• Transactions of Materials Processing
• /
• v.20 no.3
• /
• pp.193-205
• /
• 2011

Because of its rustproof property, stainless steel is widely used in kitchen appliances, building materials, electronics, chemical plants and automobile exhausts. In addition, the utilization of stainless steel for fuel cell application is growing. As the demand for this material increases, it is necessary to study the basic properties of stainless steel such as corrosion resistance, heat transfer, formability, cutting or shearing ability and weldability. In this article, the mechanical properties, formability and press forming performance of stainless steel are reviewed. Since temperature and strain rate affect the press forming performance of STS304(austenitic) stainless steel, the influence of these parameters on the plastic behavior should be investigated. Moreover, measures for the prevention of ridging of STS430(ferritic) and delayed fracture of STS430, which respectively appear during and after press forming, should be considered. Recently, stainless steel sheets with a thickness lower than 0.2 mm have been widely used in applications for mobile phone, digital camera and fuel cell separator. Therefore, there is a growing interest of studying the grain size effect and plasticity at the crystal scale in order to understand the anisotropic behavior and micro forming ability of thin sheets. This review paper was written with the objective of helping engineers and researchers to understand the forming characteristics of stainless steel and to establish standards in plastic forming techniques.

• Journal of the Korean Magnetic Resonance Society
• /
• v.14 no.2
• /
• pp.134-143
• /
• 2010

We studied the hydrogen-bonded $TlH_2PO_4$ (TDP) ferroelectrics treated with the proton-beam bombardment. The TDP material was irradiated with 1-MeV proton beam at a dose of $10^{15}/cm^2$. In order to analyze the hydrogen environment in TDP, we carried out the $^1H$ high resolution nuclear magnetic resonance (NMR) - i.e., Combined Rotation And Multiple Pulse Spectroscopy (CRAMPS) measurement. The isotropic chemical shift of hydrogen indicates its displacive property is related to the $PO_4$ lattice deformation which occurs throughout the antiferroelectric-, the ferroelastic- and the paraelastic-phase transitions. The temperature dependence of $\sigma_{iso}$ reveals the electronic charge redistribution is induced by the proton-beam irradiation and the elastic property.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.23 no.2
• /
• pp.67-74
• /
• 2017

In this work, the effects of nano $TiO_2$ on functionality and stability of low density polyethylene (LDPE) composite films were investigated for food packaging application. LDPE-nano $TiO_2$ composite films were prepared with various $TiO_2$ contents (0, 0.5, 1.0, 3.0 and 5.0wt%) by melt-extrusion and their basic properties such as crystallinity, chemical bonds and surface morphology were examined by XRD, FTIR and SEM. Ultraviolet (UV) light barrier property of as-prepared LDPE-nano $TiO_2$ composite films was also studied and the presence of nano $TiO_2$ resulted in significant improvement of UV light barrier compared to the pure LDPE film. To evaluate influence of nano $TiO_2$ on LDPE properties required as packaging material, thermal, mechanical, gas barrier and optical properties of LDPE-nano $TiO_2$ composite films were characterized with various analytical techniques including TGA, UTM, OTR, WVTR and UV-vis spectroscopy. As a result, except optical property of LDPE, no significant effects were found in other properties. Opacity of pure LDPE was greatly increased with increasing concentration of nano $TiO_2$.

• Korea-Australia Rheology Journal
• /
• v.16 no.4
• /
• pp.175-182
• /
• 2004

Colloidal coating solution was prepared to enhance the hydrophilic property of the film surface. Water and ethanol were used as the dispersion media and (glycidoxypropyl) trimethoxysilane (GPS) as a binder in the colloidal silica coatings. Ethylene diamine was added to the colloidal silica solution as the curing agent. The colloidal silica solution was regarded as a hard-sphere suspension model with low volume fraction of the silica particles. Rheological properties of the silica suspensions modified with GPS have been investigated as a function of pH and concentration. The acidic solution showed high viscosity change by fast hydrolysis reaction and adsorption of the organic binders on the surface of silica particles. However, the hydrolysis was slow at the basic condition and the binders combined with themselves by condensation. The viscosity change was smallest at pH 7. The viscosity increased with the curing time after adding ethylenediamine, and the increase of viscosity at low pH was higher than that at high pH. The hydrophilic properties of the coating film were investigated by the contact angle of water and film surface. The smallest contact angle was shown under the strong acidic condition of pH 2.

• Composites Research
• /
• v.24 no.3
• /
• pp.6-11
• /
• 2011

This paper presents an estimating method for local property changes and failure prediction of composite materials experiencing large shear deformation during draping process. The bone plate for the metaphyseal femur fracture was chosen to apply the presented method because it has complex geometry. The local property changes due to macro-/microscopic deformations of fabric composites during draping process were evaluated by various tests and the result was applied to predict static/fatigue behaviors of the bone plate. This paper was expected to present useful information on the design of composite structures with complex geometry and their performance evaluation.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
• /
• 2003.10a
• /
• pp.226-229
• /
• 2003

Following the successful development of practical high temperature superconducting (HTS) wires, there has been renewed activity in the development of superconducting power equipments. HTS equipments must be operated in the coolant, such as liquid nitrogen (L$N_2$) or cooled by cooler, such as GM-cryocooler to maintain the temperature below critical temperature. In this paper, dielectric strength of some insulating materials, such as epoxy, teflon, and glass fiber reinforced plastic (GFRP) in L$N_2$was measured. Surface breakdown voltage of GFRP which is basic property in design of HTS solenoid coil was measured. Epoxy is a goof insulating material but it is fragile at cryogenic temperature. The multi-layer insulating method of current lead is suggested to compensate this fragile property. It consists of teflon tape layer and epoxy layer fixed with texture. Based on these measurements, the 6.6㎸ class HTS magnet for DC reactor type high-T$_{c}$ superconducting fault current limiter (SFCL) was successfully fabricated and tested.d.

