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Science And Technology Of Korea
Like most other regions in the world, science and technology in Korea has experienced periods of intense growth as well as long periods of stagnation. Prehistory At the end of the Palaeolithic, people of the Korean Peninsula adopted microlithic stone tool technology, a highly efficient and useful way of making and maintaining a flexible prehistoric toolkit. The Palaeolithic also marks the beginning of a long period of plant and human interaction in which people undoubtedly adopted a number of wild plants for medicinal use. Archaeological evidence from Gosan-ri in Jeju-do indicates that pottery was first made c. 8500-8000 BC. People depended on gathering, hunting, and fishing as the main source of food until the Middle Jeulmun Period (c. 3500 to 2000 BC) when small-scale cultivation of plants began.Crawford and Lee The earliest known constellation patterns in Korea can be found on dolmens dating back to 3000 BC. Farmers of the Mumun Period began to use multiple cropping syste ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palaeolithic
The Paleolithic or Palaeolithic (), also called the Old Stone Age (from Greek: παλαιός ''palaios'', "old" and λίθος ''lithos'', "stone"), is a period in human prehistory that is distinguished by the original development of stone tools, and which represents almost the entire period of human prehistoric technology. It extends from the earliest known use of stone tools by hominins, 3.3 million years ago, to the end of the Pleistocene, 11,650 cal BP. The Paleolithic Age in Europe preceded the Mesolithic Age, although the date of the transition varies geographically by several thousand years. During the Paleolithic Age, hominins grouped together in small societies such as bands and subsisted by gathering plants, fishing, and hunting or scavenging wild animals. The Paleolithic Age is characterized by the use of knapped stone tools, although at the time humans also used wood and bone tools. Other organic commodities were adapted for use as tools, includ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brazier
A brazier () is a container used to burn charcoal or other solid fuel for cooking, heating or cultural rituals. It often takes the form of a metal box or bowl with feet. Its elevation helps circulate air, feeding oxygen to the fire. Braziers have been used since ancient times; the Nimrud brazier dates to at least 824 BC. History The word brazier is mentioned in the Bible. The Hebrew word for brazier is believed to be of Egyptian origin, suggesting that it was imported from Egypt. The lone reference to it in the Bible being the following verse: * - the winter palace of King Jehoiakim was heated by a brazier (). Roman Emperor Jovian was poisoned by the fumes from a brazier in his tent in 364, ending the line of Constantine. Uses Heating Despite risks in burning charcoal on open fires, braziers were widely adopted for domestic heating, particularly and somewhat more safely used (namely in unglazed, shuttered-only buildings) in the Spanish-speaking world. Fernando de Alva Cor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dragon Kiln
A dragon kiln () or "climbing kiln", is a traditional Chinese form of kiln, used for Chinese ceramics, especially in southern China. It is long and thin, and relies on having a fairly steep slope, typically between 10° and 16°, up which the kiln runs. The kiln could achieve the very high temperatures, sometimes as high as 1400°C, necessary for high-fired wares including stoneware and porcelain, which long challenged European potters, and some examples were very large, up to 60 metres long, allowing up to 25,000 pieces to be fired at a time. By the early 12th century CE they might be over 135 metres long, allowing still larger quantities to be fired; more than 100,000 have been claimed. History According to recent excavations in Shangyu District in the northeast of Zhejiang province and elsewhere, the origins of the dragon kiln may go back as far as the Shang dynasty (c. 1600 to 1046 BCE), and is linked to the introduction of stoneware, fired at 1200°C or more. These kilns we ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glass Transition
The glass–liquid transition, or glass transition, is the gradual and reversible transition in amorphous materials (or in amorphous regions within semicrystalline materials) from a hard and relatively brittle "glassy" state into a viscous or rubbery state as the temperature is increased. ISO 11357-2: Plastics – Differential scanning calorimetry – Part 2: Determination of glass transition temperature (1999). An amorphous solid that exhibits a glass transition is called a glass. The reverse transition, achieved by supercooling a viscous liquid into the glass state, is called vitrification. The glass-transition temperature ''T''g of a material characterizes the range of temperatures over which this glass transition occurs (as an experimental definition, typically marked as 100 s of relaxation time). It is always lower than the melting temperature, ''T''m, of the crystalline state of the material, if one exists. Hard plastics like polystyrene and poly(methyl methacrylate) are u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stoneware
Stoneware is a rather broad term for pottery or other ceramics fired at a relatively high temperature. A modern technical definition is a Vitrification#Ceramics, vitreous or semi-vitreous ceramic made primarily from stoneware clay or non-refractory fire clay. Whether vitrified or not, it is nonporous (does not soak up liquids);Arthur Dodd & David Murfin. ''Dictionary of Ceramics''; 3rd edition. The Institute of Minerals, 1994. it may or may not be glaze (ceramics), glazed. Historically, around the world, it has been developed after earthenware and before porcelain, and has often been used for high-quality as well as utilitarian wares. As a rough guide, modern earthenwares are normally fired in a kiln at temperatures in the range of about 1,000 °Celsius, C (1,830 Fahrenheit, °F) to ; stonewares at between about to ; and porcelains at between about to . Historically, reaching high temperatures was a long-lasting challenge, and temperatures somewhat below these were used for a lo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
