• 암석학회지
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• 제18권4호
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• pp.315-336
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• 2009

경상분지 북동부 일대의 제3기 결정질 응회암에서 발달하는 미세균열의 빈도수, 길이 및 밀도에 대한 분포특성을 도출하였다. 포항시 흥해읍 지역에서 채취한 3개 암석시료의 수평면 상에서 발달하는 134조의 미세균열은 박편의 확대사진을 통하여 구별하였다. 채취지점의 고도를 달리하는 3개 암석시료에 대한 미세균열의 길이-빈도 히스토그램에 대한 형태의 변화성을 도출하였다. 히스토그램들의 분포형태는 암석시료의 고도와 비례하여 음의 지수함수의 분포형에서 대수-정규의 분포형으로 점변한다. 다른 암석시료보다 고도가 낮은 암석시료 1의 분포형태는 넓은 길이분포를 보여주며, 다른 암석시료에 비하여 평균길이와 중앙값, 그리고 표준 편차가 높은 것이 특징이다. 한편 이와 같은 분포특성은 하부 경상누층군의 퇴적암에서 발달하는 절리의 길이분포와 부합한다. $N0{\sim}10^{\circ}W$의 방향을 중심으로 하여 NW 및 NE의 양쪽 방향으로 갈수록 보다 길이가 짧은 미세균열의 출현빈도수는 증가하며, $N80{\sim}90^{\circ}W$ 및 $N80{\sim}90^{\circ}E$의 방향에서 각각 우세하다. 이러한 분포특성은 미세균열 조들 사이의 생성시기의 상대적인 차이 그리고 보다 짧은 미세균열의 신규 발생을 의미한다. 한편 $N60{\sim}70^{\circ}W$(최대길이:1.18 mm) 및 $N0{\sim}10^{\circ}W$(최대길이:0.80 mm)의 방향에서는 길이가 가장 긴 미세균열을 볼 수 있으며, 이러한 유형의 미세균열은 빈도수에 비하여 숫적으로 매우 제한적이다. 방향각($\theta$)-빈도수(N), 총길이($L_t$), 평균길이($L_m$) 및 밀도($\rho$)의 종합 분포도의 전 영역은 상관곡선의 형태에 의거, 5개의 구간으로 분류할 수가 있다. 분포도에서 밀도곡선은 서북서-동남동($N70{\sim}80^{\circ}W$), 남-북~북북동-남남서($N0{\sim}10^{\circ}W/N10{\sim}20^{\circ}E$), 동북동-서남서($N50{\sim}60^{\circ}E$) 그리고 거의 동-서($N80{\sim}90^{\circ}E$)의 방향에서 각각 5개의 뚜렷한 정점을 보여준다. 특히 단층의 주방향은 밀도가 높은 방향각과 부합한다. 결과적으로 밀도곡선의 이러한 분포형태는 기존의 연구에서 시사한 대표적인 최대 주응력 방향을 반영한다.

• 대한화학회지
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• 제42권3호
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• pp.306-314
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• 1998

Acetolactate synthase(ALS)는 박테리아, yeast, 그리고 고등 식물에서 가지를 가진 아미노산 Val, Leu, Ile의 생합성에 공통적으로 관여하는 필수적인 효소이다. 최근에 개발된 sulfonylurea, imidazolinone, triazolopyrimidine, 그리고 pyrimidyl-oxy-benzoate계 제초제들은 구조적으로 상호 유사성이 없음에도 불구하고 모두 ALS를 작용 표적으로 한다. Triazolopyrimidine(TP)계의 새로운 유도체들을 합성하여 보리의 ALS에 대해 저해활성을 측정하였다. 활성을 나타낸 저해제들의 $IC_{50}값은 3.2nM-0.62mM로 몇 개의 유도체는 뛰어난 활성을 보였다. 보리 ALS에 대해 triazolopyrimidine 유도체 TP4의 저해활성은 반응 시간이 증가함에 따라 증가하였고, 혼합형 저해유형을 보여주었다. TP4와 imidazolinone 제초제인 Cadre, 그리고 feedback 저해제인 Leu에 대한 dual inhibition 실험 결과 모두 평행한 kinetic pattern이 얻어져 이들 저해제의 결합 부위가 최소한 부분적으로 중복되는 부분이 있음을 시사했다. ALS의 Tyr의 변형은 TP4에 의한 저해 효과를 감소시키는 반면 Trp과 Cys 변형은 TP4의 결합에 영향을 나타내지 않았다.

