• Bulletin of the Korean Chemical Society
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• 제35권1호
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• pp.211-217
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• 2014

A new needle-based device for headspace wire coated in-needle microextraction (HS-WC-INME) was fabricated using a nichrome wire coated with poly(ethylene glycol) (PEG) and poly(dimethylsiloxane) (PDMS) mixture. The proposed needle device was applied for the determination of volatile compounds in lavender and lavandin essential oils by gas chromatography. Fundamental parameters such as needle design, conditions of extraction and desorption were optimized along with the validation of the extraction and desorption efficiency. The optimal conditions were 30 min extraction at $50^{\circ}C$ and 2 min desorption at $240^{\circ}C$. The calibration curves showed good linearity with the suitable values of the coefficients of determination ($r^2$) greater than 0.99. The limits of detection for linalyl acetate, ${\beta}$-caryophyllene, linalool and (+)-limonene were 7.15, 9.04, 10.79 and 22.26 ng, respectively. Analytical recoveries were acceptable in the test samples, varying from 86.7% to 108.0%. The values of relative standard deviations for run to run showed range less than 0.9% while 3.9% through 7.2% for needle to needle. The proposed PEG-PDMS coating could be more suitable than PDMS coating to extract particular polar groups such as alcohols.

• 터널과지하공간
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• 제10권3호
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• pp.378-386
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• 2000

본 논문은 통계적 기법에 의한 균열망 해석 프로그램 (NAPSAC)을 사용하여 암반의 수리특성을 평가하기 위해 시도되었다. 암반내 존재하는 절리의 방향성을 고려한 투수계수를 산정하기 위해 마북리 시험터널 주위의 시추자료와 막장 자료로부터 얻어진 균열에 대한 정보로부터 대상지역의 등가 투수계수를 추정하였다. 대상지역의 관찰자료 (균열망에 대한 자료, 수리지질학적 자료 )로부터 통계적 균열망 해석을 위한 입력자료를 결정하여 해석모델의 신뢰성을 확보하였다. 구현된 모델로부터 모델의 크기를 증가함에 따라서 이방성 투수계수 및 투수계수의 변화를 계산하였다. 해석결과 대상지역의 투수성은 균열군의 방향성에 의해 강한 이방성을 보였다.

• Bulletin of the Korean Chemical Society
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• 제28권3호
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• pp.369-372
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• 2007

A fast and simple high-performance liquid chromatography (HPLC) method for the simultaneous determination of four pesticides having fungicide properties has been proposed for Panax ginseng, C. A. Meyer grown for 4, 5, or 6 years. Analytical separation was performed on C18 columns using ultraviolet detector under gradient conditions. Spiked blank samples were used as standards to counteract the matrix effect observed in the chromatographic determination. The HPLC response for all pesticides was linear, with determination coefficients > 0.9986. The average rate of recovery for pesticides spiked with 2 fortification levels was > 72% with relative standard deviations < 9%. The limits of quantification (LOQ) ranged from 0.03 to 0.16 ppm. These LOQs were lower than the respective maximum residue limits (MRL) established by the Korean Food and Drug Administration (KFDA), except for cyazofamid. The proposed method was used to determine pesticide residue levels in samples of ginseng obtained from Jeonnam Province (Republic of Korea). None of the pesticides were found in ginseng samples grown for 4, 5, or 6 years.

• Journal of Astronomy and Space Sciences
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• 제32권3호
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• pp.189-200
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• 2015

