• 방송공학회논문지
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• 제27권3호
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• pp.415-436
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• 2022

본 연구는 통합기술수용이론과 가치기반수용모델을 이용하여 이용자 인식과 특성이 스마트폰 공통 필수앱의 이용 행동에 미치는 영향을 분석하고자, 15세~65세를 대상으로 고객조사를 하였다. 연구결과, 정보프라이버시 염려를 제외한 성과기대, 즐거움, 촉진조건, 노력 기대, 사회적 영향 순으로 이용 행동에 정적인 영향을 미치는 것으로 나타났다. 연령에 의한 조절 효과는 젊은 층일수록 지각된 가치와 이용 의도 사이에서, 중장년층일수록 즐거움과 지각된 가치 사이에서 높게 나타났다. 본 연구는 선탑재 앱 설계 및 선탑재 앱 선정, 이용 활성화를 위한 전략수립에 시사점을 제공하는데 의의를 가진다.

• Geomechanics and Engineering
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• 제28권5호
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• pp.505-520
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• 2022

In recent years, geotextile-encased gravel columns (usually called stone columns) have become a popular method to increasing soil shear strength, decreasing the settlement, acceleration of the rate of consolidation, reducing the liquefaction potential and increasing the bearing capacity of foundations. The behavior of improved loose base-soil with gravel columns under shear loading and the shear stress-horizontal displacement curves got from large scale direct shear test are of great importance in understanding the performance of this method. In the present study, by performing 36 large-scale direct shear tests on sandy base-soil with different fine-content of zero to 30% in both not improved and improved with gravel columns, the effect of the presence of gravel columns in the loose soils were investigated. The results were used to predict the shear stress-horizontal displacement curve of these samples using support vector machines (SVM). Variables such as the non-plastic fine content of base-soil (FC), the area replacement ratio of the gravel column (Arr), the geotextile encasement and the normal stress on the sample were effective factors in the shear stress-horizontal displacement curve of the samples. The training and testing data of the model showed higher power of SVM compared to multilayer perceptron (MLP) neural network in predicting shear stress-horizontal displacement curve. After ensuring the accuracy of the model evaluation, by introducing different samples to the model, the effect of different variables on the maximum shear stress of the samples was investigated. The results showed that by adding a gravel column and increasing the Arr, the friction angle (ϕ) and cohesion (c) of the samples increase. This increase is less in base-soil with more FC, and in a proportion of the same Arr, with increasing FC, internal friction angle and cohesion decreases.

• Structural Engineering and Mechanics
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• 제83권4호
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• pp.551-561
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• 2022

In this paper, the effect of fire conditions according to ISO 834 standard on the behavior of carbon fibre-reinforced plastic (CFRP) reinforced steel beams coated with gypsum-based mortar has been investigated numerically. To study the efficiency of these beams, 3D coupled temperature-displacement finite element analyzes have been conducted. Mechanical and thermal characteristics of three different parts of composite beams, i.e., steel, CFRP plate, and fireproof coating, were considered as a function of temperature. The interaction between steel and CFRP plate has been simulated employing the adhesion model. The effect of temperature, CFRP plate reinforcement, and the fireproof coating thickness on the deformation of the beams have been analyzed. The results showed that within the first 120 min of fire exposure, increasing the thickness of the fireproof coating from 1 mm to 10 mm reduced the maximum temperature of the outer surface of the steel beam from 380℃ to 270℃. This increase in the thickness of the fireproof layer decreased the rate of growth in the temperature of the steel beam by approximately 30%. Besides excellent thermal resistance and gypsum-based mortar, the studied fireproof coating method could provide better fire resistance for steel structures and thus can be applied to building materials.

