• Elastomers and Composites
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• 제57권1호
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• pp.1-8
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• 2022

In this study, the photo-deposition method was used to introduce Ag onto the surface of TiO₂ to synthesize an Ag-TiO₂ composite. The effects of the varying amounts of AgNO₃ precursor and annealing time periods on the Ag content in the composites, as well as their antibacterial characteristics under visible light conditions were studied. SEM analysis revealed the spherical morphology of the Ag-TiO₂ composite. Compared with TiO₂, the Ag particles were too small to be observed. An XPS analysis of the Ag-TiO₂ surface confirmed the Ag content and showed the peak intensities for elements such as Ag, Ti, O, C, and Si. The highest Ag content was observed when 33.3 wt.% of AgNO₃ and an annealing time of 6 h were employed; this was the optimum annealing time for Ti-Ag-O bonding, in that the lowest number of O bonds and the highest number of Ag bonds were confirmed by XPS analysis. Superior antibacterial properties against Bacillus and Escherichia coli, in addition to the widest inhibition zones were exhibited by the Ag-TiO₂ composite with an increased Ag content in a disk diffusion test, the bacterial reduction rate against Staphylococcus aureus and Escherichia coli being 99.9%.

• 한국작물학회지
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• 제43권1호
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• pp.28-31
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• 1998

Nodule development was regulated partially by host plant factors originating in the shoots and roots. This study was performed to identify the origin of the factors regulating nodulation in supernodulating soybean (Glycine max [L.] Merr.) mutant 'SS2-2' which was isolated recently from ethyl methanesulfonate (EMS) mutagenesis of 'Sinpaldalkong 2'. Self- and reciprocal-grafts were made among three soybean genotypes which consisted of two supernodulating mutants, SS2-2 and 'nts 382', and a normal nodulating Sinpaldalkong 2. Self-grafted supernodulating mutants were characterized by greater nodule number, nodule dry weight, and $C_2$H$_2$ reduction activity than self-grafted wild types. They were also characterized by relatively higher nodule to root dry weight. Significant shoot genotypic effects were observed on nodule number, nodule dry weight, and $C_2\;H_2$ reduction activity per plant, whereas varying root genotypes had no effects. From this result, it is surmised that supernodulating characters are controlled by a graft-transmissible shoot factor, and mutant SS2-2 may have similar nodulation mechanism to the former supernodulating nts 382. In all grafts, both supernodulating mutants and Sinpaldalkong 2 maintained the similar balance between above ground and below ground parts regardless of significant differences in partitioning of dry matter into root and nodule between supernodulating mutants and Sinpaldalkong 2.

• 대한간호학회지
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• 제2권1호
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• pp.237-246
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• 1971

The purpose of this study is to observe the effects of ice-pack application on different body areas and to note which body area produces the best results according to age, room temperature, sex and disease. Seventeen patients, including six men and eleven women, hospitalized at Seoul National University Hospital from May 22 to August 29, 1971, ranging in age from 15 through 60 years with an oral temperature of 38℃ or over, were chosen for this study. They were observed with regard to the effect of the ice-packs after applications for 30, 45 or 60 minutes. Four ice-packs, 7.6inch by 9 inch, were applied on the chest and the abdominal surface in the control group and the same size and number of packs on the axillae and political regions in the experimental group. The study results were reviewed in a statistical method to obtain the following findings 1. There was no significant difference in the change of the body temperature between the control group and the experimental group after applying the packs for 30, 45 or 60 minutes. 2. Individually, there was a significant difference in the change of body temperature between before and after application for 30, 45 or 60 minutes. 3. The difference of room temperature also had no merle influence on the body temperature taken immediately before applying the ice-packs. Even when ice-packs were applied for 30, 45 or 60 minutes, the room temperature did not influence the reduction of temperature in the patient. 4. There was a significant difference in the change of the body temperature, according to the sex, after application for 30, 45 or 60 minutes. Male patient's body temperature decreased far more noticeably than the female patients and the degree of reduction became more pronounced the longer the packs were applied. 5. In regard to age, in adults, the degree of reduction in the body temperature by the application of ice-packs was similar after appling them for 30, 45 or 60 minutes and did not depend upon the length of application. 6. Regardless of the disease, there was no great difference in the reduction of body temperature when the ice-packs were applied for 30 or 45 minutes, except for patients with typhoid fever when a striking decrease in the fever resulted after a 60 minute application of the ice-pack.

