• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.16 no.3
• /
• pp.331-337
• /
• 2018

The decommissioning of nuclear power plants is generally executed in five steps, including preparation, decontamination, cutting/demolition, waste disposal and environmental restoration. So, for efficient decommissioning of nuclear power plants, worker safety, effects compared to cost, minimization of waste, possibility of reuse, etc., shall be considered. Worker safety and measurement technology shall be secured to exert optimal efficiency of nuclear power plant decommissioning work, for which accurate measurement technology for systems and devices is necessary. Typical In-Situ methods for decommissioning of nuclear plants are CZT, Gamma Camera and ISOCS. This study used ISOCS, which can be applied during the decommissioning of a nuclear power plant site without collecting representative samples, to take measurements of the S/G Water Chamber. To validate the measurement values, Microshield and the GEANT4 code was used as the actual method were used for modeling, respectively. The comparison showed a difference of $1.0{\times}10^1Bq$, which indicates that it will be possible to reduce errors due to the influence of radiation in the natural environment and the precision of modeling. Based on the research results of this paper, accuracy and reliability of measurement values will be analyzed and the applicability of the direct measurement method during the decommissioning of NPPs will be assessed.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.6A
• /
• pp.600-606
• /
• 2004

An interleaving delay diversity scheme is investigated in this paperand the applications in the multi-code WCDMA system along with antenna selection diversity is proposed. The proposed algorithm utilizes interleaving and delayed duplicated transmission mechanism to mitigate the effect of noise and fading. The interleaved signal and the original signal are both transmitted at intervals to obtain time diversity without any increase in required capacity. By adjusting the number of retransmissions of the information signal properly, the system achieve the receive diversity efficiently. For transmission power efficiency the proposed system also applies antenna selection diversity. By computer simulation, it has been shown that the proposed algorithm achieves better performance than the conventional algorithms by more than 2dB.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.13 no.5
• /
• pp.400-410
• /
• 1988

In this paper, a fast synchronization system using SAW TDL matched filter and SAW recirculation loop not only for acquisition but also tracking in the direct sequence spread spectrum communication receiver in case of low SNR was designed and its characteristics were investigated. When signal of 16dB SNR was inputed at the receiver, the PN code of the receiver could be synchronized from the extracted signal for synchronization through SAW TDL matched filter and SAM recirculation loop for 30 recirculations. And the average synchronization time of this system was calculated. From the results, we found that this synchronization system could achieve faster synchronization of PN codes in the receiver under the circumstances of low SNR than that of using only matched filter.

• Nuclear Engineering and Technology
• /
• v.13 no.2
• /
• pp.63-72
• /
• 1981

The change in the design-basis refueling strategy caused by the unexpected nuclear fuel failures may result in discharging intact fuel assemblies which were irradiated in the positions symmetric to the failed ones in addition to the failed ones in order to maintain the symmetric power shape in the reactor core. In this work an attempt is made to reuse the intact fuel assemblies which were discharged before reaching the design turnup in the above-described situation so as to improve the fuel utilization. The TDCORE code is used to estimate the flux and power distribution, and the RELOAD-II code for searching the optimal loading pattern with the minimum assembly radial power peaking factor. For the case of the Ko-ri unit 1, its third cycle turnup could be extended to 11,648 MWD/MTU by reusing the four low-burned fuel assemblies removed at the end of the first cycle, and then the loading pattern is searched to the equilibrium cycle.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.15 no.5
• /
• pp.47-57
• /
• 2005

For economic reasons, even though there are some security problems, the commands of re-initializing and writing patch code are widely used in smart cards. The current software tester has difficulty in detecting these trapdoor commands because trapdoors are not published and programmed sophisticatedly. Up to now the effective way to detect them is to completely reveal and analyze the entire code of the COS with applications such as the ITSEC. It is, however, a very time-consuming and expensive processes. We propose the new detecting approach of trapdoors in smart cards using timing and power analysis. With our experiments, this paper shows that the proposed approach is more practical than the current methods.

