• Journal of the Korean Society of Systems Engineering
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• v.9 no.2
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• pp.83-90
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• 2013

Integrated aircraft synthesis process for rapid analysis and design is described in this paper. Data flow between different analysis fields is described in details. All the data are divided into several groups according to importance and source of the data. Analysis of design requirements and certification regulations is carried out to determine baseline configuration of an aircraft. Overall design process can be divided into initial sizing, conceptual and preliminary design phases. Basic data for conceptual design are obtained from initial sizing, CAD and geometry analysis. Basic data are required input for weight, aerodynamics and propulsion analyses. Results of this analysis are used for stability and control, performance, mission, and load analysis. Feasibility of design is verified based on analysis results of each discipline. Design optimization that involves integrated process for aircraft analysis is performed to determine optimum configuration of an aircraft on a conceptual design stage. The process presented in this paper was verified to be used for light aircraft design.

• Journal of Industrial Technology
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• v.28 no.B
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• pp.111-116
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• 2008

Since the hydraulic fracturing field testing method was introduced first to Korean geotechnical engineers in 1994, there have been lots of progresses in a hardware system as well as an interpretation tool. The hydrofracturing system of first generation was the pipe-line type, and it has been developed to a wire-line system at their second generation. The current up-to-date system is more compact and is able to be operated by all-in-one system. With a progress in a hardware system, the software for analyzing in-situ stress regime has also been progressed. The shut-in pressure, which is the most ambiguous parameter to be obtained from hydrofracturing pressure curves, can now be acquired automatically from the various methods. While the hardware and software for hydrofracturing tests are being developed during the last decade, the author could accumulate the field test results which can cover the almost whole area of South Korea. Currently these field data are used widely in a feasibility study or a preliminary design step for tunnel construction in Korea. Regarding the difficulties in a site selection and a test performance for the in-situ stress measurement at an off-shore area, the in-situ stress regime obtained from the field experiences in the land area can be used indirectly for the design of a sub-sea tunnel. From the hydrofracturing stress measurements, the trend of magnitude and direction of in-situ stress field was shown identically with the geological information in Korea.

• Nuclear Engineering and Technology
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• v.52 no.4
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• pp.776-783
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• 2020

As the refueling of a sodium-cooled fast reactor is conducted by rotating part of the reactor head without opening it, the monitoring of existing obstacles that can disturb the rotation of the reactor head is one of the most important issues. This paper deals with the ultrasonic ranging technique that directly monitors the existence of possible obstacles located in a lateral gap between the upper internal structure and the reactor core in a prototype generation IV sodium-cooled fast reactor (PGSFR). A 10 m long plate-type ultrasonic waveguide sensor, whose feasibility has been successfully demonstrated through preliminary tests, was employed for the ultrasonic ranging technique. The design of the sensor's wave radiating section was modified to improve the radiation performance, and the radiated field was investigated through beam profile measurements. A test facility simulating the lower part of the upper internal structure and the upper part of the reactor core with the same shapes and sizes as those in the PGSFR was newly constructed. Several under-water performance tests were then carried out at room temperature to investigate the applicability of the developed ranging technique using the plate-type ultrasonic waveguide sensor with the actual geometry of the PGSFR's internal structures.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.3
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• pp.271-277
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• 2015

The present paper discusses about noble idea on various reactions including hydrides, hydrogen peroxide and nano-sized metal powders, which do not emit toxic materials as well as carbon dioxide. Here in this paper, the very first-ever concept that heat energy can be generated from the direct reaction between sodium borohydride and hydrogen peroxide is presented. Sodium hydride as fuel can supply hydrogen reacting with oxygen provided by the decomposition of hydrogen peroxide solution. Solid sodium borohydride can be resolved in water and treated as liquid solution for the easy handling and the practical usage although its solid powder can be directly mixed with hydrogen peroxide for the higher reactivity. The thermodynamic analysis was conducted to estimate adiabatic reaction temperatures from these materials. The preliminary experiment on the reactions conducted using sodium borohydride powder and hydrogen peroxide water solution revealed that the self-propagating reaction can occur and that its reactivity increases with an increase of hydrogen peroxide concentration.

• KIEAE Journal
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• v.6 no.1
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• pp.3-10
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• 2006

As has been expected, economic factors are a major consideration in almost every decision in building design process. Assuming that improving a lighting system, existing or proposed, will reduce operating cost, what preliminary economic guidelines can be established to determine whether any proposed investment appears cost effective? In such a case a reasonable technique to compare system costs is by life-cycle costing. Stated simply, a life-cycle cost represents the total cost of a system over its entire life cycle, that is, the sum of first cost and all future costs. This paper aims to exemplify the benefit of daylighting in term of economic consideration. Four different electric lighting system designs are proposed and a lighting control system that is continuously operating according to the level of daylight in the space has been adapted. The accumulated performance of electric and daylighting is figured out to declare the effective depth of daylight in the space. The analysis on the saving amount of lighting energy due to daylight has been undertaken in answer to the question, that is, several projects are being considered, which is the most desirable from the cost-effectiveness viewpoint. The result shows clearly that although denser layout of lighting fixtures might be more effective to interface to the level of daylight ceaselessly changeable, its economic benefit may not meet the expected criterion the reason of increased initial investment and maintenance cost for the fixtures and control hardware.

