• Journal of Electrochemical Science and Technology
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• 제9권1호
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• pp.20-27
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• 2018

We describe a redox-enhanced electric double-layer capacitor (EDLC) that turns the electrolyte in a conventional EDLC into an integral, active component for charge storage-charge is stored both through faradaic reactions with soluble redox-active molecules in the electrolyte, and through the double-layer capacitance in a porous carbon electrode. The mixed-redox electrolyte, composed of vanadium and iodides, was employed to achieve high power density. The electrochemical reaction in a supercapacitor with vanadium and iodide was studied to estimate the charge capacity and energy density of the redox supercapacitor. A redox supercapacitor with a mixed electrolyte composed of 0.75 M NaI and 0.5 M $VOSO_4$ was fabricated and studied. When charged to a potential of 1 V, faradaic charging processes were observed, in addition to the capacitive processes that increased the energy storage capabilities of the supercapacitor. The redox supercapacitor achieved a specific capacity of 13.44 mAh/g and an energy density of 3.81 Wh/kg in a simple Swagelok cell. A control EDLC with 1 M $H_2SO_4$ yielded 7.43 mAh/g and 2.85 Wh/kg. However, the relatively fast self-discharge in the redox-EDLC may be due to the shuttling of the redox couple between the polarized carbon electrodes.

• 대한기계학회논문집
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• 제16권8호
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• pp.1458-1467
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• 1992

본 연구에서는 균질재에서의 결과를 토대로 이종재에서도 그 성질이 보존될 것으로 기대되기 때문에 계면균열에서의 CED의 기본적 성질을 검토한후, 각 모드 인자 의 분리법과 평가법을 CED를 통해 제시한다. 또 제시한 수법을 이용하여 우선 탄성 균열 모델에서 유한요소해석을 통해 CED 및 각 모드 인자의 평가 및 기초적 검토를 실시하여 그 유효성을 확인한다.

• 한국조명전기설비학회지:조명전기설비
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• 제11권6호
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• pp.37-43
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• 1997

광방사에너지에 의해 염료나 안료의 밀도가 감소하며, 밀도 변화는 색변화를 초래한다. 이 연구에서는 방사에너지에 의한 염료밀도의 변화와, 밀도변화에 따른 색변화에 대한 가정을 이용하여 방사에너지에 의한 색변화를 예측할 수 있는 관계식을 만들었다. 또한 실험을 통하여 식중의 손상계수를 산출하였다. 이 식과 계수와 적절성을 검증하기 위하여 시료들을 일반 광원을 변색시키면서 그 변색의 크기를 측정하고 계산치와 비교한 결과, 대부분의 시료에서 일치하는 것을 확인할 수 있었다. 또한 가시 방사대에서 분광 손상계수는 분광 흡수율과 밀접한 관계가 있음을 알 수 있었다.

• 한국군사과학기술학회지
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• 제14권6호
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• pp.1192-1197
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• 2011

Recent developments of small-size unmanned or manned mobile systems such as autonomous robots, exoskeleton or armored suits, micro air vehicles, and unmanned armored vehicles require long-lasting independent power sources of high energy and power density to support the systems' operation for up to 72 hours in the fields. Chemical batteries such as Ni-MH, Li-Ion, the current primary power sources for mobile devices, however, are not capable of providing enough power and energy density for the next generation high power mobile machines. For this reason, KIMM along with KERI and KIMS has been carrying out a 500W MTG development project under the DAPA's "Next generation military power source R&D program" since 2009. In this paper, a design process for a 500W MTG system currently being developed at KIMM is briefly described and the technical issues related to its development are addressed.

• 한국재료학회지
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• 제26권2호
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• pp.95-99
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• 2016

In this study, 5 um sized $ZrSiO_4$ was ground to 1.9 um, 0.3 um, and 0.1 um sized powders by wet high energy milling process, and the sintering characteristics were observed. Pure $ZrSiO_4$ itself can-not be sintered to these levels of theoretical density, but it was possible to sinter $ZrSiO_4$ powder of nano-scale size of, -0.1 um to the theoretical density and to lower the sintering temperature for full density. Also, the decomposition of $ZrSiO_4$ with a size in the micron range resulted in the formation of monoclinic $ZrO_2$; however, in the nano sized range, the decomposition resulted in the tetragonal phase of $ZrO_2$. So, it was possible to improve the sintering characteristics of nano-sized $ZrSiO_4$ powders.

