• Earthquakes and Structures
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• v.23 no.6
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• pp.535-547
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• 2022

Handball sport, as its name postulates, is a team sport which highly physical workout. During a handball play, several ball impacts are applied on the hands resulting vibration in the forearm, upper arm, shoulders and in general in whole body. Hand has important role in the handball's game. So, understanding about the dynamics and some issues that improve the stability of the hand is important in the sport engineering field. Ulna and radius are two parallel bones in lower arm of human hand which their ends are located in elbow and wrist joint. The type of the joint provides the capability of rotation of the lower arm. These two bones with their ends conditions in the joints constructs a 4-link frame. The ulna is slightly thinner than radius. So, understanding about hand kinematics in handball's game is an important thing in the engineering field. So, in the current work with the aid of a multi-physics simulation, dynamic stability analysis of the ulna and radius bones will be presented in detail.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.3
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• pp.121-126
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• 2006

HVOF thermal spray coating of Co-alloy T800 is progressively replacing the classical hard coatings such as chrome plating because of the very toxic $Cr^{6+}$ ion known as carcinogen causing lung cancer. For the study of the possibility of replacing of chrome plating, the wear properties of HVOF Co-alloy T800 coatings are investigated using the reciprocating sliding tester both at room and at an elevated temperature of $1000^{\circ}F\;(538^{\circ}C)$. The possibility as durability improvement coating is studied for the application to the high speed spindles vulnerable to frictional heat and wear. Wear mechanisms at the reciprocating sliding wear test are studied for the application to the systems similar to the sliding test such as high speed spindles. Wear debris and frictional coefficients of T800 coatings both at room and at an elevated temperature of $1000^{\circ}F\;(538^{\circ}C)$ are drastically reduced compared to those of non-coated surface of parent substrate Inconel 718. This study shows that the coating is recommendable for the durability improvement coatings on the surfaces vulnerable to frictional heat. The sliding surfaces are weared by the mixed mechanisms such as oxidative wear, abrasion by the sliding ball slurry erosion by the mixture of solid particles and small drops of the melts and semi-melts of the attrited particles cavitation by the relative motions among the coating, sliding ball, the melts and semi-melts. and corrosive wear. The oxide particles and the melts and semi-melts play roles as solid and liquid lubricant reducing the wear and friction coefficient.

• Journal of the Korean Institute of Landscape Architecture
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• v.31 no.1
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• pp.66-77
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• 2003

The purpose of this study is to propose a standard putting green management program to prepare fast green suitable for international golf tournaments, and to conform whether the reported green speed model can be applied to the real field situations. The west course of Lakeside Country Club was selected for the case study. This study was initiated on August 1st, 2001 and continued through October 4th, 2001. The results are summarized as follows: 1. Following the long-term schedule, 'penncross' creeping bentgrass turf was mowed at 5.0mm(37days), 4.5mm(8days), 4.0mm(4days), 3.5mm(2days), 3.2mm(2days), 3.0mm(2days), 2.8mm(2days) and the mowing direction was changed daily. Variation of mowing height was reduced to a minimum range. Core aerification with deep tines was applied 19 days prior to the first practice round. Dry sand maintenance was top-dressed 2 times at 1.5mm/$m^2$ on the 17th day and 1.0mm/$m^2$ on the 10th day. Minimum irrigation was applied to keep the turf alive. During the tournament preparation week, dew on the putting greens was removed by using a sponge roller. Following the dew removal, the greens were cut once each morning at a height of 2.8mm. The mower used was the 21 inch working behind mower equipped with a tournament bedknife and 11 reel blades. Following the mowing, the peens were rolled with a light-weight roller in one direction in the morning. Rolling was used as a finishing technique to ensure that the surface was as smooth as possible, and to provide true ball roll and maximum green speed. In conclusion these management practices satisfied the daily green stimpmeter readings required for USGA championship play. 2. During the period of tournament preparation, no damage was observed on the green, but scalping in green edge appeared in about 0.39% of the total area of 18 greens in the west course.

