• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.19 no.3
• /
• pp.227-233
• /
• 1986

The compositions and seasonal variations of free sugars and non-volatile organic acids of brown algae, such as Ecklonia cava, Sargassum ringgoldianum and Myagropsis myagroides were investigated by gas chromatography. Four kinds of free sugars, such as xylose, glucose, galactose and floridoside were identified. The most abundant one was floridoside marking 118.7 mg/100 g, 90.9 mg/100 g and 70.0 mg/100 g in Ecklonia cava, Sargassum ringgoldianum and Myagropsis myagroides, respectively. There were not distinguishable seasonal variations in the contents of free sugars in all the samples. In the case of organic acids, nine kinds were identified in Ecklenia cava and major ones were succinic, citric, malic, fumaric, oxalic and lactic acid, of which succinic acid was the most abundant one marking $30.6\%$ of total organic acids. In Sargassum ringgoldianum and Myagropsis myagroides, eight kinds were identified, which major ones were succinic, citric and malic acid in both samples, and they marked $68.4\%$ and $61.1\%$ of total organic acids in Sargassum ringgoldianum and Myagropsis myagroides, respectively. There were not distinct changes in the content of total organic acids according to seasons in all the samples examined. The contents of total organic acics in Ecklonia cava was a little more than Sargassnm ringgoldianum and Myagropsis myagroides.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.21 no.6
• /
• pp.266-273
• /
• 2011

Foamed glass was fabricated by using glass powder and foaming agents. For the glass powder, we used sodalime glass which's manufactured by using refused coal ore obtained as by-product from Dogye coal mine in Samcheok. And for the foaming agents, we used Calcium carbonate, Calcium phosphate and powder of shale type refused coal ore itself which has high content of carbon materials. We additionally used liquid binder for forming, and mixed together. And we formed rectangular shape and treated $800^{\circ}C$ for 20 min in an electrical furnace. The various kinds of foam glass samples were fabricated according to the kinds of foaming agents. The physical properties of samples, as specific gravity and compressive strength, were measured. Pore structure of each samples were investigated too. Foam glass with specific gravity of 0.4~0.7 and compressive strength of 30~72 kg/$cm^2$. Especially we get satisfying foam glass sample with low specific gravity of 0.47 and high compressive strength of 72 kg/$cm^2$ by the use of liquid calcium phosphate as foaming agent. It also had small and even shape of pore structure. Therefore, it is concluded that refused coal ore can be used for raw materials to manufacture secondary glass products such as a foamed glass panel for construction and industrial materials.

• Fire Science and Engineering
• /
• v.29 no.6
• /
• pp.40-44
• /
• 2015

National and international standards for curtain wall glass are focused on wind pressure and insulation performance, but disasters such as fires and earthquakes are not considered. Failure of curtain wall glass during a fire in a skyscraper increases the loss of lives and property due to the spread of fire. Therefore, the fire resistance of curtain wall glass should be investigated, and technology to prevent glass failure should be developed to prevent fire damage due to spreading fire. It is important to predict the starting point of cracks and the cause of glass failure to prevent it effectively using the limited water in a skyscraper. In this study, double glazed glass was exposed to a radiator in an experiment performed to analyze the thermal characteristics. The results show that glass that was not directly exposed to high temperature and pressure was broken. To identify this failure case, numerical analysis was performed. Three glass specimens were installed in an ISO 9705 room and exposed to radiation using a radiator, and a thermocouple was used to measure the temperature on the surface of the glass. Widely used double glazed glass was analyzed for weakness to fire.

• 한국신재생에너지학회:학술대회논문집
• /
• 2010.11a
• /
• pp.52-52
• /
• 2010

CIS(CuInSe2)계 화합물 태양전지는 높은 광흡수계수와 열적 안정성으로 고효율 태양전지 제조가 가능하여 태양전지용 광흡수층으로 매우 이상적이다. 미국 NREL에서는 이러한 CIGS 태양전지를 Co-evaporation 방법으로 제조 20%이상의 에너지 변환 효율을 달성하였다고 보고하였다. CIGS 태양전지의 경우 기존의 유리 기판 대신 유연한 철강 기판을 사용해 태양전지를 flexible하게 제조 할 수 있다는 장점이 있다. 이러한 flexible 태양전지의 경우 기존의 rigid 태양전지의 적용분야 뿐만 아니라 BIPV, 선박, 장난감, 군용, 자동차등 더욱더 많은 분야에 활용이 가능하다. 하지만 flexible 태양전지에 사용되는 철강기판의 경우 기존의 유리 기판인 SLG에 함유되어 있는 Na이 첨가되어 있지 않아 별도의 Na 첨가가 필요하다. Na은 CIGS 광흡수층의 결정을 증가 시키며 태양전지의 전기적 특성을 향상시킨다. 이러한 Na이 없는 경우 효율이 감소한다. 따라서 flexible 태양전지 개발을 위해서는 Na 첨가에 대한 연구가 필수적이다. 본 연구에서는 Na의 증착 순서를 변화시켜서 CIGS 증착 전, 동시증착, CIGS 증착 후로 나누어 CIGS 광흡수층 결정성의 변화를 알아보고자 한다. Na의 두께를 5nm에서 500nm 까지 단계 별로 나누어 실험을 실시하였다. 이때 CIGS 광흡수층은 미국의 NREL과 같은 3 stage 방식을 이용하였다. 1st stage의 시간은 15분으로 고정하였으며 기판온도는 약 $300^{\circ}C$로 고정 하였다. 2nd stage는 실시간 온도 감지 장치를 이용하여 Cu와 In+Ga의 조성비가 1:1이 되는 시간을 기준으로 Cu의 조성을 30%더 높게 조절하였으며 기판 온도는 약 $640^{\circ}C$로 고정 후 실험을 실시하였다. 3rd stage의 경우 Cu poor 조성으로 조절하기 위해 모든 조건을 10분으로 고정 후 실험을 실시하였다. 기판은 Na의 영향만을 비교하기위하여 Na이 첨가되어있지 않은 corning glass를 사용하였다. 후면 전극으로 약 $1{\mu}m$ 두께의 Mo을 DC Sputtering 방법을 이용하여 증착 하였다. 각각의 Na 두께에 따른 CIGS 광흡수층의 특성을 분석하기 위해 FE-SEM, XRD 분석을 실시하였다.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.14 no.1
• /
• pp.61-66
• /
• 1985

