• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.1
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• pp.1-7
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• 2000

The SNOSFET memory devices with ultrathin ONO(tunnel oxide-nitride-blocking oxide) gate dielectric were fabricated using n-well CMOS process and investigated its characteristics. The thicknesses of tunnel oxide, nitride and blocking oxide were $23{\AA},\; 53{\AA}\; and\; 33{\AA}$, respectively. Auger analysis shows that the ONO layer is made up of $SiO_2(upper layer of blocking oxide)/O-rich\; SiO_x\N\_y$. It clearly shows that the converting layer with $SiO_x\N\_y(lower layer of blocking oxide)/N-rich SiO_x\N\_y(nitride)/O-rich SiO_x\N\_y(tunnel oxide)$. It clearly shows that the converting layer with $SiO_x\N\_y$ phase exists near the interface between the blocking oxide and nitride. The programming condition of +8 V, 20 ms, -8 V, 50 ms is determined and data retention over 10 years is obtained. Under the condition of 8 V programming, it was confirmed that the modified Fowler-Nordheim tunneling id dominant charge transport mechanism. The programmed threshold voltage is distributed less than 0.1 V so that the reading error of memory stated can be minimized. An $8\times8$ NAND type flash EEPROM with SONOSFET memory cell was designed and simulated with the extracted SPICE parameters. The sufficient read cell current was obtained and the upper limit of $V_{TH}$ for write state was over 2V.

• Journal of the Korean Chemical Society
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• v.39 no.5
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• pp.350-355
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• 1995

UV spectrophotometric investigation has been carried out on the system of charge-transfer (CT) complex with iodine and tetramethyltin in carbon tetrachloride solvent. The transient CT absorption spectrum can be observed in ${\lambda}_{max}=270nm$ and the subsequent disappearance of CT absorption spectrum was accompained by the cleavage of tetramethyltin with iodine (iododestannylation). From there, the rate constants for the iododestannylation were determined at 10, 20 and $35^{\circ}C$ up to 1200 bar and the reaction rates were increased with increasing temperature and pressure. From these rate constants, the values of the activation parameters (${\Delta}V^{\neq},\;{\Delta}{\beta}^{\neq},\;{\Delta}H^{\neq}\;and\;{\Delta}S^{\neq}$) were obtained and from these values discussed in terms of solvent structure variation of transition state and mechanism. From these results, it was found that the reaction is followed with $S_F2$ mechanism and weakened $S_F2$ mechanism nature by increasing pressure.

• Economic and Environmental Geology
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• v.28 no.4
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• pp.327-335
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• 1995

Illite/smectite (I/S) in the Beaufort-Mackenzie Basin, Arctic Canada has been scrutinized on the basis of mineralogical analysis of 215 core and drill-cutting samples from 22 exploratory wells onshore and offshore. I/S in the Beaufort-Mackenzie Basin includes the following four types: random, a mixture of random and ordered, R1-ordered, and R>1-ordered I/S. A mixture of random and ordered I/S occurs in the transitional interval between random and R>1-ordered I/S, and may represent a metastable state in the ordering reaction. A widespread occurrence of the mixture in natural environments suggests that the ordering reaction may be a slow process that results in co-existence of reactants and products. K-saturation experiments show that layer charges of expandable layers in I/S are variable. High-charge expandable layers transform into illite-like layers upon simple K-saturation. K-saturation alters the composition and/or the degree of ordering in I/S, suggesting that illitization in nature can be transformational.

