• Fibers and Polymers
• /
• 제1권2호
• /
• pp.103-110
• /
• 2000

Flow analysis of profile extrusion is essential for design and production of a profile extrusion die. Velocity, pressure, and temperature distribution in an extrusion die are predicted and compared with the experimental results. A two dimensional numerical method is proposed for three dimensional analysis of the flow field within the profile extrusion die by applying a modified cross-sectional numerical method. Since the cross-sectional shape of the die is varied gradually, it is assumed that the pressure is constant within a cross-sectional plane that is perpendicular to the flow direction. With this assumption, the velocity component in the cross-sectional direction is neglected. The exact cross-sectional shape at any position is calculated based on the geometry of standard cross-sections. The momentum and energy equations are solved with proper boundary conditions at a cross-section and then the same calculation is carried out for the next cross-section using the current calculated values. An L-shaped profile extrusion die is produced and employed for experimental investigation using a commercially available polypropylene. Numerical prediction for the varying cross-sectional shape provides better results than the previous studies and is in good agreement with the experimental results.

• 의학교육논단
• /
• 제17권3호
• /
• pp.131-139
• /
• 2015

The purpose of this study was to develop a career planning program for medical students and to examine its effectiveness with regard to career choice motivation and career maturity. A total of 89 medical students participated in the study. Forty-four were in the experimental group and 45 were in the control group. The collected data were analyzed with the t-test, analysis of covariance, descriptive statistics, and analysis of frequency by PASW SPSS ver. 18.0 (SPSS Inc.). A career planning program was developed using the ADDIE (analysis, design, development, implementation, and evaluation) model. The contents of self-understanding and career exploration were included in this program. The program was conducted as a seminar with preferred major professors. There was a significant difference in the intrinsic motivation score between the control and experimental groups (p<0.05). The score of the experimental group (M=4.59) was higher than that of the control group (M=4.40). Significant differences in decisiveness (p<0.01) and realistic choice (p<0.05), the sub-factors of the career maturity test, were found between the control and experimental groups. The score of decisiveness of the experimental group (M=2.94) was higher than that of the control group (M=2.79). The score of realistic choice in the experimental group (M=3.17) was lower than that in the control group (M=3.37). Most medical students were satisfied with the career planning program. It is hoped that these results provide useful information for designing career guidance programs for students in medical schools.

• Structural Engineering and Mechanics
• /
• 제47권1호
• /
• pp.45-58
• /
• 2013

In structural reliability analysis, the response surface method is a powerful method to evaluate the probability of failure. However, the location of experimental points used to form a response surface function must be selected in a judicious way. It is necessary for the highly nonlinear limit state functions to consider the design point and the nonlinear trend of the limit state, because both of them influence the probability of failure. In this paper, in order to approximate the actual limit state more accurately, experimental points are selected close to the design point and the actual limit state, and consider the nonlinear trend of the limit state. Linear, quadratic and cubic polynomials without mixed terms are utilized to approximate the actual limit state. The direct Monte Carlo simulation on the approximated limit state is carried out to determine the probability of failure. Four examples are given to demonstrate the efficiency and the accuracy of the proposed method for both numerical and implicit limit states.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2016년도 전력전자학술대회 논문집
• /
• pp.79-80
• /
• 2016

A discrete time domain analysis for the duty-cycle-controlled buck LED driver is performed in this paper. Based on the analysis, the design guidelines are derived. Experimental results are presented to confirm the design.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2017년도 전력전자학술대회
• /
• pp.321-322
• /
• 2017

A discrete time domain analysis for the slope-compensated buck LED driver is performed in this paper. Based on the analysis, the design guidelines are derived. Experimental results are presented to confirm the design.

• 산업식품공학
• /
• 제15권4호
• /
• pp.297-304
• /
• 2011

혼합물실험계획법(mixture experimental design)을 적용하여 라면 밀가루 혼합비를 최적화하였다. 밀가루 혼합비를 최적화하기 위하여 전체 기호도(overall palatability)의 최대화, 반죽 레올로지 특성의 특정 범위 유지를 최적화의 목적으로 설정하였다. 라면은 가장 보편적인 미국산 밀가루 중 강력분인 DNS, 중력분인 HRW, 박력분인 SW를 simplex-lattice 방식에 의해 혼합비를 달리하여 제조하였다. 각 시료는 Rapid Visco Analyser(RVA), 파리노그래프, 익스텐소그래프를 이용하여 반죽의 레올로지 특성치를 측정하였으며, 조리된 라면의 전체 기호도를 관능 검사 하였다. 정준상관분석(canonical correlation analysis)를 통하여 RVA의 최고점도(PV), 파리노그래프의 반죽형성시간(DT), 익스텐소그래프의 R/E 45 min을 주요 반죽 레올로지 특성치로 선발하였다. 최적화 목적으로 전체 기호도의 최대화와 최고점도(PV)(최대화), 반죽형성시간(DT)(최소화) 및 R/E45 min(최대화)를 지정하였다. 그 결과 최적화된 밀가루 혼합비는 DNS 33.3%, HRW 33.3% 및 SW 33.3% 이였으며, 이때 전체 기호도는 5.825, 최고점도(PV)는 587.9 cP, 반죽형성시간(DT)은 3.1 min, R/E 45 min는 2.339 BU/mm로 나타났다.

