• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.1
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• pp.32-37
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• 1999

Twin blocks are bite-blocks that effectively modify the occlusal inclined plane to induce favorably directed occlusal forces by causing a functional mandibular displacement. One of the advantage is that full-time wear can be possible because of less interference with normal function such as eating and speaking. So rapid correction of malocclusion is expected. Reverse twin block appliance is modification for correction of class III malocclusion with sagittal component. For increased growth stimulation effort on premaxilla, lip pads can be added. But with lip pads, patients are incapable of full-time wear especially during mealtime. So, removable lip pads can be used for stimulation of growth on premaxilla without any restriction of function. The advantages of the reverse twin block appliance with removable lip pads are: 1. Full-time wear is possible (including mealtime). 2. Patients' cooperation and adaptation is excellent. 3. There is no period of dual bite. 4. Orthopedic correction is achieved by multiple modes, shortening the treatment time. The applied case shows that the reverse twin block appliance with removable lip pads is effective for treatment of class III malocclusion and can shorten the time of treatment.

• Tribology and Lubricants
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• v.35 no.6
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• pp.382-388
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• 2019

It is currently well known that surface textures act as lubricant reservoirs, entrap wear debris, and hydrodynamic bearings, which can lead to certain increases in load-carrying capacities. Until recently, the vast majority of research has focused on parallel sliding machine components such as thrust bearings, mechanical face seals, piston rings, etc. However, most sliding bearings have a convergent film shape in the sliding direction and their hydrodynamic pressure is mainly generated by the wedge action. Following the first part of the present study that investigates the effect of groove position on the lubrication performances of inclined slider bearings, this paper focuses on the effects of groove depths and film thicknesses. Using a commercial computational fluid dynamics (CFD) code, FLUENT, the continuity and Navier-Stokes equations are numerically analyzed. The results show that the film thickness and groove depth have a significant influence on the pressure distribution. The maximum pressure occurs at the groove depth where the vortex is found and, as the depth increases, the pressure decreases. There is also a groove depth to maximize the supporting load with the film thickness. The friction force acting on the slider decreases with deeper grooves. Therefore, properly designed groove depths, depending on the operating conditions, can improve the load-carrying capacity of inclined slider bearings as compared to the bearings without a groove.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.10
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• pp.3048-3057
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• 1996

Analysis model containing two inclined surface cracks on semi-infinite elastic body is established and analyzed on the basis of linear fracture mechanics to examine mutual interference of two surface cracks. Muskhelishvili's complex stress functions are introduced and a set of singular integral equations is obtained for a dislocation density function. The stress intensity factors at crack tip are obtained by using the Gerasoulis'method. When two surface cracks are parallel and have the same length, the values of $K_1$and $\Delta K_11$(variation of $K_11$) for crack 1 and crack 2 decrease by the mutual interference of two surface cracks as the distance between the two surface cracks shortens. The effect of mutual interference is remarkable in high friction coefficient. In case that two surface cracks are parallel, the values of $K_1$and $\Delta K_11$for crack 2 decrease as the length ratio ot crack 2 to crack 1 becomes small. As the crack inclination angle rises, the value of $K_1$ and the mutual interference of $K_1$for crack 2 increase and the value of$\Delta K_11$ for crack 1 becomes smaller than that for crack 2.

• The Korean Journal of Community Living Science
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• v.19 no.1
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• pp.21-30
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• 2008

This study conducted a survey to compare the size of ready-made clothes for different body shapes and body sizes, and to discover the differences in satisfaction with the size of ready-made clothes. The subjects were women in their 208 and 308 from Busan and Gyeongnam. The women were classified into groups: normal weight, overweight, and obese, using the Body Mass Index (BMI). The comparison of the body size showed a significant difference among the shapes; the average BMI in overweight women was 24.2 while that of obese women was 27.6. For the clothing size for each body shape, obese women most often wore size 77 and size 88, regardless of the sizes of upper and lower garments. The size consistency of upper and lower garments was the lowest in obese women. However, in most of the shapes, women tended to choose larger-sizes for lower garments than for upper ones. The more obese the subject, the less inclined they were to wear garments for their real body size. Satisfaction with the clothing size was significantly different between body shapes; the more obese, the lower the level of satisfaction with the size. As well, satisfaction with the fit of clothing at certain parts was shown to be low especially in the bust measurement, shoulder width, upper garment length, crotch length, and thigh circumference. When surveyed about the use of alterations for different body shapes, the results were that over 65% of subjects did not alter upper garments regardless of their body shape. Comparatively, 68% or above of all body shapes did do alterations to lower garments for example, the length of pants or skirts.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.11 no.2
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• pp.68-74
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• 2015

Time domain response analysis for vibro-impact nonlinear behavior of multi-span tube with loose supports was performed using commercial FEA code and user subroutine. Support geometry of multi-span tube with a finite gap is realistically modeled by analytical rigid surface. Model of hydrodynamic force is based on the Qusai-steady model which accounts for the inclined angle of relative flow velocity and time delay between flow force and resulting tube motion. During tube vibration from flow loading, impact and friction at the support location is simulated using commercial FEA code with master slave contact algorithm. Analysis results has reasonable agreement with those of references and test experience. Plan of further refinement of analysis model and future test verification is briefly introduced.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.7 no.1
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• pp.35-40
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• 2011