• Journal of the Korea Safety Management & Science
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• v.5 no.3
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• pp.81-98
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• 2003

In modern society, there are diverse sorts of VIPs including a king and individuals. Some like a king or president are in need of professional secret services, and others become VIPs by being guarded by a bodyguard company at their own request. The former is called a public guard, and the latter is a private one. In the field of the public guard, the nation should be furnished with a guard system in consideration of political circumstances to protect VIPs. That is, the parliamentary cabinet system and presidential system call for a different guard system, and the guard system's professional features vary to some degree with political situations and cultural climate. If the ultimate goal of guard is to protect the chief of the democratic and open state in a most efficient and safe manner, it's mandatorily necessary to set up a professional and specialized guard organization to provide democratic and efficient secret services. It's desired that the domestic presidential guard division should be staffed with not only expert guards but other personnels dispatched from the military and police. In the police, guard mission is splitted among various guard and security agencies, including the National Police Agency's public security bureau or the Seoul Metropolitan Police Agency's public security division, 101 security unit, mobile police and 22 special guard division. As a chain of command is separated and it's difficult to manage such organizations effectively, the National Police Agency should be exclusively in charge of VIP guard and security. In the area of private guard, the private police system has shared national security task as a middle organization between the private police and private guard. But now its intent has gradually weakened, and its mission should be redefined. In addition, the way people look at private guard should change, and they should be well informed that it could serve to prevent possible crimes, protect them against crimes and get rid of their inconveniences. To make a good impression on people, the guard associations and businesses should put their efforts into reinforcing publicity activities, and the government, academic circles and press should team up with them as well.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.1
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• pp.175-179
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• 2021

With the recent increase in the proportion of single-person households, the demand for reasonable personal mobility has increased, and the "Personal Mobility" industry that can be used conveniently and concisely has grown rapidly. In fact, according to data from the Korea Transport Institute, the scale of the electric kickboards rental industry, one of the personal mobility industry sectors, is expected to expand to 200,000 units in 2022. Due to the characteristics of electric kickboards that are powered by electricity, stable and efficient battery supply is the most basic and important issue. According to recent reviews from users who have used the electric kickboard, there were cases where the use of the electric kickboard is attempted, but the battery is in a discharged state or the battery charge level is low and thus cannot be used. Therefore, this paper proposes a solar charging system for stable battery use of electric kickboards. When this system is applied, it is expected that it will not only be an eco-friendly charging method for electric kickboards, but also stably supply and demand batteries while driving.

• Journal of Powder Materials
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• v.30 no.6
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• pp.509-515
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• 2023

Lead-free perovskite ceramics, which have excellent energy storage capabilities, are attracting attention owing to their high power density and rapid charge-discharge speed. Given that the energy-storage properties of perovskite ceramic capacitors are significantly improved by doping with various elements, modifying their chemical compositions is a fundamental strategy. This study investigated the effect of Zn doping on the microstructure and energy storage performance of potassium sodium niobate (KNN)-based ceramics. Two types of powders and their corresponding ceramics with compositions of (1-x)(K,Na)NbO₃-xBi(Ni_2/3Ta_1/3)O₃ (KNN-BNT) and (1-x)(K,Na)NbO₃-xBi(Ni_1/3Zn_1/3Ta_1/3)O₃ (KNN-BNZT) were prepared via solid-state reactions. The results indicate that Zn doping retards grain growth, resulting in smaller grain sizes in Zn-doped KNN-BNZT than in KNN-BNT ceramics. Moreover, the Zn-doped KNN-BNZT ceramics exhibited superior energy storage density and efficiency across all x values. Notably, 0.9KNN-0.1BNZT ceramics demonstrate an energy storage density and efficiency of 0.24 J/cm³ and 96%, respectively. These ceramics also exhibited excellent temperature and frequency stability. This study provides valuable insights into the design of KNN-based ceramic capacitors with enhanced energy storage capabilities through doping strategies.

