• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.5
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• pp.92-100
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• 2010

Combustion stability rating tests of 75-tonf-class thrust chamber for technology demonstration were carried out at a low pressure. Two kinds of mixing heads were used in this study. One of them has injectors of 631 and the other has injectors of 721. Mixing head with injectors of 631 showed a self-oscillation instability at the chamber pressure of 30 bar. Mixing head with injectors of 721 showed that a high frequency combustion stability was maintained under the same pressure and the same mass flow rate. But mixing head with injectors of 721 generated a self-oscillation instability at the chamber pressure of 20 bar and it was found that stability boundary region was changed due to the configuration of a mixing head from these results.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.457-462
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• 2012

Daylighting software is an important component to predict the performance of daylighting system in advance of a field demonstration study with installing them in buildings. PHOTOPIA is a powerful software to generate a candela distribution curve(CDC) of an active daylighting system like a tracking dish concentrator. With PHOTOPIA, a set of candela distribution curves was generated under clear sky conditions and different solar altitude angles. The candela distribution curves were then imported to RADIANCE for rendering and analysis on the daylighting performance of a tracking dish concentrator when it installed in a actual class room without windows. As a result, the daylight collection efficiency of the dish concentrator was 68.4% when we assumed that there was no tracking error. It was found that candela(cd) and total lumens(lm) increased with solar altitude rising, whereas the distribution angle was fixed. The illuminance uniformity on the work plane in the class room was relatively low, 0.12, while the illuminance uniformity on the area of $2.7m^2$ to which the light was illuminated was considerably high, 0.60. The maximum illuminance was 1,340lux with a solar altitude angle of 80 degrees.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.79-87
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• 2017

Korea Aerospace Research Institute has being developed a staged combustion cycle rocket (SCCR) engine with high specific impulse to send a 3-ton class satellite into geostationary orbit while conducted Korean Space Launch Vehicle (KSLV) II project. The SCCR engine is different from the KSLV-II engine, which is open cycle engine using a gas-generator. The SCCR engine with closed cycle is composed of a pre-burner, a turbo pump, and a main combustor. The technology demonstration model (TDM0) was assembled and tested in the 7ton-class engine combustion test facility of Naro Space Center, and the combustion test was successfully conducted. Afterward engine-shaped SCCR engine model (TDM1) is being designed and developed for the next combustion test.

• Journal of the Korean Society of Earth Science Education
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• v.15 no.1
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• pp.16-26
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• 2022

This study was to investigate what pre-service teachers pay attention to when designing science lessons. As a result of analyzing the responses of pre-service teachers, it is analyzed that pre-service teachers are designing science lessons with emphasis on science inquiry, considering students' interest, level, and treatment of misconceptions, and closely related to daily life. In particular, it was found that elementary school pre-service teachers made a lot of comments on science class design that emphasizes experimentation and inquiry, so it was found that emphasizing inquiry was recognized as an important point in science lesson design. It is very positive that pre-service teachers recognize important aspects of science education, such as emphasizing inquiry. In addition, it is suggested that the opportunities for class design and demonstration through collaboration with teachers and colleagues should be increased for pre-service teachers' professional development of teachers.

• Fashion & Textile Research Journal
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• v.8 no.6
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• pp.634-638
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• 2006

The significance of this study is the demonstration of a new method of preservation procedure for national-treasure-class cultural-assets by examining the characteristics of the Jeogori relic, presumed to be that of King SeJo, and validating the preservation process. This Jergori as well as the wooden Munsu-donja Buddha statue from which they were found are designated as national treasure. The Jeogori relic is made of light silk and dimensions mark 77 cm in length, 67 cm in width, and 94 cm in sleeve length. It is a typical Jeogori worn in the Chosun Dynasty. Preservation procedure was in the following order: Removing dust and pollutants by vacuum, washing, removing creases, reinforcing the clothes, settling at paulownia backboard, and packing. Storage and exhibition of remains was executed with as minimal folding as possible, and microbiological damage prevention was performed by dyeing antibacterial treatment with eugenol onto supporting cloth. The relic, conservatively treated in accordance with the above procedure, is currently kept at the storage facility of the citadel Museum in the Woljeong Temple. It is displayed annually to the general public for approximately two weeks.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.9
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• pp.2854-2865
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• 1996

