• 아시안잔디학회지
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• 제16권2호
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• pp.75-83
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• 2002

The back-filled soil of the New Incheon International Airport construction site was reclaimed with sea sand in near the Young-Jong island. The primary study was carried out from August 1993 to June 1997 to study soil amendment and to select salt resistance turfgrass species. This study dealt with low maintenance area that included most part of open space of airport site. The second experiment, from October 1996 to August 1998, focused on soil amendment and selection of turfgrass species for alongside runway where turf area was maintained. Through two previous studies, propagation methods with zoysiagrass were tested for alongside runway and surrounding areas at 1998. The study of construction methods with zoysiagrass, vegetative propagation showed better results on visual quality and cover rating compare with seeding propagation. However, significant different between vegetative and seeding propagation was not showed on visual quality and drought tolerance after one year of plot establishment. The cover rating by seeding construction methods reached in excess of 70% of limitation suggested by the Incheon International Airport Cooperation. Zoysia net and sprigging net methods were the most suitable where there requires rapid and high rate of ground cover. Seeding propagation should be acceptable to obtain a resonable cover rating where there allows relatively longer period of completion. Therefore, it should be possible to attain a proper rating of ground cover on the site of open space, alongside runway or areas similar to the New Incheon International Airport which is being built on dredged seashore sand. However, the methods of soil amendment, selecting salt tolerance species, and proper construction procedure should be considered at the a time.

• 한국농공학회지
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• 제43권1호
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• pp.53-65
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• 2001

To estimate agricultural water demand, many factors such as weather, crops, soil, cultivation method, crop coefficient and cultivation area, etc. must be considered. But it is not easy to estimate water demand in consideration of these factors, which are variable according to growth stage and regional environment. This study provides estimation system for agricultural water demand(ESAD) in order to estimate water demand easily and accurately, and arranges all factors needed for water demand estimation. This study identifies the application of estimation system for agricultural water demand with the data observed in the other studies, and analyzes nationwide agricultural water demand. The results are as follows. 1) The practice of different rice cultivation in the paddy field resulted in different water demands. Water depth and infiltration ratio in paddy are the most important factors to estimate water demand. The water depths in paddy simulated by ESAD is very similar to the observed ones. 2) Water demand of upland crops varies with the crops, soil, etc.. Effective rainfall estimated by daily routing of soil moisture varies according to the crops, soil, and effective soil zone(root depth). As crop root become grown, effective rainfall and an amount of irrigation water has been increased. 3) The current unit water demand of upland crops applied as 500mm or 550mm to estimate water demand does not reflect the differences caused by the crops, regional surrounding, weather condition, etc. Results from ESAD for the estimation of water demand of upland crops show that ESAD can simulate the actual field conditions reasonably because it simulates the actual irrigation practices with the daily routing of soil moisture.

• 한국전산구조공학회논문집
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• 제30권4호
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• pp.319-327
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• 2017

본 연구에서는 콘크리트 석션식 지지구조물을 사용한 해상풍력발전시스템의 지진응답 해석을 수행하여 그 거동 특성을 파악한다. 전체 시스템을 RNA, 타워, 지지구조물로 구성된 구조계와 이에 접하고 있는 유체 및 지반의 부분구조로 분리하여 운동방정식을 유도한다. 구조계에 작용하는 유체의 동수압과 지반의 상호작용력을 산정하고, 이를 구조계의 운동방정식과 결합하여 전체 시스템의 지배방정식을 도출한 후, 이 방정식의 해를 구하여 해상풍력발전시스템의 지진응답을 계산한다. 해석 결과로부터 지반-구조물 상호작용은 콘크리트 석션식 지지구조물에 의해 지지된 해상풍력발전시스템의 지진응답을 크게 증가시킬 수 있음을 확인할 수 있다. 특히, 지반의 유연성으로 인해 시스템의 고차 고유모드 응답이 증가할 수 있으므로, 해상풍력발전시스템의 동적거동 산정 시에는 반드시 지반-구조물 상호작용의 효과를 고려하여야 할 것이다.

