• 지구물리와물리탐사
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• 제13권1호
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• pp.61-68
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• 2010

인천시 강화군 석모도의 지열에너지 개발을 위하여 성부 파쇄대 해석을 위한 MT 탐사를 수행하였다. 또한, MT 탐사자료의 해석을 위해서, 지질조사와 심부시추공 물리검층을 함께 수행하였다. 석모도의 지질은 북쪽에는 백악기와 쥬라기에 관입된 화강암이, 남쪽에는 선캄브리아기의 편암류가 분포한다. 이 지역에서 지열징후는 편암류와 백악기의 화강암의 경계부에서 발견되었다. 심부파쇄대를 따른 영수의 순환에 의해 대상지역의 지온증가율은 $45^{\circ}C/km$ 이상으로 대한민국 평균보다 훨씬 높게 나타났다. MT 탐사자료의 2차원 빛 3차원 해석 결과, 전기전도도가 매우 높은 이상대가 동쪽으로 경사져서 지하 1.5 km 깊이까지 분포하는 것으로 나타났으며 이는 해수로 채워진 파쇄대로 해석되었다. 이 이상대를 목표로 시추한 결과 1280 m 심도에서 일일 4000 ton 이상, 온도 $70^{\circ}C$ 이상의 많은 양의 지열수를 개발하는데 성공하였다. 이 지열수의 화학적인 성분은 기존 시추공에서 발견된 지열수의 화학성분과 매우 유사하여 동일한 지열저류층, 즉, 동일한 지영저류층에서 생산되는 것으로 간주할 수 있을 것으로 판단하였다. 이러한 탐사결과를 기초로 2009년부터 한국지질자원연구원에서는 지열 열병합 발전을 위한 새로운 지열개발 프로젝트를 시작하였고 추가적인 MT 탐사와 탄성파 반사법 탐사, 이미 굴착되어 있는 20여개의 심부 시추공에 대하여 물리검층을 포함한 각종 시추공 조사 등이 수행 중이다.

• Bulletin of the Korean Chemical Society
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• 제30권9호
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• pp.2021-2026
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• 2009

Toluene, xylene and styrene are volatile organic solvents that are commonly used in mixtures in many industries. Because these solvents are metabolized and then excreted in urine, their urinary metabolites are thought to be biomarkers of occupational exposure to these solvents. Therefore, a simple, rapid, and yet reliable analytical method for determining the metabolites is required for accurate biological monitoring. In the present study, a simple and rapid HPLC-UV method was developed for the simultaneous determination of eight major metabolites of toluene, xylene and styrene: hippuric acid (HA), mandelic acid (MA), o-, m- and p-methylhippuric acids (o-, m- and p-MHAs), and o-, m- and p-cresols. A monolithic column was employed as the stationary phase and several conditions, including flow rate, composition of mobile phase and column temperature, were variables for the optimization of the chromatographic resolution. All eight metabolites were successfully resolved within 5 minutes in 10% aqueous ethanol containing 0.3% acetic acid and 1.6% $\beta$-cyclodextrin, using a flow rate gradient of 1.0 - 5.0 mL/min at 25 ${^{\circ}C}$. The performance of this method was validated by linearity, intra- and inter-day accuracy, and precision. The linearity was observed with correlation coefficients of 0.9998 for HA, 0.9999 for MA, 0.9989 for o-MHA, 0.9998 for m-MHA, 0.9991 for p-MHA, 0.9997 for o-cresol, 0.9998 for m-cresol, and 0.9986 for p-cresol. The intra- and inter-day precision of the method were less than 5.89% (CV) and the accuracy ranged from 92.95 to 106.62%. The validity was further confirmed by analysis of reference samples that were prepared by the inter-laboratory quality assurance program of the Korea Occupational Safety and Health Agency (KOSHA, Seoul, Korea). All measured concentrations of the analytes agreed with the certified values.

• Korean Chemical Engineering Research
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• 제49권6호
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• pp.829-834
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• 2011

