• Journal of Digital Convergence
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• v.14 no.6
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• pp.253-261
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• 2016

As many people use internet through the various programs of PC and mobile devices, the possibility of private data leak is increasing. A program should be used after checking security of information flow. Security analysis of information flow is a method that analyzes security of information flow in program. If the information flow is secure, there is no leakage of personal information. If the information flow not secure, there may be a leakage of personal information. This paper proposes a method of analyzing information flow that facilitates SAT solver. The method translates a program that includes variables where security level is set into propositional formula representing control and information flow. The satisfiability of the formula translated is determined by using SAT solver. The security of program is represented through the result. Counter-example is generated if the program is not secure.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.12
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• pp.1222-1228
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• 2008

A small satellite, DubaiSat-1 FM(Flight Model), which is based on SI-200 standard bus platform and scheduled to be launched in 2008, is being developed by Satrec Initiative and EIAST(Emirates Institution for Advanced Science and Technology). The TCS(Thermal Control Subsystem) of DubaiSat-1 FM has been designed to mainly utilize passive thermal control in order to minimize power consumption, but the active control method using heaters has been applied to some critical parts. Also, thermal analysis has been performed for DubaiSat-1's mission orbit using a thermal analysis model. The thermal design is modified and optimized to satisfy the design temperature requirements for all parts according to the analysis result. The thermal control performance of DubaiSat-1 FM is verified by thermal vacuum space simulation, consisting of thermal cycling and thermal balance test. Also, to validate the thermal modeling of DubaiSat-1 FM, comparison of test results with analysis has been performed and model calibration has been completed.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.1
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• pp.15-24
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• 2018

In this paper, we explain a method of appproximating the differentials probability using a SAT solver. It is possible to increase the probability by constructing the differential characteristic which already known to differentials with a SAT solver. We apply our method to SPECK32 and SPECK48. As a result, we introduced a SPECK32's 10-round differentials with a probability of$2^{-30.39}$, and SPECK48's 12-round differentials with probability of $2^{-46.8}$. Both differentials are new and longer round and higher probability than previous ones. Using the differentials presented in this paper, we improved attacks of SPECK32/64 to 15 round, SPECK48/72 to 16 round, SPECK48/96 to 17 round, which attack 1 more rounds of previous works.

• Journal of Korean Academy of Nursing
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• v.31 no.5
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• pp.835-845
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• 2001

This study was to identify the relationship between personality type, college admission SAT scores and GPA scores of student nurses. Method: The data was collected from 270 student nurses enrolled in a baccaleaureate program in Seoul. MBTI was used to identify students' personality and SAT score and GPA score were collected over 4 years. The collected data was analyzed by using SPSS Win. package. Result: 1. There were slightly more extrovert (E) type (54.4%) students than the introvert (I) type; more sensing (S) type (71.1%) than the intuitive (N) type. 2. The introvert type students had significantly higher SAT scores than those of the extrovert type (p=.002). 3. The judging type students had significantly higher GPA scores throughout their college years than the perceiving type. 4. There was no statistically significant relationship between SAT and GPA scores. SAT scores did not accurately predict students' academic achievement in college in this sample. Conclusion: The distribution of the personality types in the sample was different from the general population which may suggest that college admission criteria is biased toward certain personality type. Since different personality types process information and cope with the outside world differently, effective teaching strategies need to be considered for each class.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.1
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• pp.157-162
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• 2023

To NP-complete 3-SAT problem, this paper proposes a O(nm) polynomial time algorithm, where n is the number of literals and m is the total frequency of all literals in equation f. The algorithm firstly decides a truth value of a literal in sequence of previously-set priority. The priority order is as follows: a literal whose occurrence in a clause is 1(k=1), a literal which is k≥2 and whose truth value is either 0 or 1, and a literal with the minimum frequency. Then, literals whose truth value is determined are then deleted from clause T and the remaining clauses. This process is repeated l times, the number of literals. As a result, the proposed algorithm has been successful in accurately determining the satisfiability of a given equation f and in deciding the truth value of all the literals. This paper, therefore, provides not only a linear-time algorithm as a viable solution to the SAT problem, but also a basis for solving the P versus NP problem.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.11B
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• pp.1583-1594
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• 2001

In this paper, the transmission structure and procedure of a random access channel for the IMT-2000 satellite radio specification are presented. The proposed random access method has much commonality with that of the 3GPP FD specification which is a terrestrial radio interface of IMT-2000. The proposed method was designed by considering characteristics of satellite link as we71 as the commonality with the terrestrial component. A preamble consists of sub-preamble repetition and a message is transmitted along with the preamble successively. The propose method has fast indication of preamble acquisition by physical layer. The proposed method has been included in the SAT-CDMA which is a radio transmission technology Proposed by TTA, KOREA and approved as a satellite radio interface at ITU-R. Additionally, in this Paper the signaling delay for the proposed random access channel will be analyzed and it will be compared to that of the random access methods using a conventional ALOHA procedure and the 3GPP procedure in aspect of the signaling delay. When the SAT-CDMA satellite constellation at the height of about 1600 km is considered, the delay of the proposed method was estimated to 100 ms less than that of the conventional ALOHA. This delay difference increases with 7he number of retransmissions. The delay is reduced by 30 ms, compared with the 3GPP method.

