• Journal of the Korean Chemical Society
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• v.15 no.6
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• pp.359-366
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• 1971

The extended Huckel calculations on five organic accelerators of vulcanization have been carried out. Various MO quantities e.g., electron populations and AO coefficients, are used to explain accelerator reactivity of the compounds. Results of these analyses lead us to support free radical mechanism of acceleration in vulcanization.

• Applied Biological Chemistry
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• v.25 no.4
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• pp.206-210
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• 1982

Effects of pH, organic acides and UV irradiation on the browning of ginseng were investigated. Browning of ginseng tended to increase slightly in the alkaline pH range, whereas no discernible pH effect was observed in the pH ranges of 3.0-5.0 and 10.0-12.5. The treatment of fresh ginseng with organic acid such as citric acid, succinic acid, and tartaric acid greatly enhanced the browning reaction of ginseng but all treatments of mixture of glucose, glutamic acid, and glucose+glutamic acid with fumaric acid decreased the browning reaction except the treatment of fumaric acid only. The addition of ascorbic acid in concentration of greater than 0.1 M markedly accelerated the browning reaction and concurrently increased the red color, a characteristic color of quality red ginseng. Irradiation of ultraviolet light while drying red ginseng increased the brown color intensity in the first 5 days and thereafter decreased the brown color intensity.

• Science of Emotion and Sensibility
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• v.1 no.1
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• pp.135-143
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• 1998

이 연구에서는 국제 사진 정서체계(International Affective Picture System: IAPS)중에서 가장 강한 부적 정서를 유발하는 6장의 슬라이드를 1분 동안 연속적으로 보여주어 스트레스 상태를 야기한 뒤 1분동안 정서를 유발하는 청각자극인 1/f음악이나 which noise를 들려주거나 또는 아무소리도 들려주지 않는 각 조건에서 뇌파의 상대적 출현량(reltive power)및 호흡률, 심박률, 피부전도수준 등의 자율신경계 반응의 변화를 분석하였다. 스트레스 정서 상태에서 이완상태로의 회복을 촉진시켜줌을 시사한다. 한편, 스트레스정서유발 상태에서 1/f 음악과 white noise이 제시되었을 때의 자율신경계 반응은 현저한 대비를 보여주었다. 그러나 스트레스 정서유발 이전의 기저선 수준과 비교할 때 1/f 음악에 의한 반응수준이 white noise 에 의한 반응수준 보다 기서선 수준에서 훨씬 더 벗어나 있었다. 따라서 이 결과는 부적정서상태에 부가된 정적 유발이 활성화된 자율신경계 반응의 안정상태로의 회복을 촉진한다는 가설을 지지하거나 부정하기에는 불충분하다. 이 연구에서 정서자극 제시 후의 회복단계에서 뇌파 반응과 자율신경계 반응의 시간경과에 따른 변화가 일치하지 않는 이유는 이들 생리신호의 반응속도가 다르기 때문일 수 있다. 이 실험은 시각과 청각의 복합 감각체계를 사용하여, 스트레스 정서상태에 정적정서유발자극이 부가되었을 때 스트레스 뇌파반응에서 이완된 뇌파반응으로의 회복이 촉진됨을 보여준 최초의 연구이다.

• Korean Journal of Materials Research
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• v.6 no.5
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• pp.494-503
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• 1996

에폭시/산무수물계의 등온 경화거동을 새로이 제작된 Torsion Pendulum(TP)으로 다양한 온도에서 조사하였으며 경화반응을 촉진시키기 위하여 두 종류의 경화촉진제를 사용하였다. 새로이 제작된 TP는 개인용 컴퓨터를 이용하여 모든 기계\ulcorner인 작동과 date 수집 및 분석이 자동으로 처리될 수 있도록 하였다. 이 기기로부터 얻어진 결과인 경화 동안의 상대전단강성율(RSR, relative shear rigidity)과 log decrement(LD)의 변화로부터 제작된 TP가 잘 작동한다는 것을 알 수 있었다. 두 종류의 촉진제가 전체적인 경화과정에 미치는 촉진효과는 비슷하였으나 각 촉진제로부터 얻어진 LD 곡선을 보면 서로 다른 모양을 나타내었다. 이것은 경화촉진제가 반응 촉진효과 이외에도 경화거동에 영향을 미친다는 것을 의미하며, 따라서 이러한 경화거동의 차이는 경화물의 성질에 영향을 줄 수 있다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.1
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• pp.84-92
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• 2014

The purpose of study is to analyze mechanism with early high portland cement and hardening accelerator. As the result, it was concluded that hardening accelerator makes accelerates appearance of $Ca(OH)_2$ through experiment using TG-DTA when it hydrates with cement. On the result of compressive strength, as increasing the amount of hardening accelerator used, early compressive strength was improved. Also, as a result of hydration heat, hardening accelerator accelerates hydration of $C_3S$ that is cement's component. On the result of XRD's analyzation, hydration product for each age could be check and it was shown that as increasing the amount of hardening accelerator used, peak point of hydration product was recorded high. As the result of SEM, appearance of C-S-H was shown as the amount of $Ca(OH)_2$'s appearance and each age according to additive contents of hardening accelerator. Therefore hardening accelerator used on this study is effective on getting early compressive strength.

