• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 1998년도 학술발표회
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• pp.15-15
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• 1998

Pores can form and grow in biomembranes because of factors such as thermal fluctuation, transmembrane electrical potential, and cellular environment. We propose a new statistical physics model of the pore growth treated as a non-Markovian stochastic process, with a free energy barrier and memory friction from the membrane matrix treated as a quasi-two-dimensional viscoelastic and dielectric fluid continuum.(omitted)

• 소성∙가공
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• 제10권2호
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• pp.130-136
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• 2001

The mathematical set-up model was developed to reduce the mechanical property deviation in annealed and slightly rolled steel strip. The mechanical peculiarities of skin pass rolling process, such as high friction value and non-circular contact arc, low reduction and non-negligible entry and exit elastic zones as well as central restricted deformation zone are all taken into account. The deformation of work rolls is calculated with the influence function method and arbitrary contact arc shape is permitted. The strip deformation is modeled by slab method and the entry and exit elastic deformation zones are included. The strip restricted deformation zone near the neutral point is also considered. It was revealed that the new model has better accuracy than present regression model by statistical analysis with actual mill rolling data.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.317-317
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• 2000

The mathematical set-up model was developed to reduce the mechanical property deviation in annealed and slightly rolled steel strip. The mechanical peculiarities of temper rolling process, such as high friction value and non-circular contact arc, Low reduction and non-negligible entry and exit elastic zones as well as central restricted deformation zone are all taken into account. The deformation of work rolls is calculated with the influence function method and arbitrary contact arc shape is permitted. The strip deformation is modeled by slab method and the entry and exit elastic deformation zones are included. The restricted deformation Bone near the neutral point is also considered. It was revealed that the new model has better accuracy than present regression model by statistical analysis with actual mill rolling data.

• 터널과지하공간
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• 제14권5호
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• pp.373-380
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• 2004

본 연구에서는 도로터널 환기시설 설계기준에 의한 소요환기량 산정 시 오염물질의 기준배출량을 환경부 고시기준에 대해 산정하여 차종별, 속도별로 산정된 기준배출량을 모델터널에 적용하여 시뮬레이션 한 결과 기존의 배출량 기준 적용에 대해 소요환기량은 약 49%로 감소되었다. 또한 터널 내 유동손실로서 작용하는 변수 중 터널마찰계수와 입구저항계수 및 등가저항면적을 통계적 분석기법을 이용하여 이들 계수 중 터널의 환기량 산정에 가장 민감하게 영향을 미치는 인자가 마찰계수이며 시뮬레이션을 통해 실제 적용 가능한 계수 범위가 0.018에서 0.021의 값으로 보정될 수 있을 것으로 예상된다. 검증사례로서 4개소의 터널에 적용하였을 때, 최대 약 19.2%의 소요환기량 감소가 예상되며 이에 대해 기존의 설계운용 중인 Jet Fan 설치 대수의 산정에 있어 감소될 수 있으며, 약 연간 운용비용의 저감에 적용 가능할 것으로 사료된다.

• 지질공학
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• 제19권2호
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• pp.177-189
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• 2009

이 연구는 토질역학에서 중요하게 취급되는 전단강도를 몇 가지 토질물성만으로 쉽게 산정할 수 있도록 통계적인 방법의 하나인 선형회귀분석법을 이용하여 전단강도산정모델을 개발하였다. 전단강도는 강도정수인 전단저항각(${\phi}$)과 점착력(c)으로 구분되므로 SPSS의 상관분석을 통해 토질시험 결과들 중 이들 강도정수에 유효한 토질인자를 선별한 후 선별된 인자들과의 관계를 선형회귀분석으로 공식화 하였다. 또한, 개발된 모델과 직접전단시험으로 구한 강도정수를 비교분석하여 모델의 적합성을 검증하였다. 여러 토질물성과 강도정수간의 상관관계를 분석한 결과 전단저항각에 가장 크게 영향을 미치는 토질인자는 간극비 및 건조단위중량이고, 점착력에 크게 유의한 토질인자는 간극비, 건조단위중량 및 소성지수인 것으로 나타났다. 한편, 전단강도산정모델에 의해 산정된 강도정수는 직접전단시험에 의해 구한 강도정수와 거의 유사한 결과를 보였다. 따라서 개발된 전단강도산정모델은 연구지역과 같은 토질조건인 경우 토층의 강도정수 산정을 위한 모델로 이용이 가능할 것으로 사료된다.

• Geomechanics and Engineering
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• 제19권2호
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• pp.127-139
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• 2019

Available methods to determine the ultimate bearing capacity of shallow foundations may not be accurate enough owing to the complicated failure mechanism and diversity of the underlying soils. Accordingly, applying new methods of artificial intelligence can improve the prediction of the ultimate bearing capacity. The M5' model tree and the genetic programming are two robust artificial intelligence methods used for prediction purposes. The model tree is able to categorize the data and present linear models while genetic programming can give nonlinear models. In this study, a combination of these methods, called the M5'-GP approach, is employed to predict the ultimate bearing capacity of the shallow foundations, so that the advantages of both methods are exploited, simultaneously. Factors governing the bearing capacity of the shallow foundations, including width of the foundation (B), embedment depth of the foundation (D), length of the foundation (L), effective unit weight of the soil (${\gamma}$) and internal friction angle of the soil (${\varphi}$) are considered for modeling. To develop the new model, experimental data of large and small-scale tests were collected from the literature. Evaluation of the new model by statistical indices reveals its better performance in contrast to both traditional and recent approaches. Moreover, sensitivity analysis of the proposed model indicates the significance of various predictors. Additionally, it is inferred that the new model compares favorably with different models presented by various researchers based on a comprehensive ranking system.

