Brilliant LeaderShip

Ambition Highly Encouraged

On June 6th, Juche 101(2012), the respected fatherly Marshal Kim Jong Un attended the joint national meeting of the Korean Children’s Union organizations in celebration of the 66th founding anniversary of the ...

Orphans Should Cut Inaugural Tape

One day in a June, the respected Comrade Kim Jong Un visited Wonsan Baby Home, which was nearing completion. Absolutely delighted with the best home in the world to present to the ...

What was Never Admitted

In the late 1990s, innumerable letters were sent to the Central Committee of the Workers' Party of Korea from the service personnel and people who were earnestly longing for erecting the bronze ...

Even in the Days of Fatherland Liberation War

It happened during the past Fatherland Liberation War. On the way to the front, President Kim Il Sung found himself looking for a while at the mountains packed with trees in a county. ...

Play Areas in Department Store

There are some excellent indoor play areas for children at Pyongyang Children’s Department Store. Those picturesque play areas that look like a paradise in a fairy tale remind us of one day ...

Mirae Scientists Street

One day in May, Juche 103(2014), the respected Comrade Kim Jong Un visited the construction site of apartment houses for lecturers of Kim Chaek University of Technology. Looking around almost every corner of ...

News

Jo Jun 20, 2024

Addition of Zn element into CdS improves the short circuit current density and open circuit voltage to increase the efficiency of hetero-junction based solar cells such as CdTe and CIGS, decreasing the absorption losses of the window materials in p-n junction devices and the lattice mismatch.

Over the past three decades, there have been a number of reports on the deposition and properties of Cd1-xZnxS ternary compound with a various range of Zn concentration (low Zn content, midst content and overall Zn content), using different methods like chemical bath deposition, spray pyrolysis, SILAR, vacuum evaporation, MOCVD, RF sputtering, vapor zinc chloride treatment, etc.

Ki Tong Hun, a student at the Faculty of Electronics, has deposited Cd1-xZnxS thin films (0<x<1) by the CBD method and investigated the influence of Zn content on the structural, morphological, optical and electrical properties of films by using XRD, SEM, UV-VIS spectroscopy and other analysis instruments.

The analysis results can be summarized as follows;

XRD studies revealed that the crystal phase of Cd1-xZnxS thin film changed from the hexagonal to hexagonal/cubic mixed phase at lower Zn contents, and then transformed to cubic ZnS phase as Zn content further increased.

Through the SEM measurements, he could observe certain-sized granules formed by the agglutination of Cd and Zn compounds around the nucleus due to the absorption of Cd2+ and Zn2+ ions with initial increase of Zn concentration. On the other hand, for the Zn content greater than 0.6, Cd1-xZnxS particle size decreased and the mixture phase in thin film became stable.

For further details, please refer to his paper “Investigation on the influence of Zn content on the structural, optical, morphological and electrical properties of ternary compound Cd1-xZnxS window layer for CdTe solar cell” in “Functional Materials Letters” (SCI).

...

Jo Jun 17, 2024

Redox flow battery (RFB) has been developed in popularity since 1970s and become a promising large-scale energy storage system recently. RFB is an electrochemical device that stores and releases energy through redox reactions of active ion species in electrolyte. The main advantage of RFB over other electrochemical devices such as lead acid battery and lithium ion battery is that the power system could be made very flexible because of the independence of its power from its energy and that its cost per energy in high-capacity systems is particularly low. The drawback is that the ion selective membrane for these RFBs is very expensive and it should satisfy very strict requirements for several aspects including ion selectivity, electric conductivity and chemical stability.

This has led to the recent trend of not using membranes. The advantage of the soluble lead flow battery is the absence of a membrane because only one electrolyte is used.

Kim Ju Song, a researcher at the Faculty of Chemistry, has suggested lead fluoroborate dissolved in aqueous solution of fluoroboric acid as electrolyte of SLFB and investigated the electrochemical characteristics. He chose paste of waste lead acid batteries as a source of lead and investigated its effects on the performance of electrolyte.

The results are as follows.

The conductivity of 1.5 mol/L electrolyte prepared with recycled lead has a peak when the concentration of HBF4 is less than 1.0 mol/L. The kinetic characteristics of Pb2+/Pb and Pb2+/PbO2 are almost the same in both reagent grade lead and recycled lead electrolytes. When electrolytes prepared from recycled lead are used, the average charging efficiency and the average voltage efficiency are all shown to be superior to those of methanesulfonic acid cells.

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Students on “Risang” Local Network (1)

“Risang”, homepage for distance education of Kim Chaek University of Technology, has been making the part-time learners realize their ideal to the full.

Nov 11, 2022