• 조명전기설비학회논문지
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• 제18권2호
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• pp.90-99
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• 2004

고도 정보화 사회의 발달과 함께 정보통신 설비는 빠른 전송속도를 필요로 하며, 지능형 산업설비와 행정, 금융, 교통시스템과 같은 사회시스템은 집적회로와 초소형 반도체로 구성되므로 원격감시, 조작에 의해 점차적으로 자동화 되어가고 있다. 이와 같은 현대의 초소형 전자회로는 뇌 서지에 의해 흔히 손상을 입을 수 있으며, 뇌 과전압으로부터 전자회로의 보호에 관심이 집중되고 있다. 본 논문은 일반주택에서 뇌 서지로부터 초소형 컴퓨터와 같은 전자기기의 효과적인 보호방법을 제안하기 위하여 전원계통의 접지방식에 따른 서지보호기의 보호효과를 실험적으로 분석하였다. 또한 서지보호기의 효과적인 설치방법을 조사하고 제안하였다. 기존의 설비에 추가적으로 서지보호기를 설치하는 것은 서지보호기까지의 긴 접속선으로 인한 인덕턴스 때문에 높은 잔류전압이 나타난다. 서지보호기의 설치에 있어 두 접속선을 꼬는 방법이 급격하게 상승하는 과도과전압에 매우 효과적이다.

• 소성∙가공
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• 제27권4호
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• pp.250-256
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• 2018

Oxygen-free copper (OFC) was prepared as a 90 mm cube and then processed with Multi-Axial Diagonal Forging - Initialization of Prior manufacturing History (MADF). The MADF process has been newly developed as a severe plastic deformation method. The MADF process consists of upset forging with a thickness reduction of 30% and diagonal forging with a diagonal angle of $135^{\circ}$. 1 cycle process consists of a 12 passes forging process. In order to analyze the characteristic changes according to the number of iterations, 1, 2, and 3 cycles of the MADF process were performed. The OFC specimens were MADF processed without surface cracks up to 3 cycles. The microstructure, hardness and tensile test of processed materials were analyzed to study the change of material properties according to the amount of MADF process. The results showed that the MADF process effectively refined the microstructure and increased the strength of OFC. In the case of specimens processed for more than 2 cycles, the grains of all measurement regions were refined to be less than $7{\mu}m$ of grain size. The 1 cycle MADF processed OFC showed the highest mechanical properties with the hardness of 132 HV and tensile strength of 395 MPa. Hardness and strength seemed to be saturated when processed over 2 cycles.

• 한국약용작물학회지
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• 제25권1호
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• pp.45-51
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• 2017

Background: This study was performed to evaluate the protective effect of Saururus chinensis ethanol extract (SCE) against styrene toxicity in mouse spermatocyte cells [GC-2spd (ts) cell line]. Methods and Results: Cytotoxicity in mouse spermatocyte cells was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Generation of reactive oxygen species (ROS) was determined using 2',7'-dichlorodihydrofluorescein diacetate (DCF-DA) assay. Semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) and western blotting were performed to quantify the mRNA and protein expression levels, resepectiviely, of stress or apoptosis-related genes including p21, p53, heat shock protein 70 (Hsp70), heat shock protein 90 (Hsp90), Bax, Bcl-2, and caspase-3. The results of the MTT assay showed that $50 {\mu}g/m{\ell}$ SCE did not affect cell viability. ROS generation in mouse spermatocyte cells increased by treatment with $100{\mu}M$ styrene, and decreased by co-treatment with SCE. SCE repressed the mRNA expression of stress-related genes, which increased by styrene treatment. In addition, SCE inhibited the apoptosis of mouse spermatocyte cells by ameliorating mRNA and protein levels of apoptotic genes that were altered by styrene treatment. Conclusions: These results suggest that SCE may alleviate styrene toxicity in mouse spermatocyte cells by reducing ROS stress and regulating genes related to styrene toxicity.

