• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.39-41
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• 2004

This paper demonstrates the in-house development of the subsystem C&DH in a D-SAT satellite project of Astronautic Technology (M) Sdn. Bhd. (ATSB). D-SAT is a non-imaging satellite. It will carry a dosimeter as the payload for scientific objectives. Since one of the D-SAT project establishment intended objectives is to demonstrate the research and development skill of the ATSB engineers on the satellite system building, most of the subsystems of the D-SAT are developed in-house including the C&DH subsystem. C&DH subsystem plays an important role for managing data handling tasks and general operation of the satellite system. The C&DH development includes the research and study on the hardware and software design, the design of both the hardware and software, the development of the software system, the integration between the software and the hardware system and the implementation of the subsystem into the satellite system. This program allows ATSB to accomplish the engineers with expertise not only in the C&DH subsystem but other subsystems too besides developing knowledge in the management of a space project that covers not only on the technical issues but issues relating to the economic, political and legal issues.

• The KIPS Transactions:PartD
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• v.16D no.6
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• pp.911-920
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• 2009

Airbone software must comply the DO-178B standard in order to be certified by the FAA. The standard requires the unit testing of safety-critical software to meet the coverage criterion called MC/DC(Modified Condition/Decision Coverage). Although MC/DC is known to be effective in finding errors related to safety, it is also true that generating test cases which satisfy the MC/DC criterion is not easy. This paper presents a tool named MD-SAT which generates MC/DC test cases with SAT(SATisfiability) technology. It can be employed for generating diverse test cases in tools implementing various testing techniques including decision table based test, cause-effect graphing, and state-based test.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2008.10a
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• pp.8-23
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• 2008

The purpose of this study is to develop a Cross Impact System Alternatives Tree(CISAT) model necessary for selecting the interdependent R&D planning system alternatives. This model modifies System Alternatives Tree(SAT) model developed by Kwon et al.. The SAT model is composed of several functions necessary for the achievement of a final goal and several subsystems for satisfying each function. In case that the relationship of technology alternatives is interdependent, this model overlooked a relative importance derived from occurrence or nonoccurrence of the technology alternatives in the future time varience. However, a complex evaluation process within the ballot system is another disadvantage of the SAT. To solve such problems, the Cross Impact Analysis(CIA) model is applied in the SAT model so as to consider the cross impact among interdependent system alternatives.

• The KIPS Transactions:PartD
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• v.16D no.3
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• pp.371-380
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• 2009

Recently, lots of research on automated test data generation has been actively done. However, techniques for automated test data generation presented so far have been proved ineffective for programs with flag variables. It can present problems when considering embedded systems such as engine controllers that make extensive use of flag variables to record state information concerning devices. This paper introduces a technique for generating test data effectively for programs with flag variables. The presented technique transforms the test data generation problem into a SAT(SATisfiability) problem and makes advantage of SAT solvers for automated test data generation(ATDG). For the ends, we transform a program under test into Alloy which is the first-order relational logic and then produce test data via Alloy analyzer.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.5
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• pp.621-627
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• 2011

In this paper, we analysed performance for on-wafer GaN HEMT using load-pull in X-band, and studied optimum impedance point based on analysis result. We suggested method of optimum performance device by analysis of optimum impedance for solid state device on-wafer condition before packaging. The measured device is gate length 0.25um, and gate width is 400um, 800um. device 400um is performed $P_{sat}$=33.16dBm, PAE=67.36%, Gain=15.16dBm, and device 800um is performed $P_{sat}$=35.91dBm, PAE=69.23%, Gain=14.87dBm.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.1
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• pp.70-79
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• 2016

Satrec Initiative successfully developed a high-resolution electro-optical camera system, EOS-D Ver.1.0. EOS-D Ver.1.0 is the main payload of DubaiSat-2 and Deimos-2, which are developed based on the SI-300 platform of Satrec Initiative. After the launch and early operation (LEOP) of DubaiSat-2 and Deimos-2, we performed refocusing for the telescope of EOS-D Ver.1.0 to compensate for the dimensional change of its metering structure by moisture out-gassing. Before and after refocusing, we conducted the performance evaluation of thermal control system(TCS) for EOS-D Ver.1.0 using the in-orbit telemetry data. The evaluation showed EOS-D Ver.1.0 was under well-controlled thermal environment, which demonstrates TCS was designed and developed to meet all requirements.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.3
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• pp.254-261
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• 2006

The effect of enhanced geometry (pore diameter, gap width) is investigated on the pool boiling of R-123/oil mixture for the enhanced tubes having pores with connecting gaps. Tubes with different pore diameters (and corresponding gap widths) are specially made. Significant heat transfer degradation by oil is observed for the present enhanced tubes. At 5% oil concentration, the degradation is 26 to 49% for $T_{sat}=4.4^{\circ}C$. The degradation increases 50 to 67% for $T_{sat}=26.7^{\circ}C$. The heat transfer degradation is significant even with small amount of oil (20 to 38% degradation at 1% oil concentration for $T_{sat}=4.4^{\circ}C$), probably due to the accumulation of oil in sub-tunnels. The pore size (or gap width) has a significant effect on the heat transfer degradation. The maximum degradation is observed for $d_p$ = 0.20 mm tube at $T_{sat}=4.4^{\circ}C$, and for $d_p$=0.23 mm tube at $T_{sat}=26.7^{\circ}C$. The minimum degradation is observed for $d_p$=0.27 mm tube for both saturation temperatures. It appears that the oil removal is facilitated for the larger pore diameter (along with larger gap) tube. The highest heat transfer coefficient with oil is obtained for $d_p$ =0.23 mm tube, which yielded the highest heat transfer coefficient for pure R-123. The heat transfer degradation increases as the heat flux decreases.

• Journal of Aerospace System Engineering
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• v.8 no.3
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• pp.27-33
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• 2014

The CubeSat, which was first launched to verify new technologies and for educational purposes, is now widely used as an educational tool since it makes possible development of manpower through practical training to produce the satellite at low development costs. At present, research and development on the CubSat is rapidly expanding in domestic and foreign universities. As one of the final 3 teams selected in the 2013 CUBE SATELLITE CONTEST organized by the Ministry of Science, ICT and Future Planning, Chosun University is also currently conducting R & D of STEP Cube Lab, which is a CubeSat scheduled to be launched in 2015 and whose main task is to verify space-based technologies in orbit. The present paper tries to present an overview of the CubeSat of Chosun University whose development is being led by its undergraduate students, and further, introduce the strengths of the present development program for developing space experts, based on the educational achievements from the R & D.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1252-1254
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• 1998

The characteristics of linear dichroism with temperature were investigated in normally($0^{\circ}$) and $80^{\circ}$-obliquely deposited amorphous $As_{40}Ge_{10}Se_{15}S_{35}$ thin films using low temperature equipment. The saturated dichroism($D_{sat}$) of a $80^{\circ}$-obliquely deposited film shows approximately 6% which is the larger value than 4.2 % of normally($0^{\circ}$) deposited film. The $D_{sat}$ of $80^{\circ}$-deposited film was increased to 25 % at 77 K, which is four times larger than that at room temperature. The $D_{sat}$ decreased with increasing temperature and was completely disappeared at about 335K. This could be explained as the tunneling effect due to the thermal excitation of lone-pair electrons in intimate valence alternation pairs(IVAPs) which are considered to be the origin of anisotropy. The decrease of $D_{sat}$ with increasing temperature from 77K to room temperature satisfied Gaussian approximation with a standard deviation of 158K.

• 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.