• Journal of the Speleological Society of Korea
• /
• no.73
• /
• pp.1-8
• /
• 2006

Optimization of the biphenile chloromethylation process with paraphormaldegide has been done in the presence of $ZnCl_2$ with HCl gas by the Box-Wilson method of mathematical planning of experiment. The 4,4'-(dichloromethyl)-biphenile yield dependence on the piphenile -paraphormaldegide ratio, temperature and reaction duration has been studied. A mathematical model of the process has been developed and optimal conditions for the biphenile chloromethylation procedure has been determined.

• Bulletin of the Korean Chemical Society
• /
• v.7 no.4
• /
• pp.293-296
• /
• 1986

The Hugoniot adiabatics and viscosity of shock compressed water have been calculated by applying the significant structure theory of water. To consider the effects of pressure and temperature, the sublimation energy has been expressed by the spherically averaged Stillinger-Rahman ST2 potential. Good agreements between theory and experiment are obtained in the whole extreme ranges of shock wave condition up to 100 GPa (lMbar).

• Journal of the Korean Chemical Society
• /
• v.65 no.5
• /
• pp.333-346
• /
• 2021

In this study, we developed education materials using history of science related to the experiment of 'Boyle's air pump' and the Boyle and Hobbs' debate of vacuum to find out the perceptions of NOS by pre-service chemistry teachers. For the study, 29 pre-service chemistry teachers at a college of education in Chungcheongbuk-do were selected. As RFN items that were related to the contextual situation developed in this study, items in the categories of 'Aims and Values', 'Scientific practices', 'Scientific Methods among Educational Applications' and 'Social-Institutional Aspects among Educational Applications' were selected. Through the items of RFN, the perceptions of pre-service teachers in non-contextual situations were investigated. Then we presented the pre-service teachers with the situation related to Boyle's experiment on air pump and Boyle and Hobbes' debate over vacuum. In addition, their perception of NOS was examined in contextual situations related to RFN items. Responses to the items, experimental results related to Boyle's Law, group discussion, and interview data were collected as data. As a result of the study, it was found that pre-service teachers had informed perceptions in most of the items, but cases with naive views or mixed views were found in context experimental situations. This study can contribute to the NOS education for pre-service chemistry teachers by development of context situation education materials related to NOS and by finding out their perceptions in the non-contextual and contextual situation.

• Journal of Information Display
• /
• v.12 no.3
• /
• pp.135-139
• /
• 2011

This paper presents the directly obtained rotational viscosity values of E7, which includes pentylcyanobiphenol, heptylcyanobiphenol, 4-cyano-4'-n-octyloxy-1,1'-biphenyl, and 4-cyano-4"-n-pentyl-1,1',1"-terphenyl, at various tempe using molecular dynamics computer simulation. The director mean squared displacement was achieved from the squared displacement of the mean director using the concept of the mean director of various nematic liquid crystals. The calculated values were compared with the experiment results that predicted a good agreement. Additional points that must be considered for further study are also discussed.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.347-347
• /
• 2010

We designed a new experimental set-up for measuring activity of heterogeneously catalyzed reactions. Using this set-up, we studied reduction of carbon dioxide by carbon dioxide reforming of methane (CRM) using nickel powder as catalyst. The properties of the catalysts were characterized by X-ray diffraction (XRD), Brunauer, Emmett & Teller (BET) surface area and X-ray photoelectron spectroscopy (XPS) techniques. The reactivity experiments were performed in the temperature range of $300\;-\;500^{\circ}C$. At reactivity experiment, result showed consumption of $CO_2$ and $CH_4$ with a 1:1 stoichiometry. At the same time, carbon monoxide and hydrogen were produced, which could be used for synthesizing fuels such as methanol. During the reaction, deposition of carbon on Ni was observed, which caused deactivation of the catalyst.

• Journal of the Korean Chemical Society
• /
• v.59 no.5
• /
• pp.434-444
• /
• 2015

Inquiry-based experiments provide opportunities to understand scientific knowledge and acquire nature of science. In this study, the difficulties which pre-service teachers experienced in inquiry-based experiment class were investigated and analyzed. Twenty-two pre-service teachers attended course designed as ‘ill-structured inquiry’ for 13 weeks, and researchers investigated their difficulties by questionnaires and interview. They showed difficulties mostly in designing experiment and interpretation and also in understanding inquiry purpose, lack of prior knowledge, confidence in inquiry performance, and understanding of experimental instruments and facilities. As a result, it is necessary to provide opportunities to engage in inquiries and environments to properly instruct pre-service teachers the inquiry ability in college of education.

