• 한국지반공학회논문집
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• 제28권11호
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• pp.53-67
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• 2012

본 논문에서는 기존에 사용되던 철선 TDR계측선의 문제점을 해결하기 위해 스테인리스 스틸과 열수축튜브를 이용해 개량된 TDR계측선을 개발하여, 함수비에 대한 민감도를 높이고 노이즈를 줄이며 내구성을 향상시켜 TDR시스템의 현장적용성을 높였다. 개량된 TDR계측선을 이용하여 실내에서 포화도 변화실험과 아크릴모형실험을 수행하였으며, 실험결과 별도의 필터링 및 정량화 과정을 거치지 않은 초기 계측 그래프만으로 쉽게 포화, 불포화 및 건조구간을 파악할 수 있었다. 이후 대형 모형제방에 개량된 TDR센서를 설치하여 침투실험을 수행하였으며 그 결과, 실내시험과 같은 명확한 지하수 분포형태 파악이 가능하였으며, 침투 시간경과에 따른 각 구간의 지하수 분포변화를 파악할 수 있었고 손쉽게 모형제방의 침윤선을 작도할 수 있었다.

• 한국태양에너지학회 논문집
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• 제29권2호
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• pp.62-69
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• 2009

To reduce the building energy consumption, the major advanced nations are conducting actively many researches on so called a "self-sufficient building(or other words zero energy building)" which can support its required energy by itself. Given this background, KIER(Korea Institute of Energy Research) built full size test-bed of the zero energy solar house in early 2001, and has studied on the self-sufficient heating load up to now. We analyse the sensitivity between the heating load and the solar radiation gain according to the change the effective transmittance of windows. The authors classified 9 cases by solar transmittance of glass. The results demonstrate the solar radiation amount is 0.466 MWh from the eastern zone of Fl.,1(the first floor), 0.332 MWh from Fl.,2(the second floor), 1.194 MWh form the southern zone of F1., and 0.822 MWh from the southern zone of Fl.,2 on the case 1(each cases are classified by window types). On the case 9, the solar radiation amount is 3.127 MWh, 2.662 MWh, 8.799 MWh and 6.078 MWh from the same condition. For the Fl.,1, the amount of Heat Load that is saved per year ranged 10.5 to 48%, and the reduction was anywhere from 0.2 to 17.9% for Fl.,2.

• 한국재료학회지
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• 제17권8호
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• pp.437-441
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• 2007

Preparation and morphology control of $TiO_2$ nano powders for gas sensor applications are investigated. $TiO_2$ nanopowders with rutile and anatase structures were prepared by controlling the pH value of a precursor solution without any heat treatment. The mean particle size of $TiO_2$ powders were below 10nm. The prepared $TiO_2$ nano powders were hydrothermal treated by NaOH solution. The sample was washed in HCl solution. As a result and $TiO_2$ nanotubes were formed. The lengths of $TiO_2$ nanotube were $1{\mu}m$ and the diameters were 10nm. Crystal structure and microstructure of $TiO_2$ nanotube were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM). As-prepared $TiO_2$ nanotube powders have several advantages of nano particle size and high surface area and could be a prominent candidate for nano-sensors. The sensitivity of $TiO_2$ nanotube sensor was measured for toluene and NO in this study.

• Safety and Health at Work
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• 제9권2호
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• pp.149-158
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• 2018

Background: Work comfort studies have been extensively conducted, especially in the underground and meteorological fields resulting in an avalanche of recommendations for their evaluation. Nevertheless, no known or universally accepted model for comprehensively assessing the thermal work condition of the underground mine environment is currently available. Current literature presents several methods and techniques, but none of these can expansively assess the underground mine environment since most methods consider only one or a few defined factors and neglect others. Some are specifically formulated for the built and meteorological climates, thus making them unsuitable to accurately assess the climatic conditions in underground development and production workings. Methods: This paper presents a series of sensitivity analyses to assess the impact of environmental parameters and metabolic rate on the thermal comfort for underground mining applications. An approach was developed in the form of a "comfort model" which applied comfort parameters to extensively assess the climatic conditions in the deep, hot, and humid underground mines. Results: Simulation analysis predicted comfort limits in the form of required sweat rate and maximum skin wettedness. Tolerable worker exposure times to minimize thermal strain due to dehydration are predicted. Conclusion: The analysis determined the optimal air velocity for thermal comfort to be 1.5 m/s. The results also identified humidity to contribute more to deviations from thermal comfort than other comfort parameters. It is expected that this new approach will significantly help in managing heat stress issues in underground mines and thus improve productivity, safety, and health.

