• 터널과지하공간
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• 제30권3호
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• pp.193-213
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• 2020

사용후핵연료 심층처분장 처분공에 설치된 압축 벤토나이트 완충재가 처분공 내벽에 형성된 굴착손상영역 불연속면 내로 침투하는 현상을 보다 더 현실적으로 모사할 수 있는 수학적 모델이 개발되었다. 이 모델에서는 압축 벤토나이트의 침투를 평행 평판 암반 절리을 통한 Bingham 유체의 이동으로 가정한다. 개발된 모델에 의해 벤토나이트의 침투현상을 분석한 결과, 암반 절리를 통해 압축 벤토나이트가 침투하는 최대 깊이는 포화 압축 벤토나이트의 팽윤압과 암반 절리의 폭에 비례하며, 압축 벤토나이트의 항복강도에 반비례하였다. 압축 벤토나이트의 점도는 압축 벤토나이트의 침투 속도를 좌우하나, 최대 침투깊이에는 영향을 미치지 않는다.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.162-169
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• 2003

Excavation by TBM can be characterized by a rock-machine interaction during the cutting process on a small scale, but on a large scale the interaction between the rock mass and TBM becomes very significant. For the planning and evaluation of TBM tunnelling it needs to understand rock fracture mechanism by a cutter or cutters on a small scale, and to estimate penetration rate, advance rate and utilization on a large scale. In this study rock chipping mechanism due to cutter-penetration is analysed by numerical simulation, showing that rock chipping is mainly occurred by tensile failure. Also, through the analysis of factors that affect on TBM procedures in various assessment systems, it is determined that the key elements that should be considered in the planning and evaluation of TBM tunnelling are classified into rock properties, the geological structures and properties of rock mass, and the structural and functional specifications of the machine. The user-friendly assessment tool is developed, so that penetration rate, advance rate and TBM utilization are evaluated from various input data. The tool developed in this study can be applied to a practical TBM tunnelling by understanding TBM tunnelling procedures.

• Clinical and Experimental Reproductive Medicine
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• 제20권1호
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• pp.1-7
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• 1993

The present study was designed to test the validity of the semen analysis(S/A) and the sperm penetration assay(SPA) as a prognostic indicator of male fertility in 123 patients undergoing in vitro fertilization(IVF). We attempted to correlate the traditional semen parameters or the extent of sperm penetration in SPA with the results of human IVF rate or cleavage rate. Poor correlation was found between the results of S/A and human IVF rate(sensitivity, 80.6% ;specificity, 46.7%; positive predictive value, 91.6%;negative predictive value, 25%). Conversely, good correlation was found between the results of SPA and human IVF rate(sensitivity, 100% ; specificity, 80% ;positive predictive value, 97.3% ;negative predictive value, 100%). Our results corroborate the conclusion that SPA can be a valuable tool as a prognostic indicator of male fertilizing ability.

• 한국재료학회지
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• 제18권3호
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• pp.128-136
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• 2008

Evaluation of the solid surface properties by an analysis of the liquid penetration rate into powder beds is very important in applications of powder products. The penetration rate is related the surface property in powder beds. In order to analyze the surface property of powders, the contact angle values of several powders were obtained using the Washbun equation and the Wicking method. The surface free energy value ${\gamma}S$ was divided into a polar component ${\gamma}S^p$ and a dispersion component ${\gamma}S^d$. Inorganic powders such as calcite were used as test samples. The effects of the particle size and the type of experimental liquid on the penetration rate were measured. It was confirmed that the surface free energy of the grinding sample is smaller than that of the classification sample.

• 한국군사과학기술학회지
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• 제20권2호
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• pp.238-245
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• 2017

This paper deals with the scale effects of warhead on concrete penetration. We investigated the scale effects using finite element analysis and Young's penetration equation. As the scale of penetration test decreases, the strain rate effects of target increases, and then strength of concrete target increases. This means the residual velocity and penetration depth of warhead decreases as the test model size decreases. Young's penetration equations are transformed with various penetrator mass and scale cases as a function of scale ratio. Penetration distance and residual velocity are not simply changed by the geometric scaling law.

• Journal of Korean Society for Atmospheric Environment
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• 제23권E1호
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• pp.29-38
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• 2007

A cylindrical tube connection that has a voltage difference and is separated electrically by an insulator was modelled. The penetration efficiencies of charged particles passing through the connector tube were investigated. Typically, as the particle size decreases and the applied voltage difference increases, the penetration efficiency decreases. To assess the effect of the electrode geometry, various lengths of electric insulator and aerosol flow rate with a fixed tube length and tube diameter were used when calculating penetration efficiencies. The comparison of penetration efficiencies for various electrode geometry setups suggests that the penetration efficiency can be described as a function of the product of applied voltage and electrical mobility of charged particles. The diffusion loss from this and previous studies are compared. Further, an explicit form for penetration efficiency is provided as a function of a new non-dimensional parameter, $Es(=Z_pV/U_{avg}W);\;P_{es}=0.2{\cdot}{\exp}(-Es/0.6342)+0.8{\cdot}{\exp}(-Es/4.7914)$.

