• Title/Summary/Keyword: mechanical life

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Application of Ultrasonic Nano Crystal Surface Modification into Nitinol Stent Wire to Improve Mechanical Characteristics (나이티놀 스텐트 와이어의 기계적 특성 향상을 위한 초음파 나노표면 개질 처리에 대한 연구)

  • Kim, Sang-Ho;Suh, Tae-Suk;Lee, Chang-Soon;Park, In-Gyu;Cho, In-Sik;Pyoun, Young-Shik;Kim, Seong-Hyeon
    • Progress in Medical Physics
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    • v.20 no.2
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    • pp.80-87
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    • 2009
  • Phase transformation, superelastic characteristics and variation of surface residual stress were studied for Nitinol shape memory alloy through application of UNSM technology, and life extension methods of stent were also studied by using elastic resilience and corrosion resistance. Nitinol wire of ${\phi}1.778$ mm showed similar surface roughness before and after UNSM treatment, but drawing traces and micro defects were all removed by UNSM treatment. It also changed the surface residual stress from tensile to compressive values, and XRD result showed less intensive austenite peak and clear martensite and additional R-phase peaks after UNSM treatment. Fatigue resistance could be greatly improved through removal of surface defects and rearrangement of surface residual stress from tensile to compressive state, and development of surface modification system to improve not only bio-compatability but also resistance to corrosion and wear will make it possible to develop vascular stent which can be used for circulating system diseases which run first cause of death of recent Koreans.

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A Study on a New Working-system of Mechanical Land Clearing and Development of Fertle Soil. (기계개간의 새로운 작업체계와 숙지화 촉진에 관한 연구)

  • Hwang, Eun
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.13 no.1
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    • pp.2162-2176
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    • 1971
  • From the ancient times our forefathers settled down in this peninsular and cultivated the hills and waste-lands into fields. Instead of fertilizing the lands they moved to find other fertile lands and lived a feudal life of agriculture and various machines played a main role in the land reclamation. The best method of land clearing, the time and efficiency in the operation and the effect of growing crops should sysematically analized prior to the time of 3rd Five-year Economic Development(1972-1976) in order to cultivated 210,000 ha of waste-land or the modernization of our country. The present study was investigated to find out a new working-system of mechanical land clearing and development of fertile soil. The results are as follows: 1) The land reclamation in natural slope is much more encourageable in land clearing and farming when the slope is below ten grades than bench terrace. 2) Weeds were mixed with soil in the land clearing work in order to supply organic materials and to make soil swollen instead of burning of just removing. 3) The equipments such as bulldozers, harrows, power tillers and so on should be prepared in order to do a systematic work in the land clearing. 4) The work of pulling-up roots is dependent upon the forms of roots spreading under the ground. The work of the pulling-up the straight roots was most difficult. 5) The land clearing work of the wrinkled style blocks was easy in pulling up roots and in the time of first plowing. The harrowing work could also be simply done. 6) The amount of soil carried was $240m^3/10a$, 15.6% increased amount from the standard block, while the required time of clearing work was 2 hours 15 minutes 45 seconds/10a, the one third of time required for the standard block. 7) The time disc harrowing work increased 50%, or 15 minutes/10a compared to the harrowing work required in the cultivated soil. 8) The time of rotary tilling increased 2.4 times or 1 hour 47 minutes 43 seconds/10a compared to the time required in the cultivated soil. 9) The reclamed land should be fertilized according to the soil quality, especially added fertilizer should be more than 1,200kg/10a, limes 20kg/10a. In order to produce added fertilizer grass fields should be needed. 10) The experiment of pasture growing is now progressing and therefore the effect of land clearing and the degree of developed soil will be investigated before long.

