• 한국지반공학회논문집
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• 제20권7호
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• pp.207-215
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• 2004

본 연구는 보강사면에 상계이론를 적용하여 실제 한계상태에 가까운 신뢰성이 높은 해석방법을 개발하는데 목적이 있으며 상계해석의 유한요소공식화를 전개하는데 있어 거시적인 관점으로부터 비등방성이면서 균질한 재료에 대한 수치해석의 기본 개념은 얻을 수 있다. 보강토는 뒷채움한 성토와 보강재 경계면의 상호작용으로 보강토의 강도가 보강재의 재료적 특성에 의존하고 있기 때문에 흙의 역학적 특성과 보강토의 전체 거동은 보강재의 기하학적인 배열과 상대적인 면적에 의해서 조절할 수 있다. 따라서, 상계이론은 보강사면의 한계상태 거동을 효과적으로 산정할 수 있어 국부적으로 발생하는 소성파괴를 예측할 수 있다.

• 한국지반공학회논문집
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• 제28권4호
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• pp.55-65
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• 2012

본 연구는 지반조건에 따른 효과적인 마이크로 파일의 설치방법을 제안하기 위해 실트 또는 모래지반에서 모형시험을 수행하였다. 시험결과, 관입 전단파괴가 발생한 실트지반은 압축변위에 저항하도록 마이크로 파일을 엇갈리게 설치(${\theta}$ < $0^{\circ}$)하는 것이 효과적이며, 전면 또는 국부전단파괴가 발생한 모래인 경우 횡 방향 변위에 저항하도록 마이크로 파일을 경사지게 설치(${\theta}$ > $0^{\circ}$ 또는 ${\theta}$ < $0^{\circ}$) 하는 것이 효과적인 것으로 나타났다.

• 한국환경과학회지
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• 제19권9호
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• pp.1137-1142
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• 2010

This study proposes a guideline of a green roof system suitable for the local environment by verifying the growth of Zoysia japonica in a shallow, extensive, green roof system under rainfed condition. The experimental soil substrates into which excellent drought tolerance and creeping Z. japonica was planted were made with different soil thicknesses(15cm, 25cm) and soil mixing ratios(SL, $P_7P_1L_2$, $P_6P_2L_2$, $P_5P_3L_2$, $P_4P_4L_2$). The plant height, green coverage ratio, fresh weight, dry weight and chlorophyll contents of Z. japonica were investigated. For the soil thickness of 15cm, the plant height of Z. japonica was significantly as affected by the soil mixing ratio and it was shown in the order SL= $P_4P_4L_2$ < $P_7P_1L_2$ = $P_5P_3L_2$ < $P_6P_2L_2$. For the soil thickness of 25cm, the plant height was increased in order to SL < $P_7P_1L_2$, $P_6P_2L_2$, $P_5P_3L_2$ < $P_4P_4L_2$. The green coverage ratio was not observed by soil the mixing ratio or soil thickness. However, the green coverage ratio was 86~90% with a good coverage rate overall. The chlorophyll contents of Z. japonica were not significantly affected by the soil mixing ratio in the soil thickness of 15cm, but were higher in the natural soil than in the artificial soil at 25cm soil thickness. The fresh weight and dry weight of Zoysia japonica were heavier in the 25cm thickness than in the 15cm thickness and in the artificial soil mixture than in the natural soil. The result indicated that the growth of Zoysia japonica was more effective in the 25cm soil thickness with artificial soil than in the 15cm soil thickness with natural soil in the green roof system under rainfed condition.

• Geomechanics and Engineering
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• 제22권3호
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• pp.227-236
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• 2020

