• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.581-586
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• 2018

Cast iron manhole lids cause environmental pollution during the manufacturing process, and the work environment is very poor. In addition, if the height of the manhole cover does not match the height of the road surface, it causes considerable inconvenience and safety problems. This study proposes a height - adjustable steel manhole cover that can replace cast iron manhole covers and easily match the road surface with the upper surface of the manhole cover. Structural analysis was performed to grasp the design variable of the structure of the manhole cover, satisfying the required quality performance. To fabricate a manhole cover that satisfies the required load capacity, the optimal design for the U-shaped reinforcement structure was made. The cylindrical shape of the height adjustment part and the low frame were formed by bending the steel sheet into a circular shape and then welding. Reinforcing bars were also made by bending a steel plate. The height adjustment groove was machined by a CNC milling machine. Four prototypes were fabricated and a load bearing test was carried out, and new manhole cover was made reflecting results of the test. In the load bearing test, there was no breakage of the welded part, and deformation occurred mainly at the contact area between the groove and gusset plate. Deformation of 1 to 2.7mm occurred due to a load of 450kN. On the other hand, after removing the load, there was almost no residual deformation, and the load bearing evaluation was judged to be satisfactory because the manhole cover could be disassembled and reassembled.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.131-135
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• 2017

We developed a portable card reader for the visually impaired. In South Korea, there is insufficient development of lifestyle aids for people with disabilities. Living aids for people with disabilities are being developed using information technology, smart phones, Internet of Things(IoT) devices, 3D printers, and so on. Blind people were interviewed, which showed that the card recognition function using a currently developed smart phone app was not able to recognize the screen of the smart phone by the hand of the visually impaired, and it was inconvenient to operate. In recent years, devices that enable the visually impaired to recognize cards have been studied in foreign countries and are emerging prototypes. But what is currently available is expensive and inconvenient. In addition, visually impaired people are most vulnerable to low-income families, which makes it difficult to purchase and use expensive devices. In this study, we developed a card reader that recognizes a card using a Raspberry Pi, which is an open-source hardware that can be applied to IoT. The card reader plays it by voice and vibration, and the visually impaired can use it at a low price.

• Journal of Power Electronics
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• v.11 no.4
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• pp.408-417
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• 2011

The plug-in hybrid electric vehicles (PHEVs) are specialized hybrid electric vehicles that have the potential to obtain enough energy for average daily commuting from batteries. The PHEV battery would be recharged from the power grid at home or at work and would thus allow for a reduction in the overall fuel consumption. This paper proposes an integrated power electronics interface for PHEVs, which consists of a novel Eight-Switch Inverter (ESI) and an interleaved DC/DC converter, in order to reduce the cost, the mass and the size of the power electronics unit (PEU) with high performance at any operating mode. In the proposed configuration, a novel Eight-Switch Inverter (ESI) is able to function as a bidirectional single-phase AC/DC battery charger/ vehicle to grid (V2G) and to transfer electrical energy between the DC-link (connected to the battery) and the electric traction system as DC/AC inverter. In addition, a bidirectional-interleaved DC/DC converter with dual-loop controller is proposed for interfacing the ESI to a low-voltage battery pack in order to minimize the ripple of the battery current and to improve the efficiency of the DC system with lower inductor size. To validate the performance of the proposed configuration, the indirect field-oriented control (IFOC) based on particle swarm optimization (PSO) is proposed to optimize the efficiency of the AC drive system in PHEVs. The maximum efficiency of the motor is obtained by the evaluation of optimal rotor flux at any operating point, where the PSO is applied to evaluate the optimal flux. Moreover, an improved AC/DC controller based Proportional-Resonant Control (PRC) is proposed in order to reduce the THD of the input current in charger/V2G modes. The proposed configuration is analyzed and its performance is validated using simulated results obtained in MATLAB/ SIMULINK. Furthermore, it is experimentally validated with results obtained from the prototypes that have been developed and built in the laboratory based on TMS320F2808 DSP.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.32-38
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• 2020

Cargo train braking uses the pressure changes in the air braking pipe to operate the braking tightening and releasing service repeatedly. Air-braking release failure means partial braking caused by a failure of the variable load valve after the driver handling the brake release. This phenomenon causes wheel flaws while driving a wagon, resulting in wheel breakage or train derailment. This study developed the air-braking release failure proof valve considering the technical requirements of the railway operation corporations. In addition, a durability test of the valve was carried out using a braking performance simulator, and its operating performance was evaluated from the pneumatic history under cyclic braking conditions. The warranty life of this valve was assessed by performing 160,000 cycles of testing of 12 prototypes in accordance with the zero-failure test method, considering the number of braking cycles while driving the wagon. During the durability test, the pneumatic input time, output time, and release velocity were almost constant. The warranty life of this valve was 59,860 times the 95% confidence level, which means that it can be operated without trouble for four years when the valve is installed in the bogie of the wagon.

