• Tribology and Lubricants
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• 제36권1호
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• pp.47-54
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• 2020

In this study, the effects of ultrasonic nanocrystal surface modification (UNSM) treatment at room and high temperatures (RT and HT of 400℃) on friction and wear behavior of Ti-6Al-4V alloy prepared by selective laser melting (SLM) were investigated. The objective of this study is to improve the mechanical properties and frictional behavior of Ti-6Al-4V alloy by UNSM treatment. Dry friction and wear tests were conducted using a ball-on-disk method at RT with a bearing steel as the counter ball. Due to the high HT and UNSM treatment, the surface hardness tended to increase and surface roughness tended to reduce. X-ray diffraction (XRD) analysis showed that nanocrystallization structure and compressive residual stress were formed at the surface layer after UNSM treatment at both RT and HT. After UNSM treatment, it was observed that the wear rate was reduced by about 6% for the specimen treated at RT and a 28% reduction for the specimen treated at HT in comparison with the untreated one. Based on scanning electron microscope (SEM) images showed that the damage caused by fatigue wear occurred in the wear track of the heat-treated specimen, and it is believed to be the cause of the highest wear rate. Mechanical properties and wear resistance of Ti-6Al-4V alloy were improved and prospect of industrial application was confirmed. Further research is still required to improve the characteristics of SLM Ti-6Al-4V alloy to the level of wrought Ti-6Al-4V alloy.

• 한국의상디자인학회지
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• 제7권2호
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• pp.61-74
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• 2005

Wonsam, a type of korean women's gown in Choseon Dynasty, was used as a small ceremonial costume for queens, crown princesses and princesses and as a grand ceremonial costume for royal concubines and wives of high rank officials. It was also worn as a wedding dress for commoners. In the families of illustrious officials, it was also used as burial accessories or garments for the dead. In this context, Wonsam is a formal dress for the people's most important four ceremonies of coming-of-age, marriage, funeral, and ancestor worship. It is worth emphasizing the costume since it was widely and importantly used by all ranks of women, from royal families to commoners. Through the Wonsam of An-dong Kim Clan's, we can see what the society was like at the end of Choseon Dynasty. First, a status system that strictly divided costumes for each class, was, in many parts, broken down. Second, the highly wrought patterns and texture of fabrics of the Wonsam reveal that it was granted from Court, or, if woven by the Kim family, it is considered to be produced by the Court's craftsman or through technical transfer, considering that the weaving skills used are as good as those in Courts. Third, regarding the precise needlework that is uncomparable to textiles used by other illustrious officials families, the Wonsam is considered to be granted from Court or, produced through the needlework skills that were handed down from needlewomen in Courts. The Wonsam of An-dong Kim Clan's has noble beauty in it, with outstanding weaving skills, fabrics, needlework and shape. Thus, it is no exaggeration to say that it has those qualities to be the standard costume that inherits the tradition of Korean people.

• 한국실내디자인학회논문집
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• 제15권5호
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• pp.85-94
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• 2006

Due to multidisciplinary characteristic of the Interior Design field, it has developed into complex interdisciplinary field. Therefore Interior Design field has grown and established its major trends dependent upon other related field of study. With this perspective in mind, esthetics on Interior Design has to be treated in similar manner. In modem architects or artists have defined the terminology 'object' theoretical principle where by unable to distinguish between 'object's type' and 'objects', Presently, the term 'object' became a trend word. In order to confront misconception of the idea of 'Objectification', some people definition as reflection of this complex society. In this paper, it will establish a solid groundwork for a discussion on Objectification. The initial approach will deal with Le Corbusier and esthetics, which is the center of argument. By reviewing theoretical background of the related modern art, the paper discusses about the relationship between Le Corbusier and esthetics. Subsequently, the discussion about the criterions necessary to define object is provided. This paper only suggests a methodology of analyzing a trend in Interior Design. The condition to define Objectification in Interior Design, which is a result of the reviewing process on esthetics, can be concluded as 'modeling form(transformation of morphological meaning with change wrought by causing a visual reaction)', 'mixtures and modification of materials(transformation and spontaneity through mixing materials)' and 'elements greatly influence space' of the Interior Design.

