• The Bulletin of The Korean Astronomical Society
• /
• v.43 no.1
• /
• pp.33.1-33.1
• /
• 2018

The differential rotational properties of early-type galaxies (ETGs) revealed by integral field spectroscopy surveys is arguably one of the most exciting findings in the galaxy evolution study during the past decade. Numerical studies have shown that galaxy mergers under various configurations can reproduce the observed distribution of ETG spin. However, we suggest an alternative scenario for the spin evolution of a large fraction of ETGs. Using the Horizon-AGN simulation, we follow the spin evolution of 10037 color-selected ETGs more massive than 1010 Msun that are divided into four groups: cluster centrals (3%), cluster satellites (33%), group centrals(5%), and field ETGs (59%). We find a strong mass dependence of the slow rotator fraction, fSR, and the mean spin of massive ETGs. Although the environmental dependence is not clear in the fSR, it is visible in the mean value of the spin parameter. The environmental dependence is driven by the satellite ETGs whose spin gradually decreases as their environment becomes denser. Galaxy mergers appear to be the main cause of total spin changes in 94% of central ETGs of halos with Mvir > 1012.5 Msun, but only 22% of satellite and field ETGs. We find that non-merger induced tidal perturbations better correlate with the galaxy spin-down in satellite ETGs than mergers. Given that the majority of ETGs are not central in dense environments, we conclude that non-merger tidal perturbation effects played a key role in the spin evolution of ETGs observed in the local (z < 1) universe.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.36 no.8
• /
• pp.897-904
• /
• 2012

The rifling design problem has continuous-type shape variables and an integral number of riflings. In addition, it requires considerable time for analysis because its behavior should be described by a nonlinear finite element model (FEM). Therefore, this study presents an efficient design process for rifling based on a design of experiment (DOE) approach. First, Bose's orthogonal array is used to represent 25 runs for four design variables including three shape variables and one integer variable. Then, nonlinear FE analyses are performed. Next, to minimize the bullet resistance without affecting the bullet velocity and bullet rotational angle immediately before a bullet leaves the gun barrel, a what-if design is performed. In the proposed what-if design, a functional including the design objective and constraints is constructed and effect analysis is performed by using the functional. It is found that the new design obtained from the what-if design shows better results than the current one.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.3
• /
• pp.467-472
• /
• 2006

This study has been done to design a precise system and develop position control algorithm to control a Composite Smoke Bomb Azimuth driving apparatus of a BLDC servo motor. Having to Blind the sight of opposite tank. the Smoke Bomb Rotational driving system needs instant response that is able to detect opponent appearance and blast the bomb at a short time. So a design that shows fast current response capability or $300[Hz]\sim500[Hz]$ is proposed. in the MIN-MAX PWM technology is used to increase the operational speed. in order to control the blasting position, a precision position control algorithm that utilizes the integral value of speed trajectory is suggested. Also these characteristics are monitored and assessed by the PC based monitoring program which shows the graphs of current, voltage, position, and speed parameters. The main controller is based on a TMS320VC33 high performance floating-point DSP(Digital Signal Process) and the PWM generator utilizes EPM7128 CPLD.

• The Bulletin of The Korean Astronomical Society
• /
• v.41 no.1
• /
• pp.40.1-40.1
• /
• 2016

Recent integral-field spectrograph surveys have found that similar-looking early type galaxies have wide range of rotational properties (Emsellem et al. 2007). This finding initiated a new point of view to the galaxies; rotation of galaxy as the first parameter of galaxy classification (Emsellem et al. 2011, Cappellari et al. 2011, for example). Some theoretical studies tried to address the origin of galaxy rotation. Idealized galaxy merger simulations have shown that galaxy-galaxy interactions have significant effects on the rotation of galaxies. Cosmological simulations by Naab et al. 2014 also added some more insights to the rotation of galaxies. However, previous studies either lack cosmological background or have not enough number of samples. Running a set of cosmological hydrodynamic zoom-in simulations using the AMR code RAMSES(Teyssier 2002). we have constructed a sample of thousands of galaxies in 20 clusters. Here we present a kinematic analysis of a large sample of galaxies in the cosmological context. The overall distribution of rotation parameter of simulated galaxies suggests a single peak corresponding to fast rotating galaxies. But when divided by mass, we find a strong mass dependency of galaxy rotation, and massive galaxies are distinctively slow rotating. The cumulated effective of mergers seems to neutralize galaxy rotation as suggested by previous studies (Khochfar et al. 2011, Naab et al. 2014, and Moody et al. 2014). This is consistent with the fact that massive galaxies tend to rotate more slowly after numerous mergers. However, if seen individually, merger can either increase or decrease galaxy rotation depending on mass ratio, orbital parameter, and relative rotation axis of the two galaxies. This explains the existence of some non-slow rotating massive early type galaxies.