• Journal of the Korean Institute of Landscape Architecture
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• v.14 no.2
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• pp.43-68
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• 1986

It is necessary that children's actual activities in the playgrounds should be analyzed for the study on the children's playgrounds. The purpose of this study is to establish the design principles for the improvement of the children\`s playgrounds in apartment complex by means of the various methods ; behavior mapping, questionaires and photo simulations. For the purpose of data collection, children are divided into three groups-infants(0 to 4 years), young children(pre ; 5 to 8 years, post ; 9 to 11 years), teenagers(7.2 to 14 years). The study results are as follows; 1) Analysis of behavior mapping : (a) Approximately 70 percent of the children observed stayed in the playground less than 20 minutes. (b) Playing time for each play apparatus was less than 5 minutes. (c) As a result of the observation, the duration time in the attic was 1 hour or more (d) The swing was the most frequently used apparatus as children's first and last choice. (e) Most of the users were young children(46.5%). 2) Analysis of questionaires : (a) Children considered that the existing playgrounds were lack of shadows and the play apparatuses are not interesting. (b) They felt danger and crowding at the multi-used wooden apparatus. 3) Suggestions for the playground design : It is necessary that the playgrounds are divided into the infants, the young children's and the teenagers'playground. (a) The infants'playground needs about 50 square meters and needs to be located in the apartment court. (b) The young children's playground needs about 330 to 660 square meters and needs to be located adjacent to the pedestrian road. (c) The teenagers'playground needs about 660 to 1000 square meters, which is needed for various ball games.

• Journal of the Korean Institute of Landscape Architecture
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• v.31 no.3
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• pp.91-106
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• 2003

The objective of this study is to present management methods for Korean golf courses to achieve fast green that satisfies international golf tournament standards during an official golf tournament. The results of both the research and the comparative study on putting green management of 24 tournaments hosted in Korea and 12 tournaments hosted in overseas countries in 2002 are as follows: 1. As for the putting greens in Korean and foreign golf courses where official golf tournaments were held, Korean of official golf tournaments were mainly opened in two-green system golf courses contrary to the foreign cases, and the average size of the greens in Korean golf courses was shown to be greater than that of foreign golf courses to some extent, although there was no difference between the types of turf varieties. 2. Results have shown that unlike foreign golf courses, Korean golf courses were managing putting greens by using greens mowers mostly for general (non-tournament) management, and elaborate rolling attempts failed during official tournament flay week because of an insufficient number of rollers to be input. Therefore, Korean golf courses are required to make efforts to secure 21-inch working-behind greens mowers equipped with tournament bedknifes and 11 blades, which is the greens mowing equipment for professional tournaments, and rollers above all things in order to achieve fast green during tournament play week 3. In attempting to achieve green as fast as that of foreign golf courses, Korean golf courses need to consider the method of performing mowing at 3.0mm height or less with greens mowers for professional tournaments. This needs to be done more than two times, followed by a continuous practice of rolling for proper management.

• Journal of the Korea Furniture Society
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• v.26 no.4
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• pp.346-355
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• 2015

It suggests a closet design for infants in consideration of space utilization, furniture arrangement, and goods storage by integrating a baby's closet and toy chest, which was used for storage of baby's toys and play instrument. For this, it conducted and analyzed data research on the infants' toy chests in the domestic and overseas market and based on such approach, the colors that helped development of infants' cognition and emotion were selected while suggesting familiar animal characters for infants. Without considering separate arrangement of furniture and toy chest within limited space, it allowed space utilization and provided enough storing space. Also, the attached ball casters enabled easy carry of the closet and with this function, it helps infants arrange and store goods by themselves so that making them feel a sense of accomplishment. For effective spatial utilization as well as security of its genuine storage function, the closet and toy chest were combined in this study. Thus, it is believed that development of such multifunctional furniture will suggest the direction of researches on domestic furniture development that are conducted to maximize utilization of residential space for the people living today.

