• Journal of Internet Computing and Services
• /
• v.1 no.2
• /
• pp.19-28
• /
• 2000

The scheduling problem in parallel processing systems has been a challenging research issue for decades. The problem is defined as finding an optimal schedule which minimizes the parallel execution time of an application on a target multiprocessor system. Duplication Based Scheduling (DBS) is a relatively new approach for solving the problem. The DBS algorithms are capable of reducing communication overhead by duplicating remote parent tasks on local processors. Most of DBS algorithms assume an availability of the unlimited number of processors in the system. Since the assumption may net hold in practice, the paper proposes a new scalable DBS algorithm for a target system with limited number of processors. It Is shown that the proposed algorithm with N available processors generates the same schedule as that obtained by the algorithm with unlimited number of processors, where N is the number of input tasks. Also, the performance evaluation reveals that the proposed algorithm shows a graceful performance degradation as the number of available processors in the system is decreased.

• Korean Journal of Optics and Photonics
• /
• v.15 no.3
• /
• pp.241-247
• /
• 2004

The collimator is necessary for the assembly and evaluation of high resolution satellite telescope. Traditionally, the off-axis paraboloid has been used as a collimator. However, it has some disadvantages in that it can suffer from air turbulence when the focal length of a collimator is long, which may result in some error in the measurement. In contrast, since the Cassegrain type collimator folds the beam, it occupies smaller space compared to the off-axis paraboloid for the same focal length. This can reduce the air turbulence, which can improve the measurement accuracy. In this paper, we explain the process of design and manufacturing of a diameter 450 mm Cassegrain type collimator, to evaluate the diameter 300 mm satellite telescope. After assembly of primary and secondary mirrors, the final wavefront error of the collimator was 0.07λ(λ=633 nm), which is the diffraction limit.

• Journal of the Korean Geotechnical Society
• /
• v.28 no.2
• /
• pp.5-14
• /
• 2012

CMV(Compaction Meter Value) obtained from compaction results using an accelerometer, which measures the impact on the ground and the resilient force of the ground, is compared with the other degree of compaction through regression analysis. As a result, there is no correlation between results from conventional test methods (e.g., the plate load test and field density test) and the degree of compaction evaluated by either the Geogauge or the dyanamic cone penetrometer. To assess the possibility of replacing the conventional test methods with new test methods using CMV, several degrees of compaction tests were carried out. Those results show that the CMV obtained from compaction results using an accelerometer can be used as a substitute for conventional methods to evaluate the stiffness characteristics of compacted soil.

• The Journal of the Korea Contents Association
• /
• v.17 no.9
• /
• pp.563-574
• /
• 2017

The predominant concerns of the study consist of: (1) the direct effects of social work students' evaluation toward connivers of exam-cheating on their evaluation toward connivers of corruptio ns in social welfare organizations; (2) the dual mediation effects of their concerning dysfunction of whistle-blowing and needing of protection arrangement for whistle-blowers. The notable findi ngs are as follows: First, the evaluation toward a person conniving at exam-cheating significantl y has an effect on the evaluation toward connivers committing corruptions in social welfare orga nizations($.211^{***}$). Second, the more positive evaluation for connivers of exam-cheating, the more concerning dysfunction of whistle-blowing, the less needing protection arrangement for whistle-blowers($-.191^{^{\prime}***}$). The students, concerning dysfunction of whistle-blowing more, show less neg ative evaluation toward a person, conniving at corruption in social welfare organizations($.245^{***}$). The more needing protection arrangement for whistle-blowers, the less positive evaluation regar ding whistle-blowers in the organizations($-.122^{***}$). Lastly, both mediating effects of the needing protection arrangement for whistle-blowers and concerning about dysfunction of whistle-blowing are significant so dual mediator are proved. Some practical implications are discussed based on the study's findings.

• Journal of Korean Society of Environmental Engineers
• /
• v.35 no.6
• /
• pp.394-399
• /
• 2013

