• International Journal of Fluid Machinery and Systems
• /
• 제10권3호
• /
• pp.240-253
• /
• 2017

Latin hypercube sampling is widely used design-of-experiment technique to select design points for simulation which are then used to construct a surrogate model. The exploration/exploitation properties of surrogate models depend on the size and distribution of design points in the chosen design space. The present study aimed at evaluating the performance characteristics of various surrogate models depending on the Latin hypercube sampling (LHS) procedure (sample size and spatial distribution) for a diverse set of optimization problems. The analysis was carried out for two types of problems: (1) thermal-fluid design problems (optimizations of convergent-divergent micromixer coupled with pulsatile flow and boot-shaped ribs), and (2) analytical test functions (six-hump camel back, Branin-Hoo, Hartman 3, and Hartman 6 functions). The three surrogate models, namely, response surface approximation, Kriging, and radial basis neural networks were tested. The important findings are illustrated using Box-plots. The surrogate models were analyzed in terms of global exploration (accuracy over the domain space) and local exploitation (ease of finding the global optimum point). Radial basis neural networks showed the best overall performance in global exploration characteristics as well as tendency to find the approximate optimal solution for the majority of tested problems. To build a surrogate model, it is recommended to use an initial sample size equal to 15 times the number of design variables. The study will provide useful guidelines on the effect of initial sample size and distribution on surrogate construction and subsequent optimization using LHS sampling plan.

• 응용통계연구
• /
• 제16권2호
• /
• pp.455-467
• /
• 2003

소표본 분할표 자료에서 적합도 검정통계량들의 카이제곱 근사 적용 가능에 대하여 많은 연구가 진행되었다. 소표본에서 세 가지 검정 통계량(피어슨 카이제곱 Χ$^2$, 일반화 가능도비 G$^2$, 그리고 역발산 Ι(2/3) 검정통계량)에 관하여 비교한 Rudas(1986)의 연구를 확장하여, 최근에 제안된 차이측도(BWHD(1/9), BWCS(1/3), NED(4/3) 검정통계량)를 포함시켜 비교 분석하였다. 독립모형의 이차원 분할표, 조건부 독립모형과 한 변수 독립 모형을 따르는 삼차원 분할표에 대한 모의실험을 통하여 생성된 90과 95 백분위수와 이에 대응하는 95% 신뢰구간을 살펴보고 실제 백분위수와 비교하였다. 그 결과 Χ$^2$, Ι(2/3), 그리고 BWHD(1/9) 검정통계량이 유사한 결과를 나타내었고 이 통계량들이 기존에 제안된 검정통계량들보다 적은 표본크기에서도 카이제곱 근사방법에 적용 가능함을 발견하였다.

• 품질경영학회지
• /
• 제23권4호
• /
• pp.28-41
• /
• 1995

We consider the problem of identifying multiple outliers in linear model. The available regression diagnostic methods often do not succeed in detecting multiple outliers because of the masking and swamping effect. Recently, among the various robust estimator of reducing the effect of outliers, LMS(Least Meadian Square) estimator has been to be a suitable method proposed to expose outliers and leverage points. However, as you know it, the data analysis method with LMS estimator is to be taken the median of the squared residuals in the sample which is extracted the sample space. Then this model causes the trouble, for the number of the chosen sample is nCp, i.e. as the size of sample space n is increasing, the number is increasing fastly. And the covariance matrix may be the singular matrix, so that matrix is approching collinearity. Thus we propose a procedure ELMS for the resampling in LMS method and study the size of the effective elementary set in this algorithm.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2000년도 춘계학술대회논문집
• /
• pp.1528-1532
• /
• 2000

The conventional optics and near field optics are compared numerically in the view points of the spot size and propagation characteristics. The decaying characteristics of near field light require the optics to access the object within several tens of nanometers. Therefore the gap control is one of the main issues in the near field optics area. In this paper the gap control is done by using the shear force of the NF(Near Field) probe and the characteristics are examined. The probe is modeled as a 2'nd order mass-spring-damper system driven by a harmonic force. The primary cause of the decrease in vibration amplitude is due to the damping force - shear force - between the surface and the probe. Using the model, damping constant and resonance frequency of the probe is calculated as a function of probe-sample distance. Detecting the amplitude and phase shift of the NF probe attached to the high Q-factor piezoelectric tuning fork, we can control the position of the NF probe about 0 to 50nm above the sample. The feedback signal to regulate the probe-sample distance can be used independently for surface topography imaging. 3-D view of the shear force image of a testing sample with the period of $1{\mu}m$ will be shown.

