It's about ondol.

 It's about ondol. Since we always live together, we often don't know the excellence, but I think ondol is the same. ---------------------------------- Ondol and thatched houses 50,000 years ago, traces of ondol were found in Hoeryeong Paleolithic ruins, so Korea has a narrow and small land, but climate change is severe. The climate with such a large annual temperature difference is said to be a continental climate because it is more affected by continents with smaller specific heat than the ocean. And due to the influence of seasonal winds, precipitation is five to ten times more depending on the region in the rainy summer than in the dry winter. Summer covers and rains a lot, and winter is very cold and dry. It is a so-called high temperature and low humidity climate. The expression that there is an discomfort index in summer and that it is cold as if biting flesh in winter is just right. Korea is not the only continental climate. In the eastern part of the continent with the same latitude as Korea, a continental climate appears. Japan, China's Yellow Sea coast, and New York in the eastern United States. However, it goes without saying that the climate in this region is also significantly different from ours. It is estimated that Paleolithic people lived in this land about 1 million years ago on the Korean Peninsula. The remains of the Black Moru found in Heukwoori, Sangwon-gun, Pyongyang-si, were found to have been roughly broken along with 29 kinds of beast bone fossils, which were found to have been left by people at the cause level about 1 million years ago. However, it is estimated that artificial housing generally began around 5,000 BC. In the early days, it was a structure in which the ground was dug to make a wall, and a roof frame was woven with wood to cover it, but it gradually develops into a residential area. In the hut, there was a fireplace inside Um to heat it, but as it developed into a residential area, the heating method naturally changed. What appeared at this time was ondol (also expressed in spheres). Ondol refers to a heating structure designed to warm the floor by slowly releasing radiant heat by making a girdle whale and placing a girdle field on top of the whale to spend the cold winter, and is recognized as an international language. This dictionary writes about ondol as "heating that covers the room through a passage from the furnace to the bottom of the room." In The Journal of North and East Tartaria (Northern Asia), published in 1690, Witsen of the Netherlands wrote about ondol, "When making a room, we drill a hole of about 15 centimeters under the floor and smoke from a furnace installed outside the door to warm the room." In 1883, Percy Beal Lowell, a Boston-born scientist in the United States, visited Joseon with them after visiting the United States as a guide to the first Gyeonmi mission in Joseon and stayed in Joseon that winter. After that, Lowell returned to the United States and published a book called Chosun, a Quiet Morning Country in 1885. In this book, various social, cultural, and pungmul of Joseon at the time are recorded, and among them, there is also a record of a strange heating method called Ondol. Ondol acts as a kind of furnace to warm the room in winter. Outside the room, there is a stove hole, which is called a furnace. When the fire breaks out, the heat spreads widely on the floor along a maze that looks like a honeycomb. The idea is excellent, and if you supplement the ventilation system, it will be a great heating system." Using ondol since the ancient Joseon Dynasty It has been a long time since Koreans used ondol. In North Korea, the remains of ondol during the Gojoseon period were found in the ruins of Sjuk-ri, Yeongbyeon-gun, Ronam-ri, and Yeonhwabo, Yoryeongseong Fortress, and the ondol excavated from two of the five houses in Sjuk-ri was an L-shaped single whale ondol. The ondol whale is made of flat and elongated stones and a thin sheet stone on top of them. At the front of the whale, there is a deeper furnace than the whale, and the length of the ondol whale was 3-4 meters. Such ondol ruins were also found in Musun City in northeastern China. This area is also the area of Gojoseon, which precedes the existing theory that viewed the origin of ondol as Goguryeo in the early days. However, the first literature on ondol can be found in Sugyeongju, an old Chinese geography book. This book was written by the Northern Weightlifting Center between 500 and 513, and it contains the story of ondol, saying, "It warms the floor of the room by holding stones in several strands under the floor of the room and applying mud on top to make fire flow into several branches. However, scholars estimate that the period of ondol is much older than this. The period dates back to the Paleolithic period as floors and walls presumed to be spheres were excavated from the Paleolithic residential site in O-dong, Hoeryeong, estimated to be 50,000 years ago. In addition, scholars speculate that the early ondol was caused by primitive people flowing in northern China or Manchuria, a harsh Paleolithic region, considering the foundation of the skull fossil site in the Yellow River basin estimated to be about 1 million years ago. In any case, the ondol in the early Goguryeo period can be found in the ruins of Toseong-ri, Augmented-gun, Jagang-do. Four ondols were found in the fourth district of this relic, and