• 대한전자공학회논문지TC
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• 제48권9호
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• pp.47-53
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• 2011

본 논문에서는 커넥터의 특성임피던스 추출, 분석 방법 및 설계 변경 방법을 제안하고 임피던스를 정합하여 신호 전달 특성을 개선한다. 3차원 FEM(Finite Element Method) 전자기장(Electro-Magnetic Field) 시뮬레이터를 이용하여 커넥터의 S-파라미터를 계산하고 반사손실 및 삽입손실을 추출한다. 커넥터의 신호 전달 특성은 반사손실이 0.9 GHz 이후부터 -20 dB 이상의 값으로 높게 나타났다. 신호 전달 특성이 낮은 원인을 파악하기 위해서 회로 해석 시뮬레이터를 이용하여 커넥터의 등가 회로 모델을 추출하고 특성임피던스를 계산하였다. 커넥터의 특성임피던스는 $90.3{\Omega}$으로 임피던스 부정합이 발생하여 신호 전달 특성이 저하되었다. 따라서 신호 전달 특성을 개선할 목적으로 임피던스를 정합하기 위해서 커넥터의 커패시턴스를 증가시켰다. 이러한 설계 방안으로 커넥터 신호선의 유효 면적을 확장하고, 커넥터의 몸체 소재로 고유전체를 사용하였다. 설계 변경된 커넥터의 특성임피던스는 $58.6{\Omega}$으로 임피던스 정합에 보다 근접하여 커넥터의 반사손실이 대략 10 dB 향상되었다. 신호선의 유효 면적 증가에 의한 반사손실 개선과 고유전체의 적용으로 전자기파의 신호선 주변 집중에 의해서 삽입손실 또한 개선되었다.

• 한국농공학회논문집
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• 제55권6호
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• pp.167-175
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• 2013

The objective of this study was to investigate the nutrient load balance in the reservoir irrigated paddy block during growing seasons. Idong reservoir irrigation paddy block of 10.3 ha in size was selected to collect hydrologic and water quality data. Irrigation, canal flows, and paddy field drainage were measured using a water level gauge, while water samples were collected and analysed for water quality. The water balance analysis showed that 81 % and 75 % of total outflow were through paddy and irrigation canal drainage during 2011 and 2012, respectively. The water quality of paddy field drainage varied greatly depending on rice cultivation stage ranging from 0.05 to 24.55 mg/L and from 0.01 to 0.76 mg/L for T-N and T-P, correspondently. Paddy field drainage loads during May through June account for 64 % and 76 % in 2012 and 2013, while 82 % and 81 % for T-P in 2011 and 2012, respectively. The Pearson correlation analysis showed that rainfall was significantly correlated with nutrient loads during July through August due to runoff, and irrigation was related with nutrient loads of drainage during some period of July through September due to irrigation return flow. This study results showed characteristics of inflow and outflow nutrient loads from plentiful irrigated paddy block.

• 한국측량학회지
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• 제16권1호
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• pp.1-7
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• 1998

SAR 영상은 기상이나 일조량에 관계없이 자료를 취득할 수 있으므로 종래의 전자광학적 감지기가 갖는 제약을 극복할 수 있다. 또한, SAR 영상으로 취득할 수 있는 정보는 종래의 광학적 감지기에 의한 것과는 다른 형태이므로 영상에 의한 정보취득의 범위를 확대시킬 수 있다. 그러나, SAR 영상에는 레이다의 특성과 대상물의 기하학적 특성에 따라 다양한 왜곡이 포함되므로, SAR 영상으로부터 정보를 취득하는 데 있어서 소요 정확도가 확보되기 위해서는 SAR 자료에 포함되어 있는 왜곡을 보정하여야 한다. 본 연구에서는 SAR 영상 취득시 대상물과 안테나의 기하학적 구성에 따른 반사파의 변화를 모형화하여 SAR 영상을 모의제작하고, 이를 이용해 대상물의 경사에 따른 밝기값의 왜곡을 실제 영상에서 제거하므로서 SAR 영상의 기하학적 복사 왜곡을 보정하고자 하였다. 그 결과, SAR 영상으로부터 대상물의 반사특성에 따른 정상적 정보를 취득함에 있어서 기하학적 복사왜곡에 의한 영향을 최소화하여 지형공간정보 관련 분야에서 SAR 영상을 원활히 활용할 수 있도록 기여하고자 하였다.

• 한국전자파학회논문지
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• 제15권11호
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• pp.1019-1025
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• 2004

직각 도파관 내의 주 모드인 TE$_{10}$ 모드의 필드 분포를 기준으로 만든 전송선 등가 모델을 바탕으로 슬롯 결합의 결합을 통해 급전하는 도파관 슬롯 배열 안테나를 설계하였다. 이를 위해 도파관 중심에 위치한 기울어진 슬롯(결합 슬롯)의 적절한 각도와 도파관 축 방향 슬롯(방사 슬롯)의 이격거리를 구해낸 후, 이를 EM 시뮬레이션을 통해 전자기적 특성을 파악하고 특성을 분석하였으며 실제 제작품 측정 결과 비교하였다. 측정된 반사손실 대역폭은 중심주파수 9.15 GHz에서 180 MHz, 부엽레벨은 -25 dB 이하, 반 전력 빔폭은 약 9$^{\circ}$, 이득은 25.5 dB이며 이러한 결과는 시뮬레이션 데이터와 유사하다.

