• 비파괴검사학회지
• /
• 제29권6호
• /
• pp.570-578
• /
• 2009

Excitation and propagation of guided waves are very complex problems in pipes due to their dispersive nature. Pipes are commonly used in the oil, chemical or nuclear industry and hence must be inspected regularly to ensure continued safe operation. The normal mode expansion(NME) method is given for the amplitude with which any propagating waveguide mode is generated in the pipes by applied surface tractions. Numerical results are calculated based on the NME method using different sources, i.e., non-axisymmetric partial loading and quasi-axisymmetric loading sources. The sum of amplitude coefficients for 0~nineth order of the harmonic modes are calculated based on the NME method and the dispersion curves in pipes. The superimposed total field which is namely the angular profile, varies with propagating distance and circumferential angle. This angular profile of guided waves provides information for setting the transducer position to find defects in pipes.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2010년도 춘계학술대회 논문집
• /
• pp.1697-1702
• /
• 2010

It has been recognized for decades that the spherical bearing which is sliding on curved surface in the intrinsic behavior is optimized for the railway bridge requiring a large slope deflection. However, the spherical bearing is easily corrosived at the PSC girder bridge which is exposed to the outside so the normal function of bridge bearing is not fulfilled fully. It is common that the corrosion is happened at the operating plate of steel bridge bearing and generally it is necessary to replace the bridge bearing after 20~25 years. Accordingly, It costs multi billion dollars for maintenance each year and the necessity of improvement become a issue. Korea Rail Network Authority(KR) suggested to apply the Elastomeric bearing instead of Spherical bearing through the task of construction site of 2006. But the normal Elastomeric bearing is optimized for the Highway bridge so it needs the special consideration to satisfy each design condition required by railway bridge. As the result of examination of Elastomeric bearing at the railway bridge construction site, the stress is decreased by effective dispersion of earthquakes and the maintenance fee is also decreased.

• 천문학회지
• /
• 제41권4호
• /
• pp.83-98
• /
• 2008

In an attempt of clarifying the connection between the photospheric abundance anomalies and the stellar rotation as well as of exploring the nature of "normal A" stars, the abundances of seven elements (C, O, Si, Ca, Ti, Fe, and Ba) and the projected rotational velocity for 46 A-type field stars were determined by applying the spectrum-fitting method to the high-dispersion spectral data obtained with BOES at BOAO. We found that the peculiarities(underabundances of C, O, and Ca; an overabundance of Ba) seen in slow rotators efficiently decrease with an increase of rotation, which almost disappear at $v_esin\;i{\gtrsim}100km\;s^{-1}$. This further suggests that stars with sufficiently large rotational velocity may retain the original composition at the surface without being altered. Considering the subsolar tendency(by several tenths dex below) exhibited by the elemental abundances of such rapidly-rotating (supposedly normal) A stars, we suspect that the gas metallicity may have decreased since our Sun was born, contrary to the common picture of galactic chemical evolution.

• Journal of Ginseng Research
• /
• 제45권2호
• /
• pp.228-235
• /
• 2021

Backgroud: Ginsenoside compound K (GK) is a major metabolite of protopanaxadiol-type ginsenosides and has remarkable anticancer activities in vitro and in vivo. This work used an ionic cross-linking method to entrap GK within O-carboxymethyl chitosan (OCMC) nanoparticles (Nps) to form GK-loaded OCMC Nps (GK-OCMC Nps), which enhance the aqueous solubility and stability of GK. Methods: The GK-OCMC Nps were characterized using several physicochemical techniques, including x-ray diffraction, transmission electron microscopy, zeta potential analysis, and particle size analysis via dynamic light scattering. GK was released from GK-OCMC Nps and was conducted using the dialysis bag diffusion method. The effects of GK and GK-OCMC Nps on PC3 cell viability were measured by using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay. Fluorescent technology based on Cy5.5-labeled probes was used to explore the cellular uptake of GK-OCMC Nps. Results: The GK-OCMC NPs had a suitable particle size and zeta potential; they were spherical with good dispersion. In vitro drug release from GK-OCMC NPs was pH dependent. Moreover, the in vitro cytotoxicity study and cellular uptake assays indicated that the GK-OCMC Nps significantly enhanced the cytotoxicity and cellular uptake of GK toward the PC3 cells. GK-OCMC Nps also significantly promoted the activities of both caspase-3 and caspase-9. Conclusion: GK-OCMC Nps are potential nanocarriers for delivering hydrophobic drugs, thereby enhancing water solubility and permeability and improving the antiproliferative effects of GK.

