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1 wt% Y<sub>2</sub>O<sub>3</sub> 첨가계 AlN 세라믹스의 소결 조건에 따른 전기전도도
이원진,이성민,심광보,김형태,Lee, Won-Jin,Lee, Sung-Min,Shim, Kwang-Bo,Kim, Hyung-Tae 한국세라믹학회 2007 한국세라믹학회지 Vol.44 No.2
Electrical properties of AlN ceramics sintered with 1 wt% $Y_2O_3$ have been investigated. From the impedance spectroscopy, electrical conductivity of grain boundary was found to be much lower than that of grain. DC conductivity measurement showed the electrode polarization effects caused by blocking electrode. The heat-treatment at $1700^{\circ}C$ of the specimen sintered at $1850^{\circ}C$ transformed continuous pain boundary phases along triple boundary junctions into isolated particles in grain comers. The heat-treatment induced decreases both in grain and grain boundary conductivity, and in DC electrical conductivities. From the analysis on the transference number, ionic conductivity was shown to be more dominant than electron conductivity, which was due to ion compensation mechanism during oxygen incorporation into grain.
유비쿼터스 센서 네트워크에서 전송 신뢰성 개선을 위한 재전송 방법
이원진,김승천,Lee, Won-Jin,Kim, Seung-Cheon 한국인터넷방송통신학회 2008 한국인터넷방송통신학회 논문지 Vol.8 No.3
유비쿼터스 서비스가 운용되기 위해서는 유비쿼터스 네트워크가 우선적으로 구축되어야 하며, 이 중에서 유비쿼터스 센서 네트워크는 매우 큰 부분을 차지하고 있다. 본 논문에서는 유비쿼터스 센서 네트워크가 독자적으로 운용되는 것은 물론, 유비쿼터스 서비스의 인프라로써 동작하기 위한 성능을 가지는 전송기법을 제안한다. 제안하는 방법은 데이터 전송의 신뢰성을 확보하여 성능을 향상시킨다. 특히 데이터 전송상의 오류를 부가적인 데이터 생성과 통신과정 없이 검출함으로써 통신비용을 줄이고, 네트워크의 트래픽을 감소시켜 준다. Most of the current research works on high-technology is being carried on to provide ubiquitous services to people. To make that possible, ubiquitous computing networks should be deployed in the first place, where ubiquitous sensor network (USN) will take a very big role. This paper is devoted to introduce a new transmission technique to make USN more independent and reliable as an infra-structure for ubiquitous services. The proposed scheme can elevate the network performance by ensuring the reliability of data transmission. Especially, the proposed scheme can reduce network traffic and communication cost by detecting data error without additional data and communication. In addition, it has an advantage of using the legacy routing protocols.
골결손부에서 흡수성 차폐막 단독 또는 이종골을 동반하여 시행한 조직유도재생술
이원진,김원기,안용범,장문택,김형섭,Lee, Won-Jin,Kim, Won-Gi,Ahn, Yong-Bum,Chang, Moon-Taek,Kim, Hyung-Seop 대한치주과학회 2008 Journal of Periodontal & Implant Science Vol.38 No.4
Purpose: In advanced case of periodontitis, surgical treatment without bone contouring may result in residual pockets inaccessible to proper cleaning during post-treatment maintenance. This problem can be avoided or reduced by applying guided tissue regeneration. Materials and Methods: All of 3 patients had deep periodontal pocket depth and bleeding on probing, and radiograph revealed osseous defect, so we planned guided tissue regeneration using resorbable membrane with or without xenograft. Result: 6 months later, periodontal pocket depth and bleeding on probing was improved and gingiva was stable. Conclusion: Guided tissue regeneration using resorbable membrane with or without xenograft in osseous defect is predictable.
지하수위 예측을 위한 경사하강법과 화음탐색법의 결합을 이용한 다층퍼셉트론 성능향상
이원진,이의훈,Lee, Won Jin,Lee, Eui Hoon 한국수자원학회 2022 한국수자원학회논문집 Vol.55 No.11
Groundwater, one of the resources for supplying water, fluctuates in water level due to various natural factors. Recently, research has been conducted to predict fluctuations in groundwater levels using Artificial Neural Network (ANN). Previously, among operators in ANN, Gradient Descent (GD)-based Optimizers were used as Optimizer that affect learning. GD-based Optimizers have disadvantages of initial correlation dependence and absence of solution comparison and storage structure. This study developed Gradient Descent combined with Harmony Search (GDHS), a new Optimizer that combined GD and Harmony Search (HS) to improve the shortcomings of GD-based Optimizers. To evaluate the performance of GDHS, groundwater level at Icheon Yullhyeon observation station were learned and predicted using Multi Layer Perceptron (MLP). Mean Squared Error (MSE) and Mean Absolute Error (MAE) were used to compare the performance of MLP using GD and GDHS. Comparing the learning results, GDHS had lower maximum, minimum, average and Standard Deviation (SD) of MSE than GD. Comparing the prediction results, GDHS was evaluated to have a lower error in all of the evaluation index than GD.
연 폭로 근로자들의 지질과산화 및 항산화상태에 관한 연구
이원진,황천현,김청식,장성훈,김양호,김해준,Lee, Won-Jin,Hwang, Cheon-Hyun,Kim, Cheong-Sik,Chang, Soung-Hoon,Kim, Yang-Ho,Kim, Hae-Joon 대한예방의학회 1998 Journal of Preventive Medicine and Public Health Vol.31 No.3
This study was started to find out if plasma malondialdehyde(MDA), $\alpha-tocopherol$ and erythrocyte superoxide dismutase(SOD) activity could be markers of biological activity resulting from exposed to lead in workers. Blood samples were randomly obtained from lead-exposed workers(n=29), $CO_2$, welders(n=60) and office workers(n=60). We used whole blood to analyse blood lead with atomic absorption spectrophotometer. Superoxide dismutase activity in erythrocyte was measured with spetrophotometer. MDA and $\alpha-tocopherol$ in plasma were measured with high performance liquid chromatography. Lead-exposed workers was significantly high in blood lead concentration$(29.37{\mu}g/d\ell)$ compared with welders$(6.42{\mu}g/d\ell)$ and office workers$(5.01{\mu}g/d\ell)$. The level of plasma MDA was significantly higher in the lead-exposed workers($1.87{\mu}mol/g$ cholesterol) than the welders($1.41{\mu}mol/g$ cholesterol) and office workers($1.41{\mu}mol/g$ cholesterol). Erythrocyte SOD activity in lead-exposed workers(56.80 U/g Hb) was significantly increased than those of welders(37.63 U/g Hb) and office workers(20.47 U/g Hb). The plasma $\alpha-tocopherol$ level of lead-exposed workers($4.93{\mu}g/g$ cholesterol) was statistically different from welders($4.25{\mu}g/g$ cholesterol) and office workers$4.28{\mu}g/g$ cholesterol). Neither age nor smoking was related to SOD or MDA level. Blood lead was significantly correlated with erythrocyte SOD activity(r=0.405), plasma MDA(r=0.296) and $\alpha-tocopherol$ (r=0.207). Plasma MDA was also significantly correlated with SOD (r=0.217). In multiple regression analysis, the change of MDA and SOD activity level related to the blood lead concentration. These results suggested that the increase of plasma MDA and erythrocyte SOD activity in lead-exposed workers had a close relationship with the oxidative stress induced by lead.