the ondol structure is a single whale ondol made by standing flat dolmens in two rows and mincing the bottom of it with mud. The whale is 20 centimeters wide and 20 to 25 centimeters high. Gudeul Whale is located 3.6 meters north and south and is bent at a right angle from south to west. In Dongijeon in Gudangseo and Sindangseo in China, the residence was built on a valley, and the roof was built with a band or grass, but Bulsa Temple, Sinmyo Shrine, royal palace, and Gwanaman Bay were tile roofs. According to the custom, there is a record that poor people make long gangs and heat them warmly for the winter. Looking at the phrase "Bulsa," it seems to be the record after the second year (372) of King Sosorim, when Buddhism was introduced to Goguryeo. Here, Gang is a heating facility called Can by Chinese people. The can and ondol have the same origin, but the ondol heats the entire floor, while the can heats only part of the floor by stacking bricks on one side of the room. The phrase "poor people make janggang to spend the winter and heat it warmly" means that the upper class used a heating method, not an ondol. In the upper class, it is presumed that separate facilities such as iron brazier and stove were placed in the room and heated. Goguryeo murals often feature the main characters sitting on chairs. Therefore, scholars speculate that during the Goguryeo period, standing culture in chairs and ondol culture on desk legs were already mixed. Records or evidence of Ondol in "Compromise between Ondol and Daecheong" do not appear in Baekje or Silla, but they are relatively warmer than in the north, so it is assumed that they were satisfied with installing a brazier or a brazier for the winter. In the section of King Heongang (875-886) of The History of the Three Kingdoms, it is recorded that there are tile-roofed houses lined up in Seorabeol and that they cooked rice with charcoal. This is also cited as evidence that ondol has not yet developed. Ondol began to spread nationwide after entering the early Joseon Dynasty through the Goryeo Dynasty. The term Ondol also began to be used in the early Joseon Dynasty, and the entire room where the gudeul was placed was called Ondolbang. The development of ondol resulted in the finishing of ondol rooms, especially the development of floorboards, and various methods were used to close floorboards during King Yeongjo's reign. Since the south of Korea's Korean Peninsula is relatively warm, Daecheong has developed. Daecheong is developed in houses in the south of central Korea. This is a floor room with an empty floor. When I was young, I often used under the floor playing hide-and-seek, but I remember that when the tagger came in to find people, he knew that it was cool under the floor and stopped playing hide-and-seek. It was also used as a sleeping space when it was hot in summer, but these days, the new generation of people may wonder how to sleep in a place where it is dark and has many webs. However, in a house with a child, the floor is always clean, so there was no need to worry about spider webs. This is because the most precious space for young children was just under the floor. Daecheong, which developed in the south, continues to try northward and ondol also tries southward of "Hoshi Tam Tam Tam" and finally makes a grand compromise in Seoul and Gyeonggi. A dual structure in which floors and ondol coexist in one house appears. In other words, it is a cool Daecheong for summer and an ondol room, a living space in winter. This encounter dates back to the Goryeo Dynasty. In Lee In-ro's 1152-1220, there is the following article in Gongju Dongjeonggi. "I built a pavilion called Dongjeong in Gongju. This pavilion was built according to the topography, and it has 14 bays in size, and Uksil for winter and Yangcheong for summer were built." Here, it shows that the ondol structure called Wooksil and the floor structure called Yangcheong were installed in one building. Some scholars say that there is no confirmation that Wooksil is an ondol structure, so it cannot be said that ondol and maru were combined during the Goryeo Dynasty. There is also an explanation that it shows that summer and winter are prepared at the same time in one building, which is a characteristic of Korea. In any case, the combination of ondol and floor into one house is a concept of a special residence born in a Korean climate with clear four seasons, and is almost unprecedented in the world.  "Scientific Ondol Heating Method" The principle of Ondol is a type of radiant heating method using heat conduction. Firearms are sent through a banger to heat the heated spheres emitted. Because the floor of the room is evenly covered, it is not humid and safe against fire. However, traditional ondol in Korea can maintain a relatively comfortable indoor climate, but it is a very disadvantageous method in terms of energy because it has only 30% of the actual thermal efficiency because it has a lot of calories lost through furnaces and chimneys. Therefore, in order to compensate for the inefficient aspects of heating only, cooking can be done together. It can be said that it is the wisdom of the good that has led to a double effect in consideration of this energy-efficient aspect. The secret to keeping ondol warm for a long time is the selection of stones, the ingredient of Gudeuljang. Our ancestors especially chose mica among the various stones around them.