The concept of variable-geometry truss structure(VGTS) is introduced as a class of actively controlled adaptive structure. VGTS can purposefully vary its geometric configurations by changing the lengths of some members of the structure. General kinematics and inverse kinematics of a statically determinate VGTS(variable geometry truss structure) are studied. The solution technique is based on the Jacobian matrix obtained via joint equilibrium equations. Pseudoinverse control method is applied to resolve the redundancy of a large VGTS. two types of actuator layout of octahedral type VGTS, VG truss and Stewart platform, are compared. Introducing the concept of performance index, Stewart platform based layout was found to has less consumption energy and manipulation time. A functional VGTS model with 3 octahedral modules is designed and manufactured for the labaratory demonstration. Six vertically located length-variable members are used to create general 6 d.o.f. motions.

• Perspectives in Nursing Science
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• v.9 no.2
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• pp.136-145
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• 2012

Purpose: The purpose of this study was to verify the educational effectiveness of the Objective structured clinical examination (OSCE) module development activities on nursing students in the areas of performance skill, knowledge, self-directed learning readiness, and problem solving ability for medication skill. Methods: This study was a nonequivalent control group non-synchronized post-test design. The subjects (N=47), who agreed to participate in this study, were assigned to either the experimental (n=24) or control group (n=23). The experimental group was trained with OSCE module development activities for four days. The control group was trained with a traditional demonstration and practice class for the same amount of time as the experimental group. Medication performance skill and knowledge tests and surveys were done to measure self-directed learning readiness, and learning satisfaction after the experimental treatments. Results: The experimental group which participated in the OSCE module development activities showed significantly higher performance skill, self-directed learning readiness, and problem solving ability for skin test and insulin medication than that of the control group of traditional education. Conclusion: It is recommended to use the OSCE module development activities for nursing students in nursing education-learning in order to improve nursing skills.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.94-98
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• 2017

Research for developing 9 tonf-class staged combustion cycle engine which is high performance upper stage engine has been conducted. Technical demonstration model of the staged combustion cycle engine was installed in combustion test facility of Naro space center. Combustion tests of Power-pack which consists of pre-burner and turbopump without main combustion chamber and combustion tests of engine have been conducted. The vacuuming process of hydraulic lines is introduced and the characteristics of turbopump and hydraulic lines of engine combustion test are described in this paper.

• Transactions of Materials Processing
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• v.13 no.6 s.70
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• pp.540-545
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• 2004

Ever since the ideal forming theory has been developed for process design purposes, application has been limited to sheet forming and, fur bulk forming, to two-dimensional steady flow. Here, application for the non-steady case was performed under the plane-strain condition based on the theory previously developed. In the ideal flow, material elements deform following the minimum plastic work path (or mostly proportional true strain path) so that the ideal plane-stram flow can be effectively described using the two-dimensional orthogonal convective coordinate system. Besides kinematics, fur a prescribed final part shape, schemes to optimize a preform shape out of a class of initial configurations and also to define the evolution of shapes and boundary tractions were developed. Discussions include the two problematic issues on internal tractions and the non-monotonous straining. For demonstration purposes, numerical calculations were made for a bulk part under forging.

• Journal of the Korea Safety Management & Science
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• v.14 no.4
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• pp.125-136
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• 2012

In most child-care facilities, homeroom teachers take the responsibilities for safety education, which has been conducted in class hours on a regular basis. It was found that most homeroom teachers are lacking in teacher training opportunities, and the younger they are, the less training experience they get. Teachers with fewer teaching careers had a greater interest in safety education and training courses. In addition, homeroom teachers have been utilizing monthly toddler magazines as a method to acquire knowledges for safety education and prevention of safety accidents. The safety accidents which have most frequently occurred in care-care facilities turned out to be stumble and tear, and infants aged 3 years or younger were found to be easily exposed to the safety accidents mainly due to the frolic between peers during the free-choice activity time. The homeroom teachers recognized only traffic safety education among the range of safety training courses, which varied depending on teaching career such as traffic safety education and indoor/outdoor safety environment training, etc. In addition, it turned out that the safety training methods were limited to the utilization of discussion techniques, role-playing, description and demonstration.