• Journal of Advanced Marine Engineering and Technology
• /
• v.34 no.4
• /
• pp.554-559
• /
• 2010

Lifeboat davit is composed of main frame, main arm, upper arm and support bar. In this paper, design parameters that affect the bending stiffness were set as plate thickness, width and hight of upper arm. To analyze the influence of parameter factors, FEM and Taguchi Method were used. This paper will help substantially in many industries.

• Journal of the KSME
• /
• v.30 no.4
• /
• pp.331-340
• /
• 1990

본 글에서는 2상유동의 주요 인자들에 대한 측정기법을 소개하였다. 이를 위하여 가장 중요한 기본인자인 유동양식 판별법, 건도 및 질량유량 측정법, 압력강화 측정법과 기공률 측정법을 다 루었다. 이 외에도 2상유동의 실험인자는 다양하나 본 글에서는 지면관계로 열전달 계수, 계면 파구조, entrainment rate, 계면 및 벽면전단응력과 액적 및 기포의 크기 등 부차적인 유동변수 의 측정법을 다루지 못한 것을 아쉽게 생각하며 다음에 소개할 기회를 기대한다.

• The Korean Journal of Applied Statistics
• /
• v.33 no.4
• /
• pp.365-377
• /
• 2020

We discuss latent factor regression when constructing a common structure inherent among explanatory variables to solve multicollinearity and use them as regressors to construct a linear model of a response variable. Bayesian estimation with LASSO prior of a large penalty parameter to construct a significant factor loading matrix of intrinsic interests among infinite latent structures. The estimated factor loading matrix with estimated other parameters can be inversely transformed into linear parameters of each explanatory variable and used as prediction models for new observations. We apply the proposed method to Product Service Management data of HBAT and observe that the proposed method constructs the same factors of general common factor analysis for the fixed number of factors. The calculated MSE of predicted values of Bayesian latent factor regression model is also smaller than the common factor regression model.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.43 no.4
• /
• pp.592-603
• /
• 2014

We developed various recipes of turmeric powder (Curcuma longa L.) added to milk bread and assessed the individual effects of seven ingredients [milk ($X_1$), turmeric powder ($X_2$), bread improver ($X_3$), fresh yeast ($X_4$), butter ($X_5$), sugar ($X_6$), and salt ($X_7$)] as well as the 2-way interaction effects of the ingredients on the sensory characteristics of breads using fractional factorial design method. The center and end points of each component were determined via literature review and multiple test baking. Seven trained sensory test panels evaluated the outside appearance (OA), inside appearance (IA), and flavor & texture (FT) of 38 breads using 46 items of sensory evaluation. Findings are as follows: for the OA, $X_1$ (P<0.05) and $X_4$ (P<0.0001) exhibited significant individual effects, whereas $X_1*X_7$, $X_2*X_5$, $X_3*X_6$, and $X_4*X_6$ indicated significant interaction effects (P<0.05). For the IA, $X_1$ (P<0.0001), $X_4$ (P<0.0001), $X_6$ (P<0.05), $X_2*X_4$ (P<0.05), and $X_3*X_6$ (P<0.01) showed individual and interaction effects, respectively. For the FT, $X_1$ and $X_2$ showed the most significant individual effect (P<0.0001), followed by $X_4$, $X_5$ and $X_6$ (P<0.05) in descending order. $X_4*X_7$ indicated the only significant interaction effect. We computed the magnitudes of the 2-way interaction effects of the ingredients with a distinct emphasis. Model equations predicting the levels of the ingredient effects on the breads were also provided via regression analyses. In summation, $X_4$ appeared to be the most significant component affecting the sensory characteristics based on its individual and 2-way interaction effects. Further, $X_6$, $X_1$, $X_2$, and $X_5$ indicated both individual and interaction effects. $X_3$ and X7 showed only interaction effects. The center point effect appeared to be unequivocal for whole sensory characteristics. Findings of the present study may provide insights into the selection of ingredients to derive an optimal model for turmeric powder-added bread using the response surface method hereafter.

• Journal of Preventive Medicine and Public Health
• /
• v.29 no.2 s.53
• /
• pp.255-264
• /
• 1996

To study reliability and validity of PWI, this newly developed self-administered questionnaire which measures stress, was given to medical students. All respondent(133) were followed 4 weeks later and 92 were retested. Cronbach's $\alpha$ coefficient of data was 0.93. Test-retest reliability measured by Pearson's correlation coefficient was 0.72(P<0.01). Exploratory factor analysis(EFA) performed by principal axis factor method without iteration and by varimax rotation explored 13 principal components(eigenvalues > 1). After exploring 4 factor structure according to previous study results, factor 1 showed good agreement but other factors did not. Confirmatory factor analysis(CFA) showed poor fit of 4 factor model to data. In the further study, it may be considered to model that has unidimensional factor structure.

