• 펄프종이기술
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• 제39권1호
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• pp.8-15
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• 2007

In an effort to develop control strategies for the wet-end of paper machines, dynamic models for retention and formation processes have been developed. The retention process, including headbox total and filler consistencies, white water total and filler consistencies, the basis weight and the ash content of paper, can be modeled from first-principles (mass balances). To include the effect of wet-end chemistry variables, first-pass retention was included as a parameter dependent on operating conditions. In addition, dynamics of formation was simulated by developing an empirical model of formation and coupling with the dynamic models for the retention process. A series of experiments were performed using a pilot paper machine. The experimental results and the model predictions showed relatively good agreement.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 1999년도 Proceedings of Pre-symposium of the 10th ISWPC
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• pp.125-129
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• 1999

This paper dealt with effect of dual component and micropartical retention system on papermaking. First-pass retention under dynamic drainage condition was studied in neutral and alkaline papermaking system. Cationic starches, amphoteric starches and amphoteric polyacrylamide were added prior to high shear force, then anionic. The system is found to be very useful to inprove filler retention. For mitigating unfavorable effect of interfering sub-stances, anionic trash catcher(ATC) such as p-DADMAC was tested in this study.

• 펄프종이기술
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• 제34권5호
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• pp.86-92
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• 2002

The benefits of high performance retention systems have been long recognized by the paper maker. The inter-relation between chemical retention and drainage and their effect on paper production efficiency and paper quality is significant. The subject of this paper is a summary of recent studies comparing three microparticle programs made under highly controlled pilot and commercial paper machine conditions. The results presented in this paper suggest that, in addition to improvements in machine operation, the retention, drainage and formation program can have a marked influence on the paper quality. Improvement of the topographical characteristics of the base paper was observed when the microparticle was a colloidal borosilicate inorganic oxide.

• 동의신경정신과학회지
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• 제9권2호
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• pp.37-44
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• 1998

Purpose: This study was conducted to find out the effects od Sahyangsohapwon on learning and memory of rats.Method: In the experiment, rats were divided two groups. One was control group which was adminstered Sahyangsohapwon and the other was sample group administered placebo. Numbers of each group were 13 rats. 8-arm radial maze task was used in it, and working memory test and retention(reference memory) test were done.Before the beginning of the test, the rats were deprived of water for 24hrs.In the frist test, each of eight arm was baited with water and a rat was permitted to remain on the maze until all eight arms were entered. A working memory error was defined as revisit of any previously entered arm. When a rat made an error not exceeding one time in consecutive 3 days-performance, it was regarded as learning criteria and the test was ended. The reference memory was evaluated with total days which it took rats to pass the learning crtirtia.The second test was performed after 24 hours when the first test was over. When a rat entered 4 arms, the entrance of arm was cut off during 30 seconds.Here the number if errors which was produced during a rat find remaining 4 tracks was regarded as the index of memory.This experiment compared the number of error at the control group with that of the sample group.Result: 1. In the first test, it was shown that the sample group took 7.69${\pm}$1.11 days and the control group 9.31${\pm}$1.97 days to pass the learning criteria.There was statistically significant reference mernory development at the sample group.2. In the second test, the frequency of errors made by the two groups were 0.92${\pm}$1.32 times for the control group and 1.23${\pm}$1.59 times for the Sahyangsohapwon group. There was no difference between the groups in frequency of errors.Conclusion: It is suggested that Sahyangsohapwon has effects on the improvement of learning and memory.

• Nuclear Engineering and Technology
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• 제38권2호
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• pp.163-174
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• 2006

The $Ph{\acute{e}}bus$ FP project is an international reactor safety project. Its main objective is to study the release, transport and retention of fission products in a severe accident of a light water reactor (LWR). The FPT4 test was performed with a fuel debris bed geometry, to look at late phase core degradation and the releases of low volatile fission products and actinides. Post Test Analyses results indicate that releases of noble gases (Xe, Kr) and high-volatile fission products (Cs, I) were nearly complete and comparable to those obtained during $Ph{\acute{e}}bus$ tests performed with a fuel bundle geometry (FPT1, FPT2). Volatile fission products such as Mo, Te, Rb, Sb were released significantly as in previous tests. Ba integral release was greater than that observed during FPT1. Release of Ru was comparable to that observed during FPT1 and FPT2. As in other $Ph{\acute{e}}bus$ tests, the Ru distribution suggests Ru volatilization followed by fast redeposition in the fuelled section. The similar release fraction for all lanthanides and fuel elements suggests the released fuel particles deposited onto the plenum surfaces. A blockage by molten material induced a steam by-pass which may explain some of the low releases. The revaporisation testing under different atmospheres (pure steam, $H_2/N_2$ and steam /$H_2$) and up to $1000^{\circ}C$ was performed on samples from the first upper plenum. These showed high releases of Cs for all the atmospheres tested. However, different kinetics of revaporisation were observed depending on the gas composition and temperature. Besides Cs, significant revaporisations of other elements were observed: e.g. Ag under reducing conditions, Cd and Sn in steam-containing atmospheres. Revaporisation of small amounts of fuel was also observed in pure steam atmosphere.