• The Journal of the Korean dental association
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• v.56 no.3
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• pp.159-166
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• 2018

The zirconia-reinforced lithium silicate ceramic material is a material in which lithium silicate glass contains about 10% by weight of zirconia oxide (zirconia oxide). This material has both the advantages of glass ceramics and zirconia, and it is attracting attention as a CADCAM material for single tooth restoration. ZLS materials have improved strength compared to widely used e.max (lithium disilicate ceramic) materials. It can be used for single crown restoration and ensuring a thickness of 1.5 mm is very important for reliable treatment. In the case of Celtra Duo, heat treatment may be helpful in terms of strength and abrasion resistance. Hydrofluoric acid treatment is helpful for bonding and hydrofluoric acid for a short time may not help to improve the bonding strength. Although zirconia-reinforced lithium silicate ceramic materials have been continuously conducted and published in the laboratory, reliable clinical studies are still lacking. Additional clinical studies will be a very important part of establishing a scientific basis.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.6
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• pp.1-8
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• 2007

Minimizing the cylinder wear and the consumption rate of cylinder oil in a large two-stroke marine diesel engine is of great economic importance. In Korea, authors first developed a motor-driven cylinder lubricator for a Wartsila Switzerland large two-stroke diesel engine. The characteristic of the developed product is that can control automatically the oil feed rate with a load fluctuation by the motor drive and the offset cam. For manufacturing the reliable and useful products, however, it is necessary to investigate further characteristics and to improve performances as a cylinder lubricator. In this study, the effects of pump motor speed, plunger stroke and cylinder back pressure on oil feed rate, maximum discharge and delivery pressures are experimentally investigated by using the electronically controlled quill injection system and distributer in the developed cylinder lubricator. It is found that the oil feed rates of electronic control and mechanical type quills with the in-cylinder back pressure are differently characterized by the role of accumulator, the viscous resistance of contact area, etc. It can be also shown that the maximum discharge pressure of the electronic control quill is lower than the mechanical type one but the maximum discharge pressure difference of two types decreased as plunger stroke is small, and the maximum delivery pressures of two types increased as plunger stroke, motor speed and back pressure are elevated but the maximum delivery pressure of mechanical type is higher than the one of electronic control type.

• Elastomers and Composites
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• v.36 no.4
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• pp.237-245
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• 2001

A study was made on the chemical treatment of silica and silane coupling agents, bistriethox ysilylpropyltetrasulfide(Si 69) and ${\gamma}$-mercaptopropyltrimethoxy silane (MPS) for reinforcement of silica formulation. The effects of chemical treatment method and the most popular two coupling agents were examined. The results clearly indicate that the wet method, coupling agent is combined chemically with the silica prior to mixing, has more dispersion, wetting ability, dynamic properties and stability than the dry method, coupling agent is premixed directly with the silica. The mixing was done using a bench-type kneader having two mixing cam and a two-roll mill, under approximately similar conditions. The physical properties of SBR vulcanizates give rise to marked improvements by addition of Si 69 and MPS in comparison with without silane coupling agents. The optimum amount of Si 69 and MPS was 2 w/w% by experiments in the dry method but was 4 w/w% by EA and TGA analysis in the wet method.

• Journal of Broadcast Engineering
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• v.17 no.6
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• pp.945-953
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• 2012

A depth map can be obtained by projecting/capturing patterns of stripes using a projector-camera system and analyzing the geometric relationship between the projected patterns and the captured patterns. This is usually called structured light technique. In this paper, we propose a new multi-threading scheme for accelerating a conventional structured light technique. On CPUs and GPUs, multi-threading can be implemented by using OpenMP and CUDA, respectively. However, the problem is that their performance changes according to the computational conditions of partial processes of a structured light technique. In other words, OpenMP (using multiple CPUs) outperformed CUDA (using multiple GPUs) in partial processes such as pattern decoding and depth estimation. In contrast, CUDA outperformed OpenMP in partial processes such as rectification and pattern segmentation. Therefore, we carefully analyze the computational conditions where each outperforms the other and do use the better one in the related conditions. As a result, the proposed method can estimate a depth map in a speed of over 25 fps on $1280{\times}800$ images.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.4
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• pp.227-237
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• 1993

This paper dealt with numerical analysis of sand drain considering the smear effect around drain wells and discontinuous deformation behavior due to difference in rigidity between drain materials and adjacent clayey soils. Biot's equation was selected as governing equation coupled with MODCAM (Modified Cam-clay) model or EVP(Elasto-Viscoplastic) model as constitutive equation. The validity as well as the accuracy of the method developed by author was checked by comparing the proposed method with those by Siriwardane and Ghaboussi using joint element. The FEM analysis developed in this study was applied to both 2-dimensional model foundation and actual foundation. the result of which proved to be satisfactory.

• Korean Journal of Head & Neck Oncology
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• v.12 no.2
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• pp.181-187
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• 1996

We have characterized 4 human squamous carcinoma cell lines established from the larynx and hypopharynx area. All the cell lines were cultured in RPMI-1640 medium. During the growth they showed monolayer adherence pattern in culture flask. They showed tonofilament on transmission electromicroscopy which is characteristic of squamous cell epithelium. DNA finger-printing using Hinf-l proved them to be originated from different beings. Flow cytometric analysis revealed them to show aneuploidy. Immunohistochemical staining for cytokeratin was done using CK1, CK8.13, CK19 and CAM5.2 antibody, and produced various patterns of positivity. All the cell lines showed varying degrees of tumorigenecity in athymic nude mice when injected subcutaneously, but only heterotransplanted SNU-1041 cell line showed continuous tumor growth. Histopathologic findings of the heterotransplanted tumors were identical to those of the original tumors of patients. This study suggests that establishment of many different squamous cell lines might bestow great capability in researches of the head and neck cancer.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.53.1-53.1
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• 2010

