실험계획법을 이용한 수나사 유효지름의 최적 측정방법에 대한 연구

유민우 한국기계기술학회 2022 한국기계기술학회지 Vol.24 No.5

Screws are the closest and most familiar mechanical elements of everyday life, and are generally used so widely that there is no machine without screws. Screws are used to make it easier to combine objects with objects, and are also used to transfer large forces from machines. The most influential factor in the coupling of these screws is the effective diameter. If the effective diameter is not accurate, the support cannot be finished or endured, leading to a major accident. The importance of these screws cannot be ignored, so in this study, the effective diameter was measured using the three-wire method, the screw micrometer method, and the projector method, and the one-way factor design method was applied to determine the exact method compared to the KS standard.

대학 실시간 온라인 수업유형에 따른 수업만족도와 학습실재감에 대한 상호작용 분석

유민우,김승옥,유병민 학습자중심교과교육학회 2024 학습자중심교과교육연구 Vol.24 No.3

목적 대학 실시간 온라인 강의에서 수업유형(강의유형과 교과유형)에 따른 학습자의 수업만족도와 학습실재감을 조사⋅분석하여사회적 위기 강화 실정을 맞이한 대학 교육 현장의 주요 대안으로 선택된 실시간 온라인 강의의 면대면 수업 대체 가능성과 발전 방향을 모색하고자 하였다. 방법 이를 위하여 2020년 9월 이전에 실시간 온라인 강의를 수강한 국내 대학 재학생 309명을 대상으로 웹 설문조사를 진행하였다. 실시간 온라인 수업을 선택하는 과정에서도 동일한 정보를 토대로 수업을 선택하였을 것으로 가정하여 수업유형을 강의유형(강의식 수업, 혼합식 수업)과 교과유형(이론 수업, 실습 수업)으로 구분하고 독립변인으로 설정하였다. 자료분석은 SPSS.22를 이용하여 자료를 분석하였다. 연구 도구의 일관성을 검증하기 위하여 Cronbach’ α 계수를 산출하여 신뢰성 분석(reliability)을 수행하였다. 또한 강의유형과 교과유형에 따른 수업만족도의 차이를 분석하기 위해 이원분산분석(Two-way ANOVA), 강의유형과 교과유형에 따른 학습실재감의 차이를 분석하기 위해 다변량분석(MANOVA)을 실시하였다. 결과 첫째, 대학 실시간 온라인 수업에서 교과유형에 따른 수업만족도는 유의미한 차이가 없는 것으로 나타났고, 강의유형에만 유의미한 차이가 있는 것으로 나타났다. 둘째, 강의유형과 교과유형에 대한 학습실재감은 유의미한 차이가 드러나지 않았다. 셋째, 실시간 온라인 수업에서 교과유형과 강의유형의 상호작용에 따른 수업만족도의 상호작용 효과가 없는 것으로 나타났다. 넷째, 실시간온라인 수업에서 교과유형과 강의유형의 학습실재감에 대한 상호작용은 효과가 있는 것으로 나타났다. 결론 본 연구결과를 토대로 실시간 온라인 수업에서 학습실재감의 증진을 위해서는 이론 수업은 강의식 수업을, 실습수업은 혼합식수업을 채택하는 것이 효과적이였다. 따라서 대학 수업의 과목별 특성을 개별적으로 고려하여 수업의 만족도와 학습실재감을 향상시킬수 있도록 학습자 친화적인 경험이 반영된 상호작용 증진을 위한 실시간 온라인 수업 모델의 지속적 연구가 필요하다. Objectives The purpose of this study was to examine interaction between learning method and couse division on learning satisfaction and learning presence in the synchronous universities online class. Methods Based on such research theories, the study conducted an online survey of 309 Korean university students who took synchronous online class before September 2020. The questionnaire was developed through a prior study analysis, and 308 respondents, excluding one unfaithful case, were targeted for analysis. The data was analyzed by using the Microsoft Excel spread sheet and SPSS.22 program to verify the research hypothesis. The reliability test was conducted to verity the internal consistency by calculating Cronbach' α coefficient. In addition, a Two-way ANOVA was conducted to analyze the differences in learning satisfaction between he learning method and course division, and a multivariate analysis(MANOVA) was conducted to analyze the differences in the learning presence according to he learning method and course division. Results First, in synchronous online classes at universities, the learning satisfaction level according to the type of course division was found to be no significant difference, and there were significant differences only in the type of learning method. Second, the presence of learning about the course division did not reveal any significant difference. Third, in synchronous classes, the interaction of learning satisfaction with the interaction of course division and learning method was found to be ineffective. Fourth, the interaction effect of the course division and learning method on the learning presence was shown in synchronous online classes. Conclusions The synchronous online lectures were difficult to completely replace existing face-to-face lectures. Therefore, based on the characteristics of the platform on which synchronous online lectures are conducted and the learner's needs, a continuous study of the model of synchronous online classes should be processed.

