• Korean Chemical Engineering Research
• /
• v.62 no.1
• /
• pp.7-12
• /
• 2024

The durability of the catalyst support has a significant effect on the durability of proton exchange membrane fuel cells (PEMFC). The accelerated durability evaluation of the catalyst support is performed at a high voltage (1.0 to 1.5 V), and the catalyst and ionomer binder in the catalyst layer are also deteriorated, hindering the evaluation of the durability of the support. The existing protocol (DOE protocol) was improved to find conditions in which the support, which is a durability evaluation target, deteriorates further. A protocol (MDOE) was developed in which the relative humidity was lowered by 35% and the number of voltage changes was reduced. After repeating the 1.0 ↔ 1.5 V voltage change cycle, the catalyst mass activitiy (MA), electrochemical active area (ECSA), electrical double layer capacity (DLC), Pt dissolution and particle growth were analyzed. Reaching 40% reduction in mass activity, the MDOE protocol took only 500 cycles, reducing the number of voltage changes compared to the DOE method and increasing the degradation of the carbon support by 50% compared to the DOE protocol.

• Journal of Plant Biotechnology
• /
• v.33 no.1
• /
• pp.19-25
• /
• 2006

With the use of Agrobacterium and gene-gun, cold regulated gene (BN115) has been injected in Chrysanthemum leaf disc and transgenic plants have been produced successfully on the selection media containing phytohormone. To determine the presence of the transferred cold regulated gene (BN115) in the transgenic Chrysanthemum, PCR-amplification indicated the presence of that gene. Real-Time PCR for confirmation of the putative transgenic plants was established. The copy number of cold regulated gene (BN115) is extrapolated on the basis of a standard curve. Serial dilutions of known number of gene copies were in triplicates. In this diagram, PCR cycles are plotted against the fluorescence intensity. The cycle at which the fluorescence reaches a threshold cycle is inversely proportional to the starting amount of target DNA.

• Journal of Korean Society of Steel Construction
• /
• v.9 no.4 s.33
• /
• pp.489-500
• /
• 1997

The number of railway bridges in Korea reaches to about 3,000. Among them, the ratio of steel bridges is about 47%. Most of the long span railway bridges take the truss type, its number is 15 in Korea. These bridges have more than 30 years service life, it is expected that the damages of cracks and corrosion is going. Therefore, the estimation of fatigue life with random stress is considered as significant subject in maintenance. In this paper, the random stress was measured in bridges and counted the stress cycles using the rainflow counting method So, the stress range frequencies and their equivalent stress are obtained and the amplification factor for the span length, bridge types and traveling speed is assessed by the dynamic testing. From the results, the stress range of the stringer and the lower chord is higher than the other members and the characteristics of the stress histogram is varied to the loading system and the amount of the passing through trains. And the impact effects are depended on the traveling speed as well as the span length.

• Journal of Animal Science and Technology
• /
• v.50 no.4
• /
• pp.457-464
• /
• 2008

Heritability and genetic correlation for reproductive traits in Yorkshire pig breed were estimated using Bayesian method via Gibbs sampling. The data set consisted of 9,609 reproductive records at pig breeding farm in Korea. For estimating those parameters using Gibbs sampling, 5,000 cycles of ‘burn-in’ period were discarded among a total of 55,000 samples. Out of the remaining 50,000 samples, 5,000 estimates by each parameter were retained and used for analyses to avoid any correlation among adjacent samples. The reproductive trait considered in this study were total number of born piglets(TNB) and estimated by two different models. The estimated heritability and permanent environmental effect using Gibbs sampler were 0.12±0.020 and 10.9±1.63, respectively. Estimated genetic correlations considered parities as different traits were distributed from 0.99 to －0.13. Such results indicated that reproductive traits for sows should be considered as different traits.