• Nuclear Engineering and Technology
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• 제47권1호
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• pp.47-58
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• 2015

Four recycling scenarios involving pyroprocessing of spent fuel (SF) have been investigated for a 600-MWe transmutation sodium-cooled fast reactor (SFR), KALIMER. Performance evaluation was done with code system REBUS connected with TRANSX and TWODANT. Scenario Number 1 is the pyroprocessing of Canada deuterium uranium (CANDU) SF. Because the recycling of CANDU SF does not have any safety problems, the CANDU-Pyro-SFR system will be possible if the pyroprocessing capacity is large enough. Scenario Number 2 is a feasibility test of feed SF from a pressurized water reactor PWR. Thefsensitivity of cooling time before prior to pyro-processing was studied. As the cooling time sensitivity of cooling time before prior to pyro-processing was studied. As the cooling time increases, excess reactivity at the beginning of the equilibrium cycle (BOEC) decreases, thereby creating advantageous reactivity control and improving the transmutation performance of minor actinides. Scenario Number 3 is a case study for various levels of recovery factors of transuranic isotopes (TRUs). If long-lived fission products can be separated during pyroprocessing, the waste that is not recovered is classified as low- and intermediate-level waste, and it is sufficient to be disposed of in an underground site due to very low-heat-generation rate when the waste cooling time becomes >300 years at a TRU recovery factor of 99.9%. Scenario Number 4 is a case study for the recovery factor of rare earth (RE) isotopes. The RE isotope recovery factor should be lowered to ${\leq}20%$ in order to make sodium void reactivity less than <7$, which is the design limit of a metal fuel.

• 생명과학회지
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• 제22권11호
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• pp.1515-1522
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• 2012

식물호르몬인 abscisic acid (ABA)는 식물의 비생물학적 스트레스의 적응과정에서 중요한 역할을 수행하고 있다. 또한 ABA는 종자휴면, 발아, 세포분열의 저해, 기공개폐와 같은 중요한 과정에 관여하고 있다. OsABF2(Oryza sativa ABRE Binding Factor2)는 벼에서 비생물학적 스트레스와 ABA 신호전달 과정에 양성적으로 관여하는 bZIP 형태의 전사인자이다. OsABF2 유전자의 발현은 ABA와 다양한 스트레스 처리에 의해 유도된다. 본 논문에서는 OsABF2 유전자를 과발현한 애기장대가 가뭄, 고염, 고온 상태에서의 생존율이 야생형보다 증가하는 것을 확인하였다. 또한 ABA가 존재하는 상황에서 OsABF2 유전자를 과발현한 애기장대의 발아율이 감소하는 것을 확인하였다. 이러한 결과로 미루어 OsABF2 유전자를 과발현한 애기장대는 비생물학적 스트레스에 대한 내성이 증가하고 ABA 감수성은 증가하는 것으로 확인되었다.

• Journal of Astronomy and Space Sciences
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• 제29권2호
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• pp.181-189
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• 2012

To broaden the understanding of classical Cepheid structure, evolution and atmospheres, we have extended our continuing secret lives of Cepheids program by obtaining XMM/Chandra X-ray observations, and Hubble space telescope (HST) / cosmic origins spectrograph (COS) FUV-UV spectra of the bright, nearby Cepheids Polaris, ${\delta}$ Cep and ${\beta}$ Dor. Previous studies made with the international ultraviolet explorer (IUE) showed a limited number of UV emission lines in Cepheids. The well-known problem presented by scattered light contamination in IUE spectra for bright stars, along with the excellent sensitivity & resolution combination offered by HST/COS, motivated this study, and the spectra obtained were much more rich and complex than we had ever anticipated. Numerous emission lines, indicating $10^4$ K up to ${\sim}3{\times}10^5$ K plasmas, have been observed, showing Cepheids to have complex, dynamic outer atmospheres that also vary with the photospheric pulsation period. The FUV line emissions peak in the phase range ${\varphi}{\approx}0.8-1.0$ and vary by factors as large as $10{\times}$. A more complete picture of Cepheid outer atmospheres is accomplished when the HST/COS results are combined with X-ray observations that we have obtained of the same stars with XMM-Newton & Chandra. The Cepheids detected to date have X-ray luminosities of log $L_X{\approx}28.5-29.1$ ergs/sec, and plasma temperatures in the $2-8{\times}106$ K range. Given the phase-timing of the enhanced emissions, the most plausible explanation is the formation of a pulsation-induced shocks that excite (and heat) the atmospheric plasmas surrounding the photosphere. A pulsation-driven ${\alpha}^2$ equivalent dynamo mechanism is also a viable and interesting alternative. However, the tight phase-space of enhanced emission (peaking near 0.8-1.0 ${\varphi}$) favor the shock heating mechanism hypothesis.