• 분석과학
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• 제17권2호
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• pp.130-144
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• 2004

최근 A, B 공단지역 및 주변 지역의 대기오염문제가 중요한 이슈가 됨에 따라 이 지역의 대기 중 VOCs를 측정하였다. 시료는 air sampler를 사용하여 Carbotrap에 흡착시킨 후 열탈착시스템을 사용하여 탈착시켜 가스크로마토그래피/질량분석법(GC/MS)으로 분석하였다. 모든 휘발성유기화합물들은 좋은 크로마토그래프 성질을 보였고 GC/MS-SIM에서 높은 감도를 보였다. 검출한계는 0.01-0.1 ppt(v/v)를 검량선의 직선성은 0.995이상을 보였다. 분석 결과 benzene, toluene, ethylbenzene, xylene, n-hexane, fluorotrichloromethane, carbon tetrachloride, 1,2-dichloroethane, 1,1,1-trichloroethane, trichloroethylene, tetrachloroethylene, styrene, 1,3,5-trimethylbenzene, 1,2,4-trimethylbenzene, sec-butylbenzene, naphthalene 등 16개의 VOCs가 검출되었으며, 평균 농도로서 0.81, 5.02 1.30, 3.0, 0.81, 37.9, 0.07, 0.15, 0.15, 0.79, 0.06, 0.33, 0.03, 0.12, 0.23 그리고 0.35 ppb(v/v)으로 나타났다. 전반적으로 총 VOCs의 농도는 여름철보다 가을 및 겨울철에 더 높게 검출되었으나 WHO의 기준치를 초과한 경우는 없었다.

• The Korean Journal of Physiology and Pharmacology
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• 제9권2호
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• pp.103-108
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• 2005

To study the direct effect of somatostatin (SS) on calcium channel current ($I_{Ba}$) in guinea-pig gastric myocytes, $I_{Ba}$ was recorded by using whole-cell patch clamp technique in single smooth muscle cells. Nicardipine ($1{\mu}M$), a L-type $Ca^{2+}$ channel blocker, inhibited $I_{Ba}$ by $98{\pm}1.9$% (n=5), however $I_{Ba}$ was decreased in a reversible manner by application of SS. The peak $I_{Ba}$ at 0 mV were decreased to $95{\pm}1.5$, $92{\pm}1.9$, $82{\pm}4.0$, $66{\pm}5.8$, $10{\pm}2.9$% at $10^{-10}$, $10^{-9}$, $10^{-8}$, $10^{-7}$, $10^{-5}$ M of SS, respectively (n=3∼6; $mean{\pm}SEM$). The steady-state activation and inactivation curves of $I_{Ba}$ as a function of membrane potentials were well fitted by a Boltzmann equation. Voltage of half-activation ($V_{0.5}$) was $-12{\pm}0.5$ mV in control and $-11{\pm}1.9$ mV in SS treated groups (respectively, n=5). The same values of half-inactivation were $-35{\pm}1.4$ mV and $-35{\pm}1.9$ mV (respectively, n=5). There was no significant difference in activation and inactivation kinetics of $I_{Ba}$ by SS. Inhibitory effect of SS on $I_{Ba}$ was significantly reduced by either dialysis of intracellular solution with $GDP_{\beta}S$, a non-hydrolysable G protein inhibitor, or pretreatment with pertussis toxin (PTX). SS also decreased contraction of guinea-pig gastric antral smooth muscle. In conclusion, SS decreases voltage-dependent L-type calcium channel current ($VDCC_L$) via PTXsensitive signaling pathways in guinea-pig antral circular myocytes.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.223-226
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• 2009

