• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.806-812
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• 2008

The ammonia decomposition reaction has been of increasing interest as a means of treating ammonia in flue gas in the presence of precious metal catalyst. Various catalysts, $Pt-Rh/Al_2O_3$, $Pt-Rh/TiO_2$, $Pt-Rh/ZrO_2$, $Pt-Pd/Al_2O_3$, $Pd-Rh/Al_2O_3$, $Pd-Rh/TiO_2$, $Pd-Rh/ZrO_2$, $Pt-Pd-Rh/Al_2O_3$, $Pd/Ga-Al_2O_3$, $Rh/Ga-Al_2O_3$, and Ru/Ga-$Al_2O_3$, were synthesized by using excess wet impregnation method. Using a homemade 1/4" reactor at $10,000{\sim}50,000hr^{-1}$ of space velocity in the presence of precious metal catalyst ammonia decomposition reactions were carried out to investigate the catalyst activity. The inlet ammonia concentration was maintained at 2,000 ppm, with an air balance. Both $T_{50}$ and $T_{90}$, defined as the temperatures where 50% and 90% of ammonia, respectively, are converted, decreased significantly when alumina-supported catalysts were applied. In terms of catalytic performance on the ammonia conversion in the presence of hydrogen sulfide, $Pt-Rh/Al_2O_3$ catalyst showed no effect on the poisoning caused by hydrogen sulfide. These results indicate that platinum-rhodium bimetallic catalyst is a useful catalyst for ammonia decomposition.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.3 no.1
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• pp.73-83
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• 1992

The purpose of this study was to undrstand the emotional and behavioral sequela in the abused child caused by phygical abuse. To achieve the purpose. the emotional and behavioral differences between not or less abused children group and severely abused children group were compared in this study. The subjects in this study were 61 male children who were selected among children under custody at 4 child-welfare institutions in Seoul. A violence scale in CTS(Conflict Tactics Scale) developed by Straus(1979) was modified and used as a research tool to measure the children's physical abuse. The Korean text of Child Behavior Checklist(CBCL) was also used to measure the emotional and behavioral problems of abused children. The results of this study were as follows : 1) The total scores of behavioral problems in physically abused children were significantly higher than those in control group. 2) The comparison of behavioral problems has shown significant differences between two groups in social withrawal. somatic symptom, emotional disturbance, obsessive-depressive behavior, hyperactivity and psychotic-sexual factors. However. there were no differences in aggressive and delinquent factors. The above results presents us the profile of children's emotional and behavioral problems caused by physical abuse, and can be used as a framework for the treatment protection and preservation of abused children in the course of social work practice.

• Restorative Dentistry and Endodontics
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• v.34 no.2
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• pp.113-119
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• 2009

The purpose of this study was to compare the tensile bond strength of several self-adhesive resin cements bonded to dentin surfaces with different wet conditions. Three self-adhesive resin cements: Rely-X Unicem (3M ESPE, St. Paul, MN. USA). Embrace Wetbond (Pulpdent. Oakland. MA. USA). Maxcem (Kerr. Orange. CA. USA) were used. Extracted sixty human molars were used. Each self-adhesive resin cement was adhered to the dentin specimens (two rectangular sticks from each molar) in different wet conditions. Tensile bond strength were measured using universal testing machine (EZ Test. Shimadzu corporation. Kyoto. Japan) at a crosshead speed of 1.0mm/min. After the testing. bonding failures of specimens were observed by Operative microscope (OPMI pro, Carl Zeiss. Oberkochen, Germany). T-test was used to evaluate the effect of dentin surface wetness. One-way ANOVA test was used to evaluate the tensile bond strength of self-adhesive resin cements in the same condition. Scheffe's test was used for statistical analyzing at the 95% level of confidence. The result showed that wetness of dentin surface didn't affect tensile bond strength of self-adhesive resin cements and Maxcem showed the lowest tensile bond strength.

