• Structural Engineering and Mechanics
• /
• 제82권3호
• /
• pp.271-282
• /
• 2022

The active learning surrogate model based on adaptive sampling strategy is increasingly popular in reliability analysis. However, most of the existing sampling strategies adopt the trial and error method to determine the size of the Monte Carlo (MC) candidate sample pool which satisfies the requirement of variation coefficient of failure probability. It will lead to a reduction in the calculation efficiency of reliability analysis. To avoid this defect, a new method for determining the optimal size of the MC candidate sample pool is proposed, and a new structural reliability analysis method combining polynomial chaos-based Kriging model (PC-Kriging) with adaptive sampling region is also proposed (PCK-ASR). Firstly, based on the lower limit of the confidence interval, a new method for estimating the optimal size of the MC candidate sample pool is proposed. Secondly, based on the upper limit of the confidence interval, an adaptive sampling region strategy similar to the radial centralized sampling method is developed. Then, the k-means++ clustering technique and the learning function LIF are used to complete the adaptive design of experiments (DoE). Finally, the effectiveness and accuracy of the PCK-ASR method are verified by three numerical examples and one practical engineering example.

• 청정기술
• /
• 제16권4호
• /
• pp.254-257
• /
• 2010

중국 Liaoning에서 산출된 천연 수활석(brucite)을 원료로 $Mg(OH)_2$ slurry를 제조하고, 그 탈황 성능을 조사하였다. 수활석의 입도분포의 차이 및 수열처리에 의한 활성화 효과를 검토하였다. 80 mesh 이하의 수활석 시료에 비해 입자의 크기가 작고 입도분포가 좁은 1000 mesh 이하의 사료가 de-$SO_2$ 효율이 더 높은 것을 확인할 수 있었다. 한편, 80 mesh 이하의 수활석 시료를 비교적 낮은 온도인 363 K에서 3 h 동안 수열 처리하여 매우 높은 de-$SO_2$ 성능 개선 효과를 얻을 수 있었다.

• Journal of the Korean Data and Information Science Society
• /
• 제9권1호
• /
• pp.57-62
• /
• 1998

The minimum number of samples for the measurement of plant characteristics of major crops were calculated from the data obtained from the field experiments on rice, barley, wheat, soybean and sweet potato conducted by Kyungpuk Rural Development Administration.

• 한국재료학회지
• /
• 제4권4호
• /
• pp.439-444
• /
• 1994

분극처리된 PZT세라믹스에 외부응력을 인가하였을때 인가되는 응력의 방향에 따른 열화기구의 차이를 조사하였다. 그 결과 분극축과 수직으로 응력을 인가할때의 열화현상은 공간전하분극의 확산으로, 분극축과 평행하게 응력을 인가할때는 분역재배열현상으로 설명하였다. 소결체의 입자 크기가 커지면 열화폭이 커짐을 알 수 있었는데 이것은 입자크기에 따른 내부응력의 차이로 해석하였다.

• 응용통계연구
• /
• 제8권1호
• /
• pp.27-38
• /
• 1995

본 논문에서는 사회적으로나 개인적으로 매우 민감한 조사에서 모집단이 양적속성을 갖는 여러 개의 층으로 구성되어 있을 때, 층의 크기를 모르는 경우 층화표본을 위하여 이중추출법을 이용하는 층화이중추출법에 의한 양적속성의 무관질문모형을 제안하였다. 그리고, 층화이중추출에 있어서 각 층의 표본배분에 관해 비례배분, 최적배분으로 나누어 각 층의 크기를 알고 있는 경우에 층화추출법에 의한 양적속성의 무관 질문모형과 그 효율성을 비교하였다.

• 한국안전학회지
• /
• 제16권3호
• /
• pp.83-88
• /
• 2001

This study was preformed by measuring the minimum ignition temperature of MBS according to the change of sample vessel size and the minimum ignition temperature of MBS dust cloud The minimum ignition temperature of MBS product decreased as the vessel size was large, and it was obtained in the range from $120.5^{\circ}C$ to $94.5^{\circ}C$ and the apparent activation energy was obtained with 32.94Kcal/mol. The minimum ignition temperature of MBS dust cloud was measured by using Godbert-Greenwald furnace and it was obtained at $407^{\circ}C$ with the sample of 0.4g in the air and the ignition of dust cloud was not occurred below 13% oxygen concentration.