• 여성건강간호학회지
• /
• 제6권3호
• /
• pp.383-397
• /
• 2000

This study of purpose was to define the relationship between the stress and climacteric symptoms of middle-aged women in order to provide basic data for the development of women's health care program as nursing intervention. The research tools used were a Soon-Young Park's stress questionnaire (4 points scale) and a self diagnostic MENSI scale (3 points scale) developed by a research team of Ill-Yang Pharmacy Co. This research was conducted in Korea in Muan-Gun. Chonnam province, from 22th November to 20th December 1999. The research used a survey design. Seven hundred eleven healthy middle-aged women, aged 40 to 64, and were a convenience sample by stratified ratio using the matching fixed residential and aging blocks. The data were analyzed by GLM. Pearson correlation coefficient and Scheffe test using SAS/ PC+. The results were summarized as follows : 1. The percentage of psychological stress with the following items was: fatigue and enervation, 70.0%; nervous, 61.8%; weakness, 58.5%; The percentage of physical stress with the following items were ; fatigue of eye. 82.3%; backache, 78.0%; headache, 73.8%. 2. The level of psychological stress was 40% of below average level (0-5 points), 31.7 of average level (6-12points), 20.8% of precaution level (13-19 points), and 7.5% of warning level (over 20points). The level of physical stress were 20.1% of below average level (0-5 points), 34.8 of average level (6-12 points), 29.4 of precaution level (13-19 points), and 15.7% of warning level (over 20 points). There were higher physical stress level than psychological stress level of the subjects. 3. The percentage of climacteric symptoms with the following items were : numbness, 75.3%; forgetfulness, 71.0%; pain of joints, 71.0%. The level of climacteric symptoms were 61.8% of mild level 1(10-15 points), 33.0% of moderate level (16-30 points), 5.2% of severe level (over 31 points). 4. There were high positive correlations significantly between the climacteric symptoms and the psychological stress (r=.564. P<0.000), and between the climacteric symptoms and the physical stress of the subjects(r=.678, P<0.000). 5. There were significant differences in the climacteric symptoms of the subjects among below average level, average level, precaution level, and warning level of the psychological stress (F=74.108. P<0.000. Scheffe test). 6. There were significant differences in the climacteric symptoms of the subjects among below average level, average level and precaution level, and warning level of the physical stress ((F=128.181, P<0.000, Scheffe test). In summary, climacteric symptoms complained by middle-aged women are high positive correlated to the level of the stress. Also climacteric symptoms were affected by stress.

• 대한치과교정학회지
• /
• 제23권4호
• /
• pp.565-606
• /
• 1993

The purpose of this study was to evaluate the change of before and after treatment of anterior openbite malocclusions treated by Multiloop Edgewise Archwire technique. The openbite sample consisted of 4 male and 12 female adults, treated with nonextraction or third molar extraction. The normal sample consisted of 58 subjects, which have pleasing facial profile and normal occlusion and no experience of orthodontic or prosthodontic treatment. The 58 subjects of normal sample were subdivided by cephalemetric vertical relationship of face. The 40 subjects, cephalometric vertical relationship of face was in normal range, classified as Normal Sample group 1. The 18 subjects, increased cephalometric vertical relationship of face, classified as Normal Sample group 2. The computerized cephalometric analysis was accomplished with 50 reference points for 22 skeletal measurements, 46 dentoalveolar measurements, 8 soft tissue measurements. Statistical analysis of the data was carried out with paired t-test, Student's t-test, and DUNCAN test using SAS(PC version), The results were as follows : 1. There were no statistically significant differences in skeletal measurement between before and after treatment. The major changes were in dentoalveolar region. 2. After treatment, the long axis of maxillary and mandibular posterior teeth were distally tipped-back, and uprighted to bisected occlusal plane. The interincisal angle was increased. 3. There were no statistically significant increase in the upper posterior dental height and statistically significant decrease in the lower posterior dental height. The upper anterior dental height was increased, but there was no statistically significant increase in the absolute upper anterior dental hight. The lower anterior dental height was increased. 4. After treatment, the maxillary occlusal plane to palatal plane angle and the mandibular occlusal plane to mandibular plane angle were statistically significant increased. Then, there were no statistically significant difference between after treatment group and normal sample group 2. 5. After treatment, the percentage of upper lip length to upper anterior dental height was decreased. Then, There were no statistically significant difference between after treatment group and normal sample group 2.

