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이동현,이승환,이성갑,이규탁,이영희,Lee, Dong-Hyun,Lee, Seung-Hwan,Lee, Sung-Gap,Lee, Ku-Tak,Lee, Young-Hie 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.7
We studied sintering temperature to enhance the piezoelectric properties of $0.98(Na_{0.5}K_{0.5})NbO_3-0.02Li(Sb_{0.17}Ta_{0.83})O_3$+0.01wt%ZnO (hereafter NKN-LST+ZnO) lead free piezoelectric ceramics. The synthesis and sintering method were the conventional solid state reaction method and sintering was executed at $1,080\sim1,120^{\circ}C$. We found that NKN-LST+ZnO ceramics at optimal sintering temperature showed the improved piezoelectric properties at the optimal sintering temperature. The NKN-LST+ZnO ceramics show good performance with piezoelectric constant $d_{33}$= 153 pC/N sintered at $1,090^{\circ}C$. The results reveal that NKN-LST+ZnO ceramics are promising candidate materials for lead-free piezoelectric application.
이종입자 강화 SiC/Al7075 금속복합재료의 압축특성 및 마모특성 연구
이동현,조승찬,김양도,이상관,이상복,조일국,Lee, Donghyun,Cho, Seungchan,Kim, Yangdo,Lee, Sang-Kwan,Lee, Sang-Bok,Jo, Ilguk 한국복합재료학회 2017 Composites research Vol.30 No.5
본 연구에서는 액상가압공정을 통해 고체적율의 SiC 입자가 균일 분산된 알루미늄 금속복합재료를 제조하고, 미세조직, 기계적 특성 및 내마모 특성에 대해 분석하였다. 입자크기가 다른 이종 SiC 입자가 약 60 vol.% 이상의 체적율로 균일하게 분산된 SiC/Al7075 복합재료는 단일 SiC 입자로 강화된 복합재료에 비해 체적율이 약 12% 이상 높았으며 압축강도가 200 MPa 이상 증가하였다. 내마모시험 결과 이종 SiC 입자 금속복합재료의 경우 마모너비와 깊이가 각각 $285.1{\mu}m$, $0.45{\mu}m$이며, 마찰계수는 0.16으로 내마모 특성이 가장 우수하였다. In this study, we have investigated microstructure, mechanical properties and wear characteristic of aluminum metal matrix composites with a high volume fraction and uniformly dispersed SiC particles which produced by a liquid pressing process. The volume fraction of bimodal SiC/Al7075 composite was 12% higher than that of the monomodal SiC/Al7075 composite and a compressive strength is increased about 200 MPa. As a result of the abrasion test, the wear width and depth of the bimodal SiC/Al7075 composite were $285.1{\mu}m$ and $0.45{\mu}m$, respectively. The coefficient of friction of bimodal SiC/Al7075 was 0.16.
이동현,김지은,송채빈,이현주,송원영,이태준,이상훈,태기식,Lee, D.H.,Kim, J.E.,Song, C.B.,Lee, H.J.,Song, W.Y.,Lee, T.J.,Lee, S.H.,Tae, Ki-Sik 대한의용생체공학회 2016 의공학회지 Vol.37 No.3
Sexual addiction is accompanied with anxiety, psychological and physical dependence. Also, sexual addict want to make their presence through sexual adventures and seem sexually obsessed. In this study, we examined the changes of brain activity related to sexual addiction by utilizing the developed multi-sensory therapy after 4-weeks sex offender treatment program. We analyzed the electroencephalogram (EEG) activity changes in the subjects and regions of brain. As a result, the theta wave significantly increased after treatment than before (p < 0.001). The absolute alpha wave was increased whereas the relative alpha waves were decrease significantly (p < 0.001). The results could conclude that multi-sensory therapy on sex offender shows more stable status against sexual stimulations. Moreover, the reduction of the relative alpha waves in parietal lobe of sex offender is correlated to the less attention on sexual stimulations. The multi-sensory therapy not only provides a neurobiological explanation, but also can be used for clinical implications, i.e. prevention and treatments, for sex addiction.