• 한국표면공학회지
• /
• 제28권3호
• /
• pp.164-173
• /
• 1995

Based on the potential-theory model for secondary current distribution, we could predict the thickness distributions of electroplating on patterned substrates with the different size of the auxiliary electrode. The substrates contain lithographic patterns at each sample geometry. Each sample geometry had different current distribution at the same condition except the size of the auxiliary electrodes. The size effect of the auxiliary electrode on thickness distribution of electrodeposition on patterned electrode was investigated in a series of experiments. Copper was galvanostatically deposited from an acid-sulfate solution in a reciprocating paddle cell. The thickness distributions of the workpiece scale measured by profilometry across the specimen were in good agreement with the current distribution predicted by boundary element method.

• Journal of Industrial and Engineering Chemistry
• /
• 제67권
• /
• pp.123-131
• /
• 2018

Using mixed nonionic surfactants Span/Tween, we investigated the effects of HLB value on the O/W emulsion stability and rheological behaviors. In this study, MS-01 (Span 60 & Tween 60) and MS-02 (Span 80 & Tween 80) was used as mixed nonionic surfactants. We considered required HLB value 10.85 and selected corresponding HLB value range 8-13. The droplet size distributions, droplet morphology, rheological properties, zeta-potential and creaming index of the emulsion samples were obtained to understand the mechanism and interaction of droplets in O/W emulsion. The results indicated that optimal HLB number for O/W emulsions was 10.8 and 10.7, while using MS-01 surfactant and MS-02 surfactant respectively. MS-01 (HLB = 10.8) sample and MS-02 (HLB = 10.7) sample showed smallest droplet size and highest zeta-potential value. Rheological properties are measured to understand rheological behaviors of emulsion samples. All emulsion samples showed no phase separation until 30 days storage time at $25^{\circ}C$.

• 대한간호학회지
• /
• 제27권4호
• /
• pp.857-870
• /
• 1997

The purposes of this study were to describe 12 years of patient-related oncology nursing research in Korea, identifying various nursing interventions, and assesing the effectiveness of the interventions, through analysis and synthesis of the accumulated research papers. One hundred and seventy-nine studies were selected for this study and these were mostly descriptive in design (69.2%). Of the 179 studies, 25 met the criteria for meta-analytic treatment. Twenty-five experimental studies were found in theses and dissertations (68%), 92% used convenience sample, and the median sample size was 40. Subjects were predominantly in treatment and rehabilitation (76%). Most studies(68%) were not derived from a theory base, with only 8% reporting use of a nursing theory. Results of the meta-analysis are as follows. The effect size of the nursing intervention type was found to be significantly effective. The standardized mean difference ranged from a high positive of 2.55 to a low negative of -0.22. Direct personal nursing intervention method was more effective than indirect group method. Two nursing intervention methods were more effective than one. The greatest effect size was thyxical intervention. The greatest mean effect size was scalp hypothermia technique. Teaching was a frequent intervention after 1990, although a wide range of treatments were studied. Effect size of intervention for symptom management was largest in relieving pain. Effective intervention method for relieving anxiety was exercise.

• 제어로봇시스템학회논문지
• /
• 제13권3호
• /
• pp.218-223
• /
• 2007

The dissipation of high-power ultrasonic energy at the faces of the defect causes an increase in temperature. It is resulted from localized selective heating in the vicinity of cracks because of the friction effect. In this paper the measurement of size and direction of crack using UET(Ultrasound Excitation Thermography) is described. The ultrasonic pulse energy is injected into the sample in one side. The hot spot, which is a small area around the crack tip and heated up highly, is observed. The hot spot, which is estimated as the starting point of the crack, is seen in the nearest position from the ultrasonic excitation point. Another ultrasonic pulse energy is injected into the sample in the opposite side. The hot spot, the ending point of the crack, is seen in the closest distance from the injection point also. From the calculation of the coordinates of both the first hot spot and the second hot spot observed, the size and slope of the crack is estimated. In the experiment of STS fatigue crack specimen(thickness 14mm), the size and the direction of the crack was measured.