난백에 함유된 lysozyme은 용균작용을 하며 ovalbumin은 면역계에서 항원으로써 역할을 한다. 난백분석에는 일반적으로 전기영동, 겔 투과 크로마토그래피, reversed-phase HPLC(RP-HPLC)를 사용하는데 신속한 분석을 위해 RPHPLC가 사용된다. HPLC 컬럼으로 C18 컬럼(Agilent, USA)을 사용하였다. 최적의 분리조건을 찾기 위해 이동상의 조성과 온도를 변화하였고 용량인자, 분리도를 계산하여 그 값을 비교하였다. 등용매 용리에서 acetonitrile(ACN), distilled ater(DW), trifluoroacetic acid(TFA)의 이동상 부피비를 30/70/0.1~60/40/0.1로 ACN 부피비를 10%씩 증가시키며 실험하였고 이 때 온도는 $20^{\circ}C$이었다. 기울기 용리에서는 ACN과 증류수의 비율을 20분 동안 10/90~60/40으로 증가시켰고 20, 30, $40^{\circ}C$의 온도변화를 주었다. 등용매 용리에서 이동상 조성이 50/50/0.1일 때 세 개의 피크로 분리되었고 개의 피크 중 첫 번째 피크가 lysozyme, 세 번째 피크가 ovalbumin임을 확인하였다. 기울기 용리에서는 온도가 $30^{\circ}C$일 때 네 개의 피크가 나왔으며 네 개의 피크 중 첫 번째 피크가 lysozyme, 세 번째 피크가 ovalbumin임을 확인하였다.

• Investigative Magnetic Resonance Imaging
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• 제19권2호
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• pp.76-87
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• 2015

Purpose: There is an ongoing search for a stent material that produces a reduced susceptibility artifact. This study evaluated the effect of manganese (Mn) content on the MRI susceptibility artifact of ferrous-manganese (Fe-Mn) alloys, and investigated the correlation between MRI findings and measurements of Fe-Mn microstructure on X-ray diffraction (XRD). Materials and Methods: Fe-Mn binary alloys were prepared with Mn contents varying from 10% to 35% by weight (i.e., 10%, 15%, 20%, 25%, 30%, and 35%; designated as Fe-10Mn, Fe-15Mn, Fe-20Mn, Fe-25Mn, Fe-30Mn, and Fe-35Mn, respectively), and their microstructure was evaluated using XRD. Three-dimensional spoiled gradient echo sequences of cylindrical specimens were obtained in parallel and perpendicular to the static magnetic field (B0). In addition, T1-weighted spin echo, T2-weighted fast spin echo, and $T2^*$weighted gradient echo images were obtained. The size of the low-intensity area on MRI was measured for each of the Fe-Mn binary alloys prepared. Results: Three phases of ${\alpha}^{\prime}$-martensite, ${\gamma}$-austenite, and ${\varepsilon}$-martensite were seen on XRD, and their composition changed from ${\alpha}^{\prime}$-martensite to ${\gamma}$-austenite and/or ${\varepsilon}$-martensite, with increasing Mn content. The Fe-10Mn and Fe-15Mn specimens comprised ${\alpha}^{\prime}$-martensite, the Fe-20Mn and Fe-25Mn specimens comprised ${\gamma}+{\varepsilon}$ phases, and the Fe-30Mn and Fe-35Mn specimens exhibited a single ${\gamma}$ phase. The size of the low-intensity areas of Fe-Mn on MRI decreased relative to its microstructure on XRD with increasing Mn content. Conclusion: Based on these findings, proper conditioning of the Mn content in Fe-Mn alloys will improve its visibility on MR angiography, and a Mn content of more than 25% is recommended to reduce the magnetic susceptibility artifacts on MRI. A reduced artifact of Fe-Mn alloys on MRI is closely related to the paramagnetic constitution of ${\gamma}$-austenite and/or ${\varepsilon}$-martensite.

• The Korean Journal of Ecology
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• 제21권5_3호
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• pp.713-721
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• 1998

The effects of artificial interference on the vegetation landscape in Mt. Nam of Seoul, Korea were clarified by analysing the distribution of vegetation landscape element and the number and size of patch depicted as a vegetation map in terms of landscape ecological principles. The effects of artificial interference on vegetation were also confirmed from the environmental gradient analysis on plant community extended from the lowland to the peak of that mountain. Vegetation landscape elements were divided into plantation and secondary forest in actual vegtation map. The ratio of plantation to secondary forest was higher in the lowland below mid-slope and the southern slope. Most afforested land were occupied by Robinia pseudoacacia and Populus tomentoglandulosa, Pinus rigida, P. koraiensis, Metasequoia glyptostroboides, Alnus hirsuta and so on are localy planted. In addition, projects to replace those afforested trees by P. densiflora as a kind of campaign for "Restoration of the one original feature of Mt. Nam" or to replace those tree species by planting young Abies holophylla or P. koraiensis under the mature afforested trees are also carried out in recent years. In cases of secondary forest, the southern slope was dominated by P. densiflora and the northern one by Q. mongolica. But the lowland of the northern slope is dominated by P. densiflora as the same as that in the southern slope. Vegetation landscape elements in Mt. Nam were much simplified comparing with that of suburban area around Seoul. The number of patches, which reflects the degree of diverse artificial interference was more in the lower area than in the upper area and more in the southern slope than in the northern one. On the other hand, the size of patch showed the antagonistic tendency to that of the number of patch. As a result of environmental gradient analysis, vegetation distribution in Mt. Nam was different from that in suburban area around Seoul. For example, Alnus japonica community, Zelkova serrata community, and Carpinus laxiflora community, which is established in mountain comparatively rare in artificial interference disappeared in Mt. Nam. As a result of analysis on vegetational succession in P. densiflora community and Q. mongolica community, both communities showed a tendency of retrogressive succession differently from that in control site located in suburban area around Seoul. In addition, species composition of P. densiflora and Q. mongolica communities in Mt. Nam were also different from those in Mt. Surak located around Seoul. It was interpreted that those results were originated from the environmental pollution and excessive arti ficial interferences.rferences.

