• Tribology and Lubricants
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• 제25권6호
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• pp.414-420
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• 2009

In this study, using the general expressions predicting the pressure under a blade and the volume of coating fluid passing through the blade edge, it is predicted the change of the coating wet film thickness related with various parameters determining the characteristics of this blade coating process. Using the results of this research, it can be found the optimized coating wet film thickness taking into account the parameters related with various coating process on various metal surfaces will be able to be predicted.

• 한국전자파학회논문지
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• 제19권8호
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• pp.933-939
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• 2008

본 논문에서는 고속 디지털 회로에서 발생하는 SSN(Simultaneous Switching Noise)을 억제하기 위한 자성 재료가 적용된 복합형 EBG(Electromagnetic Bandgap) 구조의 전원면을 제안하였다. 제안된 EBG 구조는 정사각형 패치와 나선형 선로로 구성된 단위 셀이 주기적으로 연결되어 있으며, 자성 재료는 EBG 구조의 단위 셀 위에 국부적으로 적용되었다. 자성 재료의 투자율 실수 성분은 EBG 단위 셀 사이의 유효 인덕턴스를 중가시켜 밴드갭을 낮은 주파수로 이동시키고, 자성 손실 특성을 갖는 허수 성분은 단위 셀 사이에서 야기되는 기생 LC 공진의 피크값을 낮춘다. 그 결과 제안된 구조는 기존 EBG 구조에 비해 낮은 차단 주파수 특성을 가지며, -30 dB 저지 대역을 기준으로 175 MHz에서 7.7 GHz까지 넓은 억제 대역폭을 나타냈다. 제안된 구조는 전원 무결성 개선 및 EBG 전원면 소형화에 크게 기여할 것으로 기대된다.

• 한국지반신소재학회논문집
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• 제2권1호
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• pp.47-55
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• 2003

14가지 니들펀치 부직포 지오텍스타일의 섬유구성인자인 두께, 기공도, 섬유장 및 직경 등이 수평투수성에 미치는 영향을 평가하였으며, 두께변화, 수평투수도, 압축 하중 하에서의 수평투수성을 구성방정식에 의해 분석, 평가하였다. 그리고 섬유 패킹 밀도가 다른 라미나(laminar) 지오텍스타일 복합재료를 제조하여 라미나 구조가 수직투수성에 미치는 영향을 평가하였다. 수평투수도는 부직포 지오텍스타일의 두께가 증가할수록 커졌으며, 기공도와 섬유직경이 커질수록 수평투수계수는 증가하였다. 수직응력이 증가할수록 기공도의 영향은 감소하였으며, 섬유장이 길수록 수평투수계수는 약간 크게 나타났다. 구성섬유의 직경이 클수록 수평 투수계수는 커지며, 직경의 비슷할수록 유사한 투수계수를 나타내었다. 라미나 지오텍스타일의 수직 투수성은 내부 경계면에서의 손실 수두에 영향을 받으며, 경계면에서 투수로의 연결형상은 bell mouth형이거나 부드러운 유입관 형태로 평가 되었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.248-251
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• 2005

To investigate the degeneration process in the intervertebral disc, a three dimensional (3D) poroelastic finite-element (FE) model was developed. Disc was modeled as two different regions, such as annulus modeled with fiber reinforced 20 node poroelastic ground matrix and nucleus having large porosity. Excess Von Mises stress in the disc element assumed to be a possible source of degeneration under compressive loading condition. Recursive calculation was continued until the desired convergence was attained by changing the permeability and porosity of those elements, which could be predicted from the previous iteration. The degenerated disc model showed that relatively small compressive stresses were generated in the nucleus elements compared to normal disc. Its distribution along the sagittal plane was matched well with a previously reported experimental result. Contrasts to this result, pore pressures in the nucleus were higher than those in the normal disc. Total stress indicated similar values for two different models. This new approach using poroelastic modeling could provide the explanation of the interaction between fluid and solid matrix in the disc during the degeneration process.

• 한국농공학회지
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• 제38권4호
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• pp.125-136
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• 1996

In order to investigate the characteristics of gravity drainage for geotextile, small-scale model tests for the geotextile chimney drain of earth dam which is a typical type of gravity drainage were carried out using 15 kinds of nonwoven and composite geotextiles. According to the results of this study, the drainage discharge of geotexgile drain generally increases with exponential function as hydraulic head increases and the increasing rate is greater in the coarser soil of dam material. It has a trend to increase when the construction slope of geotextile drain is steeper and the number of layers of geotextile is more. The relationship between the transmissivity of geotextile and the drainage discharge has positive correlation and the rate of increase is greater in the coarser soil. The geotextile products must be carefully selected in consideration of transmissivity of geotextile when the soil to be drained is coarser and the seepage flow is relatively high. Most of staple fiber nonwoven geotextile used in this study are found to be appropriate for drainage purpose. Among them, the composite geotextile the type of which geotextile is evaluated to be the most excellent material. But the geotextile of low permeability such as filament thermal bonded and filament spunbonded nowovens closely examined their transmissivity especially to be used for drainage function.

