• Korean Journal of Ecology and Environment
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• v.37 no.3 s.108
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• pp.319-331
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• 2004

This study was conducted to evaluate the ecological impact of freshwater bivalve (Corbiculidae) on plankton communities in experimental enclosure systems (2 m ${\times}$ 2 m ${\times}$ 2 m). During the acclamation period of one month, cyanobacteria, including Microcystis viridis and Microcystis aeruginosa, dominated in both control and treatment enclosures with no noticeable density difference. After the addition of 100 mussels, dominant species of phytoplankton shifted from Microcystis to Scenedesmus in concert with slight decrease in the cell density and the increase of N/P ratio. However, cell density in the control quickly increased, accompanied with changes of dominant species to Oscillatoria spp. With the introduction of additional 500 musseles in the treatment enclosure, dominant phytoplankton species in both enclosures were replaced with Selenastrum spp. and Cryptomonas sp. In the initial stage, the total zooplankton abundance in the control was higher than that of treatment, but it was reversed after the addition 100 mussels. After mussel density increased up to 600 indivisuals, zooplankton density in the treatment decreased with dominance of small taxa, such as rotifers and nauplius. However, abundance and carbon biomass of large zooplankton, such as Bosmina longirostris and Diacyclops thomasi were maintained in a high level compared with those of control. During the study period, Chl. a concentration in mussel treatment and control increased with DIP and $NH_3-N$, respectively. Due to the increase of $NH_3-N$, especially after the introduction of additional 500 mussels, nitrogen limitation did not occur in the treatment enclosure in contrast with strong nutrient limitation occurred in the control. These results indicate that filter-feeding Corbicula could exert important impact on nutrient recycling and plankton community structure in a freshwater ecosystem, through direct feeding and competition for the same food resource as zooplankton on one hand, and through alteration of nutrient availability on the other.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.6
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• pp.1245-1251
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• 2011

As a result of the growing livestock industry, varieties of organic solid and waste biomass are be generated in swine breeding and slaughtering stages. Anaerobic digestion is a promising alternative for the treatment of livestock waste biomass, as well as for the material recovery and energy production. Objectives of this study were to analyze the biochemical methane potential of swine waste biomasses that were generated from swine pen and slaughterhouse and to investigate the material recovery and methane yield per head. As pig waste biomass, swine slurry, blood, intestine residue, and digestive tract content were collected for investigation from pig farmhouse and slaughterhouse. The $B_{th}$ (Theoretical methane potential) and $B_0$ (Biochemical methane potential) of swine slurry generating in swine breeding stage were 0.525 and $0.360Nm^3\;kg^{-1}-VS_{added}$, the ratio of degradation ($B_0/B_{th}$) was 68.6%. $B_{th}$ of blood, intestine residue, and digestive tract content were 0.539, 0.664, and $0.517Nm^3\;kg^{-1}-VS_{added}$, and $B_0$ were 0.405, 0.213, and $0.240Nm^3\;kg^{-1}-VS_{added}$, respectively. And the ratio of degradation showed 75.1, 32.1, and 46.4% in blood, intestine residue, and digestive tract content. Material yield of swine waste biomass was calculated as TS 73.79, VS 46.75, TN 5.58, $P_2O_5$ 1.94, and $K_2O$ $2.91kg\;head^{-1}$. And methane yield was $16.58Nm^3\;head^{-1}$. In the aspect that slaughterhouse is a large point source of waste biomass, while swine farmhouse is non-point source, the feasibility of an anaerobic digestion using the slaughtering waste biomass need to be assessed in the economical aspect between the waste treatment cost and the profitable effect by methane production.

