• Korea-Australia Rheology Journal
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• v.16 no.4
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• pp.175-182
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• 2004

Colloidal coating solution was prepared to enhance the hydrophilic property of the film surface. Water and ethanol were used as the dispersion media and (glycidoxypropyl) trimethoxysilane (GPS) as a binder in the colloidal silica coatings. Ethylene diamine was added to the colloidal silica solution as the curing agent. The colloidal silica solution was regarded as a hard-sphere suspension model with low volume fraction of the silica particles. Rheological properties of the silica suspensions modified with GPS have been investigated as a function of pH and concentration. The acidic solution showed high viscosity change by fast hydrolysis reaction and adsorption of the organic binders on the surface of silica particles. However, the hydrolysis was slow at the basic condition and the binders combined with themselves by condensation. The viscosity change was smallest at pH 7. The viscosity increased with the curing time after adding ethylenediamine, and the increase of viscosity at low pH was higher than that at high pH. The hydrophilic properties of the coating film were investigated by the contact angle of water and film surface. The smallest contact angle was shown under the strong acidic condition of pH 2.

• Journal of Microbiology and Biotechnology
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• v.28 no.8
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• pp.1346-1351
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• 2018

Oxidoreductases are effective biocatalysts, but their practical use is limited by the need for large quantities of NAD(P)H. In this study, a whole-cell biocatalyst for NAD(P)H cofactor regeneration was developed using the economical substrate glycerol. This cofactor regeneration system employs permeabilized Escherichia coli cells in which the glpD and gldA genes were deleted and the gpsA gene, which encodes $NAD(P)^+-dependent$ glycerol-3-phosphate dehydrogenase, was overexpressed. These manipulations were applied to block a side reaction (i.e., the conversion of glycerol to dihydroxyacetone) and to switch the glpD-encoding enzyme reaction to a gpsA-encoding enzyme reaction that generates both NADH and NADPH. We demonstrated the performance of the cofactor regeneration system using a lactate dehydrogenase reaction as a coupling reaction model. The developed biocatalyst involves an economical substrate, bifunctional regeneration of NAD(P)H, and simple reaction conditions as well as a stable environment for enzymes, and is thus applicable to a variety of oxidoreductase reactions requiring NAD(P)H regeneration.

• Journal of Electrical Engineering and Technology
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• v.4 no.2
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• pp.282-286
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• 2009

This paper presents the design of a patch antenna for GPS portable devices. The antenna is designed to operate at Ll band on an FR4 PCB with a thickness of 1.6mm, a dielectric constant of 3.8 and two metallization layers. The antenna has a dimension of 49mm${\times}$36mm and operates at 1.5754GHz with a return loss of -36dB and a measured bandwidth of 250MHz.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06a
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• pp.278-281
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• 2011

Mobile devices equipped with various sensors have the potential of providing context-aware services. Location is one of the most common forms of context, which can be applied to diverse applications. In this paper, we present methods for learning and predicting users' routes between significant locations, e.g., home and workplaces, based on personal GPS data. A user's significant locations and routes between them are learned by a set of rules as well as clustering. When the user is moving, our methods can predict which of the learned routes is being taken now. After the route prediction, the user's next location can also be inferred. Our methods have been applied to the real GPS datasets from four subjects. For the next location prediction task, the achieved accuracy was 84.8%.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.401-404
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• 2007

Augustine volcano is an active stratovolcano located at the southwest of Anchorage, Alaska. Augustine volcano had experienced seven significantly explosive eruptions in 1812, 1883, 1908, 1935, 1963, 1976, and 1986, and a minor eruption in January 2006. We measured the surface displacements of the volcano by radar interferometry and GPS before and after the eruption in 2006. ERS-1/2, RADARSAT-1 and ENVISAT SAR data were used for the study. Multiple interferograms were stacked to reduce artifacts caused by different atmospheric conditions. Least square (LS) method was used to reduce atmospheric artifacts. Singular value decomposition (SVD) method was applied for retrieval of time sequential deformations. The observed surface displacements from satellite radar interferometry were compared with GPS data. Satellite radar interferometry helps to understand the surface displacements system of Augustine volcano.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2351-2353
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• 2005