• 한국재료학회지
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• 제23권11호
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• pp.631-637
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• 2013

Synthesis of sub-micron $2SnO{\cdot}(H_2O)$ powders by chemical reduction process was performed at room temperature as function of viscosity of methanol solution and molecular weight of PVP (polyvinylpyrrolidone). Tin(II) 2-ethylhexanoate and sodium borohydride were used as the tin precursor and the reducing agent, respectively. Simultaneous calcination and sintering processes were additionally performed by heating the $2SnO{\cdot}(H_2O)$ powders. In the synthesis of the $2SnO{\cdot}(H_2O)$ powders, it was possible to control the powder size using different combinations of the methanol solution viscosity and the PVP molecular weight. The molecular weight of PVP particularly influenced the size of the synthesized $2SnO{\cdot}(H_2O)$ powders. A holding time of 1 hr in air at $500^{\circ}C$ sufficiently transformed the $2SnO{\cdot}(H_2O)$ into $SnO_2$ phase; however, most of the PVP (molecular weight: 1,300,000) surface-capped powders decomposed and was removed after heating for 1 h at $700^{\circ}C$. Hence, heating for 1 h at $500^{\circ}C$ made a porous $SnO_2$ film containing residual PVP, whereas dense $SnO_2$ films with no significant amount of PVP formed after heating for 1 h at $700^{\circ}C$.

• 구강회복응용과학지
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• 제20권1호
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• pp.19-29
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• 2004

The purpose of this study was to compare the fracture strength of the IPS Empress ceramic crown according to the incisal reduction(2.0mm, 2.5mm, 3.0mm) and axial inclination ($4^{\circ}$, $8^{\circ}$, $12^{\circ}$) of the lower canine. After 10 metal dies were made for each group, the IPS Empress ceramic crowns were fabricated and each crown was cemented on each metal die with resin cement. The cemented crowns mounted on the testing jig were inclined 30 degrees and a universal testing machine was used to measure the fracture strength. The results of this study were as follows : 1. The fracture strength of the ceramic crown with 3.0mm depth and $12^{\circ}$ inclination was the highest(1377N). Crowns of 2.0mm depth and $4^{\circ}$ inclination had the lowest strength (731 N). 2. There were no significant differences of the fracture strength by axial inclination in same incisal reduction group. 3. The fracture mode of the crowns was similar. Most of fracture lines began at the loading area and extended through proximal surface perpendicular to the margin irrespective of incisal reduction.

• 동아시아식생활학회지
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• 제22권6호
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• pp.734-743
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• 2012

High sodium consumption is a significant nutrition problem in South Korea; however, few studies have examined the awareness and practice of dietitians with respect to low sodium diet in schools. In this study, we collected data from 211 dietitians in 2012. Most respondents indicated that sodium reduction was important in school meals (very important 40.5%, somewhat important 55.6%); however, they rarely checked the sodium content in the nutrition labels of processed foods (never/rarely 74.2%, sometimes 18.7%, always/often 7.2%). The main reason for not checking the sodium content was 'no nutrition table on some processed foods' (38.5%). The most important barrier to sodium reduction in school meals was overcoming the negative taste of students related to a reduced-sodium diet (70.4%). The most frequently used processed foods were processed meat (e.g. ham, bacon) (48.3%), frozen dumplings and noodles (33.8%), and sausage and dressing (14.5%) in school meals. The proportion of dietitians who used processed food ${\geq}$ 2 times per week for the school menu was 72.2% in high school, 28.4% in middle school and 12.4% in elementary school (p<0.05). Upon ranking of the importance of nutrients in school menus, calories received the highest score (4.35 points), followed by macronutrient ratios (4.30), calcium (4.06), iron (3.44) and sodium (3.20). Although most dietitians recognized that sodium reduction was important in school menu planning, they had poor dietary practices. It is suggested that we educate dietitians as well as students about the importance and practice of a reduced sodium diet. Furthermore, it is critical to develop diverse low sodium recipes and have a required nutrition labeling system for all processed foods. Overall, the results of this study could serve as a guide to planning effective nutrition programs to reduce sodium consumption in school feeding programs.

• 한국안전학회지
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• 제36권5호
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• pp.10-17
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• 2021

The controversy over the risk of the human body being affected by electromagnetic fields emitted from 60 Hz power lines continues without end. There are currently no new studies or research progress being made in this direction that is notable, and the number of civil complaints is gradually increasing. The problem is that each study produces different results, among which the effect of exposure to magnetic fields on childhood leukemia is a major one. In Korea, an electrician who was maintaining a 22.9 kV power line died of leukemia, which has recently been recognized as an occupational disease. Methods to reduce magnetic fields from power lines include shielding with wire loops, incorporating split phases and compaction techniques, installing underground power lines, converting to high-voltage direct current (HVDC), and increasing the ground clearance of transmission towers. Depending on whether a separate power supply is needed or not, there are two types of wire loops: passive loop and active loop. Magnetic field reduction is currently done through underground power lines; however, the disadvantage of this process is high construction costs. Installing passive loops, with relatively low construction costs, leads to lower magnetic field reduction rates than installing underground cables and a weakness to not solving the landscape problem. This methodological study aims at designing methods and reducing the effects of 2-wire set loops-the simplest and most practical. Since the method proposed in this study has been designed after analyzing the distribution of complex electromagnetic fields near the expected loop installation location, a practical design can be implemented without the need for any difficult optimization programming.

