• 천문학회지
• /
• 제54권2호
• /
• pp.61-70
• /
• 2021

We investigate 20 post-coronal mass ejection (CME) blobs formed in the post-CME current sheet (CS) that were observed by K-Cor on 2017 September 10. By visual inspection of the trajectories and projected speed variations of each blob, we find that all blobs except one show irregular "zigzag" trajectories resembling transverse oscillatory motions along the CS, and have at least one oscillatory pattern in their instantaneous radial speeds. Their oscillation periods are ranging from 30 to 91 s and their speed amplitudes from 128 to 902 km s-1. Among 19 blobs, 10 blobs have experienced at least two cycles of radial speed oscillations with different speed amplitudes and periods, while 9 blobs undergo one oscillation cycle. To examine whether or not the apparent speed oscillations can be explained by vortex shedding, we estimate the quantitative parameter of vortex shedding, the Strouhal number, by using the observed lateral widths, linear speeds, and oscillation periods of the blobs. We then compare our estimates with theoretical and experimental results from MHD simulations and fluid dynamic experiments. We find that the observed Strouhal numbers range from 0.2 to 2.1, consistent with those (0.15-3.0) from fluid dynamic experiments of bluff spheres, while they are higher than those (0.15-0.25) from MHD simulations of cylindrical shapes. We thus find that blobs formed in a post-CME CS undergo kinematic oscillations caused by fluid dynamic vortex shedding. The vortex shedding is driven by the interaction of the outward-moving blob having a bluff spherical shape with the background plasma in the post-CME CS.

• 한국재난정보학회 논문집
• /
• 제17권4호
• /
• pp.839-847
• /
• 2021

연구목적: 본 연구에서는 휨을 받는 탄소 나노튜브 보강 기능경사복합재 판의 구조적 거동을 해석하였다. 이를 위해, 등기하해석과 고차전단변형이론을 결합한 수치해석 방법을 이용하였다. 연구방법: 전단보정계수를 사용하지 않고 기하학적 비선형성을 고려할 수 있는 고차전단변형이론을 통하여 휨이 작용하는 탄소 나노튜브 보강 기능경사복합재 판의 비선형 거동방정식을 유도하였으며, 수정된 Newton-Raphson 반복 기법을 사용하여 등기하해석방법에 기반한 시스템 방정식의 해를 구하였다. 연구결과: 탄소 나노튜브의 배치 양상, 폭-두께 비 및 경계조건은 휨을 받는 탄소 나노튜브 보강 기능경사복합재 판의 구조적 거동에 많은 영향을 끼침을 확인하였다. 결론: 제안된 고차전단변형이론에 근거한 등기하해석 방법은 휨을 받는 탄소 나노튜브 보강 기능경사복합재 판의 구조적 거동을 정확하고 효과적으로 해석하는 것을 알 수 있었다.

• 대한한의학원전학회지
• /
• 제35권3호
• /
• pp.41-58
• /
• 2022

Objectives : In this paper, the outline and overall content of the Majinhwiseong, a specialized medical text on measles written by Lee Wonpung was introduced, along with its academic historical meaning. Methods : The entire Majinhwiseong was analyzed according to content and form. In terms of form, organization, construction, cited literature, etc., were studied, while in terms of content, diagnosis of disease pattern and treatment formulas were studied. Later, based on cited medical texts and the author's social position, the academic historical meaning of this book was discussed. Results : Through the Majinhwiseong, Lee Wonpung strengthened the credibility of the text by not only providing medical knowledge on measles but listing their sources and comparing and analyzing related contents. In the diagnosis part, Lee focused on the changes in symptom, shape, color, and pulse of measles, discussing in detail its differential diagnostic methods. In the treatment part, while listing numerous formulas suggested by Ming (明) masters, Lee did not leave out treatment experiences of Joseon physicians. Meanwhile, the Majinhwiseong is indicative of measles medicine in 18th century Joseon having been progressed in the private sector rather than the official, and how the results of private sector medicine were being absorbed into the official realm through the Uiyakdongcham (議藥同參) system. Conclusions : The Majinhwiseong is a practical treatment manual written by clinician Lee Wonpung to deal measles which was widely spread at the time. The author organized existing medical knowledge on measles for clinicians while reflecting outcomes and medical situation of Joseon physicians in this book. Based on these findings, we could verify that medicine in 18th century Joseon had been progressing actively around the private medical sector.

