• Polymer(Korea)
• /
• v.28 no.5
• /
• pp.426-432
• /
• 2004

To reduce volumetric shrinkage of the commercially available polymeric dental composite during curing reaction, (2,2-bis [4-(2-hydroxy-3-methacryloyloxy propoxy) phenyl] propane) (bis -GMA) derivatives, i.e., (2,2-bis[3-methyl, 4-(2-hydroxy-3-methacryloyloxy propoxy) phenyl] propan) (DMBis-GMA) and (2,2-his [3,5-dimethyl ,4- (2-hydroxy-3-methacryloyloxy propoxy) phenyl] propane) (TMBis-GMA) were synthesized and then new dental composite resin composed of Bis-GMA derivatives, diluent, spiro orthocarbonate (SOC), and inorganic filler was produced. Among the Bis-GMA derivative/Bis-GMA derivative/diluent mixtures, Bis-GMA/ TMBis-GMA/TEGDMA mixture exhibited the lowest volumetric shrinkage. Volumetric shrinkage of this mixture was further reduced by adding SOC. Volumtric shrinkage of dental composite prepared from commercially available resin monomer mixture was $2.5\%$, while that prepared from resin monomer mixture having minimum volumetric shrinkage was reduced to $0.7\%$. Mechanical strength of this dental composite was nearly the same with that of commercial products but the time required for the curing reaction was retarded.

• Archives of Plastic Surgery
• /
• v.37 no.4
• /
• pp.340-345
• /
• 2010

Purpose: Recently, bioceramics have become popular as a substitute graft material for reconstruction of bony defect after trauma or tumor surgery. Among the bioceramic materials, hydroxyapatite (HA) is favored due to its biocompatibility. HA scaffold is composed of the interconnected reticular framework, macropores and micropores. Macropores play an important role in cell migration, nutrients supply and vascular ingrowth. On the other hand, a number of micropores less than $10{\mu}m$ form an irregular surface on HA scaffolds, which prevents the osteoblast from adhering and proliferating on the surface of HA scaffold. Methods: In this study, three different groups were designed for comparison. In the first group (group A), conventional method was used, in which HA pellet was applied without surface pretreatment. The second group (group B) was given a HA pellet that has been coated with crystalline HA solution prior to application. In the third group (group C), the same method was used as the second group, where the pretreated HA pellet was heated ($1250^{\circ}C$, 1 hour) before application. Osteoblast-like cells ($2{\times}10^4$/mL) were scattered onto every pellet, then they were incubated in 5% $CO_2$ incubator at $37^{\circ}C$ for twelve days. During the first three days, osteoblast cells were counted using the hemocytometer daily. ALP activity was measured on the 3, 6, 9 and 12 culture days using the spectrophotometer. Results: Under SEM, group A showed a surface with numerous micropores, and group B revealed more rough crystal surface. Group C revealed a fused crystal appearance and flattened smooth surface. In proliferation and ALP activity of osteoblast cells, group C showed better results compared to group B. Group A which lacks pretreatment of the surface showed less osteoblast proliferation and ALP activity than group C, but showed better results than group B. Conclusion: We found that crystallized HA with heat treatment method enhances the osteoblasts proliferation and differentiation on the surface of HA pellets.

• Journal of Chest Surgery
• /
• v.40 no.9
• /
• pp.617-623
• /
• 2007

Background: Invasive pulmonary aspergillosis, a frequent fungal infection in immunocompromised patients, is known to have a poor prognosis despite the use of antifungal therapy in leukemic patients. We studied the outcome of surgical resection of invasive pulmonary aspergillosis where bleeding tendency, localized recurrence of infection, and incidence could be reduced. Material and Method: We retrospectively reviewed 14 patients with a hematological malignancy where invasive pulmonary aspergillosis was diagnosed during the 10 years between 1998 and 2007. From the medical records, we reviewed the type and treatment of the hematological malignancy, including the diagnostic methods of invasive pulmonary aspergillosis, the preoperative hematological conditions and their management, and the surgical methods and records. We also analyzed the development of postoperative complications and patient mortality, the recurrence of postoperative invasive pulmonary aspergillosis, and if the patients had a bone marrow transplant. Result: Fourteen patients with invasive pulmonary aspergillosis and a hematological malignancy underwent a pulmonary lobectomy. One patient had a complication of bronchopleural fistula, but there were no other serious complications such as bleeding or wound infection, and none of the patients died postoperatively. Conclusion: We have shown that pulmonary lobectomy is a safe and effective therapy for invasive pulmonary aspergillosis in patients with hematological malignancies that allow further treatment of the hematological malignancy.

• Journal of the Korean Society for Library and Information Science
• /
• v.52 no.1
• /
• pp.203-229
• /
• 2018

This study examined current status and futurity of libraries based on the survey of librarians awareness in the era of the $4^{th}$ Industrial Revolution and sought to find effective response strategies for future changes. For this purpose, this study reviewed research issues against the $4^{th}$ Industrial Revolution based on preceding researches in our library area and other fields. The awareness survey was conducted of librarians of several types including national libraries and public libraries. The results are as follows: First, librarians were interested in the $4^{th}$ Industrial Revolution, but they thought that new technologies are poorly adopted in their libraries. Second, librarians were most frequently using Desktop PCs, mobile phones, RFID tags, and QR codes for library services. Third, librarians were required intelligent-information services because of their effectiveness, but their libraries did not provide them for users. Fourth, librarians expected that the $4^{th}$ Industrial Revolution brings positive influences to libraries' future. On the other hands, they also concerned about their job losses. Fifth, librarians agreed with necessity of new technologies of the $4^{th}$ Industrial Revolution and they especially wanted educations and training related with technologies. Also, technical supports for online services and simply repeated works are required.