If a plugged tube in a steam generator is broken, it may damage nearby intact tubes. To prevent this damage, it is recommended that a stabilizer is installed into the plugged tube. However, the installation cost of a stabilizer is very high. So studies are required to determine the conditions on which the installation is necessary. For this purpose static loads and dynamic loads applied on a tube should be known to estimate the residual strength and remaining fatigue and wear life of a plugged tube. Two-dimensional and three-dimensional computational fluid dynamics (CFD) analyses are performed to obtain the drag coefficient for cross flow to a tube. Using the obtained drag coefficient, the static load can be estimated and the residual strength of a plugged tube can be calculated. An inclined flow problem is also analyzed and the vertical and horizontal forces are obtained and discussed.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.12
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• pp.66-72
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• 1997

This paper aims at reviewing the possibility application over normal or abnormal, detection used by AE and the wear characteristics of grinding process. In this study, when diamond bur in dentistry with chosen grinding conditions were tuned at grinding. The variation of grinding resistance and AE signal is detected by the use of AE measuring system. The tests are carried out in accordance with diamond burs and workpiece: arcyl and bovine. According to the experiment results, the following can be expected: AE has the possibility to detect the state normality and abnormality. Hpwever, the grinding resistance measuring can find it difficult to detect it. It can be accurately excepted from AE occurrence pattern in contact start point of diamond bur and bovine, grinding condition and derailment point. It is known that AErms is well compatible with grinding resistance. According to the increase of the material removal rate, the specific energy of the diamond bur is inclined to dectease and the grinding resistance has a tendency to increase.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.9
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• pp.1078-1085
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• 2011

Prediction of a minimum crack size for growth, which is defined as a crack size that grows fast enough to keep ahead of its removal by contact wear and periodic grinding, is the most demanding work to prevent rail from fatigue failure and develop cost effective railway maintenance strategy In this study, we investigated the wheel load increment due to a rail defect during a train ran over it, and its effect on the minimum crack size for growth. For this purpose, we developed simulation software based on the Fletcher and Kapoor's "2.5D" model and measured wheel load increment during a train passed over a defect. A maximum contact pressure and contact patch size were calculated by 3D FEM and crack growth analyses were performed by varying two of dominant contact contributors; surface friction coefficient(0.1, 0.2, 0.3 and 0.4) and crack aspect ratio. The minimum crack sizes for growth were calculated from 0.29 to 1.44mm depending on the contact conditions. They were decreasing with increasing surface friction coefficient and decreasing with crack aspect ratio(a/b).

• Journal of the Korean Society of Costume
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• v.49
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• pp.125-136
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• 1999

The present study was conducted to analyze(1) if there are any differences in jean's brand royalty according to the age·sex·educational background and income of consumers (2) the criteria for store choice by jean's brand royalty of consumers (3) the use of information souces by jean's brand royalty of consumers. The research method employed was normative-descriptive survey and questionnaires were main instrument to gather research materials. The survey was implemented from July 1st 1998 to the schools and two colleges and those who work at a comuter-related company and at a trade company. The data gathered was analyzed by mean standard deviation t-test ANOVA and Duncan -multiple range test. The results are summarized as follows: (1) 58.6% of the respondents were categorized as the brand loyalty group that was bigger than the non-brand loyalty group (41.4%) People in their late 2-'s were inclined to have the highest brand loyalty for jeans People in university and above had relatively higher brand royalty than to people with a high school or lower (2) Brand royalty group paid more attention on the quality on the quality of the fabric use; the trands of the products: brand name of the product: the distance of the store location : and the comfortable atmosphere of the store. Pleasant and kind services of the salesperson was considered as more important factor for store selection by the non-brand royalty group than by brand royalty group. (3) Almost all the information sources were used more often by brand royalty group than non-brand royalty group. For both groups their own experiences is most important information sources. The results shows that consumers have high brand loyalty for jeans product and also have many differences not only in the usage of information sources but also in the store selection criteria accorrding to the level of jeans brand loyalty . Therefore those industries carrying jeans should these points on their marketing strategies.

• Journal of the Korean Institute of Landscape Architecture
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• v.38 no.1
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• pp.129-136
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• 2010

This study was initiated to investigate thatch accumulation in several turfgrasses grown under two soil systems. The 45 centimeter deep USGA system was constructed with rootzone, intermediate and drainage layers. The mono-layer system, however, was made with only a 30cm rootzone layer. Turfgrasses used in the study were comprised of 3 varieties from Korean lawngrass of Warm-Season Grass(WSG) and 3 blends and 3 mixtures from Cool-Season Grass(CSG). A total of 9 turfgrass treatments were replicated three times in RCBD in both systems. Cultural practices for the research plot followed a typical maintenance program for highly managed turf. Treatment differences for thatch accumulation were observed among the turfgrasses in both soil systems. Thatch under the USGA system was 9% greater than under the mono-layer system due to its more favorable conditions for turf growth. Higher thatch depth was found with Korean lawngrass, 34~87% in the USGA system and 16~75% in the mono-layer system when compared with CSG. Among WSG, the Joongji variety was the highest in thatch layer under both the USGA and mono-layer systems. Kentucky bluegrass(KB) was the greatest among CSG, since it is a rhizomatous-type in growth habit, resulting in faster production of organic matter over bunch-type of tall fescue and perennial ryegrass. Proper depth in the thatch layer was known to be beneficial by enhancing the resiliency and wear tolerance of the turf in athletic fields. Thus, KB was considered to be a very excellent turfgrass in terms of turf quality, environmental performance, physical properties and soccer player safety. However, disadvantages such as poor water-holding properties, more inclined to injury from environmental stresses and severe diseases and insect injury were also expected where thatch was excessively accumulated. Therefore, these results demonstrate that more frequent measures for controlling thatch such as vertical mowing, topdressing or coring should be employed for soccer fields with Korean lawngrass and KB over other turfgrasses.