• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권2호
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• pp.1443-1446
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• 2007

The luminance and operating voltage were measured during OLED operation for the purpose of analyzing the efficiency and change of internal resistance. The half lifetime of OLED was affected by degradation of OLED due to heat generated by ambient temperature and self heating. The operating voltage constantly increased due to the increase of internal resistance. The half lifetime of OLED driven by constant current source was found to be longer than that of the OELD driven by constant voltage and the reasons were clearly explained in this paper.

• International Journal of Internet, Broadcasting and Communication
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• 제16권3호
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• pp.228-235
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• 2024

Battery use is increasing worldwide to achieve carbon neutrality and improve energy efficiency, but batteries are a finite resource and their application is determined by capacity and specifications. Battery performance deteriorates as the number of uses increases. A certain level of battery performance degradation has become an issue in the field of reuse and recycling, and various studies are being conducted on reuse to solve power shortages. Waste batteries from electric vehicles are suitable for building ESS based on reusable batteries, and for stable use, technical skills are needed to accurately predict battery life and determine status information. Predicting battery life and determining status information are difficult due to non-linearity due to internal structure or chemical changes. In this paper, we manufactured a modular internal resistance measuring device and compared the measured values with Hioki equipment to minimize the error rate through a correction method. As a result of testing Hioki equipment and modular measuring instruments to ensure efficiency and safety based on reusable batteries, an accuracy of over 95% was confirmed.

• Structural Engineering and Mechanics
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• 제32권3호
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• pp.429-445
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• 2009

Thermal stability of quasi-isotropic composite and polymeric structures is considered one of the most important criteria in predicting life span of building structures. The outdoor applications of these structures have raised some legitimate concerns about their durability including moisture resistance and thermal stability. Exposure of such quasi-isotropic composite/polymeric structures to various and severe climatic conditions such as heat flux and frigid climate would change the material behavior and thermal viability and may lead to the degradation of material properties and building durability. This paper presents an analytical model for the generalized problem. This model accommodates the non-linearity and the non-homogeneity of the internal heat generated within the structure and the changes, modification to the material constants, and the structural size. The paper also investigates the effect of the incorporation of the temperature and/or material constant sensitive internal heat generation with four encountered climatic conditions on thermal stability of infinite cylindrical quasi-isotropic composite/polymeric structures. This can eventually result in the failure of such structures. Detailed critical analyses for four case studies which consider the population of the internal heat generation, cylindrical size, material constants, and four different climatic conditions are carried out. For each case of the proposed boundary conditions, the critical thermal stability parameter is determined. The results of this paper indicate that the thermal stability parameter is critically dependent on the cylinder size, material constants/selection, the convective heat transfer coefficient, subjected heat flux and other constants accrued from the structure environment.

• Nuclear Engineering and Technology
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• 제55권11호
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• pp.4252-4265
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• 2023

In the case of nuclear power plants near end of their design life, a reassessment of the performance of safetyrelated equipment may be necessary to determine whether to shut down or extend the operation of the power plant. Therefore, it is necessary to evaluate the level of performance decline due to degradation. Electrical cabinets, including MCC and switchgear, are representative safety-related equipment. Several studies have assessed the degradation and seismic performance of nuclear power plant equipment. Most of those researches are limited to individual components due to the size of safety-related equipment and test equipment. However, only a few studies assessed the degradation performance of electrical cabinets. The equipment of various nuclear power plants is anchored to concrete foundations, and crack in concrete foundations is one of the most representative of degradation that could be visually confirmed. However, it is difficult to find a study for analysis through testing the effect of cracks in concrete foundations on the response of electrical cabinet internal equipment fixed by anchors. In this study, using a simple cabinet model considering cast-in-place anchor in uncracked and cracked concretes, a tri-axial shaking table tests were performed and the seismic behavior were observed.

