Jo Dec 20, 2022
Kim Jang Hak, a section head at the Faculty of Distance Education, has proposed a new learning content model and a communication interface with interactivity and feedback structure considering the requirements and levels of learners while meeting the pedagogical requirements for distance education.
Generally, distance education system consists of three components, namely, learner, learning content and learning management system.
Learning-based interaction is mainly of three types, i.e. learner-content, content-management system and learner-management system.
Learning content consists of a content object and an interaction object with communication interface. The content object is Sharable Content Object (SCO) for teaching activities like lecture, experiment, practice, etc. The interface object is for interaction with learners through the communication interface and standardized communication with the management system.
If the structure of content is properly defined and standardized for interaction and feedback control, the reusability, extension and inter-operability of content can be ensured and it can be used in other management systems. The design of the content in hierarchical structure allows reuse of some of the content object in other contents.
On the basis of SCORM, the content model and learning object metadata are defined in the figure above. In the figure, “organization” is a learning unit and “item” is learning resources. “Resource” is a reference set, that is, SCO or asset of minimum unit. The root folder of the content has index.html, imsmanifest.xml, XSD and DTD, metadata.xml and resources. The content model is in imsmanifest.xml and metadata files.
Finally, he managed to form the content by adding communication interface with four control objects for interactivity and feedback control to the content model in hierarchical structure. The communication interface is made up of display control object, learning control object, communication control object and evaluation control object.
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Jo Dec 18, 2022
There is a man who has amused and pleased everyone for hundreds of years only with his sleeping posture. It is a figure in the picture “Draught Ox Driver” by painter Kim Tu Ryang (1696-1763) during the feudal Joson dynasty.
The picture gives a lifelike portrayal of a draught ox driver who has fallen into a deep sleep under the shadow after all day’s tiring work. In the middle of the picture is painted a big ox and on the right is an ox driver fast asleep on the grass, which gives a glimpse into the country life in our country at that time. The ox driver in the nap in the shadow of the summer is portrayed in a simple and plain way. The thick untrimmed hair, firmly closed lips, dangling earlobes, raised corners of the eyes, undone front of the jacket and untied cord of the trousers are so impressive. The ox chewing the grass in the middle shows the gentleness and strength of Korean oxen and the neatness of the owner who values and takes good care of it. The surroundings like the bottom of the willow, the drooping branches and the grass feel as if they were emitting the fragrance of soil.
Well-composed and soft with thin coloring, the painting is an excellent masterpiece in the aspect of portrayal of that time. On the one hand, it looks as if you can hear cicadas and other insects buzzing and the farmer snoring, and the ox driver, on the other hand, looks so fast asleep that nobody would be willing to awaken him.
In a word, the painting “Draught Ox Driver” by Kim Tu Ryang exhibited in the Korean Art Gallery is a masterpiece that has stimulated extraordinary interest of a lot of people for hundreds of years only with a sleeping figure.
Jo Hwi Nam, section head at the Academy of Social Sciences
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Jo Dec 16, 2022
A research team led by Kim Tok Su, head of the Electric Power System Institute, and Mun Yong Guk, a section head at the same institute, has developed a flow meter which measures flow in real time in hydropower plants by using Winter Kennedy method.
Winter-Kennedy method utilizes a static pressure difference between the outside and the inside of a turbine spiral due to the centrifugal force acting on the curved streams of liquid in the spiral case.
The flow calculation formula in the flow meter using Winter Kennedy is Q=khn, where K is a constant coefficient and n is a power exponent which is theoretically equal to 0.5, but could be chosen between 0.48~0.51.
Generally, the values of the constant K can be determined experimentally by using flow Q measured by other standard flow meter. However, they have established a method of determining the coefficient K through FLUENT simulation.
They have introduced and examined the proposed flow meter in a generator. The result was n=0.497 9, K=0.057 and the maximum error compared with a standard flow meter was 0.616%.
As this simulation method is helpful to estimate power exponents and flow coefficients for any spiral cases, the flow meter can be used for all hydro power plants with a spiral case. It is simple in installation and it does not disturb fluid flow. Moreover, real-time measurement is possible with low cost but high accuracy.
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Jo Dec 15, 2022
Production systems operated in practice consist of repairable components and such systems may mostly be modeled as a direct-parallel system. Thus, analysis of the reliability characteristics of a direct-cold standby system is important in the reliability analysis of the system.
