• 한국지반신소재학회논문집
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• 제17권4호
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• pp.225-238
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• 2018

본 연구에서는 토목섬유 보강재의 시공중 손상 정도를 규명하기 위하여 국내에서 많이 사용되고 있는 주요 토목섬유 보강재 제품(7개 사의 15 종류)을 대상으로 다양한 입도의 성토재료를 적용한 현장내시공성시험을 수행하였다. 현장내시공성시험은 FHWA(2009) 지침을 참조하여 수행하였으며, 다짐시공 후 추출된 토목섬유 보강재 시료에서 인장강도 시편(크기 $0.2m{\times}1.4m$)을 최대 20개 이상 균등하게 샘플링하여 인장강도시험을 수행함으로써 시공에 따른 인장강도 감소 정도를 분석하였다. 분석 결과, 성토재료의 다짐시공으로 인한 토목섬유 보강재의 인장강도 감소 정도는 토목섬유 보강재의 종류와 성토재료의 최대입경에 크게 영향을 받으며, 비교적 강성이 작은 PET 결합형 지오그리드(PVC 코팅)의 인장강도 감소율이 가장 크게 나타났고, 전반적으로 성토재료의 최대입경이 클수록 인장강도 감소율은 더욱 크게 나타남을 알 수 있었다. 또한, 이 시험결과와 함께 기 수행된 현장내시공성시험 결과들을 분석하여 토목섬유 보강재의 시공성 감소계수를 보다 합리적으로 평가할 수 있는 방안을 제시하였다.

• 정보관리학회지
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• 제39권2호
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• pp.233-254
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• 2022

지적구조 분석을 위해 가중 네트워크를 시각화해야 하는 경우에 패스파인더 네트워크와 같은 링크 삭감 알고리즘이 널리 사용되고 있다. 이 연구에서는 네트워크 시각화를 위한 링크 삭감 알고리즘의 적합도를 측정하기 위한 지표로 NetRSQ를 제안하였다. NetRSQ는 개체간 연관성 데이터와 생성된 네트워크에서의 경로 길이 사이의 순위 상관도에 기반하여 네트워크의 적합도를 측정한다. NetRSQ의 타당성을 확인하기 위해서 몇 가지 네트워크 생성 방식에 대해 정성적으로 평가를 했었던 선행 연구의 데이터를 대상으로 시험적으로 NetRSQ를 측정해보았다. 그 결과 품질이 좋게 평가된 네트워크일수록 NetRSQ가 높게 측정됨을 확인하였다. 40가지 계량서지적 데이터에 대해서 4가지 링크 삭감 알고리즘을 적용한 결과에 대해서 NetRSQ로 품질을 측정하는 실험을 수행한 결과, 특정 알고리즘의 네트워크 표현 결과가 항상 좋은 품질을 보이는 것은 아니며, 반대로 항상 나쁜 품질을 보이는 것도 아님을 알 수 있었다. 따라서 이 연구에서 제안한 NetRSQ는 생성된 계량서지적 네트워크의 품질을 측정하여 최적의 기법을 선택하는 근거로 활용될 수 있을 것이다.

• Journal of Biosystems Engineering
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• 제31권4호
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• pp.315-322
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• 2006

A torsional damper comprised of two stage pre-dampers was used to reduce the rattle noise generated in the PTO gear box of a direct engine-PTO driveline of agricultural tractors. It was designed and mounted to the engine flywheel to reduce the torque fluctuation-induced speed variations at the driving gears in the PTO gearbox, which were found to be main cause of the rattle noise. The effects of a hysteresis torque and a torsional stiffness of the damper on the speed variation were analyzed using an 11 degree of freedom non-linear model of the damped PTO driveline. The torsional damper was represented by a single degree of freedom model with 7 parameters. Under a constant hysteresis torque, velocity variation was reduced with decrease in the torsional stiffness of the damper. The velocity variation was also decreased with decrease in the hysteresis torque under a constant torsional stiffness. Optimum values of the torsional stiffness and hysteresis torque were obtained by the model simulation for the PTO driveline under the study. When the optimum values of the damper were used, the sound pressure level of the rattle noise was reduced by 81%, resulting in a reduction of 15dB(A). The optimum damper also reduced the engine speed variation, resulting in a reduction of 80% at the driving gears in the PTO gearbox. The torsional damper showed a good performance in reducing the rattle noise caused by the speed variation in the direct engine-PTO driveline.

