• The Korean Journal of Rheology
• /
• v.10 no.2
• /
• pp.82-91
• /
• 1998

액정고분자/폴리카보네이트 혼합계로 구성된 분자복합계를 쉬트상으로 가공할 때 취 약해지기 쉬운 횡단면 방향의 물성을 향상시키기 위하여 미세섬유상의 배향을 in-situ 상태 로 적절히 제어할수 있는 Simultaneous Convergent-Divergent(SCD) 다이를 설계·제작하 고 압출실험을 수행하여 얻은 압출 쉬트를 대상으로 구조-물성-가공의 상관관계를 조사하 였다. 액정고분자의 첨가 함량에 따른 토오크와 토출량의 변화는 액정고분자를 10wt% 소량 첨가하였음에도 현저한 감소 효과를 보였으며 약 30wt%일 때 최소로되었다. 이는 액정고분 자가 보강 기능외에 가공특성의 개선에도 큰 효과가 있어 가공조제로서의 가능성을 보이는 결과로 혼합계의 유변학적 특성 결과에서도 확인할수 있었다. 또 DSC와 DMA를 이용한 열 분석 결과 액정고분자의 함량이 증가함에 따라 PC의 유리전이온도가 다소 감소하는 현상을 보임에 미루어 이 혼합계는 부분적으로 상용성을 갖는 것으로 볼수 있으며 모폴로지 분석을 통해서도 이를 확인할수 있었다. TLCP/PC 혼합계로 구성되는 분자복합재를 SCD 다이를 사용하여 제조한 압출 쉬트의 방향성에 따른 기계적 물성은 기존의 쉬트 다이보다 흐름방향 으로는 다소 낮은 물성치를 보이지만 횡단면 방향으로는 물성이 현저히 향상됨을 관찰할수 있었다. 모폴로지 분석결과 기존의 쉬트 다이의 경우 벽면 부근에서는 액정고분자가 미세섬 유상으로 형성되어 흐름방향으로 배향되어 있지만 중심부에서는 액정 상태로 존재하는 반 면, SCD 다이의 경우 미세섬유상으로 형성된 액정고분자가 벽면에서부터 중심부로 갈수록 횡단면 방향으로 서서히 배향되어 있음을 확인할수 있었다.

• Journal of Bio-Environment Control
• /
• v.2 no.1
• /
• pp.37-45
• /
• 1993

The purpose of this research was to develop ideal substrates for the production of good quality tomatoes in bag culture system and also to improve media with low or no environmental pollution by blending and mixing artificial substrate including peatmoss, perlite, vermiculite, granular rockwool, polyphenol resin foam, bark, and smoked rice hull. The highly efficient media proved by experiments were vermiculite, smoked rice hull, polyphenol resin foam, granular rockwool, and perlite, which showed good results in the early growth as well as the marketable yield of tomato in the bag culture. Tomato plants grown in the media mixed with peatmoss, vermiculite and granular rockwool at the ratio of 3 : 1 : 1(by volume) showed the highest marketable yield, and the next at the ratio of 2 : 1 : 1. The perlite-granular rockwool mixtures at the ratio of 2 : 3 and 1 : 4, and the peatmoss vermiculite mixtures at the ratio of 2 : 3 and 3 : 2, seemed to be promising media for bag culture.

• The Journal of Korean Institute for Practical Engineering Education
• /
• v.2 no.1
• /
• pp.52-57
• /
• 2010

Using the Operating Systems course that is offered by online, a blended learning mixed up with face-to-face lecture and e-learning for O.S. course has been carried out. In order to find a efficient management way of the blended learning, we build up two groups: one group named 01 takes a class which consists of two hours face-to-face lecture and one hour online study per week and the other group named 02 takes a class which consists of two hours online study and one hour face-to-face lecture. According to the result of a mid-term examination, the Cohen's d between two groups is 0.165. It means the small effect size. The 01 group has higer average and smaller variance than 02 group. However, 02 group has more students who earn high score than 01 group. In conclusion, if students can well carry out the self-regulated learning, then the blended learning mixed up with 02 group style is suitable. Otherwise, face-to-face lecture or the blended learning like 01 group style is suitable.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.3
• /
• pp.129-137
• /
• 2021