• Toxicological Research
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• 제35권4호
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• pp.295-301
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• 2019

In this review, we describe the absorption rates (Caco-2 cell permeability) and hepatic/plasma pharmacokinetics of 53 diverse chemicals estimated by modeling virtual oral administration in rats. To ensure that a broad range of chemical structures is present among the selected substances, the properties described by 196 chemical descriptors in a chemoinformatics tool were calculated for 50,000 randomly selected molecules in the original chemical space. To allow visualization, the resulting chemical space was projected onto a two-dimensional plane using generative topographic mapping. The calculated absorbance rates of the chemicals based on cell permeability studies were found to be inversely correlated to the no-observed-effect levels for hepatoxicity after oral administration, as obtained from the Hazard Evaluation Support System Integrated Platform in Japan (r = -0.88, p < 0.01, n = 27). The maximum plasma concentrations and the areas under the concentration-time curves (AUC) of a varied selection of chemicals were estimated using two different methods: simple one-compartment models (i.e., high-throughput toxicokinetic models) and simplified physiologically based pharmacokinetic (PBPK) modeling consisting of chemical receptor (gut), metabolizing (liver), and central (main) compartments. The results obtained from the two methods were consistent. Although the maximum concentrations and AUC values of the 53 chemicals roughly correlated in the liver and plasma, inconsistencies were apparent between empirically measured concentrations and the PBPK-modeled levels. The lowest-observed-effect levels and the virtual hepatic AUC values obtained using PBPK models were inversely correlated (r = -0.78, p < 0.05, n = 7). The present simplified PBPK models could estimate the relationships between hepatic/plasma concentrations and oral doses of general chemicals using both forward and reverse dosimetry. These methods are therefore valuable for estimating hepatotoxicity.

• 한국전자통신학회논문지
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• 제9권8호
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• pp.921-926
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• 2014

본 논문에서는 CSLR(Complementary Single Loop Resonator)을 이용한 인셋 급전 마이크로스트립 안테나의 특성에 대해 연구하였다. SLR(Single Loop Resonator) 단일 구조에서 시뮬레이션 셋업 과정을 통해 산란계수로부터 실효투자율을 계산하였으며, 실효투자율이 음의 값을 갖는 주파수에서 SLR 구조의 치수를 선택하였다. 그리고 인셋 급전된 마이크로스트립 안테나의 접지면에 SLR 구조의 쌍대 구조인 CSLR을 $3{\times}3$으로 배열하여 최적 안테나를 설계하였다. 설계한 안테나의 반사손실과 복사패턴을 구하였으며, 공진주파수 2.82 GHz에서 기존의 인셋 급전 안테나와 크기를 비교하면 면적 대비 약 56.8%가 감소하는 결과를 얻었다. 사용된 툴은 3차원 FEM 툴인 Ansoft사의 HFSS를 사용하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.119-126
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• 2002

Fractures, especially faults have most significant influence on the difficulties encountered in various engineering and mining works, because they can give rise to inevitable reductions in shear strength as well as large increase in permeability. Thus, before underground access is possible, it is desirable to estimate the distribution and geometry of fractures in advance, if reliable structural data from e.g. Televiewer tool are available. To this end, fracture face mapping is just the evaluation method used to form a fracture image determined by intersecting of each fracture plane with a selected plane section of a rock mass, assuming that all fractures be planar with fixed-aperture. Although many fractures are geometrically complex and others are altered chemically, according to the abundant experiments in recent years, it would seem that the technique could be applied to benefit the design of numerous engineering works such as slope stability, tunnel excavations, dam foundation and diverse environmental works. This paper presents at first an evaluation algorithm for fracture face mapping and then concludes with various representative examples of applications.

• 한국정보전자통신기술학회논문지
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• 제5권1호
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• pp.26-32
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• 2012

본 논문에서는 4개의 ELC 공진기 구조를 사용하여 메타 흡수체 구조의 단위 셀을 설계하였다. 제안된 구조의 단위 셀의 크기는 $9mm{\times}9mm{\times}2mm$ 이다. 메타 흡수체의 대역폭 확장을 위하여 흡수체 단위 셀은 서로 다른 크기를 갖는 2 쌍의 ECL가 사용되었다. 제안된 흡수체는 전계가 ELC 갭에 수평하게 여기되고 자계가 단위 셀 면에 수직으로 여기 될 경우에 음의 유전율과 음의 투자율 특성을 나타낸다. 제안된 단위 셀은 8.53 GHz, 9.08 GHz에서 공진을 하며 각 주파수에서 90%이상의 흡수율을 갖는다.

• Geomechanics and Engineering
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• 제30권2호
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• pp.153-167
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• 2022

This study proposes a method to analyze the distribution of coal porosity disturbances after the excavation of ultra-large-diameter water jet boreholes using a coal wetting and softening model. The high-pressure jet is regarded as a short-term high-pressure water injection process. The water injection range is the coal softening range. The time when the reference point of the borehole wall is shocked by the high-pressure water column is equivalent to the time of high-pressure water injection of the coal wall. The influence of roadway excavation with support and borehole diameter on the ultra-large-diameter jet drilling excavation is also studied. The coal core around the borehole is used to measure the gas permeability for determining the porosity disturbance distribution of the coal in the sampling plane to verify the correctness of the simulation results. Results show that the excavation borehole is beneficial to the expansion of the roadway excavation disturbance, and the expansion distance of the roadway excavation disturbance has a quadratic relationship with the borehole diameter. Wetting and softening of the coal around the borehole wall will promote the uniform distribution of the overall porosity disturbance and reduce the amplitude of disturbance fluctuations.