• 대한치과보철학회지
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• 제44권5호
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• pp.654-664
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• 2006

Statement of problem: There has been a eat interest in the use of titanium for fixed and removable prostheses in recent because of its excellent biocompatibility. However, the melting temperature and chemical reactivity of titanium necessities casting system different from those used in conventional casting. The current titanium casting systems are based on an electric-arc design for melting the metal in an argon atmosphere and its exclusive investment. Despite the new development in Ti casting system, inadequate mold filling and internal porosity are frequently observed casting defects. Purpose : The purposes of this study were to compare the castibility and reaction layer of the casting titanium under the two casting machines and their investment condition. Material and method: coping and machine-milled titanium coping according to the casting methods and the marginal configurations. The total 28 specimens were used, and these are divided into 4 groups according to 2 casting machines and 2 investments. The castings were analyzed using x-ray microanalysis and microhardness testing. The reaction layer between margin of titanium casting and the investments was observed and analyzed with scanning electron microscope. Result: 1. Castabiliy of casting titanium specimen was best in the group of centrifugal casting machine and Selevest $CB^{\circledR}$ and good that of Selevest CB and pressure differential casting machine, Rematitan plus and centrifugal casting machine, Rematitan plus and pressure differential casting machine in order. 2. There was no significanct correlation in titanium castability in respect of casting machine. However ANOVA indicated that Selevest $CB^{\circledR}$ groups had significantly better castability than Rematitan $plus^{\circledR}$ groups.(p<0.05) 3. There was a significant microhardness difference between centrifugal casting machine groups and pressure differential groups.(p<0.05) Titanium castings in centifugal groups had significantly harder than those in pressure differential groups. 4. The addition of zirconia decreased interfacial reactivity. Conclusion: above result revealed that of the castability of titanium casting specimens had little correlation in casting machines and was better in magnesia-based investment contained ZrO2 groups. However in order to practice casting titanium in clininic, its castability should be improved, also there should be more research on factor of castability so that long-span prothesis and removable partial denture metla frame may be casted completly.

• Journal of Periodontal and Implant Science
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• 제44권5호
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• pp.235-241
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• 2014

Purpose: Regulatory T cells (Tregs), expressing CD4 and CD25 as well as Foxp3, are known to play a pivotal role in immunoregulatory function in autoimmune diseases, cancers, and graft rejection. Dendritic cells (DCs) are considered the major antigen-presenting cells (APCs) for initiating these T-cell immune responses, of which $CD103^+$ DCs are derived from precursor human peripheral blood mononuclear cells (PBMCs). The aim of the present study was to evaluate the capacity of these PBMC-derived $CD103^+$ DCs to promote the differentiation of antigen-specific Tregs. Methods: Monocyte-derived DCs were induced from $CD14^+$ monocytes from the PBMCs of 10 healthy subjects. Once the $CD103^+$ DCs were purified, the cell population was enriched by adding retinoic acid (RA). Peptide numbers 14 and 19 of Porphyromonas gingivalis heat shock protein 60 (HSP60) were synthesized to pulse $CD103^+$ DCs as a tool for presenting the peptide antigens to stimulate $CD3^+$ T cells that were isolated from human PBMC. Exogenous interleukin 2 was added as a coculture supplement. The antigen-specific T-cell lines established were phenotypically identified for their expression of CD4, CD25, or Foxp3. Results: When PBMCs were used as APCs, they demonstrated only a marginal capacity to stimulate peptide-specific Tregs, whereas $CD103^+$ DCs showed a potent antigen presenting capability to promote the peptide-specific Tregs, especially for peptide 14. RA enhanced the conversion of $CD103^+$ DCs, which paralleled the antigen-specific Treg-stimulating effect, though the differences failed to reach statistical significance. Conclusions: We demonstrated that $CD103^+$ DCs can promote antigen-specific Tregs from naive T cells, when used as APCs for an epitope peptide from P. gingivalis HSP60. RA was an effective reagent that induces mature DCs with the typical phenotypic expression of CD103 that demonstrated the functional capability to promote antigen-specific Tregs.

