• 한국재료학회지
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• 제14권10호
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• pp.731-736
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• 2004

Herein, we report on the co-firing of a low-K wiring substrate and a middle-K functional substrate in LTCC. Firstly, we researched the sintering behavior and dielectric properties of the low-k wiring substrate comprised by alumina and glass frit with ${\varepsilon}_r$, of $\sim7$ and the middle-k functional substrate comprised by $Ba_{5}Nb_{4}O_{15}$ and glass frit with ${\varepsilon}_r$, of $20\sim30$. The warpage and delamination between the hetero layers of the low-K and the middle-K composition were also studied. In particular, physical matching of the hetero layers could be possible by adjusting of the sintering properties of the composition. We observed that an introduction of the glass frit to the low- and middle-K substrate gives rise to a minimization of an effect given by separation of the hetero layers, and modification of the fraction of the glass frit accompanied by a variation of the composition could control the sintering behavior and its beginning temperature. In the case of co-firing of the L03 as the low-K wiring substrate composition and the M03 as the middle-K functional substrate composition at $875^{\circ}C$, we could fabricate a desirable structure of hetero layers without any kinds of structural defects such as separation, warpage, delamination, pore trap, etc. We suppose that the co-firing techniques described in this study would provide a helpful method to fabricate a LTCC multi-functional for the next generation.

• 대한기계학회논문집A
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• 제24권10호
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• pp.2529-2534
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• 2000

Torsional vibration analysis in a large two -stroke low speed diesel engine and generator system for stationary power plants is performed to verify that the vibration characteristics of shafting system meet design requirements. Our own developed S/W is employed for the analysis, whose results are evaluated comparing with measurements. Vibration analysis results of the system are presented according to the change of loading(unload, 100%load, 110% load) and operating(mis-firing, uneven firing) conditions of the stationary power plants.

• 한국세라믹학회지
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• 제52권2호
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• pp.159-164
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• 2015

We manufacture artificial lightweight aggregates (ALWAs) using bottom-ash as the primary raw material. We coat the ALWA surfaces with low-melting point materials in order to enable them to bloat, which is essential to reduce the bulk density of the aggregate. Then, we sinter the prepared aggregates at 1000, 1100, and $1200^{\circ}C$ using either the direct or two-step firing schedules. Finally, we evaluate the properties of the fired samples through analyzing their bulk density, water absorption, and microstructure. The surface-modified samples result in a reduction of their bulk density by $0.3{\sim}0.4g/cm^3$ regardless of the firing method used. Based on these results, we conclude that this approach could provide a viable method for the mass-production of ALWAs from industrial waste such as bottom-ash.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.278-278
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• 2007

Ag conductive thick film has been used in bus and address electrodes of PDP (Plasma display panel). In PDP fabrication, the firing temperature of electrode is normally $550{\sim}580^{\circ}C$. For the application of PDP industry, we investigated an Ag conductive thick film with firing temperature. Low melting glass frit was used in the conductive thick film. The thermal properties of Ag and frit were determined by a hot stage microscopy. Based on the our results, we suggest that the Ag conductive thick film should be considered of the firing temperature which is correlated to the shrinkage, conductivity, and shape of thick film.

• 한국세라믹학회지
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• 제29권10호
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• pp.827-835
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• 1992

The effects of CeO2 on the properties of cordierite-based glass-ceramics and its applicability to low firing temperature substrate were examined. Glass-ceramics were prepared by sintering the glass powder compacts at 900~100$0^{\circ}C$ for 3 h. Density, bending strength, dielectric constant and thermal expansion coefficient of the glass-ceramics were measured as functions of CeO2 contents and sintering temperatures. By adding CeO2, dense glass-ceramics were obtained below 100$0^{\circ}C$. dielectric constant and bending strength were more dependent on the porosity of glass-ceramics containing 5 wt% CeO2, sintered at 100$0^{\circ}C$ for 3 h, were as follows; relative density is 95.3%, bending strength is 178$\pm$11 MPa, dielectric constant is 4.98$\pm$0.20 (at 1 MHz) and thermal expansion coefficient is 33.7$\times$10-7/$^{\circ}C$. Therefore, the glass-ceramics containing 5 wt% CeO2 appeared to be suitable for low firing temperature substrate of electronic devices.

• 한국세라믹학회지
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• 제31권4호
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• pp.427-435
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• 1994

Cu-metallized low firing temperature substrates were synthesized by cofiring green sheet of cordierite-based glass with Cu. By Sol-Gel method, Cu powder was coated with borosilicate gel which should act as a glass frit in Cu paste during cofiring. Theoretical weight ratios of Glass/Cu were controlled to be 2.5, 5, 10 and 15% by varying alkoxide concentrations. Average particle size of coated Cu was 0.629~0.674 ${\mu}{\textrm}{m}$ in comparison to that of as-received Cu(0.596 ${\mu}{\textrm}{m}$), which increased with alkoxide concentration but did not increase above certain concentration. The weight ratios of coated layer were 2.11~5.37%. The properties of Cu-metallized low firing temperature substrate, cofired at 90$0^{\circ}C$ for 1h under H2/N2 atmosphere, were as follows; sheet resistance was 13~43 m{{{{ OMEGA }}/$\square$, adhesion strength was 1.0~2.1 kgf/$\textrm{mm}^2$. From the observations of SEM photographs, the gel coated on Cu performed excellently as a glass frit.

• 한국군사과학기술학회지
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• 제22권1호
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• pp.20-26
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• 2019

In this paper, we propose measurement based numerical resistivity model for low energy exploding foil initiator (LEEFI) of electronic safety and arming device(ESAD). A resistivity model describes a behavior of variable resistance in LEEFI by firing current. The previous resistivity model was based on high energy detonator applications as explosive bridge wire and exploding foil initiator. Therefore, to estimate the voltage, current, and burst time of LEEFI, a resistivity model suitable for LEEFI is needed. For the modeling of resistivity of LEEFI, we propose a specific action based equation which represents a behavior of LEEFI when firing current is applied. To verify the proposed model, we analyze a firing current transmission path to obtain parasitic impedance. We experimentally verify that the proposed resistivity model offers precise estimation for the behavior of variable resistance in LEEFI.

• 한국항공우주학회지
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• 제50권4호
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• pp.233-240
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• 2022

스마트무장은 종말 유도조종을 통해 정밀타격 임무를 수행하는 초소형 유도무기로 미래 전장환경의 신무기체계이다. 하지만 크기로 인한 구조적 제한으로 인해 압전구동 방식의 조종날개를 이용해 제어를 수행하기 때문에 기동력이 작아 유도범위가 제한적이다. 본 논문에서는 스마트무장의 효과도를 높이기 위한 비 표준조건 사격제원 산출 알고리즘을 제안한다. 제안된 알고리즘은 획득한 전장환경 정보를 이용해 표준조건에서의 사격제원을 보정해 비 표준조건의 사격제원을 산출한다. 다양한 조건에서의 수치 시뮬레이션을 통해 제안된 알고리즘의 성능을 검증하였다.

• Journal of Mechanical Science and Technology
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• 제14권4호
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• pp.433-440
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• 2000

The influence of combustion air at temperatures on nitric oxide emission was studied. The nitric oxide emission generally increases with a rise in the temperature of the combustion air. However, if combustion products for dilution of fuel or combustion air are used before the combustion reaction, then the nitric oxide emission can be reduced even when highly preheated air for combustion air is used. Combustion in low oxygen concentrations flattens the firing mode, resulting in a uniform reaction, and, thus, low nitric oxide emission can be achieved.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1999년도 추계학술발표강연 및 논문개요집
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• pp.170-170
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• 1999