• 경영정보학연구
• /
• 제9권1호
• /
• pp.67-84
• /
• 2007

한 정보시스템을 소개 및 전파 시에, 만약 정보시스템의 공급자가 조기 수용성향을 가진 사용자 집단을 식별해낼 수 있다면, 그 집단에 대한 집중적인 권장 및 홍보를 통하여 더욱 효율적으로 시스템을 전파할 수 있을 것이다. 또한, 도입 이후 그 조기수용자들은 타 수용대상 집단들에 대한 시스템의 자발적 홍보와 수용 시의 도움들을 통해 시스템 도입을 더욱 용이하게 하는 효과를 가져오게 할 수 있다. 이와 같은 조기 수용자군 식별 목적을 위하여, 본 논문은 기존 주로 사용되어 온 이산선택기법 대신, 의사결정나무를 이용한 식별기법을 제안한다. 기존의 이산선택기법에 비하여 이 기법은 집단 예측에 있어서 더욱 정확하며, 비선형적으로 세분화된 그룹을 식별할 수 있는 장점도 가지고 있다. 이와 같은 효과의 검증을 위하여, 본 논문은 농업분야의 한 정보시스템 도입시의 실증데이터를 이용하여 목표집단 식별상의 의사결정나무기법의 우수성을 입증하였다. 본 기법은 앞으로 조기 수용자 집단 식별목적에 실질적으로 시스템 개발 공급자에게 이용될 수 있을 기법으로 기대된다.

• 청정기술
• /
• 제20권3호
• /
• pp.290-297
• /
• 2014

본 연구에서는 활성탄을 사용하여 coomassi brilliant blue G (CBBG)염료를 흡착하는데 필요한 흡착평형과 흡착동역학 및 열역학 파라미터들에 대하여 조사하였다. 등온흡착평형관계로 부터 Langmuir 식과 Freundlich 식의 분리계수를 평가하여 활성탄에 의한 CBBG의 흡착조작이 유효한 처리방법이 될 수 있음을 알았고, Dubinin-Radushkevich 식으로부터 흡착공정이 물리흡착공정임을 알았다. 흡착공정에 대한 동력학적 해석을 통해 흡착반응은 유사이차반응속도식이 유사일차반응속 도식에 비해 일치도가 높은 것으로 나타났으며, 입자내확산이 흡착공정의 지배단계임을 알았다. 유사이차반응속도식을 적용한 열역학적 해석을 통해 평가된 엔탈피 변화값(406.12 kJ/mol)으로부터 흡착공정이 흡열반응으로 진행됨을 알았다. 또한 엔트로피 변화값(1.66 kJ/mol K)은 흡착공정의 무질서도가 증가한다는 것을 나타내었다. 온도가 올라갈수록 자유에너지 값이 감소하는 경향을 보인 것은 활성탄에 대한 CBBG의 흡착반응은 온도가 올라갈수록 자발성이 높아지는 것으로 판단되었다.

• Corrosion Science and Technology
• /
• 제2권1호
• /
• pp.18-25
• /
• 2003

Effects of the precipitation of $\sigma$ phase on the metastable pitting as a precursor of stable pitting corrosion and also on the progress of stale pitting of the 25Cr-7Ni-3Mo-0.25N duplex stainless steel were investigated in chloride solution. Electrochemical potential and current noises of the alloy were measured in 10 % ferric chloride solution ($FeCl_3$) with zero resistance ammeter (ZRA), and then analyzed by power spectral density (PSD) and by corrosion admittance ($A_c$) spectrum. With aging at $850^{\circ}C$, the passive film of the alloy was found to get significantly unstable as represented by power spectral density (PSD) and a transition from metastable pitting state to stable one was observed. In the corrosion admittance spectrum, the number of negative $A_c$ corresponding to the state of localized corrosion increased with aging, suggesting that the precipitation of $\sigma$ phase considerably degraded the passive film by depleting Cr and Mo around it at $\alpha/\sigma$ or $\gamma/\sigma$ phase boundaries, thereby leading to the initiation of the pitting corrosion. However, the Cr and Mo at $\alpha/\sigma$ or $\gamma/\sigma$ phase boundaries which were once depleted due to the precipitation of the $\sigma$ phase were partly replenished by the diffusion of Cr and Mo from the surrounding matrix with aging time longer. The initiation of pitting seems to be associated with the precipitation density of the $\sigma$ phase with an effective size needed to induce the sufficient depletion of Cr and Mo around it.

