• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.150.1-150.1
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• 2014

Showerhead is used as a main part in the semiconductor equipment. The face plate flatness should remain constant and the cleaning performance must be gained to keep the uniformity level of etching or deposition in chemical vapor deposition process. High operating temperature or long period of thermal loading could lead the showerhead to be deformed thermally. In some case, the thermal deformation appears very sensitive to showerhead performance. This paper describes the methods for robust design using computational fluid dynamics. To reveal the influence of the post distribution on flow pattern in the showerhead cavity, numerical simulation was performed for several post distributions. The flow structure appears similar to an impinging flow near a centered baffle in showerhead cavity. We took the structure as an index to estimate diffusion path. A robust design to reduce the thermal deformation of showerhead can be achieved using post number increase without ill effect on flow. To prevent the showerhead deformation by heat loading, its face plate thickness was determined additionally using numerical simulation. The face plate has thousands of impinging holes. The design key is to keep pressure drop distribution on the showerhead face plate with the holes. This study reads the methodology to apply to a showerhead hole design. A Hagen-Poiseuille equation gives the pressure drop in a fluid flowing through such hole. The assumptions of the equation are the fluid is viscous-incompressible and the flow is laminar fully developed in a through hole. An equation can be expressed with radius R and length L related to the volume flow rate Q from the Hagen-Poiseuille equation, $Q={\pi}R4{\Delta}p/8{\mu}L$, where ${\mu}$ is the viscosity and ${\Delta}p$ is the pressure drop. In present case, each hole has steps at both the inlet and the outlet, and the fluid appears compressible. So we simplify the equation as $Q=C(R,L){\Delta}p$. A series of performance curves for a through hole with geometric parameters were obtained using two-dimensional numerical simulation. We obtained a relation between the hole diameter and hole length from the test cases to determine hole diameter at fixed hole length. A numerical simulation has been performed as a tool for enhancing showerhead robust design from flow structure. Geometric parameters for the design were post distribution and face plate thickness. The reinforced showerhead has been installed and its effective deposition profile is being shown in factory.

• Journal of Biosystems Engineering
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• v.39 no.1
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• pp.47-56
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• 2014

Purpose: In protected crop production facilities such as greenhouse and plant factory, farmers should be present and/or visit frequently to the production site for maintaining optimum environmental conditions and better production, which is time and labor consuming. Monitoring of environmental condition is highly important for optimum control of the conditions, and the condition is not uniform within the facility. Objectives of the paper were to investigate spatial and vertical variability in ambient environmental variables and to provide useful information for sensing and control of the environments. Methods: Experiments were conducted in a strawberry-growing greenhouse (greenhouse 1) and a cherry tomato-growing greenhouse (greenhouse 2). Selected ambient environmental variables for experiment in greenhouse 1 were air temperature and humidity, and in greenhouse 2, they were air temperature, humidity, PPFD (Photosynthetic Photon Flux Density), and $CO_2$ concentration. Results: Considerable spatial, vertical, and temporal variability of the ambient environments were observed. In greenhouse 1, overall temperature increased from 12:00 to 14:00 and increased after that, while RH increased continuously during the experiments. Differences between the maximum and minimum temperature and RH values were greater when one of the side windows were open than those when both of the windows were closed. The location and height of the maximum and minimum measurements were also different. In greenhouse 2, differences between the maximum and minimum air temperatures at noon and sunset were greater when both windows were open. The maximum PPFD were observed at a 3-m height, close to the lighting source, and $CO_2$ concentration in the crop growing regions. Conclusions: In this study, spatial, vertical, and temporal variability of ambient crop growing conditions in greenhouses was evaluated. And also the variability was affected by operation conditions such as window opening and heating. Results of the study would provide information for optimum monitoring and control of ambient greenhouse environments.

• Korean Journal of Construction Engineering and Management
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• v.17 no.4
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• pp.49-56
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• 2016

Recent research has been ongoing for modular buildings in the country and interest increases. However, the activation of modular building projects is obstructed in the construction industry. There are many reasons to identity for this obstruction but one issue should be focussed. Modular buildings require to change the existing construction production system to a new construction production system, which is factory production - transportation - erection. However, the existing project delivery system in the public sector could not be adapted for this new construction production system due to the obligation of multi prime contract use, such as electrical, communication, fire fighting contracts by Law. Therefore, modular buildings in the existing project delivery system are separately contracted by multi prime contracts and modular units composed of the buildings are contracted by an architectural prime contractor as a commodity. As results, construction costs are increased, potential quality problems are raised and the existing project delivery system is finally an obstacle not to maximize benefits of the modular buildings. In this paper, we propose a new project delivery system for the modular buildings to adapt then ew construction production system.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.2
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• pp.220-226
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• 2013