• 한국재료학회지
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• 제26권10호
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• pp.528-534
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• 2016

The aim of this paper is to consider the effect of the manufacturing processes on corrosion and centerline cracking of ancient bronze spoons. The ancient bronze spoons in question were made by several steps of forging, in reheated condition with cast ingots. The manufacturing method is similar to that of the modern spoons. The investigations include observations from light and scanning electron microscopes of the microstructure in terms of the crack propagation. Cracks in the centerline are caused by solute segregation in the center-line region; this solute is solidified in the final stage of bronze spoon manufacture. Centerline cracking is also caused by ${\alpha}$ phase segregation, accompanied by forged overlapping along the longitudinal direction of the spoons. A vertical stripe with cracks along the centerline of the spoon's width is formed by folding in the wrought process. The overlapping area causes crack propagation with severe corrosion on the spoon surfaces over a period of a thousand years. The failure mechanisms of ancient bronze spoons may be similar to that of modern spoons, and the estimation of the failure mechanisms of ancient spoons can be appropriate to determine failure causes for such modern spoons.

• 대한기계학회논문집
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• 제18권9호
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• pp.2374-2385
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• 1994

SiCw/Al composite material is especially attractive because of their superior specific strength, specific stiffness, corrosion fatigue resistance, creep resistance, and wear resistance compared with the corresponding wrought Al alloy. In this study, Fatigue crack growth behavior and fatigue crack path morphology(FCPM) of SiC whisker reinforced Al 6061 alloy with 25% SiC volume fraction and Al 6061 allay were performed. Result of the fatigue crack growth test sgiwed that fatigue crack growth rate of SiCw/Al 6061 composite was slower than that of Al 6061 matrix therefore it was confirmed that Sic whisker have a excellent fatigue resistance. And Al 6061 matrix had only FCPM perpendicular to loading direction. On the other hand SiCw/Al 6061 composite had three types in fatigue crack path morphology. First type is that both sides FCPM of artificial notch are perpendicular to loading direction. Second type is that a FCPM in artifical notch has slant angle to loading direction and the other side FCPM is perpendicular to loading direction. Third type is that both sides FCPM of notch have slant angle to loading direction. It was considered that this kinds of phenomena were due to non-uniform distribution of SiC whisker and confirmed by SEM observation for fracture mechanism study.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 제5회 압연심포지엄 신 시장 개척을 위한 압연기술
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• pp.63-71
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• 2004

Recently, a sheet forming process of Mg alloys is highlighted again due to increasing demand for Mg wrought alloys in the applications of casings of mobile electronics and outer-skins of light-weight transportation. Microstructure control is essential for the enhancement of workability and formability of Mg alloy sheets. In this research, AZ31 Mg alloy sheets were prepared by hot rolling process and the rolling condition dependency of the microstructure and texture evolution was studied by employing a conventional rolling mill as well as an asymmetric rolling mill. When rolled through multiple passes with a small reduction per pass, fine-grained and homogeneous microstructure evolved by repetitive dynamic and static recrystallization. With higher rolling temperature, dynamic recrystallization was initiated in lower reduction. However with increasing reduction per pass, deformation was locallized in band-like regions, which provided favorable nucleation sites f3r dynamic recrystallization. Through post annealing process, the microstructures could be transformed to more equiaxed and homogeneous grain structures. Textures of the rolled sheets were characterized by $\{0002\}$ basal plane textures and retained even after post annealing. On the other hand, asymmetrically rolled and subsequently annealed sheets exhibited unique annealing texture, where $\{0002\}$ orientation was rotated to some extent to the rolling direction and its intensity was reduced.

• 한국분말재료학회지
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• 제22권4호
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• pp.271-277
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• 2015

As wrought stainless steel, sintered stainless steel (STS) has excellent high-temperature anti-corrosion even at high temperature of $800^{\circ}C$ and exhibit corrosion resistance in air. The oxidation behavior and oxidation mechanism of the sintered 316L stainless was reported at the high temperature in our previous study. In this study, the effects of additives on high-temperature corrosion resistances were investigated above $800^{\circ}C$ at the various oxides ($SiO_2$, $Al_2O_3$, MgO and $Y_2O_3$) added STS respectively as an oxidation inhibitor. The morphology of the oxide layers were observed by SEM and the oxides phase and composition were confirmed by XRD and EDX. As a result, the weight of STS 316L sintered body increased sharply at $1000^{\circ}C$ and the relative density of specimen decreased as metallic oxide addition increased. Compared with STS 316L sintered parts, weight change ratio corresponding to different oxidation time at $900^{\circ}C$ and $1000^{\circ}C$, decreased gradually with the addition of metallic oxide. The best corrosion resistance properties of STS could be improved in case of using $Y_2O_3$. The oxidation rate was diminished dramatically by suppression the peeling on oxide layers at $Y_2O_3$ added sintered stainless steel.

