• 한국터널지하공간학회 논문집
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• 제24권5호
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• pp.375-393
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• 2022

본 논문은 이수식 쉴드TBM의 이수분출 안정성 및 세그먼트라이닝 부력에 대한 안정성 평가법의 제안에 대한 내용을 다루고 있다. 토피가 얇은 하·해저터널 건설을 위해 이수식 쉴드TBM 적용 시 이수분출 안정성 및 세그먼트라이닝 부력 안정성을 평가하여야 하는데 현재 적용되는 이론식은 다소 복잡함에 따라 실무적으로 계산이 불편한 문제점이 있다. 본 연구에서는 이수분출 안정성 및 세그먼트라이닝 부력 안정성 평가방법을 고찰하고 터널 계획단계에서 간편하게 이수분출 안정성과 부력 안정성을 평가하는 간편도표를 제안하였다. 또한, 강도감소법을 활용한 세그먼트라이닝에 작용하는 부력 안전율을 평가하고 이론식에 의한 부력 안전율과 비교·분석을 수행하였다. 본 연구에서 제시된 이수분출 및 부력 안정성 평가를 위한 간편도표는 하·해저터널 계획 및 설계 시 유용하게 활용될 수 있을 것으로 기대된다.

• 한국산학기술학회논문지
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• 제9권5호
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• pp.1119-1124
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• 2008

본 연구는 성형해석 및 실험적 방법을 통하여 페트 용기의 두께 편차를 최소화하기 위한 프리폼 최적화 설계를 수행하였다. 사출성형과정을 정확하게 묘사하기 인하여 3차원 모델을 이용하여 충진, 보압 및 냉각해석을 통하여 최적의 프리폼 설계변수를 설정하였으며, 이 결과를 이용하여 블로우 성형해석을 수행하였다. 성형해석결과를 평가하기 위한 사출성형 및 블로우 성형 실험을 수행하였으며, 실험결과와 해석결과는 정성적으로 일치하는 것을 확인하였다. 이러한 실험결과 데이타를 설계에 반영함으로서 최적의 프리폼 형상을 얻을 수가 있었다.

• 소성∙가공
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• 제10권7호
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• pp.525-533
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• 2001

PET bottles are main]y manufactured by the stretch blow-molding process. In order to improve the thickness distribution to avoid crack generation at bottom region of one-piece PET bottle, process analysis of stretch blow-molding using a finite element method has been carried out. Finite element analysis has been carried out using ABAQUS/Standard. CREEP user subroutine provided in ABAQUS has been used to model PET behavior that is rate sensitive. Among the process parameters, the effect of plunger movement to thickness distribution of bottle has been considered by axisymmetric analysis. A modified process of plunger movement, which yields more uniform thickness distribution, has been proposed. 3D FE analysis has been done to confirm the validity of the proposed process.

• 한국기계가공학회지
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• 제19권4호
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• pp.36-44
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• 2020

This study analyzed the deformation behavior of the high density polyethylene (HDPE) bottle in the blow molding process. We carried out finite element (FE) simulations using ANSYS Polyflow. First, the axisymmetric model was executed by 2D FE-simulation to determine the change of bottle wall thickness during the molding process. Then, the square model of the bottle was executed by 3D FE-simulation to gauge the effects of gas pressure on the change of wall thickness. The experiment results showed that the FE-simulations were able to upgrade the quality of the HDPE bottle in the blow molding process. These results can be used as guidance in adjusting gas pressure, as well as be extended for further study to determine process parameters such as temperatures, forming velocity, parison shape, etc.

• 폴리머
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• 제25권1호
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• pp.63-70
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• 2001

대표적 가교형태 변화에 따른 유사한 stress-strain 특성을 나타내는 조건하에서 공정특성 및 전반적 물성에 미치는 영향을 조사하였다. 천연고무 기본 배합에서 촉진제나 황 공여체(sulfur donor) 증가에 따라 induction time은 길어지나, 가류속도는 빨라졌다. 가교계 변화에 따른 인장강도의 영향은 매우 적은 반면 신장율은 conventional vulcanization (CV)계에서 efficient vulcanization (EV)계로 갈수록 감소하는 경향을 보여 주었다. Blow-out이 발생하는 시간을 가교형태에 따라 비교하여 보면 CV

• 한국산학기술학회논문지
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• 제11권1호
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• pp.1-6
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• 2010

