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큐빅상 자성 나노입자를 함유한 초상자성 마이크로 니들의 제작 및 특성 분석
민현규,김진아,김진철,이승준 조선대학교 공학기술연구원 2019 공학기술논문지 Vol.12 No.3
In this study, we have prepared the iron oxide nanoparticles under cubic phase to prepare magnetic cubosome nanopaticles(MCNs). Then, superparamagnetic microneedles(SMMNs) containing MCNs were manufactured through PDMS mold by casting technique. And then, the shapes of SMMNs were imaged by scanning electron microscopy(SEM). Also, skin permeability and cell viability were measured to confirm mechanical strength and cytotoxicity, respectively of SMMNs. Also, magnetic hysteresis measurements were performed using a SQUID-VSM magnetometer to investigate the magnetic properties of SMMNs. Magnetic hysteresis of SMMNs showed a superparamagnetic curve. These results suggest that SMMNs could be utilized as an MRI contrast agent.
Performance Improvement of Classifier by Combining Disjunctive Normal Form features
민현규,강동중 한국인터넷방송통신학회 2018 International Journal of Internet, Broadcasting an Vol.10 No.4
This paper describes a visual object detection approach utilizing ensemble based machine learning. Object detection methods employing 1D features have the benefit of fast calculation speed. However, for real image with complex background, detection accuracy and performance are degraded. In this paper, we propose an ensemble learning algorithm that combines a 1D feature classifier and 2D DNF (Disjunctive Normal Form) classifier to improve the object detection performance in a single input image. Also, to improve the computing efficiency and accuracy, we propose a feature selecting method to reduce the computing time and ensemble algorithm by combining the 1D features and 2D DNF features. In the verification experiments, we selected the Haar-like feature as the 1D image descriptor, and demonstrated the performance of the algorithm on a few datasets such as face and vehicle.
민현규,강동중,김기주,박준협 한국정밀공학회 2017 International Journal of Precision Engineering and Vol.18 No.11
Digital image correlation technique has been widely and effectively applied in the measurement of material properties. This paper presents a new method named Stride-Crawl Approaching Method by combining the steepest descent method and the Levenberg- Marquardt method. It is no longer necessary to provide initial guess of deformation by applying this method. And, the result can always converge to the absolute optimum. Moreover, regardless of the deformations are large or small, this method can always be applied directly. Therefore, this method is more suitable and has great advantages compared to other conventional methods. The proposed method was tested two different simple deformation forms including the rigid body translation, and the uniform tensile elongation by comparing the experimental values with the theoretical values. The images for the verification were generated by numerical simulation. And then the errors were analyzed and it turned out that the error of the displacements was about pixels and the error of displacement gradients was usually limited in 3%. Finally, the stress-strain curves of BeCu was drawn using the output data of the proposed method. And then the tensile properties of BeCu including the elastic modulus, 0.2% yield strength, ultimate tensile strength, and fracture strain were obtained from the stress-strain curves.
비 자살목적 의도적 음독환자의 정신과 진료 의뢰가 필요한가?
민현규,권오영,이종석,홍훈표,고영관,백종우,김신철,김동필,최한성 대한응급의학회 2010 대한응급의학회지 Vol.21 No.6
Purpose: The purpose of this study was to investigate the relationship between suicide risk factors and psychiatric disorders,and between suicide risk factors and suicide attempts after discharge, and to analyze the necessity of a psychiatrist referral in patients who intentionally ingested drug but did not make a suicide attempt. Methods: Between January 1, 2004 and December 31,2008, we investigated cases of intentional drug ingestion in patients greater than 15 years of age who visited Kyung Hee University emergency medical center. We divided the patients into two groups - a suicide attempt group and a non-suicide attempt group. The difference between suicide risk factors of the two groups was investigated prospectively. Among the risk factors for suicide, we determined whether psychiatric diagnosis was highly associated with suicide and whether it was an influential factor in suicide attempts after discharge. SPSS version 13.0 was used for statistical analysis. Chi-square, paired sample t-test, and Fisher’s exact test were performed, and a p<0.05 was considered to be statistically significant. Results: There were no significant differences in suicide risk factors between the two groups (p>0.05). Patients who did not attempt suicide who had a psychiatric history associated with suicide attempts, who had previous suicide attempts, who had a family history of suicide, and who lived alone, may have psychiatric disorders associated with suicide or suicide attempt after discharge (p<0.05). Conclusion: All patients who intentionally ingested drugs should be given a psychiatrist referral, even if the patients did not attempt suicide. In particular, the psychiatric referral should be made when the patient has risk factors such as a psychiatric history associated with suicide attempts, previous suicide attempts, a family history of suicide, and living alone.
박막 인장 시험 시 신뢰성 높은 데이터 획득을 위한 초기 조건 설정 방법
민현규(Hyeon-Gyu Min),박준협(Jun-Hyub Park) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.06
박막의 기계적 물성 측정은 반도체 공정 및 MEMS 기술을 적용한 제품의 설계 및 해석을 위한 기본 자료가 될 뿐만 아니라, 부품의 신뢰성 문제와 깊은 관련이 있다. 같은 재료라 하더라도 박막은 거대 구조물(bulk)과는 기계적 물성이 현저히 다르므로, 실제 공정 및 제품에 사용되는 구조물의 크기를 가지는 시편을 제작하여 그물성을 측정할 필요가 있다. 따라서 본 연구에서는 박막의 기계적 물성의 측정을 위한 인장 시험 시 시편의 공정영향이나 시편 체결에 의한 영향을 분석하였다. 이를 위해서 구리 박막의 전해 도금을 통해서 제작하고 시편의 거동을 정밀하게 관찰할 수 있는 in-situ SEM 인장 시험기를 제작하였다. 이를 통해서 인장 시험 시 시편 체결 및 정렬 등 결과에 영향을 주는 인자의 영향을 줄이기 위한 초기 실험 방법과 박막 공정 시 발생하는 잔류 변형률등을 제거하는 방법을 제안한다.