• Proceedings of the Korean Vacuum Society Conference
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• 1998.02a
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• pp.120-120
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• 1998

Boron nitride (BN) films have attracted a growing interest for a variety of t technological applications due to their excellent characteristics, namely hardness, c chemical inertness, and dielectrical behavior, etc. There are two crystalline phases 1551; of BN that are analogous to phases of carbon. Hexagonal boron nitride (h-BN) has a a layered s$\sigma$ucture which is spz-bonded structure similar to that of graphite, and is t the stable ordered phase at ambient conditions. Cubic boron nitride (c-BN) has a z zinc blende structure with sp3-bonding like as diamond, 따ld is the metastable phase a at ambient conditions. Among of their prototypes, especially 삼Ie c-BN is an i interesting material because it has almost the same hardness and thermal c conductivity as di없nond. C Conventionally, significant progress has been made in the experimental t techniques for synthesizing BN films using various of the physical vapor deposition 밍ld chemical vapor deposition. But, the major disadvantage of c-BN films is that t they are much more difficult to synthesize than h-BN films due to its narrow s stability phase region, high compression stress, and problem of nitrogen source c control. Recent studies of the metalorganic chemical vapor deposition (MOCVD) of I III - V compound have established that a molecular level understanding of the d deposition process is mandatory in controlling the selectivity parameters. This led t to the concept of using a single source organometallic precursor, having the c constituent elements in stoichiometric ratio, for MOCVD growth of 삼Ie required b binary compound. I In this study, therefore, we have been carried out the growth of h-BN thin f films on silicon substrates using a single source precursors. Polycrystalline h-BN t thin films were deposited on silicon in the temperature range of $\alpha$)() - 900 $^{\circ}$C from t the organometallic precursors of Boron-Triethylamine complex, (CZHs)3N:BRJ, and T Tris(dimethylamino)Borane, [CH3}zNhB, by supersonic molecular jet and remote p plasma assisted MOCVD. Hydrogen was used as carrier gas, and additional nitrogen w was supplied by either aDlIDonia through a nozzle, or nitrogen via a remote plasma. T The as-grown films were characterized by Fourier transform infrared spectroscopy, x x-ray pthotoelectron spectroscopy, Auger electron spectroscopy, x-ray diffraction, t transmission electron diffraction, optical transmission, and atomic force microscopy.roscopy.

• Fire Science and Engineering
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• v.28 no.6
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• pp.82-89
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• 2014

Disasters that destroy homes and infrastructure and cause significant financial damage are becoming more common as population centers grow. In addition, several natural disasters have resulted in a major loss of life and created countless refugees due to damage to housing. After major catastrophic disasters, it is very important that the government agencies respond to post-disaster housing issues and provide resources such as temporary housing before the full rehabilitation and reconstruction of destroyed and damaged housing. To provide affordable temporary housing for residents who may lose their homes as the result of a catastrophic disaster including storms, government agencies must develop a post-disaster housing prototype. In general, government agencies should explore several different forms of factory-built single-story, single family housing, such as modular homes, panelized homes, and precut homes. In urban cities including New York and Seoul, it is very important to provide housing which supports the demand for higher-density living spaces than single-family homes or trailers typically available due to the high population density and the desire to resettle as many residents as possible in their former neighborhoods. This study identified the urban post-disaster housing prototypes that may provide higher density housing with high quality living spaces, high air quality, and energy efficiency as well as rapid deployment. A case study of "Urban Post-Disaster Housing Prototype Program in New York" was conducted through a detailed interview process with a designer, engineer, contractor, the Office of Emergency Management (OEM) in New York, the U.S. Army Corps of Engineers (USACE), and temporary occupants. An appropriate disaster housing program that can provide living spaces for victims of disasters that keeps residents in their community and allows them to live and work in their neighborhoods was developed.

