• The Journal of Engineering Geology
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• v.31 no.2
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• pp.165-178
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• 2021

The influence of Soil-Water Characteristic Curve (SWCC) fitting parameters for an unsaturated natural slope was evaluated through seepage and slope stability analysis as a function of rainfall. Soil samples were collected from the study area in Jirisan National Park and the physical and mechanical characteristics of unsaturated soil layers were measured in laboratory tests. The saturation depth was calculated via seepage analysis by changing fitting parameters α, the parameter related to the Air Entry Value (AEV) and n, the parameter related to the slope of the SWCC in the range of natural conditions. Slope stability analysis using the limit equilibrium method considered the calculated depth of saturation. Results from seepage analysis for various rainfall conditions indicate the saturation depth in the soil layer suddenly increased as the fitting parameter α decreased; the saturation time for the entire soil layer also decreased. Slope stability analysis considering the calculated depth of saturation shows that the slope safety factor rapidly decreased as the fitting parameter α decreased, whereas the variation in slope safety factor was very small when n increased. Hence, fitting parameter α has a large effect on saturation depth during rainfall and therefore on slope stability, whereas slope stability is relatively unaffected by the fitting parameter n.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.2
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• pp.101-106
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• 2007

The optical performance of the mirror for satellite camera is highly dependent on the adhesive properties between the mirror and its support. Therefore, in order to design a mirror with high optical performance, the mechanical properties of adhesives should be well defined. In this paper, the mechanical properties of three kinds of space adhesives are studied. Elastic moduli of the adhesives are determined by tensile tests. Stress-strain relation is obtained by using exponential curve fitting for the adhesive which shows non-linear behavior. In case of the linear behavior material, elastic modulus is calculated through linear curve fitting. For the tensile tests, several points have been selected in the operating temperature range of the adhesive. The elastic modulus of each adhesive is expressed as a function of temperature. Characteristics of the adhesives are discussed regarding their temperature sensitivity.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.435-436
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• 2012

본 논문은 가변 조정계수를 이용한 적응형 MPPT 제어 기법을 제안한다. MPPT 제어 루프가 소신호 모델링을 통해 구성되며, PV array 의 동작점에 상관없이 MPPT 제어의 성능을 일정하게 유지하기 위한 가변 조정계수가 결정된다. 가변 조정계수는 오차에 대한 근사화된 곡선맞춤 다항식을 통해 결정되며, 이를 통해 사용자가 원하는 MPPT 의 동특성과 안정성을 전 MPPT 영역에 걸쳐 확보할 수 있다. 제안된 MPPT 기법의 타당성은 3KW 급 시스템에 대한 실험을 통해 검증한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.386-389
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• 2016

최근 남녀노소를 불문하고 피부 관리에 대한 관심이 증가하면서, 피부 개선에 효과적인 화장품의 선택에 관심이 높아지고 있다. 하지만 다양한 화장품들을 대상으로 자동화된 고객 맞춤형 화장품 추천은 그 발전이 더디고, 이와 관련된 연구 또한 아직 미미한 실정이다. 또한, 다양한 특성을 가지는 고객 피부 데이터 셋의 확보가 어려운 상황에서, 소수의 데이터 표본만을 이용하여 화장품 추천이 진행되고 있어 추천의 정확도를 확보하지 못하고 있다. 본 논문은 스마트폰용 휴대용 카메라를 이용하여 고객의 피부 상태를 진단한 후, 고객의 피부 개선에 적합한 화장품을 자동으로 추천하는 기법을 제안한다. 먼저, 화장품 추천을 위해 사용자의 SNS 데이터와 피부 데이터를 수집 및 분석하여 추천 리스트를 생성한다. 이를 기반으로, 추천된 각 화장품의 스코어를 계산한다. 그 다음, 피부 개선 순위와 스코어 기반의 화장품 특성 순위 간의 상관계수를 이용하여 가장 높은 상관계수의 화장품을 우선 추천한다. 성능 평가를 위해 실제 화장품 회사에서 제시한 화장품 추천 리스트와 본 논문에서 제안한 방법을 적용한 화장품 추천 리스트를 비교함으로써 효용성과 타당성을 입증하였다.

