• Current Optics and Photonics
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• v.5 no.4
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• pp.402-408
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• 2021

An off-axis system refers to an optical system in which the optical axis and normal vector at the vertex of each surface do not match. The most important specification in an optical system is its focal length. Among the various methods for measuring the focal length, the most suitable method for the off-axis system is the method that adopts magnification. However, head-mounted display (HMD) optics must be measured while considering the virtual image distance, which is not infinity owing to product characteristics. For the virtual image distance, a camera with a focusing function was used. By measuring HMD optics via this magnification method, the error generated in this measurement was 0.68% of the HMD's focal length, which is within the 1%-3% range of the conventionally permitted design error for the focal length allowed at the optical design stage. Therefore, it can be verified that the measurement accuracy of the method proposed in this study is sufficiently feasible in practice.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.1
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• pp.140-148
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• 2004

A novel rapid prototyping (RP) process, a full-automated transfer type variable lamination manufacturing process (Full-automated VLM-ST) has been developed. In the full-automated VLM-ST process, a vacuum chuck and a rectilinear motion system transfer the EPS foam material in the form of the plate with two pilot holes to the rotary supporting stage. The supplied material is then cut into an automated unit shape layer (AUSL) with a desired width, a desired length, a desired slope on the side surface, and a pair of reference shapes, which is called the guide shape (GS)’, including two pilot holes in accordance with CAD data through cutting in two steps using a four-axis synchronized hotwire cutter. Then, each AUSL is stacked by setting each AUSL with two pilot holes in the building plate with two pilot pins, and subsequently, adhesive is applied onto the top surface of the stacked AUSL by a bonding roller and pressure is simultaneously given to the bottom surface of the stacked AUSL. Finally, three-dimensional shapes are rapidly and automatically fabricated. This paper describes the method to generate guide shapes in AUSL data for the full-automated VLM-ST process. In order to examine the applicability of the method to generate guide shapes, three-dimensional shapes, such as a piston shape and a human head shape, are fabricated from the full-automated VLM-ST apparatus.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.3
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• pp.29-38
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• 2015

In this paper, scale efficiencies and relative efficiencies of R&D projects in Industrial Technology Program, sponsored by Ministry of Trade, Industry and Energy, Korea, are calculated and compared. For the process, various DEA (Data Envelopment Analysis) models are adopted as major techniques. For DEA, two stage input oriented models are utilized for calculating the efficiencies. Next, the calculated efficiencies are grouped according to their subprograms (Industrial Material, IT Fusion, Nano Fusion, Energy Resources, and Resources Technology) and recipient types (Public Enterprise, Large Enterprise, Medium Enterprise, Small Enterprise, Lab., Univ., and etc.) respectively. Then various subprograms and recipient types are compared in terms of scale efficiencies (CCR models) and relative efficiencies (BCC models). In addition, the correlation between the 1st stage relative efficiencies and the 2nd stage relative efficiencies is calculated, from which the causal relationship between them can be inferred. Statistical analysis shows that the amount of input, in general, should increase in order to be scale efficient (CCR models) regardless of the subprograms and recipient types, that the 1st and 2nd stage relative efficiencies are different in terms of the programs and recipient types (BCC models), and that there is no significant correlation between the 1st stage relative efficiencies and the 2nd stage relative efficiencies. However, the results should be used only as reference because the goal each and every subprogram has is different and the situation each and every recipient type faces is different. In addition, the causal link between the 1st stage relative efficiencies and the 2nd relative efficiencies is not considered, which, in turn, is the limitation of this paper.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.501-503
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• 2005

The improvement of load following operation of the thermal power plant is influenced to the electrical quality. Analysis of boiler, turbine, and governor system, and the study of control algorithm are preceded. The thermal power plant is operated by various control systems. In the case of faulty governor system, it takes long days to solve the problem and impossible to repair the mechanism without outage. A non-planned out-age is taken into consideration because of economical power production. In this paper, to clear the continuous swings of an old turbine governor system(YEOSU #1), the trend, the control logic, and the hydraulic mechanism are analyzed, and then the control circuit with ADAPT function and the 1st order lag circuit are inserted and modified. After that, the power plant comes to automatic governor control operation.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.4
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• pp.22-28
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• 2013