하악 전돌증 환자에서 전산화 단층 촬영을 이용한 하악관의 해부학적 위치에 관한 연구
이동현,김재원,이수연,김재현,안상헌,이상한,장현중,Lee, Dong-Hyun,Kim, Jae-Won,Lee, Su-Youn,Kim, Jae-Hyun,An, Sang-Heon,Lee, Sang-Han,Jang, Hyun-Jung 대한악안면성형재건외과학회 2009 Maxillofacial Plastic Reconstructive Surgery Vol.31 No.6
Purpose: In this study, we analyzed and compared the anatomical position of the mandibular canal in normal occlusion and mandibular prognathism patients. Patients and Methods: Computed tomography image from 58 patients were divided into normal occlusion group and mandibular prognathism group, and each measurement were taken in the each measuring points(2nd premolar, 1st molar, 2nd molar, 3rd molar, ramus). Measurements were statistically analyzed by student's t-test. Results: BC (Thickness of the buccal cortex) value was 2.3~2.7 mm, CB (Distance from the canal to the lingual aspect of the buccal cortex) value was 1.3~4.3 mm, MC (Diameter of the canal) value was 3.2~3.8 mm, LI (Distance from the canal to the lingual aspect of the lingual cortex) value was 2.0~3.7 mm, TM (Thickness of the total mandible) value was 9.5~12.9 mm and CM (Distance from the canal to the inferior border of the mandible) value was 6.9~17.5 mm. Conclusion: In the comparison between two groups, there was statistically significant difference in CB value of 2nd, 3rd molar between normal occlusion and mandibular prognathism, and other value in the rest of the measuring points didn't show statistically significant difference.
신경외과 수술로 인한 신경영양각막염 환자에서 동일초점현미경을 이용한 각막미세구조 변화 분석
이동현*,최은영*,김응권,이형근,Dong Hyun Lee*,Eun Young Choi*,Eung Kweon Kim,Hyung Keun Lee 대한안과학회 2014 대한안과학회지 Vol.55 No.12
Purpose: To investigate the changes of the corneal microstructure of neurosurgically-induced neurotrophic keratitis patients compared to normal human corneas using in vivo confocal microscope (IVCM). Methods: Ten eyes in the normal control group and 11 eyes in the neurosurgically-induced neurotrophic keratitis patient group were included in the present study. After corneal sensitivity tests were performed, thickness of each layer and number of endothelial cells and stromal keratocytes in the cornea were assessed using IVCM. Morphological characteristics of the corneal nerves were measured by ImageJ software. Results: After analysis of corneal thickness layer by layer, the Bowman’s layer was significantly reduced in the neurosurgicallyinduced neurotrophic keratitis patient group compared with the normal control group (<EM>p</EM> = 0.016) and the portion of Bowman’s layer was significantly reduced in the neurosurgically-induced neurotrophic keratitis patient group compared with the control group (<EM>p</EM> = 0.024). The nerve fiber length per square-millimeter became significantly shorter compared to the normal control group (<EM>p </EM>= 0.042). The nerve fiber length per square millimeter showed significant correlations with the number of fibers, number of beading, branching patterns, and nerve tortuosity (<EM>p</EM> = 0.002, 0.002, 0.013 and 0.034, respectively). The number of endothelial cells and stromal keratocytes, the number of nerve fibers and beading, and the pattern of branching and nerve tortuosity showed no significant differences between the normal and neurosurgically-induced neurotrophic keratitis patient groups. Conclusions: Our results showed that decreased thickness of Bowman’s layer may be related to the decreased corneal nerve distribution, secondary to the dysfunction of trigeminal nerve branch innervating the cornea. The microstructural changes of Bowman’s layer can help diagnose the disease and evaluate the current status in neurosurgically-induced neurotrophic keratitis patients. J Korean Ophthalmol Soc 2014;55(12):1765-1771