• Clinical and Experimental Reproductive Medicine
• /
• v.26 no.2
• /
• pp.239-249
• /
• 1999

The role of amino acids in culture media for IVF-ET was examined in a total of 76 cycles. Patients received clomiphene citrate (CC) followed by hMG or GnRH-a combined with gonadotropins (FSH/hMG) for controlled ovarian hyperstimulation. Severe male (<$4{\times}10^6$ motile sperm) or age factor (>39 y) patients were excluded in this study. Pregnancy was classified as clinical if a gestational sac or fetal cardiac activity was seen on ultrasound. No significant differences were found in age, duration of infertility, follicle size, the level of $E_2$ on the day of hCG injection, the mean number of oocytes retrieved, total motile sperm count, fertilization rate and the mean number of embryos transferred between bHTF (without amino acids) and mHTF (with amino acids) groups. However, total ampules of gonadotropins were higher (p<0.01) in mHTF group than bHTF group. Significantly (p<0.05) more clinical pregnancies were recorded in mHTF group (13/30) compared with bHTF group (9/46). The multiple pregnancy rates were 11.1% in bHTF group and 7.7% in mHTF group. There were one ectopic pregnancy in mHTF group and one heterotopic pregnancy in bHTF group. Abortion rates were 22.2% in bHTF group and 7.7% in mHTF, respectively. The ongoing pregnancy or livebirth rate was significantly (p<0.05) higher in mHTF group (12/30) than bHTF group (7/46). These results suggest that the addition of amino acids in culture media is essential for culture of zygotes in vitro and adjustment of energy substrates in phosphate-free culture media appears to be beneficial for human IVF-ET procedure.

• Clinical and Experimental Reproductive Medicine
• /
• v.31 no.2
• /
• pp.95-103
• /
• 2004

Objective: To compare COH characteristics and IVF outcomes among IVF-ET patients who were treated with various therapeutic modalities for ovarian endometriomas and to propose effective pre-cyclic therapeutic modalities to improve IVF-ET outcomes in the patients with ovarian endometriomas. Methods: All cases that had undergone IVF-ET after laparoscopy between January 1997 to August 2003 were reviewed. Forty-eight patients with tubal factor were assigned to Group I. Twenty seven, 22 and 38 patients diagnosed as severe pelvic adhesion with ovarian endometriomas by laparoscopy received only medical therapy (Group II), cyst aspiration (Group III), and sclerotherapy (Group IV), respectively. Laparoscopic cystectomy was performed in 20 patients (Group V). Resistance index was measured on day administering hCG. Results: As compared with Group I, in Group II resistance index increased (p<0.05) but number of oocytes, good-quality oocyte ratio (mature and intermediate oocytes/total retrieval oocytes), fertilization rate, and embryo development rate decreased (p<0.05). In Group III fertilization rate and embryo development rate decreased (p<0.05). There was no difference between Group IV and Group I in all parameters except basal FSH which increased (p<0.05). In Group V basal FSH, and resistance increased (p<0.05) and number of oocytes and good-quality oocytes ratio decreased (p<0.05). Conclusion: Sclerotherapy is an effective therapeutic option which can be done prior to IVF-ET cycles in the patients with ovarian endometriomas. Further studies on a large scale are necessary to confirm these data.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.17 no.1
• /
• pp.15-28
• /
• 2019

In accordance with the decommissioning plan for the Kori Unit 1 NPP, the reactor coolant system will be chemically decontaminated as soon as possible after permanent shutdown. This study developed the chemical decontamination process though the development project of decontamination technology of reactor coolant system and dismantled equipment for NPP decommissioning, which has been carried out since 2014. In this study, Oxidation/reduction process was conducted using system decontamination process development equipment of lab scale and was divided into unit and continuous processes. The optimal process time was derived from the unit process, and decontamination agent and the number of process were derived through the continuous processes. Through the unit process, the oxidation process took 5 hours and the reduction process took 4 hours. As optimum decontamination agent, the oxidizing agent was $200mg{\cdot}L^{-1}$ Permanganic acid + $200mg{\cdot}L^{-1}$ Nitric acid and the reducing agent was $2000mg{\cdot}L^{-1}$ Oxalic acid. In the case of the number of processes, all oxide films were removed during the two-cycle chemical decontamination process of STS304 and SA508. In the case of Alloy600, all oxide films were removed when chemical decontamination was performed for three cycles or more.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.10 no.4
• /
• pp.81-93
• /
• 2000

