• Journal of Power Electronics
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• v.14 no.2
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• pp.315-323
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• 2014

An optimized space vector pulse width modulation (SVPWM) method with common mode voltage elimination and neutral point potential balancing is proposed for an open-end winding induction motor. The motor is fed from both of the ends with two neutral point clamped (NPC) three-level inverters. In order to eliminate the common mode voltage of the motor ends and balance the neutral point potential of the DC link, only zero common mode voltage vectors are used and a balancing control factor is gained from calculation in the strategy. In order to improve the harmonic characteristics of the output voltages and currents, the balancing control factor is regulated properly and the theoretical analysis is provided. Simulation and experimental results show that by adopting the proposed method, the common mode voltage can be completely eliminated, the neutral point potential can be accurately balanced and the harmonic performance for the output voltages and currents can be effectively improved.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2007.05a
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• pp.227-230
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• 2007

The expansion of open education and the 7th revision of educational curriculum have brought big changes in the school facilities. In response to the integrated curriculum for the first and second grades of elementary school, various plans, such as open classroom, expanded classroom size, and the installation of multi-purpose space, have been attempted. However, such plans have appeared in the form of an open classroom--a uniform spatial composition. As a result, a plan for unit learning space to support the educational curriculum and activities for low grade levels is still insufficient. In the case of advanced countries, a lot of studies on space are being actively conducted to develop the creativity of children and to facilitate free-style learning, and such space is actually applied to a real educational environment. Therefore, this study will analyze the spatial composition of unit learning space for low grade level elementary schools in Korea. From the cases of advanced countries, a more concrete proposal will be suggested to diversify unit learning space for low grade levels.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.1
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• pp.28-34
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• 2015

HCCI (Homogeneous Charged Compression Ignition) hydrogen engine has relatively narrower operation range caused by backfire occurrence due to the rapid pressure rising by using higher compression ratio and significant reaction velocity. In this study, to grasp of backfire process and characteristic in the HCCI research hydrogen engine, in-cylinder pressure, intake pressure and backfire limit range are analyzed with compression ratio and intake valve open timing, experimentally. As the result, it is observed that knock is occurred just before backfire occurrence in HCCI hydrogen engine but not spark igntion type, this phenomenon is always the same for the above variables. Also backfire limit range are expanded up to 50% for the more retarding intake valve open timing in this operating conditions.

• Advances in Traditional Medicine
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• v.4 no.4
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• pp.249-252
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• 2004

The methanol extract of Diospyros peregrina bark was studied for its effect on the central nervous system (CNS) using the pentobarbitone induced sleeping time test, the open field test and the hole cross test in Swiss albino mice. The present investigation revealed that the extract, at the doses of 250 and 500 mg/kg, significantly prolonged the pentobarbitone induced sleeping time in mice though the onset of sleep was delayed as compared to the control. In open field test, the depressing effect was prominent from the second observation period (30 min) and persisted throughout the entire experimental period (240 min). In the hole cross test, the depressing effect was observed from the second observation period (30 min) and persisted up to fifth observation period (120 min) for 250 mg dose group and up to sixth observation period (180 min) for 500 mg dose group. These results support the finding that D. peregrina bark extract at the above doses has CNS depressing effects and indicate that D. peregrina bark may contain biologically active constituent(s) having CNS depressant activity.

• Korean Journal of Materials Research
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• v.32 no.2
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• pp.85-93
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• 2022

Porous mullite-corundum ceramics were prepared using organic foam impregnation method with alumina and silica as raw materials. The influence of alkaline treatment and surfactant modification on polyurethane foam were studied. Effects of sintering process and material composition on porous mullite-corundum ceramics were investigated. The results show that the hang-pulp quantity of polyurethane foam increases with alkaline treatment. After treatment with 3 wt% SDS solution, the hang-pulp quantity of polyurethane foam further improved. Open porosity of sample decreased with elevation of sintering temperature and holding time, and compressive strength of sample showed a trend opposite to the change of porosity. The open porosity of the sample was enhanced by the increase of m(Al₂O₃/SiO₂); the compressive strength decreased with increase of m(Al₂O₃/SiO₂). However, when m(Al₂O₃/SiO₂) was 2.5, the compressive strength of the sample reached 6.23 MPa, and the open porosity of the sample was 80.7 %.

• Clinics in Shoulder and Elbow
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• v.2 no.1
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• pp.60-73
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• 1999

Purpose : The purpose of this study was to compare patients with anterior shoulder instability who were treated with an open Bankart procedure with those treated with an arthroscopic procedure, and to evaluate factors influencing the final outcomes and recurrence. Materials & Methods : One hundred seven shoulders underwent open Bankart repair, and fifty-one shoulders were treated arthroscopically. Average followup for open group was 34 months, and for arthroscopy group was 25 months. The Bankart Rating System by Rowe was used to evaluate the clinical outcome of the procedure. And, the patients were asked about any changes concerning their sports and professional activities. Results: According to Bankart Rating system by Rowe, open group had 97% fair to excellent results with 2 recurrent dislocation(1.8%) and 4 recurrent subluxation(3.6%), and arthroscopy group had 94% fair to excellent results with 3 recurrent dislocation(5.8%) and 4 recurrent subluxation(8%). In open group, 9 shoulders(8.4%) had the mild limitation of range of motion at the time of followup, and 2 shoulders(3.9%) in arthroscopy group. Age and gender do not seem to be a significant factor contributing to an increased re-recurrence rate. The incidence of re-recurrence seems to be affected by dominance, frequency, and patient's activity. The size of Bank art lesion might be also considered as a contributing factor. Conclusion: Either open or arthroscopic Bankart procedures are safe and effective methods with acceptable results if an adequate patient's selection, precise surgical technique and proper postoperative care are done. And arthroscopic surgery could be considered if the anterior instability is non-dominant, non-athlete, traumatic unidirectional and Bankart lesion has minimal erosion of the glenoid and it has thick and mobile labrum.