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Physical Properties and Detachment Characteristics of Persimmon Fruit (감 과실(果實)의 물리성(物理性)및 이탈특성(離脫特性))

  • Kim, Tae Han
    • Current Research on Agriculture and Life Sciences
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    • v.3
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    • pp.62-69
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    • 1985
  • In order to develop the mechanical fruit harvest system the detachment force, type and torque investigated and analyse as several loading modes were applied on the fruit-stem of the persimmon fruit. A proving ring with strain gauges was used for the experiment. The following conclusions were drawn from the results : The mode of withdrawl of the stem from the calyx appeared highly as the persimmon fruit matured. The mode of failure at the junction of the stem and calyx which was desirable mode for mechanical fruit harvest increased as the angular displacement of the fruit with respect to the stem axis increased from zero to ninety degrees. However the mode of failure of the fruiting branch decreased for the same degree of angle pull as above. The range of detachment force of the persimmon fruit was from 13 to 5 kg. The detachment force decreased from 47 to 8 % as the fruit matured. Also, the force decreased from 31 to 24 % for the same maturity levels as the angular displacement of the fruit with respect to the stem axis increased from zero to ninety degrees. The range of detachment force to weight ratio(F/W) of the fruit was from 130 to 54 approximately. The detachment force to weight ratio (F/W) decreased from 36 to 8 % as the fruit matured. Also, the ratio (F/W) decreased from 49 to 33 % for the same maturity levels as the same degree of angle pull as above. In order to remove fruit from tree the desirable force applied to the stem is approximately from 1,280 to 530 kg. Also, the desirable torque to remove the fruits was approximately from 1.1 to $0.5kg{\cdot}cm$.

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Stellite bearings for liquid Zn-/Al-Systems with advanced chemical and physical properties by Mechanical Alloying and Standard-PM-Route

  • Zoz, H.;Benz, H.U.;Huettebraeucker, K.;Furken, L.;Ren, H.;Reichardt, R.
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2000.04a
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    • pp.9-10
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    • 2000
  • An important business-field of world-wide steel-industry is the coating of thin metal-sheets with zinc, zinc-aluminum and aluminum based materials. These products mostly go into automotive industry. in particular for the car-body. into building and construction industry as well as household appliances. Due to mass-production, the processing is done in large continuously operating plants where the mostly cold-rolled metal-strip as the substrate is handled in coils up to 40 tons unwind before and rolled up again after passing the processing plant which includes cleaning, annealing, hot-dip galvanizing / aluminizing and chemical treatment. In the liquid Zn, Zn-AI, AI-Zn and AI-Si bathes a combined action of corrosion and wear under high temperature and high stress onto the transfer components (rolls) accounts for major economic losses. Most critical here are the bearing systems of these rolls operating in the liquid system. Rolls in liquid system can not be avoided as they are needed to transfer the steel-strip into and out of the crucible. Since several years, ceramic roller bearings are tested here [1.2], however, in particular due to uncontrollable Slag-impurities within the hot bath [3], slide bearings are still expected to be of a higher potential [4]. The today's state of the art is the application of slide bearings based on Stellite\ulcorneragainst Stellite which is in general a 50-60 wt% Co-matrix with incorporated Cr- and W-carbides and other composites. Indeed Stellite is used as the bearing-material as of it's chemical properties (does not go into solution), the physical properties in particular with poor lubricating properties are not satisfying at all. To increase the Sliding behavior in the bearing system, about 0.15-0.2 wt% of lead has been added into the hot-bath in the past. Due to environmental regulations. this had to be reduced dramatically_ This together with the heavily increasing production rates expressed by increased velocity of the substrate-steel-band up to 200 m/min and increased tractate power up to 10 tons in modern plants. leads to life times of the bearings of a few up to several days only. To improve this situation. the Mechanical Alloying (MA) TeChnique [5.6.7.8] is used to prOduce advanced Stellite-based bearing materials. A lubricating phase is introduced into Stellite-powder-material by MA, the composite-powder-particles are coated by High Energy Milling (HEM) in order to produce bearing-bushes of approximately 12 kg by Sintering, Liquid Phase Sintering (LPS) and Hot Isostatic Pressing (HIP). The chemical and physical behavior of samples as well as the bearing systems in the hot galvanizing / aluminizing plant are discussed. DependenCies like lubricant material and composite, LPS-binder and composite, particle shape and PM-route with respect to achievable density. (temperature--) shock-reSistibility and corrosive-wear behavior will be described. The materials are characterized by particle size analysis (laser diffraction), scanning electron microscopy and X-ray diffraction. corrosive-wear behavior is determined using a special cylinder-in-bush apparatus (CIBA) as well as field-test in real production condition. Part I of this work describes the initial testing phase where different sample materials are produced, characterized, consolidated and tested in the CIBA under a common AI-Zn-system. The results are discussed and the material-system for the large components to be produced for the field test in real production condition is decided. Outlook: Part II of this work will describe the field test in a hot-dip-galvanizing/aluminizing plant of the mechanically alloyed bearing bushes under aluminum-rich liquid metal. Alter testing, the bushes will be characterized and obtained results with respect to wear. expected lifetime, surface roughness and infiltration will be discussed. Part III of this project will describe a second initial testing phase where the won results of part 1+11 will be transferred to the AI-Si system. Part IV of this project will describe the field test in a hot-dip-aluminizing plant of the mechanically alloyed bearing bushes under aluminum liquid metal. After testing. the bushes will be characterized and obtained results with respect to wear. expected lifetime, surface roughness and infiltration will be discussed.

