• The Bulletin of The Korean Astronomical Society
• /
• v.42 no.2
• /
• pp.37.1-37.1
• /
• 2017

Since the seminal work of Perrin, physicists have understood in the context of kinetic theory how ink slowly diffuses in a glass of water. The fluctuations of the stochastic forces acting on water molecules drive the diffusion of the ink in the fluid. This is the archetype of a process described by the so-called fluctuation-dissipation theorem, which universally relates the rate of diffusion to the power spectrum of the fluctuating forces. For stars in galaxies, a similar process occurs but with two significant differences, due to the long-range nature of the gravitational interaction: (i) for the diffusion to be effective, stars need to resonate, i.e. present commensurable frequencies, otherwise they only follow the orbit imposed by their mean field; (ii) the amplitudes of the induced fluctuating forces are significantly boosted by collective effects, i.e. by the fact that, because of self-gravity, each star generates a wake in its neighbours. In the expanding universe, an overdense perturbation passing a critical threshold will collapse onto itself and, through violent relaxation and mergers, rapidly converge towards a stationary, phase-mixed and highly symmetric state, with a partially frozen orbital structure. The object is then locked in a quasi-stationary state imposed by its mean gravitational field. Of particular interests are strongly responsive colder systems which, given time and kicks, find the opportunity to significantly reshuffle their orbital structure towards more likely configurations. This presentation aims to explain this long-term reshuffling called gravity-driven secular evolution on cosmic timescales, described by extended kinetic theory. I will illustrate this with radial migration, disc thickening and the stellar cluster in the galactic centre.

• International Journal of Costume and Fashion
• /
• v.9 no.1
• /
• pp.34-43
• /
• 2009

This study compared the thermal comfort of indoor clothing from Tencel material that is getting higher in demand due to being eco-friendly with superior wettability, with that from Polyester material that despite being most widely used for indoor clothing, rapidly discharges body sweat due to low wettability. The experiments were performed in the two manners, objective evaluation under the conditions of an artificial climate chamber and subjective evaluation of wearing the given clothes at home followed by filling in the questionnaire. Subjects were 8 healthy elderly women in their 60's who spend majority of their time at home rather than in social activities, and comparison was made on skin temperature and humidity inside clothing at exercise and relaxation states under early summer environment. Based on these results, wearing Tencel material clothing maintained cooler temperatures under warm environment rather than when wearing Polyester material clothing, thus enabling activities under more comfortable state. Regarding humidity inside clothing, parts with twofold clothing did not show difference between Tencel and Polyester, but the onefold arm showed lower when wearing Tencel. With this results, Tencel is regarded as more comfortable and nicer than Polyester.

• Journal of computational fluids engineering
• /
• v.21 no.1
• /
• pp.86-93
• /
• 2016

In this paper, heat transfer characteristics of pulsating heat pipes are investigated with the diameter and the number of tubes through the computational analysis of thermal flow. The numerical simulation includes the phase change precess with VOF model using OpenFOAM software. The numerical code is modified for the phase change to occur with saturation temperature. The numerical results are compared with the previous ones to validate the present code. The resonable results have been obtained based on the mass transfer time relaxation parameter considering the density ratio. When the ratio of length to diameter and the number of tubes are on the decrease, the thermal resistances also tends to decrease in the pulsating heat pipes. These numerical results will supply the base line data to design and to manufacture the pulsating heat pipe.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.13 no.5
• /
• pp.85-98
• /
• 1993

A method of analysis for the material and geometric nonlinear analysis of planar prestressed concrete cable-stayed bridges including the time-dependent effects due to load history, creep, shrinkage, aging of concrete and relaxation of prestress is described. The analysis procedure, based on the finite element method, is capable of predicting the response of these structures through elastic, cracking, inelastic and ultimate ranges. The nonlinear formulation for the description of motion is based on the updated Lagrangian approach. To account for the material nonlinearity, nonlinear stress-strain relationship and cracking of concrete, nonlinear stress-strain relationships of reinforcing steel, prestressing steel, and cable, including load reversal are given. Results from a numerical examples on ultimate analyses of cable-stayed bridges are presented to illustrate the analysis method.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.12 no.4 s.27
• /
• pp.307-312
• /
• 2006

The necessity of improving manning standards in the Ship Officer's Act has recently been strongly advocated by the fisheries industry. The fisheries industry maintained the position of the relaxation cf current manning standards. However, the Labor unions, Marine Officers Association, and Radio Officers' Association persisted to strengthen the standards or to keep the current standards. This paper studies the appropriateness of current manning standards and proposes its improvement scheme to secure the safe operation of vessels.

