• 마이크로전자및패키징학회지
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• 제16권4호
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• pp.17-22
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• 2009

Two different organic-inorganic hybrid thin film transistors (OITFTs) with the structures of glass/ITO/ZnO/PMMA/Al (staggered structure) and glass/ITO/PMMA/ZnO/Al (inverted staggered structure), were fabricated and their electrical and structural properties were compared. The ZnO thin films used as active channel layers were deposited by the atomic layer deposition (ALD) method at a temperature of $100^{\circ}C$. To investigate the effect of the substrates on their properties, the ZnO films were deposited on bare glass, PMMA/glass and ITO/glass substrates and their crystal properties and surface morphologies were analyzed. The structural properties of the ZnO films varied with the substrate conditions. The ZnO film deposited on the ITO/glass substrate showed better crystallinity and morphologies, such as a higher preferred c-axis orientation, lower FWHM value and larger particle size compared with the one deposited on the PMMA/glass substrate. The field effect mobility ($\mu$), threshold voltage ($V_T$) and $I_{on/off}$ switching ratio for the OITFT with the staggered structure were about $0.61\;cm^2/V{\cdot}s$, 5.5 V and $10^2$, whereas those of the OITFT with the inverted staggered structure were found to be $0.31\;cm^2/V{\cdot}s$, 6.8 V and 10, respectively. The improved electrical properties for the staggered OITFTs may originate from the improved crystal properties and larger particle size of the ZnO active layer.

• 대한치과기공학회지
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• 제40권3호
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• pp.115-123
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• 2018

Purpose: The purpose of this study was establishing process of manufacturing dental prosthesis by using eZIS system(DDS Inc.,Korea). Methods: To evaluate accuracy verification, the test was practiced two ways. First, Comparison of 3D printing models and stone models was practiced by using 3D superimposing software. #36 prepared master model was scanned by eZIS system and three 'Veltz3D' 3D printing models and three 'Bio3D' 3D printing models were manufactured. three stone models were manufactured by conventional impression technique. Second, Fitness test was practiced. the 3D printing models and the stone models was compared by manufacturing same resin crown. #36 prepared master model was scanned 9 times and manufactured (milled) 9 resin crowns by eZIS system. These crowns were cemented three 'Veltz3D' 3D printing models, three 'Bio3D' 3D printing models and three stone models. These crowns were sliced mesiodistal axis and gaps were measured by digital microscope. Results: The average accuracy of Bio3D models were 65.75%. Veltz3D(Hebsiba) models were 60.11% Stone models were 41.00%. Conclusion : This study results showed 3D printing model is similar with stone model. So it was under clinical allow, didn't affect final dental prothesis. There were no significant differences in the appearance of the three types of milling crowns.

• 한국전자통신학회논문지
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• 제11권2호
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• pp.215-222
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• 2016

걸음 인식과 그 활용에 대하여 연구가 활발하게 진행되고 있다. 본 연구는 보행자의 비정상적인 보행을 인식하는 방안을 제안한다. 기존의 정상적인 걸음을 인식하는 것이 신체활동을 측정하거나, 인증을 위한 것이었다면, 본 연구의 비정상적인 걸음 인지는 보행자의 생활안전 보장을 위한 것이다. 보행자가 스스로 자신의 취약한 상태를 인지하고 도움을 요청하지 못하는 상황이 있기 때문에, 근래의 IoT기술을 도입하여 본인의 인지와 자발적 도움 요청이 없더라도 위험과 어려움을 벗어날 수 있도록 하고자 함이다. 이에 본 연구는 3축 가속도 센서를 활용하여 보행자의 정상적인 걸음을 분석함으로써 정상적인 걸음이 유지되는 상태에 대한 범위를 정하고, 이후 3축 가속도 센서를 활용하여 걸음을 측정하여 그 결과를 정상적인 걸음 범위에 대조하여 정상과 비정상 여부를 판단하도록 한다. 정상적인 걸음을 유지하는 상태를 벗어날 때, 이를 비정상적인 걸음으로 인지하는 방안을 제안한다.

