• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.11a
• /
• pp.340.1-340
• /
• 2002

The unbalance exciting force induced by HDD of lately getting higher speed is directly influenced by the rotational speed and the mechanical assembly allowance between disk and spindle motor, and which gives rise to the structure borne noise of the personal computer. The absolute unbalance mass of HDD needs to be measured and adjusted by the counter mass to control the unbalance exciting force effectively in the stage of assembling the disk and spindle motor. This study introduces the measurement methods of the magnitude of the absolute unbalance mass and the position of HDD by 2 accelerometers. The absolute unbalance mass can be obtained by the acceleration responses and the mobility of the mechanical part, while the position of the unbalance mass can e obtained by the rotation acceleration orbit.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2009.10a
• /
• pp.1051-1054
• /
• 2009

This paper investigates approaches for improving effective mobility of organic thin film transistors (OTFTs). We consider gate dielectric optimization, whereby we demonstrated >2x increase in mobility by using a silicon-rich silicon nitride ($SiN_x$) gate dielectric for polythiophene-based (PQT) OTFTs. We also engineer the dielectric-semiconductor ($SiN_x$-PQT) interface to attain a 27x increase in mobility (up to 0.22 $cm^2$/V-s) using an optimized combination of oxygen plasma and OTS SAM treatments. Augmentative material systems by combining 1-D nanomaterials (e.g., carbon nanotubes, zinc oxide nanowires) in an organic matrix for nanocomposite OTFTs provided a further boost in device performance.

• Journal of Periodontal and Implant Science
• /
• v.29 no.1
• /
• pp.193-207
• /
• 1999

The purpose of this study was to compare the clinical results of guided tissue regeneration(GTR) using a resorbable barrier manufactured from an copolymer of polylactic acid (PLA) and polylaetic-glycolic acid(PLGA) with those of nonresorbable ePTFE barrier. Thirty two patients(25 to 59 years old) with one radiographically evident intrabony lesion of probing depth ${\geq}$6mm participated in a 6-month controlled clinical trial. The subjects were randomly divided into three independent groups. The first group(n=8) received a ePTFE barrier. The second group (n=12) received a resorbable PLA/PLGA barrier. The third group (n=12) received a resorbable PLA/PLGA barrier combined with an alloplastic bone graft. Plaque index (PI), gingival index(GI), probing depth(PD), gingival recession, clinical attachment level(CAL), and tooth mobility were recorded prior to surgery and at 3, 6 months postsurgery, Statistical tests used to analyze these data included independent t-test, paired t-test, one-way ANOVA. The results were as follows : 1. Probing depth was significantly reduced in all groups at 3, 6 months postsurgery and there were not significant differences between groups. 2. Clinical attachment level was significantly increased in all groups at 3, 6 months postsurgery and there were not significant differences between groups. 3. There were not significant differences in probing depth, clinical attachment level, gingival recession, tooth mobility between second group (PLA/PLGA barrier) and third group (PLA/PLGA barrier combined with alloplastic bone graft) 4. Tooth mobility was not significantly increased in all groups at 3, 6 months postsurgery and there were not significant differences between groups. In conclusion, PLA/PLGA resorbable barrier has similar clinical potential to eP'IFE barrier in GTR procedure of intrabony pockets under the present protocol.

• Journal of Advanced Navigation Technology
• /
• v.23 no.4
• /
• pp.265-272
• /
• 2019

In this paper, we selected commuting scenarios in the most congested metropolitan area in Korea, and conducted noise analysis during personal air vehicle (PAV) operation using aviation environmental design tool (AEDT)software which was developed by Federal Aviation Administration (FAA). Noise is the second important factor after safety in order to operate PAVs through concepts such as ODM (on-demand mobility) introduced by National Aeronautics and Space Administration (NASA). Noise analysis were performed by modeling low-noise ePAVs as commercial helicopters and predicted residential suitability in order to resolve problems in which accurate NPD (noise power distance) data from PAVs were not released. The application of noise reduction technology such as electric propulsion has significantly reduced noise exposure levels and has reached the conclusion that commuting with PAVs is feasible without noise problems in the metropolitan area.

• Elastomers and Composites
• /
• v.53 no.4
• /
• pp.213-219
• /
• 2018

The degradation mechanism and physical properties of an FKM O-ring were observed with thermal aging in this experiment. From X-ray photoelectron spectroscopy (XPS) analysis, we could observe carbon (285 eV), fluoro (688 eV), and oxygen (531 eV) peaks. Before thermal aging, the concentration of fluoro atoms was 51.23%, which decreased to 8.29% after thermal aging. The concentration of oxygen atoms increased from 3.16% to 20.39%. Under thermal aging, the FKM O-ring exhibited debonding of the fluoro-bond by oxidation. Analysis of the C1s, O1s, and F1s peaks revealed that the degradation reaction usually occurred at the C-F, C-F2, and C-F3 bonds, and generated a carboxyl group (-COOH) by oxidation. Due to the debonding reaction and decreasing mobility, the glass transition temperature of the FKM O-ring increased from $-15.91^{\circ}C$ to $-13.79^{\circ}C$. From the intermittent CSR test, the initial sealing force was 2,149.6 N, which decreased to 1,156.2 N after thermal aging. Thus, under thermal aging, the sealing force decreased to 46.2%, compared with its initial state. This phenomenon was caused by the debonding reaction and decreasing mobility of the FKM O-ring. The S-S curve exhibited a 50% increase in modulus, with break at a low strain and stress state. This was also attributed to the decreasing mobility due to thermal aging degradation.