• 생물환경조절학회지
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• 제16권4호
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• pp.372-378
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• 2007

본 연구는 칼륨의 시비농도를 인위적으로 조절하여 잎들깨의 생장과 결핍증상 발현에 미치는 영향을 구명하고, 생육을 우수하게 유지할 수 있는 식물체 및 토양의 한계농도를 밝히기 위하여 수행하였다. 칼륨 결핍 증상은 노엽에서 시작되었으며, 노엽의 가장자리가 황변하고, 황변된 부위가 점차 갈색으로 변화되었으며, 갈변 후 괴사하였다. 칼륨 시비농도를 8mM까지 높일 경우 엽장과 줄기직경이 길거나 굵어졌으며, 생체중 및 건물중이 무거워지고, 엽록소 함량이 감소하였다. 생육이 우수하였던 K 8mM 시비구의 식물체당 건물중과 K 함량이 5.01g과 2.76%였으며, 생장억제를 방지하기 위해서는 1.7% 이상의 K 함량을 가져야 한다고 판단되었다. 칼륨을 8mM로 시비한 처리의 엽병추출액내 K 농도가 $12,289mg{\cdot}kg^{-1}$였고, 1:2로 추출한 토양농도가 $11.65mg{\cdot}L^{-1}$였으며, 엽병추출액은 $8,700mg{\cdot}kg^{-1}$이상, 토양용액은 $4.5mg{\cdot}L^{-1}$을 유지하도록 시비하여야 수량 감소를 방지할 수 있다고 판단되었다.

• Journal of Gastric Cancer
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• 제18권1호
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• pp.69-81
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• 2018

Purpose: It has been reported that the survival of patients with locally advanced gastric cancer (LAGC) is better in East Asia countries than in developed western countries; however, the prognosis of LAGC remains poor. This study aimed to evaluate the effects of perioperative chemotherapy on the long-term survival of East Asia patients with LAGC. Materials and Methods: From October 2006 through August 2008, 43 patients with LAGC received perioperative S-1 combined with weekly docetaxel in a phase II study (neoadjuvant group). These patients were matched using propensity scores to patients who underwent surgery without neoadjuvant chemotherapy during the same period (surgery group). The surgical outcomes and long-term survivals were compared between the 2 groups. Results: After matching, 43 and 86 patients were included in the neoadjuvant and surgery groups, respectively, and there was no significant difference in their baseline characteristics. Although the operating time was longer in the neoadjuvant group, there was no significant difference in postoperative complications between the 2 groups. The neoadjuvant group had a significantly higher 5-year overall survival (OS) rate (73.3% vs. 51.1%, P=0.005) and a trend towards higher 5-year progression-free survival (PFS) (62.8% vs. 49.9%, P=0.145). In the multivariate analysis, perioperative chemotherapy was an independent factor for OS, with a hazard ratio of 0.4 (P=0.005) and a marginal effect on the PFS (P=0.054). Conclusions: Perioperative chemotherapy was associated with better long-term survival without increasing postoperative complications in the setting of D2 surgery for patients with LAGC, suggesting that perioperative chemotherapy can be a therapeutic option in East Asia countries.

• Asian-Australasian Journal of Animal Sciences
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• 제21권6호
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• pp.861-867
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• 2008

The objective of this study was to evaluate the effect of exogenous ghrelin on the behaviors, weight gain, and feed intakes of weanling piglets. A total of 25 pairs of Duroc$\times$Landrace$\times$Large White piglets weaned at 21 days of age were used in this experiment which finished on day 36. Each pair of healthy piglets from the same litter with similar body weight and of the same gender were selected and randomly arranged to ghrelin or control groups. Thus, there were 50 piglets (ghrelin 25; control 25) kept in 10 pens (ghrelin 5; control 5) and 5 piglets per pen. Initial body weight of the pigs did not differ between the control and ghrelin treatment ($7.43{\pm}0.17kg$; p = 0.81). Experimental pigs were infused with ghrelin ($1{\mu}g/d$ pig) via the marginal ear vein between 0750 and 0800 h at 22, 23, 24 days of age. Control pigs were infused with 0.9% saline. Feed consumption was measured on days 23, 24, 25, 29 and 36. Body weight was measured on days 22, 23, 24, 25, 29 and 36. Behavior data of individual piglets were collected by real-time observation from 0800-1500 h through remote supervisory equipment at 22, 23 and 24 days of age. The results indicated that ghrelin infusion could increase drinking (p<0.05) and lying behaviors (p<0.01) and decrease mounting behaviors (p<0.05). No significant influence of ghrelin was found on average daily weight gain (ADG) and average daily feed intake (ADFI) in this experiment (p>0.05). In conclusion, exogenous ghrelin by the method above and at the dosage of $1{\mu}g/d$ pig could cause a variety of behavioral effects, but not improve performance of weanling piglets.