• 정보처리학회논문지C
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• 제11C권5호
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• pp.671-676
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• 2004

다양한 데이터 속도와 버스트 타입과 같은 다양한 형태의 신호가 혼재하는 멀티미디어 서비스를 전송하기 위한 초고속 광 가입자망을 구축하기 위하여 수정한 PN 코드를 사용한 주파수영역에서 확산하는 광 CDMA 시스템을 제안한다. 광 멀티미디어 가입자망에서 동시 가입자의 수를 늘리고, 간섭잡음을 경감시키기 위하여 수정한 PN 코드를 사용한 FBG형 광 CDMA에 대하여 광원의 SPD(spectral power distortion)에 의한 특성변화를 수치적으로 분석한다. 다양한 데이터의 속도의 신호가 혼재한 멀티미디어 시스템에서 데이터의 속도에 관계없이 동시 가입자의 수가 같을 경우 BER 특성이 동일하다는 것을 알 수 있다. 그리고 제안한 광주파수영역 CDMA를 이용한 초고속 멀티미디어 네트워크에서의 BER 특성이 종래방식보다 훨씬 향상되는 것을 알 수 있다.

• Molecules and Cells
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• 제40권12호
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• pp.935-944
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• 2017

More than 50% of sepsis cases are associated with pneumonia. Sepsis is caused by infiltration of bacteria into the blood via inflammation, which is triggered by the release of cell wall components following lysis. However, the regulatory mechanism of lysis during infection is not well defined. Mice were infected with Streptococcus pneumoniae D39 wild-type (WT) and lipase mutant (${\Delta}lipA$) intranasally (pneumonia model) or intraperitoneally (sepsis model), and survival rate and pneumococcal colonization were determined. LipA and autolysin (LytA) levels were determined by qPCR and western blotting. S. pneumoniae Spd_1447 in the D39 (type 2) strain was identified as a lipase (LipA). In the sepsis model, but not in the pneumonia model, mice infected with the ${\Delta}lipA$ displayed higher mortality rates than did the D39 WT-infected mice. Treatment of pneumococci with serum induced LipA expression at both the mRNA and protein levels. In the presence of serum, the ${\Delta}lipA$ displayed faster lysis rates and higher LytA expression than the WT, both in vitro and in vivo. These results indicate that a pneumococcal lipase (LipA) represses autolysis via inhibition of LytA in a sepsis model.

• 한국정보통신학회논문지
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• 제8권1호
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• pp.34-40
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• 2004

본 논문에서는 X-band용 저위상잡음을 갖는 위상고정 유전체 공진 발진기를 설계 및 제작하였다. 위상고정 유전체 공진 발진기의 루프대역 내의 위상잡음을 개선하기 위해서 샘플링위상비교기(Sampling Phase Detector)를 사용하여 전압제어 유전체 공진 발진기를 고안정의 기준주파수에 위상 고정시켰으며 루프대역 밖의 위상잡음을 개선하기 위해서 고임피던스 변환기를 이용한 낮은 위상잡음의 전압제어 발진기를 설계하였다. 제작된 위상고정 유전체 공진 발진기는 51.67㏈c의 고조파 억압특성을 가지고 있으며 공급전력은 1.95W 이하를 필요로 한다. 위상잡음은 상온에서 -107.17㏈c/Hz $\circleda$10KHz와 -113.0㏈c/Hz $\circleda$100KHz의 우수한 특성을 나타내었으며 출력전력은 $-20 ∼ +70^{\circ}C$의 온도 범위에서 13.0㏈m${\pm}$0.33㏈의 안정된 특성을 나타내었다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.533-536
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• 2007

The LiDAR data structure has the potential for modeling in three dimensions because the LiDAR data can represent voxels with z value under certain defined conditions. Therefore, it is possible to classify the physical damaged degree of vegetation by forest fire as using the LiDAR data because the physical loss of canopy height and width by forest fire can be relative to an amount of points reached to the ground through the canopy of damaged forest. On the other hand, biological damage of vegetation by forest fire can be explained using the NDVI (Normalized Difference Vegetation Index) which show vegetation vitality. In this study, we graded the damaged degree of vegetation by forest fire in Yangyang-Gun of South Korea using the LiDAR data for physical grading and digital aerial photograph including Red, Green, Blue and Near Infra-Red bands for biological grading. The LiDAR data was classified into 2 classes, of which one was Serious Physical Damaged (SPD) and the other was Light Physical Damaged (LPD) area. The NDVI was also classified into 2 classes which are Serious Biological Damaged (SBD) and Light Biological Damaged (LBD) area respectively. With each 2 classes ofthe LiDAR data and NDVI, the damaged area by forest fire was graded into 4 degrees like damaged class 1,2,3 and 4 grade. As a result of this study, 1 graded area was the broadest and next was the 3 grade. With this result, we could know that the burned area by forest fire in Yangyang-Gun was damaged rather biologically because the NDVI in 1 and 3 grade appeared low value whereas the LiDAR data in 1 and 3 grade included light physical damage like the LPD.