• 한국산업경영시스템학회:학술대회논문집
• /
• 한국산업경영시스템학회 2002년도 춘계학술대회
• /
• pp.37-44
• /
• 2002

In order to review the failure rate of PC monitor under normal environmental conditions, we experimented for various levels of each factors, e.g Power on/off, DPM mode, using voltage, Incoming Surge, Torque strength etc. According to the results of experiment and SN ratios we investigated that the causes of the failure for the horizontal output TR of monitor are Mode change, dispersion of Torque and $h_{FE}$ and these are critical effect. For the new reliability test we suggested that strengthened part tests In IQC branch, Torque change controls in the TR specification are necessary.

• Annals of Clinical Neurophysiology
• /
• 제4권2호
• /
• pp.98-107
• /
• 2002

Multifocal motor neuropathy (MMN) is a chronic immune-mediated peripheral myelinopathy. The major clinical features include slowly progressive, painless, and asymmetric weakness, usually of distal limb muscle. Early in the course of the disease, weakness is not necessarily associated with muscle atrophy, owing to the initial primary involvement of peripheral myelin. Chronic progressive weakness is often associated with some degree of concurrent axonal loss and subsequent muscle atrophy. Sensory symptoms are usually mild or absent, and involvement of cranial and respiratory muscles is rare. The findings of multifocal motor conduction block, abnormal temporal dispersion, and focal conduction slowing at segments not at risk for common entrapment or compression injury, associated with normal sensory conduction studies along the same segments, are the hallmark electrophysiologic features of MMN. The slow progression and absence of upper motor neuron signs are the major clinical points that separate MMN from amyotrophic lateral sclerosis. The role of GM1 antibodies, found in high titers in 22~84% of MMN patients, remains uncertain. The contention that MMN is an autoimmune disorder is largely based on the often dramatic improvement in symptoms following the administration of intravenuos immunoglobulin or cyclophosphamide.

• 대한기계학회논문집
• /
• 제15권6호
• /
• pp.2181-2188
• /
• 1991

본 연구에서는 주파수도메인에서의 측정방법중 진폭 스펙트럼 방법에 대한 이 론적 배경을 알아보고, 얇은 두께의 재료에 적용한 측정결과를 보이고자 하며, 비교적 두께가 두꺼운 재료에서의 측정결과를 위상 스펙트럼 방법으로의 측정 결과와 비교하 여 측정의 정확성을 서로 비교하였다.

• Nuclear Engineering and Technology
• /
• 제11권2호
• /
• pp.127-132
• /
• 1979

원자력 시설에서 방사선 방출에 의한 주거 인구에 미치는 영향을 분석평가하는데 부지의 기상 조건을 직접 관련시키는 방법을 고려해 보았다. 이 방법은 정상가동시에 누출되는 방사능과 가상사고시의 누출로 부터 자연환경에 주는 영향을 보다 현실에 맞게 평가하는데 사용될 수 있다. 개개인이 받을 방사선량과 전체인구가 받을 피폭선량을 보다 논리적으로 계산함으로써 설비 설계에 반영하여 누출량과 대기내의 화산을 별도로 분석하여 평가하는 재래식 방법으로 부터 초래되는 필요 이상의 안전설계를 지양할 수 있다.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
• /
• pp.284-287
• /
• 2004

A high ductile fiber reinforced mortar has been developed by employing micromechanics-based design procedure. Micromechanical analysis was initially performed to properly select water-cement ratio, and then optimal mixture proportion was determined based on workability considerations, including desirable fiber dispersion without segregation. Subsequent direct tensile tests revealed that the fiber reinforced mortar exhibited high ductile uniaxial tension property, represented by $1.8\%$ strain capacity, which is around 100 times the strain capacity of normal concrete.

• International Journal of Reliability and Applications
• /
• 제4권3호
• /
• pp.97-111
• /
• 2003

By applying Theorem 2.6.4 (Fang and Zhang, 1990, p.66) the dispersion matrix of a multivariate power exponential (MPE) distribution is derived. It is shown that the MPE and the gamma distributions are related and thus the MPE and chi-square distributions are related. By extending Fang and Xu's Theorem (1987) from the normal distribution to the Univariate Power Exponential (UPE) distribution an explicit expression is derived for calculating the probability of an UPE random variable over an interval. A representation of the characteristic function (c.f.) for an UPE distribution is given. Based on the MPE distribution the probability density functions of the generalized non-central chi-square, the generalized non-central t, and the generalized non-central F distributions are derived.