• 유체기계공업학회:학술대회논문집
• /
• 2004.12a
• /
• pp.680-686
• /
• 2004

Recently, the application of variable geometry turbocharger (VGT) to the high speed direct injection (HSDI) diesel engine has gained more and more interest in automotive industry. A steady state experimental investigation has been undertaken on a 1.5L HSDI diesel engine to verify the benefits of VGT comparing to the standard engine having a waste gate turbocharger (WGT). Specifically, part load performances (e.g., fuel economy and emission) have been investigated under various vane angles of the VGT. The results show that the real exhaust gas recirculation (EGR) rate as well as the pumping loss is very important to improve break specific fuel consumption (BSFC). It was previously known that the pumping loss only is a main parameter. In addition, the trade-off relationship between BSFC and NOx according to boost pressure, and the decreasing tendency of NOx with increasing real EGR rate have been verified. 1-D numerical analysis also has been performed, and the numerical results are in good agreement with experimental results.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 1997.10a
• /
• pp.49-56
• /
• 1997

Most large strike-slip faults do not rupture their entire length during single faulting but generally break in segments which are different in location and time of faulting. Studies related to the development of the Yangsan fault have been reported based on partial results from characteristics of geolgocial distribution, geophysical prospecting and paleostress analyses. This paper shows, based on preliminary results, that the Yangsan fault could be divided into four structural areas along entire length. These areas are different in geological distribution, bedding attitude measured from sedimentary rocks, strike of main fault, geometry of small faults, termination types of fault tips, cyclic variation of fault zone width, and arrangement of paleostress. Therefore, the Yangsan fault could be divided into at least four segments.

• Macromolecular Research
• /
• v.10 no.3
• /
• pp.168-173
• /
• 2002

Unstabilized low-density polyethylene (LDPE) films and films formulated with hindered amine light stabilizer (HALS) were exposed to UV-radiation; and the physicochemical changes during photooxidation processes have been investigated using tensile, FTIR spectre-photometric and thermal analytical (DSC) techniques. The dependence of tensile properties (elongation- and stress-at-break), carboxyl index and heat of fusion on UV-irradiation time have been discussed. The use of HALS is found to be effective in maintaining the UV-mechanical properties of the LDPE films. The experimental results showed that there exists no correlation between mechanical properties and carbonyl index, whereas crystallinity correlates well with carbonyl index in unstabilized and stabilized films for irradiation times greater than 100 h. The rate of formation of carbonyl groups is found to be dependent on UV exposure time. Crystallinity of the film samples is strongly influenced by both exposure time and presence of HALS.

• Journal of the Korea Safety Management & Science
• /
• v.6 no.4
• /
• pp.25-37
• /
• 2004

Safety diagnostic indicator pointer can divide by greatly two. One is management (Software) side that one that differ with mechanical (Hardware) side that handle laying stress on equipment connected with safety manages organization and management connected with safety. Weight appropriates according to specific gravity that relevant element occupies in facilities. To give so big value in particular element in grant of weight pays attention because break balance of whole guideline and should gives. Finally, efficient safety net may see effect before self-regulation inside by minimum target establishment using AHP by government and legal, systematic countermeasure establishment for this, strict law application and each business proprietor and though activity and user's active safety activity forms harmony properly.

• Proceedings of the Safety Management and Science Conference
• /
• 2004.05a
• /
• pp.1-4
• /
• 2004

Need safety diagnostic indicator pointer that is objective as estimation basis to be scientific and manages systematically safety existing condition and level for city gas facilities. Safety diagnostic indicator pointer can divide by greatly two. One is management (Software) side that one that differ with mechanical (Hardware) side that handle laying stress on equipment connected with safety manages organization and management connected with safety. Weight appropriates according to specific gravity that relevant element occupies in facilities. To give so big value in particular element in grant of weight pays attention because break balance of whole guideline and should gives. Finally, efficient safety net may see effect before self-regulation inside by minimum target establishment by government and legal, systematic countermeasure establishment for this, strict law application and each business proprietor and though activity and user's active safety activity forms harmony properly.

• Proceedings of the KSR Conference
• /
• 1998.05a
• /
• pp.556-563
• /
• 1998

Railway bridges have a significant effect on the stress and displacement of continuous welded rail(CWR). Longitudinal compression force at high temperature, combined breaking or acceleration forces can introduce track buckling. On the other hand, longitudinal tensile forces, associated with low temperatures, in combination with breaking forces may break rail. Therefore, it is very important to work out thorough counter measures for those problems, specially in high speed rail which high safety is required. The exact evaluation of longitudinal force of rail has the key to the solution. The main aim of the present paper is to examine whether the longitudinal force of CWR's on Kyung-Bu-HSR satisfy the criteria to be fulfilled in the design of railway bridge. The analyses are carried out by using "CWRAP" program which was developed by our research group. The ballast resistance and breaking force effects on the longitudinal force of CWR are investigated.

• Electronics and Telecommunications Trends
• /
• v.32 no.6
• /
• pp.1-7
• /
• 2017

A metamaterial is a material engineered to have a property that does not exist in nature. A designable material property can be achieved by tailoring its structure, and thus a metamaterial is a novel ICT material and component technology that can break through the limitations of conventional technologies. Among the metamaterials available, a perfect metamaterial absorber is a technology that can nearly absorb light, sound waves, thermal waves, and electromagnetic waves with a simple structure, and has been of significant interest in energy, display, sensor, stealth, and military applications, with wavelengths from visible light to microwaves. In this article, we introduce a brief description of metamaterial absorber technology, the critical issues for its application, as well as ETRI's developed metamaterial absorber technology and its prospects for future use.

• The Bulletin of The Korean Astronomical Society
• /
• v.39 no.1
• /
• pp.51.2-51.2
• /
• 2014

CQUEAN(Camera for QUasars in EArly uNiverse) has been used at the 2.1 m Otto Struve Telescope of the McDonald Observatory since 2010. This camera is optimized at 0.7 - 1.1 um for the survey of Lyman break of high redshift (z > 5) quasars in the early universe. The current system has a filter wheel consist of seven (g', r', I', z', Y, Iz and Is) broad-band filters. We are upgrading this filter wheel to have 20 narrow band filters, with which we can take spectral energy distributions of targets. The new filter wheel consists of interchangeable cartridges for 50 mm square filters, a speed reducer unit, and a step motor. This new design of the large size filter wheel can be applied to other large format CCD cameras.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2004.11a
• /
• pp.102-107
• /
• 2004

New designed floating breakwater made of Polyethelener with considering the introduction of new material for being harmony with environment and stability of the floater is developed for a marine ranching. Model experiment in order to test its capability is performed for the regular and irregular waves in ocean engineering basin. Good capability to break the incident wave within the 6 second of period and 1 m of height is shown. Breaking efficiency for long period wave is not so good in regular and irregular wave. The results of this study will contribute to the design and construction of the floating breakwater.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.259-260
• /
• 2008

In this paper, we fabricated elastomer epoxy specimens by added liquid elastomer to improve the mechanical and electrical properties instead of previous high-voltage epoxy materials. As increased additive contents, glass transient temperature (Tg) was continually decreased in DSC (differential scanning calorimetry). Among specimens, 15 phr sample showed the mechanical and electrical properties similar of high-voltage epoxy in modulus, break-down and arc test. From the optimized condition of elastic epoxy, we confirmed a chance of application for high-voltage materials and power electrical instruments.