Ri Jang Son, inventor of the time bomb

Ri Jang Son was an engineer of the 16th century who invented and made a powerful shell during the Imjin Patriotic War.

He was in a low social position as a handicraftsman who made a fire gun and so he was held in contempt by the feudal rulers.

With a strong sense of patriotism, he had made every effort to produce a powerful weapon capable of dealing a heavy blow to the Japanese aggressors.

At last, during the Imjin Patriotic War, he succeeded in inventing and manufacturing a more powerful shell - Pikyokjinchonroe by improving the Jinchonroe of which use was limited before then.

There were three types of Pikyokjinchonroes: extra big, big and medium. Pikyokjinchonroes were fired by cannons such as extra big Wangu, big Wangu and medium Wangu, ranging about 750 to 900 m.

The shell was a time bomb with a fuse. It was a time bomb that either accelerated or slowed down the time of the explosion depending on the number of screw grooves (the length of the fuse).

The enemy, without knowing the principle of the shells, gathered to see the shells which had been flown from a distance, and were hit hard to wholesale death by steel fragments when they were explored with loud explosion sound.

Like this, Ri Jang Son invented a new weapon, thus making a great contribution to the victory of the then Imjin Patriotic War.

Great Wall of Koryo

The Great Wall of Koryo was the important military facility for defending the northern part of the country.

The building of great wall of a thousand ri was aimed to protect the sovereignty of the country and nation from the invasion by foreign aggressors by setting up more durable and durable defensive facilities in the northern part of the country, as the aggressor forces in the north were constantly watching for an opportunity of aggression.

It was built with either stone or earth to suit the topography of the area where the walls passed. Outside building method was adopted mainly in mountainous areas, and double sides’ building method was adopted in the plain areas. The walls in the mountain areas were built along the high and steep peaks and ridges with an elevation of 830-930 m above sea level.

It was also noteworthy that large rivers had been used effectively to enhance the defensive power of walls. In some places, the walls were built on high cliffs and steep hills by the riverbanks and, and the logs were driven into the water in order to prevent the passage of ships in the legs of the rivers or lakes where the walls crossed.

Characteristics of Korean Folk Games

First of all, the content and method of folk games are sound and cultured. This is because the Korean folk games reflect the noble and civilized life and sound and optimistic way of life of Korean nation which entered the era of civilization in its early years. That the content and method of folk games are sound and cultured, means that most of them are composed of those that help children to train their physical strength and develop their intelligence and satisfy the demands of cheerful and interesting emotional and recreational games, thus making a substantial contribution to their cultural and emotional lives.

Games such as hide-and-seek, watermelon picking, tail-picking, shuttlecock kicking, sleigh-riding and playing with dolls help everyone to cooperate in harmony, understand what the collective is, know what the strength of unity and harmony is, and experience the emotions of the juvenile mind to the full.

Secondly, there are large number of various plays, and everyone can learn easily and enjoy themselves. The Korean folk games are diverse and are characterized by the fact that everyone can learn easily and enjoy themselves. In yut-game, for example, everyone from children to adults can learn easily and enjoy themselves. This kind of plays includes wood splint counting play, shadow playing, scissors-paper-rock playing, and ball kicking.

Thirdly, a considerable number of games were created by taking into account the scientific principles of natural phenomena. Our people have created many folk games taking into account the principles of natural phenomena. Kite-flying using the force of the wind blowing in autumn and winter, sleigh-riding on the ice or snow in winter, top spinning, swinging using the elasticity of the string and the centrifugal force, rope skipping, shuttlecock kicking using the principle of the object falling in the air, and the likes had been created from the scientific principles of natural phenomena.

Lastly, all the games are cheerful, optimistic and emotional.

Astronomical and meteorological instruments in the 15th century

The talented and intelligent Korean people made and used astronomical and meteorological observation instruments on a high level in the 15th century on the basis of the scientific and technological achievements in the preceding periods.

Typical instruments were Kanui(instrument to observe the astronomical phenomena), Honchonui(instrument to observe the or bit of the heavenly bodies), Angbuilku(sundial), and udometer.

Kanui was an instrument for measuring the horizontal coordinates, equatorial coordinates of the heavenly bodies, and time, and it was made by Richon, Jang Yong Sil, etc. in 1432. The original instrument was made of wood and then made of copper elaborately, which was called Big Kanui. In 1434, Ri Chon, Jongcho, Jonglinji and others made a smaller Kanui, knowing that Big Kanui was heavy and inconvenient for the actual observation. This was called Small Kanui.

Kanui was a typical observation instrument showing the development of the astronomical meteorological observation technique of the Korean prople, as it also depends on the instrument measuring the height and azimuth of the heavenly body.

In the 15th century, Honchonui was also invented, and it was an astronomical observatory instrument to measure astronomical values, including the positions of heavenly bodies. The astronomical values which were measured by this metallic instrument are almost similar to those used in astronomy today. A typical example is that the intersection angle of the ecliptic plane and the equatorial plane was set to 24°.

Angbuilgu was made of copper or brass. The structure of this instrument is as follows: there stands a guide pole at the bottom of the dome, and the sight line and the season line are drawn. People can guess the time and the season according to the movement of the pole’s shadow in the instrument. Angbuilgu was the more complete and accurate form of sundial than the sundial with a flat shadow plate. This was because the celestial sphere was reduced to a small spherical shape, and hence there was little error.

The udometer had made its first appearance as the first rainfall measurement instrument in the world. In 1441, a round box-shaped metallic udometer was firstly made, and then it was remade several times. In the local areas, the udometers were made of ceramic or earthenware, were placed in the courts of the government public offices, and were used to measure the raining time and quantity when it rained.

Treatment of brain diseases using ultrasound

Researchers in a country have reportedly succeeded in injecting drugs into the brain using ultrasound.

In general, it is difficult to inject drugs into the brain. The brain has a blood-brain barrier, which is responsible for the reliable protection of the central nervous system from microorganisms and toxins circulating along the blood.

However, this blood-brain barrier prevents drug penetration, which is a challenge for the treatment of diseases. This is particularly urgent matter for the treatment of glioblastoma and other kinds of brain cancer that require chemotherapy.

Based on the study of the properties of weak ultrasound, researchers thought if this might help to treat brain cancer. Researchers have installed a small instrument that produces weak ultrasound in the the patients’ skull by surgery. One to two weeks later, researchers started to operate the device and inject microcapsules into the patient's blood.

The results demonstrated that the blood-brain barrier was temporarily opened by the action of weak ultrasound, and that drugs in microcapsules could penetrate the brain.

Bean paste soup in breakfast good for the removal of toxins

Bean paste is a favourite basic food of the Korean people. It contains proteins, carbohydrates, lipids, minerals and vitamins, and amino acids that people need to take.

In particular, bean paste soup in breakfast is a good food for removing body toxins. The ingredients in the bean paste are reponsible to wash the fat and remove the bacteria left in the intestine. Lecithin in bean paste melts extra fat in the body and the fiber is used to clean the intestine. The vitamins in bean paste also remove the toxic components of nicotine.