• Tuberculosis and Respiratory Diseases
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• 제45권1호
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• pp.99-106
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• 1998

연구배경: 기관지 천식은 다양한 원인에 대한 기도 협착과 과민 반응을 특정으로 하는 기도 질환으로, 그 병인에 대한 연구를 임상적으로 시행하는 데에는 한계가 있어, 동물 천식 모형을 이용한 연구가 필요하다. 동물에서의 기도 저항의 측정은 주로 마취나 삽관 상태에서 침습적으로 측정되었으나, 최근 비침습적으로 의식이 있는 상태에서 일상호흡 중의 specific 기도 저항을 측정하는 방법들이 고안되었다. 이에 저자들은 기니픽에 allergen인 ovalbumin을 피하 주사하여 감작시킨 후, 의식이 있는 상태에서 ovalbumin과 methacholine을 각각 흡입시켜, 비침습적인 방법으로 specific 기도 저항을 측정함으로써 즉시형 기관지 수축 정도와 methacholine에 대한 기도 과민성의 변화를 연구하여 동물 천식 모형을 만들고자 하였다. 연구방법: 기니픽 30마리를 천식군 20마리, 대조군 10마리로 나누어, 천식군에서는 ovalbumin을 피하 주사하여 감작시킨 후, ovalbumin을 흡입(1% wt/vo1)으로 노출시켰고, 대조군은 생리 식염수를 동일한 방법으로 감작, 노출시켰다. specific 기도 저항(airway resistance $\times$ thoracic gas volume)은 의식이 있는 상태에서 비침습적으로 동물 body plethysmography를 사용하여, Pennock법으로 allergen 노출 3분전부터, 노출후 27분까지 3분 간격으로 30분간 측정하였다. Methacholine은 지속적으로 2배씩 농도를 증가하여, 각 농도에 대하여 3분 간격으로 흡입시킨 후, 통일한 방법으로 specific 기도 저항을 측정하여 기도 저항이 200% 이상 증가될 때의 methacholine 농도 ($EC_{200}R_L$)를 구하였다. 결 과: 천식군 20마리 중 65%인 13마리에서 ovalbumin 흡입에 대한 specific 기도 저항이 3분부터 증가하여 6분에 231.5%로 최고를 보이고 실험 측정 종료까지인 30분까지 대조군에 비하여 유의하게 증가된 상태로 지속되어 (p<0.001), 천식 모형이 형성되었다. Methacholine에 대한 기관지 과민 반응은 $EC_{200}R_L$가 대조군에서 평균 $0.446{\pm}0.287mg/ml$, 기하평균 $-1.429{\pm}0.976$였고, 천식군에서 형성된 천식 모형에서의 평균은 $0.149{\pm}0.075mg/ml$, 기하평균 $-2.923{\pm}0.760$으로 천식 모형에 있어서 methacholine에 대한 기관지 과민 반응이 대조군에서보다 2 배 높았다(p<0.0013).

• ETRI Journal
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• 제26권1호
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• pp.7-13
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• 2004

To improve the characteristics of breakdown voltage and specific on-resistance, we propose a new structure for a LDMOSFET for a PDP scan driver IC based on silicon-on-insulator with a trench under the gate in the drift region. The trench reduces the electric field at the silicon surface under the gate edge in the drift region when the concentration of the drift region is high, and thereby increases the breakdown voltage and reduces the specific on-resistance. The breakdown voltage and the specific on-resistance of the fabricated device is 352 V and $18.8 m{\Omega}{\cdot}cm^2$ with a threshold voltage of 1.0 V. The breakdown voltage of the device in the on-state is over 200 V and the saturation current at $V_{gs}=5V$ and $V_{ds}$=20V is 16 mA with a gate width of $150{\mu}m$.

• Corrosion Science and Technology
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• 제6권1호
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• pp.1-6
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• 2007

Ferritic stainless steels for the SOFC interconnect applications are required to possess not only a good oxidation resistance, but also a high electrical conductivity of the oxide scale that forms during exposure at the SOFC operating environment. In order to understand the effects of alloying elements on the oxidation behavior of ferritic stainless steels and on the electrical properties of oxide scales, two kinds of commercial ferritic stainless steels, STS 430 and STS 444, were investigated by performing isothermal oxidations at $800^{\circ}C$ in a wet air containing 3% $H_{2}O$. The results showed that STS 444 was superior to STS 430 in both of the oxidation resistance and the area specific resistance. Although STS 444 contained a less amount of Mn for the $(Mn,Cr)_{3}O_{4}$ spinel formation than STS 430, the minor alloying elements of Al and Mo in STS 444, which were accumulated in the base metal region adjacent the scale, were suggested to reduce the scale growth rate and to enhance the scale adherence to the base metal.