• Progress in Medical Physics
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• v.26 no.3
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• pp.153-159
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• 2015

This study is to evaluate thedosiemtric leaf gap (DLG) at different depths for dynamic intensity-modulated radiation therapy (IMRT) in order to evaluate the absolute dose and dose distribution according to the different positions of tumors and compare the measured and planned the multileaf collimator (MLC) transmission factor (T.F.) and DLG values. We used the 6 MV and 15 MV photon beam from linear accelerator with a Millenium 120 MLC system. After the import the DICOM RT files, we measured the absolute dose at different depths (2 cm, 5 cm, 10 cm, and 15 cm) to calculate the MLC T. F. and DLG. For 6 MV photon beam, the measured both MLC T. F. and DLG were increased with the increase the measured depths. When applying to treatment planning systemas fixed transmission factor with its value measured under the reference condition at depth of 5 cm, although the difference fixed and varied transmission factor is not significant, the dosiemtric effect could be presented according to the depth that the tumor is placed. Therefore, we are planning to investigate the treatment planning system whichthe T. F. and DLG factor according to at the different depths can be applied in the patient-specific treatment plan.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.4
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• pp.403-408
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• 2011

Purpose: To study the concentration distribution and diffusion depth in tinted lenses using the law of diffusion. Methods: The measured values taken from experiments were fitted with the theoretical fitting curve induced on the basis of Fick's second law of diffusion. Results: The fitting curves were in very good agreement with the measured values. As the results, we found the quantitative relationship between mass of dye solution diffused into the tinted lens per unit area and dyeing time, and evaluated concentration distribution of dye in tinted lens, diffusion depth, etc. Conclusions: The dyeing mechanism of tinted lenses can be well described by diffusion theory.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.04a
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• pp.554-557
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• 2016

2015년 우리나라 스마트폰 보급률이 83%에 다다르고 인터넷 정보 검색은 PC보다 모바일이 추월한지 오래다. 범람하는 정보 안에서 편하고 빠른 것에 익숙해진 사용자들은 이제 개인화된 맞춤형 추천 정보의 제공을 원한다. 맞춤형 추천을 위해서는 사용자의 행동을 이해하고 추천하는 것이 필요하다. 현재 대중화된 개인 추천 서비스는 책과 영화가 있는데 생활에 많은 부분을 차지하고 있는 음식점 방문에 대해서도 맞춤형 추천 서비스를 제공해 줄 수 있다. 본 논문에서는 음식점 방문에 대한 비슷한 태도를 보인 사용자를 추출한 후 방문했던 장소를 비교하여 추천하는 사용자 행동 기반 다속성 태도 모델 기반의 장소 추천 모델을 연구한다. 다속성 태도점수를 산출하기 위해 피쉬바인(Fishbein) 방정식을 활용하고 피어슨 상관계수를 이용하여 사용자들간의 유사한 장소를 추출했다. 그리고 그룹렌즈의 선호도 예측 알고리즘을 활용하여 추천 대상 장소를 선정하고 유클라디안 거리법으로 사용자의 거리기반 장소를 추천하였다. 또한 본 논문에서는 실제 데이터를 이용한 실험을 통해 본 논문에서 제시한 시스템의 우수성도 입증하였다.

• Smart Media Journal
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• v.5 no.2
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• pp.84-89
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• 2016

For a place-recommendation model based on user's behavior and multi-attribute attitude in this thesis. We focus groups that show similar patterns of visiting restaurants and then compare one and the other. We make use of The Fishbein Equation, Pearson's Correlation Coefficient to calculate multi-attribute attitude scores. Furthermore, We also make use of Preference Prediction Algorithm and Distance based method named "Euclidean Distance" to provide accurate results. We can demonstrate how excellent this system is through several experiments carried out with actual data.

• Journal of Biomedical Engineering Research
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• v.18 no.4
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• pp.499-505
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• 1997

A non-invasive technique to measure absorption and scattering coefficients was investigated The reflected backscattered light from the surface of phantom and biological tissue was obtained by using a time-correlated single photon counting system in pico-second time domain. The absorption and scattering coefficients were acquired by the time of peak and asymptotic behavior of the time-resolved reflectance curve and agreed well the ones that is obtained with deconvolution method It was found that the approximation method was good for biological medium to calculate optical properties due to its convenience and accuracy.

• The KIPS Transactions:PartB
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• v.16B no.1
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• pp.47-54
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• 2009

Automatic object recognition in 3D measuring data is of great interest in many application fields e.g. computer vision, reverse engineering and digital factory. In this paper we present a software tool for a fully automatic object detection and parameter estimation in unordered and noisy point clouds with a large number of data points. The software consists of three interactive modules each for model selection, point segmentation and model fitting, in which the orthogonal distance fitting (ODF) plays an important role. The ODF algorithms estimate model parameters by minimizing the square sum of the shortest distances between model feature and measurement points. The local quadric surface fitted through ODF to a randomly touched small initial patch of the point cloud provides the necessary initial information for the overall procedures of model selection, point segmentation and model fitting. The performance of the presented software tool will be demonstrated by applying to point clouds.