• Journal of Ecology and Environment
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• v.33 no.4
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• pp.289-298
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• 2010

A number of characteristics of the Lake H$\ddot{o}$vsg$\ddot{o}$l watershed, such as the lake's location at the edge of the Central Asian continuous permafrost zone, provide a unique opportunity to evaluate possible anthropogenic impacts in this remote area in northern Mongolia. In this study, we compared stream solute concentrations in six sub-watersheds in the Lake H$\ddot{o}$vsg$\ddot{o}$l watershed. Water samples were collected during the summer months between 2003 and 2005. Concentrations of $Cl^-$ ranged from 9.8 to $51.3\;{\mu}mol/L$; average nitrate concentrations were very low and ranged from undetectable to $1.1\;{\mu}mol/L$ and average ${SO_4}^{2-}$ concentration at sampling stations with minimal animal grazing ranged from 66 to $294\;{\mu}mol/L$. Average dissolved organic carbon (DOC) concentrations ranged from 642 to $1,180\;{\mu}mol$ C/L. We did not find statistically significant differences in DOC concentrations among the six streams, although DOC concentrations tended to be higher in the two northernmost streams, possibly related to differences in the active layer above the permafrost. Dissolved organic nitrogen (DON) concentrations were correlated with DOC concentration, and followed the same spatial pattern as those for DOC. In streams in this remote watershed, total dissolved nitrogen was made up of mostly organic N, as has been found for other regions distant from anthropogenic N sources. Overall, these results suggest that future research on the dynamics of DOC and DON in this watershed will be especially insightful in helping to understand how changes in climate and land use patterns will affect transformations, retention, and export of dissolved organic matter within these sub-watersheds in the Lake H$\ddot{o}$vsg$\ddot{o}$l region.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.3
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• pp.189-196
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• 2018

Propeller performance measurement system for high altitude UAV was designed and applied to the wind tunnel test for 2 propeller models with a diameter around 1 m. Mechanical power of the propeller was directly measured by using the torque sensor installed on the rotating axis. The thrust of whole operation body including the propeller was measured by thrust road cell. The guide rail system was suggested to reduce the weight influence of operation body on the thrust road cell. The influence of each measured variables on the aerodynamic coefficients was studied with the repeatability and uncertainty analysis. This analysis result shows that the accuracies of the road cell and the wind velocity were major factors for the thrust coefficient. Propeller performance with typical RPM was measured with various wind speeds and the test results was summarized by performance coefficients for 5 different RPM.

• Journal of Periodontal and Implant Science
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• v.32 no.4
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• pp.811-825
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• 2002

Recently, many natural medicines, whose advantages are less side effects and possibility of long-term use, have been studied for their capacity, their anti-bacterial and anti-inflammatory effects and regenerative potential of periodontal tissues. Cervi Parvum Comu(CPC) have been traditionally study as an hale, growth. hematogenous, anti-aging, hack pain in Eastern medicine. The purpose of present study was to investigate the effects of CPC extract on cell cycle progression and its molecular mechanism in human fetal osteoblasts. CPC extracts (10 ${\mu}g/ml$) increased cell proliferation in the human fetal osteoblasts compared to non-supplemented control. There was no significant change in the G1 and S phase, hut a increase in the G2/M phase in 10 ${\mu}g/ml$ and 100 ${\mu}g/ml$ of CPC extracts group as compared to non-supplemented control. The protein expression of cyclin E, cdk 2, cycln D, cdk 4, and cdk 6 was higher than that of control group. The level of p21 was lower than that of control. But that of pRb and pl6 was not distinguished from control. These results indicate that the increase of cell proliferation by CPC extracts may be due t o the increased expression of cyclin E, cdk 2, cyclin D, cdk 4 and cdk 6, and the decreased expression of p21 in human fetal osteoblasts.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.42 no.1
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• pp.20-30
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• 2016