• 천문학회보
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• 제37권1호
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• pp.95.2-95.2
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• 2012

We have compared the geoeffective parameters of halo coronal mass ejections (CMEs) to predict geomagnetic storms. For this we consider 50 front-side full halo CMEs whose asymmetric cone model parameters and earthward direction parameter were available. For each CME we use its projected velocity (Vp), radial velocity (Vr), angle between cone axis and sky plane (${\gamma}$) from the cone model, earthward direction parameter (D), source longitude (L), and magnetic field orientation (M) of the CME source region. We make a simple and multiple linear regression analysis to find out the relationship between CME parameters and Dst index. Major results are as follows. (1) $Vr{\times}{\gamma}$ has a higher correlation coefficient (cc = 0.70) with the Dst index than the others. When we make a multiple regression of Dst and two parameters ($Vr{\times}{\gamma}$, D), the correlation coefficient increases from 0.70 to 0.77. (2) Correlation coefficients between Dst index and $Vr{\times}{\gamma}$ have different values depending on M and L. (3) Super geomagnetic storms (Dst ${\leq}$ -200 nT) only appear in the western and southward events. Our results demonstrate that not only the cone model parameters together with the earthward direction parameter improve the relationship between CME parameters and Dst index but also the source longitude and its magnetic field orientation play a significant role in predicting geomagnetic storms.

• 대한기계학회논문집
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• 제8권5호
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• pp.442-449
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• 1984

본 연구에서는 두 분류가 교우되어 배합이 이루어지는 유동역에서 3차원 방향 에 대하여 평균속도분포, 난류강도분포, 난류전단응력분포, 상관계수의 분포 및 난류 운동에너지와 운동량의 변화 등을 측정 분석하였다.

• 대한의생명과학회지
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• 제15권3호
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• pp.249-255
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• 2009

All living things have been developed efficient strategies to cope with external and internal environmental changes via a process termed 'homeostasis'. However, chronic prenatal maternal stress may significantly contributes to pregnancy complications by disturbing hypothalamic-pituitary-adrenal (HPA) axis and the automatic nervous system (ANS), and results in unfavorable development of the fetus. Dysregulation of these two major stress response systems lead to the increased secretion of the glucocorticoids (GCs) which are known to be essential for normal development and the maturation of the central nervous system. As Hox genes are master key regulators of the embryonic morphogenesis and cell differentiation, we aimed to determine the effects of dexamethasone, a potent synthetic glucocorticoid, on gene expression in mesenchymal stem cell C3H10T1/2. Analysis of 39 Hox genes based on reverse transcription PCR (RT-PCR) method revealed that the expression patterns of Hox genes were overall upregulated by long dexametasone treatment. These results indicate that maternal stress may have a deleterious effect on early developing embryo through the stress hormone, glucocorticoid.

• 대한치과보철학회지
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• 제45권1호
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• pp.12-20
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• 2007

Purpose: The purpose of this study was to compare the fracture strength of the zirconia monolithic all-ceramic crowns according to the thickness (0.5mm, 0.8mm, 1.1mm) and metal-ceramic crowns (1.0mm, 1.5mm) Material and method: Twelve crowns for each of 3 zirconia crown groups were fabricated using CAD/CAM system (Kavo, Germany) and twelve crowns for each of 2 metal-ceramic crown groups were made by the conventional method. All crowns were luted to the metal dies using resin cement. Half of the specimens were exposed to thermocycling ($5-55^{\circ}C$, 1 Hz) and cyclic loading (300,000 cycles, 50N). Subsequently, all crowns were mounted on the testing jig in a universal testing machine. The load was directed at the center of crown with perpendicular to the long axis of each specimen until catastrophic failure occurred. Analysis of variance and Tukey multiple comparison test (P<.05) were used for statistical analysis of all groups, and paired t-test (P<.05) was followed for statistical comparison between each groups' fracture load before and after cyclic loading. Results: 1. The fracture strength of the zirconia monolithic crowns and the metal-ceramic crown increased as thickness increased (P<.05). 2. The cyclic loading and thermocycling significantly decreased the fracture strength of the zirconia monolithic crowns (P<.05). 3. The standard deviation of fracture strength of the zirconia monolithic crowns was very low. Conclusion: The fracture strength of the zirconia monolithic crowns for the posterior area tends to be higher with thickness increased and 0.8mm or over in thickness is recommended to have similar or over the fracture strength of metal-ceramic crowns.

