• Journal of The Korean Society of Agricultural Engineers
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• v.50 no.2
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• pp.27-34
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• 2008

Recently, owing to the development of industry and improvement of building techniques, concrete structures are becoming larger and higher. This study was performed to analyze hydration reation properties of concrete with binders and admixtures, such as OPC, low heat cement, belite rich cement, slag powder, lime powder and fly ash. To investigate effects of PC type superplasticizer on the hydration, experiments involving FT-IR, XRD, DSC, SEM were analyzed at the curing age 1day, 3days and 28days. The hydration reaction rate of OPC concrete slightly delayed at the curing age 1day, blast furnace slag powder and fly ash were more effective. BRC and LHC concretes can be used for concrete structures in winter season.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.4
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• pp.630-638
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• 2011

A new smooth bore test barrel was developed to be used in sensitivity assessment test for explosives and fragment impact test. The bore diameter of the barrel is 20 mm, and the powder chamber is designed to be replaceable with the 12.7 mm, 20 mm and 30 mm type chamber. The test results showed the wide range of fragment velocity from 400 to 2000 m/s, included the fragment velocity requirement of the fragment impact test(alternate procedure #1) in MIL-STD-2105B. The stability of the bullet trajectory was checked by test shots and the structural safety of the system has been confirmed through the stress analysis and the interior ballistics analysis of the barrel.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.405-409
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• 2010

금속분말을 청정 에너지원으로 이용하기 위해 금속분말 소형 연소기의 구현이 필요하다. 이를 위한 선행연구로 연료 공급 시스템인 핀틀인젝터형(pintle injector type) 금속분말 공급장치의 중요 성능인 분사량을 실험적으로 측정하였다. 분사량 측정 시험에 앞서 간단한 금속분말 공급 시험으로 확인된 문제점을 장치의 변경을 통해 해결하였다. 측정 시험의 결과, 연료 공급 장치에 이송 가스 압력이 상승함에 따라 많은 질유량의 금속분말이 분사되었고 압력에 따른 정량적 분사량을 확인하였다. 이송 가스와 금속분말의 혼합 성능을 개선하여 균일한 분사를 하고자 이송 가스를 25 Hz로 가진 하여 공급하였고 가진이 없는 경우의 실험결과와 비교하였다.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.220.2-220.2
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• 2003

Many interference in blood should be considered for non-invasive blood glucose level monitoring by near-infrared spectroscopy because blood glucose concentration is about 0.1% (w/v) in normal state. In this study, we investigated the influence of other blood components on blood glucose level monitoring by near-infrared spectroscopy. It carried out by newly developed portable type-NIR system (1100∼2200 nm). Spectrum features of NIR diffuse spectral data were investigated for some blood compnents powder such as hemoglobin, blood serum albumin, urea, uric acid, ascorbate, glucose, cholesterol and as adding glucose powder into other blood components powder mixture. (omitted)

• Journal of the Korean Ceramic Society
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• v.34 no.12
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• pp.1247-1253
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• 1997

Sinter-active yttria powders were prepared by a solution precipitation with using a self-decomposing precipitation agent NH2CONH2(urea). The cold-pressed powders can be sintered to full density and the microstructure of grains less than 200 nm at a temperature as low as 120$0^{\circ}C$. The activity of the yttria powder has been controlled by varying nucleation conditions during precipitation and by minimizing formation of aggregates. The type of precursor is decisive in preparation of a sinter-active oxide powder, and urea is desirable as a precipitation agent for an active yttrium oxide powder.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.935-938
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• 2001

This paper reports the relation of concrete setting characteristic and lateral pressure in mass concrete wall such as side wall of LNG underground storage tank. In order to estimate the lateral pressure, initial setting time of low heat cement concrete with type of mineral admixture was measured for three concrete mixtures(W/P=41.6%) containing limestone powder, fly ash, and slag powder. As a result, the lateral pressure of the concrete containing limestone powder was the smallest than those of other concretes as well as the initial setting time.

• Journal of Powder Materials
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• v.2 no.2
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• pp.142-148
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• 1995

2219 aluminum alloy bonded diamond wheels containing intermetallic compounds were fabricated by powder metallurgy method. Nickel and titanium were added in aluminum matrix piece. The hot pressing condition was $600^{\circ}C$ and 20 Mpa in the furnace of the electric resistance type. The mechanical properties and grinding tests were carried out to confirm the wheel performance. Aluminum oxide ceramics were chosen for use in the grinding tests. The test proved that the heat resistance 2219 aluminum bonded diamond wheel containing 15 wt% nickel and 15 wt% titanium respectively showed the best performance.

• Journal of Industrial Technology
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• v.28 no.A
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• pp.119-123
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• 2008

Structural and magnetic properties of $CO_{1-x}Zn_xZ$ ($Ba_3Co_{1-x}Zn_xFe_{24}O_{41}$) hexa-ferrite are studied using XRD, VSM and SEM, respectively. Powder was prepared from co-precipitation and firstly heat treated at $1350^{\circ}C$ for 6 hours in $O_2$ atmosphere. Second heat treatment was performed at 900, 1000, $1100^{\circ}C$ for 6 hours in air, respectively. Saturation magnetization value of first heat treated powder is acceptable and coercivity is high for applying to device. These result may be originated from incomplete formation reaction from M and Y phases to Z phase. Second heat treatment leads to small value of coercivity.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1382-1384
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• 1998

Electroluminescence is occurred when phosphor is located in electric field. Object of this research show new type of powder electroluminescent device (PELD) for high brightness compared with conventional PELD. New type of PELD structured as follow ITO/phosphor + dielectric/Silver paste). To investigate optical properties of PELDs, EL spectrum, CIE coordinate system, Brightness of PELDs was measured. The suitable ratio between phosphor and dielectric in new type of PELD was 7:3(phosphor:dielectric). At 200 V 400 Hz, new type of PELD which had ratio of 7:3 was 5700 cd/$m^2$.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2001.11a
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• pp.10-10
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• 2001