• Women's Health Nursing
• /
• v.6 no.2
• /
• pp.305-315
• /
• 2000

The purpose of this study was to explore the psychoneuroimmunologic effect of aromatherapy massage and to compare the effect with that of massage. This study is designed as a nonequivalent control group pretest-posttest quasi-experimental study and each twenty postpartum mothers volunteered the experimental group and control group. For experimental group, researcher used massage with 2% Jojova oil mixed with Lavender and Rosemary oil (Bush Boake Allen Inc., USA) for 20 minutes, whereas for control group Jojova oil was used as luburicant for massage. Skin temperature was measured with YSI Tele-thermometer(Simpson electric Co., USA) and the concentration of IgA in salivary was analyzed by immunoturbididimetric assay(Cobas INTEGRA, Roche, Swiss) at pre and post test. Also at this time fatigue were measured by Rhoten Fatigue Scale through self-report. The data were analyzed using SAS and hypothesis was tested with unpaired t-test. The results were as follows : 1) Score of fatigue decreased significantly after use of aromatherapy massage. 2) Skin temperature increased significantly after use of aromatherapy massage. 3) Concentration of salivary IgA increased significantly after use of aromatherapy massage. In conclusion, from the standpoint of psychoneuroimmunologic view, the results suggest that aromatherapy massage have greater effect compared with massage and can be effective nursing intervention to enhance relaxation of mind and body in the postpartum mothers.

• Journal of the Korean Chemical Society
• /
• v.26 no.4
• /
• pp.205-209
• /
• 1982

Anisotropic rotation of $CDCl_3$ in neat liquid is investigated by the analysis of ${\nu}_1$ band of Raman spectrum and the diffusion constant($D_{\perp}$) for the tumbling motion is obtained. The diffusion constant ($D_{II}$) for the spinning motion is obtained from the above $D_{\perp}$ value and the chlorine-35 nuclear quadrupole relaxation time. The diffusion constants thus obtained seem to agree very well with the ones obtained from $^2H$ and $^35C$l in NQR results within experimental errors. The data suggest fairly anisotropic character of reorientational motions in neat $CDCl_3$.

• Korean Journal of Optics and Photonics
• /
• v.6 no.1
• /
• pp.33-38
• /
• 1995

We have measured the excited state absorption in $Ce:YAlO_{3}$, crystals for the first time and assigned it for a 5d$\rightarrow$conduction band transition. Two broad absorption bands were observed at 555 nm and 465 nm fowllowing the 308 nm XeCl laser excitation and their cross sections and oscillator strengths were calculated. We have also measured the fluorescence lifetimes in between 300 K and 700 K to study the nonradiative relaxation from the lowest 5d state of $Ce^{3+}$ ions and explained ESA and the transition process from the state in terms of a configurational coordinate.dinate.

• Korean Journal of Clinical Pharmacy
• /
• v.10 no.3
• /
• pp.120-124
• /
• 2000

Diltiazem inhibits calcium channels and leads to vascular smooth muscle relaxation and negative inotroic and chronotropic effects in the heart. Diltiazem (DTZ) is almost completely absorbed after oral administration, but its bioavailability is reduced because of considerable hepatic first-pass metabolism. The main metabolite of DTZ is deacetyldiltiazem. The purpose of this study was to report the pharmacokinetic changes of DTZ and its metabolite, deacetyldiltiazem (DAD) after intravenous administration of diltiazem to control rabbits and rabbits with mild and medium folate-induced renal failure (FIRRs). The area under the plasma concentration-time curves (AUC) of DTZ were significantly increased in mild and medium FIRRs. The metabolite ratio of the DAD to DTZ were significantly decreased in mild and medium FIRRs. The elimination rate constant $(\beta)$ and total body clearances (CLt) of DTZ were significantly decreased in mild and medium FIRRS. These findings suggest that the hepatic metabolism of diltiazem was inhibited and CLt and ${\beta}$ of DTZ were significantly decreased in mild and in rabbits with medium folate-induced renal failure.

• Advances in Computational Design
• /
• v.2 no.3
• /
• pp.211-223
• /
• 2017

This research presented a numerical and experimental study on the seismic performance of first-generation base-isolated and fixed-base nuclear power plants (NPP). Three types of the base isolation system were applied to rehabilitate the first-generation nuclear power plants: frictional pendulum (FP), high-damping rubber (HDR) and lead-rubber (LR) base isolation. Also, an Excel program was proposed for the design of the abovementioned base isolators in accordance with UBC 97 and the Japan Society of Base Isolation Regulation. The seismic assessment was performed using the pushover and nonlinear time history analysis methods in accordance with the FEMA 356 regulation. To validate the adequacy of the proposed design procedure, two small-scale NPPs were constructed at Universiti Teknologi Malaysia's structural laboratory and subjected to a pushover test for two different base conditions, fixed and HDR-isolated base. The results showed that base-isolated structures achieved adequate seismic performance compared with the fixed-base one, and all three isolators led to a significant reduction in the containment's tension, overturning moment and base shear.