• Journal of Biosystems Engineering
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• v.3 no.2
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• pp.35-61
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• 1978

To find out the power tiller's travel and tractive characteristics on the general slope land, the tractive p:nver transmitting system was divided into the internal an,~ external power transmission systems. The performance of power tiller's engine which is the initial unit of internal transmission system was tested. In addition, the mathematical model for the tractive force of driving wheel which is the initial unit of external transmission system, was derived by energy and force balance. An analytical solution of performed for tractive forces was determined by use of the model through the digital computer programme. To justify the reliability of the theoretical value, the draft force was measured by the strain gauge system on the general slope land and compared with theoretical values. The results of the analytical and experimental performance of power tiller on the field may be summarized as follows; (1) The mathematical equation of rolIing resistance was derived as $$Rh=\frac {W_z-AC \[1+ \frac{sl}{K} \(\varrho ^{-\frac{sl}{K}-1\)\] sin\theta_1}} {tan\phi \[1+ \frac{sl}{K} \(\varrho ^{-\frac{sl}{K}-1\)\]+\frac{tan\theta_1}{1}$$ and angle of rolling resistance as $$\theta _1 - tan^1\[ \frac {2T(AcrS_0 - T)+\sqrt (T-AcrS_0)^2(2T)^2-4(T^2-W_2^2r^2)\times (T-AcrS_0)^2 W_z^2r^2S_0^2tan^2\phi} {2(T^2-W_z^2r^2)S_0tan\phi}\] $$and the equation of frft force was derived as$$P=(AC+Rtan\phi)\[1+ \frac{sl}{K} \(\varrho ^{-\frac{sl}{K}-1\)\]cos\phi_1 \ulcorner \frac {W_z \ulcorner{AC\[ [1+ \frac{sl}{K} \(\varrho ^{-\frac{sl}{K}-1\)\]sin\phi_1 {tan\phi[1+ \frac{sl}{K} \(\varrho ^{-\frac{sl}{K}-1\]+ \frac {tan\phi_1} { 1} \ulcorner W_1sin\alpha $$The slip coefficient K in these equations was fitted to approximately 1. 5 on the level lands and 2 on the slope land. (2) The coefficient of rolling resistance Rn was increased with increasing slip percent 5 and did not influenced by the angle of slope land. The angle of rolling resistance Ol was increasing sinkage Z of driving wheel. The value of Ol was found to be within the limits of Ol =2\ulcorner "'16\ulcorner. (3) The vertical weight transfered to power tiller on general slope land can be estim ated by use of th~ derived equation: $$R_pz= \frac {\sum_{i=1}^{4}{W_i}} {l_T} { (l_T-l) cos\alpha cos\beta \ulcorner \bar(h) sin \alpha - W_1 cos\alpha cos\beta$$The vertical transfer weight $R_pz$ was decreased with increasing the angle of slope land. The ratio of weight difference of right and left driving wheel on slop eland,$\lambda= \frac { {W_L_Z} - {W_R_Z}} {W_Z} $, was increased from ,$\lambda$=0 to$\lambda$=0.4 with increasing the angle of side slope land ($\beta = 0^\circ~20^\circ) (4) In case of no draft resistance, the difference between the travelling velocities on the level and the slope land was very small to give 0.5m/sec, in which the travelling velocity on the general slope land was decreased in curvilinear trend as the draft load increased. The decreasing rate of travelling velocity by the increase of side slope angle was less than that by the increase of hill slope angle a, (5) Rate of side slip by the side slope angle was defined as $ S_r=\frac {S_s}{l_s} \times$ 100( %), and the rate of side slip of the low travelling velocity was larger than that of the high travelling velocity. (6) Draft forces of power tiller did not affect by the angular velocity of driving wheel, and maximum draft coefficient occurred at slip percent of S=60% and the maximum draft power efficiency occurred at slip percent of S=30%. The maximum draft coefficient occurred at slip percent of S=60% on the side slope land, and the draft coefficent was nearly constant regardless of the side slope angle on the hill slope land. The maximum draft coefficient occurred at slip perecent of S=65% and it was decreased with increasing hill slope angle $\alpha$. The maximum draft power efficiency occurred at S=30 % on the general slope land. Therefore, it would be reasonable to have the draft operation at slip percent of S=30% on the general slope land. (7) The portions of the power supplied by the engine of the power tiller which were used as the source of draft power were 46.7% on the concrete road, 26.7% on the level land, and 13~20%; on the general slope land ($\alpha = O~ 15^\circ ,\beta = 0 ~ 10^\circ$) , respectively. Therefore, it may be desirable to develope the new mechanism of the external pO'wer transmitting system for the general slope land to improved its performance.l slope land to improved its performance.