Objectives: To validate a critical-size mandibular bone defect model in miniature pigs. Materials and Methods: Bilateral notch defects were produced in the mandible of dentally mature miniature pigs. The right mandibular defect remained untreated while the left defect received an autograft. Bone healing was evaluated by computed tomography (CT) at 4 and 16 weeks, and by micro-CT and non-decalcified histology at 16 weeks. Results: In both the untreated and autograft treated groups, mineralized tissue volume was reduced significantly at 4 weeks post-surgery, but was comparable to the pre-surgery levels after 16 weeks. After 16 weeks, CT analysis indicated that significantly greater bone was regenerated in the autograft treated defect than in the untreated defect (P=0.013). Regardless of the treatment, the cortical bone was superior to the defect remodeled over 16 weeks to compensate for the notch defect. Conclusion: The presence of considerable bone healing in both treated and untreated groups suggests that this model is inadequate as a critical-size defect. Despite healing and adaptation, the original bone geometry and quality of the pre-injured mandible was not obtained. On the other hand, this model is justified for evaluating accelerated healing and mitigating the bone remodeling response, which are both important considerations for dental implant restorations.

• Journal of Aerospace System Engineering
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• v.11 no.5
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• pp.56-64
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• 2017

A high altitude long endurance aircraft which carries out missions of environmental research communication relay or ground surveillance, should have the capacity to cruise in the stratosphere at a relatively low speed for a long dwell time without the necessity of refueling. When one considers the propulsion system for such an aircraft, a reciprocating engine with a serial turbo-charger system to boost rarefied ambient air up to sea level condition, would represent an good, informed and practical choice regardless of the cruising altitude of the aircraft. In this paper, high altitude long endurance aircraft developed by overseas research groups and research trends, regarding multi-stage turbocharger systems, are introduced.

• Clinical and Experimental Reproductive Medicine
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• v.47 no.2
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• pp.122-129
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• 2020

Objective: The survival of a semi-allogeneic fetus depends on several immunological mechanisms, and it has been suggested that recurrent pregnancy loss (RPL) could develop as a result of one or more immunological abnormalities. Methods: Compatibility between partners for human leukocyte antigen (HLA) genotypes and the relationships between maternal killer-cell immunoglobulin-like receptor (KIR) and paternal HLA-Bw4/Bw6 and HLA-C1/C2 supra-groups were investigated in 25 couples with RPL in comparison to healthy couples with children. HLA and KIR genotyping was performed using polymerase chain reaction with sequence-specific primers and/or sequence-specific oligonucleotides. Results: HLA class I incompatibility between partners, especially in HLA-B alleles, was more common in the RPL group (p= 0.01). HLA-C2 homozygosity was more frequent in the male partners of RPL couples than in other groups (p= 0.03). The KIR2DL5 gene frequency was significantly higher in both the female and male partners of RPL couples, whereas the KIR2DS3 gene frequency in male partners of RPL couples was significantly reduced (p= 0.03). The presence of KIR2DL3 in women with RPL was correlated with the presence of HLA-C2 alleles in their spouses (p= 0.03). Conclusion: Our data from a Turkish population suggest that male HLA-C2 homozygosity may play an important role in RPL. Additionally, an incidental match between male HLA-C2 and female HLA-C1 ligand KIR receptors might perturb the balance between activatory and inhibitory KIR-ligand interactions during pregnancy in couples affected by RPL. The roles of orphan KIR2DL5 and orphan KIR2DS3 in RPL remain obscure.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.4
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• pp.393-404
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• 2014

Unmanned aerial vehicles (UAVs) have been applied to not only military missions like surveillance and reconnaissance but also commercial missions like meteorological observation, aerial photograph, communication relay, internet network build and disaster observation. Fuel cells make UAVs eco-friendly by using hydrogen. Proton exchange membrane fuel cells (PEMFCs) show low operation temperature, high efficiency, low noise and high energy density and those characterisitcs are well fitted with UAVs. Thus Fuel cell based UAVs have been actively developed in the world. Recently, fuel cell UAVs have started to develope for high altitude UAVs because target altitude of UAVs is expanded upto stratosphere altitude. Long endurance of UAVs is essential to improve effects of the missions. Improvement of UAV endurance time could be fulfilled by developing a hydrogen fuel storage system with high energy density and reducing the weight of UAVs. In this paper, research trend and analysis of fuel cell UAVs are introduced in terms of their altitude and endurance time and then the prospect of fuel cell UAVs are shown.