• Tuberculosis and Respiratory Diseases
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• 제54권4호
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• pp.449-458
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• 2003

연구배경 : Cyclosporin A(CsA)와 tacrolimus(FK506)은 현재 임상에서 널리 쓰이는 면역억제제이다. CsA와 FK506이 $I{\kappa}B/NF-{\kappa}B$ 경로에 미치는 영향에는 세포에 따라 다양한 효과가 알려져 있다. 그러나 CsA와 FK506이 기관지 상피세포에서 $I{\kappa}B/NF-{\kappa}B$ 경로에 미치는 효과에 관해서는 알려져 있지 않고, 각종 염증 세포에서의 차이에 관해서도 보고가 미미한 실정이다. 본 연구에서는 비염증세포인 기관지상피세포와, 폐의 염증에 중요한 역할을 하는 염증 세포(폐포대식세포, 단핵구, 림프구)에서 CsA와 FK506이 $I{\kappa}B{\alpha}$의 분해에 미치는 영향과 그 기전을 평가하였다. 방 법 : 비염증세포로는 BEAS-2B와 A549 세포주를 이용하였다. FK506 또는 CsA 전처치 후 TNF-${\alpha}$로 자극하고 anti-$I{\kappa}B{\alpha}$ 항체를 이용한 Western blot으로 $I{\kappa}B{\alpha}$의 분해 여부를 관찰하였다. 염증세포로는 폐포대식세포, 말초혈액 단핵구 및 림프구를 이용하였고, 역시 FK506 또는 CsA 전처치 후 TNF-${\alpha}$, IL-$1{\beta}$, LPS로 자극하고 anti-$I{\kappa}B{\alpha}$ 항체를 이용한 Western blot으로 $I{\kappa}B{\alpha}$의 분해 여부를 관찰하였다. IKK의 활성도는 GST-$I{\kappa}B{\alpha}$를 기질로 이용한 in vitro immune complex kinase assay로 평가하였다. 결 과 : 사용된 모든 세포에서 CsA와 FK506은 $I{\kappa}B{\alpha}$의 발현에 영향을 미치지 않았다. 기관지 상피세포에서 TNF-${\alpha}$ 자극에 의한 $I{\kappa}B{\alpha}$의 분해는 CsA의 전처치로 억제되었으나, FK506의 전처치로는 억제되지 않았다. 단핵구, 림프구 및 폐포대식세포에서 외부자극에 의한 $I{\kappa}B{\alpha}$의 분해는 CsA 또는 FK506의 전처치로 억제되었으나 IKK활성은 억제되지 않았다. 결 론 : CsA와 FK506은 각각 기관지 상피세포와 단핵구, 림프구, 폐포대식세포에서 외부 자극에 의한 $I{\kappa}B{\alpha}$의 분해를 억제하는데, 이는 IKK 활성화의 억제가 아닌 다른 경로를 통하는 것으로 생각된다.

• 한국재료학회지
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• 제17권5호
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• pp.268-272
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• 2007

Inconel 617 is a candidate tube material for high temperature gas-cooled reactors(HTGR). The microstructure and mechanical properties of Inconel 617 were studied after exposure at high temperature($1050^{\circ}C$). The dominant oxide layer was Cr-oxide. The internal oxide and Cr-depleted region were observed below the Cr-oxide layer. The depth of Cr-depleted zone and internal oxide increased with exposure time. The major phases of carbides are $M_{23}C_6\;and\;M_6C$. The composition of $M_{23}C_6\;and\;M_6C$ were determined to be Cr-rich and Mo-rich, respectively. $M_6C$ carbide is more stable than $M_{23}C_6$ at high temperature. From the results of high temperature compression test, there were no significant changes in hardness and yield strength upon increasing exposure time.

• 한국건축시공학회지
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• 제16권6호
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• pp.595-601
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• 2016

현재 건축구조물에 사용되는 단열재의 단열성능은 초기성능을 기준으로 설계 시에만 반영하고 있으며, 장기 내구성 저하에 따른 단열성능 감소는 반영되고 있지 않다. 본 연구에서는 가속내구성 시험을 통해 단열재의 내구성 저하에 따른 단열성능 저하를 검토하였다. 연구결과, 발포폴리스티렌 단열재 비드법의 경우 표준환경 조건 및 실험실 가속 시험 조건에서는 경시변화에 따른 성능저하가 나타나지 않았으나, 동결 융해 시험 조건에는 성능이 저하하는 것으로 나타났다. 반면, 압출법의 경우 동결 융해 시험 조건에서는 단열성능 저하가 작았지만, 경시변화 초기에 내부 가스의 방출로 급격한 성능저하를 나타내었다. 또한, 경질 폴리우레탄 폼 단열재의 경우 다른 단열재에 비해 초기 단열성능이 매우 뛰어났으나, 실험실 가속 시험조건 및 동결 융해 시험 조건에서는 성능이 다소 저하하는 것으로 나타났다.

