선형회귀모형에서 다중공선성이 존재할 때 결정계수에 대한 연구+

유정빈 서원대학교 응용과학연구소 1996 응용과학연구 Vol.5 No.1

The coefficient of determination R²is a very useful measure in linear regression analysis. But if the independent variables are correlated, many problems are produced in ordinary linear regression analysis. One of them is (수식입력불가). Sometimes under what conditions the sum is less than (수식입력불가). This topic was discussed in Park and Lee(1995). But the sufficient conditions that they founded for k=3 are ambiguous. In addition, examples to be proposed are not available. In this paper the new method to find the conditions for (수식입력불가) and for k=2 and 3 the new examples to be available in most practical cases are proposed.

임업총조사 자료로부터 층화절사추출법을 이용한 표본크기 결정 방법

유정빈 서원대학교 응용과학연구소 2002 응용과학연구 Vol.11 No.1

In this paper, a sample design is studied for 2000 forestry management survey of five types forestry ; tree felling gathering of pine mushroom, growing of nut trees, growing of wild flowers, and lumbering industry. I introduce population stratificatin and a modified stratified cut-off sampling which deal with determination of sample size.

반응표면 분석에서 다중반응의 동시 최적화

유정빈 서원대학교 응용과학연구소 1994 응용과학연구 Vol.3 No.1

A method is developed for the simultaneous optimization of several response functions that depend on the same set of controllable variables and are adequately represented by a response surface model of the same degree. This algorithm is developed under the condition that individual response has the target value. In order to use Box-Draper estimation the data are first checked for linear dependencies among the responses by eigenvalue analysis. Thus a set of responses among which no linear functional relationships exist is chosen and used in developing a functions that measures the distance of the vector of estimated responses from the target values.

다구찌 품질 공학에 관한 연구

유정빈 서원대학교 응용과학연구소 1992 응용과학연구 Vol.1 No.1

This paper considers the philosophy and methods proposed by Professor G. Taguchi. He has emphasized the use of designed experiments in several novel and important applications. And the use of statistical experimental designs is accomplished by designing products to be robust to environmental conditions. The engineering concept of robust product design is very important since it is frequently impossible to control sources of variation due to environmental conditions. Robust product design enables the experimenter to discover how to nodify the design of the product to minimize the effect due to variation from environmental sources. In the present paper the many criticisms and improved propositions which are discussed from 1985 to 1991 contain. In particular the uses of crossed-product orthogonal arrays in the parameter designs, of the ANOVA by SN-ratios and of the accumulation analysis are discussed. And as the process optimization going beyond Taguch Methods, the response surface methods (RSM) are introduced.

수중 외발젓기 운동 시 수심과 속도에 따른 주동근 근전도 반응에 미치는 영향

유정빈,최종인,김기홍 한국스포츠학회 2022 한국스포츠학회지 Vol.20 No.2

The purpose of this study was to analyze muscle activity of lower extremity and trunk muscles according to water depth and speed during single leg swing aquatic exercise, and to provide a mechanism for intermuscular coordination to maintain balance and basic data for balance training in water. The subjects of this study were 9 males with more than 6 months of resistance training experience, and a total of 9 experiment were performed according to 3 water depths and speed conditions. EMG was measured during exercise and the measured variables were analyzed with Repeated measurements two-way ANOVA. As a result, as the speed of rowing foot increased, the muscle activity was significantly higher in the lower extremity and trunk muscles(p=.001), (p=.019, p=.001). On the other hand, the lower the water depth, the higher the calf muscle activity of the stepping foot(p=019, p=.001), and the higher the rectus abdominis muscle activity at the waist(p=.043). Therefore, this study is thought to be able to control intensity of exercise by increasing the speed during exercise to improve balance in water, and in the water depth condition, it is appropriate to gradually lower the water depth for training the muscles around the ankle, and it is judged that the waist depth is the most suitable for training the trunk muscles. 이 연구는 수중 외발젓기 운동 시 수심과 속도에 따른 하지근과 몸통근의 근활성도를 분석하여 균형을 유지하기 위한 근육 간 협응 기전과 수중에서 평형성 훈련 시 기초자료를 제공하고자 하였다. 연구대상자는 저항운동 경력 6개월 이상의 남자 대학생 9명을 선정하였으며, 3가지 수심과 속도조건에 따라 수중 외발젓기 운동을 총 9회 실시하였다. 운동 중 하지근과 몸통근의 근전도를 측정하였으며, 측정된 변인들은 반복측정 이원변량분석으로 분석하였다. 그 결과 젓는발의 속도가 빨라질수록 하지근과 몸통근에서 근활성도가 유의하게 높게 나타났으며(p=.001), (p=.019, p=.001), 한편 수심 조건에서는 수심이 낮아질수록 디딤발 종아리 근육의 근활성도가 유의하게 높게 나타났고(p=019, p=.001), 배곧은근은 허리수심에서 근활성도가 유의하게 높게 나타났다(p=.043). 따라서 이 연구는 수중에서 평형성 향상을 위한 운동 시 동작의 속도를 증가시켜 운동의 강도를 조절할 수 있을것으로 판단되며, 한편 수심에 따라서는 발목 주변 근육의 강화를 위해 단계적으로 수심을 낮추는 것이 효과적이고, 몸통 주변 근육의 강화를 위해서는 허리수심이 가장 적합할 것으로 판단된다.

