• 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.

• 한국환경과학회지
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• 제13권8호
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• pp.721-731
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• 2004

The dispersion of suspended particulates in the coastal complex terrain of mountain-inland basin (city)-sea, considering their recycling was investigated using three-dimensional non-hydrostatic numerical model and lagrangian particle model (or random walk model). Convective boundary layer under synoptic scale westerly wind is developed with a thickness of about I km over the ground in the west of the mountain, while a thickness of thermal internal boundary layer (TIBL) is only confined to less than 200m along the eastern slope of the mountain, below an easterly sea breeze circulation. At the mid of the eastern slop of the mountain, westerly wind confronts easterly sea breeze, which goes to the height of 1700 m above sea level and is finally eastward return flow toward the sea. At this time, particulates floated from the ground surface of the city to the top of TIBL go along the eastern slope of the mountain in the passage of sea breeze, being away the TIBL and reach near the top of the mountain. Then those particulates disperse eastward below the height of sea-breeze circulation and widely spread out over the coastal sea. Total suspended particulate concentration near the ground surface of the city is very low. On the other hand, nighttime radiative cooling produces a shallow nocturnal surface inversion layer (NSIL) of 200 m thickness over the inland surface, but relatively thin thickness less than 100m is found near the mountain surface. As synoptic scale westerly wind should be intensified under the association of mountain wind along the eastern slope of mountain to inland plain and further combine with land-breeze from inland plain toward sea, resulting in strong wind as internal gravity waves with a hydraulic jump motion bounding up to about 1km upper level in the atmosphere in the west of the city and becoming a eastward return flow. Simultaneously, wind near the eastern coastal side of the city was moderate. Since the downward strong wind penetrated into the city, the particulate matters floated near the top of the mountain in the day also moved down along the eastern slope of the mountain, reaching the. downtown and merging in the ground surface inside the NSIL with a maximum ground level concentration of total suspended particulates (TSP) at 0300 LST. Some of them were bounded up from the ground surface to the 1km upper level and the others were forward to the coastal sea surface, showing their dispersions from the coastal NSIL toward the propagation area of internal gravity waves. On the next day at 0600 LST and 0900 LST, the dispersed particulates into the coastal sea could return to the coastal inland area under the influence of sea breeze and the recycled particulates combine with emitted ones from the ground surface, resulting in relatively high TSP concentration. Later, they float again up to the thermal internal boundary layer, following sea breeze circulation.

• 천문학회지
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• 제36권spc1호
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• pp.101-107
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• 2003

The magnetosphere is often perturbed by impulsive input such as interplanetary shocks and solar wind discontinuities. We study how these initial perturbations are propagating within the magnetosphere over various latitude regions by adopting a three-dimensional numerical dipole model. We examine the wave propagation on a meridional plane in a time-dependent manner and compare the numerical results with multi-satellite and ground observations. The dipole model is used to represent the plasmasphere and magnetosphere with a realistic Alfven speed profile. It is found that the effects of refraction, which result from magnetic field curvature and inhomogeneous Alfven speed, are' found to become important near the plasmapause. Our results show that, when the disturbances are assumed at the subsolar point of the dayside magnetosphere, the travel time becomes smaller to the polar ionosphere compared to the equatorial ionosphere.

• 한국소음진동공학회논문집
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• 제12권3호
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• pp.236-242
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• 2002

This paper presents some advanced and supplemental methods to enhance the accuracy In case of calculating geometric divergence attenuation, attenuation by multiple screening structures, ground attenuation at unflat surfaces of sound during propagation outdoors by the methods specified in ISO 9613-2. Moreover, a calculation method for considering short-term wind effect, specified in ASJ Model-1998, is also introduced. To verity the accuracy of adopted methods, we have carried out highway traffic noise prediction and measurement at tile twelve locations appearing representative road shapes and structures, such as flat, retained cut, elevated, barrier-constructed roads. From the results, we have confirmed the predicted results show good correspondence with the measured at direct, diffracted and reflected sound fields within 30 m from the center of near side lane.

• 한국터널지하공간학회 논문집
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• 제18권2호
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• pp.235-244
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• 2016

해저터널 시공 중 단층, 파쇄대 및 미고결층 등의 취약한 지반조건에서 일어나는 문제점을 극복하기 위해 시공 중 그라우팅을 진행한다. 암반에서 그라우팅은 주로 불연속면을 따라 주입되므로 절리의 분포, 거칠기 또는 폭과 같은 절리 인자들이 그라우팅 보강암반의 물성에 지대한 영향을 미친다. 해저터널 주변의 그라우팅 보강암반은 해저환경에서 정수압을 다 부담하여 장기적인 열화와 미세구조변화 및 균열 등이 발생하며 암반물성이 시간에 따라 변하므로 그라우팅으로 인한 해저터널 주변암반의 장기적인 거동평가가 요구된다. 본 연구에서는 실내실험을 통해 다양한 축 응력, 양생기간 및 절리조건에서 그라우팅 보강암반의 탄성파 전달특성을 분석하였고 국내에서 사용되는 다양한 암반분류법들의 탄성파 기준을 고려하여 그라우팅 보강암반의 보강정도를 탄성파 속도로 추론하였다.

