• 인간식물환경학회지
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• 제21권6호
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• pp.485-492
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• 2018

This study aimed to develop and validate highly sensitive determination method of a prostaglandin ($PGE_1$, OP 1206) in human plasma by LC-MS/MS using column switching. Plasma stored at $-30^{\circ}C$ and treated with methanol effectively inhibited interferences synthesized post-sampling. Samples were added with internal standard and were separated by reversed-phase HPLC with a cycle time of 30min. The method was selective for OP 1206 and the regression models, based on internal standard, were linear across the concentration range 0.5-50 pg/mL with the limit of quantification of 0.5 pg/mL (limit of quantitation, LOQ) for OP 1206. The calibration curve of OP 1206 standards spiked in five individual plasma samples was linear ($r^2=0.9999$). Accuracy and precision at the concentrations of 0.5, 1.5, 5.0 and 40 pg/mL, and at the lower LOQ of 0.5 pg/mL were excellent at 20%. OP120 < 6 was stable in plasma samples for at least 24 hours at room temperature, 24 hours frozen at $-70^{\circ}C$, 24 hours in an auto sampler at $6^{\circ}C$, and for two freeze/unfreezing cycles. The validated determination method successfully quantified the concentrations of OP 1206 in plasma samples from simulated administrating a single $5{\mu}g$ OP 1206 formulation. Thus, this novel LC-MS/MS technique for drug separation, detection and quantitation is expected to become the standard highly-sensitive detection method in bioanalysis and to be applied to many low dose pharmaceutical products.

• 한국산학기술학회논문지
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• 제19권4호
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• pp.1-7
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• 2018

화석연료를 사용하는 내연기관에서 배출되는 가스는 환경오염, 지구온난화와 인체에 유해하여 많은 사회적인 문제를 야기시키고 있다. 최근에는 신재생에너지의 수요가 증가하고 있으며, 정부의 정책적인 지원과 연구개발 또한 활발하다. 가정에서 많이 사용되는 태양열에너지 시스템의 집열부는 열매체로 프로필렌글리콜 부동액이 물과 50% 고정된 값으로 혼합되어 영하온도에서도 집열부에 열을 전달한다. 그러나 집열부 내의 열매체에 누수가 발생되면 태양열시스템 특성상 보충수를 태양열 집열부에 공급하는데, 이로 인하여 보충수 내의 급수로 인하여 부동액 농도가 낮아지게 된다. 이에 따라 태양열 집열부위의 온도가 저하되어 동파를 야기하게 되는데 태양열에너지 시스템 정비 보수를 위해서 비용 부담이 증가하여 많은 문제점을 증가시킨다. 이 연구는 태양열에너지 시스템에 발생되는 동파 방지를 위하여 온도 저하에 따라 자동으로 부동액 농도를 제어가능한 장치를 개발하는 것이다. 물 성분이 프로필렌글리콜보다 전기전도도가 크며, 온도가 저온으로 내려갈수록 저항값이 증가하였다. 프로필렌글리콜 농도 제어 목표값 40, 50 및 60% 값은 39.6, 50.7 및 60.1%의 프로필렌글리콜 농도값으로 보정을 통하여 제어를 해야 한다.

• 한국도로학회논문집
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• 제8권3호
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• pp.163-172
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• 2006

