• Geomechanics and Engineering
• /
• 제3권2호
• /
• pp.131-151
• /
• 2011

The electrical conductivity of a soil-water system is related to its engineering properties. By measuring the soil electrical conductivity, one may obtain quantitative, semi-quantitative, or qualitative information to estimate the in-situ soil behavior for site characterization. This paper presents the results of electrical conductivity measured on compacted kaolin clay samples using a circular two-electrode cell in conjunction with a specially designed compaction apparatus, which has the advantage of reducing errors due to sample handling and increasing measurement accuracy. The experimental results are analyzed to observe the effects of various parameters on soil electrical conductivity, i.e. porosity, unit weight, water content and pore water salinity. The performance of existing analytical models for predicting the electrical conductivity of saturated and unsaturated soils is evaluated by calculating empirical constants in these models. It is found that the Rhoades model gives the best fit for the kaolin clay investigated. Two general relationships between the formation factor and soil porosity are established based on the experimental data reported in the literature and measured from this study for saturated soils, which may provide insight for understanding electrical conduction characteristics of soils over a wide range of porosity.

• 대한인간공학회지
• /
• 제28권4호
• /
• pp.61-69
• /
• 2009

With increasing needs for affective design, it became an essential part in a product development process to look up quantitative ergonomic data that reflects customers' preferences on design factors in various products. This study looked at wide LCD monitors and analyzed customers' affective preferences regarding monitor's bezel frame size and shape. The monitor's bezel frame depth, size and ratio were selected as independent variables among many design parameters. As dependent variables, customer's subjective preferences were measured. A statistical analysis revealed that monitor's bezel frame depth, size and ratio had significant effects on customer's preferences. Also, it was possible to find a different tendency on affective variables and their levels for 19" and 24" wide LCD monitors. In general, experiments revealed that customers reacted more sensitively in 24" wide LCD monitors to all variables. In 19" wide LCD monitors, only the lower frame bezel size had a significant effect, otherwise, lower, upper and side frame bezels appeared to be effective variables in 24" monitors. In order to reflect customer's affective preferences to new design of wide LCD monitors, this study is expected to provide quantitative ergonomic data and guidelines for the design of wide LCD monitor's bezel frame depth and size.

• Earthquakes and Structures
• /
• 제7권3호
• /
• pp.251-269
• /
• 2014

To investigate the seismic performance and to obtain quantitative parameters for the requirement of performance-based bridge seismic design approach, 12 reinforced concrete (RC) hollow rectangular bridge column specimens were tested under constant axial load and cyclic bending. Parametric study is carried out on axial load ratio, aspect ratio, longitudinal reinforcement ratio and transverse reinforcement ratio. The damage states of these column specimens were related to engineering limit states to determine the quantitative criteria of performance-based bridge seismic design. The hysteretic behavior of bridge column specimens was simulated based on the fiber model in OpenSees program and the results of the force-displacement hysteretic curves were well agreed with the experimental results. The damage states of residual cracking, cover spalling, and core crushing could be well related to engineering limit states, such as longitudinal tensile strains of reinforcement or compressive strains of concrete, etc. using cumulative probability curves. The ductility coefficient varying from 3.71 to 8.29, and the equivalent viscous damping ratio varying from 0.19 to 0.31 could meet the requirements of seismic design.

• Nuclear Engineering and Technology
• /
• 제53권7호
• /
• pp.2341-2347
• /
• 2021

Because single-photon emission computed tomography (SPECT) is one of the widely used nuclear medicine imaging systems, it is extremely important to acquire high-quality images for diagnosis. In this study, we designed a super-resolution (SR) technique using dense block-based deep convolutional neural network (CNN) and evaluated the algorithm on real SPECT phantom images. To acquire the phantom images, a real SPECT system using a^99mTc source and two physical phantoms was used. To confirm the image quality, the noise properties and visual quality metric evaluation parameters were calculated. The results demonstrate that our proposed method delivers a more valid SR improvement by using dense block-based deep CNNs as compared to conventional reconstruction techniques. In particular, when the proposed method was used, the quantitative performance was improved from 1.2 to 5.0 times compared to the result of using the conventional iterative reconstruction. Here, we confirmed the effects on the image quality of the resulting SR image, and our proposed technique was shown to be effective for nuclear medicine imaging.