Cooked rice was prepared by the conventional cooking method being used among Korean families. The bottom layer (very slightly roasted and charred) and upper layer of the cooked rice in a cooking vessel were collected separately in order to determine the chemical changes and volatile carbonyl formation occurring in rice during the cooking process. Amino acids, especially free amino acid contents were reduced with the decrease of reducing sugar in rice after cooking. A little change was shown in the fatty acid composition of lipid fractions, however, decreased iodine values and increased fatty acid values were observed after cooking process. Volatile carbonyl compounds from cooked rice were isolated and 8 carbonyls of them were identified. A significant difference of relative composition of the identified carbonyls was found between the upper layer and bottom layer of cooked rice. Generally, the cooked rice obtained from the bottom layer had shown a little more changes in chemical composition and a stronger browning flavour than those of the upper layer of cooked rice.

• Korean Journal of Food Science and Technology
• /
• v.27 no.3
• /
• pp.290-293
• /
• 1995

This study was designed to investigate the effect of potato lipoxygenase on the change of dough chemical composition including lipid distribution, fatty acid composition, carotenoids content and color value in wheat flour dough. For the study, the potato lipoxygenase was added to wheat flour at a level of $6.5{\times}10\;unit/g$ flour. The addition of potato lipoxygenase to wheat flour dough was found to cause an increase in free lipid content, an effect apparently related to the decrease in linoleic acid content and increase in peroxide value. This phenomena might be due to the enzymatic oxidation of polyunsaturated fatty acid. Also, the bleaching effect of lipoxygenase was observed as the decrease in carotenoids content of wheat flour dough. In comparison of color value, it was shown that redness, yellowness and total color difference$({\delta}E)$ were lower by addition of lipoxygenase.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.431-431
• /
• 2010

본 논문은 기존의 수은 형광 램프와 LED를 대체할 수 있는 무 수은 면광원의 방전 가스 조성 변화(He, Ne, Ar, Xe)에 따른 전기 광학 특성에 관한 연구이다.[1]~[4] 무 수은 면광원의 기본 구조는 그림 1과 같이 방전 공간 내에 유전체에 의해 방전 공간과 분리된 한 쌍의 평행한 전극으로 이루어져 있다. 그리고 방전 공간 내면에는 일정한 두께와 형상을 가지는 형광체가 도포되어 있고 주 전극의 반대 평판유리 외벽에 보조전극을 형성하였다. 방전을 발생시키기 위한 기본적인 구동 방법은 5~25kHz의 주파수와 $0.7{\sim}1.5{\mu}s$의 폭을 가지는 사각 펄스를 사용한다.[4] 그림 2는 Ne-Xe 가스를 기본으로 하여 He 첨가에 따른 전기 광학 특성을 보여준다. He 첨가량이 증가할수록 동작 전압이 높아지면서 방전 개시와 동시에 수축 방전으로 전이되는 형태를 보이며, 효율 또한 감소함을 보였다. 이것은 무 수은 면광원에서는 높은 He의 이차전자 방출 계수보다 He의 높은 이온화 에너지가 더 크게 작용하기 때문이라 생각된다. 그림 3은 Ne-Xe 가스를 기본으로 하여 Ar 첨가에 따른 특성을 보여준다. He과는 다르게 Ar 첨가량이 증가할수록 동작 전압 마진이 넓어진다. 그러나 동작 전압이 상승하고, 효율 역시 감소하는 단점이 있다. 이것은 Ar은 Ne에 비해 이온화 에너지가 낮지만 Ar-Xe 조합은 Penning 효과를 얻을 수 있는 혼합 가스가 아니며, Ar의 2차전자 방출 계수 역시 Ne에 비해 낮기 때문에 결과적으로 방전 전압은 상승하고 효율이 감소하는 결과를 보여준다. 그러므로 무 수은 면광원에서 낮은 구동 전압과 높은 휘도 효율을 얻기 위해서는 Ne-Xe 가스조건이 가장 적합한 가스 조건이다. 효율 개선을 위해서는 Ne-Xe 가스 조건에서 압력을 높이거나 높은 Xe 함량의 가스 조성비를 사용하여 자외선 발광원인 Xe 가스량을 높이는 방법이 가장 유리하다. 그림 4는 Ne-Xe 가스 조건에서 Xe 가스량을 높이면 효율이 증가하는 경향성을 보여준다. 가스 최적화 연구와 더불어 형광체 최적화 연구[5]를 통해서 Ne-Xe25% 100Torr 가스 조건에서 그림 5와 같은 19,000nit의 높은 휘도와 75lm/W의 고 효율 특성을 얻을 수 있었다.