Recently, with the rapid development of factory automation and logistics system, a few workers were able to manage the broad workplace such as large vessels and warehouse. To estimate the exact location of these workers in the conventional wireless indoor localization systems, three or more fixed nodes are generally used to recognize the location of a mobile node consisting of a single node. However, these methods are inefficient in terms of node deployment because the broad workplace requires a lot of fixed nodes compared to workers(mobile nodes). Therefore, to efficiently deploy fixed nodes in these environments that need a few workers, this paper presents a novel estimation algorithm which can reduce the number of fixed nodes by efficiently recognizing the relative coordinates of two fixed nodes through a mobile node composed of three nodes. Also, to minimize the distance errors between mobile node and fixed node, rounding estimation(RE) technique is proposed. Experimental results show that the error rate of localization is improved, by using proposed RE technique, 90.9% compared to conventional trilateration in the free space. In addition, despite the number of fixed nodes can be reduced by up to 50% in the indoor free space, the proposed estimation algorithm recognizes precise location which has average error of 0.15m.

• Archives of design research
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• v.12 no.4
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• pp.89-98
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• 1999

The application of tool which has grown rapidly by the age was used for the product development, however as today the computer digitalization has been fixed to the necessary process in every factory-made mass production, making the sensitive desire of designer the digitalization through systematic, rational information database building from the planning level of product to the final mass production in such a environment change. It should satisfy a variety of needs of consumer. The enterprise that hopes to get a winner in the present age brought in computer with useful tool to process information efficiently. The computer has displayed much more excellent computation ability than human to come up to their expectation and the growth of electronic technology was possible to make the computer's high-efficiency, economy and integration. No matter what we have a good economy and integration. No matter what we have a good information there is no meaning unless we are able to use it' so we should take it out by the our need. Therefore, this paper observes a future-oriented possibility of computer & Telecommunication in information society, information-oriented design environment and the trends of minimal and integrated computer. We will improve the designer's ability to develop a novel product that have the diversification of them using application, aiming at computer utilization and image identification design strategy of product in the age of network telecommunication.

• Proceedings of the Korean Society of Laser Processing Conference
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• 1998.11a
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• pp.0-0
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• 1998

-Part I- As market needs become more various, the production of smaller quantities of a wider variety of products becomes increasingly important. In addition, in order to meet demands for more efficient production, long-term unmanned factory operation is prevailing at a remarkable pace. Within this context, laser machines are gaining increasing popularity for use in applications such as cutting and welding metallic and ceramic materials. FANUC supplies four models of $CO_2$ laser oscillators with laser power ranging from 1.5㎾ to 6㎾ on an OEM basis to machine tool builders. However, FANUC has been requested to produce laser oscillators that allow more compact and lower-cost laser machines to be built. To meet such demands, FANUC has developed six models of Slab type YAG laser oscillators with output power ranging from 150W to 2㎾. These oscillators are designed mainly fur cutting and welding sheet metals. The oscillator has an exceptionally superior laser beam quality compared to conventional YAG laser oscillators, thus providing significantly improved machining capability. In addition, the laser beam of the oscillator can be efficiently transmitted through quartz optical fibers, enabling laser machines to be simplified and made more compact. This paper introduces the features of FANUC’s developed Slab type YAG laser oscillators and their applications. - Part II - All-solid-state lasers employing laser diodes (LD) as a source of pumping solid-state laser feature high efficiency, compactness, and high reliability. Thus, they are expected to provide a new generation of processing tools in various fields, especially in automobile and aircraft industries where great hopes are being placed on laser welding technology for steel plates and aluminum materials for which a significant growth in demand is expected. Also, in power plants, it is hoped that reliability and safety will be improved by using the laser welding technology. As in the above, the advent of high-power all-solid-state lasers may not only bring a great technological innovation to existing industry, but also create new industry. This is the background for this project, which has set its sights on the development of high-power, all-solid-state lasers with an average output of over 10㎾, an oscillation efficiency of over 20%, and a laser head volume of below 0.05㎥. FANUC Ltd. is responsible for the research and development of slab type lasers, and TOSHIBA Corp. far rod type lasers. By pumping slab type Nd: YAG crystal and by using quasi-continuous wave (QCW) type LD stacks, FANUC has already obtained an average output power of 1.7㎾, an optical conversion efficiency of 42%, and an electro-optical conversion efficiency of 16%. These conversion efficiencies are the best results the world has ever seen in the field of high-power all-solid-state lasers. TOSHIBA Corp. has also obtained an output power of 1.2㎾, an optical conversion efficiency of 30％, and an electro-optical conversion efficiency of 12%, by pumping the rod type Nd: YAG crystal by continuous wave (CW) type LD stacks. The laser power achieved by TOSHIBA Corp. is also a new world record in the field of rod type all-solid-state lasers. This report provides details of the above results and some information on future development plans.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.1-8
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• 2016

