• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.05a
• /
• pp.972-975
• /
• 2002

An understanding of tribological behavior in CMP(Chemical Mechanical Polishing) is one of the most important things to reveal the mechanism of material removal. In CMP, the contact type is thought to be semi-direct, elastohydrodynamic contact type from the Stribeck diagram, which is a combination of solid-solid direct contact and hydrodynamic lubrication with thin liquid film. This study is focused on the decay of friction force during CMP from two points of view, one of which is change of the real contact area and the other is the decrease of the elastic modulus of the pad caused by the increase of the temperature during CMP Experiments are implemented with elastic modulus measuring system and tool dynamometer. Results show that the decay of friction force during CMP results from the decrease of the real contact pressure working on an abrasive, which is induced by the decrease of elastic modulus of pad caused by the increase of temperature. And, the phenomenon is thought to be happen specially in the case that the weight concentration of abrasive in slurry is small enough.

• Journal of the Korean Society for Precision Engineering
• /
• v.14 no.4
• /
• pp.30-37
• /
• 1997

This thesis is concerned with the study on the characteristics of the tool failure occuring at the beginning of cutting in finish machining of hardened steels such as carbon tool steel and alloy tool steel by a ceramic tool (Al$_{2}$O$_{3}$+TiC) with nose radius. In the machining of hardened carbon steel STC3, the wear mechanism on the flank face of the ceramic tool is abrasion wear. The mode of tool failure is developed into catastropic fracture with flaking. It is thought that the fracture caused by FeO and TiO$_{2}$ results from the oxidation of Fe in the workpice and TiC in the ceramic tool and the deposit of Fe formed on the surface of the ceramic tool. In the machining of hardened alloy steel STD11, the wear mechanism on the flank face of the ceramic tool is that abrasion and adhesion wear exist simultaneously. The mode of tool failure at the beginning of cutting features is DOC notch wear. It is thought that the DOC notch wear caused by FeO and TiO$_{2}$results from the oxidation of Fe and TiC in the workpiece and ceramic tool, respectively.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.21 no.2
• /
• pp.561-569
• /
• 1994

The autotransplantation procedure were performed for the cases with impacted maxillary anterior teeth, which were thought unrealistic by the treatment with surgical exposure and orthodontic traction into the arches. The results were as follow : 1. As the treatment with autotransplantation is the last resort, the case indicated should be selected cautiously by adequate case analysis. 2. In order to reduce postoperative complication, damages to periodontal ligaments and adjacent bony structures should be minimized by conservative surgical procedures. 3. After autotransplantation procedures, postoperative endodonic treatment and continuous follow-up check with clinical and radiographic examination should be followed. Although the autotransplantation procedure is not the treatment of choice in most cases, it was thought to be a good alternative in certain cases when orthodontic treatment is unrealistic with continuous study to overcome the handicaps.

• Korean Journal of Health Education and Promotion
• /
• v.18 no.3
• /
• pp.77-88
• /
• 2001

This study was conducted to examine middle and high school students' knowledge level of first aid, health promotion, and safety. Data were collected from 1.165 students from March 6, 2000 to April 4, 2000. The results of this study are summarized as follows. 1. 80.1％ of the respondents felt the necessity of first aid. The sources of information about methods of first aid were school (43.9％), mass media (15.6％), and self-study (10.5％). 30.0％ of them never learned the methods of first aid. 2. In the case of obtaining information on first aid through mass media, 58.2％ of them got it from TV. 7.3％ of them obtained it from magazines, while 5.8％ of them got it from newspapers. According to their viewpoints of adequate time to teach the methods of first aid, 38.6％ of them thought that the methods had to be taught in the primary school and 25.2％ of them thought that they had to be taught in the kindergarten. 24.9％ of them replied that the methods had to be taught in the middle school, while 11.3％ of them replied that they had to be taught in the high school. 3. The points for knowledge of first aid were 98.29:t20.91 on the basis of 150 points (65.5 points on the basis of 100 points). The points showed significant differences in the variables of sex, education level, numbers of siblings, parents' education level, and guardian's occupation.

• Journal of the Korean earth science society
• /
• v.31 no.2
• /
• pp.185-204
• /
• 2010

Inquiring earth science phenomena is characterized by the followings: a big scale of time and space, inaccessibility, uncontrollability, and complexity. Thus, it is very difficult or, in some cases, impossible to investigate them through the actual manipulation in laboratories. Therefore, it is necessary to provide chance for students to experience scientific inquiry without actual manipulation in earth science classes. This study is to explore the role of reasoning based on a thought experiment as a representative model without actual manipulation, and to investigate features of various inquiry models using reasoning in classes. We can make implications when applying for applying each inquiry model to earth science classes, proposing a reasoning-based inquiry model embedded in earth scientific phenomena.