• Earthquakes and Structures
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• 제20권2호
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• pp.187-200
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• 2021

The main factor for the amplification of ground motions near the crest or the toe of a slope is the reflection of the incident waves. The effects of the slope topography on the surrounding lands over the crest or at the toe can amplify the seismic responses of buildings. This study investigates the seismic performance of the slope topography and three mid-rise buildings (five, ten, and fifteen-storey) located near the crest and toe of the slope by 3D numerical analysis. The nonlinear model was used to represent the real behavior of building and ground elements. The average results of seven records were used in the investigations. Based on the analysis, the amplification factor of acceleration near the crest and toe of the slope was the most effective at distances of 2.5 and 1.3 times the slope height, respectively. Accordingly, the seismic performance of buildings was studied at a distance equal to the height of the slope from the crest and toe. The seismic response results of buildings showed that the slope topography to have little impact on up to five-storey buildings located near the crest. Taking into account a topography-soil-structure interaction system increases the storey displacement and base shear in the building. Accordingly, in topography-soil-structure interaction analyses, the maximum lateral displacement was increased by 71% and 29% in ten and fifteen-storey buildings, respectively, compare to the soil-structure interaction system. Further, the base shear force was increased by 109% and 78% in these buildings relative to soil-structure interaction analyses.

• 한국지반공학회논문집
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• 제39권8호
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• pp.41-48
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• 2023

미생물에 의한 탄산칼슘 침전(MICP)은 생물학적 기술로 지반의 공학적 특성을 향상시키는 개량공법이다. 본 논문에서는 식물 생장에 MICP 약액의 농도가 미치는 영향을 분석하였다. 큰김의털 종자를 주문진 표준사로 채워진 식물 용기에서 생장시킨 다음에 표면 처리법으로 MICP 약액을 살포하였다. 실험 결과는 MICP 약액이 처리된 식물의 줄기 생장은 무처리 식물과 비교하여 억제되었다. MICP 약액으로 인한 토양의 화학적 성분 변화를 분석하기 위해 pH와 전기전도도를 측정하였으며, pH는 MICP 약액 처리와 상관 없이 모든 경우에서 pH 7에 가까운 중성상태를 보였지만, 전기전도도는 MICP 약액의 농도가 높을수록 증가하였다. MICP 처리 과정에서 발생한 이온들이 식물 뿌리 주변 토양의 삼투압을 증가시켜 식물 성장에 필요한 물과 양분의 흡수를 저해하였고, 궁극적으로 식물 생장을 억제하였기 때문이다.

• 한국토양비료학회지
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• 제48권6호
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• pp.744-750
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• 2015

The objectives of this study were to investigate soil chemical characteristics for forest rehabilitation and suggest management in abandoned coal mine areas in Boryeong City, Chungcheongnam-do. Total study sites were seven sites, and soil properties analyzed were soil pH, total organic carbon (TOC), total-N, C/N ratio, and available $P_2O_5$ (A.v. P). Average soil pH (range) was 5.9 (4.5~7.0). Three study sites (Samgwang, Shinsung1, and Shimwon1) showed lower soil pH than standard (pH 5.6~7.3) of Korea Industrial Standards (KS) for abandoned coal mine forest rehabilitation. Average contents of TOC, and total-N were 1.5% (0.1~4.7%), and 0.10% (0.03~0.23%), respectively. Five study sites where the collapsed time was less than 10 years (Wangjashingang, Wonpoong, Samgwang, Shinsung1, and Shinsung2) showed lower TOC level than standard of KS (more than 1.2%). Wangjashingang, Wonpoong, Samgwang, and Shinsung1 showed lower level of total-N than standard of KS (more than 0.09%). C/N ratio of six study sites except Shimwon1 was out of proper range (15:1~30:1). Average A.v. P (range) was $20.7mgkg^{-1}$ (4.8~63.1), less than other abandoned coal mine fores rehabilitation areas in Mungyong City, and Hwasun-gun. TOC, total N and A.v. P increased with elapsed time from forest rehabilitation, while other soil properties did not show distinct pattern. Betula platyphylla was planted in Samkwang and Sinsung where soil pH was less than KS standard. Because the growth of Betula platyphylla can be limited in acid soil, it is necessary to neutralize soil pH to proper level with some soil amendment such as lime or shell of oyster. Furthermore, TOC, total-N and A.v. P in early stage of forest rehabilitation showed lower level than proper to vegetation growth. Therefore it needs continuous monitoring of soil characteristics and fertilization for vegetation growth and influx from surrounding forest in early stage of rehabilitation.

