• The Journal of Natural Sciences
• /
• v.5 no.1
• /
• pp.77-86
• /
• 1992

By cation-exchange-reaction long-chain organic cationic tensides can be intercalated in the montmorillonite layer space, and thus intercalations-complexes of montmorillonite with different properties of materials can be obtained. Such intercalations-complexes are finding strong technical appliances in many areas and are also used very often as model-systems for studying behaviors of materials. Therefore in this research intercalations-complexes of montmorillonite with organic cationic tensides ad model-systems were synthesized and their behabiors under various different conditions were studied.

• Korean Journal of Materials Research
• /
• v.15 no.12
• /
• pp.829-832
• /
• 2005

Thermal analysis of new designed heat-sink models was carried out according to the natural ana the forced convection using computational fluid dynamics(CFD). Heat resistance of wave type, top vented wave type and plate type of heat sink was compared with each other As the direction of fin and air flow are vertical(z-axis), it is shown that radiant heat performance of all of heat sinks was superior than other experimental conditions. Especially, the heat resistance of top vented wave heat sink was $0.17^{\circ}C/W$(forced convection) and $0.48^{\circ}C/W$(natural convection). The radiant heat performance of heat sink was increased with increasing the height of fin and the width of fin pitch.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2002.03a
• /
• pp.343-346
• /
• 2002

The chemical compatibility of leachate with the two natural materials was analyzed by performing the hydraulic conductivity test. The selected liner materials were natural marine clay and weathered soil sampled from Kimpo wastefill and Daehwa Dong, Kyonggi Do, respectively. PARAFIX, which is mainly composed of paraffin, cement, stearic acid, PVA etc., was used as solidifying agent. The chemical solutions used in the test were 10% acetic acid, 10% methanol, and real leachate from Kimpo wastefill and the results of tests were compared with that of distilled water. The results of tests show that hydraulic conductivity of solidified clay was increased slightly with permeation of acetic acid, methanol and the increase of hydraulic conductivity was not shown with permeation of leachate, distilled water and in case of weathered soil. Based on the tests, it is ascertained that the tested liner materials can be stable with the solution of low concentration.

• Steel and Composite Structures
• /
• v.31 no.1
• /
• pp.43-51
• /
• 2019

This paper is concerned with the numerical calculation of mixed-mode stress intensity factors (SIFs) of 2-D isotropic functionally graded materials (FGMs) by the natural element method (more exactly, Petrov-Galerkin NEM). The spatial variation of elastic modulus in non-homogeneous FGMs is reflected into the modified interaction integral ${\tilde{M}}^{(1,2)}$. The local NEM grid near the crack tip is refined, and the directly approximated strain and stress fields by PG-NEM are enhanced and smoothened by the patch recovery technique. Two numerical examples with the exponentially varying elastic modulus are taken to illustrate the proposed method. The mixed-mode SIFs are parametrically computed with respect to the exponent index in the elastic modulus and external loading and the crack angle and compared with the other reported results. It has been justified from the numerical results that the present method successfully and accurately calculates the mixed-mode stress intensity factors of 2-D non-homogeneous functionally graded materials.

• 연구논문집
• /
• s.23
• /
• pp.121-126
• /
• 1993

In general, natural gas engine converted from gasoline engine has disadvantage of power decrease. In order to increase power output in natural gas engine, the improvement of in-cylinder flow motion has been believed as the most effective method. In this study, the geometry of combustion chamber in 4 valve DOHC natural gas engine is modified, and in-cylinder flow patterns are analyized. Also engine performance is evaluated according to the modification of in-cylinder flow motion.

• Bulletin of the Korean Chemical Society
• /
• v.29 no.3
• /
• pp.705-707
• /
• 2008

• Journal of the Korea Furniture Society
• /
• v.26 no.3
• /
• pp.207-221
• /
• 2015

Inlay is a high technique of inlaying patterns on the surface of crafts and widely used transcending time and place at various hand crafting area. Inscribed pattern technique using rare materials in the area have been used by the artisans of artistic flair and functionality and its value is also highly regarded from ancient to modern and inherits and is being developed today. Existing inlay technique, however, has not been spread out because it needs craftsman's skill based on the handcraft and inscribed materials are very rare to use. This paper aims to replace natural wood Sanggam materials for traditional furniture patterns such as Samho Jang, Ohho Jang, Seongtoenoe Moon, Gyeopgwinoe Moon and wood inlay text like Soo (Long life), Bok (Luck), Kang (Peace), Ryoung (Relaxed) and gammadion cross pattern. Gathered black, yellow and white color dyed wood using power tools can replace rare natural inlay materials through reliable and standardized supply. Dyed-gathered inlay materials can easily replace wood inlay materials, therefore, attempt to create an improved direction regarding materials and fabrication techniques in order to make traditional or contemporary artistic furniture to be produced.

• Journal of the Korean Institute of Gas
• /
• v.17 no.6
• /
• pp.20-26
• /
• 2013

In this study, based on a 12L class diesel engine, a natural gas-diesel dual fuel engine was developed by adding natural gas fuel supply system. For optimal control of dual fuel engine, a conventional diesel engine ECU and a dual fuel ECU were utilized. To convert the dual fuel engine, MPI natural gas injectors were installed on the new modified intake manifold adapter. As a results, the dual fuel engine showed same level of torque, power performance and exhaust gas emissions as those of a diesel base engine.. Furthermore, overall fuel replacement rate was 70~76 % and total fuel cost saving was 37~40%.

• Bulletin of the Korean Chemical Society
• /
• v.27 no.10
• /
• pp.1549-1552
• /
• 2006

We report a new series of blue dopants composed of both electron donating and electron accepting moieties in one molecule, based on nalidixic acid. The EL device derived from the dopant exhibits pure blue light emission (0.15, 0.14) The current efficiency is estimated to be 3.88 cd/A at 100 $cd/m^2$, which shows remarkable enhancement, compared to that of the host itself (2.5 cd/A at 100 $cd/m^2$) under the same conditions. These results demonstrate that the incorporation of a proper guest into the host in a guest-host doped system improves not only the purity of the fluorescent blue emission but also elevates its quantum efficiency, thus improving the OLED performance.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2004.08a
• /
• pp.1142-1146
• /
• 2004

The synthetic route and physical properties for three-ring derivatives, trans-2,3,2',3'-tetrafluoro-4-alkyl-4'-(4-alkyl-cyclohexyl)-biphenyl and 4-alkyl-cyclohexane carboxylic acid 2,3,2',3',4'-pentafluoro-biphenyl-4-yl ester are presented. They exhibit broad range nematic phases exceeding 30K and low viscosity of nematic liquid crystal mixtures containing these materials. Their viscosity is compared with that of homologues with a lateral isothiocyanate group and show large negative dielectric anisotropies. The threshold voltage $V_{th}$ was low enough to be operated at a driving voltage of 5V. Our novel LC compounds are suitable materials for the improvement of dielectric anisotropy of vertical align liquid crystal displays (VA-LDCs).