• Journal of the Korean Society of Safety
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• v.28 no.3
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• pp.123-128
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• 2013

The Advanced Power Reactor Plus(APR+), which is a GEN III+ reactor based on the APR1400, is being developed in Korea. In order to enhance the safety of the APR+, a passive auxiliary feedwater system(PAFS) has been adopted in the APR+. The PAFS replaces the conventional active auxiliary feedwater system(AFWS) by introducing a natural driving force mechanism while maintaining the system function of cooling the primary side and removing the decay heat. As the PAFS completely replaces the conventional AFWS, it is required to verify the cooling capacity of PAFS for the core damage frequency(CDF) evaluation. For this reason, this paper discusses the cooling performance of the PAFS during transient accidents. The test case and scenarios were picked from the result of the sensitivity analysis in APR+ Probabilistic Safety Assessment(PSA). The analysis was performed by the best estimate thermal-hydraulic code, RELAP5/.MOD3.3. This study shows that the plant maintains the stable state without the core damages under the given test scenarios. The results of PSA considering this analysis' results shows that the CDF values are decreased. The analysis results can be used for more realistic and accurate performance of a PSA.

• Journal of Information Technology Services
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• v.16 no.1
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• pp.73-82
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• 2017

Recently in-memory data stream processing has been actively applied to various subjects such as query processing, OLAP, data mining, i.e., frequent item sets, association rules, clustering. However, finding regular periodic patterns of events in an infinite data stream gets less attention. Most researches about finding periods use autocorrelation functions to find certain changes in periodic patterns, not period itself. And they usually find periodic patterns in time-series databases, not in data streams. Literally a period means the length or era of time that some phenomenon recur in a certain time interval. However in real applications a data set indeed evolves with tiny differences as time elapses. This kind of a period is called as a pseudo-period. This paper proposes a new scheme called FPMH (Finding Periods using Multiple Hash functions) algorithm to find such a set of pseudo-periods over a data stream based on multiple hash functions. According to the type of pseudo period, this paper categorizes FPMH into three, FPMH-E, FPMH-PC, FPMH-PP. To maximize the performance of the algorithm in the data stream environment and to keep most recent periodic patterns in memory, we applied decay mechanism to FPMH algorithms. FPMH algorithm minimizes the usage of memory as well as processing time with acceptable accuracy.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.3
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• pp.173-179
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• 2010

In a HLW repository, the buffer is exposed to an elevated temperature due to a radioactive decay and geochemical conditions for a long time and such a hydrothermal condition may cause a significant loss of its barrier function. This study carried out hydrothermal tests with a domestic smectite clay to investigate the changes in the expandibility, layer charge, and cation exchange capacity of the smectite. When the temperature and potassium concentration in solution was increased for the hydrothermal treatments, the expandibility decreased, the layer charge negatively increased, and the CEC also decreased.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.3159-3168
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• 2014

Interevent Time Definition(IETD) is essential in CSOs(Combined Sewer Overflows) tank design for the treatment of non-point source pollution. However, existent rainfall analysis can not calculate total amout of non-point source pollution. For deviding continuous rainfall events, therre are several IETD calculating methods. In this research, After calculate IETD by existents methods, problem of results is identified as existents method. To supplement these problems, new method using exponential decay function is suggested. The confidence range of ${\lambda}$ is estimated.

• Journal of KIISE:Databases
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• v.28 no.4
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• pp.620-632
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• 2001

This paper proposes a mediator system which can provide a view management function in the today's heterogeneous computing environment including operating system database management systems and other software. while most mediators use view modification mechanism only, the use of view materialization is also considered in this research. In order to optimize the management cost for materialized views the proposed method applies a decay factor for modeling the access behaviors of views In other words, the most recently access pattern gets the highest attention in the optimization process all the necessary it with the CORBA.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.10
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• pp.3333-3354
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• 2022

The 5G Core Network (5GC) is an essential part of the mobile communication network, but its security protection strategy based on the boundary construction is difficult to ensure the security inside the network. For example, the Network Function (NF) mutual authentication mechanism that relies on the transport layer security mechanism and OAuth2.0's Client Credentials cannot identify the hijacked NF. To address this problem, this paper proposes a trust model for 5GC based on NF interaction behavior to identify malicious NFs and improve the inherent security of 5GC. First, based on the interaction behavior and context awareness of NF, the trust between NFs is quantified through the frequency ratio of interaction behavior and the success rate of interaction behavior. Second, introduce trust transmit to make NF comprehensively refer to the trust evaluation results of other NFs. Last, classify the possible malicious behavior of NF and define the corresponding punishment mechanism. The experimental results show that the trust value of NFs converges to stable values, and the proposed trust model can effectively evaluate the trustworthiness of NFs and quickly and accurately identify different types of malicious NFs.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.49.5-50
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• 2021

