• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1997년도 가을 학술발표회 논문집
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• pp.315-324
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• 1997

• 한국지반공학회지:지반
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• 제12권6호
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• pp.185-198
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• 1996

EPS(Expanded Polystyrene)를 이용한 하중경감공법은 초경량재(20~30kg/m3)인 EPS를 본 연구는 보강토 토류벽체의 뒤채움재로서 폐 EPS 조각을 혼합한 경량의 성토재료를 개발, 활용하기 위한 기초연구로서, 우리나라에 광범위하게 분포하는 화강풍화토와 폐 EPS조각을 혼합한 경량성토재에 대해 공학적 특성파악을 위한 기본물성시험을 수행하였고, 또한 국내에서 판매되고 있는 두가지 대표적인 강성 및 연성 지오그리드 보강재에 대해 폐 EPS조각의 혼합비를 변화시 켜가며 실내인발시험을 수행하였으며, 이들 시험결과를 토대로 하여 폐 EPS조각 혼합경량토의 토질공학적 특성과 지오그리드-혼합경량토 사이의 마찰특성을 분석.평가하였다. 또한 본 연구에서는, 인장력 이외에도 다짐하중 및 상재하중 등 수직하중에 의한 압축력이 추가로 동시에 작용하는 경우의 지오그리드의 인장력-변형률 관계를 고려할 수 있는 마찰강도 산정방법을 제시하였으며, 이 방법을 토대로 하여 지오그리드-혼합토 사이의 마찰강도 평가시 적용가능한 보정계수 a1 및 a2 값의 범위를 제시하였다.

• 한국정밀공학회지
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• 제29권12호
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• pp.1351-1359
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• 2012

Due to the development of electric and hybrid vehicles, the trend has changed from hydraulic power steering system to electric power steering system (EPS). In this paper, design parameters are deduced through the structural analysis based on the finite element analysis for the intermediate shaft of the EPS on the market. By analyzing the design parameters, the structure design is improved to support the required high torque on the EPS. The numerical analysis is performed to obtain the improved design of the intermediate shaft model and the analysis results are compared with the existing model. It is noted through this numerical approach that the improved design of the intermediate shaft can be acquired the structural safety and high stiffness than existing model.

• Journal of Welding and Joining
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• 제21권5호
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• pp.525-533
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• 2003

The dimensional accuracy and global roughness between successive layers of VLM-s, which is a new rapid prototyping process using hotwire cutter and EPS foam, depend significantly on the operating parameters of hotwire cutter. In the present study, the effect of cutting angle on the kerf width and edge shape in hotwire cutting of EPS foam for the case of single-sloped cutting with one cutting angle was investigated. Through single-sloped cutting tests, the modified relationship between kerf width and effective heat input, considering the effect of the cutting angle, and the relationship between the melted area and the cutting angle were obtained. In order to investigate the effect of cutting angles on the thermal field in EPS foam, transient heat transfer analyses using single-sloped volumetric heat flux model and locally-conformed mesh were performed. Through the comparison between experimental and numerical results, it was shown that the proposed analysis model is needed to estimate the three-dimensional temperature distribution of the EPS foam for the case of single-sloped hotwire cutting.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.947-951
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• 2002

During the hotwire cutting of EPS foam sheet, the dimensional accuracy and part quality of the cut par are highly dependent upon the thermal field in the EPS. The thermal field is determined by operating parameters such as heat input, cutting speed and cutting angle. The objective of this study is to investigate into the influence of cutting angle on the kerfwidth and part quality of the cut part in hotwire cutting of EPS foam using the experiments and the numerical analysis in the case of a single sloped cutting. In order to estimate an accurate temperature field, the transient thermal analysis using a moving coordinate system and the sloped heat flux model is carried out. From the results of the experiments and the analysis, it has been found that the effect of cutting angle on the kerfwidth and the melted area at the edge are 0.1 mm and 0.11 m$m^2$ respectively. The results of the experiments show that the surface roughness is not appreciably influenced by the cutting angle.

• 한국지반공학회지:지반
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• 제12권5호
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• pp.127-136
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• 1996

초 경량재인 E.P.S(20~30kg/m3)를 성토재로 사용하여 부족한 지지력과 침하에 대한 안정 성을 확보하는 방법이 최근 많이 사용되고 있다. 국내에서는 1993년 인천의 연약지반상 교대 됫채움재로 이 공법이 처음 사용된 이래 점차 활용이 늘어나고 있는 실정이다. 그러나 아직까지 EPS를 성토 재료로 사용한 지반에서 EPS의 거동을 예측하기 위한 합리적인 수치해석 모델이 제시되어 있지 않고 일축압축강도 및 크리프시험 결과에 따른 설계강도만이 제안되어 있는 실정이다. 따라서 본 연구에서는 성토재료로 사용된 EPS의 수치해석 모델을 제시하기 위하여 성토재로 사용되는 여러 종류 밀도의 EPS에 대해 구속압을 변화시키면서 삼축압축시험을 실시하였다. 삼축압축시험 결과를 분석하여 EPS의 축방향 변형률-응력 관계와 이의 도함수 그리고 포아송비를 밀도와 구속압에 의한 함수식으로 나타낼 수 있었다. 이 관계로부터 EPS의 거동을 예측하기 위한 비선형모델을 제안하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.176-180
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• 2002

