• Title/Summary/Keyword: 열방산

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A study of analytical method for volatile fatty acids (VFA) by cryogenic trapping-thermal desorption (CT-TD) technique (저온농축열탈착 시스템을 연계한 유기지방산의 분석법 평가 및 검토)

  • Ahn, Ji-Won;Kim, Ki-Hyun;Im, Moon-Soon;Ju, Do-Weon
    • Analytical Science and Technology
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    • v.24 no.3
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    • pp.200-211
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    • 2011
  • In this study, 13 compounds including four volatile fatty acids (VFA) and nine volatile organic compounds (VOC) were analyzed by cryogenic trapping-thermal desorption technique. In order to evaluate the analytical method for VFA, calibration experiments were performed using five different sorbent materials. When the calibration results are compared between different sorbents, sampling tube filled with Carbopack X showed the highest response factor (RF) for both VFA and VOC. To validate this new analytical method for VFA using cryogenic trapping-thermal desorption technique, this method was compared with alkali absorption method recommended by the odor prevention law of the Korea Ministry of Environment (KMOE). For this purpose, unknown samples were analyzed by two different methods, i.e., cryogenic trapping-thermal desorption (TD) and alkali absorption with solid phase microextraction (SPME). When the results of two different methods were compared, ratios of concentrations determined by the two analytical methods (TD/SPME) was found as 0.46 (valeric acid) ~ 0.71 (isovaleric acid). Therefore, additional study is required to properly establish and find stable analytical conditions for VFA analysis. Furthermore, comparison between two different methods should be made with more reliable calibration approaches.

Arrester Design of High power Converter (대용량 컨버터의 Arrester 설계)

  • Kim Chan-Ki;Lee Won Kyo;Shin Jin Chul;Ryu Hong U
    • Proceedings of the KIPE Conference
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    • 2004.07a
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    • pp.461-464
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    • 2004
  • 본 논문은 대용량 컨버터에 이용되는 Arrester에 대한 설계기법을 보여주고 있다. 본 논문에는 Arrester의 설계방법과 일반적인 AC계통에서 사용하는 Arrester와 다른 열방산 특성을 다루었다.

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Heat Conduction Analysis of Spreaders with Concentrated Heat Sources-Thermal Concentration Effect in Cooling Electronic Devices- (집중열원이 있는 방산판의 열전도 해석-전자부품 냉각에서의 열집중 현상-)

  • 최상민
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.13 no.4
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    • pp.726-733
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    • 1989
  • Conduction heat transfer in heat spreaders with concentrated heat sources is analyzed by finite element method calculation and the results are compared to analytical solutions for simplified cases. The local temperature rise is dependent on the heat flux, thermal conductivity of the spreader material, and the contact size of the heat source. The effect of the adjacency of other heat sources is also examined.

Optimization of Soybean Oil Fatty Acid Methyl Esters Preparation for Sucrose Polyesters Synthesis (Sucrose polyesters 합성에 사용하는 대두유 지방산 메틸에스테르 제조의 최적화)

  • Chung, Ha-Yull;Kim, Suk-Ju;Yoon, Sung-Woo;Yoon, Hee-Nam;Kong, Un-Young
    • Korean Journal of Food Science and Technology
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    • v.24 no.3
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    • pp.240-246
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    • 1992
  • Preparation of soybean oil fatty acid methyl esters (soybean oil FAME) through the transesterification of soybean oil with alkaline catalyst was optimized in terms of contents of residual free fatty acids (FFA) in soybean oil FAME and yield of soybean oil FAME due to the inhibitory effect of FFA on sucrose polyesters synthesis. Soybean oil FAME and residual FFA were analyzed quantitatively by simultaneous gas chromatography on a fused silica capillary column after converting the FFA in soybean oil FAME to tert.-butyldimethylsilyl (TBDMS) derivatives. Transesterification of soybean oil was successfully performed with alkaline catalyst (NaOH, 95%), which resulted in 99.1% yield of soybean oil FAME and less than 0.1% residual FFA contents under the conditions such as $30^{\circ}C$, 20min. and 6:1 molar ratio of anhydrous methanol to soybean oil.