• School Mathematics
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• v.19 no.1
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• pp.153-170
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• 2017

This study conducted an analysis of types of reasoning shown in students' solving a problem and processes of students' reasoning according to type of problem by posing an open-ended problem where students' reasoning activity is expected to be vigorous and a multiple-choice problem with which students are familiar. And it examined teacher's role of promoting the reasoning in solving an open-ended problem. Students showed more various types of reasoning in solving an open-ended problem compared with multiple-choice problem, and showed a process of extending the reasoning as chains of reasoning are performed. Abduction, a type of students' probable reasoning, was active in the open-ended problem, accordingly teacher played a role of encouragement, prompt and guidance. Teachers posed a problem after varying it from previous problem type to open-ended problem in teaching and evaluation, and played a role of helping students' reasoning become more vigorous by proper questioning when students had difficulty reasoning.

• The korean journal of orthodontics
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• v.11 no.2
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• pp.109-123
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• 1981

The author studied and analyzed statistically 112 adults female ranging in age from 18 to 20 years with normal occlusion, 56 adults female ranging in age from 18 to 24 years with deep overbite and 53 adults female ranging in age from 18 to 28 years with open bite by vertical cephalometric analysis. The results were as follows; 1. In comparing normal occlusion with deep overbite and open bite, skeletal linear measurements were more significant than dentoalveolar linear measurements. SN-MP angle, SN-OP angle, PP-OP angle and Xi angle (ANS-Xi-Pog) were significant in anglular measurements. 2. Upper posterior facial height (SE-PNS), upper anterior alveolar height, lower posterior alveolar height, lower posterior alveolar height/lower anterior alveolar height and SN-PP angle were non significant between deep overbite and open bite. 3 The most significant items between deep overbite and open bite were lower anterior facial height (ANS-ME) and SN-MP angle. 4. Correlation coefficients of angular measurements were higher in deep overbite, while that of linear measurement total anterior facial height (N-ME) was higher in open bite. 5. In the multiple regression equation, significant variables were total anterior facial height (N-ME), lower anterior alveolar height, upper anterior alveolar height, upper posterior alveolar height, Xi angle (ANS-Xi-Pog) and ramus height (AR-Go) in deep overbite, and total anterior facial height (N-Me), lower anterior alveolar height, ramus height (AR-Go), lower posterior alveolar height, PP-MP angle and upper posterior facial height (SE-PNS) in open bite.

• Journal of Korean Elementary Science Education
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• v.29 no.3
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• pp.262-276
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• 2010

The purpose of this study was to investigate and analyze the elementary teachers' views and students' views about the difficulties in teaching and learning on open inquiry activities of elementary school science. Semi-structured interviews were conducted individually with three elementary teachers who have serviced more than three years, and with twenty four elementary students attending schools located in Cheongju City. And their anecdotes were collected and analyzed. The interview questions were developed through Seidman's steps to acquire the reliability in the interview data. From the interviews and anecdotes, we found that elementary teachers' views about the difficulties of teaching open inquiry activities: the difficulties of teaching in finding inquiry problem and planning inquiry, the difficulties of managing group activities, the difficulties of managing class hours for inquiry, the lack of the students' inquiry abilities, and problems on students' affective characteristics. And the students have the views about the difficulties in doing open inquiry activities: the difficulties of finding inquiry problem and planning inquiry, being unaccustomed to write reports, the troubles with investigating, problems on affective characteristics, the difficulties of joining in a group, and the lack of inquiry abilities. The teachers give suggestions for effective application of the open inquiry activities: first, the teachers must encourage students' emotion and will in doing open inquiry activities, second, there must be the steady inquiry teaching and learning in ordinary elementary science classes. Based on the results, this study suggested that elementary teachers should concern specially about students' being unaccustomed to write reports and the troubles in doing scientific investigation.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.11
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• pp.1591-1598
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• 2004

To isolate the $\beta$-galactosidase producing thermophilic bacteria, samples of mud and water were collected from hot springs of avolcanic area near Golden Springs in New Zealand. Among eleven isolated strains, the strain of KNOUC112 produced the highest amounts of $\beta$-galactosidase at 40 h incubation time (0.013 unit). This strain was aerobic, asporogenic bacilli, immobile, gram negative, catalase positive, oxidase positive, and pigment producing. Optimum growth was at 70-72$^{\circ}C$, pH 7.0-7.2, and it could grow in the presence of 3% NaCl. The main fatty acids of cell components were iso-15:0 (30.26%), and iso-17:0 (31.31%). Based on morphological and biochemical properties and fatty acid composition, the strain could be identified as genus Thermus, and finally as Thermus thermophilus by phylogenetic analysis based on 16S rRNA sequence. So the strain is designated as Thermus thermophilus KNOUC112. A gene from Thermus thermophilus KNOUC112 encoding $\beta$-galactosidase was amplified by PCR using redundancy primers prepared based on the structure of $\beta$-galactosidase gene of Thermus sp. A4 and Thermus sp. strain T2, cloned and expressed in E. coli JM109 DE3. The gene of Thermus thermophilus KNOUC112 $\beta$-galactosidase(KNOUC112$\beta$-gal) consisted of a 1,938 bp open reading frame, encoding a protein of 73 kDa that was composed of 645 amino acids. KNOUC112$\beta$-gal was expressed as dimer and trimer in E. coli JM109 (DE3) via pET-5b.