• 한국시뮬레이션학회논문지
• /
• 제28권3호
• /
• pp.83-89
• /
• 2019

본 연구는 회전 비행체(Magnus rotor)를 탑재한 분산탄두의 분산 균일도에 미치는 요인 분석과 성능지표를 도출하기 위해 모탄의 속도 V와 회전속도 ${\omega}$, 비행경로각(flight path angle) ${\gamma}$ 그리고 고도 h의 변화에 따른 해석 결과를 기술했으며, 이때 모탄의 회전속도와 속도의 비를 새로운 변수로 정의했다. 자탄의 분산 해석에는 풍동실험을 통해 획득한 공력계수를 사용한 6 자유도 운동방정식을 이용했으며, 분산도 분석을 위해 회귀분석과 결정계수를 구해 분산도를 평가했다. 해석결과 최적의 회전속도와 낙하속도의 비, 비행경로각(flight path angle)을 구할 수 있었으며, 방출고도는 분산도에 회전속도와 낙하속도의 비, 비행경로각(flight path angle)의 영향에 비해 영향은 크지 않고, 자탄의 분산반경에 영향이 큰 것을 확인했다.

• 생약학회지
• /
• 제54권1호
• /
• pp.38-43
• /
• 2023

A simple and accurate assay was developed for the quantitative analysis of 1-deoxynojirimycin (1-DNJ) derived from the silkworm (Bombyx mori). Normal-phase high-performance liquid chromatography coupled with an evaporative light scattering detector (HPLC-ELSD) and a hydrophilic interaction liquid chromatography column was used. Various parameters were applied to optimize the analysis method. The limits of detection and quantification of 1-DNJ were 2.97 × 10^-3 and 9.00 × 10^-3 mg/mL, respectively. The calibration curve showed good linearity results. The concentration range and the r² value were 0.0625-1.0 mg/mL and 0.9997, respectively. The accuracy test demonstrated a significantly high recovery rate (89.95-103.22%). The relative standard deviation was ≤ 1.00%. Thus, a method for the accurate identification and quantitative analysis of 1-DNJ in silkworms was developed. Moreover, in this procedure, the process of derivatization of 1-DNJ, which was required in previous experiments, could be eliminated. This technique may be actively utilized for the development of pharmaceuticals and health functional foods using 1-DNJ.

• Natural Product Sciences
• /
• 제23권2호
• /
• pp.75-83
• /
• 2017

The optimization and microwave assisted extraction of stem bark of Terminalia arjuna, quantitative estimation of the marker compounds arjunic acid and arjunolic acid using HPTLC and the evaluation of free radical scavenging activity has been performed in this study. The central composite design was used for optimization and the values of parameters for optimized batch of microwave assisted extraction were 1000 W (Power), 3 minutes (Time) and 1/120 (Solid/solvent ratio). The solvent system to carry out the HPTLC was toluene: acetic acid: ethyl acetate (5: 5: 0.5) and quantitative estimation was done using standard equations obtained from the marker compounds. The in-vitro free radical scavenging activity was performed spectrophotometrically using ascorbic acid as standard. The value of estimated percentage yield of arjunic acid and arjunolic acid was 1.42% and 1.52% which upon experimentation was obtained as 1.38% and 1.51% respectively. The DPPH assay of the different batches of microwave assisted extraction and marker compounds taken suggested that the marker compounds arjunic acid and the arjunolic acid were responsible for the free radical scavenging activity as the batch having the maximum percentage yield of the marker compounds showed best free radical scavenging effect as compared to standard ascorbic acid. The $IC_{50}$ value of the optimized batch was found to be 24.72 while that of the standard ascorbic acid was 29.83. Hence, the yield of arjunic acid and arjunolic acid has direct correlation with the free radical scavenging activity of stem bark extract of Terminalia arjuna and have potential to serve as active lead compounds for free radical scavenging activity.

