• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.12
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• pp.1061-1069
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• 2010

In this study, a simplified axisymmetric model is proposed for the problem of compressible internal flow past a microgap. Using numerical and experimental methods, the phenomena of choked flows are observed; these flows are induced by the acceleration of subsonic flows past the narrow cross-section of an annular shape made by a microgap. The relation between mass flow rate and differential pressure is obtained, and by comparing the result with experimental results, the reliability of the numerical results is discussed. The generation of a supersonic jet flow and its diffraction are visualized by performing the numerical analysis of axisymmetric compressible Navier-Stokes equations. This investigation greatly extends the physical understanding of the axisymmetric compressible flow, which has a wide range of engineering applications, e.g., in the case of valves in automotive power systems.

• Journal of the Korean School Mathematics Society
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• v.17 no.2
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• pp.275-290
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• 2014

This study aims to examine how secondary mathematics teachers perceive and how they use constructed-response assessment in their mathematics classrooms. For this purpose, we conducted a survey in Seoul, Inchun, and Gyeonggi-do; 189 teachers participated in the survey. Results from the data analysis suggest as follows: a) the secondary mathematics teachers participated in the survey seem to consider the primary goals of assessment through constructed-response items as evaluating student achievement and the development of students' thinking and creativity; b) the teachers perceive that constructed-response assessment would promote students' mathematical thinking and problem solving skills; c) in general, constructed-response items were included in both performance assessment(less than 20 percent) and paper-and-pencil test(20 to 40 percent); and d) constructed-response items were primarily used as a part of regular examination, rather than as an independent assessment.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.3
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• pp.353-358
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• 2010

This research introduces a new and improved design for a pneumatic cylinder driven roll feeder wherein each of the principal rotating feeder parts is configured so as to have feeding accuracy and to be low manufacturing cost. The feed pitch accuracy of the proposed roll feeder was evaluated by measuring lengths of cut offs of the strip stock with a shear attached to an air press. The air press was designed, manufactured, and mounted on the same table of the proposed roll feeder such that the strip stock maintained horizontal plane until the strip stock entered into the shear. The proposed roll feeder and the air press were designed to be operated automatically by a PLC employed controller. The feed pitch accuracy of the proposed roll feeder was analyzed by setting the pitch as 10, 12.5, and 15mm. At each predetermined feed pitch, the proposed roll feeder was tested 300 times as one test set and replicated three times. The average lengths of the cut offs of the strip stock ranged from 9.98 to 10.13mm, from 12.42 to 12.57mm, and from 14.96 to 15.06mm at the predetermined 10, 12.5, and 15mm feed pitch, respectively, among the total of 900 samples of each feed pitch. Main cause of variation of the length of the cut off of the strip stock fed by the proposed roll feeder was considered to be fluctuation of the air press during recompressing period of the air compressor to pressurize the air in the air tank. The largest difference between the maximum and the minimum length of the cut off was appeared while the air compressor recompressing the air. The air compressor used for this study restricted the air delivered to the proposed roll feeder while it was still running. Thus, this air delivery restriction problem should be improved by stabilizing the air press while the proposed roll feeder is running.

• Journal of Convergence for Information Technology
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• v.7 no.5
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• pp.75-82
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• 2017

Recently, as the roles and utilization fields of UAV become more diverse, demand for high - level mission has been increasing. To solve this issue, researches on the operation of multiple small UAVs and related systems have been actively carried out. The multiple small UAVs based application system has a problem that the task complexity of control personnel increases because the control personnel must continuously control and manage several small UAVs. Hence, it is necessary to develop a software platform that can perform efficient control in order to employ a multiple small UAVs based application system successfully. In this paper, we propose an effective ground control software platform for application systems using multiple small UAVs. We first analyze the requirements for the software platform, and design and implement software based on the analysis. Simulation using the X-plane flight simulator shows that multiple flight data are effectively displayed and that the image data transmitted from many small UAVs are simultaneously displayed in real time.

• Journal of the Korea Society of Computer and Information
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• v.19 no.6
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• pp.139-149
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• 2014

Much research has been conducted in educational robot, a new instructional technology, for K- 12 education. Several studies have shown that educational robot provides effective learning opportunities for students in both content areas of STEM(science, technology, engineering, and mathematics) and critical academic skills, such as collaboration, problem solving and communication skills. However, most studies to date on applications of educational robots have been conducted outside the formal education setting. This study analyzed the influence of using robots in an elementary school science class in Korea with regard to science learning motivation. A total of 121 students in fourth and fifth grades participated in the study. The experimental group was taught using robots in the science class, while the control group was taught using traditional methods. Analysis of covariance (ANCOVA) was conducted to compare the between-group differences in learning motivation before and after the experiment; an interview was also conducted for the experimental group. The study results showed a significant improvement (p<.05) in both learning motivation in the experimental compared with the control group. There was also positive response to learning with a robot. This study will play an important role in research on the use of educational robot in formal education in the future.

• Journal of the Korea Society of Computer and Information
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• v.18 no.5
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• pp.95-102
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• 2013

In metabolomics, metabolic pathway is represented by well-displayed graph. Metabolic pathways, especially, have a complex binding structure, which makes the graphical representation hard to visualize. There is a problem that edge crossings exponentially increase as the number of nodes grows. To apply automatic graph layout techniques to the genome-scale metabolic flow of metabolism domains, it is very important to reduce unnecessary edge crossing on a metabolic pathway layout. we proposed a metabolic pathway layout algorithm based on 2-layer layout. Our algorithm searches any meaningful component existing in a pathway, such as circular components, highly connected nodes, and the components are drawn in upper layer. Then the remaining subgraphs except meaningful components are drawn in lower layer by utilizing a new radial layout algorithm. It reduces ultimately reduced the number of edge crossings. This algorithm is the basis of flexible analysis for metabolic pathways.