We report the optical follow-up observations of three long γ-ray burst events, GRB 201020A, GRB 201103B and GRB 210104A by the network of telescopes in the SomangNet project. We show light curves, color evolution and SED evolution, and fit them to a single power law function to derive decay index and compare their properties with other long GRBs samples. Also, we show a good observational example that 0.4-1m class telescopes in SomangNet have potential to catch dim light from high red shift object (R>22 mag) by deep imaging. In conclusion, we found that three GRBs have optical afterglow properties of long GRB and our results are consistent with the reports of high energy analysis.

• Geomechanics and Engineering
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• v.14 no.6
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• pp.545-552
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• 2018

Blast-induced ground vibrations by a significant amount of explosives may cause many problems for mining slope stability. Geological discontinuities have a significant influence on the transmission of dynamic pressure of detonation and according to their position relative to the slope face may have damaging or useful impacts on the slope stability. In this study, the effect of geological discontinuities was investigated by modelling a slope with geological discontinuities through applying the dynamic pressure in three-dimensional discrete element code (3DEC). The geological discontinuities in four states that generally apperceived in mine slopes are considered. Given the advantages of the pressure decay function defined by some researcher, this type of function was used to develop the pressure-time profile. The peak particle velocities (PPV) values were monitored along an axis by utilization of Fish programming language and the results were used as an indicator to measure the effects. As shown in the discontinuity-free model, PPV empirical models are reliable in rocks lacking discontinuities or tightly jointed rock masses. According to the other results, the empirical models cannot be used for the case where the rock mass contains discontinuities with any direction or dip. With regard to PPVs, when the direction of discontinuities is opposite to that of the slope face, the dynamic pressure of detonation is significantly damped toward the slope direction at the surface of discontinuities. On the other hand, when the discontinuities are horizontal, the dynamic pressure of detonation affects the rock mass to a large distance.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.spc1
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• pp.94-109
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• 1996

Antioxidants of sesame have been reported to cure and prevent various diseases by means of diverse physiological activities, prevention of acidification in organisms, prevention of acidification and decay of lipids, cholesterol depression, preventive effects on chemical breast cancer, skin beauty and senescence inhibition, and so on. Recognizing their significance to health and disease prevention, researchers in Japan and America have given so much importance to study antioxidants in the last decade. In addition, they are actively pursuing studies on production, processing for food use and development of new varieties that have high antioxidant content. Recently, researchers in Korea have shown the same interest and have conducted similar studies, however, the importance of the following basic issues must be recognized to guide in future activites : First, improvement of sesame quality must be done to raise the contents of not only the fat and fatty acid but also sesamin, sesamolin and sesaminol glucoside. For the use of these components it is necessary to study the gentic pattern and individual selections developed from minimum sample size and fast lipid analysis techniques. Second, sesaminol of sesame has a remarkable function in preventing acidification and so sesame can be utilized as a food that prevents or delays aging caused by automatic acidification of fat. Therefore, for maximum medicinal benefit from sesame oil there is a need to develop food materials having new medicinal functions. Third, the sesamin and sesamolin content of sesame germplasms collected in Korea showed lower ranges of $0.04\~0.68$ percent and $0.08\~0.68$ percent respectively, while Japanese germ-plasm showed 1.9 percent maximum content of seasmin. Thus, germplasm collection and analysis of worldwide genetic resources are urgently needed.

• Journal of the Korean Institute of Intelligent Systems
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• v.11 no.6
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• pp.477-486
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• 2001

In this paper , we study the problem of designing TS(Takagi-Sugeno) fuzzy controllers for the systems that can be approximated or represented by the TS fuzzy model. The main strategy used in this paper is the inverse optimal approach, in which the cost function is determined later than the Lyapunov function and its corresponding control input satisfying the design requirements such as stability, decay rate, and robustness against uncertainty. This approach is useful because it yields controllers satisfying the inherent robustness of optimal controllers as well as the considered design goals. The design procedures established in this paper are all in the from of solving LMIs(Iinear matrix inequalities). Since the LMIs arising in the design procedures can be solved within a given tolerance by the interior point methods. the design method of the paper are efficient in practice. The applicability of the proposed design procedures is demonstrated by design examples.