• Magazine of the Korean Society of Agricultural Engineers
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• v.20 no.2
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• pp.4695-4707
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• 1978

The objeative of this study is to study how to rapidly convert tidal land into cultivable land. The study of a rapid, reasonable desalinization method is conducted at Namyang tidal land which represents soil texture of tidal lands along the south west costa larea of Korea. Therefore, Researches were made at many Pilots in order to find a way of high efficiency of leaching with simpler facilities and cheaper costs. The results of study are briefly summarized as follaws: 1. Subdrainage efficieny is 35%. This is a Poorly drained area, and needs longer leaching desalinization period. 2. The efficieny of desalinization in P.V.C 16 meters plot is the same as that of mole drainage 2 meters plot. P.V.C 4 meters plot has desalinization effect as much as two times compared to P.V.C 16 meters plot. 3. Because the soil texture is silty-clay, desalinization in non-treated plot of sub-drainage and surface drainage desalinization take three times longer period in comparision with P.V.C 4 meters plot. 4. As to the desalinization rate of soluble salt in the soil, the efficieny of desalinization of the topsoil in P.V.C plots was 50% higher than that of mole drainage plot and about 170% higher than that of non-treated plot. In the deep soil salt accumulation at topsoil was observed in non-treated and mole drainage plots, but efficiency in P.V.C polt is about 40 times as high as that of mole drainage and non-treated plot. 5. As to the results of use gypsum and lime as sub-drainage soil improver, gypsum was 60% more efficieny than lime in the continuously inundated plot and 44% in the intermittently inundated plot. The efficieny of gypsum and lime in the intermittently flooded plot is 35% and 42% higher than that of continuously flooded plot reapeaticee1y.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.2
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• pp.81-92
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• 2017

Recently, agricultural lands have decreased sharply, which was caused by huge housing site, urbanization, land consolidation, and road construction etc. In particular, Yangju city near Seoul city has the most severe land use change in Korea. Therefore, we analyzed changes of land use, soil properties, and soil information in order to provide the basic soil information and soil management practices in this city. The area of crop cultivated land in Korea (2015) reduced by 12,090 ha compared to ones from the previous year (2014). The paddy field decreased by 25,421 ha but, upland field increased by 13,331 ha. One of the reasons for the reduction of the paddy field was converting paddy field to upland (20,916 ha) > others (3,056) > building (2,571) > public facilities (847) > idle land (217). But, reasons for increase of upland field were switching paddy to upland (20,916 ha) > land developed (634). The main reason of converting paddy field to upland was changing from rice to more profitable speciality crops or pulses. The cropland area (paddy fields, upland, orchard) of Yangju city reduced by 1,412 ha (2015/2014). The ratio of cropland area in each city reduced by 22.9% dramatically compared 2015 to 1999. The paddy fields located in alluvial plains in Yangju city were changed into upland or green house. The drainage classes of soil have been deteriorated because the flows of water were intercepted by road construction and other disturbance to water flows. In particular, paddy fields have been changed to not only upland, orchard, greenhouse cultivation but also to fallow and soil dressing on paddy in Yangju city. To analyze result of soil survey of Yangju city, 858 soil codes (soil phases) were used and the area was 105.17ha. The number of soil series increased from 60 to 65, and that of soil phase increased from 105 to 124. The largest increased area was Noegog soil series. 125.7ha of Neogog soil series was incorporated from the existing Sachon, Yecheon and Eungog soil series. The soil suitability class of paddy field in Ogjung huge housing site of Yangju city was the 4th grade for 32.6% of the area. The soil suitability classes of upland were 2nd and 3rd grade for 72.4% of the area. Farm land with high quality should be conserved by related law.

