• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.167-178
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• 2000

An experimental study on step up filling method is carried out to reinforce the Yano method which is widely used to estimate volume ratio and self-weight consolidation settlement in reclamation area. This method considers actual reclamation construction in which dredged clay is continuously filled and rising of deposit height is presented as a result of volume decrease by height rising and self-weight consolidation. It measured the relationship between filling velocity and deposit rising velocity; calculated the total filling height which is needed to achieve the planned final deposit height, and its solid height and the time which is taken to finish the planned final deposit height; and on the basis of these calculated parameters, predicted the self-weight consolidation and volume change ratio in reclamation construction. Yano method is also used to predict the same conditions. 29.8% in self-weight consolidation, 31.1% in volume ratio, 40% in void ratio and water content is underestimated in Yano method compared to step up filling method.

• 한국해양학회지
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• v.28 no.2
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• pp.142-152
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• 1993

해양에 투기된 폐기물의 시공간적인 분포와 변화과정은 해양 물리학적 확산과 이 동, 생물학적 흡수 및 변환과정, 화학적 반응 및 상태변화등 여러 과정이 복합적으로 작용하여 일여난다. 이러한 폐기물의 해양투기가 해양생태계 및 환경보전에 미치는 여 러 가지 영향은 이에 대한 규제 및 적절한 운용을 통하여 원활한 해양생태 및 환경을 유지할 수 있도록 최소화되어야 한다. 해양투기의 최적화를 위하여서는 첫째, 생태학 적 배제원칙(biological exclusion)이 최우선적으로 고려되어야 하고 둘째, 생태계 및 수산자원 보존을 위하여 원활한 해수교환 및 물질확산이 극대화된 투기장소의 입지 선 정(hydrographic option)이 매우 중요하다. 둘째 로는 적법한 투기행위 및 적절한 투 기장 운용을 위한 감독 및 감시체제의 확립이 필요하다. 현재 우리 나라의 해양 폐기 물 투기는 초기의 단계에 있으나 최근 점차 요구되는 인접 해양국가 간의는 지역환경 협의체 구성 및 국가간 환경 부담 비용을 고려할 때 공해상의 해양투기는 더 이상 국 내적 문제가 아니므로 보다 신중한 해양투기 활동 및 타당성의 국토가 필요하다. 황해 에 위치한 투기장의 경우 현재까지의 관련자료를 검토할 때 적정 투기 규모 및 투기장 입지 선정, 그리고 불법 폐기물 투기가능성의 미비점에 대한 보완책이 필요한 것으로 사료된다.

• Journal of the Korean Geotechnical Society
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• v.30 no.9
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• pp.19-28
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• 2014

It is necessary to understand the behavior of the soils for the dredging constructions. The objective of this study is to estimate void ratio and density changes of the dredged soils by using the geophysical testing methods. A series of laboratory tests is performed to obtain geotechnical index properties of the specimen, retrieved from the west coastal of Korea. The sedimentation and self-weight consolidation tests are carried out with observing changes of the interfacial height and the elastic wave velocities. The same amounts of the soils are poured into the testing column at intervals of 12 hours until the interheight reaches to a certain level. After the completion of the sedimentatation and self-weight consolidation tests, downward permeability test is performed to assess a tidal influence in the nearshore. The mini resistance cone is penetrated into the specimen to measure the electrical resistivity with depth. All tests are completely finished, the weight of specimens are measured to calculate the void ratio with the depth. Experimental results show that the aspects of the self-weight consolidation are invisible during dredging process because of rapid sedimentation characteristics of ML. However, the elastic wave velocities increase with increasing in the effective stresses. During permeability test, measured permeability and the elastic wave velocities maintain almost identical values. Void ratio based on the elastic wave velocities changes linearly with time during the step dumpings. Void ratio estimated by the electrical resistivity represents the repeatedly layered depositions according to the step-by-step dumpings. Void ratio determined by soil sampling is similar to those of elastic waves and electrical resistivity profiles. This experimental study demonstrates that the geophysical testing methods may be an effective method for evaluating the behavior of dredged soils.

• Journal of the Korean GEO-environmental Society
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• v.3 no.1
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• pp.67-77
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• 2002

Volume change of the dredged soils is composed of the volume loss of soil particle flowing over an outflow weir with water and settlement due to both the self-weight consolidation in reclaimed layer and the desiccation at the surface of reclaimed layer. In order to estimate the amount of soil particles flowing over an outflow weir with water, the evaluation procedure of loss ratio of the dredged soils is proposed in the present study based on the Marsal's modified breakage theory and the results of hydrometer analyses. To verify a validity of the proposed procedure, evaluated loss ratio is compared with results from the other existing methods. The model test results and those of field test were compared and analyzed. Also, the variation of soil loss ratio was examined through the model test in the lab.