본 논문은 포장도로의 표면 상태를 고성능의 레이저 변위 센서를 사용하여 정밀하게 측정하고, GPS(Global Positioning System)를 사용하여 측정 위치 데이터를 획득하는 도로 표면 측정 장비 개발에 관한 논문이다. 본 연구에서는 전체 시스템을 설계하고, 차량 주행을 모사한 실험 모형을 제작하여 실내 실험을 실시하였으며, GPS 단말기로부터 실시간으로 위치 신호를 수신하여 도로면 데이터와 연동할 수 있도록 하였다. 그리고 평가 차량의 전면에 레일(rail)을 장착하여 레이저 변위 센서가 좌우로 왕복운동이 가능하도록 하였으며, 레일을 작동시킨 상태에서 도로면을 측정해 보았다. 실험 모형의 측정 곁과는 차량이 80km/h로 주행할 때 도로 표지 타이닝(tinning)의 폭 오차 3.24%, 깊이 오차 5%였다. 차량이 정지된 상태에서 레일을 작동시켜 요철을 측정하였을 경우 레일 방향에 대한 폭 오차는 0.07%였다.

• Journal of Korean Port Research
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• v.12 no.1
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• pp.119-130
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• 1998

As a satellite positioning system, GPS is designed to provide the information on three dimensional position, velocity, and time all over the world. The purpose of this paper is to obtain what day has the best accuracy and what time has the best accuracy of measuring of forteen-twenty mimutes for effective using of MAGELLAN G.P.S NAV DLX-10 system. The result of measurement maximum deviation value from November, 1997 to March, 1998 that latitude deviation is 3' .75 and longitude deviation is 2' .1 And the result of measurement maximum deviation value during fourteen minutes of April 29, 1998 that latitude deviation is 3' .75 and longitude deviation is 1' .9. The result of measurement maximum deviation value during twenty minutes of May 6, 1998 that latitude deviation is 4' .75 and longitude deviation is 2' .1 and that is provid 3' .25, 4' .1 to May 13, 1998. So, we expect efficient use of horizontal position for navigation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.277-278
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• 2012

• Journal of Korean Society on Water Environment
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• v.29 no.3
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• pp.383-392
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• 2013

In this research, mixing behavior of the floating pollutant such as oil spill accidents was analyzed by studying the advection-diffusion of GPS floaters at water surface. The LPT (Lagrangian Particle Tracking) model of EFDC (Environmental Fluid Dynamics Computer Code) was used to simulate the motion of the GPS floater tracer. In the field experiment, 35 GPS floaters were injected at the Samun Bridge of Nakdong River. GPS floaters traveled to downstream about 700 m for 90 minutes. The field data by the GPS floater experiments were compared with the simulation in order to calibrate the parameter of LPT model. The turbulent diffusion coefficient of LPT model was determined as $K_H/hu^*$ = 0.17 from the scatter diagram. The arrival time of peak concentration and transverse diffusion from the simulation results were similar with the experiments from the concentration curves. Numerical experiments for anticipation of damage from floating pollutant were conducted in the same reach of the Nakdong River and the results show that the pollutant cloud transported to the left bank where the Hwawon pumping station is located. For this reason, it is suggested that the proper action should be needed to maintain the safety of the water withdrawal at the Hwawon pumping station.

• Electronics and Telecommunications Trends
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• v.31 no.3
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• pp.20-31
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• 2016

위성항법 보강시스템은 항법위성인 GPS 제공 항법신호를 수신 처리하여 각종 오차 성분을 제거시킴으로써 산출된 위치정확도, 시스템 가용도 및 제공신호에 대한 무결성 등이 향상됨에 따라 항공분야, 해양분야 및 차량내비 등 육상분야에서 요구하는 위치정확도뿐만 아니라 보강 및 무결정정보 등을 특정 성능 요구를 만족시킬 수 있도록 제공하는 시스템이다. GPS 신호에 대한 오차를 보강한 메시지를 활용하는 매체를 무엇을 활용하는지에 따라 구분할 수 있는데 위성을 이용하면 위성기반 보강시스템(Satellite Based Augmentation System: SBAS), 지상망을 이용하면 지상기반 보강시스템(Ground Based Augmentation System: GBAS), 비행기를 이용하면 항공기반보강시스템(Aircraft-Based Augmentation System: ABAS)으로 일컫는다. 본고에서는 위성항법 보강시스템의 현황과 그 관련 기술에 대하여 기술하고 한다.