• 대한화학회지
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• 제53권2호
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• pp.175-188
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• 2009

본 연구에서는 학교 현장에 적용 가능한 ‘샤를의 법칙’ 실험방법을 개발하였다. 교과서 및 문헌 분석을 통하여 실험 장치 및 방법을 구성하는데 필요한 요소를 분석하였다. 전체 부피를 결정하는 부분 으로 단순 구조인 주사기를 사용할 때 보다 바이알과 부피 변화를 관찰하는 부분으로 유리관을 연결한 구조를 사용하였을 때 온도 변화에 따른 기체의 부피 변화를 쉽게 측정할 수 있었고, 비커 같은 큰 부피 의 물중탕 기구 보다 눈금실린더를 이용한 물중탕 방법이 냉각 시간에 있어서 이점을 보여주었다. 부피 변화 부분에서 저항이 최소화된 형태로 액체 마개 형태가 이용되었다. 액체 마개로 물방울을 사용할 경 우 측정 초반에 증발에 의해 기체 부피변화에 큰 영향을 주는데, 글리세롤을 사용할 경우 이 같은 영향 은 거의 없었다. 제안된 실험방법으로 대략 1 시간 이내의 실험 시간을 소요하여 높은 선형 상관계수($R^2$ = 0.999)를 갖는 결과를 얻을 수 있었고, 부피가 0이 되는 온도가 $-216.7\;{^{\circ}C}$로 예측되는 정도로 매우 정확 한 결과를 보여주었다. 본 연구를 통해 개발된 샤를의 법칙 실험은 학교 급별 교육과정에 따라 수준을 조절하여 실시할 수 있을 것으로 예상한다.

• 대한기계학회논문집B
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• 제35권3호
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• pp.237-244
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• 2011

경사각이 대기압하의 포화상태인 물의 풀비등에 미치는 영향을 조사하기 위해 실험을 통한 연구를 수행하였다. 연구를 위하여 5mm의 틈새간격을 가지는 하부유로개폐 상태인 환상공간을 고려하였다. 환상공간의 내부에 설치된 튜브를 가열하였으며 튜브의 직경과 길이는 각각 25.4mm와 500mm이다. 경사각은 수평부터 수직까지 변경하였다. 본 실험의 결과를 틈새간격이 더 큰 환상공간 및 단일튜브에 대한 결과와 서로 비교하였다. 작은 틈새간격을 가지는 환상공간의 경우 경사각이 열전달에 미치는 영향은 그다지 크지 않음을 확인하였다. 그러나 환상공간이 수평상태인 경우 80kW/$m^2$에서 임계열유속이 관찰되었다. 액체 교란의 정도와 기포군집형성이 환상공간 내부 풀비등의 주된 열전달 기구로 이해된다.

• 한국가축번식학회지
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• 제9권2호
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• pp.105-112
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• 1985

This research was carried out to investigate the optimal conditions ssociated with the RIA procedures such as a bridging phenomena, prozone effects and a new separation methods etc. The results obtained were summarized as follows: 1. The lgG fractions of donkey anti-rabbit IgG sera were purified by Protein-A-Sepharose affinity column, which indicates that Protein-A an affinity for IgG class of donkey antiserum. 2. In coating the IgG fraction on polystryene tubes, incubation conditions made no differences between 2 hr at room temperature and overnight at 4$^{\circ}C$. 3. There were no significant differences between 1st antibody-coated tube and 2nd antibody-coated tube as a separation method when compared in terms of reproducbility. A better reproducibility may be expected if the titers of 1st antibody for the progesterone to be assayed and of corresponding 2nd antibody are reasonably high. 4. The titers of anti-progesterone antibody for 3H-progesterone and progesterone-11HS-125I were 1:300 and 1:700 in liquid-phase, and 1:100 and 1:300 in solid-phse for the separation methods. 5. A bridging phenomena in which a standard curve is long and shallow were observed when progesterone-11HS-125I was used for the tracer, but not in 3H-progesterone. 6. A prozone effect in a solid-phase system, especially 1st antibody-coated tube method was observed which the degree of inhibition was significantly different although zero bindings look the same. In this case, the titration curve should be made both in the absence and in the presence of a, pp.opriate amount of competiter, standard, respectively.