• Journal of Conservation Science
• /
• v.26 no.3
• /
• pp.311-324
• /
• 2010

The purpose of this study aims to reveal characteristics of reproduced potteries which made with clays of various chemical compositions in different firing temperatures and thereafter to provide comparative samples for identifying the manufacturing techniques of earthenwares from archaeological excavation by reproducing and characterizing sample under controlled conditions. For this study, various samples of earthenware are reproduced using different types of raw clays at several different firing temperature, followed by physical and structural characterization. Chemical specification were varied from different types of clay, which were calculated by Seger formula, and four different types of clay were selected based on different mole ratio of acidic oxide. The temperatures of firing of 7 samples were varied between $600^{\circ}C$ to $1200^{\circ}C$ at the interval of $100^{\circ}C$ for each sample. The result of analysis revealed that each reproduced earthenware has different chemical compositions divided into two groups: 1. Sample Y(6.10) and Sample G(5.85) clay; 2. Sample H(3.41) and Sample S(2.85) clay. The former which has higher mole ratio of acidic oxide than the latter, shows higher level of rockwell hardness at the same firing temperature. In addition, all four samples presented that as the firing temperature was increased, absorption rates of Y and G were abruptly dropped at $1200^{\circ}C$. Furthermore the more mole ratio of acidic oxide increase, the more microtexture of samples were vitrificated. Such result reveals that mole ratio of acidic oxide influence physical and microtextural characteristics of earthenwares, and it can be used as the comparison data in the understanding of manufacture techniques for the earthenwares of similar chemical composition.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.34 no.4
• /
• pp.394-402
• /
• 2001

In order to investigate the composition of dried layer, Porphyra yezoensis cultured at the south coast of Korea, the dried laver was analyzed separately for extractive nitrogen, free and combined amino acids, ATP and related compounds and quaternary ammonium basis using specimens collected monthly from January to April 1998. The extractive nitrogen contents of dried layer extracts were $976\~1,196\;mg/100\;g$ (on dry basis). Twenty-eight to thirty-one kinds of free amino acids were found in the dried laver extracts and their total amounts were 5,648-6,845 mg/100 g (on dry basis). The extracts were rich in free amino acids such as alanine, glutamic acid, taurine, phosphoserine and aspartic acid. Eighteen to twenty-two kinds of combined amino acids from oligopeptides were found in the extracts and their total amounts were $1,194\~1,406\;mg/100\;g$ (on dry basis). The amounts of ATP and related compounds were $111.6\~195.5\;mg/100\;g\;(3.30\~6.00{\mu}mol/g$ on dry basis). Homarine was detected in all samples but glycinebetaine, $\beta$-alaninebetaine and $\gamma$-butyrobetaine disappeared during processing, TMAO was detected in all samples but low TMA was found in some. During processing of dried layer, P. yezoensis, free amino acids, ATP and its related compounds were increased but the other constituents such as combined amino acids, TMAO and TMA and betaines were decreased in all specimens.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.34 no.4
• /
• pp.403-411
• /
• 2001

In order to investigate the composition of dried layer, Porphyra dentata cultured at the south coast of Korea, the dried layer was analyzed for extractive nitrogen, free amino acids, combined amino acids, ATP and its related compounds and quaternary ammonium basis, The extractive nitrogen contents of dried laver extracts were 670-1,304 mg/100 g (on dry basis). From twenty-eight to twenty-nine kinds of free amino acids were found in the dried laver extracts and their total amounts were $2,796\~6,277\;mg/100\;g$ (on dry basis). The extracts were rich in free amino acids such as alanine, taurine, glutamic acid, glutamine and phosphoserine, From eighteen to twenty-one kinds of combined amino acids were found in the extracts and their total amounts were $1,406\~2,142\;mg/100\;g$ (on dry basis). The amounts of ATP and its related compounds were $65.7\~124,7\;mg/100\;g(2.13\sim3.68{\mu}mol/g$ on dry basis), Homarine was detected in all samples but $\beta$-alaninebetaine, $\gamma$-bufobetaine and trigonelline disappeared during processing. TMAO and TMA were detected in all samples. During processing of dried layer, free amino acids, TMAO and TMA were increased but the other constituents such as combined amino acids, ATP and its related compounds and betaines were decreased in all specimens.