• The korean journal of orthodontics
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• v.38 no.2
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• pp.95-103
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• 2008

Objective: This study was performed to investigate the labio/buccal clinical crown curvatures of Korean permanent teeth and to obtain the curve-ratio data in an attempt to fabricate bracket bases fit for each individual Korean permanent tooth. Methods: Three-dimensional digital models were made from 30 sets of dental casts with normal anatomic structures. According to the FA points, horizontal and vertical reference planes were established and lines were drawn on the tooth surfaces in reference to these planes. The curvature was expressed as the coefficient of a quadratic equation. Lines mesial, distal, gingival and occlusal to the horizontal, vertical reference planes and the FA point were drawn. Results: The curvature measured for each line revealed that there are no significant differences between male and female, except for maxillary canines and maxillary second bicuspids (p > 0.05). There were notable differences in the mesio-distal or gingivo-occlusal curvatures among the mandibular lateral incisors, maxillary canines, maxillary and mandibular first and second bicuspids and first molars (p < 0.05). Conclusions: The labial & buccal crown curvatures of teeth in Korean normal occlusion were measured on the mesial and distal, gingival and occlusal sides respectively in this study. Based on these data, a SWA can be developed to fit the individual features of Korean tooth crowns.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.129-136
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• 2020

A Cut Out Switch (COS) is used for line protection and pole transformer protection in power systems. The COS used to protect the pole transformer is installed on the power side of the pole transformer to protect the electric equipment from fault currents. The COS is composed largely of a body and a fuse holder, and when the fault current is energized, the element of the fuse link in the fuse holder is melted to block the fault current. The arc generated when the COS fuse link is blown causes fire and noise, causing discomfort to residents in the surrounding area, and the arc flame can cause secondary damage to the peripheral device. In this study, a current-limiting COS fuse with improved overcurrent blocking performance rather than explosion type was developed to solve the arc and noise problems during COS operation. The overcurrent breaking performance of the current-limiting COS improves the reliability by developing a striker and COS fuse bracket. In addition, this study aimed to verify the performance of the developed current-limiting COS fuse through a test at an authorized institution.

• International Journal of Fluid Machinery and Systems
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• v.10 no.1
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• pp.40-46
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• 2017

Small valves including ball valves, gate valves and butterfly valves have been adopted in the fields of steam power generation, petrochemical industry, carriers, and oil tankers. Butterfly valves have normally been applied to fields where in narrow places installing the existing valves such as gate valves and ball valves have proven difficult due to the surrounding area and the heavier of these valves. Butterfly valves are used to control the mass flow of the piping system under low pressure by rotating the circular disk installed inside. The butterfly valve is benefitted by having simpler structure in which the flow is controlled by rotating the disc circular plate along the center axis, whereas the weight of the valve is light compared to the gate valve and ball valve above-mentioned, as there is no additional bracket supporting the valve body. The manufacturing company needs to acquire the performance and life test equipment, in the case of adopting the improving factors to detect leakage and damage on the seat of the valve disc. However, small companies, which are manufacturing the industrial valves, normally sell their products without the life test, which is the reliability test and environment test, because of financial and manpower problems. Furthermore, the failure mode analysis of the products failed in the field is likewise problematic as there is no system collecting the failure data on sites for analyzing the failures of valves. The analyzing and researching process is not arranged systematically because of the financial problem. Therefore this study firstly tried to obtain information about the failure data from the sites, analyzed the failure mode based on the field data collected from the customers, and then obtained field data using measuring equipment. Secondly, we designed and manufactured the performance and life test equipment which also have the real time monitoring system with the naked eye for the butterfly valves. The concept of this equipment can also be adopted by other valves, such as the ball valve, gate valve, and various others. It can be applied to variously sized valves, ranging from 25 mm to large sized valves exceeding 3000 mm. Finally, this study carries out the life test with square wave pressure, using performance and life test equipment. The performance found out that the failures from the real time monitoring system were good. The results of this study can be expanded to the other valves like ball valves, gate valves, and control valves to find out the failure mode using the real time monitoring system for durability and performance tests.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11b
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• pp.489-497
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• 2000

