• 환경위생공학
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• 제12권2호
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• pp.43-49
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• 1997

Iron and manganese problems in ground water affect far more water systems than almost any other water quality concern. The purpose of this study is to find the optimum condition of ozonation for the removal of dissolved iron, manganese and other organics in the polluted ground water. We proposed 4mg/l, 8mg/l as optimum ozone dose for the removal of $Fe^{2+},{\;}Mn^{2+}$, respectively. The removal efficiencies of $COD_{Mn}$ and $COD_{Cr}$ in ozone dose of 2mg/l - 6mg/l were about 40-50%. The removal efficiency of $NH_{3}-N$ was about 30-40% at pH8.5. In conclusion, it needs further systematic study and research concerned to treatability of $Fe^{2+},{\;}Mn^{2+}$ and biodegradability of organic compounds using Ozonation followed by biological filtration process in ground water treatment train.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회 2차
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• pp.13-20
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• 2010

This paper presents the results of a numerical investigation on the ground deformation in deep excavation with emphasis on the groundwater lowering. Using the stress-pore pressure coupled analysis Consideration to the effect of ground excavation and groundwater interaction were carried out and a series of two-dimensional finite element model was employed to perform a parametric study on a wide range of soil profile and initial ground water table condition.

• 한국군사과학기술학회지
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• 제13권1호
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• pp.22-29
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• 2010

In this study, computational multi-body dynamics and structural vibration analyses including some impact condition have been conducted for the ground flight test system of the developed smart UAV model. Designed ground test system has four degree-of-freedom motions with limited motion control mechanism. Design safety margin designs for several structural components are tested and verified considering expected critical motions (pitching and rolling) of the test smart UAV model. Computational results for various analysis conditions are practically presented in detail. Futhermore, proper design modifications of the initially designed test equipment in order to guarantee or increase structural safety have been successfully conducted in the design stage.

• 한국지열·수열에너지학회논문집
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• 제6권1호
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• pp.23-28
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• 2010

The objective of this study is to develope ground heat exchanger using PHC pile used to building foundation, and it's element technology. So we made PHC piles into ground heat exchanger and evaluate it's performance. First, we studied PHC pile type, heat exchanger pipe, grouting materials, and present apartment house's foundation condition for PHC ground heat exchanger. As a result we designed BIGS(Building Integrated Geothermal System) prototype. Second, we applied BIGS to apartment houses' utility building in Osan built by Daelim. Third, we monitored heating performance of winter season. 1be result of heating performance was so good to apply to heat & cooling system in building.

• 한국지열·수열에너지학회논문집
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• 제11권2호
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• pp.7-11
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• 2015

Recently, as the demand for sustainable energy sources is increasing, ground-source heat pump (GSHP) systems are receiving growing attention. However, the initial cost of GSHP system is higher than it of the conventional systems, especially, in small-size buildings. Therefore, for the application to the small-size building, it is necessary to develop small-size ground heat exchanger with small-size buildings. In this study, analysis of unit-type heat exchanger due to grouting materials. As a result, 1492.14 W of heat exchange rate was acquired in the condition of cement-silica sand-graphite materials.

• 전기학회논문지
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• 제58권11호
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• pp.2242-2246
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• 2009

In this paper, a homogeneous dual composite right/left-handed (D-CRLH) transmission line (TL) is proposed by using a defected ground structure (DGS) on the ground plane. In order to satisfy a homogeneity condition of metamaterial, a subwavelength unit cell is designed by way of a spiral DGS and a meander stub. From a dispersion diagram, it is expected that the frequency bands for the left-handed (LH) property is 3.5 - 4.4 GHz. At 3.8 GHz in the LH band, backward propagating phenomenon is observed from full-wave analysis. The experimental results show that the proposed TL has a stop-band in 1.75 - 3.6 GHz.

