• Current Photovoltaic Research
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• 제7권3호
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• pp.55-60
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• 2019

Polymer:nonfullerene solar cells with an inverted-type device structure were fabricated by employing the bulk heterojunction (BHJ) active layers, which are composed of poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophene-2-yl)-benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione))] (PBDB-T) and 3,9-bis(6-methyl-2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3-d']-s-indaceno[1,2-b:5,6-b']dithiophene (IT-M). The BHJ layers were formed on a pre-patterned indium-tin oxide (ITO)-coated glass substrate by spin-coating using the blend solutions of PBDB-T and IT-M. The solar cell performances were investigated with respect to the cell position on the ITO-glass substrates. In addition, the short-term shelf lifetime of solar cells was tested by storing the PBDB-T:IT-M solar cells in a glovebox filled with inert gas. The results showed that the performance of solar cells was relatively higher for the cells close to the center of substrates, which was maintained even after storage for 24 h. In particular, the PCE of PBDB-T:IT-M solar cells was marginally decreased after storage for 24 h owing to the slightly reduced fill factor, even though the open circuit voltage was unchanged after 24 h.

• 대한임베디드공학회논문지
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• 제9권2호
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• pp.75-80
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• 2014

Energy consumption of sensor nodes is minimized because it has limited energy generator in wireless sensor network. Electronic shelf label system is one of application fields using wireless sensor networks. Battery size of small apparatus for displaying price is restricted. Therefore its current consumption have to be minimized. Furthermore the method for minimization of peak current would be considered because life cycle of coin battery used to display or RF is vulnerable to intensity of drain current. In this paper, we analyze current consumption pattern of low-power electronic shelf label system. Then we propose the method for minimization of current consumption by modification of software and hardware. Current consumption of the system using proposed method are approximately 15 to 20 percent lower than existing system and the life cycle of the system is approximately 10 percent higher than existing system.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2007년도 학술발표회 논문집
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• pp.201-202
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• 2007

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.163-167
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• 2017

유도탄 수명 연장은 유도탄의 교체 비용을 절감할 수 있고 전력을 유지할 수 있으며, 시효성 품목의 수명 평가와 유도탄의 정비와 구성품의 성능 개량으로 구성된다. 그러므로 수명 연장 기술은 체계 개발과 동시에 개발하여 지속적으로 발전시켜야 하며, 많은 분야의 전문 기술과 오랜 기간의 경험과 데이터베이스가 결합된 융합 기술이다.

• 한국추진공학회지
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• 제16권4호
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• pp.33-41
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• 2012

KM6 단기추진제의 저장수명을 감마과정 이론을 이용한 확률론적 방법으로 추산하였다. 장기 저장에 따른 안정제 함량의 저하량이 0.8%일 때를 상태고장으로 보았으며 정상감마과정으로 가정하였을 때 형상함수의 상수와 척도모수를 모멘트법으로 추정하였다. 저장기간별 확률밀도함수로부터 각 저장기간에서의 상태분포를 확인할 수 있으며 누적고장분포함수 곡선에서 누적고장확률이 10%인 $B_{10}$수명은 25년이며 $B_{50}$수명은 36년으로 추산되었다. 실용적 관점에서 볼 때 $B_{50}$수명을 평균저장수명으로 볼 수 있으며 확률과정론을 이용하면 저장수명을 분포곡선으로 표현할 수 있다.

• Current Photovoltaic Research
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• 제8권4호
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• pp.107-113
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• 2020

Here we report the long-term stability of polymer:nonfullerene solar cells which were stored under dark and indoor light condition. The polymer:nonfullerene solar cells were fabricated using bulk heterojunction (BHJ) layers of poly[(2,6-(4,8-bis(5-(2-ethylhexyl) thiophen-2-yl)-benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione))] (PBDB-T) and 3,9-bis(6-methyl-2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3-d']-s-indaceno[1,2-b:5,6-b']dithiophene (IT-M). To investigate their long-term stability, the PBDB-T:IT-M solar cells were stored in an argon-filled glove box. One set of the fabricated solar cells was completely covered with an aluminum foil to prevent any effect of light, whereas another set was exposed to indoor light. The solar cells were subjected to a regular performance measurement for 40 weeks. Results revealed that the PBDB-T:IT-M solar cells underwent a gradual decay in performance irrespective of the storage condition. However, the PBDB-T:IT-M solar cells stored under indoor light condition exhibited relatively lower power conversion efficiency (PCE) than those stored under the dark. The inferior stability of the solar cells under indoor light was explained by the noticeably changed optical absorption spectra and dark spot generation, indicative of degradations in the BHJ layers.