• Journal of Pharmaceutical Investigation
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• 제23권3호spc1호
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• pp.1-8
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• 1993

A simple and quick method based on the transient diffusion theory for predicting the steady state rate of penetration of a drug after transdermal drug administration was proposed. The amount of drug entering the stratum corneum was determined by 20 strippings with an adhesive tape. From the profile of the amount of drug as a function of the number of strippings, the quantity of drug on the surface of stratum corneum was extrapolated. Based on the amounts of drug entering the stratum corneum during two time intervals $(t_1\;and\;t_2)$ within 1 hour after the application, the diffusion and partition coefficient were determined. Once the diffusion coefficient of the drug in the stratum corneum and the partition coefficient (stratum corneum/vehicle) were determined from the present approach, the steady-state flux of penetration across the stratum corneum was calculated. The steady-state rates of penetration of ascorbic acid and estradiol across hairless mouse skin were evaluated from this approach and compared with those obtained from ill vitro penetration experiment using excised hairless mouse skin. The data confirmed that the proposed method can predict the steady-state rate of penetration of these drugs across the stratum corneum.

• Nuclear Engineering and Technology
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• 제51권4호
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• pp.1060-1068
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• 2019

This work aims to establish a model of a primary water stress corrosion crack growth rate of Alloy 690 material for the head penetration nozzles of Korean pressurized water reactors. The test material had an inhomogeneous microstructure with bands of fine-grains and intragranular carbides in the matrix of coarse-grains, which was similar to the archive materials of the head penetration nozzles. The crack growth rate was measured from the strain-hardened materials as a function of the stress intensity factor in simulated primary water at various temperatures and dissolved hydrogen contents. The effects of strain-hardening, temperature, and dissolved hydrogen on the crack growth rate were analyzed independently, and were then introduced as normalizing factors in the crack growth rate model. The crack growth rate model proposed in this work provides a key element of the tools needed to assess the progress of a stress corrosion crack when detected in thick-wall Alloy 690 components in Korean reactors.

• 대한소아치과학회지
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• 제26권2호
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• pp.416-426
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• 1999

본 연구의 목적은 치면열구전색제 수복시에 상아질 접착제의 primer 도포의 치면열구전색제 열구 침투도 향상 효과를 확인하는 것으로, 발거된 영구 구치상에서 통상적으로 치면열구전색제를 도포한 대조군과 $Scotchbond^{TM}$ Multi-Purpose system과 $All-Bond^{(R)}$ 2 system의 primer 도포 후에 치면열구전색제를 도포한 실험군들의 열구 기저부까지 전색제 침투 성공율을 비교하여 다음과 같은 결론을 얻었다. 1. $Scotchbond^{TM}$ Multi-Purpose system과 $All-Bond^{(R)}$ 2 system의 primer 를 사용한 군의 열구 기저부까지 치면열구전색제 침투 성공율은 primer를 사용하지 않은 대조군보다 높았으나 통계학적으로 유의성 있는 차이는 없었다(p>0.05). 2. 열구 깊이와 폭 및 '깊이/폭' 값은 열구 기저부까지 전색제 침투성공률에 대하여 통계학적으로 유의성 있는 효과를 나타내었다(p<0.05). 3. 열구 기저부까지 전색제 침투 성공률은 열구 깊이가 $25{\mu}m$ 증가할 때마다 약 0.9배로 감소하였고, 열구 입구의 폭이 $25{\mu}m$ 증가할 때마다 약 1.1배로 증가하였으며, 열구의 '깊이/폭' 비율이 1 증가할 때마다 약 0.6배로 감소하였다.

• 터널과지하공간
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• 제17권3호
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• pp.225-233
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• 2007

노르웨이는 계곡이나 피요르드와 같은 굴곡이 심한 지형 때문에 터널이 많이 건설되었으며, 그 가운데 지난 30년 동안 59개의 터널이 전단면 기계굴착으로 완성되었다. 이러한 기계굴착 경험을 통하여 예측기법이 개발되고 발전되었으며 마침내 국립공과대학인 NTNU에서 예측법이 체계화되었다. 본 보고는 TBM 굴착자료가 알려진 14개의 노르웨이 터널과 4개의 국내의 터널에서 순굴착속도와 굴진속도를 분석하여, 이들의 발전경향을 연구한 것이다. 이 기간동안 노르웨이에서는 디스크 커터의 직경을 증대시키고 배열을 최적화하여 순굴착속도와 굴진속도를 두배 정도로 증진시켰다. 국내에서도 1980년부터 1990대까지 15년 동안 IBM의 굴진속도는 노르웨이에 비하여 작은 크기이지만 뚜렷이 증가하는 경향을 보였다. 이러한 작은 속도는 암반의 특성에도 기인하지만 17 인치보다 작은 직경의 디스크 커터를 사용한데 크게 기인된 것으로 판단된다. 향후 국내의 전단면 기계굴착에서 장비와 기술의 개선을 이루고, 특히 17 또는 19 인치의 디스크 커터를 사용한다면 순굴착속도와 굴진속도를 향상시킬 수 있을 것으로 예측된다.