• 한국산업보건학회지
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• 제26권3호
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• pp.307-316
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• 2016

Objectives: In general, NIOSH method 5506 is most widely used for the occupational exposure measurement of PAHs, but 2-4 ring PAHs have poor desorption efficiency, especially for a filter. The purpose of this study was to determine a method to increase the desorption efficiency of 16-PAHs using an ultrasonic extraction procedure. Methods: Test samples prepared spiked XAD-2 tubes and PTFE filters in the range of $0.01-1.0{\mu}g/mL$ for desorption efficiency study. Four different extraction solvents, acetonitrile, acetone, tetrahydrofuran and dichloromethane, were tested in order to select the most suitable solvent for the extraction of the 16 PAHs. The addition of dimethyl sulfoxide and sonication time were considered in order to determine the method with the highest extraction efficiency. All samples were made in three sets and analysis was replicated seven times by HPLC. Results: Acetonitrile and acetone were the optimized as an extraction solvent and desorption efficiency of 2-ring PAHs such as naphthalene, acenaphthylene were increased 3~19% with dimethyl sulfoxide for XAD-2. Acetone was the best extraction solvent for PTFE filter and the desorption efficiency was increased 3~13% for 2- to 4-ring PAHs. The optimum sonication time was 60 minutes and desorption efficiency increased with extraction time. Conclusions: As a result, the best extraction solvent was acetone with dimethyl sulfoxide for ultrasonic extraction procedure and the desorption efficiency of this method was better than NIOSH 5506's. This study could be applied as a method for occupational exposure measurement of PAHs.

• Bulletin of the Korean Chemical Society
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• 제32권7호
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• pp.2212-2216
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• 2011

An ionic liquid-based ultrasonic-assisted extraction method has been successfully applied to the effective extraction of phenolic compounds from Laminaria japonica Aresch. Three kinds of 1-alkyl-3-methyl-imidazolium with different cations and anions were evaluated for extraction efficiency. The results showed that both the characteristics of anions and cations have remarkable effects on the extraction efficiency. In addition, the ionic liquid-based ultrasonic-assisted extraction procedure was also optimized on some extraction parameters, such as ultrasonic power, extraction time and solid-liquid ratio. Compared with the conventional solvent, the optimum approach gained the highest extraction efficiency within the shortest extraction time. Average recoveries of phenolic compounds were from 75.5% to 88.3% at three concentration levels.

• 마이크로전자및패키징학회지
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• 제18권4호
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• pp.91-95
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• 2011

GaN 기반의 LED에서 광 추출 효율을 정량적으로 분석하였다. Ray-Tracing기반의 시뮬레이션을 이용하여 사파이어 기판에 형성된 패턴의 형태, 크기, 깊이, 간격들을 분석하여 최적의 패턴 요소들을 도출하였다. 시뮬레이션의 결과로 최적의 패턴 형태는 반구 형태에서 높은 광 추출 효율을 보였다. 일반적인 패턴이 없는 사파이어 기판을 사용한 LED의 광 추출 효율보다 반구 형태의 패턴을 가진 사파이어 기판에서 약 40% 향상된 광 추출 효율을 보였다.

• 문화기술의 융합
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• 제7권1호
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• pp.564-569
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• 2021

본 연구에서는 일반적인 구조의 LED와 경사진 구조의 LED에 대하여, 전극이 없을 때와 전극에서 20%의 흡수(80% 반사)가 발생할 때, 그리고 전극에서 60%의 흡수(40% 반사)가 발생할 때로 구분하여, 전극에서의 흡수와 활성 영역의 높이가 광추출 효율 및 평균 광자 진행 거리에 미치는 영향을 조사하고, 활성 영역의 적절한 높이를 제안하였다. 일반적인 LED에서 전극의 흡수가 증가할수록, 광추출 효율은 18%에서 15%, 13%로 낮아지고, 활성 영역의 높이가 두 전극 사이의 정 중앙에 위치할 때 가장 광 추출 효율이 높다. 경사진 구조의 LED에서는 전극의 흡수가 증가할수록, 광추출 효율은 38%에서 33%, 25%로 낮아지고, 활성 영역의 높이가 두 전극 사이의 정 중앙에 위치할 때 가장 광 추출 효율이 높다. 경사진 구조의 LED는 일반적인 LED 보다 광추출 효율을 두 배 이상 높일 수 있다. 이는 전반사에 의해 광자가 칩 내부에 갇히는 현상을 줄여주기 때문이다.

• 한국대기환경학회지
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• 제16권6호
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• pp.595-606
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• 2000

In order to compare analytical conditions for measuring PAHs(polycyclic aromatic hydrocarbons) in ambient air, a series of experiment were conducted using three different types of extraction methods that include:(1) accelerated solvent extraction (ASE), (2) soxhlet, and (3) sonification methods. Efficiency and relevant analytixal parameters for each of these methods were examined on five different types of solvents that include:(1) 10% diethyl ether in n-hexane(v/v), (2) dichloromethane, (3)cyclohexane.(4) toluene, and (5) Benzene: ethanol (4:1). Comparison of extraction efficiency for various combinations between methods and solvents was made through an application of both internal and external standard calibration techniques. The extraction efficiency tests, when checked using both internal and external standards, allowed us to derive meaningful comparison among different techniques and among solvents.

