• 전기학회논문지P
• /
• 제65권2호
• /
• pp.77-83
• /
• 2016

The electric quality of train is represented by voltage and current harmonics at PT(Ratio 25,000/15/[V]) which is located between pantograph and primary winding of train transformer. In this paper, voltage and current harmonics were measured on the test EMU(electric multiple unit)train with maximum speed of 180km/h in existing railway lines(chungbuk, Taeback, Honam). As a results of test, it is found that the electric quality of train depends on the mostly operation conditions which is accelerating mode and braking mode on each sections. Voltage THD is above all 3[%] and current harmonics is monitored from lowest Harmonic to highest Harmonic in case of accelerating mode. But, highest current harmonics is not monitored in case of breaking mode. The results in this paper can help to stabilize the power device and power converter of the test EMU train.

• Nuclear Engineering and Technology
• /
• 제51권3호
• /
• pp.877-883
• /
• 2019

Superconducting multi-spoke cavities are outstanding alternative choice for acceleration of heavy ions in medium velocity regimes. Based on the scheme of China ADS, several researches on the superconducting double-spoke cavities were done and two prototype cavities have been developed. In this paper, the RF design, the mechanical design and fabrication considerations of the bare cavity will be described in detail. After Buffered Chemical Polishing and High Pressure Rinsing, one of the prototype cavities was installed into the Vertical Test Stand for high gradient RF testing at 4.2 K. The measurement results of the quality factor as a function of the accelerating field and the maximum surface field will be presented. An accelerating gradient of more than 15 MV/m is achieved during the test, with maximum surface electric field of 58 MV/m, and maximum surface magnetic field of 117 mT.

• 대한산업공학회지
• /
• 제20권1호
• /
• pp.39-51
• /
• 1994

Almost all accelerated life tests assume that no basic failure mechanism changes within the test stresses. But accelerated life test, considering failure mechanism changes, is needed since failure mechanism changes when accelerating beyond the used stress. This paper studies the analysis when the failure mechanism changes within the test stresses. The piecewise linear regression, which the join point of two lines is estimated, is applied In particular, two accelerated life tests, with and without a change in failure mechanism are examined.

• 한국산학기술학회논문지
• /
• 제22권2호
• /
• pp.267-272
• /
• 2021

본 연구는 최근 증가하고 있는 건축물의 다양한 외벽 형상에 따라 적용이 가능한 비정형 건축물에의 적용을 위해 3D 프린팅 기법을 적용한 외장재의 제조를 위한 기초 연구로서 진행하였다. 3D 프린팅 외장재의 출력성과 적층성의 확보를 위하여 3D 프린팅 콘크리트를 몰드에 타설한 시험체와 급결제를 사용한 출력물 시험체의 단위중량과 강도특성을 분석하였다. 몰드에 타설한 콘크리트의 단위중량에 비하여 급결제를 사용한 3D 프린팅 콘크리트의 단위중량이 3.5%~5.0% 정도 감소하는 경향을 나타내었고, 압축강도는 몰드에 타설한 콘크리트의 압축강도에 비하여 3D 프린팅을 통한 출력물의 압축강도는 36%~46%정도 감소하는 경향을 나타냈다. 휨강도의 경우 몰드에 타설한 콘크리트의 압축강도에 비하여 3D 프린팅을 통한 출력물의 압축강도는 36%~46%정도 감소하는 경향을 나타냈다. 급결제를 사용한 3D 프린팅 콘크리트의 강도 특성에 관한 영향은 2.0~5.8%정도 감소하는 경향을 나타냈다. 따라서, 3D 프린팅 출력시 급결제의 사용에 따른 강도 특성에 영향은 출력에 의한 강도 특성의 감소 보다 적은 것으로 나타나 3D 프린팅 외장재 제조시 급결제의 사용이 가능한 것으로 판단된다.

