• Journal of the Korean Geotechnical Society
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• v.29 no.2
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• pp.47-56
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• 2013

There are many technical problems, which can not be resolved by the concept of saturated soil mechanics. Unsaturated soils show an apparent cohesion due to negative pore pressure and relatively lower permeability due to entrapped air compared to saturated soils. The determination of engineering properties of soils with various moisture content is very important to evaluate shear strength and stability of natural and engineered soils. So various researches should be made on unsaturated soils. Especially, sandy soils are widely distributed near Nakdong river, one of the four rivers where Restoration Projects were carried out. Many structures such as dams, flood control facilities, detention facilities and reservoirs have been built in this area. In this study, unsaturated triaxial compressive tests were conducted on sands or silty sands at Nakdong river in order to provide their fundamental characteristics for design and construction of geotechnical structures. As a result of the tests, the maximum deviator stress increased as the confining stress and matric suction increased. The cohesion increased non-linearly as the matric suction increased, but the angle of internal friction was marginally changed.

• Current Research on Agriculture and Life Sciences
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• v.14
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• pp.85-100
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• 1996

The Studies were conducted to provide the state of mulberry cultivation and it's development in Banguet province (high land) of Philippines. Philippines initiated the sericulture industry with the technical asistance of Japan in 1974 and established mulberry field and sericultural facilities with technical asistance of Korea in 1990 and 1995. The required average of 100 to 150mm per month is not available during the dry season from December to March. Therefore mulching with grass which is available abundantly in the Philippines should be established to conserve moisture, to control soil erosion, surface ran-off and also to increase the humus content in the soil. In chemical properties of mulberry field, the pH value of soil is 4.7, organic matter 1.6%, and available phosphorus 6ppm. Therefore, all fields should do liming and be applied compost. To improve leaf yield for mulberry planted under partial shade area of pine trees, more pruning of pine tree should be done for good sunshining of mulberry, more liming and compost should be applied to improve acidic soil. To control the leaf roller, DDVP and KAFIL are able to be used. When spraying insecticides to control mulberry insect pests, care should be taken to consider the residual effects of chemicals on the leaf. Leaf should be fed to silkworms only after the leaves are free of any residual effects.

• Journal of agriculture & life science
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• v.45 no.4
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• pp.105-112
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• 2011

Nutritional components and antioxidant activities of commercial loquat leaf tea (CLLT) were evaluated. Proximate compositions were as follows; moisture 5.34%, crude protein 8.38%, crude fat 13.26%, nitrogen free extract 46.21%, crude fiber 19.24% and crude ash 7.57%, respectively. Ascorbic acid and total phenolics content of CLLT was 0.47 mg/100 g and 42.55 mg/GAE g, respectively. Mineral elements were Ca 1,624.01 mg/100 g, K 1,099.66 mg/100 g, and Mg 192.70 mg/100 g, respectively. Amino acid contents of CLLT were very rich in glutamic acid 565.98 mg/100 g and deficient in cystine 12.97 mg/100 g. The 2,2'-azino-bis (3-ethylbenzthiazoline-6- sulfonic acid) diammonium salt (ABTS), 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities of hot water extract from CLLT were 72.51% and 90.11%, respectively at a concentration of $1,000{\mu}g/mL$. Reducing power and ferric reducing antioxidant power (FRAP) of hot water extract from CLLT were increased in a dose dependent manner. Therefore, these results suggest that the hot water extract of CLLT possess antioxidant activities and thus it has great potential as a source for functional food such as natural antioxidant.

• Journal of the Korean Society of Marine Environment & Safety
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• v.12 no.2 s.25
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• pp.107-113
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• 2006

Water treatment plant sludge occurred in sedimentation and inverse wash process is generally disposed by ocean dumping or reclamation after dehydration processing using mechanical or natural dry method. Recently, ocean dumping of sludge is limited actually by London Convention. Physical, chemical, and geotechnical characteristics of water treatment plant sludge were analyzed by experiments. The possibilities for recycling of the dehydration sludges as materials for covering sanitary landfill were examined. Experiments performed with sludges mixed with general soil to improved the sludge properties are the hydrometer analysis, the liquid and plastic limit test, the specific gravity test, the compaction test, and the unconfined compression test. The value of ${\gamma}_{dmax}$ is increased and OMC(Optimum Moisture Content) is lessened with mixed sludge. The value of maximum compressive strength and friction angle are increased and the cohesion is decreased with mixed sludge. The ratio between sludge and soil in mixed sludge was 3:7 and the strength of mixed sludge showed $3.6kg/cm^2$. These results satisfy the regulation of U.S. E.P.A regarding materials for covering sanitary landfill.