• Journal of the Korean Regional Science Association
• /
• v.6 no.1
• /
• pp.39-55
• /
• 1990

The principal measure of housing demand is income and the preferences expressed by households through their respective indifference curves. In this context, housing essentially becomes a derived demand, i.e., the household consumes land and a location (or distance-in time and money costs), according to its relative preferences for space, accessibility, and all other nonhousing goods. This paper attempts to deal with both aspects of housing (apartment) demand and household mobility in the Seoul Metropolitan Areas. Housing services will be measured using hedonic regression technique. From observations on the market prices of dwelling units and on the underlying characteristics of housing, one can estimte the relationships between the two empirically. In predicting the probability of the future moves into new towns in the Seoul Metropolitan areas, the best predictors of the future moves into new best predictors are found to be the degree of satisfaction not only with the current residence as a whole, but with some of the major amenities, accessibility and child education. The reasons for moving into new towns are diverse depending on the households' current situation; the most frequently cited is "improvement of housing conditions," followed by "improvement of living environment," "asset improvement" and "home ownership". It appears that people move houses because of a dissatisfaction with their current housing status, relative their income or needs, or a desire to improve their housing and neighborhood amenities, or both. On the other hand, it is clear that the development of new towns in the Seoul Metropolitan Areas should be based on the analysis of housing demand and the pattern of household mobility in Seoul housing market.sehold mobility in Seoul housing market.

• BMB Reports
• /
• v.31 no.6
• /
• pp.565-571
• /
• 1998

The expression of the endogenous human apolipoprotein(apo)E gene was significantly induced when HepG2 cells were treated with exogenous 25-hydroxy-cholesterol. This sterol-mediated apoE gene upregulation appears to require the participation of a positive element for the apoE gene transcription (PET) ( -169/ -140), a core sequence of upstream regulatory element (URE)1 enhancer of the human apoE gene. This PET was renamed as sterol regulatory element (SRE)4 based on its new role as a sensor for the level of intracellular sterol. Furthermore, a gel mobility shift analysis showed that binding activity of the SRE4 binding protein (BP) obtained from HepG2 cells was induced by sterol treatment, while that from either MCF7 or BT20 cells remained unchanged. Binding activity of SRE4BP was also induced in mouse macrophage cells, J774A.1, by sterol treatment, but it was drastically reduced when cells were subjected to treatment of AY-9944, a potent inhibitor for sterol synthesis. However, binding activity of Spl, which is a co-binding protein to the SRE4 region, remained the same in either condition, suggesting that SRE4BP (formally known as PETBP) may be mainly responsible for the sterol-mediated regulation of the apoE gene expression. Deletion analysis of the core binding site of SRE4BP by gel mobility shift assays showed that the minimal sequence of the SRE4BP binding appears to reside between -157 and -140, confirming the identity of SRE4 with the previously determined core sequence of URE1.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.5
• /
• pp.1659-1663
• /
• 2012

New semiconducting polymer, poly[1,4-bis(($E$)-2-(5-bromo-3-dodecylthiophen-2-yl)vinyl)benzene], was designed, synthesized and characterized. The structure of polymer was confirmed by $^1H$-NMR, IR and elemental analysis. The polymer was soluble in specific organic solvent. The weight-average molecular weights (MW) of polymer was found to be 11,000 with polydispersity of 1.82. UV-Visible absorption spectrum showed the maximum absorption at 428 nm (in solution) and 438 nm (in film). The highest occupied molecular orbital (HOMO) energy of the polymer is -5.36 eV by measuring cyclic voltammetry (CV). A solutionprocessed polymer thin film transistor device shows a mobility of $8.59{\pm}10^{-4}\;cm^2\;V^{-1}\;s^{-1}$, an on/off current ratio of $2.0{\times}10^4$.

• Journal of the Korean Ceramic Society
• /
• v.40 no.3
• /
• pp.262-267
• /
• 2003

The heteroepitaxial ZnO thin film on sapphire (0001) substrate was prepared by an off-axis Radio Frequency(RF) magnetron sputtering. The crystallinity of ZnO thin film was affected by deposition pressure, RF power, and substrate temperature. High quality heteroepitaxial ZnO thin film was obtained when the kinetic energy of sputtered particles is well harmonized with the surface mobility. In the result of Photoluminescence(PL) of heteroepitaxial ZnO thin film, Ultraviolet(UV) emissions at 3.36 and 3.28 eV were observed at low(17 K) and Room Temperature(RT). respectively. As the ZnO thin film was annealed in O$_2$ambient, the crystallinity was improved while UV emission was drastically decreased.

• Journal of Digital Contents Society
• /
• v.11 no.3
• /
• pp.341-348
• /
• 2010

Unlike host-based IPv6 mobility support protocols such as Mobile IPv6 (MIPv6), Hierarchical Mobile IPv6 (HMIPv6), and Fast handover for Mobile IPv6 (FMIPv6), Proxy Mobile IPv6 (PMIPv6) is expected to accelerate the real deployment of IPv6 mobility support protocol by using only collaborative operations between the network entities without mobile node (MN) being involved. In this paper, we analyze and compare the handover latency of network-based IPv6 mobility support protocol (i.e., PMIPv6) with the representative host-based IPv6 mobility support protocols such as MIPv6, HMIPv6, and FMIPv6. Analytical results show that the handover latency of PMIPv6 is considerably lower than those of MIPv6 and HMIPv6, and the handover latency of PMIPv6 becomes lower than that of FMIPv6 in case the wireless link delay is greater than the delay between mobile access gateway (MAG) and local mobility anchor (LMA).