• Journal of the Korea Organic Resources Recycling Association
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• v.27 no.1
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• pp.49-56
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• 2019

This experiment was conducted to select an optimum application rate of blended biochar pellet as slow release fertilizer during cabbage cultivation. The blended biochar pellet made with a combination(4:6) of biochar and pig manure compost with unloading N, P, K solutions for adjusting about 9% of total nitrogen(TN). The treatments were consisted of the control as recommended application rates for cabbage cultivation in National Institute of Agricultural Sciences, N 40%, N 40% and 0.07M MgO and N 60 % of the blended biochar pellet, respectively, based on nitrogen application of recommended rates to cabbage cultivation. Changes of $NH_4-N$, $NO_3-N$, $P_2O_5$ and $K_2O$ concentrations in the soil and growth characteristic and yield components were investigated and observed during the cabbage cultivation. The experimental result shown that contents of $NH_4-N$, $NO_3-N$ and $K_2O$ of soil in the N 40% were significantly difference(p<0.01) with the control. $P_2O_5$ concentrations of soil in the N 40% were highest among the treatments. The fresh weight per cabbage in the N 40% was not significantly different(p>0.05) from the control, but in the N 40% and 0.07M MgO and N 60% was lower than that of the control. It was considered that an optimum blended biochar application rate for cabbage cultivation was 40% of recommended nitrogen application.

• Korean Journal of Plant Resources
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• v.35 no.5
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• pp.594-606
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• 2022

This study was conducted to figure out the environment factors including vegetation structure and soil characteristics in natural habitats of Sageretia thea, and offers the basic information for habitats conservation and proliferation. The natural habitats of Sageretia thea were located at altitudes between 0~370 m with inclinations ranged as 3~35°. Through the vegetation research, the dominant species of tree layers were found to be divided into four communities. Cornus macrophylla (Com. I), Pinus thunbergii - Cinnamomum camphora (Com. II), Machilus thunbergii (Com. III), and Pinus thunbergii (Com. IV). The Species diversity (H') was 1.397~1.455, evenness (J') was 0.972~0.986, and dominance (D) was found to be 0.014~0.028. As a result of the physicochemical characteristics of soils, habitats soil mainly consisted of sandy soil and sandy loam soil. The average soil pH was 5.28~5.98, electronic conductivity was 0.22~63 ds/m, soil organic matter was 13.33~19.33 cmol⁺/kg, Exchange cations were appeared in the order of Ca²⁺, Mg²⁺, K⁺, and Na⁺. The Ordination result showed that Correlation coefficient between communities and environmental factors were significantly correlated with 4 main factors altitude, electronic conductivity, cation exchange capacity, exchangeable Na⁺. As expected, The result of this study will be helpful information on the preservation and mass production for use.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.2
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• pp.212-223
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• 2022

For the remediation and restoration of contaminated sediment at the West Sea-Byeong dumping site, dredged materials was dumped in 2013, 2014, 2016, and 2017. The physicochemical properties and benthic fauna in surface sediments of the capping area (5 stations) and natural recovery area (2 stations) were analyzed annually from 2014 to 2020 to evaluate the capping effect of the dredged materials. The natural recovery area had a finer sediment with a mean particle size of 5.91-7.64 Φ, while the sediment in the capping area consisted of coarse-grained particles with a mean particle size of 1.47-3.01 Φ owing to the capping effect of dredged materials. Considering that the contents of organic matters (COD, TOC, and TN) and heavy metals in the capping area are approximately 50 % lower (p<0.05) than that in the natural recovery area, it is judged that there is a capping effect of dredged materials. As a result of analyzing macrobenthic assemblages, the number of species and ecological indices of the capping area were significantly lower than that of the natural recovery area (p<0.05). The number of species and ecological indices at the capping area were increased for the first four years after the capping in 2013 and 2014 and then tended to decrease thereafter. It is presumed that opportunistic species, which have rapid growth and short lifetime, appeared dominantly during the initial phase of capping, and the additory capping in 2016 and 2017 caused re-disturbance in the habitat environment. In the natural recovery and capping areas, Azti's Marine Biotic Index (AMBI) was evaluated as a fine healthy status because it maintained the level of 2^nd grades (Good), whereas Benthic Pollution Index (BPI) remained at the 1^st and 2^nd grade. Therefore, capping of dredged materials for remediation of contaminated sediment in the dumping site has the effect of reducing the pollution level. However, in terms of the benthic ecosystem, it is recommended that the recovery trend should be monitored long-term. Additionally, it is necessary to introduce an adaptive management strategy when expanding the project to remediate the contaminated sediment at the dumping area in the future.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.297-306
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• 2023

