• Journal of Periodontal and Implant Science
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• 제38권sup2호
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• pp.325-334
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• 2008

Purpose: The carrier used as delivery agent for bone morphogenetic proteins(BMPs) should also act as a scaffold for new bone formation. Moreover, bone formation should be predictable in terms of the volume and shape. This study examined the osteogenic effect of macroporous biphasic calcium phosphate (MBCP) block combined with ePTFE membrane as a carrier for recombinant human bone morphogenetic proteins (rhBMP-2). In addition, the additive effect of ePTFE membrane on bone formation was evaluated. Materials and Methods: Eight-millimeter critical sized calvarial defects were created surgically in 28 male Sprague-Dawley rats. The animals were divided into 2 groups containing 14 animals each. The defects were treated with either rhBMP-2/MBCP block (rhBMP-2/MBCP group) or rhBMP-2/MBCP block/ePTFE membrane (rhBMP-2/MBCP/ePTFE group). A disc-shaped MBCP block (3 mm height and 8 mm diameter) was used as the carrier for the rhBMP-2 and ePTFE membrane was used to cover the rhBMP-2/MBCP block. The histologic and histometric parameters were used to evaluate the defects after 2- or 8-week healing period (7 animals/group/healing interval). Results: The level of bone formation in the defects of both groups was significantly higher at 8 weeks than that at 2 weeks (P < 0.05). The ePTFE membrane has no additional effect compared with the rhBMP-2/MBCP block only. However, at 8 weeks, rhBMP-2/MBCP/ePTFE group showed more even bone formation on the top of the MBCP block than the rhBMP-2/MBCP group. Conclusion: These results suggest that the ePTFE membrane has no additive effect on bone formation when a MBCP block is used as a carrier for rhBMP-2.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제31권4호
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• pp.306-311
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• 2005

Despite advances in surgery, radiotherapy, and chemotherapy, the survival of patients with oral squamous cell carcinoma has not significantly improved over the past several decades. Gene therapy is currently under investigation and shows us new possibility of cancer curing method. This experiment was undergone to find out the cell growth inhibition effect and evidence of apoptosis by HCCS-1(human cervical cancer suppressor-1), one of the candidates of tumor suppressor gene, transducted to human oral cancer cell line. To determine the efficiency of the adenovirus as a gene delivery vector cell line was transducted with LacZ gene and analysed with X-gal staining. Northern blot was performed to confirm the transfection with HSCC-1 gene and cell viability was assessed by cell cytotoxicity assay using cell count kit(CCK). To show the evidence of apoptosis, DNA fragmentation assay and flow cytometry(FACS) were performed. We had successfully construct the recombinant HSCC-1 adenovirus(Ad5CMV-HCCS-1), and importation efficiency was 20% at 2 MOI(multiplicity of infection), 80% at 20 MOI. Northern blot analysis showed that a single 0.6kb mRNA transcript was expressed in Ad5CMV-HCCS-1 transducted cell lines. As a result of CCK, when comparing to control subjects, transducted group showed 50% growth inhibition. In DNA fragmentation assay, according to increasing of MOI, DNA volume was diminished. In FACS analysis, DNA distribution showed fragmentation. This results imply that HCCS-1gene has growth inhibition effect in human oral cancer cell lines through apoptosis induction.

• Polymer(Korea)
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• 제26권5호
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• pp.691-700
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• 2002

Interstitial therapy using biodegradable polymeric device loaded with anticancer agent can deliver the drug to the tumor site at high concentration, resulting in an increase of therapeutic efficacy. 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU, carmustine) is most commonly used as chemotherapeutic agent for brain tumors. The design of implantable device is regarded as an important factor lot the efficient delivery of antitumor agent to targeting site. In order to control the release profile of drug, the release pattern of BCNU with the changes of various dimension and additives was investigated. The PLGA wafers containing 3.85, 10, 20 and 30% of BCNU were prepared in various shape (diameter of 3, 5 and 10 mm, thickness of 0.5, 1 and 2 mm) by direct compression method. In vitro drug release profile of BCNU-loaded PLGA wafers could be controlled by changing the dimension of wafers such as initial drug content, weight, diameter, thickness, volume and surface area of wafers, as well as PLGA molecular weight and additives. Drug release from BCNU-loaded PLGA wafers was facilitated with an increase of BCNU-loading amount or presence of poly(N-vinylpyrrolidone)(PVP) or sodium chloride (NaCl). The effects of various geometric factors and additives on the BCNU release pattern were confirmed by the investigation of mass loss and morphology of BCNU-loaded PLGA wafers.

