• Journal of Sericultural and Entomological Science
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• no.11
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• pp.1-14
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• 1970

The following results were obtained by surveying the productivity of mulberry fields in Korea. 1. The productivity of mulberry field per 10a in which cocoon can be yield belongs to the range of 9.8∼105kg, and among them the productivity of 20 to 60kg was chiefly distributed. And their average was 50.2kg. 2. In general, the larger the mulberry field in scale per a person is, the lower the productivity of it is, but about 6.6 ares per a person was estimated to be economic scale for high productivity. 3. As far as the texture of soil is concerned, sandy-loam and loam contained a capacity of higher productivity while others like clay and sand that of lower productivity, And the depth of surface soil must be at least 50cm, although 70cm's depth of surface sail could bring about high productivity. 4. Fertilization of 900kg's compost on planting and 1,200kg's that after planting could enhance the productivity, because the use of compost have a positive relation to the productivity. 5. The greater the number of farmer's domestic animals is as a source of organic matter the higher the productivity is. 6. In the case of fertilization of 1,200kg compost, the amount of 20kg's nitrogen per 10 ares as chemical manure was best for high productivity. However, fertilization of 14.7kg's nitrogen as average amount of that, which is far below the standard amount, had been a factor to reduce the productivity of mulberry field. 7. In pruning the low-cut form resulted in high productivity, but as their shape become taller due to the lack of techniques, they were turned out to be non head pruning, thus to produce poor harvest of leaves. 8. The pure mulberry fields showed better productivity than others such as wide and narrow ridge planting and inter-crop planting. 9. As for the degree of planting density, at least 800 trees per 10 ares should be planted to increase the productivity, although the planting of 713 trees per 10 ares could be possible in case of the low stemmed pruning. 10. The hole and tranch in planting must be digged as wider and dipper as possible far the better growth of mulberry tree. 11. On the whole, varieties like NOsang and Y oung-cheun choowoo had a tendency of lower productivity.

• International Journal of Highway Engineering
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• v.10 no.4
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• pp.103-116
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• 2008

In this study, in-situ testing method, Dynamic Cone Penetration Test(DCPT) was presented to establish a new compaction control criteria with using mechanical property like elastic modulus instead of unit weight for field compaction control. Soil chamber tests and in-situ tests were carried out to confirm DCPT tests can predict the designed elastic modulus after field compaction, and correlation analysis among the DCPT, CBR and resilient modulus of sub grade were performed. Also, DCPT test spacing criteria in the construction site was proposed from the literature review. In the result of laboratory tests, Livneh's equation was the best in correlation between PR of DCPT and CBR, George and Pradesh's equation was the best in the predicted resilient modulus. In the resilient modulus using FWD, Gudishala's equation estimates little larger than predicted resilient modulus and Chen's equation estimates little smaller. And KICT's equation estimates the modulus smaller than predicted resilient modulus. But using the results of laboratory resilient modulus tests considering the deviatoric and confining stress from the moving vehicle, the KICT's equation was the best. In the results of In-situ DCPT tests, the variation of PR can occur according to size distribution of penetrate points. So DCPT test spacing was proposed to reduce the difference of PR. Also it was shows that average PR was different according to subgrade materials although the subgrade was satisfied the degree of compaction. Especially large sized materials show smaller PR, and it is also found that field water contents have influence a lot of degree of compaction but a little on the average PR of the DCPT tests.

• Korean Journal of Environment and Ecology
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• v.32 no.2
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• pp.231-243
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• 2018

This study was conducted to determine and compare the perceived number of users (PNU) and evaluative standards for each type of visitors to "Healing Field" of Jangseong Pyunbaek Healing Forest (JPHF). Data were collected from 158 samples selected by convenient sampling method from the users of "Healing Field" in JPHF during September 2017. Visitors to "Healing Field" consisted of 49.3% for recreation (VR), 15.3% for healing (VH), and 35.3% for both recreation and healing (VRH). Respondents' average PNU was 23.8 (median: 20.0), and the range of average PNU by visitor type was 21.1-27.8 (median: 20.0). Respondents' PNU showed low correlations with perceived crowding (PC) (r=0.23) and perceived interference of healing experience (PIHE) (r=0.20). There were no differences in the optimal number of users (ONU) of "Healing Field" among the types of visitors. The overall average ONU was 28.9(median: 25.0), and the range of average ONU by types of visitors was 25.4-31.4 (median: 25.0-27.5). The overall maximum acceptable number of users (MANU) was 38.1, and MANU for VR, VH, and VRH was 36.9, 32.0, and 38.0, respectively. Respondents' mean PC was 2.73 (SD: 3.26, 9-point scale) while mean PIHE was 3.26 (SD: 1.77, 9-point scale). The VRH group showed a higher PC and PIHE than the VR group. The group with greater PNU than ONU showed higher PC and PIHE than the other groups. Based on the results, this paper presented some managerial implications, discussed the limitations of the study, and suggested the further studies.

