• 한국정밀공학회지
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• 제17권6호
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• pp.143-152
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• 2000

The comer filling in shaped drawing process is an important characteristic, unlike the round drawing. It has also influence on the dimensional accuracy of the product. In this study, therefore, the shaped drawing process has been simulated by the three dimensional rigid-plastic finite element method in order to investigate the effect of process variables such as reduction in area and semi-die angle to the corner filling. The artificial neural network has also been introduced to reduce the number of simulations. To verify the results of simulations, experiments have been performed on the real industrial products. According to the results, the main process variable on the corner filling is the combination of semi-die angle in the irregular shaped drawing processes, but in the case of regular shaped drawing processes, reduction in area has great influence on the corner filling.

• International Journal of CAD/CAM
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• 제6권1호
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• pp.193-198
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• 2006

Plunge milling is the fastest way to mill away large volumes of metal in the axial direction. The residual volume (inaccessible volume by the plungers) is minimized when selecting a specific direction of filling. This direction is known as the optimal inclination angle for filling of the plunged area. This paper proposes a new algorithm to calculate the optimal inclination angle of filling and to fill the plunged area with multi-plungers sizes. The proposed algorithm uses the geometry of the 2D area of the shape that being cutting to estimate the optimal inclination angle of filling. It is found that, the optimal inclination angle for filling of the plunged area is the same direction as the longer width of the equivalent convex polygon of the boundary contour. The results of the tested examples show that, the residual volume is minimized when comparing the proposed algorithm with the previous method.

• 한국농촌건축학회논문집
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• 제23권3호
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• pp.1-8
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• 2021

Rural multi-purpose buildings needs to ensure their safety against various disasters. Therefore, a pile foundation, which is a foundation type that can transmit the load of the structure to the bedrock layer, has been designed. The pile foundation method is largely divided into driving piles method and pre-bored pile method. Recently, in order to respond to the Noise and Vibration Control Act and related environmental complaints, construction of pile foundation adopts pre-bored pile method. The bearing capacity of the pre-bored pile method is calculated through a load test in situ. However, a disadvantage stems in that it is difficult to measure the ultimate bearing capacity due to field conditions. Therefore, in this study, the skin frictional force of pre-bored pile was measured through a model test in laboratory for each pile filling material. In result, the pile filling material with using circulating resources shows superior skin frictional force than ordinary portland cement. This study also judged that the result can be applied in place of ordinary Portland cement in the field.

• Restorative Dentistry and Endodontics
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• 제16권2호
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• pp.118-125
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• 1991

Eighty - eight recently extracted teeth were used to evaluate the leakage characteristics of the following retrofilling materials; amalgam, zinc oxide eugenol cement, glass - ionomer cement, and cermet glass - ionomer cement. Root canals were prepared with step - back method and obturated with gutta percha and zinc oxide eugenol sealer. Root apex were resected 2 mm from apex and class I cavities were prepared with 2 mm or 4 mm depth. The cavities were filled with above materials. After application of varnish on all surface except resected surface, the roots were placed in 1 % methylene blue solution for 6 days. After longitudinal polishing to expose cental parts of filled materials, penetrated depths of dye were measured. The results were as follws. 1. As retrofilling material, glass ionomer cement filling groups showed less leakage than the other groups except zinc oxide eugenol cement filling group(p<0.01). 2. Amalgam filling groups had greater leakage than zinc oxide eugenol cement filling group(p<0.01). 3. 4 mm depth of retrofilled cavity had no effect on leakage characteristics compared with 2 mm depth cavity(p>0.05). 4. Glass ionomer cement and cermet glass ionomer cement filling groups showed less apical leakage than amalgam filling groups. But there was no statistical significance(p>0.05). 5. There was no difference in apical leakage between glass ionomer cement filling groups and cermet glass ionomer cement filling groups(p>0.05).

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1994년도 추계학술대회 논문집
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• pp.133-140
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• 1994

In this paper, we have proposed a new method to determine the initial billet for the forged products using a function approximation in neural networks. the architecture of neural network is a three-layer neural network and the back propagation algorithm is employed to train the network. By utilizing the ability of function approximation of neural network, an optimal billet is determined by applying nonlinear mathematical relationship between shape ratio in the initial billet and the final products. A volume of incomplete filling in the die is measured by the rigid-plastic finite element method. The neural network is trained with the initial billet shape ratio and that of the un-filled volume. After learning, the system is able to predict the filling region which are exactly the same or slightly different to results of finite element method. It is found that the prediction of the filling shape ratio region can be made successfully and the finite element method results are represented better by the neural network.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.551-556
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• 2001

The filling pattern technique based on the finite element method and Eulerian mesh advancement approach has been developed to analyze incompressible transient viscous flow with free surfaces. The governing equation for flow analysis is Navier-Stokes equation including inertia and gravity effects. The penalty and predictor-corrector methods are used effectively for finite element formulation. The flow front surface and the volume inflow rate are calculated using the filling pattern technique to select an adequate pattern among four filling patterns at each triangular control volume. Using the proposed numerical technique, the collapse of a dam has been analyzed to predict flow phenomenon of fluid and the predicted front positions versus time have been compared with the reported experimental result.

