• Korean Journal of Optics and Photonics
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• v.13 no.6
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• pp.530-536
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• 2002

The accurate measurements of thermal expansion coefficients is one of the most important techniques required not only in material science but also in industries. A high precision interferometric dilatometer, using acoustic optical modulator, has been constructed and its performance has been tested. The system consists of a double-path optical heterodyne interferometer and a radiant heating furnace. This provides highly accurate length measurement, and allows rapid heating and cooling method for the specimen. A three longitudinal mode frequency stabilized He-Ne laser, using the secondary beat frequency, is constructed. Its stability is found to be $5{\times}10^{-9}$. The uncertainty in the length measurement is estimated to be of nanometer order in the range between room temperature to 1100 K.

• Journal of Food Hygiene and Safety
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• v.13 no.1
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• pp.24-28
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• 1998

Korean sesame oil mixed with corn oil and Chinese sesame oil were subjected to instrumental determination for fatty acid composition, sesaminol and sesamin contents, and induction period by AOM test to obtain basic data for ascertaining the truth of pure sesame oil, respectively. In sesame oil mixed with corn oil, stearic acid content of sesame oil containing above 20% corn oil was remarkably discriminated from that of pure sesame oil. Oleic and linoleic acid contents of sesame oil with 10% corn oil were significantly differnt from that of pure sesame oil. Stearicllinoleic acid ratio of sesame oil mixed with corn oil dcreased in proportion to corn oil content in sesame oil. Sesamolin and sesamin contents of sesame oil containing 30% corn oil were lower 18.3% and 21.0% than those of pure sesame oil, respectively. Induction periods of sesame oil by AOM were 8.14~9.24 hrs in Chinese sesame oil and sesame oils including 20% and 40% corn oils, but around 16hrs in Korean pure sesame oil. Based on the above results, it is considered that the comparisons of fatty acids, sesaminol and sesamin contents, and induction period by AOM test might be one of the potential criteria in discriminating between pure sesame oil and sesame oil mixed with corn oil.

• Food Science and Preservation
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• v.9 no.1
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• pp.67-73
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• 2002

In order to obtain the basal data far quality and sanitary stability of sesame oil extracted from imported sesame flours oil of whole sesame and flour sesame were investigated the proximate composition, chemical properties, fatty acid composition, sesamol, sesamolin, sesamin contents and oxidation induction period by AOM test. Moisture contents of sesame flours were less remarkably than whole sesame. There were no differences in proteins. Acid value and saponiflcation value were higher sesame flour oil than whole sesame oil. iodine value of sesame flour oil were lower than whole sesame oils. In fatty acid composition of sesame oil, contents of linolenic acid and linoleic acid were 222.44 ∼144.14 and 2713.00 ∼ 1776.46 mg/mL, respectively. And the contents of linoleic acid and γ-linoleic acid were lower sesame flour oil than whole sesame oil. The sesamol contents of sesame oil were higher whole sesame oil than sesame flour oil, sesamol content of India whole sesame oil was highest of them. The sesaminl sesamolin contents of Korean whole sesame oil were the Highest Oxidation induction periods of sesame oil by AOM were 6.76 and 13.35 In on north Korea and Chinese sesame flour oil, respectively. Therefore, it appears that oxidative stability was lower in north Korea and China sesame flour oil than in whole sesame oil group.

• Journal of the Korean Applied Science and Technology
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• v.6 no.1
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• pp.9-14
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• 1989

Effectiveness of some natural antioxidants were investigated by measuring the physico-chemical charcteristics and fatty acid composition during thermal oxidation in palm oil. Tocopherol showed most enhanced thermal oxidation stabilities compared to the other natural antioxidants. AR spice was no good AOM stability and changes of acid value but the other parameters were obtained desirable results. The changes of linoleic aicd content was slightly decreased during thermal oxidation. Addition of rosemary and glycyrriza extract increased the stabilities of oil less than tocopherol and AR spice. Order of antioxdative effects was tocopherol, AR spice and others. There was no significiant difference in stability of rosemary and glycyrriza extract.