• Journal of Korean Society of Forest Science
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• v.89 no.2
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• pp.208-215
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• 2000

In order to improve 'Salso' method (conventional tapping method) which was very inefficient in the aspects of collection time and labor, this study was carried out to investigate the effect of the application date and the distance from treatment point in the lactree(Rhus verniciflua) treated with 10% CEPA and to decide the possibility of application of the technique in the field. Bark thickness was significantly increased to the part 40cm above and below the treatment point, but urushiol content was increased to the part 20cm above and 10cm below the zone treated with 10% CEPA. The urushiol content of the bark was highest at 5cm above the treated zone and decreased in the order of 10, 20, and 40cm. And the urushiol contents of the bark of the upper part were higher than that of the low part. The effects of CEPA on bark thickness were similar to urushiol contents. Urushiol production of lactree is highly dependent on climatic conditions and particularly on the precipitation, and duration of sunshine. Ten percent of CEPA-lanolin pastes which was treated on June 16 affected bark anatomy and urushiol contents, while the treatment on August 24 did not affect. In the Rhus verniciflua treated with 10% CEPA, the urushiol contents was initially increased from 7 days after treatment, continued for the 4 weeks, and then slight decrease occurred at 5 weeks after the treatment. We measured a total sap yield by Salso method in lactree treated with 10% CEPA. By applying 10% CEPA, the sap yield was increased 3-4 times compared to that of untreated trees in the first tapping. But the relative ratio was gradually decreased from the second tapping to sixth, and after seventh tapping, the untreated trees secreted more sap than the treated trees. We discussed about the causes.

• Journal of Soil and Groundwater Environment
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• v.6 no.3
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• pp.53-59
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• 2001

There is a lot of method to manage the insanitary landfill but vertical cutoff walls have been widespreadly used and were installed into the subsurface to act as a barrier to horizontal groundwater flow, The stabilized material such as specialized cement or mixed soil with additives has been generally applied for the materials of the deep soil mixing barrier in korea. The amount of the stabilized material is dependent on the field conditions, because the mixing ratio of the material and the field soil should achieve a requirement in the coefficient of permeability, lower than 1.0$\times$$10^{7}$cm/sec. This study determined the quantity and optimized function ratio of the stabilized material in the formation process of the mixed barrier that was added with stabilized material on the field soil classified into SW-SC under USCS (Unified Soil Classification System). After that the fly ash and lime were selected as an additives an that could improve the function of the stabilized material and then the method to improve the functional progress in the usage of putting into the stabilized material as an appropriate ratio was studied and reviewed. The author used the flexible-wall permeameter for measuring the permeability and unconfined compressive strength tester for compressive strength, and in the view of environmental engineering the absorption test of heavy metals and leaching test regulated by Korean Waste Management Act were performed. As the results, the suitable mixing ratio of the stabilized material in the deep soil mixing barrier was determined as 13 percent. To make workability easy, the ratio of stabilized material and water was proven to be 1 : 1.5. With the results, the range of the portion of the additives(fly ash : lime= 70 : 30) was proven to be 20-40% for improving the function of the stabilized material, lowering of permeability. In heavy metal absorption assessment of the mixing barrier system with the additives, the result of heavy metal absorption was proved to be almost same with the case of the original stabilized material; high removal efficiency of heavy metals. In addition, the leaching concentration of heavy metals from the leaching test for the environmental hazard assessment showed lower than the regulated criteria.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.916-921
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• 2011

This study was carry out on a Jang-Won series (fine loamy, mixed, mesic family of typic fragipan) that were established and classified as a fragipan soil in Korea. The morphological, physical, chemical and minerals characteristics of Jang-Won series were studied to determine the genesis of fragipan soils in natural environment. Each sample was analyzed for its physical, chemical and mineralogical characteristics. The particle size distribution of samples was measured using pipette method. Clay minerals were investigated on parallel-oriented specimens of the clay fraction ($<2{\mu}m$) from each horizon, separated by sieving and centrifugation, using X-ray diffraction (XRD) analysis. Micromorphological observations were made on thin sections prepared from soil blocks impregnated with Crystic Resin, cut and ground to less than $30{\mu}m$ in thickness, and finally polished with diamond paste. Most horizons have pH values in the range of fewer than 5.0 and have very low base-saturation values. Their textural classification ranges from silt loam to loam, the lower horizons being the finer. The clay fraction revealed the occurrence of illite, kaolinite, chlorite and vermiculite. The micro-morphological analysis carries out thin sections from each soil profile. The silt concentrations occur as extremely dense and homogenous bands or zones of silt-sized materials, brownish in colour in plane-polarized light and anisotropic in cross-polarized light, surrounding or adhering to skeleton grains. The genesis of fragipan in the Jangweon series assumed composition of clay fraction rather than silt concentration. Therefore, this results suggested an authentic interpretation which Jangweon series is classification as Typic Fragiochrepts.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.425-433
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• 2019

In this study, a simple method of calculating the passive earth pressure coefficient, which is based on the limit equilibrium method, was proposed and the calculated earth pressure coefficients were compared with those of several researchers. The angle of the linear failure surface, which is combined with the logarithmic spiral arc, to the failure surfaces of the passive zone was derived and the whole passive thrust acting on the Rankine passive zone was considered in the proposed method instead of considering the horizontal component of passive thrust. The variations of the passive earth pressure coefficients of the proposed method showed the same tendency as that of the Coulomb's passive earth pressure coefficients with an inclined angle of backfill and internal friction angle. The magnitude of passive earth pressure coefficients of the proposed method were smaller than those of the Coulomb in almost all cases. A comparison of the passive earth pressure coefficients with the wall friction angle revealed the passive earth pressure coefficients of the proposed method to be smaller than those of the Coulomb and the differences between the two values increased with increasing internal friction angle and wall friction angle. A comparison of the passive earth pressure coefficients of the proposed method with those of the existing researchers for the considered internal friction angles of $25^{\circ}$, $30^{\circ}$, $35^{\circ}$, and $40^{\circ}$ and three wall friction angles revealed the maximum percentage differences for the Kerisel and Absi method, Soubra method, Lancellotta method, $Ant\tilde{a}o$ et al. method, Kame method, and Reddy et al. method to be 4.8%, 3.8%, 31.1%, 4.0%, 20.6%, and 12.8% respectively. The passive earth pressure coefficient and existing pressures were similar in all cases.