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INTERGRANULAR CORROSION-RESISTANT STAINLESS STEEL BY GRAIN BOUNDARY ENGINEERING

  • Hiroyuki Kokawa;Masayuki Shimada;Wang, Zhan-Jie;Yutaka S. Sato
    • Proceedings of the KWS Conference
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    • 2002.10a
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    • pp.250-254
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    • 2002
  • Intergranular corrosion of austenitic stainless steels is a conventional and momentous problem during welding and high temperature use. One of the major reasons for such intergranular corrosion is so-called sensitization, i.e., chromium depletion due to chromium carbide precipitation at grain boundaries. Conventional methods for preventing sensitization of austenitic stainless steels include reduction of carbon content in the material, stabilization of carbon atoms as non-chromium carbides by the addition of titanium, niobium or zirconium, local solution-heat-treatment by laser beam, etc. These methods, however, are not without drawbacks. Recent grain boundary structure studies have demonstrated that grain boundary phenomena strongly depend on the crystallographic nature and atomic structure of the grain boundary, and that grain boundaries with coincidence site lattices are immune to intergranular corrosion. The concept of "grain boundary design and control", which involves a desirable grain boundary character distribution, has been developed as grain boundary engineering. The feasibility of grain boundary engineering has been demonstrated mainly by thermomechanical treatments. In the present study, a thermomechanical treatment was tried to improve the resistance to the sensitization by grain boundary engineering. A type 304 austenitic stainless steel was pre-strained and heat-treated, and then sensitized, varying the parameters (pre-strain, temperature, time, etc.) during the thermomechanical treatment. The grain boundary character distribution was examined by orientation imaging microscopy. The intergranular corrosion resistance was evaluated by electrochemical potentiokinetic reactivation and ferric sulfate-sulfuric acid tests. The sensitivity to intergranular corrosion was reduced by the thermomechanical treatment and indicated a minimum at a small roll-reduction. The frequency of coincidence-site-lattice boundaries indicated a maximum at a small strain. The ferric sulfate-sulfuric acid test showed much smaller corrosion rate in the thermomechanically-treated specimen than in the base material. An excellent intergranular corrosion resistance was obtained by a small strain annealing at a relatively low temperature for long time. The optimum parameters created a uniform distribution of a high frequency of coincidence site lattice boundaries in the specimen where corrosive random boundaries were isolated. The results suggest that the thermomechanical treatment can introduce low energy segments in the grain boundary network by annealing twins and can arrest the percolation of intergranular corrosion from the surface.

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Entrepreneurship Education in Internet Business;Current Status & Future Direction (인터넷 창업교육 현황과 발전방안에 관한 연구)

  • Jeong, Jin-Su;Yang, Young-Seok
    • 한국벤처창업학회:학술대회논문집
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    • 2007.11a
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    • pp.143-174
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    • 2007
  • The objective of Starts-up education rears leading company that minimize a risk & connect them with successful idea. Internet Starts-up education is serviced in public & civil parts, it is insufficient to reach successful Starts-up support. This study is targeting on review the present condition of the Internet Starts-up education, research which it sees Internet Starts-up education actual condition investigation through investigation student of education satisfactorily and education contents and the plan to grope an Starts-up education progress coat problem and developmental plan it did. The current events point which has become research result escape first, age of the students of education, followed in educational background and, education motive and education experience presence education satisfactory boat song it appeared in these demand different, base grudge the form which is various it fixed and the education was demanded. Second, currently the department of pedagogy joining in establishment leader against the technical element which is advanced swip, the education reinforcement against an enterprise accomplishment ability back human factor, an enterprise propulsion environment and an enterprise item back enterprise environment element was demanded. Time after support and consulting, completion lifestyle community construction, completion lifestyle for item connection support and the trade name net after third, establishing an enterprise we the king, after toe ring back educating which carries on shoulder the importance of the civil official was embossed. The study which it sees led and like this investigation analysis the education progress for the successful support of the Internet Starts-up and time after connection setup construction it led and the plan which it will put out advancement of Starts-up education and it groped.

