• Restorative Dentistry and Endodontics
• /
• v.22 no.1
• /
• pp.428-446
• /
• 1997

Restorative procedures can lead to weakening tooth due to reduction and alteration of tooth structure. It is essential to prevent fractures to conserve tooth. The resistance to fracture of the restored tooth may be influenced by many factors, among these are the cavity dimension and the physical properties of the restorative material. The placement of direct composite resin restorations has generally been found to have a strengthening effect on the prepared teeth. It is the purpose of this investigation to study the relationship between the cavity isthmus and the fracture resistance of a tooth in composite resin restorations. In this study, MO cavity was prepared on maxillary first premolar. Three dimensional finite element models were made by serial photographic method and isthmus(1/4, 1/3, 1/2 of intercuspal distance) were varied. Two types of model(B and R model) were developed. B model was assumed perfect bonding between the restoration and cavity wall and R model was left unfilled. A load of 500N was applied vertically at the first node from the lingual slope of the buccal cusp tip. This study analysed the displacement, 1 and 2 direction normal stress and strain with FEM software ABAQUS Version 5.2 and hardware IRIS 4D/310 VGX Work-station. The results were as follows : 1. Displacement of buccal cusp in R model occurred and increased as widening of the cavity, and displacement in B model was little and not influenced by cavity width. 2. There was a significant decrease of stress resulting in increase of fracture resistance in B model when compared with R model. 3. With the increase of the isthmus width, B model showed no change in the stress and strain. In R model, the stress and strain increased both in the area of buccal-pulpal line angle and the buccal side of marginal ridge, therefore the possibility of crack increased. 4. The stress and strain were distributed evenly on the tooth in B model, but in R model, were concentrated on the buccal side of the distal marginal ridge and buccal-pulpal line angle, therefore the possibility of fracture increased.

• Restorative Dentistry and Endodontics
• /
• v.32 no.2
• /
• pp.87-94
• /
• 2007

This study was done to evaluate transportation of the apical foramen after 0.5 mm overinstrumentation by ProFile, ProTaper and $K^3$ in simulated resin root canal. Sixty simulated resin root canal with a curvature of J and S-shape were divided into two groups. Each group consisted of three subgroups with 10 blocks according to the instruments used: $ProFile^{(R)},\;ProTaper^{TM},\;and\;K^{3TM}$. Simulated resin root canal was prepared by ProFile, ProTaper and $K^3$ with 300 rpm by the crown-down preparation technique. Pre- and post-instrumentation apical foramen images were overlapped and recorded with Image-analyzing microscope 100X (Camcope, Sometech Inc, Korea). The amounts of difference in width and dimension on overlapped images were measured after reference points were determined by Image Analysis program ($Image-Pro^{(R)}$ Express, Media Cybernetic, USA). Data were analyzed using Kruskal-Wallis and Mann-Whitney U-test. The results suggest that ProFile showed significantly less canal transportation and maintained original apical foramen shape better than $K^3$ and ProTaper.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.11 no.2 s.24
• /
• pp.37-55
• /
• 1987

Pasul (Herein after referred to Korean-styled Pasul) to cover up the secrets, which has originated from Bool-an original mode of clothes is to put around a belt with a kind of towel. With the development of culture, it has been handed down the parts of ornamental and symbolic functions, losted its particular and original one. In general, we cannot exactly show when the Pasul has been used as a ritual dress, but, dare to maintain in this thesis, which has been used in Koguryu era. This thesis is summarized as follows: 1. The Bool, which is the first dress of all has its origin in the prehistory, and gradually has developed to a ceremonial dress with the help of man's intelligence. 2. Korean-styled Pasul has continuously been handed down from generation to generation (to adding up, from Koguryu era to Yi dynasty). Today, the color of the Pasul is known as a pink one, but I, herein, would like to refer that king Kojong in Yi dynasty had on a yellow-colored Pasul. 3. With becoming to be a form of ceremonial dress, the Bool has become to be complicated in style. For example, in the Koguryu era, the style is in the form of 'U,' and in Koryu era, it is the echelon formation tinting a pink color and weaving a mountain and flare shaped designs, and its dimension, the upper is one ja (a ja means a unit of length, 0.33 M), the lower, two ja, its length three ja. The Bool of Yi dynasty tints a pink color, and weaves a seaweeds, rices, axes and shaped designs. The Pasul which King Kojong in Yi dynasty put in, was a yellow-colored one weaving dragons and fire shaped design. 4. The Pasul is a ceremonial dress used a ritual or court dress. The purposes of wearing it are to distinguish the upper from the lower classes, to make them abide by regulations, and to respect courtesy. Accordingly, the Pasul. as the dress for special occassions does make us review the old and learn the new. 5. The reason that Pasul has been handed down are: 1) richness and fecundity. 2) symbol mark to represent classicalism. 3) to symbolize the authority by putting on it, for it is necessary to distinguish the upper from the lower classes along with the class consciousness in society. 6. On the basis of the study, the Pasul transition is to be handed down the function of the ornament and symbol. after losted its original functions, with the development of culture.