• Advances in Energy Research
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• 제4권4호
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• pp.299-323
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• 2016

Cylindrical parabolic solar concentrators of small concentration ratio are attractive options for working temperatures around $120^{\circ}C$. The heat gained can be utilized in many applications such as air conditioning, space heating, heating water and many others. These collectors can be easily manufactured and do not need to track the sun continuously. Using a heat pipe as a solar absorber makes the system more compact and easy to install. This study is devoted to modeling a system of cylindrical parabolic solar concentrators of small concentration ratio (around 5) fitted with a heat pipe absorber with a porous wick. The heat pipe is surrounded by evacuated glass tube to reduce thermal losses from the heat pipe. The liquid and vapor flow equations, energy equation, the internal and external boundary conditions were taken into consideration. The system of equations was solved and the numerical results were validated against available experimental and numerical results. The validated heat pipe model was inserted in an evacuated transparent glass tube as the absorber of the cylindrical parabolic collector. A calculation procedure was developed for the system, a computer program was developed and tested and numerical simulations were realized for the whole system. An experimental solar collector of small concentration, fitted with evacuated tube heat pipe absorber was constructed and instrumented. Experiments were realized with the concentrator axis along the E-W direction. Results of the instantaneous efficiency and heat gain were compared with numerical simulations realized under the same conditions and reasonably good agreement was found.

• The Journal of Advanced Prosthodontics
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• 제7권4호
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• pp.323-328
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• 2015

PURPOSE. This in-vitro study was designed to evaluate retention forces, microleakage and plastic deformation of a prefabricated 2-implant bar attachment system (SFI-Bar, Cendres+$M{\acute{e}}taux$, Switzerland). MATERIALS AND METHODS. Two SFI implant-adapters were torqued with 35 Ncm into two implant analogues. Before the tube bars were finally sealed, the inner cavity of the tube bar was filled with liquid red dye to evaluate microleakage. As tube bar sealing agents three different materials were used (AGC Cem (AGC, resin based), Cervitec Plus (CP; varnish) and Gapseal (GS; silicone based). Four groups with eight specimens each were tested (GS, GS+AGC, AGC, CP). For cyclic loading, the attachment system was assembled parallel to the female counterparts in a chewing simulator. The mean retention forces of the initial and final ten cycles were statistically evaluated (ANOVA, ${\alpha}{\leq}.05$). RESULTS. All groups showed a significant loss of retention forces. Their means differed between 30-39 N initially and 22-28 N after 50,000 loading cycles. No significant statistical differences could be found between the groups at the beginning (P=.224), at the end (P=.257) or between the loss of retention forces (P=.288). Microleakage occurred initially only in some groups but after 10,000 loading cycles all groups exhibited microleakage. CONCLUSION. Long-term retention forces of the SFI-Bar remained above 20 N which can be considered clinically sufficient. The sealing agents in this study are not suitable to prevent microleakage.

• 대한기계학회논문집B
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• 제26권7호
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• pp.911-918
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• 2002

Evaporation heat transfer coefficients of carbon dioxide($CO_2$), R-22, and R-134a in a horizontal smooth tube were measured and analyzed as a function of heat flux, mass flux, and evaporating temperature. The experiments were carried out by varying heat flux from 10 to 20 $kW/m^2$, mass flux from 170 to 340 $kg/m^2s$, and saturation temperatures of 5 and $10^{\circ}C$. It was found that the heat transfer coefficient of $CO_2$ decreased with a rise of quality due to an earlier liquid-film dryout as compared to R-22 and R-134a. Averaged heat transfer coefficients of $CO_2$ were 22-63% higher than those of R-22 and R-134a at all test conditions. The effects of mass flux and heat flux on averaged heat transfer coefficients were much greater in $CO_2$ than in R-22 and R-134a. When comparing $CO_2$ test results with the correlations in the literature, the existing models yielded large deviations at medium and high qualities. Therefore, a generalized correlation for $CO_2$evaporation heat transfer needs to be developed by including the effects of dryout phenomenon.

• 공업화학
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• 제17권1호
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• pp.111-117
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• 2006

냉 난방 수요에서 일어나는 환경오염의 최소화와 화석연료 소비를 감소시키기 위해서 에너지보존을 개선시키는 것은 필수적이다. 이러한 점에서 흡수식 열펌프기술은 에너지 절약을 위해서 많은 가능성을 가지고 있다. 흡수식 열펌프는 에너지를 주입하지 않고 폐열의 이용을 높일 수 있는 방법이다. 흡수식 열펌프는 흡수기에서 흡수된 양의 증가가 매우 중요하기 때문에 흡수기 성능이 매우 중요하다. 본 연구에서는 흡수기의 성능을 개선시키기 위해서 메탄올과 글리세린을 작동유체로 하는 두 종류의 흡수기에 관한 연구를 수행하였다. 전자는 흡수기 내에 액상을 접선방향으로 공급하는 것이고 후자는 흡수기 내벽에 나선형 관을 설치하여 액상을 접선방향으로 공급하는 것이다. 실험 결과 후자가 흡수기에서 발생하는 열 및 물질전달이 향상되어 흡수성능이 증가되었음을 알 수 있었다.