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A review of analytical method for volatile fatty acids as designated offensive odorants in Korea (악취성 유기지방산 성분의 분석기술)

  • Ahn, Ji-Won;Kim, Yong-Hyun;Kim, Ki-Hyun;Song, Hee-Nam
    • Analytical Science and Technology
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    • v.25 no.2
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    • pp.91-101
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    • 2012
  • A list of volatile fatty acids (VFA) including propionic acid, butyric acid, isovaleric acid, valeric acid, etc. is well known for offensive odorants. The analysis of odorant VFA is a highly delicate task due to high reactivity and unstable recovery rate. At present, analytical methods of VFA are recommended to include alkali impregnation filter method and alkali absorption method by the malodor prevention law of the Korea Ministry of Environment (KMOE). In this review, a survey has been made to explore various approaches available for the analysis of VFA to include both official methods of the KMOE and others. In light of the unreliability of those established analytical methods, it is highly desirable to develop some substituting methods for VFA. Among such options, one may consider such option as sorbent tube (ST) sampling and cryogenic trapping-thermal desorption technique. Moreover, procedures used for standard preparation, sampling steps, and instrumental detection stage are also evaluated. Application of container sampling (like Tedlar bag) is however not recommendable due to significant (sorptive) loss in sampling and in storage stage. In the detection stage, the use of GC/MS is recommendable to replace GC/FID due to the presence of diverse interfering substances. Thus, it is essential to properly establish the basic quality assurance (QA) for VFA analysis in air.

빛나는 경영인 - "기업은 사람에 대한 투자를 아끼지 않아야 합니다" (주)이오시스템 이원승 회장

  • 한국광학기기협회
    • The Optical Journal
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    • s.146
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    • pp.13-16
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    • 2013
  • 이오시스템은 1979년 설립돼 처음 정밀광학 부품업체에서 현재는 야간투시경, 주야간 잠망경, 열영상조준경 등 우리 군이 요구하는 각종 광학 장비를 만드는 방산업체로 성장했다. 첨단기술의 집합체인 우리 군의 '눈'을 만들어 내고 있는 이오시스템의 이원승 회장을 만나 이야기를 들어봤다.

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Variations in Monoterpene Emissions from Pinus densiflora in Simwon Village at Jiri Mountain (지리산 심원마을 소나무의 Monoterpene 방산 농도 변화)

  • Park, Mi-Jin;Choi, Won-Sil;Cho, Minseok;Kim, Juwan;Kim, Jaehyeon;Lee, Young-Kyu
    • Journal of Korean Society of Forest Science
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    • v.110 no.1
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    • pp.13-21
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    • 2021
  • In this research, monoterpene emissions were investigated from pine trees(Pinus densiflora) and in the forest air in Simwon village at the Jiri Mountain. Air samples from an enclosed chamber and pine forest air were collected using a Tenax TA Tube five times a day(at 09:00, 11:00, 13:00, 15:00, and 17:00) on 1 day per month from March to November 2014. Selected needles and branches from individual pine trees were enclosed for the measurement of their monoterpene emissions. The concentration and composition of emitted monoterpenes were analyzed in a time series. The major components of monoterpenes emitted from pine trees were α-pinene, β-myrcene, β-phellandrene, and β-pinene. Seasonal data showed that the concentration of monoterpenes emitted from pine trees began increasing in June and reached its peak in August, decreasing thereafter. In addition, seasonal emissions of monoterpenes were dependent on environmental factors such as temperature. The major species of monoterpenes in forest air were α-pinene, β-pinene, and camphene. The concentration of monoterpenes in forest air began rising from March to April and reached its peak in May; multiple peaks subsequently formed in July and November. Diurnal variation in monoterpenes decreased from 09:00-10:00, reaching a low and high at 13:00-14:00 and 17:00-18:00, respectively.