• Journal of Animal Environmental Science
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• 제11권1호
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• pp.25-34
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• 2005

The study aimed to develop a tractor drawn animal slurry manure sub-soil injector for arable land and thus, can reduce the waste management cost through effective treatment and utilization of animal slurry manure. The application of animal slurry manure to agricultural land will probably be one of the most effective ways to enrich the soil with vital nutrients. However, some existing slurry manure spenders are not suitable in the field because of their adverse effects to the environment. Based on this premise, a prototype was designed and assembled using 5 sub-soiling standards attached to the sin injector device. The traction force of the Prototype measured in the depth of 10 cm and 15 cm from the ground surface of a paddy field was 1,062 kgf and 1,214 kgf, respectively. A unique feature of the machine was that there was an equal volume of slurry manure flowing from each delivery pipe and regulated by a pressurized container that was likewise synchronized with the speed of the tractor The sub-soiling manure injection system can mitigate or reduce the harmful emission of obnoxious gases and malodor during the injection operation.

• Journal of KIISE:Databases
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• 제37권4호
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• pp.177-184
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• 2010

In these day, many data including sensor, delivery, credit and stock data are generated continuously in massive quantity. It is difficult to learn from these data because they are large in volume and changing fast in their concepts. To handle these problems, learning methods based in sliding window methods over time have been used. But these approaches have a problem of rebuilding models every time new data arrive, which requires a lot of time and cost. Therefore we need very simple incremental learning methods. Bayesian method is an example of these methods but it has a disadvantage which it requries the prior knowledge(probabiltiy) of data. In this study, we propose a learning method based on attribute values. In the proposed method, even though we don't know the prior knowledge(probability) of data, we can apply our new method to data. The main concept of this method is that each attribute value is regarded as an expert learner, summing up the expert learners lead to better results. Experimental results show our learning method learns from data very fast and performs well when compared to current learning methods(decision tree and bayesian).

• Journal of radiological science and technology
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• 제42권3호
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• pp.217-222
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• 2019

The purpose of this study is to evaluate the dose distribution by gantry rotation and MLC moving speed on treatment planning system(TPS) and linear accelerator. The dose analyzer phantom(Delta 4) was scanned by CT simulator for treatment planning. The planning target volumes(PTVs) of prostate and pancreas was prescribed 6,500 cGy, 5,000 cGy on VMAT(Volumetric Modulated Arc Therapy) by TPS while MLC speed changed. The analyzer phantom was irradiated linear accelerator using by planned parameters. Dose distribution of PTVs were evaluated by the homogeneity index, conformity index, dose volume histogram of organ at risk(rectum, bladder, spinal cord, kidney). And irradiated dose analysis were evaluated dose distribution and conformity by gamma index. The PTV dose of pancreas was 4,993 cGy during 0.1 cm/deg leaf and gantry that was the most closest prescribed dose(5,000 cGy). The dose of spinal cord, left kidney, and right kidney were accessed the lowest during 0.1 cm/deg, 1.5 cm/deg, 0.3 cm/deg. The PTV dose of prostate was 6,466 cGy during 0.1 cm/deg leaf and gantry that was the most closest prescribed dose(6,500 cGy). The dose of bladder and rectum were accessed the lowest during 0.3 cm/deg, 2.0 cm/deg. For gamma index, pancreas and prostate were analyzed the lowest error 100% at 0.8, 1.0 cm/deg and 99.6% at 0.3, 0.5 cm/deg. We should used the optimal leaf speed according to the gantry rotation if the treatment cases are performed VMAT.

• Journal of Climate Change Research
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• 제2권2호
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• pp.115-131
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• 2011

Out of all the possible actions that can be taken to respond to greenhouse gas reduction, including development of greenhouse gas reduction technology, infrastructure, actions to improve energy saving and efficiency, and offset with carbon emission reductions (CERs), this study shall focus on the investment on CERs. This study will take a look at risks involved with investing in CERs such as UN registration refusal risk and CERs price fluctuation, and will design risk management model which shall be verified. The goal of this paper is to provide optimized CERs investment strategies for different types of investors, such as general trading companies seeking for investment opportunities and financial companies with plans for green products development and investment by preparation for carbon market. It is expected that the global competitiveness of domestic financial companies shall be improved by taking actions on carbon market instead of previous passive response to climate change and that Korea, the number two Carbon Emissions supplier and number one derivatives market in terms of volume, shall be able to lead the worldwide carbon market.

