Jo Nov 21, 2022
Chlorination leaching, one of non-cyanidation processes, which was in use until the end of 19th century after its development in the middle of the 19th century, was deprecated after the cyanidation process was born. However, in the eighties of the 20th century it was found that chlorination leaching had a good effect on fine grains of gold ores, and researchers’ interest in it revived, leading to some successes.
Compared to cyanidation leaching, chlorination leaching of gold by chlorine or hypochlorite has faster gold leaching rate and less pollution. What is more, it is cheaper and simpler.
Kim Chang Sok, a researcher at the Science Engineering Institute, has conducted thermodynamic and experimental research on chlorination leaching of refractory gold concentrates. Then, he has observed the influence of the redox potential on gold leaching and confirmed reasonable conditions for the potential.
The results demonstrate that for a higher leaching rate of gold, leaching time should be more than two hours and redox potential should be controlled at 1.0V or more. Under the conditions of the initial concentration of active chlorine 0.5%, the value of pH 4.0, the leaching time at least two hours and the redox potential more than 1.0V, the leaching rate of gold could reach over 96%.
You can find more information about this in his paper “Research on Chlorination Leaching of Pressure Oxidized Refractory Gold Concentrate” presented to the SCI Journal “Hydrometallurgy”.
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Jo Nov 20, 2022
An apron is one of the things that show well a good living habit of Korean women, who have always loved smartness.
An apron is a piece of clothing that women wear over the front of the body and tie around the waist when cooking.
The custom of wearing an apron in our country has a very long history. Maids wearing semi-oval aprons are painted on the mural paintings in Kamsin Tomb and Anak Tomb No. 2 of Koguryo, which tells us that aprons started to be used already in our country before the period of the Three Kingdoms. As shown in the murals, aprons of that time were similar in shape to present-day aprons. They were made in different colours including white and light pink, and red or pink strips of cloth were sewn around them. The custom was inherited down to the feudal Joson dynasty, when aprons made of four pieces of cotton cloth in pleats were almost similar to skirts in length, and they were worn over skirts to cover the front as well as the sides of the body. Among the aprons that had been passed down from olden times was “Haengju Apron” named after the patriotic deeds of the women in the fortress on Mt. Haengju, who carried stones in their aprons to assist the warriors in the battle against Japanese invaders during the Japanese invasion of Korea in 1592.
Aprons were made of thin white cotton cloth such as cotton or calico and they were always washed, starched and ironed before use.
It is a fine custom of our women to wear smart aprons whenever working ― cooking in particular. It was a normal practice for our women to wear aprons when serving food to guests as well as preparing meals for the family in the mornings and evenings, and it was regarded as common courtesy to take them off when they need to enter rooms or answer the door in the middle of cooking. In a word, aprons served as an important symbol of the aesthetic feelings of our women, who have loved neatness and cleanliness from early days.
Today our women enjoy wearing aprons when they do the housework. Present-day aprons that are made of white cloth in semi-oval or rectangular shape to cover front parts only are decorated with simple flower embroidery, applique, lace or small pockets.
Pak Sin Jong, researcher at the Academy of Social Sciences
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Jo Nov 17, 2022
Several works have revealed the inclusion properties between the Orlicz spaces, which are complicated in the proof process and very difficult to apply.
Kim Jin Ju, a lecturer at the Faculty of Applied Mathmatics, has formulated a necessary and sufficient condition for the existence of inclusion properties between weighted and weighted weak Orlicz spaces, which is a more generalized space than an Orlicz space, using the characteristic function of a sphere.
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Jo Nov 16, 2022
Not only the style and pattern but also the colour of clothing represent features of times and national sentiments. The colours of the traditional clothing of our nation fully display the lofty and pure sentiments of our nation. Our nation preferred white or light soft vivid colours to strong colours for primary colours of their clothing. From olden times, our nation worshipped white and usually chose white for their clothing. Therefore, our nation has been called “white-clad race” or “white-clad folk”.
