• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제42권6호
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• pp.352-357
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• 2016

Objectives: This study aimed to evaluate the stability of prosthetic screws from three types of craniofacial prostheses retention systems (bar-clip, ball/O-ring, and magnet) when submitted to mechanical cycling. Materials and Methods: Twelve models of acrylic resin were used with implants placed 20 mm from each other and separated into three groups: (1) bar-clip (Sistema INP, São Paulo, Brazil), (2) ball/O-ring (Sistema INP), and (3) magnet (Metalmag, São Paulo, Brazil), with four samples in each group. Each sample underwent a mechanical cycling removal and insertion test (f=0.5 Hz) to determine the torque and the detorque values of the retention screws. A servo-hydraulic MTS machine (810-Flextest 40; MTS Systems, Eden Prairie, MN, USA) was used to perform the cycling with 2.5 mm and a displacement of 10 mm/s. The screws of the retention systems received an initial torque of 30 Ncm and the torque values required for loosening the screw values were obtained in three cycles (1,080, 2,160, and 3,240). The screws were retorqued to 30 Ncm before each new cycle. Results: The sample was composed of 24 screws grouped as follows: bar-clip (n=8), ball/O-ring (n=8), and magnet (n=8). There were significant differences between the groups, with greater detorque values observed in the ball/O-ring group when compared to the bar-clip and magnet groups for the first cycle. However, the detorque value was greater in the bar-clip group for the second cycle. Conclusion: The results of this study indicate that all prosthetic screws will loosen slightly after an initial tightening torque, also the bar-clip retention system demonstrated greater loosening of the screws when compared with ball/O-ring and magnet retention systems.

• Molecular & Cellular Toxicology
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• 제3권4호
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• pp.246-253
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• 2007

Doxorubicin and daunorubicin are excellent chemotherapeutic agents utilized for several types of cancer but the irreversible cardiac damage is the major limitation for its use. The biochemical mechanisms of doxorubicin- and daunorubicin- induced cardiotoxicity remain unclear. There are many reports on toxicity of doxorubicin and doxorubicin in cardiomyocytes, but effects in cardiovascular system by these drugs are almost not reported. In this study, we investigated gene expression profiles in human umbilical vein endothelial cells (HUVECs) to better understand the causes of doxorubicin and doxorubicininduced cardiovascular toxicity and to identify differentially expressed genes (DEGs). Through the clustering analysis of gene expression profiles, we identified 124 up-regulated common genes and 298 down-regulated common genes changed by more than 1.5-fold by all two cardiac toxicants. HUVECs responded to doxorubicin and doxorubicin damage by increasing levels of apoptosis, oxidative stress, EGF and lipid metabolism related genes. By clustering analysis, we identified some genes as potential markers on apoptosis effects of doxorubicin and doxorubicin. Six genes of these, BBC3, APLP1, FAS, TP53INP, BIRC5 and DAPK were the most significantly affected by doxorubicin and doxorubicin. Thus, this study suggests that these differentially expressed genes may play an important role in the cardiovascular toxic effects and have significant potential as novel biomarkers to doxorubicin and doxorubicin exposure.

• The Korean Journal of Ecology
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• 제14권3호
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• pp.305-316
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• 1991

Growth hadit and demograph in a mature population of polygonatum and polygonatum humile in kanghwa island were studied for two growing seasons. Shoots of two species emerged early spring from the growing apices of the underdground rhizomes which had persisted for up to 1~5 year.after flowering, the ramets produced two rhizome buds at the shoot base. Bacause of the apical dominance in the rhizome system, a new rhizome was developed from only one bud, an actual bud,and the other latent buds were suppressed sothat remained dormant. The latent dud produced a new rhizome only when the actual dud was severed by the herbivores or by the physical obstacles. Therefore, the ramet number is not increased by the new rhizome from the latent bud. however, new ramets dould sometimes grow from latent buds which had been produced more than a year ago. Production of these ramets was main means increasing the ramet numbew and widening the potential zone of exploitation. Changes in size class of each ramet were noyiceable after a tear in small size-classes. Small ramets replaced themselves with larger-sized ramet, while large ramets with similar-sized or smallar-sized ramets. ramet numbers were average 0.82and 1.14 times of those fromthe previous year inp. involucratum and p. humile, though there was between-site variation. Almost all the ramets in the quadrats were alive during the growing season. when the entire rhizome systems were excavater next spring, there were many rhizomesegments without shoots, especially in p. involucratum. therefore, the drcrease of ramet number in p. involucratum in probably due to the climatic factors of winter.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2000년도 춘계종합학술대회
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• pp.447-450
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• 2000