• Geomechanics and Engineering
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• 제21권6호
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• pp.503-511
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• 2020

This study evaluated the side resistance of drilled shafts socketed into rock sections. Commonly used analysis methods for side resistance of piles in rocks are examined by utilizing a large number of load test data. The analysis of the unit side resistance of pile foundations embedded into rock sections is based on an empirical coefficient (α) and the uniaxial compressive strength (q_u) or its root (${\sqrt{q_u}}$). The Davisson criterion was used to interpret the resistance capacity from the load test results to acquire the computed relationships. The α-${\sqrt{q_u}}$ relationship is proven to be reliable in the prediction of friction resistance. This study further analyzed the relationship by including the effect of rock quality designation (RQD) on the results. Analysis results showed that the analysis model of α-${\sqrt{q_u}}$-RQD provided better prediction and reliability considering the RQD classification. Based on these analyses, the side resistance of drilled shafts socked into rocks is provided with statistical data to support the analysis.

• 소음진동
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• 제9권4호
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• pp.643-651
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• 1999

A brief description of the current technology (contact-start-stop) employed in most of today's hard disk drive is presented. The dynamics and head/disk interactions during a start/stop process are very complicated and no one has been able to accurately model the interactions. Thus, the head/disk interface that meets the start/stop durability and stiction requirements are always developed statistically. In arriving at a solution. many sets of statistical tests are run by varying several parameters. such as, the carbon overcoat thickness. lubricant thickness. disk surface roughness, etc. Consequently, the cost associated III developing an interface could be significant since the outcome is difficult to predict. An alternative method known as Load/Unload technology alters the problem set. such that. the start/stop performance can be designed in a predictable manner. Although this techno¬logy offers superior performance and significantly reduces statistical testing time, it also has some potential problems. However. contrary to the CSS technology. most of the problems can be solved by design and not by trial and error. One critical problem is that of head/disk contacts during the loading and unloading processes. These contact can cause disk and slider damage because the contacts are likely to occur at high disk speeds resulting in large friction forces. Use of glass substrate disks also may present problems if not managed correctly. Due to the low thermal conductivity of glass substrates. any head/disk contacts may result in erasure due to frictional heating of the head/disk interface. In spite of these and other potential problems. the advantage with L/UL system is that these events can be understood. analyzed. and solved in a deterministic manner.

• Geomechanics and Engineering
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• 제37권3호
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• pp.197-211
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• 2024

This research studies the effect of geotechnical factors on EPB-TBM performance parameters. The modeling was performed using simple and multivariate linear regression methods, artificial neural networks (ANNs), and Sugeno fuzzy logic (SFL) algorithm. In ANN, 80% of the data were randomly allocated to training and 20% to network testing. Meanwhile, in the SFL algorithm, 75% of the data were used for training and 25% for testing. The coefficient of determination (R²) obtained between the observed and estimated values in this model for the thrust force and cutterhead torque was 0.19 and 0.52, respectively. The results showed that the SFL outperformed the other models in predicting the target parameters. In this method, the R² obtained between observed and predicted values for thrust force and cutterhead torque is 0.73 and 0.63, respectively. The sensitivity analysis results show that the internal friction angle (φ) and standard penetration number (SPT) have the greatest impact on thrust force. Also, earth pressure and overburden thickness have the highest effect on cutterhead torque.

• Advances in nano research
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• 제16권4호
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• pp.341-352
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• 2024

This study investigates the heat and mass transfer characteristics of a MoS₂ nanoparticle suspension in ethylene glycol over a porous stretching sheet. MoS₂ nanoparticles are known for their exceptional thermal and chemical stability which makes it convenient for enhancing the energy and mass transport properties of base fluids. Ethylene glycol, a common coolant in various industrial applications is utilized as the suspending medium due to its superior heat transfer properties. The effects of variable thermal conductivity, variable mass diffusivity, thermal radiation and thermophoresis which are crucial parameters in affecting the transport phenomena of nanofluids are taken into consideration. The governing partial differential equations representing the conservation of momentum, energy, and concentration are reduced to a set of nonlinear ordinary differential equations using appropriate similarity transformations. R software and MATLAB-bvp5c are used to compute the solutions. The impact of key parameters, including the nanoparticle volume fraction, magnetic field, Prandtl number, and thermophoresis parameter on the flow, heat and mass transfer rates is systematically examined. The study reveals that the presence of MoS₂ nanoparticles curbs the friction between the fluid and the solid boundary. Moreover, the variable thermal conductivity controls the rate of heat transfer and variable mass diffusivity regulates the rate of mass transfer. The numerical and statistical results computed are mutually justified via tables. The results obtained from this investigation provide valuable insights into the design and optimization of systems involving nanofluid-based heat and mass transfer processes, such as solar collectors, chemical reactors, and heat exchangers. Furthermore, the findings contribute to a deeper understanding of stretching sheet systems, such as in manufacturing processes involving continuous casting or polymer film production. The incorporation of MoS₂-C₂H₆O₂ nanofluids can potentially optimize temperature distribution and fluid dynamics.