• 폴리머
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• 제30권1호
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• pp.85-89
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• 2006

이축압출기를 이용한 용융혼련으로 제조한 기상성장 탄소섬유(Vapor Grown Carbon Fiber, VGCF) 충전 폴리페닐렌설파이드(polyphenylene sulfide, PPS) 복합체외 VGCF 함량에 따른 전기적, 유변학적 특성을 살펴보았다. 복합체의 파단면 모폴로지 관찰결과, 본 방법은 PPS 매트릭스 내에 VGCF를 균일하게 분산시키는데 있어서 효과적임을 확인할 수 있었다. $5\;wt\%$, VGCF 혼입까지는 미충전 PPS와 거의 유사한 전기적 성질과 유변학적 거동을 보였으며 $10\;wt\%$로 VGCF의 혼입양을 증가시켰을 때 현저한 도전성 발현 및 점도 상승, 탄성률의 주파수 무의존성 등 유변학절 성질의 변동이 관찰되었다. 고충전 PPS계에서의 탄성률의 주파수 무의존성은 복합체 내에서의 VGCF의 네트워크 형성으로 인한 건으로 추정되며, 이는 전기적 성질뿐만 아니라 유변학적 성질의 측정결과로부터 복합체 내의 도전성 네트워크의 형성을 확인할 수 있음을 보여준다.

• Restorative Dentistry and Endodontics
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• 제27권5호
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• pp.502-514
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• 2002

The aim of this study was to evaluate the marginal adaptation of direct class II sandwich restoration with packable composites(P-60), resin modified glass ionomer cement(Fuji-II LC), flowable compomer(Dyract Flow), flowable composites(Filtek Flow) in comparison with total bond restorations. In addition, for sandwich restorations, influence of different sandwich techniques was also evaluated. Large butt-joint box typed class II cavites with cervical margins 1mm below the cemento-enamel junction were cut into 70 extracted human molars. The cavities(7 groups, n=10) were filled using a closed/open sandwich restoration or total bond restoration technique with materials according to the manufacturer's recommandation using the single-component bonding agent for each system. Teeth were thermocycled 500 times between 5$^{\circ}C$ and 55$^{\circ}C$ with 30-second dwell time. The teeth were then coated with nail polish 1mm short of the restoration, placed in a 2% methylene blue for 24 hours, and sectioned with diamond wheel. Sections were examined with a stereoscope to determine the extent of microleakage. Dentine /Cementum margins were analyzed for microleakage on scale of 0(no leakage) to 4(entire axial wall) and interface between materials, on scale of 0(no leakage) to 3(axial wall). Results were evaluated with Kruskal Wallis Test, corrected for ties, to determine whether there were statistically significant differences among the seven groups. Pairs of groups were analyzed using the Student-Newman-Keuls Method and Dunn s Method. The results were as follows : 1. All groups showed some micoleakage in cervical portion. But there were no microleakage in interface between materials. 2. Closed sandwich restorations with Fuji-II LC and Filtek Flow had significantly lower leakage rating than total restorations with only P-60. However, open sandwich restorations with Dyract Flow showed significantly higher (P<0.05) 3. Closed sandwich restorations had significantly lower leakage rating than total restorations. However open sandwich restoration s showed significantly higher (P<0.05). 4. Sandwich restorations with Fuji-II LC were iou$.$or leakage than only P-60. Filtek Flow, Dyract Flow. But there were no statistically differences among the materials. From the results above, it could be concluded, closed sandwich restorations was effective in reducing microleakage of class II restorations. The best results showing the least microleakage were for the closed sandwich technique with Fuji-II LC and Filtek Flow.

• Asia pacific journal of information systems
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• 제18권1호
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• pp.117-144
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• 2008

