신기한 사실, 상식

A refrigerator is a device that cools its interior by removing heat from food. A substance called a refrigerant circulates inside the refrigerator, and heat is transferred through the process of this refrigerant changing its state. First, the refrigerant absorbs heat from its surroundings in the evaporator inside the refrigerator and turns into a gas. It then passes through the compressor, increasing its pressure and temperature. In the condenser on the outside, it releases heat to the surrounding air and returns to a state close to liquid. After passing through the expansion device, its pressure drops, lowering the refrigerant's temperature, and it's ready to absorb heat from the inside again. This process repeats, keeping the inside of the refrigerator cool. The warm air coming out from the back or bottom of the refrigerator is because it's releasing the heat taken from the inside. A refrigerator isn't just a machine that makes cold air; it's a device that moves heat from one place to another. Frequently opening the door or putting in a lot of hot food can raise the internal temperature, making the cooling process take longer.

The daily lives of people in the Joseon Dynasty varied greatly depending on their social status and occupation. Farmers would head to their fields at sunrise to work the land, with their tasks changing according to the season. Merchants went to the market to buy and sell goods, while artisans used their skills to craft various items. The yangban class focused on studying or preparing for official positions. At home, families ate and lived together, and since there were no bright electric lights like today, they often went to bed early at night. Time was told using the sun's position, water clocks, or sundials. In winter, ondol (underfloor heating) was used to endure the cold, and in summer, people sought relief from the heat by feeling the breeze on the wooden floors (maru). While clothing, food, and living spaces differed by social class, a commonality was living in accordance with the changing seasons. These lifestyles were quite different from modern times, yet they shared similarities with today in terms of living together with family and neighbors and working according to the seasons.

Hangeul is the script used by Koreans, created by King Sejong the Great for the benefit of his people. During the Joseon Dynasty, literacy was limited to a select few, and many commoners struggled to learn the complex Chinese characters. King Sejong sought to resolve this inconvenience by creating a new writing system. The fundamental principles of Hangeul were completed in 1443, and it was promulgated to the world under the name "Hunminjeongeum" in 1446. A key characteristic of Hangeul is that its consonants and vowels were created based on a consistent principle. The consonants were designed by imitating the shapes of the mouth and throat during pronunciation, while the vowels originated from the basic principles representing heaven, earth, and humanity. Because letters are combined to form syllables, Hangeul is convenient to learn and use. Today, Hangeul is the primary script for recording the Korean language and is regarded as an important cultural heritage that connects our language and culture. Hangeul continues to be used today as a vital script for recording our thoughts and culture. It is widely used even now.

If you wash your face by filling a basin or sink with water, definitely read this post!!! I also used to do it as written above, but then I realized when I saw the water I was about to use for rinsing...! Thinking I was about to reach out with my hand to apply the soapy water, which was made by rinsing my face once!! As an alternative method, from now on, I turn on the water to wet my face and soap, then turn it off and rub my face, then turn on the water again to catch it in my hands and use fresh water that hasn't touched the sink!!! (If you rinse 4 times, including the initial wetting, you'll use fresh water in your hands 5 times!) However, if I turn the water on full blast, the water bill might be significant, so I turn it on a.. a.. trickle.. and use the fresh water caught in my hands. Later, to check the water usage, I closed the sink drain and even after finishing my trickle.. trickle.. trickle.. face wash, the collected water was less than a third of the sink. (If you plan to wash your face the way I do with a trickle.. trickle.. trickle.., try checking your water usage like I did. Everyone's standards are different, and what feels like a trickle.. trickle.. trickle.. can also vary.)

After it rains and the sun shines, beautiful rainbows sometimes appear in the sky. Rainbows are formed through the process of light refracting and reflecting when sunlight meets raindrops. Although sunlight appears to be made of a single color, it's actually a mixture of various colors. When sunlight enters a water droplet, refraction occurs, changing the direction of light. After reflecting once inside the droplet, it exits, causing the colors to separate. Because each color of light refracts slightly differently, the various colors spread out in different directions. In the rainbows we commonly see, colors appear in the order of red, orange, yellow, green, blue, indigo, and violet. Rainbows also depend on the positions of the sun and the observer, so they can't be seen just anywhere. Generally, you need the right conditions where it's raining and the sunlight is shining from the appropriate direction. It's fascinating that scientific principles like refraction and reflection of light are hidden within something as ordinary as a rainbow.