• Journal of Korea Port Economic Association
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• v.26 no.4
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• pp.1-18
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• 2010

The purpose of this paper is to evaluate the green logistics of Korea enterprises. According to participate pan-nationally about environment problems, the field of logistics is required to transfer green logistics like increase efficiency of using energy and construct economic systems. And also environment-friendly policies of enterprises are playing important role. So authors selected and analysed factors through precedent study and questionnaire. Selected factors are cultivation about environment-friendly policy awareness to employees, Utilization environment-friendly resources, decrease of atmosphere pollution substance, company's promotion of outside environment-friendly policy. In order to shed light on these problem, fuzzy AHP method is adopted and the factor of cultivation about environment-friendly policy awareness to employees is the highest weight. And also result of the highest weight between enterprises that set policies about green logistics and factors' are The Korean Air, Glovis, Korea Express synthetically.

• Clinical and Experimental Reproductive Medicine
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• v.38 no.3
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• pp.126-134
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• 2011

Preimplantation genetic diagnosis (PGD) is gradually widely used in prevention of gene diseases and chromosomal abnormalities. Much improvement has been achieved in biopsy technique and molecular diagnosis. Blastocyst biopsy can increase diagnostic accuracy and reduce allele dropout. It is cost-effective and currently plays an important role. Whole genome amplification permits subsequent individual detection of multiple gene loci and screening all 23 pairs of chromosomes. For PGD of chromosomal translocation, fluorescence $in-situ$ hybridization (FISH) is traditionally used, but with technical difficulty. Array comparative genomic hybridization (CGH) can detect translocation and 23 pairs of chromosomes that may replace FISH. Single nucleotide polymorphisms array with haplotyping can further distinguish between normal chromosomes and balanced translocation. PGD may shorten time to conceive and reduce miscarriage for patients with chromosomal translocation. PGD has a potential value for mitochondrial diseases. Preimplantation genetic haplotyping has been applied for unknown mutation sites of single gene disease. Preimplantation genetic screening (PGS) using limited FISH probes in the cleavage-stage embryo did not increase live birth rates for patients with advanced maternal age, unexplained recurrent abortions, and repeated implantation failure. Polar body and blastocyst biopsy may circumvent the problem of mosaicism. PGS using blastocyst biopsy and array CGH is encouraging and merit further studies. Cryopreservation of biopsied blastocysts instead of fresh transfer permits sufficient time for transportation and genetic analysis. Cryopreservation of embryos may avoid ovarian hyperstimulation syndrome and possible suboptimal endometrium.

• YAKHAK HOEJI
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• v.58 no.1
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• pp.40-46
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• 2014

Drugs with a narrow therapeutic index (NTI) require very precise dosing. Warfarin and digoxin are the examples of NTI-drugs and dosing of them varies widely for different patients. However, in South Korea, only two strengths of warfarin and one of digoxin are commercially available. This is a big barrier for the precise dispensing and has potential safety risks to patients, particularly to elderly patients. To find a potential solution to the problem, an analysis of the prescribed doses and dispensing patterns of those drugs was performed. Data were collected by computer-facilitated prescription review in a university hospital. The period screened was from May 1st, 2012 to April 30th, 2013. All the prescriptions with either warfarin or digoxin tablets were selected for this study and dispensing patterns were analyzed according to the prescribed doses. A total of 17,017 warfarin prescriptions were analyzed; 8,148 for inpatient prescriptions, 8,869 for outpatient prescriptions, respectively. Of the 23 kinds of prescribed doses, 2 mg (19.9%) was most frequent, followed by 3 mg (13.2%) and 2.5 mg (11.7%). By analyzing the dispensing patterns, 60.3% (10,253) of the prescriptions required pill splitting and 72.0% of them were for the patients 65 years old and over. On the other hand, 4,350 digoxin prescriptions were included in this study. Of the 6 kinds of prescribed doses, 0.125 mg (71.2%) was most frequent, followed by 0.0625 mg (20.2%). Among the prescriptions for digoxin, 92.0% (3,998) should be split and 65.7% of them were for the patients aged 65 years and over. Despite limitations of strengths, various doses of warfarin and digoxin were prescribed. Furthermore, more than half of the prescriptions that required pill splitting were for elderly patients. The results from this study suggest that different strengths of warfarin and digoxin should be provided for accuracy of dispensing and safety for patients receiving them.

• Journal of the Korea Society of Computer and Information
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• v.15 no.8
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• pp.51-58
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• 2010

Programming education needs learning which is adjusted individual learners' level of their learning abilities. Recommendation system is one way of implementing personalized service. In this research, we propose recommendation method which learning items are recommended for individual learners' learning in web-based programming education environment by. Our proposed system for leveled programming education provides appropriate programming problems for a certain learner in his learning level and learning scope employing collaborative filtering method using learners' profile of their level and correlation profile between learning topics. As a result, it resolves a problem that providing appropriate programming problems in learner's level, and we get a result that improving leaner's programming ability. Furthermore, when we compared our proposed method and original collaborative filtering method, our proposed method provides the ways to solve the scalability which is one of the limitations in recommendation systems by improving recommendation performance and reducing analysis time.