• Restorative Dentistry and Endodontics
• /
• v.14 no.2
• /
• pp.77-97
• /
• 1989

The purpose of this study was to observe the effect of ${\beta}GP$ in the remaining dental pulp tissue after pulpotomy in the dogs' teeth. For vital pulpotomy, 72 dogs' teeth were used and class V cavities were prepared and the pulps were amputated. ZOE and Dycal (Caulk Co., USA) were placed over the amputated tissue and cavities were sealed with ZOE cement in the control group. In the experimental group, ${\beta}GP$, ${\beta}GP$-ZOE, ${\beta}GP$-Dycal were placed over the exposed pulp tissues respectively. Dogs were sacrificed after 1, 2 and 4 weeks following the operations and the teeth were decalcified in the nitric acid, sectioned and stained with HE for light microscopic examination. For electron microscopic examination, specimens were made after 2 and 4 weeks following the operation. A comparative microscopic examination revealed as follows. 1. The dentin bridge was formed continuously due to osteodentin in the ${\beta}GP$-Dycal group at the 2nd week, the dentin bridge composed of osteodentin and tubular dentin was observed at the 4th week. 2. Osteodentin formation was vigorously in the ${\beta}GP$-Dycal than in the Dycal group. 3. In the surface of osteodentin the osteodentinoblasts showing vivid synthetic activity were observed and the matrix vesicles were presented during calcification of osteoid dentin matrix. 4. The dentin bridge formation was not observed in ${\beta}GP$ group and ${\beta}GP$-ZOE group.

• Restorative Dentistry and Endodontics
• /
• v.12 no.1
• /
• pp.51-64
• /
• 1986

The purpose of this study is to obtain the data of prestep in cavity preparation by observing changed conditions of laser irradiated dental hard tissues. The forty five extracted caries free human molars were divided into three groups and each group into five subgroups. A $CO_2$ laser irradiation was performed each subgroup of group I for one second with output power of 5 W, 10 Wand 20 W. On group II, laser irradiation was done ten times for 0.1 second duration using same power ratings as group I. On group III, laser irradiation was done 0.1 second, 0.2 second and 0.4 second with output power of 50 W. We investigated mineral contents and crater wall of obtained specimens, i.e., laser irradiated teeth, using computer controlled electron probe microanalyzer and scanning electron microscope. The following results were obtained: 1. Both calcium and phosphorus contents in laser irradiated enamel crater wall were increased, and magnesium content was decreased, but these trends were not statistically significant. 2. In laser irradiated dentin, change of mineral content was more significant. 3. In laser irradiated enamel and dentin, there were no significant differences on mineral content change due to irradiation condition and energy density. 4. In scanning electron microscopic study, enamel rods of the crater wall were fused and clefts were observed in parallel with the direction of enamel rod for all groups. 5. In laser irradiated dentin, irregular fusion and clefts were observed. In irradiated teeth with high power and short duration, the locally formed narrow crater wall was observed.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.20 no.4
• /
• pp.285-292
• /
• 1991

The effects of acute and chronic ethanol administration on hepatic and cerebellar glutathione (GSH) statuses and lipid peroxide levels in rats were investigated. In the liver, chronic ethanol feeding (6.9 g/kg, per day) as 10% (v/v) drinking water for 4 weeks produced a slight decrease of total GSH and an increase in the ratio of GSSG/total GSH without change of GSSG (oxidized GSH). Lipid peroxide level however was not modified. Many other studies have shown the acute ethanol loading effect in the rat liver, that is moderate decrease of total GSH and elevation of lipid peroxide level. Relating to this, it was observed that total GSH in the plasma obtained from post. hepatic inferior vena cava was increased by acute ethanol injection (50 mmol/kg, i.p.). This increased hepatic efflux of GSH into blood, in addition to the promoted antioxidative utilization of GSH, could be suggested as one of the possible reasons for the decrease of hepatic GSH induced by ethanol load. In the cerebellum, acute ethanol load did not change the total GSH and GSSG, but increased the lipid peroxidation rate. In the chronic, neither GSH pattern nor lipid peroxidation rate was changed.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.35 no.10
• /
• pp.1329-1335
• /
• 2006

LP-BM5 murine leukemia retrovirus induces the excessive oxidative stress and immune dysfunction leading to B cell leukemia and murine AIDS with cytokine dysfunction. In the present study, the immune restoratory effect of antioxidant hormone dedydroepiandrosterone sulfate (DHEAS) was investigated in the primary splenocytes from LP-BM5 retrovirus-infected C57BL/6 mice. DHEAS significantly increased T and B cell response to mitogen and normalized the unbalanced production of Th1/Th2 type cytokines. In particular, both protein and mRNA expression of IL-4, IL-6, and $TNF-\alpha$ were down-regulated by DHEAS treatment whereas IL-2 and $IFN-\gamma$ level were increased. This result suggests that DHEAS directly or indirectly regulates the gene expression of Th1/Th2 type cytokines in transcription level. In addition, DHEAS treatment decreased the hepatic lipid peroxidation and preserved vitamin E level in liver cells. These results suggested that DHEAS could effectively prevent immune dysfunction by regulating cytokine secretion and preventing the oxidative stress in murine AIDS.