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Effect of Antimicrobial Microperforated Film Packaging on Extending Shelf Life of Cluster-type Tomato (Lycopersicon esculentum Mill.) (천연 항균물질 미세천공필름 포장이 송이토마토의 품질에 미치는 영향)

  • Lee, Youn-Suk;Lee, Young-Eun;Lee, Jung-Soo;Kim, Young-Shik
    • Horticultural Science & Technology
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    • v.29 no.5
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    • pp.447-455
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    • 2011
  • To investigate the effects of the improvement of postharvest quality on fresh tomato, antimicrobial microperforated (AMP) films were prepared and their antimicrobial abilities were observed. AMP films were made by coating different types of natural antimicrobial agents such as cinnamon, clove, and clary sage essential oils into microperforated (MP) films. Cinnamon essential oil of 10% (v/v) has proven to be very effective as inhibitor of the mold growth on tomato, compared to the clove and clary sage essential oils. Quality changes of fresh tomatoes packed using the natural AMP films (AMP10 and AMP30) and MP films (MP10 and MP30) during storage were evaluated. Total microbial growth, weight loss, firmness, lycopene content, and decay rate as the major quality parameters were monitored over 9 days at $15^{\circ}C$. The oxygen transmission rates and mechanical properties between the natural AMP and MP films were also compared. There was no significant difference in change of oxygen transmission rate, tensile strength and elongation between the AMP and MP films. For storage studies, the freshness of tomato packaged in AMP30 film was higher than that in OPP film (the control), MP10, MP30, and AMP10 films. Especially, AMP30 film exhibited high efficiency compared to the control for tomato decay during storage periods. Based on the results, the microperforation and antimicrobial properties of the packaged films may significantly affect the maintenance of an optimum gas composition within the package atmosphere for increasing the storage life and quality of produce. They were also effective on the inhibition of microbial growth by controlled release of antimicrobial agent at an appropriate rate from the package into the tomato. Natural antimicrobial agent coating microperforated films could use potential functional package as a method of extending the freshness of postharvest tomato for storage.

