• Bulletin of the Korean Chemical Society
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• 제35권12호
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• pp.3509-3513
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• 2014

Phospholipase D (PLD) catalyzed the generation of phosphatidic acid (PA) from phosphatidylcholine (PC) at the outer layer of the vesicles prepared through layer by layer via a double emulsion technique. The generation induced a curvature change in the vesicles, which eventually led them to fuse each other. The ratio of two-fatty-acid-tail ethanolamine (PE) to one-fatty-acid-tail ethanolamine (PE) was found to acquire the condition where the mixed-phospholipid vesicles were stable identically with pure two-fatty-acid-tail PC. The effect of the outer-layer mixture on the PLD-induced vesicle fusion was investigated using the fluorescence intensity change. 8-Aminonaph-thalene-1,3,6-trisulfonic acid disodium salt (ANTS) and p-Xylene-bis(N-pyridinium bromide) (DPX) were encapsulated in the vesicles, respectively, for the quantification of the fusion. The fluorescence scale was calibrated with the fluorescence of a 1/1 mixture of ANTS and DPX vesicles in NaCl buffer taken as 100% fluorescence (0% fusion) and the vesicles containing both ANTS and DPX as 0% fluorescence (100% fusion), considering the leakage into the medium studied directly in a separate experiment using vesicles containing both ANTS and DPX. The fusion data for each composition were acquired with the subtraction of the leakage from the quenching. From the monitoring, the vesicle fusion caused by the PLD reaction seems dominantly to occur rather than the vesicle lysis, because the composition effect on the fusion was observed identically with that on the change in the vesicle structure. Furthermore, the diameter measurements also support the fusion dominancy.

• 설비공학논문집
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• 제12권3호
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• pp.258-266
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• 2000

Experimental investigation and cycle simulation of a capacity modulation of a heat pump system using a hydrofluorocarbon (HFC) refrigerant mixture, R32/134a as an alternative to R22, have been done. In the cycle simulation, the refrigeration system was operated by assigning the temperatures of the external heat transfer fluids with the heat exchangers generalized by an average effective temperature difference. Heating capacity, cooling capacity, and coefficient of performance (COP) of the system were investigated at several operating conditions. Experimental apparatus which had a refrigeration part and a composition changing part was built, and the performance of the heat pump system filled with R32/134a mixture was investigated. A gas-liquid separator was used in the experiment to change the composition by collecting the vapor and the liquid Phase separately, The mass fraction of the charged refrigerant in the heat pump system was 40/60 and 70/30 by weight percentage. The composition of the refrigerant with initial composition of 40/60 varied from 29/71 to 41/59 in the refrigeration cycle. For the refrigerant with initial composition of 70/30, the composition varied from 65/35 to 75/25.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2002년도 추계학술발표강연 및 논문개요집
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• pp.26-26
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• 2002

• 한국환경농학회지
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• 제38권3호
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• pp.139-144
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• 2019

BACKGROUND: Epigeic arthropods participate in ecological functions as predators, decomposers and herbivores. The purpose of this study was to investigate the responses of some dominant arthropods in rice fields to different forms of agricultural land management. METHODS AND RESULTS: The abundance of microarthropods was compared between rice fields and uplands in the non-growing season. Collembola, Oribatida and Mesostigmata were more abundant in the upland fields than in the paddy fields. The community composition and diversity of epigeic arthropods were compared between fallow and rice fields. The total abundance and species richness of spiders and ground beetles were not significantly different in the two types of agricultural fields. The abundance of Arctosa kwangreungensis was greater in fallow fields than in cultivated fields. The community structure of arthropods was compared between paddy fields with and without barley. The cropping system altered the community composition of spiders but not their biodiversity. Barley cultivation increased the abundance of ground beetles but decreased that of spiders. We suggest that this contrast was partly due to the availability of plants that provided shelter and food for ground beetles. CONCLUSION: These results show that soil use intensity and cropping system alter the community composition of epigeic spiders and ground beetles. This could result in ecosystem-level alterations with respect to the control of pests and weeds. Our results also suggest that biodiversity of ground-dwelling arthropods may not increase during short fallow periods.

• 한국농촌건축학회논문집
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• 제22권4호
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• pp.25-34
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• 2020

The study of the modern age period folk house is still insufficient in the Korean folk house study. The study subject had a tendency towards mainly on the plan in the field of the traditional folk house which had been studied relatively lively. We were going to grasp the formation and the actual situation of the folk house in this paper targeting at Yeosu city where the folk houses were left relatively a lot. Specifically, we examined it how the composition and dimensions of timber framework changed according to period. The division of period from before 1910 to the 1960s classified it at 4 periods on the basis of the sociocultural change. However, as a result of investigation analysis, the change of the composition and dimensions of timber framework was classified at 3 periods not 4 periods. The division of 3 periods is "traditional era", "modern age 1", and "modern age 2" not "traditional era", "modern age", and "contemporary age". The folk house group came as a common name for folk house without doing the division of period until now. There is a meaning in that this paper subdivided the period of the folk house group by the change of the timber framework technology. The timber framework is the effective index to investigate the actual condition because the change is difficult after building. Therefore, we examined it including the dimensions as well as the composition of timber framework in this paper comprehensively and systematically.

