• Journal of the Korean Applied Science and Technology
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• v.31 no.2
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• pp.305-312
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• 2014

The following study is the result of herbal teas puffed at different temperatures between $140{\sim}220^{\circ}C$. There was change of single breadth that some carbonization occurs according to rise of processing temperature and crude ash content rises relatively, and crude protein and crude fat content had hardly changed and moisture content decreased. The solid elution rate of the herbal teas appeared by 0.18~0.27% (w/w), it increased as puffing temperature rises. The reason for the increase in solid elution rates is due to the breakage of cross bridges between the raw materials in the herbal tea which are carbohydrates, proteins, lipids and etc. after treatments of physical changes rather than chemical ones. Benzopyrene content happened difference in B(${\alpha}$)P content according to processing temperature, raw material by 0.18~0.24 ppbs.

• Journal of the Korea Institute of Building Construction
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• v.20 no.4
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• pp.321-330
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• 2020

The addition of a limestone filler(LF) to fill into the voids between cement and aggregate particles can reduce the cementitious paste volume. In previous studies, it has been found that the addition of LF to reduce the cementitious paste volume would substantially increase the compressive strength, and reduce the heat generation. This paper aim to evaluate the influence of LF contents on the hydration kinetics and compressive strength. Hydration kinetics were evaluate using heat of hydration, ignition loss and thermal analysis. The heat of hydration was measured using Isothermal Calorimetry. The degree of hydration was measured using ignition loss. Hydration product analysis was carried out by Thermal Gravimetric and Differential Thermal Analysis. The results show that the addition of LF reduces not only the initial setting time and heat of hydration peak, also degree of hydration and rate of strength development at early age increase with the addition of LF. It can be concluded the LF fills the pore between cement particles due to formation of carboaluminate, which may accelerate the setting of cement pastes.

• Korean Chemical Engineering Research
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• v.58 no.1
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• pp.92-97
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• 2020

In this study, the solubilities of a pharmaceutical compound, nifedipine, in three mixed solvents were determined. In addition, the nifedipine, that was dissolved in solvents (acetone, DMF, methylene chloride), was recrystallized using antisolvents (water, hexane, carbon dioxide) The external shape, size, and melting point of the crystallized nifedipine were measured. As the mixed solvents, acetone+water, DMF+water, and methylene chloride+hexane were used, and the solubility of nifedipine decreased with increasing antisolvent concentrations in the mixtures. In case of acetone+water, the solubility maximum was observed due to the density anomaly of the mixture, and this phenomenon was not observed in other systems. The crystallized nifedipine particles exhibited the bladed, equant, and prismatic habits, and the particles size was significantly reduced compared to the raw material. The average particle size of raw nifedipine was 337 ㎛, and the size of crystallized particles was in the range of 11.6~69.8 ㎛. All the crystallized nifedipine particles had the same thermal behavior and this result was not influenced by the change of solvent and antisolvent.

• Resources Recycling
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• v.22 no.5
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• pp.3-12
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• 2013

It is necessary to manage risk of metals which are has rigid supply structures and expected demand expansion, considering to industry structure and resource securing capacity of each country. Countries conducted various criticality analyses and selected mainly rare metals as critical materials(or Critical metals or Critical raw materials). This study examined cases of metals risk evaluation and management which are based on technology changes and imbalance supply-demand. EU and U.S.A evaluated risk on metals needed as supply expansion of renewable energy. Japan forecasted demand of rare metals needed in Japan's growth engine industry. U.K analyzed criticality of metals, considering environmental burden occurred from mining to refining. Critical materials has features such as weak price signal, inelastic supply structure, demand volatility in technology change.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.5
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• pp.529-534
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• 2009

Physiological activities of mistletoe extracts were examined. Total polyphenol contents, electro-donating ability, SOD-like activity, nitrite-scavenging ability and tyrosinase of mistletoe extracted with water, 50%, and 100% ethanol were determined. Total polyphenol contents of powder extracts were higher than slice extracts. EDAs showed over 90% at powder extracts. Especially mistletoe extracts with 50% ethanol were higher than water extracts. SOD-like activities of water, 50% and 100% ethanol extracts of all samples were $23.71{\sim}33.4%$ lower than those of 1.0% and 0.1% L-ascorbate solutions. Nitrite-scavenging activities at pH 1.2 were the most effective in water, 50% and 100% ethanol extracts. The results will be useful for understanding the physiolosical activities of mistletoe extracts.

• Environmental and Resource Economics Review
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• v.18 no.4
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• pp.745-766
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• 2009

It is not valid to measure the degree of market power based on the markup of price over marginal market cost in an industry for which the market price of some inputs is not available because those inputs are then excluded in estimating the dual total cost function. If the roles of those inputs are ignored, the markup of price over marginal market cost is likely to be positive in the perfectly competitive industry. In order to have accurate market power markups for the environmentally regulated Korean iron and steel industry, in which the market price of raw material and the price of abatement capital are hard to obtain, in this paper, a dual cost function is derived given the optimal quantities of raw material and abatement capital, and then estimated jointly with the supply relation. The annual average degree of market power for the industry is estimated to be 0.49 over the period 1982~2001. Ignoring environmental regulation would overstate the degree of market power by about 8 percent.

