• Journal of the Korean Society for Heat Treatment
• /
• v.11 no.2
• /
• pp.140-149
• /
• 1998

The graphitization is affected by the addition of small amount of the elements, such as Si, Al, Ni, B, Cr and Mn etc. Boron is well known as the most effective element for the graphitization of cementite in high carbon steels. But a study on quantitative analysis of B effect on the graphitization is few reported. Therefore the effect of boron addition in Fe-0.65%C-1.0%Si-0.5%Mn steels on the graphitization is investigated quantitatively using hardness tester, optical microscope and scanning electron microscope, neutron induced microscopic radiography. The graphitization in high carbon steels is promoted with 0.003~0.005%B addition. But the graphitization in steels which has no boron takes long holding time at $680{\sim}720^{\circ}C$. The hardness of quenched steel containing 0.003%B is higher than that of 0.005%B added steel due to complete dissolution of fine graphites into the austenite. The 0.003%B added high carbon steel graphitized at $680^{\circ}C$ for 25hr is useful steel for the agricultural implements and automobile parts which needed a good formability and high hardness.

• Journal of Powder Materials
• /
• v.21 no.4
• /
• pp.266-270
• /
• 2014

Metal foams have a cellular structure consisting of a solid metal containing a large volume fraction of pores. In particular, open, penetrating pores are necessary for industrial applications such as in high temperature filters and as a support for catalysts. In this study, Fe foam with above 90% porosity and 2 millimeter pore size was successfully fabricated by a slurry coating process and the pore properties were characterized. The Fe and $Fe_2O_3$ powder mixing ratios were controlled to produce Fe foams with different pore size and porosity. First, the slurry was prepared by uniform mixing with powders, distilled water and polyvinyl alcohol(PVA). After slurry coating on the polyurethane(PU) foam, the sample was dried at $80^{\circ}C$. The PVA and PU foams were then removed by heating at $700^{\circ}C$ for 3 hours. The debinded samples were subsequently sintered at $1250^{\circ}C$ with a holding time of 3 hours under hydrogen atmosphere. The three dimensional geometries of the obtained Fe foams with an open cell structure were investigated using X-ray micro CT(computed tomography) as well as the pore morphology, size and phase. The coated amount of slurry on the PU foam were increased with $Fe_2O_3$ mixing powder ratio but the shrinkage and porosity of Fe foams were decreased with $Fe_2O_3$ mixing powder ratio.

• Management & Information Systems Review
• /
• v.1
• /
• pp.333-362
• /
• 1997

Since the profess of the reformation and opening Policy in 1978, China has been outstandingly developed its economy and increased the real scale of its economy 4 times as big as before, and is expected to rise as a superpower holding in check U.S.A even in economy as well as politics, military affairs and diplomacy in the 21st century. In this position, China has constantly tried to join WTO since 1986, as an effort to gain a status in the international society. It hsa been making various economic reformations to provoke a crustal movement in its own economy such as tariffs lowering measurement for the almost whole items, remove of restriction of import items, lowering the refunding rate of over deposit tax and annihilation of the special treatments for the foreign investment. In short, recently Chinese government is cutting down the special treatments for the foreign capital enterprises and changing the policy to the direction of gradually reinforcing the control, so it requires that our enterprises trying to advance and invest in China have to consider these carefully. Investment in China of our enterprises become serious since 1990 is focused on such labor intensive industries as textiles, sewing and shoes which lost the competitive power due to the wage increase. Particularly, Pusan economy having played the role of locomotive for Korean economy in the past developing period has been weakened in the competitiveness and not yet activated in 1990s. In terms of this, the enterprises engaged in such typical industries of Pusan as shoes, textiles and sewing have borne much fruit from the investment in China with abundant and cheap labors. However, from a few years the enterprises in Pusan invested in China due to the cheap labors and rich resources and invested in China have suffered much troubles and failures more and more resulted from the advancement without sufficient previous knowledge and information related to the investment including investment environment. Therefore, at the time of advancement in China, Korean enterprises should make their decision related to the investment, after taking these investment environment into account previously to a full extent and making an investment strategy.