In this study, we present the results of orbit determination (OD) using satellite laser ranging (SLR) data for the Science and Technology Satellite (STSAT)-2C by a short-arc analysis. For SLR data processing, the NASA/GSFC GEODYN II software with one year (2013/04 - 2014/04) of normal point observations is used. As there is only an extremely small quantity of SLR observations of STSAT-2C and they are sparsely distribution, the selection of the arc length and the estimation intervals for the atmospheric drag coefficients and the empirical acceleration parameters was made on an arc-to-arc basis. For orbit quality assessment, the post-fit residuals of each short-arc and orbit overlaps of arcs are investigated. The OD results show that the weighted root mean square post-fit residuals of short-arcs are less than 1 cm, and the average 1-day orbit overlaps are superior to 50/600/900 m for the radial/cross-track/along-track components. These results demonstrate that OD for STSAT-2C was successfully achieved with cm-level range precision. However its orbit quality did not reach the same level due to the availability of few and sparse measurement conditions. From a mission analysis viewpoint, obtaining the results of OD for STSAT-2C is significant for generating enhanced orbit predictions for more frequent tracking.

• 한국학교보건학회지
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• 제32권2호
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• pp.116-124
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• 2019

Purpose: This study was performed to measure the influence of drinking motives, drinking refusal self-efficacy, and self-determination on the intention to control drinking among nursing students. Methods: A cross-sectional survey was done with the participation of 258 nursing students attending four universities in G city. Data collection was conducted from May to June, 2018, using a self-report questionnaire. Data were analyzed using the t-test, ANOVA, $Scheff{\acute{e}}$ test, Pearson's correlation coefficients, and Hierarchical multiple regression. Results: The average scores for drinking motives, drinking refusal self-efficacy, self-determination, and intention to control drinking were 2.29, 4.54, 3.89, and 4.29 respectively. There were significant differences in the intention to control drinking according to grade, religion, and age of alcohol initiation. The factors influencing the intention to control drinking in nursing students were identified as self-determination (${\beta}=.24$), drinking refusal self-efficacy (${\beta}=.17$) and drinking motives (${\beta}=-.17$). This factor explained 26% of the nursing students' intention to control drinking. Conclusion: Therefore, it is necessary to develop a alcohol education program to improve the drinking culture of nursing college students and to improve their self-regulation skills in order to help them form a desirable drinking habit, and it is also necessary to apply the developed intervention program and test the effect.

• 한국압력기기공학회 논문집
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• 제13권2호
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• pp.38-43
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• 2017

This paper investigates how to determine the Rayleigh damping coefficients for dynamic time history seismic analysis of piping systems. Three methods are applied. The first one is a conventional method to use the natural frequencies of the mode 1 and 2, derived from dynamic analysis. The second method is to determine the Rayleigh damping coefficients based on frequency range of the acceleration histories. The last one is a iterative transient response analysis method using the transient analysis results without and with damping. It is found that the conventional method and the iterative transient response method yield the same results whereas the acceleration frequency-basis method provides more conservative result than the other methods. In addition, it is concluded that the iterative transient response method is recommended.

• 영어어문교육
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• 제17권2호
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• pp.93-114
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• 2011

The aim of this study is twofold. First, this study aimed to explore how Korean university students' English learning motivation is related to their English listening proficiency and study time. Second, it attempted to interpret the English learning motivation linking the two different motivation theories: self-determination theory and L2 motivational self system. The constructs of the students' L2 learning motivation were investigated with the data obtained through the questionnaire from 122 sophomore students. A factor analysis was conducted to extract the major factors of motivation. As a result, 6 factors were extracted: Intrinsic Pleasure, Identified Value Regulation, Intrinsic Accomplishment, Introjected Regulation, External Regulation, and Identified Regulation. The Interrelatedness among the assessment results on the L2 listening proficiency (pre and post test), listening study time, and motivation factors was measured by correlation coefficients. The statistical results indicated that pre-test scores were significantly related to Identified Regulation and Identified Value Regulation toward English learning, and post-test results had significant correlation with Intrinsic Accomplishment and Identified Regulation. However, no motivation subtypes showed statistical association with the students' listening study time. The results were attempted to be interpreted both under L2 motivational self system and self-determination framework to better illuminate the motivation theory with more explanatory power.