• 화약ㆍ발파
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• 제31권1호
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• pp.23-32
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• 2013

발파, 브레이커, 진동로울러 및 파일 작업과 같은 건설공정이 있을 경우, 건설 작업 인접 지역에서는 피해가 발생할 수 있다. 수중 소음의 경우, 지반진동이 고체 전달음의 형태로 전달된다. 이와 같은 수중소음은 강이나 바다 혹은 육지의 양식장에 피해를 유발할 수 있다. 본 연구는 발파, 천공, 브레이커 및 진동로울러와 같은 작업 공정으로 인하여 발생된 지반진동이 수중소음으로 입사될 때의 소음값 및 주파수를 분석하였다. 수중 소음 측정시에는 수중소음기 (TC 4013)을 활용하였으며, 저장 및 분석은 Prosig 프로그램을 활용하였다.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 2003년도 International Symposium on Clean Environment
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• pp.19-26
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• 2003

The dispersion of recycled particulates in the complex coastal terrain containing Kangnung city, Korea was investigated using a three-dimensional non-hydrostatic numerical model and lagrangian particle model (or random walk model). The results show that particulates at the surface of the city that float to the top of thermal internal boundary layer (TIBL) are then transported along the eastern slope of the mountains with the passage of sea breeze and nearly reach the top of the mountains. Those particulates then disperse eastward at this upper level over the coastal sea and finally spread out over the open sea. Total suspended particulate (TSP) concentration near the surface of Kangnung city is very low. At night, synoptic scale westerly winds intensify due to the combined effect of the synoptic scale wind and land breeze descending the eastern slope of the mountains toward the coast and further seaward. This increase in speed causes development of internal gravity waves and a hydraulic jump up to a height of about 1km above the surface over the city. Particulate matter near the top of the mountains also descends the eastern slope of the mountains during the day, reaching the central city area and merges near the surface inside the nocturnal surface inversion layer (NSIL) with a maximum ground level concentration of TSP occurring at 0300 LST. Some particulates were dispersed following the propagation area of internal gravity waves and others in the NSIL are transported eastward to the coastal sea surface, aided by the land breeze. The following morning, particulates dispersed over the coastal sea from the previous night, tend to return to the coastal city of Kangnung with the sea breeze, developing a recycling process and combine with emitted surface particulates during the morning. These processes result in much higher TSP concentration. In the late morning, those particulates float to the top of the TIBL by the intrusion of the sea breeze and the ground level TSP concentration in the city subsequently decreases.

• 한국음향학회지
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• 제34권1호
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• pp.52-59
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• 2015

국내 철도의 환경 소음 예측을 위해서 기존에는 총합 소음도의 거리별 경험식에 기초한 모델을 이용하였던 바, 교량 주변 소음도를 계산하는 데에도 거리만의 함수를 이용하였다. 그러나 콘크리트교에서는 수음점의 거리뿐만 아니라 위치에 따라서도 소음도가 변화한다. 본 논문에서는 철도 콘크리트교에서 교량 상판에 의한 회절 및 지면 효과를 고려한 소음전파 예측모델을 도출하였으며, 이때 ISO 9613-2의 소음 전파 모델을 이용하였다. 고속철도 콘크리트 교 주변 소음도에 대한 예측값을 실제 측정결과와 비교하였으며, 그 결과 본 예측 모델이 비교적 작은 오차를 냄을 확인하였다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 춘계 학술발표회논문집
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• pp.50-58
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• 2003

We have developed a locally variable time-step scheme matching with discontinuous grids in the flute-difference method for the efficient simulation of seismic wave propagation. The first-order velocity-stress formulations are used to obtain the spatial derivatives using finite-difference operators on a staggered grid. A three-times coarser grid in the high-velocity region compared with the grid in the low-velocity region is used to avoid spatial oversampling. Temporal steps corresponding to the spatial sampling ratio between both regions are determined based on proper stability criteria. The wavefield in the margin of the region with smaller time-step are linearly interpolated in time using the values calculated in the region with larger one. The accuracy of the proposed scheme is tested through comparisons with analytic solutions and conventional finite-difference scheme with constant grid spacing and time step. The use of the locally variable time-step scheme with discontinuous grids results in remarkable saving of the computation time and memory requirement with dependency of the efficiency on the simulation model. This implies that ground motion for a realistic velocity structures including near-surface sediments can be modeled to high frequency (several Hz) without requiring severe computer memory

• 화약ㆍ발파
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• 제33권2호
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• pp.25-39
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• 2015

수중 암반 제거 방법은 화약을 사용한 수중발파와 크레인에 장착된 쇄암봉 낙하 충격을 이용하는 방법 등이 널리 이용된다. 이와 같은 암반 제거 방법은 환경적인 요인에서 지반 진동과 수중 소음을 유발하게 된다. 본 연구 대상 현장은 하역 부두의 접안능력을 향상시키기 위해 기 설치된 잔교식 돌핀 구조물에 근접한 지역의 수중 기반암을 쇄암봉 낙하에 의해 제거하도록 설계되어 있다. 시험시공을 통하여 쇄암봉 낙하 충격으로 유발되는 진동에 대한 계측, 평가를 거쳐 진동 추정식을 획득하였고, 이를 본 공사에 반영하여 구조물에 대한 안전성을 확보하였다.