• Journal of the Korean Ceramic Society
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• v.33 no.12
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• pp.1387-1393
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• 1996

A study on mesophase pitch as a matrix precursor of carbon fiber reinforced carbon (C/C) composite has been recently presented. This study is concerned with the production of mesophase pitch as matrix precursors for C/C composite from coal tar pitch. A commercial coal tar pitch was heat-treated at 25$0^{\circ}C$ for 2 hours to remove low molecular weight fraction from the pitch then increasing the temperature of the pitch to between 350~45$0^{\circ}C$ to produce mesophase pitch. The pitch was continuously stirred during this time and nitrogen gas was continuously bubbled through the pitch. Spherical and bulk mesophases were formed in the pitch after heat-treatment,. Parent and mesophae pitches were characterized by elemental analysis coke yield solubi-lity in tetrahydrofuran and hexane and an optical microscopy to measure the mesiophase content. It was neces-sary to produce C/C composite that a mesophase pitch with about 30-40 vol% mesophase spherulites can be infiltrated into a fiber preform without a filter effect as a matrix precursor conditions. This condition was satisfied with mesophase pitch heat treated at 40$0^{\circ}C$ for 2 hours. The other heat treatment conditions showed the nuclei of mesophase or bulk mesophae which were not satisfied with the matix precursor condition.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.7
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• pp.370-378
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• 2002

As resent trends in structural construction have been to build taller and larger structures than any time in the past, they have had high flexibility and low damping that can cause large vibration response under severe environmental loading such as earthquakes, winds, and mechanical excitations. The damper with mass and spring is one approach to safeguarding the structure against excessive vibrations. In this paper, the lumped electrical circuit approach of mass/spring system is used to model the mechanical aspects according to the frequency. Therefore, the mass/spring system can be dealt with here and linked with the equivalent circuit of electric linear oscillatory actuator(LOA). Analysis models are two types of vibration control system, active mass damper(AMD) and hybrid mass damper(HMD). AMD consists of the moving coil LOA with mass only The LOA of HMD with mass and spring is composed of the fixed coil and the movable permanent magnet(PM) field part. The PM field part composed magnet modules and iron coke, is the damper marts itself. We Present the motional resistance and reactance of mass/spring system and the system impedance of AMD and HMD according to the frequency.

• Korean journal of food and cookery science
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• v.6 no.2
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• pp.105-119
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• 1990

A study on the dietary habit and the food perference of Pre-school Children was made in order to identify the state of their dietary life and provide the data of dietetic education which can help the children to live a desirable food life, by analysing the present dietry life into the dietry habits, food preference, the actual condition of nutrition intake and table manners. 1. The Diet Habits. Both boys and girls were fond of dinner best and tended to neglect breakfast and lunch. 64.2% of the total children took meals regularly. 2. Food Preference. The most favorite food was beef, ham, Dupoo (beancurd), squid, ice-cream, bananas, watermelon, sweet potatoes, corn, Ingeolmi (cake form glutinous rice), doughnuts, JJajangmyon (Chinese noodles), Coke, fried chicken. 3. The Actual Conditions of Nutrition Intake. The frequency of intake of meat and its processed food was the lowest and that of fishes, shellfishes, fats and vegetables was low, too. 4. Table manners and Sanitary Conditions. The average mark of table manners and sanitary conditions is 12.49${\pm}$2.65. The children didn't practice well in the following points; talking at table, beginning to eat after the beginning of elder person's, brushing their teeth after taking meals, keeping a straight posture.

• Clean Technology
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• v.23 no.3
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• pp.314-324
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• 2017

To verify the viability of Co, Ru and Zr-based catalyst for $CO_2$ (dry) reforming reaction, catalysts were fabricated using cordierite, silicon carbide and rota monolithic substrates, and they were compared with the conventional $Co-Ru-Zr/SiO_2$ catalyst in terms of performance and durability. Cordierite monolith was showed high activity with the least amount of active component. In addition, when Cordierite monolith was coated with Co-Ru-Zr in various ways, most excellent performance was showed at a precursor solution coating method. In particular, when 0.9 wt% Co-Ru-Zr/Cordierite was used for reaction, it was observed that 95% $CO_2$ conversion was maintained for 300 h at $900^{\circ}C$.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.27 no.3
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• pp.21-25
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• 2004

In today's mass production/consumption society, there are many important constituents people need to have/do for their happy life. Very few People think that among those components enjoying Pro-sports in their life is essential, and Many business companies are interested in owning/operating pro-sports teams. Thus, many studies have been progressed on sports management or sports marketing domestically and abroad. This paper studied the preference relationship between subject's majors and products/service and pro-sports. We constructed hypotheses about the relationship and tested them by using ANOVA and Tuckey tests. We found significant results that preference for coke/cider is influenced by subject's majors, and that preference for pro-baseball, pro-football, and pro-basketball is also influenced by subject's major, etc. As the results, we can have important information about who are the most important customers and who should be target customers for marketing and promotion, and with the information related business companies can attain higher profitability and less loss through more effective sports marketing.