Digital painting: Image transfonnation, simulation, heterologie and transfonnation (현대회화에서의 형태와 물질 -Digital Transfiguration에 관한 연구-)

  • Jeong, Suk-Yeong
    • Journal of Science of Art and Design
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    • v.10
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    • pp.161-181
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    • 2006
  • The words which appeared in my theoretical study and work are image transformation to digital painting, simulation, heterologie and transfiguration, etc. Firstly, let's look into 'digital era' or 'new media era'. Nowadays, the image world including painting within the rapid social and cultural change, which is called as digital era, is having the dramatic change. Together with the development of scientific technology, large number of events which was deemed to be impossible is happening as real in image world Moreover, these changes in image world is greatly influencing to our life. The word which compresses this change of image world and shows is 'digital'. Digit, which means fingers in Latin, indicates separately changing signal, and to be more narrow, it indicates the continual signal of '0' and ' 1' in computer. The opposite word is 'analogue'. As analogue is the word meaning 'infer' or 'similarity', it indicates the signal or form which continuously changes along the series of time when it is compared to digital. Instead of analogue, digital is embossed as a major ruler along the whole area of our current culture. In whole culture and art area, and in whole generalscience, digital is appearing as it has the modernism and importance. The prefix, 'digital', e.g. digital media, digital culture, digital design, digital philosophy, etc, is treated as the synonym of modernism and something new. This advent of digital results the innovative change to the image world, creates the new beauty experience which we could not experience before, and forecasts the formation of advanced art and expansion of creative area. Various intellectual activities using computer is developing the whole world with making the infrastructure. Computer in painting work immediately accomplishes the idea of painters, takes part in simulation work, contingency such as abrupt reversal, extraction, twisting, shaking, obscureness, overlapping, etc, and timing to stimulate the creativity of painters, and provides digital formative language which enables new visual experience to the audience. When the change of digital era, the image appeared in my work is shown in 'transfiguration' like drawing. The word, 'transfiguration' does not indicate the completed and fixed real substance but indicate endlessly moving and floating shape. Thus, this concept is opposite to the substantial consideration, so that various concepts which is able to replace this in accordance with the similar cases are also exist such as change, deterioration, mutation, deformity of appearance and morphing which is frequently used in computer as a technical word. These concepts are not clearly classified, and variably and complicatedly related. Transfiguration basically means the denial of "objectivity' and '(continual) stagnation' or deviation from those. This phenomenon is appeared through the all art schools of art ever since the realism is denied in the 19th century. It is called as 'deformation' in case of expressionism, futurism, cubism, etc, in the beginning of the century, which its former indication is mostly preserved within the process of structural deviation and which has the realistic limit which should be preserved. On the contrary, dramatic transfiguration which has been showing in the modern era through surrealism is different in the point that dramatic transfiguration tends to show the deterioration and deviation rather than the preservation of indicated object. From this point, transfiguration coming out from morphing using computer deteriorates and hides the reality and furthermore, it replaces the 'reality'. Moreover, transfiguration is closely approached to the world of fake or 'imaginary' simulation world of Baudrillard. According to Baudrillard, the image hides and deteriorates the reality, and furthermore, expresses 'not existing' to 'imaginary' under the name of transfiguration. Certain reality, that is, image which is absent from the reality is created and overflowed, so that it finally replaces the reality. This is simulation as it is said by Baudrillard. In turn, Georges Bataille discusses about the image which is produced by digital technology in terms of heterologie. Image of heterologie is the visual signal which is established with the media. Image of media is to have the continuous characteristics of produce, extinction, and transformation, and its clear boundary between images becomes meaningless. The meaning of composition, excess, violation, etc of digital image is explained to heterological study or heteologie suggested as important meaning of Georges Bataille who is a heretic philosopher. As the form and image of mutation shows the shape in accordance with mechanical production, heterologie is introduced as very low materialism (or bas materialisme), in this theory. Heterologie as low materialism which is gradually changing is developing as a different concept and analysis because of the change of time in the late 20s century beside high or low meaning. Including my image, all images non-standardizes and transforms the code. However, reappearance and non-standardization of this code does not seem to be simple. The problem of transformation caused by transfiguration which appears in my digital drawing painting, simulation, heterologie, etc, are the continual problems. Moreover, the subject such as existence of human being, distance from the real life, politics and social problems are being extended to actual research and various expressing work. Especially, individual image world is established by digital painting transfiguration technique, and its change and review start to have the durability. The consciousness of observers who look at the image is changing the subject. Together with theoretical research, researchers are to establish the first step to approach to various image change of digital era painting through transfiguration technique using our realistic and historical image.