• Korean Journal of Plant Resources
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• v.13 no.3
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• pp.188-194
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• 2000

This study was carried out to obtain the optimum cultivation conditions of wild ornamental plant resources, Dicentra spectabilis L. The altitude of the habitat was ranged from 630m to 690m in Mt. Gujeol. Most of the habitat faced toward the northeast aspect and the gradient was ranged from 25 to 33 degrees. The light intensity of Dicentra community was 14,000lux on the average, and it was tendency to decrease by foliation of other woody plants. The appearance number of Dicentra per quadrat was 30 individuals on the average, and total appearance species in all quadrat surveyed was 52 taxa. Among them, Quercus mongolica, Lindera obtusiloba, Corylus heterophylla, Cornus controversa, woody plants, Corydalis speciosa, Pseudostellaria heterophylla, Artemisia keiskeana, Dryopteris crassirhizoma, Arisaema amurense var. serratum, Carex siroumensis, and Chloranthus japonicus, herbaceous plants, were showed as dominant species. Soil acidity in the habitat was 5.15 to 5.96, and average content of soil moisture was 32.6%. The contents of average organic matter, $P_2O_5$, K, Ca, and Mg were 1.99%, 14mg/kg, 0.55me/100g, 15.2me/100g, and 3.3me/100g, respectively. Electron conductivity was ranged from 0.50 to 0.76dS/m. Also, the average air temperature of May and June was 14.2$^{\circ}C$ and 19.4$^{\circ}C$, respectively.

• Journal of Life Science
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• v.29 no.3
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• pp.362-368
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• 2019

For the practical application and development of biopolymer flocculant Biopol32 produced by Pseudomonas sp. GP32, its flocculation effect on wastewater from food processing, slaughter houses, and the dyeing industry was investigated. In the food processing wastewater, Biopol32 led to a chemical oxygen demand (COD) reduction rate of 70% and a suspended solid (SS) removal rate of 49% at pH 6.0. In the slaughter house wastewater at pH 4.0, a COD reduction rate of 61% and SS removal rate of 91% were observed, and in the dyeing wastewater, the rates were 72% and 92%, respectively, at pH 5.0. The size of floc formed during the flocculation process was 10 mm at a final concentration of 20 ppm, and the dehydration efficiency was 62%. In both the bioflocculant Biopol32 group and a PAA synthetic flocculant group, optimal flocculant concentration that yielded the best overall dehydration efficiency was 20 ppm, and, at this concentration, the shortest filtration time to reach the natural critical moisture content of 78.1% was attained.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2020.08a
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• pp.11-11
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• 2020

Background : The genus Cypripediums are typically adapted to the low temperature and cold climates of the high land in Korea. The species which were reported in Korean peninsula are C.japonicum, C.macranthos, C.calceolus and C.guttatum. We had already reported the successful germination of the C.macranthos and C.guttatum. The small spotted lady's slipper orchid(C.guttatum) is most endangered plants to extinction of which population was reported less than 100 in Korea. The objective of the present research is restoration of the C.guttatum in ex situ and adaptation in high land and nursery. Methods and Results : The 350 seedlings of C.guttatum were transplanted in soil at alpine area(altitude 750m) and the nursery of Korea National Arboretum(KNA) in YangPyeong city on May 2019 and 2020 in order to verify the possibility of ex situ restoration. The sprouted ratio of the seedlings were less than 10% in the alpine area and 83% in the nursery of KNA. The reasons of the diverse survival ratio are presumed as the low moisture content in the soil and heavy shade of the alpine area. The 15 cypripedium species and 29 hybrids were also effectively adapted in the KNA rare plant garden. Conclusion : These results demonstrated the difficulties of the restoration for small spotted lady's slipper orchid in the natural habitation. From the above results, we may conclude that the critical factors of the genus Cypripedium are intensive care for the fragile seedlings during the 1^st year acclimatization.