• Journal of The Korean Society of Grassland and Forage Science
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• v.12 no.3
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• pp.30-40
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• 1992

The area of grassland established and the arable land in forage production have been decreased recently in Korea. As a result, forages available from the grassland and the arable land provided only 40% of the total roughage consumed by cattle in 1991, compared with 54% in 1989. The decreasing trend of the forage production has been impinged on by a number of legislative. socio-economic. technical and other constraints negatively affecting grassland and forage development. Consequently. effective systems and strategies are quite necessary to have sustainable grassland farming in Korea. In spring and autumn, temperatures are too low for subtropical forage crops, and the summer monsoon climate is another serious limitation to the use of cool-season species. Therefore it is an imperative that not only the research-based grassland development but also the forage crop production should be strongly supported by the government authorities to overcome such climatic limitations. Private forest land holdings are of relatively small units in Korea. Accordingly. it is necessary and important to enlarge the forest land holdings per farm to develop as economic units of grassland. For this the government should introduce new policy measures such as for example: long-term leases of Sorest land and the idle arable land of absentee owners ; rational rental system of national and public forest lands; integrating livestock and forest production. All the laws and regulations standing in the way of the grassland development in forest lands should be modified and revised to open the way for much easier development of grassland. It is also proposed that a high level of financial incentives -hould be provided for structural improvements for the grassland development. They may be: mechanization facilitation, construction of new roads relating to grassland, and land exchange and consolidation. And it is basically necessary that financial enumeration or profits must be garanteed in order to motivate farmers to keep up farming continuously. For more efficient grassland development in mountainous areas, reorganization of Alpine Experiment Station and NAB1 Namwon Branch Station may be needed. Research should be strengthened for completion of pasture mixtures, development of maximum forage production methods with a view to saving labor and reducing production costs, introduction of grazing and forage conservation techniques. and utilization of rice straw as more palatable and nutritious forage source. In order to have more efficient and effective transfer of advanced forage production technologies to livestock farmers the user-clients. it is also essential that special training measures should be given to livestock farmers through making greater use of specialized research and extension workers.

• Land and Housing Review
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• v.11 no.3
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• pp.69-74
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• 2020

Since the design Standard for Energy Conservation in Building was implemented in 2008 for the first time, building elements such as window and door should satisfy the minimum criteria to apply for a building. Though its regulation does not cover the whole building yet, recent demand to reduce energy consumption in building sector grows rapidly year by year and also draws a lot of interest to ensure the whole building level. For example, a Zero energy building, one of low-energy buildings, requires a customized solution to resolve the air leakage issue to meet the standards in achieving the high level of air tightness. In this study, six non-residential buildings were tested by fan pressurization method to observe the air tightness of whole building to suggest the construction guideline for air tightness of low-energy building. Five out of six tested buildings showed 0.27 to 1.16 h^-1 of number of air changes except one community center. These buildings were carefully constructed not only for building planning but also for parts where there was a concern of air leakage, thereby securing high levels of air-tightness. The construction skills were developed as a checklist to manage and supervise the construction site. It is our suggestion to use this checklist at construction sites for ZEB with the high level of air-tightness.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.2
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• pp.137-150
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• 2010

A meso-urban meteorological model (Urbanized MM5; uMM5) with urban canopy parameterization (UCP) was applied to the high-resolution simulation of meteorological fields in a complex coastal urban area and the assessment of urban impacts. Multi-scale simulations with the uMM5 in the innermost domain (1-km resolution) covering the Busan metropolitan region were performed during a typical sea breeze episode (4~8 August 2006) with detailed fine-resolution inputs (urban morphology, land-use/land-cover sub-grid distribution, and high-quality digital elevation model data sets). An additional simulation using the standard MM5 was also conducted to identify the effects of urban surface properties under urban meteorological conditions. Results showed that the uMM5 reproduced well the urban thermal and dynamic environment and captured well the observed feature of sea breeze. When comparison with simulations of the standard MM5, it was found that the uMM5 better reproduced urban impacts on temperature (especially at nighttime) and urban wind flows: roughness-induced deceleration and UHI (Urban Heat Island)-induced convergence.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.5 no.6
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• pp.43-48
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• 2002

