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221.

University Instructors Beliefs and Practices Toward Student-Centered Learning

Lee Eunbae 한국교육학회 교육학연구 24 Pages

한국교육학회 교육학연구 2021, 59권 7호 1 1-24 (24 pages)

Lee Eunbae 저
...
- 5,300원
This study explores undergraduate course instructors’ stated beliefs and practices toward student-centered learning. In-depth interviews with four undergraduate course instructors in a variety of disciplines in the United States revealed their beliefs about the roles of instructors’ and students’ as well as student-centered learning. Also, the instructors’ teaching styles are measured and compared with their stated beliefs and practices. Through thematic analysis and deductive and inductive...
222.

Psychometric Properties of Context-Specific Measures of Students’ Interest and Value in Learning Science : A Multinational Examination

Ham EunHye, Jang Hyesuk, Shin TaeSeob 한국교육학회 교육학연구 22 Pages

한국교육학회 교육학연구 2015, 53권 4호 12 305-326 (22 pages)

Ham EunHye, Jang Hyesuk, Shin TaeSeob 저
...
- 5,100원
This study aims to examine how context-specific measures of students' interest and value differ from their context-general measures in psychometric properties across countries. Using PISA2006 Science data, differential effects of item context on assessing interest and value were illustrated in both the individual and country levels. The main findings are as follows: First, correlation between context-specific and context-general measures tended to be slightly higher in value than in interest....
223.

Catalytic hydrogenation-assisted preparation of melt spinnable pitches from petroleum residue for making mesophase pitch based carbon fibers

Dong Hun Lee, Jisu Choi, Young Se Oh, Yoong Ahm Kim, Kap Seung Yang, Ho Jin Ryu, Yong Jung Kim 한국탄소학회 Carbon Letters 8 Pages

한국탄소학회 Carbon Letters 2017, Vol.24 4 28-35 (8 pages)

Dong Hun Lee, Jisu Choi, Young Se Oh, Yoong Ahm Kim, Kap Seung Yang, Ho Jin Ryu, Yong Jung Kim 저
...
- 3,000원
We demonstrated an effective way of preparing melt spinnable mesophase pitches via catalytic hydrogenation of petroleum residue (fluidized catalytic cracking-decant oil) and their subsequent thermal soaking. The mesophase pitches thus obtained were analyzed in terms of their viscosity, elemental composition, solubility, molecular weight, softening point and optical texture. We found that zeolite-induced catalytic hydrogenation under high hydrogen pressure contributed to a large variation in the...
224.

Hole quality assessment of drilled CFRP and CFRP-Ti stacks holes using polycrystalline diamond (PCD) tools

Dave Kim, Aaron Beal, Kiweon Kang, Sang-Young Kim 한국탄소학회 Carbon Letters 8 Pages

한국탄소학회 Carbon Letters 2017, Vol.23 1 1-8 (8 pages)

Dave Kim, Aaron Beal, Kiweon Kang, Sang-Young Kim 저
...
- 3,000원
Polycrystalline diamond (PCD) tools possessing high hardness and abrasive wear resistance are particularly suited for drilling of carbon fiber reinforced plastic (CFRP) composites, where tool life and consistent hole quality are important. While PCD presents superior performance when drilling CFRP, it is unclear how it performs when drilling multi-stack materials such as CFRP-titanium (Ti) stacks. This comparative study aims to investigate drilling of a Ti plate stacked on a CFRP panel when...
225.

Synthesis and characterization of carbon doped TiO₂ photocatalysts supported on stainless steel mesh by sol-gel method

JO. Tijani, OO. Fatoba, TC. Totito, WD. Roos, LF. Petrik 한국탄소학회 Carbon Letters 12 Pages

한국탄소학회 Carbon Letters 2017, Vol.22 6 48-59 (12 pages)

JO. Tijani, OO. Fatoba, TC. Totito, WD. Roos, LF. Petrik 저
...
- 4,100원
This study synthesized pure anatase carbon doped TiO₂ photocatalysts supported on a stainless steel mesh using a sol-gel solution of 8% polyacrylonitrile (PAN)/dimethylformamide (DMF)/TiCl₄. The influence of the pyrolysis temperature and holding time on the morphological characteristics, particle sizes and surface area of the prepared catalyst was investigated. The prepared catalysts were characterized by several analytical methods: high resolution scanning electron microscopy (HRSEM), energy...
226.