• Journal of the Korean Wood Science and Technology
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• v.34 no.1
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• pp.23-31
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• 2006

X-ray transit materials with straight path and the its intensity is proportional to the density of materials. Therefore, X-ray has been extensively used as a nondestructive evaluation (NDE) method in various fields. This study was carried out for development of a portable X-ray CT (computed-tomography) system to detect deteriorations of wood members in buildings. Based on the results of our previous study, a procedure of CT image reconstruction was established In order to verify the applicability of developed system, CT images of three wood disks were reconstructed by newly developed procedure and compared with the prototypes. From the results of this study, it was shown that the newly developed system could be used not only to determine the shape, size, and position of defects, but also to find the density distribution in cross section of wood structure members. The density distribution may be utilized to clarify the reason of wood deterioration and to provide the preventive method on how to treat or repair wood buildings. Because it was initial stage of system development, there were some limitations concerned with measuring equipment and image reconstruction algorithm. Especially, measuring time including equipment setup time was longer and measuring accuracy was lower than we expected. Therefore, we planned some additional studies on improvement of equipment and algorithm to enhance the capability of X-ray CT system.

• Archives of design research
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• v.11 no.1
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• pp.237-244
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• 1998

Rapid prototyping is an efficient method to evaluate the usability of electric home appliances. However, the use of rapid prototyping method in usability tests has not been sufficiently validated. The purpose of this study was to validate computer-generated prototypes whether they can replace real products in usability tests. The control-display panel of a refrigerator was selected for this study. Sixteen female subjects participated in a between-subjects experiment: Eight subjects of them used the real refrigerator while others used the computer-generated prototype of the refrigerator. The difference between the refrigerator and the prototype was analyzed in terms of task failure rate, task completion time, and the number of buttons pressed for three typical tasks: clock setting, selecting an operation mode for refrigerating room, and selecting an rapid freezing mode. The results of a non-parametric statistical test showed that the prototype was not significantly different from the real refrigerator. Therefore, the rapid prototyping technique can be applied to the usability tests for the simple electric home appliances such as the refrigerator.

• The Journal of the Korea Contents Association
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• v.7 no.11
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• pp.175-181
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• 2007

Design prototype is described from the stately aspect as a principle of formative art, and from the shapeable aspect of physical feature. The prototype can be a common denominator which is contained in one nation's culture, art and life, as the thing which corresponds to the daily industrial craft, architecture and art's production intention and activity with the thought and background of the culture. We have formed the design prototypes with time and space in the process which absorbs and integrates the new culture. Modern Korean design's prototype can be seen in the late Chosun. As the upper culture and sub-culture were combined, the active culture was developed. Nobody can deny that Chosun's culture and art becomes a basis of today's design and Korea's beauty. In creating the design prototype, the natural environmental factors such as topography and climate are the most important. Such natural environmental factor led the design recognition of art and craft art, as well as an architecture and indoor environment's form. Korea design produced the artisan sprite which is devoted to a moral duty and instinct as our nation's nature and emotion, and ensured the emotional process not the rational process. So, it created naturalism which accepted the material and shape. Our design prototype's path tracking as an energy of future society's new design identity, can be the important theme for our design development.

• Journal of Korea Technology Innovation Society
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• v.15 no.2
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• pp.242-261
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• 2012

Early stages of technology valuation have been often overlooked or under-represented. The early stage technologies are even riskier due to their inadequacy of commercial development and market applicability. More than 95% of patents fail to earn any revenues so that the majority of patents were valueless. Technology transfers from laboratories at universities and research institutes to industrial firms have increased to acquire value from invented technologies. Technology transfer, a process of transferring discoveries and innovations resulted from research to commercial sectors, typically comprises several steps: disclosing the discoveries and innovations, i.e., intellectual property (IP), evaluating the IP's economic prospects, securing a patent, copyright or trademark for the IP, commercializing the technology through licensing, forming a joint venture, or selling. At each of those stages in the research and development of technology, the value of technology would play a very important role of making decision on the movement toward the next step, however, the financial value of technology is not easy to determine due to a great amount of uncertainty in the course of research and development, and commercialization. This paper refers to technology embodied as devices, equipment, software or processes primarily developed at public research institutions such as universities. Sometimes it is also as the result of externally financed projects contracted with industry. Nearly always technology developed at public research entities results in laboratory prototypes. When it is required to define the technology transfer contract terms for the license of the university patrimonial rights to external funding companies or other interested parties, a question arises: what is the monetary value? In this paper, we present a method for technology valuation based on the identification of specific value points related to its development. The final technology value must be within previously defined value limits. This paper consists of the review of issues related to technology transfer and commercialization, the identification of characteristics of technologies in the early stage of technology development, the formulation of framework of methods to value the early stage technologies, and the conclusion and implication of the previous review.