Pyongyang, North Korea
Pyongyang, North Korea

Kim Il-sung University, founded on 1 October 1946, is the first university built in North Korea. It is located on a 15 hectare campus in Pyongyang, the nation's capital. Along with the main academic buildings, the campus contains 10 separate offices, 50 laboratories, libraries, museums, a printing press, an R&D centre, dormitories and a hospital. The university is named in honor of Kim Il-sung, the founder of the Democratic People's Republic of Korea. Courses in the department of social science take 5 years, while those of the department of natural science take 6 years to complete. Wikipedia.

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Yun J.N.,Shanghai JiaoTong University | Yun J.N.,Kim Il Sung University | Su J.,Shanghai JiaoTong University | Su J.,Key Laboratory of System Control and Information Processing | And 2 more authors.
IEEE Transactions on Industrial Electronics | Year: 2013

This paper proposes a method for designing disturbance observer (DOB) in vibration suppression control of two-inertia system. The key to a vibration suppression control of two-inertia system is eliminating the effect of vibration modes of the plant. For this purpose, feedback controller is designed to cancel the stable vibration modes of plant. However, this cancellation fails due to model error from parameter variations. In this paper, the DOB is employed to compensate for the effect of parameter variations. The Q-filter of DOB is designed with the following specifications: optimal disturbance suppression performance with restricted cutoff frequency; robust stability of closed-loop system against modeling error between the plant and its nominal model; structural restriction of Q-filter itself such as relative order and internal model order. This paper proposes a systematic and straightforward method to attain the above design specifications using standard H\infty control framework. Experimental results verify that the proposed DOB can improve the transient response and effectively suppress the vibration and improve external disturbance removing performance as well. © 1982-2012 IEEE.

Kim N.-C.,Wuhan University | Kim N.-C.,Kim Il Sung University | Li J.-B.,Wuhan University | Yang Z.-J.,Wuhan University | And 2 more authors.
Applied Physics Letters | Year: 2010

We investigated the scattering property of a single plasmon interacting with two quantum dots coupled to one-dimensional surface plasmonic waveguide. We demonstrated that the transmission of a single plasmon could be switched on or off by adjusting spectral detuning and controlling spatial separation of the two quantum dots. These transport properties of the nanosystem could find the applications in plasmonic nanodevices and quantum information processing. © 2010 American Institute of Physics.

Kim N.-C.,Kim Il Sung University | Ko M.-C.,Kim Il Sung University | Wang Q.-Q.,Wuhan University
Plasmonics | Year: 2015

Switching of a single plasmon interacting with n equally spaced quantum dots coupled to one-dimensional surface plasmonic waveguide is investigated theoretically via the real-space approach. We showed that the transmission and reflection of a single plasmon can be switched on or off by dynamically tuning and changing the number of the equal transition frequencies of the quantum dots. Increasing the number of doped quantum dots having the equal transition frequencies results in the wide–band reflection of a single plasmon and the complete transmission peaks near the resonant frequencies. © 2014, Springer Science+Business Media New York.

Metzler W.,University of Kassel | Yun C.H.,Kim Il Sung University
International Journal of Bifurcation and Chaos | Year: 2010

We present a general method for generating continuous fractal interpolation surfaces by iterated function systems on an arbitrary data set over rectangular grids and estimate their Box-counting dimension. © 2010 World Scientific Publishing Company.

Kim Y.-S.,CAS Wuhan Institute of Hydrobiology | Kim Y.-S.,Kim Il Sung University | Ke F.,CAS Wuhan Institute of Hydrobiology | Lei X.-Y.,CAS Wuhan Institute of Hydrobiology | And 2 more authors.
PLoS ONE | Year: 2010