리튬용액 침투방법에 의한 Li2TiO3 페블 제조

유민우,박이현,이상진 한국세라믹학회 2013 한국세라믹학회지 Vol.50 No.5

To fabricate spherical lithium titanate (Li2TiO3) pebbles which are used for a breeder material in fusion reactor, titanium oxide (TiO2)granules were used as a starting material. The granules were pre-sintered, and then aqueous lithium nitrate solution infiltrated into the granules at vacuum condition. The granules were crystallized to Li2TiO3 after sintering under the control of process parameters. In this study, the concentration of lithium in the solution, as well as the number of penetration times and sintering temperature affected the final crystallite phase and the microstructure of the pebbles. In particular, the sphericity and size of the pebbles were effectively controlled by a technical rolling process. The useful spherical Li2TiO3 pebbles which have 10 ~ 20% porosity and 60 ~ 120 N compressive strength were obtained through the sintering at 1000 ~ 1100o C in the multi-times infiltration process with 50 wt%solution. The physical properties of pebbles such as density, porosity and strength, can be controlled by a selection of TiO2 powders and control of processing parameters. It can be thought that the lithium penetration method is a useful method for the fabrication of mass product of spherical Li2TiO3 pebbles.

One-way ANOVA를 적용한 진원도 최적 측정방법에 대한 연구

유민우,정호연 한국기계기술학회 2023 한국기계기술학회지 Vol.25 No.5

Out-of-roundness is crucial for the proper functioning of individual products or parts in a machine. Mechanical components often consist of circular elements that require precise alignment. These circular parts are used in critical areas of the machine, and the shape characteristics of each component can significantly impact overall performance. In this study, we focus on a specific specimen and use three different methods - the Diameter method, Radius method, and Three-point method - to measure its out-of-roundness. The collected data is then analyzed using one-way ANOVA to propose an effective out-of-roundness measurement technique suitable for industrial settings.

리튬용액 침투방법에 의한 Li₂TiO₃ 페블 제조

유민우,박이현,이상진,Yu, Min-Woo,Park, Yi-Hyun,Lee, Sang-Jin 한국세라믹학회 2013 한국세라믹학회지 Vol.50 No.5

To fabricate spherical lithium titanate ($Li_2TiO_3$) pebbles which are used for a breeder material in fusion reactor, titanium oxide ($TiO_2$) granules were used as a starting material. The granules were pre-sintered, and then aqueous lithium nitrate solution infiltrated into the granules at vacuum condition. The granules were crystallized to $Li_2TiO_3$ after sintering under the control of process parameters. In this study, the concentration of lithium in the solution, as well as the number of penetration times and sintering temperature affected the final crystallite phase and the microstructure of the pebbles. In particular, the sphericity and size of the pebbles were effectively controlled by a technical rolling process. The useful spherical $Li_2TiO_3$ pebbles which have 10~20% porosity and 60~120 N compressive strength were obtained through the sintering at $1000{\sim}1100^{\circ}C$ in the multi-times infiltration process with 50 wt% solution. The physical properties of pebbles such as density, porosity and strength, can be controlled by a selection of $TiO_2$ powders and control of processing parameters. It can be thought that the lithium penetration method is a useful method for the fabrication of mass product of spherical $Li_2TiO_3$ pebbles.

