Software Defined Radio (SDR) 무전기용 접힌 평면 구조의 초광대역 안테나

오준화(Jun-Hwa Oh),오일영(Il-Young Oh),육종관(Jong-Gwan Yook) 大韓電子工學會 2009 電子工學會論文誌-TC (Telecommunications) Vol.46 No.12

We propose a folded monopole antenna with loads, and analyze the roles of design parameters which affect the return loss of the proposed antenna. VSWR < 3 bandwidth of the antenna is 30 ~ 2000 ㎒, ranging from the HF/VHF/UHF bands. For operating travelling antenna, we connect six loads at the end of the antenna. The reflected wave is drastically reduced due to the six loads. For improved return loss properties, we use Klopfenstein tape that determine positions and values of six loads. The propose antenna has omni-directional radiational patterns like that of conventional monopole antennas. For wideband impedance transformation, we use the balun which operating frequency region is 10 ~ 1900 ㎒. We expect the proposed antenna has important role for the wideband and multi-rold multi-functional communication systems. 본 논문에서는 부하 저항을 갖는 접힌 구조의 모노폴 안테나를 제안 하였고, 설계 변수들이 안테나의 반사손실 특성에 미치는 영향에 대해 분석 했다. 제안한 안테나의 임피던스 대역폭(VSWR < 3)은 30 ~ 2000 ㎒이고, 이는 HF/VHF/UHF 대역을 모두 포함한다. 진행파 안테나로 동작하게 하기 위해 안테나에 여섯 개의 부하 저항을 이용하여 안테나의 끝에서 발생하는 반사파를 많이 줄일 수 있었다. 부하 저항에 의해서 감소되는 방사 효율 감소를 줄이기 위해 안테나의 끝부분에 부하 저항을 달았고, 부하 저항들의 저항 값은 반사 손실 특성이 좋은 Klopfenstein taper를 이용하였다. 제안한 안테나는 모노폴 안테나와 같이 전방향성 방사패턴을 갖는다. 급전부분과 제안한 안테나의 입력단 부분에서의 광대역 임피던스 변환을 위해 급전 부분과 안테나의 입력단 사이에 10 ~ 1900 ㎒에서 동작하는 발룬(Balun)을 이용하였다. 제안한 안테나의 광대역 특성과 방사패턴은 다대역 다기능 통신기에 이용될 수 있을 것으로 예상한다.

일제 강점기 동안의 우리나라 영어교육 - 공립 중등학교를 중심으로

오준일(Oh, Jun-Il) 동북아시아문화학회 2020 동북아 문화연구 Vol.1 No.63

English teaching in Korea during the Japanese colonial period has often been described as the victim of a dark age. Most previous studies on the topic tended to cover diverse aspects of English teaching in Korea at different school levels and in different contexts, thus making it impossible to characterize the nature of English teaching at public schools. In an attempt to better understand the nature of English teaching in Korea during the Japanese colonial period, this study focused on English teaching at Korean public secondary schools during the period. First, the study looked at weekly instructional hours as dictated by four educational edicts to evaluate the commonly made claim that English teaching in Korea experienced a dark age throughout the Japanese colonial period. In addition, the study examined why the grammar-translation method was the most commonly adopted approach to teaching English at public secondary schools. An analysis of the four educational edicts showed that there were substantial differences in the number of instructional hours across different periods of Japanese colonial rule. Thus, characterizing the entire colonial period as a dark age of English teaching seemed to lack validity. In addition, considerations of various contextual factors suggested that the adoption of the grammar-translation when teaching English at Korean public secondary schools during the Japanese colonial period was a forced choice, not a choice mandated by any political entity. Big class size, Japanese teachers’ inadequate English proficiency, high-stakes English examinations, and other factors seemed to be responsible for widespread use of the grammar-translation method.

특집 : 차세대 초초임계압 화력발전 보일러용 니켈계초 내열합금의 연구 개발 동향

오준학 ( Jun-hak Oh ),최인철 ( In-chul Choi ),신경수 ( Gyeong-su Shin ),이동복 ( Dong Bok Lee ),김선진 ( Seon-jin Kim ),장재일 ( Jae-il Jang ) 대한금속재료학회 ( 구 대한금속학회 ) 2011 재료마당 Vol.24 No.2

WRF 모형의 수도권 지역 상세 국지 기상장 모의 성능 평가

오준서(Jun-Seo Oh),이재형(Jae-Hyeong Lee),우주완(Ju-Wan Woo),이두일(Doo-Il Lee),이상현(Sang-Hyun Lee),서지현(Jihyun Seo),문난경(Nankyoung Moon) 한국기상학회 2020 대기 Vol.30 No.3

Faithful evaluation of the meteorological input is a prerequisite for a better understanding of air quality model performance. Despite the importance, the preliminary meteorological assessment has rarely been concerned. In this study, we aim to evaluate the performance of the Weather Research and Forecasting (WRF) model conducting a year-long high-resolution meteorological simulation in 2016 over the Seoul metropolitan area. The WRF model was configured based on a series of sensitivity simulations of initial/boundary meteorological conditions, land use mapping data, reanalysis grid nudging method, domain nesting method, and urban canopy model. The simulated results of winds, air temperature, and specific humidity in the atmospheric boundary layer (ABL) were evaluated following statistical evaluation guidance using the surface and upper meteorological measurements. The statistical evaluation results are presented. The model performance was interpreted acceptable for air quality modeling within the statistical criteria of complex conditions, showing consistent overestimation in wind speeds. Further statistical analysis showed that the meteorological model biases were highly systematic with systematic bias fractions (f<SUB>SB</SUB>) of 20~50%. This study suggests that both the momentum exchange process of the surface layer and the ABL entrainment process should be investigated for further improvement of the model performance.