• The Plant Pathology Journal
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• 제39권1호
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• pp.123-135
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• 2023

Previously, Pseudomonas plecoglossicida YJR13 and Pseudomonas putida YJR92 from a sequential screening procedure were proven to effectively control Phytophthora blight caused by Phytophthora capsici. In this study, we further investigated the anti-oomycete activities of these strains against mycelial growth, zoospore germination, and germ tube elongation of P. capsici. We also investigated root colonization ability of the bacterial strains in square dishes, including cell motility (swimming and swarming motilities) and biofilm formation. Both strains significantly inhibited mycelial growth in liquid and solid V8 juice media and M9 minimal media, zoospore germination, and germ tube elongation compared with Bacillus vallismortis EXTN-1 (positive biocontrol strain), Sphingomonas aquatilis KU408 (negative biocontrol strain), and MgSO₄ solution (untreated control). In diluted (nutrient-deficient) V₈ juice broth, the tested strain populations were maintained at >10⁸ cells/ml, simultaneously providing mycelial inhibitory activity. Additionally, these strains colonized pepper roots at a 10⁶ cells/ml concentration for 7 days. The root colonization of the strains was supported by strong swimming and swarming activities, biofilm formation, and chemotactic activity towards exudate components (amino acids, organic acids, and sugars) of pepper roots. Collectively, these results suggest that strains YJR13 and YJR92 can effectively suppress Phytophthora blight of pepper through direct anti-oomycete activities against mycelial growth, zoospore germination and germ tube elongation. Bacterial colonization of pepper roots may be mediated by cell motility and biofilm formation together with chemotaxis to root exudates.

• 한국균학회지
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• 제39권1호
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• pp.48-52
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• 2011

본 연구에서는 표고 교잡균주들의 생화학적 특성을 이해하기 위한 하나의 시도로서 교잡균주간의 laccase 효소의 활성을 비교하는 빠르고 간편한 방법을 모색하고자 균사체 배양 배지의 성상과 염색물질이 laccase 활성 검출에 미치는 영향을 조사 비교하였다. 고체배지와 액체배지 모두에서 발색시약이 Remazol Brilliant Blue R(RBBR)일 경우는 potato dextrose 성분 보다 malt extract 성분 배지를 사용하는 것이 표고버섯균 균사가 분비하는 세포외 laccase 활성 검출이 용이하였다. Guaiacol을 발색시약으로 사용하는 경우는 potato dextrose 성분과 malt extract 성분 배지 모두 세포외 laccase 활성 검출이 용이하였다. 2ml microfuge tube를 이용한 액체 배양 방법은 RBBR와 Guaiacol 모두 malt extract 성분배지에서 3일만에 표고 교잡균주간의 세포외 laccase 활성 검출과 정량적 비교를 가능케 하였다.

• 한국수소및신에너지학회논문집
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• 제19권1호
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• pp.56-63
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• 2008

In this study, thermochemical degradation of hemicellulose by Acetone-Solvolysis, the effects of reaction temperature, conversion yield, degradation properties and degradation products were investigated. Experiments were performed in a tube reactor by varying reaction temperature from $200{\circ}C$ to $400{\circ}C$ at 40 min of reaction time. The liquid products from pyrolysis-liquefaction of hemicellulose contained various kinds of ketones. ketones, as 4-methyl-3-penten-2-one, 3-methylene-2-pentanone, 22,6-dimethyl-2, 5-heptadien-4-one, 4-methyl-2-pentanone, 5-methyl-2-hexanone, 3,5,5-trimethyl-2-cyclohexen-1-one, and bezenes. as 1,4-dimethylbenzene, 1-methyl-2-(1-methylethyl)-benzene, 1,4-dimethyl-2-(2-methylpropyl)benzene, 4-secbutyl-ethyl benzene, could be used as high-octane-value fuels and fuel additives. Combustion heating value of liquid products from thermochemical conversion processes of hemicellulose was in the range of $6,680{\sim}7,170cal/g$. After 40min of reaction at $400{\circ}C$ in Acetone-Solvolysis of hemicellulose, the energy yield and mass yield was as high as 72.2% and 41.2g oil/100g raw material, respectively.