Background: Envelope protein 53R was identified from frog Rana grylio virus (RGV), a member of the family Iridoviridae, and it plays an important role in the virus assembly. Although inhibition of iridovirus major capsid protein (MCP) by small hairpin RNAs (shRNAs) has been shown to cause resistance to viral infection in vitro, RNA interference (RNAi) to inhibit aquatic animal virus envelope protein gene product has not been reported. Methodology: We devised artificial microRNAs (amiRNAs) that target a viral envelope protein gene RGV 53R. By incorporating sequences encoding amiRNAs specific to 53R of RGV into pre-miRNA155 (pSM155) vectors, which use the backbone of natural miR-155 sequence and could intracellularly express 53R-targeted pre-amiRNAs. The pre-amiRNAs could be processed by the RNase III-like enzyme Dicer into 21-25 nt amiRNAs (amiR-53Rs) in fish cell lines. The levels of 53R expression were analyzed through real-time PCR and RGV virions assembly were observed by electronic microscopy in fish cells transfected with or without amiR-53Rs at 72 h of RGV infection. Conclusion/Significance: The results argue that viral envelope protein RGV 53R can be silenced and the virions assembly was deficient by amiR-53R-1, and further identified the first amiRNA of envelope protein gene from iridovirus that was able to cause resistance to virus infection in fish cells. The data demonstrate that the viral infection is efficiently suppressed (58%) by amiR-53R-1 targeting positon 36-57 of RGV 53R. Moreover, electron microscopic observations revealed virion assembly defect or reduced virions assembly capacity was closely correlated to expression of amiR-53R-1. Based on real time PCR of the Mx gene, we found no evidence of activation of IFN by amiR-53R-1. © 2010 Kim et al.

News Article | September 20, 2016

There are more than 140 million .com and .net domains on the internet. There's also millions of websites for each country code top-level domain, or ccTLD, such as .de for Germany, .cn for China and so on. North Korea, one of the most closed-off countries in the world, is not a huge fan of the internet and the web, and we had no idea how many websites the country had registered for its own top-level domain, .kp—until today. Read more: The North Korean Facebook Clone Has Already Been Hacked On Tuesday, apparently by mistake, North Korea misconfigured its nameserver, essentially a list that holds information on all of the domains that exist for .kp, allowing anyone to query it and get the list. In other words, a snafu by North Korea's system administrators allowed anyone to ask the country's nameserver: "can I have all of your information on this domain?" and get an answer, giving everyone a peek into the strange world of North Korea's web. "Now we have a complete list of domain names for the country and it's surprisingly (or perhaps unsurprisingly) very small," Matt Bryant, a security engineer who found out about the mistake, told Motherboard in an email. "We didn't think there was much in the way of internet resources in North Korea, and [...] we were right." North Korea has only 28 registered domains, according to the leaked data. "We didn't think there was much in the way of internet resources in North Korea, and according to these leaked zone files, we were right," Doug Madory, a researcher at Dyn, a company that monitors internet use and access around the world, told Motherboard. Some of the sites aren't reachable, perhaps because after Bryant discovered them, they are being deluged with traffic. "I hope for the head of the NK chief propaganda minister that the grand divine dictator's internet does not break down with all the traffic from Hacker News," a user on Hacker News joked. Most of the websites seem pretty banal, such as the site of the state-owned Air Koryo airline, or that of the Kim Il Sung University. Others, such as the site of the official newspaper of North Korea's communist party, give us a glimpse of the government's powerful propaganda machine. Some users of Hacker News have been able to visit other sites that seem to be unreachable for me. One user, for example, wrote that seems to be a Facebook clone (no, not that weird Facebook clone we discovered months ago), appears to be a Yahoo clone, and looks like a clone of movie4k, a piracy website. Bryant explained that he caught the mistake and downloaded the data because he monitors all top level domains for these kinds of issues, and to get a peek into what countries are doing with their DNS, or domain name servers, which are essentially the internet's phone book. Bryant said that this kind of data is often kept secret by some countries, so it's valuable to grab it while it's available. "The shorter version is just that I'm a nerd who's obsessed with DNS," he said. Thanks to his nerdery, we got a peek into North Korea's small, and mundane, web. Get six of our favorite Motherboard stories every day by signing up for our newsletter.

