• International Journal of Aeronautical and Space Sciences
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• v.9 no.2
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• pp.98-106
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• 2008

The motive gas of a supersonic ejector is supplied from different sources depending on the application. The performance of an ejector that is represented by the secondary flow pressure, starting and unstarting pressures heavily depends on the molecular properties of the motive gas. The effects of specific heat ratio of the motive gas were investigated experimentally for an axi-symmetric annular injection type supersonic ejector. Both the starting pressure and unstarting pressure, however, decreased with the increase of the specific heat ratio of the motive gas. It was discovered that the secondary flow pressure increased as the specific heat ratio of the motive gas decreased even if the stagnation pressure of the motive flow was invariant. However, when the motive gas flow nozzle area ratio is large enough for the motive gas to be condensed, different tendency was observed.

• The KSFM Journal of Fluid Machinery
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• v.5 no.2 s.15
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• pp.22-28
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• 2002

Steady state flow calculations are conducted for the newly-designed turbo-pump inducers to validate the performance of Tascflow code. Hydrodynamic performance is evaluated, and structures of the passage flow and leading edge recirculation are also investigated. The calculated results show good coincidence with the experimental data of the static pressure performance and velocity profiles near the leading edge. Upstream recirculation, tip leakage and vortex flow at the blade tip and near leading edge are main sources of pressure losses. Amount of pressure losses from the upstream to the leading edge corresponds to that of pressure losses through the whole blade. The total viscous losses are considerably large due to the strong secondary flow.

• Journal of Applied Reliability
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• v.13 no.2
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• pp.129-140
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• 2013

As a fundamental experimental study for reliability improvement of lithium ion secondary battery, degradation mechanism was investigated by microscopic observation and acoustic emission monitoring. Microstructural observation of the decomposed battery after cycle test revealed mechanical and chemical damages such as interface delamination, microcrack of the electrodes, and solid electrolyte interphase (SEI). Acoustic emission (AE) signal was detected during charge and discharge of lithium ion battery to investigate relationships among cumulative count, discharge capacity, and microdamages. With increasing number of cycle, discharge capacity was decreased and AE cumulative count was observed to increase. Observed damages were attributed to sources of the detected AE signals.

• Hwankyungkyoyuk
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• v.2 no.1
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• pp.92-99
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• 1991

According to our secondary school curriculum for natural science and technical circles, there be used 353 of chemical reagents including 24 kinds of harmful and toxicant components. At present, most school are discharging their school laboratory waste water without any chemical and physical treatments. So as to solve the environmental problem for water pollution, this study tried to research a kind of adsorbant utilizing saw dust, wasted wood sources and designed the simple processing system using the adsorbent. This adsorbent was made by extracting lignin substances from raw saw dust under the solution of 0.5N-NaOH at the temperature of $100^{\circ}C$. Their metal removed rates was measured not only by processing of column and vessel. but also by comparing the standard solution and real waste water. The results were proved as more than 90(%) of the adsorptive efficiency on the average from Pb, Cd, Cu except Cr(VI)in case of the school experimental waste water soaked in vessels a long with 4g of the adsorbent for 24 hours. The new processing system enables to remove most harmful and toxicant metals by filtering, sedimenting and adsorbing at the low cost.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.482-485
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• 2004

On the basis of theoretical studies on the effect of the cylinders attached to semi-infinite screens, the tangential sound power-transport parallel to the surface of the attached cylinder is minimized by means of a secondary sound field, which is generated from a part of the attached cylinder. The numerical study shows the possibility of deflecting the incident sound by minimizing the acoustic surface impedance of the upper sections. The acoustical shadow region was more pronounced in both near- and far-field compared to the passive case with rigid surface, i.e. without active control. For a relatively wide frequency range it was possible to enhance shielding effects only with few secondary sources and error microphones. In this paper effects of some control parameters on the actively controlled sound field near the top edge of noise barriers are studied. Results of numerical study and model measurements are shown and discussed.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.4
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• pp.717-726
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• 2021

