• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.20 no.1
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• pp.113-124
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• 1990

For the study of the influence of kilovoltage and exposure time on radiographic density and contrast, we measured radiographic density of aluminum step wedge which composed of contiguous 8 steps wedges of 2-16㎜ thickness with densitometer. Aluminum step wedge was radiographed on Kodak ultraspeed DF-58 and Ektaspeed EP-21 film with range of 60-90 kVp and 5-60 impulse and subject contrast of aluminum step wedge with constant radiographic density and image contrast percentage without radiographic density was evaluated. Then we evaluated the film quality of teeth and their surrounding structure according to the change of kVp and exposure time by score rating method. The obtained results were as follows: 1. Radiographic density was related to the change of kilovoltage, especially in increased exposure time. 2. With constant radiographic density, subject contrast of thin aluminum step wedges was greater in low kilovolt age than high kilovoltage, but kilovolt age had not great influence on subject contrast of thick aluminum step wedge. On the other hand, radiographic density difference between 2mm and 16mm aluminum step wedge was decreased according to in- creasing kilovoltage. 3. Without constant radiographic density, image contrast percentage was decreased with increasing kilovoltage, but was not related with the change of exposure time. 4. Radiographic contrast of teeth and their surrounding structure which was taken with the range of 60-90 kVp and 6-30 impulse had not great influence on film quality.

• Aerospace Engineering and Technology
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• v.1 no.1
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• pp.72-83
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• 2002

Required power and solar array sizing of KOMPSAT-2 have been analyzed by ASTRIUM and KARI in November, 2000. There are Electrical Power Subsystem(EPS) design discrepancies between ASTRIUM and Korea Aerospace Research Institute(KARI) according to heritage program, EPS operation concepts, power source and the characteristic of the electrical boxes. To design the power system of KOMPSAT-2, ASTRIUM has used the EPS design of the CHAMP and GlobalStar program. But SSTI, TOMS-EP and KOMPSAT-1's design concepts has been used for KOMPSAT-2 EPS design by the KARI. To get the design conclusion, there are many trade-off meetings for the EPS sizing using each sides' heritage program and EPS operation concept. And the EPS design factors and approaching methods have been reviewed and discussed. In addition the EPS design results from ASTRIUM and KARI are summarized in this paper.

• Journal of Microbiology
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• v.42 no.2
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• pp.103-110
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• 2004

In order to understand the molecular basis of selective expression of stationary-phase genes by RNA polymerase containing$\sigma$$\^$38/ (E$\sigma$$\^$38/) in Escherichia coli, we examined transcription from the stationary-phase promoters, katEP, bo1AP, hdeABP, csgBAP, and mcbP, in vivo and in vitro. Although these pro-moters are preferentially recognized in vivo by E$\sigma$$\^$38/, they are transcribed in vitro by both E$\sigma$$\^$38/ and E$\sigma$$\^$70/ containing the major exponential $\sigma$, $\sigma$$\^$70/. In the presence of high concentrations of glutamate salts, how-ever, oldy E$\sigma$$\^$38/ was able to efficiently transcribe from these promoters, which supports the concept that the promoter selectivity of $\sigma$$\^$38/-containing RNA polymerase is observed only under specific reaction con-ditions. The examination of 6S RNA, which is encoded by the ssr1 gene in vivo, showed that it reduced E$\sigma$$\^$70/ activity during the stationary phase, but this reduction of activity did not result in the elevation of E$\sigma$$\^$38/ activity. Thus, the preferential expression of stationary-phase genes by E$\sigma$$\^$38/ is unlikely the con-sequence of selective inhibition of E$\sigma$$\^$70/ by 6S RNA.

• Journal of the Korean Geotechnical Society
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• v.20 no.1
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• pp.101-108
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• 2004

For the last 30 years, the use of EPS as a lightweight filling material has grown significantly throughout the world. The fields of applying EPS block have also increased. The most representative example in geotechnical applications is using EPS block as a compressible inclusion that causes the reduction of static earth pressure on earth-retaining wall, bridge abutment and pipes. EPS blocks have a good workability by its lightweight characteristic and a uniform engineering property with the change of its density. Also EPS blocks have best material property as a compressible inclusion. This paper analyzes that the compressible inclusion function of EPS causes the reduction of static earth pressure on retaining wall and concrete box culvert. A series of in-situ tests were conducted to evaluate the reduction of static earth pressure using EPS inclusion. Based on in-situ test, it is found that the magnitude of static earth pressure was reduced to about 20% for the retaining wall and about 45∼53% for the box culvert compared with theoretical active earth pressure.

• Journal of the Korea Concrete Institute
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• v.17 no.2 s.86
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• pp.293-302
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• 2005

This study describes data from determination of the optimum mix proportion and site application of the mass concrete placed in bottom slab and side wall having a large depth and section as main structures of LNG in-ground tank. This concrete requires low heat hydration, excellent balance between workability and consistency because concreting work of LNG in-ground tank is usually classified by under-pumping, adaptation of longer vertical and horizontal pumping line than ordinary pumping condition. For this purpose, low heat Portland cement and lime stone powder as cementitious materials are selected and design factors including unit cement and water content, water-binder ratio, fine aggregate ratio and adiabatic temperature rising are tested in the laboratory and batch plant. As experimental results, the optimum unit cement and water content are selected under $270kg/m^3$ and $l55{\~}l60 kg/m^3$ separately to control adiabatic temperature rising below $30^{\circ}C$ and to improve properties of the fresh and hardened concrete. Also, considering test results of the confined water ratio($\beta$p) and deformable coefficient(Ep), $30\%$ of lime stone powder by cement weight is selected as the optimum replacement ratio. After mix proportions of 5cases are tested and compared the adiabatic temperature rising($Q^{\infty}$, r), tensile and compressive strength, modulus of elasticity, teases satisfied with the required performances are chosen as the optimum mix design proportions of the side wall and bottom slab concrete. $Q^{\infty}$ and r are proved smaller than those of another project. Before application in the site, properties of the fresh concrete and actual mixing time by its ampere load are checked in the batch plant. Based on the results of this study, the optimum mix proportions of the massive concrete are applied successfully to the bottom slab and side wall in LNG in-ground tank.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.8
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• pp.453-464
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• 2004

