• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.12
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• pp.1421-1426
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• 2014

To improve the inherent safety of the sodium-cooled fast reactor (SFR), the supercritical $CO_2$ ($S-CO_2$) Brayton cycle is being considered as an alternative power conversion system to steam the Rankine cycle. In the $S-CO_2$ system, a PCHE (printed circuit heat exchanger) is being considered. In this type of heat exchangers, diffusion bonding is used for joining the thin plates. In this study, the diffusion bonding characteristics of various austenitic alloys were evaluated. The tensile properties were measured at temperatures starting from the room temperature up to $650^{\circ}C$. For the 316H and 347H types of stainless steel, the tensile ductility was well maintained up to $550^{\circ}C$. However, the Incoloy 800HT showed lower strength and ductility at all temperatures. The microstructure near the bond line was examined to understand the reason for the loss of ductility at high temperatures.

• Journal of the Korean Society for Railway
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• v.13 no.2
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• pp.131-138
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• 2010

Recently, extruded aluminium-alloy panels have been used in the car bodies in order to meet the needs for the speed-up and light-weight of the railway vehicles. Most of the car bodies were jointed by arc weldings, like GMAW (GasMetal Arc Welding) and GTAW (Gas Tungsten Arc Welding), but these weldings became fairly worse the mechanical properties of the junction than the base metal. Nowadays, FSW (Friction Stir Welding), which is superior to the arc weldings, has been applied in the railway vehicles. In this study, the mechanical properties of the joints in both FSW and GMAW for A6005 extruded aluminium-alloy sheets have discussed. In addition, the relationships between the welding conditions and the mechanical properties for the joint of FSW have analyzed through the sensitivity analysis. It can be concluded that the mechanical properties for the joint of FSW are better than those of GMAW and the welding speed is the most sensible welding condition in the process of FSW.

• Composites Research
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• v.22 no.2
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• pp.1-6
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• 2009

The mechanical characteristics of gamma-ray irradiated UHMWPE specimens were investigated under various heat treatment conditions. The heat treatment was performed in the range of annealing and remelting temperatures. The annealing treatment below the temperature of $130^{\circ}C$ hardly induced changes in the tensile strength, the strain at the failure and the hardness. However the remelting treatment above $140^{\circ}C$ deteriorated those mechanical properties. It was shown in an FTIR analysis that the annealing treatment caused some oxidation of free radicals created by the pretreatment of the irradiation. These quantitative data represented by the behavior of mechanical properties might be used as basic informations for the design and analysis of various artificial joints.

• Membrane Journal
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• v.28 no.2
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• pp.83-89
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• 2018

Hydrophobic porous PVDF hollow fiber membranes for Membrane Distillation (MD) were fabricated by a combination of thermally induced phase separation (TIPS) and stretching. The purpose of this study is to investigate the shape and operating conditions of the module and the effect of piping size on parallel connection. In the optimization experiment of the vacuum membrane distillation module, the flux decreased as the packing density and length of the membrane in the module increased. When the module was connected vertically, it was confirmed that the nearest to the inlet of the vacuum port was the highest flux. In selecting the size of the header pipe of the module, it was confirmed that the maximum flux is shown when the inner diameter area of the hollow fiber membrane and the inner diameter area of the header pipe are the same. Also, it is necessary to find the optimal linear velocity because the higher the linear velocity in the module, the higher the flux, but the pressure acting on the module also increases proportionally.

• Conservation Science in Museum
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• v.16
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• pp.96-113
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• 2015

High-barrier films are used to store cultural heritage objects in a safe environment sealed from oxygen and moisture. One of the high-barrier films use populary E manufactured by Japanese company M from the 1990's. However, this product has stayed in wide use, due to dearth of research on related subjects - including studies comparing it with other similar products-, in spite of the fact that high price information about its characteristics and environmental conditions is largely lacking. This study examines the characteristics of a number of high-barrier films with the goal to establish environmental standards for safer conservation of cultural heritage objects. E by the Japanese manufacturer M is compared with four other films; an electronics packaging films by a Korean firm, a film specially produced for the purposes of experiment in this study and a zipper bag-type film. Experiments were performed to compare the properties and gas blocking ability of the films by looking at their cross-section and measuring the thickness, tensile strength, elongation, absorbance of UV and visible light, yellowing and the permeability for oxygen and vapor. Based on these experiments, there are observed changes under different environmental conditions and depending on the length of use through temparature and humidification reproucing test. The results showed that while the high-barrier film by the Korean manufacturer was suitable for use as a packaging material for cultural heritage objects, the zipper bag-type film (P) was ill-adapted for this purpose. Based on the experiments reproducing the real-world environment, the length of useful life was also determined for each.

• The Journal of Korean Philosophical History
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• no.31
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• pp.53-86
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• 2011

Taoism exercised its influence and has made much progress apparently under the aegis of the Tang dynasty. But since the external alchemy, a traditional way of eternal life that they have pursued, met the limitation, they were placed in a situation where they needed to seek a new discipline. From this period to the early North Song dynasty, three religions have established the unique theoretical systems of their own theory of ascetic practices. They showed their own unique formats as follows. Neo-Confucianism established the theory of moral training, Buddhism did the theory of ascetic practices and Taoism had theory of discipline. By this time, a person who claimed the Intermixture of Three Religions composed the new system of theory of ascetic practice by taking advantage of other religions and putting them into his own view. Chen tuan established the theory of internal alchemy of Taoism and was the most influential figure in the world of thought since North Song dynasty. He clearly declared that he accepted the merits of other religions in his theory. He added I Ching of Confucianism in I Ching of secret of Taoism to stop the logical gaps during the process of disciplines in Taoism and took ascetic practices on mind of Buddhism into his system while he sought a way to integrate the dual structure of body and mind. The theory of Chen tuan's internal alchemy was training schema with stages of 'YeonJeongHwaGi', 'YeonGiHwaSin', and 'YeonSinHwanHeo' based on the concepts of vital, energy and spirit. The internal alchemy practice that Chen tuan was saying started from the practice of Zen to keep the mind calm with the basis of fundamental principles of interpretation of book of change according to Taoism. When a person reached the state to be in concert with all changes at the end of the silence and be full of wisdoms, he finally returned to the state of BokGwiMuGeuk by taking the flow of subtle mind and transforming it into energy. He expressed this process by drawing 'MuGeukDo'. Oriental philosophy categorized human into 'phenomenal existence' and 'original existence'. The logic of theory of ascetic practice has been established from these 'category of existence'. It would be determined whether it will return to 'original existence' or be stepped up from 'phenomenal existence' according to how the concept of 'self' or 'I' was made. Chen tuan who established the theory of internal alchemy in Taoism has established the unique theory of internal alchemy discipline and system of intermixture of three religions in this aspect. Today is called 'era of self-loss' or 'era of incurable diseases' caused by environmental pollution. It's still meaningful to review the theory of discipline of Chen tuan's connecting the body and the soul to heal the self, and keep life healthy and pursue the new way of discipline based on it.