• Proceedings of the Korea Crystallographic Association Conference
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• 2002.11a
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• pp.5-6
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• 2002

The new spectrometer for X-ray Induced Electron Emission Spectroscopy (XIEES) .has been recently developed in KRISS in collaboration with PTI (Russia). The spectrometer allows to perform research using the XAFS, SXAFS, XANES techniques (D.C.Koningsberger and R.Prins, 1988) as well as the number of techniques from XIEES field(L.A.Bakaleinikov et all, 1992). The experiments may be carried out with registration of transmitted through the sample x-rays (to investigate bulk samples) or/and total electron yield (TEY) from the sample surface that gives the high (down to several atomic mono-layers in soft x-ray region) near surface sensitivity. The combination of these methods together give the possibility to obtain a quantitative information on elemental composition, chemical state, atomic structure for powder samples and solids, including non-crystalline materials (the long range order is not required). The optical design of spectrometer is made according to Johannesson true focusing schematics and presented on the Fig.1. Five stepping motors are used to maintain the focusing condition during the photon energy scan (crystal angle, crystal position along rail, sample goniometer rail angle, sample goniometer position along rail and sample goniometer angle relatively of rail). All movements can be done independently and simultaneously that speeds up the setting of photon energy and allows the using of crystals with different Rowland radil. At present six curved crystals with different d-values and one flat synthetic multilayer are installed on revolver-type monochromator. This arrangement allows the wide range of x-rays from 100 eV up to 25 keV to be obtained. Another 4 stepping motors set exit slit width, sample angle, channeltron position and x-ray detector position. The differential pumping allows to unite vacuum chambers of spectrometer and x-ray generator avoiding the absorption of soft x-rays on Be foil of a window and in atmosphere. Another feature of vacuum system is separation of walls of vacuum chamber (which are deformed by the atmospheric pressure) from optical elements of spectrometer. This warrantees that the optical elements are precisely positioned. The detecting system of the spectrometer consists of two proportional counters, one scintillating detector and one channeltron detector. First proportional counter can be used as I/sub 0/-detector in transmission mode or by measuring the fluorescence from exit slit edge. The last installation can be used to measure the reference data (that is necessary in XANES measurements), in this case the reference sample is installed on slit knife edge. The second proportional counter measures the intensity of x-rays transmitted through the sample. The scintillating detector is used in the same way but on the air for the hard x-rays and for alignment purposes. Total electron yield from the sample is measured by channeltron. The spectrometer is fully controlled by special software that gives the high flexibility and reliability in carrying out of the experiments. Fig.2 and fig.3 present the typical XAFS spectra measured with spectrometer.

• Journal of Korean Society of Transportation
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• v.23 no.8 s.86
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• pp.101-111
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• 2005

Various urban transport policies have an effect on urban transit riderships and accessibility. This study reports variations of metropolitan subway travel patterns affected by an enormous change in bus routes and transfer discount fare policy between subway and bus mode conducted by Seoul city in July 1st of 2004. In an effort to see the difference between the before and the after policies, two data sets are prepared. Firstly, on a daily bassis. an origin-destination trip table of May of 2004 is used. Secondly, on a daily bassis, an origin-destination trip table of August-September of 2004 is used as a counter measure. Even if seasonal variation was not considered, Seoul metropolitan area have experienced increasing riderships and accessibility. Finally, the effects of accessibility in spatial interaction model by rall service changes such as random shocks were scrutinized and interpreted in detail.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.5C
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• pp.454-464
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• 2002

In the ATM-PON (Asynchronous Transfer Mode-Passive Optical Network), the downstream cell transmitted by an OLT is broadcast to all ONUs. The ONU receives selectively its own cells by VP filtering. On the other hand, the upstream cell can be transmitted by ONU in the case of receiving a grant from the OLT. After providing the grant to an ONU, the OLT expects the arrival of a cell after an elapse of the equalized round trip delay. ITU-T G.983.1 recommends that one bit error is allowed between the expected arrival time and the actual arrival time at the OLT. Because the ONU processes the different delay to each type of grant (ranging, user cell, and mimi-slot grant), it is not simple to design the transmission part of ONU. In this paper, we implement a grant processor which provides the delay accurately in the ONU TC chip with the FPGA. For the given equalized delay, it deals with the delay for the cell, the byte, and the bit unit by using the shift register, the byte counter, and the D flip-flop, respectively. We verify the operation of the grant processor by the time simulation and the measurement of the optical board output.

