• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.10
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• pp.1850-1855
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• 2010

The application field of the pulse power is very wide. Recently, Pulse power technologies take a large place in several applications. Then, many civil and military applications proceed. Marx generator is widely used in high voltage applications. Marx generator is widely used in high voltage applications, such as eletromagnetic wave and power lasers. This paper, we described about the high voltage pulse generator. A compact size high voltage pulse generator with nanosecnd rise time has been fabricated and investigated experimentally. The marx generator has 2 stages. Each stage was constructed one charging capacitor, two electrodes and one charging resistor. A inductance structure is used in order to improve the switching performances fo the whole generator. The experiments of rise time in pure gas and mixtures of gases were described. We tested the Marx generator at different insulation gas. the results show that the dielectric strength of the $N_2-SF_6$ mixture was significantly increased compared with pure nitrogen gas. The experimental results show that the rise time characteristics of the Marx generator can be controlled through varying insulation gas.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.1
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• pp.71-77
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• 2004

It was proved that Hen is an algebraic ,elation of degree [n(l+1]/2] for an (n, 1)-combine. which consists of n LFSRs and l memory bits. For the summation generator with $2^k$ LFSRs which uses k memory bits, we show that there is a non-trivial relation of degree at most $2^k$ using k+1 consecutive outputs. In general, for the summation generator with n LFSRs, we can construct a non-trivial algebraic relation of degree at most 2$^{{2^{[${log}_2$}n]}}$ using [${log}_2$＋1 consecutive outputs.

• Fire Science and Engineering
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• v.24 no.2
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• pp.139-144
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• 2010

An experimental study has been carried out to investigate the possibilities of an industrial $N_2$ generator that it replace Halon series as a natural extinguishing system. And this study comparison design standard of gas series extinguishing system with natural extinguishing system. We manufactured simple protected enclosure for analyzing fire-extinguishing performance of the $N_2$ generator. As a $N_2$ gas is exhausted on protected enclosure, a various of Oxygen concentration is measured to analyze fireextinguishing performance experimentally. The results, in case of $100m^3$ protected enclosure and $5m^3$/min $N_2$ flow rate, the Oxygen concentration is decreased below 15% within 3 minutes. And so, the $N_2$ generator make full use of an suffocating extinguishing system.

• Fire Science and Engineering
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• v.24 no.6
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• pp.54-60
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• 2010

An experimental study has been carried out to determine the flow rate for a feasible N2 generator to extinguish the fire, and this study analogized the correlations to determine the flow rate for $N_2$ generator considered an Oxygen concentration, protected enclosure, discharging pressure and discharging time. We manufactured simple protected enclosure for analyzing fire-extinguishing performance of the $N_2$ generator. As a $N_2$ gas is exhausted on protected enclosure, a various of Oxygen concentration is measured to analyze fire-extinguishing performance experimentally. The correlations determined as an uncertainty analysis for the Oxygen concentration deviations of the theoretical and experimental value. The analogized correlations is Q = (21 $\times$ V)/($O_2+{\zeta}{\cdot}P$)-V. In case of $300m^3$ protected enclosure, 0.8 MPa discharging pressure and $40m^3$/min $N_2$ flow rate, the Oxygen concentration is decreased below 15% within 3 minutes.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.6
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• pp.13-21
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• 2010

A energy efficient $V_{pp}$ generator using a variable pumping frequency for mobile DRAM is presented in this paper. The proposed $V_{pp}$ generator exploits 3 stages of a cross-coupled charge pump for energy efficiency. Instead of using a fixed pumping frequency in the conventional $V_{pp}$ generator, our proposed $V_{pp}$ generator adopts a voltage-controlled oscillator and uses variable frequencies to reduce the ramp-up time. As a result, our $V_{pp}$ generator generates 3.0 V output voltage with 24.0-${\mu}s$ ramp-up time at 2 mA current load and 1 nF capacitor load with 1.2 V supply voltage. Experimental results show that the proposed $V_{pp}$ generator consumes around 26% less energy (1573 nJ $\rightarrow$ 1162 nJ) and reduces 29% less ramp-up time (33.7-${\mu}s$ $\rightarrow$ 24.0-${\mu}s$) compared to the conventional approach.

• The Korean Journal of Nuclear Medicine Technology
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• v.17 no.2
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• pp.48-52
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• 2013

