• 품질경영학회지
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• 제34권3호
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• pp.62-65
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• 2006

We can use the ridge regression as a means for stabilizing the coefficient estimators in the fitted model when performing experiments in highly constrained regions causes collinearity problems in mixture experiments. But there is no theory available on which to base statistical inference of ridge estimators. The bootstrap could be used to seek the confidence intervals of ridge estimators.

• Communications for Statistical Applications and Methods
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• 제7권3호
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• pp.759-766
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• 2000

In order to design fractional factorial experiments which include some debarred combinations, we should select defining contrasts so that those combinations are to be excluded. Choi(1999) presented a method of selectign defining contrasts to construct orthogonal 3-level fractional factorial experiments which exclude some debarred combinations. In this paper, we extend Choi's method to general p-level fractional factorial experiments to select defining contrasts which cold exclude some debarred combinations.

• 대한화학회지
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• 제55권3호
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• pp.529-540
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• 2011

이 연구는 9학년 과학교과서 물질변화에서의 규칙성 단원에 제시되어 있는 실험의 분석과 small-scale chemistry (SSC)를 적용한 실험을 개발하고자 하는 것이다. 연구를 위하여 9학년 9종 과학교과서의 물질변화에서의 규칙성 단원에 제시되어 있는 앙금생성, 물의 전기분해, 과산화수소수의 분해 실험들을 분석하고, 13명의 과학교사들에게 과학교과서의 실험들을 수행하게 하여 문제점과 개선해야할 사항들을 추출하였다. 개선해야할 사항들을 바탕으로 SSC를 적용하여 개발한 실험들을 19명의 예비교사들에게 과학교과서의 실험과 함께 수행하게 한 후 SSC를 적용한 실험의 장점과 단점을 조사하였다. 연구 결과, 요오드화납 앙금생성 실험과 Hoffman식 물의 전기분해 실험, 그리고 이산화망간을 촉매로 사용하는 과산화수소수의 분해 실험이 9학년 과학교과서에 가장 많이 제시되어 있었다. 과학교과서의 실험들에서 개선해야할 사항들로는 시약의 소모량, 실험시간, 실험장치 규모 등이었다. SSC를 적용하여 개발한 실험들의 장점은 적은 양의 시약 사용으로 폐액 처리의 용이성과 실험의 안전성을 높여주며, 실험시간의 단축과 재현성이 있는 실험결과들을 얻을 수 있는 것 등이었다. 반면에 단점은 적은 양의 시약 사용으로 실험관찰에서 다소간의 어려움과 성취감의 감소, 작은 규모의 실험 기구 사용의 미숙함 등이었다. 그러나 SSC를 적용하여 개발한 실험들을 9학년 과학실험으로 활용한다면, 적은 양의 시약을 사용하여 간편하게 재현성이 있는 실험을 이론수업과 병행하여 실시할 수 있어, 학생들이 물질변화에서의 규칙성에 대한 과학적인 개념을 형성하는데 도움을 줄 것으로 기대된다.

• 대기
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• 제17권4호
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• pp.435-453
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• 2007

KEOP (Korea Enhanced Observing Period)-2004 intensive summer observation was carried out from 20 June to 5 July 2004 over the Southwestern part of the Korean peninsula. In this study, the effects of KEOP-2004 intensive observation data on the simulation of precipitation system are investigated using KLAPS (Korea Local Analysis and Prediction System) and PSU/NCAR MM5. Three precipitation cases during the intensive observation are selected for detailed analysis. In addition to the control experiments using the traditional data for its initial and boundary conditions, two sensitivity experiments using KEOP data with and without Jindo radar are performed. Although it is hard to find a clear and consistent improvement in the verification score (threat score), it is found that the KEOP data play a role in improving the position and intensity of the simulated precipitation system. The experiments started at 00 and 12 UTC show more positive effect than those of 06 and 18 UTC. The effect of Jindo radar is dependent on the case. It plays a significant role in the heavy rain cases related to a mesoscale low over Changma front and the landing of a Typhoon. KEOP data produce more strong difference in the 06/18 UTC experiments than in 00/12 UTC, but give more positive effects in 00/12 UTC experiments. One of the possible explanations for this is that : KEOP data could properly correct the atmosphere around them when there are certain amounts of data, while gives excessive effect to the atmospheric field when there are few data. CRA analysis supports this reasoning. According to the CRA (Contiguous Rain Area) analysis, KEOP data in 00/12 UTC experiments improve only the surrounding area, resulting in essentially same precipitation system so the effects remain only in each convective cell rather than the system itself. On the other hand, KEOP data modify the precipitation system itself in 06/18 UTC experiments. Therefore the effects become amplified with time integration.

• 한국가금학회:학술대회논문집
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• 한국가금학회 2000년도 제17차 정기총회 및 학술발표
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• pp.36-53
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• 2000

Five experiments were conducted to investigate the effects of antioxidants(Santoquin and Oxiban) using fresh or oxidized fat on the performance of broiler chicks. Day-old broiler chicks (except for Experiment 5 in which 6-d-ol birds were given experimental diets for 10 d) were fed diets containing fresh or oxidized fat (animal-vegetable fat blend in Experiments 1, 4, and 5 and corn oil in Experiments 2 and 3) with or without graded concentrations of Santoquin (0,250, 500 ppm in Experiments 1 and 2 and 0, in Experiment 4 and 400 ppm with 0.1% lipase in Experiment 5) of 2wk. In all experiments, birds fed fresh fat gained more weight, had better feed/gain, together with higher AME$_{n}$ and apparent fat digestibility (Experiments 1 and 2) than birds fed oxidized fat(P<0.05). There was no interaction among fat sources and antioxidants on the performance of chicks in any experiment. In Experiment 3, Santoquin more than 200 ppm resulted in a reduction in weight gain and feed intake(P<0.05). The livers of chicks fed oxidized fat in Experiments 2 and 5 had higher malondialdehyde (MDA) values (P<0.05) Chicks fed oxidized fat with 250 ppm Santoquin in Experiment 2 had lower liver MDA values, although this situation did not occur in Experiments 1, 4, and 5. These results indicate that antioxidant supplements can alleviate most deleterious effects of feeding oxidized fat and that supplementation of Santoquin more than 200 ppm has a negative effect on the performance of broiler chicks.s.