• Korea-Australia Rheology Journal
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• v.13 no.3
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• pp.141-148
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• 2001

In this research, experimental studies leave been performed on the hydrodynamic interaction between a spherical particle and a plane wall by measuring the force between the particle and wall. To approach the system as a resistance problem, a servo-driving system was set-up by assembling a microstepping motor, a ball screw and a linear motion guide for the particle motion. Glycerin and dilute solution of polyacrylamide in glycerin were used as Newtonian and non-Newtonian fluids, respectively. The polymer solution behaves like a Boger fluid when the concentration is 1,000 ppm or less. The experimental results were compared with the asymptotic solution of Stokes equation. The result shows that fluid inertia plays all important role in the particle-wall interaction in Newtonian fluid. This implies that the motion of two particles in suspension is not reversible even in Newtonian fluid. In non-Newtonian fluid, normal stress difference and viscoelasticity play important roles as expected. In the dilute solution weak shear thinning and the migration of polymer molecules in the inhomogeneous flow field also affect the physic of the problem.

• Research in Mathematical Education
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• v.18 no.3
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• pp.171-185
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• 2014

Mathematically deductive reasoning skill is one of the major learning objectives stated in senior secondary curriculum (CDC & HKEAA, 2007, page 15). Ironically, student performance during routine assessments on geometric reasoning, such as proving geometric propositions and justifying geometric properties, is far below teacher expectations. One might argue that this is caused by teachers' lack of relevant subject content knowledge. However, recent research findings have revealed that teachers' knowledge of teaching (e.g., Ball et al., 2009) and their deductive reasoning skills also play a crucial role in student learning. Prior to a comprehensive investigation on teacher competency, we use a case study to investigate teachers' knowledge competency on how to teach their students to mathematically argue that, for example, two triangles are congruent. Deductive reasoning skill is essential to geometry. The initial findings indicate that both subject and pedagogical content knowledge are essential for effectively teaching this challenging topic. We conclude our study by suggesting a method that teachers can use to further improve their teaching effectiveness.

• Korean Journal of Adult Nursing
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• v.17 no.1
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• pp.44-55
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• 2005

Purpose: The purposes of this study were to examine the effects of recreational therapy (60 minutes * 3times/week * 6weeks) on dementia behavior & affection, and activity of daily living of senile people with dementia. Methods: The subjects were 27 senile people with dementia, 16 experimental group, 11 control group, admitted at K hospital in Chungnam province in quasi-experimental study. The recreational therapy program was developed, based on the recreational program for senile welfare made by athletics science research institute in Chungnam National University(1997). It consisted of rhythm game, ball play, and beanbag game. The data were collected through questionnaires from May 1st to June 10th 2003 and were analyzed using descriptive statistics, ${\chi}^2$-test, Fisher' exact test, and Man Whitney U test. Result: The dementia behavior and affection score was significantly different between the two groups (U=32.5, p=.005). The ADL score was significantly different between the two groups (U=12.0, p=.000). There were significant decrease in dementia behavior & affection, and improvement in ADL in the experimental group compared to the control group. Conclusion: Recreational therapy intervention was proved effect in decreasing dementia behavior & affection and promoting ADL of senile people with dementia. We recommended re-test in containing a communicating variable.

• Korean Journal of Materials Research
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• v.19 no.7
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• pp.349-355
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• 2009

Metal thin film patterns on a LTCC substrate, which was connected through inner via and metal paste for electrical signals, were formed by a screen printing process that used electric paste, such as silver and copper, in a conventional method. This method brought about many problems, such as non uniform thickness in printing, large line spaces, and non-clearance. As a result of these problems, it was very difficult to perform fine and high resolution for high frequency signals. In this study, the electric signal patterns were formed with the sputtered metal thin films (Ti, Cu) on an LTCC substrate that was coated with protective oxide layers, such as $TiO_2$ and $SiO_2$. These electric signal patterns' morphology, surface bonding strength, and effect on electro plating were also investigated. After putting a sold ball on the sputtered metal thin films, their adhesion strength on the LTCC substrate was also evaluated. The protective oxide layers were found to play important roles in creating a strong design for electric components and integrating circuit modules in high frequency ranges.