Lots of virtual communities and online businesses presently derive their primary sources of revenues through advertising, but nevertheless are plagued with marginal profitability though they might possess a significant user base. In the light of the need for an efficacious business model, there have been recent insights of an online community in particular reaping profits through an innovative and lucrative revenue generation method that earns by selling digital items. There have been some obvious evidences (e.g., Cyworld, SecondLife, Habo Hotel, etc.) that online communities can be profitable through their unique business model of selling digital items. However, there is lack of understanding about the motivation of purchasing digital items. This study tries to identify the main motivators of digital item purchases based on social/individual identity theory and self-presentation theory. "Digital items", otherwise known as "virtual assets", may include online avatars, accessories for the avatars, decorative ornaments like furniture, digital wallpapers, skins, background music and virtual weapons used for Internet games. These digital items are employed by users for representation and articulation in the online space, especially to create and enhance their online profiles in web pages and games. Prices for digital items typically range from a few cents to a few dollars each. Based on the theoretical framework like social identity theory and self-presentation theory, we developed the research model and proposed seven hypotheses. An analysis of 225 members of Cyworld found that digital item purchase intention in virtual world is affected by both members' need for self-presentation and need for affiliation. We also found that the need for self-presentation is significantly increased by innovativeness of members, community group norm, and community involvement. We concluded that the need for self-presentation could be a key variable for profitable business model in online community service industry. However, neither individual self-efficacy nor the need for affiliation significantly influenced the need for self-presentation which triggers purchase intention of digital items. In term of the theoretical and practical contribution, this study can be a pioneering empirical research that investigates the purchase intention of digital items based on social identity theory and self-presentation theory in the online context. Also, the findings of our study are valuable and practical for practitioners in the market who wish to adopt or improve the business model of selling digital items in an online community. From the findings, it can be seen that innovativeness of users, community group norm, and community involvement are three significant factors that influence need for self-presentation of users which ultimately leads to their intentions to buy digital items. These findings put forth that virtual community providers and online businesses selling digital items should prioritize their efforts and focus on these three factors if they want to increase the sales of these digital items and generate greater revenues. This study provides important implications for academic researchers and practitioners to understand why the community members pay money for their digital items in virtual world and how the practitioners can increase the sales of digital items in an online community. A couple of limitations of the study and future research directions are also discussed.

• Journal of Animal Science and Technology
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• 제62권2호
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• pp.227-238
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• 2020

Use of raw feedstuffs for livestock is limited by low digestibility. Recently, fermentation of feedstuffs has been highlighted as a new way to improve nutrient absorption through the production of organic acids using inoculated microorganisms, which can also play a probiotic role. However, standard procedures for feedstuff fermentation have not been clearly defined because the process is influenced by climatic variation, and an analytical standard for fermented feedstuffs is lacking. This study aimed to evaluate the microbiological and biochemical changes of feedstuffs during fermentation at temperatures corresponding to different seasons (10℃, 20℃, 30℃, and 40℃). We also investigated the effects of yeast, lactic acid bacteria (LAB), and Bacillus spp. on fermentation and determined the results of their interactions during fermentation. The viable cells were observed within 8 days in single-strain fermentation. However, when feedstuffs were inoculated with a culture of mixed strains, LAB were predominant at low temperatures (10℃ and 20℃), while Bacillus spp. was predominant at high temperatures (30℃ and 40℃). A significant drop in pH from 6.5 to 4.3 was observed when LAB was the dominant strain in the culture, which correlated with the concentrations of lactic acid. Slight ethanol production was detected above 20℃ regardless of the incubation temperature, suggesting active metabolism of yeast, despite this organism making up a marginal portion of the microbes in the mixed culture. These results suggested that fermentation temperature significantly affects microbiological profiles and biochemical parameters, such as pH and the lactic acid concentration, of fermented feedstuffs. Our data provide valuable information for the determination of industrial standards for fermented feedstuffs.

• 한국식품과학회지
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• 제46권6호
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• pp.739-742
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• 2014

이 연구에서는 식품포장분야에 사용되는 유연포장재들의 두께에 따른 방충효과를 규명하여 각각의 포장재에서 일정 수준의 방충효과를 나타내기 위한 필름의 최적의 조건을 연구하고자 하였다. 식품용 유연포장재들 중에서도 가장 널리 이용되고 있는 PE, PP, PS, AF, PET를 채택하여 실험을 진행한 결과, 각 포장재들의 두께에 따른 화랑곡나방 유충에 의한 침투율은 전반적으로 필름의 종류에 관계없이 두께가 얇을수록 포장재 내부로 빠르게 침투하는 경향을 보였다. 특히 PP와 PS의 경우 다른 필름들과는 다르게 각각 $20{\mu}m$와 $30{\mu}m$에서 72시간 이내에 100% 침투되는 결과값을 보여 방충포장소재로서의 상대적인 취약함을 보였다. 결과적으로 필름의 종류에 상관없이 두께가 증가할 수록 화랑곡 나방 유충의 침투율이 낮아진다는 것을 보여 주었다. 따라서 식품 내 해충과 같은 동물성 이물의 혼입을 방지하기 위해서는 포장 소재의 종류에 따라 특정 두께 이상을 확보해야 한다고 판단된다.