The recalcitrant hairs which are accumulated in the U-trap equipped to prevent the stench from the drainage produce the phenomenon of blocking the flow of water through the home drainage pathway. The chemical dissolution solutions commercially manufactured are excessively poured into U-trap to solve this blocking problem. In this study, the specially designed instrument was developed for the experiments to cut and crush the hairs of which main component are the recalcitrant keratin proteins. The performance of the instrument for cutting and crushing hairs was investigated using experimental methods. The cutting and weighing method was used in order to obtain the average length of a large amount of hairs cut by instrument. This method is relatively simple to measure the weight of cutting hairs to obtain the average length of the fibers, the values of average length showed not greater tolerances. Also the average cutting number was defined to evaluate the performance of the cutting and crushing instruments designed for this study. We were able to apply these evaluation methods to provide the criteria to obtain the optimal structure of instrument and proper operation time in the given experimental conditions. These experimental methods and results will provide the good example to design and to analyze the various device that can be used for cutting the fibers. The cutting and crushing instrument developed in this study showed the effective abilities to cutting the hairs. The general using the cuttting and crushing instrument at every home would be helpful to prevent water environmental pollution.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.10
• /
• pp.7196-7203
• /
• 2015

The purpose of this study is to evaluate the value of the development technology for the Digital Radio Frequency Memory(DRFM), which is a core part of the aircraft jamming equipment to retransmit the jamming signals. In this study, we evaluated the values of the development technology using DTV, which is a developed methodology for the evauation of defense technology by the Defense Agency for Technology and Quality(DTaQ). From the results, the economic value for the DRFM development technology and the multiplier of public benefit considering the peculiarities of defense technology were evaluated in 854 million won and 0.7899, respectively, and the public benefit value was calculated as 675 million won. The final value of the development technology was evaluated in 1,529 million won.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.45 no.1
• /
• pp.63-70
• /
• 2017

In this paper, we design and fabricate a de-orbiter using drag-sail and evaluate deployment characteristics. Without employing an actuator to deploy, the de-orbiter is activated by the SMA wire based the release mechanism and driven by the restoring force of the tape-spring. For efficient storage and deployment of drag-sail, an origami method of original ISO flasher is chosen and low priced mylar film is used as the material of the drag-sail. In addition, through the fault tree analysis method which is one of the one-shot device reliability evaluation methods, we confirm the reliability of the de-orbiter(0.997572) and the Roller failure has the highest criticality. Finally, we find feasibility of the proposed de-orbiter through the deployment demonstration of drag-sail.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.35 no.11
• /
• pp.1191-1198
• /
• 2011

The use of a ventricular assist device (VAD) can raise the one-year survival rate without cardiac transplantation from 25% to 52%. However, malfunction of the VAD system causes 6% of VAD patients' deaths, which could possibly be avoided through the development of new VADs in which VAD malfunctions do not affect the patient's heart movement or hemodynamic state. A conventional VAD has an impeller or vane for propelling blood that can allow blood to regurgitate when the propelling force is weaker than the aortic pressure. In this paper, we developed a new pulsatile conduit-shaped VAD that has two valves. This device removes the possibility of blood regurgitation and has a small stationary area even when the pumping force is extremely weak. We estimated the characteristics of the device by measuring the outflow and the pressure of the pump in in-vitro and in-vivo experiments.

• Nuclear Engineering and Technology
• /
• v.25 no.3
• /
• pp.353-360
• /
• 1993

Many types of pipe whip restraints are installed to protect the structural components from the anticipated pipe whip phenomena of high energy lines in nuclear power plants. It is necessary to investigate these phenomena accurately in order to design the pipe whip restraints properly and/or to evaluate the acceptability of the pipe whip restraint design. Various research programs have been conducted in many countries to develop analytical methods and to verify the validity of the methods. In this study, various types of finite elements in ANSYS[1], the general purpose finite element computer program, was used to simulate the postulated pipe whips to obtain impact loads and the calculated results were compared with the specific experimental results from the sample pipe whip test for the U-shaped pipe whip restraints. Some calculational models, having the gap element or the spring element between the pipe whip restraint and the pipe line, give reasonably good transient responses of the restraint forces compared with the experimental results, and could be useful in evaluating the acceptability of the pipe whip restraint design.

• Journal of the Korean Institute of Gas
• /
• v.22 no.5
• /
• pp.124-132
• /
• 2018

The supply of renewable energy has become more vigorous due to Paris Agreement. In Korea, supply policies of renewable energy is being promoted with priority given to public buildings, so, the supply of fuel cell system that are relatively easy to install in buildings is expected to expand, so it is important that study on anti-islanding evaluation of grid-connected power conditioning system(PCS) for fuel cell. In this study, we consider that KGS AB934 PC53 in domestic certification standard of PCS for fuel cell correspond with abroad standard and analyze anti-islanding evaluation that important safety performance when connected grid. Additionally, we constructed a prototype for anti-islanding evaluation of PCS for fuel cell connected in parallel and carried out the demonstration evaluation, so, we have conducted ways that ensure safety performance in accordance with the circumstances where several fuel cell systems are installed.