• BMB Reports
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• 제42권8호
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• pp.475-481
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• 2009

Emerging data demonstrate pivotal roles for brain insulin resistance and insulin deficiency as mediators of cognitive impairment and neurodegeneration, particularly Alzheimer's disease (AD). Insulin and insulin-like growth factors (IGFs) regulate neuronal survival, energy metabolism, and plasticity, which are required for learning and memory. Hence, endogenous brain-specific impairments in insulin and IGF signaling account for the majority of AD-associated abnormalities. However, a second major mechanism of cognitive impairment has been linked to obesity and Type 2 diabetes (T2DM). Human and experimental animal studies revealed that neurodegeneration associated with peripheral insulin resistance is likely effectuated via a liver-brain axis whereby toxic lipids, including ceramides, cross the blood brain barrier and cause brain insulin resistance, oxidative stress, neuro-inflammation, and cell death. In essence, there are dual mechanisms of brain insulin resistance leading to AD-type neurodegeneration: one mediated by endogenous, CNS factors; and the other, peripheral insulin resistance with excess cytotoxic ceramide production.

• Asian Pacific Journal of Cancer Prevention
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• 제16권3호
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• pp.1105-1109
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• 2015

Chemoresistance is the most common cause of chemotherapy failure during breast cancer (BCA) treatment. It is generally known that the mechanisms of chemoresistance in tumors involve multiple genes and multiple signaling pathways,; if appropriate drugs are used to regulate the mechanisms at the gene level, it should be possible to effectively reverse chemoresistance in BCA cells. It has been confirmed that chemoresistance in BCA cells could be reversed by ginsenoside Rh2 (G-Rh2). Preliminary studies of our group identified some drugresistance specific miRNA. Accordingly, we proposed that G-Rh2 could mediate drug-resistance specific miRNA and corresponding target genes through the gene regulatory network; this could cut off the drug-resistance process in tumors and enhance treatment effects. G-Rh2 and breast cancer cells were used in our study. Through pharmaceutical interventions, we could explore how G-Rh2 could inhibit chemotherapy resistance in BCA, and analyze its impact on related miRNA and target genes. Finally, we will reveal the anti-resistance molecular mechanisms of G-Rh2 from a different angle in miRNA-mediated chemoresistance signals among cells.

• Membrane and Water Treatment
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• 제9권4호
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• pp.245-253
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• 2018

The aim of this study is to investigate the membrane fouling in a thermophilic membrane bioreactor (TMBR) operated different sludge retention times (SRTs). For this purpose, TMBR was operated at four different SRTs (10, 30, 60 and 100 days). Specific cake resistance (${\alpha}$), cake resistance, gel resistance, total resistance, MFI (modified fouling index) and FDR (flux decrease ratio) were calculated for all SRTs. It was observed that flux in the membrane increases with rising SRT although the sludge concentrations in the TMBR increased. The steady state flux was found to be 31.78; 34.70; 39.60 and 43.70 LMH ($Liter/m^2/h$) for the SRTs of 10, 30, 60 and 100 days respectively. The concentrations of extracellular polymeric substance (EPS) and soluble microbial product (SMP) decreased with increasing SRT. The membrane fouling rate was higher at shorter SRT and the highest fouling rate appeared at an SRT of 10 d. Both the sludge cake layer and gel layer had contribution to the fouling resistance, but the gel layer resistance value was dominant in all SRTs.

• 수산해양기술연구
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• 제25권2호
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• pp.87-104
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• 1989