Unmo is a mineral commonly found in igneous and metamorphic rocks and is divided into layer structures such as Baegunmo, Sodownmo, biotite, and Jinbaldite. Among them, biotite, especially biotite, is an insulator that does not carry heat or electricity well. For this reason, Jeong Soon-shin explained that Baegunmo is contained in the bottom of the iron. Baegunmo Gudeuljang, an insulator, does not let out the hot heat below into the room at once. In addition, the thickness of the lower and upper necks of Gudeuljang are different. This is close to a fire-making furnace in the case of the lower neck, so it can get too hot, so use thick stones and apply thick mud here. For this reason, the gudeuljang of the lower neck can store a large amount of heat. Meanwhile, the upper neck's gudeuljang was made thin so that it could heat up quickly. The temperature difference between the lower and upper necks can be reduced as much as possible. This is the same when the room cools down. After the heat supply from the furnace is stopped, the spirits stored in the lower neck are gradually released, and the girdle field of the upper neck does not rapidly cool down due to convection in the whale. As such, ondol is the product of scientific knowledge. What cannot be left out of ondol is a cultural factor. The lower part of the ondol has long been an essential space for the Korean people's The whole family sitting together on the lower neck and sharing affection was an essential factor in maintaining a harmonious family atmosphere. It is a story that often appears in fairy tales that the grandfather sitting on the lower neck grilled sweet potatoes in a furnace and gave them to his grandchildren, and the grandchildren gently fall asleep while begging them to tell another story after the old story. The development of ondol resulted in the finishing of ondol rooms, especially the development of floorboards, and various methods were used to close floorboards during King Yeongjo's reign. Usually, it was common for ondols in private houses to set up dawn and set up a new floor every four or five years. First of all, after the dawn dries up, we first serve with sebum or white paper, and then rub the floor evenly with a strong bowl upside down. On top of that, a window paper is applied again to whiten the background, and then a thick sheet of paper is attached with perilla oil. On this floor, a bean dam (grind soaked soybeans in water into a millstone, put them in a bag, and rub the floor of the room), and when this dries, repeat the dry mop countless times. Choi Soon-woo explained that the floorboard with a woman's sincerity gradually turns into a millet, and conventionally, it becomes like a mirror. When the floor mat is old, the change of the upper and lower muks under the influence of temperature also enhances the atmosphere of the room. These days, the floorboards are the only floorboards, but they also use plastic wallpaper patterns as well as colorful flower floorboards. Although the wave of modernization cannot be blamed blindly, it is comforting that some people insist on traditional floorboards because it is regrettable that the characteristics of Koreans disappear. "Ondol Lost by the Wave of Modernization" The wave of modernization took the lower neck away from us. This is because ondol has turned into an improved ondol with hot water pipes instead of spheres. Depending on the space, a radiator is installed indoors to circulate steam or hot water, or a stove or bechica is installed to heat. The former is called radiant heating and the latter is called convective heating. Convective heating requires that the heated air stays on the ceiling and loses heat outdoors, so it must cover the cold air of the outside air. Moreover, since the air at the heat dissipation site is locally high temperature, it rises rapidly, causing the temperature under the ceiling to be the highest and the floor to be low. In a human standing position, medical experts point out that the head part is high and the feet part is low, which is not good for health. This means that high-temperature air rapidly accelerates the motion speed of oxygen molecules in the air and expands, resulting in a distance between molecules, which eventually reduces the number of oxygen molecules in the cardiopulmonary system. This causes disruption to the human body. In fact, it is also proven that the long-lived area around the world is an area where a large number of oxygen can be supplied from cold places, and the lifespan of tropical people is short. The thermal characteristics of convective heating and ondol heating were explained as follows in Chosun Technology Development History. First, the temperature of the heating surface can be taken low. In the case of convective heating, the temperature of the surface of the heat dissipation surface is usually about 50 degrees, but in the case of ondol heating, the surface temperature