• 한국임상수의학회지
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• 제8권1호
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• pp.31-45
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• 1991

Present experiment was performed in order to establish the optimal reaction conditions for determination of urinary AAP and GRS activities and to investigate the applicability of urinary AAP and GRS in nephrotoxicity test in rat. The results were as follows ; 1. The optimal pH of phosphate buffer for determination of urinary AAP activity was 7.8. 2. The Michaelis constant of urinary AAP ranged from 0.8 to 1.0mmol/$\ell$ 3. The optimal wave length for determination of urinary GRS activity was 405nm. 4. The optimal pH of acetate buffer for determination of urinary GRS activity was 5.6. 5. The Michaelis constant of urinary GRS ranged from 0.65~0.79mmo1/$\ell$. 6. The AAP activities in gel-filtered samples were significantly higher than those in crude samples. Mean values of AAP activities in gel-filtered samples and crude samples were 29$\pm$20 and 20$\pm$13U/$\ell$, respectively. 7. There was not significant difference between gel-filtered samples and crude samples in urinary GRS activities. Mean values of GRS activities in gel-filtered samples and crude samples were 57$\pm$40 and 56$\pm$39U/$\ell$, respectively. 8. Limits of linearity of urinary AAP and GRS activities were 2.0 and 3.6U/$\ell$, respectively. 9. Within-run imprecisions of the assays, were acceptable, as the coefficients of the AAP activities ranged from 5.5 to 6.3% and those of GRS activities ranged from 1.4 to 6.2%, respectively. 10. Urinary AAP excretion was 675$\pm$227mu/24hrs.kg before administration of potassium dichromate, and increased significantly to 4246$\pm$2567mU/24hrs.kg within 24 hours after administration of potassium dichromate. 11. Urinary GRS excretion did not increase significantly after administration of potassim dichromate. 12. From these findings it is concluded that urinary AAP excretion is early and sensitive Indicator to detect kidney damage in nephrotoxicity experiment.

• 대한토목학회논문집
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• 제32권2B호
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• pp.139-147
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• 2012

본 연구는 자연하천의 모래 179개, 자갈 992개, 조약돌 651개, 호박돌 53개 수로로 구성된 현장실측 1,875개 하천자료를 사용하여 흐름 저항에 대한 Darcy-Weisbach 마찰계수와 Manning의 조도계수 및 무차원 유속의 관계식을 각각 유도하였다. 멱함수 형의 이들 관계식은 유량, 수로경사 및 상대 잠수비에 대한 함수식으로 회귀분석과 반 경험적 방법에 의해 제안하였다. Box-Whisker 분석에 의한 Manning 조도계수의 실측치 분포는 각각 모래자료에서 0.004~0.151, 자갈자료에서 0.008~0.250, 조약돌 자료에서 0.015~0.327 및 호박돌 자료에서 0.023~0.444로 나타났다. 이들 반 경험적 관계식과 저항계수는 수공분야의 정보제공에 유용하게 사용될 것이다.

• 한국지반환경공학회 논문집
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• 제22권9호
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• pp.5-16
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• 2021

본 연구에서는 현장베인시험과 UU시험과 함께 수행한 피에조콘 관입시험결과를 이용하여 화성, 군산, 창원, 부산지역 점토의 피에조콘계수를 분석하였다. 서해안(화성, 군산) 지역의 피에조콘계수는 N_kt=12.6, N_qu =8.8이며 남해안(창원, 부산) 지역의 N_kt=16.5, N_qu =9.2이다. 이것은 지역별로 흙의 물리적 특성의 차이에 의한 것이며, 서해안 지역은 액성한계가 50% 이하인 CL이 대다수 분포하고, 남해안 지역은 액성한계가 50% 이상인 CH가 대다수 분포한다. 시험별 및 액성한계별 피에조콘계수 분류결과, 시험별로 약간의 차이를 보이나 기존에 제시된 값과 유사한 경향을 보인다. 그러나 흙의 물리적 특성인 액성한계에 따른 피에조콘계수 차이는 확연히 나타난다. 피에조콘계수는 액성한계와 밀접한 관련이 있으며 액성한계에 따른 선별 적용이 필요하다.