• The Journal of the Acoustical Society of Korea
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• v.20 no.1E
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• pp.14-19
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• 2001

We have proposed BIST method and circuit for embedded 16M SDRAM with logic. It can test the AC parameter of embedded 16M SDRAM using the BIST circuit capable of detecting the address of a fail cell installed in an Merged Memory with Logic(MML). It generates the information of repair for redundancy circuit. The function and AC parameter of the embedded memory can also be tested using the proposed BIST method. It is possible to test the embedded SDRAM without external test pin. The total gate of the BIST circuit is approximately 4,500 in the case of synthesizing by 0.25μm cell library and is verified by Verilog simulation. The test time of each one AC parameter is about 200ms using 2Y-March 14n algorithm.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.547-550
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• 2004

An interleaved single-stage power-factor-correction (PFC) AC/DC converter is presented in this paper. The proposed converter is combined by two single-stage AC/DC converters based on flyback converter Each PFC stage operates in discontinuous conduction mode (DCM). By exploiting the interleaving technique, the input ripple current and output ripple voltage are reduced. The proposed converter complied with EN/1EC61000-3-2 harmonic regulations achieves high efficiency and low cost. The performance of the proposed converter was evaluated on a 180W $(90W\times2,\;24V,\;7.5A)$ experimental prototype.

• Progress in Superconductivity and Cryogenics
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• v.7 no.1
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• pp.47-50
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• 2005

The AC loss is an important issue in the design of the high temperature superconductor (HTS) power cables, which consist of a number of lli 2223 tapes wound on a former. In the cables, the tapes have different critical currents intrinsically. And they are electrically connected to each other and current leads. These make loss measurements considerably complex, especially for short samples of laboratory size. In this work we have prepared a multi-tape conductor composed of Bi-2223 tapes. The at losses of the conductor have experimentally investigated. The loss tests indicate that the effect of tapes critical currents on AC loss measurement in the multi tape conductor is negligible only if currents in the tapes flow uniformly Moreover, the measured tosses of the conductor are in good agreement with the sum of the transport losses in the tapes. However, in the case of non-uniform current distributions, the measured AC losses considerably depend on the current distribution parameter of the positioning of a voltage lead. Thus special cautions should be needed for the measurement of the true AC losses in the short power cable samples.

• Journal of Korea Foundry Society
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• v.38 no.5
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• pp.87-94
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• 2018

The effects of Sr and (Ti-B) additives on the tensile properties of AC4A recycled (35% scrap content) aluminum alloys were investigated. An acicular morphology of the eutectic Si phase of as-cast specimens was converted to a fibrous morphology upon the addition of Sr. Moreover, morphology of the Sr modified eutectic Si phase became finer due to a T6 heat treatment. The grain size of the ${\alpha}$-solid solution was decreased by the addition of (Ti-B) additives. Depending on the treatment conditions of the as-cast specimens, i.e., no addition, a Sr addition and a (Ti-B)+Sr addition, the tensile strength levels of the as-cast specimens were 182, 192, and 204MPa, respectively. The corresponding strengths of T6 heat-treated specimens were 293, 308, and 318MPa. Elongations of the as-cast specimens were 2.2, 3.1, and 5.6%, and the corresponding elongations of the T6 heat-treated specimens were 4.6, 6.1, and 7.6%. The percentage of the reduced section area in the tensile specimens was also increased by the Sr and (Ti-B) additives. Sr and (Ti-B) additives changed the microstructure and the distribution of defects in the castings, resulting in an improvement of the tensile properties of AC4A aluminum alloys. According to our test results, recycled (35% scrap content) AC4A aluminum alloy met all of the KS requirements of the tensile strength and elongation values of AC4A aluminum alloy except for the elongation value of the one specimen condition, in this case the as-cast no-addition condition.

• Research in Plant Disease
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• v.24 no.3
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• pp.213-220
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• 2018

We classified the previously reported antagonistic strains of Sorangium cellulosum into 5 subspecies (A-E). Four strains were antagonistic to Botrytis cinerea (AB group) and two strains were antagonistic to Colletotrichum acutatum (AC group). According to the genetic and sequential analyses with standard genes, xynB1, bglA2, groEL1 for grouping, all strains of AB group were belonged to subspecies C and all strains of AC group were belonged to subspecies D. In addition, high pressure liquid chromatography with the culture filtrates confirmed the genetic results, because AB group had peaks with retention time at 20-22.5 minutes, whereas AC group had no peak. There was positive relationship ($R^2=0.9652$) between the control values of infecting B. cinerea on cherry tomatoes and the main peak areas of chromatograms among the four isolates of AB group. From the subspecies results of AB group, the main peak of KYC 3270 was expected to be epothilone D. However the retention times of the standard of commercial epothilone D and the main peak of KYC 3270 culture filtrate were different as 9.9 and 11.581 min., respectively. Finally, the antagonistic metabolite of AB group was inferred as 7-ketone epothilone D.