복합운동 및 비트루트 섭취가 중년비만 여성의 간기능 및 심혈관질환 위험인자에 미치는 영향

유민우,조준용 한국체육대학교 체육과학연구소 2022 스포츠사이언스 Vol.40 No.1

The purpose of this study was to verify the effect of beetroot intake and combined exercise on liver function and cardiovascular disease risk factors in middle-aged obese women. For this purpose, the study was conducted on 20 middle-aged obese women aged 40-55 who expressed their intention to participate in the study. To this end, the study was conducted for 8 weeks by dividing the group into a beat intake and complex exercise group (n=5), a beat intake group (n=5), a complex exercise group (n=5), and a control group (n=5). The collected data were analyzed using the spss25.0 statistical program, and to calculate the mean and standard deviation for each item of all variables, and to compare the difference between the mean values ??of each item before and after the experiment between the four groups, the two-way variable by repeated measurement. analysis was analyzed. If there was a difference between groups, Tukey was used for post-test. If there was an interaction, a paired sample t-test was performed to verify the difference within the group. The statistical significance level for each item was set to α<.05. The results were derived as follows. As a result of pre-post comparison in the beat intake and complex exercise groups, significant differences were found in all variables. Therefore, combined exercise and beet intake in this study improved liver function in middle-aged obese women and showed a positive effect on cardiovascular disease risk factors. These positive effects are considered to have an effect on improving the health of obese middle-aged women and reducing cardiovascular disease risk factors. It is considered that follow-up studies on beet intake and exercise are needed in the future.

복합 운동과 오메가-3(Ω-3PUFA) 보충이 비만 여성의 체성분, 혈청 지질 프로필, 염증 매개체, 근육 성능 및 인지 능력에 미치는 영향

유민우,조준용 한국체육대학교 체육과학연구소 2023 스포츠사이언스 Vol.41 No.2

The purpose of this study was to investigate the effects of combined exercise and omega-3 intake on body composition, blood lipids, muscle function, inflammatory markers, and cognitive function in middle-aged obese women. A total of 21 obese women (46.14 ± 5.01 years old, BMI = 28.54 ± 2.26 kg/m2) were placed into 3 groups (7 in each group) including placebo (C), ω-3(S) and ω-3 plus exercise. separated by The ω-3 group and the COMBI group consumed 2000mg of ω-3 supplement daily, and the COMBI group performed compound exercise. The collected data were subjected to two-way analysis of variance by repeated measurements using the SPSS 25.0 statistical program, and a paired-sample t-test was conducted to verify differences within groups in the case of interactions. As a result, in the COMBI group, body composition improved and blood lipids decreased. In addition, the COMBI group showed a decrease in inflammation level, a positive effect on muscle function, and an increase in BDNF level in cognitive function tests. These positive effects suggest that combined exercise and ω-3 intake lowered body fat by regulating blood lipids in middle-aged obese women, alleviated inflammatory biomarkers, promoted serum BDNF levels, and had a positive effect on muscle performance, thereby reducing middle-aged obesity. It will improve women's health and help prevent obesity.

멀티모드 하이브리드 차량용 건식클러치의 자동화 메카니즘 분석

유민우(Minwoo Ryu),임원식(Wonsik Lim),남궁철(Koongchoul Nam),김수현(Soohyun Kim) 한국자동차공학회 2012 한국자동차공학회 부문종합 학술대회 Vol.2012 No.5

Due to the increase of oil price, the needs of the reduction of the fuel cost is rising. Therefore, necessity of hybrid vehicle that runs with engine and the electric motor is on the rise. Hybrid vehicles have been developed into various ways including serial type, parallel type, power split type. In this research, multi mode hybrid power train system, which can implement more than two modes, is used as subject. Especially, automation mechanism of dry type clutch, that exist between engine and power split gear train, is analyzed in detail.

경기변동과 인플레이션 사이의 동태적 관계 분석

유민우 ( Min Woo Ryu ),이한식 ( Hahn Shik Lee ) 서강대학교 경제연구소 2007 시장경제연구 Vol.36 No.-

운전자 모니터링 시스템을 위한 최적의 운전자 영역 검출

유민우(Min Woo Yoo),사비나 콜라코(Savina Colaco),김도형(Kim Do Hyung),한동석(Dong Seog Han) 한국통신학회 2019 한국통신학회 학술대회논문집 Vol.2019 No.11