• Korean Chemical Engineering Research
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• v.51 no.5
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• pp.602-608
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• 2013

Gas hydrate studies are attracting attention of many researchers as an innovative, economic and environmentally friendly technology when it is applied to $CO_2$ capture, transport, and storage. In this study, we investigated whether $CO_2$ hydrate shows the self-preservation effect or not, that is the key property for developing a novel $CO_2$ transport/storage method. Especially the degree of self-preservation effect for $CO_2$ hydrate was studied according to the particle size of $CO_2$ hydrate samples. We prepared three kinds of $CO_2$ hydrate samples varying their particle diameter as millimeter, micron and nano size and measured their change of weight at $-15{\sim}-30^{\circ}C$ under atmospheric pressure during 3 weeks. According to our experimental result, the lower temperature, larger particle size, and compact structure for higher density are the better conditions for obtaining self-preservation effect.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.15 no.5
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• pp.65-76
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• 2020

This study analyzed the impact of women's self-preservation on their intention to start a business by using self-efficacy as a mediation, reflecting the importance of women's self-preservation to adapt to the new environment of start-up. In particular, in addition to the overall self-preservation, the sub-factors of behavioral delay, compensatory natural strategy, and constructive thinking strategy were also validated. As a research method, 198 people who responded to the online survey were analyzed using Model 4 of the PROCESS macro proposed by Hayes(2018), and indirect effects were analyzed by designating 5,000 bootstrapping samples. The findings were as follows. First, self-efficacy has been shown to have a mediating effect in which women's self-preservation influences their intention to start a business. At this time, the medium effect was shown as a partial medium. Second, the sense of self-efficacy was found to have a mediating effect on women's behavior-oriented strategies affecting their intention to start a business. At this time, the medium effect was shown as a partial medium. Third, self-efficacy was found to have a mediating effect in which women's natural compensatory strategies affect their intention to start a business. At this time, the medium effect was shown as a partial medium. Fourth, self-efficacy was found to have a mediating effect in which women's constructive thinking strategies affect their intention to start a business. At this time, the medium effect was shown as a complete medium. This shows that the higher a woman's self-preservation, the higher her self-efficacy and willingness to start a business. Based on the results of these studies, he made a developed proposal for women's start-ups.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.123.2-123.2
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• 2011

Self-preservation effect was identified by means of macroscopic dissociation experiments after keeping natural gas hydrate samples at 258 K for 15 days. The hydrate samples were formed using synthetic natural gas hydrate whose compositions are 90% $CH_4$, 7% $C_2H_6$, and 3% $C_3H_8$. In addition, during the formation, heavy hydrocarbons of propane and ethane are found to occupy hydrate cages in a more favorable way than methane so as to change the gas composition after hydrate formation. Experimental results obtained in this study can provide useful information on applications of natural gas hydrate for storing or transporting natural gas in the form of solid hydrate.

• Food Science and Preservation
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• v.4 no.1
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• pp.1-10
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• 1997

This study was performed to determine chemical compositions of dried persimmons stored with plastic film at low temperature and the effect of film packaging on dried persimmons during storage. The moisture contents of dried persimmons were 30 to 36% and alcohol contents were 264 to 318 mg/100g and acetaldehyde contents were 25 to 40mg/100g. Total lipid contents of dried persimmon were 626 to 869mg/100g and oleic, palmitic, linolenic, and palmitoleic acid were major fatty acids in total lipids. Major amino acids were glutamic acid, arginine, cystine and aspartic acid. From the result of storage experiment, non-packed group was that hardness was high as decreased in moisture content. In case of film packed groups stored at 5$^{\circ}C$, self life was longer than non-packed and packed groups stored at room temperature. But, it need to develop available packing material and storage method.

• Korean Chemical Engineering Research
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• v.50 no.4
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• pp.690-695
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• 2012

Gas hydrate is an inclusion compound consisting of water and low molecular weight gases, which are incorporated into the lattice structure of water. Owing to its promising aspect to application technologies, gas hydrate has been widely studied recently, especially $CO_2$ hydrate for the CCS (Carbon Capture and Storage) issue. The key point of $CO_2$ hydrate technology for the CCS is how to produce gas hydrate in an efficient and economic way. In this study, we have tried to study the characteristic of gas hydrate formation using micro-sized ice through an ultrasonic nozzle which generate 2.4 MHz frequency wave. $CO_2$ as a carrier gas brings micro-sized mist into low-temperature reactor, where the mist and carrier gas forms $CO_2$ hydrate under $-55^{\circ}C$ and atmospheric pressure condition and some part of the mist also remains unreacted micro-sized ice. Formed gas hydrate was average 10.7 of diameter at average. The starting ice particle was set to constant pressure to form $CO_2$ hydrate and the consumed amount of $CO_2$ gas was simultaneously measured to calculate the conversion of ice into gas hydrate. Results showed that the gas hydrate formation was highly suitable because of its extremely high gas-solid contact area, and the formation rate was also very high. Self-preservation effect of $CO_2$ hydrate was confirmed by the measurement of $CO_2$ hydrate powder at normal and at pressed state, which resulted that this kind of gas storage and transport could be feasible using $CO_2$ hydrate formation.

