• Journal of Korea Foundry Society
• /
• v.33 no.1
• /
• pp.32-40
• /
• 2013

• Journal of Mechanical Science and Technology
• /
• v.16 no.7
• /
• pp.902-910
• /
• 2002

Cast stainless steel may experience embrittlement when it is exposed approximately to 300$\^{C}$ for a long period. In the present investigation, the three classes of the thermally-aged CF8M specimen were prepared using an artificially-accelerated aging method. After the specimens were held for 300, 1800 and 3600hrs. at 430$\^{C}$, respectively, the specimens were quenched in water which is at room temperature. Load versus load line displacement curves and J-R curves were obtained using the unloading compliance method. talc values were obtained using the ASTM E813-87 and ASTM E 813-81 methods. In addition to these methods, talc values were obtained using the SZW (stretch zone width) method described in JSME S 001-1981. The results of the unloading compliance method are J$\_$Q/=543.9kJ/㎡ for virgin materials. The values of J$\_$IC/ for the degraded materials at 300, 1800 and 3600hrs. are obtained 369.25kJ/㎡, 311.02kJ/㎡, 276.7kJ/㎡, respectively. The results obtained by the SZW method are compared with those obtained by the unloading compliance method. Both results are quite similar. Through the elastic-plastic fracture toughness test, it is found that the value of loc is decreased with an increase of the aging time.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.10 s.181
• /
• pp.2405-2412
• /
• 2000

A cast stainless steel may experience an embrittlement when it is exposed to approximately 30$0^{\circ}C$ for long period. In the present investigation, The three classes of the thermally aged CF8M specimie n are prepared using an artificially accelerated aging method. Namely, after the specimen are held for 300, 1800 and 3600hrs. at 43$0^{\circ}C$ respectively, the specimens are quenched in water to room temperature. Load versus load line displacement curves and J-R curves are obtained using the unloading compliance method. $J_{IC}$ values are obtained following ASTM E 813-87 and ASTM E 813-81 methods. In addition to these methods, JIC values are obtained using SZW(stretch zone width) method described in JSME S 001-1981. The results of the unloading compliance method are $J_Q$=485.7 kJ/m$^2$ for virgin material, $J_{IC}$ of the degraded materials associated with 300, 1800 and 3600hrs are obtained 369.25 kJ/m$^2$, 311.02 kJ/m$^2$, 276.7 kJ/m$^2$, respectively. The results of SZW method are similar to those of the unloading compliance method. Through the elastic-plastic fracture toughness test, it is found that the value of $J_{IC}$ is decreased with increasing of the aging time. The results obtained through the investigation can provide reference data for a leak before break(LBB) of reactor coolant system of nuclear power plants.

• Journal of Korea Foundry Society
• /
• v.14 no.6
• /
• pp.530-540
• /
• 1994

Aluminium-silicon alloy(JIS AC8A) matrix composites reinforced with SiC particles were fabricated by spray-cast forming process, and the microstructure of powders and preforms produced were studied by using an optical and scanning electron microscopy. SiC particles were co-sprayed by mixed phase injection method during the spray casting process. Most of the composite powders formed by this mixed phase injection method exhibit morphology of particle-embedded type, and some exhibits the morphology of particle attached type due to additional attachment of the SiC particles on the surface of the powders in flight. The preforms deposited were resulted in dispersed type microstructure. The pre-solidified droplets and the deposited preform of SiC-reinforced aluminium alloy exhibit finer equiaxed grain size than that of unreinforced aluminium alloy. Eutectic silicons of granular type are crystallized at the corner of the aluminum grains in the preforms deposited, and some SiC particles seem to act as nucleation sites for primary/eutectic silicon during solidification. Such primary/eutectic silicons seem to retard grain growth during the continued spray casting process. It is envisaged from the microstructural observations for the deposited preform that the resultant distribution of SiC injected particles in the Al-Si microsturcture is affected by the amount of liquid phase in the top part of the preform and by the solidification rate of the preform deposited.

• Proceedings of the KIEE Conference
• /
• 2002.07b
• /
• pp.1126-1128
• /
• 2002

In proportion to the development of various cultural contents industry, although the lighting tools with advanced control system are needed, the fields of the lighting tools are not competitive in techniques because they are limited in small businesses and have been lost their markets to foreign companies in the high value added industry. Accordingly, the technique that is better than current lighting tools is needed urgently. So, for the new lighting tools, this paper presents a new dimming method using IGBT(Insulated Gate Bipolar Transistor) devices. There are three procedures in this study. For the first, the authors verify superiority of IGBT Dimmer with simulation using EMTDC in former step for development of IGBT dimmer. Secondly, the authors made IGBT dimmer directly with the basis of simulation results. For the last, the efficiency, the Total Harmonic Distortion(THD) current, temperature characteristic, noise characteristic, voltage drop, heat losses between the IGBT dimmer and the Thyristor dimmer that is being used popularly in the industries the stages, and the theaters were tested and compared..