YouTube
YouTube is a global online video platform, online video sharing and social media, social media platform headquartered in San Bruno, California. It was launched on February 14, 2005, by Steve Chen, Chad Hurley, and Jawed Karim. It is owned by Google, and is the List of most visited websites, second most visited website, after Google Search. YouTube has more than 2.5 billion monthly users who collectively watch more than one billion hours of videos each day. , videos were being uploaded at a rate of more than 500 hours of content per minute. In October 2006, YouTube was bought by Google for $1.65 billion. Google's ownership of YouTube expanded the site's business model, expanding from generating revenue from advertisements alone, to offering paid content such as movies and exclusive content produced by YouTube. It also offers YouTube Premium, a paid subscription option for watching content without ads. YouTube also approved creators to participate in Google's Google AdSens ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alaska
Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., it borders the Canadian province of British Columbia and the Yukon territory to the east; it also shares a maritime border with the Russian Federation's Chukotka Autonomous Okrug to the west, just across the Bering Strait. To the north are the Chukchi and Beaufort Seas of the Arctic Ocean, while the Pacific Ocean lies to the south and southwest. Alaska is by far the largest U.S. state by area, comprising more total area than the next three largest states (Texas, California, and Montana) combined. It represents the seventh-largest subnational division in the world. It is the third-least populous and the most sparsely populated state, but by far the continent's most populous territory located mostly north of the 60th parallel, with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Okjeo
Okjeo () was an ancient Korean tribal state which arose in the northern Korean peninsula from perhaps the 2nd century BCE to the 5th century CE. Dong-okjeo (Eastern Okjeo) occupied roughly the area of the Hamgyŏng provinces of North Korea, and Buk-okjeo (Northern Okjeo) occupied the Duman River region. Dong-okjeo was often simply called Okjeo, while Buk-okjeo was also sometimes referred to as Chiguru (置溝婁, 치구루) or Guru (구루), the latter name being also applied to Goguryeo. Okjeo bordered the other minor state of Dongye on the south, and shared a similar fate. History In its early history, Okjeo oscillated between domination by the Chinese commanderies and by Goguryeo. From the 3rd century BCE to 108 BCE, it was controlled by Gojoseon. At 107 BCE, it became part of the Xuantu Commandery. As the Xuantu Commandery retreated towards the liadong peninsula as a result of expansion of Goguryeo, East okjeo became part of the eastern part of the Lelang Commandery. Du ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ondol
Ondol (; , Hangul: 온돌, 溫堗, ) or gudeul (Hangul: 구들, ) in Korean traditional architecture, is underfloor heating that uses direct heat transfer from wood smoke to heat the underside of a thick masonry floor. In modern usage it refers to any type of underfloor heating, or to a hotel or a sleeping room in Korean (as opposed to Western) style. The main components of the traditional ''ondol'' are an ''agungi'' (firebox or stove) accessible from an adjoining room (typically kitchen or master bedroom), a raised masonry floor underlain by horizontal smoke passages, and a vertical, freestanding chimney on the opposite exterior wall providing a draft. The heated floor, supported by stone piers or baffles to distribute the smoke, is covered by stone slabs, clay and an impervious layer such as oiled paper. History Origin Use of the ''ondol'' has been found at archaeological sites in present-day North Korea. A Neolithic Age archaeological site, circa 5000 BC, discovered in Unggi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Songguk-ri
Songguk-ri () is a Middle and Late Mumun-period (c. 850–300 B.C.) archaeological site in Buyeo-gun, Chungcheongnam-do, South Korea. Songguk-ri is a settlement and burial site that is important in the study of Korean prehistory. It is registered as Historical Site No. 249. Songguk-ri is a main point of reference in Korean prehistory—Korean archaeologists have represented the prehistoric village and the material culture excavated from there as the type-site for Middle Mumun Culture in southern Korea. History of Excavations Excavations began there in 1975 and Songguk-ri was one of the first archaeological sites in South Korea to yield bronze artifacts, large tubular greenstone beads, and pit-houses with rounded plan-shapes. Rounded pit-houses similar with those of Songguk-ri were later found at other archaeological sites along with a suite of other co-occurring artifacts prompting archaeologists to use Songguk-ri as the type site for Middle Mumun culture and label features an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molding (process)
Molding (American English) or moulding (British and Commonwealth English; see spelling differences) is the process of manufacturing by shaping liquid or pliable raw material using a rigid frame called a mold or matrix. This itself may have been made using a pattern or model of the final object. A mold or mould is a hollowed-out block that is filled with a liquid or pliable material such as plastic, glass, metal, or ceramic raw material. The liquid hardens or sets inside the mold, adopting its shape. A mold is a counterpart to a cast. The very common bi-valve molding process uses two molds, one for each half of the object. Articulated molds have multiple pieces that come together to form the complete mold, and then disassemble to release the finished casting; they are expensive, but necessary when the casting shape has complex overhangs. Piece-molding uses a number of different molds, each creating a section of a complicated object. This is generally only used for larger a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