임플란트 증례에서 발생하는 심미적 문제점들에 관한 고찰
이동현,Lee, Dong-Hyun 대한심미치과학회 2015 Journal of the Korean Academy of Esthetic Dentistr Vol.24 No.1
전치부 임플란트의 심미성에 영향을 미치는 중요한 요소는 다음과 같다. 1) 임플란트 식립체의 올바른 위치, 2) 치조골의 충분한 양, 3) 연조직의 최적의 양. 임플란트 위치는 심미적인 치료결과를 얻는 데에 가장 중요한 요소일 것이다. 임플란트의 3차원적 위치는 치조제의 위치와 방향에 의해 결정된다. 임상가들은 수복물을 제작할 때 흔히 자연치를 모방하려 한다. 그러나 심미적인 진단 및 치료를 하는 과정에서 잊지 말아야 할 것은 얼굴형태, 입술, 치은, 치조제, 그리고 잔존치아들과의 상관관계를 고려하는 것이다. 전치부는 구치부에 비해 생물학적으로 불리하며, 조금이라도 임플란트 위치가 틀어지면 심미적으로 좋지 않은 결과를 야기할 수 있다. 임플란트 3치원적 위치의 생물학적, 보철적 의미를 이해한다면, 전치부에 더욱 심미적인 결과를 얻을 수 있을 것이다. The critical factors affecting the esthetics of anterior implants can be summarized as following: 1) Correct positioning of implant fixture, 2) Enough amount of alveolar bone, 3) Optimum volume of soft tissue. The position of implant is probably the most important factor in obtaining esthetic treatment outcome. The 3-dimensional orientation of implant is determined by the position on the alveolar ridge and its direction. Clinicians often try to mimic natural teeth when fabricating restorations. During the course of esthetic diagnosis and treatment, however, one should not forget to consider the correlation between facial pattern, lips, gingiva, alveolar ridge, as well as remaining dentition. Since anterior region is biologically unfavorable when compared with posterior region, one minor discrepancy in positioning of implant can cause esthetically undesirable treatment outcome. If one understands the biological and prosthetic meaning of implant' s 3-dimensional position, he or she can achieve superior esthetic outcome in anterior region.
심층 컨벌루션 신경망 기반의 실시간 드론 탐지 알고리즘
이동현,Lee, Dong-Hyun 한국로봇학회 2017 로봇학회 논문지 Vol.12 No.4
As drones gain more popularity these days, drone detection becomes more important part of the drone systems for safety, privacy, crime prevention and etc. However, existing drone detection systems are expensive and heavy so that they are only suitable for industrial or military purpose. This paper proposes a novel approach for training Convolutional Neural Networks to detect drones from images that can be used in embedded systems. Unlike previous works that consider the class probability of the image areas where the class object exists, the proposed approach takes account of all areas in the image for robust classification and object detection. Moreover, a novel loss function is proposed for the CNN to learn more effectively from limited amount of training data. The experimental results with various drone images show that the proposed approach performs efficiently in real drone detection scenarios.
차동 구동형 모바일 로봇의 효율적인 운용을 위한 우선순위 기반의 원격제어 시스템
이동현,Lee, Dong-Hyun 대한임베디드공학회 2020 대한임베디드공학회논문지 Vol.15 No.2
In situations where mobile robots are operated either by autonomous systems or human operators, such as smart factories, priority-based teleoperation is crucial for the multiple operators with different priority to take over the right of the robot control without conflict. This paper proposes a priority-based teleoperation system for multiple operators to control the robots. This paper also introduces an efficient joystick-based robot control command generation algorithm for differential-drive mobile robots. The proposed system is implemented with ROS (Robot Operating System) and embedded control boards, and is applied to Pioneer 3AT mobile robot platform. The experimental results demonstrate the effectiveness of the proposed joystick control command algorithm and the priority-based control input selection.