본 연구에서는 원유 정제과정에서 발생되는 산업부산물인 황을 주성분으로 폴리머 성분의 첨가제를 혼합하여 개발된 개질 첨가제인 SPC(Sulfur Polymer Cement;가칭)를 비율별 (0%, 10%, 30%, 50%)로 첨가하여 개질 아스팔트 바인더 및 혼합물의 실내 물성 평가를 수행하였다. 개질 아스팔트 바인더의 특성을 평가하기 위해 수퍼페이브 바인더 시험법을 이용하여 아스팔트 바인더의 PG(Performance Grade) 등급을 분류하고 온도에 따른 특성을 파악하였다. 또한 개질 아스팔트 혼합물의 피로균열 및 저온균열 특성을 평가하기 위해 $10^{\circ}C$ 및 $-10^{\circ}C$에서 간접인장실험(Indirect Tensile Test)을 수행하였으며, 소성변형에 대한 저항성을 평가하기 위해 휠트랙킹 실험을 수행하였다. 실험 결과, 개질 첨가제인 SPC의 첨가 비율이 증가할수록 소성 변형에 대한 저항성이 증가하는 것으로 나타났으며, 저온 균열 저항성을 증가시킬 수 있는 잠재성을 보여주었다. 그러나 피로균열 SPC는 피로균열 저항성 향상에는 큰 효과가 없는 것으로 나타났다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.228-231
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• 2004

The purpose of this study evaluates possibilities of waste phosphogypsum into concrete by steam curing admixture. The waste phosphogypsums were classified into 4 forms(Dihydrate, $\beta-Hemihydrate$, III-Anhydrite and II-Anhydrite) which were changed to in low temperature of calcination. Also, various admixtures were made of waste phosphogypsum(PG) and pozollanic fine powderers (Fly-ash, Blast Furnace Slag), and the basic properties of the cement mortars incorporating with these admixtures were examined and analyzed under a verity of experimental conditions. As a result, III-Anhydrite, these is similar to II-Anhydrite from compressive strength and are great in the effect of strength improvement. also, it was proved that specimens made on type III-Anhydrite of waste phosphogypsum and blast furnace slag increased on the compressive strength of cement mortar. Therefore, III-Anhydrite phosphogypsum calcined at lower temperature could be used as steam curing admixture for concrete 2th production.

• 한국농공학회논문집
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• 제62권3호
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• pp.29-38
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• 2020

Since some warm-mix asphalt (WMA) concretes were known to show poorer rut resistance than the hot-mix asphalt (HMA) concretes, many studies were performed in efforts of improving its performance at high temperature. The reason is assumed to be due to the moisture remaining in aggregates dried at lower temperature. Therefore, not only the rut resistance, the crack resistance of WMA concrete was also in question. In this study, fatigue life of WMA concrete was evaluated in comparison with HMA using 3-point bending (3PB) beam test. The asphalt mixtures were prepared based on Korean mix-design guide using a 13 mm dense-graded aggregate and 6 binders; two HMA binders and four WMA binders. By 3PB fatigue test, normal (unmodified) and polymer-modified WMA concretes were evaluated in comparison with normal and polymer-modified HMA concretes at a low temperature (-5℃). The results showed that most of WMA concretes showed longer fatigue lives than HMA concretes, even though the same PG binders were used for HMA and WMA. This result indicates that the WMA concretes have stronger resistance against fatigue cracking than HMA at the low temperature, and this result is in contrast to the high-temperature performance test.

• 한국도로학회논문집
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• 제18권6호
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• pp.97-104
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• 2016

OBJECTIVES : The objective of this research is to develop additives for the modification of Solvent DeAsphalting Residue (SDAR) to be used as pavement materials, and evaluate the performance of asphalt mixture manufactured using the SDAR modified by developed additives. METHODS : The SDAR generally consists of more asphaltenes and less oil components compared to the conventional asphalt binder, and hence, the chemical/physical properties of SDAR are different from that of conventional asphalt binder. In this research, the additives are developed using the low molecular oil-based plasticizer to improve the properties of SDAR. First, the chemical property of two SDARs is analyzed using SARA (saturate, aromatic, resin, and asphaltene) method. The physical/rheological properties of SDARs and SDARs containing additives are also evaluated based on PG-grade method and dynamic shear-modulus master curve. Second, various laboratory tests are conducted for the asphalt mixture manufactured using the SDAR modified with additives. The laboratory tests conducted in this study include the mix design, compactibility analysis, indirect tensile test for moisture susceptibility, dynamic modulus test for rheological property, wheel-tracking test for rutting performance, and direct tension fatigue test for cracking performance. RESULTS : The PG-grade of SDARs is higher than PG 76 in high temperature grades and immeasurable in low temperature grades. The dynamic shear modulus of SDARs is much higher than that of conventional asphalt, but the modified SDARs with additives show similar modulus compared to that of conventional asphalt. The moisture susceptibility of asphalt mixture with modified SDARs is good if, the anti-stripping agent is included. The performance (dynamic modulus, rutting resistance, and fatigue resistance) of asphalt mixture with modified SDARs is comparable to that of conventional asphalt mixture when appropriate amount of additives is added. CONCLUSIONS : The saturate component of SDARs is much less than that of conventional asphalt, and hence, it is too hard and brittle to be used as pavement materials. However, the modified SDARs with developed additives show comparable or better rheological/physical properties compared to that of conventional asphalt depending on the type of SDAR and the amount of additives used.