• Journal of the Korean Vacuum Society
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• v.10 no.2
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• pp.275-281
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• 2001

We used the discrete-sectional model to analyze the particle growth by coagulation of particles in silane plasma reactor, considering the Gaussian distribution function for particle charges. The effects of process conditions such as monomer size and mass generation rate of monomers on particle growth in plasma reactor were analyzed theoretically/ Based on the Gaussian distribution function of particle charges, the large particles of more than 40 nm in size are almost found to be charged negatively, but some fractions of small, tiny particles are in neutral state or even charged positively. As the particle size and surface area increase with time by particle coagulation, the number of charges per particle increases with time. As the large particles are generated by particle coagulation, the particle size distribution become bimodal. The results of discrete-sectional model for the particle growth in silane plasma reactor were in close agreement with the experimental results by Shiratani et al. [3] for the same plasma conditions. We believe the model equations for the particle charge distribution and coagulation between particles can be applied to understand the nano-sized particle growth in plasma reactor.

• Progress in Medical Physics
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• v.2 no.2
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• pp.129-139
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• 1991

The method of etching tracks in PN-3 dosimeter has been applied to tracks of recoil protons from a neutron source. Both the etch and the detection response of PN-3 has been studied as a function of etched-track diameters against various parameters. We could obtain very useful informations about charge, energy, and mass of particles and the relationship between the track etching rate and the track forming procedure in order to analyze the particle recorded in the solid state track detector. The best etching condition could be found by means of changing the etching circumstances for various energies and particles in order to detect the charged particle accurately. It could be influenced widely that the polymer plastic detector could develep the detecting technique for the low energy level neutron and could be used as a neutron dosimeter in the radiation field such as the nuclear power station, the medical institute and the nondtructive testing institute.

• Journal of the Korean Vacuum Society
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• v.6 no.4
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• pp.337-342
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• 1997

We have investigated Mossbauer effect and emission properties of the Fe-doped GaAs grown by liquid phase epitaxy (LPE). The powder type of isotope $^{57}Fe$ was used as a dopant source in LPE-GaAs. From the analysis of Mossbauer effect the value of isomer shift, 0.303$\pm$0.018 mm/sec, is calculated at low temperature. This means that charge state of Fe ion in GaAs is 3+. The results of double crystal x-ray rocking curve (DCRC) and low temperature photoluminescence (PL) show the crystal quality of the epitaxial layers are good. Unusual luminescence peaks from the Fe-GaAs epitaxial layers appeared at emission energy of 0.99 eV and 1.15 eV. We attribute these emissions to Fe-acceptor related two deep radiative centers.

• Journal of Radiation Protection and Research
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• v.41 no.2
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• pp.81-86
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• 2016

Background: For positron emission tomography (PET) application, cadmium zinc telluride (CZT) has been investigated by several institutes to replace detectors from a conventional system using photomultipliers or Silicon-photomultipliers (SiPMs). The spatial and energy resolution in using CZT can be superior to current scintillator-based state-of-the-art PET detectors. CZT has been under development for several years at the Korea Atomic Energy Research Institute (KAERI) to provide a high performance gamma ray detection, which needs a single crystallinity, a good uniformity, a high stopping power, and a wide band gap. Materials and Methods: Before applying our own grown CZT detectors in the prototype PET system, we investigated preliminary research with a developed discrete type data acquisition (DAQ) system for coincident events at 128 anode pixels and two common cathodes of two CZT detectors from Redlen. Each detector has a $19.4{\times}19.4{\times}6mm^3$ volume size with a 2.2 mm anode pixel pitch. Discrete amplifiers consist of a preamplifier with a gain of $8mV{\cdot}fC^{-1}$ and noise of 55 equivalent noise charge (ENC), a $CR-RC^4$ shaping amplifier with a $5{\mu}s$ peak time, and an analog-to-digital converter (ADC) driver. The DAQ system has 65 mega-sample per second flash ADC, a self and external trigger, and a USB 3.0 interface. Results and Discussion: Characteristics such as the current-to-voltage curve, energy resolution, and electron mobility life-time products for CZT detectors are investigated. In addition, preliminary results of gamma ray imaging using 511 keV of a $^{22}Na$ gamma ray source were obtained. Conclusion: In this study, the DAQ system with a CZT radiation sensor was successfully developed and a PET image was acquired by two sets of the developed DAQ system.