• Journal of Advanced Marine Engineering and Technology
• /
• v.33 no.4
• /
• pp.451-458
• /
• 2009

This experimental study was conducted to investigate macroscopic characteristics of the flash boiling spray with tow component mixing fuel. Homogeneous Charge Compression Ignition (HCCI) is a newer combustion method for internal combustion engines to reduce nitrogen oxide and particulate matter simultaneously. But it is difficult to put this combustion method to practical use in an engine because of such problems as instability of combustion in low load operating conditions and knocking in high load operating conditions. In HCCI, combustion characteristics and exhaust emissions depend on conditions of air/fuel mixture and chemical reactions of fuel molecules. The fuel design approach is achieved by mixing two components which differ in properties such as density, viscosity, volatility, ignitability and so on. We plan to apply the fuel design approach to HCCI combustion generated in a real engine, and examine the possibility of mixture formation control using the flash boiling spray. Spray characteristics of two component fuel with a flash boiling phenomenon was investigated using Shlieren and Mie scattering photography. Test fuel was injected into a constant volume vessel at ambient conditions imitated injection timing BTDC of a real engine. As a result, it was found that a flash boiling phenomenon greatly changed spray structure, especially in the conditions of lower temperature and density. Therefore, availability of mixture formation control using flash boiling spray was suggested.

• Journal of Agricultural Extension & Community Development
• /
• v.8 no.1
• /
• pp.41-58
• /
• 2001

The purpose of this study was to develop plans for activating the 4-H clubs in Korea. Data for this study were collected from 125 members in 4-H clubs and 140 extension educators who participated in 4-H activity. Total of 265 responses were analyzed after data screening. The Statistical Package for Social Sciences(SPSS) for Windows for the personal computer were used to analyze the data. Frequency, percentage, ANOVA, and LSD test for post-hoc interpretation were employed to analyze the data with a statistical significance level of .05. Based on the conclusions of this study, following recommendations were offered: To activate rural youth organizations, especially 4-H clubs in Korea the following measures should be included in the plans for activation; 1) To classify membership into student and non-student clubs to focus on the needs of active members; 2) To establish clear objectives for club activities; 3) To enhance field-oriented operation of clubs; 4) To develop various activity programs that members could be fascinated; 5) To promote subject matter specialists in order to support club activities effectively; and 6) To clarify functions and roles of extension service centers and non-governmental organizations in order to support club activites.

• Journal of Sport and Applied Science
• /
• v.3 no.1
• /
• pp.1-14
• /
• 2019

Numerous types of sporting events have been hosted in Korea during the last decades. Sport events produce various types of data, and there is a clear necessity of storing and utilizing this information. From this background, the purpose of this study is to draw complex sports categories from international sport events life cycles in order to categorize standards of knowledges management system. This study utilized qualitative methods: expert groups discussion for overall life cycle steps and in-depth interviews for detail life cycle steps. The results show that there are several life cycle steps: bidding, preparation, operation, evaluation, post management steps. To be more specific, for the bidding step, there are check, plan, implementing detail phase; and the preparation step is based on event preparation Basis Build, event preparation implementation, test and supplementation phases. For the operation step, event operation system switch, event operation during the period, finish operation phases are deducted. Evaluation and post management step do not have detail phases. Efforts to store and utilize knowledge can be one of the starting points to make the operation of sport events efficiently.

• Proceedings of the KSR Conference
• /
• 2010.06a
• /
• pp.1430-1436
• /
• 2010

Tubular member is hollow and is an excellent source of structural member with great buckling resistance and tortional resistance. With its development and simplicity in structure, steel tubular truss has the ability to be structured in long span bridges, without a stiffener. Recently, it has been used in many countries in Europe, Canada, Japan, and the US with the help of international committees such as CIDECT(International Committee for the Development and Study of Tubular Structures and International Institute of Welding). The most important problem when using the tubular member is the fact that it is difficult to test the fatigue stress determined by nominal stress, since geometrical stress concentration occurs due to the welded joint's nod of complexity. The purpose of this study is to compare and examine current theories and widely applied Hot Spot stress determinations through finite element analysis, which is about welded joints of steel tubular truss. We would like to suggest a way of design practice which involves a bridge plan with rarely domestically used steel tubular truss` basic research data as well as considering the future of tubular member.

• Proceedings of the KSR Conference
• /
• 2010.06a
• /
• pp.1669-1679
• /
• 2010

Related to the on-going "Train Control System Project of Pilot Line Construction for Urban MAGLEV Train", activities by each phase shall be conducted to achieve SIL4 level and obtain safety certification from the Independent Safety Assessment(ISA), based on the IEC standards((IEC 62278/62279 and IEC 62425) for the first time in Korea. This thesis describes the introduction of IEC standards, system assurance activities (such as plan, analysis, test, verification and validation) in compliance with requirements management and project life-cycle and relations with the safety assessment activities; and certification activities (such as document reviews and audits) through system RAMS activities, software quality assurance activities and safety assessment, for the purpose of achieving a successful safety certification at the time of completing the project as system assurance activities including software and safety certification activities in order to acquire the safety certification for train control system which does not exist at all in domestic cases. It is believed that overall system safety assurance activities in this project will contribute to develop more upgraded products of the domestic train control system on the quality and safety point of view, find overseas markets and establish a bridgehead in the future.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2012.04a
• /
• pp.263-269
• /
• 2012