• Journal of Bio-Environment Control
• /
• v.10 no.3
• /
• pp.172-180
• /
• 2001

A grape fruit is required for a lot of labor to harvest in time in Korea, since the fruit is cut and grabbed currently by hand. In foreign country, especially France, a grape harvester has been developed for processing to make wine out of a grape, not to eat a fresh grape fruit. However, a harvester which harvests to eat a fresh grape fruit has not been developed yet. Therefore, this study was designed and constructed to develope a image processing system for a fresh grape harvester. Its development involved the integration of a vision system along with an personal computer and two cameras. Grape recognition, which was able to found the accurate cutting position in three dimension by the end-effector, needed to find out the object from the background by using two different images from two cameras. Based on the results of this research the following conclusions were made: The model grape was located and measured within less than 1,100 mm from camera center, which means center between two cameras. The distance error of the calculated distance had the distance error within 5mm by using model image in the laboratory. The image processing system proved to be a reliable system for measuring the accurate distance between the camera center and the grape fruit. Also, difference between actual distance and calculated distance was found within 5 mm using stereo vision system in the field. Therefore, the image processing system would be mounted on a grape harvester to be founded to the position of the a grape fruit.

• Journal of Engineering Education Research
• /
• v.22 no.6
• /
• pp.51-63
• /
• 2019

This study aims to present concept of "gong" which was shared by traditional East Asian societies (Korea, China and Japan) and to identify how it has been developed through their respective process of modernization and industrialization. Despite the territorial proximity of the three countries, their industrial and technological development followed different patterns, and the notion of engineering from the Occident was also accepted and reconstructed with a certain difference in each country. Japan had developed its own concept of engineering as part of industrialization in Western style and in the context of establishment of an imperialist nation. What was important for Japan was how engineering could contribute to the national development of technology and industry, and to the development of Imperial Japan. For China, which attached importance to resistance to Western civilizations and to strengthening the competitiveness for and which needed to resolve domestic political conflicts, engineering constituted more than a simple issue on technological and industrial dimension; it was also associated with obtaining ethical and political legitimacy which would allow the nation to gain support from the working and peasant classes. Though belated, Korean attempted to build an independent modern state, yet experienced a considerable nuisance from the invasion of Japan and the protracted colonial period. Engineering of Korea had to take a long time before emerging from backwardness especially because of Japanese policies which tended to restrict technological development and avoid fostering qualified engineers in the colony. Therefore, engineering in Korea started to contribute to the nation's development and the improvement of technological competitiveness only after it was combined with modern higher education after liberation, under the name of engineering science (工學, gong-hak). This study argues that our recognition of what engineering was for and who engineers were in East Asia will allow us to evaluate current status of engineering education and provide us with significant insight which will be useful when we imagine the future society. Identity of engineering in Korea, China, and Japan has been developed along with historical contexts such as clash of civilizations, wars, recovery of sovereignty and obtaining of national competitiveness; now, what will be combined with engineering in the next generation? This question will lead and motivate engineering students to think and imagine about what future engineering should be and how they respond to it.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.21 no.1
• /
• pp.91-99
• /
• 2017

The purpose of this paper is to evaluate the flexural performance of reinforced concrete (RC) beams repaired with polymer mortar. The repaired and non-repaired 13th beams which was fabricated by considering repair position, repair depth, and curing age of polymer mortar as test variables were tested under three point loading. All specimens repaired in compressive and tensile zone did not fail due to interfacial failure between polymer mortar and concrete but failed when the strain of repaired mortar exceeded the ultimate tensile strain of polymer mortar. Maximum load of specimens repaired in compressive zone was similar to that of non-repaired specimen, reference specimen. Additionally, their ductility index was higher than that of reference specimen. On the other hand, specimens repaired in tensile zone failed very brittlely and have a lower ductility index than reference specimen. Nonlinear analysis by using OpenSees was performed to predict the behavior of RC beam repaired with polymer mortar. Two dimension frame element was used to simplify an analysis model and fiber model was applied to consider the material non-linearity. It was confirmed from the analysis results that nonlinear analysis properly predicts the behavior of specimens repaired in compressive zone and overestimates the behavior of specimens repaired in tensile zone.

• Survey Research
• /
• v.5 no.1
• /
• pp.51-78
• /
• 2004

This paper examines political leaders' image based on the concepts of social identity and distance. These concepts come from the two ideas: (1) Individuals create events to confirm the sentiments that they have about themselves and others in the current situation. (2) During this process structured sets of beliefs (social identity) about attributes of various entities are formed. Statistical analysis of the data from college students in Seoul offers three main findings. First, attributes clustered into four major groups-sociability, responsibility, power and activity. Sociability concerns as sense of approval or disapproval that can elaborated into closeness and intimacy. Responsibility relates to the judgement of morality, public obligation, or other standards. Power refers to social power, physical magnitude and so on. Activity indexes an entity's spontaneity, which can be elaborate into judgements of agency, speed and so on, Second, respondents evaluate negatively political leaders at the dimensions of sociability, responsibility, and activity, They are positively evaluated only at the dimension of power. Third, political leaders who are felt to be closer than others seem to have more political support nowadays.

