• 대한영상의학회지
• /
• 제82권2호
• /
• pp.359-370
• /
• 2021

목적 증상이 있는 123명의 coronavirus disease 2019 (이하 COVID-19) 환자에서 흉부 CT 병변의 소견과 일련의 변화를 분석하였다. 대상과 방법 2020년 2월 19일부터 4월 7일까지 총 123명의 COVID-19 환자(남성, 44명; 여성, 79명; 평균 연령 59.2 ± 18.6)를 후향적으로 연구하였다. 총 234개의 CT 스캔을 검토하여 패턴[급성 폐포 손상(acute alveolar insult) 패턴: 간유리음영, 돌조각보도모양, 혼합된 패턴, 또는 폐경화; 기질화 폐렴(organizing pneumonia) 패턴: 소엽주위 패턴, 띠 음영, 곡선형 음영, 역달무리 음영, 또는 소결절경화; 호전형 패턴: 순수 간유리음영, 잔존 곡선형 음영, 또는 소결절경화]과 폐 이상의 연속적인 변화를 분석하였다. 피어슨 카이 제곱 검정과 피셔의 정확 검정을 사용하여 시간 경과에 따른 급성 폐포 손상 패턴, 기질화 폐렴 패턴, 호전형 패턴의 비율을 비교하고, 패턴과 질병 심각도 간의 연관성을 분석하였다. 결과 초기 입원군(증상 발병 후 0~10일)의 CT 패턴은 급성 폐포 손상 패턴(87%) 이 가장 많았고, 후기 입원군(10일 이상)에서는 기질화 폐렴 패턴(45.7%), 퇴원군(퇴원 시 및 퇴원 후)에서는 호전형 패턴(47.2%; 84.8%)이 가장 많았다. 시간 경과에 따른 우세한 CT 패턴에 대한 비율의 차이는 통계적으로 유의하였다(p < 0.001, 피어슨 카이 제곱 검정). 패턴과 질병 중증도 간에 통계적으로 유의한 연관성은 발견되지 않았다(p = 0.055, 피셔의 정확 검정). 후속 CT 스캔에서 병변의 섬유화는 관찰되지 않았다. 결론 COVID-19 환자의 연속적 CT 스캔은 COVID 폐렴의 폐 손상 및 복구의 단계로서 다양한 CT 영상 소견을 보여주었다.

• 대한가정학회지
• /
• 제38권7호
• /
• pp.1-12
• /
• 2000

Although the term 'family business' is relatively new, this style of business is universal. An Unusual feature that must be noted, is that even though it is a common style of business is not clearly defined. The purpose of this study is to identify the different family participation patterns, and the variables that effect different types of participation. '1997 Daewoo Panel Data' was used. Some descriptive statistics and a multinomial logit model were employed for the analysis. The standard type of business focused on in this study was a family owned and operated 'ma and pa' typed business and the sample was limited to households where one or both of the partners involved in a family owned and operated business. The main resets obtained from this sample were as follows: 1. Personal characteristics such as respondents' gender, age and educational level were important variables that effected the participation of family members in the business. As can be seen in the gender analysis, family businesses owned by men showed all available patterns of family operated businesses in relatively high numbers. A large percentage of businesses owned women were of self-employed pattern. According to the analysis by age and educational level, young people with a high level of education tend to managed their small businesses by employing others rather than utilising the self-employed or family operated pattern. 2. While big families showed a high percentage of a combination pattern of a family-run, and ordinary employer/employee company, relatively small families usually opted for purely family-run businesses. Whether the family have children under 6 or not, and the number of children under 6 did net significantly effect to the patterns of the family system of small family businesses. 3. The size, location and kind of family business also effected participation patterns of the family members significantly. These results suggest that further study will be required to gain more exact and meaningful information to help Korean family businesses.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 춘계학술대회 논문집
• /
• pp.1925-1928
• /
• 2005