• 한국약용작물학회지
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• 제23권3호
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• pp.231-236
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• 2015

Skin anti-wrinkle activities of the stems and leaves of Abeliophyllum distichum Nakai were evaluated by the extracts obtained from various extraction processes such as using hot water at $100^{\circ}C$, 70% ethanol at $85^{\circ}C$, and 70% ethanol with ultrasonication at $60^{\circ}C$ The ultrasonicated extract showed 95.62% of the highest cell viability in addition of $0.3mg/m{\ell}$ of the extracts into the normal human fibroblast cell, CCD-986sk. For antioxidant activities, the extracts using ultrasonicated extract showed the highest DPPH free radical scavenging as 80.27%, followed by 75.88% and 62.44% for the extracts using ethanol extract and water extract. The ultrasonicated extract also showed the highest elastase inhibition activity as 25.32%, compared to ethanol extract and water extract based method at 22.01% and 12.88%, respectively. MMP-1 production was most effectively decreased down to $2908.1pg/m{\ell}$ with ultrasonicated extract while $6640.8pg/m{\ell}$ with water extract and $3609.3pg/m{\ell}$ with ethanol extract, in addition of $0.3mg/m{\ell}$. Collagen production was increased up to $154.7ng/m{\ell}$ in addition of ultrasonicated extract, and followed by $121.4ng/m{\ell}$ and $31.2ng/m{\ell}$ for ethanol extract and water extract, respectively. These results indicate that the ethanol extract should have skin anti-wrinkling activities and can be improved by the ultrasonication process that high energy input elute more amounts of bioactive substances eluting more amounts of bioactive substances from the high energy input of ultrasonication.

• Journal of Pharmaceutical Investigation
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• 제23권3호spc1호
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• pp.9-18
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• 1993

Sugar spheres loaded with melatonin (MT) were coated with $Aquacoat^{\circledR}$ to control the release rate of MT over 8 hours. A zero-order release pattern over 8 hours was obtained with 20% coating on 8-10 mesh beads in USP basket dissolution studies. MT in 20% coated beads was quite stable at room temperature with less than 5% MT degraded during 6 months' storage. Dissolution profiles were also unchanged after 6 months. An oral preparation containing MT-loaded uncoated beads for immediate release and 20% coated beads with $Aquacoat^{\circledR}$ for controlled release over 8 hours was evaluated in six human subjects. When total 0.5 mg MT as low dose (immediate release portion of MT, 0.1 mg) was administered to four subjects, average peak plasma MT concentration was reached at about 600 pg/ml and maintained at about 10 pg/ml over 8 hours. Plasma MT concentration-time profiles were similar in shape to computer-simulated profiles. However, maximal plasma MT concentrations were three times greater compared to computer simulated curve. These results suggest that MT dose, ratio of immediate and controlled release MT, and pharmacokinetic parameters selected are adjusted to mimic endogenous MT concentration-time curve. In another study, 0.2 mg MT having 10% of immediate release portion and 80% controlled release portion produced plasma MT concentration-time curve which is more similar to endogenous profiles. A low bioavailability (<20%) may result from extensive first pass metabolism and remaining amounts of MT from controlled beads. A good correlation between plasma MT concentration and urinary excretion rate of 6-sulphatoxymelatonin (6-STMT), a major metabolite of MT was observed. As plasma MT concentration increased, urinary excretion rate of 6-STMT increased concomitantly. The linear relation between plasma MT and urinary excretion rate of 6-STMT was statistically significant. This result suggests that urinary 6-STMT may be used as an index of circadian rhythms of MT in humans.