The effect of the spinning conditions on the structure of mesophase pitch-based carbon fibers by Taguchi method

Zhao Jiang, Ting Ouyang, Xiangdong Yao, Youqing Fei 한국탄소학회 Carbon Letters 10 Pages

한국탄소학회 Carbon Letters 2016, Vol.19 11 89-98 (10 pages)

Zhao Jiang, Ting Ouyang, Xiangdong Yao, Youqing Fei 저
...
- 3,000원
Taguchi’s experimental design was employed in the melt spinning of molten mesophase pitch to produce carbon fibers. The textures of the obtained carbon fibers were radial with varied crack angles, as observed by scanning electron microscopy and polarized optical imaging. The diameter, crack angle, preferred orientation, and tensile modulus of the produced samples were examined to investigate the influence of four spinning variables. The relative importance of the variables has been emphasized...
227.

Pitch-based carbon fibers from coal tar or petroleum residue under the same processing condition

Jiyoung Kim, Ui-Su Im, Byungrok Lee, Dong-Hyun Peck, Seong-Ho Yoon, Doo-Hwan Jung 한국탄소학회 Carbon Letters 7 Pages

한국탄소학회 Carbon Letters 2016, Vol.19 9 72-78 (7 pages)

Jiyoung Kim, Ui-Su Im, Byungrok Lee, Dong-Hyun Peck, Seong-Ho Yoon, Doo-Hwan Jung 저
...
- 3,000원
Spinnable pitches and carbon fibers were successfully prepared from petroleum or coal pyrolysis residues. After pyrolysis fuel oil (PFO), slurry oil, and coal tar were simply filtered to eliminate the solid impurities, the characteristics of the raw materials were evaluated by elemental analysis, 13C nuclear magnetic resonance spectrometer, matrix-assisted laser desorption/ionization time-of-flight mass spectrometer (MALDI-TOF-MS), and so on. Spinnable pitches were prepared for melt-spinning...
228.

Microstructural changes of polyacrylonitrile-based carbon fibers (T300 and T700) due to isothermal oxidation (1): focusing on morphological changes using scanning electron microscopy

Seong-Moon Oh, Sang-Min Lee, Dong-Su Kang, Jae-Seung Roh 한국탄소학회 Carbon Letters 6 Pages

한국탄소학회 Carbon Letters 2016, Vol.18 3 18-23 (6 pages)

Seong-Moon Oh, Sang-Min Lee, Dong-Su Kang, Jae-Seung Roh 저
...
- 3,000원
Polyacrylonitrile (PAN)-based carbon fibers have high specific strength, elastic modulus, thermal resistance, and thermal conductivity. Due to these properties, they have been increasingly widely used in various spheres including leisure, aviation, aerospace, military, and energy applications. However, if exposed to air at high temperatures, they are oxidized, thus weakening the properties of carbon fibers and carbon composite materials. As such, it is important to understand the oxidation...
229.

Advances in liquid crystalline nano-carbon materials: preparation of nano-carbon based lyotropic liquid crystal and their fabrication of nano-carbon fibers with liquid crystalline spinning

Yong-Mun Choi, in Jung Jun Yeon, Hwang Seung Min, Kim Hyeonsu Jeong, Bon-Cheol Ku, Munju Goh 한국탄소학회 Carbon Letters 10 Pages

한국탄소학회 Carbon Letters 2015, Vol.16 No.4 1 223-232 (10 pages)

Yong-Mun Choi, in Jung Jun Yeon, Hwang Seung Min, Kim Hyeonsu Jeong, Bon-Cheol Ku, Munju Goh 저
...
- 3,000원
This review presents current progress in the preparation methods of liquid crystalline nanocarbon materials and the liquid crystalline spinning method for producing nano-carbon fibers. In particular, we focus on the fabrication of liquid crystalline carbon nanotubes by spinning from superacids, and the continuous production of macroscopic fiber from liquid crystalline graphene oxide.
230.

Influence of defective sites in Pt/C catalysts on the anode of direct methanol fuel cell and their role in CO poisoning: a first-principles study

Soonchul Kwon, Seung Geol Lee 한국탄소학회 Carbon Letters 5 Pages

한국탄소학회 Carbon Letters 2015, Vol.16 No.3 6 198-202 (5 pages)

Soonchul Kwon, Seung Geol Lee 저
...
- 1,500원
Carbon-supported Pt catalyst systems containing defect adsorption sites on the anode of direct methanol fuel cells were investigated, to elucidate the mechanisms of H2 dissociation and carbon monoxide (CO) poisoning. Density functional theory calculations were carried out to determine the effect of defect sites located neighboring to or distant from the Pt catalyst on H2 and CO adsorption properties, based on electronic properties such as adsorption energy and electronic band gap. Interestingly,...

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