본 연구에서는 성형해석 및 실험적 방법을 통하여 페트 용기의 두께 편차를 최소화하기 위한 프리폼 최적화 설계를 수행하였다. 사출성형과정을 정확하게 묘사하기 위하여 3차원 모델을 이용하여 충진, 보압 및 냉각해석을 통하여 최적의 프리폼 설계변수를 설정하였으며, 이 결과를 이용하여 블로우 성형해석을 수행하였다. 성형해석결과를 평가하기 위한 사출성형 및 블로우 성형실험을 수행하였으며, 실험결과와 해석결과는 정성적으로 일치하는 것을 확인하였다. 이러한 실험결과 데이타를 설계에 반영함으로서 최적의 프리폼 형상을 얻을 수가 있었다.

• Journal of Biosystems Engineering
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• 제40권1호
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• pp.1-9
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• 2015

Purpose: The objective of this study was to understand the operating mechanism of the rock-drill drifter, to explain how to setup an experimental test system and measure the strain of the drifter's rod, and to evaluate the drifter's performance with respect to the impact energy and blow frequency. Methods: The structure of the rock-drill drifter and its operating principle regarding the impact process were analyzed. Static calibration was carried out to calculate the correction factor using a drifter rod as the first step of the experimental test. The impact energy and blow frequency were then calculated based on strain measurements of the drifter's rod. Results: Experimental results showed that the tested drifter elicited a blow frequency of 3330 BPM (Blows Per Minute) and generated impact energy of 170 J/blow. This indicates that the drifter elicits a higher percussion speed and results in a lower impact energy compared to the hydraulic breaker at the same input power. Conclusions: The study proposed methodologies that deal with the experimental setup and the evaluation of the performance of the rock-drill drifter. These methodologies can be extensively used for validating and improving the percussion performance of the drilling equipment.

• Design & Manufacturing
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• 제12권3호
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• pp.5-12
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• 2018

Plastic containers which provides the opportunity to reduce transportation costs are lighter and less brittle than glass containers. As a results, efforts to replace glass with plastic are ongoing. The blow molding method is a typical approach in producing plastic containers. Single-stage injection blow molding (ISBM) is one of the blow molding methods. However, the difficulty in controlling the temperature during the injection molding process is considered its main disadvantage. In this study, ISBM process analysis of relatively thick walled containers such as cosmetic containers is carried out. The initial temperature distribution of the preform is deemed to be the most influential factor in the accuracy of blow molding for the thick vessel. In order to accurately predict this, all heat transfer processes of the preform are considered. The validity of this analytical procedure is verified by comparing the cross-sectional thickness with the actual product. Finally, the validated analytical method is used to evaluate the factors affecting the thickness of the final molded part. The ISBM analysis technique for thick walled vessels developed through this study can be used as an effective predictor for preform design and blow process.

• Archives of Plastic Surgery
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• 제33권5호
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• pp.552-556
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• 2006

Purpose: As the use of computed tomographic scanning spread, the diagnosis of blow-out fractures of the medial orbital wall increased. Conventionally, the surgery of blow-out fractures in medial orbital wall was performed by various approaches with external incision or endoscopic approach. Although the field of orbital surgery has progressed significantly during the last decade, accurate realignment and replacement of component is difficult due to lack of visualization of the fracture site, blind dissection of the orbital wall, and difficulty in insertion of implant. In order to overcome these shortcomings, we explored the use of endoscopic transnasal approach together with subciliary approach. Methods: The entrapped periorbital tissues in the ethmoid sinus were completely reduced endoscopically, and the bone defect of medial orbital wall was reconstructed with $Medpor^{(R)}$ insertion via subciliary approach. This technique was applied to 13 patients who had medial orbital wall fracture. Results: The patients were followed-up for 3 to 24 months with an average of 9 months. The postoperative courses were satisfactory in all cases. Conclusion: The conjunction of endoscopic transnasal and subciliary approach technique seems to produce good results in medial orbital wall fracture.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.920-922
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• 2003

Large plumes of yellow send or yellow dust blow out over the Sea of Japan and the Japanese archipelago from mainland of China. In this study, the methodology to capture the perspective on the large Yellow dust storm by using MODIS data is discussed. As the typical image of yellow send, MODIS data obtained of April 8, 2002 were used in this study.