• 대한족부족관절학회지
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• 제14권2호
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• pp.157-160
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• 2010

Purpose: The purpose of this study is to find out the correlation factors for prognosis of calcaneal fractures. Materials and Methods: 120 cases (feet) of calcaneal fractures, all of them followed up for more than 1 year after surgical procedures, consisted of 101 men (105 feet) and 13 women (15 feet) were reviewed retrospectively. The collected clinical data were as follows : injury mechanism, surgical procedures, time to procedure, time to work and the radiologic data: Bohler angle, heel width, displacement of posterior facet. AOFAS hindfoot score and VAS score were checked. With ANOVA test and multiple regression analysis, the data processed statistically. Results: According Sanders classification, type II was 37 cases (31%), type III 66 cases (55%), and type IV 17 cases (14%). On plane radiography, the Bohler angle improved to average 28.4 degree from 5.6 degree, and the displacement of posterior facet was corrected to average 1.2 mm. AOFAS hindfoot score was checked average 81.7 points postoperatively, and the meaningful difference existed between types of Sanders classification. The Bohler angle represented the outline of the calcaneus had the better correlation with the clinical outcome of calcaneal fractures rather than the anatomical reduction of the posterior facet did. And the width of calcaneus had good correlation with the clinical score. Conclusion: We should also concern about the outline of calcaneus, the width of calcaneus and the Bohler angle representing anatomical reduction, not only the acute reduction of the posterior facet.

• 한방재활의학과학회지
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• 제27권3호
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• pp.107-115
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• 2017

Objectives This study is planned to classify correlation between HIVD of L-spine MRI and Digital Infrared Thermal Image (DITI). Methods We measured the temperature of both leg whose 120 men and 116 women patients with lumbar pain in Bucheon Jaseng Korean Medicine Hospital. And We use Magnetic Resonance Imaging (MRI) for classifying the patients who has lumbar intervertebral disc or not. Results 1) There was no statistical relation between difference of both leg's temperature and gender (p>0.05). 2) There was meaningful statistical relation between difference of both leg's temperature and age (p<0.05). 3) There was meaningful statistical relation between direction of HIVD of L-spine and direction of temperature reduction. 4) There was meaningful statistical relation between the severity of HIVD of L5/S1 and degree of temperature reduction. But there was no statistical relation between the severity of HIVD of L3/4, L4/5 and degree of temperature reduction. Conclusions We can use Digital Infrared thermal image (DITI) on low back pain patients for diagnosis. But we should not use DITI alone. DITI has limit in diagnosis.

• 약학회지
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• 제55권1호
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• pp.39-44
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• 2011

Many reports indicate that $18{\beta}$-glycyrrhetinic acid ($18{\beta}$-GA) from Glycyrrhizae Radix has anti-inflammatory and immunoregulatory activities, whereas reports regarding anticancer activity of the compound are few. In present study, we investigated antitumor effect of $18{\beta}$-GA on tumor caused by A549 cancer cell in mice. Data resulting from the cytotoxicity assay showed that $18{\beta}$-GA caused killing of A549 cells. $LD_{50}$ values of $18{\beta}$-GA were app. 180 ${\mu}M$ and 80 ${\mu}M$, corresponding to 48 hr- and 72 hr-treatments, displaying that the killing activity was more effective as the $18{\beta}$-GA treatment was prolonged. Based on these data, antitumor effect of $18{\beta}$-GA was tested in nude mice. For induction of the tumor, A549 ($3{\times}10^6$ cells/mouse) was injected subcutaneously into the lateral abdomen of nude mice (Balb/c nu/nu). To determine the antitumor effect, nude mice with tumor were given $18{\beta}$-GA (1 mg/200 ${\mu}l$/mouse) intraperitoneally every three days for four times. Tumor-sizes were measured with a caliper for a period of 24 days. Results showed that the $18{\beta}$-GA treatment reduced the tumor-sizes (P<0.05) as compared with negative control nude mice that received diluent (DPBS). The reduction degree was greater than reduction degree by doxorubicin (60 ${\mu}g$/mouse), and the pattern of reduction was almost sustained during the entire period of the observation. In conclusion, our studies demonstrate that $18{\beta}$-GA has antitumor activity to the A549 cancer cell-caused tumor.

• 한국환경보건학회지
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• 제34권4호
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• pp.316-326
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• 2008

The Earth's temperature has risen $0.76^{\circ}C$ (degree) during last 100 years which Implies a sudden rise, compare with the 4oC (degrees) rise through out the past 20,000 years. If the volume of GHG (Greenhouse Gas) emission continues at the current level, the average temperature of the Earth will rise by $1^{\circ}C$ (degree) by 2030 with the further implication that the temperature of Earth will rise by $2{\sim}5^{\circ}C$ (degrees) every 100 years. Therefore, as we are aware that the temperature of the glacial epoch was $8{\sim}9^{\circ}C$ (degrees) lower than the present time, we can easily predict that the above temperature rises can be potentially disastrous for human life. Every country in the world recognizes theseriousness of the current climate change and adopted a convention on climate change in June 1992 in Rio. The COP1 was held in March 1995 in Berlin and the COP3 in Dec. 1997 in Kyotowhere the target (2008-2012) was determined and the advanced nations' reduction target (5.2%, average)was also agreed at this conference. Korea participated in the GHG reduction plan which required the world's nations to ratify the Kyoto Protocol. Ratification of the Kyotoprotocol and the followup requirement to introduce an international emissions trading scheme will require severe reductions in GHGs and considerable economic consequences. USA are still refusing to fully ratify the treaty as the emission reductions could severely damage the economies of these countries. In order to estimate the exact $CO_2$ emission, this study statistically analyzed $CO_2$ emission of each country based on the following variables : level of economic power and scientific development, the industrial system, productivity and energy efficiency.