• 대한불안의학회지
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• 제10권2호
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• pp.115-127
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• 2014

Objective : Existing depression rating scales do not fully reflect depressed patients' perspective of remission, which goes beyond symptom resolution. The Remission from Depression Questionnaire (RDQ) captures a broader array of domains, and the present study examines the reliability and validity of the Korean Version of the RDQ (K-RDQ). Methods : The test-retest reliability of the K-RDQ was studied in 60 depressed patients and 30 normal subjects working at a university hospital. Subjects were evaluated at baseline and again 1-2 weeks later. The validity of the K-RDQ was studied in 200 depressed patients who were rated on the 17-item HDRS and the CGI-S ; each patient also completed the QIDS-SR, STAI-S, GHQ/QL-12, and SDS. Results : The K-RDQ demonstrated excellent internal consistency, with a Cronbach's ${\alpha}$ of 0.965 for the total scale and above 0.80 for each of the 7 subscales. The test-retest reliability of the total scale was 0.951. Mean K-RDQ scores ($45.79{\pm}18.65$) of the depressed patients were significantly higher than those ($15.87{\pm}10.60$) of the mentally healthy subjects (t=12.8, p<0.001). Five factors from the K-RDQ were extracted by principal axis factoring with equimax rotation. Conclusion : These results indicate that the K-RDQ is a reliable and valid measure that evaluates multiple domains that depressed patients consider important in determining remission. Thus, the K-RDQ maybe considered an appropriate tool for use in the clinical setting.

• Geomechanics and Engineering
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• 제16권3호
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• pp.295-308
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• 2018

The excavation of twin tunnels is a process that destabilizes the ground. The stability of the tunnel lining, the control of ground displacements around the tunnel resulting from each excavation and the interaction between them must be controlled. This paper provides a new approach for replacing the costly 3D analyses with the equivalent 2D analyses that closely reflects the in-situ measurements when excavating twin tunnels. The modeling was performed in two dimensions using the FLAC2D finite difference code. The three-dimensional effect of excavation is taken into account through the deconfinement rate ${\lambda}$ of the soil surrounding the excavation by applying the convergence-confinement method. A comparison between settlements derived by the proposed 2D analysis and the settlements measured in a real project in Algeria shows an acceptable agreement. Also, this paper reports the investigation into the changes in deformations on tunnel linings and surface settlements which may be expected if the twin tunnels of T4 El-Harouche Skikda were constructed with a tunneling machine. Special attention was paid to the influence of the excavation phase shift distance between the two mechanized tunnel faces. It is revealed that the ground movements and the lining deformations during tunnel excavation depend on the distance between the tunnels' axis and the excavation phase shift.

• Journal of Korean Neurosurgical Society
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• 제29권12호
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• pp.1634-1641
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• 2000

Objective : The cerebrospinal fluid(CSF) pulsates within the craniospinal axis in response to rhythmic cerebral blood volume variation during the cardiac cycle. The aim of this study is to characterize the normal and abnormal CSF flow and its waveforms in the cervical spinal subarachnoid space. Methods : The magnetic resonance(MR) images were obtained with 1.5 T(GE Signa, GE Medical Systems, Milwaukee, USA) unit using the 2 dimensional cine PC(phase contrast) sequence with cardiac gating and gradient recalled echo imaging. This pulse sequence yielded 16 quantitative flow-encoded images per cardiac cycle. Sagittal and axial images of the cervical spinal CSF space were obtained, and target sites were analyzed for characteristic CSF flow (TR=50ms, TE=12.5-15ms). The region of interest(ROI) was 1mm 3 in volume. Twenty six persons were included in this study : 10 healthy volunteers and 16 patients with cervical myelopathy. The post-operative cine MR study were also done in five patients. Results : The normal CSF pulsation dynamics in the cervical spine showed discrete systolic and diastolic components. The CSF flow revealed a sine wave pattern, in which the systolic phase was shorter than the diastolic phase(ratio=2 : 3). The patient group revealed decreased amplitudes of the CSF flow and irregularly distored flow waves. The systolic phase was elongated in the ROI above the stenotic level, whereas the diastolic phase was lengthened below the level. In the postoperative images, the abnormal pattern and amplitude were found to be corrected. Conclusion : From these results, the authors believe that the CSF flow study provides valuable informations regarding the extent of cervical stenosis and may be useful for the surgical planning and post-operative evaluation.