중등학교 영어과 교사의 학생 평가 전문성에 대한 인식 조사

전병만 ( Byoung Man Jeon ),오준일 ( Jun Il Oh ) 글로벌영어교육학회(구 호남영어교육학회) 2006 Studies in English education Vol.11 No.2

An increasing need for accurate and valid assessment in the classroom mandates that English teachers have expertise in student assessment. Teachers are expected to be experts in student assessment, yet research on secondary school English teachers` competence in student assessment has been rare in Korea. This study surveyed what English teachers in secondary schools think of their own competence in student assessment. The results are revealed that secondary school teachers in Korea perceive of themselves as lacking competence in areas of student assessment in which they have not been trained during their pre- or in-service program. It is hoped that the results of this survey might help establish a set of competency standards for student assessment.

중학생의 영어 받아쓰기 과정에 관한 연구

신정숙 ( Jung Suk Shin ),오준일 ( Jun Il Oh ) 글로벌영어교육학회 2007 Studies in English education Vol.12 No.1

L-Carnitine, pyridoxine hydrochloride, DL-α-tocopheryl acetate를 이용한 분유모델시스템의 마이얄반응생성물 저감화 조건 최적화

정혜림(Hye-Lim Jung),남미현(Mi-Hyun Nam),홍충의(Chung-Oui Hong),표민철(Min-Cheol Pyo),오준구(Jun-Gu Oh),김용기(Young Ki Kim),최유영(You Young Choi),권정일(Jung Il Kwon),이광원(Kwang-Won Lee) 한국식품과학회 2015 한국식품과학회지 Vol.47 No.1

본 연구는 분유모델시스템에 L-carnitine, pyridoxine hydrochloride, DL-α-tocopheryl acetate를 첨가하여 Maillard 반응에 의해 생성된 MRPs를 저감화 시키기 위한 최적조건을 찾기 위해 RSM의 CCD를 이용하였다. L-Carnitine (X₁), pyridoxine hydrochloride (X₂), DL-α-tocopheryl acetate (X₃)의 농도를 독립변수로 하고 형광도와 HMF 함량을 종속변수로 각각 설정하였다. 종속변수 회귀식의 결정계수(R<SUP>2</SUP>)는 각각 0.942, 0.861로 반응표면분석 모델에 적합하였다. 형광도와 HMF 함량은 L-carnitine과 pyridoxine hydrochloride의 농도가 낮을 때 DL-α-tocopheryl acetate의 농도가 감소할수록 그 값이 급격히 감소하였다. L-Carnitine의 농도가 높을 때 pyridoxine hydrochloride의 농도가 20 μM 이하로 감소할수록 형광도가 감소하였고 HMF 함량은 L-carnitine의 농도에 관계없이 pyridoxine hydrochloride의 농도가 20 μM 이하로 감소할수록 감소하는 경향을 나타냈다. 본 실험에서 분유모델시스템에서 생성된 MRPs를 저감화 할 수 있는 최적조건으로 L-carnitine, pyridoxine hydrochloride, DL-α-tocopheryl acetate의 농도는 각각 2.26, 15.77, 20.63 μM이었다. 이때 형광도는 77.4%였고 HMF 함량은 248.7 ppb로 각각 유단백질-유당 마이얄 반응생성물(LC, lactose+sodium caseinate)대비 MRPs를 22.6, 23.1% 감소시킬 수 있다고 예측할 수 있었다. 또한, RSM을 통해 찾은 최적 조건의 실험값으로 형광도는 79.3%였고 HMF 함량은 247.6 ppb로 각각 LC대비 MRPs를 20.7, 17.8% 감소 시켰다. 따라서, L-carnitine, pyridoxine hydrochloride, DL-α-tocopheryl acetate의 최적화된 혼합을 통하여 분유제조 시 MRPs 생성을 저감화 시킬 수 있을 것으로 생각된다. The Maillard reaction is a non-enzymatic reaction between amino and carbonyl groups. During milk processing, lactose reacts with milk protein through this reaction. Infant formulas (IFs) are milk-based products processed with heattreatments, including spray-drying and sterilization. Because IFs contain higher Maillard reaction products (MRPs) than breast milk, formula-fed infants are subject to higher MRP exposure than breast milk-fed ones. In this study, we investigated the optimization of conditions for minimal MRP formation with the addition of L-carnitine (L-car), pyridoxine hydrochloride (PH), and DL-α-tocopheryl acetate (α-T) in an IF model system. MRP formation was monitored by response surface methodology using fluorescence intensity (FI) and 5-hydroxymethylfurfural (HMF) content. The optimal condition for minimizing the formation of MRPs was with 2.3 μM L-car, 15.8 μM PH, and 20.6 μM α-T. Under this condition, the predicted values were 77.4% FI and 248.7 ppb HMF.