• 한국식생활문화학회지
• /
• 제34권1호
• /
• pp.53-60
• /
• 2019

This study investigated the sensory characteristics and antioxidative activity of the reduced salt dried bulgogi bibimbap containing AF-343, a dandelion-derived compound extract. A sample with a 30% reduced salt had a sodium amount of 659.01 mg, which was significantly lower than that of the sample before the reduction (p<0.05). The textural hardness of the SW (Standard sample with the AF-343), showed the lowest value of $1.03N/cm^2$, indicating that the AF-343-containing sample could have a slightly softer texture than the non-containing sample. In the analytical sensory test, the AF-343-containing samples showed a synergistic effect on the aroma and flavor of bulgogi, with values of 5.7 and 8.4, respectively, which were significantly higher than that of the non-containing sample group (4.3 and 4.4, respectively). The hardness by the sensory test was slightly hard with values of 7.2-8.1 in all samples, indicating that textural improvement was needed. In the acceptance test, all the samples scored with slightly lower values of 4-5 points, highlighting the need for future studies to improve the sensory characteristics of dried bibimbap. The flavonoid contents of AF-343-containing SW and RW sample groups were 68.21 and 64.31 mg GAE/100 g, respectively, which were significantly higher than those of the samples without AF-343 (49.06 and 44.82 mg GAE/100 g, respectively) (p<0.05). The ABTS and DPPH radical scavenging activities were similar to those of the flavonoid contents. As a result, in the production of AF-343-containing reduced-salt dried bulgogi bibimbap, more study on the textural improvement will be needed to achieve better palatability.

• 대한원격탐사학회지
• /
• 제30권6호
• /
• pp.787-795
• /
• 2014

본 논문에서는 정합된 특징점 가운데 과대 오차를 포함한 정합점을 제거한 후에 삼각망 기반 지역 변환(Triangulation-based Local Transformation, TLT)을 이용한 영상 등록 방법을 제안한다. 기하 평균 기반의 코너 검출기를 통해 검출된 코너점에 대해 Pearson's correlation coefficient를 이용한 코너 정합을 수행하고 임계값 이상의 유사도를 가지는 코너 가운데 좌우 일관성 검사(Left-Right Consistency, LRC)를 통과한 코너를 1차 정합쌍으로 선정한다. 1차 정합쌍 가운데 RANSAC 기반 글로벌 변환(RANSAC-based Global Transformation, RGT) 오차가 이상치 임계값보다 작은 정합쌍을 최종 정합쌍으로 결정한다. 최종 정합쌍 코너를 이용해서 기준 영상과 관측 영상에서 Delaunay Triangulated Irregular Networks(TINs)을 각각 구성한 후에 서로 대응되는 각 삼각형마다 어파인 변환을 수행하고 각 삼각형 내부의 모든 화소들을 기준 영상 좌표로 변환한다. 제안한 알고리즘을 KOMPSAT-2 영상에 적용하여 RANSAC 기반 글로벌 변환보다 우수한 영상 등록 성능을 보임을 확인하였다.

• 품질경영학회지
• /
• 제48권2호
• /
• pp.269-282
• /
• 2020

Purpose: The practical design for experiments with mixtures of q components is consisted in the four types of design points, vertex, center of edge, axial, and center points in a (q-1)-dimensional simplex space. We propose a sequential method for the successful construction of the design space in Quality by Design (QbD) by allowing the different number of replicates at the four types of design points in the practical design when the quadratic canonical polynomial model is assumed. Methods: To compare the mixture designs efficiency, fraction of design space (FDS) plot is used. We search for the practical mixture designs whose the minimal half-width of the tolerance interval per a standard deviation, which is denoted as d₂, is less than 4.5 at 0.8 fraction of the design space. They are found by adding the different number of replicates at the four types of the design points in the practical design. Results: The practical efficient mixture designs for the number of components between three and five are listed. The sequential method to establish a design space is illustrated with the two examples based on the simulated data. Conclusion: The designs with the center of edge points replications are more efficient than those with the vertex points replication. We propose the sample size of at least 23 for three components, 28 for four components, and 33 for the five components based on the list of efficient mixture designs.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제24권5호
• /
• pp.11-16
• /
• 2019

In this study, a reliable number of soil samples for TPH fractionation was investigated in order to perform risk assessment. TPH was fractionated into volatile petroleum hydrocarbons (VPH) with three subgroups and extractable petroleum hydrocarbons (EPH) with four subgroups. At the study site, concentrations of each fraction were determined at 18 sampling points, and the 95% upper confidence limit (UCL) value was used as an exposure concentration of each fraction. And then, 5 sampling points were randomly selected out of the 18 points, and an exposure concentration was calculated. This process was repeated 30 times, and the results were compared statistically. Exposure concentrations of EPH obtained from 18 points were 99.9, 339.1, 27.3, and 85.9 mg/kg for aliphatic $C_9-C_{18}$, $C_{19}-C_{36}$, $C_{37}-C_{40}$, and aromatic $C_{11}-C_{22}$, respectively. The corresponding exposure concentrations obtained from 5 points were 139.8, 462.8, 35.1 and 119.4 mg/kg, which were significantly higher than those from 18 points results (p <0.05). Our results suggest that limited number of samples for TPH fractionation may bias estimation of exposure concentration of TPH fractions. Also, it is recommended that more than 30 samples need to be analyzed for TPH fractionation in performing risk assessment.