• Korean journal of applied entomology
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• v.31 no.3
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• pp.314-327
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• 1992

Insecticide resistance is a serious is a serious threat to IPM, resulting in various adverse effects not to mention the loss of yield in agriculture. One approach to counter the problem is the disruption of resistance mechanisms. This can be achieved by (1) compounds which show a negative correlation with resistance at the site of action, (2) specific metabolic inhibitors which serve as synergists, or (3) a certain combination of two insecticides producing a joint action. This approach, however, requires certain precautions for the side effects may cause an increase in toxicity to mammals. Owing to the recent advances in theoretical studies on resistance management employing computer simulation and mathematical models, a few principles to reduce the risk of development of resistance have been clarified. They are helpful in designing operational strategies with regard to, for instance, insecticide doses to be applied, mode of application, and choice and nature of the insecticide(s) to be used. For restoration of insecticide susceptibility of a resistant population, reintroduction of susceptible individuals to the resistant population is feasible when certain conditions are met. Natural enemies which developed resistance to insecticides can be an important component of IPM as has been shown in the pest management in apple orchards. After all, the implementation of a successful resistance management program depends upon cooperation between different sigments of the agricutural community. Although resistance is a preadaptive phenomenon, in some cases spontaneous loss of resistance does occur without contamination by susceptible individuals. The instability of resistance in these insects implies the possible existence of a switch machanism controlling the expression of resistance gene(s). Elucidation of such a mechanism may eventually provide us with a new technical approach with which we can combat the problem of insecticide resistance.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.E1
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• pp.15-28
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• 2004

To study the characteristics of ammonia and the related compounds, atmospheric aerosols and gases were collected using a triple filter pack sampler, a low volume air sampler, and a three-stage Anderson air sampler in Seoul and Kangwha Island, Korea from Dec. 1996 to Oct. 1997. Ammonia concentrations showed approximately two times higher in summer than in winter at both sites. The highest $HNO_3$ levels were generally observed in summertime at two sampling sites. The average mass concentration of $PM_{2.5}$ in heavily industrialized Seoul was about three times higher than that of Kangwha. In winter, the sum of $NH_4^+$ and its counter ions (such as $Cl^-,\;NO_3^-$, and $SO_4^{2-}$) comprised $30-41\%$ of $PM_{2.5}$ mass concentration at each sampling site. Temperature dependence of particulate nitrate was examined at the urban sampling site. The formation of the nitrate in the fine mode was dependent not only on the amount of precursors but also on the variation of temperature. $(NH_4)_2SO_4$ and $NH_4HSO_4$ coexisted with $NH_4NO_3$ and $NH_4Cl$ at each site. According to the summertime backward trajectory analysis, $NO_3^-$ showed higher level with air parcels transported from northeast Asian continent. On the other hand, the concentration of $SO_4^{2-}$ showed significantly higher level when air masses originated from Pacific Ocean, southern part of Japan, and Korea.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.111-111
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• 2007

Further scaling the semiconductor devices down to low dozens of nanometer needs the extremely shallow depth in junction and the intentional counter-doping in the silicon gate. Conventional ion beam ion implantation has some disadvantages and limitations for the future applications. In order to solve them, therefore, plasma source ion implantation technique has been considered as a promising new method for the high throughputs at low energy and the fabrication of the ultra-shallow junctions. In this paper, we study about the effects of DC bias and base pressure as a process parameter. The diluted mixture gas (5% $PH_3/H_2$) was used as a precursor source and chamber is used for vacuum pressure conditions. After ion doping into the Si wafer(100), the samples were annealed via rapid thermal annealing, of which annealed temperature ranges above the $950^{\circ}C$. The junction depth, calculated at dose level of $1{\times}10^{18}/cm^3$, was measured by secondary ion mass spectroscopy(SIMS) and sheet resistance by contact and non-contact mode. Surface morphology of samples was analyzed by scanning electron microscopy. As a result, we could accomplish the process conditions better than in advance.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.2
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• pp.135-143
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• 2005