Recently, with the tendency of more lightening, high-strength and high-speed in the marine industries such as marine structures, ships and chemical plants, the use of the aluminium Alloy is rapidly enlarge and there occurs much interest in the study of corrosion fatigue crack characteristics. In this paper, the initiation of surface crack and the propagation characteristics on the base metal and weld zone of 5086-H116 Aluminium Alloy Plate which is one of the Al-Mg serious alloy(A5000serious) used most when building the special vessels, were investigated by the plane bending corrosion fatigue under the environments of marine, air and applying cathodic protection. The effects of various specific resistances on the initiation, propagation behavior of corrosion fatigue crack and corrosion fatigue life in the base metal and heat affected zone were examined and its corrosion sensitivity was quantitatively obtained. The effects of corrosion on the crack depth in relation to the uniform surface crack length were also investigated. Also, the structural, mechanical and electro-chemical characteristics of the metal at the weld zone were inspected to verify the reasons of crack propagation behavior in the corrosion fatigue fracture. In addition, the effect of cathodic protection in the fracture surface of weld zone was examined fractographically by Scanning Electron Microscope(S.E.M.). The main results obtained are as follows; (1) The initial corrosion fatigue crack sensitibity under specific resistance of 25Ω.cm% show 2.22 in the base metal and 19.6 in the HEZ, and the sensitivity decreases as specific resistance increases (2) By removing reinforcement of weldment, the initiation and propagation of corrosion crack in the HAZ are delayed, and corrosion fatigue life increases. (3) As specific resistance decreases, the sensitivity difference of corrosion fatigue life in the base metal and HAZ is more susceptible than that of intial corrosion fatigue crack. (4) Experimental constant, m(Paris' rule) in the marine environment is in the range of about 3.69 to 4.26, and as specific resistance increases, thje magnitude of experimental constant, also increases and the effect by corrosion decreases. (5) Comparing surface crack length with crack depth, the crack depth toward the thickness of specimen in air is more deeply propagated than that in corrosion environment. (6) The propagation particulars of corrosion fatigue crack for HAZ under initial stress intensity factor range of $\Delta$k sub(li) =27.2kgf.mm super(-3/2) and stress ratio of R=0 shows the retardative phenomenon of crack propagation by the plastic deformation at crack tip. (7) Number of stress cycles to corrosion fatigue crack initiation of the base metal and the welding heat affected zone are delayed by the cathodic protection under the natural sea water. The cathodic protection effect for corrosion fatigue crack initiation is eminent when the protection potential is -1100 mV(SCE). (8) When the protection potential E=-1100 mV(SCE), the corrosion fatigue crack propagation of welding heat affected zone is more rapid than that of the case without protection, because of the microfissure caused by welding heat cycle.

• 전기전자학회논문지
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• 제26권4호
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• pp.728-735
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• 2022

이번 연구에서 우리는 낮은 온 저항을 위해 p-well 영역 아래에 도입된 전류 확산층을 변화시켜 고전압 4H-SiC 전력 Diffused MOSFET(DMOSFET)에 대해 연구했다. Current Spreading Layer(CSL)의 두께(T_CSL)를 0~0.9 um, CSL의 도핑 농도(N_CSL)를 1~5×10¹⁶ cm^-3으로 변화시키면서 소자의 전기적 특성을 분석하였다. TCAD 2D-simulation을 통해 최적화되었으며 CSL이 온 저항을 낮추는 것뿐만 아니라 항복전압도 낮춤으로써 CSL의 최적화의 중요성을 확인하였다. 최적화된 구조는 59.61 mΩ·cm²의 온저항, 5 kV의 항복전압, 0.43 GW/cm²의 Baliga's Figure of Merit(BFOM)을 보여주었다.

• Journal of Welding and Joining
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• 제31권2호
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• pp.21-25
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• 2013

Aluminum alloys have been considered for substantial use in these industries. This ensues from their attractive strength to weight ratio, superb formability, apposite weldability and acceptable corrosion resistance. Depending on the specific application, corrosion behavior is a significant factor of a welded joint. In this study, recent researches in the view of corrosion resistance of friction stir welded aluminum alloys are briefly reviewed.

• 대한기계학회논문집B
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• 제37권2호
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• pp.119-124
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• 2013

본 연구에서는 전도성 잉크의 레이저 열경화 공정시 은 나노입자 잉크의 레이저 열경화 공정 온도를 수치해석하였다. 유리기판 위에 잉크젯 프린팅을 이용하여 인쇄한 은 나노 입자 잉크를 532 nm 파장의 CW 레이저를 각기 다른 세기로 60 초 동안 조사하여 가열하였다. 온도계산을 위해서, 열생성항에 들어가는 반사율을 구하였고, 레이저 조사 중 실시간 은 나노입자 잉크의 비저항을 측정하였다. 온도 계산은 2차원 열전도 방정식에 Wiedemann-Franz law 를 적용하였다. 그 결과, 레이저 조사로 인해 인쇄된 잉크의 온도가 상승할수록 비저항이 떨어지는 결과를 확인하였다.