• Korean Journal of Food Science and Technology
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• v.17 no.3
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• pp.180-185
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• 1985

The alkali refined rice bran oil (ARBO) and the esterified rice bran oil (ERBO) with glycerol were compared for their thermal stabilities at $150^{\circ}C$ and $180^{\circ}C$, respectively. The acid value gradually increased in ARBO during heating period but increased slowly in ERBO-2 and declined gradually in ERBO-1. The peroxide value was somewhat fluctuated during heating period, and the maximum peroxide value in all samples was 13.3 meq/kg. TBA value was sharply increased for the first 10 hr. heating and slowed down thereafter for all samples but ERBO were intensely colored after the heat treatment. The TG ratio of the oils after 90 hr. heating was not different at $150^{\circ}C$ but ERBO was 2-7% higher ratio of TG than ARBO at $180^{\circ}C$. The oxidative stability of ARBO was twice higher than ERBO according to the result of active oxygen test.

• Korean Journal of Food Science and Technology
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• v.32 no.2
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• pp.246-251
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• 2000

This study was investigated to compare the changes of antioxidative compounds in sesame oil with roasting temperature$(110^{\circ}C{\sim}230^{\circ}C)$. Lightness was decreased markedly over $170^{\circ}C$. In the changes of lignan contents, 7 different lignans unchanged up to $170^{\circ}C$ and sesamolin and sesamin decreased markedly, whereas sesamol, unknown1, unknown3 increased drastically at the higher temperatures. In tocopherol contents, ${\gamma}-tocopherol$ decreased from 70.59 mg% in unroasted oil to 33.87 mg% at $220^{\circ}C$, and to 26.73 mg% at $230^{\circ}C$. In the result of AOM(active oxygen method) test carried out at $120^{\circ}C$ for evaluating oxidative stability, the induction period of unroasted oil was 4.12 hrs and that of roasted oils was increased with roasting temperature (induction period at $220^{\circ}C$ was 27.9 hrs.). From the above results, it was confirmed that correlation coefficient between oxidative stability and lightness is -0.993 and that between oxidative stability and sesamol content is 0.934 above $170^{\circ}C$. Therefore its remarkable oxidative stability with the roasting temperature, might be considered to be due to the increase of sesamol, other lignans(unknown 1, unknown 3).

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.5
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• pp.893-898
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• 2002

To examine the antioxidant activity of grape seed ethanol extract, the antioxidative index (AI) by the active oxygen method (AOM) and peroxide value (POV) of linoleic acids containing the extract at levels of 100, 500, 1000 ppm was measured during storage at 6$0^{\circ}C$ for 12 days. When comparing with BHT, the extract at levels of 500 ppm showed similar or better antioxidant activity (AI: 2.25, POV: 57 meq/kg oil) than that (AI: 1.21, POV:58 meq/kg oil ) of BHT at 200 ppm level. The mixture of 500 ppm of the extract and 500 ppm of ascorbic acid showed intense synergistic antioxidant activity (AI: 6.21, POV: 14 meq/kg oil) compared with using 1000 ppm of the extract only (AI: 3.39, POV 43 meq/kg oil). Also to determine the feasibility of using the extract for natural antioxidant, the oxidative stability of roasted peanut and Ramyon was investigated by measuring the POV of crude oils from the samples stored at 60"C for 18 days. The oxidative stability of roasted peanut and Ramyon seemed to be enhanced by treatment with the extract at level of 1000 ppm, especially with the 1 : 1 mixture of extract and ascorbic acid. This study suggested that grape seed ethanol extract could be used as the natural antioxidant for the improvement of overall oxidation stability of fat containing foods.oods.