• 한국작물학회지
• /
• 제36권3호
• /
• pp.241-248
• /
• 1991

한국 재래품종, 잡초형 벼인 샤례벼와 앵미 그리고 불복장미 등의 입형 종피색ㆍamy1ose 함량ㆍAlkali 붕양도 및 esterase 반응성 등 몇가지 벼 형질들을 검토하여 Indica의 범주에 속하는 것들이 있음을 밝히고 고농서와 근래 일본인들이 우리나라에서 채집 분류 보고한 기록들 중 Indica에 관한 것을 검토하였다. 이것을 요약하면 다음과 같다. 1. 1920년대에 수집 보존되어 오는 한국 재래품종 중 분명히 Indica의 범주에 속하는 것들이 있다 2. 샤례벼 집단에서 분리 계통화한 것들 중에도 Indica 범주에 속하는 것들이 있다 3. 농가 포장에서 수집한 앵미 중에도Indica 범주에 속하는 것들이 있다. 4. 1302년 불복장미로 발견된 한 시료는 쌀의 형태와 amylose 함량으로 보아 당시 Japonica와 Indica가 혼재되었던 것으로 생각된다. 5. 과거의 기록과 보고를 검토하여 우리나라에는 Japonica 뿐만 아니라 Indica도 오래전부터 재배되었을 것으로 추론하였다.

• 한국컴퓨터정보학회논문지
• /
• 제14권12호
• /
• pp.55-62
• /
• 2009

이 논문에서는 개체를 명확하게 분류하기 어려운 곤충 발자국 영상으로부터 개체를 인식하기 위해서 추출된 특징값 성분들의 기여도를 측정하고, 서로 관계된 기여도에 따라 가중치를 조정하는 퍼지 가중치 결정 방법을 제안한다. 곤충은 몸의 크기가 작아서 발자국은 작은 점의 형태로 나타난다. 그리고 다른 생물체의 발자국과 달리, 규칙적인 형상을 정의하기 어렵고 발자국 데이터와 구분이 분명하지 않는 노이즈와 혼재하기 때문에 개체를 판단하는데 많은 어려움이 있다. 이런 이유로 추출된 곤충 발자국 특징값은 명확하게 구분되는 특징성분 영역과 그렇지 않는 성분을 함께 가지게 된다. 이중 어떤 성분이 다른 성분과 비교하여 다른 클래스와 구분하기에 충분한 변별력을 가질 경우, 개체를 분류하도록 높은 가중치를 할당한다. 산출된 가중치는 퍼지함수에 의해서 출력신호를 결정하고 우세한 출력신호에 의해서 개체를 판단할수 있다. 제안한 기여도 퍼지 가중치 결정 방법을 이용하여 발자국영상의 인식 실험을 수행하고 실험 결과를 제시하였다.

• 천문학회보
• /
• 제46권2호
• /
• pp.75.2-76
• /
• 2021

MESSIER is a science satellite project to observe the Low Surface Brightness (LSB) sky at UV and optical wavelengths. The wide-field, optical system of MESSIER is optimized minimizing optical aberrations through the use of a Linear Astigmatism Free - Three Mirror System (LAF-TMS) combined with freeform mirrors. One of the key factors in observations of the LSB is the shape and spatial variability of the Point Spread Function (PSF) produced by scatterings and diffraction effects within the optical system and beyond (baffle). To assess the various factors affecting the PSF in this design, we use PhoSim, the Photon simulator, which is a fast photon Monte Carlo code designed to include all these effects, and also atmospheric effects (for ground-based telescopes) and phenomena occurring inside of the sensor. PhoSim provides very realistic simulations results and is suitable for simulations of very weak signals. Before the application to the MESSIER optics system, PhoSim had not been validated for confocal off-axis reflective optics (LAF-TMS). As a verification study for the LAF-TMS design, we apply Phosim sequentially. First, we use a single parabolic mirror system and compare the PSF results of the central field with the results from Zemax, CODE V, and the theoretical Airy pattern. We then test a confocal off-axis Cassegrain system and check PhoSim through cross-validation with CODE V. At the same time, we describe the shapes of the freeform mirrors with XY and Zernike polynomials. Finally, we will analyze the LAF-TMS design for the MESSIER optical system.