• 한국재료학회지
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• 제3권3호
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• pp.261-271
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• 1993

4.5 Pb($Zn_{1/3}Nb_{2/3})O_3-40.5Pb(Ni_{1/3}Nb_{2/3})O_3$-55PZT와 PLZT(10/70/30, 11/60/40)를 경사조성으로 하여 경사기능 재료를 제조하였으며, 그 유전 특성과 압전 변형율 특성을 조사하였다. 경사기능재료는 A/B/A의 세층으로 성형하고 소결한 후 한 층을 연마해내어 제작하였다. 닥터블레이드용 슬립에는 acrylic계 유기 결합제가 34-36wt% 혼합되었으며, 건조 후 균열이 없는 양호한 thick film을 제조하였다. $1250^{\circ}C$, 2시간의 소성에 의해 경사기능화된 시편은 Nb와 La등의 조성 차이에 의한 구배를 이루었으며, 구배영역은 약 30${\mu}$m 정도였다. 경사기능재료에서 유전상수나 큐리온도롸 같은 유전특성은 조합한 조성층의 특성들사이의 값을 나타내었다. 인가 전압에 따른 변형율 특성은 단일 조성의 시편보다 현저하게 증가하였다. 실제로 경사기능 압전엑튜에이터를 제조한 결과 약 3${\mu}$m/100V 정도의 변위향을 나타내었다.

• 한국약용작물학회지
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• 제27권5호
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• pp.322-329
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• 2019

Background: Studies have suggested that the northern provinces of Gangwon-do are good sites for licorice (Glycyrrhiza uralensis Fisch.) cultivation in Korea, as they have similar temperatures to its original locations in northern China. However, poor growth and freezing injury are often reported in Korea. Therefore, it is necessary to reassess the domestic cultivation site of licorice. Methods and Results: To determine the optimum temperature for cultivating licorice, the growth, yield, and pharmacological characteristics of G. uralensis were assessed in a temperature gradient tunnel at Eumseong, Chungcheongbuk-do, Korea in 2017. Plant height increased until the temperature rose to $5.9^{\circ}C$ above the local external temperature. Yield (㎏/10a) increased by 46.9% when the growing temperature was $1.5^{\circ}C$ to $3.0^{\circ}C$ (T2) above the external temperature and by 72.6% when the growing temperature was $3.0^{\circ}C-4.5^{\circ}C$ (T3) above the external temperature. However, a difference of $4.5^{\circ}C-5.9^{\circ}C$ (T4) above the external temperature, decreased the yield by 9.8% compared to that at T2. The glycyrrhizin content of G. uralensis roots in each temperature band was 0.72%, 0.53%, 0.91%, and 0.84% (T1, T2, T3, T4), these differences appear to result form individual plant variation rather than growth temperature. Conclusions: Based on the results of this study, we estimate that the temperature-based optimum cultivation site for G. uralensis in Korea is the south central region, rather than the northern province of Gangwon-do. Improvement in growth and yield maybe observed if the plantations in the central Jecheon (Chungcheongbuk-do, Korea) are expanded into the south central region.

• Geomechanics and Engineering
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• 제17권4호
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• pp.343-354
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• 2019