• Membrane Journal
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• v.13 no.4
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• pp.268-282
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• 2003

Pervaporation-facilitated esterification with slow reaction regime was characterized by using a practical model based on non-perfect separation through membrane. A non-perfect separation in which the membrane is not perfectly permselective to water was applied to the model. Thus, membrane selectivity and membrane capability to remove water were included in the simulation model to explain how they influence the membrane-facilitated reaction process and improve the reactor performance. It was shown by simulation that in the reaction systems with non-perfect separation, reaction completion can hardly be achievable when any reactant at initial molar ratio=1 or the less abundant reactant at initial molar ratio>1 permeates through membrane, and the permeation of ester accelerates the forward reaction md increase reaction conversion at any instant through removal of product species like water. The volume change causes concentrating both reactants and products that affect the reaction with time in opposite ways; reactant-concentrating effect is dominant during the initial stage of reaction, increasing the reaction rate, and then concentrating product influences more reaction by decreasing the reaction rate.

• Solar Energy
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• v.14 no.2
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• pp.91-101
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• 1994

Heat release characteristics of a CaO packed bed reactor which is used for a chemical heat storage device has been studied. We employed Cu-plate fins to release the heat of reaction of the CaO packed bed inside the reactor fast and effectively. Two-dimensional analysis of unsteady state heat flow inside the bed was performed as a function of time and under various conditions of the Cu-plates. It is noted that the time required to release the heat of reaction with Cu fins is reduced more than twice fast compared to that without Cu fins. That was largely dependent upon the number of Cu-plate, as well.

• Membrane Journal
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• v.27 no.3
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• pp.205-215
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• 2017

Polymer membranes are cheap and easy in fabrication, and show a high permeability and selectivity, thus play pivotal roles in gas separation as well as water purification. However, polymer membranes typically exhibit the trade-off relation between permeability and selectivity; i.e. when the permeability is high, the selectivity is low and vice versa. Facilitated transport has been considered one of the solutions to address this issue. Over the last decades, facilitated transport concept had played an important role in preparing the membranes and providing ideal and various models for the transport. Understanding the nature of carrier, the mobility of matrix and the physico-chemical properties of polymer composites are crucial for facilitated transport. Depending on the mobility of carrier, facilitated transport membrane is classified into three; mobile carrier membrane, semi-mobile carrier membrane, fixed-site carrier membrane. Also, there are four types of reversible reaction between the carrier and the specific target; proton transfer reaction, nucleophilic addition reaction, p-complexation reaction and electrochemical reaction. The facilitated transport membranes have been applied in the separation of CO2, O2 and olefin (propylene or ethylene). In this review, major challenges surrounding facilitated transport membranes and the strategies to tackle these challenges are given in detail.

• Science of Emotion and Sensibility
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• v.15 no.1
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• pp.37-46
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• 2012

We tested the effects of endogenous attention and reorienting on the performance of detection task. In the classic detection paradigm of Posner and Cohen (1980), performance on target detection is measured, where target appears either on the same or difference spatial location of cue stimulus after brief period of SOA (stimulus onset asynchrony). In this study, we induced exogenous attention by manipulating predictability of cue for target, and also induced reorientation by inserting additional (reorienting) cue between initial cue and target. Experiment 1 had three conditions of reorienting speed: Early, middle, and late. Facilitation and IOR (inhibition of return) occurred in different forms depending on SOA and reorienting speed, but we were not able to discover interpretable pattern in the results. However, reanalysis of early reorienting condition revealed that facilitation and IOR occurred in a crossed manner where short SOA found facilitation and long SOA did IOR, the typical results of simple detection task. Experiment 2 collected additional data to replicate the results in early reorienting condition of experiment 1. The results obtained that facilitation occurred with short SOA and IOR with long SOA. These results contrast with those of Wright and Richard (2000) where they reported elimination of IOR when cue had predictability of target locations. These results suggest that additional cue (here, orienting cue), which rapidly appears before extinction of IOR by prior cue, brings about double IOR. The present research demonstrates that even when attention is allocated to certain location via endogenous mechanism, rapidly repeating cues in certain location maximizes IOR that offsets the effects of endogenous attention to the same location.

• Korean Journal of Microbiology
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• v.29 no.4
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• pp.258-262
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• 1991

Rate of 11.alpha.-hydroxylation of progesterone with Rhizopus nigricans was accelerated by glucose. Glucose seemed to play an important role in the formation of cofactor because its effects on the reaction were almost same as those of electron acceptors such as NADPH and $NaIO_{4}$. Rate of glucose consumption appeared to increase in proportion as the rate of hydroxylation reaction, which enhanced with increase in the glucose concentration to level off at 0.5 g/l for mycelia and at 20 g/l for spores. However, for mycelia immobilized in polyacrylamide gel, externally added glucose did not affect the reaction rate at all because of the glucose accumulated in the gel during the cultivation period. 5.alpha.-Reduction of 11.alpha.-hydroxyprogesternoe required much higher concentration of glucose than 11.alpha.-hydroxylation of progesternoe so that high yield of 11.alpha.-hydroxyprogesternoe can be obtained by repressing the activity of 5.alpha.-reductase at low concentration of glucose.