• International conference on construction engineering and project management
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• 2007.03a
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• pp.625-634
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• 2007

Energy-saving is one of important issues in multi-family housing projects in South Korea. According to the study by Yu et al. (2002), the balcony conversion causes energy loss approximately one and a half times. Therefore, it is important to select the economical glass type in the balcony window. In order to identify the most economical glass type of balcony conversion in multi-family housing projects, the most typical type of the multifamily housing projects in the metropolitan area was selected as a candidate project. The selected candidate project has been simulated using ENERGY-10 program to estimate the heat load by the different five types of glasses as well as their life cycle cost analysis (LCCA) using present worth method. Finally, sensitivity analysis has been conducted to determine the most economical glass types under a different discount rate (interest rate) and service life of building.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.1
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• pp.46-50
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• 1990

Heteroface AlGaAs/GaAs drift solar cells with an active area conversion efficiency of 15.9% under one sun and AM 1.5 condition have been grown by molecular beam epitaxy(MBE). These drift solar cells have graded doping profiles in the base and emitter regions. The cells have a short circuit current density (Jsc) of 19.00 mA/cm\ulcorner an open circuit voltage(Voc) of 0.93 V, and f fill factor(FF) of 0.78, respectively. Conventional solar cells with fixed doping profiles were also grown by MBE for comparison with the drift solar cells. Even though the fabrication cost of MBE grown solar cell is higher, the expected highest conversion efficiency of the single or multiple cells could compensate for the increased cost, particularly in case of space applications.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.372-376
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• 2001

Due to several advantages of Pulse Width Modulation(PWM) Converter, such as unity power factor operation, elimination of low-order harmonics and regeneration of motor braking energy to source, the application range of PWM Converter has been rapidly extended in industrial application. Nowadays, vector control algorithm and space vector PWM(SVPWM) method are applied to improve the performances of PWM Converter, but vector control algorithm and SVPWM require to use Microprocessor and other digital devices in hardware, causing costly and somewhat large dimension system. In every practical application of energy conversion equipments, the design and implementation should be carried out considering cost and performance. High performance and low cost is the best choice for energy conversion equipments. So, this paper presents the practical design method and implementation results of 3-phase PWM Converter with analog hysteresis current controller, and verifies the performances of unit power factor operation and energy regeneration operation via experimental results.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.2121-2124
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• 2008

The total length of Korean railway network is about 3,300km. Since it is of great scale in system view point, the systemization of GIS-based information system requires so much cost and time. One of the difficulties is due to the fact that GIS-based information system requires the feature database for GIS, which is generally built manually from many as-built drawing files. In order to build-up the feature database for GIS with ease, this study suggests the automatic data conversion from electronic drawings to make feature database for GIS. The proposed method can be applied to build large-scale railway facility management system at lower cost.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.730-733
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• 2008

In this paper, a novel CII method using a depth conversion technique is proposed. The proposed method can move a far 3D object near lenslet array and reduce the computation cost dramatically. To show the usefulness of the proposed method, we carry out the preliminary experiment and its results are presented.

• Solar Energy
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• v.2 no.1
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• pp.33-48
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• 1982

A planetary boundary layer model has been modified to study the feasibility of siting the wind energy conversion systems over Jejudo island. Our objective is to demonstrate a numerical model that is simple enough to be economical in terms of computational cost and contains most of the mesoscale processes occurring in the planetary boundary layer at the same time. Simulated fields of atmospheric parameters are compared favorably with available climatological data and interpreted in terms of physical phenomena occurring.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.16.2-16.2
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• 2009

Developing a low cost printing material that can replace silver for the formation of a conducting pattern is an important issue in printed electronics. We report a novel approach using a non-oxidized copper material during the printing and sintering process under ambient conditions, which was previously considered unachievable. An attempt was made to understand the conversion process of cuprous oxide nanoparticle aggregates on metallic copper crystals through chemical reduction in the solution phase. The detailed mechanism for this conversion, including the role of the surfactant and crystal growth, was examined.

• ETRI Journal
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• v.30 no.1
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• pp.33-46
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• 2008

This paper presents the experimental results of a low-power low-cost RF transceiver for the 915 MHz band IEEE 802.15.4b standard. Low power and low cost are achieved by optimizing the transceiver architecture and circuit design techniques. The proposed transceiver shares the analog baseband section for both receive and transmit modes to reduce the silicon area. The RF transceiver consumes 11.2 mA in receive mode and 22.5 mA in transmit mode under a supply voltage of 1.8 V, in which 5 mA of quadrature voltage controlled oscillator is included. The proposed transceiver is implemented in a 0.18 ${\mu}m$ CMOS process and occupies 10 $mm^2$ of silicon area.

• The Journal of the Korea Contents Association
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• v.20 no.2
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• pp.424-434
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• 2020

The purpose of this study is to investigate the effects of selection factors which include accessibility, trade area, spatiality, convenience, reliability, assurance on satisfaction. Also, the relationship among satisfaction, conversion cost, and reuse intention was examined. The survey was conducted for college students who had used coffee shops in the last month and 247 copies were used for the analysis. The study model was analyzed by the basic statistical analysis, factor analysis, reliability analysis, and structural model analysis using SPSS 18.0 and AMOS 18.0. As a result of analysis, it was confirmed that customer satisfaction was influenced by factors in order of assurance, accessibility, commerciality, reliability, and spatiality. Also, satisfaction and conversion cost have a significant effect on reuse intention. The result shows that the satisfaction of selection factors increases student customer's behavioral intentions and ultimately contributes to the improvement of coffee shop performance. Therefore, a coffee shop targeting college students needs a lot of interest in the taste of coffee, price, various menus and accessibility, trade area, and large space.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.3
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• pp.240-244
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• 2011

The high cost of crystalline silicon solar cells has been considered as one of the major obstacles to their terrestrial applications. Spin on doping (SOD) is presented as a useful process for the manufacturing of low cost solar cells. Phosphorus (P509) was used as an n-type emitters of solar cells. N-type emitters were formed on p-type EFG ribbon Si wafers by using a SOD at different spin speed (1,000~4,000 rpm), diffusion temperatures ($800^{\circ}C{\sim}950^{\circ}C$), and diffusion time (5~30 min) in $N_2+O_2$ atmosphere. With optimum condition, we were able to achieve cell efficiency of 14.1%.