• 한국산학기술학회논문지
• /
• 제16권5호
• /
• pp.2993-2999
• /
• 2015

강 제조 회사들은 연속주조금형의 표면을 보호하기 위해 Ni-B 또는 Ni-Co 합금 도금을 적용하고 있으며, 도금 층에 균열이 생기게 하는 황을 함유한 사카린 윤활제를 사용하고 있다. 균열 및 인장 응력을 유발하는 것은 Ni-S 화합물로 여겨진다. Ni-Mn-B 삼원합금은 Ni-S 화합물이 형성되기 이전에 Mn-S 화합물을 형성하여 균열을 억제하기 위해서 개발되었으나, Ni-Mn-B 합금 도금에 관한 국내나 해외 기준이 없다. 그리하여 새로이 개발된 Ni-Mn-B 도금을 평가하기 위한 신뢰성 평가기준을 개정하려한다. 가속수명시험을 개발하기 위해 FMEA(고장형태 영향분석)가 사용되어 도금의 주요 파괴 원인을 분석하였다. Ni-Mn-B 신뢰성 기준은 가속수명시험 방법을 포함하였고, 기본 성능 시험과 환경시험, 가속수명시험으로 분류되었으며, 80% 신뢰수준으로 B10수명 1 000시간을 보장하도록 고안되었다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2003년도 봄 학술발표회 논문집
• /
• pp.767-772
• /
• 2003

The clay which transported into a pond under the high water content condition have no effective stress which develop from the starting point of sedimentation and self-weight consolidation. Since sedimentation and self-weight consolidation dependent on self-weight of solids is made progress over a long time, to accelerating it have many advantages in the economic view In this paper, sand spreading method which is one of sedimentation and self-weight consolidation acceleration method is studied through a series of experiments considering the mixing ratio of sand and clay. The test results show that the mixing ratio of clay and sand of 1:0.2 is the biggest rate of consolidation and the pouring at the end point of sedimentation considerably effects on consolidation rate.

• 품질경영학회지
• /
• 제43권3호
• /
• pp.409-420
• /
• 2015

Purpose: This study is to estimate the life of elevator wire rope by using the accelerated degradation test with two accelerating variables of applied load and corrosion. Methods: Linear regression method is used to find the pseudo life of elevator wire rope at each combination of accelerating variables and the median life of elevator wire rope at use condition is estimated under the assumption that the life of elevator wire rope follows lognormal distribution. Results: The particular case study demonstrated that the results of the elevator wire life estimation by using the proposed method can provide the better solutions than existing methods. Conclusion: It can be economical to use accelerated degradation model for estimating the life of elevator wire rope.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 춘계학술대회
• /
• pp.1939-1944
• /
• 2004

Recently, several kinds of experimental and computational studies are being carried out to investigate the WIG aerodynamic characteristics which are of practical importance to develop the new ground transportation vehicle system. These works are mainly based upon conventional wind tunnel tests, but many problems associated with the WIG aerodynamic characteristics cannot be satisfactorily resolved due to the wind tunnel blockage effects or string problems to support the test object. To do this, it is necessary to develop a novel simulator appropriate to the WIG aerodynamics. The objective of the present study is to clarify the aerodynamic characteristics of a new developed WIG simulator, which is able to imitate real WIG flow circumstances such as gradually decelerating and accelerating flows.

• 한국전기전자재료학회논문지
• /
• 제15권1호
• /
• pp.93-101
• /
• 2002

In this study, the stator form-winding sample coils based on silicone resin and polyimide were made for fault prediction and reliability estimation on the C-Class(200$\^{C}$ ) insulation system of traction motors. The complex accelerative degradation was periodically performed during 10 cycles, which was composed of thermal stress, fast rising surge voltage, vibration, water immersion and overvoltage applying. After aging of 10 cycles, the condition diagnosis test such as insulation resistance '||'&'||' polarization index, capacitance '||'&'||' dielectric loss and partial discharge properties were investigated in the temperature range of 20 ∼ 160$\^{C}$. Relationship among condition diagnosis tests was analyzed to find a dominative degradation factor and an insulation state at end-life point.

• Current Photovoltaic Research
• /
• 제9권2호
• /
• pp.36-44
• /
• 2021

To endorse the reliability and durability of the solar photovoltaic (PV) device several tests were conducted before exposing to the outdoor field in a non-ideal condition. The PV module has high probability that intend to perform adequately for 30 years under operating conditions. To evaluate the long term performance of the PV module in diversified terrestrial conditions, one should use the outdoor performance data. However, no one wants to wait for 25 years to determine the module reliability. The accelerating stress tests performing in the laboratory by mimicking different field conditions are thus important to understand the performance of a PV module. In this review, we will discuss briefly about different accelerating stress types, levels and prioritization that are used to evaluate the PV module reliability and durability before using them in real field.