• Journal of Electrochemical Science and Technology
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• v.11 no.2
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• pp.155-164
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• 2020

Here we report our preliminary results about nickel phosphide (Ni-P) electroless coating on the surface of cellulose paper (CP) and its feasibility as the anode for lithium (Li) batteries. In particular, CP can act as a flexible skeleton to maintain the mechanical structure, and the Ni-P film can play the roles of both the anode substrate and the active material in Li batteries. Ni-P films with different P contents were plated uniformly and compactly on the microfiber strands of CP. When they were tested as the anode for Li battery, their theoretical capacity per physical area was comparable to or higher than hypothetical pure graphite and P film electrodes having the same thickness. After the large irreversible capacity loss in the first charge/discharge process, the samples showed relatively reversible charge/discharge characteristics. All samples showed no separation of the plating layer and no detectable micro-cracks after cycling. When the charge cut-off voltage was adjusted, their capacity retention could be improved significantly. The electrochemical result was just about the same before and after mechanical bending with respect to the overall shape of voltage curve and capacity.

• 한국가시화정보학회:학술대회논문집
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• 2007.11a
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• pp.105-108
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• 2007

To diagnose the vascular diseases from the viewpoint of hemodynamics, we need detailed quantitative hemodynamic information of related blood flows with a high spatial resolution of tens micrometer and a high temporal resolution in the order of millisecond. For investigating in-vivo hemodynamic phenomena of vascular circulatory diseases, a new diagnosing technique combining a medical radiography and PIV method was newly developed. This technique called 'Angiographic PIV system' consists of a medical X-ray tube, an X-ray CCD camera, a shutter module for generating double pulse-type X-ray, and a synchronizer. Through several preliminary tests, the feasibility of the Angiographic PIV technique was verified. For in-vivo applications to real blood flows, we developed tracer microcapsules, which were optimized to this system, made of a contrast material of iodine and a matrix material of PVA (polyvinylpyrrolidone). In near future, the Angiographic PIV technique will be used for understanding hemodynamic phenomena of vascular diseases and for their early detection.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.1 s.244
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• pp.87-94
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• 2006

This paper presents the hydrodynamic design and performance analysis method for a miniaturized centrifugal blood pump using three-dimensional computational fluid dynamics (CFD) code. In order to obtain the hydraulically high efficient configuration of a miniaturized centrifugal blood pump for cardiopulmonary circulation, a well-established commercial CFD code was incorporated considering detailed flow dynamic phenomena in the blood pump system. A prototype of centrifugal blood pump developed by the present design and analysis method has been tested in the mock circulatory system. Predicted results by the CFD code agree very well with in vitro hydraulic performance data for a centrifugal blood pump over the entire operating conditions. Preliminary in vivo animal testing has also been conducted to demonstrate the hemodynamic feasibility for use of centrifugal blood pump as a mechanical circulatory support. A miniaturized centrifugal blood pump developed by the hydraulic design optimization and performance prediction method presented herein shows the possibility of a good candidate for intra and extracorporeal cardiopulmonary circulation pump in the near future.

• The Journal of Korean Physical Therapy
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• v.22 no.4
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• pp.83-89
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• 2010

Purpose: The goal of this study was to investigate the feasibility for the early diagnosis of inflammatory arthritis by the reconstruction of three-dimensional photoacoustic imaging with a tissue phantom. Methods: Q-switched Nd:YAG laser (l = 532 nm) was applied to a tissue phantom to generate photoacoustic waves, and the acquired photoacoustic signals at different positions around the sample were used to recombine the distribution of the optical absorption and the images were subsequently generated through a reconstruction algorithm. Results: From the acquired photoacoustic signals, the surface andinner core of the phantom was clearly distinguished. Furthermore, the back-projection algorithm was able to reconstruct two-dimensional and three-dimensional photoacoustic images that contained the optical absorption property information of the tissue phantom. Conclusion: The results indicate that the photoacoustic imaging technique has many advantages such as high optical contrast and high acoustic resolution. The acquired images can be used for the early diagnosis of inflammatory arthritis by the structural information obtained from the region of interest.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.7
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• pp.715-720
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• 2010

We propose an electroosmosis-based air delivery scheme for polymer electrolyte fuel cells and experimentally investigate its feasibility. An electroosmotic pump under a low-frequency AC electric field is used to displace initially a volume of pump working liquids. This working liquid is then pumped into a space enclosed by a flexible membrane and the movement of the membrane delivers air to a fuel cell. We successfully demonstrated the operation of a forced-convection fuel cell using this technique. In this preliminary study, however, the power consumption of the pump exceeds the power generated by the fuel cell. We conclude this paper with a discussion of several ways to reduce the pump-to-fuel cell power ratio.