• 한국지하수토양환경학회지:지하수토양환경
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• 제19권6호
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• pp.13-17
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• 2014

Subcritical water acts like an organic solvent at elevated temperature in terms of its physicochemical properties. Taking into account this advantage, the remediation experiments of benzo[a]pyrene contaminated soil (8.45 mg/kg of initial concentration) were conducted using subcritical water extraction apparatus. The effect of operating factors on the removal efficiency was studied at the varying the conditions of the water temperature ranging $200{\sim}300^{\circ}C$, extraction time 30~90 min, and flow rate 0.3~2.0 mL/min. 12 g of benzo[a]pyrene contaminated soil was inserted into the extraction cell and placed into the reactor and then the subcritical water was driven through the cell. In this study, the removal efficiency of benzo[a]pyrene was increased from 55.1 to 98.1% when the temperature increased from 200 to $300^{\circ}C$. The removal efficiency was decreased from 97.0 to 77.0% when the flow rate increased from 0.3 to 2.0 mL/min, suggesting that the extraction is limited by intra-particle diffusion. The 30 min reaction time was determined as an effective treatment time at $250^{\circ}C$. Based on the results, the optimum condition for the remediation of benzo[a]pyrene contaminated soil was suggested to be $250^{\circ}C$, 30 min, and 0.3 mL/min.

• 융합정보논문지
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• 제11권12호
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• pp.115-126
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• 2021

본 연구에서는 내외수 범람을 동시에 고려하여 침수해석을 수행하는 시뮬레이션 모형을 개발하였다. 외수 침수해석을 위해 제방 월류 및 파제에 의한 하천범람 유입량을 고려할 수 있도록 하였고, 내수 침수해석을 위해서 이중배수체계 개념을 반영하도록 구성하였다. 지표면 침수해석과 관련하여 하천의 유동해석과 제내지의 유동해석을 통합적으로 수행하기 위해 유한요소법(FEM)을 적용하여 침수확산 해석을 수행할 수 있도록 하였다. 모형의 검증을 위해 우선 개념모델에 대해서 적용하였고, 이어서 실제 유역에 대해서 적용하였다. 본 연구를 통해 홍수로 인한 피해를 줄이고 홍수 피해를 저감하기 위한 효과적인 대책을 마련하기 위해 활용될 수 있을 것으로 기대된다.

• 산업식품공학
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• 제14권2호
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• pp.173-182
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• 2010

A fiber fraction (Aloe cellulose), the by-product obtained from Aloe vera gel processing was freeze dried and investigated for in vitro glucose/ bile acid retarding effects of powdered sample (100 mesh) comparing with commercial $\alpha$-cellulose as a reference sample. We also examined the effectiveness of physiological functionality such as the antiobesity and anti-constipation on Sprague-Dawley (SD) rat. The Aloe cellulose powders during in vitro dialysis experiment for 2 hours exhibited the glucose and bile acid retarding index of 20.32-35.2% and 53.13-28.30%, respectively. Especially, freeze dried aloe cellulose showed the 2.5 and 1.2-6 times higher effect on in vitro glucose and bile acid retardation than those of $\alpha$-cellulose. These relatively good retarding effects on glucose and bile acid diffusion suggest a potential of preventing from diabetes and arteriosclerosis of some extent. Also, the results from animal experiments on SD rats fed a high-fat diet for 4 weeks suggested that Aloe cellulose might be used as a novel dietary fiber showing an effective anti-obesity and anti-constipation effect.

• 한국재료학회지
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• 제29권7호
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• pp.412-424
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• 2019

Global fitting functions for Fe-selective chlorination in ilmenite($FeTiO_2$) and successive chlorination of beneficiated $TiO_2$ are proposed and validated based on a comparison with experimental data collected from the literature. The Fe-selective chlorination reaction is expressed by the unreacted shrinking core model, which covers the diffusion-controlling step of chlorinated Fe gas that escapes through porous materials of beneficiated $TiO_2$ formed by Fe-selective chlorination, and the chemical reaction-controlling step of the surface reaction of unreacted solid ilmenite. The fitting function is applied for both chemical controlling steps of the unreacted shrinking core model. The validation shows that our fitting function is quite effective to fit with experimental data by minimum and maximum values of determination coefficients of $R^2$ as low as 0.9698 and 0.9988, respectively, for operating parameters such as temperature, $Cl_2$ pressure, carbon ratio and particle size that change comprehensively. The global fitting functions proposed in this study are expressed simply as exponential functions of chlorination rate(X) vs. time(t), and each of them are validated by a single equation for various reaction conditions. There is therefore a certain practical merit for the optimal process design and performance analysis for field engineers of chlorination reactions of ilmenite and $TiO_2$.

