• Journal of Powder Materials
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• v.13 no.6 s.59
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• pp.421-426
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• 2006

The microstructural and mechanical properties of Al-Si alloyed powder, prepared by gas atomization fallowed by hot extrusion, were studied by optical and scanning electron microscopies, hardness and wear testing. The gas atomized Al-Si alloy powder exhibited uniformly dispersed Si particles with particle size ranging from 5 to $8{\mu}m$. The hot extruded Al-Si alloy shows the average Si particle size of less than $1{\mu}m$. After heat-treatment, the average particle size was increased from 2 to $5{\mu}m$. Also, mechanical properties of extruded Al-Si alloy powder were analyzed before and after heat-treatment. As expected from the microstructural analysis, the heat-treated samples resulted in a decrease in the hardness and wear resistance due to Si particle growth. The friction coefficient of heat-treated Al-Si alloyed powder showed higher value tough all sliding speed. This behavior would be due to abrasive wear mechanism. As sliding speed increases, friction coefficient and depth and width of wear track increase. No significant changes occurred in the wear track shape with increased sliding speed.

• Journal of Powder Materials
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• v.24 no.6
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• pp.472-476
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• 2017

Porous W-10 wt% Ti alloys are prepared by freeze-drying a $WO_3-TiH_2$/camphene slurry, using a sintering process. X-ray diffraction analysis of the heat-treated powder in an argon atmosphere shows the $WO_3$ peak of the starting powder and reaction-phase peaks such as $WO_{2.9}$, $WO_2$, and $TiO_2$ peaks. In contrast, a powder mixture heated in a hydrogen atmosphere is composed of the W and TiW phases. The formation of reaction phases that are dependent on the atmosphere is explained by a thermodynamic consideration of the reduction behavior of $WO_3$ and the dehydrogenation reaction of $TiH_2$. To fabricate a porous W-Ti alloy, the camphene slurry is frozen at $-30^{\circ}C$, and pores are generated in the frozen specimens by the sublimation of camphene while drying in air. The green body is hydrogen-reduced and sintered at $1000^{\circ}C$ for 1 h. The sintered sample prepared by freeze-drying the camphene slurry shows large and aligned parallel pores in the camphene growth direction, and small pores in the internal walls of the large pores. The strut between large pores consists of very fine particles with partial necking between them.

• Korean System Dynamics Review
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• v.2 no.2
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• pp.119-134
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• 2001

Since 1998, government-led Korean venture business boom now proceeds into the stage of market-oriented venture business growth. At such a moment, this research is to clarify the relations between the success factors of Korean venture businesses, based on domestic and foreign documentary surveys and inquiry surveys over domestic venture businesses. This research starts from the necessity to overcome the limits of the existing researches by uni-dimensional probing research into success factors of Korean venture businesses and to manifest the multi-dimensional relations between the success factors from the various viewpoints. And this research adopts System-Dynamics methodology to manifest and utilize relations among those factors, avoiding the existing metrical approaches. This research can be called a new approach to the current ecosystems of Korean venture in which whether venture businesses success in Korea is considered to depend on the list on the stock market. For this, this research implemented verification analysis through the simulations of each factor at various levels to build causality map which clarifies the causality of success factors of venture businesses through the System-Dynamics methodology and to utilize it as a way of supporting tool for decision-making of venture businesses. This research will be able to suggest the reactions depending on various internal and external situations. This research tried to manifest the causality map of each factor on the basis of inquiry surveys and documentary surveys to verify feedback among each factor by the SD methodology. This research will be a basis bolster up the still fragile substructure of venture businesses through an efficient analysis framework using the verification of SD methodology and resulting outcomes from this research.

