• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.686-689
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• 2003

Many technologies are applied to the measurement of elastohydrodynamic lubrication (EHL) film thickness. In particular, optical in-situ interferometric method has many advantages in making the actual contact behaviors realized with the experimental apparatus. Careful selection of incident lights greatly enhances the fringe resolution up to nanometer scale by using image processing technology. In this work, it is found that dichromatic incident light can provide much finer resolution of EHL film thickness than monochromatic incident light, because it has much more variables of color components to be discriminated among the wavelengths of colors according the variations of EHL film thickness. Some simulated interferometric images are shown how the film thickness is resolutionized in nanometer scale

• Geomechanics and Engineering
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• v.32 no.1
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• pp.21-34
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• 2023

In order to analyze the effect of the cyclic lateral loading on the response of a pile-soil system, a full-scale single steel pile was subjected to one-way cyclic loading. The test pile was driven into a bi-layered soil consisting of a normally consolidated saturated clay overlying a silty sandy layer, the site being submerged by water up to one meter above the mudline in order to reproduce the conditions of an offshore pile foundation. The aim of this paper is to present the main results of interpretation of the cyclic lateral tests in terms of pile deflections, bending moment, and cyclic P-Y curves. From these latter an absolute secant reaction modulus E_AS,N was derived and a simple calculation model of the test single pile is proposed based on this modulus. Two applications of the proposed model are carried out, one with a 2D finite element modelling, and the second with a load transfer curves-based method.

• Educational Technology International
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• v.9 no.2
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• pp.1-15
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• 2008

One of the challenges that online learners face is feeling of isolation and diminishing desire of maintaining active participation during e-learning. Social presence, that is considered to be a vital factor in e-learning, is recently started to receive a support from the field. Although research indicated a significant role of social presence in both learning process and learning outcome, there is no widely accepted measurement scale of social presence. This study, therefore, developed a new scale to measure social presence based on the existing theories and validated it against 723 participants. Nineteen self-report items with three dimensions, co-presence, influence, and cohesiveness, were identified and validated using Exploratory Factor Analysis (EFA) in a preliminary and a follow-up study.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.2
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• pp.620-636
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• 2015

Survivability is a necessary property of network system in disturbed environment. Recovery ability is a key actor of survivability. This paper concludes network survivability into a novel composite metric, i.e. Network Recovery Degree (NRD). In order to measure this metric in quantity, a concept of Source-Destination Pair (SD Pair), is created to abstract end-to-end activity based on end nodes in network, and the quality of SD Pair is also used to describe network performance, such as connectivity, quality of service, link degree, and so on. After that, a Survivability Test method in large scale Network based on SD pairs, called STNSD, is provided. How to select SD Pairs effectively in large scale network is also provided. We set up simulation environment to validate the test method in a severe destroy scenario and evaluate the method scalability in different large scale network scenarios. Experiment and analysis shows that the metric NRD correctly reflects the effort of different survivability strategy, and the proposed test method STNSD has good scalability and can be used to test and evaluate quantitative survivability in large scale network.

• Journal of Digital Convergence
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• v.20 no.1
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• pp.71-86
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• 2022

The purpose of this study is to develop and validate a scale to measure the ethical awareness of users who accept artificial intelligence technology or service. To this end, the constructs and properties of AI ethics were identified through literature analysis on AI ethics. Reliability and validity were assessed through a preliminary survey(N=273), after conducting an open-type survey to men and women(N=133) in 10s to 70s nationwide, extracting the first questions, and reviewing them by experts. The results of an online survey conducted on men and women(N=500) were refined by confirmatory factor analysis. Finally, an AI technology ethics scale was developed. The AI technology ethics awareness scale was developed with 16 questions in total of 4 factors (transparency, safety, fairness, accountability) so that general awareness of ethics related to AI technology can be measured by detailed factors. In addition, through follow-up research, it will be possible to reveal the relationship with measurement variables in various fields by using the ethical awareness scale of artificial intelligence technology.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.164.1-164
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• 2003

In this study, medium-chain fatty acid (MCFA) metabolized in the liver for quick energy and CLA exhibited biological activity were used for synthesis of structured lipids (SLs). SLs were synthesized by acidolysis of soybean oil, capric acid (C10:0) and CLA with Chirazyme L-2 lipase as biocatalysts. The effect of enzyme load (2, 4, 6, 8, 10% w/w substrates) was investigated. Production of SL (scale-up) was performed with a 1:2:2 molar ratio (oi1/C10:0/CLA) for 24 h at 55$^{\circ}C$ in a stirred batch reactor (420 rpm). The reaction was catalyzed by Chirazyme L-2 lipase (24.48g, 4％ w/w substrates). The scale-up result showed that capric acid and total CLA were incorporated 4.9%, 4.1% (mole%), respectively, in soybean oil. Then, physio-chemical property and flavor characteristic of produced SL-soybean oil were analyzed. Therefore, SL-soybean oil containing C10:0 and CLA was successfully synthesized and may be beneficial in desirable food and nutritional applications.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.6
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• pp.640-647
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• 2006