Since Chinese cabbages weigh 3 to 5kgf and are big in size at the time of harvest, handling operations such as harvesting, loading and unloading including transportation require the highest labor demand among all other cultivation processes. Recently, though several cabbage harvesters were developed in Japan and Europe, those harvesters were not suitable for Chinese cabbages cultivated in Korea because of the size and shape. The cabbage harvester is almost meaningless without any proper cabbage piling and pallet unloading mechanism. Most harvesters developed so far adopted a sort of slide and free falling way in collecting cabbages into the pallet. Three or four labors are usually required for cleaning incoming cabbages and loading those in the pallet. Because of the required time for piling cabbages without severe damage and the required space capacity to carry empty and loaded pallets, harvesting speed should be adjusted in accordance with time required for consecutive operations. Up to now, any automatic or semi-automatic collecting device has not been developed in the world to pile cabbages on the layer one by one into the pallet in the ordered way with little damage and to unload pallet from the harvester continuously during the harvest process. To compromise system expenses and function, Semi-automatic cabbage piling and pallet unloading mechanism was devised and it required one labor. The foldable mesh pallet with a size of 1050mm x 1050mm x 1000mm and holding capacity of around 70 cabbages was utilized. The prototype for piling and unloading mechanism was composed of three parts such as feeding device, automatic piling device with retractable bellows, and pallet unloading device. Prior to developing the prototype, the geometric properties and the amount of the damage of the cabbage caused during the piling operation were investigated. Considering the height of the pallet, a series of cabbage carrying plates were mounted to the bracket chain to lift and to carry cabbages to the loading device. Indoor laboratory experiments showed that the cabbage carrying chain conveyor worked successfully. Considering the conveying speed 0.46m/sec of the pull up belt from the cabbages on the ground, the speed of cabbage carrying chain conveyor worked property in the range of 0.26m/sec to 0.36m/sec. The system allowed the operator to modify the position of cabbage slightly. Overall system worked successfully resulting into almost same capacity without severe damage to the cabbage as human did.

• Korean Security Journal
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• no.20
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• pp.141-177
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• 2009

The purpose of this study is to identify the effects of service orientation perceived by employees of security companies on service quality and management performance based on service orientation theory. To test this, 345 participants were sampled from the security companies located in Seoul and Gyeonggi area using stratified cluster random sampling, and then frequency analysis, exploratory factor analysis, t-test, one-way ANOVA analysis and path analysis of the resulting data were conducted using SPSS 15.0 program. Conclusions derived from the aforementioned analytical methods are as follows: there were difference in service orientation according to demographic characteristics. And results from analyses showed that service leadership, which is sub factor of service orientation, was highly evaluated by the male group, and the customer service, by the participants of having college education and more, and the service system, by the group of the income bracket between 1.51 and 2 Million Won.

• Journal of radiological science and technology
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• v.27 no.3
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• pp.59-69
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• 2004

By studying on the characteristics of cancer patients who receive radiotherapy and the attitudes of medical social workers, this thesis aims to suggest of requirements for medical social work intervention. The study was conducted using SPSS 10.0 for Windows to analyze data taken from a survey involving 90 cancer patients receiving radiotherapy in 4 general hospitals in Daejeon city. The data were collected form Oct. 1st to 15th, 2003, and its analyses used averages, correlation, and regression. The results were summarized as follows ; 1. The average family income in 67.8% of the cases was less than 2,000,000 won, which is a lower income bracket. In the disease characteristics, fatigue ware the highest (2.78) in the side effects of radiotherapy, which most patients were receiving alongside other forms of treatment. 2. It was shown that cancer patients receiving radiotherapy receive a high level of psychological and social support from doctors and other medical staffs, and that they also received a high average (4.38) of individual care and encouragement from family members. 3. In the psychosocial status, the need for financial assistance in the form of a national aid program or an expansion of medical insurance was great, especially in the need for house keeping service and night nurses. The need for psychosocial counselling rose following rises in treatment side effects and depression. Information for cancer patients was especially needed in the areas of treatment plans, treatment costs, and side effects of radiotherapy. The need for information rose in accordance with an elongation of hospital treatment and an escalation of care from family members.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.4
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• pp.202-213
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• 1992

For the analysis and design of ship structures the generalized slope deflection method(GSDM) taking account of axial elongation effect as well as the bending and shearing deformation is developed. Using the span point concept, the existing slope deflection method is easy to transform the variable section to the equivalent uniform one under the bending moment and the shear force, but it is difficult to analyze the web frame with inclined members because the axial deformation effect is not considered. In the present method, the equilibrium conditions including all force components(i.e. axial force, shear force, bending moment) are formulated at the both ends of the variable section beam, such that the usual space frame stiffness equation which can be solved easily by the matrix method is derived. The accuracy and applicability of the present method is demonstrated by analyzing the ship web frame structures.