This study was carried out to clarify the change characteristics of stream water quality by land-use of forest from July to September, 2000 in three stands(Pinus densiflora, Castanea crenata (I), Castanea crenata (II) stand) of Jeongpyeong-ri, Jinju-si, Gyeongnam. The mean pH of rainfall results in acid rain of 5.3. The pH of stream water in three stands was high in order of Pinus densiflora (pH 6.59), Castanea crenata (II)(pH 6.53) and Castanea crenata (I) stand(pH 6.47). The electrical conductivity of stream water was high in order of Castanea crenata (I), Pinus densiflora and Castanea crenata (II) stand. Cations contents of three stands in stream water were high in order of $Ca^{2+}$, $Na^{2+}$, $Mg^{2+}$, $K^+$ and ${NH_4}^+$. But anions of stream water in Pinus densiflora stand and Castanea crenata (II) stand were high in order of ${SO_4}^{2-}$, $Cl^-$ and ${NO_3}^-$. In Castanea crenata (I) stand cations of stream water were high in order of ${NO_3}^-$, ${SO_4}^{2-}$ and $Cl^-$. The level of pH, ${NH_4}^+$, ${NO_3}^-$, $Cl^-$ and ${SO_4}^{2-}$ of stream water in Pinus densiflora stand and Castanea crenata (II) stand reached within the level of domestic use standard for drinking water But the level of ${NO_3}^-$ of stream water in Castanea crenata (I) stand was higher than that of domestic use standard. Therefore, non-point sources like forest watersheds which are fertilizer application lands should be taken to the appropriate mitigation measures.

• Journal of Biosystems Engineering
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• v.3 no.2
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• pp.34-34
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• 1978

To find out the power tiller's travel and tractive characteristics on the general slope land, the tractive p:nver transmitting system was divided into the internal an,~ external power transmission systems. The performance of power tiller's engine which is the initial unit of internal transmission system was tested. In addition, the mathematical model for the tractive force of driving wheel which is the initial unit of external transmission system, was derived by energy and force balance. An analytical solution of performed for tractive forces was determined by use of the model through the digital computer programme. To justify the reliability of the theoretical value, the draft force was measured by the strain gauge system on the general slope land and compared with theoretical values. The results of the analytical and experimental performance of power tiller on the field may be summarized as follows; (1) The mathematical equation of rolIing resistance was derived as $$Rh=\frac {W_z-AC \[1+ \frac{sl}{K} \(\varrho ^{-\frac{sl}{K}-1\)\] sin\theta_1}} {tan\phi \[1+ \frac{sl}{K} \(\varrho ^{-\frac{sl}{K}-1\)\]+\frac{tan\theta_1}{1}$$ and angle of rolling resistance as $$\theta _1 - tan^1\[ \frac {2T(AcrS_0 - T)+\sqrt (T-AcrS_0)^2(2T)^2-4(T^2-W_2^2r^2)\times (T-AcrS_0)^2 W_z^2r^2S_0^2tan^2\phi} {2(T^2-W_z^2r^2)S_0tan\phi}\] $$and the equation of frft force was derived as$$P=(AC+Rtan\phi)\[1+ \frac{sl}{K} \(\varrho ^{-\frac{sl}{K}-1\)\]cos\phi_1 ? \frac {W_z ?{AC\[ [1+ \frac{sl}{K} \(\varrho ^{-\frac{sl}{K}-1\)\]sin\phi_1 {tan\phi[1+ \frac{sl}{K} \(\varrho ^{-\frac{sl}{K}-1\]+ \frac {tan\phi_1} { 1} ? W_1sin\alpha $$The slip coefficient K in these equations was fitted to approximately 1. 5 on the level lands and 2 on the slope land. (2) The coefficient of rolling resistance Rn was increased with increasing slip percent 5 and did not influenced by the angle of slope land. The angle of rolling resistance Ol was increasing sinkage Z of driving wheel. The value of Ol was found to be within the limits of Ol =2? "'16?. (3) The vertical weight transfered to power tiller on general slope land can be estim ated by use of th~ derived equation: $$R_pz= \frac {\sum_{i=1}^{4}{W_i}} {l_T} { (l_T-l) cos\alpha cos\beta ? \bar(h) sin \alpha - W_1 cos\alpha cos\beta$$The vertical transfer weight $R_pz$ was decreased with increasing the angle of slope land. The ratio of weight difference of right and left driving wheel on slop eland,$\lambda= \frac { {W_L_Z} - {W_R_Z}} {W_Z} $, was increased from ,$\lambda$=0 to$\lambda$=0.4 with increasing the angle of side slope land ($\beta = 0^\circ~20^\circ) (4) In case of no draft resistance, the difference between the travelling velocities on the level and the slope land was very small to give 0.5m/sec, in which the travelling velocity on the general slope land was decreased in curvilinear trend as the draft load increased. The decreasing rate of travelling velocity by the increase of side slope angle was less than that by the increase of hill slope angle a, (5) Rate of side slip by the side slope angle was defined as $ S_r=\frac {S_s}{l_s} \times$ 100( %), and the rate of side slip of the low travelling velocity was larger than that of the high travelling velocity. (6) Draft forces of power tiller did not affect by the angular velocity of driving wheel, and maximum draft coefficient occurred at slip percent of S=60% and the maximum draft power efficiency occurred at slip percent of S=30%. The maximum draft coefficient occurred at slip percent of S=60% on the side slope land, and the draft coefficent was nearly constant regardless of the side slope angle on the hill slope land. The maximum draft coefficient occurred at slip perecent of S=65% and it was decreased with increasing hill slope angle $\alpha$. The maximum draft power efficiency occurred at S=30 % on the general slope land. Therefore, it would be reasonable to have the draft operation at slip percent of S=30% on the general slope land. (7) The portions of the power supplied by the engine of the power tiller which were used as the source of draft power were 46.7% on the concrete road, 26.7% on the level land, and 13~20%; on the general slope land ($\alpha = O~ 15^\circ ,\beta = 0 ~ 10^\circ$) , respectively. Therefore, it may be desirable to develope the new mechanism of the external pO'wer transmitting system for the general slope land to improved its performance.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.6
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• pp.439-446
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• 2011