• Archives of design research
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• v.9
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• pp.301-320
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• 1994

Filmff.V. is one of the most poweful media in the modern society. Its influnces on economics, culture, and social behavior are being extened more and more. By the growth of mutimedia market and existing film/T.V. market which are nurtured by the modern technology, filmff.V. culture became a giant influencial element. Filmff.V. culture in Korea did not settle down in right position, because of the uncontrolled implant and imitation of foreign film/T.V. culture under the short time of developing our own film/T.V. culture to support exploding technical aspects. A systematic filmff.V. education and financial investment are needed urgently to produce our own creative film/T.V. programs, and review on our filmff.V. culture and educational system are needed also to make a right understanding of filmff.V. media. In this proposal, I discuss the differences of educational system and curriculum between Korean filmff.V. educational institute and foreign countries'. Through this discussion, I sample a futuce oriented filmff.V. educational system and curriculum.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.5
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• pp.53-64
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• 2012

Deep and narrow welds can be produced by laser welding at high welding speeds with a narrow heat-affected zone (HAZ) and little distortion of the workpiece. This study aims to evaluate the usefulness of laser welding at automobile component manufacture. Microstructure observation, hardness test, tensile test and fatigue life test are performed by using the fiber laser welded SPFC590 steel sheets which is used widely in the manufacture of automotive seat frame. Three kinds of specimens are only a SPFC590 steel plate, quasi-butt joint plate and lap joint plate by laser welding. The following results that will be helpful to understand the static strength, fatigue crack initiation and growth mechanism were obtained. (1) The tensile strength of quasi butt joint specimens nearly equal to base metal specimens, but lap joint specimens fractured in shear area of weld metal. (2) The fatigue strength of quasi-butt joint specimen was approximately 8 percent lower than that of the base metal specimens. Furthermore, the lap joint specimens were less than 86 percent of the base metal specimens. (3) The lap joint fatigue specimens fractured at shear area in high level stress amplitude, while fractured at normal area in low level stress amplitude. From these results, the applicability of the laser welding to the automobile component is discussed.

• Journal of the Korea Furniture Society
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• v.27 no.2
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• pp.111-121
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• 2016

In the structure of modern houses, a living room is the space most frequently used by family members. In a living room, they rest, talk together, watch TV, study, read books and enjoy hobbies. A living room is furnished with a TV cabinet, a storage closet, a sofa, a bookshelf, a desk and etc. depending on the purposes of activities in it, which can be different in each house. Furniture is the required tool for indoor architectural space and humans to lead a life. In most families, a man and a woman marry each other and become man and wife, go through the honeymoon phase, give birth to one or two children and become a family with three or four members. According to the children's growth cycle from birth to infancy, early childhood, childhood, adolescence, youth and adulthood, furniture layout and kinds of furniture in a living room change. Depending on the family life cycle, most parents of young children try to help their children to form good habits of reading books and studying for their future. As for the environmental elements interrupting reading and studying, watching TV and using smart phones excessively are being regarded as problems. As the number of two-income families is increasing in this era when many women are participating in the social activities with the government's encouragement, children are having more time.

• Korean Journal of Veterinary Service
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• v.41 no.1
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• pp.57-61
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• 2018

Canine peripheral nerve sheath tumors (PNSTs) are spindle cell tumors that arise from Schwann cells, perineural cells, fibroblasts or all of them. Based on the morphology and biologic behavior, PNSTs are divided into benign PNST (BPNST) and malignant PNST (MPNST) forms. The aim of this study is to diagnose the two cases of neoplastic tissue samples with features of PNSTs by the histopathology and immunohistochemistry. The study was performed using two specimens from small animal clinic. The first case, A was a mass, 3~4 cm in diameter, extruded from vaginal mucosa of 10-year-old spayed female mixed-breed dog. And the second case, B was a subcutaneous mass, 1.5 cm in diameter, which is originated from right hind leg of 9-year-old castrated male mixed-breed dog. Two cases were stained with hematoxylin and eosin (H&E) for histopathological examination. And also immunohistochemistry (IHC) was performed by the avidin-biotin peroxidase complex (ABC) method with antibodies specific for the following proteins: S-100 protein, smooth muscle actin (SMA) and epidermal growth factor receptor (EGFR). In results, Antoni B schwannoma pattern characterized by pleomorphic, round and fusiform polygonal cells was seen in A. In B, Antoni A pattern, densely packed spindle cells arranged in interlacing bundles was seen in addition to Antoni B pattern. In IHC, cytoplasms of neoplastic cells were diffusely labeled for S-100 expression in A and B. For SMA, both A and B show negative expression. And for EGFR, A shows negative expression but B shows partially positive expression in areas of Antoni B schwannoma pattern. The histopathologic features of two cases coupled with the S-100 immunoreactivity led to a diagnosis of PNST. For SMA, both A and B show negative expression. The diagnosis of A will be a BPNST with the negative result and B will be a MPNST with the positive result for EGFR.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.7
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• pp.621-627
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• 2017

