• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.272.1-272.1
• /
• 2016

In a three-dimensional topological insulator Bi2Se3, a stress control for band gap manipulation was predicted but no systematic investigation has been performed yet due to the requirement of large external stress. We report herein on the strain-dependent results for Bi2Se3 films of various thicknesses that are grown via a self-organized ordering process. Using small angle X-ray scattering and Raman spectroscopy, the changes of d-spacings in the crystal structure and phonon vibration shifts resulted from stress are clearly observed when the film thickness is below ten quintuple layers. From the UV photoemission/inverse photoemission spectroscopy (UPS/IPES) results and ab initio calculations, significant changes of the Fermi level and band gap were observed. The deformed band structure also exhibits a Van Hove singularity at specific energies in the UV absorption experiment and ab initio calculations. Our results, including the synthesis of a strained ultrathin topological insulator, suggest a new direction for electronic and spintronic applications for the future.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.16 no.4
• /
• pp.38-45
• /
• 2017

A finite element analysis-based approach which investigates the causes of the breakdown in the outer ring of the choke at hot rod rolling mill is presented. Two-dimensional drawings of the whole vertical-type mill stand are transformed into three-dimensional CAD models. Non-linear elasto-plastic deformation analysis of material at the roll gap is performed for computing roll force and torque of the work roll. Then, the reaction forces of the bearing rings together with a set of roller bearings that support the work roll are obtained by means of rigid body motion analysis. Finally, stress behaviors in the bearing rings together with a set of roller bearings that support the work roll are investigated by linear elastic analysis. Results reveal that stress at the contact area between the outer ring and roller bearing is extraordinary high when an internal gap between an external surface of the outer ring and the internal surface of the chock due to wear of the inside of the chock occurs.

• Journal of the Korea Concrete Institute
• /
• v.14 no.1
• /
• pp.33-40
• /
• 2002

Vacuum concrete manufactured by vacuuming and decompressing fresh concrete. It is known to have improvement on abrasion and strength by making a structural confinement through elimination of internal gap. It has been implemented on buildings floors, concrete dam, etc. in developed countries. This study was aimed to monitor changes in physical characteristics such as strength and slump of concrete influenced by changes of vacuum, decompression level and combination condition during concrete manufacturing process. The results are as follows: It is indicated that decompressed concrete shoved increase in unit weight and compressive strength by compact compression phenomenon influenced by decrease in internal gap caused by diminishing oxygen. However, continuous research is necessary to resolve problems on construction, design and durability.

• The Journal of Advanced Prosthodontics
• /
• v.9 no.3
• /
• pp.176-181
• /
• 2017

PURPOSE. The purpose of this study was to evaluate the marginal and internal gaps of Ni-Cr and Co-Cr copings, fabricated using the dental ${\mu}-SLA$ system. MATERIALS AND METHODS. Ten study dies were made using a two-step silicone impression with a dental stone (type IV) from the master die of a tooth. Ni-Cr (NC group) and Co-Cr (CC group) alloy copings were designed using a dental scanner, CAD software, resin coping, and casting process. In addition, 10 Ni-Cr alloy copings were manufactured using the lost-wax technique (LW group). The marginal and internal gaps in the 3 groups were measured using a digital microscope ($160{\times}$) with the silicone replica technique, and the obtained data were analyzed using the non-parametric Kruskal-Wallis H test. Post-hoc comparisons were performed using Bonferroni-corrected Mann-Whitney U tests (${\alpha}=.05$). RESULTS. The mean (${\pm}$ standard deviation) values of the marginal, chamfer, axial wall, and occlusal gaps in the 3 groups were as follows: $81.5{\pm}73.8$, $98.1{\pm}76.1$, $87.1{\pm}44.8$, and $146.8{\pm}78.7{\mu}m$ in the LW group; $76.8{\pm}48.0$, $141.7{\pm}57.1$, $80.7{\pm}47.5$, and $194.69{\pm}63.8{\mu}m$ in the NC group; and $124.2{\pm}52.0$, $199.5{\pm}71.0$, $67.1{\pm}37.6$, and $244.5{\pm}58.9{\mu}m$ in the CC group. CONCLUSION. The marginal gap in the LW and NC groups were clinically acceptable. Further improvement is needed for CC group to be used clinical practice.