Automation of inventory management in a steel plate factory was a difficult problem unresolved for a long time. And now, it is also necessary to work diligently in the steel industry on efficient inventory management of thick plates. So far, the environmental characteristics of stacked thick plates means it is not easy to apply advanced technology for their automatic identification. In this paper, we propose a thick-plate robotic scanning system based on radio-frequency identification (RFID) that can provide quick and accurate inventory management by acquiring plate information after the scanning automatically recognizes the RFID tags under difficult load conditions. This system is equipped with a crane to move the plates in a pulled-up operation. It is equipped with a plate-only linear dipole antenna only for scanning the position of the plate tag. Only the linear dipole antenna, while moving the x-axis and y-axis information, automatically identifies the tag information attached to the plate. The tag information acquired by the system is used for stockpiling and is managed by steel plate inventory control software. The effectiveness of the proposed system is verified through field performance evaluation. As a result, the recognition rate of the plate tags is 99.9% at a maximum distance of 320 cm. The developed thick-plate antenna showed excellent performance compared to an existing commercial antenna.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.26-37
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• 2019

Recently, standardization of installation progress and technology of site acceptance test(SAT) for energy storage system(ESS) are being required due to performance of ESS depending on working condition and environment even though the quality and safety of each component of ESS　is guaranteed. And also, it has been required to perform not only performance testing by H/W equipments but also performance verification by S/W tool, in order to more accurately and reliably validate the performance of the ESS in advanced countries. Therefore, this paper proposes evaluation algorithm for SAT to evaluate performance of ESS and presents modeling of SAT test equipment for ESS by using PSCAD/EMTDC. Furthermore, 30[kW] scaled portable test equipments is implemented based on the proposed algorithm and modeling. From the various simulation and test results, it is confirmed that performance of ESS related to characteristics of capacity and Round-trip efficiency, Duty-cycle efficiency, low voltage ride through(LVRT) and Anti-islanding can be accurately evaluated and that the simulation results of PSCAD/EMTDC are identical to test results of 30[kW] test equipment.

• Journal of the Korean GEO-environmental Society
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• v.12 no.3
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• pp.5-12
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• 2011

In this paper, after studying structural performance for the representative corrugated steel plate used in Korea, we proposed the optimum shape for section of corrugated steel plate considering a width of steel plates that can be produced currently in the factory. Using AISI(1986) in examination for the performance of the corrugated steel plate, we determined the mechanical limit of the optimum sections considering shear force and bending moment of corrugated steel plate and also determined the geometric limit of them considering formability, shapes and ratio between width of steel plate before forming and that after forming. As a result of examination for performance of steel plate applying algorithm for searching optimal sections algorithm developed in this study to the existing representative corrugated steel plate, allowable force and moment of inertia indicated the maximum values at bending radius 76mm and internal bending angle $50^{\circ}$. And as an application result of the optimum design system that used SS490 with 1,550mm of width and 4,700mm of length considering current production situation in Korea, we developed the new section with more than 2 times of structural performance comparing with existing corrugated steel plate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.85-91
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• 2021

The DAPA (Defense Acquisition Program Administration) has been operating the DQ mark certification since 2012 to certify the superior technology and quality of munitions. On the other hand, the current DQ mark certification can not directly provide DQ mark certification to software because it is impossible to verify the quality of software alone. Therefore, this study analyzed domestic/overseas software quality evaluation/certification standards to find a way to verify the quality of software in the DQ mark certification. Among them, the method of applying the GS certification according to the international standard ISO/IEC 25000 series to the DQ mark certification was suggested as an improvement plan, and DQ mark certification verified the quality of software and provided certification. An attempt was made to expand the certification scope of DQ mark certification. This paper proposes that the DQ mark can be given to the system software by introducing GS certification to the DQ mark certification. To this end, an improved procedure for omitting the factory audit and verification by submitting a GS certificate for product evaluation is proposed. This is expected to increase defense exports using the granted DQ mark and improve the quality of defense software products through GS certification.