• Korean Journal of Agricultural Science
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• v.5 no.2
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• pp.127-135
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• 1978

For improvement and new design of tillage equipments, indoor test is very useful and more desirable than outdoor because the experiment of outdoor is very difficult and its cost is expensive. This study was carried out to determine the physical properties of artificial soil suitable for the indoor test with the soil bin manufactured at the workshop of the Dept. of Agricultural Machinery Engineering. The artificial soil being studied was made with very similarity to the natural soil of the experimental plots of Chungnam National University, and it consist of 39.35 percent, by weight of bentonite and 48.10 percent of sand with 12.55 percent of SAE 10W oil. The results are summarized as follows: 1. Bulk density increased with increasing number of rolling, and its relationship could be expressed. $y=1.073200+0.070780x-0.002263x^2$ where, y=bulk density ($g/cm^3$), x=number of rolling. These results could be explained that the effect of rolling velocity on the bulk density was not singnificant in the range of 4.5~10.4 em/sec. 2. The absolute soil hardness depended directly upon number of rolling, and their relationship could be expressed by the equation. $y=37.74(0.64 +0.17x-0.0054x^2)/(3.36-0.17x-0.0054x^2)^3$. where, y=absolute soil hardness($kg/cm^3$), x=number of rolling. 3. Relationship between the bulk density and absolute soil hardness could be expressed by the equation; $y=37.74(2.46x-2.02)/(6.02-2.46x)^3$. where, y=absolute soil hardness, x=bulk density. 4. The cohesion and the angle of internal friction of artificial soil were increased with increasing its bulk density. According to the cohesion and angle of internal friction, at the range of 1.60~1.75 ($g/cm^3$) of bulk density, this artificial soil was similar with sandy loam of 29.5% moisture content of natural soil. 5. Sliding-fricfion coefficient of steel plate on the artificial soil was 0.3~0.4 and rubber plate on it is 0.64~0.72. Those values were very similar with those of natural soil being studies by many others.

• Korean Journal of Food Science and Technology
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• v.8 no.3
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• pp.136-140
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• 1976

To investigate the preservability of Tongil, three types(rough, brown and milled rice) of Tongil and the common variety (being composed of typical varieties) in Korea were stored at a ambient and a low temperature $(15^{\circ}C)$ warehouse from April to October of each year for three years (1972-1974). The results obtained are described as follows; 1) Temperatures of atmosphere and the natural temperature warehouse changed in the same way. 2) Similar changes of relative humidity were observed in atmosphere and both warehouses. 3) Equilibrium moisture content of Tongil at $25^{\circ}C$ was 0.55 % lower in rough and brown rice. 0.33% lower in milled rice than each type of the common variety. 4) Weight loss rate in the natural temperature storage and in the low temperature storage was 1.35% and 0.74% after 6 month storage. 5) The change of fat acidity in browe rice was greater than any others (rough and milled rice). 6) Hardness of Tongil was 1.64kg higher than that of the common variety. 7) Germination rate was about the same during the low temperature storage, but that of brown of the natural temperature storage was abruptly decreased to $23%{\sim}37%$ after August. As a result, it is possible Tongil is applicable to the long-term storage of rice due to Tongil's superior preservability.

• The Journal of Engineering Geology
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• v.16 no.4 s.50
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• pp.359-371
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• 2006

In this study, the soil characteristics are analyzed using the result of various soil tests as an object of the soil layer of natural slopes in landslides areas composed with gneiss, granite, and the tertiary sedimentary rock. To investigate the soil characteristics according to landslide and non landslide areas, soils are sampled from Jangheung, Sangju and Pohang. The landslides at three areas are occurred due to heavy rainfall in same time. The geology of Jangheung area, Sangju area and Pohang area is gneiss, granite, and the tertiary sedimentary rock, respectively. On the basis of the landslide data and the result of soil test, the soil characteristics at the landslide area and the differentiation between landslide area and non landslide area are analyzed. However soil characteristics have a little differentiation to geological condition, the uniformity coefficient and the coefficient of gradation of soils at the landslide area is larger than those of soils at the non landslide area. Also, the proportion of fine particle of soils at the landslide area is higher. The plastic limit of soils sampled from the granite and the sedimentary rock regions is larger than that sampled from the gneiss region. However the liquid limit is irrelevant to the geological condition. Also, the consistency of soils at the landslide area is smaller. The natural moisture content of soils in the sedimentary rock regions is larger than that of the granite and gneiss. It is mainly influenced by mineral composition, soil layer structure, weathering condition, and so on. The soils sampled from landslide area have higher porosity and lower density than those from non landslide area. It means that the soils of landslide area have poor particle size distribution and loose density. Therefore, the terrain slope with poor distribution and loose density is vulnerable to occur in landslides. Also, landslides are occurred in the terrain slope with high permeability. The permeability is mainly influenced by the soil characteristics such as particle size distribution, porosity, particle structure, and the geological origins such as weathering, sedimentary environment. Meanwhile, the shear strength of soils is little difference according to the geological condition. But, the internal friction angle of soils sampled from the landslide area is lower than that of soils from the non landslide area. Therefore, the terrain slope with low internal friction angle is more vulnerable to the landslide.