• 한국신뢰성학회지:신뢰성응용연구
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• 제16권3호
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• pp.208-215
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• 2016

Purpose: ASRP for the domestic development guided missiles requires not only for the reliability evaluation of the products in storage but also for the life cycle management of the products including development prototypes and initial production items. Methods: For this purpose, it should be performed to build a performance database before and after the accelerated aging test with shelf life items including development prototypes and initial production items, based on which the lifetime prediction should also be carried out. In addition, HILS must be applied for the acceptance test with the initial and follow-up production items, and also for ASRP for the long-term storage products in order to secure systematic quality assurance. Results: The results for the life cycle reliability Improving of domestic development of guided missiles are DB building of prescription Item performance, active application of HILS, Management associated with guided missiles life cycle and to Secure technology data about the introduction of foreign guided missiles. Conclusion: Furthermore, it is demanded that DTaQ, the managing agency of ASRP, actively take part in the process to maintain reliability engagement consistency over the life cycle of guided missiles.

• 한국추진공학회지
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• 제18권3호
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• pp.17-25
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• 2014

본 논문은 장약포의 저장기간에 따른 파단하중 저하에 관하여 감마과정 모델을 이용하여 저장수명을 예측하는 방법에 대한 연구결과이다. 추진제의 자연분해로 발생하는 질소화합물과 장약포의 화학반응은 파단하중을 저하시킨다. 장약포의 가속수명시험 결과에 감마과정 모델을 적용하여 시간의 경과에 따른 상태와 수명을 확률분포로 표현하였다. 저장수명은 중위수로 표현하고 품질보증을 위한 정책결정기준으로 $B_1$ 또는 $B_5$ 수명을 활용하는 것이 적절하다.

• Nuclear Engineering and Technology
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• 제44권5호
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• pp.543-550
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• 2012

The decrease in the fracture toughness of ferritic steels in a reactor pressure vessel is an important factor in determining the lifetime of a nuclear power plant. A surveillance program has been in place in Korea since 1979 to assess the structural integrity of RPV steels. In this work, the surveillance data were collected and analyzed statistically in order to derive the empirical relationship between the embrittlement and strengthening of irradiated reactor pressure vessel steels. There was a linear relationship between the yield strength change and the transition temperature shift change at 41 J due to irradiation. The proportional coefficient was about $0.5^{\circ}C$/MPa in the base metals (plate/forgings). The upper shelf energy decrease ratio was non-linearly proportional to the yield strength change, and most of the data lay along the trend curve of the US results. The transition regime temperature interval, ${\Delta}T_T$, was less than the US data. The overall change from irradiation was very similar to the US results. It is expected that the results of this study will be applied to basic research on the multiscale modeling of the irradiation embrittlement of RPV materials in Korea.

• Nuclear Engineering and Technology
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• 제54권6호
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• pp.2198-2203
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• 2022

As robotics become more sophisticated, there are a growing number of generic systems being used for routine tasks in nuclear environments to reduce risk to radiation workers. The nuclear sector has called for more commercial-off-the-shelf (COTS) devices and components to be used in preference to nuclear specific hardware, enabling robotic operations to become more affordable, reliable, and abundant. To ensure reliable operation in nuclear environments, particularly in high-gamma facilities, it is important to quantify the tolerance of electronic systems to ionizing radiation. To deliver their full potential to end-users, mobile robots require sophisticated autonomous behaviors and sensing, which requires significant computational power. A popular choice of computing system, used in low-cost mobile robots for nuclear environments, is the UP Core single board computer. This work presents estimates of the total ionizing dose that the UP Core running the Robot Operating System (ROS) can withstand, through gamma irradiation testing using a Co-60 source. The units were found to fail on average after 111.1 ± 5.5 Gy, due to faults in the on-board power management circuitry. Its small size and reasonable radiation tolerance make it a suitable candidate for robots in nuclear environments, with scope to use shielding to enhance operational lifetime.