The plastics are widely utilized in the inside of vehicles. The dynamic tensile characteristics of auto-body plastics are important in a prediction of deformation mode of the plastic component which undergoes the high speed deformation during car crash. This paper is concerned with the dynamic tensile characteristics of the auto-body plastics at intermediate strain rates. Quasi-static tensile tests were carried out at the strain rate ranged from 0.001/sec to 0.01/sec using the static tensile machine(Instron 5583). Dynamic tensile tests were carried out at the strain rate ranged from 0.1/sec to 100/sec using the high speed material testing machine developed. Conventional extensometry method is no longer available for plastics, since the deformation of plastic is accompanied with localized deformation. In this paper, quasi-static and dynamic tensile tests were performed using ASTM IV standard specimens with grids and images from a high speed camera were analyzed for strain measurement. True stress-strain relations and the actual strain rates at each deformation step were obtained by processing load data and deformation images, assuming the plastics to deform uniformly in each grid.

• Asian-Australasian Journal of Animal Sciences
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• 제26권8호
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• pp.1119-1126
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• 2013

The objective of this study was to compare the goodness of fit of four lactation curve models: Wood's Gamma model (WD), Wilmink (WL), and Pollott's multiplicative two (POL2) and three parameters (POL3) and to determine the environmental factors affecting the complete lactation curve of F1 dairy sheep under organic management. A total of 5,382 weekly milk yields records from 150 ewes, under organic management were used. Residual mean square (RMS), determination coefficients ($R^2$), and correlation (r) analysis were used as an indicator of goodness of fit for each model. WL model best fitted the lactation curves as indicated by the lower RMS values (0.019), followed by WD (0.023), POL2 (0.025) and POL3 (0.029). The four models provided total milk yield (TMY) estimations that were highly correlated (0.93 to 0.97) with observed TMY (89.9 kg). The four models under estimated peak yield (PY), whereas POL2 and POL3 gave nearer peak time lactation estimations. Ewes lambing in autumn had higher TMY and showed a typical curve shape. Higher TMY were recorded in second and third lambing. Season of lambing, number of lambing and type of lambing had a great influenced over TMY shaping the complete lactation curve of F1 dairy sheep. In general terms WL model showed the best fit to the F1 dairy sheep lactation curve under organic management.

• 한국전산유체공학회지
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• 제20권2호
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• pp.88-95
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• 2015

Blood pump analysis process includes both mechanical and bio-mechanical aspects. Since a blood pump is a mechanical device, it has to be mechanically efficient. On the other hand, blood pumps function is sensitively related to the blood recirculation; hence, bio-factors such as hemolysis and thrombosis become important. This paper numerically investigates the mechanical and bio-mechanical performances of the Rotaflow in the extracorporeal membrane oxygenation(ECMO), Ventricular Assist Device(VAD), and full-load conditions. The operational conditions are defined as(400[mmHg], 5[L/min.]), (100[mmHg], 3[L/min.]), and (600[mmHg], 10[L/min.]) for ECMO, VAD, and full-load conditions, respectively. The results are presented and analyzed from the mechanical aspect via performance curves, and from bio-mechanical aspect via focusing on hemolytic characteristics. Regions of top and bottom cavities show recirculation in both ECMO and VAD condtions. In addition, Eulerian-based calculation of modified index of hemolysis(MIH) has been investigated. The results demonstrate that the VAD condition has the least risk of hemolysis among the others, while the full-load condition has the highest risk.

