• Journal of the Korean Institute of Educational Facilities
• /
• v.20 no.4
• /
• pp.31-35
• /
• 2013

• The Bulletin of The Korean Astronomical Society
• /
• v.4
• /
• pp.27.2-27.2
• /
• 1979

• Proceedings of the KIEE Conference
• /
• 1995.07c
• /
• pp.1428-1430
• /
• 1995

In this study we fabricate Knife type Si-tip array using (110) Si wafer. We can fabricate vertical structure by anisotropic etching using EPW and observe it by SEM. After the step, we perform isotropic etching and oxidation sharpening of the structure and also observe it by SEM, respectively. The purpose of isotropic etching is to reduce the oxidation time. We attain a optimal tip whose radius is about $100{\AA}$ after anisotropic etching 2.25 min.+isotropic etching 5 min.+oxidation 1 hour and 23 min.

• Proceedings of the IEEK Conference
• /
• 2005.11a
• /
• pp.311-316
• /
• 2005

The power saving mechanism of IEEE 802.16e operates in two modes; awake mode and sleep mode. While the user terminal transmits and receives packets in awake mode, it sleeps for a given interval to save the power consumption in sleep mode. The IEEE 802.16e specifies that the user terminal increases the sleep interval exponentially unless it has to wake up. In this paper, we analyze the performance of IEEE 802.16e power saving mechanism by considering down link traffic conditions. With the extensive simulations, we observe the trade-off between the power saving performance and the average packet delay. In addition, we observe that various performance parameters of IEEE 802.16e power saving mechanism are affected by the traffic patterns.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.87.2-87.2
• /
• 2016

As an era of nano science approaches, the understanding on the shape and optical properties of various materials in a nanoscale range is getting important more seriously than ever. Accordingly the development of high spatial-temporal-spectral resolution measurement tools for characterization of nanomaterials/structures is highly required. Generally, the various properties of sample can be measured independently, e.g. to observe the structural property of sample, we use the scanning electron microscopy or atomic force microscopy, and to observe optical property, we have to use another independent measurement tool such as photoluminescence spectroscopy or Raman spectroscopy. In the case of nano-materials, however, it is very difficult to find out the same position of sample at every different measurement processes, and the condition of sample can be changed by the influence of first measurement. The tip enhanced Raman scattering(TERS), which can simultaneously measure the two or more information of sample with nanoscale spatial resolution, is one of solutions of this problem. In this talk, I will present our recent nano Raman scattering data of graphene that measured by TERS and optimized tip fabrication method for efficient experiment.

• The Journal of Korean Physical Therapy
• /
• v.10 no.1
• /
• pp.149-154
• /
• 1998

This study was designed 1) to quantitatively observe changes in static platform and 2) to observe balance performance using vision. Seventy-five subjects participated in the study. Subjects comprised 39 males and 36 females(mean ages=23.8 years) without neurologic and orthopaedic impairments. Static balance was measured with eyes open and closed. Subjects was required to move the cneter of balance curser in a counterclockwise for 30 sec. The effect for the COBx(-) suggests that subjects tended to maintain their weight slightly In the left. The time taken and the accuracy to move the center of balance from target to target was 14 sec, $49.47\%$. The body sway upon reaching the target was 7.3 AP sway and 11.88 LR sway distance. In this study, the data developed could be appropriate to use for sine comparisons when balance training patients with neurologic or orthopaedic impairments.

• Speech Sciences
• /
• v.14 no.1
• /
• pp.93-103
• /
• 2007

The aims of this study were to examine the acoustic features of Korean and Japanese vowels, and to determine whether new phones that do not have counterparts in Japanese or similar phones that have counterparts improve more from learning. This study consisted of three parts. In Experiment I, a speech production test was performed to observe the acoustic features of Korean and Japanese vowels. In Experiment II, the speech production of Korean vowels produced by Koreans, advanced Japanese learners of Korean, and beginning Japanese learners of Korean was investigated. In Experiment III, a speech perception study of Korean vowels produced by the two Japanese learner groups was conducted to observe the effect of learning on acquiring L2 phones. The conclusion drawn from the study was that the similar phones produced by Japanese show more similarity with those of Koreans than new phones in terms of F1 and F2, but Japanese learners of Korean displayed more improvement in new phones from learning.

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.700-705
• /
• 2007

In this study, we observe the application of shape memory alloy(SMA) into smart structures for repeatable actuation, because SMA changes its material properties and characteristics progressively under cyclic loading conditions and finally reaches stable path(state) after a certain number of stress/temperature loading-unloading cycles, so called 'training'. In this paper, SMA wires that have been in a stable state through the training are used. Stress-strain curve of the SMA wire at different temperature levels are measured. In addition, we observe other important effects such as the rate effect according to strain rates for rapid actuation response. The current work presents the experimental test using SMA wire after training completion by mechanical cycling. Through these tests, we measure the characteristics of SMA. With the estimated SMA properties and effects, we compare the experimental results with the simulation results based on the SMA constitutive equations.

• Journal of Biomedical Engineering Research
• /
• v.28 no.1
• /
• pp.24-28
• /
• 2007

Presuming that firing neurons have motions inside the MRI magnet due to the interaction between the neuronal magnetic field and the main magnetic field, we applied motion encoding gradients to dissected snail ganglia to observe faster responding MRI signal than the BOLD signal. To activate the snail ganglia in synchronization with the MRI pulse sequence, we used electrical stimulation with the frequency of 30 Hz and the pulse width of 2s. To observe the fast responding signal, we used the volume selected MRI sequence. The magnetic resonance signal intensity, measured with 8 ms long motion encoding gradient with a 20mT/m gradient strength, decreased about $3.46{\pm}1.48%$ when the ganglia were activated by the electrical stimulation.

• Proceedings of the KOSOMBE Conference
• /
• v.1990 no.11
• /
• pp.33-37
• /
• 1990

Endoscope system is the device that observe interior the body. It has some demerits because it use of optical fibers. The resolution of images depends on the number of optical fibers, it is impossible that several people observe at the same time and it needs special camera in order to record images. In order to overcome these demerits, electro endoscope system using CCD(Charge Coupled Device) has been developed recently. If the diameter of insertion tube is thinner, it is easier to be examined by thin endoscope system. At the present time, we develope these type of electro endoscope system in the department of SNU biomedical engineering. Moreover, we are researching an algorithm of the 3D-reconstruction of interior of the gaster. In this paper, a method for 3D information detection using electroendoscopic image sequence has been presented.