• Journal of Magnetics
• /
• 제18권1호
• /
• pp.65-73
• /
• 2013

In this paper, design and performance analysis of robust and inexpensive permanent magnet-assisted synchronous reluctance generators (PMa-SynRG) for tactical and commercial generator sets is studied. More specifically, the optimal design approach is investigated for minimizing volume and maximizing performance for the portable generator. In order to find optimized PMa-SynRG, stator winding configurations and rotor structures are analyzed using the lumped parameter model (LPM). After comparisons of stator windings and rotor structure by LPM, the selected stator winding and rotor structure are optimized using a differential evolution strategy (DES). Finally, output performances are verified by finite element analysis (FEA) and experimental tests. This design process is developed for the optimized design of PMa-SynRG to achieve minimum magnet and machine volume as well as maximum efficiency simultaneously.

• Earthquakes and Structures
• /
• 제20권2호
• /
• pp.133-148
• /
• 2021

The paper presents a simplified force-based seismic design procedure for the preliminary design of steel haunch retrofitting for the seismic upgrade of deficient RC frames. The procedure involved constructing a site-specific seismic design spectrum for the site, which is transformed into seismic base shear coefficient demand, using an applicable response modification factor, that defines base shear force for seismic analysis of the structure. Recent experimental campaign; involving shake table testing of ten (10), and quasi-static cyclic testing of two (02), 1:3 reduced scale RC frame models, carried out for the seismic performance assessment of both deficient and retrofitted structures has provided the basis to calculate retrofit-specific response modification factor Rretrofitted. The haunch retrofitting technique enhanced the structural stiffness, strength, and ductility, hence, increased the structural response modification factor, which is mainly dependent on the applied retrofit scheme. An additional retrofit effectiveness factor (ΩR) is proposed for the deficient structure's response modification factor Rdeficient, representing the retrofit effectiveness (ΩR=Rretrofitted /Rdeficient), to calculate components' moment and shear demands for the retrofitted structure. The experimental campaign revealed that regardless of the deficient structures' characteristics, the ΩR factor remains fairly the unchanged, which is encouraging to generalize the design procedure. Haunch configuration is finalized that avoid brittle hinging of beam-column joints and ensure ductile beam yielding. Example case study for the seismic retrofit designs of RC frames are presented, which were validated through equivalent lateral load analysis using elastic model and response history analysis of finite-element based inelastic model, showing reasonable performance of the proposed design procedure. The proposed design has the advantage to provide a seismic zone-specific design solution, and also, to suggest if any additional measure is required to enhance the strength/deformability of beams and columns.

• 응용통계연구
• /
• 제10권1호
• /
• pp.15-27
• /
• 1997

Randomized block design (RBD) with three replication is very frequently adopted in agricultural experiments of the Rural Development Administration of Korea. Even though it works well in field trials of traditional crops, it may not accomodate trial site conditions and/or experimental environment. In this research report, we deal with two such cases. The first case is for a crop experiment in green houses. In house conditions, RBD may not be appropriate since it cannot reflect two directions of the yield gradient. So, a Latin square design is suggested as an alternative. The second case is for local field experiments of the newly-inbred rice. RBD with three replications is used without doubt for decades, even though the site layout is not appropriately shaped for the design. In this case, we suggest the RBD in two blocks with multiple replicates for control varieties as an alternative. To improve the quality of statistical experimental designs in over one-thousand agricultural trials performed annually in the Rural Development Administration, we need to re-train agricultural researchers on the design and analysis of experiments and call for concerns of Korean statisticians.

• 재활간호학회지
• /
• 제17권1호
• /
• pp.48-55
• /
• 2014

Purpose: In this study, we attempted to provide an evidence for the effects of meridian acupressure on relieving and preventing constipation in the institutionalized elderly. Methods: The research design was a non-equivalent control group, non-synchronized design. The subjects consisted of 31 institutionalized elderly (experimental group: 16, control group: 15). The experimental group was given meridian acupressure for 10 minutes daily for 2 weeks. The data was analyzed by the ${\chi}^2$-test, Fisher's exact test, t-test and repeated measures ANOVA. Results: The number of bowel movements per week of the experimental and control group performed meridian acupressure verified by repeated-measures analysis of variance revealed that interaction existed between the meridian acupressure availability and the measurement point (F=98.183, p<.001). Repeated measures analysis of variance to compare the changes in Bristol stool form scale scores of the experimental and control group performed meridian acupressure revealed that interaction existed between the meridian acupressure availability and the measurement point (F=48.896, p<.001). Conclusion: The results of this study show the meridian acupressure is a useful nursing intervention on constipation in the institutionalized elderly.