• The Journal of Korean Academy of Prosthodontics
• /
• v.55 no.2
• /
• pp.135-143
• /
• 2017

Purpose: This research was conducted to compare the marginal and internal fit of zirconia prostheses fabricated with the model scan method and the intraoral scan method. Materials and methods: In this study, 20 extracted human mandibular first molar was used in the preparation of abutment tooth for the fabrication of zirconia prostheses. In the first group, the model scan method was applied on 10 prepared teeth. In the other group, the intraoral scan method was used on other 10 prepared teeth. Datum of both groups were transmitted to the software system. Afterwards, 20 zirconia prostheses were fabricated using the Ceramill system. Weight technique was used to evaluate the internal gap of the zirconia prostheses. In the Replica technique, marginal gap of the zirconia prostheses were analyzed by optical microscopy. Statistical analysis was based on one-way ANOVA. Results: Model scan group showed lower average weight than intraoral scan group when weight technique was applied, which has significance (P < .05). Also, model scan group showed significantly lower figures in all 5 measurements of replica technique than intraoral scan group (P < .05). Conclusion: Zirconia prostheses of both groups demonstrated clinically acceptable margin and internal fit. However, model scanned zirconia prostheses showed higher marginal and internal fit than intraoral scanned crowns.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.11 no.1
• /
• pp.159-167
• /
• 1984

In this experiments, the fracture loads were measured and analysed by using of Instron universal testing machine (Model 1132). With 80 upper and lower deciduous molars that were free of dental caries. Isthmus of teeth were prepared to 1/3 and 1/4 of intercuspal width, and internal line angles with round and sharp shape, and then amalgam restoration were performed. The results of this study were as follows; 1. Resistance to fracture loads were greater with isthmus of 1/3 intercuspal width than of 1/4 intercuspal width, especially, statistically significant difference on upper and lower second deciduous molars. 2. Resistance to fracture loads were greater with rounded internal line angle than sharp internal line angle. The above results were as follows, the fracture loads had greater resistance on isthmus of 1/3 intercuspal width, and rounded internal line angle, but normal physiological occlusal forces could permit isthmus of 1/4 intercuspal width and rounded internal line angle.

• Computational Structural Engineering
• /
• v.9 no.3
• /
• pp.125-134
• /
• 1996

The base-isolation of building, as appeared in many studies, has shown remarkable performance in seismic response attenuation of the internal system as well as the building structure itself. But for the case that the internal system is submerged and hence subject to a considerable hydrodynamic effect, the seismic response of the system due to the base-isolation of building can be greater than the case that they are in air. This paper presents the dynamic analysis of a submerged internal system on base-isolated building to show such an example. The results show that an additional treatment is required to reduce the adverse effects on the seismic response of such a system when the building is base-isolated, and that the system response can be reduced to some extent by an appropriate control of fluid gap between the system and the building structure.

• Journal of Technologic Dentistry
• /
• v.41 no.1
• /
• pp.9-19
• /
• 2019

Purpose: This study was conducted to comparative evaluate the marginal and internal gap of three-unit metal frameworks(Co-Cr) fabricated by wax milling method and digital light projection method of CAD/CAM systems. Methods: All the specimens were fabricated by three different fabrication methods: conventional wax up with casting(CWC), milled wax block with casting(MWC), digital light projection with casting(DLPC) (n=10 each). The marginal and internal fits of specimens were examined using a replica technique. The light-body silicone thickness was measured at 8 reference points(each abutment: 16 measurements). All measurements were conducted by a stereomicroscope. Digital photo were taken at $150{\times}$ magnification and then analyzed using a measurement software. The Mann-Whitney test was used for analyzing the results. Results: Statistically significant differences were found between the fabrication methods(p<0.001). The mean(SD) is ${\mu}m$ for fabrication methods, the mean marginal fit were recorded respectively, CWC 63(38), MWC group 50(33), DLPC 103(54) and the mean internal fit CWC 96(47), MWC group 116(41), DLPC 138(66). Conclusion : The marginal and internal fit were statistically different according to the fabrication methods(p<0.001). In all fabrication methods, the greatest misfit was found the occlusal area of all specimens.

