• Journal of Chest Surgery
• /
• v.29 no.5
• /
• pp.589-592
• /
• 1996

We report two cases of the thoracoscopic thymectomies for patients of myasthenia gratis with tracheostomy (Osserman's Group-ll-C-1). The Irst case was 47-year-old male wlth generalized myas- thenia gravis who was under the mechani al ventilator therapy with tracheostomy. The second case was 60-year-old male with deteriorating generalized myasthenia gratis after the mechanical ventilator therapy. We decided to resect the thymus by vldeo-assisted thoracoscopy to prevent the ouurrence of postoperative complications, especially mediastinitis because all two cases were under tracheostomy state. We could stop the mechanical ventilator therapy on the postoperati'fe 16th day and 3rd day respect- ively and they were recovered without mediastinitis. So we concluded that video-assisted thoracoscopic thymectomy is a good alternative surgical method for myasthenia gratis patients with tracheostomy.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.08a
• /
• pp.381-381
• /
• 2011

The influence of the water vapor on the growth of single-walled carbon nanotubes (SWCNTs) was investigated. SWCNTs were synthesized by catalytic chemical vapor deposition of acetylene over Fe-Mo/MgO catalyst with injection of water vapor. The morphologies and structures of the water-assisted SWCNTs were investigated according to the growth conditions such as water vapor concentrations, flow rate of the gas, furnace temperature, and growth time. Water-assisted SWCNTs exhibited large bundle morphological features with well-alignment of each CNT, while SWCNTs synthesized in the absence of water vapor showed entangled CNT with the random orientation. We also found that the diameter of the SWCNT bundle could be controlled by the growth condition. In our optimal growth condition, the product yield and the purity were 300 wt. % and 75%, which were 7.5 and 2.5 times higher than those of SWCNTs synthesized without water vapor, respectively. More detail discussion will be offered at the poster presentation.

• Transactions of Materials Processing
• /
• v.13 no.3
• /
• pp.262-267
• /
• 2004

Ultrasonic machining has been known as one of the conventional machining methods in the glass fabrication processes. In ultrasonic machining, typically, glass is removed by the impulse energy of the abrasive generated by the ultrasonic power. However, when the machining feature decrease under hundreds of micrometers, as conventional ultrasonic machining uses only the impulse energy of the abrasive, the speed of ultrasonic machining decreases significantly and the surface roughness becomes deteriorated. To overcome this size effect, the chemicals which can erode glasses, such as HF, XF, etc, are added to the slurry. The chemical-assisted ultrasonic machining method, so called, is another alternating effective way for micro machining of glasses. In previous work, we used the hydrofluoric acid (HF) as an additive chemical. But, as the HF solution is too poisonous to be used as a ultrasonic process additive, it is needed to be substituted by other safe chemicals. As results of the machinability comparison of several chemicals, the GST-500F was selected to replace the HF. The GST-500F (pH $4.0{\pm}1.0$) is non-volatile, odorless. During experimental works, it was shown that the machining rate increases 1.5 times faster than the conventional ultrasonic machining. The machining load also decreases. However, the enlargement of the hole diameter and significant tool wear are still the problems to be solved.

• Proceedings of the Korea Society for Industrial Systems Conference
• /
• 2002.06a
• /
• pp.239-247
• /
• 2002

With the introduction of the 7th Curriculum, it has been put greater emphasis on learning by experience. This study aims to implement the quiz-based wireless application for helping to learn more effectively what one will see and hear on the spot when he visits the cultural assets. The materials about Busuk Temple, used as the example of the quiz-based assisted learning, were collected from the libraries and through the internet. And they were programmed using the basic components and properties of WML and then operated with UP SDK 4.0, Phone.com WAP development toolkit. This wireless application makes the user know if it is correct when he selects either O or X as the answer of each question, and shows the individual score after solving 10 questions in total. Each user can also have additional chances to solve them again, even though they doesn't influence the previous score. This study is focused on the implementation of the wireless application for assisted learning by a mobile phone which almost everybody will possess. Various kinds of wireless contents are expected to be developed and provided in the field of education.

• Journal of the Korea Convergence Society
• /
• v.8 no.3
• /
• pp.177-184
• /
• 2017

The purpose of this study was to explore children and robot interaction in distant language learning environments using three different video-conferencing technologies-two traditional screen-based videoconference technologies and a telepresence robot. One American and six Korean elementary school students participated in our case study. We relied on narratives of one-on-one interviews and observation of nonverbal cues in robot assisted language learning. Our findings suggest that participants responded more positively to interactions via a telepresence robot than to two screen-based video-conferencings, with many citing a stronger sense of immediacy during robot-mediated communications.