Chuseok is one of Korea's representative holidays, celebrated on the 15th day of the 8th lunar month. Historically, when grains and fruits ripened in autumn, people held ancestral rites to express gratitude and shared food with their families. The customs of making songpyeon (rice cakes), visiting ancestral graves, and gathering with relatives have been passed down through generations. Songpyeon, in particular, is a representative Chuseok dish made with newly harvested rice and various ingredients. While the way people celebrate Chuseok has changed with the times, the meaning of gathering with family to welcome the abundant autumn and wish each other well seems to have endured. Learning about the origin of this holiday, which I didn't know much about before, makes Chuseok feel a bit more meaningful.

Western music has evolved in various forms, influenced by society and culture throughout different eras. In ancient times, music was used for religion, education, and performances, with Greece notably considering music a vital academic discipline. During the Middle Ages, the Church's influence grew, making Gregorian chants and other monophonic religious music central. The Renaissance saw the development of polyphonic music, where multiple voice parts harmonize, and secular music also flourished. The Baroque era is characterized by ornate decorations and strong contrasts, featuring composers like Bach and Handel. The Classical period emphasized balance and form, with Haydn, Mozart, and Beethoven as key figures. The Romantic era highlighted individual emotions and free expression, with Chopin and Liszt being prominent. From the 20th century onwards, new musical forms emerged, breaking away from traditional tonality and structures, leading to the development of diverse genres like jazz and electronic music.

The official term for sleep paralysis is 'sleep paralysis'. During REM sleep, where most dreaming occurs, the brain inhibits the movement of skeletal muscles to prevent us from acting out our dreams. However, when you wake up and your consciousness returns before your body's paralysis wears off, you find yourself in a state where your mind is awake but your body cannot move. At this time, dream images or sounds from REM sleep can overlap with reality, leading to hallucinations of figures, shadows, or voices. When the terror of being unable to move is added, the brain might interpret ambiguous stimuli as 'someone being in the room.' This is why some people report seeing a person standing by their bed or feeling a weight on their chest. What's more interesting is that the appearance of entities during sleep paralysis can vary by culture. In some places, they are described as ghosts or spirits, while in others, they are depicted as monsters or intruders. Even the same sleep phenomenon can be influenced by an individual's memories and cultural imagery in shaping the experience.

Frida Kahlo is a representative Mexican painter, well-known for her self-portraits that honestly express her life and emotions. Born in Mexico in 1907, Kahlo suffered from health problems from a young age and began painting after experiencing a major accident. These experiences greatly influenced her later works. Kahlo's paintings often feature not only her own image but also themes of pain, love, family, Mexican traditional culture, and nature. Her work is particularly characterized by intense colors, symbolic imagery, and unique self-portraiture. Notable works include "The Two Fridas" and "The Broken Column." Frida Kahlo didn't just paint her own image; she poured her experiences and emotions into her art. That's why looking at her paintings allows you to feel her life and thoughts at the time, which is impressive. She remains a painter remembered by many for her unique artistic world and strong personality to this day.

Ganggangsullae is a representative traditional folk game and song of Korea, a culture that has been enjoyed especially during holidays like Chuseok. It is typically performed by women holding hands, forming a circle, and singing while dancing or playing various games together. Ganggangsullae has been passed down mainly in the coastal regions of Jeollanam-do and was often performed on bright moonlit nights, such as during Jeongwol Daeboreum or Chuseok. Depending on the tempo of the song, participants might walk slowly and then gradually speed up, or mix in various movements and games. Beyond being a simple game, Ganggangsullae also holds the meaning of gathering with people and fostering community harmony. It was designated as a National Intangible Cultural Property in 1966 and was inscribed on the UNESCO Representative List of the Intangible Cultural Heritage of Humanity in 2009. It seems to be even more meaningful as a traditional Korean culture that has been passed down for a long time. Even today, one can experience Ganggangsullae through performances or traditional cultural events.