Saemangeum Lake is the largest artificial lake in Korea. The continuous deterioration of lake water quality necessitates the introduction of novel water quality management strategies. Therefore, this study aims to identify the spatiotemporal water quality characteristics of Saemangeum Lake using data from the National Water Quality Measurement Network and provide basic information for water quality management. In the water quality parameters of Saemangeum Lake, water temperature and total phosphorous content were correlated, and salt, total nitrogen content, pH, and chemical oxygen demand were significantly correlated. Other parameters showed a low correlation. The spatial principal component analysis of Saemangeum Lake showed the characteristics of its four zones. The mid-to-downstream section of the river affected by freshwater inflow showed a high nutrient salt concentration, and the deep-water section of the drainage gate and the lake affected by seawater showed a high salt concentration. Two types of water qualities were observed in the intermediate water area where river water and outer sea water were mixed: waters with relatively low salt and high chemical oxygen demand, and waters with relatively low salt and high pH concentration. In the principal component analysis by time, the water quality was divided into four groups based on the observation month. Group I occurred during May and June in late spring and early summer, Group II was in early spring (March-April) and late autumn (November-December), Group III was in winter (January-February), and Group IV was in summer (July-October) during high temperatures. The water quality characteristics of Saemangeum Lake were found to be affected by the inflow of the upper Mangyeong and Dongjin rivers, and the seawater through the Garuk and Shinshi gates installed in the Saemangeum Embankment. In order to achieve the target water quality of Saemangeum Lake, it is necessary to establish water quality management measures for Saemangeum Lake along with pollution source management measures in the upper basin.

• The korean journal of orthodontics
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• v.36 no.5
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• pp.339-348
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• 2006

Objective: With development of the skeletal anchorage system, orthodontic mini-implant (OMI) assisted on masse sliding retraction has become part of general orthodontic treatment. But compared to the emphasis on successful anchorage preparation, the control of anterior teeth axis has not been emphasized enough. Methods: A 3-D finite element Base model of maxillary dental arch and a Lingual tipping model with lingually inclined anterior teeth were constructed. To evaluate factors influencing the axis of anterior teeth when OMI was used as anchorage, models were simulated with 2 mm or 5 mm retraction hooks and/or by the addition of 4 mm of compensating curve (CC) on the main archwire. The stress distribution on the roots and a 25000 times enlarged axis graph were evaluated. Results: Intrusive component of retraction force directed postero-superiorly from the 2 mm height hook did not reduce the lingual tipping of anterior teeth. When hook height was increased to 5 mm, lateral incisor showed crown-labial and root-lingual torque and uncontrolled tipping of the canine was increased.4 mm of CC added to the main archwire also induced crown-labial and root-lingual torque of the lateral incisor but uncontrolled tipping of the canine was decreased. Lingual tipping model showed very similar results compared with the Base model. Conclusion: The results of this study showed that height of the hook and compensating curve on the main archwire can influence the axis of anterior teeth. These data can be used as guidelines for clinical application.

• Journal of Korean Medical classics
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• v.3
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• pp.218-247
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• 1989