• 한국자원식물학회:학술대회논문집
• /
• 한국자원식물학회 2012년도 정기총회 및 춘계학술발표회
• /
• pp.18-18
• /
• 2012

Antioxidant is an important role to protect the human body against damage by reactive oxygen species. However, the excessive intake of such antioxidant is known to cause a serious poisonous influence on one's liver, lungs and circulating system. Therefore, it is necessary to develop a safe natural antioxidant. For the purpose of developing natural antioxidant and antibacterial, the antioxidant activity and antibacterial effects of various extract solvents from Artichoke (Cynara Scolymus L.) leaf were determined. In this study, the extracts of Artichoke leaf dried from solvent extraction were examined by means of DPPH free radical scavenging activity and ABTS free radical scavenging activity. The effect of free radical scavenging compared with $\alpha$-tocopherol and L-ascorbic acid. In Artichoke leaf extract, evaluated by using DPPH and ABTS showed that the highest antioxidant activities were found to be in methanol extracts from DPPH radical ($IC_{50}$: $20.06{\mu}g\;mL^{-1}$), ABTS radical ($IC_{50}$: $16.01{\mu}g\;mL^{-1}$) and followed by ethanol > methyl chloride > ethyl acetate > n-Hexane. By using disc diffusion method, the antibacterial activity showed that the Artichoke leaf extract was found to be most effective against all of the tested organisms and the methyl chloride extract showed the most significant antibacterial effect against all of tests among 5 solvents extract, followed by ethyl acetate > n-Hexane > ethanol > methanol. As a result, optimal in antioxidant activity for Artichoke (Cynara Scolymus L.) leaf is methanol extract and for antibacterial effect is Methyl Chloride extract.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2009년도 하계학술발표대회 논문집
• /
• pp.645-649
• /
• 2009

Liquid desiccant cooling technology can supply cooling by using waste heat and solar heat which are hard to use effectively. For compact and efficient design of a dehumidifier, it is important to sustain sufficient heat and mass transfer surface area for water vapor diffusion from air to liquid desiccant on heat exchanger. In this study, the plate type heat exchanger is adopted which has extended surface, and hydrophilic coating and porous layer coating are adopted to enhance surface wettedness. PP(polypropylene) plate is coated by porous layer and PET(polyethylene terephthalate) non-woven fabric is coated by hydrophilic polymer. These coated surfaces have porous structure, so that falling liquid film spreads widely on the coated surface foaming thin liquid film by capillary force. The temperature of liquid desiccant increases during dehumidification process by latent heat absorption, which leads to loss of dehumidification capacity. Liquid desiccant is cooled by cooling water flowing in plate heat exchanger. On the plate side, the liquid desiccant can be cooled by internal cooling. However the liquid desiccant on extended surface should be moved and cooled at heat exchanger surface. Optimal mixing and distribution of liquid desiccant between extended surface and plate heat exchanger surface is essential design parameter. The experiment has been conducted to verify effective surface treatment and distribution characteristics by measuring wall side flow rate and visualization test. It is observed that hydrophilic and porous layer coating have excellent wettedness, and the distribution can be regulated by adopting holes on extended surface.

• 한국치위생학회지
• /
• 제12권3호
• /
• pp.631-640
• /
• 2012

Objectives : This study mean to confirm the antibacterial activity of a garlic extract widely culturing in our region and was to determine the effect of dentifrice containing 0.1% extracts of garlic on dental plaque and gingivitis in a double blind and clinical studies in 50 healthy adults aged from 20 to 22 years who provided a consent for their participation. Methods : The antibacterial activity was evaluated using triple distilled water and the Kirby-Bauer disk diffusion method and the minimal inhibitory concentration(MIC) against various pathogens for periodontal disease, such as P. gingivalis 381(ATCC33277), was estimated. The experimental groups classified according to the concentration of garlic extract used: 10,000ppm(A), 5,000ppm(B), 2,500ppm(C), 1,000ppm(D). Oral examination of subjects was performed through clinical periods and on day of baseline, 6, 12, 19, 25 days plaque index and gingival index were scored by Turesky' modified index and Loe & Silness index. After 12, 19, 25 days use of their respective dentifrices, statistically decreases of plaque index, gingival index were shown in both the experimental and the control group, respectively. Results : There was significant antibacterial activity in the "2,500ppm(C)" group against P. gingivalis 381. Experimental group exhibited significantly the lower plaque levels and the higher levels of gingival health by the use of the dentifrices contained extract of garlic from 6 days compare with control group(p<0.05). The degree of decrease was more significant on gingivitis level of the experimental group than the control group(p<0.05). Conclusions : This findings indicated that the oral products containing a garlic extract is effective in preventing and treating periodontal diseases, and has potential value in inhibiting periopathogens.