• Journal of Korean Academy of Oral Health
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• 제43권3호
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• pp.118-123
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• 2019

Objectives: The purpose of this study was to investigate changes in the composition of artificial cariogenic biofilms using a Streptococcus mutans biofilm model over a period of time. Methods: We analyzed the dry weight, colony forming unit (CFU) number, extracellular polysaccharide (EPS) biovolume, and acid production rate of S. mutans biofilms formed on saliva-coated hydroxyapatite discs after 26 h, 50 h, 74 h, 98 h, 171 h, and 195 h. In addition, we performed a laser scanning confocal fluorescence microscopy to determine the bacterial volume, EPS biovolume, and biofilm thickness. We calculated the biofilm density using dry weight and EPS biovolume. Results: Over a period of time, there was no change in the CFU number and acid production rate of S. mutans biofilms, but there was an increase in the dry weight and EPS biovolume of S. mutans biofilms. The bacterial volume, EPS biovolume, and biofilm thickness only increased in the 50-h-old biofilm; however, no change was observed in 50-195-h-old biofilms. In addition, an increase in the biofilm density was observed over time. Conclusions: These results suggest that the acid production ability of cariogenic biofilms does not change, but the biofilm density increases over time. However, due to scientific information, further research needs to be conducted in the field of dentistry to get further insights on the progression of cariogenic biofilms over time.

• 농촌계획
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• 제24권2호
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• pp.69-78
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• 2018

The purpose of this study is on identifying vegetation change through monitoring representative complementary village forests according to different management. For this, two of complementary village forests around Mai mountain which many ones remain were selected. Those are complementary village forests of Seochon and Wonyeonjang. Seochon forest is a representative one which is managed naturally and Wonyeonjang one is a representative one which is managed artificially. The field survey for monitoring was preformed in 2002 and 2007, 2016. D(Dominant degree) and S(Sociability degree) were measured by Brown-Blanquet's method in field survey. Through the analysis and review of survey data, the change of species richness, appearing species characteristics, species composition and layer structure etc. according to different management was monitored. As a result, it can be seen that natural succession has increased species diversity, improved vegetation structure and circulation of complementary village forest. On the other hand, excessive anthropomorphic management was found to be detrimental to the health of the forests and to the vegetation structure and species composition. And it was found that excessive management threaten sustainability and periodical proper management is necessary. Through this review, the useful management direction of complementary village forests was suggested.

• 한국문헌정보학회지
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• 제39권3호
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• pp.225-244
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• 2005

본 연구는 대학도서관의 주제화 경향과 구성요소별 변화를 파악하고자 하였다. 새로운 정보환경과 서비스 제공환경의 변화, 대학의 학문적 특성 그리고 이용자의 정보요구에 효과적으로 대응하기 위해 대학도서관의 장서와 서비스는 주제화를 기초로 하여 재구성할 필요가 있다. 또한, 이와 같은 주제화를 보다 효과적으로 적용시키기 위해 도서관을 구성하는 물리적$\cdot$지적$\cdot$인적$\cdot$이용자구성요소의 변화를 주제화의 관점에서 분석함으로써 필요성과 당위성을 인식할 필요가 있다. 즉, 건물 및 공간의 편의성과 동선에 대한 고려, 논리성보다는 실효성에 기초한 장서의 구성 및 배치, 사서의 주제능력 개발을 통한 주제적 서비스의 활성화 그리고 점차 주제적 성향을 보이는 이용자들의 변화에 따라 도서관의 장서와 서비스는 주제를 기초로 재조직될 필요가 있다.

• Journal of Advanced Marine Engineering and Technology
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• 제29권6호
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• pp.707-712
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• 2005

PRAM (Phase change random access memory) is one of the most promising candidates for next generation Non-volatile Memories. The Phase change materials have been researched in the field of optical data storage media. Among the phase change materials. $Ge_2Sb_2Te_5$ is very well known for its high optical contrast in the state of amorphous and crystalline. However the characteristics required in solid state memory are quite different from optical ones. In this study. the structural Properties of GeSbTe thin films with composition were investigated for PRAM. The 100-nm thick $Ge_2Sb_2Te_5$ and $Sb_2Te_3$ films were deposited on $SiO_2/Si$ substrates by RF sputtering system. In order to characterize the crystal structure and morphology of these films. x-ray diffraction (XRD). atomic force microscopy (AFM), differential scanning calorimetry (DSC) and 4-point measurement analysis were performed. XRD and DSC analysis result of GST thin films indicated that the crystallization of $Se_2Sb_2Te_5$ films start at about $180^{\circ}C$ and $Sb_2Te_3$ films Start at about $125^{\circ}C$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.203-204
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• 2005

PRAM (Phase change Random Access Memory) is one of the most promising candidates for next generation Non-volatile Memories. The Phase change material has been researched in the field of optical data storage media. Among the phase change materials $Ge_2Sb_2Te_5$(GST) is very well known for its high optical contrast in the state of amorphous and crystalline. However, the characteristics required in solid state memory are quite different from optical ones. In this study, the structural properties of GST thin films with composition were investigated for PRAM. The 100-nm thick GeTe and $Sb_2Te_3$ films were deposited on $SiO_2$/Si substrates by RF sputtering system. In order to characterize the crystal structure and morphology of these films, we performed x-ray diffraction (XRD) and atomic force microscopy (AFM).