• Journal of the Korean earth science society
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• v.27 no.2
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• pp.177-187
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• 2006

Due to a lack of reproducibility and visibility of the conventional equipment for westerly wave simulation, it is difficult to have indoor experiments at high school that show the stream of Hadley cell. A modified improvement of the old one improves the problem. The side wall and bottom of the new equipment is made by copper and acrylic resin, respectively, in order to clarify the difference between the water temperature inside and outside of the water tank. The equipment also has a high quality digital record for generating exact analysis of the results. And we also carried out several experiments that relate theoretical and experimental aspection of westerly wave. Temperature Detected Sheet (TDS) in flow visualization unit provides not only visual information of liquid flow, but also clear understanding of the relation between upper and lower wind flow structure. And the liquid stream simulated in indoor experiment using proposed equipment is commensurate with westerly wave in real atmosphere. The efficiency of educational properties of the proposed equipment is verified indirectly by Likert Scales survey of high school teachers.

• Fire Science and Engineering
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• v.29 no.4
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• pp.81-88
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• 2015

A low-cost device using the light-extinction method was developed to measure the optical smoke density in various fire experiments in the present study. The relative measurement accuracy of low-cost device was evaluated through the comparison of optical density measured by a high-cost standard device consisting of He-Ne laser, photo detector and various optical components. The low-cost device was composed of laser module, photocell and acrylic board. From the experiments using a smoke generator can be easily adjusted the smoke concentration, it was found that the low-cost device could measure the smoke density within the range of ${\pm}10%$, compared to the standard device. In addition, the reliability of low-cost device was also confirmed in the experiment using a polyethylene flame. Finally, it is expected that the low-cost device developed with real-time measurement and simple installation for measuring the smoke density will be used instead of the high-cost standard device.

• Journal of Aerospace System Engineering
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• v.17 no.2
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• pp.94-102
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• 2023

A nylon wire holding and release mechanism (HRM) has been widely used for deployable applications of CubeSat owing to its simplicity and low cost. In general, structural safety of solar panel with an HRM has been designed by performing structural analysis under a launch environment. However, previous studies have not performed thermal analysis for HRM in an on-orbit environment. In this study, Launch and Early Orbit Phase (LEOP) thermal analysis was performed to evaluate thermal stability of the mechanism in the orbital thermal environment of the pogo pin-based HRM applied to CubeSat. In addition, the effectiveness of the thermal design and performance of the pogo pin-based HRM were verified through a thermal vacuum test.

• Transactions of the KSME C: Technology and Education
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• v.3 no.2
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• pp.131-140
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• 2015

The mono-ski for the paraplegia designed to skiing is formed as seat bucket on the sled. The impact force transferred by snow surface during skiing is absorbed by the leg joints of normal human, but it is transferred to the human body on the seat when using mono-ski. Most of commercially available mono-ski have absorbing device and link mechanism between seat and ski mount in order to complement it. In this study we developed the comfort evaluation model that could provide skiing simulation of mono-ski with hydraulic damper and analyzed vibrational acceleration occurred during skiing uneven surface. The evaluation method used in this study is the international standard BS6841. We evaluated comfort performance of mono-ski in accordance with nozzle adjustment of hydraulic damper.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.1
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• pp.103-108
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• 2014

The flash memory which is exploited on hand-held devices such as smart phones is a non-volatile storage and has the benefit that it can store mass data at a small sized chip. To process queries on the mass data stored in the flash memory, the index scheme should be exploited. However, since the write operation of the flash memory is slower than the read operation and the overwrite is not supported, it is required to reevaluate the performance of the index and find out the drawbacks. In this paper, we evaluate the performance of a space division typed index scheme on the flash memory. To do this, we implement the fixed grid file and measure the average speeds of the query and update processing on a various condition and compare the value of the flash memory with that of the magnetic disk.

• Progress in Medical Physics
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• v.9 no.3
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• pp.143-154
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• 1998

The image intensifier is the key component which determines the imaging characteristics in a fluoroscopic imaging system. A system performance program for clinical evaluation of two image intensifiers, that is simple, non-invasive and time effective, was described. Tests were grouped into three headings: x-ray generator, image quality, and collimation. For the x-ray generator, the kVp accuracy and the automatic exposure control operation were compared. Low- and high-contrast resolution measurements, and mesh pattern study belong to the image quality tests and those tests were performed for the video monitor and photospot images. For the collimation, usable field diameter and image distortion of image intensifiers were measured and quantified. The procedures and the results are hoped to be used for the clinical evaluation of system performance and/or acceptance tests for image intensifiers.

• Journal of the Korea Organic Resources Recycling Association
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• v.5 no.2
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• pp.29-37
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• 1997

Because food waste have high moisture content, landfill or incineration is not most suitable. The reuse of food waste by composting contribute to solve resourse, environmental, aglicultural problems. The purpose of this research is to optimise operating conditions and to develop new microorganisms for recycling of food waste by ultilizing small-scale composting equipment. The reduction rate of food waste was 75~85% by weight, and it was coincided with moisture reduction. When initial moisture was 25%, 45% and 60%, C/N ratio on based net weight was 9.8, 10.7 and 11. 8, respectively. And it was suitable for composting. But, The developed microorganism, PNU2, was better than existing commercial seed in the activity based on $CO_2$ concentration.

• Journal of IKEEE
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• v.14 no.3
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• pp.173-181
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• 2010

The high flowability performance evaluation device for the concrete is the device which was designed to compensate from the incorrect data detection of the viscosimetry examination of the existing concrete. As for the existing concrete viscosimetry method, the measuring data for a viscosity are very irregular by the point of view of an experimenter and a supervisor, Therefore there were some problems to have many different opinions by a small numerical value difference according to the job characteristic. In this paper, we suggested some mechanism to compensate the problem and some driving electronics including the related algorithm, and the communication structure with wireless sensor network between the devices and users are also presented. The effectiveness of the suggested method was verified with a real experiment.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.2223-2231
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• 2010

Recently, an important physical device of transportation, such as car, railroad, ship and aircraft has changed into electronic control unit. According to accident reports, the most of car accidents are caused by faults of embedded software loaded to computer control unit. The facts implies that the test to find defects in embedded software haven't performed sufficiently. As a result, it is necessary to establish the test procedures of embedded software based on safety assessment criteria. The objective of this proposal is to provide a unit test procedure complied with the safety assessment criteria for the embedded software. In addition, an effective unit testing procedure and defect analysis methods are proposed and a testing procedure using a safety criteria built-in tool is presented.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.325-330
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• 2006

The container terminal is the unified transportation system which connects between a land transportation and a sea transportation. This system has many subsystems such as ship operation, yard transfer operation, yard storage system, gate operation, and information manage system. This paper presents a method of modeling a simulator with which user can evaluate the efficiency of the equipment and allocation policies in the container terminal. The final purpose is to estimate the efficiency of each equipments and the distribution policies. In a design step in the simulator development. We suggest the Object Oriented method with which the developer can easily design, because the object oriented method has the advantages of reusability and modularity.