• 한국터널지하공간학회 논문집
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• 제7권2호
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• pp.133-141
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• 2005

저토피 구간에서 기존터널 하부에 새로운 터널을 교차하여 신설할 때에 하부 터널굴착으로 인하여 발생하는 교차부 주변지반의 거동을 대형모형실험과 수치해석을 통하여 연구하였다. 모형실험결과 교차 전 후의 하부터널 굴착에 따른 종방향 응력전이가 상부터널에 의하여 차단됨을 알 수 있었다. 수치해석결과에 의하면 측압계수 K = 0.38인 경우에 응력그림자 현상으로 단일터널 천단부에서의 최소주응력 감소는 상하교차터널의 천단에서보다 크게 발생한다. 직각교차터널에서는 기존상부터널의 영향으로 응력그림자 현상이 나타나 단일터널에 비하여 작은 응력감소를 보인다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 II
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• pp.943-946
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• 2003

This paper proposes new SPICE Macro-Model of MTJ(Magnetic Tunnel Junction). This Macro-Model has five I/O terminals, reproduces MR characteristics including hysteresis and behaves correctly to time varying input signals. Furthermore, this Model can be easily modified to various MTJs with different characteristics by simply varying internal parameters.

• 한국추진공학회지
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• 제24권5호
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• pp.56-64
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• 2020

29.7% 축소 NASA 표준 연구 모형에 대하여 소형 저속 풍동에서 시험을 수행하였다. 풍동시험 모형은 NASA Langley 연구소와 AIAA 항력추정 워크숍 위원회의 지침에 따라 알루미늄으로 제작하였다. 풍동의 능력 한계 등으로 상대적으로 낮은 레이놀즈수인 0.3 × 10⁶ 에서 정적 힘과 모멘트를 측정하였다. 세 가지 타입(핀 스팅, 블레이드 스팅, 벨리 스팅) 모형지지부에 대하여 피칭모멘트를 비교하였다. 보정된 벨리 스팅과 핀 스팅에 의한 피칭모멘트 보정량은 비슷하였으며 블레이드 스팅에 의한 피칭모멘트 값이 가장 적었다.

• 신재생에너지
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• 제4권2호
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• pp.87-93
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• 2008

Wind tunnel test for the 12% scaled model of NREL Phase VI wind turbine was conducted in KARI low speed wind tunnel for $2006{\sim}2007$. The 1st and 2nd test was designed to find out the wind tunnel test method for the blade manufacturing accuracy and surface treatment method by using the composite and aluminum blades. And the 3rd test was designed to study the scale effect. The chord extension method which was used for Bo-105 40% scaled model was adapted for scale effect correction. Test results shows that the chord extension method works well for the torque slope but the maximum torque for scaled model is about 8% below than the real scale model. New correction method to correct this offset was proposed.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1994년도 가을 학술발표회 논문집
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• pp.235-246
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• 1994

At pre-construction design stage, most of the design data are based on the site investigation results or property estimation which often does not provide satisfactory output for the tunnel analysis. Nonlinear FEM tunnel analysis was cariied out by Hoek-Brown model which is principly semi-empirical design method based on insitu rock descriptions, rock test results as well as field measurement data. The results of the analytical methods from Hoek-Brown model and Mohr-Coulomb model are compared with the sige measurement data from two-NATM tunnel construction sites. It was found that the Hoek-Brown model can be satisfactorily adopted as a feed back analysis technique in order to examin the safety of NATM tunnel at any construction stage.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.613-616
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• 2008

This study presents an IFC-based information model for standardized and integrated information management system of tunnel monitoring. Information items of tunnel monitoring were extracted from the Tunnel Design Standard of Ministry of Construction and Transportation. Then, the information items were compared with components of IFC 2x Edition3 model. Two main entities are added into the IFC model for generic representing of monitoring devices and data. IfcMonitoringElement which is composed of IfcMonitoringLogger and IfcMonitorinSensor is proposed to represent physical information of data loggers and sensors, and relationship between data logger and sensors. Besides, as an additional resource of IFC model, IfcMonitoringData is provided to express measured data from sensors and warning histories.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 봄 학술발표회 논문집
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• pp.309-314
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• 1999

In this paper, an application of finite element procedure fur tunnel failure analysis has been studied. The numerical model is applied to the simulation of a series of plane strain laboratory tests on the small scale model of a shallow tunnel. By comparing experimental and numerical results some conclusions are drawn on the effectiveness of the numerical approach. The findings from these numerical experiments show relative differences in the pattern of failure behaviour for shallow tunnels.

• Geomechanics and Engineering
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• 제29권3호
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• pp.301-310
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• 2022

Accurate prediction of mixed ground conditions ahead of a tunnel face is of vital importance for safe excavation using tunnel boring machines (TBMs). Previous studies have primarily focused on electrical resistivity surveys from the ground surface for geotechnical investigation. In this study, an FE (finite element) numerical model was developed to simulate electrical resistivity surveys for the prediction of risky mixed ground conditions in front of a tunnel face. The proposed FE model is validated by comparing with the apparent electrical resistivity values obtained from the analytical solution corresponding to a vertical fault on the ground surface (i.e., a simplified model). A series of parametric studies was performed with the FE model to analyze the effect of geological and sensor geometric conditions on the electrical resistivity survey. The parametric study revealed that the interface slope between two different ground formations affects the electrical resistivity measurements during TBM excavation. In addition, a large difference in electrical resistivity between two different ground formations represented the dramatic effect of the mixed ground conditions on the electrical resistivity values. The parametric studies of the electrode array showed that the proper selection of the electrode spacing and the location of the electrode array on the tunnel face of TBM is very important. Thus, it is concluded that the developed FE numerical model can successfully predict the presence of a mixed ground zone, which enables optimal management of potential risks.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권6호
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• pp.728-732
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• 2014

Macro-model of magnetic tunnel junction (MTJ) for spin transfer torque magnetic random access memory (STT-MRAM) has been developed. The macro-model can describe the dynamic behavior such as the state change of MTJ as a function of the pulse width of driving current and voltage. The statistical behavior has been included in the model to represent the variation of the MTJ characteristic due to process variation. The macro-model has been developed in Verilog-A.

• 터널과지하공간
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• 제17권6호
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• pp.453-463
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• 2007

Terzaghi터널토압 이론은 shield 및 도심 NATM터널의 설계토압으로 현재까지도 사용되고 있다. 본 논문에서 지반의 변형거동과 한계상태를 가정한 Terzaghi 토압과의 상호 관계에 관한 조사를 위해 Terzaghi 터널토압이론, 2차원 실내 터널 모형 실험과 변형률 연화모델을 기본으로한 비선형 수치해석을 실시하였다. 굴착에 따른 터널 토압와 지반 변형거동의 폭넓은 이해와 그들의 상호작용에 대한 효율적인 활용은 경제적인 터널 지보설계와 안정한 시공을 이끌 수 있다.