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The life and medical idea of Jang Won-So (장원소(張元素)의 생규(生涯)와 의학사상(醫學思想))

  • Kim, Yong-Jin;Yoon, Chang-Yeol
    • Journal of Korean Medical classics
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    • v.4
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    • pp.127-157
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    • 1990
  • Geum-Won dynasty is the era which totalized the every medical attainments of before Song dynasty and appeared some medical practioners who found new medical theory based upon this, and is important time for various developments of the oriental medical theory. At this time of the era, the representative practioners are called the four noted physician of Geum-Won dynasty. Jang Won-So who influenced the formation of the theory of the four noted physcian of Geum-Won dynasty, originated new theory by joining the theory of "Nae-Gyung" with his own medical experience. The results can be summarized as follows after studying his life and idea of medicine. 1. Jang Won-So, courtesy name is Gyeol-Go, came from Yeog-Joo and it is unknown that when he was born and dead, but he lived in 11C. At 27, after failed in a Jin-Sa examination, he started medical study, and widely spreaded his medical art by healing the Yoo Wan-So's Sang-Han disease. 2. There are many Jang Won-So's writings, such as "Eui-Hag-Gye-Won" which is the condensation of his idea of medicine, "Jin-Joo-Nang" which is greatly contributed to development of Herbology, "Jang-Boo-Pyo-Bon-Han-Yeol-Heo-Sil-Yong-Yag-Sig" which is the sample of Jang-Boo-Byun-Jeung-Lon-Chi, and "Yag-Joo-Nan-Gyung" "Gyeol-Go-Ga-Jin" "Gyeol-Go-Joo-Sug-Hwa-Mag-Gyeol" "Gyeol-Go-Bon-Cho" "San-Yog-Bo-Sang-Bang" which are known do not existing. 3. Jang Won-So's study about Jang-Boo-Byun-Jeung was influenced by "Nae-Gyung" "Jung-Jang-Gyung" "So-A-Yag-Jeung-Jig-Gyeol" etc. and outline by Han-Yeol-Heo-Sil and the change and prognosis of the state of disease can be decided by Saeng-Sa-Yeog-Soon, so he contribute to development of lang-Boo-Byun-Jeung-Lon-Chi of posterity. 4. Jang Won-So succeeded and develope the theory of the herbs of Oh-Jang-Go-Yog-Bo-Sa and about Ki-Mi-Seung-Gang-Boo-Chim etc. appeared on "Nae-Gyung", especially invented such as Kwi-Gyung-Lon, In-Gyeung-Bo-Sa-Seol, Jang Boo-Pyo-Bon-Yag-Sig and he enriched the content of pharmacological theory, so he motivated various development of herbalogical theory. 5. Jang Won-So's idea of On-Yang-Bi-Wi directly influence Lee Go's assertion of Bi-Wi-Lon, idea of Go-Geum-I-Gue-Seol presented theological basis of posterior medical practioners formation of prescription, so the way of drug usage greatly developed. 6. Jang Won-So's theory of the lang-Boo-Byun-Jeung and herbology directly influenced to Lee Go, Wang Ho-Go, Na Chen-Ik, lang Byeok etc. so he became the father of Yeog-Soo class and indirectly influenced to Seol Gi, Jo Hen-Ga, lang Gae-Bin, Lee Jung-Jae etc. of Myeng dynasty, so the On-Bo class has been formed. Like this, because, his idea of medicine developed at various aspect and greatly influenced to posterity, Lee Si-Jin said "Since the emergency of "Nae-Gyung", Jang Won-So is the only man who greatly enhance medical principle.", so it is clear that this is not unfounded expression at all.

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A Study on Welding Deformation of thin plate block in PCTC (PCTC 박판 블록 용접 변형에 관한 연구)

