• 생태와환경
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• 제47권2호
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• pp.127-134
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• 2014

본 연구는 안정동위원소 분석방법을 적용하여, 호소내 식물플랑크톤 성장에 영향을 미치는 외부 오염원의 기원을 추정함으로써, 효율적인 수질 관리 및 수생태계 기능해석을 제공하기 위하여 연구하였다. POC, PN, Chl. a, 탄소 안정동위원소비 및 질소 안정동위원소비의 자료로 유추해 보았을 때, 팔당댐, 남한강, 북한강 지역에 비해서 경안천 지역에서 계절에 따른 유기물의 기원 변동이 뚜렷하게 관찰되고 있다. 유입량 및 강우량이 많은 시기인 7, 8월경에 입자성 유기물의 기원이 자생기원 유기물보다는 외부기원 유기물이 높은 영향을 미치는 것으로 여겨진다. 한강 유역에서 입자성 유기물의 탄소 및 질소 안정동위원소비를 이용한 유기물 기원 연구는 적용가능 할 것으로 여겨지며, 추후 유역 오염원의 대표값(end member)의 지속적인 조사를 통하여 자료구축이 이루어져야 할 것이다.

• 한국축산식품학회지
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• 제33권1호
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• pp.39-44
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• 2013

Origin authenticity of the animals used as food has always been a major concern to consumers around the world. In the past twenty years, a stable isotope ratio has been used for origin authentication. In this study, pork samples, both local and imported, were collected from the major markets from all around South Korea and analyzed for stable isotope ratios of nitrogen (${\delta}^{15}N$‰) and carbon (${\delta}^{13}C$‰), using Isotope Ratio Mass Spectrometry (IR-MS). A total of 599 samples with 335 Korean and 264 imported from 13 countries within America and Europe were investigated in accordance to the standard established methods for isotope ratio analysis. The results showed a significant variation related to the origin of the samples, explaining the difference in the feeding styles of the pork in each country. The stable isotope ratio values of carbon (${\delta}^{13}C$‰) were found in the decreasing order of: America ($-15.55{\pm}1.01$‰)>Korea ($-19.62{\pm}0.89$‰)>Europe ($-24.79{\pm}1.35$‰). Canada was having ${\delta}^{13}C$ ratio of $-22.87{\pm}0.92$‰, which is very low in the region of America and very close to Europe (-23.78 to -27.17‰). For nitrogen ${\delta}^{15}N$‰ the order was: America ($4.92{\pm}0.71$‰)>Europe ($4.54{\pm}0.66$‰)>Korea ($3.69{\pm}0.54$‰), with a slight variation among countries in each region studied. From the results it was concluded that the stable isotope ratio of the pork samples from different countries provide enough information about the origin and is therefore a potential tool which can be employed for origin authentication.

• 생태와환경
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• 제40권1호
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• pp.93-102
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• 2007

남한강과 북한강 상류지역에 위치한 11개 하천을 대상으로 강우 시 발생하는 탁수의 생지화학적 특성을 조사하였다. 강우 시 하천에서 POM와 DOM의 유출특성은 유량변동에 따라 다르게 나타났으며, 특히 POM의 유출은 하천의 유역특성과 밀접한 관련이 있는 것으로 나타났다. 강우의 영향에 따라 DOM내 용존 부식물질(Humic substance)의 비율을 반영하는 SUVA값이 증가하였고, 이는 하천유역으로부터 난분해성유기물의 유입이 증가함을 의미한다. 강우 시 발생된 탁수의 생지화학적 특성을 분석한 결과 농경지역에서 유출되는 탁수가 삼림지역으로부터 유출되는 탁수보다 안정탄소동위원소비가 약 $1{\sim}2%_{\circ}$정도 높게 나타났다. 이는 상대적으로 안정탄소동위원소비가 높은 $C_4$계열의 작물이 농경지역에서 우세한 경우 또는 삼림지역으로부터 유출된 탁수에서 주로 $C_3$계열의 식물체의 리그닌(Lignin)의 함량이 높기 때문이다. 유기물의 기원에 따라 Isotopic mass balance를 적용한 결과 농경지나 경작지의 비율이 높아질수록 $C_4$계열 작물의 기여도가 높아지고 이에 따라 탄소동위원소비가 증가하는 경향을 보였다. 본 연구결과를 바탕으로 안정탄소동위원소를 이용한 탁수 연구는 유기물의 기원특성을 연구하는데 유용한 지표가 될 수 있다.