• Journal of Electrochemical Science and Technology
• /
• v.1 no.2
• /
• pp.121-126
• /
• 2010

An amperometric ascorbic acid selective sensor utilizing the transfer reaction of proton liberated from the dissociation of ascorbic acid in aqueous solution across an elliptic micro-hole water/organic gel interface is demonstrated. This redox inactive sensing platform offers an alternative way for the detection of ascorbic acid to avoid a fouling effect which is one of the major concerns in redox based sensing systems. The detection principle is simply measuring the current change with respect to the assisted transfer of protons by a proton selective ionophore (e.g., ETH 1778) across the micro-hole interface between the water and the polyvinylchloride-2-nitrophenyloctylether gel phase. The assisted transfer reaction of protons generated from ascorbic acid across the polarized micro-hole interface was first characterized using cyclic voltammetry. An improved sensitivity for the quantitative analysis of ascorbic acid was achieved using differential pulse stripping voltammetry with a linear response ranging from 1 to $100\;{\mu}M$ concentrations of ascorbic acid. As a demonstration, the developed sensor was applied for analyzing the content of vitamin-C in different types of commercial pharmaceutical tablets and syrups, and a satisfactory recovery from these samples were also obtained.

• Journal of The Korean Association For Science Education
• /
• v.12 no.1
• /
• pp.47-60
• /
• 1992

The purpose of this study was to investigate studesnts' attitudes toward computers and science subject using CAI(Computer-Assisted Instruction) as an instructional strategy in the elementary school level of science and computer literacy course. The influence of CAI programs on learner's attitudes toward computers and science varied according to the variables of,(l)sex (2)experience by computer learning, (3)learner's attitudes toward computers and science. Eighty nine samples were divided into the two groups.One group(48 studesnts)which is in the experimental group took a science instruction using CAI programs and computer literacy course, another group which is in the control group took only a science instruction using CAI programs. Data were collected and compared the experimental group with the control group. The results indicate as follows:(l) studesnts took science instruction using the CAI programs appeared a positive attitudes toward science. (2) the science attitudes of science instruction using the CAI programs was more effective in the lower group than in the upper group. (3) computer literacy course produced the positive attitude toward computers regardless of the experience by computer learning. (4) students using CAI programs with computer literacy course were more effective than students using CAI program only. (5) science instruction using the CAI programs was not found a meaningful difference by sex.

• Journal of the Korean Ceramic Society
• /
• v.46 no.5
• /
• pp.484-487
• /
• 2009

$SiC_f$/SiC composites with whiskers and pyrolytic carbon (PyC) coated whiskers in the matrix were fabricated for enhancement of the fracture behaviors by the whisker growing assisted chemical vapor infiltration (WA-CVI) process, respectively. $SiC_f$/SiC composites were also prepared by the conventional CVI process as reference material. The mechanical properties and fracture behaviors were analyzed by comparison of the two types of composites prepared by WA-CVI and conventional CVI. The densities of $SiC_f$/SiC composites were in the range of $2.6{\sim}2.65g/cm^3$. The flexural strengths of composite with whiskers and with those coated by PyC were 650 MPa and 600 MPa, respectively. The tensile strength of composites with whiskers was ${\sim}285$ MPa.

• Survey Research
• /
• v.1 no.2
• /
• pp.137-159
• /
• 2000

In this paper, the following facts have been reviewed: First, statistics should have the characteristics of descriptive, inferential, and applicative statistics in "information-Knowledge Society." Second, the computer has been employed in the process of data collection and data analysis for producing the statistics with timeliness and efficiency. Third. we have to develop a statistical development plan which lays emphasis on the production of applicative statistics in the coming "Internet Cyber Society" In addition, we investigated overall status of computer utilization, and the process of the development of computer-assisted statistical survey methods. The prospects of internet surveys were also investigated here. On the basis of the above review and investigation, we suggested "an integrated system of computer-assisted statistical surveys" that can be applied to all kinds of surveys and statistics.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.13 no.10
• /
• pp.828-833
• /
• 2000

Growth characteristics and microstructure of AIN thin films grown by plasma assisted molecular beam epitaxy on Si substrates have been investigated. Growing temperature and substrate orientation were chosen as major variables of the experiment. Reflection high energy electron diffraction (RHEED), X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microscopy/diffraction (TEM/TED) techniques were employed to characterize the micorstructure of the films. On Si(100) substrates, AlN thin films were grown along the hexagonal c-axis preferred orientation at temperature range 850-90$0^{\circ}C$. However on Si(111), the AlN films were epitaxially grown with directional coherency in AlN(0001)/Si(111), AlN(1100)/Si(110), and AlN(1120)/Si(112) at 85$0^{\circ}C$ and the epitaxial coherencry seemed to be slightly distorted with increasing temperature. The microstructure of AlN thin films on Si(111) substrates showed that the films include a lot of crystal defects and there exist micro-gaps among the columns.