It is difficult to treat wastewater involved in heavy metal in electroplating industry. Recently, many industries adopt the clean technology to prevent production of pollutant in the process or reuse after the appropriate pollutant treatment. In this study, we estimate the ability of recovery of nickel and the efficiency using lab-scale ion exchange and electrodialysis process with electroplating industry wastewater. In the ion exchange experiments with 5 types of resin, the result showed that S 1467(gel-type strong acidic cation exchange resin) has the highest exchange capacity. And it showed that the 4 N HCl has the highest in regeneration efficiency and maximum concentration in the regeneration experiments with various kinds md concentration of the regenerant. During the electrodialysis experiments, we varied the current density, the concentration of electrode rinse solution, the flow rate of concentrate and electrode rinse solution in order to find the optimum operating condition. As a result, we obtained $250A/m^2$ of current density, 2 N $H_2SO_4$ of concentration of electrode rinse solution, 30 mL/min of flow rate of concentrate and electrode rinse solution as the best operating conditions. We performed the scale-up experiments on the basis of ion exchange and electrodialysis experiments. And we obtained the experimental result that exchange capacity of S 1467 was 1.88 eq/L resin, and regeneration efficiency was 93.7% in the ion exchange scale-up experiment, we also got the result that concentration and dilution efficiency increased, and current efficiency kept constant in the scale-up experiments.

• Journal of Mechanical Science and Technology
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• v.19 no.3
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• pp.913-923
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• 2005

The dynamic mixed model (DMM) combined with a box filter of Zang et. al. (1993) has been generalized for passive scalar transport and applied to large eddy simulation of turbulent channel flows with Prandtl number up to 10. Results from a priori test showed that DMM is capable of predicting both subgrid-scale (SGS) scalar flux and dissipation rather accurately for the Prandtl numbers considered. This would suggest that the favorable feature of DMM, originally developed for the velocity field, works equally well for scalar transport problem. The validity of the DMM has also been tested a posteriori. The results of the large eddy simulation showed that DMM is superior to the dynamic Smagorinsky model in the prediction of scalar field and the model performance of DMM depends to a lesser degree on the ratio of test to grid filter widths, unlike in the a priori test.

• Journal of Pharmaceutical Investigation
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• v.13 no.3
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• pp.115-125
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• 1983

제제설계란 제형의 설계 및 그에 따른 처방설정(formulation)을 의미하며 경험적인 제제방법 및 그 기술측면에서의 제제화는 주악 및 첨가물의 종류와 배합비율의 설정등 비교적 단순한 내용을 의미하지만 의약품은 실제적으로 인체에 적용되므로 치료설계상의 연구와 생물약제학적 검토에 의한 유효정과 안전성을 발휘할 수 있도록 설계가 되어야 한다. 또한 약물의 효력은 체내 특정부위에 특정농도의 약물분포가 필요하고, 일정시간 지속되는 것이 요구되므로 약용량도 중요하지만 약물투여 후의 흡수, 체내이행, 대사, 배설등의 상태를 파악하고 이에 미치는 부형제의 영향도 검토하여야 한다. 제제물리학적 측면에서 품질보증을 위하여 preformulation단계에서 주약의 물성검토, 첨가제의 사용량, interaction 및 혼합순서 등과 처방설정 단계에서 제제화에 사용되는 기계장치의 특성 및 능력, 제제화 후의 포장용기 및 포장상태에서의 안정성 등도 면밀히 검토하여야한다. 제제설계란 단순한 dosage form의 design만이 아니고 유효성이 높고, 부작용이 적은 제제를 합리적으로 만드는 기술과 정보의 종합관리로 scale up과정에서 원료, 기계장치, 제조방법, 작업자 등에 의한 품질변동 요인을 극소화하고, 공정의 초기단계에서 즉시 조정될 수 있는 종합관리 system이 필요하다.

• Journal of the Optical Society of Korea
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• v.19 no.4
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• pp.415-420
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• 2015

A novel method to measure the scale factor for the all-optical atomic spin inertial measurement device (ASIMD) is demonstrated in this paper. The method can realize the calibration of the scale factor by a self-consistent method with small errors in the quiescent state. At first, the matured IMU (inertial measurement unit) device was fixed on an optical platform together with the ASIMD, and it has been used to calibrate the scale factor for the ASIMD. The results show that there were some errors causing the inaccuracy of the experiment. By the comparative analysis of theory and experiment, the ASIMD was unable to keep pace with the IMU. Considering the characteristics of the ASIMD, the mismatch between the driven frequency of the optical platform and the bandwidth of the ASIMD was the major reason. An all-optical atomic spin magnetometer was set up at first. The sensitivity of the magnetometer is ultra-high, and it can be used to detect the magnetization of spin-polarized noble gas. The gyromagnetic ratio of the noble gas is a physical constant, and it has already been measured accurately. So a novel calibration method for scale factor based on the gyromagnetic ratio has been presented. The relevant theoretical analysis and experiments have been implemented. The results showed that the scale factor of the device was $7.272V/^{\circ}/s$ by multi-group experiments with the maximum error value 0.49%.