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The outcome of surfactant replacement therapy in above nearterm neonates with severe pulmonary disease (준 만삭 이상아에서 폐표면 활성제 보충요법의 성적)

  • Shon, Su-Min;Lee, Bo-Young;Kim, Chun-Soo;Lee, Sang-Lak;Kwon, Tae-Chan
    • Clinical and Experimental Pediatrics
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    • v.50 no.12
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    • pp.1200-1205
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    • 2007
  • Purpose : We performed this study to investigate the outcome of surfactant replacement therapy (SRT) in above nearterm neonates who were required mechanical ventilatory care due to meconium aspiration pneumonia (MAP), respiratory distress syndrome (RDS) or other severe pneumonia (PN). Methods : 48 patients, gestational period ${\geq}36weeks$, who were admitted in NICU of Dongsan Medical Center, Keimyung University between July 1999 and June 2004 were enrolled. They were divided into three groups, MAP group (15 cases), RDS group (27 cases) and PN group (6 cases). All patients were received SRT and evaluated several clinical data (gestational age, oxygen index, duration of ventilator care) and outcome (complications and mortality rate) between pre-SRT and post-SRT. The mean dose of surfactant (modified bovine surfactant, Newfacten, Yuhan Co., Seoul, Korea) was 120 mg/kg. Results : Among each groups, mean pre-SRT OI was higher in MAP group ($21{\pm}3.2$) than other groups, mean duration (days) of ventilatory care and oxygen therapy were similar distributions. Compared with pre-SRT values, significant improvements (P<0.05) in mean values for FiO2 and oxygenation index were documented at 12 hours after SRT. Early complications (persistent pulmonary hypertension of newborm, pneumothorax) and survival rate were lower in MAP group. Within RDS group, earlier SRT (given before 12 hours of life) revealed significantly lower early complication rate than later SRT (given after 12 hours of life) (13.3% vs 58.3%, P<0.05) Conclusion : Our study suggested that SRT seems to be an effective therapy in above nearterm neonates with severe pulmonary disease, and earlier SRT tends to reduce complications in RDS group than later therapy.

On the field of domestic studies on Western Art History and Western Art Theory (국내 서양미술사, 서양미술이론 연구 장에 관한 연구)

  • Shim, Sang-Yong
    • The Journal of Art Theory & Practice
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    • no.2
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    • pp.75-120
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    • 2004
  • Studies on western art in Korea has been caught in a dilemma that they could deal with only those things which had been arranged according to their 'historical generalization' in their contexts because of the bounds of time and space. It is not trivial that such conditions affect art studies in Korea. Access to the original texts and to their contexts of production is so restricted that the studies on them are prone to he superficial. And it is not independent on the politics of Korean art scene. Such factors are on the background of Korean art's excessive 'assimilation or accordance' with western art. The domestic studies on western art history and art theory have failed to notice the differences in context and Korean art has simply mediated or reproduced the restricted information by those studies. Also the studies on western art in Korea have been made use of as a justifying method of one's own academic domains. In such situations we should lead the studies on western art history and western art theory to a more reflective direction and confirm that the studies should not have any privileges of the realities. And we should try to reform a scholarship which participates in our life and existence. The field of domestic studies on western art history and western art theory should free itself from the invention of objectivity or the neutrality of mechanical reading and turn its eyes to the realities of life where events happens. Constantly suggesting which way Korean art and world art should go has to be the field's new coordinates.