• Journal of Applied Biological Chemistry
• /
• v.42 no.4
• /
• pp.175-179
• /
• 1999

Grape seed oil was extracted using different preparatory treatments as follows: (1) grinding, (2) grinding and roasting, (3) grinding and wet- roasting, (4) grinding, roasting, and wet-roasting, and (5) grinding, wet-roasting, and wet-roasting. The highest antioxidant activity was obtained from the sample with the method (2). Initial states of oxidation were similar except method (1) that showed more oxidized state, being P.O.V.8. Acid values were observed in the range from 1.42 to 1.89. The lowest acid value was found as 1.42 in method (1) and those of others were somewhat higher, indicating that heating process of roasting produced some free fatty acids. From the results of sensory evaluation, the best odor and taste were obtained from the methods (2) and (3). Repetitive procedure of wet-roasting, like method 5, caused some loss of flavor components and decrease in the sensory evaluation score. Addition of grape seed oil (method 2) to soybean and perilla oil at the level of 20% retained considerable antioxidant activities as much as 4.3 and 5 times, respectively, than 100% soybean or perilla oil stored for 12 weeks. When soybean or perilla oil was mixed with 20% grape seed oils, P.O.V. decreased to half of that of unmixed oils.

• Journal of Veterinary Clinics
• /
• v.25 no.5
• /
• pp.363-369
• /
• 2008

The aim of this study was to establish an experiment animal model for easy diagnosis and monitoring effect of treatment of cholelithiasis by cholesterol and mixed gall stone. In 12 adult beagle dogs, five dogs there were in the control group and seven dogs in the experiment group with ligated cystic duct. General clinical signs were recorded, CBC and blood chemistry were examined. Control group and experiment group were evaluated every 2 weeks for a period of 20 weeks. The results were (1) Total blirubin, cholesterol, alanine aminotransferase (ALT), aspartate aminotransferase (AST) activity were significantly higher in the experiment group with ligated cystic duct than control group during 2-8 weeks. (2) Total alkaline phosphatase (TALP) activity was significantly higher when compare with control group during 2-8 weeks. Bone alkaline phosphatase(BALP) activity was increased slightly between 2 and 8 weeks but was decreased between 10 and 20 weeks. (3) Blood urea nitrogen (BUN) was decreased between 2 and 8 weeks. After 10 weeks, this was in normal range. (4) On complate blood count (CBC), $Ca^{2+}$ and P were not changed until 20 weeks. (5) On clinical signs in experimental group, they observed a depression, yellow color of mucus membrane and conjunctiva, xanthinuria and xanthochromic. The present study showed that the experimental animal model with ligated cystic duct was a useful model to study biliary tract disease.

• Korean Journal of Agricultural Science
• /
• v.47 no.4
• /
• pp.1049-1056
• /
• 2020

Ultrafine dust causes asthma and respiratory and cardiovascular diseases when inhaled. Ammonia (NH3) plays a big role in ultrafine dust formation in the atmosphere by reacting with nitrogen oxides (NOx) and sulfur oxides (SOx) emitted from various sources. The agricultural sector is the single largest contributor of NH3, with the vast majority of emissions ensuing from fertilizers and livestock sector. Interest in using biochar to attenuate these NH3 emissions has grown. This experiment was conducted to study the effects of using rice hull biochar pyrolyzed at three different temperatures of 250℃ (BP 4.6, biochar pH 4.6), 350℃ (BP 6.8), and 450℃ (BP 10.3) on the emission of ammonia from soil fertilized with urea. The emissions of NH3 initially increased as the experiment progressed but decreased after peaking at the 84th hour. The amount of emitted NH3 was lower in soil with biochar amendments than in that without biochar. Emissions amongst biochar-amended soils were lowest for the BP 6.8 treatment, followed in an ascending order by BP 10.3 and BP 4.6. Since BP 6.8 biochar with neutral pH resulted in the lowest amount of NH3 emitted, it can be concluded that biochar's pH has an effect on the emissions of NH3. The results of this study, therefore, indicate that biochar can abate NH3 emissions and that a neutral pH biochar is more effective at reducing gaseous emissions than either alkaline or acidic biochar.

• Applied Biological Chemistry
• /
• v.44 no.3
• /
• pp.179-184
• /
• 2001

To investigate the effects of harvesting times on physicochemical and milling properties of rice, milling tests were performed applying laboratory milling systems. Milling and head rice yields were highest in rice harvested at the 45 days after heading at 76.49 and 94.43%, respectively. Milled rice grain harvested 45 days after heading showed the highest minimum viscosity, as shown in the amylogram curves, as well as the lowest consistency viscosity. Protein and amylose contents were highest in rice harvested at 35 days after heading, whereas the instrumental taste score was highest 45 days after heading.