• KIPS Transactions on Software and Data Engineering
• /
• v.4 no.1
• /
• pp.19-30
• /
• 2015

Smart TV manufacturers have constructed automatic Smart TV execution environment for reducing cost of Smart TV testing. However, the conventional test methods still require high cost because of manual test script written by testers. Test scripts manully written have less reusability, and then less reusable scripts cannot be used for new TV models. In this paper, we propose constructing reusable test models for Smart TV and present a model-based Smart TV test script generation method using the modes. And we apply the method to NetCast Smart TV to confirm the effectiveness of enhancing reusability.

• The Journal of Advanced Prosthodontics
• /
• v.9 no.1
• /
• pp.52-56
• /
• 2017

PURPOSE. Considering the importance of metal-ceramic bond, the present study aimed to compare the bond strength of ceramics to cobalt-chrome (Co-Cr) alloys made by casting and selective laser melting (SLM). MATERIALS AND METHODS. In this in-vitro experimental study, two sample groups were prepared, with one group comprising of 10 Co-Cr metal frameworks fabricated by SLM method and the other of 10 Co-Cr metal frameworks fabricated by lost wax cast method with the dimensions of $0.5{\times}3{\times}25\;mm$ (following ISO standard 9693). Porcelain with the thickness of 1.1 mm was applied on a $3{\times}8-mm$ central rectangular area of each sample. Afterwards, bond strengths of the samples were assessed with a Universal Testing Machine. Statistical analysis was performed with Kolmogorov-Smirnov test and T-test. RESULTS. Bond strength in the conventionally cast group equaled $74.94{\times}16.06\;MPa$, while in SLM group, it equaled $69.02{\times}5.77\;MPa$. The difference was not statistically significant ($P{\leq}.05$). CONCLUSION. The results indicated that the bond strengths between ceramic and Co-Cr alloys made by casting and SLM methods were not statistically different.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.29 no.3
• /
• pp.163-168
• /
• 2003

Three-dimensional solid model has not been widely used in surgical prediction of orthognathic surgery because frequent artifacts from occlusal restorations or prosthesis limited the usefulness of simulated surgery involving occlusion. We prepared three-dimensional(3D) solid model from CT data and integrated the 3D solid model with dental cast using a face-bow transfer technique combined with skeletal reference measurement and confirmation with cephalometric radiographs. With this simple and easy method, it was possible to predict bony interference between the proximal and distal segment of the mandible so that we can prevent condylar displacement after sagittal split ramus osteotomy of the mandible with prominent asymmetry. The method error was within 2mm and it seemed to be useful in preoperative planning for maxillofacial surgery with maxillo-mandibular occlusal change.

• Proceedings of the KOR-BRONCHOESO Conference
• /
• 1972.03a
• /
• pp.1.3-1
• /
• 1972

The are early diagnosis of acoustic neuroma is important for radical removal of it and for early radiologic diagnosis which was considered to be the most reliable method it is required to know the normal dimension of the internal auditory meatus. There are two methods for internal auditory meatal measurement; one is indirect, such as the conventional roentogenography, laminoraphy and cisternography and the other is direct using rubber cast method of Amjad, A.H. et. al. Authors measured the anatomical dimensions of Korean adult internal auditory meatus with regular rubberbase impression material.

• Journal of Computational Design and Engineering
• /
• v.2 no.2
• /
• pp.96-104
• /
• 2015

Aluminum die casting is an important manufacturing process for mechanical components. Die casting is known to be more accurate than other types of casting; however, post-machining is usually necessary to achieve the required accuracy. The goal of this investigation is to develop machining- free aluminum die casting. Improvement of the accuracy of planar and cylindrical parts is expected by correcting metal molds. In the proposed method, the shape of cast aluminum made with the initial metal molds is measured by 3D scanning. The 3D scan data includes information about deformations that occur during casting. Therefore, it is possible to estimate the deformation and correction amounts by comparing 3D scan data with product computer-aided design (CAD) data. We corrected planar and cylindrical parts of the CAD data for the mold. In addition, we corrected the planar part of the metal mold using the corrected mold data. The effectiveness of the proposed method is demonstrated by evaluating the accuracy improvement of the cast aluminum made with the corrected mold.