• Journal of the Korean Vacuum Society
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• v.12 no.3
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• pp.151-156
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• 2003

Two capacitance diaphragm gauges(CDG) and two resonance silicon gauges(RSG) were calibrated using an ultrasonic interferometer as a national low vacuum standard in KRISS. The CDG has superior pressure resolution and is rugged as well as resistant to over-pressure because of all-metal inner components. Meanwhile, the RSG is a new type of MEMS sensor that has excellent calibration stability and is resistant to mechanical shocks. The calibration uncertainties were analyzed according to the ISO procedures. Results showed that the maximum difference of the expanded uncertainties was $9\times10^{-3}$Pa at the generated pressure of 100 Pa for the two different types. It is remarkable that the RSG can be used as a transfer standard at low vacuum since their accuracies were found to be within 0.5 %.

• Journal of the Korean Ceramic Society
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• v.42 no.1
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• pp.22-27
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• 2005

The preparation of B4C by SHS in $B_{2}O_{3}-Mg-C$ system was investigated in this study. In the preparation of B4C, the effect on reactivity and reaction products of the initial pressure of inert gas in reactor, the content of Mg and C in mixture was investigated. The minimum initial pressure of inert gas in reactor for SHS reaction in this system was 25 atm, and as the pressure increased, the concentration of unreacted Mg decreased and combustion temperature increased. At the initial inert gas pressure in reactor of 25 atm, the optimum composition for the preparation of pure B4C was $2B_{2}O_{3}+6.3Mg +0.94C$. The B4C synthesized in this condition had an irregular shape and the particle size of $1\~3{\mu}m$.

• Journal of Ecology and Environment
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• v.29 no.6
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• pp.581-584
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• 2006

The tissue water relation parameters were compared to assess the resistance of representative three gardening tree species to water stress. Zelkova serrata showed a strong resistant characteristics to water stress compared to Betula platyphylla var. japonica and Liriodendron turipifera. Turgor pressure at turgor loss point in Z. serrata was -2.54 MPa, whereas those of 5. platyphylla var, japonica and L. turipifera were -2.24 and -2.03, respectively. In addition, Z. serrata showed less reduction in pressure potential to decrease of free water content in the leaf tissue, indicating effective shrinking of the cell wall compared to others. On the other hand, L. turipifera indicated a weak resistance to water stress, which has low turgor potential at turgor loss point and cell wall elasticity. These results suggest that Z. serrata would be suitable for relatively dry conditions of location and humid conditions of location would be suitable for L. dendronas plantation.

• Applied Chemistry for Engineering
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• v.9 no.1
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• pp.76-81
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• 1998

Physical adsorption on a silica gel(pore size of 80 nm, particle size of $10{\mu}m$)has been studied for binary mixture of acetone diluted in $CO_2$ by use of a FTIR transmission technique and we have compared the result of FTIR transmission technique with that of a chromatographic technique. Measurements were made at 313.2 K and under pressures up to 15MPa. As the pressure increases from 0.1MPa, the IA(Integral Absorbance) of the hydrogen-bonded OH groups interacting with acetone and adsorbed amount by use of a chromatographic technique increases at first, and reaches a maximum at a pressure below the critical pressure of $CO_2$, and then the intensities decrease gradually with increasing pressure. It is found that the pressure dependency of the chromatographic isotherm is a little larger than that of spectroscopic isotherm in the supercritical fluid region. This difference might be attributable to the weaker van der Waals force and relatively stronger hydrogen-bonding force influencing the adsorption of acetone on the sllica gel. The unique spectroscopic characteristics of amine group which vibrational frequencies of hydroxyl groups on the silica gel surface shift downward to about $1300cm^{-1}$ were measured from experimental result of triethylamine diluted in $CO_2$ or $N_2$.

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.5
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• pp.349-355
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• 2014

Wall thinning defects can occur in the pressure vessels used in a variety of industries. Such defects are related to the flow velocity. Considering the fact that such vessels constitute up to 70 or 80% of the plant structures in a power plant, it is important to measure internal defects as part of a safety evaluation. In this study, optical measurement were applied in a non-destructive evaluation using shearography to ensure the safety and improve the reliability of a power plant through the non-contact, non-destructive evaluation of pressure vessels. In order to verify whether the pressure vessels contained faults, experimental and analytical investigation were conducted to measure any internal defects and out-of-plane deformation from inner temperature changes and pressure changes in the piping of the circulation system. The most important factors in this research were the thickness, width, and length of a defect. An increase in these could confirm an increase in the deformation. Thus, internal defects in a pressure vessel were measured using shearography, which made it possible to ensure the reliability and integrity of the pipe.