• Korean Journal of Remote Sensing
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• v.27 no.5
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• pp.573-586
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• 2011

The MTF(modulation transfer function) is one of parameters to evaluate the performance of imaging systems. Also, it can be used to restore information that is lost by a harsh space environment (radioactivity, extreme cold/heat condition and electromagnetic field etc.), atmospheric effects and falloff of system performance etc. This paper evaluated the MTF values of images taken by DubaiSat-1 satellite which was launched in 2009 by EIAST(Emirates Institute for Advanced Science and Technology) and Satrec Initiative. Generally, the MTF was assessed using various methods such as a point source method and a knife-edge method. This paper used the slanted-edge method. The slantededge method is the ISO 12233 standard for the MTF measurement of electronic still-picture cameras. The method is adapted to estimate the MTF values of line-scanning telescopes. After assessing the MTF, we performed the MTF compensation by generating a MTF convolution kernel based on the PSF(point spread function) with image denoising to enhance the image quality.

• Journal of Space Technology and Applications
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• v.2 no.1
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• pp.41-51
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• 2022

CubeSat is a satellite platform that is widely used not only for earth observation but also for space exploration. CubeSat is also used in magnetic field investigation missions to observe space physics phenomena with various shape configurations of magnetometer instrument unit. In case of magnetic field measurement, the magnetometer instrument should be far away from the satellite body to minimize the magnetic disturbances from satellites. But the accommodation setting of the magnetometer instrument is limited due to the volume constraint of small satellites like a CubeSat. In this paper, we investigated that the magnetic field interference generated by the cube satellite was analyzed how much it can affect the reliability of magnetic field measurement. For this analysis, we used a reaction wheel and Torque rods which have relatively high-power consumption as major noise sources. The magnetic dipole moment of these parts was derived by the data sheet of the manufacturer. We have been confirmed that the effect of the residual moment of the magnetic torque located in the middle of the 3U cube satellite can reach 36,000 nT from the outermost end of the body of the CubeSat in a space without an external magnetic field. In the case of accurate magnetic field measurements of less than 1 nT, we found that the magnetometer should be at least 0.6 m away from the CubeSat body. We expect that this analysis method will be an important role of a magnetic cleanliness analysis when designing a CubeSat to carry out a magnetic field measurement.

• The KIPS Transactions:PartD
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• v.15D no.6
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• pp.777-784
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• 2008

Recently in the field of model checking, to overcome the state explosion problem, the method of using a SAT-solver is mainly researched. To use a SAT-solver, the system to be verified is translated into CNF and the Boolean cardinality constraint is widely used in translating the system into CNF. In BCC it is dealt with set of boolean variables, but there is no translating method of the sequence among Boolean variables. In this paper, we propose methods for translating the problem, which is extracting a subsequence with length k from a sequence of Boolean variables, into CNF formulas. Through experimental results, we show that our method is more efficient than using only BCC.

• Journal of the Korea Institute of Building Construction
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• v.18 no.5
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• pp.419-427
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• 2018

The purpose of this study is to recycle steel slag generated from the iron producing process and to use steel slag as a construction material which is currently landfilled Steel slag is subjected to aging treatment due to the problem of expansion and collapse when it reacts with water. The Slag Atomizing Technology (SAT) method developed to solve these problems of expanding collapse of steel slag. In this study, experimental study on the emergency repair mortar using the reducing slag, electric arc furnace slag and silicon manganese slag manufactured by the SAT method is Reduced slag was shown an accelerated hydration when it was replaced with rapidly-setting cement, and the rate of substitution was equivalent to 15%. It is shown that the electric furnace oxide slag is equivalent to 100% of the natural aggregate, and it can be replaced by 15-30% when the silicon manganic slag is substituted for the electric furnace oxide slag. With the above formulation, it was possible to design the rapidly repair mortar for road use. These recycling slags can contribute on achieving sustainability of construction industry by reducing the use of cement and natural aggregates and by reducing the generation of carbon dioxide and recycling waste slag.