• Journal of electromagnetic engineering and science
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• 제12권3호
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• pp.216-222
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• 2012

This paper presents a single-pole eight-throw switch, based on an eight-way power divider, using substrate integrate waveguide(SIW) technology. Eight sectorial-lines are formed by inserting radial slot-lines on the top plate of SIW power divider. Each sectorial-line can be controlled independently with high level of isolation. The switching is accomplished by altering the capacitance of the varactor on the line, which causes different input impedances to be seen at a central probe to each sectorial line. The proposed structure works as a switching circuit and an eight-way power divider depending on the bias condition. The change in resonant frequency and input impedance are estimated by adapting a tapered transmission line model. The detailed design, fabrication, and measurement are discussed.

• 기본간호학회지
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• 제8권3호
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• pp.366-378
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• 2001

Objective: The purpose of this study was to identify differences in measurement methods for blood pressure (Direct measurement, HP automatic indirect measurement, and SE 7000 Korean made indirect measurement), and to evaluate the clinical trial of the Korean made automatic indirect blood pressure measurement. Material & Methods: From June, 1999 to February, 2000, fifty five consecutive patients were randomized into hypertension group (n=20), normotension group (n=20), and hypotension group (n= 15). Measuring blood pressure by indirect methods (HP NIBP M 1008B and SE 7000 NIBP Korean made) was done simultaneously in the same arm with arterial line for direct blood pressure measurement (HP M1006A). The procedures were repeated ten times at intervals of 2 minutes. Statistical analysis was Performed using SPSS (version 8.0 for windows) software package. Values were expressed as means and standard deviation and means were compared using t-test. Statistical significance was considered present with a p value less than 0.05. Results: In the hypertension group and noromotension group, the disparity between HP direct measurement and indirect SE 7000 NIBP did not show any differences compared to the disparity between HP direct measurement and indirect HP NIBP. In the hypotension group, the disparity in the diastolic pressure between HP direct measurement and indirect SE 7000 NIBP was significantly different compared to the disparity between HP direct measurement and indirect HP NIBP (p<0.001), however, disparities in systolic pressure did not showed any differences. Conclusion: Direct blood pressure measurement (HP M1006A) can be replaced with indirect blood pressure measurements (HP NIBP M 1008B & SE 7000 NIBP) in normotension and hypertension patients. Korean made indirect measurement was found to be more accurate compared to HP indirect measurement in hypotension Patients, but more study is needed.

• 한국기후변화학회지
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• 제1권2호
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• pp.147-161
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• 2010

단일 기층의 모형 대기에 적용하기 위한 태양 복사 모델을 기준 모델(Line-by-Line Model: LBL)로 보정하여 2009년 1월부터 2009년 12월까지 한반도의 지표면 태양광 시공간 분포를 계산 및 분석하였다. 이 연구에 사용된 태양 복사 모델의 입력 자료는 기상청(KMA)의 수치모델 자료 그리고 위성자료로부터 도출된 오존 전량과 에어로졸 및 구름 자료 등이 사용되었다. 이 연구 기간 동안 4 km 간격으로 수평면에 대하여 한반도의 지표면 태양광을 계산하였고 그 결과를 지표면 일사 관측값들과 비교하였다. 그 결과 모델에 의하여 계산된 연 누적 태양광은 안동과 대구 및 진주를 연결하는 지역에서 최대값($5,400MJ/m^2$ 이상)이 나타났고 이 값들은 위성 관측 전운량 자료와 잘 일치하였다. 그러나 지표면 일사 관측 자료의 공간 분포는 모델 계산 결과와 차이가 있었으며 그 원인은 관측소 일사계의 보정 및 관리운영에 따른 자료 정확성 때문인 것으로 분석된다.

• Journal of Electrical Engineering and Technology
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• 제10권2호
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• pp.474-486
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• 2015

This paper proposes a multi-objective optimal placement method of Phasor Measurement Units (PMUs) in large electric transmission systems. It is proposed for minimizing the number of PMUs for complete system observability and maximizing measurement redundancy of the buses, simultaneously. The measurement redundancy of the bus indicates that number of times a bus is able to monitor more than once by PMUs set. A high level of measurement redundancy can maximize the system observability and it is required for a reliable power system state estimation. Therefore, simultaneous optimizations of the two conflicting objectives are performed using a binary coded firefly algorithm. The complete observability of the power system is first prepared and then, single line loss contingency condition is added to the main model. The practical measurement limitation of PMUs is also considered. The efficiency of the proposed method is validated on IEEE 14, 30, 57 and 118 bus test systems and a real and large- scale Polish 2383 bus system. The valuable approach of firefly algorithm is demonstrated in finding the optimal number of PMUs and their locations by comparing its performance with earlier works.