본 논문에서는 III-V 화합물 반도체 마이크로머시닝을 위한 InP를 기반으로한 미세구조의 제조에 관하여 보고한다. InP/InGaAsP/1nP 구조를 성장시키기 위하여 수직 LPE 시스템을 사용하였다. 성장된 InGaAsP층의 두께는 0.4$\mu\textrm{m}$이고, InP top-layer의 두께는 l$\mu\textrm{m}$이었다. InGaAsP 미세구조의 제조는 front side 벌크 마이크로머시닝으로 이루어졌다. 실험결과에서 <110> 방향에서 빔의 측면에칭이<100> 방향에서의 에칭보다 더 빠르기 때문에 빔은 <110> 방향으로 정렬되어야 함을 보였다.

• International Journal of Fluid Machinery and Systems
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• 제10권3호
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• pp.254-263
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• 2017

The cavitation erosion remains an industrial issue for many applications. This paper deals with the cavitation intensity, which can be described as the fluid mechanical loading leading to cavitation damage. The estimation of this quantity is a challenging problem both in terms of modeling the cavitating flow and predicting the erosion due to cavitation. For this purpose, a numerical methodology was proposed to estimate cavitation intensity from 3D unsteady cavitating flow simulations. CFD calculations were carried out using Code_Saturne, which enables U-RANS equations resolution for a homogeneous fluid mixture using the Merkle's model, coupled to a $k-{\varepsilon}$ turbulence model with the Reboud's correction. A post-process cavitation intensity prediction model was developed based on pressure and void fraction derivatives. This model is applied on a flow around a hydrofoil using different physical (inlet velocities) and numerical (meshes and time steps) parameters. The article presents the cavitation intensity model as well as the comparison of this model with experimental results. The numerical predictions of cavitation damage are in good agreement with experimental results obtained by pitting test.

• Journal of the Korean Wood Science and Technology
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• 제42권2호
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• pp.119-129
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• 2014

This work undertook to prepare nanofibers of cellulose nanofibrils (CNF)/polyvinyl alcohol (PVA) composite by electrospinning, and characterize the electrospun composite nanofibers. Different contents of CNFs isolated from hardwood bleached kraft pulp (HW-BKP) by 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO)-mediated oxidation were suspended in aqueous polyvinyl alcohol (PVA) solution, and then electrospun into CNF/PVA composite nanofibers. The morphology and dimension of CNFs were characterized by transmission electron microscopy (TEM), which revealed that CNFs were fibrillated form with the diameter of about $7.07{\pm}0.99$ nm. Morphology of the electrospun nanofiber observed by field-emission scanning electron microscopy (FE-SEM) showed that uniform CNF/PVA composite nanofibers were manufactured at 1~3% CNF contents while many beads were observed at 5% CNF level. Both the viscosity of CNF/PVA solution and diameter of the electrospun nanofiber decreased with an increase in CNF content. The diameter and its distribution of the electrospun nanofibers helped explain the differences observed in their morphology. These results show that the electrospinning method was successful in preparing uniform CNF/PVA nanofibers, indicating a great potential for manufacturing consistent and reliable cellulose-based nanofibrils for scaffolds in future applications.