  • Kang, Serng-Ku;Yang, Jong-Su;Kim, Ho-Kyeong
    • Proceedings of the KWS Conference
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    • 2009.11a
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    • pp.97-97
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    • 2009
  • The use of thin plate increases due to the need for light weight in large ship. Thin plate is easily distorted and has residual stress by welding heat. Therefore, the thin plate should be carefully joined to minimize the welding deformation which costs time and money for repair. For one effort to reduce welding deformation, it is very useful to predict welding deformation before welding execution. There are two methods to analyze welding deformation. One is simple linear analysis. The other is nonlinear analysis. The simple linear analysis is elastic analysis using the equivalent load method or inherent strain method from welding experiments. The nonlinear analysis is thermo-elastic analysis which gives consideration to the nonlinearity of material dependent on temperature and time, welding current, voltage, speed, sequence and constraint. In this study, the welding deformation is analyzed by using thermo-elastic method for PCTC(Pure Car and Truck Carrier) which carries cars and trucks. PCTC uses thin plates of 6mm thickness which is susceptible to welding heat. The analysis dimension is 19,200mm(length) * 13,825mm(width) * 376mm(height). MARC and MENTAT are used as pre and post processor and solver. The boundary conditions are based on the real situation in shipyard. The simulations contain convection and gravity. The material of the thin block is mild steel with $235N/mm^2$ yield strength. Its nonlinearity of conductivity, specific heat, Young's modulus and yield strength is applied in simulations. Welding is done in two pass. First pass lasts 2,100 second, then it rests for 900 second, then second pass lasts 2,100 second and then it rests for 20,000 second. The displacement at 0 sec is caused by its own weight. It is maximum 19mm at the free side. The welding line expands, shrinks during welding and finally experiences shrinkage. It results in angular distortion of thin block. Final maximum displacement, 17mm occurs around welding line. The maximum residual stress happens at the welding line, where the stress is above the yield strength. Also, the maximum equivalent plastic strain occurs at the welding line. The plastic strain of first pass is more than that of second pass. The flatness of plate in longitudinal direction is calculated in parallel with the direction of girder and compared with deformation standard of ${\pm}15mm$. Calculated value is within the standard range. The flatness of plate in transverse direction is calculated in perpendicular to the direction of girder and compared with deformation standard of ${\pm}6mm$. It satisfies the standard. Buckle of plate is calculated between each longitudinal and compared with the deformation standard. All buckle value is within the standard range of ${\pm}6mm$.

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Effect of Smart Life on Politics, Society, Culture, and Economy (스마트라이프가 정치.사회.문화.경제에 미치는 영향)

  • Kim, Man-Ki
    • Journal of Digital Convergence
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    • v.9 no.6
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    • pp.91-102
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    • 2011
  • Smart work is deeply embedded in our contemporary lives. This is called Smart Life. The expansion of communication, caused by smart life is utilized for the political purposes of politicians, political candidates, and political policies. Chiefly, smart life includes improvement in awareness, personal relations, and policy advocacy. Socially, smart life leads the proliferation of issues and civil movement. In particular, smart life has a significant effect on culture. In the case of K-POP, it is disseminated going beyond space time. It enhances economic value added by joining and sharing at the same time. Smart life has numerous advantages such as improving the quality of life, but it might cause inconvenience depending on users because there are differences in acceptance according to generations. Due to the heavy weight on the device, there are some side-effects such as lacking in human thinking, disclosure in private life, lacking in basic securities, increase in information addicts who are anxious when they do not get on the Internet or SNS, and interference with work. However, this inconvenience can change into convenience when users are accustomed to it. Like this, smart life influences politics, economy, society, and culture a lot. Working environment of smart life is a new paradigm, which can generate high performance through working in an exciting and bright atmosphere with easy economy and putting value on results.

Entrepreneurship Education in Internet Business: Current Status & Future Direction (인터넷 창업교육 현황과 발전방안에 관한 연구)

  • Jeong, Jin-Su;Choi, Jong-In
    • Asia-Pacific Journal of Business Venturing and Entrepreneurship
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    • v.3 no.1
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    • pp.29-55
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    • 2008
  • The objective of Starts-up education rears leading company that minimize a risk & connect them with successful idea. Internet Starts-up education is serviced in public & civil parts, it is insufficient to reach successful Starts-up support. This study is targeting on review the present condition of the Internet Starts-up education, research which it sees Internet Starts-up education actual condition investigation through investigation student of education satisfactorily and education contents and the plan to grope an Starts-up education progress coat problem and developmental plan it did. The current events point which has become research result escape first, age of the students of education, followed in educational background and, education motive and education experience presence education satisfactory boat song it appeared in these demand different, base grudge the form which is various it fixed and the education was demanded. Second, currently the department of pedagogy joining in establishment leader against the technical element which is advanced swip, the education reinforcement against an enterprise accomplishment ability back human factor, an enterprise propulsion environment and an enterprise item back enterprise environment element was demanded. Time after support and consulting, completion lifestyle community construction, completion lifestyle for item connection support and the trade name net after third, establishing an enterprise we the king, after toe ring back educating which carries on shoulder the importance of the civil official was embossed. The study which it sees led and like this investigation analysis the education progress for the successful support of the Internet Starts-up and time after connection setup construction it led and the plan which it will put out advancement of Starts-up education and it groped.