• 한국산학기술학회논문지
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• 제20권6호
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• pp.598-603
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• 2019

삼차원 형상 측정 기술은 다양한 산업에서 활용하고 있는 기술이다. 그 중, 광 삼각법에 기초한 광학식 삼차원 형상 측정 기술들은 매일 공장에서 오랜 시간 동안 대량의 삼차원 형상 측정을 하고, 미세한 측정 또한 요구되는 반도체 생산품 검사 분야에서 주로 사용된다. 이러한 광 삼각법 기반의 삼차원 측정 장비들의 구성 요소인 광원과 구동 회로는 장시간 작동하게 되면 발열이 나타나게 되고 장시간 작동하며 주변의 온도가 일정하지 않은 상황에 노출되기도 하여 온도로 인한 측정 오차가 발생하게 된다. 본 논문에서는 장시간 반복해서 사용하는 PMP(Phase Measuring Profilometry) 형상 측정법에서의 열 변위 보정에 관한 방법을 제안하였다. PMP 형상 측정법 기반의 삼차원 형상 측정 장치를 구현하여 10시간에 걸쳐 물체의 높이와 주변 온도를 측정하는 실험을 진행하였고, 측정된 온도와 높이 값을 이용하여 단순 선형 회귀 분석을 하여 회귀직선을 얻었다. 이 회귀직선을 이용하여 온도에 따른 높이 측정값의 오차를 보정하게 되면 정상적인 측정값에서의 오차 값이 139.88 um(Micrometer) 에서 13.12 um로 보정되는 것을 확인하였다.

• 한국식품과학회지
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• 제26권4호
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• pp.448-452
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• 1994

압출물의 두께를 실시간 측정할 수 있는 컴퓨터 영상처리시스템이 제시되었다. 영상처리시스템은 CCD 카메라, 영상 취득기, 486 PC로 구성되었다. 시스템에 들어온 영상은 실시간 측정을 위해 작성된 C-프로그램에 의하여 분석되었다. 제안된 컴퓨터 알고리즘을 이용하여 정확한 압출물의 두께 측정이 실시간 내에 가능하였으며 처리 시간은 1초 이내였다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 춘계학술발표대회 개요집
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• pp.167-170
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• 2002

• 한국광학회:학술대회논문집
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• 한국광학회 2006년도 동계학술발표회 논문집
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• pp.133-134
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• 2006

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.126-131
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• 2001

This paper deals with implementation of inverter systems for DC power regeneration, which can regenerate the excessive DC power from DC bus line to AC supply in substations for traction systems. From the viewpoint of both power capacity and switching losses, a three-phase square-wave inverter system is adopted. To control the regenerated power, the magnitude and phase of fundamental output voltages should be appropriately controlled in spite of the variation of input DC voltage. Inverters are operated with modified a-conduction mode to fix the potential of each arm. The overall system consists of the line-to-line voltage and line current sensors, an actual power calculator using d-q transformation method, a complex power controller with PI control scheme, a gating signal generator for modified $\alpha-conduction\;mode\;with\;\delta\;and\;\alpha$, a DPLL for frequency followup, and power circuit.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.99.5-99
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• 2001

This study presents a simulation of the traction return current based on $2{\times}25kV$ power supply system in order to determine the impedance bond intensity of impulse type track circuit on the electrified Gyeongbu line. The results of the simulation enables us to measure the precise intensity of catenary current that returns to the substation through KTX (Korean Train Express) operated by $2{\times}25kV$ power supply system with common earth network. The combination of $2{\times}25kV$ and common earth network established on the electrified Gyeongbu line for the first time in Korea. We show that the relationships among the traction return current, earth current, and catenary current, and catenary current can be applied to this line in order to determine the optimal impedance bond intensity ...