Purpose: The Molybdenum which is the raw material of $^{99}Mo-^{99m}Tc$ generator is produced from the nuclear reactor. However, output has dwindled as the two nuclear reactors supplying the bulk of radioactive material-one in Chalk River, Ontario and the other in Petten, the Netherlands-have been closed for repairs or maintenance. This resulted in the enhancement of its price. So $^{99}Mo-^{99m}Tc$ generator using$(n,{\gamma})^{99}Mo$ is developed by Korea Atomic Energy Research Institute (KAERI). Medicinal availability of this generator is evaluated in this study. Materials and Methods: The radioactivity of $^{99m}Tc$ eluted in generator 1, 2 and 3 unit developed by KAERI was measured. The quality control test of generator such as appearance test, pH test, LAL test, sterility test, chemical impurity (Al) test and radiochemical purity test were performed. Planar and SPECT/CT image sof SD rat (6 weeks, Female) at 2 hr after injection of $^{99m}Tc-HDP$ (hydroxymethylenediphosphonate) (TechneScan HDP, Malinckrodt Medical, Dutch) and $^{99m}Tc-DPD$ (diphosphono-1, 2-propanedicarboxylicacid) (TECEOS, CIS bio international, France) which were labeled with $^{99m}Tc$ eluted in KAERI and commercial generator (40.5 GBq, Malinckrodt Medical, Dutch) using SPECT/CT camera (Symbia, Siemense, Germany) were obtained respectively. Results: The mean radioactivity of $^{99m}Tc$ elution generator 1unit was 4.18 GBq (113 mCi), generator 2 unit was 4.73 GBq (128 mCi) and generator 3 unit was 3.33 GBq (90 mCi). All quality control tests were within normal limit except pyrogentest. Pyrogen test was positive. Planar and SPECT/CT images of rat injected $^{99m}Tc-HDP$ which was labeled with $^{99m}Tc$ eluted in commercial generator show increased uptake in bone, stomach and bowl. Planar images show increased uptake in liver and bone in case of $^{99m}Tc-DPD$. However, images of rat injected $^{99m}Tc-HDP$ and $^{99m}Tc-DPD$ which were labelled $^{99m}Tc$ eluted in KAERI generator show increased uptake in bone, liver and spleen. Conclusion: If shortcoming is removed such as pyrogen and liver appearance, domestic role as an alternative generator is thought to be able to fill and to secure the national medical service by supplying $^{99m}Tc$ when the supply of $^{99m}Tc$ be comes short.

• New & Renewable Energy
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• v.6 no.4
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• pp.41-49
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• 2010

Over the last decade, wind turbine industry has rapidly increased around world. These days many parts of the wind generators are induction generator. But it has some problems such as gearbox failure, rotor excitation and maintenance. Thus many manufacturers are considered permanent magnet synchronous generator named PMSG and direct drive. PMSG uses NdFeB magnet has many the advantage compare with induction generator. In this study, 3MW class outer rotor type PMSG for wind turbine is proposed. The generator features 2.6m stator outer radius, 1200mm stator length, 81 pole pairs, 14 rated rpm, 42kN/$m^2$ shear force density and 94.2% efficiency. Design and analysis generator using FEM program. Then calculate and derivate no load voltage, losses, conductor temperature. To reduce total harmonic distortion and cogging torque, the stator is applied the stator skewing. And to evaluate the designed generator, compare with other generators by active mass per rating torque and torque density.

• KSTLE International Journal
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• v.10 no.1_2
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• pp.33-36
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• 2009

The nuclear steam generator is composed of a bundle of tubes. The length of these tubes is very long, but their diameter is small. Fluid exists inside of the steam generator and its flow causes vibration, therefore these tubes are supported by anti-vibration bars. The wear damage due to the vibration is known as fretting wear, which should be minimized to ensure the safety of the plants. Research needs to be done about decreasing the amount of fretting wear. Hard coatings have proven to be very effective in reducing the amount of wear. The commercial coatings of TiN and CrN have excellent wear resistance and are used to protect the Inconel tube from fretting wear. The tube-on-flat type tester was used for conducting the fretting wear tests. It was found that the wear amounts of the coated tubes decreased depending on the coating thickness. CrN was found to be very effective in reducing the wear, while the wear amounts were dependent on the coating thickness in the case of TiN and a thick coating of TiN was very effective on wear resistance.

• Korean Journal of Materials Research
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• v.27 no.2
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• pp.89-93
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• 2017

A thin film thermoelectric generator that consisted of 5 p/n pairs was fabricated with $1{\mu}m$-thick n-type $In_3Sb_1Te_2$ and p-type $Ge_2Sb_2Te_5$ deposited via radio frequency magnetron sputtering. First, $1{\mu}m$-thick GST and IST thin films were deposited at $250^{\circ}C$ and room temperature, respectively, via radio-frequency sputtering; these films were annealed from 250 to $450^{\circ}C$ via rapid thermal annealing. The optimal power factor was found at an annealing temperature of $400^{\circ}C$ for 10 min. To demonstrate thermoelectric generation, we measured the output voltage and estimated the maximum power of the n-IST/p-GST generator by imposing a temperature difference between the hot and cold junctions. The maximum output voltage and the estimated maximum power of the $1{\mu}m$-thick n-IST/p-GST TE generators are approximately 17.1 mV and 5.1 nW at ${\Delta}T=12K$, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.14 no.2
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• pp.137-145
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• 1989

In this paper we consider the design of bent sequence generators employing a modified bent function. Through the experimental results and simulation, we show that the period of sequences is $2^n$-1, the number of sequences in the set is $2n/2$, the largest magnitude of correlation is $2n/2$+1, and the sequence generators easy to randomly initialize into any assigned code and hence can be rapidly hopped from sequence to sequence. And we construct a code synchronization system with bent sequence generator as the local code generator, a sliding correlator and DLL as the acquisition subsystem and the tracking subsystem, respectively for DS-CODA, and verify the experimenta results for accomplishing code synchronism.