• Journal of Welding and Joining
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• 제31권3호
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• pp.31-38
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• 2013

The transition of serrated grain boundary and its effect on liquation behavior in the simulated weld heat-affected zone (HAZ) have been investigated in a wrought Ni-based superalloy Alloy 263. Recently, the present authors have found that grain boundary serration occurs in the absence of adjacent coarse ${\gamma}^{\prime}$ particles or $M_{23}C_6$ carbides when a specimen is direct-aged with a combination of slow cooling from solution treatment temperature to aging temperature. The present study was initiated to determine the interdependence of the serration and HAZ property with a consideration of this serration as a potential for the use of a hot-cracking resistant microstructure. A crystallographic study indicated that the serration led to a change in grain boundary character as special boundary with a lower interfacial energy as those terminated by low-index {111} boundary planes. It was found that the serrated grain boundaries are highly resistant to boron enrichment, and suppress effectively grain coarsening in HAZ. Furthermore, the serrated grain boundaries showed a higher resistance to susceptibility of liquation cracking. These results was discussed in terms of a significant decrease in interfacial energy of grain boundary by the serration.

• 열처리공학회지
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• 제21권6호
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• pp.293-299
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• 2008

In order to provide with fundamental data of the wrought Mg alloy for press forging, the effect of annealing temperature on the microstructure, texture development and tensile properties is studied in a commercial AZ31B Mg alloy sheet. Basal texture i.e. $(0001){\pm}5^{\circ}$[21$\bar{3}$0] is developed in a commercial AZ31B Mg sheet, and the texture is not changed considerably by annealing over $400^{\circ}C{\times}30min$, while (10$\bar{3}$0) component with high intensity can be observed due to abnormal grain growth. When the sheet is tensile-deformed with RD, $45^{\circ}$ and TD directions at room temperature, fracture strains are given by 25.8, 21.4 and 11.9% in the order of RD, $45^{\circ}$ and TD directions, respectively. With increasing annealing temperature up to $450^{\circ}C{\times}30min$, little change in mean grain size can be revealed by annealing below $300^{\circ}C{\times}30min$ but an abnormal grain growth, where some grains become significantly coarser than the rest, occurs by annealing above $400^{\circ}C{\times}30min$. The maximum tensile strain of around 25% is obtained by annealing below $300^{\circ}C{\times}30min$, but it is abruptly decreased to 16% by annealing above $400^{\circ}C{\times}30min$ owing to intergranular fracture of abnormal grown grains.

• 영어영문학
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• 제56권4호
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• pp.691-717
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• 2010

Chaucer's Troilus and Criseyde is a tale of love framed by an overarching pattern of death, set in the war-torn and doomed Troy, from which the lovers cannot separate their fate. Compared with Boccaccio's poem, the attention paid to death in Chaucer's version underlies his complex treatment of love. Above all, the language of death in Chaucer's poem provides the thread from which the entangled web of love is woven. Death together with desire pervades the language and rhetoric of the poem, prominent not only in the courtly love tropes, but also in the characters' asides and speeches. The prominence of these two concepts, desire and death, seem to be central to the various issues that the poem contains explicitly and implicitly. That is, two concepts are the basis for the breadth and depth of Chaucer's examination of love in light of the social and political realities of late fourteenth century England. The language of death in Chaucer's poem reflects the powerful influence on his imagination. With the devastation wrought by the plague and the changing fortunes of England in the war with France, Chaucer's world was once saturated in death, and one that could amply parallel the turn from prosperity to downfall. In particular, Chaucer's poem is suffused with the language of contagion and death in connection with desire. Troilus's lovesickness mimics the progress of a viral infection. Once breached, his body performs its newly compromised identity through fever, loss of appetite, and physical disintegration. On the other hand, Chaucer depicts Boccaccio's conventional portrait of Criseyde into a elaborate paramour of a pathogen. She is characterized as the contaminant that infects male hero. In addition, Criseyde is cast as sole earthly cure of illness that Troilus suffers from. In spite of Criseyde's role as nurturer and healer, Troilus longs for his own death and feels death clutching his heart. Finally, Troilus's love toward Criseyde is doomed to death.