• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2008년도 춘계학술발표대회 개요집
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• pp.42-42
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• 2008

• 한국방재학회:학술대회논문집
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• 한국방재학회 2007년도 정기총회 및 학술발표대회
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• pp.546-550
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• 2007

High excess pore water pressure may develop when loose saturated sand is subjected to earthquake excitation, resulting in reduction in the shear strength and stiffness, and ultimately can result in liquefaction. It is very important to accurately assess the level of the pore pressure generation for seismic design and to perform effective stress analysis. A simple numerical 모형 is developed for estimating the development of pore water pressure due to seismic loading. The method only uses two parameters and the length of the accumulated shear strain. The accuracy of the proposed 모형 is verified through a series of laboratory test data. Comparisons show that the modified 모형 is an improvement over existing 모형s.

• 한국세라믹학회지
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• 제27권2호
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• pp.169-178
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• 1990

The sintering characteristics of ZrO2 were analyzed in terms of pore microstructure and kinetics of pore elimination. The pore structue of the ZrO2 sample prepared from colloid suspension was characterized by three distinct types of pores ; intradomain, interdomain, and intergglomerate pores. Sintering data at 1600$^{\circ}C$ showed that pores larger than a certain critical size(∼3$\mu\textrm{m}$) were difficult to remove, and this was analyzed in terms of the interagglomerate pore formed from the suspension under the condition of low kinetic stability, that is, the stability ratio smaller than its critical value. A theoretical equation for densification rate was derived and was applied to the densification rate of the ZrO2 polycrystalline body containging both the matrix(the 1st-generation) pores and the interagglomerate (the 2nd-generation) pores under the condition of slow grain growth.

• 한국세라믹학회지
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• 제30권11호
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• pp.881-890
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• 1993

MAS system has narrow sintering temp. range due to the liquid phae sintering and thereby densify rapidly. And especially, its poor mechanical properties limitedthe industrial application. In this study, the improvement of mechanical properties and densification is suggested by the consideration of the toughening mechanisms and isolated pore generation mechanism which is derived by the liquid phase sintering theory in 3Y-TZP added composites. After Pressureless sintering up to 140$0^{\circ}C$ for 5hr, the dihedral angle and contact angle are analyzed by the observation of microstructure. As a result of microstructure analysis, the sintering stage of the specimen sintered for 5hr is analyzed as solid-skeleton stage. And the isolated pore generation mechanisms are considered as (1) The swelling of the liquid phase is predominent due to the facts that dihedral angle is larger than 60$^{\circ}$, contact angle is large and that liquid volume fraction is smaller than 10%. (2) The porous characteristics of the MAS system is also suggested as: the SiO2-rich liquid film is firstly formed at the srface and therefore this reduces the contiguity of the pore, which induces the isolated pore. The strength and fracture toughness increased with the addition of 3Y-TZP and the main fracture toughness improvement mechanisms are analyzed as the crack deflection.

• 멤브레인
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• 제27권5호
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• pp.441-448
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• 2017

본 연구에서는 다공성 폴리에틸렌 지지체를 기반으로 세 가지 가교제를 혼합 도입한 세공충진 이온교환막을 제조하고 역 전기투석에서 멤브레인의 특성이 발전성능에 미치는 영향을 고찰하였다. 실험 결과, 분자 크기가 다른 가교제를 혼합함으로써 이온교환막의 가교도 및 자유체적이 효과적으로 조절됨을 확인하였으며 상관 분석을 통해 멤브레인의 전기화학적 특성 및 이를 적용한 역 전기투석의 발전성능에 복합적인 영향을 미침을 알 수 있었다. 특히 세공충진 양이온 교환막은 최적 가교조건에서 상용막 대비 동등 이상의 발전 성능을 나타내었으며 음이온 교환막 또한 상용막에 근접하는 우수한 성능을 나타내었다.

