• Journal of Electrical Engineering and Technology
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• 제7권4호
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• pp.570-575
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• 2012

In a wireless communication RF transmitter, the output of a quadrature modulator (QM) is distorted by not only the linear imperfection features such as in/quadrature-phase (I/Q) input gain imbalance, local phase imbalance, and local gain imbalance but also the nonlinear imperfection features such as direct current (DC) offset and mixer nonlinearity related to in-band spurious signal. In this paper, we propose the unified QM model to analyze the combined effects of the linear and nonlinear imperfection features on the performance of the QM. The unified QM model consists of two identical nonlinear systems and modified I/Q inputs based on the two-port nonlinear mixer model. The unified QM model shows that the output signals can be expressed by mixer circuit parameters such as intercept point and gain as well as the imperfection features. The proposed approach is validated by not only simulation but also measurement.

• 전산구조공학
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• 제1권1호
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• pp.79-85
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• 1988

제2계 2차모멘트법인 점적합 포물체 근사법의 역과정의 연산을 구하여 신뢰성설계에 적용할 수 있도록 하였으며, 파괴점을 구하기 위한 신뢰성조건법을 연산과정을 수정하여 한계상태함수가 비선형인 경우에도 문제마다 식을 새로 수립하는 번거로움을 피하도록 하였다. SOSM/RC 조합방법을 이용하면 결과적인 파괴확률은 목표파괴확률에 부합하며 넓은 범위의 하중비에 대해 거의 일정한 부분안전계수를 얻을 수 있다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전력기술부문
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• pp.110-112
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• 2008

This paper describes the effects of earth continuity conductor for reducing the level of induced sheath overvoltage at the single point bonded section of combined transmission systems. Firstly, 3 kinds of fault section are considered, and also faulty phases and the distance between phase conductor and earth continuity conductor are changed for the various analysis.

• 환경위생공학
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• 제19권3호
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• pp.58-64
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• 2004

Biological treatment of wastewater was studied with a purpose to remove TOC by the reduction of water hardness. The optimal conditions of coagulant were determined by reaction time and amount of coagulant. Experimental results indicate that the biological treatment after physico-chemical treatment was found to provide very efficient removal efficiency in the process to treat the textile wastewater, including the carbon dioxide treatment. The combined process of carbonization in the physico-chemical treatment respectively was increased the removal efficiencies of $30.0\%$ in biological treatment in comparison with exclusive biological treatment. As a result, the treatment of hardness after carbonization had the best removal efficiency of approximately $60.0\%$. The removal efficiencies in the exclusive biological treatment using Bacillus subtilis and after carbonization were increased by $38.9\%\;and\;69.0\%$ respectively. The combined Bacillus subtilis-assisted biological treatment was determined to be the most effective method to treat the textile wastewater in an economic point of view, the water quality in the wastewater treatment plays an important role.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1998년도 춘계학술대회논문집; 용평리조트 타워콘도, 21-22 May 1998
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• pp.327-333
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• 1998

A method for analysis of the free vibrations of the composite cylindrical shell with a longitudinal, interior rectangular plate is developed by using the receptance method. This method is based on the ratio of a deflection(or slope) response to a harmonic force(or moment) at an joint point. The natural frequencies of the combined shells calculated numerically. The results are compared with the experiment and a finite, element analysis results in order to validate the formulation. The effects of the location and thickness of the plate on the frequencies are also investigated.

• Structural Engineering and Mechanics
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• 제12권1호
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• pp.71-84
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• 2001

The objective of this paper is to develop a simplified method that could predict the strength of concrete filled steel tube (CFT) columns applicable to high strength material under combined axial compression and flexure. The simplified method for determining the strength of CFT columns is based on the interaction curve of the section approached by a polygonal connection of the points. These points are determined by using symmetrical properties of the CFT section. For each point, a simple equation is proposed to determine the strength of the slender columns under compression and flexure. The simple equation was adjusted with results of elasto-plastic analysis results. Validation of the simplified method is undertaken by comparison with data from the test conducted at Kyushu University. These results confirm the fact that the simplified method could accurately and reliably predict the strength of CFT columns under combined axial compression and flexure.

• 한국연소학회지
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• 제7권1호
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• pp.58-64
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• 2002

The bed combustion in an incinerator interacts with the gas flow region through heat and mass transfer. Combined bed combustion and gas flow simulations are performed to investigate this coupled interaction for various operating conditions and furnace configurations. Radiation onto the bed from the furnace is interrelated with the combustion characteristics in the bed, and is also affected by the flow pattern in the gas flow region. Since the contribution of gaseous emission to the total radiation is significant, an adequate flow pattern in a well-designed furnace shape would lead to an increased heat influx on the bed, especially in the early stage of the waste combustion. Advancing the initiation point of the waste combustion can also reduce the size of the lower gas temperature region above the bed, which can be achieved by controlling operating conditions such as the waste feeding rate, the bed height and the primary air flow distribution.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.203-206
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• 2001

A 30kw Dual rotor Turbines HAWT/VAWT combined wind turbine system that can drastically enhance the power production capability compared to conventional Single Rotor Turbine HAWT system. The combined system that takes advantage of strong point of both horizontal and vertical Axis wind turbine system developed by a venture firm KOWINTEC of Chonbuk national university. The HAWT/VAWT hybrid system has been successfully field tested and commercial operating since Feb. 12, 2001 in Hae-chang rest park, Bu-an county near the Sae Man-Kum Sea Dike. This paper will briefly describe the field test results performance and a special aerodynamic structure with bevel-planetary gear box of Dual Rotor Wind Turbine system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 A
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• pp.443-445
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• 2000

This paper describes the assessment of proper location of lightning arrester in combined transmission line which is connected with overhead line and underground cable. The modeling for simulation is established using the actual system in ATP Draw and EMTP. Simulation is carried out to find out the best point to install the arrester in given the model system. And also voltage and current is analyzed on cable covering protection unit(CCPU). The simulation result demonstrated the best location of arrester in the given transmission line through the detailed analysis and its assessment.

• 산업기술연구
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• 제28권B호
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• pp.129-133
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• 2008

A method to reduce seam line artifact in spatial compounding of ultrasonic images is presented. Spatial compounding is a speckle reducing imaging technique in which a number of ultrasound images of a given target that have been obtained from multiple view angles are combined into a single compounded image by combining the data received from each data point in the compounded image. Since different view angle results in different view area, and the images of different view arms are combined into an image, the compounded image consists of regions with different signal to noise ratio, and the boundary lines between these regions are visible as seam lines in the compounded images. In this paper, we present an algorithm that reduces the visibility of this seam line in the spatially compounded images. Design procedure for a FIH filter is described and the results of applying the filter to in-vivo ultrasonic images are analyzed.