• Korean Journal of Human Ecology
• /
• v.13 no.5
• /
• pp.741-749
• /
• 2004

The purpose of this study was parents' perception on young children's safety life, safety accident, and safety education and provided basic data of administrating parent education for young children's safety. Subjects of this study were 620 parents (310 fathers and 310 mothers) of young children attending at four public kindergartens and two day care centers located in C city and D county. The results of the study were as follows: First, regarding parents' perception on young children's safety life, parents thought that their perception and attitude would mostly affect young children' safety life. Second, with regard to parents' perception on safety accident, half of parents experienced such safety accident as accident during play, traffic accident, accident in dangerous places, accident from dangerous matters, accident in sport activities, fire, and electric shock. Third, most parents looked upon safety education as very important one, and fathers were more satisfied with the safety education administered by kindergartens. Fourth, with regard to parents' perception on parent education for young children's safety, most parents thought that parent education for safety would be necessary. They ranked traffic and play accidents as the most important contents of safety education.

• Journal of the Korean Institute of Rural Architecture
• /
• v.15 no.4
• /
• pp.103-110
• /
• 2013

This study aims to draw the basis documents for rural landscape management of Daewon-Ri through frequency analysis of landscape elements and preference analysis of rural landscape. The results are as follows. First, according to the frequency analysis of the landscape elements, a distant view is few effect characteristics in rural village landscape planning. It is acted as the landscape elements that degree of integration and skyline of the building to see more nearby than it are the most important. In addition, in the case of the establishment of the landscape management planning, the landscape elements in the close view is the most important. Second, It is thought that the scenery which natural environments and residential quarter match is the most desirable for the par of the landscape preference in the rural village. On the other hand, about the scenery of an old historic building, the residents of a city considers it as an affirmative factor of the rural village landscape, but rural village inhabitants are negative. Finally, it is thought that the excessive public designs by government sponsored enterprise are undesirable for the scene of the village.

• Korean Journal of Community Nutrition
• /
• v.5 no.1
• /
• pp.23-35
• /
• 2000

The purpose of this study was to find the sociopsychological factors influencing the compliance of dietary regimen in diabetes by using focus group interviews. The data were collected from fifty three diabetes patients in eleven focus groups from September 1997 to March , 1998 in Seoul and Suwon Korea. The interviews were tape-recorded and the contents of the interviews were analysed by researchers. The subjects knew the causes, complications, and therapies of diabetes although they were incorrect at times . Patients had a wide range of outcome expectations from very optimistic to pessimistic. They recognized diabetes as a disease which needs life-time care, and they though that good care could provide a normal life. One the other hand they thought diabetes could lead to death through complications, and cause financial problems as well as social isolation. As for self-efficacy they recognized the importance of compliance to diet regimen but they thought the diet therapy was very difficult and were not very willing to follow it. They felt medical professionals, especially doctors, were influential for the therapies. However they frequently felt counselling provided by doctors was insufficient in time and content and led to attitude problems. They felt support from families and others was often insufficient and inadequate. Nutrition education fostering outcome expectation, social support, and self-efficacy is needed to increased compliance. The most influential referents were medical professional including doctors, nurses, dieticians, so their role in diet therapy should by emphasized.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.58 no.4
• /
• pp.602-608
• /
• 2009

In this thesis, output voltage, current and power of solar module were classified by irradiation from data of overall operating characteristics collected for one year in order to manage efficient photovoltaic generation system and deliver maximum power. In addition, from these data, correlations between irradiation of photovoltaic cell and amount of power given by photovoltaic cell was quantitatively examined to deduce optimization of the design and construction of photovoltaic generation system. As I-V characteristics according to a temperature range of 10~50[$^{\circ}C$], the area of I-V characteristics were increased with an increase in temperature. Since this area corresponds to the power, output power is thought to have increased with temperature. As output power characteristics according to a temperature range of 10~50[$^{\circ}C$], output power was increased with an increase in temperature. Since output power increases with temperature increase, the result corresponds well to the related equation on temperature and output power. As I-V characteristics according to a irradiation range of 100~900 [$W/m^2$], voltage and current were increased with an increase in irradiation. The result is thought of as an increase in output power with increasing irradiation. As output power characteristics according to a irradiation range of 100~900 [$W/m^2$], output power was increased with increasing irradiation. This result corresponds well to the related equation on irradiation and output power.

• Journal of the Korean Society of Safety
• /
• v.25 no.3
• /
• pp.78-82
• /
• 2010

This study is to test insulation mortar mixed with wastepaper and sawdust to find out its insulation performance. Therefore, wastepaper and sawdust have been added to normal mortar. They are analyzed for the above purpose using compressive strength and insulation performance. It is found that the more wastepaper and sawdust will be mixed, the lower heat conductivity will be taken. Wastepaper and sawdust mixture will be more 2.0% then the insulation mortar quality can be compatible with the 3rd kind of the standard. Optimal mixture for insulation will be wast paper:sawdust=4:6. Cohesive test of materials showed that test material has stronger than stand are $0.10N/mm^2$. It is satisfactory the test result showed a range of $0.12{\sim}0.15N/mm^2$ from the test result. Optimal mixture of wastepaper and sawdust have been found out from the study comprehensively, exclusive of the proportion of wastepaper:sawdust = 8:2. It is thought that standard of length deformation; 0.5% is reasonable. This means that deformation of mortar itself can be considered. But it is also Shown that water mixture has also been sharply changed at first flow test. Therefore, it is thought that absorbed water content in the material gave considerable effect to variation rate.