• 한국항만학회지
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• 제10권2호
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• pp.69-90
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• 1996

This study is related to save the bearing capacity from using Meyerhof formula namely, static mechanics formula with the S.P.T(N value) of the soft ground and is to choose the soft ground improvement method by the using of total load for the proper method of the pile foundation and then to design the most suitable pile foundation to fit the actual circumstance. The purpose of this study is calculating the diameter of the pile foundation by static mechanics formula and introducing the optimum design condition from the result of the bearing capacity for using N value of the S.P.T obtained from the deep soft ground about the piles such as P.H.C pile, pipe and cast-in-place pile of big diameter, etc. As above-mentioned, it is considered that the use of P.H.C pile or pipe pile is advisable on the synthetical investigation and that the selection of cast-in-place pile method is desirable in terms of the constructive safety and durability.

• 한국정밀공학회지
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• 제12권4호
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• pp.46-54
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• 1995

This paper presents a simple method for measurenemt of roughness of ground surfaces. The present method utilizes fluxes of scattered lights condensed through lenses aligned along the specular direction. A theoretical analysis is preformed for the purpose of investigating the possibility of the method as well as determining the experimental condition. Experiments are also performed to show the effectiveness and robustness of the proposed method. The theoretical and experimental results show that the proposed method is simple enouth to implement and has a potential to identify a wide range of roughness of ground surfaces.

• 한국철도학회논문집
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• 제18권4호
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• pp.289-300
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• 2015

철도 전동 소음은 철도에서 발생하는 대표적인 소음으로서 차륜과 레일의 음향 조도에 의해 가진 된 차륜 및 레일의 진동으로부터 발생한다. 철도 전동 소음 해석 시 레일 방사 소음은 자유 공간에 놓인 레일의 음향 방사 파워를 이용해 원거리에서 계산하므로, 일반적으로 소음원 모델에 지면 반사를 고려하지 않는다. 그러나 레일 주위의 근접 음장을 해석하고 저감 대책을 적용하기 위해서는 지면에 의한 음파의 반사를 고려해야 한다. 본 논문에서는 파수유한요소/경계요소법을 이용해 지면에 의해 발생하는 레일 소음의 변화와 그 특성을 살펴보았다. 해석은 먼저 레일이 강체 지면에 부착된 경우와 레일 패드 높이만큼 강체 지면에서 이격된 경우에 대해 방사효율을 구하고 그 결과를 비교하였다. 이를 통해 레일과 강체 지면의 이격 여부에 따라 레일 방사 소음에 크게 변화함을 확인하였다. 둘째로는 지면에 임피던스 경계조건을 부여하고 레일에서 방사되는 음향 파워 및 지향 특성의 변화를 살펴보았다.

• 한국지반신소재학회논문집
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• 제17권1호
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• pp.127-137
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• 2018

쇄석다짐말뚝(Gravel Compaction Pile, 이하 GCP)는 느슨한 사질토지반이나 연약한 점토지반에 쇄석을 다지고 압입하여 원지반에 말뚝을 조성함으로써 지반을 개량하는 공법이다. 국내 GCP공법은 많은 연구자들이 실내실험, 현장실험 등을 이용해 GCP 복합지반의 응력거동을 분석하였으나, GCP 복합지반의 상부에 재하되는 매트기초의 강성 차이에 따른 거동분석은 다소 미미한 실정이다. 따라서 본 연구에서는 수치해석을 통해 기초의 강성 차이에 따라 응력분담비를 규명하고자 하였다. 이를 위해 유한요소 해석프로그램인 ABAQUS를 이용하여 치환율을 변화시켜 모델링하고, 강성 차이에 따라 복합지반의 응력분담비와, 침하량 및 최대 수평변위량을 분석하였다. 분석 결과, 강성기초의 하중재하시 응력분담비는 연성기초의 하중재하보다 높게 평가되었으며, 연성하중재하조건에서의 침하량은 강성조건에서 보다 다소 높은 경향이 나타났다. 이는 상부기초의 강성 차이에 대한 응력거동 특성을 명확히 규명해야 할 필요성이 있다고 판단된다. 또한, 최대 수평변위는 강성의 차이에 상관없이 일정한 위치에서 최대 변위가 발생하였다.