The understanding of the mechanical properties of amyloid fibers, which induce various neurodegenerative diseases, is directly related to the amyloid growth mechanism. Diverse studies have been performed on amyloid fibers from the viewpoint of disease epidemiology. Recently, attempts have been made to use amyloid fibers as new materials because of their notable mechanical properties and self-aggregation abilities. In this study, the mechanical properties of transthyretin (TTR105-115), which induces cardiovascular disease, were evaluated using a molecular dynamics (MD) simulation. In particular, the effect of the end-terminal capping on the structural stability of TTR105-115 was evaluated. The mechanical behavior and properties of TTR105-115 were measured by steered molecular dynamics (SMD). We clarified the factors affecting the mechanical properties of these materials and suggested the possibility of utilizing them as nature inspired materials.

• Health Policy and Management
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• v.8 no.1
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• pp.232-265
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• 1998

Taiwan has experienced rapid economic growth during the past two decades. As a result, the demand for health care in Taiwan has increased rapidly. To meet the rising demand, Taiwan implemented a National Health Insurance (NHI) program on March 1, 1995. This program now covers more than 96 percent of Taiwan's citizens. Implementation of the NHI in 1995 represents fulfillment of a primary social and health policy goals of Taiwan. The goals of the NHI program is to eliminate financial barriers of health care for the citizens, to improve the quality of care. To achieve these goals, the NHI was designed on the following principles: 1. All Taiwan citizens are compul내교 joined the NHI program by law; 2. The NHI program provides comprehensive services; 3. The NHI is run by one single govt' subsidy; 5. The NHI adopt fee-for-services scheme to pay medical expenses and copayment to avoid abouse of medical services. However, the scheme did not bring in the efficient use of health care C. National Health Council, 1986 NARC, Aging in Japan, International Publication Series 1991;2 Kahana EF. Kiyak HA. Attitude and behavior of staff in facilities for the aged, 1984 Naoki I, John CC. Health polic report japan's medical care system, New England Joumal of Medicine 1995; 333(19) National Economic Research Associates, The Health CAre System in Japan, NERA, 1993. National Federation of health Insurance Societies (KEMPOREM), Health Insurance and Health Insurance Societies in Japan, 1995. Owe Ahlund, Aging and housing in sweden, Paper presented at the International Symposium, Long term Care Facility, 1993. Statisitics Jahrbuch, Statistisches Bundesamt, 1992. Stein S. Linn, MIW. and Stein EM. Patient's anticipation of stress in nursing home care, 1985. U. S. Senate Special Committee on Aging, A Report of the special Committee on Aging, Washing D. C, 1992. U.S. Bureau of the Census, 1994.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.6
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• pp.937-946
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• 1986

In this paper, the plane stress fracture toughness of low carbon steel with 3mm thickness is investigated for various specimen widths and crack ratios using the J integral. The experiments is carried out for the compact tension(CT) specimen on an Instron machine. For materials that may be approximated by the Ramberg and Osgood stress strain law, the relevant crack parameter like the J integral and load line displacement are approximately normalized. Crack driving forces in terms of J integral is computed using the above estimation scheme. Abtained results are summarized as follows. (1) The plane stress fracture toughness, J$_{c}$, is almost constant in the range 50-70mm of width. Hence J$_{c}$ can be obtained by using smaller specimen than ASTM standard. (2) Yoon's and Simpson's formular which considers crack growth in obtaining J integral show more consevative J than Rice's and Merkle's (3) J$_{c}$ is almost constant in the range 0.499-0.701 crack ratios tested. J$_{c}$ obtained by using Kumar's formular is 28.14kgf/mm for base metal specimen and 32.51kgf/mm for annealed. (4) Comparison of the prediction with actual experimental measurements by Yoon's formular show good agreement for several different-size specimens.