• Journal of Biomedical Engineering Research
• /
• v.21 no.4
• /
• pp.373-384
• /
• 2000

The goal of this paper is to develop a computational method to predict cancellous bone density distributions based upon continuum levels of volumetric strain. Volumetric strain is defined as the summation of normal strains, excluding shear strains, within an elastic range of loadings. Volumetric strain at a particular location in a cancellous structure changes with changes of the boundary conditions (prescribed displacements, tractions, and pressure). This change in the volumetric strain is postulated to predict the adaptive change in the bone apparent density. This bone remodeling theory based on volumetric strain is then used with the finite element method to compute the apparent density distribution for cancellous bone in both lumbar spine and proximal femur using an iterative algorithm, considering the dead zone of strain stimuli. The apparent density distribution of cancellous bone predicted by this method has the same pattern as experimental data reported in the literature (Wolff 1892, Keller et al. 1989, Cody et al. 1992). The resulting bone apparent density distributions predict Young's modulus and strength distributions throughout cancellous bone in agreement with the literature (Keller et al. 1989, Carter and Hayes 1977). The method was convergent and sensitive to changes in boundary conditions. Therefore, the computational algorithm of the present study appears to be a useful approach to predict the apparent density distribution of cancellous bone (i.e. a numerical approximation for Wolff's Law)

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.11
• /
• pp.4932-4939
• /
• 2011

The purpose of this study was to conduct a survey of general status of drinking culture among college students in Korea. Three hundred college students answered the self-administered questionnaire from May 6 to May 10 in 2009. The questionnaire consisted of drinking-related behavior by gender, recognition and need for moderation in drinking program, and the reason for stopping drinking by gender. The statistical method was done by SPSS WIN version 14.0. The first drinking time was high school comprising 41.0% of the respondents. The reason for drinking was to get the personal relationship. The experience of blackout was 50.3% in twice a year and 26.0% in twice per six months. The reasons for stopping drinking were health problem(36.9%), personal relationship(34.5%), and financial difficulty(20.8%). These results will make it possible to establish the right drinking habit, prevention of sexual violence and vehicle accident and health promotion of the students.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.32 no.5
• /
• pp.649-653
• /
• 1999

A magnetic fluid separation technology was confirmed to be very effective to remove the suspended solids (SS) from aquacultural recirculating water, In this study, the effects of operating variables on the characteristics of SS removal were investigated through the test runs using magnetite of 2 $\mu$m mean diameter as magnetic powder. Magnetic flocculation here formed by adsorbing fine magnetites on the surface of suspended solid was observed. The strength of magnet was of significance in determining the SS removal efficiency as well as the capacity of the equipment. In addition, the SS removal efficiency decreased with an increase in the superficial liquid velocity, but the effect became negligible when the mass ratio of magnetite to the suspended solids was higher than 1.0.

• Resources Recycling
• /
• v.26 no.5
• /
• pp.12-21
• /
• 2017

Red mud generated in the alumina manufacturing process contains various valuable resources, but it is not comprehensively recycled yet causing severe environmental problems. In Korea, red mud is producing about 200,000 tons annually and most of them are landfilled or disposed. Red mud's recycling technology is also being developed in many countries, but red mud's recycling technologies are still lacking compared to the production rate. In this study, we analyzed the characteristics and the amount of red mud, and the current status and technology development trend. Red mud has shown that recycling studies are being carried out in fields such as construction, recycling, metal recovery, adsorbent, and pollution stabilization. In particular, technologies for recovering rare earths have been developed as worldwide because of their high economic value. The data analyzed in this study will be used as basic data for the further development of technologies in the future.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.15 no.2
• /
• pp.85-94
• /
• 2016

Lane Designation is defined as reasonable road management to ensure the road safety and enhance road efficiency. While the lane designation system was abolished in 1999, it was redefined because of the increasing number of large vehicles in the passing lane, violent on driving and traffic accidents in 2000. The needs of improvement on operating the lane designation has been increasing more in recent due to the low ratio of compliance with the system and difficulties to keep the right lane due to need of turning and demand of widening of designates lane for two-wheeled vehicles and truck. In this study, we presented the improvement plan through the question survey, simulation analysis, safety evaluation. It found a problem that the low-speed vehicle is to use the upper level roadway, difficulties of supervision, the imbalance in the lane use, imbalance traffic and does not match the international standards. This study suggested five different alternatives through the survey. micro simulation has used in order to examine each alternative by management effectiveness and feasibility. It analyzed the traffic speed, efficiency, traffic balance of alternatives. Also, safety evaluation conducted in terms of the range of field-of-view to ensure the easiness of field of view by various configurational difference between the vehicles. By the analysis results of such indicators, This study presents proposals for improvement in operating designated lane that low-speed-big-sized vehicles keep to the right lane, and high-speed-small sized vehicles keep to the left lane.

• Korean Journal of Remote Sensing
• /
• v.25 no.2
• /
• pp.145-154
• /
• 2009

High spatial resolution satellite image classification has a limitation when only using the spectral information due to the complex spatial arrangement of features and spectral heterogeneity within each class. Therefore, the extraction of the spatial information is one of the most important steps in high resolution satellite image classification. This study proposes a new spatial feature extraction method, named SSI(Shape-Size Index). SSI uses a simple region-growing based image segmentation and allocates spatial property value in each segment. The extracted feature is integrated with spectral bands to improve overall classification accuracy. The classification is achieved by applying a SVM(Support Vector Machines) classifier. In order to evaluate the proposed feature extraction method, KOMPSAT-2 and QuickBird-2 data are used for experiments. It is demonstrated that proposed SSI algorithm leads to a notable increase in classification accuracy.