• 대한기계학회논문집
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• 제15권1호
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• pp.355-365
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• 1991

본 연구에서는 화염간 상호 작용을 해석함으로써 정의 적용에 있어서의 적절 성과 유용성을 검토 하고 화염간 상호 작용 특성을 밝히기 위하여, 해석의 대상은 화 염간의 상호작용을 명확히 관찰할 수 있는 두 개의 평행한 사각 덕트형 노즐로부터 분 출되는 기체연료에 의해 형성 되는 두 개의 동등한 3차원 제트 난류 확산화염을 택한 다. 2-화염계는 상호작용 화염군의 기본 단위이며, 현재까지 원형제트 화염에 비하 여 3차원제트 화염에 대한 연구는 많지 않은 실정이다. 연구의 방법으로는 이론적 모델링과 수치해석을 통한 모의 실험에 중점을 두고 부분적인 실험으로 타당성을 점검 한다.이는 기존의 연구들이 대부분 실험적인 것들이거나 간단한 해석적 모델을 사 용한 것들이어서 상호 작용하의 화염 특성을 예측할 수 있는 수치 해석적 모델의 개발 이 필요하며, 또한 기존의 연구들이 온도나 성분만을 측정함으로서 유동장에서의 운동 량 전달의 상호작용 특성이 자세히 연구되지 못했으므로, 이를 위해서는 난점이 있는 속도 측정의 실험적 방법보다 수치해석적 접근법이 필요하기 때문이다. 이상과 같이 본연구는 상술한 정의를 적용해 보고 이에따라 화염간 상호작용의 특성을 파악하며 이 를 예측할 수 있는 이론적 모델을 개발하는 것을 목적으로 한다.

• Restorative Dentistry and Endodontics
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• 제27권4호
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• pp.411-420
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• 2002

The aim of this study is to compare the adaptability of thermoplasticized injectable gutta-percha technique to the canal walls in ribbon-shaped canals. Thirty resin models simulated ribbon-shape canals were instrumented to #40 using .06 taper Profile systems. Three groups of each 10 resin models were obturated by the lateral condensation technique(LC) and the two thermoplasticized injectable gutta-percha technique; Ultrafil Endoset+Obtura II(EO) and Ultrafil Firmset(UF), respectively. After resin model were kept at room temperature for 4 days, they were resected horizontally with micro-tome at 1, 2, 3, 4 and 5mm levels from apex. At each levels. image of resected surface were taken using CCD camera under a stereomicroscope at $\times$40 magnification and stored. Ratio of the area of gutta-percha was obtained by calculating area of gutta-percha cone to the total area of canal using digitized image-ana-Iyzing program. The data were collected then analyzed statistically using One-way ANOVA. The results were as follows. 1 At 1mm levels, there was no statistically significant difference in the mean ratio of gutta-percha among the groups. 2. At 2mm level, EO showed the highest mean ratio of gutta-percha (p<0.05) and there was no significant difference between LC and UF. 3. At 3, 4, 5mm levels, EO and UF had significantly greater mean ratio of gutta-percha than LC(p<0.05) and there was no significant difference between EO and UF. In conclusion, the thermoplasticized injectable gutta-percha techniques demonstrated relatively favorable adaptability to canal walls than lateral condensation technique in ribbon-shaped canals except for 1mm level.

• 동력기계공학회지
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• 제13권6호
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• pp.13-21
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• 2009

This basic study is required to examine spray or jet behavior depending on fuel phase. In this study, analyses of diesel fuel(n-Tridecane, $C_{13}H_{28}$) spray and natural gas fuel(Methane, $CH_4$) jet under high temperature and pressure are performed by a general-purpose program, ANSYS CFX release 11.0, and the results of these are compared with experimental results of diesel fuel spray using the exciplex fluorescence method. The simulation results of diesel spray is analyzed by using the combination of Large-Eddy Simulation(LES) and Lagrangian Particle Tracking(LPT) and of a natural gas jet is analyzed by using Multi-Component Model(MCM). There are two study variables considered, that is, ambient pressure and injection pressure. In a macroscopic analysis, the higher ambient pressure is, the shorter spray or jet tip penetration is at each time after start of injection. And the higher injection pressure is, the longer spray or jet tip penetration is at each time after start of injection. When liquid fuel is injected, droplets of the fuel need some time to evaporate. However, when natural gas fuel is injected, the fuel does not need time to evaporate. Gas fuel consists of minute particles. Therefore, the gas fuel is mixed with the ambient gas more quickly at the initial time of injection than the liquid fuel is done. The experimental results also validate the usefulness of this analysis.