• Journal of Korean Tunnelling and Underground Space Association
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• v.6 no.4
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• pp.291-302
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• 2004

Blast-induced anisotropic rock damage around a blast-hole was analyzed by a using numerical method with user-defined subroutine based on continuum damage mechanics. Anisotropic blasting pressure was evaluated by applying anisotropic ruck characteristics to analytical solution which is a function of explosive and rock properties. Anisotropic rock damage was evaluated by applying the proposed anisotropic blasting pressure. Blast-induced isotropic rock damage was also analyzed. User-defined subroutines to solve anisotropic and isotropic damage model were coded. Initial rock damages in natural ruck were considered in anisotropic and isotropic damage models. Blasting pressure and elastic modulus of rock were major influential parameters from parametric analysis results of isotropic rock damage. From the results of anisotropic rock damage analysis, blasting pressure was the most influential parameter. Anisotropic rock damage area in horizontal direction was approximately 34% larger and about 12% smaller in vertical direction comparing with isotropic rock damage area. Isotropic rock damage area under fully coupled charge condition was around 30 times larger than that under decoupled charge condition. Blasting pressure under fully coupled charge condition was estimated to be more than 10 times larger than that of decoupled charge condition.

• Information Systems Review
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• v.15 no.1
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• pp.1-24
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• 2013

This study empirically investigated inter-relationships among the influence factors on the adoption of e-commerce, which are classified as cause factor (i.e., perceived environmental uncertainty and competition), facilitators (i.e., perceived economic benefits, inter-organizational trust, suppliers' pressure and capability and asset specificity) and support factor (i.e., top management's support and organizational resource capability). The results of regression analyses showed that competition, inter-organizational trust, suppliers' pressure and capability, top management's support, and organizational resource capability have a positive impact on the adoption of e-commerce. In the analyses of inter-relationships among the influence factors, it was found that perceived environmental uncertainty positively influences suppliers' pressure and capability and perceived economic benefits, and competition has a positive impact on asset specificity. It was also observed that perceived economic benefits, inter-organizational trust and suppliers' pressure and capability positively affect top management's support, and inter-organizational trust and suppliers' pressure and capability have a positive impact on organizational resource capability. With mediating regression analyses, it was found that competition has an indirect impact on the adoption of e-commerce through the effect on perceived economic benefits, suppliers' pressure and capability, organizational resource capability and top management's support. The results of mediating regression analyses also showed that suppliers' pressure and capability and perceived economic benefits have indirect effects on the adoption of e-commerce through the effects on top management's support and organizational resource capability. From these results, it is concluded that intense competition causes the activation of facilitators, and the facilitators contribute to both the enhancement of top management support and the creation of organizational resource capability, which are directly linked to the adoption of e-commerce.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.814-819
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• 1998

원자력 발전소의 운영개선에 2차 방사성폐기물을 줄여야 하는 것은 중요한 과제이다. 기존 세탁 법은 2차 방사성폐기물을 상당히 많이 배출는데, 개선방안으로 초임계 유체($CO_2$)를 이용한 제염가능성을 알아보았다. 본 연구에서 순광유, 그리고 산업용으로 쓰이는 기어유와 그리스의 초임계 $CO_2$ 내에서의 용해도와, 제거율을 구하였다. 용해도 측정 실험에서는 초임계 상태에서 압력에 따라 용해도가 급격히 증가하였으며 반응시간 또한 매우 빨라 확산성이 매우 우수하였다. 실제 적용을 위해 소량의 첨가용매를 사용한다면 더욱 큰 성과가 기대된다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.6
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• pp.810-820
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• 1985

배기 decoupling chamber룰 갖고 있는 맥동 연소 급수가열기에 대한 수학적인 모델링과 관련된 컴퓨터 시뮬레이션을 하였고, 이 때 계에 대한 맥동 현상과 관련된 열적 및 동적 특성을 고려 였다. 시뮬레이션결과 시동기간에 대한 계의 각 부분에서 일어나는 열전달, 압력 및 온도를 구 였고 또한 해석의 제한성과 개선의 필요성을 논의하였다. 이 연구에서 얻어진 결과는 도관에서 맥동에 의한 대류열전달을 예측하기 위한 모델을 세우는데 활용될 수 있다.

• 정보화사회
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• s.43
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• pp.48-55
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• 1991

국가기간전산망사업의 일환으로 추진되고 있는 금융전산망사업은 금융기관의 급속한 전산화를 가져와 국민편의 확대는 물론 국제경쟁력 확보, 지급결제업무의 개선, 정책수립자료의 신속한 제공 등 많은 가시적 성과를 거두어 왔다. 이러한 금융전산망 사업은 그러나 은행.증권.보험.투자금융 등 각 업계별 전산화 뿐만 아니라 이들 전 금융기관이 공동참여하는 단일 전산망 구축문제, 그리고 외국은행 국내지점의 금융기관공동 전산망 가입 압력 등 대내외적으로 풀어나가야 할 산적한 많은 과제들을 안고 있다. 이에 본지는 대 국민 인식제고를 위해 금융전산망사업중 주도적으로 추진되고 있는 은행공동전산망의 종류와 내용, 추진현황, 향후전망과 과제 등을 알아본다.