• Archives of design research
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• no.16
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• pp.113-122
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• 1996

ilesi gn is on process. j)esign is not a result, but a process, It requires organizatiun ui design process to ubtain the most efiectivc design. The urganizatiun of design process means to understand the inner ur outer problems. to cr-eate r-esonable process, and to hale ability of problem soiving, In this paper, we suggest lhal student need to understand the importance oi 'discovering \ulcornerrOCeflB'. not 'd iscovered process'. _\ nd we also SUi(\{est text model of instructor with respeCl to the basic concept of creative ability and den]opmcnt of imagination ahality.

• Journal of Astronomy and Space Sciences
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• v.30 no.4
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• pp.241-246
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• 2013

We have investigated drought periodicities occurred in Seoul to find out any indication of relationship between drought in Korea and solar activities. It is motivated, in view of solar-terrestrial connection, to search for an example of extreme weather condition controlled by solar activity. The periodicity of drought in Seoul has been re-examined using the wavelet transform technique as the consensus is not achieved yet. The reason we have chosen Seoul is because daily precipitation was recorded for longer than 200 years, which meets our requirement that analyses of drought frequency demand long-term historical data to ensure reliable estimates. We have examined three types of time series of the Effective Drought Index (EDI). We have directly analyzed EDI time series in the first place. And we have constructed and analyzed time series of histogram in which the number of days whose EDI is less than -1.5 for a given month of the year is given as a function of time, and one in which the number of occasions where EDI values of three consecutive days are all less than -1.5 is given as a function of time. All the time series data sets we analyzed are periodic. Apart from the annual cycle due to seasonal variations, periodicities shorter than the 11 year sunspot cycle, ~ 3, ~ 4, ~ 6 years, have been confirmed. Periodicities to which theses short periodicities (shorter than Hale period) may be corresponding are not yet known. Longer periodicities possibly related to Gleissberg cycles, ~ 55, ~ 120 years, can be also seen. However, periodicity comparable to the 11 year solar cycle seems absent in both EDI and the constructed data sets.

• Advances in aircraft and spacecraft science
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• v.6 no.2
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• pp.117-144
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• 2019

High Altitude and Long Endurance (HALE) aircraft are capable of providing intelligence, surveillance and reconnaissance (ISR) capabilities over vast geographic areas when equipped with advanced sensor packages. As their use becomes more widespread, the demand for additional range, endurance and payload capability will increase and designers are exploring non-conventional configurations to meet the increasing demands. One such configuration is the joined-wing concept. A joined-wing aircraft is one that typically connects a front and aft wings in a diamond shaped planform. One such example is the Boeing SensorCraft configuration. While the joined-wing configuration offers potential benefits regarding aerodynamic efficiency, structural weight, and sensing capabilities, structural design requires careful consideration of elastic buckling resulting from the aft wing supporting, in compression, part of the forward wing structural loading. It has been shown already that this is a nonlinear phenomenon, involving geometric nonlinearities and follower forces that tend to flatten the entire configuration, leading to structural overload due to the loss of the aft wing's ability to support the forward wing load. Severe gusts are likely to be the critical design condition, with flight control system interaction in the form of Gust Load Alleviation (GLA) playing a key role in minimizing the structural loads. The University of Victoria Center for Aerospace Research (UVic-CfAR) has built a 3-meter span scaled and flexible wing UAV based on the Boeing SensorCraft design. The goal is to validate the nonlinear structural behavior in flight. The main objective of this research work is to perform Ground Vibration Tests (GVT) to characterize the dynamic properties of the scaled flight vehicle. Results from the experimental tests are used to characterize the modal dynamics of the aircraft, and to validate the numerical models. The GVT results are an important step towards a safe flight test program.