• 복식
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• 제53권2호
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• pp.87-100
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• 2003

In this study, the modern street fashion of Kangnam and Kangbuk was qualitatively examined and comparatively analyzed through the field case study, and it is expected that the results of this study be importantly used in planning commodity of fashion brand. The photographs taken in the Kangnam and Kangbuk streets were classified as looks. which were comparatively analyzed each other. Also, a questionnaire was carried out in return for women in those streets, and data related with an age group, occupation, school, academic major, etc. for participant personality and with time purchasing clothing. average expenses for clothing per month. market and reasons for buying clothing, current fashion style, etc. for fashion preference trend were obtained. The streets around Kangnam subway station and KOEX mall for the Kangnam fashion style were selected for the sampling, and Sinchon and entrance of Ewha University for the Kangbuk, where college students and middle/high school students mostly gather. Results showed that an easy casual style was most popular in the Kangbuk area, and a romantic feminine style including a bobos style most popular in the Kangnam area. This case studied on the street fashion gaves the qualitative results about the fashion trend and fashion prediction information, and they could be compared with quantitative those known previously. Also, it could be a basis research on strengthening the competitive power in fashion commodity. However, this study was subjected to restriction in the sampling due to the short time and a few streets. This study will be extended into longer time and various streets including Apgujungdong in Kangnam and many colleges in Kangbuk.

• 전기학회논문지
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• 제61권3호
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• pp.485-490
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• 2012

Nowadays, in metropolitan railroad, DC feeding system is being generally applied. In order to reduce damage of electro-chemical corrosion caused by stray current and leakage current, in DC feeding system, rail is used as negative-polarity return conductor for traction load current. However, it has problem of rail potential increase and there are no adequate measures to prevent it in domestic. The rise of rail potential leads to damage for human and equipments. To solve the problems, this paper presents fundamental theory and related standards about rail potential increase. And then, we analyzed field testing data and simulated a variety of operations by using PSCAD/EMTDC as an analysis program of power system. In addition, this paper suggests rail potential limit device and addresses how to the device. To verify the effect, simulation of DC feeding system before and after the application of the device is carried out in various cases.

• 대한수의학회지
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• 제27권1호
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• pp.137-140
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• 1987

Information on certain reproductive traits were obtained from field material. The data for this study were taken from 1,111 breeding records of 273 cows and 193 heifers at Koheung, Chonnam, during the period 1979 to 1984. The cattle were bred by artificial insemination; only one or two cattle were reared by one farmer. The heifers were first bred at 551.75 days after they were born; they were pregnant at 569.06 days after birth. The average estrous cycle length was 21 days; the average number of inseminations per conception was 1.56. The non-return rate for first inseminations for cows and heifers was 62.5% and 59.6%, respectively. The gestation length was 285.79 days. Of 1,111 viable calved born 582 were male, giving a sex ratio of 100:110. The average length between calving and first insemination was 88.9 days; average calving interval was 397.69 days.

• 천문학회보
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• 제39권1호
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• pp.75.1-75.1
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• 2014

Sunspot penumbrae show supersonic downflow patches along the periphery. These patches are believed to be the return channels of the Evershed flow. There was previous study to investigate their structure in detail using Hinode SOT/SP observations (M. van Noort et al. 2013) but their data sample was only two sunspots. To make general description it needs to check more sunspot sample. We selected 242 downflow patches of 17 sunspots using Hinode SOT/SP observations from 2006 to 2012. Height-dependent maps of atmospheric parameters of these downflows was produced by using HeLix which was height dependent LTE inversion code of Stokes profiles. The inversion code at high resolution allows for the accurate determination of small scale structures. The recovered atmospheric structure of three layers indicates that regions with very high downflow velocities contain very strong magnetic fields reaching up to 7kG. The higher downflow velocity patches have bigger patch size. Magnetic fields of downflow patches are more vertical while penumbra shows horizontal field and neighbor of downflow patches have opposite polarity. Temperature of downflow patches at highest layer have more strong value than penumbra at deepest layer. The direction of velocity of downflow patches at highest layer have two branches. These result shows that we can expect some heating precess in the middle of layer.

• 농촌계획
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• 제26권2호
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• pp.51-59
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• 2020

In this study, we analyzed the characteristics of 511 agricultural districts through statistical data, and classify these districts as the vulnerable area to drought through correlation and cluster analysis. The criteria for classification was related to ground-water recharge, irrigation water demand, and water supply. As a result, 8 types of agricultural districts were extracted. For example, the type 1 indicated the high priority area for ground-water development, thus the districts which were classified as type 1 showed ground-water use was less than 80 % of maximum capacity, and irrigation water supply was only 37.5 % and 76.5 % of irrigation water demand in upland and paddy field, respectively. As a result, 44 of 511 districts were classified as type 1.36 districts (types 5-8) were areas where groundwater development is limited. The results of this study are expected to provide useful information for establishing the direction of the rural area development project in connection with the revitalization of policy of people return to rural area.

• 반도체디스플레이기술학회지
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• 제22권1호
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• pp.94-98
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• 2023

In the case of high-speed data transmission on high multilayer boards, signal coherence is a problem, especially due to the via hole, and a solution to improve return loss or insertion loss by applying a back drill to the via hole is being proposed. In this paper, Near-Field Electromagnetic measurements were made on a high multilayer board to determine how the presence or absence of back drill affects signal consistency. For this purpose, we used a signal generator, spectrum analyzer, and EMC scanner on a test board to determine if it is possible to distinguish between areas with and without back drill in the via holes of the stubs on the board. Also, we analyzed the measured value of S11, S21 and EMC etc. for how much it improves the signal attenuation of the stub with back drill. Through this, we knew that less electromagnetic waves are generated the stub via with back drill. At future research, we will analyze how much it improves the signal loss and electromagnetic waves due to the depth of back drill.