Drewes M.,TU Munich | Kang J.U.,Kim Il Sung University
Nuclear Physics B | Year: 2013

We calculate the relaxation rate of a scalar field in a plasma of other scalars and fermions with gauge interactions using thermal quantum field theory. It yields the rate of cosmic reheating and thereby determines the temperature of the "hot big bang" in inflationary cosmology. The total rate originates from various processes, including decays and inverse decays as well as Landau damping by scatterings. It involves quantum statistical effects and off-shell transport. Its temperature dependence can be highly non-trivial, making it impossible to express the reheating temperature in terms of the model parameters in a simple way. We pay special attention to the temperature dependence of the phase space due to the modified dispersion relations in the plasma. We find that it can have a drastic effect on the efficiency of perturbative reheating, which depends on the way particles in the primordial plasma interact. For some interactions thermal masses can effectively close the phase space for the dominant dissipative processes and thereby impose an upper bound on the reheating temperature. In other cases they open up new channels of dissipation, hence increase the reheating temperature. At high temperatures we find that the universe can even be heated through couplings to fermions, which are often assumed to be negligible due to Pauli-blocking. These effects may also be relevant for baryogenesis, dark matter production, the fate of moduli and in scenarios of warm inflation. © 2013 Elsevier B.V.

We theoretically study chirped four-wave mixing for VUV pulse generation in hollow-core photonic crystal fibers. We predict the generation of sub-10'fs VUV pulses with energy of up to hundreds of 'J by broad-band chirped idler pulses at 830'nm and MW pump pulses with narrow-band at 277'nm. The MW pump could be desirable to reduce the complexity of the laser system or use a high repetition rate laser system. The energy conversion efficiency from pump pulse to VUV pulse reaches to 30% . This generation can be realized in a kagome-lattice hollow-core PCF filled with noble gas of high pressure with core diameter less than 40''m, which would enable technically simple or highly efficient coupling to the fundamental mode of the fiber. © 2015 Astro Ltd.

Sin J.-S.,Kim Il Sung University | Im S.-J.,Kim Il Sung University | Kim K.-I.,Kim Il Sung University
Electrochimica Acta | Year: 2015

We theoretically study electrostatic properties of electric double layer using a generalized Poisson-Boltzmann approach taking into account the orientational ordering of water dipoles and the excluded volume effect of water molecules as well as those of positive and negative ions with different sizes in electrolyte solution. Our approach enables one to predict that the number densities of water molecules, counterions and coions and the permittivity of electrolyte solution close to a charged surface, asymmetrically vary depending on both of sign and magnitude of the surface charge density and the volume of counterion. We treat several phenomena in more detail. Firstly, an increase in the volume of counterions and an increase in the surface charge density can cause the position of the minimum number density of water molecules to be farther from the charged surface. Secondly, width of the range of voltage in which the properties at the charged surface symmetrically vary decreases with increasing bulk salt concentration. In addition, we show that the excluded volume effect of water molecules and the orientational ordering of water dipoles can lead to early onset and lowering of the maximum of electric capacitance according to surface voltage. Our approach and results can be applied to describing electrostatic properties of biological membranes and electric double layer capacitor for which excluded volume effects of water molecules and ions with different sizes may be important. © 2014 Elsevier Ltd. All rights reserved.

Im S.-J.,Kim Il Sung University | Ho G.-S.,Kim Il Sung University
Laser Physics Letters | Year: 2015

We study transmission in a nano waveguide coupled to high-quality plasmon resonances for which the metal loss is overcompensated by gain. The on-resonance transmission can vary widely from lower than -20 dB to higher than 20 dB for a range of gain coefficient. A reversible transition between the high-quality amplification and the suppression can be induced by a quite small change of gain coefficient for a moderately increased distance between the waveguide and the resonator. It is expected that in practice a small change of gain coefficient can be made by flexibly controlling pumping rate or utilizing nonlinear gain. Additionally, based on the frequency-dependant model for gain-transition susceptibility, it is shown that the wide variation of the on-resonance transmission can also be observed for defferent detuning of the gain-transition line-center. Such a widely controllable on-resonance transmission is promising for applications such as well-controlled lumped amplification of surface plasmon-polariton as well as plasmonic switching. © 2015 Astro Ltd.

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