• Journal of the Korean Society for information Management
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• v.38 no.4
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• pp.231-250
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• 2021

Despite the increasing number of international students in Korea, there is a lack of research on the health information-seeking behavior of international students. This study examined the health information search behavior of international students in Korea through a questionnaires and in-depth interviews adopting Critical Incident Technique. Most frequent health information needs that the participants experienced were related to Covid-19 and locating doctors/hospitals. The difficulties in seeking health information were language barriers, lack of knowledge of the Korean medical system, insufficient or overflowing information on the Internet. However, despite the language barrier, international students mainly used Korean sources (friends/family, websites, social media) for searching health information. In order to search health information on Korean websites, they used Google Translator or got help from bilingual friends/family members. The participants who have lived in Korea for a shorter period of time or who have lower Korean language proficiency tend to obtain health information through the community on social networks; whereas the longer the period of residence in Korea and the better the Korean language proficiency, the more likely to use websites. Only 28% of the participants gave positive answers to the question asking their confidence in finding the health information they needed. It is discussed how to help international students find accurate and credible health information.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.4
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• pp.535-541
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• 2010

Excessive intake of sodium is known as a risk factor for hypertension, and Korean adults consume sodium 3 times higher than Dietary Reference Intakes (DRIs). The purpose of this study was to evaluate the difference on sodium content between analyzed and estimated by food composition table and food exchange list. Seven days of low salt diet and seven days of high salt diet were prepared, and sodium contents were estimated by food composition table and food exchange list and measured by atomic absorption spectrophotometer. Sodium contents of diet per day estimated by food exchange list significantly differed from analyzed content, but those estimated by food composition table were not. However, when absolute differences from analyzed content were compared by dishes in the low and high salt diet periods, there were significant differences among estimated sodium content by food composition table and food exchange list and analyzed sodium content. The discrepancy between those results was due to that absolute value was used to compare sodium contents of dishes but not to compare sodium contents of days. In addition, main dish, side dish, and soup were significantly different among estimated sodium content by food composition table and food exchange list and analyzed sodium content. Actual sodium contents of Jap-Chae Deop-Bap and Roasted chicken with oyster sauce differed to a great extent from estimated contents by food exchange list and food composition table. In conclusion, actual sodium contents of Korean dishes were significantly different from those estimated by food composition table and food exchange list, and thus these differences in salt content should be considered on planning of low-salt menu for hypertensive patients.

• Korean Chemical Engineering Research
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• v.47 no.5
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• pp.630-638
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• 2009

A computational fluid dynamics(CFD) model is developed and validated with on-site experiments for a urea-based SNCR(selective non-catalytic reduction) process to reduce the nitrogen oxides($NO_x$) in a municipal incinerator. The three-dimensional turbulent reacting flow CFD model having a seven global reaction mechanism under the condition of low CO concentration and 12% excess air and droplet evaporation is used for fluid dynamics simulation of the SNCR process installed in the incinerator. In this SNCR process, urea solution and atomizing air were injected into the secondary combustor, using one front nozzle and two side nozzles. The exit temperature($980^{\circ}C$) of simulation has the same value as in situ experiment one. The $NO_x$ reduction efficiencies of 57% and 59% are obtained from the experiment and CFD simulation, respectively at NSR=1.8(normalized stoichiometric ratio) for the equal flow rate ratio from the three nozzles. It is observed in the CFD simulations with varying the flowrate ratio of the three nozzles that the injection of a two times larger front nozzle flowrate than the side nozzle flowrate produces 8% higher $NO_x$ reduction efficiency than the injection of the equal ratio flowrate in each nozzle.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.4
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• pp.405-412
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• 2012