• Journal of the Korean Institute of Gas
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• v.24 no.4
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• pp.32-38
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• 2020

Based on the cases of fire and explosion accident in the chemical reactor, thr problems of preventive measures installed in the chemical reactor were analyzed. The chemical reactors produce a variety of chemicals and install rupture disk to relieve the pressure that rises sharply in the event of a runaway reaction. In order to maintain the function of the rupture disk, the emissions was allowed to be discharged into the atmosphere, resulting in fire and explosion accidents. As a way to improve this, safety instrumented system based on the safety integrity level(SIL3) was applied as a preventive measures for chemical reactor. Two emergency shur-off valves are installed in series on pipe dropping raw materials for chemical reactor so that the supply of raw materials can be cut off even if only one of the two emergency shut-off valves is operated during the runaway reaction. The automatic on/off valve is installed in parallel in the supply pipe of the reaction inhibitor so that the reaction inhibitor can be injected even if only one valve is opened at the time of the runaway reaction.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.27-27
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• 2010

최근에 고유가와 지구온난화로 인하여 에너지가 향후 인류의 50년을 좌우할 가장 큰 문제로 대두되고 있어서 지구의 모든 에너지의 근원인 태양광을 이용하는 태양광 발전은 무한한 청정 에너지로 각광받고 있다. 빛을 흡수하여 전기에너지로 변환하는 태양전지는 풍력, 수소연료전지, 조력, 바이오에탄올 등의 신재생에너지 기술 중에서 상품성은 가장 뛰어나지만 발전단가가 가장 높은 것이 단점이다. 태양광 발전단가를 줄여서 기존의 화석에너지를 이용한 발전단가와 견줄 수 있는 그리드 패러티(grid parity)를 달성하려면 태양전지 모듈의 고효율화와 동시에 저가화가 반드시 이루어져야 한다. 현재 태양광 모듈 시장의 90%는 효율이 12-16% 정도로 높은 단결정(single crystalline or monocrystalline) 실리콘이나 다결정(polycrystalline or multicrystalline) 실리콘 등의 벌크(bulk)형 결정질 실리콘 모듈이 차지하고 있으나 원재료인 실리콘 웨이퍼의 제조단가의 50%를 차지하고 있어서 저가화가 어렵다. 반면, 원료가스를 분해하여 대면적 기판에 증착하는 박막(thin-film) 실리콘 태양전지의 경우는 차세대 태양전지로 각광받고 있다. 박막 실리콘 모듈은 매우 적은 실리콘 원재료를 소비한다. 단결정이나 다결정 실리콘 웨이퍼의 두께가 $180-250\;{\mu}m$ 정도인 것에 비해서 박막 실리콘의 두께는 $0.3-3\;{\mu}m$ 수준이다. 더불어, 유리, 플라스틱 등의 저가 기판에 저온 대면적 증착이 가능하여 저가양산화에 유리하다. 박막 실리콘 모듈은 벌크형 실리콘 모듈(-0.5%/K) 대비 낮은 온도계수[비정질 실리콘(amorphous silicon; a-Si:H)의 경우 -0.2%/K]와 빛의 세기가 약한 산란광에서도 동작하여 평균발전시간이 증가하므로 외부환경에서 우수한 발전성능을 보이고 있다. 태양전지 모듈은 상온에서의 안정화 효율을 기준으로 가격이 책정되어($/$W_p$) 판매되기 때문에 벌크형 실리콘 모듈에 비해서 박막 실리콘 모듈은 가격대 성능비가 우수하다. 따라서 박막 실리콘 모듈은 벌크형 결정 실리콘 모듈의 대안으로 떠오르고 있으며, 레이저 기술을 이용하여 수려한 투광형 건물일체형(building integrated photovoltaic; BIPV) 모듈을 제작할 수 있는 장점도 있다. 이러한 장점에도 불구하고 기존의 양산화된 단일접합 비정질 실리콘 태양광 모듈은 효율이 6-7%로 낮아서 설치면적 및 설치 모듈의 증가가 성장의 걸림돌이 되고 있다. 박막 실리콘 태양전지의 고효율화를 도모하기 위해서 적층형 탄뎀셀로 양산 트렌드가 변화하고 있다. 이에 적층형 박막 실리콘 태양전지 효율의 한계 및 돌파구에 대해서 논의한다.

• Korean Journal of Microbiology
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• v.38 no.3
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• pp.230-233
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• 2002

Superoxide is involved in causing inflammation, cancer, and arteriosclerosis in many cases. Taking antioxidant material can be helpful in preventing the diseases. Natural food such as barley, wormwood, sea tangle, and soybean contain antioxidant ingredients. Antioxidant activity increase was determined by fermenting them with microorganism. To determine the activity, 1,1-diphenyl-2-picrylhydrazyl (DPPH) solution was used. When barley, wormwood, sea tangle, and soybean were fermented with Bacillus lichenifomis Bl, antioxidant activities of each fermented product increased 2.6, 1.6, 2.7, and 1.7 folds, respectively. Also, absorbance of fermented soybean was higher than that of soybean at the range of 250~290nm, which might be involved in differences of antioxidant activity of the two. Paraquat suppressed Esherichia coli DH5$\alpha$ growth by making superoxide inside the strain. However, when ethanol extract from fermented soybean was added into the GM (glucose-mineral) media containing the strain, its growth was recovered, suggesting that ethanol extract can move across E. coli, and can function as anti-oxidant material in vivo. Thus, it will be possible to develope antioxidant material from fermented soybean which can be taken orally.

• Korean Journal of Food Science and Technology
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• v.34 no.3
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• pp.390-395
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• 2002

Concentrations of minerals (Ca, K, Mg, Na, Se, Zn, Fe, and Mn) in 50 different Korean foodstuffs were determined through neutron activation analysis. To check the accuracy of this method, the U.S. NIST standard reference materials were analyzed. Anchovy, sesame, perilla, and laver were found to contain relatively higher concentrations of Ca, Mg, Fe, and Zn than the other foodstuffs.