• Korea journal of population studies
• /
• v.30 no.2
• /
• pp.147-168
• /
• 2007

The objective of this study is to examine the studies of foreign workers in Korea at a level of meta-analysis focusing on their subjects and methodology. Over the last 15 years, studies of foreign workers have diversified subjects and refined methodology reflecting major characteristics of migration patterns including a rapid increase in number, large populations of illegal sojourners, a majority low-skilled young male workers from less developed countries, and an active role of migrant-support NGOs. Nevertheless, the studies have shown problems such as a higher ratio of macroscopic discussions, overemphasis on social problematic issues and a tendency towards descriptive analysis. Methodologically, they have also revealed an inactive use of empirical and quantitative data, lack of representativeness of sample and disregard of an importance of language in the study of foreigners. Based on the analysis, this study proposes strategies to enhance researches of foreign workers in Korea.

• Journal of the Economic Geographical Society of Korea
• /
• v.11 no.3
• /
• pp.319-333
• /
• 2008

Government R&D policies generate diverse intended and unintended effects including innovator-specific and spatial effects. The Korean government has promoted R&D policies throughout the industrializing period, resulting in R&D networks focused on government research institutes geographically concentrated in the Capital region and Daedeok. This research aims to review the development of the Korean national R&D projects and analyze the recent composition of participants and spatial effects of the Korean national R&D projects. The results show that, in terms of the participants, the R&D networks generated from the Korean national R&D projects have been diversified from dominance of the government research institutes to strategic collaboration between the Korean private firms, universities, and government research institutes. Spatially, the R&D networks are not regionalized, and many private firms in most of the regions have nationwide R&D networks or still rely on the R&D networks in the Capital region.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.49 no.11
• /
• pp.901-907
• /
• 2021

The present study introduces an artificial neural network (ANN) that can predict the missile aerodynamic coefficients for various missile nose shapes and flow conditions such as Mach number and angle of attack. A semi-empirical missile aerodynamics code is utilized to generate a dataset comprised of the geometric description of the nose section of the missiles, flow conditions, and aerodynamic coefficients. Data normalization is performed during the data preprocessing step to improve the performance of the ANN. Dropout is used during the training phase to prevent overfitting. For the missile nose shape and flow conditions not included in the training dataset, the aerodynamic coefficients are predicted through ANN to verify the performance of the ANN. The result shows that not only the ANN predictions are very similar to the aerodynamic coefficients produced by the semi-empirical missile aerodynamics code, but also ANN can predict missile aerodynamic coefficients for the untrained nose section of the missile and flow conditions.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.4
• /
• pp.2217-2224
• /
• 2014

This paper deals with system development which measures 12 channel ECG using medical analog front end(AFE) and discriminates arrythmia through signal analysis. Recently, occurrences of cardiac arrest have been increased. So the need of system that diagnoses an arrythmia which results in cardiac arrest is increasing. There are some drawbacks of conventional 12 channel ECG system that it occupies bulk and consists of complicated circuit. To improve those, we made up the system composed of medical AFE, algorithm for discriminating arrythmia and DSP for signal processing. This system can be monitored 12 channel ECG waveforms and the discriminant analysis result of arrhythmia through 7" LCD and received the input through touch pannel. In this study, we conducted normal operation test about output signal of ECG simulator(normal/abnormal ECG signal) to verify the implemented system and performance evaluation of the optimization process for applying arrhythmia algorithm to an embedded environment.

• Journal of the Korea Computer Graphics Society
• /
• v.26 no.3
• /
• pp.133-142
• /
• 2020

In this research, we describe the method of implementing a 360-degree panorama using one projector, in terms of hardware and in the production of projected pre-distortion images. We propose a method of installing a projector and a reflector on the central ceiling of the space to minimize the shadows generated based on the position of the spectators. We used a virtual camera and virtual space where the projector and hemisphere positions were set to the same as in the exhibition space in Unity. After the image projected on the screen was mapped on the wall of the virtual space, the pre-distortion image was created by the method of capturing from the virtual camera using the ray tracing technique. When the produced pre-distortion image is hemispherical reflected and projected by the projector installed at the same position as the virtual camera, the image is reflected and projected 360 degrees on the panoramic screen.

• Journal of Biomedical Engineering Research
• /
• v.35 no.5
• /
• pp.125-131
• /
• 2014

The purpose of this study is to verify the utility of reflected photoplethysmography sensor using two green light emitting diodes that influenced by ambient light. Recently it has been studied that green light emitting diode is suitable for light source of reflected photoplethysmography sensor at low temperature and high temperature. Another study showed that, green light is better for monitoring heart rate during motion than led light. However, it has a bad characteristic about ambient light noise. To verify the utility of reflected photoplethysmography sensor using green light emitting diode, this study measures the photoplethysmography signal that is distorted by ambient light and will propose a solution. This study has two parts of research method. One is measurement system that composed sensor and board. The sensor is made up PE-foam and Non-woven fabric for flexible sensor. The photoplethysmography signal is measured by measurement board that composed high-pass filter, low-pass filter and amplifier. Ambient light source is light bulb and white light emitting diode that has three steps brightness. Photoplethysmography signal is measured with lead II electrocardiography signal at the same time and it is measured at the finger and radial artery for 1 minute, 1000 Hz sampling rate. The lead II electrocardiography signal is a standard signal for heart rate and photoplethysmography signal that measured at the finger is a standard signal for waveform. The test is repeated 3 times using three sensor. The data is processed by MATLAB to verify the utility by comparing the correlation coefficient score and heart rate. The photoplethysmography sensor using two green light emitting diodes is shown better utility than using one green light emitting diode and red light emitting diode at the ambient light. The waveform and heart rate that measured by two green light emitting diodes are more identical than others. The amount of electricity used is less than red light emitting diode and error peak detectability factor is the lowest.