• 오토저널
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• 제13권2호
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• pp.103-111
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• 1991

To determine the effects of microstructure on the fatigue crack propagation behavior in SM45C steel, experimental investigations have been carried out with the specimens of different grain sizes and different spacings between the Fe$_{3}$C particles. Fatigue and tensile tests were conducted and the quantitative analysis of the relations between the threshold stress intensity range and grain size, interparticle spacing and yield stress were carried out. Some of the conclusions obtained are as follows; (1) .DELTA.K$_{th}$ was observed to increase with grain size and the spacing between the Fe3C particles. (2) In both pearlite and spheroidite microstructures, .DELTA.K$_{th}$ was increased when yield stress was decreased.sed.

• 환경위생공학
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• 제13권2호
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• pp.57-65
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• 1998

In this research, Effect of C/N ratio on nutrient removal in intermittently aerated activated sludge system(IAASS) was investigated with dormitary, building and swine wastewater. Three types (2-stage, 4-stage, modified) of IAASS were operated. Time interval of aeration/nonaeration in IAASS was 1hr/1hr. In treatment of Dormitary wastewater(BOD/T-N ratio : 4.4), Building wastewater (BOD/T-N ratio : 3.14) and swine wastewater(BOD/T-N ratio : 3.84), Nitrogen removal efficiency of 80, 70 and 90.4% was achieved, respectively. Nitrogen removal in IAASS was a great influenced on influent C/N ratio, efficient nitrogen removal was achieved at BOD/T-N ratio over 4. In IAASS operation, $\Delta $BOD mg/L/$\Delta $ nitrogen mg/L ratio was about 4-6. Simultaneous removal of organic, nitrogen and phosphorus in IAASS can achieved. And influent organic was efficiently utilized in denitrification. IAASS could be one of the best alternative process for the retrofit of conventional activated sludge system for the removal of nutrients.

• 한국재료학회지
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• 제7권12호
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• pp.1077-1082
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• 1997

TiN은 기상반응법으로 티타늄판과 질소가스의 질화반응에 의해 제조되었다. $\delta$-TiN은 약 1100-140$0^{\circ}C$의 온도 범위에서만 형성되는데 반해, 110$0^{\circ}C$이하의 온도에서는 $\varepsilon$-TiN 상도 관찰할 수 있었다. $\delta$-TiN의 미소정도값은 3000$\pm$300kg/m$m^2$였고, 격자상수는 0.4226$\mu\textrm{m}$였다. 가스의 유동속도가 0.7$\ell$/min의 속도이하에서는 확산과정에 의해 지배됨을 알 수 있었다. 활성화에너지가 110$0^{\circ}C$이상에서는 67.6Kcal/mol이었고 110$0^{\circ}C$이상에서는 13.9Kcal/mol이었던 것으로 보아 반응메커니즘이 110$0^{\circ}C$를 기점으로 변한다는 것을 명백히 관찰할 수 있었다. 그리고 증착속도가 확산과정에 의해 지배되는 영역에서 TiN의 증착속도는 전체 유량의 제곱근에 비례하였다.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2003년도 High Temperature Superconductivity Vol.XIII
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• pp.41-41
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• 2003

• The Korean Journal of Physiology and Pharmacology
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• 제17권1호
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• pp.51-56
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• 2013