• 한국항공우주학회지
• /
• 제42권3호
• /
• pp.243-253
• /
• 2014

본 논문은 플랜트 파라미터의 불확실성에도 불구하고 강인성을 보장하는 정량적 궤환 이론에 대해 다루고 있다. 정량적 궤환 이론은 플랜트의 파라미터와 외란의 불확실성에 대해 주파수 영역에서 설계 사양의 강인성을 보장한다. 정량적 궤환 이론을 이용하기 위해 선정한 플랜트는 기동성이 뛰어나며 헬리콥터와 같이 수직 이착륙이 가능한 4-회전익 비행체를 이용하였으며, 4개의 블레이드를 구동하는 모터의 파라미터 불확실성을 설정하여 요구사양에 맞는 자세 제어가 가능함을 실험하였다. 또한, 자세 제어에는 4-회전익 비행체의 파라미터 변동 범위와 동작 범위를 고려한 전필터를 사용하였다. 이를 위해 MATLAB에서 정량적 궤환 이론에 의해 제어기를 설계할 수 있는 QFT control toolbox인 QFTCT를 사용하여 각 설계 단계에 대해 소개하고 있다.

• 마이크로전자및패키징학회지
• /
• 제15권2호
• /
• pp.55-61
• /
• 2008

본 논문은 블루투스 모듈의 구조 및 솔더접합부에 대한 신뢰성 평가에 국한된 기존의 방법을 확장하여 정량적인 신뢰성 평가를 수행한 결과를 나타낸다. Field 환경조건에서의 정량적인 신뢰성 평가를 위해, 온도 싸이클링(temperature/thermal cycling)에서의 온도차를 가속스트레스로 선정하여 가속수명시험을 실시하였다. 가속수명시험을 통해 구한 고장시간 데이터들을 이용하여 수명분포 매개변수들을 추정하고 코핀-만슨(Coffin-Manson) 모델을 이용하였다. 가속수명시험을 수행한 결과, 블루투스 모듈의 고장모드는 Open, 고장메커니즘은 크랙(Crack)과 박리(Delamination)였다. Field에서 수거한 고장품들의 고장모드와 고장메커니즘이 가속수명시험을 통해 재현되었다. 또한 본 논문에서 블루투스 모듈이 Field에서 받을 수 있는 온도 싸이클링에서의 다양한 온도차에 대한 정량적인 수명을 예측할 수 있는 방법이 제시되었다. 제안된 방법을 이용하여 온도차 $70^{\circ}C$를 받고 있는 블루투스 모듈의 $B_{10}$ 수명은 약 4년으로 추정되었다.

• Bulletin of the Korean Chemical Society
• /
• 제32권12호
• /
• pp.4397-4402
• /
• 2011

The NF-${\kappa}B$ system of transcription factors plays a crucial role in inflammatory diseases, making it an important drug target. We combined quantitative structure activity relationships for predicting the activity of new compounds and quantitative dynamic models for the NF-${\kappa}B$ network with intracellular concentration models. GFA-MLR QSAR analysis was employed to determine the optimal QSAR equation. To validate the predictability of the $IKK{\beta}$ QSAR model for an external set of inhibitors, a set of ordinary differential equations and mass action kinetics were used for modeling the NF-${\kappa}B$ dynamic system. The reaction parameters were obtained from previously reported research. In the IKKb QSAR model, good cross-validated $q^2$ (0.782) and conventional $r^2$ (0.808) values demonstrated the correlation between the descriptors and each of their activities and reliably predicted the $IKK{\beta}$ activities. Using a developed simulation model of the NF-${\kappa}B$ signaling pathway, we demonstrated differences in $I{\kappa}B$ mRNA expression between normal and different inhibitory states. When the inhibition efficiency increased, inhibitor 1 (PS-1145) led to long-term oscillations. The combined computational modeling and NF-${\kappa}B$ dynamic simulations can be used to understand the inhibition mechanisms and thereby result in the design of mechanism-based inhibitors.