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유전율/투자율 측정을 위한 2-PORT PROBE (pp.1287-1288)
박상복(Sangbok Park),이장수(Jangsoo Lee),천창율(Changul Cheon) 대한전기학회 2006 대한전기학회 학술대회 논문집 Vol.2006 No.7
본 연구에서는 2-port probe를 설계, 제작하고, 이를 이용하여 유전율과 투자율을 동시에 측정해내는 기법을 연구하였다. 기존에는 유전율 측정을 위해 끝이 open되어 있는 1-port probe를 주로 이용하였지만 이는 유전율만이 측정이 가능하고 주파수 대역에 한계가 있었다. 2-port probe는 유전율과 투자율이 동시에 측정이 가능하며 주파수의 한계를 극복하였다. 2-port probe를 등가화 하여 이를 수식적으로 해석했을 경우 수많은 변수들이 발생되는데 이것을 여러 수치기법들을 이용하여 정리한 후, 유전율을 알고 있는 용액들을 이용하여 보정하였다. 또한 2-port probe에 약간의 길이 변화를 주어 주파수대역의 변화를 실험을 통해 비교 분석하였다.
캐비티 공진기를 이용한 반고체 상태 물질의 복소 비유전율 측정 방법
박래승(Rae-Seoung Park),장지현(Jihyun Jang),박병덕(Byungdeok Park),김준환(Junhwan Kim),박상복(Sangbok Park),정용식(Young-Seek Chung),천창율(Changyul Cheon) 한국전자파학회 2014 한국전자파학회논문지 Vol.25 No.8
본 논문은 새로운 캐비티 공진기 구조를 이용한 반고체 상태 물질의 복소 비유전율 측정 방법을 제안하고 있다. 윗면에 개구면이 존재하고, Ground 판이 분리되어 있는 구조를 이용하여 반고체 상태 물질도 캐비티 내부에 위치할 수 있도록 했다. 공진주파수의 변화와 Critical-Points Method를 이용해 실험적으로 증류수와 0.9 % 식염수의 복소 비유전율을 측정하였으며, 측정값을 Cole-Cole Equation을 통해 이론값과 비교했다. This paper proposes a measurement method of the complex relative permittivity of semi-solid materials using a new cavity structure. Semi-solid materials are positioned in the proposed cavity where an aperture exists on each corner of the upper part and a ground plane is separated. In order to show the validation of the proposed method, we measured the complex relative permittivity of distilled water and 0.9 % saline by sensing a shift of resonant frequency and using Critical-Points Method, and compared the results with those derived from the Cole-Cole equation.
Oscillation System을 이용한 알루미늄판의 Phi방향 Monostatic RCS 감쇄 연구
황주성(Joosung Hwang),박상복(Sangbok Park),장성훈(Sunghoon Jang),천창율(Changyul Cheon) 대한전기학회 2013 전기학회논문지 Vol.62 No.2
This paper proposes a new method that reduces RCS(rader cross section) of the aluminum plate using a oscillation system composed of a VGA(variable gain amplifier) and a phase shifter. Once the oscillation system receives the external-RF signal through a probe on aluminum plate, it makes an amplified signal with a specific phase to cancel the signal reflected from the aluminum plate. The signal transmitted from the oscillation system has the same amplitude and out of phase with the reflected signal. And it can be controlled by the VGA and the phase shifter in the oscillation system. In order to validate the performance of the proposed oscillation system, FEM simulator was used and we measured how much an amplitude of the signal reflected from the aluminum plate rotated in phi direction is reduced in an anechoic chamber.
최선희 ( Choi Sunhee ),배지영 ( Bae Jiyoung ),박상복 ( Park Sangbok ) 글로벌영어교육학회 2024 Studies in English education Vol.29 No.1
The purpose of this study is to examine the extent to which the Middle School English Listening Test utilizes the communicative functions presented in the 2015 national curriculum. The test is the only nationwide English test that assesses all the middle school students in Korea except those under the jurisdiction of Seoul Metropolitan Office of Education. To achieve the goal, an analysis was conducted on the use of communicative functions in the dialogues included in the tests administered in September 2022 and April 2023. A total of 1258 T-units were extracted from 100 dialogues, and then each unit was compared with the expressions exemplifying different types of communicative functions provided in the national curriculum. The results showed that the ‘exchanging information’ function was used most, which was followed by ‘persuading and making suggestions’ and ‘expressing one’s will’. However, some of the functions such as ‘repairing communication’ and ‘expressing knowledge, memory, and assurance’ were rarely used. In addition, there was some inconsistency in the use of communicative functions in different grades. Pedagogical implications and future directions for developing a more balanced English listening test are discussed.