Expansive soils are renowned for their swelling-shrinkage property and these volumetric changes resultantly cause huge damage to civil infrastructures. Likewise, subgrades consisting of expansive soils instigate serviceability failures in pavements across various regions of Pakistan and worldwide. This study presents the use of polypropylene fibers to improve the engineering properties of a local swelling soil. The moisture-density relationship, unconfined compressive strength (UCS) and elastic modulus (E₅₀), California bearing ratio (CBR) and one-dimensional consolidation behavior of the soil treated with 0, 0.2, 0.4, 0.6 and 0.8% fibers have been investigated in this study. It is found that the maximum dry density of reinforced soil slightly decreased by 2.8% due to replacement of heavier soil particles by light-weight fibers and the optimum moisture content remained almost unaffected due to non-absorbent nature of the fibers. A significant improvement has been observed in UCS (an increase of 279%), E₅₀ (an increase of 113.6%) and CBR value (an increase of 94.4% under unsoaked and an increase of 55.6% under soaked conditions) of the soil reinforced with 0.4% fibers, thereby providing a better quality subgrade for the construction of pavements on such soils. Free swell and swell pressure of the soil also significantly reduced (94.4% and 87.9%, respectively) with the addition of 0.8% fibers and eventually converting the medium swelling soil to a low swelling class. Similarly, the compression and rebound indices also reduced by 69.9% and 88%, respectively with fiber inclusion of 0.8%. From the experimental evaluations, it emerges that polypropylene fiber has great potential as a low cost and sustainable stabilizing material for widespread swelling soils.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 지반공학 공동 학술발표회
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• pp.320-329
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• 2005

The use of diverse methods for the retaining system has been continuously increased in order to maintain the stability during excavation. However, ground anchor system occasionally may have the restriction in urban excavation sites nearby the existing structures because of space limitation. In this case, soil nailing system with relatively short length of nails could be efficiently useful as an alternative method. The general soil nailing support system, however, may result in excessive deformations particularly in excavating the zone of weak soils or nearby the existing structures. Therefore, applying the pretension force to the soil nails then could play important roles to reduce deformations mainly in an upper part of the nailed-soil excavation system as well as to improve the local slope stability. In this study, a newly modified soil nailing technology named as the PSN(Pretention Soil Nailing) is developed to reduce both facing displacements and ground surface settlements during top-down excavation process as well as to increase the global slope stability. Up to now, the PSN system has been investigated mainly focusing on an establishment of the design procedure. In the present study, the field tests including pull-out tests were fulfilled to investigate the behavior of characteristics for PSN system. All results of tests were also analyzed to provide a fundamental and efficient design.

• The Korean Journal of Ecology
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• 제22권1호
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• pp.7-11
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• 1999

환경오염과 관련하여 제안된 미국자리공의 분포확대가 토양의 산성화와 나아가서는 사막화를 가져온다는 가설을 실험적으로 확인하여 그 실체를 밝히고자 울산과 청주를 대상으로 미국자리공 군락에서의 근권 토양산성도를 측정하였다. 측정한 장소 중에서 청주의 부모산을 제외한 울산의 신선산, 돗질산 그리고 봉대산은 pH가 5.0 이하로 5.25와 5.33의 범위에서 변화한 청주의 부모산의 근권토양보다 강한 산성을 나타내었다. 그러나 봉대산을 제외하고는 식물체의 축을 중심으로 수평적으로나 수직적으로나 근권산성도에 유의차가 보여지지 않았다. 반면, 울산의 봉대산에서는 뿌리를 중심으로 수평적으로는 근권산성도가 변하지 않았지만 지표면 토양이 그 아래 토양보다 높은 산성도를 나타내었다. 이것은 일반적인 토양산성도의 패턴과 반대 현상으로, 지표면이 더욱 산성이라는 것은 지상환경의 오염, 즉 대기오염과 관련이 있다는 것을 나타내 주고 있다. 또한 이러한 사실은 미국자리공의 생장과정에서도 근권 토양산성도가 거의 변하지 않았던 모델실험 결과와도 잘 부합되었다. 따라서 미국자리공이 토양을 산성화시킨다는 가설은 다시 한번 고려되어야 할 것이다.