• Korean Chemical Engineering Research
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• 제46권5호
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• pp.903-914
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• 2008

본 연구는 ethylene oxide로부터 monoethylene glycol을 주제품으로 생산하는 상용화된 실제 공정의 생산 능력 증가시에 필요한 공정 모사와 에너지 절감을 위한 최적화 연구로서, 공정에 관여하는 다성분계의 기/액 상평형 거동을 NRTL-RK식으로 나타내고, 필요한 총 91개의 2성분계쌍의 상호작용 파라미터 값들로는 8개의 2성분계쌍에 대해서는 Aspen $Plus^{TM}$ 상용 모사기(Ver. 2006)에 내장된 값, 28개의 쌍에 대해서는 상평형 데이터를 문헌에서 조사하여 회귀분석하고 나머지 2성분계에 대해서는 모사기 내의 추산 기능을 이용하여 구한 값을 사용하였으며, 공정 모사 결과와 실제 공정 데이터와의 비교를 통해 상평형 계산의 정확성을 확인한 후, 모사기에 내장된 민감도 분석 기능을 사용하여 전체 에너지 소모량에 대한 각 장치의 민감도를 조사하여 적절한 조절변수를 선정하고 모사기 내에 내장되어 있는 순차적 2차 계획법에 의한 최적화 기능을 이용하여 공정 전체의 에너지 절약을 위한 최적화 작업을 수행하였다.

• 한국수소및신에너지학회논문집
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• 제30권6호
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• pp.490-498
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• 2019

The intermittent electric power supply of renewable energy can have extremely negative effect on power grid, so long-term and large-scale storage for energy released from renewable energy source is required for ensuring a stable supply of electric power. Power to gas which can convert and store the surplus electric power as hydrogen through water electrolysis is being actively studied in response to increasing supply of renewable energy. In this paper, we proposed the novel concept of hydrogen liquefaction process combined with pre-cooling process using the liquid air. It is that hydrogen converted from surplus electric power of renewable energy was liquefied through the hydrogen liquefaction process and vaporization heat of liquid hydrogen was conversely recovered to liquid air from ambient air. Moreover, Comparisons of specific energy consumption (kWh/kg) saved for using the liquid air pre-cooling was quantitatively conducted through the performance analysis. Consequently, about 12% of specific energy consumption of hydrogen liquefaction process was reduced with introducing liquid air for pre-cooling and optimal design point of helium Brayton cycle was identified by sensitivity analysis on change of compression/expansion ratio.

• Journal of Animal Science and Technology
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• 제46권5호
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• pp.841-848
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• 2004

살균된 우유에 오염된 Salmonella의 신속한 검출 방법을 공중 보건의 보호를 위하여 중요하다. RT-PCR 방법은 생균과 사균을 분별하여 검출할 수 있는 분자유전학적 방법이다. 본 연구의 RT-PCR 방법은 Salmonella의 type 1 fImbriae의 단량체 단백질을 암호화하는 fimA 유전자의 mRNA를 주형으로 하여 DNA를 증폭하는 방법으로서 활력이 있는 Salmonella를 검출할수 있기 위하여 개발되었다. RNA 시료를 RQRNase-free DNase로 처리하여 오염된 DNA를 파괴하여 RT-PCR 반응에서 주형으로서 DNA가 합성되는 것을 방지할 수 있었다. 이 RT-PCR 방법은 Salmonella 7균주를 검출하였으나 Escherichia coli, Shigella sonnei, Citrobacter freundii, 및 Klebsiella pneumoniae 는 검출하지 않았다. 우유 내에서 열처리된 $10^7/ml과 10^6/ml$ 세균수의 Salmonella는 검출되 었으나 $10^5{\sim}100/ml$는 검출되지 않았다. RT-PCR를 검출할 수 있는 활력이 있는 Salmonella의 최소 세균수는 100/ml이었다.