• 한국농공학회지
• /
• 제41권5호
• /
• pp.93-98
• /
• 1999

The results of an experimental investigation on the characteristics of compaction and compressive strength of polypropylene fiber reinforced soil are presented in this paper. This study has been performed to obtain the physical properties of PFRS(polypropylene fiber reinforced soil) such as strain-stress relationships, OMC(optimum moisture contents) and ${\gamma}$dmax (maximum dry unit weight), with four different contents (i.e., 0.1%, 0.3%, 0.5% and 1.0% weights ) of mono-filament and fibrillated polypropylene fibers. From the compaction test results, it is found that OMC increased with the contents ratio of fiber, but ${\gamma}$dmax decreased. It means that the improvement of the workability and the reduction of the weight of embankment structures by the asddtion of the polypropylene fiber. And, from the compression test results, it is found that the additon of the polypropylene fiber remarkably improved the compressive strength of PFRS. And it was observed in the viewpoint of strength that the fibrillated polypropylene fiber reinforced soil is more effective than the mono-filament polypropylene fiber reinforced soil.

• 한국환경과학회지
• /
• 제4권5호
• /
• pp.41-41
• /
• 1995

In order to discuss the differences among the SMP(Surface Moisture Availability Parameter), by previous researchers on the basis of their own theoretical and empirical background, we assessed the SMP according to the soil types and volumetric soil water contents. The results are as follows. There are differences among all the five SMAPs. There''s a tendency that the larger grain size, the higher value of parameters. And they divided into two groups for their value: one group has parameters with exponential function and the other with cosine and linear function. The maximum difference between the two groups appears when the volumetric soil water contents are 0.07$m^3m^{-3}$ for sand, 0.l1$m^3m^{-3}$ for loam, 0.12 for clay, and 0.13$m^3m^{-3}$ for silt loam. So, these differences must be considered when we estimate the surface evaporation rate. From field data, the paddy field soil around Junam reservoir is classified as a silt has high wetness, 0.56. So, the parameter obtained from the field measurement is much higher than that of Clapp and Hornberger(1978)''s Table. This study treated the SMP for a certain point of time in winter season. But if we measured the soil water contents continuously, we could obtain better time-dependent parameter.

• 한국환경복원기술학회지
• /
• 제5권6호
• /
• pp.37-42
• /
• 2002

This study has been performed to investigate the physical and mechanical characteristics of compaction, volume change and compressive strength for reinforced soil mixed with polypropylene fiber, and to confirm the reinforcing effects with admixture such as polypropylene fiber. To this end, a series of compaction test and compression test was conducted for clayey soil(CL) and polypropylene fiber reinforced soil. In order to determine proper moisture contents and mixing ratio, pilot test was carried out for natural soil and PFRS(polypropylene fiber reinforced soil). And the mixing ratio of mono-filament fiber and fibrillated polypropylene fiber admixture was 0.1%, 0.3%, 0.5% and 1.0% by the weight of dry soil. From the experimental results, it was found that the optimum moisture contents(OMC) increased with the mixing ratio of fiber, but the maximum dry unit weight and the volume change was decreased with the mixing ratio. It means that the improvement of the workability and the reduction of the weight of embankment was done by the addition of the polypropylene fiber. And, from the compression test results, it was found that the addition of the polypropylene fiber remarkably improved the compressive strength of PFRS. And it was observed in the viewpoint of strength that the fibrillated polypropylene fiber reinforced soil was more effective than the mono-filament polypropylene fiber reinforced soil.

• 한국농공학회지
• /
• 제18권3호
• /
• pp.4163-4170
• /
• 1976

This study was conducted to investigate the effect of starch as a retarder on the maximum dry density and the unconfined compressive strength of soil cement mixtures for varied starch contents (0-3%), cement contents (3-12%), and delay times (0-6hrs) in four soils. The experimental results obtained from maximum dry density and unconfined compressive strength tests are as follows: 1. Maximum dry density and unconfined compressive strength were increased greatly in soil cement mixtues rwhen starch was added as retarder but their value schanged according to soil varieties. 2. Maximum dry density showed at about 0.5 percent to 1.0 percent of starch in KY soil and about 2.0 percent to 2.5 percent in SS soil when delay time was changed in 2.4, and 6 hours in compaction test. 3. The larger content of cement was, the bigger effects of maximum dry density and compressive strength were in soil cement. mixtures. 4. As delay time changed 2.4, and 6 hours in compaction test, 7-day unconfined compressive strength showed the biggest value at about 0.5 percent of starch in KY soil and 2.0 percent in SS soil, and the maximum value of 28-day unconfined compressive strength showed at about 0.5 percent in KY soil and 1.5 percent in SS soil.