• 한국토양비료학회지
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• 제48권5호
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• pp.464-468
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• 2015

Our government has performed to support the nation-wide application of customized fertilizer based on soil-testing results and crop nutrient balance in order to promote the environment-friendly agriculture and to respond the global environment guide-line since 2010. This study was performed at the selected local paddy fields (Hwaseong-si, Uiseong-gun and Miryang-si) with different soil chemical properties in 2012. The contents of amino acids measured showed an increasing trend with fertilization, and glutamic acid was the most abundant amino acid followed by aspartic acid, leucine and alanine. However, valine, isoleusine, tyrosine and lysine were not significantly affected by fertilization. The significant differences in grain N, expressed as a crude protein, and amino acids dose was observed between experimental sites (p<0.001), treatments (p<0.01 to 0.001) and interaction of both factors (p<0.01 to 0.001). In our experiment the following order of carbon skeleton backbones to produce amino acids was observed irrespective of experiment sites and fertilization: ${\alpha}$-ketoglutarate > oxalate > pyruvate > 3-phosphoglycerate > phosphoenolpyruvate. In conclusion, customized fertilizer had no difference in amino acids compared to the conventional-NPK practice which was higher than in no fertilization, and also the normal paddy represented slightly higher amino acids compared to the reclaimed. Further study based on the present results is required to investigate what is main factor to amino acids between genetic and environmental factors.

• 한국농공학회논문집
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• 제61권4호
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• pp.63-73
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• 2019

Coastal and fishing facilities are gradually deteriorating in function due to the continual accumulation of soil sediments, which has affected local economic activities. Currently, there are many methods to remove soil sediments, but these methods are either a temporary solution or require a repetitive removal of the soil sediments, which is a huge financial burden for the maintenance of the facilities. To solve these problems, this study proposed a non-power soil cleaning system and evaluated field applicability by carrying out field model tests. The conditions for the evaluation focused on the drainage-elapsed time and drainage-outflow velocity according to the water level change in the water tank. In the field test, silty clay and sand were separately installed, and sedimentation soil removal test was practiced. As a result, the system was verified to have a sufficient outflow velocity for the removal of soil sediments. In addition, a generalization equation that can be used in different regions of the tide was suggested in this study. These results will greatly contribute to removing soil sediments in ports and dike gate facilities on the southwest coast. Since the system is an eco-friendly technology that does not require additional energy, thus it is expected to contribute to maintenance of sustainable facility performance as well as economic effect in the future.

• 한국토양비료학회지
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• 제29권2호
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• pp.81-85
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• 1996

1. 밭 토양의 개별특성(個別特性)인 지형조건(地形條件)과 경사도(傾斜度), 유효토심(有效土深) 및 밭 토양의 집단특성(集團特性)인 규모(規模)(면적), 분포토양의 복합도(複合度)(soil complexity), 작도단위(作圖單位)(군(群))의 분산도(分散度)(mapping unit separation), 사업 예정지역의 장폭비(長幅比)(W/L ratio) 등을 연역적(演繹的)으로 계수화(係數化)하여, 적성등급(適性等級)의 일종으로 볼 수 있는 밭 토양 경지정리(耕地整理) 대상지역(對象地域) 선정기준(選定基準)을 제안하였다. 2. 본 기준을 표본지역(標本地域)인 화강암지대(花崗岩地帶) 전작지역(田作地域)과 퇴적암지대(堆積岩地帶) 답작지역(畓作地域)의 밭 토양에 적용하여 본 결과, 지역특성을 객관적으로 차등화(差等化)하므로서 상호비교가 용이하였다. 3. 밭 토양 경지정리(耕地整理) "매우 적합지(適合地)"는 하성평원지(河成平垣地) 전작지(田作地)이거나 밭 토양이 집단적으로 분포된 저구릉지(低丘陵地)로서 분포토양이 단순하고 작도단위당(作圖單位當) 면적도 넓은 지역이었다. 한편, "부적지(不適地)"는 좁고 긴 곡간(谷間)으로서 곡저부(谷底部)(valley bottom)가 논으로 되어있어 작도단위(作圖單位)가 분산(分散)된 지역이었다.

• 한국연초학회지
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• 제9권1호
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• pp.35-43
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• 1987

This survey was been conducted to classify the distribution of morphological and chemical characteristics of soils in the major districts cultivating flue-cured tobacco plant. The results obtained are summarized as follows; 1. Tobacco was mainly grown in local valley, 7-15% slopes, loam and sandyloam containing gravels, and productivity classes of soil were corresponded to 3-4 degree for upland crops. 2. most soils were acidic (below pH 5.5) and contained low organic matters. (below 2%) 3. Dominant soil series were SANGJU, JIGOG, SEOCTO, SAMGAG ANRYONG, SUAM, and YESAN.