In addition to white, many bright colours like light yellow, light pink or light green were also popular. With light soft colours instead of harsh strong ones, our people managed to produce a good harmony of colours, adorning Korean clothes to look more beautiful. Since Korean clothes are usually in two pieces, upper and lower garments in harmony of colours give fresh feelings and beauty. Making the most use of such advantage, our people added as much beauty as possible to the Korean clothes with a colourful harmony of two pieces as in “green jacket and crimson skirt” or “yellow jacket and crimson skirt”. Korean people further raised the ornamental effect of Korean clothes by making their small parts such as gussets, collars, cuffs, coat strings, etc. different in colours from the main part. This combination of colours demonstrated the great aesthetic sense of our nation whereby they could get maximum effect by making effective use of visual aspects of the harmony of only a few colours.
The colours of the Korean clothing reflective of the aesthetic sense and feelings of the Koreans, who created bright and soft beauty, are still in wide use. Our clothes are undergoing development as unique, graceful and elegant ones full of the flavor and fragrance of our nation only.
Pak Sin Jong, researcher at the Academy of Social Sciences
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Jo Nov 15, 2022
There may be potential flaws in the whole process of quality formation. The time and expenditure for their control are different according to when they are detected.
Many people found one famous principle while they were summing up their quality management. That is the Law of Ratio 1:10:100.
It means that it takes an hour and 1 won to manage a flaw of quality at the stage of development and design, 10 hours and 10 won at the stage of production, and 100 hours and 100 won at the stage of marketing. That is to say, plan: production: marketing = 1:10:100.
Kang In Song, an institute head at the Faculty of Management of Industrial Economy, has formulated 6 types related to the time of flaw detection and rectification and analyzed the influences of each type on customer satisfaction, time and cost.
Type 1-4: stages of development and design, design examination, production, and test, respectively. In each stage, quality flaws are found and controlled.
Type 5 and 6: stages when quality flaws have been transferred to customers. Type 5 gives priority to troubleshooting and maintenance and also employs refund or exchange of goods. Type 6 is when quality flaws transferred to customers cannot be controlled by enterprises.
Enterprises can choose one of these types to manage quality flaws.
The effects on customer satisfaction, time and cost are:
The enterprise which agrees to Type 1 might make the best choice by giving great satisfaction to the customers and ensuring minimum time and cost. It guarantees preventive management of quality. This enterprise can be said to have quality management level of 6σ.
Any enterprise in favor of Type 2 may give basic satisfaction to the customers and control flaws with comparatively short time and low cost. It has quality management level of 5σ. Its drawback is relative – it is not preventive but has pursuit property and delays the time of starting production.
An enterprise whose quality management goal is Type 3 may have the following advantages. It is preventive and gives partial satisfaction to the demand of the customers. It might ensure production and supply in good time and save a lot of money for equal and continuous improvement even if it needs 10 times as much expenditure. It might have quality management level of 4σ.
An enterprise in favor of Type 4 may not have good points by and large but flaws are not transferred to the customers. It might have quality management level of 3σ. It is not preventive but has pursuit property. It does not satisfy customers’ requirement but ask them for its quality level. It might delay supply and need 10 times its expenditure, in particular in the last stage.
The enterprise in Type 5 might not have good points but if any, it is responsible for flaws and takes measures even though they have already been transferred to the customers. It has quality management level of 2σ. It might always deal with the customers to fix exchange or refund the goods. It has a problem of whom to allocate extra pay – the enterprise or the customers. It might need time for fixing and servicemen and equipment for it.
Any enterprise in Type 6 may have decreased income and legal problems. It might injure its reputation, causing a lot of loss and hardly managing its own business, as flaws are transferred to customers, which makes them disappointed. It is on the verge of bankruptcy. Its quality management level is 1σ.
The 6 types mentioned above let us aware of different effects on customer’s satisfaction, time and cost.
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