In recent years, the importance of the characterization of fall for a fracture prevention system keeps increasing since fracture from a fall can lead to serious health problems. Fall is one of the major sources which increase morbidity in elderly people. In terms of the cost and the influence to the quality of life, the most serious injury with hip fractures is caused by falls. The traditional methods in characterizing fall patterns have been mainly by the epidemiological surveys. With surveys, the exact data of fall patterns can not been acquired. In this paper, we measured and analyzed with the parameters related to fall pattern such as velocities and accelerations during the motion of falls using 3D motion capture program. We acquired the parameters of the fall pattern of intentional and unexpected fall. The result showed that the variation of velocity and acceleration during fall was very important in characterizing fall pattern, which of vital importance for the development of a fracture prevention system and for the safety of the elderly

• 한국항해항만학회:학술대회논문집
• /
• 한국항해항만학회 2007년도 추계학술대회 및 제23회 정기총회
• /
• pp.337-339
• /
• 2007

컨테이너 터미널의 생산성은 안벽 크레인의 생산성으로 간주 될 수 있다. 안벽크레인의 경우 그 기계적인 생산력은 이미 고정되어 있기 때문에 최대생산성을 발휘하기 위해 장치장에서 크레인으로의 원활한 화물의 흐름이 요구되고 있다. 이를 위해서는 터미널 생산성에 직접 관련이 있는 수출 화물 장치장을 효율적으로 계획하고 운영해야 함으로서, 장치장, 크레인간 병목현상을 줄이고 원활한 화물 흐름을 유도해야 한다. 하지만 수출 컨테이너의 경우 그 반입 시점이 매우 불확실하고, 임의의 시점에 반입량이 예측 불가능한 특성으로 인해 효율적인 수출 장치장 계획에 어려움을 겪고 있다. 따라서 본 연구에서는 터미널의 반입 패턴을 분석하고 이에 맞는 수출 장치장 계획을 수립하는 방법에 대해 연구해 보았다.

• 한국정밀공학회지
• /
• 제18권11호
• /
• pp.51-57
• /
• 2001

A light beam reflected from a machined surface generally containes information concerning about its surface roughness. This study examines and proposes a surface roughness measurement technique for on-machine measurement of machined surfaces. The technique is based on the measurement of a reflected laser beam pattern and the statistical analysis of its light intensity distribution. The surface roughness was found to be closely related to the standard deviation of the light intensity on the primary axis of the reflected pattern. An image acquisition device is made up of a laser diode, a half mirror, a screen, and a CCD camera. The exact image with the primary and secondary axes of a reflected laser beam pattern is calculated through such image processing algorithm as thresholding, edge detection, image rotation, segmentation, etc. A median filter and a surrounding light correction algorithm are improve the image quality and reduce the measuring error. Using the developed measuring device the effect of screen materials and workpiece and workpiece materials was investigated. Experimental results regarding to relatively high-quality surfaces machined by grinding, polishing, lapping processes have shown the measurement error is within 10% in the range of $0.1{mu}m~0.8{\mu}m R_q.$Therefore, the proposed method is thought to be effectively used when quick measurements is needed with workpieces fixed on the machine.

• 한국컴퓨터정보학회논문지
• /
• 제11권4호
• /
• pp.77-85
• /
• 2006

동영상 프레임의 블록 정합에 있어서 현재 프레임의 블록들 사이에는 공간적 상관성이 존재한다. 본 논문에서는 움직임 벡터의 중심 지향적 특성과 동영상 내의 공간적 상관성을 이용한 개선된 고속 블록 정합 움직임 추정 알고리즘을 제안한다. 제안하는 알고리즘은 현재 프레임의 인접한 매크로 블록들에서 예측된 움직임 벡터와 크로스-육각 탐색 패턴을 이용하여 정확한 움직임 벡터를 결정한다. 실험 결과를 통해 제안하는 알고리즘이 예측 탐색 알고리즘 (NNS)과 고속 블록 정합 알고리즘 (CHS)에 비해 탐색 속도와 화질 면에서 우수한 성능을 나타내었다. 제안하는 알고리즘을 사용하였을 때 탐색 속도 측면에서는 약 $0.1{\sim}38%$ 정도의 향상을 보였고, 화질 측면에서도 PSNR (Peak Signal Noise Ratio) 값이 약 $0.05{\sim}2.5dB$ 정도 향상되었다.