• The KIPS Transactions:PartD
• /
• v.8D no.6
• /
• pp.705-714
• /
• 2001

The computing systems of today expanded business trade and distributed business process Internet. More and more systems are developed from components with exactly reusability, independency, and portability. Component based development is focused on advanced concepts rater than passive manipulation or source code in class library. The primary component construction in CBD. However, lead to an additional cost for reconstructing the new component with CBD model. It also difficult to serve component information with rapidly and exactly, which normalization model are not established, frequency user logging in Web caused overload. A lot of difficult issues and aspects of Component Based Development have to be investigated to develop good component-based products. There is no established normalization model which will guarantee a proper treatment of components. This paper elaborates on some of those aspects of web application to adapt user requirement with exactly and rapidly. Distributed components in this paper are used in the most tiny size on network and suggest the network-addressable interface based on business domain. We also discuss the internal and external specifications for grasping component internal and external relations of user requirements to be analyzed. The specifications are stored on Servlets after dividing the information between session and entity as an EJB (Enterprise JavaBeans) that are reusable unit size in business domain. The reusable units are used in business component through query to get business component. As a major contribution, we propose a systems model for registration, auto-arrange, search, test, and download component, which covers component reusability and component customization.

• KIPS Transactions on Computer and Communication Systems
• /
• v.2 no.5
• /
• pp.217-222
• /
• 2013

Return-Oriented Programming(ROP) is an advanced code-reuse attack like a return-to-libc attack. ROP attacks combine gadgets in program code area and make functions like a Turing-complete language. Some of previous defense methods against ROP attacks show high performance overhead because of dynamic execution flow analysis and can defend against only certain types of ROP attacks. In this paper, we propose Indirect Branch Target Address Verification (IBTAV). IBTAV detects ROP attacks by checking if target addresses of indirect branches are valid. IBTAV can defends against almost all ROP attacks because it verifies a target address of every indirect branch instruction. Since IBTAV does not require dynamic execution flow analysis, the performance overhead of IBTAV is relatively low. Our evaluation of IBTAV on SPEC CPU 2006 shows less than 15% performance overhead.

• Nuclear Engineering and Technology
• /
• v.14 no.3
• /
• pp.138-147
• /
• 1982

A theoretical basis for analysis of plutonium-hearing fuel in a thermal nuclear power reactor has been established. The analysis of UO$_2$-PuO$_2$ fueled, light water moderated uniform lattice experiments has been performed. A unit cell program, KARATE, which is based on the theoretical models of GAM and THERMOS with some modifications, has been developed to generate a few-group cross-sections. These cross-sections are subsequently used in the diffusion theory code, KIDD, to compare the calculated values of the effective multiplication factor with the measured. The average value of the effective multiplication factor for 41 selected critical experiments is estimated to be 0.9997 with standard deviation of 0.43%. This illustrates the fact that KARATE/KIDD system can be effectively used for the analysis of uniform lattices of UO$_2$-PuO$_2$fuels.

• Fire Science and Engineering
• /
• v.15 no.1
• /
• pp.100-107
• /
• 2001

A Interior material, a main cause of fire-growth and generating toxic gas when it burns, should be dealt with great care in life safety design. Nonetheless, it has been used recklessly with undue attention to its contribution to fire in particular in entertainment occupancy and causes many victims in fire. Therefore, this study attempts to examine the current use of interior material in Korea and find out what to be improved and enhanced in terms of related regulations. Based on the comparison and analysis of the Korea regulation with those of advanced nations, suggestions are made for an effective and efficient improvement and complement to the current system. What can be suggested from this study are as follows. The use of interior material should be controlled under the unified regulation of fire-safety codes. Code should be set up so that the current construction enforcement should be applied in retroactive to those entertainment buildings that obtained a license prior to the implementation of the system certifying that the building is fire-resistant and fire-protective. The legislation should be made to control the fire-protection facilities of small-sized, underground entertainments. It should be obliged to present the blueprint displaying the use of interior material at the time of changing occupancy. Or, it should be compelled to report changes that go way without permit to the administrative office. A compulsory provision should be set up to have a fire-resistant performance to movable furniture. The classification index designating the fire hazard of interior material by flame spread rate and smoke toxicity and its test method should be established.

• Aerospace Engineering and Technology
• /
• v.2 no.1
• /
• pp.213-222
• /
• 2003

Some analytical methods to analyze low-velocity impact force history of composite laminated structures used in aerospace vehicles are reviewed. A classical method used at initial research of low-velocity impact problem in 1980s was reviewed on its physical meaning, and the approximate method assuming the shape of impact force history as a sinusoidal wave was reviewed. A parametric study on contact constant and exponent in contact law was performed in order to analyze an effect on impact force history, and finally its was understood that impact force history could be analyzed accurately even though the linearized contact law was used. Also, in this paper it was shown that impact problem could be analyzed simply and easily using a commercial finite element code.