This study is a qualitative study conducted using focus group interviews to examine the mixed offline and online education experience of nursing students in the context of Covid-19. The subjects of this study included 7 students enrolled in the Department of Nursing at J City V University, and focus group interviews were conducted with sufficient explanation and written consent for the study. The contents of the interviews were recorded, and the interview contents were directly transcribed directly after the interview. Research results were derived through content analysis. As a result of the study, 5 domains, 10 categories, and 24 subcategories were derived from the experiences of nursing college students on mixed lectures. The 5 domains included 'mixed lectures,' 'tasks,' 'tests,' 'motivation,' and 'improvement.' The contents of each domain derived from this research result are expected to be used as basic data in the design of the on/offline mixed lectures in the future.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.9 no.1
• /
• pp.61-66
• /
• 2005

A theoretical analysis is developed for an annular-injection-type supersonic ejector having a second-throat downstream the ejector under the assumption that the Fabri choking is placed in mixing chamber. Non mixing theory is applied to formulate secondary flow pressure in the region between inlet of the mixing chamber and Fabri choking. To describe the shock standing at the inlet of the mixing chamber, two dimensional oblique shock relations are used and it is assumed that the shock affects only primary flow at Fabri choking plane. Physical constraint, which is that primary flow pressure and secondary flow pressure are same at Fabri choking plane, is added. In conclusion, it agrees well with experiments in case of small contracting angle of mixing chamber, under 4degrees.

• 대한공업교육학회지
• /
• v.34 no.2
• /
• pp.267-285
• /
• 2009

The collaborative learning has been considered as an efficient teaching model and under the recent basic learning environment, even face-to-face classroom circumstance rapidly increases the courses of blended learning which utilize the merits of e-learning environment. Nonetheless, the study on the strategy for systematic blended learning is quite scarce. In this study, the survey was done for developing the blended learning strategy, based on the collaborative learning model at the face-to-face environment and judging the satisfaction on the courses which the model was applied to. The survey consists of demographic questions, satisfaction in the whole courses, satisfaction in the collaborative learning under the blended learning environment and satisfaction in the blended learning strategy and support tools applied to each step of the learning. The result of this study is as follows. First, in response to the question that the blended learning can complement the face-to-face classroom courses, the respondents represented average 4.09 at 5-point Likert scale. And to the question whether the collaborative learning is more efficient under the blended learning environment than the face-to-face classroom, the response corresponds to 4.06 scale on the average. Second, as for the satisfaction in the blended learning strategy and support tools applied to the each step of the blended learning, the satisfaction degree is analyzed as high as over 4.0 on the average toward all the questions. Third, regarding the support tools used for the blended learning strategy, the learners consider the tools as most helpful in order of chatting, team community, mail & note and archive. Lastly, I would like to suggest that the study result should be highly reflected in constructing the collaborative learning module of learning control system in the future.