• Transactions on Electrical and Electronic Materials
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• v.7 no.5
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• pp.224-229
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• 2006

Many studies have been done on the application of residual charge measurement in cable degradation diagnosis. In this paper, the behavior of residual charges measured with water-tree degraded XLPE sheets and cable are discussed. At charge injection process, the charge is injected by applying dc voltage as a conventional method, suddenly cut-off ac voltage or impulse voltage. Therefore the residual charge is influenced by the applying process. At charge release process, transient dc current flows when applying ac high voltage and also ac high voltage superimposed to dc low voltage. From the results, new diagnosis method is suggested.

• Transactions on Electrical and Electronic Materials
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• v.7 no.5
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• pp.262-266
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• 2006

The insulation diagnostic test and the AC breakdown test were performed under off-line using the 3.3 kV class induction motor which have been served for 10 years. These tests were conducted in means of nondestructive and destructive test. In this paper, we compared the correlation between the nondestructive and destructive test. Furthermore we setup an experimental condition with moisture and compared the insulation characteristics between moist and dry sample. From the results of the nondestructive and destructive test, it was found that the second AC current, which is the previous step of insulation breakdown, suddenly increased at a point of around 8.5 kV. The insulation breakdown of moist sample occurred at 12-14 kV, which is 4-5 kV lower than dry sample.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.7
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• pp.1206-1213
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• 2010

The case that HVDC system is connected to the strong AC network has little the considering problems. However, because there are many problems(example for voltage stability, inertia and low frequency resonance) in case of connecting the weak AC system, a detailed attentions are needed. In particular, because HVDC system can control the flow of AC network freely, have to contain the range of stability and safe operation range. This paper deals with HVDC control algorithms, which are operated within 1 second on viewpoint of time domain, that is, transient stability. The target of HVDC introduced in this paper is Jindo-Cheju HVDC system, which will be operated at 2011. And the introduced algorithm can be actually implemented to Jindo-Cheju HVDC system.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.33 no.1 s.60
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• pp.7-10
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• 2007

The interaction between polymers and surfactants was investigated by means of rheological and surface tension measurements. The polymers used in this study were acrylates/$C_{10-30}$ alkyl acrylate crosspolymer (AC) and ammonium acryloyldimethyltaurate/VP copolymer (AV). And the surfactants were PEG-40 hydrogenated castor oil (HC) and polysorbate 60 (P60). HC and P60 made the micelles intervening between AC polymers, resulting in the increase of viscosity. However, HC showed a similar behavior over the wider range of surfactant concentration than P60. Regarding of surface tensions in the same range of surfactant concentration, AC/HC solution showed the area of increasing surface tension with surfactant concentration in contrast to the AC/P60 solution showing no increasing area. It is assumed that the micelles between AC/HC were formed so cooperatively and strongly that the surfactants located at the surface originally moved to the micelles.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.7
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• pp.626-630
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• 2007

The AC loss is an important issue in the design of the high temperature superconductor (HTS) power cables and fault current limiters. In these applications, a cylindrical HTS conductor is often used. In commercialization of these apparatuses, AC loss is a critical factor but not elucidated completely because of complexities in its measurement, e.g. non-uniform current distribution and phase difference between currents flowing in an individual HTS tape. We have prepared two cylindrical conductors composed of a Bi-2223 tape with different critical current density. In this paper, the AC loss characteristics of the conductors have been experimentally investigated and numerically analyzed. The result show that the measured losses for two conductors are not dependent on both arrangements and contact positions of a voltage lead. This implies that most of loss flux is only in the conductors. The loss for the Bi-2223 conductor with low critical current density is in good agreement with the calculated loss from Monoblock model, whereas the loss measured for the Bi-2223 conductor with high critical current density doesn't coincide with the loss calculated from the Monoblock model. The measured loss is also different from numerically calculated one based on the polygon model especially in low transport current.