• Journal of Korean Academy of Nursing Administration
• /
• v.6 no.2
• /
• pp.259-279
• /
• 2000

This study is a descriptive analytic research measuring nursing service quality, using SERVQUAL model, to make fundamental data and strategies for nursing service improvement. Data were collected by self-reported questionnaire from 202 patients and 142 nurses, from June 7 to 14, 1999. The reliability of instrument were adequate(Cronbach ${\alpha}=.94$). SAS program was utilized for statistical analysis of collected data. The results were as follows; 1. There was a gab between patient's expectation and perception on nursing service(Gap B). Gap D was indicated an affecting factor to decide nursing service quality. Gap C was indicated an indirect affecting factor of nursing service quality. Because it was not statistically significant in total item analysis, but in individual item analysis, 7 items were appeared statistically significant. Gap A was not a gap occurrence factor of nursing service quality. 2. Focuses of nursing service quality improvement strategies were; (1) to direct qualitative improvement of nursing service in order to correspondence patient's nursing service expectation. (2) to make nurse's service activity modified because nurse's practice were not reached patient's expectation level. (3) to need internal, external factor analysis affecting nurse's service activity. 3. Nursing service quality was decided by rather environmental inappropriateness provided nursing service than itself. Therefore, to make nursing service quality improvement, it is required to improve nursing service environment. For this, followings are required; (1) to strengthen nurse's education on lower part of nursing service satisfaction and QI activities. (2) to balance demand and supply of nursing personnel. 3) to fix computerized system for reducing other duties weight except nursing care through analysis of nursing activity. (4) to construct rational cooperating system among related departments. 4. The important parts for nursing service quality improvement were indicated as follows: (1) Gap B: 'prompt reaction', 'examination symptom before patient's complaint', 'hearted nursing service reducing patient's dissatisfaction', 'explanation goals of nursing activities', 'having special Knowledge enough', 'maintenance position comfortably', 'management of patient's physical hygiene'. (2) Gap C: 'maintenance physical safety', 'explanation about hospital rules and facilities'. (3) Gap D: 'tender, safe injection and wound care'. Because above items are mostly improved through nurse's attitude change and quality improvement, it is required to establish nursing standardization and to strengthen nurse's clinical education. As the based on above results, followings are suggested; 1. SERVQUAL model is very useful to make strategies for nursing service quality improvement because it indicates multiple factors affecting hap occurrence. 2. At individual items analysis of Gap C, statistically significant 7 items appeared higher nurse's perception level than patient's perception level on nursing service were trouble perception level on nursing service quality improvement. So. it need further research to analysis about these difference occurring factors. 3. At analysis of Gap D, it is indicated that in nursing service performance process, multiple factors lowing nursing service quality were intruded. So it needs further research to analysis what these factors are and how each factors affect on nursing performance process. 4. nursing service quality measurement is changeable according to sample select time or sampled subject's characteristics. So to develope strategy for nursing service quality improvement is based on the results of periodical analysis.

• Journal of the Korea Society of Computer and Information
• /
• v.25 no.11
• /
• pp.27-40
• /
• 2020

In this paper, we investigate the correlation between the amount of English sentences that Korean English learners (L2ers) are exposed to and their sentence processing patterns by examining what Long Short-Term Memory (LSTM) language models (LMs) can learn about implicit syntactic relationship: that is, the filler-gap dependency. The filler-gap dependency refers to a relationship between a (wh-)filler, which is a wh-phrase like 'what' or 'who' overtly in clause-peripheral position, and its gap in clause-internal position, which is an invisible, empty syntactic position to be filled by the (wh-)filler for proper interpretation. Here to implement L2ers' English learning, we build LSTM LMs that in turn learn a subset of the known restrictions on the filler-gap dependency from English sentences in the L2 corpus that L2ers can potentially encounter in their English learning. Examining LSTM LMs' behaviors on controlled sentences designed with the filler-gap dependency, we show the characteristics of L2ers' sentence processing using the information-theoretic metric of surprisal that quantifies violations of the filler-gap dependency or wh-licensing interaction effects. Furthermore, comparing L2ers' LMs with native speakers' LM in light of processing the filler-gap dependency, we not only note that in their sentence processing both L2ers' LM and native speakers' LM can track abstract syntactic structures involved in the filler-gap dependency, but also show using linear mixed-effects regression models that there exist significant differences between them in processing such a dependency.