• Korean Journal of Radiology
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• 제22권10호
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• pp.1708-1718
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• 2021

Objective: The purpose of this study was to evaluate the magnetic resonance (MR) characteristics and applicability of new, uniform, extremely small iron-based nanoparticles (ESIONs) with 3-4-nm iron cores using contrast-enhanced magnetic resonance angiography (MRA). Materials and Methods: Seven types of ESIONs were used in phantom and animal experiments with 1.5T, 3T, and 4.7T scanners. The MR characteristics of the ESIONs were evaluated via phantom experiments. With the ESIONs selected by the phantom experiments, animal experiments were performed on eight rabbits. In the animal experiments, the in vivo kinetics and enhancement effect of the ESIONs were evaluated using half-diluted and non-diluted ESIONs. The between-group differences were assessed using a linear mixed model. A commercially available gadolinium-based contrast agent (GBCA) was used as a control. Results: All ESIONs showed a good T1 shortening effect and were applicable for MRA at 1.5T and 3T. The relaxivity ratio of the ESIONs increased with increasing magnetic field strength. In the animal experiments, the ESIONs showed peak signal intensity on the first-pass images and persistent vascular enhancement until 90 minutes. On the 1-week follow-up images, the ESIONs were nearly washed out from the vascular structures and organs. The peak signal intensity on the first-pass images showed no significant difference between the non-diluted ESIONs with 3-mm iron cores and GBCA (p = 1.000). On the 10-minutes post-contrast images, the non-diluted ESIONs showed a significantly higher signal intensity than did the GBCA (p < 0.001). Conclusion: In the phantom experiments, the ESIONs with 3-4-nm iron oxide cores showed a good T1 shortening effect at 1.5T and 3T. In the animal experiments, the ESIONs with 3-nm iron cores showed comparable enhancement on the first-pass images and superior enhancement effect on the delayed images compared to the commercially available GBCA at 3T.

• 대한기계학회논문집A
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• 제32권3호
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• pp.258-266
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• 2008

The conventional approximate optimization method, which uses the statistical design of experiments(DOE) and response surface method(RSM), can derive an approximated optimum results through the iterative process by a trial and error. The quality of results depends seriously on the factors and levels assigned by a designer. The purpose of this study is to propose a new technique, which is called a sequential design of experiments(SDOE), to reduce a trial and error procedure and to find an appropriate condition for using artificial neural network(ANN) systematically. An appropriate condition is determined from the iterative process based on the analysis of means. With this new technique and ANN, it is possible to find an optimum design accurately and efficiently. The suggested algorithm has been applied to various mathematical examples and a structural problem.

• 한국자기공명학회논문지
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• 제5권1호
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• pp.29-36
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• 2001

The structures of two VBS (viral binding site) RNAs, SL1 and SL2, of Yeast Saccharomyces cerevisiae vims have been studied by 2D and 3D NMR experiments. VBSs play a crucial role in viral particle binding to the plus strand and packaging of the RNA. The secondary structures of the two VBS RNAs share a common feature of the stem-internal loop-stem-hairpin loop structure although the size of the internal loops of SL1 and SL2 differs. 2D experiments were sufficient for fill assignments of SL1. However, isotope labeling of the sample and multidimensional experiments were required for 28-nucleotide-long SL2 due to the spectral overlap. Several 3D HCCH experiments have accomplished full assignment of SL2 RNA.

• 한국과학교육학회지
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• 제25권3호
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• pp.346-352
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• 2005

이 연구에서는 문제 해결을 강조한 탐구적 일반화학 실험을 개발하여 그 적용 효과와 학생들의 실험에 참여하는 태도에 미치는 영향을 알아보는데 목적을 두고 있다. 문제 해결을 강조한 일반화학 실험이 실험에 참여하는 태도 변화에 효과가 있었는데, 맹목적 참여자에서 비판적 참여자로 변화한 수가 실험집단에서 3배 가까이 많았다. 또한, 차별성 인식, 탐구 정도, 토론의 유용성 부분에서 유의미한 차이를 보였다.

• 한국대기환경학회지
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• 제11권2호
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• pp.145-152
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• 1995

Predictability of a Gaussian model, ISCST2 was assessed by scaling up wind tunnel experiments with a 1/3,000 terrain model to the real scale. Concentration profiles obtained from the flat-terrain experiment in the neutral condition were estimated to be in agreement with the calculated ones from ISCST2 in the stability class A, but the difference between the two was still large. Concentration profiles from the mountainous-terrain experiments were better fitted to the calculated ones primarily because in the experiment, concentration behind the source was raised due to the effect of a hill in the upstream side. Model prediction was improved with including the downwash effect of buildings and the hill, but overall concentration profiles were not much different from a typical Gaussian profile. While concentration profiles in the experiments were changed with local flows by varying the wind direction and the topography, those from the Gaussian modeling were mot freely changed together with these variations.