• Radiation Oncology Journal
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• v.24 no.2
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• pp.138-143
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• 2006

Purpose: To analyze the long-term stability of Farmer-type cylindrical ionization chambers by calibration factor provided from the KFDA (Korea Food Drug Administration) Materials and Methods: The cylindrical ionization chambers used in this study were the PTW 30001 (30006), 30013, 30002, 30004, 23333, the Capintec PR06C, the WE 2571, the Exradin A12 and the Wellhofer FC65G (IC70). We were analyzed that the $N_k$ and $N_{D.W}$ calibration factor for the cylindrical chambers and compared between the measured $N_{D.W}$ and calculated $N_{D.W}$ calibration factor. Results: We have observed that the long-term stability of the PTW 30013 (30006), the Wellhofer FC65G (IC70) and the NE 2571 has varied within 0.2%. The measured $N_{D,W}$ calibration factor was about 1.0% higher than the calculated $N_{D,W}$ that determined by the $N_k$ calibration factor. Conclusion: The study has evaluated that the long-term stability of the cylindrical chambers through analysis for the $N_k\;and\;N_{D,W}$ calibration factor. It has contributed to the improvement of clinical electron dosimetry in radiotherapy centers.

• Membrane Journal
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• v.18 no.1
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• pp.65-74
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• 2008

NOM and fine particles are the main target materials in water treatment using membranes. Particularly, humic substances extracted from soils are frequently used in many fundamental studies representing natural organic matter in raw water for drinking water treatment. In this study, ultrafiltration (UF) of artificial humic water and natural river water was conducted and the characteristics of removal efficiency and permeability were compared. In the UF of river water, the transmembrane pressure increased in the same pattern with that of 5 mg/L humic water. For the removal of organic matter and fine particles, however, two types of feed water had shown different trends. Kaolin particles and humic acids added to artificial water were better removed, while colloids and organics in natural water were relatively poorly removed. From the $UV_{254}$ and GPC analyses, it seemed that the hydrophobicity and size of humic substances contributed to the greater removal of organic matter. The UF membrane applied for humic water also showed a higher flux recovery by caustic chemical cleaning than that for river water.

• Journal of the Korean Geosynthetics Society
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• v.14 no.4
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• pp.97-104
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• 2015

When carrying out design for soft ground improvement before reclamation of dredged soil, it is very important to appropriately evaluate design parameters such as compression index and undrained strength in order to estimate optimum construction cost. In this study, consolidation and strength parameters were estimated by the samples obtained from the similar reclaimed land. Water content and compression index of dredged soil reclaimed by hydraulic fill method were quite decreased in comparison with those of in-situ conditions at Incheon site. Relationships between compression index(Cc) and water content (wn), and between undrained strength (su) and water content (wn) for dredged soil were obtained by field vane test and oedometer test, respectively. Applicability of Schmertmann correction method (compression index) for low plasticity silty soil was discussed according to comparison with designed and measured settlements.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.9
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• pp.270-275
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• 2012

This paper describes design of a variable-N frequency synthesizer for RF PLL with $0.13{\mu}m$ silicon CMOS technology being used as an application of the UWB system like MBOA. To get good performance of speed and noise super dynamic circuits was used, and to get variable-N division ratio MOSFET switching circuits was used. Especially to solve narrow bandwidth problem of the dynamic circuits load resistance value of unit divider block was varied. Simulation results of the designed circuit shows very fast and wide operation characteristics as 5~26GHz frequency range.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.6
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• pp.73-81
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• 2001

This study uses the distributed parameter systems resented by the spatial discretization technique. In this paper, the distributed parameter systems are converted into lumped parameter systems, End fast Walsh transform and the Picard's iteration method are allied to analysis the state of the systems. This thesis presents a new algorithm which usefully exercises the optimal contro1 in the distributed parameter systems. In exercising the optimal control of the distributed parameter systems, the excellent consequences are found without using the existing decentralized contro1 or hierarchical control method. This study can be applied to the linear time-varying systems and the non-linear systems. Farther researches are required to solve the problems of convergence in case of the numerous applicable intervals. The simulation proves the effectiveness of the proposed algorithm.

• Journal of the Korean Institute of Intelligent Systems
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• v.12 no.4
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• pp.373-378
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• 2002

In fuzzy inferencing, most of conventional fuzzy controllers have problems of speed down in floating point operations of fuzzy membership functions in (0,1) as compared with integer operations. Therefore, in this paper, we propose a high-speed fuzzy controller with only integer operations. In this, for fast fuzzy computations, we use a scan line conversion algorithm to convert lines of each fuzzy linguistic term to the set of the closest integer pixels. We also implement a GUI (Graphic User Interface) application program for the convenient environments to modify and input fuzzy membership functions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10C
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• pp.948-955
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• 2006

In this paper, we propose motion estimation and compensation using Low-Band-Shift(LBS) with Integer Lifting Shift property. To overcome shift-variant property on wavelet coefficients, the LBS was previously proposed. This method which is applied to reference frame in video coding technique has superior performance in terms of rate-distortion characteristic. However, this method needs more memory and computational complexity. For the enhancement of those disadvantages, we propose motion estimation using Low-Band-Shift with Integer Lifting. The Integer Lifting implementation gives us good efficiency of calculation and storage.

• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.45-50
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• 2005

Sand pile method, such as sand drain method and sand compaction pile method, has been popularly used as an improved method for soft clay grounds. The effect of accelerating consolidation of soft clay grounds has been evaluated with Barren's solution. The consolidation behavior of soft clay ground with sand piles strongly depends on both the nonlinear mechanical interaction between sand piles and surrounding clays and the degradation permeability of clays. In this paper a method of determining consolidation parameters of soft clay ground with sand drains by using Barren's solution was proposed through a series of numerical simulations. Through the method, the change in both volume compressibility and permeability during consolidation was reasonably evaluated.

• Journal of Advanced Navigation Technology
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• v.14 no.6
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• pp.800-807
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• 2010

Jack knifing accident of semi trailer vehicle is one of the most dangerous accident type because the vehicle cross over its lane by the accident. Jack knifing accident can be predicted and detected by GNSS precise relative positioning. But integer ambiguity resolution procedure is inevitable in GNSS precise relative positioning. In this paper, success rate improving method of integer ambiguity resolution is proposed for jack knifing accident prediction and detection of semi trailer vehicle, and proposed method is tested by simulation.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.36-36
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• 2011

고분자 전해질 연료전지용 분리판은 가격비와 중량비가 높아 부품 가격 및 중량을 낮출 경우 파급 효과가 높을 것으로 예상된다. 일반적인 금속판들은 연료전지 스택 내의 산성 분위기에서 존재하므로 표면 부식이 쉽게 발행한다. 본 연구에서는 연료전지의 사용환경을 고려하여 금속판의 부식방지 및 표면특성 향상을 위해 그라핀을 코팅하였으며, 연료전지 스택 내부와 유사한 산화성 분위기를 모사하여 전기화학적 특성을 분석하였다.