• The Korean Journal of Coaching Psychology
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• v.4 no.1
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• pp.1-19
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• 2020

The study was intended to explore the relevance of the variables below, assuming that the intolerance of uncertainty and dichotomous thinking would represent sequential serialized effects in the relationship between perfectionistic self-presentation and social anxiety. The data of this study were collected on questionnaire survey of 252 adult men and women in Seoul using perfectionistic self-presentation scale, social interaction anxiety scale, social phobia scale, intolerance of uncertainty scale and dichotomous thinkingI-30R as index, which results are as follow. First, intolerance of uncertainty and dichotomous thinking showed perfect mediation effects on the relationship between perfectionistic self-presentation and social anxiety. Intolerance of uncertainty and dichotomous thinking were identified as contributing factors to the development and preservation of social anxiety by perfectionistic self-presenters. Second, in the relationship between perfectionistic self-presentation and dichotomous thinking, intolerance of uncertainty showed mediation effect. And in the relationship between intolerance of uncertainty and social anxiety, dichotomous thinking showed mediation effect. This suggested that if tolerance of uncertainty was deficient, it was likely to lead to dichotomous thinking. And a dichotomous thinking has prompted or accelerated negative cognitive biases resulting from intolerance of uncertainty, triggering and deepening social anxiety. Lastly, the limitations of this study and future research direction were suggested.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.5
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• pp.589-601
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• 2014

Natural gas hydrate (NGH) is emerging as a new eco-friendly source of energy to replace fossil fuels in the 21st century. It is well known that the Natural Gas Hydrate contains large amount of natural gas about 170 times as much as its volume and it is easy to be stored and transported safely at about $-20^{\circ}C$ under atmospheric pressure due to so called "self-preservation effect". The option of gas transport by gas hydrate pellets carrier has been investigated and developed in various industry and academy. The natural gas hydrate pellet carrier is on major link in a potential gas hydrate process chain, starting with the extraction of natural gas from the reservoir, followed by the production of hydrate pellets and the transportation to an onshore terminal for further processing or marketing. In recent years, Korean project team supported by Korean Government has been working on the development of NGH total systems including novel NGH carrier since 2011. In order to increase the knowledge on the NGH pellet carrier developed and to understand the major hazards that could have significant impact on the safety of the vessel, this paper presents and evaluates the pros and cons of cargo holds, loading and unloading systems through the analysis of current patent technology. Based on the proven and well-known technologies as well as potential measures to mitigate sintering and minimize mechanical stress on the hydrate pellet in the self-preservation state, this study presents the conceptual and basic design for NGH carrier.

• The Korean Journal of Food And Nutrition
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• v.22 no.2
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• pp.313-319
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• 2009

To improve the growth of human mesenchymal stem cells(hMSCs) under general cell culture conditions(20% $O_2$ and 5% $CO_2$), we examined the effect of s-allylcysteine(SAC), which is known as an antioxidant and the main component of aged-garlic extract, on hydrogen peroxide-induced cellular stress in hMSCs. We found that SAC blocked hydrogen peroxideinduced cell death and cellular apoptosis, but that SAC did not improve the growth of hMSCs during short-term culture. To evaluate the protective effect of SAC, we examined the endogenous expression of the antioxidant enzymes catalase (CAT), superoxide dismutase(SOD), and glutathione peroxidase(Gpx) in hMSCs. Hydrogen peroxide was found to downregulate the expression of CAT, SOD, and Gpx at the protein level. However, in the pre-treatment group of SAC, SAC inhibited the hydrogen peroxide-induced down-regulation of CAT, SOD, and Gpx. Unfortunately, treatment with SAC alone did not induce the up-regulation of antioxidant enzymes and the cell proliferation of hMSCs. Surprisingly, SAC improved cell growth in a single cell level culture of hMSCs. These results indicate that SAC may be involved in the preservation of the self-renewal capacity of hMSCs. Taken together, SAC improves the proliferation of hMSCs via inhibition of oxidative-stress-induced cell apoptosis through regulation of antioxidant enzymes. In conclusion, SAC may be an indispensable component in an in vitro culture system of human MSCs for maintaining self-renewal and multipotent characterization of human MSCs.

• Ocean and Polar Research
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• v.26 no.3
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• pp.515-521
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• 2004

The processes of formation and dissociation of gas hydrates were investigated by monitoring pressure and temperature variations in a pressure cell in order to understand the kinetic behavior of gas hydrate and the controlling factors fur the phase transition of gas hydrate below freezing. Gas hydrates were made kom guest gases ($CH_4,\;CO_2$, and their mixed-gas) and fine ice powder. We found that formation and dissociation speeds of gas hydrates were not controlled by temperature and pressure conditions alone. The results of this study suggested that pressure levels at the formation of mixed-gas hydrate determine the transient equilibrium pressure itself.

• Journal of environmental and Sanitary engineering
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• v.11 no.1
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• pp.83-91
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• 1996

It is not too much to say that the territorial inhabitants' concerns are wholly c concentrated on the environmental preservation-problem and development-problem in Korea given effect to the local self-government system. At a time like this I was studied the effect on nutrients removal through lighting period in aerobic high rate pond and we know that waste stabilization pond method is the most economical and energy saving wastewater treatment technology than others. At the results which was studied through operating the reactor-l artifically main-tained at a temperature, $25^{\circ}C$, a light intensity, 3000lux, and a lighting period, 24hrs and the reactor-2 artifically maintained at a tern야rature, $25^{\circ}C$ and a light intensity 3000lux, and a lighting period period, 12hrs, It has appeared for 24hrs.-lighting period -reactor-1 to be prior to the reactor-2. The attained results are that 1. reactor-1 is prior to reactor-2 on oxygen-generation 2. reactor-1 is prior to reactor-2 on algal production 3. COD removal efficiency, 90.76%, T-N removal efficiency, 80%, T-P removal e efficiency, 74.47 % in reactor-2, in reactor-1 COD removal efficiency, 94.85 %, T-N removal efficiency, 98.07%, T-P removal efficiency, 72.13% are, so the treatment efficiency of reactor-1 is more excellent than things of reactor-2 4. it appeared that the detention time is 8, 9days.