Most of the components for a repairable system are not the same after repair as new ones and component’s lifetime decreases with the increase in the time of use. What is more, the time for repair increases more and more once they stop working, which finally leads to complete failure.
On the assumption that the lifetime and repair time of components follow a geometric process, Kim Man Su, a lecturer at the Faculty of Applied Mathematics, has studied the reliability of several dual series direct-parallel systems in consideration of such decrepitude.
The figure above shows a state transition graph of a system, where a circle stands for in operation and a square means break down.
It is assumed that the system consists of components 1, 2 and 3, and components 2 and 3 make up a dual cold standby system, which is then connected with component 1 directly. Here, component 1 gets priority in repair. There is a repairman. Components 2 and 3 are repaired in order of failure.
The system is a unidirectional closed dual series cold standby system. It means if component 1 fails, the system breaks down.
At the beginning, three components are all new, and components 1 and 2 are in operation and component 3 is under cold standby. When the three components in the system are in good condition, two are in operation and one is under cold standby. The repairman sets to work once one of them fails. At the same time, the standby one begins to work. When the failed one has been repaired, it is put on cold standby until the next failure. If one fails while the other is still under repair, it must wait for repair and the system breaks down. It is assumed that each component after repair is not ‘as good as a new one’.
A deteriorative repairable system will not support constant repair of its components. For a deteriorative repairable system, it seems more reasonable to assume that the successive working time of the system after repair will become shorter and shorter while the consecutive repair time of the system after failure will get longer and longer. Ultimately, it cannot work any longer, nor can it be repaired.
In a dual series cold standby system, after N cycle of component 2, when it finishes working, a plan to replace it with a new one (the same as the first dual series cold standby system) is called N replacement policy.
If the lifetime and repair time of components follow a geometric process in a unidirectional closed dual series cold standby system, the solution of state probability (density) is difficult to present analytically, so replacement cycle N needs to be defined and the characteristics of the system be analyzed.
In order to determine an effective replacement cycle, he studied the stationary conditions of the unidirectional closed system using the transitive property of the Markov chain assuming every state in all possible cases in the system.
The results showed that the proposed mathematical method could be effectively used in different pieces of research of other kinds of queuing models.
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Jo Dec 14, 2022
Hoejang jogori is a piece of clothing whose collar, breast-tie, cuffs and armholes are decorated with strips of cloth different in color from the ground.
Our people have sewn strips of cloth in different colors onto collars, hems, cuffs, etc. over a long period of time. Sewing colored strips for trimming originated from the need to keep their clothes clean by replacing colored pieces of cloth on the easy-to-get-dirty parts as often as they could. Later, the strips developed into a means of adornment, adding beauty to the Korean jackets.
The Korean jacket with colorful strips was divided into two kinds ― samhoejang jogori (those with strips on the collar, armholes and cuffs) and panhoejang jogori (those with strips on one or two parts of them). Samhoejang jogori was usually worn by young ladies as formal clothes for wedding, while panhoejang jogori was worn by the middle-aged. For its elegance, women loved being dressed in it, not just on formal occasions or holidays but for everyday life.
Hoejang jogori is still popular with the Korean women for its smartness and gorgeous harmony of colors.
Pak Sin Jong, researcher at the Academy of Social Sciences
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Jo Dec 12, 2022
According to the characteristics of the subject with geographic objects and phenomena as the main study, Kim Un Hyok, a researcher at the Faculty of Earth Science and Technology, has introduced virtual reality technology to raise the effectiveness of teaching.
The most typical application of virtual reality in geospatial information science is a virtual globe. It is a globe that has digitized information of the earth and all things happening on it.
The virtual globe is a fine tool that enables people to learn about the earth, the world and people’s everyday life. If it is in effective use in geographic information system, it will prove to be helpful to attain teaching aims.
Unlike the past days when he used to give basic knowledge such as definitions and concepts before going into the main point, he showed a virtual globe first to make his students discuss collection and management, edition, analysis and output of geographic information. In other words, he converted his lecture into a question and answer session and let them make virtual visual aids including a virtual globe on their own.
As a result, he could ensure high teaching density and at the same time guide them to give a full play to their abilities for enquiry, design and creation.
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