• 대한기계학회논문집B
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• 제23권8호
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• pp.1040-1047
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• 1999

The characteristics of flame propagation in inert particle-laden $H_2$/Air premixed gas are numerically investigated on this study. The 2nd order TVD scheme is applied to numerical analysis of governing equations and multi-step chemical reaction model and detailed transport properties are sued to solve chemical reaction terms. Radiation heat transfer is computed by applying the finite volume method to a radiative transfer equation. The burning velocities against the mole fractions of hydrogen agree well with results performed by different workers. The inert particles play significant roles in the flame propagation on account of momentum and heat transfer between gas and particles. Gas temperature, pressure and flame propagation speed are decreased as the loading ratio of particle is increased. Also the products behind flame zone contain lots of water vapor whose absorption coefficient is much larger than that of unburned gas. Thus, the radiation effect of gas and particles must be considered simultaneously for the flame propagation in a mixture of $H_2$/Air and inert particles. As a result, it is founded that because the water vapor emits much radiation and this emitted radiation is released at boundaries as radiant heat loss as well as reabsorbed by gas and particles, flame propagation speed and flame structure are altered with radiation effect.

• 한국자동차공학회논문집
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• 제18권5호
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• pp.85-90
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• 2010

As the environmental regulation of vehicle emission is strengthened, investigations for $NO_x$ and PM reduction strategies are popularly conducted. Two current available technologies for continuous $NO_x$ reduction onboard diesel vehicles are Selective Catalytic Reduction (SCR) using aqueous urea and lean $NO_x$ trap (LNT) catalysts. The experiments were conducted to investigate the $NO_x$ reduction performance of SCR system which can control the ratio of $NO/NO_2$, temperature and SV(space velocity), and the model gas was used which is similar to a diesel exhaust gas. The maximum reduction efficiency is indicated when the $NO:NO_2$ ratio is 1:1 and the SV is 30,000 $h^{-1}$ in $300^{\circ}C$. Generally, ammonia slip from SCR reactors are rooted to incomplete conversion of $NH_3$ over the SCR. In this research, slip was occurred in 6cases (except low SV and $NO:NO_2$ ratio is 1:1) after SCR. Among 6 case of slip occurrence, the maximum conversion efficiency is observed when SV is 60,000 $h^{-1}$ in $400^{\circ}C$.

• 한국식품과학회지
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• 제5권2호
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• pp.89-94
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• 1973

육제품(肉製品)의 착색제(着色劑)로 사용되고 있는 식용적색2호(食用赤色2號)와 황색4호(黃色4號)의 가열(加熱) 및 감마(線) 조사(照射)에 의한 변색정도(變色程度)와 첨가물(添加物)에 의한 영향을 model system 을 사용하여 관찰하였다. 황색2호(黃色2號)는 가열(加熱)에 의하여 뚜렷한 변색(變色)을 나타내지 않았으나 황색4호(黃色4號)는 Na-TPP 와 cinnamon oil 을 첨가(添加)하므로써 약간의 퇴색(褪色)을 하였다. 감마선(線) 조사(照射)에 의한 영향은 선량(線量)의 증가와 더불어 퇴색(褪色)하였으며 $NaNO_2$ 와 ascorbic acid 는 퇴색(褪色)을 억제하는 반면 Na-TPP 와 cinnamon oil 은 오히려 촉진하는 경향을 보였다. 이러한 퇴색도(褪色度)는 적색2호(赤色2號)보다는 황색4호(黃色4호(號)가 더욱 현저하였으며 $5^{\circ}C$ 보존(保存)보다는 $25^{\circ}C$보존(保存)에서 퇴색(褪色)이 촉진되었다.

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2005년도 International Meeting of the Microbiological Society of Korea
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• pp.159-161
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• 2005

Hypovirus infection of the chestnut blight fungus Cryphonectria parasitica is a useful model system to study the hypoviral regulation of fungal gene expression. The hypovirus is known to downregulate the fungal laccase1 (lac 1), the modulation of which is tightly governed by the inositol triphosphate ($IP_3$) and calcium second messenger system in a virus-free strain. We cloned the gene cplc1 encoding a phosphatidyl inositol-specific phospholipase C (PLC), in order to better characterize the fungal gene regulation by hypovirus. Sequence analysis of the cplc1 gene indicated that the protein product contained both the X and Y domains, which are the two conserved regions found in all known PLCs, with a 133 amino acid extension between the 2nd ${\beta}$-strand and the ${\alpha}$-helix in the X domain. In addition, the gene organization appeared to be highly similar to that of a ${\delta}$ type PLC. Disruption of the cplc1 gene resulted in slow growth and produced colonies characterized by little aerial mycelia and deep orange in color. In addition, down regulation of lac1 expression was observed. However, temperature sensitivity, osmosensitivity, virulence, and other hypovirulence-associated characteristics did not differ from the wild-type strain. Functional complementation of the cplc1-null mutant with the PLC1 gene from Saccharomyces cerevisiae restored lac1 expression, which suggests that the cloned gene encodes PLC activity. The present study indicates that the cplc1 gene is required for appropriate mycelial growth, and that it regulates the lac1 expression, which is also modulated by the hypovirus. Although several PLC genes have been identified in various simple eukaryotic organisms, the deletion analysis of the cplc1 gene in this study appears to be the first report on the functional analysis of PLC in filamentous fungi.

