• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.52.2-52.2
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• 2017

Recent success of gravitational wave (GW) detection by LIGO opened a new window to expand our understanding of the Universe. In addition to LIGO, several other developments are going on or under planning. However, each of these detectors has a specific sensitive frequency range. There is a missing frequency band, 0.1-10 Hz, where detectors loose sensitivity significantly due to Newtonian noise on the Earth. We introduce a plan to develop a Superconducting Low-frequency Gravitational- wave Telescope (SLGT), which can observe massive black holes in 0.1-10 Hz. The SLGT system consists of magnetically levitated six test masses, superconducting quantum interference devices (SQUIDs), rigid support frame, cooling system, vibration isolation, and signal acquisition. By taking the advantage of nearly quantum-limited low-noise SQUIDs and capacitor bridge transducers, SLGT's detection sensitivity can be improved to allow astrophysical observation of black holes in cosmological distances. We present preliminary design study and expected sensitivity, and its technical feasibility.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.3
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• pp.69-75
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• 2017

There are two types of expensive measuring instruments currently on the market shape measurement and roundness measurement instruments. As they are very expensive, from tens of millions to more than 200 million won, buying them is economically burdensome for small companies or individuals. Therefore, in order to integrate the shape and roundness measurements into a single transfer device, this study aimed to reduce the trial and error by 3D modeling and simulation, and we confirmed the feasibility of operation. Based on these outcomes, a prototype hybrid measuring instrument was fabricated. As a result of performance evaluation and comparative evaluation, we verified the feasibility of implementation and application of the hybrid measuring instrument.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.3
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• pp.307-314
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• 2015

In this paper, the embedding type novel liquid metal strain gauge was developed for measuring the deformation of wind turbine blades. In general, the conventional methods for the SHM have many disadvantages such as frequency distortion in FBG sensors, the low gauge factor and mechanical failures in strain gauges and extremely sophisticated filtering in AE sensors. However, the liquid metal filled in a pre-confined micro channel shows dramatic characteristics such as high sensitivity, flexibility and robustnes! s to environment. To adopt such a high feasibility of the liquid metal in flexible sensor applications, the EGaIn was introduced to make flexible liquid metal strain gauges for the SHM. A micro channeled flexible film fabricated by the several MEMS processes and the PDMS replication was filled with EGaIn and wire-connected. Lots of experiments were conducted to investigate the performance of the developed strain gauges and verify the feasibility to the actual wind turbine blades health monitoring.

• New & Renewable Energy
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• v.5 no.1
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• pp.32-39
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• 2009

Availability of reliable and affordable energy supply is a prerequisite for economic growth. Renewables are the third largest contributor to global electricity production after coal and natural gas and account for a share of 18%. Power generating capacity from renewables has increased to around 900GW by the year 2007. Today biodiesel fuels have been in commercial use in many countries and recently the world-wide biodiesel market has experienced considerable growth, which is partly due to various tax concession programs and other financial incentives. In Korea, biodiesel has already been used for transportation fuel, but not used for power generation fuel yet Korean government has a strategy for renewable energy propagation, especially the goal of power generation amount by renewable energy is 3% of total power production by 2012. This paper focuses on the feasibility study for adaptability and strategy of using biodiesel as power generation fuel. The study also has the plan to replace the fuel of thermal power plant, gas turbine and distributed power system. As the increase of biodiesel fuel, I look forward to environment-friendly power generation and the strategy of Renewable Portfolio Standards(RPS).

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.5
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• pp.459-464
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• 2013

Structures can be evaluated their health status by allowable loading criteria. These criteria can be determined by the maximum strain. Therefore, in order to detect this maximum strain of structures, fiber optic Bragg grating(FBG) sensor probes are newly designed and fabricated to perform the memorizing detection even if the sensor system is on-and-off. The probe is constructed with an FBG optical fiber embedded in silver epoxy. When the load is applied and removed on the structure, the residual strain remains in the silver epoxy to memorize the maximum strain effect. In this study, a commercial Al-foil bonded FBG sensor probe was tested to investigate the detection feasibility at first. FBG sensor probes with silver epoxy were fabricated as three different sizes. The detection feasibility of maximum strain was studied by doing the tensile tests of CFRP specimens bonded with these FBG sensor probes. It was investigated the sensitivity coefficient defined as the maximum strain divided by the residual strain. The highest sensitivity was 0.078 of the thin probe having the thickness of 2 mm.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.12 no.3
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• pp.9-16
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• 2016