• 한국재료학회지
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• 제12권12호
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• pp.930-934
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• 2002

Nanosized $WO_3$ powders were synthesized by the sol-precipitation process using $WCl_{6}$ as the starting material, ethanol as a solvent and $NH_4$OH solution as a precipitant, followed by a washing-drying treatment and calcination. The effects on the powder crystallinity and microstructure of calcination temperature were investigated with XRD and FE-SEM. The $WO_3$ powders calcined at $500^{\circ}C$ and $700^{\circ}C$ showed good crystallinity and their mean particle size was 30nm and 70nm, respectively. These powders were used for the preparation of pastes which were printed as thick films on alumina substrates with comb-type Pt electrodes. The particle size strongly influenced the $NO_2$ gas sensing property of the thick films. A significant reduction in the $NO_2$ sensitivity was observed for the film prepared from larger particle size, having thus a larger grain size. For the film having a smaller grain size, on the other hand, the higher $NO_2$ sensitivity was observed and the sensitivity increased with $NO_2$ concentration.

• Biomolecules & Therapeutics
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• 제10권4호
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• pp.224-229
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• 2002

Triazine herbicide has been reported to directly suppress the immune response. In the present study, we examined various functions of murine peritoneal macrophages that were isolated and stimulated with LPS after simazine (300 and 600 mg/kg body weight), a triazine herbicide, was administered every day for 4 weeks. Simazine decreased the capacity of phagocytosis, compared to those of carboxymethylcellulose (CMC)-treated control group. In addition, the production of NO and TNF-$\alpha$ was decrcased in macrophages of simazinetreated mice. However, the production of hydrogen peroxide ($H_{2}O_{2}$) was not altered. In vitro tumoricidal activity of in vivo simazine-treated macrophages was reduced against target cell. B 16 melanoma. Taken together, these results suggested that simazine might have the immunosuppressive effect on macrophages after in vivo exposure, which was related to the reduction of tumoricidal activity.

• Bulletin of the Korean Chemical Society
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• 제4권1호
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• pp.3-9
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• 1983

Lithium n-butylborohydride was prepared from borane-dimethylsulfide (BMS) and n-butyllithium, and the approximate rates and stoichiometrics of its reactions with selected organic compounds containing representative functional groups were studied in THF at room temperature. Phenol and benzenetiol liberated hydrogen quickly and quantitatively, and the reactions of primary alcohols, 2,6-di-ter-butylphenol and 1-hexanethiol liberated hydrogen quantitatively within 3 hrs, whereas the reactions of secondary and tertiary alcohols were very slow. Aldehydes and ketones were reduced rapidly and quantitatively to the corresponding alcohols. Cinnamaldehyde utilized 1 equiv. of hydride rapidly, suggesting the reduction to cinnamyl alcohol. Carboxylic acids evolved 1 equiv. of hydrogen rapidly and further reduction was not observed. Anhydrides utilized 2 equiv. of hydride rapidly but further hydride uptake was very slow, showing a half reduction. Acid chlorides were reduced to the alcohol stage very rapidly. All the esters examined were reduced to the corresponding alcohol rapidly. Lactones were also reduced rapidly. Expoxides took up 1 equiv. of hydride at a moderate rate to be reduced to the corresponding alcohols. Nitriles and primary amides were inert to this hydride system, whereas tertiary amide underwent slow reduction. Nitroethane and nitrobenzene were reduced slowly, however azobenzene and azoxybenzene were quite inert. Cyclohexanone oxime evolved 1 equiv. of hydrogen rapidly, but no further reduction was observed. Phenyl isocyanate and pyridine N-oxide were proceeded slowly, showing 1.74 and 1.53 hydride uptake, respectively in 24 hours. Diphenyl disulfide was reduced rapidly, whereas di-n-butyl disulfide, sulfone and sulfonic acids were inert or sluggish. n-Hexyl iodide and benzyl bromide reacted rapidly, but n-octyl bromide, n-octyl chloride, and benzyl chloride reacted very slowly.