• 한국세라믹학회지
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• 제16권1호
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• pp.31-37
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• 1979

The middle point of composition within the system $MgO-Al_2O_3-SiO_2$ has been studied for applicability as ceramics dielectrics. A Kyul Sung Tale of high purity, magnesia clinker of Sam-wha chemical company, C.P. aluminium oxide, calcium carbonate, red lead, barium carbonate which was made into frit were used the raw materials. A number of steatite ceramics were prepared under carefully controlled condition and the water absorption, linear shrinkage, power factor, dielectric constant and dielectric loss were measured at elevated temperature. When we used magnesia clinker as flux, the quantity of this flux was 0.05mole, sintering temperature was continued for 2 hrs. at 1, 27$0^{\circ}C$. From this conditions, we could get the data whose power factor was 0.142%, water absorption was zero, linear shrinkage was 8.76%, dielectric constant was 5.63, dielectric loss was 0.00799. When we used red lead as flux, the quantity of this flux was 0.033mole and 0.066mole, sintering temperature was continued for 2hrs. at 1, 26$0^{\circ}C$. From this conditions, we could get the data whose water absorption was zero, linear shrinkage was 8.03%, and 8.48%, power factor was 0.136% and 0.062%, dielectric loss was 0.0072 and 0.0037. When we used barium carbonate made into frit as flux, the quantity of this flux was 0.02mole, sintering temperature was continued for 2hrs. at 1, 27$0^{\circ}C$. From this conditions, we could get the data whose water absoption was zero, linear shrinkage was 8.44%, power factor was 0.138%, dielectric constant was 5.69, dielectric loss was 0.0074.

• 대한기계학회논문집
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• 제19권9호
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• pp.2122-2132
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• 1995

There are some cases which require to grasp the abrasion resistance property in the fields of the high-technology to be required the high specific strength and modulus. In this study, wear test with the various test temperature and velocity were performed in the SiCw/A16061 composite and A16061 matrix using the wear test machine of the ring-on-disc type. As the results, the friction and wear properties by various test temperature and velocity were examined. The worn surface has observed by scanning electron microscope in order to examine the wear mechanism.

• 한국광학회지
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• 제5권2호
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• pp.311-318
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• 1994

광섬유의 클래딩을 갈아내고 코어 가까이에 알루미늄 박막을 증착하여 표면 플라즈몬으로의 편광 선택적인 모드 결합 원리를 이용하는 광섬유 편광기를 제작하였다. 633nm, 830nm, $1.3\mu\textrm{m}$의 단일 모드 광섬유를 사용하여 알루미늄 박막의 두께를 달리하며 소광률과 삽입손실을 측정한 결과 대부분의 샘플에서 30dB 이상의 소광률을 얻을 수 있었으며 삽입손실은 0.2dB 에서 1.5dB 사이였다.

• 한국세라믹학회지
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• 제30권4호
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• pp.309-315
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• 1993

Gas pressure sintering is a promising process in various densification methods of high strength Si3N4 ceramics. Environmental influences on gas pressure sintering of Si3N4 was investigated with the variationof packing powder, specimen container and N2 gas pressure. The specimens had higher density, larger weight loss and inhomogeneous color in graphite specimen container than in SN26 crucible. The variations of sintering densities in various packing powders (Si3N4, SN26, AlN, BN) were very small but SiC powder was synthesised in graphite crucible with Si3N4 packing powder, aluminium oxynitride compounds were synthesised in SN26 crucible with AlN packing power. Also N2 gas pressure over 20kg/$\textrm{cm}^2$ reduced the densification of Si3N4 in one step-gas pressure sintering. As the result of two step-gas pressure sintering at 700kg/$\textrm{cm}^2$ for 15min., relative density of 99.9% and 3-point bending strength of 1090MPa and dense microstructure of 3~4${\mu}{\textrm}{m}$ grain size were obtained.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(1)
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• pp.439-442
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• 2002

We present in this Paper a microwave Power sensor fabricated by a standard CMOS process and a bulk micromachining process. The sensor consists of a CPW transmission line, a resistor as a healer, and thermocouple arrays. An input microwave heater, the resistor so that the temperature rises proportionally to the microwave power and tile thermocouple arrays convert it to an electrical signal. The sensor uses air bridged 8round of CPW realized by wire bonding to reduce tile device size and cost and to improve the thermal impedance. Al/poly-Si junctions are used for the thermocouples. Poly-Si is used for tile resister and Aluminium is for transmission line. The resistor and hot junctions of the thermocouples are placed on a low stress silicon nitride diaphragm to minimize a thermal loss. The fabricated device operates properly from 1㎼ to 100㎽\ulcorner of input power. The sensitivity was measured to be ,3.2～4.7 V/W.

• Structural Engineering and Mechanics
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• 제33권4호
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• pp.391-406
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• 2009

Viscoelastic materials store as well as dissipate energy to the thermal domain under deformation. Two efficient modelling techniques reported in literature use coupled (thermo-mechanical) ATF (Augmenting Thermodynamic Fields) displacements and ADF (Anelastic Displacement Fields) displacements, to represent the constitutive relationship in time domain by using certain viscoelastic parameters. Viscoelastic parameters are first extracted from the storage modulus and loss factor normally reported in hand books with the help of Genetic Algorithm and then constitutive relationships are used to obtain the equations of motion of the continuum after discretizing it with finite beam elements. The equations of motion are solved to get the frequency response function and modal damping ratio. The process may be applied to study the dynamic behaviour of composite beams and rotors comprising of several viscoelastic layers. Dynamic behaviour of a composite beam, formed by concentric layers of steel and aluminium is studied as an example.