• 한국과학예술포럼
• /
• 제25권
• /
• pp.379-388
• /
• 2016

인체연속절단 영상은 관상면, 시상면 영상으로 재구성할 경우 절단무늬가 발생한다. 이러한 문제는 FFT(Fast Fourier Transform)와 놋치필터를 이용하여 제거할 수 있었지만 놋치필터의 사용으로 급격한 주파수 변화에 따른 파문현상의 발생은 여전히 문제로 남아 있다. 따라서 본 연구는 놋치필터의 다양한 형태와 효과를 알아보고 인체연속절단면 영상에 적합한 놋치필터 설계를 제안하고자 한다. 연구의 결과는 다음과 같다. 첫째, 방사형-놋치필터를 사용할 경우 상대적으로 절단무늬를 자연스럽게 보정할 수 있다. 둘째, 방사형-놋치 필터를 사용으로 파문현상이 상대적으로 줄어들었다. 향후 이러한 연구 결과와 더욱 진전된 후속 연구를 통해 파문현상을 완전히 제거하고, 실제 인체 정보에 근접한 데이터를 재현할 수 있을 것으로 기대한다.

• Composites Research
• /
• 제36권3호
• /
• pp.230-240
• /
• 2023

전개형 반사판 안테나는 단위 구조물 형태의 반사판이 접힌 상태로 수납되어 발사체에 탑재된 후, 운용궤도에 도달 및 전개되어 임무를 수행하는 위성체이다. 전개형 반사판 안테나는 수납 부피를 줄일 수 있어 발사체의 제한적 수납공간에 대형 우주 구조물을 탑재시킬 수 있으며, 경량소재를 적용할 경우 발사 및 운용 성능 향상에 용이한 장점이 있다. 본 논문에서는 전개형 반사판 안테나를 구성하는 주반사판에 대해 강성 및 강도 등의 구조적 분석을 통해 초기 개념설계를 수행하였다. 탄소섬유 복합재 및 허니콤 코어를 적용하여 경량 복합재 주반사판을 설계하였으며, 적층 패턴 및 형상을 설계 변수로 운용조건에 적합한 주반사판 설계안을 도출하였다. 이후 모드(Modal analysis), 준정적(Quasi-static), 열 구배(Thermal gradient) 및 동적(Dynamic) 거동에 대한 상세 구조해석을 수행하여 경량 복합재 반사판 안테나의 성능을 분석하였다

• 한국의상디자인학회지
• /
• 제25권2호
• /
• pp.1-16
• /
• 2023

Due to the current seriousness of environmental pollution and the eco-friendly movement of the fashion industry, research on sustainable fashion design is being actively conducted. In this study, consumer perception of upcycling products, are divided into image, function, and meaning; and image is further divided into shape, color, and material. It was redefined as pattern, and image recognition was evaluated among men and women in their 20s and 30s, and men and women in their 40s and 50s used as subjects. First, factors that determine each image were extracted based on qualitative analysis of the precedent cases of upcycling bags, and quantitative analysis of the subjects was induced through a questionnaire. As a result of the analysis of evaluation items related to image association, the average frequency analysis of all subjects for each stimuli and the cognitive variance of the frequency analysis by generation by gender were found to be similar. However, awareness of some stimuli by generation showed a significant difference. Overall, in the three stimuli with high overall preference, common features, such as the basic box-shaped symmetrical structure, the monochromatic color of the Munsell system, solid and practical texture, and appropriate use of patterns were identified. In addition, it was confirmed that there was a difference with factors such as femininity, simplicity, touch, and splendor in the measurement factors. In conclusion, it is considered that the main significance of this study is that it excluded the recognition and meaning of upcycling products and explored the original design and image elements of products. Therefore, it is expected that this study will be used as a basic data for responding to the gender image of each generation as an alternative method of sustainable fashion design, and it will be an opportunity to expand the scope of the study to a detailed study beyond the biased topic.

• 한국식생활문화학회지
• /
• 제25권4호
• /
• pp.366-377
• /
• 2010

We surveyed 553 middle school students living in Incheon using questionnaires to compare their food behaviors and snack intake patterns according to weight groups based on BMI. Mean BMI was 20.3 for males and 19.6 for females. The rate of underweight, normalweight and overweight students was 33.3, 51.7, and 15.0%, respectively. Compared to the other two groups, the overweight students perceived their body shape more accurately (p<0.01). Regarding the reasons for skipping dinner, the most frequent answer by the underweight students was 'because of snacks', while that of the overweight students was 'to lose weight' (p<0.01). The normalweight students were found to eat a Korean traditional type breakfast more frequently than the other weight groups (p<0.05). The overweight female group was more likely to overeathabitually, whereas the normalweight and underweight groups tended to overeat when they were under stress (p<0.05). As for the amount of the snack intake, the overweight male students replied that they eat quite a lot of snacks. As a conclusion, the problems found in the underweight group were unbalanced diet and the disturbance of regular meal patterns due to inappropriate snack intake. The problems shown in the overweight group were overeating due to habit or stress, fast eating speed and large amount of snack intake.