• Particle and aerosol research
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• 제18권3호
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• pp.51-59
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• 2022

In this work, virion concentration and its dose changes by HVAC and air cleaners were estimated in a subway station platform to control airborne infection of SARS-CoV-2. Collection efficiencies with particle size were measured for the air filter equipped in a HVAC in one subway station in Daejeon. Indoor PM_2.5 changes according to outdoor PM_2.5 with time were also measured to estimate air infiltration rate in the subway station platform. When infected persons generate virions by 10⁴, 10⁵, 10⁶, 3 × 10⁶ and 5 × 10⁶ h^-1 in a 2,400 m³ volume platform, the concentration and dose were estimated as 9, 92, 275 and 458 virions/m³ and 4, 43, 130 and 217 virions after 1 hour exposure, respectively. The concentration and dose were reduced by 70%, and 64%, respectively by operations of both HVAC (with a flow rate of 16,000 m³/h, MERV 11) and ten air cleaners(with total CADR 10,740 m³/h) compared to those without operation of both HVAC and air cleaners. However, virion dose in the platform was estimated to be too low at the general conditions due to a large space, a high air infiltration (3 h^-1) and a short residence time (usually < 10 mins) in the platform irrespective of the operations of HVAC or air cleaners. HVAC with filters and air cleaners would be more necessary in the concourse or shopping areas in the subway stations to reduce the infection dose from a few hundred to several tens virions in a hour.

• Journal of the Korean Society of Radiology
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• 제17권5호
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• pp.633-640
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• 2023

With the recent development of static and dynamic modulated brachytherapy methods in brachytherapy, which use radiation shielding to modulate the dose distribution to deliver the dose, the amount of parameters and data required for dose calculation in inverse treatment planning and treatment plan optimization algorithms suitable for new directional beam intensity modulated brachytherapy is increasing. Although intensity-modulated brachytherapy enables accurate dose delivery of radiation, the increased amount of parameters and data increases the elapsed time required for dose calculation. In this study, a GPU-based CUDA-accelerated dose calculation algorithm was constructed to reduce the increase in dose calculation elapsed time. The acceleration of the calculation process was achieved by parallelizing the calculation of the system matrix of the volume of interest and the dose calculation. The developed algorithms were all performed in the same computing environment with an Intel (3.7 GHz, 6-core) CPU and a single NVIDIA GTX 1080ti graphics card, and the dose calculation time was evaluated by measuring only the dose calculation time, excluding the additional time required for loading data from disk and preprocessing operations. The results showed that the accelerated algorithm reduced the dose calculation time by about 30 times compared to the CPU-only calculation. The accelerated dose calculation algorithm can be expected to speed up treatment planning when new treatment plans need to be created to account for daily variations in applicator movement, such as in adaptive radiotherapy, or when dose calculation needs to account for changing parameters, such as in dynamically modulated brachytherapy.

• Information Systems Review
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• 제23권4호
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• pp.45-67
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• 2021

As the transaction volume of the C2C second-hand market is growing, the number of frauds, which intend to earn unfair gains by sending products different from specified ones or not sending them to buyers, is also increasing. This study explores the model that can identify frauds in the online C2C second-hand market by examining the postings for transactions. For this goal, this study collected 145,536 field data from actual C2C second-hand market. Then, the model is built with the characteristics from postings such as the topic and the linguistic characteristics of the product description, and the characteristics of products, postings, sellers, and transactions. The constructed model is then trained by the machine learning algorithm XGBoost. The final analysis results show that fraudulent postings have less information, which is also less specific, fewer nouns and images, a higher ratio of the number and white space, and a shorter length than genuine postings do. Also, while the genuine postings are focused on the product information for nouns, delivery information for verbs, and actions for adjectives, the fraudulent postings did not show those characteristics. This study shows that the various features can be extracted from postings written in C2C second-hand transactions and be used to construct an effective model for frauds. The proposed model can be also considered and applied for the other C2C platforms. Overall, the model proposed in this study can be expected to have positive effects on suppressing and preventing fraudulent behavior in online C2C markets.