• The Korean Journal of Ecology
• /
• 제21권3호
• /
• pp.313-320
• /
• 1998

Ameliorating effects of dolomite and sludge on the polluted soil sampled from Ulsan and yeocheon Industrial Complexes were investigated. Ameliorating effects were analysed by changes of soil properties and plant growth after treatment of dolomite and sludge. Soil properties were investigated by analysing organic matter, N, P, K, Ca and Mg contents and pH. Growth of sample plants was investigated by leaf area calculated from length and breadth of leaves and by biomass from diameter and height of sample plants. Quercus serrata and Celtis sinensis selected as tolerant plants in field survey were used as experimental plants. Treatment with dolomite showed ameliorating effects by increassing n, Ca, and Mg com\ntents, and pH of soil and by decreasing Al content. Treatment of sludge showed similar effects by increasing N, Ca, Mg and organic matter contents, and by decreasing A1 content. But treatment of sludge did not show any effect on pH. Both soil ameliorators showed accelerating effects on the growth of experimental plants in Ulsan soil. But those effects in Yeocheon soil were somewhat different. Treatment of sludge showed accelerating effects of the growth of both sample plants but dolomitic liming did not so. From those results, we confirmed availability of sludge, a kind of industrial waste, as one of ameliorators of the polluted soil. In addition, we recognized that soil properties had to be considered to select soil ameliorators suitable for restoration of degraded ecosystems.

• 한국산림과학회지
• /
• 제97권5호
• /
• pp.492-500
• /
• 2008

Since vegetation significantly influences on soil carbon and nutrient storage, vegetation change has been focused on terrestrial carbon and nutrient cycling studies. In this study we investigated soil carbon and major nutrient capitals at the abandoned fields, which had different vegetation composition: a three year abandoned field ($AGR_3$), two ten years abandoned fields ($PD_{10}$ dominant with Pinus densiflora and Fraxinus rhynchophylla and $PM_{10}$ dominant with Populus maximowiczii), and an over sixty years forest ($FOR_{60}$). which were located at Hongcheon-gun, Kangwon-do, South Korea. Both main effects for organic matter (%) were significant: shallow soil > deep soil and $FOR_{60}=PM_{10}$ > $AGR_3=PD_{10}$. Nitrogen concentrations at $PM_{10}$ were the highest, while the lowest at $PD_{10}$. Available phosphorus concentrations were the highest at $PD_{10}$, which were over 10 times of site $FOR_{60}$ and $AGR_3$ at 0-10 cm soil depth. The average organic matter ($173Mg\;ha^{-1}$) and nitrogen contents ($10Mg\;ha^{-1}$) of $PM_{10}$ and $FOR_{60}$ were higher than those of $AGR_3$ and $PD_{10}$ by 57% and 42%, respectively. The available phosphorus contents above 30 cm mineral soil at $PD_{10}$ ($3.8Mg\;ha^{-1}$) and $PM_{10}$ ($1.3Mg\;ha^{-1}$) were over 120 times and 40 times more than at $FOR_{60}$. Calcium ($3.7Mg\;ha^{-1}$) and magnesium contents ($2.8Mg\;ha^{-1}$) at $FOR_{60}$ were twice or three times higher than at other sites. Organic matter amounts in 0-10 cm and 10-30 em soil had significant positive relationships with nitrogen, calcium, and magnesium contents, but not available phosphorus and potassium contents. This study could not identify the effect of chronological factor and vegetation composition on soil carbon and nutrient capital owing to diverse topography as well as limited study sites. However, this study suggests the accuracy of investigation for regional carbon and nutrient sequestration can be achieved by considering the period of abandoned time on the fields and the land use types. These results may suggest the benefits of forest restoration for soil carbon and nutrient accumulation in marginal agricultural lands in South Korea.

• The Korean Journal of Ecology
• /
• 제17권3호
• /
• pp.277-286
• /
• 1994

수도권과 그 주변 지역의 33지소의 리기다소나무 숲에서 리기다소나무 잎과 잔뿌리의 주요이온의 함량을 정량하였다. 잎 속의 N, P, K 및 Mg 함량운 전년도 잎에 비해 당해연도 잎속에 높았지만, Al과 Ca은 그 반대였다. 잎 속의 N, P, K 및 Al 함랴은 지역간의 차이가 없었지만, Ca과 Mg 함량은 전원지에 비해 도심지에서 낮았다. 그러나 잎속의 N/Ca와 N/Mg의 비의 값은 전원지에보다 도심지에서 컸다. 표토 잔뿌리 속의 Mg 함량은 도심으로부터 거리가 멀어짐에 따라 증가하였으나, 심층토 잔뿌리 속의 Al 함량은 그 반대였다. 토양층 잔뿌리 속의Al 함량은 도심지보다 전원지에서 낮았다. 토양층 잔뿌리속의 Al 함량은 낙엽층의 잔뿌리에 비하여 2~3배 높았다. 그리고 표토보다 심층토에 존재하는 잔뿌리 속에 Al 함량이 높았다. 그러므로 수도권 지역에서 리기다소나무의 생장감소는 조직 속의 Ca과 Mg 부족, N/Ca과 N/Mg 비의증가 및 잔뿌리 생장에 대한 Al 독성에 있었다. 그리고 수도권 지역에서 잔뿌리의 비정상적인 분포는 산성토양에서 Al 독성에 의한 잔뿌리의 생장감소가 그 원인으로 해석된다.