• Korean Journal of Child Studies
• /
• v.37 no.2
• /
• pp.169-187
• /
• 2016

Objective: This study aimed to identify profiles based on early childhood and elementary school teachers' goal orientations and to examine differences in teacher efficacy, psychological wellbeing, and job satisfaction among these profile groups. Methods: Data were collected through a teacher questionnaire. The teacher goal-orientation scale consisted of six sub-dimensions: growth, leisure, wealth, relationship, promotion, and social contribution. Data were analyzed using latent profile analyses. Results: Latent profile analyses revealed three distinct profile groups: one group characterized by higher scores across all six dimensions (balanced-goal-orientation group); another characterized by lower scores on all six dimensions, with a relatively higher score on the relationship dimension (relationship-goal-oriented group); another one characterized by lower scores on all dimensions except the leisure goal (leisure-goal-oriented group). MANOVA showed that the balanced-goalorientation group was significantly higher in total years of teaching, educational attainment, and age, compared to the leisure-goal-oriented group. In regression analyses, when controlling for educational attainment, teacher types (kindergarten vs. elementary school) did not significantly predict each of the dummy-coded profile groups (0 = no, 1 = yes). When taking into account teachers' age and educational attainment, belonging to the balanced-goal-orientation group was consistently associated with higher levels of teacher efficacy, job satisfaction, and psychological well-being, whereas the opposite pattern was observed in leisure-goal-oriented group. Conclusion: These findings imply that it is crucial to help pre- and in-service kindergarten and elementary school teachers foster a balance between different types of goals, which would ultimately strengthen and stabilize the supply of a teaching force and the provision of a better education.

• Journal of Magnetics
• /
• v.19 no.2
• /
• pp.161-169
• /
• 2014

The aim of this study is to investigate the efficacy of pulsed electromagnetic field (PEMF) on the alleviation of lumbar myalgia. This is a randomized, real-sham, double blind pilot study. 38 patients were divided into the PEMF group and the Sham group, each of which was composed of 19 patients (1 patient dropped out in the Sham group) of randomized allocation. The PEMF group was treated by using the PEMF device and the Sham group by using a sham device on the lumbar muscle and acupuncture points, three times a week for a total of two weeks. Evaluations of Visual Analogue Scale for bothersomeness (VASB), Visual Analogue Scale for pain intensity (VASP), Oswestry Disability Index (ODI), 36-Item Short Form Health Survey Instrument (SF-36), EuroQol-5Dimension (EQ-5D), Beck's Depression Inventory (BDI) and Roland-Morris Disability Questionnaire (RMDQ), etc. before and 1 week after treatment were carried out. The primary outcome measure was the VASB, measured 1 week after the end of the pulsed electromagnetic therapy. VASB scores for the PEMF group changed by $-2.06{\pm}2.12$ from the baseline, and that for the Sham group changed by $-0.52{\pm}0.82$ (p < 0.05). VASP scores for the PEMF group were reduced by $-2.10{\pm}2.12$ from the base line, and that for the Sham group was reduced by $-0.53{\pm}1.50$ (p < 0.05). PEMF group showed significant improvements in all VASB, VASP, ODI, SF-36, EQ-5D, BDI and RMDQ scores, while the Sham group showed significant improvements in all scores, except the VASP score. However, the VASB, VASP and RMDQ scores of the PEMF group were much lower than those of the Sham group. The two groups showed no significant difference in ODI, SF-36, EQ-5D and BDI. This study demonstrates the effectiveness of PEMF treatment for alleviating lumbar myalgia.

• Journal of Service Research and Studies
• /
• v.8 no.1
• /
• pp.13-26
• /
• 2018

Most product consists of various national components, and brand strategy using nationality images is prevalent in marketing field. Country of origin is meaningful consideration for decision making. The purpose is that how consumer evaluate the global brand depending on two-sided dimension of country of origin. This research aims to examine the interaction effect of two-sided country of origin and moderating effect of global identity. In study 1, two-way interaction effect of origin of brand and origin of production was significant with social prestige. In study 2, there-way ANOVA provided marginally significant main effect of origin of brand and global identity. Two-way interaction effect of origin of brand and production was significant with social prestige. Also two-way interaction effect origin of brand and global identity was significant with innovation and social responsibility. Three-way interaction of origin of brand, origin of production, and global identity was significant with social responsibility, this approved moderating effect of global identity. Results contribute to understanding global brands strategy using country of origin effect, and to adding new knowledge to the country of origin literature. Academic and practical implications, limitations, and future research directions were discussed.