비대칭 모집단을 두 개의 층으로 나누는 절사점에 대한 연구

유정빈 서원대학교 응용과학연구소 2001 응용과학연구 Vol.10 No.1

In extremely non-symmetric distribution it is very difficult to design the sampling method. Cut-off sampling is a proper method in this situation. In this method it is not easy to decide the cut-off point which devide two strata. A criterion of deciding the cut-off point which devide two strata will be suggested by using population-ratio of a specific item, sampling number and MSE.

Enhancement of Thermo-Electric Energy Conversion Using Graphene Nano-platelets Embedded Phase Change Material

유정빈,윤재륜,송영석 한국고분자학회 2021 Macromolecular Research Vol.29 No.8

Phase change materials (PCMs) containing graphene nano-platelets (GNPs) were fabricated and utilized for efficient thermo-electric energy harvesting during the phase transition process. A system composed of two different PCMs at opposite positions can absorb or release large amounts of thermal energy while remaining in a nearly isothermal condition. Based on the Seebeck effect, the energy harvesting system generates electrical current from temperature differences. The increase in the thermal conductivity of the PCMs can create isothermal fields and enhance thermoelectric energy conversion efficiency. In this study, two different PCM composites were found to exhibit higher thermal conductivity with increasing the amount of GNPs filler. The thermal conductivity of the two composites clearly increased to 0.5858 W/mK and 0.4974 W/mK, while the heating and cooling thermo-electric conversion efficiencies were also enhanced to 55.59% and 33.33%. Furthermore, the thermo-electric energy profiles were numerically modeled using the finite element method (FEM) to compare with the experimental results.

Modification of Graphene Aerogel Embedded Form-Stable Phase Change Materials for High Energy Harvesting Efficiency

유정빈,송영석 한국고분자학회 2022 Macromolecular Research Vol.30 No.3

While porous graphene aerogel can hold plenty of pure phase change material (PCM) in the internal space, its volume shrinkage is a serious problem to decrease the weight of working material. Since the thermal energy storage (TES) capacity of PCM composite, however, depends on the mass ratio of pure PCM during the phase transition process, graphene aerogel filled PCM composite is an appropriate material for high latent heat thermal energy storage (LHTES). In this work, polydimethylsiloxane (PDMS) is embedded into the graphene aerogel by using a spraying method. The PDMS-embedded graphene aerogel exhibits higher mechanical property and flexibility than pristine aerogel. It reduces the volume shrinkage effectively and sustains the initial 3D porous structure to infiltrate pure PCM into the internal space, which can lead to an increase in the efficiency of thermo-electric energy harvesting due to the increase of PCM weight. A PN junction of thermo-electric power generator (PN TEG) is connected to the modified PCM composites, and a temperature difference between two sides of device occurs under the change of external conditions. The modified PCM composites constructed PN TEG generates stable and continuous thermo-electric energy during heating and cooling processes. In addition, finite element method (FEM) is employed to verify the experimental measurement.

소지역추정법에 의한 충청북도 농림어업과 제조업부문의 GRDP 추계

유정빈 서원대학교 응용과학연구소 2002 응용과학연구 Vol.11 No.1

In this Era of Information and Localization, Gross Regional Domestic Product(GRDP) is recognized as indispensable information to establish regional economic policy. Especially, to raise Chungbuk province's economical independence and to establish effectual regional economic development plans, Chungbuk province needs quarterly estimated GRDP for developing regional economic forecasting system. In this study, utilizing small area estimation is proposed to estimate the quarterly Chungbuk-GRDP. To estimate quarterly GRDP, this study assumes that the comovement between the annual Chungbuk-GRDP provided by the Bureau of Statistics and nation's GDP provided by Bank of Korea exists. Moreover, from the nation's quarterly GDP in each section of economical activity, this study has presumed the quarterly comovement, applied it to subdivide Chungbuk annual GRDP quarterly, and estimated quarterly Chungbuk-GRDP.

갱년기 비만 여성의 체중감량 운동프로그램 사례

유정빈,손재헌,김기홍 대한운동사협회 2015 대한운동사협회 운동사대회자료집 Vol.2015 No.-