• Journal of the Korean Geotechnical Society
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• v.31 no.11
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• pp.49-60
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• 2015

Open-water sediment disposal has many applications in costal construction. Dumping of sediment in open water can be divided into descending stage under water and sedimentation stage on the seabed, and retained rate is evaluated from analyzed results of these two successive stages. Descending particle cloud have two distinct thermal and swam phase, and trajectory equations for each phase are derived to describe settling velocity and radius of particle cloud. For sedimentation stage, a numerical simulator is used to calculate growth factors for particle fiction angle and current velocity. Retained rate is defined as a mass rate of remained sediment inside the circle which has a center at dumping point on the sea level and user-defined effective radius. Retained rate map for Singapore coast is presented with water depth of 20 m, current velocity of 0.0~1.5 m/s, and effective radius of 5 m. It will decrease sediment mass loss during disposal operation and minimize surrounding environmental pollution.

• Journal of the Korean Geographical Society
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• v.43 no.3
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• pp.392-411
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• 2008

The purpose of this paper is to develop a method for exploring hotspot patterns of house price volatility where there is a high fluctuation in price and homogeneity of direction of price volatility. These patterns are formed when the majority of householders in an area show an adaptive tendency in their decision making. This paper suggests a method that consists of two analytical parts. The first part uses spatial scan statistics to detect spatial clusters of houses with a positive range of price volatility. The second part utilizes local Moran's I to evaluate the homogeneity of direction of price volatility within each cluster. The method is applied to the areas of Gangnam-Gu, Seocho-Gu, and Songpa-Gu in Seoul from August to November of 2003; the Participatory Government of Korea designated these areas and this period as the most speculative. The results of the analysis show that the area around Gaepo-Dong was as a hotspot before the Government's anti-speculative 10.29 policy in 2003; the house prices in the same area stabilized in October, 2003 and the area was identified as a coldspot in December, 2003. This case study shows that the suggested method enables exploration of hotspot of house price volatility at micro spatial scales which had not been detected by visual analysis.

• Journal of the Korean Data and Information Science Society
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• v.22 no.3
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• pp.449-458
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• 2011

Illegal waste dumping is one of the major problems that the government agency monitoring water quality has to face. Recently government agency installed COD (chemical oxygen demand) auto-monitering machines in river. In this article we provide an outlier detection algorithm using R based on the time series intervention model that detects some outlier values among those COD time series values generated from an auto-monitering machine. Through this algorithm using R, we can achieve an automatic algorithm that does not need manual intervention in each step, and that can further be used in simulation study.

• Journal of the Korean Geotechnical Society
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• v.18 no.2
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• pp.75-86
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• 2002

This paper presents sedimentation and consolidation characteristics of dredged soils mixed with sand materials through the self-weight consolidation tests adopting stepwise filling method. After completely throwing away dredged soils daily by flour kinds of S-C, which is the quantity of sand contained, results fi:om laboratory tests are compared with those from a new method using hyperbolic, which considers stage settling and consolidating characteristics, and those from the existing analyzing method. Liquid limit up to 65% had a large effect on consistency properties. Assuming that the settlement occurred only by clay content of dredged soils, it is shown that the clay void ratio is less than 2 and 4 respectively in case S-C is 0% and 50%. In the applied hyperbolic method, reinitialized curve has a linear behavior of a coefficient of correlation of almost 1, and the coefficient of slope and intercept except fur the specimen with the height of 10cm and 20cm had a tendency to fellow exponent function and a shape of zone settling and dispersing settling. The results computed by the applied hyperbolic method rather than the existing analyzing method coincide with those of laboratory tests. It is shown that the former is more suitable than the latter for the area considering the influence, of sand materials.

• Defense and Technology
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• no.1 s.143
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• pp.20-29
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• 1991

미래의 비행훈련은 기술수준이 보다 높아지면서 훈련의 효율은 높이면서 전투부대에서의 훈련을 감소시킴으로써, 경제성을 도모한다는 기본적인 목표를 잘 표시하고 있다. 미 공군의 EFS, PATS, BFTS/TTTS 역시 모두 훈련의 효율성과 경제성을 목표로 하고 있다. 특히 BFTS야말로 21세기중반까지 이 시대에 등장할 최신예전투기를 조종할 조종사를 훈련시켜야 될 SUPT의 최종단계 훈련이기 때문에 어떤 종류의 훈련을 시켜야 될 것인가를 판별하는 것이 가장 중요하다. 따라서 BFTS는 TTTS나 PATS에 비해서 선행기간과 개발기간이 길어질수밖에 없다

• Journal of the Korean Society for Railway
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• v.14 no.2
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• pp.143-150
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• 2011

This paper presents a preliminary study for air-tightness evaluation of vacuum tube structures for super-speed tube railway systems. The formula for flow rate of the air caused by the pressure difference of the inside and outside of the tube structure is derived based on Darcy's law. A test is then performed to measure the air-permeability of concrete with various compressive strengths, the result of which is used for analytical simulation of the air intrusion for a tube structure with a preliminarily defined section. It has been shown that concrete with the compressive strength of at least more than 50MPa is recommended for effective operation and maintenance of the vacuum pump systems, as the air-permeability of concrete is inversely proportional to the exponent of its compressive strength.