• 한국전기전자재료학회논문지
• /
• 제36권1호
• /
• pp.16-22
• /
• 2023

In a solar cell, degradation refers to the decrease in performance parameters caused by defects originated due to various causes. During the fabrication process of solar cells, degradation is generally related to the processes such as passivation or firing. There exist sources of many types of degradation; however, the exact cause of Light and elevated Temperature Induced Degradation (LeTID) is yet to be determined. It is reported that the degradation and the regeneration occur due to the recombination of hydrogen and an arbitrary substance. In this paper, we report the deposition of Al₂O₃ and SiN_X on silicon wafers used in the Passivated Emitter and Rear Contact (PERC) solar structure and its degradation pattern. A higher degradation rate was observed in the sample with single layer of Al₂O₃ only, which indicates that the degradation is affected by the presence or the absence of a passivation thin film. In order to alleviate the degradation, optimization of different steps should be carried out in consideration of degradation in the solar cell fabrication process.

• 대한금속재료학회지
• /
• 제46권5호
• /
• pp.276-282
• /
• 2008

Material degradation of Cr steels in boiler tubes was accompanied by the microstructural changes including carbide behavior and crack formation. The microstructural change and the mechanical behavior of hardness and creep properties in accelerated heat-treatments were studied in order to identify the material degradation of the X20 Cr steel. The degradation behavior was occurred in the hardness increasing followed by decreasing due to carbide dissolution and precipitation.

• 동력기계공학회지
• /
• 제16권1호
• /
• pp.58-64
• /
• 2012

Power plant boiler is one of the most important utilities providing steam to turbine in thermal power plant. It is composed of thousands of boiler tubes for high efficient heat transfer. Boiler tube material is used in such high temperature and pressure as $540^{\circ}C$, $170kg/mm^2$. The boiler tube material is needed to resist corrosion damage, creep damage and fatigue damage. 2.25%Cr-1Mo steel is used for conventional boiler tubes. In these days steam temperature and pressure of the power plant became higher for high plant efficiency. So, the material property of boiler tube must be upgraded to meet the plant property. Several boiler tube material was developed to meet such condition. X20CrMoV12.1 steel is also developed in early 1980's and used for superheater and reheater tubes in supercritical boilers. The material has martensitic structure, which is difficult to evaluate the material degradation. Boiler tube material at severe condition was tested to evaluate long term and short term degradation and creep. Through long term and high temperature degradation test, lath structure was decreased and recrystallization has been proceeded by sub-crystal. And in this research the effect of temperature and stress on boiler tube characteristic,for example, deformation by creep was changed rapidly at relatively high temperature and stress because creep was affected easily by temperature and stress.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1987년도 정기총회 및 창립40주년기념 학술대회 학회본부
• /
• pp.207-209
• /
• 1987

This paper reports the effect of additive elements such as Bi, Sb on degradation and hole formation of the Te-Se thin films. Changes in light transmission were used to monitor the degradation rate of thin Te films in an accelerated temperature-humidity environment. In thin accelerated temperature-humidity environment, $(Te_{86}Se_{14})_{70}Bi_{30}$ thin film was stable and $(Te_{86}Se_{14})_{50}Sb_{50}$ thin film was unstable in comparison with the other films that used in this experiment. The hole formation was carried out in the Te-based thin films.

• 한국화재소방학회논문지
• /
• 제31권6호
• /
• pp.91-98
• /
• 2017

본 논문은 PVC 절연재료의 가속열화에 따른 트래킹 특성에 관한 연구이다. PVC 절연재료를 절연열화 시키기 위해 가속수명 시험방법 중 아레니우스 방정식을 이용한 가속열화실험을 진행하여 등가연수 0년, 10년, 20년, 30년, 40년 된 실험시료를 제작하였다. 그 후 KS C IEC 60112 기준에 의한 트래킹 실험을 진행하였다. 가속열화에 따른 PVC 트래킹 특성 측정 결과 염화암모늄 0.1%를 PVC 절연재료에 투하하였을 때, 트래킹은 발생하지 않았다. 하지만 트래킹 진전과정의 전류파형 및 전압파형을 등가수명 0년에서부터 40년까지 분석한 결과 절연성이 파괴되어 본 재질의 기능성을 갖지 못하는 BDB 구간까지 등가수명 0년을 기준으로 등가수명 10년의 경우 위험성 1.4배 증가, 20년의 경우 위험성 2배 증가, 30년의 경우 위험성 3.5배 증가, 40년의 경우 위험성 7배 증가하는 것으로 나타났다.