Tourism is one of the key economic drivers not only in Vietnam but also in the world. This study explores the awareness and perceptions of key stakeholders such as local residents, tourism businesses, and tourists on sustainable tourism development in the Mekong Delta in Vietnam. Both quantitative and qualitative research approaches have been used with the secondary and primary data to provide insights on the subject. The secondary data is from vast sources, including the governmental department of tourism, statistical departments, annual all-level governmental reports, businesses, and others. The primary data is from the survey by questionnaires with 230 enterprises, 720 local residents, and 670 tourists and from the semi-structured and in-depth interviews conducted with local residents, businesses, tourists, local authorities' officers, and especially with 5 experts who are also stakeholders of Mekong Delta tourism. The results will help the related authorities understand the awareness and perceptions of the key stakeholders and deliver valuable information and a concrete delineated roadmap toward sustainable tourism development of the research settings.

• Research in Mathematical Education
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• v.27 no.1
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• pp.93-109
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• 2024

This study compared the perceptions of 548 Korean and Indonesian secondary school teachers in the COVID-19 era and examined factors affecting their intention to continue online learning. Based on survey data, the two countries were compared on seven factors (teaching readiness, challenges and issues, competencies that require training, sources of support, types of support, and endurance). Furthermore, we examined what factors influence the intention to continue online learning. As a result, Korean teachers perceived their teaching readiness for online learning to be less than that of Indonesian teachers. Indonesian teachers perceived that they did not receive sufficient support. Additionally, factors affecting the intention to continue online learning differed depending on the country. Based on these results, we suggested implications for integrating online learning into mathematics education.

• The Journal of Korean Academy of Sensory Integration
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• v.1 no.1
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• pp.73-79
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• 2003

The significant historical events and developments in the area of approach for sensory integration in Korean Society of Sensory Integration Therapists(KSSIT) are reviewed to stimulate future planning and clinical application in professional and health promotion. The paper reviewed the purposes of establishment, the role of members, progress of regular meetings and education for members and seminars in KSSIT. This review is placed within the context of the progressive period of KSSIT history, 1997-2003. Historical data are used as primary sources as records of events in KSSIT's homepage, official transcripts, professional articles, and secondary sources such as news letters for occupational therapists and oral information from first members. This review examined current actions and thinking, and suggests further actions and thinking for progressive professional education programs, research, clinical applications and public relations in sensory integration approach in KSSIT.

• Biomolecules & Therapeutics
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• v.24 no.6
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• pp.561-571
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• 2016

Marine biosphere is the largest one of the earth and harbors an enormous number of different organisms. Living conditions differ fundamentally from those in terrestrial environment. The production of specific secondary metabolites is an important adaption mechanism of marine organisms to survive in the sea. These metabolites possess biological activities which make them interesting as possible drugs for human. The review presents sources, chemistry, production and pharmacology of FDA approved marine derived pharmaceuticals arranged according to their therapeutic indication. Four of the presently seven approved drugs are used for the treatment of cancer. Each another one is applicated for treatment of viral diseases, chronic pain and to lower triglyceride level in blood. Some other products are of interest in diagnostic and as experimental tools. Besides, this article describes challenges in drug development from marine sources, especially the supply problem.

• Journal of Distribution Science
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• v.13 no.3
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• pp.21-29
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• 2015

Purpose - This paper addresses the role of designers in design-oriented firms and how they should work together with other organization members. The aim of this paper is to investigate how designers generate ideas and cooperate with others as well as how their participation in decision-making reflects on corporate design strategies. Research design, data, and methodology - An in-depth exploratory study examined how designers actually perform their roles in enterprises; in addition, information, knowledge, communication among designers, and sources of creativity were examined. Hanssem and Ikea grew as design-intensive businesses in a declining industry. Data were obtained from interviews with the design staff of each company as well as secondary sources. Results - Designers were found to use their designs to communicate with customers as well as with communities outside of the enterprise; they also participated in overall decision-making in relation to important design strategies. Conclusions - This study emphasized the increasing importance of the innovative and creative role of designers; thus, it might substantially help companies to develop their own design capabilities and deploy design strategies.