• 한국산학기술학회논문지
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• 제17권3호
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• pp.171-176
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• 2016

본 논문은 도로안전시설물의 공용중 부식 발생으로 인한 기능 손실을 줄일 수 있는 방안으로 고내식성 용융합금도금 강판을 적용한 도로안전시설물을 제안한다. 고내식성 용융합금도금강판을 적용한 도로안전시설물 제품에 대한 신뢰성 있는 충돌성능 평가 기초자료를 제공할 목적으로 고내식강이 적용된 교량난간 제품에 대한 충돌 시뮬레이션 및 실물 차량 충돌시험 연구를 수행한다. 시뮬레이션 및 실차충돌 시험 결과, 변형률 속도 의존성을 고려할 수 있는 정교한 동특성 재료모델을 도입한 충돌 시뮬레이션을 통해 얻어지는 충돌 거동과 실물 차량 충돌 시험 결과가 매우 유사한 것으로 도출되었다. 본 논문에서 제안된 고내식성 용융합금도금 강판을 적용한 교량난간은 실물 차량 충돌 시험의 충돌성능 평가 기준을 모두 충족시켜 현장 적용을 앞두고 있다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.219-228
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• 2006

In urban areas, tunnelling induced ground deformations, particularly ground settlements should be considered in order to minimize the damage of adjacent structures. Therefore, an appropriate monitoring system for the tunnel construction should be setup at the planning or design stage. A number of studies on ground settlements due to tunnelling in soft ground have been carried out so far. However, most studies have focused on clay soil rather than sand soil. In particular, a few studies on behaviour of subsurface deformations in granular material have been reported. In this study, two-dimensional laboratory model test with aluminium rods regarded as continuum granular material and close range photogrammetric technique, and numerical analysis were carried out in order to identify the behaviour of subsurface deformations due to shallow tunnelling. Direction and magnitude of displacement vectors from the model test was identical to the numerical analysis. In particular, the vector direction was appeared to be toward a point below the tunnel invert level. A narrow 'chimney or tulip like' pattern of vertical displacement was confirmed by both the model test and numerical analysis. This is consistent with the field data. In addition to the qualitative comparison, the quantitative comparison of subsurface settlements according to 2D volume loss showed good agreement between the model test and numerical analysis. Therefore, close range photogrammetric technique applied in the model test may be used to validate the result from the continuum numerical analysis.

• Journal of Plant Biology
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• 제37권3호
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• pp.309-316
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• 1994

To make regional comparisons of water status of pitch pine, the temporal changes of water status in pitch pine were investigated at different areas; urban Seoul (heavily polluted area), surburb of Seoul (lightly polluted area), and rural area (control). The effects of air pollutants, acid rain and chemical properties of soil on water deficit in pitch pine were also investiaged. Water content of needles growing at polluted areas were usually lower than that at unpolluted area. Water saturation deficit of needles growing at polluted areas were usually higher than that at unpolluted area especially in dry season. These results indicated that water in needles growing at polluted areas were usually more deficient than that at unpolluted area, and were more deficient in April than other months. At polluted areas, the older the needles were, the more quickly transpirated the water in the needle was. At unpolluted areas, however, water in old needles was not so quickly transpirated as those at polluted areas. Water potential of needles of pitch pine seedlings treated with simulated acid rain (SAR) of pH 3.5 decreased more quickly than that of needles treated with SAR of pH 5.6. Loss of water through epicuticular layer was greater in the following order: magnesium deficiency＋100 $\mu$M aluminium>100$\mu$M aluminium>magnesium deficiency>control. In addition to Mg deficiency and Al toxicity, growth decline of pitch pine widely occurring in polluated Seoul could to a large extent be due to cuticle degredation and abnormal vertical distribution of fine roots, which lead to water stress, particularly in dry seasons.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2005년도 학술대회 논문집
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• pp.151-155
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• 2005

지금까지의 핵융합 장치는 자기우물과 열역학을 바탕으로 한 토카막 장치가 수소핵융합을 하였으나 고온의 플라스마를 장시간 동안 가둠이란 현실적으로 불가능하여 성공사례가 없었다. 본 핵융합 촉진 방법을 이용한 새로운 핵융합 장치는 토카막 장치의 토로이달 자기장용 알루미늄코일 내에 토러스 철심 C형 Core Block과 토로이달 알루미늄코일을 넣어 토로이달 자기장을 모으고 토로이달 전류 흐르도록 하여 토러스 Core의 일부가 절개된 간극사이에 핵융합로를 배치하고 융합원료(전해액)를 토로이달 전류로 전기분해 한다. 전원과 토로이달 자계용 코일, 토로이달 코일 융합원료로 직렬회로로 이루어져 있어 토로이달 전류는 필라멘트 전류로 되어 융합원료에 투입된다. 필라멘트 전류사이에는 자기흡입력이 외부의 입력전력으로 계속 증대되어 쿨롱에 힘을 넘어 핵융합에 이르고 그로인해 질량결손이 생겨 아인슈타인의 질량에너지$(E=mC^2)$가 빛에너지와 열에너지로 방출됨을 확인했다.