• 대한정형외과스포츠의학회지
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• 제2권1호
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• pp.28-36
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• 2003

목적: 전방십자인대재건술의성공에영향을미치는요인가운데수술후초기단계에는이식건에대한고정력이가장중요한인자로알려져있으며, 지금까지여러가지의고정방법들이사용되고있다. 저자는전방십자인대재건술후대퇴골측의초기안정성을알아보기위하여현재주로쓰이고있는6가지의고정방법들에대하여주기성인장부하검사를시행하기전,후의최대인장력을측정하여그결과를비교하고, 실패양상을관찰하고자하였다. 대상및방법: 돼지(Yorkshire) 슬관절72개를이용하여6가지고정방법(슬괵건-LA나사(R), 슬괵건-생체흡수성간섭나사, 슬괵건-Semifix 나사(R), 슬괵건-Endobutton(R)고정, 슬개건-티타늄간섭나사, 슬개건-생체흡수성간섭나사)으로이식건을고정하고 Instron(R) 인장검사기를이용하여주기성인장부하검사및최대실패인장력검사를시행하였다. 주기성인장부하검사는50 mm/min의속도로 30N에서 150N사이를1000회주기적으로반복하도록하였으며, 동일시편으로최대인장력검사를 시행하여주기성부하 후 최대 인장력의 변화를 비교, 분석하였다. 각 실험군에 따른 인장력 차이의통계적 유의성은ANOVA와Duncan 다중비교분석법을이용하였다. 결과: 주기성인장부하전,후이식건의최대인장력은슬괵건-LA나사(R) 군이평균1003.4$\pm$145N에서601.1$\pm$154N으로, 슬괵건-생체흡수성간섭나사군이평균 595.5$\pm$104N에서평균360.7$\pm$56N으로, 슬괵건-Semifix(R) 군이평균1431.7$\pm$135N에서평균710.7$\pm$114N으로, 슬괵건-Endobutton(R) 고정군이평균603.6$\pm$54N에서평균459.1$\pm$46N으로, 슬개건-티타늄 간섭나사군이평균 1067.4$\pm$145N에서평균 601.8$\pm$134N으로, 슬개건-생체흡수성간섭나사군이평균 987.1$\pm$168N에서588.7$\pm$124N으로각각40$\%$, 39$\%$, 50$\%$, 24$\%$, 44$\%$, 40$\%$가감소하였다. 결론: 수술후초기고정력은슬괵건을LA나사(R) 또는Semifix(R)로고정하는방법과슬개건을티타늄및생체흡수성간섭나사로고정하는방법등이우수하였으며, 슬괵건을생체흡수성간섭나사나Endobutton(R)으로 고정하는 방법 등은고정력이 상대적으로매우약함을 알수있었다. 최대인장력은단순인장검사로는이상의대퇴골측고정방법의고정력이초기부하를견뎌내는데충분하다고생각되었으나주기성부하실험후현저히감소되어충분한초기안정성을제공하지못함을알수있었다.

• 한국토양환경학회지
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• 제3권3호
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• pp.45-53
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• 1998

본 연구의 목적은 석유계탄화수소 오염토양의 처리에 있어서 초기농도 및 영양소의 영향을 평가하는 것이었다. 본 연구에서 이용한 반응기는 용기형태의 슬러리상 생물반응기였다. 디이젤연료 오염토양의 처리 및 미생물성장에 대한 수행결과는 실험실규모에서 얻어졌다. TPH(총 석유계 탄화수소)의 거동 및 미생물성장은 생물학적 제거율과 연관하여 평가되었다. 50,000및 100,000 mg TPH/kg soil의 초기부하수준에 대한 영향이 연구되었다. 두 반응기에서의 수행결과는 각각 90.5%와 90.8%의 총체적인 TPH제거율 나타내었다. 그러나 50,000mg TPH/kg soil의 초기농도가 적용된 반응기가 초기농도 100,000mg TPH/kg soil이 적용된 반응기에 비하여 휘발에 의한 제거를 제외한 순수한 생물학적 TPH제거율에 있어서 우수한 결과를 보여주었다. 다른 영양소량이 두 반응기에 적용되었음에도 불구하고 미생물성장율에 있어서 현저한 차이를 보이지는 않았다. 그러나 본 결과에서 고려되어야 할 중요한 요소는 두 반응기에 대하여 초기농도가 다르게 적용되었다는 것이다. 초기농도가 영양소가 첨가되지 않은 반응기에 비하여 두배나 높았음에도 불구하고 총체적 및 생물학적 TPH제거율에 있어서 영양소가 첨가된 반응기는 그렇지않은 반응기에 비하여 뛰어난 결과를 보여주었다.