• Journal of Korean society of Dental Hygiene
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• v.7 no.4
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• pp.405-418
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• 2007

The purpose of this study was to examine the interest level of mothers in oral health. The subjects in this study were 184 mothers whose children attended daycare centers in the city of K. A survey was conducted from March 15 through April 30, 2007, and SPSS WIN 11.5 program was employed to analyze their answer sheets. The findings of the study were as follows: 1. A group of mothers whose children brushed their teeth three times a day on the average made up 55.7 percent of those who were at the age of 35 and under. Among the mothers having three or more children, those mothers accounted for 59.1 percent. The daily mean toothbrushing frequency of children was higher among the better-educated mothers. 2. Concerning dietary and oral guidance, the mothers whose academic background was better curbed their children's excessive sugar intake more often, and the gap between them and the others was statistically significant(pE.05). As to the importance of oral health by the number of child and academic credential, those who had two children(36.0%) taught them the importance of oral health frequently(pE.01), and the better-educated mothers taught about it often(pE.05). The gap between the groups and the others was significant. 3. As for experience of visiting dental institutions, the working mothers visited dental institutions more often than the stay-at-home mothers, and the gap between them was statistically significant(pE.05). Regarding purpose of the visit, the largest group aimed to get treatment(64.6%), followed by having a dental checkup(14.6%) and receiving preventive treatment(13.5%). As to any inconveniences in using dental institutions, those who were working and who were in the upper income bracket found it more inconvenient to do that because of a long distance or time constraints. The gap between them and the others was significant. 4. In regard to concern for dental care, the mothers who were better educated(pE.001) and whose family income was 3 million won or more had their teeth scaled more often, and the gap between them and the others was statistically significant(pE.01). The rate of the regular visitors of dental institutions stood at 32.7 percent of the junior-college graduates, 31.0 percent of the mothers receiving college or higher education and 10.1 percent of the high-school graduates(pE.01). And those who earned larger income paid a visit to dental institutions more often and on a regular basis. The gap between them and the others was statistically significant(pE.05).

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.1
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• pp.190-198
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• 2018

In recent years, non-welded building hardware has been installed by bolt assembly is used. The non-welded building hardware method can reduce accidents caused by welding, and can be constructed by bolt assembly, which can reduce labor costs and shorten the construction period. However, there is a need for a method to compensate for the occurrence of buckling at the time of construction. The purpose of this study is to evaluate the behavior of joints between steel pipe and fastener and to evaluate the behavior of joints of non-welded and welded hardware frame. As a result, it was found that the foundation steel structure without welded joints was deformed to a rotation angle of member much larger than the allowable interlayer displacement angle 0.01 to 0.02 required according to the seismic load rating in the seismic load resistance system.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.1
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• pp.81-90
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• 2007

The purpose of this study was to assess the effect of light-tip distance on the shear bond strength of a visible light-cured glass ionomer cement(Fuji Ortho LC ; GC, Japan) cured with three different light curing units : a halogen light(Elipar Trilight ; 3M ESPE, Seefeld, Germany), a Light Emitting Diode (LED, Elipar Freelight2 ; 3M ESPE, Seefeld, Germany) and a plasma arc light (Flipo ; LOKKI, France). 1. When used at a distance of 0mm from the bracket, the three light curing units showed no statistically different shear bond strengths. At distance of 3 and 6mm, no significant differences were found between the halogen and plasma arc lights, but both had significantly higher shear bond strengths than the LED light. 2. The halogen light and plasma arc light showed that no significant differences in bond strength were found among the three distances. Using the LED light, a greater light-tip distance produced significantly lower shear bond strengths.