• 한국토양비료학회지
• /
• 제22권3호
• /
• pp.234-238
• /
• 1989

황금근(黃芩根)의 품질(品質)을 향상(向上)시키기 위만 합리적(合理的)인 재배법정립(栽培法定立)에 필요한 기초자료를 얻기 위하여 재배지토양이화학성(栽培地土壤理化學性) 및 황금근(黃芩根)에 함유(含有)된 무기성분함량(無機性分含量)이 baicalin함량(含量)에 미치는 영향(影響)을 조사(調査)하였다. 황금근(黃芩根) 중(中) 규소함량(奎素含量)은 0.28~1.26 %, 인함양(燐含量)은 0.17~0.46%, 가리함량(加里含量)은 1.00~1.49의 범위에 속(屬)하였다. 황금근(黃芩根) 중(中) baicalin함량(含量)은 안동산(安東産)이 11.41~14.76%, 의성산(義城産)이 13.67~16.31 %이었다. 토양(土壤) 중(中) 점토(粘土), 유기물(有機物) 및 치환성(置換性) K, Ca, Mg의 함량(含量)은 황금근(黃芩根)의 질소(窒素) 및 인(燐)의 함량(含量)과 부(負)의 상관(相關)이 인정(認定)되었다. 토양(土壤) 중(中) 치환성(置換性) 가리함량(加里含量)은 baicalin함량(含量)과 정(正)의 상관(相關)이 인정(認定)되었다. 황금근(黃芩根) 중(中) 질소(窒素) 및 인(燐)의 함량(含量)은 baicalin함량(含量)과 부(負)의 상관(相關)이 인정(認定)되었으나, 가리함량(加里含量)은 유의성(有意性)이 없었다.

• The Korean Journal of Ecology
• /
• 제22권1호
• /
• pp.13-19
• /
• 1999

토양산성화로 인해 나타나는 토양의 양이온결핍과 신갈나무의 당년지 및 잎의 영양염류 함량 변화 및 연륜생장의 변동을 조사하기 위하여 서울 남산을 기점으로 동쪽으로 25 km 떨어진 경기도 남양주군 예봉산으로부터 185 km 떨어진 강원도 명주군 매봉산까지 신갈나무 숲 14개 지소를 선정하여 조사하였다. 토양 Ca/sup 2+/, Mg/sup 2+/, Na/sup +/ 및 양이온 유효치환능(ECEC)은 서울에서 동쪽으로 멀어질수록 증가하는 경향이었다. 토양 pH도 서울에서 동쪽으로 멀어질수록 증가하였다. 당년지의 Ca과 Mg함량은 서울에서 동쪽으로 멀어질수록 증가하였으나, 당년지의 K및 Na함량은 서울에서 동쪽으로 멀어질수록 대체로 감소하였다. 신갈나무 잎의 Ca함량은 서울에서 동쪽으로 멀어질수록 증가하였으나, 당년지의 K 및 Mg함량은 서울에서 동쪽으로 멀어질수록 감소하였다. 당년지의 생장은 경기도 지방의 것이 강원도 지방의 것보다 작았다. 대기오염지역으로서 남산과 대조지역으로서 예봉산의 연륜생장을 조사하였는데 평균연륜폭은 1970년대 초반부터 1980년대 후반까지 남산의 것이 예봉산의 것에 비하여 좁았다.

• Journal of Biosystems Engineering
• /
• 제2권1호
• /
• pp.25-32
• /
• 1977

This experiment was conducted in order to find out the drawing performance of a two-wheel tractor under different levels of the soil moisture and hardness, so as to obtain some basic data for improving their drawing performance. With fairly homogeneous soil, 5 levels of soil moisture contents (8, 13, 17, 20 and 23%) and 3 levels of soil hardness (0 , 2 and 4kg/$cm^2$) were selected for this experiment.The summerized results are as follows ;1. The draft force, on the hard soil (hardness ; 4kg/$cm^2$), had a distinct tendency to decrease with the increasing soil moisture. On the medium soil (hardness ; 2 kg/$cm^2$), and the soft soil (hardness ; 0kg$cm^2$), the draft force showed the highest when the moisture contents were within the range of 16-19%.But the maximum draft force, on the soft soil, was higher than that on the medium soil by 10 %. 2. The driving axle torque increased with increasing soil by 10 %. 3.The values of horizontal distance between the soil reaction point and axle shaft were within the range of 0~10cm , and it had the tendency to increase with the increasing soil moisture. Also, it s value was the largest on the hard soil and the smallest on the soft soil. 4.The tractive efficiency decreased with the increasing soil moisture. On the hard soil, the average value of tractive efficiency was higher than that on the medium soil by 19.0% and that on the soft soil was lower than that on the medium soil. 5.The traction ratio were within the range of 30 ~45%, and their changing tendency with respect to the soil moisture was similar to that in the case of the draft force. 6. The travel resistance ratio tended to increased with increasing soil moisture, and the highest value was found on the soft soil, and the lowest on the hard soil.