_2$ flux, whereas the chlorophyll content of Q. variabilis seedlings showed a significant negative correlation with increasing $CO_2$ flux (P<0.05). The RCD and H growth rates of both species showed the significant difference in the distance from the well of the $CO_2$ anthropogenic release treatment. In particular, the RCD and H growth rate of P. densiflora seedlings and the RCD growth rate of Q. variabilis seedlings increased significantly as the seedlings were closer to the well, but the H growth rate of Q. variabilis seedlings decreased significantly. In addition, as the $CO_2$ concentration in the ground increases, ${\Delta}R/S$ ratio increases in both species, suggesting that the high $CO_2$ concentration in the soil promotes carbon distribution relative to the root part. The results of this study can be used as data necessary to monitor the $CO_2$ leakage and physiological and growth responses of both species to leakage of stored $CO_2$ in the future.