As mentioned above, I got the next conclusion since I had considered the medical contents of the ancient period(上古時代) and the era of the old-Korea(古朝鮮時代) through several bibliographic records. 1. There were Pung-baeg(風伯), Uh-sa(雨師), Un-sa(雲師) that were the names of the governmental officials during the ancient period of Whan-ung(桓雄). Among them, Uh-sa specially managed the treatment for diseases. When we think of the significance of Pung(風)-which means the winds, Uh(雨)-which means the rain, Un(雲)-which means of clouds, we will find out that the human life will be affected by all kinds of phenomena of the nature. So I can infer that ancestries could prevent and treat diseases with adjusting them tn the changes in the weather. 2. There were five government officials(五事) in the ancient period of Whan-ung(桓雄上古時代). They are Uh-ga(牛加), Ma-ga(馬加), Ku-ga(狗加), Cheo-ga(猪加) and Yang-ga(羊加), and had charges of five important duties. Among them, Cheo-ga was set to a charge of treatment for diseases. So we can notice that there existed people who treated for diseases professionally. When we think of the meanings of Uh(牛)-which intends cows or bulls. Ma(馬)-which intends horses, Ku(狗)-which intends dogs, Cheo(猪)-which intends wild boars and Yang(羊)-which intends sheep, we can see that livestocks would be raised at that time, and they came to have more chances to digest meat. Since the digestion of meat became to be a burden on the stomach and the intestines, it might cause a lot of indigestive troubles. 3. When I compared Tan-gun Pal-ga(檀君八加) with the Oh-ga(五加) in the ancient period of Whan-ung(桓雄上古時代), I could tell that the community of Tan-gun's period is more advanced and specialized than one of Whan-ung's. When I think of the next sentence ; "The Prince Imperial, Bu-u(夫虞) become to be a Ro-ga(鷺加), who treat for diseases professionally.", I am sure that the treatment for diseases was more importment than any other things, because he was the third son of Tan-gun(檀君). 4. According to Tan-gun(檀君) mythology, Whan-ung(桓雄) came down from the heaven of the pure Yang(純陽) to the earth and then changed into a man who had had more Yang(陽) than Yin(陰). And a bear came up from the underground(or the cave) to the ground and then changed into a women who had had more Yin(陰) than Yang(陽). So both of them became to hold together. This story implicated that ancestors had taken a serious view of each of them, namely the ancestors didn't give the ascendance to the one side of them, and made much account of the mutual harmony. So I am sure that this fact coincided with the basic theories of oriental medical science. To refer to two proverbs of Tan-gun mythology that are "Ki-Sam-Chil-Il(忌三七日)" which means caring for twenty one days, and "Pul-Gyon-Il-Gwang-Baeg-Il(不見日光百日)" which means keeping indoors for one hundred days, I can tell you that "twenty-one-day" involves the principle of the birth of life, and "one-hundred-day" contains a preparatory period or the period of death to bear another life. 5. From the medical stuff, such as wormwood(艾), garlic(蒜), or wonder-working herbage(靈草), that had been written at the bibliographic papers of the ancient period(上古時代) and the era of the old-Korea(古朝鮮時代), I consider that many people might get a lot of women's diseases, indigestive troubles, and other diseases that were caused by the weakness, but with using various spices, such as the leaves of water pepper(蔘), they could prevent the occurrance of all kinds of diseases previously. So I regard this treatment as the medicine from food. 6. One of the sayings at Nae-gyong(內經) is that "The stone accupuncture(砭石) came from the orient." We can see both "wonder-wor-king wormwood(靈草)" and "dried wormwood(乾艾)" in the several bibliographic papers of the ancient history of the old-Korea(朝鮮上古史). From these records, I can be convinced that ancestors would utilize the acupuncture(針) and the moxa cautery(灸) to cure a patient of a disease. 7. Even though someone claimed that the book, "medical science and chemistry(醫學化學)" and "medical treatment(醫學大方)" had had been written during the ancient period of the old-Korea(上古朝鮮時代), such a fact can't have been ascertained historical evidence. But it has been handed down that there existed the original phonetic alphabet, such as the "Ka-Im-To alphabet(加臨土文字)" at that time. The terms about the diseases, which had been occurred at the community of the old-Korea(古朝鮮地域), were recorded fragmentarily at other records after that time. The origin of confucianism came from the race of the eastern barbarians, and Tae-Ho-Pok-Hi(太嗅伏義) and the king. Sun(舜) came from the eastern barbarians, too. The divination of tortoise shells at the country of Un(殷) is another from which was developed at the eastern barbarians' fortune-telling of animal bones. From these facts, I can infer that, by all means, they might record the medical knowledge which had been stored for thousands of years while contacting with china directly.

• Journal of The Korean Society of Grassland and Forage Science
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• v.15 no.3
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• pp.175-185
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• 1995