In the MCFC power generation system, the combustor supplies a high temperature mixture of gases to the cathode and heat to the reformer by using the off-gas from the anode; the off-gas includes high concentrations of $H_2O$ and $CO_2$. Since a combustor needs to be operated in a very lean condition and avoid local heating, a catalytic combustor is usually adopted. Catalytic combustion is also generally accepted as one of the environmentally preferred alternatives for generation of heat and power from fossil fuels because of its complete combustion and low emissions of pollutants such as CO, UHC, and $NO_x$. In this study, experiments were conducted on catalytic combustion behavior in the presence of Pd-based catalysts for the BOP (Balance Of Plant) of 5 kW MCFC (Molten Carbonate Fuel Cell) power generation systems. Extensive investigations were carried out on the catalyst performance with the gaseous $CH_4$ fuel by changing such various parameters as $H_2$ addition, inlet temperature, excess air ratio, space velocity, catalyst type, and start-up schedule of the pilot system adopted in the BOP.

• The Journal of the Korea Contents Association
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• v.20 no.11
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• pp.603-614
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• 2020

The purpose of this study was to classify latent profiles based on SNS addictive tendencies of married women and to examine the effects of age, adult attachment, extrinsic motivation of the fear of missing out and marriage satisfaction. A total of 300 married women who have been using SNS participated in this study. The result indicated that there were three latent profiles for SNS addictive tendencies of married women : (1) high-risk group (2) potential-risk group (3) low-risk group. The high-risk group had high scores in all sub-areas (obsession and withdrawal symptoms, over-communication and immersion, over-consumption). The high-risk group accounted for 24.51% of the total and the potential-risk group was 44.33%, which had the highest proportion of them. While attachment anxiety, attachment avoidance, extrinsic motivation of the fear of missing out, and marriage satisfaction were significant determinants of latent profiles, age was not. This study divided groups according to the characteristics of married women's SNS addiction tendencies and provided implications for counseling and education according to group characteristics, and discussed the need for various research through the development of standardized SNS addiction scale for married women.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.5
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• pp.301-306
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• 2013

This research was conducted to investigate whether sequential anoxic/aerobic biofilm reactors and microfilteration (MF) membrane system can be used as a direct treatment for the removal of perchlorate and nitrate in groundwater. The biofilm process consisted of an anoxic first stage to remove perchlorate and nitrate and aerobic second stage to remove remaining acetate used as a carbon source for dissimilatory reduction of perchlorate and nitrate. In final stage, hollow fiber MF membrane was used to remove turbidity. In this research, perchlorate was reduced from the influent concentration of 102 ${\mu}/L$ to below the IC detection level (5 ${\mu}/L$) and nitrate was reduced from 61.8 mg/L (14 mg/L $NO_3$-N) to 4.4 mg/L (1 mg/L $NO_3$-N). Acetate used as a carbon source was consumed from 179 mg/L $CH_3COO-$ to 117 and 11 mg/L $CH_3COO^-$ in effluents from anoxic and aerobic biofilm reactors, respectively. Turbidity was reduced from 3.0 NTU to 1.5, 0.3, and 0.2 NTU in effluents from anoxic/aerobic biofilm reactors and MF membrane, respectively. It is expected that the sequential anoxic/aerobic biofilm reactors and MF membrane system can efficiently remove perchlorate and nitrate in surface water or groundwater.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.542-550
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• 2020

A stream serve the functions of different water utilization, flood control, and the environment, and contributes to the development of national life and culture. On the other hand, it is difficult to efficiently evaluate various projects, such as effectiveness verification and comparison between projects, because the evaluation procedures and evaluation techniques of projects are not uniform and different for each institution. Therefore, a standardization technology was developed for a post-assessment of stream projects that can recognize stream problems and comprehensively evaluate stream-related projects. To this end, various projects, such as project evaluation techniques, national R&D projects, and social welfare projects, were compared and analyzed, and the standardization stages of the project were first suggested. In addition, based on the standardization stage, the evaluation indices for each stage were derived to develop an evaluation table that can evaluate stream-related projects comprehensively. Finally, it is possible to prevent the repeated use of failure factors in the planned projects.