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Quality Characteristics of Jeung-Pyun Prepared with Milk (우유 첨가에 따른 증편의 품질 선택)

  • Jang, Jung-Sun;Park, Young-Sun
    • Journal of the East Asian Society of Dietary Life
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    • v.18 no.3
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    • pp.311-321
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    • 2008
  • In order to improve the insufficient protein content of Jeung-Pyun with respect to sitology, as well as its fermentation process, this study prepared Jeung-Pyun doughs containing 0, 5, 10, 15, and 20 g of milk, respectively, and examined their mechanical and functional characteristics. The internal structure of the Jeung-Pyun was observed by SEM. With regard to color, the L-value increased with increasing amounts of added milk, and the highest value (65.43) occurred in the group containing 20 g of added milk; however, there were no significant differences among groups. The group containing 20 g of added milk also presented the highest a-value, and the samples with added milk had higher b-values than the control. At 8 hours of fermentation, the 10 g- and 15 g-added milk groups had viscosities of 5726.67 and 6600 respectively; viscosity increased with increasing amounts of milk, and the added-milk groups had significantly higher values than the control group. Hardness also increased with increasing amounts of added milk. However, there were no significant differences in resilience and cohesive power among the groups. The groups containing 5 and 10 g of added milk had the lowest cohesion and break values. For appearance, the group without added milk had the whitest color. Pore size decreased and showed less uniformity as the amount of added milk increased. The unique tackju aroma of Jeung-Pyun decreased significantly as the level of added milk increased, and the 20 g addition presented the lowest value. The 10 g-added milk group had the highest level of sweetness, and sourness increased with increasing amounts of added milk. For softness, the control group was estimated as slightly softer than the added-milk groups. The stickiest sample was generally preferred when considering taste, white color, and sweetness. Among the quality characteristics, having greater stickiness, resilience, moisture, and softness was better in terms of chewing. Overall, the size of the Jeung-Pyun containing 10 g of milk was even and well-developed.

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Effect of Physical, Chemical Properties and of Pelleting Solid Materials on the Germination in Pelleted Carrot Seeds (펠렛 피복물질의 물리, 화학적 특성이 당근 펠렛종자의 발아력에 미치는 영향)

  • Kang, Jum-Soon;Son, Beung-Gu;Choi, Young-Whan;Lee, Yong-Jae;Park, Young-Hoon;Choi, In-Soo
    • Journal of Life Science
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    • v.17 no.12
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    • pp.1701-1708
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    • 2007
  • Seed pelleting is generally conducted in order to save the labor for sowing and thinning by enabling the precision mechanical planting. In the present study, the influence of physical and chemical properties of pelleting solid materials was investigated on carrot seed germination. Among the pelleting solid materials evaluated, dialite, kaolin, and talc showed low bulk density and high porosity. Bentonite and dialite carried high water holding capacities of 184% and 173%, respectively, while calcium carbonate, calcium oxide, and fly ash showed relatively low water holding capacity. The pH of kaolin (6.8) and dialite (7.4) were close to neutral, while limestone (12.8), calcium oxide (13.0), and bentonite (10.0) were highly basic. High electro-conductivity was shown in limestone and calcium oxide. EDS analysis revealed that the main elemental compositions of talc were Si (71.0%) and Mg (29.0%), and those of calcium carbonate were Ca (66.6%), Si (22.9%), and Mg (10.5%). High granulation capacity was observed from talc and the mixture of talc and calcium carbonate. Seeds pelleted with bentonite showed the highest hardness. The dissolving type of the pellet layer after imbibition was split type in talc, limestone, zeolite, and fly ash, melt type in calcium carbonate and calcium oxide, and swell type in bentonite and vermiculite. The shortest dissolving time of pellet layer was observed from calcium carbonate and kaolin. The germination speed $(T_{50})$ was delayed as the size of pelleted seeds increased. The optimum size of pelleting was 19 ratio in carrot.