• Proceedings of the KSME Conference
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• 2001.11b
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• pp.610-615
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• 2001

Effects of rotor-stator blade count ratio on the unsteady aerodynamic characteristics of a cascade was studied by using a Navier-Stokes code. Present Navier-Stokes code is a parallel code and works on a multi-cpu machine. It is based on the SIMPLE algorithm and uses QUICK scheme for convection terms and second order back difference for all temporal derivatives. Computations were carried out for two cases : case 1 is for 3 stator cascade passages subjected to two upstream wakes while case 2 is for 2 stator cascade passages subjected to three upstream wakes. Numerical solutions show that rotor-stator blade count ratio plays a significant role in the unsteady aerodynamic characteristics of the stator cascade. Case 2 shows smaller unsteady fluctuation than case 1, even if they show the same time averaged value. The smaller fluctuation of case 2 is believed due to strong interaction between unsteady vortices. The unsteady lift variation of case 2 is shown to have many high frequency fluctuations as more unsteady vortices travel around the cascade. The unsteady turbulent kinetic energy due to the upstream wake is also shown to decay faster through the cascade passage than in the free stream.

• Journal of Mechanical Science and Technology
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• v.17 no.2
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• pp.246-253
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• 2003

The tribological mechanism between the valve plate and the cylinder block in oil hydraulic axial piston pumps plays an important role on high power density. In this study, the fluid film thickness between the valve plate and the cylinder block was measured with discharge pressure and rotational speed by use of a gap sensor, and a slip ring system in the operating period. To investigate the effect of the valve plate shapes, we designed two valve plates with different shapes . the first valve plate was without a bearing pad, while the second valve plate had a bearing pad. It was found that both valve plates behaved differently with respect to the fluid film thickness characteristics. The leakage flow rates and the shaft torque were also experimented in order to clarify the performance difference between the valve plate without a bearing pad and the valve plate with a bearing pad. From the results of this study, we found out that in the oil hydraulic axial piston pumps, the valve plate with a bearing pad showed better film thickness contours than the valve plate without a bearing pad.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.12
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• pp.5028-5057
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• 2015

In this paper, a new mathematical scheme of Macro Handover Management (MHM) in F-HMIPv6 networks based on Location Based Services (LBS) is proposed. Previous schemes based on F-HMIPv6 protocol usually suffer from three major drawbacks: First, They don't exploit the information about the user mobility behavior in order to reduce handover effects. Second, they only focus on the micro mobility level. Third, they don't consider the quality of service (QoS) of the traffic. The proposed MHM scheme avoids these drawbacks using the available information about Mobile Node (MN) such as user mobility patterns and MN's velocity to predict handover and improve network's QoS. It also takes the traffic type in consideration since it presents a major factor in locating QoS for the user. MHM is analyzed and compared with the F-HMIPv6. The results show that MHM improves the performance in terms of packet delivery cost, location update cost, and handover latency. The design of MHM comprises software package in the MN in addition to a hardware part in the network side. It has implications for communication, design, and pricing of mobile services.

• Journal of the Korean Society of Earth Science Education
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• v.6 no.3
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• pp.221-234
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• 2013

The purpose of this study was to examine the impact of the application of a creative thinking technique for development on the creativity and attitude toward science of the students in elementary school. In order to better assist students' levels of creative thinking process, creative thinking techniques were reorganized based on the features of creative learning content in science textbooks. Furthermore, related units from an elementary science textbook were analyzed to map out the lesson plans. The findings of the study were as follows. First, the creative thinking technique developed in this study could be applicable to teaching-learning activities. When a creative thinking technique is applied, that should carefully be selected in consideration of all the creativity elements to be covered in class, and that should be used in a manner to be covered in class, and that should be used in a manner to be appropriate at learner level. Second, the utilization of the creative technique turned out to have a good impact on boosting the creativity of the elementary schoolers. Third, the utilization of the creative technique turned out to exert a good influence on fostering the school children's attitude toward science.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1994.11a
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• pp.135-140
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• 1994

Over past decades, numerous in vitro model has been developed to investigate drug metabolism. In the order of complexity we found the isolated perfused liver, hepatocytes in co-culture with epithelial cells, hepatocytes in suspension and in primary culture and subcellular hepatic microsomal fractions. Because they can be easily prepared from both animals (pharmacological and toxicological species) and humans (whole livers as well as biopsies obtained during surgery) hepatocytes in primary culture provide the most powerful model to better elucidate drug behavior at an early stage of preclinical development such as : 1. the characterization of main biotransformation reactions. 2. the identification of phase I and phase II isozymes involved in such reactions 3. the evaluation of interspecies differences allowing the selection of a second toxicological animal species more closely related to man on the basis of metabolic profiles 4. the detection of the inducing and/or inhibitory effects of a drug on metabolic enzymes, the prediction of drug interactions 5. the estimation of inter-individual variability in biotransformation reactions. The use of hepatocytes, and in particular those obstained from humans, at an early stage of drug development allows the obtention of more predictive preclinical data and a better knowledge of drug behavior in humans before the first administration of the drug in healthy volunteers.