All types of VLM-s process include the linear heat cutting of EPS foam to generate a layer with 3D shape. The dimensional accuracy and part quality of the cut part are dependent on the thermal characteristics in the EPS foam. The thermal characteristics are determined by operating parameters such as an effective heat input and cutting angle. The objective of this study is to investigate into the influence of cutting angle on the kerfwidth and the melted length of the cut part using the numerical analysis and the experiments in generally sloped cutting with two cutting angles. In order to estimate an accurate temperature field, the transient thermal analysis using moving coordinate system, the fully conformed mesh and the heat flux model with two cutting angles is carried out. From the results of the analysis and the experiments, it has been found that the influence of the rotational angle about x-axis in which the rotational axis is normal with hotwire cutting direction is appreciably negligible in comparison with that of the rotational angle about y-axis.

• 대한기계학회논문집A
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• 제29권9호
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• pp.1169-1174
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• 2005

Imprint lithography is a promising method for high-resolution and high-throughput lithography using low-cost equipment. In particular, ultraviolet-nanoimprint lithography (UV-NIL) is applicable to large area imprint easily. We have proposed a new UV-NIL process using an elementwise patterned stamp (EPS), which consists of a number of elements, each of which is separated by channel. Experiments on UV-NIL are performed on an EVG620-NIL using the EPS with 3mm channel width. The replication of uniform sub 70 nm lines using the EPS is demonstrated. We investigate the nonuniformity of residual layer caused by wafer deformation in experiment with varying wafer thickness. Severely deformed wafer works as an obstacle in spreading of dropped resin, which causes nonuniformity of thickness of residual layer. Numerical simulations are conducted to analyze aforementioned phenomenon. Wafer deformation in the process is simulated by using a simplified model, which is a good agreement with experiments.

• Computers and Concrete
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• 제20권6호
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• pp.689-704
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• 2017

The paper presents experimental and numerical investigations of prefabricated composite structural building reinforced concrete slabs with the insulating material for a residential building construction. The building slabs were composed of concrete and expanded polystyrene. In experiments, the slabs in the full-scale 1:1 were subjected to vertical concentrated loads and failed along a diagonal shear crack. The experiments were numerically evaluated using the finite element method based on two different constitutive continuum models for concrete. First, an elasto-plastic model with the Drucker-Prager criterion defined in compression and with the Rankine criterion defined in tension was used. Second, a coupled elasto-plastic-damage formulation based on the strain equivalence hypothesis was used. In order to describe strain localization in concrete, both models were enhanced in the softening regime by a characteristic length of micro-structure by means of a non-local theory. Attention was paid to the formation of critical diagonal shear crack which was a failure precursor.

• 대기
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• 제25권2호
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• pp.375-387
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• 2015

A Selected Multi-model CONsensus (SMCON) technique was developed and verified for the tropical cyclone track forecast in the western North Pacific. The SMCON forecasts were produced by averaging numerical model forecasts showing low 70% latest 6 h prediction errors among 21 models. In the homogeneous comparison for 54 tropical cyclones in 2013 and 2014, the SMCON improvement rate was higher than the other forecasts such as the Non-Selected Multi-model CONsensus (NSMCON) and other numerical models (i.e., GDAPS, GEPS, GFS, HWRF, ECMWF, ECMWF_H, ECMWF_EPS, JGSM, TEPS). However, the SMCON showed lower or similar improvement rate than a few forecasts including ECMWF_EPS forecasts at 96 h in 2013 and at 72 h in 2014 and the TEPS forecast at 120 h in 2013. Mean track errors of the SMCON for two year were smaller than the NSMCON and these differences were 0.4, 1.2, 5.9, 12.9, 8.2 km at 24-, 48-, 72-, 96-, 120-h respectively. The SMCON error distributions showed smaller central tendency than the NSMCON's except 72-, 96-h forecasts in 2013. Similarly, the density for smaller track errors of the SMCON was higher than the NSMCON's except at 72-, 96-h forecast in 2013 in the kernel density estimation analysis. In addition, the NSMCON has lager range of errors above the third quantile and larger standard deviation than the SMCON's at 72-, 96-h forecasts in 2013. Also, the SMCON showed smaller bias than ECMWF_H for the cross track bias. Thus, we concluded that the SMCON could provide more reliable information on the tropical cyclone track forecast by reflecting the real-time performance of the numerical models.