• Restorative Dentistry and Endodontics
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• 제44권1호
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• pp.8.1-8.7
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• 2019

Objectives: Irrigants are imperative in endodontic therapy for the elimination of pathogens from the infected root canal. The present study compared the antimicrobial efficacy of octenidine dihydrochloride (OCT) with chlorhexidine (CHX) and sodium hypochlorite (NaOCl) against Staphylococcus epidermidis (S. epidermidis) for root canal disinfection. Materials and Methods: The minimum inhibitory concentration (MIC) was obtained using serial dilution method. The agar diffusion method was then used to determine the zones of inhibition for each irrigant. Lastly, forty 6-mm dentin blocks were prepared from human mandibular premolars and inoculated with S. epidermidis. Samples were randomly divided into 4 groups of 10 blocks and irrigated for 3 minutes with saline (control), 2% CHX, 3% NaOCl, or 0.1% OCT. Dentin samples were then collected immediately for microbial analysis, including an analysis of colony-forming units (CFUs). Results: The MICs of each tested irrigant were 0.05% for CHX, 0.25% for NaOCl, and 0.0125% for OCT. All tested irrigants showed concentration-dependent increase in zones of inhibition, and 3% NaOCl showed the largest zone of inhibition amongst all tested irrigants (p < 0.05). There were no significant differences among the CFU measurements of 2% CHX, 3% NaOCl, and 0.1% OCT showing complete elimination of S. epidermidis in all samples. Conclusions: This study showed that OCT was comparable to or even more effective than CHX and NaOCl, demonstrating antimicrobial activity at low concentrations against S. epidermidis.

• 상하수도학회지
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• 제33권3호
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• pp.191-204
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• 2019

The 20-kHz ultrasonic irradiation was applied to investigate bacterial inactivation and antibiotic susceptibility changes over time. Applied intensities of ultrasound power were varied at 27.7 W and 39.1 W by changing the amplitude 20 to 40 to three bacteria species (Escherichia coli, Enterococcus faecalis, and Staphylococcus aureus). By 15-min irradiation, E. coli, a gram-negative bacterium, showed 1.2- to 1.6-log removals, while the gram-positive bacteria, Enterococcus faecalis and Staphylococcus aureus, showed below 0.5-log removal efficiencies. Antibiotic susceptibility of penicillin-family showed a dramatic increase at E. coli, but for other antibiotic families showed no significant changes in susceptibility. Gram-positive bacteria showed no significant differences in their antibiotic susceptibilities after ultrasound irradiation. Bacterial re-survival and antibiotic susceptibility changes were measured by incubating the ultrasound-irradiated samples. After 24-hour incubation, it was found that all of three bacteria were repropagated to the 2- to 3-log greater than the initial points, and antibiotic inhibition zones were reduced compared to ones of the initial points, meaning that antibiotic resistances were also recovered. Pearson correlations between bacterial inactivation and antibiotic susceptibility showed negative relation for gram-negative bacteria, E. coli., and no significant relations between bacterial re-survival and its inhibition zone. As a preliminary study, further researches are necessary to find practical and effective conditions to achieve bacteria inactivation.

• 한국게임학회 논문지
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• 제18권6호
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• pp.95-110
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• 2018

게임산업은 국내 문화산업을 대표할 만큼 성장했지만, 게임에 대한 사회문화적 위상은 산업 성장만큼 높지 않다. 2000년대 초반 청소년 게임이용의 역기능 문제는 사회적 이슈가 되면서 게임문화정책이 수립되어 15년간 추진되고 있다. 본 연구는 게임문화정책의 핵심 내용인 역기능 예방, 순기능 확산, 인식 개선을 중심으로 정책의 효과를 확인하고자 한다. 게임의 역기능 예방은 다소 효과가 있다고 할 수 있지만, 순기능 확산은 미흡하고 인식 개선은 부정적 경향이 더 많아졌다. 정책 실적에 비해 효과는 미흡하다. 게임문화정책의 효과를 확인할 수 있는 데이터가 부족하고, 효과도 미흡하다는 것은 향후 게임문화정책이 개선되어야 할 것이다. 기초 데이터의 확보, 정책의 사후관리, 문화 의미의 제고, 게임문화의 보편성 등에 대한 고려를 통해 게임문화정책의 방향성을 조정하는 것이 필요하다.