$Y^2$(Yonsei-Yale) Isochrones은 Yale의 항성 진화 계산을 이용한 정밀한 등연령곡선으로 구상성단의 연구에 널리 사용되고 있다. 이번 연구에서는 $Y^2$-Isochrones를 Kurucz 모형을 이용한 색변환을 통해서 SDSS로 널리 알려진 ugriz 필터 체계에 대해 적용하고 실제 관측 결과와 비교함으로써 타당성을 검증하고자 한다. 우선 ugriz 필터의 등연령곡선을 제공하는 BaSTI와 DSEP, Padova 모델간의 비교를 통해 $Y^2$-Isochorones이 MSTO에서 g-r값이 다른 모델에 비해 0.05정도 큼을 확인하였다. 또한 CFHT 3.6m 망원경의 가시광 카메라 MegaCam으로부터 얻은 중원소 함량이 낮은 다섯 개의 구상성단 M15, M30, M53, NGC 5053, NGC 5466에 대한 g, r, i 필터의 색등급도에 각각의 등연령곡선을 적용하여 모델에 따른 구상성단의 특성을 분석하였다. $Y^2$-isochrones를 이용한 (g-r, r) CMD의 분석 결과, BaSTI와 DSEP 모델에 비해 0.1~0.3만큼 거리지수가 크고, 성단의 나이는 1~3Gyr 정도 어리게 측정됨을 확인할 수 있었다. 더불어 SDSS 관측으로부터 얻어진 구상성단에 대한 색등급도와 비교 분석과정을 수행하여, 다른 망원경에서의 사용가능 여부를 확인하였다. 이 연구를 통하여 각 모델에 따른 등연령곡선의 차이를 확인하고, 현재 여러 망원경에서 사용되고, 앞으로 여러 대형망원경에서 사용될 ugriz 필터 체계에 $Y^2$-Isochrones를 적용할 수 있는 타당성을 제시하고자 한다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.7
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• pp.394-399
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• 2016

The silicon dioxide ($SiO_2$) was deposited using various gas as oxygen and nitrous oxide ($N_2O$) in nowadays. In order to improve electrical characteristics and the interface state density ($D_{it}$) in low temperature, It was deposited with carbon dioxide ($CO_2$) and silane ($SiH_4$) gas by inductively coupled plasma chemical vapor deposition (ICP-CVD). Each $D_{it}$ of $SiO_2$ using $CO_2$ and $N_2O$ gas was $1.30{\times}10^{10}cm^{-2}{\cdot}eV^{-1}$ and $3.31{\times}10^{10}cm^{-2}{\cdot}eV^{-1}$. It showed $SiO_2$ using $CO_2$ gas was about 2.55 times better than $N_2O$ gas. After 10 years when the thin film was applied to metal/insulator/semiconductor(MIS)-nonvolatile memory(NVM), MIS NVM using $SiO_2$($CO_2$) on tunneling layer had window memory of 2.16 V with 60% retention at bias voltage from +16 V to -19 V. However, MIS NVM applied $SiO_2$($N_2O$) to tunneling layer had 2.48 V with 61% retention at bias voltage from +20 V to -24 V. The results show $SiO_2$ using $CO_2$ decrease the $D_{it}$ and it improves the operating voltage.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.3
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• pp.219-224
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• 2017

A study on dissimilar friction-welded joints was performed for cam shaft applications using solid bar samples, 20mm in diameter, of forging steel(SF45) and carbon steel(SM45C). The main parameters of friction welding such as tensile tests, Vickers hardness surveys of the bond of area, the heat affected zone (HAZ), and the observation of microstructure were investigated to ensure a good quality of friction welding through visual observations. The specimens were tested as-welded and post weld heat treatment(PWHT). This paper deals with optimizing the welding conditions and analyzing various rotary bending fatigue test(RBFT) properties about heat-treated base metal(BM), as-welded and PWHT. Consequently, two materials for friction welding are strongly mixed with a well-combined structure of micro-particles without any molten material, particle growth, or any defect. Moreover, the fatigue limit of BM(SF45) and PWHT for the RBFT were observed as 180MPa and 250MPa, respectively. It was confirmed that the PWHT causes approximately 40％ improvement in the fatigue limit when compared to the BM(SF45).

• Journal of radiological science and technology
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• v.43 no.5
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• pp.397-404
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• 2020

Coronavirus disease(COVID-19) is highly infectious disease that directly affects the lungs. To observe the clinical findings from these lungs, the Chest Radiography(CXR) can be used in a fast manner. However, the diagnostic performance via CXR needs to be improved, since the identifying these findings are highly time-consuming and prone to human error. Therefore, Artificial Intelligence(AI) based tool may be useful to aid the diagnosis of COVID-19 via CXR. In this study, we explored various Deep learning(DL) approach to classify COVID-19, other viral pneumonia and normal. For the original dataset and lung-segmented dataset, the pre-trained AlexNet, SqueezeNet, ResNet18, DenseNet201 were transfer-trained and validated for 3 class - COVID-19, viral pneumonia, normal. In the results, AlexNet showed the highest mean accuracy of 99.15±2.69% and fastest training time of 1.61±0.56 min among 4 pre-trained neural networks. In this study, we demonstrated the performance of 4 pre-trained neural networks in COVID-19 diagnosis with CXR images. Further, we plotted the class activation map(CAM) of each network and demonstrated that the lung-segmentation pre-processing improve the performance of COVID-19 classifier with CXR images by excluding background features.