• 한국화재소방학회논문지
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• 제20권2호
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• pp.72-79
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• 2006

본 연구에서는 부분배연설비의 배연효율을 분석하고, 화재시 운영방안을 제시하기 위하여 수치해석을 실시하였다. 해석결과 선행된 실험을 통하여 얻었던 균일댐퍼의 배연효율 및 연기의 단면분포에 의한 성층화 결과는 서로 일치하는 경향을 얻을 수 있었다. 균일댐퍼의 운영방안은 화재시 화재 근방의 댐퍼만을 개방하였을 경우가 터널내 모든 댐퍼를 개방하였을 경우에 비하여 약 7%의 배연효율이 증가됨을 보였다. 또한, 터널내 차량이 정체시 화재가 발생할 경우 승객의 안전한 대피를 위한 부분배연설비의 정량적인 운전방안을 제안하였다.

• 한국축산식품학회지
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• 제35권2호
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• pp.265-271
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• 2015

In a previous study, hydrolysates of porcine placenta were obtained and the extraction efficiency for proteins and amino acids was compared between sub- and super-critical water extraction systems; optimum efficiency was found to be achieved using subcritical water ($170^{\circ}C$, 10 bar). In this study, the effects of adding ethanol to the subcritical water system were investigated. The lowest-molecular-weight extraction product detected weighed 434 Da, and the efficiency of extraction for low-molecular-weight products was increased when either the concentration of ethanol was decreased, or the extraction time was lengthened from 10 min to 30 min. The highest concentration of free amino acids (approximately 8 mM) was observed following 30 min extraction using pure distilled water. The concentration of free amino acids was significantly lower when ethanol was added or a shorter extraction time was used (p<0.05). Color change of the solution following extraction was measured. There were no significant differences in color between lysates produced with different extraction times when using distilled water (p>0.05); however, using different extraction times produced significant differences in color when using 20% or 50% ethanol solution for subcritical extraction (p<0.05). The range of pH for the hydrolysate solutions was 6.4-7.5. In conclusion, the investigated extraction system was successful in the extraction of $\leq$ 500 Da hydrolysates from porcine placenta, but addition of ethanol did not yield higher production of low-molecular-weight hydrolysates than that achieved by DW alone.

• 한국전기전자재료학회논문지
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• 제28권10호
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• pp.676-681
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• 2015

Recently many studies being carried out to increase the light efficiency of LED. The external quantum efficiency of LED, generally the light efficiency, is determined by the internal quantum efficiency and the light extraction efficiency. The internal quantum efficiency of LED was already reached to more than 90%, but the light extraction efficiency is still insufficient compared with the internal quantum efficiency because the total internal reflection is generated in the interface between the LED chip and air. Thus, we studied about flip chip LED with PSS and performed the optical simulation which find more optimized PSS for flip chip LED to increase the light extraction efficiency. Decreasing of the total internal reflection and effect of diffused reflection according to PSS improved the light extraction efficiency. To get more higher the efficiency, we simulated flip chip with PSS that the parameters are arrangement, edge spacing, radius, height and shape of PSS.

• 한국지하수토양환경학회지:지하수토양환경
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• 제23권2호
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• pp.15-22
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• 2018

Aqua regia extraction for the quantification of heavy metals and As in contaminated soils was investigated as one of preliminary steps for on-site monitoring using sensor technology. Soil samples were taken from closed railway depot, closed mines, and closed refinery and various extraction conditions including $30^{\circ}C/15min$, $30^{\circ}C/30min$, $30^{\circ}C/60min$, $30^{\circ}C/120min$, $80^{\circ}C/15min$, $80^{\circ}C/30min$, $80^{\circ}C/60min$, $80^{\circ}C/120min$ were tested. The optimal extraction condition was determined as $80^{\circ}C/60min$ because the extraction efficiencies of Zn were relatively low and did not reach the targeted level (80-100% of original concentrations) for $30^{\circ}C$ conditions. It was found that the fractionation of heavy metals and As using the sequential extraction method was useful to understand the degree of metal extraction. In order to enhance the extraction efficiency within short extraction time, ultrasound technology using a 20 kHz horn-type sonicator was additionally used for $30^{\circ}C/15min$. It was revealed that ultrasound could significantly enhance the extraction efficiency and pulsed irradiation showed higher efficiency than continuous irradiation due to the less formation of bubble clouds. However high temperature condition ($80^{\circ}C$) was required to achieve high extraction efficiency for Zn in spite of the use of ultrasound.

• 분석과학
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• 제26권4호
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• pp.256-261
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• 2013

고춧가루의 매운맛을 나타내는 capsaicinoids인 capsaicin과 dihydrocapsaicin을 초고속액체 크로마토그래피로 간편하게 측정하기 위하여 고춧가루의 입도, 추출시간에 따른 추출율 비교하고 환류추출법과 가열블록법을 비교하였다. 환류추출법의 경우 3 시간 추출하는 것이 효율적이었으며 capsaicinoids 추출율은 덜 매운 고춧가루의 경우 입도가 고울수록 높았으나 매운 청량고추의 경우는 추출율이 입도에 영향을 덜 받았다. 시료량을 달리한 경우 용매의 사용을 동일하게하면 시료를 적게 사용하는 것이 추출율이 높았다. 환류추출법으로 3시간 추출한 것은 가열블록법으로 1 시간 추출한 것에 비하여 추출효율이 3-9% 높았으나 품질관리의 목적인 경우 신속간편 방법인 가열블록법으로 고춧가루의 capsaicinoids를 측정하는 것이 가능하였다.