• 에너지공학
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• 제23권2호
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• pp.49-56
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• 2014

생물학적 하수처리공정에서 안정적인 방류수질 확보와 처리 비용을 적게 하는 것은 매우 중요하다. 하지만 유입수 유량 및 성분 농도의 변화와 미생물의 비선형적인 동특성, 기타 환경 요인에 의해서 최적의 운전 제어를 하기가 쉽지 않기 때문에, 기존의 하수처리장에서는 필요한 양 이상의 폭기 및 화학물질을 과량 주입하는 방법 등을 사용하였다. 본 연구에서는 포기조에서 미생물에 필요한 용존산 소농도를 유지함과 동시에 과폭기로 인한 전력 비용을 감소할 수 있는 최적 제어 방법을 제안하였다. 최적 제어를 위하여 실시간 미생물 호흡률 측정기(Oxygen uptake rate, OUR)을 이용하여 측정하였고, 실시간 호흡률 측정값을 바탕으로 현재 미생물에 필요한 최적 DO 농도를 제안하였으며, 이에 따라 공기송풍기가 자동제어될 수 있도록 구성하였다. 최적 제어 방법을 통하여 하수처리장 포기조의 공기 송풍량에 소요되는 전력비용을 절감할 수 있었다.

• Steel and Composite Structures
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• 제30권6호
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• pp.551-565
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• 2019

A total of 36 carbon steel and stainless steel bolted connections subjected to shear loading at different strain rates was experimentally investigated. The connection specimens were fabricated from carbon steel grades 1.20 mm G500 and 1.90 mm G450, as well as cold-formed stainless steel types EN 1.4301 and EN 1.4162 with nominal thickness 1.50 mm. The connection tests were conducted by displacement control test method. The strain rates of 10 mm/min and 20 mm/min were used. Structural behaviour of the connection specimens tested at different strain rates was investigated in terms of ultimate load, elongation corresponding to ultimate load and failure mode. Generally, it is shown that the higher strain rate on the bolted connection specimens, the higher ultimate load was obtained. The ultimate loads were averagely 2-6% higher, while the corresponding elongations were averagely 8-9% higher for the test results obtained from the strain rate of 20 mm/min compared with those obtained from the lower strain rates (1.0 mm/min for carbon steel and 1.5 mm/min for stainless steel). The connection specimens were generally failed in plate bearing of the carbon steel and stainless steel. It is shown that increasing the strain rate up to 20 mm/min generally has no effect on the bearing failure mode of the carbon steel and stainless steel bolted connections. The test strengths and failure modes were compared with the results predicted by the bolted connection design rules in international design specifications, including the Australian/New Zealand Standard (AS/NZS4600 2018), Eurocode 3 - Part 1.3 (EC3-1.3 2006) and North American Specification (AISI S100 2016) for cold-formed carbon steel structures as well as the American Specification (ASCE 2002), AS/NZS4673 (2001) and Eurocode 3 - Part 1.4 (EC3-1.4 2015) for stainless steel structures. It is shown that the AS/NZS4600 (2018), EC3-1.3 (2006) and AISI S100 (2016) generally provide conservative predictions for the carbon steel bolted connections. Both the ASCE (2002) and the EC3-1.4 (2015) provide conservative predictions for the stainless steel bolted connections. The EC3-1.3 (2006) generally provided more accurate predictions of failure mode for carbon steel bolted connections than the AS/NZS4600 (2018) and the AISI S100 (2016). The failure modes of stainless steel bolted connections predicted by the EC3-1.4 (2015) are more consistent with the test results compared with those predicted by the ASCE (2002).