• 한국대기환경학회지
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• 제18권3호
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• pp.183-192
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• 2002

Concentrations of $\alpha$- and ${\gamma}$-hexachlorocyclohexane (HCH) were measured in ambient air samples at a two week intervals between July 1999 and February 2000 at Ansung, Kyonggi province. Their concentration levels averaged at 78 ($\alpha$-HCH) and 18 pg/m$^3$(${\gamma}$-HCH). Although the use of HCHs was ceased in South Korea since 1979, their residues are still present in air even after nearly 20 years. Given the composition of the two main HCH pesticide formulation (technical HCH antral lindane), the $\alpha$/${\gamma}$-HCH ratio in air is a useful indicator on the regional scale. The moderately low $\alpha$/${\gamma}$-HCH ration in this study indicates previous usage of both technical HCH and lindane. The relationship of temperature with gas-phase partial pressures was also examined using the Clausius-Clapeyron equation. Slopes generated by linear regression analysis between partial pressure (In P) and 1/T were considerably steep thor HCHs. It is thus suggested that their concentrations are controlled by re-volatilization processes from surfaces in the local surroundings of the sampling site.

• 환경생물
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• 제32권3호
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• pp.168-175
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• 2014

본 연구는 2012년 3월 저수온기 동해연안의 10개 정점에서 식물플랑크톤의 군집구조를 세포의 크기에 따라 구분하여 조사하였다. 식물플랑크톤의 총 개체수는 $3.4{\times}10^6{\sim}7.6{\times}10^6cells\;L^{-1}$, 탄소량은 $0.0^8{\times}10^8{\sim}6.3{\times}10^8pg\;L^{-1}$로 나타났다. 개체수를 기반으로 생물량을 보았을 때, 극미소플랑크톤의 비율이 미세 미소 플랑크톤보다 높았다. 그러나 탄소량을 기반으로 하는 생물량을 보았을 때, 극미소플랑크톤은 세포 크기가 작아 기여도가 미미하였고, Coscinodiscus속과 같이 크기가 큰 종들은 기여도가 높았다. 이와 같이 식물플랑크톤의 생물량을 정확하게 파악하기 위해서는 다양한 관점으로 여러 항목을 조사할 필요성이 있는 것으로 나타났다. 식물플랑크톤의 군집 구조를 확인한 결과, 총 10개 정점 중에 8 정점에서 극미소플랑크톤이 우점하였다. 또한 8개 정점에서 미소플랑크톤의 개체수가 미세플랑크톤보다 높은 비율을 나타냈다. 미세 미소플랑크톤 중에서는 규조류의 비율이 95% 이상이었다. 극미소플랑크톤의 군집구조를 살펴보면, 5가지의 형태학적 특성이 다른 군집이 확인되었으며, 7개 정점에서 S type이 가장 우점한 것으로 나타났다. 본 연구를 통해 확인된 극미소플랑크톤이 차지하는 생태학적 기여도가 커 이들에 대한 연구가 꾸준히 수행되어야 하며, 이를 위하여 그들의 분류학적 체계 구축과 생리학적 특성 연구가 선행되어야 할 것으로 판단된다. 이와 같은 연구를 기반으로 향후, 변화하고 있는 동해연안에서 생물 군집 변화 현상을 규명할 수 있을 것이다.