This experiment was carried out to investigate the optimum rates of animal excreta(cattle slurry-N) for the highest dry matter production and improve the nutritive values of reed canarygrass with different cutting frequency. The results are summarized as follows; The highest relative dry matter yields for annual dry matter yield were 42.2% and 45.2% at 3rd cut in 3 and 4 cuttings, and 34.7% at 4th cut in 5 cuttings, respectively. The annual dry matter yields of non slurry-N application plot showed were from 6.8 tons to 8.0 tons/ha in all cutting frequencies. The highest annual dry matter yield obtained was in 3 cuttings. The annual dry matter yield increased with an increase of applied rates of slurry-N in all cutting frequencies. Annual dry matter yield was produced by 3.3 tons/ha at rates of 90 kg N/ha/cut in 3 cuttings, and more 1.7 tonsha and 2.4 tons/ha at rates of 30 kg N/ha/cut in 4 and 5 cuttings than that of non slurry-N application plots. The contents of crude protein were 12.01% and 15.0% at rates of 90 kg N/ha/cut in 3 and 4 cuttings, and 16.59% at rates of 120 kg N/ha/cut in 5 cuttings, respectively. On the contrary, the content of acid detergent fibre(ADF) showed the lowest values at same rates of slurry-N application in each cutting. J. The average content of crude protein was significantly increased with cutting frequencies, and they were 11.43%, 13.53% and 15.53% in 3, 4 and 5 cuttings, respectively. The average contents of acid detergent fibre(ADF) were 40.27%, 40.53% and 37.06% in 3, 4 and 5 cuttings. The values of 5 cuttings were significantly lower than other cutting frequencies, but the values of acid detergent fibre(ADF) was not significantly different between 3 and 4 cuttings. 6. The efficiency of dry matter production to slurry-N application rates showed the highest values of 18.9 kg and 15.7 kg DM/kg N at rates of 30 kg N/ha/cut in 3 and 5 cuttings, and 16.3 kg DM/kg/ N at rates of 90 kg N/ ha/cut in 4 cuttings. The efficiency of total nitrogen yield to slurry-N application rates were the highest values of 0.51 kg and 0.43 kg W k g N at rates of 30 kg N/ha/cut in 4 and 5 cuttings, and 0.52 kg TN/kg N at rates of 90 kg N/ha/cut in 3 cuttings, respectively. 7. The ranges of economic slurry-N rates were estimated as the 107.2-151.0 kglha, 359.1-375.7 kgha and 160.3-236.9 kg/ha in 3, 4 and 5 cuttings, and marginal dry matter yields were 9.6-10.0 tons/ha, 12.4-12.6 tons/ha and 9.0-9.7 tons/ha in 3, 4 and 5 cuttings, respectively. 8. The limiting sluny-N application rates to maintain the highest dry matter yields were estimated to be 420.0 kg/ ha, 440.6 kg/ha and 666.3 kg/ha in 3, 4 and 5 cuttings.

• Economic and Environmental Geology
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• v.40 no.5
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• pp.605-622
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• 2007

Elemental, Rock-Eval pyrolysis and isotopic analysis of the core sediments from the northwestern and eastern Ulleung Basin of the East were carried out to identify their geochemical characteristics, spatial and vertical variation and origin of organic matter in Upper Quaternary sediments from the northwestern and eastern Ulleung Basin of the East Sea. TOC, m and TS did not show spatial variation between the sampling locations whereas they showed systematic vertical variation associated with MIS stages related to the sea-level change of the East Sea. It is suggested that these past changes of sea-level influenced the sedimentary depositional environments and/or diagenesis which resulted the patterns observed in this study. Based on the results of TOC/N, TS/TOC, ${\delta}^{13}C_{org}\;and\;{\delta}^{15}N_{org}$ analysis, organic matters in the study area appears to be predominantly originated from the marine algae rather than land plant and deposited under normal marine oxic condition during MIS I and MIS III period, and under euxinic/anoxic condition during MIS II period. TOC/N, ${\delta}^{13}C_{org}\;and\;{\delta}^{15}N_{org}$ have a relatively constant value irrespective of MIS stages, implying that the organic matter source does not change by the sea-level fluctuations. However, the results of Rock-Eval pyrolysis indicates that the organic matter is in immature stage and originated from land-plant (Type III), locating in the immature stage land plant (Type III). Similar differences were reported from other areas such as the Atlantic Ocean, Iberia Abyssal Plain, Mediterranean Sea, suggesting that Rock-Eval method does not exactly reflect the characteristic of immature organic matters. Accordingly, the application of Rock-Eval pyrolysis for delineating the source of immature organic matters should be approached with caution and all other geochemical proxies should be considered altogether at the same time.