• Korean Chemical Engineering Research
• /
• v.54 no.1
• /
• pp.44-51
• /
• 2016

The powder core, conventionally fabricated from iron particles coated with insulator, showed large eddy current loss under high frequency, because of small specific resistance. To overcome the eddy current loss, the increase in the specific resistance of powder cores was needed. In this study, copper oxide coating onto electrically conductive iron particles was performed using a planetary ball mill to increase the specific resistance. Coating factors were optimized by the Response surface methodology. The independent variables were the CuO mass fraction, mill revolution number, coating time, ball size, ball mass and sample mass. The response variable was the specific resistance. The optimization of six factors by the fractional factorial design indicated that CuO mass fraction, mill revolution number, and coating time were the key factors. The levels of these three factors were selected by the three-factors full factorial design and steepest ascent method. The steepest ascent method was used to approach the optimum range for maximum specific resistance. The Box-Behnken design was finally used to analyze the response surfaces of the screened factors for further optimization. The results of the Box-Behnken design showed that the CuO mass fraction and mill revolution number were the main factors affecting the efficiency of coating process. As the CuO mass fraction increased, the specific resistance increased. In contrast, the specific resistance increased with decreasing mill revolution number. The process optimization results revealed a high agreement between the experimental and the predicted data ($Adj-R^2=0.944$). The optimized CuO mass fraction, mill revolution number, and coating time were 0.4, 200 rpm, and 15 min, respectively. The measured value of the specific resistance of the coated pellet under the optimized conditions of the maximum specific resistance was $530k{\Omega}{\cdot}cm$.

• Investigative Magnetic Resonance Imaging
• /
• v.13 no.2
• /
• pp.161-170
• /
• 2009

Purpose : A parallel imaging method provides us to improve temporal resolution to obtain three-dimensional (3D) MR images. The objective of this study was to optimize three 3D MRI techniques by adjusting 2D SESNE factors of the parallel imaging method in phantom and human brain. Materials and Methods : With a 3 Tesla MRI system and an 8-channel phase-array sensitivity-encoding (SENSE) coil, three 3D MRI techniques of 3D T1-weighted imaging (3D T1WI), 3D T2-weighted imaging (3D T2WI) and 3D fluid attenuated inversion recovery (3D FLAIR) imaging were optimized with adjusting SESNE factors in a water phantom and three human brains. The 2D SENSE factor was applied on the phase-encoding and the slice-encoding directions. Signal-to-noise ratio(SNR), percent signal reduction rate(%R), and contrast-to-noise ratio(CNR) were calculated by using signal intensities obtained in specific regions-of-interest (ROI). Results : In the phantom study, SENSE factor = 3 was provided in 0.2% reduction of signals against without using SENSE with imaging within 5 minutes for 3D T1WI. SENSE factor = 2 was provided in 0.98% signal reduction against without using SENSE with imaging within 5 minutes for 3D T2WI. SENSE factor = 4 was provided in 0.2% signal reduction against without using SENSE with imaging around 6 minutes for 3D FLAIR. In the human brain study, SNR and CNR were higher with SENSE factors = 3 than 4 for all three imaging techniques. Conclusion : This study was performed to optimize 2D SENSE factors in the three 3D MRI techniques that can be scanned in clinical time limitations with minimizing SNR reductions. Without compromising SNR and CNR, the optimum 2D SENSE factors were 3 and 4, yielding the scan time of about 5 to 6 minutes. Further studies are necessary to optimize 3D MRI techniques in other areas in human body.

• Explosives and Blasting
• /
• v.31 no.2
• /
• pp.1-5
• /
• 2013

Parameters of Swedish bench blast design was analyzed by robust design method. Orthogonal array which is adopted in this study was $L_9(3^4)$ and the parameters were hole diameter, explosive type, hole inclination and rock factor of 3 levels. Result of analysis showed that maximum and minimum burden are most affected by hole diameter, followed by explosive type, rock type and inclination of hole. Parameters affecting specific charge are in the order of rock type, explosive type and to specific drilling are hole diameter and explosive type. Cost analysis showed that robust design is capable of parameter optimization.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.23 no.6
• /
• pp.423-438
• /
• 2021

The blade of motor grader is used for scattering and leveling the aggregates on the foundation of road construction site. The paper performed a design improvement research of the blade part to enhance the working efficiency of motor graders. The scattering works of aggregates by blade driving were simulated by DEM (discrete element method) of a dynamic code. The four design parameters were selected and a specific leveling scenario for the simulation was determined. The nine blade models were numerically experimented, and the sensitivity of each factors was analyzed. Next, the design factors that influence a blade performance have been selected by ANOVA, and these key design factors were applied to the progressive quadratic response surface method (PQRSM). The optimum set of design factors of the blade was finally proposed.

• The Science & Technology
• /
• v.4 no.3 s.15
• /
• pp.35-39
• /
• 1971

1.서론 2.생체실험과 관여인자 3.종족차와 대사경로 4.약효평가 5.실험방법의 개발 6.결론