This study had the purpose on feasibility judgment through performance forecast of wind power generation system using the cross flow vertical type wind power turbine for the situation of domestic small size wind power technology development. Wind power generation system uses the principle of venturi tube that gathers the wind through the first guide vane, and second guide vein changes the angle of the wind simultaneously by playing the role of venturi tube. After this, wind got out from the second guide vane spins the wind power turbine and has the meaning of judging on the aspect of numerical interpretation the feasibility for the small size wind power generation through wind power generation system that comes out from the back.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1603-1608
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• 2008

Powered robotic exoskeletons are currently under development for assisting or supporting human muscle power. Many applications using this system for the purpose of national defense system, medical support, and construction industry are now frequently introduced. In this paper, we proposed the exoskeletal wearable robotics for construction workers. First, we analyzed general work conditions at the construction site and set up target tasks through the datum. Then dominant muscles’ activity which is related with the defined target tasks was checked up. Herein, wearers’ intent signal generation methodology was introduced in order to effectively activate the proposed system. In the final part of this paper, we evaluated the capability and feasibility of the exoskeletal robotics by the electromyography (EMG) signal variance; demonstrated that robotic exoskeletons controlled by muscle activity could be useful way of assisting with construction workers.

• Journal of the Korean Institute of Landscape Architecture
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• v.33 no.3 s.110
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• pp.84-93
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• 2005

The purpose of this study is to analyze the economic feasibility of the construction of a new ecological park, based on the case of a plan in Yeongcheon City. For fulfilling the purpose of this study, questionnaire survey was conducted in Yeongcheon City. Based on the survey data, cost-benefit analysis is conducted. For this study, costs and benefits of the project are estimated. Then, using NPV, IRR, and B/C ratio criteria, cost-benefit analysis for this study is conducted. from the empirical cost-benefit analysis, NPV of the proposed project is estimated at 5,420 million Won, IRR is estimated at 12.16%, and B/C ratio is estimated at 1.44. Thus, it is found that the construction of a new ecological park in this area would be feasible from the economic point of view.

• Journal of Welding and Joining
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• v.17 no.4
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• pp.26-31
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• 1999

An attempt was made in this study to investigate the brazing characteristics of Zr-Be binary amorphous alloys for the development of a new brazing filler metal for joining Zircaloy-4 nuclear fuel cladding tubes. This study was also aimed at the feasibility study of rapidly solidified amorphous alloys to substitute the conventional physical vapor-deposited(PVD) metallic beryllium. The $Zr_{1-x}Be_{x}$($0.3\leq$x$\leq0.5$) binary amorphous alloys were produced in the ribbon form by the melt-spinning method. It was confirmed by x-ray diffraction that the ribbons were amorphous. The amorphous. the amorphous alloys were used to join bearing pads on Zircaloy-4 nuclear fuel cladding tubes. Using Zr-Be amorphous alloys as filler metals, it was found that the reduction in the tube wall thickness caused by erosion was prevented. Especially, in the case of using $Zr_{0.65}Be_{0.35}$ and $Zr_{0.7}Be_{0.3}$ amorphousalloys, the smooth and spherical primary $\alpha$-Zr particles appeared in the brazed layer, which was the most desirable microstructure from the corrosion-resistance standpoint.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.6
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• pp.123-132
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• 1999

This paper describes a research work of developing computer-aided design of lead frame, semiconductor, with blanking operation which is very precise for progressive working. Approach to the system is based on the knowledge-based rules. Knowledge for the system is formulated from pasticity theories, experimental results and the empirical knowledge of field experts. This system has been written in AutoLISP on the AutoCAD using a personal computer and in I-DEAS Drafting Programming Language on the I-DEAS Master Series Drafting with Workstation, HP9000/715(64). Transference of data between AutoCAD and I-DEAS Master Series Drafting is accomplished by DXF(drawing exchange format) and IGES(initial graphics exchange specification) methods. This system is composed of five modules, which are input and shape treatment, production feasibility check, strip-layout, data-conversion and die-layout modules. The process planning and Die design system is designed by considering several factors, such as complexities of blank geometry, punch profiles, and the availability of a press equipment and standard parts. This system provides its efficiecy for strip-layout, and die design for lead frame, semiconductor.