• 에너지공학
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• 제12권1호
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• pp.35-41
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• 2003

본 연구에서는 배가스의 현열회수를 통해 연소기기의 열효율을 향상시키는 축열연소시스템에서 구형축열체를 이용한 축열기내 열유동을 해석할 수 있는 수치해석 코드를 개발하였다. 이를 통해 축열기내 비정상 열유동을 해석하고 축열기 길이를 포함한 축열기 형상과 축열체 구경에 따른 배열회수와 압력손실의 관계를 파악해 보았다. 수치해석은 1차원 2상 유체역학 모델을 도입하여 MacCormack방식으로 해를 얻었으며, 실험적 경향과 일치함을 알 수 있었다. 개발된 수치코드를 통해 얻은 결론은 축열기 길이가 길고 입자구경이 작으며 축열기내 유체 유속이 빠른 경우에 많은 배열을 회수할 수 있으나 압력손실이 커짐을 알 수 있었다.

• 한국근적외분광분석학회:학술대회논문집
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.1519-1519
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• 2001

The aim of this work was to test the feasibility of NIRS in analysing textural characteristics of “Pasta Filata” cheese during the shelf-life. For this purpose, 128 samples of “Pasta Filata” cheese, subdivided into two sets on the basis of the wax used to avoid mechanical damages (paraffin, biodegradable wax), were analysed by using an InfraAlyzer 500 (Bran+Luebbe). Analyses were performed at room temperature. Samples were cut into small cylinders (D=3.2 cm, height = 1 cm), in agreement with literature information. Data were processed by using Sesame Software (Bran+Luebbe). Samples were analysed, during the shelf-life, at 90 and 120 days. In parallel, textural characteristics were detected carrying out a compression method by using an Universal Testing Machine Instron model 4301 (Instron Corporation, Canton, Massachusetts). As compression probe was used a cylinder (D = 5.8 cm, height = 3.7 cm) and a speed rate of 20mm/min was applied. The load at 20 mm of compression was recorded on sample cylinders of 1.7 cm (D) by 2 cm (height). Qualitative analysis of full spectra showed the possibility to gather samples on the basis of the days of shelf-life. The textural characteristics of cheese during the shelf-life was evaluated by comparing NIRS data with rheological results. The best correlation was obtained applying MLR to the first derivative of normalized absorbance values at seven wavelengths. Load values were plotted against the NIR prediction values based on first derivatives. NIRS proved to be an useful tool in classifying samples on the basis of the shelf-life period as well as in predicting their textural characteristics ($R^2$= 0.916, SEC = 0.192, SEP = 0.248, SEV = 0.345).

• 마케팅과학연구
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• 제12권
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• pp.121-134
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• 2003

기상마케팅은 기상 상태의 변화에 따른 소비자의 욕구와 구매행태의 변화를 기업의 마케팅계획에 반영하려는 노력으로 빙과류, 맥주나 음료 에어컨, 방한의류 등과 같은 계절적 상품들에서 일찍부터 중요성이 인식되어져 활용되어져 왔다. 그러나 기상요인의 영향력에 대한 연구는 기업의 사내 보고서 형태로 이루어져 왔으며 주요 기상요인들이 제품판매에 미치는 영향에 대한 학문적인 접근은 거의 이루어지지 않은 상태이다. 이에 본 연구에서는 국내 주요 백화점에서 판매되는 다앙한 패션의류제품올 대상으로 일별 매출데이터와 기상특성자료들간의 관계를 체계적으로 분석하였다. 특히 기상요인들이 매출에 미치는 영향이 어느 정도인지를 파악하기 위해 백화점의 주요 판매촉진 수단인 정기세일과 사은품 증정의 효과와 비교함으로서 기상요인의 영향력을 평가하였다. 분석결과 패션제품 매출에 있어 기상요인들은 정기세일보다는 낮지만 사은품증정과 유사한 수준의 효과를 갖고 있는 것으로 나타났으며, 기상요인들중 기온, 강수량, 바람이 매출에 유의한 영향을 미치는 것으로 나타났다. 그러나 기상요인의 구체적인 효과는 계절에 따라, 복종별로 상이하게 나타나 향후 의류제품 판매에 있어 기상마케팅의 적용은 시즌과 제품특성을 반영한 체계적인 예측모형의 구측과 적용이 필요한 것으로 나타났다.