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Genetic Population Structure and Phylogenetic Relationship of the Large-footed Bat (Myotis macrodactylus) on Jeju Island (제주도 큰발윗수염박쥐(Myotis macrodactylus)의 유전적 집단 구조와 계통 유연관계)

  • Kim, Yoo-Kyung;Park, Su-Gon;Han, Sang-Hoon;Han, Sang-Hyun;Oh, Hong-Shik
    • Journal of Life Science
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    • v.26 no.7
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    • pp.749-757
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    • 2016
  • This study was carried out to reveal the genetic population structure of the Jeju Island population and the phylogenetic relationship of East Asian populations of the large-footed bat (Myotis macrodactylus) based on the genetic polymorphisms of mitochondrial cytochrome B (CYTB) and NADH dehydrogenase subunit 1 (ND1) gene sequences. A total of fourteen and nine haplotypes were found in the CYTB and ND1 sequences from East Asian bats, respectively. Haplotype distribution showed locality specific patterns. The results from ND1 haplotype analysis showed that the Jeju Island population has four haplotypes: the Mt. Halla and Western subpopulations have three ND1 haplotypes, but the Eastern subpopulation has just a single haplotype Nd03, which is commonly found on this island. The neighbor-joining (NJ) tree showed the closer relationship between Jeju Island and Japan rather than that between Jeju and Gangwon-do Province. The divergence time between the maternal ancestor lineages of Japanese and Chinese populations was estimated to be 0.789±0.063 MYBP. The secondary divergence between Jeju and Japanese bats was calculated about to be 0.168±0.013 MYBP. The Jeju population has immigrated to the island at least fifty thousand years ago. In addition, ND1 haplotype analysis suggested that the insular bats have experienced at least two further genetic differentiation events within this island. Consequently, these findings suggested that the results of this study may play a critical role in understanding the phylogenetic relationship among East Asian bat populations of M. macrodactylus. To prepare more explainable information on evolutionary correlation, analysis is still required to examine using expanded samples from China, Russia, and southern parts of the Korean Peninsula.

Analysis of inundation and rainfall-runoff in mountainous small catchment using the MIKE model - Focusing on the Var river in France - (MIKE 모델을 이용한 산지소유역 강우유출 및 침수 분석 - 프랑스 Var river 유역을 중심으로 -)

  • Lee, Suwon;Jang, Dongwoo;Jung, Seungkwon
    • Journal of Korea Water Resources Association
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    • v.56 no.1
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    • pp.53-62
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    • 2023
  • Recently, due to the influence of climate change, the occurrence of damage to heavy rain is increasing around the world, and the frequency of heavy rain with a large amount of rain in a short period of time is also increasing. Heavy rains generate a large amount of outflow in a short time, causing flooding in the downstream part of the mountainous area before joining the small and medium-sized rivers. In order to reduce damage to downstream areas caused by flooding, it is very important to calculate the outflow of mountainous areas due to torrential rains. However, the sewage network flooding analysis, which is currently conducting the most analysis in Korea, uses the time and area method using the existing data rather than calculating the rainfall outflow in the mountainous area, which is difficult to determine that the soil characteristics of the region are accurately applied. Therefore, if the rainfall is analyzed for mountainous areas that can cause flooding in the downstream area in a short period of time due to large outflows, the accuracy of the analysis of flooding characteristics that can occur in the downstream area can be improved and used as data for evacuating residents and calculating the extent of damage. In order to calculate the rainfall outflow in the mountainous area, the rainfall outflow in the mountainous area was calculated using MIKE SHE among the MIKE series, and the flooding analysis in the downstream area was conducted through MIKE 21 FM (Flood model). Through this study, it was possible to confirm the amount of outflow and the time to reach downstream in the event of rainfall in the mountainous area, and the results of this analysis can be used to protect human and material resources through pre-evacuation in the downstream area in the future.