• Research in Community and Public Health Nursing
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• v.28 no.1
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• pp.98-106
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• 2017

Purpose: To understand the meaning of the lived experience with Person under train (PUT) for train or subway operators. Methods: The study was built on hermeneutic phenomenological themes from individual interviews of present-day train or subway operators in South Korea. Eight participants were selected to participate in the study. All qualitative data were analyzed using the heuristic guides of Van Manen. Results: Four fundamental lifeworld themes and eight sub themes emerged in the findings. The first theme of spatiality had'the place pressed by the darkness' and 'the train drags me there'. The second theme, corporeality had 'a foreboding fear', and 'debris of death that gets stuck in the whole body'. The temporality theme had'distorted time in chaos', and 'memory trapped in time'. Finally the last existential theme of relationality had 'intrapersonal encounter' and 'resentment and guilt'. Conclusion: The four existential lifeworld themes provided a framework for in-depth investigation of the operator's "lived experience." This leads to clear understanding of effects of PUT experience on related individuals. The findings imply that specific active nursing intervention strategies are necessary in order to treat affected train operators, and to prevent further issues in their work and private life.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.8 no.2
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• pp.244-258
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• 2001

Purpose: The purpose of this study was to develop and apply a conceptualized PBL module for Fundamentals of Nursing. Method: A case study method was used to describe and explore the Process of developing and implementing the PBL module. Result: This module included three PBL packages that were designed to deal with more complexed and indepth concepts as the packages proceeded. In order to achieved that, all the contents of Fundamentals of Nursing II and III were reorganized and integrated into three main concepts, hygiene, infection and dehydration. This module was implemented for first year college student nurses in the second semester of year 2000. The student self-evaluation results showed that they were generally satisfied with their achievement in learning, both final outcome and process. Also, the results indicated that they were more satisfied with the subject management, the lecturer and their peers after implementing PBL. Conclusion : This study demonstrated the potentiality for the application of a partially integrated PBL module within an existing subject. However, when student learning needs were beyond the extent of Fundamentals of Nursing, the lecturer had to set boundaries on learning content and this may have reduced the effects of learning. Therefore, the researchers emphasize the importance of developing an integrated PBL curriculum to maximize student learning outcomes.

• Journal of Industrial Technology
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• v.35
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• pp.3-8
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• 2015

A study has been made on defects which are formed in manufacturing processes of engine bearing and also on fatigue crack growth behavior in each step of bearing metal manufacturing. After the first step(sinter brass powder on steel plate ; Series A) many voids are made on brass surface and its size is decreased by the second step(rolling process of sintered plate ; Series B). After the third step(re-sintering step of brass powder and rolling ; Series C) the number of voids is decreased and its type shows line. The time of fatigue crack initiation and the growth rate of fatigue crack are in order of Series A, Series B, Series C. These reasons are that void fosters the crack initiation and growth, and residual stress made by rolling process effects on the crack growth rate in Series B, C. In forming and machining processes by use of final bearing metal, crack was observed at internal corner of flange and peeling off was observed at junction between steel and brass. Owing to the above crack and peeling off, it is considered that there is a possibility of fatigue fracture during the application time.

• Korean Institute of Interior Design Journal
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• v.20 no.4
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• pp.136-144
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• 2011

The purpose of this research is to analyze the manifestation of children's color education in the software in order to evaluate conditions of color education as well as improvement of its direction. The procedure and method of the research is begun from evaluating the characteristic of children's developmental stage, content analysis of the nation's organization of color education and analysis and evaluation of education program through the investigation on 8 different softwares in reward for the tournament. The results are as followings; First, the research shows that the elementary school stage of color education is inadequate in comparison to children's cognitive developmental stage. Second, most of the color theory was composed of characteristic of a color, stimulation of emotion and effects of psychology. Considering of children's cognitive development, it is necessary to make up for the basic of color theory and the system of color. Third, Softwares of color education program for 1 st. and 2nd grade in elementary school was so rare that it should be properly developed and made for systematic contents. Fourth, color education for the 5th and 6th grade children remained in understanding basic characteristics of the color which is below the par and brings the necessity for more professional and structural contents.

• Journal of the Korean Institute of Landscape Architecture
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• v.33 no.6 s.113
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• pp.1-11
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• 2006

The purpose of this study was to investigate the influence of natural landscapes in the context of work environments. The study examined the impact of natural landscapes on urban office workers' stress reduction and cognitive performance, using physiological, psychological, and cognitive measures. One-hundred-twenty urban office workers participated in the experiments. The physiological measures used were GSR (galvanic skin response) and IBI (interbeat interval), and the psychological measure was ZIPERS (Zucherman Inventory of Personal Reactions). Cognitive performance was measured using a mental arithmetic test that had been developed by a pretest. The results from the physiological, psychological, and cognitive measures converged to indicate that the natural landscape had more beneficial effects in relieving both psychological and physiological stress and in enhancing cognitive performance of the of office workers than the city landscape. The results suggest wide applications in the fields of workers' well-being and landscape research. First, the results can provide reliable information for promoting natural landscaping in work places in order to relieve worker stress and enhance cognitive performance. Second, the results provide an example for future empirical landscape research using multiple measurements, such as psychological, physiological, and cognitive tests. Third, they can foster experimental research to investigate the relationship between stress reduction and natural landscapes.