• 한국사이코드라마학회지
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• 제21권2호
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• pp.57-72
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• 2018

본 연구의 목적은 중학교 1학년을 대상으로 학교폭력예방 소시오드라마를 실시한 후 학교폭력인식의 효과와 만족도를 분석하는데 있다. 본 연구의 진행은 2018년 4월에 실시하였으며, 실험집단과 통제집단은 S시와 A시 중학교 1학년 각각 12명이다. 연구결과 실험집단의 학교폭력인식 수준은 사전검사 14.50, 사후검사 11.83, 평균 순위 9.33이었다. 통제집단의 학교폭력인식 수준은 사전검사 14.25, 사후검사 13.83, 평균 순위는 15.67이었다. 두 집단 간의 Mann-Whitney의 U 검정 결과 통계적으로 유의하게 나타나, 학교폭력예방 소시오드라마가 효과적이라고 볼 수 있다. 또한 실험집단의 소시오드라마 만족도는 전체 평균이 5점 만점 중 4.71로 매우 높게 나왔으며, 특히 '선생님의 수업진행'에 대한 만족도가 가장 높았다. 본 연구를 통해 중학생을 위한 학교폭력예방 소시오드라마의 보급과 확산을 기대한다.

• Journal of Dental Anesthesia and Pain Medicine
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• 제20권6호
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• pp.387-395
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• 2020

Background: The anterior-middle superior alveolar (AMSA) anesthetic technique has been reported to be a less traumatic alternative to several conventional nerve blocks and local infiltration for anesthesia of the maxillary teeth, their periodontium, and the palate. However, its anatomic basis remains controversial. The present study aimed to determine if the pattern of cortical and cancellous bone density in the maxillary premolar region can provide a rationale for the success of the AMSA anesthetic technique. Method: Cone-beam computed tomography scans of 66 maxillary quadrants from 34 patients (16 men and 18 women) were evaluated using a volumetric imaging software for cortical and cancellous bone densities in three interdental regions between the canine and first molar. Bone density was measured in Hounsfield units (HU) separately for the buccal cortical, palatal cortical, buccal cancellous, and palatal cancellous bones. Mean HU values were compared using the Mann-Whitney U test and one-way ANOVA with post-hoc analysis. Results: Cancellous bone density was significantly lower (P ≤ 0.001) in the palatal half than in the buccal half across all three interdental regions. However, there was no significant difference (P = 0.106) between the buccal and palatal cortical bone densities at the site of AMSA injection. No significant difference was observed between the two genders for any of the evaluated parameters. Conclusions: The palatal half of the cancellous bone had a significantly lower density than the buccal half, which could be a reason for the effective diffusion of the anesthetic solution following a palatal injection during the AMSA anesthetic technique.

• 한국미생물·생명공학회지
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• 제49권4호
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• pp.587-593
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• 2021

Infertility is a key issue affecting mood and behavior in men. Microorganisms are one of the primary etiological agents that may be associated with infertility. The objective of the present study was to identify bacterial causative agents from the semen of infertile subjects and determine the effect of bacterial infection on sperm quality, as well as determine the susceptibility of these bacteria to drugs. Forty semen samples from 30 infertile patients and 10 fertile individuals were collected. The pH, volume, motility, and concentration of semen were analyzed. The samples were processed and identified by biochemical testing using API identification kits. The antibiotic susceptibility pattern was determined using the disc diffusion method. Abnormal sperm quality was observed. The mean age of the individual and their sperm morphology, concentration, progressive motility, pH level, and pus cell content were 31.9 years, 2.7%, 10.4 million/ml, 27.3%, 8.3, and 5.7, respectively. Among the tested samples, oligoasthenozoospermia was found to show the highest occurrence, at 27/30 samples, followed by teratozoospermia, at 25/30 samples, and asthenozoospermia, at 22/30 samples. Of the tested infertile patients' sperm, 19, 6, and 5 isolates were identified as Escherichia coli, Klebsiella pneumonia, and Staphylococcus epidermidis, respectively. The results also revealed multi-drug resistance in the bacteria. Compared to that shown by the other tested antibiotics, amikacin showed higher activity against all isolated bacteria. However, the bacteria exhibited maximum resistance against gentamicin, cefotaxime, levofloxacin, and ampicillin. In conclusion, leukocytospermia and bacterial infections are possibly responsible for sperm abnormalities. Multi-drug resistant bacteria were detected. Gentamicin, cefotaxime, levofloxacin and ampicillin were shown the highest resistance, while amikacin was the most effective antimicrobial agent against the isolated bacteria.