• Journal of Mechanical Science and Technology
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• 제19권8호
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• pp.1529-1543
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• 2005

Recently an unmanned aerial vehicle (UAV) has been widely used for military and civil applications. The role of a navigation system in the UAV is to provide navigation data to the flight control computer (FCC) for guidance and control. Since performance of the FCC is highly reliant on the navigation data, a fault in the navigation system may lead to a disastrous failure of the whole UAV. Therefore, the navigation system should possess a fault detection and isolation (FDI) algorithm. This paper proposes an attitude determination GPS/INS integrated navigation system with an FDI algorithm for a UAV. Hardware for the proposed navigation system has been developed. The developed hardware comprises a commercial inertial measurement unit (IMU) and the integrated navigation package (INP) which includes an attitude determination GPS (ADGPS) receiver and a navigation computer unit (NCU). The navigation algorithm was implemented in a real-time operating system with a multi-tasking structure. To evaluate performance of the proposed navigation system, a flight test has been performed using a small aircraft. The test results show that the proposed navigation system can give accurate navigation results even in a high dynamic environment.

• 전자공학회논문지A
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• 제31A권6호
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• pp.88-97
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• 1994

We describe the design, fabrication, and performance of the optical fiber-photodiode 1$\times$12 arry module using mesa-type InS10.53T GaS10.47TAS/INP 1$\times$12 PIN photodiode array. We fabricated the PIN PD array for high-speed optical fiber parallel data link optimizing quantum efficiency, operating speed sensitivity from the PIN-FET structure, and electrical AC crosstalk. For each element of the array, the diameter of the photodetective area is 80 $\mu$m, the diameter of the p-metal pad is 90 $\mu$m, and the photodiode seperation is 250 $\mu$m to use Si v-groove. Ground conductor line is placed around diodes and p-metal pads are formed in zigzag to reduce Ac capacitance coupling between array elements. The dark current (IS1dT) is I nA and the capacitance(CS1pDT) is 0.9 pF at -5 V. No signifcant variations of IS1dT and CPD from element to element in the array were observed. We calulated the coupling efficiency for 10/125 SMF and 50/125 GI MMF, and measured the responsivity of the PD array at the wavelength is 1.55 $\mu$ m. Responsivities are 0.93 A/W for SMF and 0.96 A/W for MMF. The optical fiber-PD array module is useful in numerous high speed digital and analog photonic system applications.

• ETRI Journal
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• 제13권4호
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• pp.70-79
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• 1991

$In_1-x$$GA_X$$As_y$$P_1-y$ has a very wide range of applications in optoelectronic devices especially for optical communications because $In_1-x$$GA_X$$As_y$$P_1-y$ has the bandgap of the lowest dispersion ($1.3\mum$) and the lowest loss ( $1.55\mum$) of the optical fiber by changing the composition. The quality of $In_1-x$$GA_X$$As_y$$P_1-y$ epitaxial layer is believed to have a significant effect on the performance of device. The OMVPE growth conditions for the latticematched $In_1x$$GA_X$$As_y$$P_1-y$/InP were investigated. Effects of growth conditions such as V/III ratio, growth temperature, and Ga source material on the electrical and optical properties were studied. The composition, electrical and optical properities of $In_1-x$$GA_X$$As_y$$P_1-y$ were characterized using double crystal X-ray diffractometer (DCD), photoluminescence (PL), XPS(ESCA) and Hall measurement.

• 조명전기설비학회논문지
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• 제13권4호
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• pp.134-141
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• 1999

본 논문은 전동차량용 전원장치의 출력전압 제어 안정성을 향상시키기 위한 연구이다. 입력전압 변동 및 부하 변동 등 과도상태시 출력 정전압 제어를 수행할 경우, L-C 필터부에서 공진이 발생함으로써 출력전압이 흔들리고 시스템이 불안해진다. 본 논문에서, 출력전압제어의 안정성을 확보하기 위해 주필터부에 공진을 억제하는 댐핑회로를 새롭게 제안하고, 이에 적합한 제어방법을 소개한다. 제안한 댐핑회로는 R-L로서 소형이고 간단히 구성된다. 제어기에는 과도상태분의 궤환제어와 대역저지필터를 적용한다. 또한 전력회로는 3레벨 PWM방식을 적용하였다. 이로서 과도상태에서 출력전압의 흔들림없이 변동폭을 10[%]이하로 제어할 수 있었으며, 정상상태의 출력 전압 왜형율도 3[%]이하로 감소시켰다.