Many intracellular proteins and signaling cascades contribute to the sensitivity of N-methyl-D-aspartate receptors (NMDARs). One such putative contributor is the serine/threonine kinase, protein kinase C (PKC). Activation of PKC by phorbol 12-myristate 13-acetate (PMA) causes activation of extracellular signal-regulated kinase (ERK) and promotes the formation of new spines in cultured hippocampal neurons. The purpose of this study was to examine which PKC isoforms are responsible for the PMA-induced augmentation of long-term potentiation (LTP) in the CA1 stratum radiatum of the hippocampus in vitro and verify that this facilitation requires NMDAR activation. We found that PMA enhanced the induction of LTP by a single episode of theta-burst stimulation in a concentration-dependent manner without affecting to magnitude of baseline field excitatory postsynaptic potentials. Facilitation of LTP by PMA (200 nM) was blocked by the nonspecific PKC inhibitor, Ro 31-8220 ($10{\mu}M$); the selective $PKC{\delta}$ inhibitor, rottlerin ($1{\mu}M$); and the $PKC{\varepsilon}$ inhibitor, TAT-${\varepsilon}V1$-2 peptide (500 nM). Moreover, the NMDAR blocker DL-APV ($50{\mu}M$) prevented enhancement of LTP by PMA. Our results suggest that PMA contributes to synaptic plasticity in the nervous system via activation of $PKC{\delta}$ and/or $PKC{\varepsilon}$, and confirm that NMDAR activity is required for this effect.

• 대기
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• 제20권3호
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• pp.261-271
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• 2010

Carbon isotopic compositions of the YC-2 stalagmite in Yongcheon Cave were analyzed to delineate paleoclimatic variations near Korean peninsula for the past historical period. The YC-2 stalagmite is about 68 mm long and annual growth laminae are distinctively identified. Because the number of growth laminae is at least 242, the stalagmite can be estimated to be at least 241 years old. At about 15 mm from the bottom, one thick brown growth lamina is observed, and this lamina was likely to have been formed when the stalagmite ceased to grow, making the hiatus. High resolution, carbon isotope data indicate past fluctuations of East Asia monsoonal intensity (intimately related to the amount of precipitation). Based on the carbon isotope trend, the stalagmite can be divided into three stages (Stages I, II and III). The highest carbon isotopic compositions of Stage I (${\delta}^{13}C$=-3.3~0.4‰, PDB) indicate that the stalagmite grew during the Little Ice Age when cold and dry climate prevailed with less vegetation. Stage II is characterized by a transitional period from cold and dry to warm and wet climate with a increasing trend of carbon isotopic compositions (${\delta}^{13}C$=-9.6~-0.6‰) and this period indicates the weakening of the Little Ice Age climate. This decreasing trend also suggests that Little Ice Age was terminated near middle 1870's around Korean peninsula. Relatively low carbon isotopic compositions during Stage III (${\delta}^{13}C$=-11.0~-8.0‰) indicates that the climate was changed to warm and wet conditions which are similar to the present.

• Journal of the Korean Wood Science and Technology
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• 제42권1호
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• pp.13-19
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• 2014

국내의 주 생산 수종인 잣나무 $90{\times}90mm$ 각재의 적정한 열처리 조건을 찾기 위해 3가지 열처리 스케줄을 적용하여 재색과 물성에 미치는 영향을 연구하였다. 1차 열처리시 온도는 $170^{\circ}C$와 $190^{\circ}C$, 시간은 예비가열시간 1시간을 포함하여 9시간과 13시간을 적용하였다. 2차와 3차 열처리는 모든 공시 각재에 동일하게 $190^{\circ}C$-9시간을 적용하였다. 열처리 횟수가 증가할수록 백색도 $L^*$는 직선적으로 감소하였으며 표준편차도 감소하였다. 열처리 횟수가 증가할수록 색차 ${\Delta}E^*$는 직선적으로 증가하였으며, 표준편차가 커지는 경향이 있었다. 알려진 바와 달리 열처리 시편의 평균 종압축강도가 무처리 시편보다 9% 높았다. 항팽윤율과 중량증가율을 측정하여 열처리 시편의 치수안정성이 무처리보다 크게 증가하였음을 보였다.