It was evaluated that the effect of turbidity removal by Pore Controllable Fiber Filter(PCF) installed in NS(Naksang) small water treatmant plant(system) using under flow water as raw water in the study. The results of the study are as the followings. Firstly, the removal efficiency of turbidity by PCF without coagulation(in operation mode not using coagulants) was mostly below 20 percent. On the other hand, when operation using proper coagulants, that of turbidity was mostly over 80 percent. Secondly, slow sand filtration after PCF, total turbidity removal efficiency of final treated water was 84.3 percent, and the contribution by PCF was 57.1 percent and that of slow sand filtration was 27.7 percent. Therefore the introduction of PCF as pre-treatment process would be helpful to reduce the loading of high turbidity of slow sand filtration. Thirdly, the results of particle counter measurements showed that when operated PCF with coagulants, fine flocs captured or adsorbed at the pore of PCF were flow out into the effluents from 120 minutes after backwashing because of the increase of headloss of PCF. Therefore the decision of backwashing time should made consideration into the outflow of fine flocs from PCF. Fourth, coagulant dosages on PCF at the same turbidity was largely variable because of the effect of the raw water characteristics and the turbidity increase velocity at rainy days, therefore flexible coagulant dosages should be considered rather than fixed coagulant dosage by the influent jar-test result.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.6
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• pp.1026-1031
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• 2008

Nowdays, homes and small businesses rely more and more PON(Passive Optical Networks) for financial transactions, private communications and even telemedicine. Thus, encryption for these data transactions is very essential due to the multicast nature of the PON In this parer, we presented our implementation of a counter mode AES based on Virtex4 FPGA. Our design exploits three advanced features; 1) Composite field arithmetic SubByte, 2) efficient MixColumn transformation 3) and on-the-fly key-scheduling for fully pipelined architecture. By pipeling the composite field implementation of the S-box, the area cost is reduced to average 17 percent. By designing the on-the-fly key-scheduling, we implemented an efficient key-expander module which is specialized for a pipelined architecture.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.278-281
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• 2012

Numerical studies were performed to investigate the three-dimensional front structure and dynamics features of detonation wave propagating in a circular tube such as Pulse Detonation Engine (PDE). By carrying out a series of parametric study using one step irreversible Arrhenius kinetics model, mechanisms of the three-dimensional front structure were investigated for two-, three-, four and six-cell mode detonations. A comparison with two-dimensional results, the effects of slapping transverse waves in radial direction were confirmed. In the all muti-cell modes, the detonation front structures and smoked-records on the wall are formed by the propagation of transverse waves along the wall in clockwise and counter-clockwise while the slapping move in radial direction. And the strength of reflected waves on the curved wall is changed by the multi-dimensional confinement effect.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.32 no.5
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• pp.807-816
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• 2022

See-In-The-Middle (SITM) is an analysis technique that uses Side-Channel information for differential cryptanalysis. This attack collects unmasked middle-round power traces when implementing block ciphers to select plaintext pairs that satisfy the attacker's differential pattern and utilize them for differential cryptanalysis to recover the key. Romulus, one of the final candidates for the NIST Lightweight Cryptography standardization competition, is based on Tweakable block cipher Skinny-128-384+. In this paper, the SITM attack is applied to Skinny-128-384 implemented with 14-round partial masking. This attack not only increased depth by one round, but also significantly reduced the time/data complexity to 2^14.93/2^14.93. Depth refers to the round position of the block cipher that collects the power trace, and it is possible to measure the appropriate number of masking rounds required when applying the masking technique to counter this attack. Furthermore, we extend the attack to Romulus's Nonce-based AE mode Romulus-N, and Tweakey's structural features show that it can attack with less complexity than Skinny-128-384.