In a methodological approach to improve the processing performance of modulo exponentiation which is the primary arithmetic in RSA crypto algorithm, we present a new RSA hardware architecture based on high-radix modulo multiplication and CRT(Chinese Remainder Theorem). By implementing the modulo multiplier using radix-16 arithmetic, we reduced the number of PE(Processing Element)s by quarter comparing to the binary arithmetic scheme. This leads to having the number of clock cycles and the delay of pipelining flip-flops be reduced by quarter respectively. Because the receiver knows p and q, factors of N, it is possible to apply the CRT to the decryption process. To use CRT, we made two s/2-bit multipliers operating in parallel at decryption, which accomplished 4 times faster performance than when not using the CRT. In encryption phase, the two s/2-bit multipliers can be connected to make a s-bit linear multiplier for the s-bit arithmetic operation. We limited the encryption exponent size up to 17-bit to maintain high speed, We implemented a linear array modulo multiplier by projecting horizontally the DG of Montgomery algorithm. The H/W proposed here performs encryption with 15Mbps bit-rate and decryption with 1.22Mbps, when estimated with reference to Samsung 0.5um CMOS Standard Cell Library, which is the fastest among the publications at present.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.25 no.4
• /
• pp.56-64
• /
• 2021

Leakage due to deterioration and damage is one of the major causes of volume change by freezing and thawing, and it leads micro-cracking and surface scaling in concrete structures. The deterioration of damaged concrete accelerates with the chloride attack. Thus, in the detailed guidelines for facility performance evaluation (2020), the quality of cover concrete and the freeze-thaw (FT) repetition cycle were newly suggested for concrete durability assessment. The quality of cover concrete should be evaluated by the rebound hammer test and the FT repetition cycle should be also considered in the deterioration environmental assessment. This study suggested the application of fast dynamic based nonlinear ultrasound method to monitor initial micro-scale damage under freezing and thawing environment. Concrete specimens were fabricated with different water-cement ratios (40%, 60%) and air contents (1.5% and 3.0%). The compressive strength, rebound number, relative dynamic modulus, and nonlinear ultrasound were measured with different FT cycles. The scanning electron microscopy was also performed to investigate the micro-scale FT damage. As a result, both the rebound number and the relative dynamic modulus had difficulty to detect early damage but the proposed method showed a potential to detect initial micro-scale damage and predict the FT resistance performance of concrete.

• Journal of KIISE:Computer Systems and Theory
• /
• v.32 no.6
• /
• pp.306-313
• /
• 2005

Conditional branch prediction is an important technique for improving processor performance. Branch mispredictions, however, waste a large number of cycles, inhibit out-of-order execution, and waste electric power on mis-speculated instructions. Hence, the branch predictor with higher accuracy is necessary for good processor performance. In global-history-based predictors like gshare and GAg, many mispredictions come from commit update of the history. Some works on this subject have discussed the need for speculative update of the history and recovery mechanisms for branch mispredictions. In this paper, we present a simple mechanism for recovering the branch history after a misprediction. The proposed mechanism adds an age_counter to the original predictor and doubles the size of the branch history register. The age_counter counts the number of outstanding branches and uses it to recover the branch history register. Simulation results on the Simplescalar 3.0/PISA tool set and the SPECINTgS benchmarks show that gshare and GAg with the proposed recovery mechanism improved the average prediction accuracy by 2.14$\%$ and 9.21$\%$, respectively and the average IPC by 8.75$\%$ and 18.08$\%$, respectively over the original predictor.