• Journal of Digital Convergence
• /
• v.10 no.8
• /
• pp.239-247
• /
• 2012

This paper is related to an Object VR-based virtual textile wearing system carrying out textile texture mapping based on viewpoint vector estimation and intensity difference map. The proposed system is characterized as capable of virtually wearing a new textile pattern selected by the user to the clothing shape section segmented from multi-view 2D images of clothes model for Object VR(Object Virtual Reality), and three-dimensionally viewing its virtual wearing appearance at multi-view points of the object. Regardless of color or intensity of model clothes, the proposed system is possible to virtually change the textile pattern with holding the properties of the selected clothing shape section, and also to quickly and easily simulate, compare, and select multiple textile pattern combinations for individual styles or entire outfits. The proposed system can provide higher practicality and easy-to-use interface, as it makes real-time processing possible in various digital environment, and creates comparatively natural and realistic virtual wearing styles, and also makes semi-automatic processing possible to reduce the manual works.

• Carbon letters
• /
• v.22
• /
• pp.48-59
• /
• 2017

This study synthesized pure anatase carbon doped $TiO_2$ photocatalysts supported on a stainless steel mesh using a sol-gel solution of 8% polyacrylonitrile (PAN)/dimethylformamide (DMF)/$TiCl_4$. The influence of the pyrolysis temperature and holding time on the morphological characteristics, particle sizes and surface area of the prepared catalyst was investigated. The prepared catalysts were characterized by several analytical methods: high resolution scanning electron microscopy (HRSEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), and X-ray photoelectron spectroscopy (XPS). The XRD patterns showed that the supported $TiO_2$ nanocrystals are typically anatase, polycrystalline and body-centered tetragonal in structure. The EDS and XPS results complemented one another and confirmed the presence of carbon species in or on the $TiO_2$ layer, and the XPS data suggested the substitution of titanium in $TiO_2$ by carbon. Instead of using calcination, PAN pyrolysis was used to control the carbon content, and the mesoporosity was tailored by the applied temperature. The supported $TiO_2$ nanocrystals prepared by pyrolysis at 300, 350, and $400^{\circ}C$ for 3 h on a stainless steel mesh were actual supported carbon doped $TiO_2$ nanocrystals. Thus, $PAN/DMF/TiCl_4$ offers a facile, robust sol-gel related route for preparing supported carbon doped $TiO_2$ nanocomposites.

• Journal of Korean Medical classics
• /
• v.29 no.4
• /
• pp.105-125
• /
• 2016

Objectives : This study aims to investigate the background of, and theoretical system behind the Jinkuiyuhanjing that was edited and published at the same time as the Shanghanlun by the Jiaozhengyishuju (governmental publishing sector) of Northern Song. Methods : To determine the background against which Jinkuiyuhanjing was published, its position and meaning within the Medical Texts Editing Project of the Jiaozhengyishuju was firstly examined. For its theoretical background, the contents of Zhengzhizongli, which is considered to be an introduction to the Jinkuiyuhanjing was thoroughly analyzed. Moreover, to understand the unique philosophy of the Jinkuiyuhanjing, referneces were made to relevant contents in the 'Shinhyeong' chapter of the Donguibogam. Results : The findings of the study call for a re-evluation of the Jinkuiyuhanjing as holding a unique philosophical perspective and having an independent lineage instead of being a supplementary material to the Shanghanlun as it was once understood. Conclusions : The research of Zhangzhongjing's Classical Formulas(經方) revealed that the theoretical thinking and contents of Jinkuiyuhanjing hold much value and should be actively studied and applied. Furthermore, it lends important meaning in understanding the tradition of Korean Classical Formulas as represented in the Donguibogam.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.6
• /
• pp.629-641
• /
• 2016

This study analyzed the use of the phenomenological method proposed by Colaizzi (1978) in order to understand the meaning of block system class experiences in nursing students. Furthermore, this study provides primal data to improve curriculum efficiency. The data were collected from 18 participants who were students at a nursing university in the city of G from 20th of June to 10th of July 2015. This study investigated nursing student's block system class experience. The study results show six theme clusters consisting of 'Discomfort', 'Unsystematic study', 'Holding back an urge', 'Ever intensifying relationship', 'New discovery', and 'Chance for development', 17 themes, and 42 sub themes, which are included in those clusters in 58 configured meanings. This demonstrates that nursing students could reestablish their resolve for personal betterment and realize the importance of managing time by finishing the procedure with their best efforts although they suffer from physical and psychological inconvenience due to massive amounts of learning and assignment. These results indicate the need for development of stress management and an emotional support program based on the experience of nursing students.