• Korean Journal of Plant Resources
• /
• v.14 no.3
• /
• pp.196-205
• /
• 2001

The results of examining cultivation of tlyster mushroom using NSM(Non Sterilized Media) for determining the condition of artificially culturing oyster mushroom(Pleurotus ostreatus) are as follows. Mycelial growth an[1 density of oyster mushroom. were the highest in the medium of waste cotton(spinning) : corn cob(80 : 20, V/V) followed by the order of rice bran, beet pulp. Expecially, mycelial growth and density of oyster mushroom is the lowest at the mixture rate of 80% waste cotton(spinning) : 10% beet pulp. Mycelial growth and density of oyster mushroom. were the highest in the medium of cotton seed hull and beet pulp mixture followed by the order of rice bran, corn cob. Expecially, mycelial growth and density of oyster mushroom is the lowest at the mixture rate of 80% cotton seed hull : above 20% rice bran. Mycelial growth and density of oyster mushroom were the highest in the medium rate of 70% waste cotton(spinning), 10% corn cob and 10% beet pulp(V/V). Mycelial growth and density of oyster mushroom were the highest in the medium rate of 70% cotton seed hull , 10% corn cob and 10% beet pulp(V/V). Optimal concentration of NSM for the mycelial growth and density of oyster mushroom were shown to be 500 times concentration. Optimal water contents for the mycelial growth and density of NSM was 70%.

• Journal of the Korean Geotechnical Society
• /
• v.15 no.3
• /
• pp.71-81
• /
• 1999

A study on the undrained behavior of isotropically consolidated clay-sand mixtures was carried out using the automated triaxial testing apparatus. Overconsolidated ratio, effective mean pressure and clay content( up to 20% bentonite) were the factors varied in the experimental investigation. Undrained behavior(strength and pore water pressure generation during shear in triaxial loading) depends upon overconsolidation ratio, confining pressure and clay content. Significant changes in undrained compression characteristics occurred at around 20% of clay contents in the sand. The test results were analyzed and their behaviors were interpreted within the framework of plasticity constitutive model for clay-sand mixtures. Possible physical bases for the proposed forms are discussed. Validation of the applied model using the laboratory results is also given.

• Proceedings of the Korean Fiber Society Conference
• /
• 1998.10a
• /
• pp.110-113
• /
• 1998

면/양모 혼방직물은 면 섬유와 양모 섬유의 특징을 적절히 혼합하여 이용할 수 있는 이점이 있지만 염색에 의해 균염을 얻기 어려운 단점을 가지고 있다. 일반적으로 면/양모 혼방직물은 각 구성 섬유의 염색성이 상이하여 이 욕에 의한 염색이 일반화되어 있으나, 이는 양모의 알카리에 의한 상해를 동반하기도 하며 공정의 이분화로 인해 비경제적이라고 할 수 있다. (중략)

• Restorative Dentistry and Endodontics
• /
• v.28 no.2
• /
• pp.169-177
• /
• 2003

본 연구는 total etching (Scotchbond Multi-Purpose; MP) 및 self-etching (Clearfil SE Bond; SE 과 Prompt L-pop LP) 상아질 접착제의 nanoleakage 양상을 관찰하고 열순환 후의 nanoleakage 양상의 변화를 분석하고자 하였다. 30개의 발거된 치아의 교합면 및 협, 설측 법랑질을 제거하였다. 열 순환 시행 여부에 따라 두 군으로 나누어 실험하였으며 각각의 상아질 접착제 도포 후 Z-250으로 교합면을 수복하였다. Silver nitrate용액 및 현상액에 침적 후치아의 협설 방향으로 평행하게 절단하여 SEM으로 관찰하였다. 서로 다른 양상의 nanoleakage가 관찰되었다. MP의 경우는 resin tag 주위로 뚜렷한 은의 침착을 관찰 할 수 있었으며 혼합층 전체 두께에 띠 및 점상으로 흩어져 침착된 은을 관찰 할 수 있었다. SE의 경우는 혼합층의 하층을 따라 은으로 침착된 선을 관찰 할 수 있었으며 혼합층과 adhesive 경계를 따라 무정형의 은 침착물 들을 관찰할 수 있었다. LP의 경우는 혼합층의 하부 및 혼합층 내에 띠 모양으로 은의 침착을 관찰 할 수 있었으며 혼합층의 하부에서는 관찰되지 않고 혼합층의 내부에서만 관찰되는 경우도 있었다. 열순환을 시행한 군에서는 전반적 nanoleakage 양상은 열 순환을 시행하지 않은 군과 유사하였으나 은 침착의 증가를 관찰 할 수 있었다.