• Gut and Liver
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• 제12권6호
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• pp.633-640
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• 2018

Background/Aims: Obesity is a risk factor for gastroesophageal reflux disease (GERD), with several studies demonstrating positive associations between body mass index (BMI) and GERD symptoms. However, little is known about the effect of BMI changes on erosive esophagitis (EE). In this study, we investigated whether BMI reduction could resolve EE. Methods: A retrospective cohort study was performed to assess the natural course of EE according to changes in BMI. Participants undergoing health check-ups from 2006 to 2012 were enrolled, and 1,126 subjects with EE were included. The degree of esophagitis was measured by upper endoscopy and serially checked over a 5-year follow-up. Logistic regression and Cox proportional hazards models were used to investigate the association between BMI reduction and EE resolution. Results: Substantial weight loss is associated with EE resolution. The adjusted odds ratio for EE resolution was 1.44 (95% confidence interval [CI], 1.09 to 1.92) among participants with a decrease in BMI compared to those with no decrease in BMI. The EE resolution rate was related to the degree of BMI reduction. The effect of weight loss on EE resolution was higher among subjects who lost more weight. Compared with subjects with no decrease in BMI, the hazard ratios for EE resolution were 1.09 (95% CI, 0.89 to 1.35), 1.31 (95% CI, 1.01 to 1.72) and 2.12 (95% CI, 1.44 to 3.12) in subjects with BMI reductions of ${\leq}1$, 1-2, and >$2kg/m^2$, respectively. Conclusions: EE resolution is associated with a decrease in BMI, and weight loss is potentially an effective GERD treatment.

• Journal of Korean Neurosurgical Society
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• 제67권2호
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• pp.217-226
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• 2024

Objective : The efficacy of sciatic nerve decompression via transgluteal approach for entrapment of the sciatic nerve at the greater sciatic notch, called piriformis syndrome, and factors affecting the surgical outcome were analyzed. Methods : The outcome of pain reduction was analyzed in 81 patients with sciatic nerve entrapment who underwent decompression through a transgluteal approach. The patients were followed up for at least 6 months. The degree of pain reduction was analyzed using a numerical rating scale-11 (NRS-11) score and percent pain relief before and after last follow-up following surgery. Success was defined by at least 50% reduction in pain measured via NRS-11. To assess the degree of subjective satisfaction, a 10-point Likert scale was used. In addition, demographic characteristics, anatomical variations, and variations in surgical technique involving sacrotuberous ligamentectomy were analyzed as factors that affect the surgical outcome. Results : At a follow-up of 17.5±12.5 months, sciatic nerve decompression was successful in 50 of 81 patients (61.7%), and the pain relief rate was 43.9±34.17. Subjective improvement based on a 10-point Likert scale was 4.90±3.43. Among the factors that affect the surgical outcome, only additional division of the sacrotuberous ligament during piriformis muscle resection played a significant role. The success rate was higher in the scarotuberous ligementectomy group (79.4%) than in the non-resection group (42.6%), resulting in statistically significant difference based on average NRS-11 score, percent pain relief, and subjective improvement (p<0.05, independent t-test). Conclusion : Sciatic nerve decompression is effective in pain relief in chronic sciatica due to sciatic nerve entrapment at the greater sciatic notch. Its effect was further enhanced by circumferential dissection of the sciatic nerve based on the compartment formed by the piriformis muscle and the sacrotuberous ligament in the greater sciatic notch.

• Journal of Electrochemical Science and Technology
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• 제4권2호
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• pp.71-80
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• 2013

The study of methyl viologen ($MV^{2+}$) mediated oxygen reduction in electrolytic ethanol media possesses potential application in the electrochemical synthesis of hydrogen peroxide mainly due to the advantages of the much increased solubility of molecular oxygen ($O_2$) and high degree of reversibility of $MV^{2+/{\bullet}+}$ redox couple. The diffusion coefficients of both $MV^{2+}$ and $O_2$ were investigated via electrochemical techniques. For the first time, $MV^{2+}$ mediated $O_2$ reduction in electrolytic ethanol solution has been proved to be feasible on both boron-doped diamond and micro-carbon disc electrodes. The electrocatalytic response is demonstrated to be due to the radical cation, $MV^{{\bullet}+}$. The homogeneous electron transfer step is suggested to be the rate determining step with a rate constant of $(1{\pm}0.1){\times}10^5M^{-1}s^{-1}$. With the aid of a simulation program describing the EC' mechanism, by increasing the concentration ratio of $MV^{2+}$ to $O_2$ electrochemical catalysis can be switched from a partial to a 'total catalysis' regime.