Condition-based maintenance (CBM) has been used as a useful concept for optimizing maintenance plan and decreasing maintenance cost in several kinds of plant sites. This study introduced an example that developed an integrated management system for maintenance parameters and hydraulic turbine of hydro-power plant in order to improve its maintenance system as applying CBM techinique. The integrated management system consists of three parts. One is a hardware part including PDA inspection system and several kind of precision measuring instruments. Another is a vibration monitoring system on hydraulic turbine. The other is a software part that takes charge of making hierarchy tree of maintenance parameters and their inspection route, managing accumulated database, assessing health condition of components, and supporting interface with other enterprise management system. The system has been installed at Chuncheon Hydro-power plant for test and demonstration. It is expected that the system can contribute database construction for diagnostics and prognostics on facility health condition and systematic accumulation of know-how on operation and maintenance of plant.

• Fire Science and Engineering
• /
• v.23 no.4
• /
• pp.25-31
• /
• 2009

With rapid growths of economy and technology, structures and forms of buildings have been diversified and complicated. Buildings also have become higher and larger than ever before. As a result, more people use a building and more combustibles exist in the building. Without understanding of combustion characteristics and the establishment of a fire safety plan in case of a residential fire, it is expected great loss of lives and properties. In this study, experiments were carried out to promote an understanding of the combustion characteristics of combustibles in the building. Sofa and bed were used as combustibles in the experiment. Heat release rate of the sofa was about 1.9MW. Heat release rate of the bed was approximately 650kW.

• The Journal of Korean Association of Computer Education
• /
• v.19 no.6
• /
• pp.55-68
• /
• 2016

Informatics curriculum revised 2015 proposed the use of block type and text type of programming language by organizing problem solving and the programming unit in a spiral. The purpose of this study is to find out whether the algorithms helps programming learning and whether there is a positive transition effect in block type programming learning to text type programming trailing learning. For 15 elementary school students was conducted block type and text type programming learning. As a result of the research, it is confirmed that writing the algorithm in a limited way can interfere with the learner's expression of thinking, but the block type programming learning has a positive transition to the text type programming learning. This study is meaningful that it suggested a plan for the programming education which is sequential from elementary school.

• Korean Journal of Child Studies
• /
• v.35 no.4
• /
• pp.79-101
• /
• 2014

The purpose of this study was validate the Preschool and Kindergarten Behavior Scale-2(PKBS-2) and develop the Korean version PKBS-2(K-PKBS-2) through the phases of concept and statistical review. For this purpose, this study conducted PKBS-2 for teachers with 1,119 young children in Jeonbuk province. During the factor structure review, according to the results of exploratory factor analysis, 30 items and 4 factors(social interaction, social cooperation, social compliance, and social independence) in social skills scale and 40 items and 4 sub-factors of 3 factors(internalizing behavior, externalizing behavior, and interpersonal emotional behavior) in problem behavior scale were extracted. In addition, confirmatory factor analysis, the model fits of social skills and problem behavior scales were higher than the original test and very high reliability and internal consistency were produced. During external factor review, convergent validity and discriminant validity were verified. After cultural specificity and cultural universality between PKBS-2 and K-PKBS-2 were discussed, K-PKBS-2 was presented as e scale which is very useful for the screening, prevention, and intervention program plan of challenging behavior behaviors in young children in Korea.

• The Journal of the Korean dental association
• /
• v.38 no.6 s.373
• /
• pp.549-557
• /
• 2000

ㆍPurpose: This study was performed to investigate the initial conservative treatment for TMD patients using careful counselling and medication prospectively. ㆍMaterials and Methods: Careful counselling and medication were performed in 51 TMD patients and 27 patients had follow-up check 2 months or more. Diagnosis of TMD was based on medical history and, physical and radiographic examination. TMD included masticatory disorder, internal derangement, degenerative joint disease, inflammatory joint disorder. and problems resulting from extrinsic trauma. All patients had chief complaints of TMJ pain, mouth-opening limitation. joint noise, and/or referred pain. We counselled and explained to the patient about the pathogenesis, etiologic factors, diagnosis and treatment plan for abut 10 minutes. We prescribed nonsteroidal anti-inflammatorv analgesic(Somalgen) and amitriptyline 10mg per day for 2 weeks. We informed the patient of the attention sheet and taught self-exercise of jaw. The patient were assessed by answering the questionnaire of subjective evaluation of TMD & maxillofacial pain. Questionnaire of an activity limitation. Questionnaire of a jaw function, and Questionnaire for the evaluation of TMD. ㆍResults: In questionnaire for the evaluation of TMD, 88.5% of 26 patients answered that the treatment was efficacious. 71.4% of 21 patients answered no problem in everyday life. There were significant differences between pretreatment and final follow-up in the evaluation of the subjective pain in the following sections: opening widely, chewing, resting, morning, masticatory muscle, and temporal portion(SAS program, paired T-test, P = 0.05). ㆍConclusions: Considerate counselling and proper medication could be significantly effectve in the initial treatment of TMD.