In order to solve the well-known drawback of reduced flexibility that is associate with ASIC implementations, this paper proposes a novel arithmetic unit over GF(2$^{m}$ ) for field programmable gate arrays (FPGAs) implementations of elliptic curve cryptographic processor. The proposed arithmetic unit is based on the binary extended GCD algorithm and the MSB-first multiplication scheme, and designed as systolic architecture to remove global signals broadcasting. The proposed architecture can perform both division and multiplication in GF(2$^{m}$ ). In other word, when input data come in continuously, it produces division results at a rate of one per m clock cycles after an initial delay of 5m-2 in division mode and multiplication results at a rate of one per m clock cycles after an initial delay of 3m in multiplication mode respectively. Analysis shows that while previously proposed dividers have area complexity of Ο(m$^2$) or Ο(mㆍ(log$_2$$^{m}$ )), the Proposed architecture has area complexity of Ο(m), In addition, the proposed architecture has significantly less computational delay time compared with the divider which has area complexity of Ο(mㆍ(log$_2$$^{m}$ )). FPGA implementation results of the proposed arithmetic unit, in which Altera's EP2A70F1508C-7 was used as the target device, show that it ran at maximum 121MHz and utilized 52% of the chip area in GF(2$^{571}$ ). Therefore, when elliptic curve cryptographic processor is implemented on FPGAs, the proposed arithmetic unit is well suited for both division and multiplication circuit.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.8A
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• pp.787-793
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• 2008

3GPP evolved packet system (EPS) is an all-IP based system that supports various access networks such LTE, HSPA/HSPA+, and non-3GPP networks. Recently, the support of IP flows with packet level QoS profiles was added to the requirements of the EPS. This paper proposes an adaptive modulation and coding (AMC) scheme that supports the QoS of such IP flows in the 3G LTE access network of the EPS. Defining the retransmission as a critical factor for QoS, the proposed scheme applies different maximum packet error probability $P_{max}$ to each packet when selecting the AMC transmission mode. In determining $P_{max}$, the QoS constraints and NACK-to-ACK error as well as channel condition are considered, balancing two objectives: the satisfaction of the QoS and the maximization of spectral efficiency. The simulation results show that it is able to reduce both delay violation and status report by 10%, while improving the throughput 10% in comparison with an existing scheme.

• Transactions on Electrical and Electronic Materials
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• v.13 no.3
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• pp.116-120
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• 2012

In this paper, ZnO-Epoxy nanocomposites (NEP) were prepared and epoxy composites that contain 5 wt% micro ZnO (MEP) and deliberately not well dispersed nano ZnO (NDNEP) were also prepared for purpose of comparison. The effects of the particle size and dispersion of ZnO on dielectric properties of epoxy resin were chiefly studied. Test results showed that: at a loading of 5 wt%, the three epoxy composites seem to have no significant difference on resistivity compared to epoxy resin; Dielectric constants of all the epoxy composites are also basically the same but they are bigger compared to that of the pure epoxy resin (unfilled); Dielectric dissipation factors ($tan{\delta}$) of NDNEP is greater than that of NEP and MEP. NEP has the minimum dielectric loss factor, whereas dielectric loss factors of the three epoxy composites are larger than that of the pure epoxy resin. The decreasing order of electrical breakdown strength for the three epoxy composites and for the pure epoxy resin is as follows: NEP>MEP>NDNEP>EP. Finally, in order to explain the experimental results the aggregation interface phase was proposed. Furthermore, addition of well dispersed nano filler has proved to have a positive effect on the improvement of the dielectric properties of epoxy resin.

• Smart Media Journal
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• v.5 no.3
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• pp.35-41
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• 2016

In this paper, we propose hand-gesture signal recognition based on EPS(Electronic Potential Sensor) using Deep learning model. Extracted signals which from Electronic field based sensor, EPS have much of the noise, so it must remove in pre-processing. After the noise are removed with filter using frequency feature, the signals are reconstructed with dimensional transformation to overcome limit which have just one-dimension feature with voltage value for using convolution operation. Then, the reconstructed signal data is finally classified and recognized using multiple learning layers model based on deep learning. Since the statistical model based on probability is sensitive to initial parameters, the result can change after training in modeling phase. Deep learning model can overcome this problem because of several layers in training phase. In experiment, we used two different deep learning structures, Convolutional neural networks and Recurrent Neural Network and compared with statistical model algorithm with four kinds of gestures. The recognition result of method using convolutional neural network is better than other algorithms in EPS gesture signal recognition.

• Resources Recycling
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• v.18 no.1
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• pp.58-67
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• 2009

The annual requirement of domestic waste photoresist stripper solution is about 1 trillion won level (50,000 tons) depends entirely on imports for its supplies. Nevertheless, there waste strippers which contain the impurities have been recycled or incinerated to a low level of recycle. These days the recycling technologies of the waste stripper solution has been widely studied from the view points of economy and efficiency. In this paper, the recycling technologies on patent of the waste stripper solution were analyzed. The range of search was limited within the open patents of USA (US), European Union (EP), Japan (JP), and Korea (KR) up to september, 2007. Patents have been collected using key-words searching and filtered by filtering criteria. The trends of the patents was analyzed by the years, countries, companies, and technologies.