• 한국재료학회지
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• 제12권1호
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• pp.75-81
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• 2002

The ferroelectric properties of Pb(Zr,Ti)O$_3$[PZT] films degrade when the films with Pt top electrodes are annealed in hydrogen containing environment. This is due to the reduction activity of atomic hydrogen that is generated by the catalytic activity of the Pt top electrode. At the initial stage of hydrogen annealing, oxygen vacancies are formed by the reduction activity of hydrogen mainly at the vicinity of top Pt/PZT interface, resulting in a shift of P-E (polarization-electric field) hysteresis curve toward the negative electric field direction. As the hydrogen annealing time increases, oxygen vacancies are formed inside the PZT film by the inward diffusion of hydrogen ions, as a result, the polarization degrades significantly and the degree of P-E curve shift decreases gradually. The direction and the magnitude of the remnant polarization in the PZT film affect the motion of hydrogen ions which determines the degradation of polarization characteristics and the shift in the P-E hysteresis curve of the PZT capacitor during hydrogen annealing. When the remnant polarization is formed in the PZT film by applying a pre-poling voltage prior to hydrogen annealing, the direction of the P-E curve shift induced by hydrogen annealing is opposite to the polarity of the pre-poling voltage. The hydrogen-induced degradation behavior of the PZT capacitor is also affected by the internal field that has been generated in the PZT film by the charges located at the top interface prior to hydrogen annealing.

• Journal of Microbiology and Biotechnology
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• 제27권12호
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• pp.2119-2128
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• 2017

Citrinin (CIT) is a toxic secondary metabolite produced by fungi belonging to the Penicillium, Aspergillus, and Monascus spp. This toxin has been detected in many agricultural products. In this study, a strain Y3 with the ability to eliminate CIT was screened and identified as Cryptococcus podzolicus, based on the sequence analysis of the internal transcribed spacer region. Neither uptake of CIT by cells nor adsorption by cell wall was involved in CIT elimination by Cryptococcus podzolicus Y3. The extracellular metabolites of Cryptococcus podzolicus Y3 stimulated by CIT or not showed no degradation for CIT. It indicated that CIT elimination was attributed to the degradation of intracellular enzyme(s). The degradation of CIT by C. podzolicus Y3 was dependent on the type of media, yeast concentration, temperature, pH, and initial concentration of CIT. Most of the CIT was degraded by C. podzolicus Y3 in NYDB medium at 42 h but not in PDB medium. The degradation rate of CIT was the highest (94%) when the concentration of C. podzolicus Y3 was $1{\times}10^8cells/ml$. The quantity of CIT degradation was highest at $28^{\circ}C$, and there was no degradation observed at 3$5^{\circ}C$. The study also showed that acidic condition (pH 4.0) was the most favorable for CIT degradation by C. podzolicus Y3. The degradation rate of CIT increased to 98% as the concentration of CIT was increased to $20{\mu}g/ml$. The toxicity of CIT degradation product(s) toward HEK293 was much lower than that of CIT.

• 대한한방내과학회지
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• 제22권4호
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• pp.639-645
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• 2001

Angiogenesis is a fundamental process in reproduction and wound healing. Under these condition, neovascularization is tightly regulated. Unregulated angiogenesis may lead to several angiogenic diseases, and is thought to be indispensible for solid tumor growth and metastsis. The construction of new vascular network is a multistep cascade involving basement membrane degradation, endothelial cell proliferation, endothelial cell migration, and tube formation. Newly reported anti-angiogenic agents in oriental medical field have targeted both specific and multistep stages in the angiogenic process. From recent approach in oriental medical field with several herb medicines including activating blood flow and removing blood stasis medicine(活血化瘀藥), it may be possible in the future to develope specific anti-angiogenic agents that offer a less toxic potential therapy for cancer and angiogenic disease.