• Mycobiology
• /
• 제49권5호
• /
• pp.461-468
• /
• 2021

The genus Laccaria (Hydnangiaceae, Agaricales) plays an important role in forest ecosystems as an ectomycorrhizal fungus, contributing to nutrient cycles through symbiosis with many types of trees. Though understanding Laccaria diversity and distribution patterns, as well as its association with host plants, is fundamental to constructing a balanced plant diversity and conducting effective forest management, previous studies have not been effective in accurately investigating, as they relied heavily on specimen collection alone. To investigate the true diversity and distribution pattern of Laccaria species and determine their host types, we used four different approaches: specimen-based analysis, open database search (ODS), NGS analysis, and species-specific PCR (SSP). As a result, 14 Laccaria species have been confirmed in Korea. Results regarding the species distribution pattern were different between specimen-based analysis and SSP. However, when both were integrated, the exact distribution pattern of each Laccaria species was determined. In addition, the SSP revealed that many Laccaria species have a wide range of host types. This study shows that using these four different approaches is useful in determining the diversity, distribution, and host of ECM fungi. Furthermore, results obtained for Laccaria will serve as a baseline to help understand the role of ECM fungi in forest management in response to climate change.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
• /
• 제8권4호
• /
• pp.87-92
• /
• 2019

본 연구에서는 머신 러닝 기법을 활용하여 공장에서 발생하는 에너지 사용량에 대한 데이터 분석 및 패턴 추출에 대해 다룬다. 통계학이나 기존의 방법들은 몇 가지 물리적 특성을 반영하는 수학적 모델을 구축하는 반면, 머신 러닝을 통한 접근방법은 데이터 학습을 통하여 모델의 계수들을 결정하게 된다. 기존의 방법들은 특정한 구조를 갖는 수학적 모델을 구축해야 한다는 어려움이 있으며 과연 데이터의 특징들을 잘 반영하는지에 대한 의문이 존재했다. 그러나 머신 러닝을 통한 방법은 사람이 구축하기 어려운 작업들을 용이하게 구축한다는 장점을 가지고 있기 때문에 데이터 간의 관계를 파악하기에 더 효율적이라는 장점을 가지고 있다. 공장의 에너지 소비에 직접적으로 영향을 끼치는 요소들이 존재하며 이러한 전력 소비는 시간에 따른 데이터로 나타나게 된다. 각 요소들로부터 발생하는 소비 전력을 계측하고 데이터 베이스를 구축하기 위해 각 요소에 센서를 장착하였다. 취득된 데이터에 대해 전처리 과정 및 통계적인 분석을 거친 뒤, 머신 러닝을 통해 패턴을 분석하는 과정을 거쳤다. 이를 통해 공장에서 발생하는 소비 전력 데이터에 대한 패턴 분석을 진행하였다.

• Interaction and multiscale mechanics
• /
• 제4권4호
• /
• pp.313-320
• /
• 2011

This paper proposes an approximate formulation to estimate the bifurcation buckling loads of cylindrical shells with soft elastic cores under the conditions of axial compression. In general, thin-walled, axially compressed cylindrical shells buckle into a diamond pattern in the elastic range. However, buckling symmetrical with respect to the axis of the cylinder may occur when the cylindrical shell is supported by an elastic medium. By considering this characteristic, we introduce the simplified approximate formulation that can give sufficiently accurate results for the bifurcation buckling loads of cylindrical shells. Moreover the results are compared with the exact buckling loads in order to confirm the accuracy of the proposed approximate formulation.

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 1999년도 Proceedings of International Symposium on Remote Sensing
• /
• pp.479-484
• /
• 1999

Rice crop has relatively short growing season during the summer in Korea and, therefore, it is often difficult to acquire cloud-free imagery on time. This study was attempt to define the temporal characteristics of radar backscattering observed from satellite L-band SAR data on different growing stages of rice crop. Six scenes of multi-temporal JERS SAR data were obtained from the transplanting season to the harvesting month of October. Six layers of multi-temporal SAR data were registered on a common geographic coordinate system. Using topographic maps, field collected data, and Landsat TM data, several sample rice fields were delineated from the imagery and their relative radar backscatters were calculated by using a set of reference targets. The temporal pattern of radar backscattering was very distinctive by the growing stage of rice crop. It was also separable between two types of rice fields having different cultivation practices. Considering the temporal characteristics of radar backscattering observed from the study, it is obvious that a certain date of the growing season can be more effective to delineate the exact area of the cultivated rice crop field.