In this research, enhanced land-cover classification methods using high-resolution satellite image (HRSI) and GIS in terms of practicality and accuracy was proposed. It aims for understanding non-point pollutant origin/loading, assessment the efficiency of rainfall storage/infiltration facilities and sounds water-environment management. The result of applying enhanced land-cover classification methods to the urban region verifies that roof and road area are including various vegetations such as roof garden, flower bed in the median strip and street tree. This accounts for 3% of total study area, and more importantly it was counted as impervious area by GIS alone or conventional indoor work. The feasibility of the method was assessed by applying to rainfall-runoff analysis for three weak rainfall in the range of 7.1-10.5 mm events in 2000, Chiba, Japan. A good agreement between simulated and observed runoff hydrograph was obtained. In comparison, the hydrograph simulated with land-use parameters by the detailed land-use information of 10m grid had an error between 31%~71%, while enhanced method showed 4% to 29%, and showed the improvement particularly for reproducing observed peak and recession flow rate of hydrograph in weak rainfall condition.

• Journal of the Korean Institute of Landscape Architecture
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• v.20 no.4
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• pp.12-25
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• 1993

The purpose of this study is to interpret the landscape meaning of village grove and then combines this interpretations with landscape planing if it is possible. So we chose four village groves among seven villlage interpretations with landscape planing if it is possible. So we chose four village groves among seven village groves in HAMPYUNG & YOUNGKWANG Province(CHONRANAMDO, KOREA). The reason why we did it is that the meaning of korean groves is divided into three types(Confucianism, Feng-shui, Native belief etc.) according to original planting reasons. This study was done mainly by both referring to the regional character of those types and examining the nature of grove meanings. As a result of this process, we are able to find three demensions which were explained by physical-ecological, user's behavioral and cultural meaning. 1. Physical landscape of village grove is composed with ecological meaning that is related with people's land use not only inside but outside of it. So this kind of ecological meaning is the mutual relation among physical elements of village groves, for example old high trees, surface, user's facilities, land use around a grove and soon. 2. User's behavior meaning of grove shows that it has high relation with physical dimension, for example distance and accessiblity to a grove, linkage with open space around a village and so on. User's behavior inside of grove is usually divided into three types(recreation, play, ritual services). Especially, we were able to find a tendency to have numerous people use in the case of a village grove well to preserve its ritual service. 3. Cultural meaning of grove has the holistic character which usually defines the regional theme of each village and village grove(Confucianism, Feng-shui, Native belief etc.). So, the Landscape meaning of village grove is not only a physical shape but a certain concept existing inside of village grove. This diversed meaning existing in a grove have a direct effect on good fortune or misfortune of a village and its dwellers.