• Journal of Neurogastroenterology and Motility
• /
• v.24 no.4
• /
• pp.570-576
• /
• 2018

Background/Aims Swallows with viscous or solid boluses in different body positions alter esophageal manometry patterns. Limitations of previous studies include lack of standardized viscous substrates and the need for chewing prior to swallowing solid boluses. We hypothesize that high-resolution impedance manometry (HRiM) using standardized viscous and super-viscous swallows in supine and upright positions improves sensitivity for detecting esophageal motility abnormalities when compared with traditional saline swallows. To establish normative values for these novel substrates, we recruited healthy volunteers and performed HRiM. Methods Standardized viscous and super-viscous substrates were prepared using "Thick-It" food thickener and a rotational viscometer. All swallows were administered in 5-mL increments in both supine and upright positions. HRiM metrics and impedance (bolus transit) were calculated. We used a paired two-tailed t test to compare all metrics by position and substrate. Results The 5-g, 7-g, and 10-g substrates measured 5000, 36 200, and 64 $700mPa{\cdot}sec$, respectively. In 18 volunteers, we observed that the integrated relaxation pressure was lower when upright than when supine for all substrates (P < 0.01). The 10-g substrate significantly increased integrated relaxation pressure when compared to saline in the supine position (P < 0.01). Substrates and positions also affected distal contractile integral, distal latency, and impedance values. Conclusions We examined HRiM values using novel standardized viscous and super-viscous substrates in healthy subjects for both supine and upright positions. We found that viscosity and position affected HRiM Chicago metrics and have potential to increase the sensitivity of esophageal manometry.

• Journal of Oral Medicine and Pain
• /
• v.20 no.1
• /
• pp.141-158
• /
• 1995

This study was performed to invetigate the relationship between clinical manifestations related to temporomandibular joint sounds and temporomandibular joint vibrations that occurred synchronously with sounds. There have been reported in many articles that joint sounds indicate internal joint pathology. Therefore, it is necessary to evaluate type and patterns of joint sounds, and radiographic changes of temporomandibular joint(TMJ) in order to diagnose and deal with the Temporomandibular Disorders(TMD). For this study 142 patients with TMDs were collected and they were examined by routine diagnostic procedure for TMDs. The author classified TMJ sounds clinically into 3 types : click, popping, and crepitus. Transcranial and panoramic radiographs were taken for observein bony changes of TMJ, and for observing vibrations of TMJ Sonopak of Biopak system was used. The obtained results were as follows : 1. Female subjects with crepitus were older than those with click or popping and their mean ages were about 45 years old. But in male subjects, there was no age difference. 2. For all subjects, mean value of maximal mouth opening were above 40mm, which are lower limit of normal vertical opening. But in subjects with L-type opening deviation, mouth opening capacity were about 36mm of range. 3. Symptom duration stated when patient presented first were slightly longer in subjects with crepitus but there were no statistical differences. And there were also no radiographic differences among 3 types of joint sounds in regard to symptom duration. 4. In subjects wih click, it might have been interpreted that 12% had closed lock, 12% had degenerative joint disease, and about 17% of he subjects had normal joints by Sonopak. 5. There were no significant relationships between subjective loudness of joint sounds and magnitude of joint vibrations. 6. The highest value of Integral and peak amplitude were observed in popping sounds and though it was not significant, value of peak frequency was highest in crepitus. 7. Amount of mandibular positional change were differed between click and crepitus on frontal plane, between click, crepitus and popping on horizontal plane in rotational movement, respectively. However, there no difference among them in translational movements.

• International Journal of Ocean System Engineering
• /
• v.2 no.3
• /
• pp.185-194
• /
• 2012

A Macroscopic combination of two or more distinct materials is commonly referred to as a "Composite Material", having been designed mechanically and chemically superior in function and characteristic than its individual constituent materials. Composite materials are used not only for aerospace and military, but also heavily used in boat/ship building and general composite industries which we are seeing increasingly more. Regardless of the various applications for composite materials, the industry is still limited and requires better fabrication technology and methodology in order to expand and grow. An example of this is that the majority of fabrication facilities nearby still use an antiquated wet lay-up process where fabrication still requires manual hand labor in a 3D environment impeding productivity of composite product design advancement. As an expert in the advanced composites field, I have developed fabrication skills with the use of machinery based on my past composite experience. In autumn 2011, the Korea government confirmed to fund my project. It is the development of a composite sanding machine. I began development of this semi-robotic prototype beginning in 2009. It has possibilities of replacing or augmenting the exhaustive and difficult jobs performed by human hands, such as sanding, grinding, blasting, and polishing in most often, very awkward conditions, and is also will boost productivity, improve surface quality, cut abrasive costs, eliminate vibration injuries, and protect workers from exposure to dust and airborne contamination. Ease of control and operation of the equipment in or outside of the sanding room is a key benefit to end-users. It will prove to be much more economical than normal robotics and minimize errors that commonly occur in factories. The key components and their technologies are a 360 degree rotational shoulder and a wrist that is controlled under PLC controller and joystick manual mode. Development on both of the key modules is complete and are now operational. The Korean government fund boosted my development and I expect to complete full scale development no later than 3rd quarter 2012. Even with the advantages of composite materials, there is still the need to repair or to maintain composite products with a higher level of technology. I have learned many composite repair skills on composite airframe since many composite fabrication skills including repair, requires training for non aerospace applications. The wind energy market is now requiring much larger blades in order to generate more electrical energy for wind farms. One single blade is commonly 50 meters or longer now. When a wind blade becomes damaged from external forces, on-site repair is required on the columns even under strong wind and freezing temperature conditions. In order to correctly obtain polymerization, the repair must be performed on the damaged area within a very limited time. The use of pre-impregnated glass fabric and heating silicone pad and a hot bonder acting precise heating control are surely required.