The present study demonstrates the application of seismic petrophysics and amplitude versus angle (AVA) forward modeling to identify the reservoir fluids, discriminate their saturation levels and natural gas composition. Two case studies of the Lumshiwal Formation (mainly sandstone) of the Lower Cretaceous age have been studied from the Kohat Sub-basin and the Middle Indus Basin of Pakistan. The conventional angle-dependent reflection amplitudes such as P converted P ($R_{PP}$) and S ($R_{PS}$), S converted S ($R_{SS}$) and P ($R_{SP}$) and newly developed AVA attributes (${\Delta}R_{PP}$, ${\Delta}R_{PS}$, ${\Delta}R_{SS}$ and ${\Delta}R_{SP}$) are analyzed at different gas saturation levels in the reservoir rock. These attributes are generated by taking the differences between the water wet reflection coefficient and the reflection coefficient at unknown gas saturation. Intercept (A) and gradient (B) attributes are also computed and cross-plotted at different gas compositions and gas/water scenarios to define the AVO class of reservoir sands. The numerical simulation reveals that ${\Delta}R_{PP}$, ${\Delta}R_{PS}$, ${\Delta}R_{SS}$ and ${\Delta}R_{SP}$ are good indicators and able to distinguish low and high gas saturation with a high level of confidence as compared to conventional reflection amplitudes such as P-P, P-S, S-S and S-P. In A-B cross-plots, the gas lines move towards the fluid (wet) lines as the proportion of heavier gases increase in the Lumshiwal Sands. Because of the upper contacts with different sedimentary rocks (Shale/Limestone) in both wells, the same reservoir sand exhibits different response similar to AVO classes like class I and class IV. This study will help to analyze gas sands by using amplitude based attributes as direct gas indicators in further gas drilling wells in clastic successions.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 추계학술대회 논문집 학회본부
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• pp.372-375
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• 1988

The III-V ternary alloy semiconductor $In_{l-x}Ga_{x}As$ were grown by the temperature Gradient of $0.60{\leq}x{\leq}0.98$. The electrical properties were investigated by the Hall effect measurement with the Van der Pauw method in the temperature range of $90{\sim}300K$. $In_{l-x}Ga_{x}As$ were revealed n-type and the carrier concentration at 300K were in the range of $9.69{\times}10^{16}cm^{-3}{\sim}7.49{\times}10^{17}cm^{-3}$. The resistivity was increased and the carrier mobility was decreased with increasing the composition ratio. The optical energy gap determined by optical transmission were $20{\sim}30meV$ lower than theoretical valves on the basis of absorption in the conduction band tail and it was decreased with increasing the temperature by the Varshni rule. In the photoluminescence of undoped $In_{l-x}Ga_{x}As$ at 20K, the main emission was revealed by the radiative recombination of shallow donor(Si) to acceptor(Zn) and the peak energy was increased with increasing the composition, X. The diffusion depth of Zn increases proportionally with the square root of diffusion time, and the activation energy for the Zn diffusion into $In_{0.10}Ga_{0.90}As$ was 2.174eV and temperatures dependence of diffusion coefficient was D = 87.29 exp(-2.174/$K_{B}T$). The Zn diffusion p-n $In_{x}Ga_{x}As$ diode revealed the good rectfying characteristics and the diode factor $\beta{\approx}2$. The electroluminescence spectrum for the Zn-diffusion p-n $In_{0.10}Ga_{0.90}As$ diode was due to radiative recombation between the selectron trap level(${\sim}140meV$) and Zn acceptor level(${\sim}30meV$). The peak energy and FWHM of electroluminescence spectrum at 77K were 1.262eV and 81.0meV, respectively.

• 한국산림과학회지
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• 제107권2호
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• pp.113-125
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• 2018

우리나라의 아고산대는 기후변화에 지역적 취약성을 띄는 지역으로, 아고산대의 산림식생은 기후변화에 따른 영향을 관찰할 수 있는 중요한 기초지표 중 하나이다. 본 연구는 지리산 아고산대의 기후변화 취약수종 분포지의 산림식생을 대상으로 하여 식물사회학적 식생 유형 및 희귀-특산식물 분포 특성에 대해 구명하였다. 2015년 3월부터 10월까지 37개소에서 식생조사를 실시하였고, 식물사회학적 식생유형 분류를 통해 종조성을 파악하고, 종의 우점도를 파악하기 위해 중요치를 이용하여 식생유형별 층위구조를 분석하였다. 그 결과 식생유형분류체계는 8개 종군유형과 5개의 식생단위로 구분되었다. 산림청 지정 특산식물은 9분류군, 희귀식물은 17분류군이 출현하였고, 북방계식물의 비율은 41.2%이며, 식생단위별 해발고도가 증가함에 따라 희귀-특산식물도 함께 증가하는 것으로 나타났다. 중요치 분석 결과, 구상나무는 모든 식생단위에서 평균상대우점치가 높게 나타났다. 또한 층위별로 보았을 때 식생단위 1을 제외한 단위들에서는 신갈나무, 당단풍나무 등의 수종과 경쟁관계에 놓여 있는 것으로 판단되었다. 본 연구의 결과는 기후변화로 인한 아고산대 산림식생의 변화를 이해하기 위한 기초 자료 뿐만 아니라 식생학적 접근을 통한 장기 모니터링의 기초지표로 활용될 것으로 판단되었다.