• Applied Chemistry for Engineering
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• v.24 no.3
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• pp.239-246
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• 2013

Principle of foamed glass manufacturing process first starts with putting vitreous material powder into a mold. After the foaming calcination, foamed body should be annealed after separation from the mold. For this reason, existing manufacturing process could not be a continuous type process. In this study, in order to develop a continuous production process of foamed glass, the possibility of new foam glass manufacturing process was investigated by foaming calcination of the compact body obtained from compression-molding of vitreous raw materials in stead of using a mold. Through the experimental results of the foaming calcination of the compact body with adding various foaming agents such as $Na_2CO_3$, $CaCO_3$ and petroleum coke, into hydrated soda-lime vitreous raw materials, it was shown that developing a continuous process without using any molds for manufacturing foamed glass would be possible.

• Korean Chemical Engineering Research
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• v.44 no.4
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• pp.345-349
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• 2006

Conversion of DME (dimethyl ether) or methanol to light olefins (ethylene, propylene, butenes) over SAPO-34 were systematically studied, where it was observed that DME was dehydrated to light olefins and partially converted to by-products such as CO and $CO_2$ at various reaction temperatures on the time-on-stream. SAPO-34 catalyst during the DTO (dimetyl ether-to-olefins) reaction was significantly deactivated compared with MTO (methanol-toolefins) reaction. By addition of water to the reaction feed, the yield to light olefins was not only increased, but the life time of the catalyst was also prolonged by the suppression of the coke formation by steam.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.267-267
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• 2012

$TiO_2$-Ni inverse catalysts were prepared using atomic layer deposition (ALD) process and catalytic $CO_2$ reforming of methane (CRM) reaction over catalysts (either bare Ni or $TiO_2$ coated-Ni particles) were performed using a continuous flow reactor at $800^{\circ}C$. $TiO_2$-Ni inverse catalyst showed higher catalytic reactivity at initial stage of CRM reactions at $800^{\circ}C$ comparing to bare Ni catalysts. Moreover, catalytic activity of $TiO_2$/Ni catalyst was kept high during 13 hrs of the CRM reactions at $800^{\circ}C$, whereas deactivation of bare Ni surface was started within 1hr under same conditions. The results of surface analysis using SEM, XPS, and Raman showed that deposition of graphitic carbon was effectively suppressed in a presence of $TiO_2$ nanoparticles on Ni surface, thereby improving catalytic reactivity and stability of $TiO_2$/Ni catalytic systems. We suggest that utilizing decoration effect of metal catalyst with oxide nanoaprticles is of great potential to develop metal-based catalysts with high stability and reactivity.

• Journal of the Korean Ceramic Society
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• v.54 no.2
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• pp.128-136
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• 2017

Fly ash from a circulating fluidized bed combustion boiler (CFBC fly ash) is very different in mineralogical composition, chemical composition, and morphology from coal ash from traditional pulverized fuel firing because of many differences in their combustion processes. The main minerals of CFBC fly ash are lime and anhydrous gypsum; however, due to the fuel type, the strength development of CFBC fly ash is affected by minor components of active $SiO_2$ and $Al_2O_3$. The initial hydration product of the circulating fluidized bed combustion fly ash (B CFBC ash) using petro coke as a fuel is Portlandite which becomes gypsum after 7 days. Due to the structural features of the portlandite and gypsum, the self-cementitious strength of B CFBC ash was low. While the hydration products of the circulating fluidized bed combustion fly ash (A CFBC ash) using bituminous coal as a fuel were initially portlandite and ettringite, after 7 days the hydration products were gypsum and C-S-H. Due to the structural features of ettringite and C-S-H, A CFBC ash showed a certain degree of self-cementitious strength.

• International Journal of Advanced Culture Technology
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• v.3 no.1
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• pp.31-38
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• 2015

Coking accumulations via dry methane reforming (DMR) over 10NAM monolithic catalyst and pelletized catalyst was investigated. 10NAM catalyst was synthesized and coated on a wall of monolithic reactor. Pelletized catalyst of 10NAM was also prepared for the comparison. Consequently, catalyst was characterized by BET, $H_2-TPR$ and $H_2-TPD$. The catalytic reaction was undergone at $600^{\circ}C$ under atmospheric pressure and $CH_4$ to $CO_2$ reactant ratio of 1:2. The coking formation over spent catalyst was then carried out in the hydrogen flow using temperature programmed technique (TPH). According to the results, DMR over 10NAM monolithic catalyst exhibits a minimized coking formation comparing to the use of pelletized catalyst. This could be attributed to a prominent heat transfer efficiency of the monolithic catalyst.