• 한국레이저가공학회지
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• 제14권4호
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• pp.14-20
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• 2011

The advantage of using lasers for through silicon via (TSV) drilling is that they allow higher flexibility during manufacturing because vacuums, lithography, and masks are not required; furthermore, the lasers can be applied to metal and dielectric layers other than silicon. However, conventional nanosecond lasers have disadvantages including that they can cause heat affection around the target area. In contrast, the use of a picosecond laser enables the precise generation of TSVs with a smaller heat affected zone. In this study, a comparison of the thermal and crystallographic defect around laser-drilled holes when using a picosecond laser beam with varing a fluence and repetition rate was conducted. Notably, the higher fluence and repetition rate picosecond laser process increased the experimentally recast layer, surface debris, and dislocation around the hole better than the high fluence and repetition rate. These findings suggest that even the picosecond laser has a heat accumulation effect under high fluence and short pulse interval conditions. To eliminate these defects under the high speed process, the CDE (chemical downstream etching) process was employed and it can prove the possibility to applicate to the TSV industry.

• Elastomers and Composites
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• 제49권2호
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• pp.160-166
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• 2014

자동차 선도장용으로 알루미늄 페이스트를 사용하여 6가지 베이스코트용 포뮬레이션이 설계되었다. 알루미늄 페이스트는 pancake 형태의 금속 안료인 #501, #801, #601와 cornflake 형태의 금속 안료인 #750, #770, #790가 사용되었다. 베이스코트의 상대적인 경화 밀도는 #501, #801, #601, #750, #770, #790 순으로 증가하였다. T-bending, 내충격성, 테이핑 부착력은 경화 밀도의 증가에 따라 향상되었다. Cornflake 형태의 안료에 대한 외관(combined factor) 테스트에서 입자가 가장 작은 #790이 다른 두 가지(#750, #770)와 비교하였을 때 가장 좋은 combined factor를 보여 주었다.

• Nuclear Engineering and Technology
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• 제53권9호
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• pp.3058-3067
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• 2021

Sodium zinc borate glasses doped with dysprosium and modified with different concentrations of barium oxide (0-50 mol %) were fabricated using the melting quenching technique. The structural properties of the prepared glass systems were characterized using XRD and FTIR methods. The absorption spectra of the prepared glasses were measured to determine their energy gap and their related optical properties. The density of the glasses and other physical parameters were also reported. Additionally, with the help of Photon Shielding and Dosimetry (PSD) software, we investigated the radiation shielding parameters of the prepared glass systems at different energy values. It was found that an increase in the density of the glasses by increasing the concentration of BaO significantly improved the gamma ray shielding ability of the samples. For practical results, a compatible irradiation set up was designed to check the shielding capability of the obtained glasses using a gamma ray source at 662 keV. The experimentally obtained results strongly agreed with the data obtained by PDS software at the same energy. These results demonstrated that the investigated glass system is a good candidate for several radiation shielding applications when comparing it with other commercial shielding glasses and concretes.

• 한국분말재료학회지
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• 제26권1호
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• pp.58-69
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• 2019

High performance lithium-ion batteries (LIBs) have attracted considerable attention as essential energy sources for high-technology electrical devices such as electrical vehicles, unmanned drones, uninterruptible power supply, and artificial intelligence robots because of their high energy density (150-250 Wh/kg), long lifetime (> 500 cycles), low toxicity, and low memory effects. Of the high-performance LIB components, cathode materials have a significant effect on the capacity, lifetime, energy density, power density, and operating conditions of high-performance LIBs. This is because cathode materials have limitations with respect to a lower specific capacity and cycling stability as compared to anode materials. In addition, cathode materials present difficulties when used with LIBs in electric vehicles because of their poor rate performance. Therefore, this study summarizes the structural and electrochemical properties of cathode materials for LIBs used in electric vehicles. In addition, we consider unique strategies to improve their structural and electrochemical properties.

• Elastomers and Composites
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• 제58권4호
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• pp.208-215
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• 2023

In this study, the properties of polyurethane-polydimethylsiloxane (PU-PDMS) hybrid foams containing different types and contents of physical blowing agents (PBAs) were investigated. Two types of blowing agents, namely physical blowing agents and thermally expandable microspheres (TEM), were applied. The apparent density was measured using precisely cut foam samples, and the pore size was measured using image software. In addition, the microstructure of the foam was confirmed via scanning electron microscopy and transmission electron microscopy. The thermal conductivities related to the microstructures of the different foams were compared. When 0.5 phr of the hydrocarbon-based PBA was added, the apparent density and pore size of the foam were minimal; however, the pore size was larger than that of neat foam. In contrast, the addition of 3 phr of TEM effectively reduced both the apparent density and pore size of the PBAs. The increase in resin viscosity owing to TEM could enhance bubble production stability, leading to the formation of more uniform and smaller pores. These results indicate that TEM is a highly efficient PBA that can be employed to decrease the weight and pore size of PU-PDMS hybrid foams.