• 한국지하수토양환경학회지:지하수토양환경
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• 제15권5호
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• pp.16-22
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• 2010

Heavy metals in soils exist in various forms dependent upon surrounding conditions. As the Janghang smelter area is of concern for its high elevated heavy metal concentrations, Korean government decided to remediate the area. Main objectives of this research were; to analyze heavy metal concentrations and their existing forms in the vicinity of the smelter; and to understand differences made by analysis techniques of heavy metals. Top soils of rice field, crop field, bare field, and forestry in the area were sampled and analyzed for their physicochemical characteristics. Concentrations of Cu, Cd, Pb, and As were analyzed with two pretreatment techniques adopted using 0.1 N HCl and aqua regia. To analyze existing forms of heavy metals, Tessier's schemes for sequential extraction technique were adopted. Exchangeable fraction and carbonate bound fraction of heavy metals may pose potential threat to environment and were in the order of Pb > As > Cu > Cd. If assessing mobile fraction of heavy metals by land uses, the order was forestry > bare land > crop field > rice field. When analyzed using Tessier's scheme, high ratio of residual fractions to total arsenic concentration should be considered for remediation design of the area.

• 한국안전학회지
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• 제25권4호
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• pp.42-47
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• 2010

Recently, many techniques have been developed for the inspection of pipelines using guided waves. However, few researches have been made on the application of those techniques for buried underground pipes. Guided wave motions in the buried pipes are somewhat different from those of on-ground pipes which have traction-free (air) boundary condition on outer pipe walls and thus are strongly affected by the mechanical property of the surrounding soils. Therefore, it should be investigated the effect of soil properties on the guided wave behavior in buried pipe. On the other hand, the mechanical property of soil is largely depending on its moisture conditions nevertheless of other influential factors such as void ratio. In this study, the effect of moisture conditions in soils on mode attenuation of guided waves in the buried pipe is investigated. To this end, numerical study is performed to characterize mode attenuation behavior in buried pipes and the effective mode which is suitable for long range inspection is identified.

• 한국해양공학회지
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• 제24권4호
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• pp.32-37
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• 2010

This study presents the attenuation characteristics of the first guided longitudinal wave mode propagating in water-filled, buried steel pipes in order to investigate the effects of soil saturation and compaction on the attenuation patterns. For numerical calculation of attenuation, 10 different combinations of S-wave velocity, P-wave velocity, and soil densities were considered. From the attenuation dispersion curves, which were obtained using Disperse software, we determined that the attenuation decreases as saturation increases, whereas it increases as compaction increases. Over the frequency range from 0.2 to 0.4 MHz, the first longitudinal wave mode has attenuations that are relatively lower than for other ranges, is faster than the first flexural wave mode, and is sensitive to defects aligned in the axial direction. Hence, the first longitudinal wave mode over the mentioned frequency range would be the proper choice for long-range buried pipelines that transport water.

• Structural Engineering and Mechanics
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• 제21권4호
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• pp.437-450
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• 2005

In this study, a complete analysis of soil-structure interaction problems is presented which includes a modelling of the near surrounding of the building (near-field) and a special description of the wave propagation process in larger distances (far-field). In order to reduce the computational effort which can be very high for time domain analysis of wave propagation problems, a special approach based on similarity transformation of the infinite domain on the near-field/far-field interface is applied for the wave radiation of the far-field. The near-field is discretised with standard Finite Elements, which also allows to introduce non-linear material behaviour. In this paper, a new approach to calculate the involved convolution integrals is presented. This approximation in time leads to a dramatically reduced computational effort for long simulation times, while the accuracy of the method is not affected. Finally, some benchmark examples are presented, which are compared to a coupled Finite Element/Boundary Element approach. The results are in excellent agreement with those of the coupled Finite Element/Boundary Element procedure, while the accuracy is not reduced. Furthermore, the presented approach is easy to incorporate in any Finite Element code, so the practical relevance is high.