A Study of the Material Properties of Steel Used to Repair the Stupa of State Preceptor Jigwang from Beopcheonsa Temple, Wonju in 1957 (1957년 원주 법천사지 지광국사탑 수리에 사용된 철물(鐵物)의 재료학적 특성 연구)

  • You, Harim;Lee, Jaesung;Lee, Taejong;Park, Heejeoung
    • Korean Journal of Heritage: History & Science
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    • v.53 no.4
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    • pp.100-117
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    • 2020
  • National Treasure no. 101, the stupa of State Preceptor Jigwang from the Beopcheonsa Temple Site in Wonju has been transferred from place to place and reassembled several times since it was built. In particular, overall dismantling and repair was carried out in 1957 to restore parts damaged by bombing during the Korean War. Documented information on the repair process and materials used at that time does not exist. However, various types of metal materials used for this stupa have been identified during conservation work. Besides clamps anchor bolts, 9mm-thick circular rebars were mainly used for joining the parts of this stupa, while circular rebars and wires of various thicknesses were used for joining the parts with mortar restoration materials. Although deformed bars are typically used for stone pagodas classified as architectural structures, smooth circular rebars were used in this case. In terms of restoration using mortar, material shapes were transformed, bound alternately, and twisted irregularly to improve bonding strength and coherence in order to insert restoration materials and to bolster structural weaknesses. In addition, metallographic analysis showed the material to be hypo-eutectoid steel with low carbon content. Many non-metallic inclusions in the shape of drops of different sizes were included, which do not affect the whole elemental composition due to the very small quantities involved. Qualitative and EPMA analysis of Mn and S, which were not identified by SEM-EDS area analysis, established an even distribution of MnS in crystal grains of the microstructure, regardless of the shape of the samples. It is presumed that secondary homogenization and softening might have been conducted after manufacturing to facilitate the working process. Furthermore, in consideration of properties indicating that the thinner the steel is, the less carbon content contained and the greater the elasticity and elongation, it is judged that restoration work was ordered.

Characteristics and Significance of the Huirang Daesa Sculpture at Haeinsa Temple in Hapcheon (합천(陜川) 해인사(海印寺) 희랑대사상(希朗大師像)의 특징과 제작 의미)

  • Jeong, Eunwoo
    • MISULJARYO - National Museum of Korea Art Journal
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    • v.98
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    • pp.54-77
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    • 2020
  • Produced during the Goryeo period (718-1392), the statue of the monk Huirang Daesa at Haeinsa Temple in Hapcheon is almost life-size, with a height of 82.4 cm, a width of 66.6 cm at the knees, and a maximum width of 44 cm at the torso (front and back). Notably, it is the only known example of an East Asian Buddhist sculpture made from wood and dry lacquer that was formed by joining the front and back halves. However, a similar technique was used on a dry lacquer statue of the Medicine Buddha at Cheongnyangsa Temple in Bonghwa, which is estimated to date from the late Goryeo or early Joseon period. As such, this technique is thought to represent this particular time period. In an eighteenth-century travelogue about a trip to Mt. Gayasan, the author describes a sculpture that is believed to be the statue of Huirang Daesa at Haeinsa Temple, based on various unique features that closely correspond to the sculpture's current appearance. For example, the sculpture is said to have a hole in the chest and rough, knobby tendons and bones, two features that can still be seen today. Another sculpture of a Buddhist monk who was active in the western regions during the third and fourth century also has a hole in the chest, which is said to be a symbol of spiritual strength. The travelogue also states that the statue was lacquered black at the time, which means that it must have been painted with its present colors some time in the nineteenth century. Over time, the sculpture has been enshrined in various halls of Haeinsa Temple, including Haehaengdang, Jinsangjeon, and later Josajeon (Hall of the Patriarchs), and Bojangjeon. Records show that images of Buddhist monks, or "seungsang," were produced in Korea as early as the Three Kingdoms period (18 BCE-660 CE), but few of these works have survived. At present, only four such sculptures are extant, including the images of Huirang Daesa from the Goryeo period, and those of Monk Naong and Uisang Daesa from the Joseon period. Of these, the sculpture of Huirang Daesa has special significance for its early production date (i.e., CE. tenth century), outstanding production techniques, and superb artistic quality, realistically capturing both the external appearance and internal character of the subject. The tradition of producing, sanctifying, and worshipping statues of monks was prevalent not only in Korea, but also in China and Japan. However, each country developed its own preferred materials and techniques for producing these unique images. For example, while China has a large number of mummified Buddhist images (yuksinbul), Japan produced diverse images with various materials (e.g., dry lacquer, wood, clay) according to period. But despite the differences in materials and techniques, the three nations shared the same fundamental purpose of expressing and honoring the inherent spirituality of the monks.