• 한국식품위생안전성학회지
• /
• 제35권2호
• /
• pp.189-194
• /
• 2020

본 연구는 항생제 내성 Salmonella Typhimurium CCARM 8009을 저해하기 위한 phage와 항생제 조합처리의 효과를 평가하였다. 디스크 확산법과 액체배지 희석법에 의해 phage와 항생제의 상승 저해효과를 측정하였고 배양을 통한 항생제 내성 유도를 평가하였다. Phage를 처리한 cefotaxime, chloramphenicol, ciprofloxacin, erythromycin의 디스크의 저해 구역은 각각 13.6%, 19.3%, 12.7%, 78.8%로 증가되었다. Phage와 항생제 조합 처리에 의해 tetracycline, chloramphenicol, ciprofloxacin, erythromycin, streptomycin의 최소생육억제농도는 각각 64, 4, 0.0078, 64, 256 mg/mL으로 감소되었다. Phage와 항생제의 조합 처리는 항생제 내성 S. Typhimurium CCARM 8009을 효과적으로 저해하였다 (4 log reduction). 본 결과는 phage와 항생제의 조합처리는 항생제 내성균을 제어하기 위한 방법으로 충분히 응용가치가 높음을 보여주고 있다.

• 한국축산식품학회지
• /
• 제31권3호
• /
• pp.413-419
• /
• 2011

The antimicrobial effects of the natural flavonoids kaempferol, quercetin, apigenin, and naringenin as well as a novel flavonoid 7-O-butyl naringenin against the growth of four meat-born Staphylococcus aureus strains were evaluated. First, the flavonoids were screened for inhibitory effects against the growth of each strain using the paper disc diffusion method. Second, the growth inhibitory effects of flavonoids that showed antimicrobial activity were measured using the microplate method. Third, the bactericidal effects of flavonoids were evaluated in a 0.8% (w/v) NaCl solution. All flavonoids showed bacteriostatic effects at >20 mM. Among the flavonoids studied, quercetin was more effective than the others tested. However, the inhibitory effect of 7-O-butyl naringenin on growth of S. aureus KCCM 32395 was greater than that of quercetin at the same concentration. Additionally, 7-O-butyl naringenin exhibited significant bactericidal effects at >25 ${\mu}M$. When bacterial cells were examined using scanning electron microscopy, it appeared that the S. aureus membranes were damaged or morphologically changed when treated with quercetin and 7-O-butyl naringenin at 200 ${\mu}M$.

• 한국세라믹학회지
• /
• 제51권3호
• /
• pp.197-200
• /
• 2014

We investigated the influence of blistering on $Al_2O_3$/SiON stacks and $Al_2O_3$/SiNx:H stacks passivation layers. $Al_2O_3$ film provides outstanding Si surface passivation quality. $Al_2O_3$ film as the rear passivation layer of a p-type Si solar cell is usually stacked with a capping layer, such as $SiO_2$, SiNx, and SiON films. These capping layers protect the thin $Al_2O_3$ layer from an Al electrode during the annealing process. We compared $Al_2O_3$/SiON stacks and $Al_2O_3$/SiNx:H stacks through surface morphology and minority carrier lifetime after annealing processes at $450^{\circ}C$ and $850^{\circ}C$. As a result, the $Al_2O_3$/SiON stacks were observed to produce less blister phenomenon than $Al_2O_3$/SiNx:H stacks. This can be explained by the differences in the H species content. In the process of depositing SiNx film, the rich H species in $NH_3$ source are diffused to the $Al_2O_3$ film. On the other hand, less hydrogen diffusion occurs in SiON film as it contains less H species than SiNx film. This blister phenomenon leads to an increase insurface defect density. Consequently, the $Al_2O_3$/SiON stacks had a higher minority carrier lifetime than the $Al_2O_3$/SiNx:H stacks.

• 대한치과마취과학회지
• /
• 제2권1호
• /
• pp.1-6
• /
• 2002

The usage of nitrous oxide is increased for the anxious patient to dental treatment. There are two methods to induce the sedation during dental treatment. One is sedation with drugs the other no need of drugs. We discussed here about sedation with drugs. The methods of drug administration are oral, intramuscular, intravenous, inhalation. The method of oral administration of drugs are convenient to patient and doctor but poor controllability. Intramuscular method is a parenteral technique that maintains several advantages over the enteral technique. However its pales in comparison to other parenteral technique. Intravenous method represents most effective method of ensuring predictable and adequate sedation in all patients. But it has inability to reverse the action of drugs after they have been injected except some drugs (e.g., narcotics and benzodiazepine). A variety of gaseous agents may be administered by inhalation to produce sedation. In dental practice, the inhalation administration of gas means use of nitrous oxide. There are many advantages of nitrous oxide administration. First, very short latent period and rapid onset of drug action which lead to possible titration of drug concentration. With nitrous oxide, clinical effects may become noticeable as quickly as 15 to 30 seconds after inhalation. Recovery from inhalation sedation is also quite rapid. In out patient dental practice rapid recovery is very important because it permit to discharge the patient without escort and the patient return to their ordinary life without limit. To success the conscious sedation with nitrous oxide, the administrator should be keep the mind that always titration of nitrous oxide concentration during induction and treatment. Careful observation need during treatment to prevent oversedation because the adequate nitrous oxide concentration to patients changed by environmental stress. Always begins with 100% oxygen and ends with 100% oxygen to prevent diffusion hypoxia which rare in clinical practice.