• Journal of Mechanical Science and Technology
• /
• 제18권8호
• /
• pp.1368-1374
• /
• 2004

The remaining life estimation for the aged components in power plants as well as chemical plants are very important because mechanical properties of the components are degraded with in-service exposure time in high temperatures. Since it is difficult to take specimens from the operating components to evaluate mechanical properties of components, nondestructive techniques are needed to evaluate the degradation. In this study, test materials with several different degradation levels were prepared by isothermal aging heat treatment at $630^{\circ}C$. The DC potential drop method and destructive methods such as tensile and fracture toughness were used in order to evaluate the degradation of 1Cr-1Mo-0.25V steels. In this result, we can see that tensile strength and fracture toughness can be calculated from resistivity and it is possible to evaluate material degradation using DC potential drop method, non-destructive method.

• Journal of Welding and Joining
• /
• 제16권6호
• /
• pp.86-96
• /
• 1998

This study proposes the analysis method of time series ultrasonic signal using the chaotic feature extraction for degradation extent evaluation. Features extracted from time series data using the chaotic time series signal analyze quantitatively degradation extent. For this purpose, analysis objective in this study is fractal dimension, lyapunov exponent, strange attractor on hyperspace. The lyapunov exponent is a measure of the rate at which nearby trajectories in phase space diverge. Chaotic trajectories have at least one positive lyapunov exponent. The fractal dimension appears as a metric space such as the phase space trajectory of a dynamical system. In experiment, fractal correlation) dimensions, lyapunov exponents, energy variation showed values of 2.217∼2.411, 0.097∼ 0.146, 1.601∼1.476 voltage according to degardation extent. The proposed chaotic feature extraction in this study can enhances precision ate of degradation extent evaluation from degradation extent results of the degraded materials (SA508 CL.3)

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 하계학술대회 논문집
• /
• pp.157-160
• /
• 2001

Three sets of ZnO ceramic devices (reference samples with Matsuoka\`s composition; added 7o MgO, A1$_2$O$_3$, SiO$_2$) have been prepared by the conventional mixed oxide route. These additives were determined by the factors of valences and ionic radiuses. DC accelerated degradation test was performed for analysis of degradation characteristics versus the various additives. The conditions of DC degradation test were 115${\pm}$2$^{\circ}C$ for 12h. Using XRD and SEM, the Phase and microstructure of samples were analyzed respectively. E-J analysis was used to determine ${\alpha}$. Frequency analysis was accomplished to understand the relationship between R$\sub$g/ and $R_{b}$ with the electric stress at the equivalent circuit.

• 한국전기전자재료학회논문지
• /
• 제18권10호
• /
• pp.902-908
• /
• 2005

Various stresses (such as electrical stress, mechanical stress, environmental and electrochemical stress, and defects of structure) result in insulation degradation of epoxy mold type insulators. Since the insulation degradation of BCT(Bushing Current Transformer) and bushing proceeds during fabrication process or operation time due to these causes, various methods to reduce the degradation in their insulation ability have been suggested. In this paper, we investigated surface temperature increment of these insulators due to PD(partial discharge). After the voltage applied into the insulator to generate the artificial PD, the surface temperature of the insulator was measured with non-contact thermometer using infrared rays. It was confirmed through the analysis based on PD experiments that the procession in the insulation degradation of the insulator could be estimated through the measurement of the surface temperature in the insulator.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2000년도 제2회 학술대회 논문집 일렉트렛트 및 응용기술전문연구회
• /
• pp.25-28
• /
• 2000

In this paper, the technology for accelerating degradation & life estimation on the traction motor was introduced with the stator form-winding sample coils of the 200 Class insulation system The accelerative degradation was performed in 10 cycles, which were composed of thermal stress, fast rising surge voltage, vibration, water immersion and overvoltage applying. After aging of 10 cycles, condition diagnosis test such as insulation resistance & polarization index, capacitance & dielectric loss and partial discharge properties were investigated in the temperature range of $20{\sim}160^{\circ}C$. Relationship between degradation conditions and diagnosis results were analyzed to find an dominative degradation factor at the end-life point