• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.187-190
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• 2001

In this paper we designed a dual-frequency circular sector microstrip antenna fed microstrip line with orthogonal polarization. The operating frequencies and polarization characteristics of the proposed antenna is calculated by using a cavity model. The antenna operating at about 1.87 GHz and 2.42 GHz is fabricated and its S-parameters and radiation patterns are measured.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.740-744
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• 2003

The development of electric vehicle has been accelerated by the recent 'California Initiative' which has required increasing proportions of new vehicle in Los Angeles area to be ZEV(Zero Emission Vehicles) But, because skill of battery is feeble, ZEV regulation was postponed but that is by CO2 restriction and environmental pollution problem the latest because do development require. In the electric vehicle and hybrid electric vehicle, the battery ECU(Battery Management System, BMS) is very important and an essential equipment. The accurate state of charge(SOC) is required for the battery for hybrid electric vehicles. This paper proposes SOC algorithm for the HEV based on the terminal voltage. Also, designed and analyzed battery ECU to apply on HEV.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.45-46
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• 2016

As coal fly ash emissions have increased due to additional constructions of domestic heat power plants, the amount of embedded reject ash (Rj henceforth) is increasing as well. Most Rj is embedded, so if it is used as an alternative admixture instead of cement, embedded quantities will decrease, leading to economic and environmentally positive effects. Therefore this study conducted an experiment to contemplate the usability of Rj ground in the Los Angeles abraser, and what effects ground Rj has on the engineering properties of high compressive strength mortar. The result was that as the number of grinding turns increased, liquidity, air quantity and intensity were improved, proving Rj a possible alternative admixture to cement.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.96-97
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• 2016

As coal fly ash emissions have increased due to additional constructions of domestic heat power plants, the amount of embedded reject ash (Rj henceforth) is increasing as well. Most Rj is embedded, so if it is used as an alternative admixture instead of cement, embedded quantities will decrease, leading to economic and environmentally positive effects. Therefore this study conducted an experiment to contemplate the usability of Rj ground in the Los Angeles abraser, and what effects ground Rj has on the engineering properties of poor-mix mortar. The result was that as the number of grinding turns increased, liquidity, air quantity and intensity were improved, proving Rj a possible alternative admixture to cement.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.04a
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• pp.39-40
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• 2002

대기 중 초미세입자 (0.1 마이크론 이하)들을 최근 건강 위해성에 대한 연관성이 추정됨에 따라 도시지역 초미세입자에 대한 다각적인 연구의 필요성이 증대하고 있다. 초미세입자들은 전체 질량농토에 대한 그 기여도가 매우 낮아 수 농도와 크기분포에 의하여 보다 잘 표현되지만 도시지역 초미세입자의 수 농도 크기분포에 대한 자료는 아직 부족한 실정이다. (중략)

• Economic and Environmental Geology
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• v.23 no.4
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• pp.411-424
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• 1990

Mechanical, physical and petrographic properties of seventeen marble specimens collected from ten marble mines in Korea were investigated. Studied marbles were mainly composed of calcite, dolomite, and various amounts of serpentine, tremolite, olivine, quartz and opaque minerals. Complete and sutured textures were dominant. Compressive strength measured normal to the bedding plane is larger almost two times than that measured parallel to the bedding plane. From the results of Shore hardness test on marbles, water content was an important factor to decrease Shore hardness values. Engineering geological properties, especially, compressive strength, Young's modulus, wear resistance and water absorption could be controlled by the presence of quartz, and the type of marble texture. Water absorption-porosity, compressive strength-Young's modulus, and impact strength index-Los Angeles abrasion couples show good correlation. According to the comparative utility as commercial stone, it could be concluded that marbles from the Banglim mine, Songbo mine, Kwangdeok mine and Bongjeong mine were superior to that of other studied marbles.

• Steel and Composite Structures
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• v.8 no.4
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• pp.265-280
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• 2008

An investigation on the combined effect of foundation type, foundation flexibility, axial load and PR (semi-rigid) connections on the natural frequencies of steel frames is presented. These effects were investigated using a suitable modified FE program for cases where the foundation flexibility, foundation connectivity, and semi-rigid connections could be treated as equivalent linear springs. The effect of axial load on the natural frequency of a structure was found to be significant for slender structures subjected to high axial loads. In general, if columns of medium slenderness are designed without consideration of axial load effects, the frequency of the structure will be overestimated. Studies on the 3-story Los Angeles PR SAC frame indicate that the assumption of rigid connections at beam-column and column-base interfaces, as well as the assumption of a rigid foundation, can lead to significant errors if simplified design procedures are used. These errors in an equivalent static analysis are expected to lead to even more serious problems when considering the effect of higher modes under a non-linear dynamic analysis.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.9
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• pp.898-904
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• 2006

Ionospheric storms, caused by the interaction between Solar and geomagnetic activities, may degrade the differential GNSS(Global Navigation Satellite Systems) performance significantly, and the importance of the ionospheric storm research is growing for the GBAS(Ground-Based Augmentation System) and SBAS(Satellite-Based Augmentation System) development. In order to support Korean GNSS augmentation system development, a software tool for analyzing the regional ionosphere is being developed and its preliminary results are discussed. After brief description of the ionosphere and ionospheric storm, the research topics on the GBAS applications are discussed. The need for ionospheric spatial gradient analysis is described and some results on the ionospheric spatial gradient during recent storm periods are discussed.

• International Journal of CAD/CAM
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• v.2 no.1
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• pp.29-37
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• 2002

De-manufacturing is an entire process of collecting, disassembling, reusing, refurbishing, recycling, and/or disposing products that are obsolete or un-repairable. Designing the products for inexpensive and efficient disassembly enhances the ease of de-manufacturing. Virtual disassembly addresses the difficulty and the methods to disassemble a product in design stage rather than really disassemble a product at the end of its life cycle. Based on the virtual disassembly analysis results, design will be improved for better assembling/disassembling. This paper presents a systematic virtual disassembly methodology such as disassembly relation modeling, path/sequence automatic generation and evaluation. This paper also presents a new virtual disassembly interface paradigm via virtual reality technology for disassembly simulation in virtual environment.

• International Journal of Knowledge Content Development & Technology
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• v.3 no.2
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• pp.29-42
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• 2013

The purpose of this study is to explore the information management behaviors of undergraduate students in their dormitory rooms, using Personal Information Management (PIM) as the theoretical framework. Ethnographic methods were applied to study how students devise their own systems combining digital and traditional tools to collect, create, manipulate, organize, and manage the information they need to fulfill their roles as university students. Results show a broad diversity of behaviors influenced more by individual learning styles and preferences than high-tech gadgetry. It is proposed that just as every individual has unique learning styles and preferences, so too do we have individual information styles, and we apply our tools and gadgets in our own ways to best accommodate our own styles.