• Journal of Periodontal and Implant Science
• /
• v.25 no.1
• /
• pp.67-75
• /
• 1995

The progress of periodontal disease and the wound healing process after treatment result in alveolar bone bone change. So, detection of it is very important in the diagnosis and the radiograph of periodontal disease. Various effects have been made to assess the subtle alveolar bone change and digital subtraction radiography (DSR) has been reported to be the best method in evaluating it qualitatively and quantitatively. The present study was performed to estimate the detectable alveolar bone change qualitatively with digital subtraction radiography. For the in vitro study, 10 intraoral standard radiographs were taken from porcine dry mandible which a rectangular cortical bone chip of 0.1mm to 1.0mm thickness with 0.1mm increment was attached on the buccal surface. The radiographs without and with bone plates were reviewed at the same time by 10 observers and requested to detect the presence of cortical bone plates. Digital Subtraction radiograph was reviewed subsequently by using the DSR system(digital converter-256 grey-levels,DT 2851,Data Translation Co., U.S.A;IBM 386 ; CCD camera, FOTOVIX, Tamrom Co., Japan). The detectable thickness of cortical bone plate was O.4mm on the intraoral radiograph and 0.2mm on the subtaction images. For the human study, radiographs were taken from patients by using intraoral film holding device and aluminum reference wedge before and 3 month after bone graft and 1 week after osteoplasty. The grey level change was estimated in the subtraction images and calculated to aluminum equivalent thickness. The grey level of the grafted site was higher that that of healthy controls. Average grey levels of change on healthy controls were O.48mm aluminum equivalent. However, the amount of changes in grafted sites were 1.87mm aluminum thickness equivalent and in the site of osteoplasty were -1.49mm aluminum thickness equivalent. In conclusion, digital subtraction radiography was more effective in detecting as subtle change of alveolar bone than intraoral standard radiography. With the aid of quantitative analysis of digital subtraction radiography, alveolar bone resorption of apposition can be estimated during diagnosis and treatment of periodontally diseased patients.

• The Korean Journal of Physiology and Pharmacology
• /
• v.1 no.6
• /
• pp.741-748
• /
• 1997

In the present study, we have investigated the effect of metabolic inhibition on the inward rectifier K current ($I_{K1}$). Using whole cell patch clamp technique we applied voltage ramp from +80 mV to -140 mV at a holding potential of -30 mV and recorded the whole cell current in single ventricular myocytes isolated from the rabbit heart. The current-voltage relationship showed N-shape (a large inward current and little outward current with a negative slope) which is a characteristic of $I_{K1}$. Application of 0.2 mM dinitrophenol (DNP, an uncoupler of oxidative phosphorylation as a tool for chemical hypoxia) to the bathing solution with the pipette solution containing 5 mM ATP, produced a gradual increase of outward current followed by a gradual decrease of inward current with little change in the reversal potential (-80 mV). The increase of outward current was reversed by glibenclamide ($10\;{\mu}M$), suggesting that it is caused by the activation of $K_{ATP}$. When DNP and glibenclamide were applied at the same time or glibenclamide was pretreated, DNP produced same degree of reduction in the magnitude of the inward current. These results show that metabolic inhibition induces not only the increase of $K_{ATP}$ channel but also the decrease of $I_{K1}$. Perfusing the cell with ATP-free pipette solution induced the changes very similar to those observed using DNP. Long exposure of DNP (30 min) or ATP-free pipette solution produced a marked decrease of both inward and outward current with a significant change in the reversal potential. Above results suggest that the decrease of $I_{K1}$ may contribute to the depolarisation of membrane potential during metabolic inhibition.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.43 no.7 s.349
• /
• pp.1-6
• /
• 2006

We show for the first time the optical properties of the selectively oxidized vertical cavity laser (VCL) - depleted optical thyristor (DOT), which has not only a low threshold current, but also a high sensitivity to the optical input light. In order to analyze their switching characteristics, nonlinear s-shaped current-voltage characteristics are calculated and the reverse full-depletion voltages (Vneg's) are obtained as function of semiconductor parameters by using a finite difference method (FDM). The selectively oxidized PnpN VCL-DOT clearly shows the nonlinear s-shaped current-voltage and lasing characteristics. A switching voltage of 5.24 V, a holding voltage of 1.50 V, a spectral response at 854.5 nm, and a very low threshold current of 0.65 mA is measured, making these devices attractive for optical processing applications.