• 한국대기환경학회지
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• 제18권1호
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• pp.39-49
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• 2002

In this study, limits of detection (LOD), accuracy and precision of four sampling/ analytical methods were evaluated and compared for the determination of airborne hexavalent chromium, Cr (VI). The methods include : (1) a combination of the National Institute for Occupational Safety and Health (NIOSH) Method 7600/U. S. Environmental Protection Agency (EPA) Method 218.6 (NIOSH/EPA Method) proposed by Shin and Paik, 2) two impinger methods using 2% NaOH/3% Na$_2$CO$_3$. (3) same as (2) but with 0.02 N NaHCO$_3$absorbing solution, and (4) the Occupational Safety and Health (OSHA) Method ID-215. An ion chromatograph/visible absorbance detector was used for the analysis of Cr (VI) in sample solution. Limit of detection (LOD) , analytical accuracy, and precision were also tested using Cr (VI) spike samples. Recoveries (as index of accuracy) and coefficient of variation (CV) (as a index of precision) were determined. Two-way ANOVA and Turkey's test were performed to test the significance in differences among recoveries and CVs of the methods. In all the methods, the peaks of Cr (VI) were separated sharply on chromatograms and exhibited a strong linearity with Cr (VI) concentrations in solution. The correlation coefficients of calibration curves typically ranged from 0.9997 to 0.9999, and the analytical LODs from 0.025 to 0.1$\mu\textrm{g}$/sample. All the method had good sensitivities and linearities between Cr (VI) levels and peak areas. The accuracies (% mean recoveries) of the methods ranged from 80.1 to 104.2%, while the precisions (pooled coefficient of variation) ranged from 3.16 to 4.43%. The impinger methods showed higher recoveries ( > 95%) than those of the PVC filter methods (the OSHA Method and the NIOSH/EPA Method). It was assumed that Cr (VI) on PVC filter was exposed to air and reduced to trivalent chromium, Cr (III), whereas it was stabilized in alkali solution contained in impinger. Thus, a special treatment of Cr (VI) samples collected on PVC filters may be required.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 제33회 추계학술대회논문집
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• pp.177-180
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• 2009

본 연구에서는 HTPE 추진제 원료 및 HTPE 둔감 추진제 조성 2종에 대하여 DSC와 TGA를 사용하여 열분해 특성을 고찰하였다. AN이 포함된 HTPE 002는 약 $125^{\circ}C$에서 AN의 상전이 과정($II{\rightarrow}I$)을 거친 후, 약 $200^{\circ}C$범위까지 BuNENA와 AN이 함께 발열특성을 가지고 분해됨을 알 수 있었다. 추진제 HTPE 001과 HTPE 002의 열폭발에 대한 임계온도, $T_c$,를 Semenov의 열폭발 이론과 몇 가지 가열속도에서 측정된 비등온 곡선으로부터 계산되었고, 임계온도 계산에 사용된 열분해에 대한 활성화 에너지는 Kissinger방법으로 측정하였다.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제21권4호
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• pp.289-296
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• 2018

Purpose: We aimed to study the pattern of liver-injury in children with dengue fever (DF) and validate serum aminotransferase ${\geq}1,000IU/L$ as a marker of severe DF. Methods: Children admitted with DF were included. DF was defined by presence of clinical criteria and positive serological or antigen tests in absence of other etiology. DF severity was graded as dengue without or with warning signs and severe dengue. Liver-injury was defined as alanine aminotransferase (ALT) more than twice the upper limit of normal (boys, 30 IU/L; girls, 21 IU/L). Results: Of 372 children with DF, 144 (38.7%) had liver-injury. Risk of liver-injury and aminotransferase levels increased with DF severity (p<0.001). Recommended ALT and aspartate aminotransferase (AST) cut-off at ${\geq}1,000IU/L$ had sensitivity 4.8% (5/105), specificity 99.3% (265/267) for detection of severe DF. In children with ALT and AST <1,000 IU/L (n=365), the area under receiver operating curves for prediction for severe DF, were 0.651 (95% confidence interval [CI], 0.588-0.714; p<0.001) for ALT and 0.647 (95% CI, 0.582-0.712; p<0.001) for AST. Serum ALT at 376 IU/L and AST at 635 IU/L had sensitivity and specificity comparable to ${\geq}1,000IU/L$ for defining severe DF. Conclusion: Liver-injury is common in DF. The ALT and AST levels increase with DF severity. ALT and AST levels of ${\geq}1,000IU/L$ could be lowered to 376 IU/L and 635 IU/L respectively for defining severe DF.