• 한국산학기술학회논문지
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• 제21권2호
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• pp.175-181
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• 2020

본 연구는 도심지에서 좁은 폭 구간에 실시하는 물다짐 공법의 적정 시공방법 제안을 연구목적으로 한다. 도심지 차도나 보도의 도로함몰로 차량의 파손, 인명의 손실 등이 발생할 수 있다. 공사장 인근에서 발생하는 도로함몰의 주요 원인은 부실시공이다. 원인조사 결과 약 25~49%가 굴착복구 미흡으로 발생하는 것으로 발표되었다. 굴착복구 시공은 장비 혹은 인력으로 실시하며, 다짐장비나 인력으로 다짐이 어려운 소폭의 관로 되메우기, 흙막이가시설과 구조물 사이 협소 공간 되메우기 등을 수행할 때는 통상적으로 물다짐 공법을 사용하고 있다. 그러나 물다짐에 관한 다짐원리와 시공 조건 관련 표준시방 및 품질관리 기준은 미흡한 상태이다. 이에 본 연구에서는 물다짐 공법에 대해서 다짐원리 및 적정 되메우기 재료와 다짐효율에 관한 실내모형시험을 수행하고, 현장시공 현황 및 문제점을 조사·분석하여 물다짐 공법의 가이드라인을 제시하였다. 결론적으로 물다짐 공법의 원리를 분석한 결과 투기하는 되메우기 재료는 입도분포와 투수성이 주요 인자로 입도 및 투수계수의 세부기준을 제시하였고, 시공방법은 다짐효율을 높이기 위해 하부 배수층을 확보한 상태로 0.3m 단위로 층별 물다짐을 수행하여 상대다짐도 90%이상의 다짐품질을 확보해야 한다. 또한 물다짐이 완료된 상태에서 엄지말뚝을 인발한 경우 교란범위인 H-pile 단면기준으로 폭(B)의 1.5배, 높이(H)의 1.0배 주변 지반에 추가 물다짐을 수행하여야 한다.

• Journal of Electrical Engineering and Technology
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• 제11권1호
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• pp.135-142
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• 2016

Generally, closed slots are adopted to reduce the water friction loss in both the stator and the rotor of water filling submersible motor due to the special environment of operation. One of the obvious differences between the traditional induction motors and water filling submersible motors is that the submersible motors only need relatively smaller starting torque. This paper aims to analyze the slot leakage reactance of water filling submersible motor during starting transient operation. An improved analytical method which considered the magnetic saturation of the slot bridge and the skin effect of rotor bars is proposed. The slot permeance factor which has a direct impact on the slot leakage reactance is calculated. Then finite element models with different stator slot types are constructed and search coils are introduced to measure the slot flux linkage. Moreover, the starting performances of the models with two typical stator slots are compared and the flux leakage characteristics are obtained. Finally, the results obtained by finite element method are very close to the results obtained by analytical method.

• 터널과지하공간
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• 제24권5호
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• pp.373-385
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• 2014

최근 국내에서는 폐광산 지반보강공사를 실시함에 있어 수압식 충전법을 적용하는 사례가 증가하고 있으나 효율적인 충전법 적용을 위한 다양한 연구가 미흡한 실정이다. 본 연구에서는 수압식 충전공법의 충전효율 개선을 위한 충전재료의 입도, 충전관의 형태 및 충전관 직경을 변경해 가면서 현장실험을 실시하였다. No.100체 통과백분율이 16.3% 인 모래를 이용하여 수직관 및 이경티관의 종류에 따른 충전량을 실험결과, 수직관을 이용하여 수로관에 충전한 경우 모래 충전량이 28.84 ton이였고, 100 mm 이경티관을 사용하여 충전한 경우 모래 충전량이 42.62 ton, 80 mm 이경티관을 사용하여 충전한 경우 모래 충전량이 53.33 ton, 50 mm 이경티관을 사용하여 충전한 경우 모래 충전량이 63.33 ton으로 각각 약 47.8%, 84.9%, 119.6% 증가하는 것을 확인할 수 있었다. 이는 단순 충전관의 형태만 변경해도 충전 효과를 극대화 할 수 있을 것으로 기대된다.

• Geomechanics and Engineering
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• 제36권1호
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• pp.27-37
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• 2024

The roof-filling body system stability plays a key role in gob-side entry retained (GER). Taking the GER of the 1103 belt transportation roadway in Heilong Coal Mine as engineering background, stability analysis of roof-filling body system was conducted based on the cusp catastrophe theory. Theoretical results showed that the current design parameters of 1103 belt transportation roadway could ensure the roof-filling body system stable during the resistance-increasing support stage of the filling body and the stable support stage of the filling body. Moreover, a verified global numerical model in FLAC3D was established to analyze the failure characteristics including surrounding rock deformation, stress distribution, and plastic zone. Numerical simulation indicated that the width-height ratio of the filling body had a great influence on the stability of the roof-filling body system. When the width-height ratio was greater than 0.62, with the decrease of the width-height ratio, the peak stress of the filling body gradually decreased; when the width-height ratio was greater than 0.92, as the distance to the roadway increased, the roof stress increased and then decreased. The theoretical analysis and numerical simulation findings in this study provide a new research method to analyze the stability of the roof-filling body system in GER.