• 한국전자파학회논문지
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• 제13권6호
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• pp.552-559
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• 2002

본 논문에서 는 Ka-band 위 성 중계 기용 국부발진기 의 EM(Engineering Model)을 설계 및 제작하였다. 루프 대역 밖의 위상잡음을 개선하기 위해서 고임피던스 변환기를 이용한 낮은 위상잡음의 전압제어 발진기를 설계하고 샘플링위상비교기(Sampling Phase Detector)를 사용하여 전압제어 발진기를 고안정의 OCXO(Oven Controlled Crystal Oscillator)에 위상 고정시킴으로써 루프 대역 내의 위상잡음을 개선하였다. 개발된 국부발진기는 43.83 dBc 이상의 고조파 억압특성을 가지고 있으며 공급전력은 15 V, 160 mA를 필요로 한다. 위상잡음은 -102.5 dBc/Hz @10 KHz와 -104.0 dBc/Hz @100 KHz의 특성을 나타내며 출력전력은 -20 - +7$0^{\circ}C$의 온도 범위에서 13.50 dBm$\pm$0.33 dB의 특성을 얻었다.

• 반도체디스플레이기술학회지
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• 제19권3호
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• pp.23-29
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• 2020

Electrochromic (EC) device is an element whose transmittance is changed by electrical energy. Coloring and decoloring states can be easily controlled and thus used in buildings and automobiles for energy saving. There exist several types of EC devices; EC using electrolytes, polymer dispersed liquid crystal (PDLC), and suspended particle device (SPD) using polarized molecules. However, these devices involve solutions such as electrolytes and liquid crystals, limiting their applications in high temperature environments. In this study, we have studied all-solid-state EC device based on Tin(IV) oxide (SnO₂). A coloring phase is achieved when electrons are accumulated in the ultraviolet (UV)-treated SnO₂ layer, whereas a decoloring mode is obtained when electrons are empty there. The UV treatment of SnO₂ layer brings in a number of localized states in the bandgap, which traps electrons near the conduction band. The SnO₂-based EC device shows a transmittance of 70.7% in the decoloring mode and 41% in the coloring mode at a voltage of 2.5 V. We have achieved a transmittance change as large as 29.7% at the wavelength of 550 nm. It also exhibits fast and stable driving characteristics, which have been demonstrated by the cyclic experiments of coloration and decoloration. It has also showed the memory effects induced by the insulating layer of titanium dioxide (TiO₂) and silicone (Si).

• Journal of applied mathematics & informatics
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• 제11권1_2호
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• pp.305-316
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• 2003

Recently, an iterative algorithm for finding the interior eigenvalues of a definite matrix by CG-type method has been proposed. This method compares to the inverse power method. The given matrices A, and B are assumed to be large and sparse, and SPD( Symmetric Positive Definite) The CG scheme for the optimization of the Rayleigh quotient has been proven a very attractive and promising technique for large sparse eigenproblems for smallest eigenvalue. Also, it is very amenable to parallel computations, like the CG method for the linear systems. A proper choice of the preconditioner significantly improves the convergence of the CG scheme. But for parallel computations we need to find an efficient parallel preconditioner. Our candidates we ILU(0) in the wave-front order, ILU(0) in the multi-coloring order, Point-SSOR(Symmetric Successive Overrelaxation), and Multi-Color Block SSOR preconditioner. Wavefront order is a simple way to increase parallelism in the natural order, and Multi-coloring realizes a parallelism of order(N), where N is the order of the matrix. Another choice is the Multi-Color Block SSOR(Symmetric Successive OverRelaxation) preconditioning. Block SSOR is a symmetric preconditioner which is expected to minimize the interprocessor communication due to the blocking. We implemented the results on the CRAY-T3E with 128 nodes. The MPI (Message Passing Interface) library was adopted for the interprocessor communications. The test problem was drawn from the discretizations of partial differential equations by finite difference methods. The results show that for small number of processors Multi-Color ILU(0) has the best performance, while for large number of processors Multi-Color Block SSOR performs the best.