It is important to begin left ventricular assist device (LVAD) treatment at appropriate time for heart failure patients who expect cardiac recovery after the therapy. In order to predict the optimal timing of LVAD implantation, we predicted pumping efficacy of LVAD according to the severity of heart failure theoretically. We used LVAD-implanted cardiovascular system model which consist of 8 Windkessel compartments for the simulation study. The time-varying compliance theory was used to simulate ventricular pumping function in the model. The ventricular systolic dysfunction was implemented by increasing the end-systolic ventricular compliance. Using the mathematical model, we predicted cardiac responses such as left ventricular peak pressure, cardiac output, ejection fraction, and stroke work according to the severity of ventricular systolic dysfunction under the treatments of continuous and pulsatile LVAD. Left ventricular peak pressure, which indicates the ventricular loading condition, decreased maximally at the 1st level heart-failure under pulsatile LVAD therapy and 2nd level heart-failure under continuous LVAD therapy. We conclude that optimal timing for pulsatile LVAD treatment is 1st level heart-failure and for continuous LVAD treatment is 2nd level heart-failure when considering LVAD treatment as "bridge to recovery".

• Hwankyungkyoyuk
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• v.20 no.1
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• pp.62-72
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• 2007

In spite of the perceived importance of sustainable development in society, we still fails to reflect consistently our best understandings about the sustainable development and education for sustainable development. The purpose of this study is to inquire into the orientation of education for sustainable development in the 21st Century knowledge-based society. The results of this study can be summarized as follows. First, it is necessary to provide newly defined sustainable development which enables us to transform unsustainable way of life into environmentally sound and sustainable development. Education for sustainable development is defined as a basic education that have a mature understanding among the human, nature and wisdom of life. Second, we should emphasis on a system thinking, basic communication in order to encourage education for sustainable development as a learning strategy. Third, we should suggest both individual and community learning education for sustainable development. Finally, we develope knowledge system of sustainable development in accordance with the theories of knowledge management. In conclusion, it is necessary to approach education for sustainable development in the context of the knowledge-based society and the information age. It enables us enhance a new awareness and attitudes towards sustainable development. Furthermore, it is expected to develop an education program for the sustainable development of understanding.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.4
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• pp.324-332
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• 2014

In order to reveal the long-term variations of water quality in Jinhae Bay, water qualities had been monitored at 9 survey stations of Jinhae Bay during 2000~2012. The surface and bottom waters concentrations of chemical oxygen demand (COD), dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), and chlorophyll-a (Chl.-a) were higher at the survey stations of Masan Bay than the stations of other Bays. Especially, station 1 which is located at the inner area of Masan Bay had the highest values in the concentrations of COD, DIN, and Chl.-a because there were terrestrial pollutant sources near the station 1 and sea current had not well circulated in the inner area of Masan Bay. In factor analysis, the station 1 also had the highest factor values related to factors which increase organic matters and nutrients in surface and bottom waters of Masan Bay. However, the stations (st.5, st.6, st.7, st.8, and st.9) of other Bays had lower values of the factors. In time series analysis, the COD concentrations of the bottom waters at 8 stations except for station 1 distinctly decreased. However, the COD concentrations of the surface waters showed no distinct decrease trends at all stations. In the concentrations of nutrients (DIN and DIP) of both surface and bottom waters, there were tremendous decrease trends at all stations. Therefore, these distinct decrease trends of the COD in bottom waters and the nutrients in surface and bottom waters of Jinhae Bay could have been associated with water improvement actions such as TPLMS (total pollution load management system).

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.1194-1198
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• 1993

Active roll control can improve handling and ride comfort. Dynamic characteristics of the hydraulic actuators for active suspension, which can be modeled as the 1'st order time lag system, hinders the performance improvement. To overcome this shortcoming a predictive controller is designed based on 3 d.o.f. linear vehicle handling model. The effect of this controller is studied through the simulation based on 10 d.o.f. nonlinear vehicle model and the results is compared to that of feedforward controller which uses lateral acceleration as control signal.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.153-158
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• 2000

This study was carried out in order to investigate the relationship roundness of fly ashes and fluidity of fly ash cement paste. electrostatic precipitator system in coal-fired power plant have many successive collection fields in the direction of flue gas travel. In experiment, the roundness of fly ashes collected from the same location had similar values regardless of the load or boiler, and they increased going from the 1st collection filed to third collection filed in the direction of gas movement. In considering the relation between roundness of fly ashes and fluidity of fly ash cement paste, it has a high correlation.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.3
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• pp.238-242
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• 1988

It is analyzed how performance of phase-locked loop driven by photodetector current in optical receiver will be changed under the condition that Gaussian thermal noise, pattern noise and shot noise are present and the loop has the nonzero detuning frequency. The phase error variance cahnges with the circuit configuration and the produced noise models. The analyzed results are applied to the previously implemented 90.194Mbps optic system whose loop filter is the improved active noninverting 1-st order lag-lead type.