is 30 to 35 degrees. Second, when the surface temperature of the ondol is 30°C, heat exchange is about half of the total amount of heat exchange, so it is advantageous to make the comfort temperature of the room. Third, the ondol main room increases the temperature of the room by radiant heat exchange, thereby reducing the amount of heat emitted by radiation from the human body. It means it's hygienically good. Fourth, in ondol heating, an equal room temperature with little difference in indoor up and down temperature is formed except for the floor surface and the ceiling surface. In addition, ondol is a scientific and ideal heating method because the body, including the soles of the feet, directly contacts the ondol and at the same time promotes blood circulation. According to the experiment, the comfort temperature of the room is set to 21 degrees, and in the case of ondol heating, the floor height is maintained at about 50 centimeters to 22 degrees. However, the convective heating method has the advantage of being easier to construct, cheaper to heat, and shorter preheating time compared to radiant heating, so almost all non-bedroom spaces such as the main room are occupied by radiators in houses. When the energy wave hit and energy savings for heating consumption in buildings became a major issue, traditional ondol disappeared and improved ondol began to be supplied. The government has implemented energy-saving policies to improve the insulation and airtightness of residential buildings. As a result, the heating load of each room can be handled with relatively little energy, but the concept of the warmth of the ondol floor, which is naturally thought of as an ondol, disappears. Moreover, they put in the bed while doing panel heating. The bed is even airing an advertisement called Science, not Furniture. They give up the complex advantages of ondol culture and mistake the bed as if it were an advanced life. In other words, residential life in Korea has changed to a form without nationality. However, unlike foreign standing life, we are generally familiar with contact heat by warm floors, so even if the indoor temperature is in a pleasant range, we do not get satisfaction if the temperature of the floor surface is low. It is a general view that the floor of the room is very good for health to make a temperature difference as much as possible. Scholars point out that children these days often suffer from residual diseases because they live a centralized heating life such as apartments with little temperature difference. As a supplement to these shortcomings, there is also a method of adopting a latent heat storage material that can feel warmth for a long time. I compared and reviewed the heat dissipation effect after installing calcium chloride hexahydrate (CaCl2·6H2O) with a phase change temperature of 29.7 degrees evenly in ondol panels and hot water ondol. According to experimental results, when the latent heat storage material is not added, the latent heat storage material is overheated, but when the latent heat storage material is added, overheating may be prevented and warmth may be felt for a long time due to natural heat dissipation. Moreover, in this case, the heating rate can also be reduced by about 15%. On the other hand, there is also a partial heating method that partially increases the entire ondol floor without heating it to a constant temperature to perform "warm floor" heating adapted to our custom. This method allows the floor temperature required by the resident to be obtained by adjusting the area of the heat dissipation surface. Even though it is a so-called pipe ondol, it artificially creates the upper and lower necks. According to an experiment by Professor Son Jang-yeol of Hanyang University, it can be seen that in the case of partial heating, the indoor heating environment is different from that of all heating. The range of the comfortable floor temperature of the human body is about 31-35 degrees, but it can be seen that the temperature is lower than the comfortable floor temperature felt by the human body as it is about 28 degrees when the entire heating is performed. Therefore, in order to maintain the floor temperature as a comfortable heating temperature, it is rather effective to perform partial heating instead of overall heating. In this case, even if the heating ratio is reduced by 10%, the floor temperature of about 3 degrees can be increased, so the effect of killing two birds with one stone is obtained. Small electric blankets are being sold at department stores in the United States under the name of Mini Ondol. It is a so-called hit product with General Electric, a great maker. France's National Institute of Science and Technology (CNRS) is also studying ondol as part of energy conservation. This is because the use of ondol saves more than 20% of energy than the forced ventilation heating method used in standing-up life.