• 대한환경공학회지
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• 제37권2호
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• pp.73-80
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• 2015

본 연구에서는 잔류의약물질로써 환경에서 노출 빈도가 높은 항생물질인 Tetracycline (TTC)을 대상으로 수용액 상에서의 망간산화물(birnessite)을 이용한 산화-변환 반응을 통한 제거와 용존성 자연유기물인 휴믹산(HA) 존재에 따른 영향을 조사하였다. TTC의 산화-변환 제거 특성 실험은 다양한 반응조건(반응시간, 망간산화물 주입량 및 pH 등)에서 회분식으로 조사하였으며, HA의 영향은 pH (3~9)와 HA농도 변화에 따라 조사하였다. 실험결과는 유사-일차 반응속도식을 적용하여 해석하였으며, 본 실험조건(TTC=0.25 mM, ${\delta}-MnO_2=1.0g/L$)에서의 TTC의 산화-변환 제거 반응속도상수(k, $hr^{-1}$)는 pH가 감소함에 따라 0.98 (pH 9)에서 2.97 (pH 3)로 일정하게 증가하였고, 망간산화물 주입량(1~2 g/L)이 2배 증가할 때 반응속도 상수는 약 1.3배 정도 증가하였다. HA (5 mg-C/L) 존재 시 망간산화물에 의한 TTC 변환제거는 $pH{\geq}6$에서 반응효율 상승을 나타냈으며, HA의 주입농도(1~10 mg-C/L, at pH 6)의 증가에 따라 일정하게 증가함을 확인하였다. 이상에서 얻은 연구결과는 기존 문헌에 제시된 TTC 반응기작과 비교 해석하였고, 망간산화물을 매개로 한 TTC의 산환-변환 제거 반응특성과 HA의 존재가 미치는 영향에 대하여 고찰하였다.

• Biomolecules & Therapeutics
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• 제25권4호
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• pp.452-459
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• 2017

In this study, the effect of particle size of genistein-loaded solid lipid particulate systems on drug dissolution behavior and oral bioavailability was investigated. Genistein-loaded solid lipid microparticles and nanoparticles were prepared with glyceryl palmitostearate. Except for the particle size, other properties of genistein-loaded solid lipid microparticles and nanoparticles such as particle composition and drug loading efficiency and amount were similarly controlled to mainly evaluate the effect of different particle sizes of the solid lipid particulate systems on drug dissolution behavior and oral bioavailability. The results showed that genistein-loaded solid lipid microparticles and nanoparticles exhibited a considerably increased drug dissolution rate compared to that of genistein bulk powder and suspension. The microparticles gradually released genistein as a function of time while the nanoparticles exhibited a biphasic drug release pattern, showing an initial burst drug release, followed by a sustained release. The oral bioavailability of genistein loaded in solid lipid microparticles and nanoparticles in rats was also significantly enhanced compared to that in bulk powders and the suspension. However, the bioavailability from the microparticles increased more than that from the nanoparticles mainly because the rapid drug dissolution rate and rapid absorption of genistein because of the large surface area of the genistein-solid lipid nanoparticles cleared the drug to a greater extent than the genistein-solid lipid microparticles did. Therefore, the findings of this study suggest that controlling the particle size of solid-lipid particulate systems at a micro-scale would be a promising strategy to increase the oral bioavailability of genistein.

• 대한치과보철학회지
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• 제43권4호
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• pp.511-518
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• 2005

Purpose: The purpose of this study is to find the effect of rare earth magnet's magnetic field of to the osteoblast around the implant by the means of observation number, and distribution around the implant which is connected to the permanent magnet but not, counted and compared by the number of cells attached to the surface of the implant. Material and method: The permanent magnets, made in the healing cap form, were connected to the implant future, and placed on the culture plate, The osteoblast-like cell: MC3T3-E1 were used for cell culture. As the control group, the implant were connected to normal healing cap, and cultured in the same conditions. 48 hours later, using inverted microscope, the number and distribution of osteoblast around the implant were observed, and 72 hours later, the number of the cells attached to the implant were counted. Results: As a result, the implant connected to the permanent magnet had proved to have a more concentrated cell distribution rate than the control group. The implant connected to the permanent magnet, neck area : which has about 10 gauss magnetic force, had more cells than apex area. The implant connected to the permanent magnet had proven to attach to the osteoblast more productively than control group's implant. Conclusions: This research showed that the magnetic field of the permanent magnet affected the distribution and growth rate of the osteoblast around the implant. In order to support this study, it also had need to monitor the progress of the permanent magnet specifically shown on the neck area, which has10 gauss magnetic force. So after additional research on the distribution and attachment of the cells, and further more, on bone formation, it will be concluded that the clinical applications ,such as immediate loading of implant treatment are possible.