• 한국지진공학회논문집
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• 제28권1호
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• pp.33-39
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• 2024

Understanding the behavior of soil under cyclic loading conditions is essential for assessing its response to seismic events and potential liquefaction. This study investigates the effect of non-plastic fines content (FC) on excess pore pressure generation in medium-density sand-silt mixtures subjected to strain-controlled cyclic direct simple shear (CDSS) tests. The investigation is conducted by analyzing excess pore pressure (EPP) ratios and the number of cycles to liquefaction (Ncyc-liq) under varying shear strain levels and FC values. The study uses Jumunjin sand and silica silt with FC values ranging from 0% to 40% and shear strain levels of 0.1%, 0.2%, 0.5%, and 1.0%. The findings indicate that the EPP ratio increases rapidly during loading cycles, with higher shear strain levels generating more EPP and requiring fewer cycles to reach liquefaction. At 1.0% and 0.5% shear strain levels, FC has a limited effect on Ncyc-liq. However, at a lower shear strain level of 0.2%, increasing FC from 0 to 10% reduces Ncyc-liq from 42 to 27, and as FC increases further, Ncyc-liq also increases. In summary, this study provides valuable insights into the behavior of soil under cyclic loading conditions. It highlights the significance of shear strain levels and FC values in excess pore pressure generation and liquefaction susceptibility.

• Tribology and Lubricants
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• 제28권1호
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• pp.7-11
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• 2012

In this paper, the results of finite element(FE) analysis of chemical mechanical polishing(CMP) process using 2-dimensional elements were discussed. The objective of this study is to find the generation mechanism of microscratches on a wafer surface during the process. Especially, a FE model with a particle inside pad pore was considered to observe how such a contact situation could contribute to microscratch generation. The results of the finite element simulations revealed that during CMP process the pad-particle mixture could be formed and this would be a major factor leading to microscratch generation.

• 한국수소및신에너지학회논문집
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• 제21권4호
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• pp.328-339
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• 2010

A new gasification model for coal char was developed considering the effects of pore structure and solid reaction product (ash) and compared with conventional models. Among various parameters reflecting microscopic pore structure, initial pore surface per unit volume of char was found to have the largest effect on carbon conversions. Reaction studies showed that the proposed model can predict carbon conversion more accurately over a broader range of reaction degree compared to the conventional models. Therefore the model proposed in this study would be useful for the design of pilot or commercial scale gasifiers.

• 한국해양공학회지
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• 제21권3호
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• pp.26-32
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• 2007

A series of large-scale experiments were carried out in order to examine wave-induced liquefaction in a loosely packed sandbed, its afterward high densification and liquefaction by oscillatory pore pressure. The experiments were conducted in a Large Hydro-Geo Flume that can nearly solve the problems of scale effects of the sandbed, and the 50% sieve diameter of sand was 0.2 mm. The generation of residual pore pressure and its afterward high densification which had observed by Takahashi et al. (1999) in a wave flume experiment using fine sand with the size of 0.08 mm. As a result, the relative density of the sandbed after high densification was increased up to 79% and liquefaction by oscillatory pore pressure was not observed.

• 한국의상디자인학회지
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• 제23권1호
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• pp.37-45
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• 2021

This study observed the release of microplastics according to washing weights and filtering conditions, measured microplastic generation rates, fiber lengths, and fiber diameters. This study attempted to present data for the development of filters that decrease microplastic generation. For test samples, polyester piled knit fabric (cut-pile) was selected, which currently has the highest amount of consumption in the clothing industry, but can easily cause marine pollution because of its low biodegradability. For test equipment, a drum washer was used and microplastics were collected using two filter pore sizes, 5 ㎛ and 20-25 ㎛. Microplastic fibers weights and lengths were measured. The results of the experiment showed the following: 1) The release of microplastics differed according to the fabric weights and washing process; 2) washing fabric weights showed a differences in the collection amount according to the filter pore size (5 ㎛, 20-25 ㎛); 3) observations of differences in the lengths of the microplastics that occur during the washing process by filter pore size were made. Fibers with shorter lengths appeared with filter pore sizes of 5㎛ in comparison to filter pore sizes of 20-25㎛. The results from this study on microplastic generation by fabric during washing, demonstrated the following conclusions that can be used to reduce the release of microplastics. First, the release of microplastics according to fabric weights and washing courses are affected by physical force. Therefore, it is necessary to reduce the amount of physical force due to water flow, increase the fabric weight, or wash the material in low temperatures. Second, in the manufacturing of washing machines, microplastic filtration can be promoted or legislatation supporting microplastic filtration can be introduced.