• Korean Journal of Food Science and Technology
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• v.26 no.6
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• pp.655-658
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• 1994

This study was designed to investigate the suitability of oxidation matters and physico-chemical characteristics as a quality evaluation for the extent of rancidity development in fats and oils undergoing thermal oxidation. The results showed that acid value rapidly increased during heating time. Soybean oil, especially revealed a faster increase than palm oil and palm olein. Anisidine value and conjugated diene value also increased. Especially, soybean oil increased more rapidly than palm oil and palm olein. Active oxygen method stability was good in the ranks of palm oil, palm olein and soybean oil. Primary oxidation matter (POM) and secondary oxidation matter (SOM) were surveyed as an evaluation method for the extent of rancidity development in fats and oils. POM and SOM showed a sharp increase during the thermal oxidation period.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.288-289
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• 2000

SBN, BSKNN KNSBN 등의 tungsten-bronze 계열에 속하는 광굴절 결정은 짧은 파장에서 좋은 감광도와 빠른 응답시간을 갖는다. 이중에서도 KNSBN 결정은 큰 크기의 결정 성장 및 도핑이 용이하고 광굴절 결정에서 중요한 특성 중 하나인 열 안정성(thermal stability)이 좋기 때문에 빠른 응답특성이 요구되는 응용분야에서 촉망받는 매질이다. 본 논문에서는 광정보저장, 광정보처리, 광컴퓨터, 광통신과 같은 다양한 분야에서 응용가능성을 가지는 Cu가 0.04wt.%도핑된 5mm$\times$5mm$\times$5mm 크기의 KNSBN 결정을 이용한 광신호의 증폭기술에 대하여 연구하였다. 먼저 Cu-KNSNB 결정의 2광파 결합 특성을 분석하기 위하여, 기록 파장에 따른 지수이득계수의 외부입사각의존성, 최대 지수이득계수를 나타내는 외부입사각에서 입사빔의 세기비에 따른 2광파 결합 이득을 측정하였다. 또한, 632.8nm파장 영역에서 기록 및 삭제시간 상수, 회절 효율의 입사빔 세기비 의존성을 측정하였다. 그리고, 음향-광학 변조기(AOM: acousto-optic modulator)에 의해 진폭 변조된 신호빔을 이용하여 광신호 증폭특성을 분석하고 그 결과를 제시하였다. 이때 두 빔의 입사각은 최대 지수이득계수를 나타내는 입사반각 12$^{\circ}$로 고정하고, 감쇄기를 이용하여 신호빔의 세기를 조절하면서 신호빔의 차동이득을 측정하였다. 투과된 신호빔은 같은 주파수에서 차동 이득(diffrerential gain)을 보였으며, 이는 moving grating과 시간-변조된 신호빔(또는 펌프빔)사이의 새로운 상호작용은 광굴절 결정의 시간 적분 특성에 의한 것이다. (중략) 경우는 상온에서 펌프 펄스의 유지시간이 0.5% 인 경우 레이저가 동작하는 것을 보여주었다. 이는 구조내에서 열전도가 문제가 된다는 것을 의미하는데 위아래가 공기로 둘러 싸여 있어 발생한 열이 가는 유전체 네트웍을 통해서만 전달 될 수 있기 때문이다. (중략)$^4$A$_2$에 의한 nophonon line R$_1$, R$_2$(680.4, 678.5 nm) 및 $^2$T$_1$$\longrightarrow$$^4$A$_2$(655.7, 649.3, 645.2 nm)의 형광방출 스펙트럼을 얻었으며, 형광수명은 0.264 ms로 조사되었다. 제조된 레이저 발진봉은 직경 6.3 m, 길이 45 nm이었다.\pm$0.06kHz Ge $F_4$; -1.84$\pm$0.04kHz$0.04kHz/TEX>0.04kHz 모국어 및 관련 외국어의 음운규칙만 알면 어느 학습대상 외국어에라도 적용할 수 있는 보편성을 지니는 것으로 사료된다.없다. 그렇다면 겹의문사를 [-wh]의리를 지 닌 의문사의 병렬로 분석할 수 없다. 예를 들어 누구누구를 [주구-이-ν가] [누구누구-이- ν가]로부터 생성되었다고 볼 수 없다. 그러므로 [-wh] 겹의문사는 복수 의미를 지닐 수 없 다. 그러면 단수 의미는 어떻게 생성되는가\ulcorner 본 논문에서는 표면적 형태에도 불구하고 [-wh]의미의 겹의문사는 병렬적 관계의 합성어가 아니라 내부구조를 지니지 않은 단순한 단어(minimal $X^{0}$ elements)로 가정한다.