• Journal of Fashion Business
• /
• v.18 no.3
• /
• pp.1-13
• /
• 2014

This study investigated the store switching behavior of fashion stores targeting college students. A random sample of college students completed a questionnaire that contained measurements of store property, relationship quality, switching intent of store, preference of on/offline store, purchase of brand/non-brand product and monthly clothing expenses. The factors extracted as switching behavior of on/offline fashion store are store property, relationship quality and switching intent of store. Dimensions of store switching behavior in online shopping mall is revealed to be composed of diversity/ easy to search, store reliability, home page layout, sales promotion, reliability, commitment and switching intent of store. Also those of offline store is revealed to be composed of store comfort/salespeople service, product diversity, store location, product price, reliability, commitment and switching intent of store. The significant differences were found between store switching behavior of college students by preference of on/offline store and purchase of national brand/non brand. It is expected that this results can be used as a basic material for further study and setting up the fashion retailing strategies in fashion store for selling non brand products.

• Journal of Engineering Education Research
• /
• v.24 no.3
• /
• pp.70-76
• /
• 2021

As intellectual property has become an important competitive element in the industry, government-led patent education is rapidly expanding. It is important to look at whether each patent education course is organically linked to each other under a life-long patent education system from elementary school to college. This study focused on the link between high school education and college education to analyze statistically how invention activities in high school affect patent education achievement at college. Statistical analysis of a survey of students taking a basic course of intellectual property revealed no statistically significant correlation between invention experience in high school and college students' patent class total score, contrary to popular perception. These results are believed to be due to the distribution of data on the number of invention contest participations or the number of invention class participations, which does not form a normal distribution and has a relatively large skewness. Rather, the attendance to the patent class showed a relatively distinct positive linear correlation with the patent class total score, indicating that the student's attitude in class was important for the patent education achievement.

• Journal of Ocean Engineering and Technology
• /
• v.20 no.5 s.72
• /
• pp.42-48
• /
• 2006

This paper shows theresults of centrifuge model experiments to investigate the behavior of a replacement method in dredged and reclaimed ground. For this experimental work, centrifuge model tests were carried out to investigate the behavior of a replacement method in soft clay ground. Basic soil property tests were performed to find the mechanical properties of clay soil sampled from the southern coast of Korea, which was used for the ground material in the centrifuge model tests. The reconstituted clay ground of the model was prepared by applying reconsolidntion pressure in a 1 g condition with a specially built model container. Centrifuge model tests were carried out under the artificially accelerated gravitational level of 50 g. Replacement material of lead with a certain degree of angularity was used and placed until the settlement of the replacement material embankment reached a state of equilibrium. Vertical displacement of the replacement material was monitored during tests. The depth and shape of the replacement, especially the slope of the penetrated material and the water content of the clay ground were measured after finishing tests. Model tests for investigating the stability of an embankment after backfilling were also performed to simulate the behavior of a dike treated with replacement and backfilled with sandy material. As a result of the centrifuge model test, the behavior of the replacement, the mechanism of the replacement material being penetrated into clay ground, and the depth of the replacement were evaluated.

• Korean Institute of Interior Design Journal
• /
• v.22 no.3
• /
• pp.108-116
• /
• 2013

This study has the purpose to review the way of experience element and property of space design appearing in vocational experience space and accumulate basic study material for children's vocational experience space and build systematic and specialized modules. Analysing the marketing elements of experience space through pilot research to arrange frame of analysis, and in a determined range, experimental marketing's property appearing in children's vocational experience center is analysed. This researcher analysed experimental displaying space's function of recognition, emotional, behavior, sense marketing and experimental marketing induced from pilot research on space design expressive elements of experimental marketing when it is applied to spaces through the frame of analysis with the combination of total 8 kind's experience display space function such as investigative, conceptional, aesthetic, entertaining, logical, relative, participating, and comprehensive experience based on 5 vocational experience spaces located in Seoul and Gyeonggi, opened after 2010, being operated at present with more than 500 pyeong (about 1,650 square meter) and targeted for children, after this researcher visited the site directly to make check list with the frame of analysis together with the staff and administrator in charge of vocational experience education. As a conclusion, vocational experience center is a space of edutainment helping children experience various profession more easily to find their interest and to bring up their dream. By analysing current vocational experience center through the element called experimental marketing, current status of vocational experience center could be known. the experience itself in vocational experience center becomes a merchandise. Instead of mere experience, so as to get professional experience and new information, new experiences should be provided by incessant variation and development. This study is to build basic research data for children's vocational experience space, however not only drawing specialty of vocational experience center through the connection of enterprises based on the contents arranged above but also systematic and specialized modules are expected to be built in next researches.