• 대한기계학회논문집B
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• 제27권5호
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• pp.589-595
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• 2003

DME(Dimethyl ether) is an oxygenated fuel with a octane number higher than that of diesel oil. It meets the ULEV emission regulation and reduces the smoke to almost zero when used in a diesel engine. In the present study, engine performance and exhaust emissions were investigated with a conventional DI diesel engine which has a jerk type injection pump. Test results showed that the power with DME were almost same as that of pure diesel oil, and the brake thermal efficiency increased a little. Also, smoke index from DME engine showed nearly zero level, but NO$_{x}$ was increased compare to diesel oil.

• Elastomers and Composites
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• 제32권3호
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• pp.179-185
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• 1997

In solution and melting state, SiOD prepolymer was prepared by cured excess DDM with epoxy-terminated siloxane oligomers to control phase separation when DGEBA was blended with PDMS. DGEBA/SiOD prepolymer was also cured at $150^{\circ}C$ for 3hrs. Mechanical and thermal properties of the cured prepolymer specimen were investigated. DGEBA/SiOD60 specimen blended SiOD prepolymer had the best flexural strength, modulus and impact strength. To show crack-formation procedure to morphology, DGEBA/DDM neat specimen was flowed homogeneously in direction of crack energy, whereas DGEBA/SiOD$(30{\sim}60)$ specimen showed heterogeneously dispersed particles and scattered domain of crack energy, but DGEBA/SiOT specimen showed homogeneous phase.

• 설비공학논문집
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• 제18권6호
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• pp.493-500
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• 2006

This paper concerns the measurement of thermal conductivity of grouting materials for ground loop heat exchanger. A thermal conductivity meter, QTM-500 based on modified transient hot wire method was used to measure the thermal conductivity of neat bentonite and mixtures of bentonite and various additives. Relative to the total mixture mass, as the percent additive was increased the mixture thermal conductivity increased. For the bentonite-silica sand mixtures, the higher density of the sand particles resulted in much higher mixture thermal conductivity. The quartzite and silica sands produced the largest increases in mixture thermal conductivity, while common masonry and limestone sands produced lower thermal conductivity increases.

• 대한핵의학회:학술대회논문집
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• 대한핵의학회 2002년도 제23차 연수교육
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• pp.77-95
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• 2002

During the last several decades, prognosis of differentiated thvroid cancers improved markedly, mainly due to refinement of surgical techniques and routine use of radioactive iodine. Total or neat-total thyroidectomy is to be performed as the first line of treatment. Routine remnant ablation just after surgery decreases recurrence and increases survival. After then patients are maintained on suppressive dose of thyroid hormone to keep endogenous TSH below normal. Regular follow-up of the patients with serum thyroglobulin measurement and iodine whole body scan after thyroid hormone withdrawal or under recombinant human thyrotropin stimulation select high risk patients with recurrence or metastatic disease and treatment with therapeutic dose of radioactive iodine prolongs survival and sometimes leads cure. Currently recommended diagnostic and therapeutic strategies, present controversies and future directions are discussed.

• Kyungpook Mathematical Journal
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• 제18권2호
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• pp.211-215
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• 1978

In the present paper, we obtain two new and interesting finite summation formulae for the H-function of two variables in a very neat and elegant form. The novel feature of the paper is that the method used here in deriving these formulae is simple and direct and does not impose heavy restrictions on the parameters involved. On account of the most general nature of the H-function of two variables, a number of related finite summation formulae for a number of other useful functions can also be obtained as special cases of our results. As an illustration, we have obtained here from our main results, the corresponding finite summation formulae for $Kamp{\acute{e}}$ de $F{\acute{e}}riet$ function. Appell's function and Gauss' hypergeometric function which are also believed to be new.

• 한국미생물·생명공학회지
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• 제22권5호
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• pp.531-537
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• 1994

This study was undertaken with objective of optimizing the conditions of fermentation in an aqueous two-phase system which is composed of polyethylene glycol (PEG) 20000 and crude dextran (Dx). The data were obtained and analyzed using the Box-Wilson's experimental design protocol and the response surface methodology. To reach this end a multilinear polynomial regres- sion model was developed, which can be utilized for the purpose of optimizing the extractive fermentation. Optimum conditions for batch fermentation with aqueous two phase system were found to be at 4.2~5.4% PEG/3.2~4.2% Dx range. The composition of the center was 4.8% PEG/ 3.6% Dx. Optimum operating conditions for initial sugar concentration and fermentation time were approximately 160 g/l, and 21~22 hr, respectively. Fermentation in the aqueous two phase system composed of 5% PEG/4% Dx showed increase of 23% in ethanol concentration, of 9.5% in ethanol yield, and of 19% in ethanol productivity as compared to the case of fermentation of neat Jerusalem artichoke juice.

• Korea-Australia Rheology Journal
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• 제20권4호
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• pp.227-233
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• 2008

High impact polystyrene (HIPS)/organoclay nanocomposites via in situ polymerization were synthesized and their rheological properties were investigated. For the study, two types of organoclays were used: a commercially available organoclay, Cloisite 10A (C10A), and a laboratory-prepared organoclay having a reactant group, vinylclay (ODVC). The X-ray diffraction and transmission electron microscopy experiments revealed that the HIPS/ODVC nanocomposite achieved an exfoliated structure, whereas the HIPS/C10A nanocomposite achieved an intercalated structure. In the small-amplitude oscillatory shear experiments, both storage modulus and complex viscosity increased with increasing organoclay. A pronounced effect of the organoclay content was observed, resulting in larger storage modulus and stronger yield behavior in the low frequency region when compared to neat HIPS. The crossover frequencies associated with the inverse of a longest relaxation time decreased as the organoclay content increased. Over a certain value of ODVC content, a change of pattern in rheological properties could be found, indicating a solid-like response with storage modulus greater than loss modulus at all frequencies.

• 한국가구학회지
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• 제12권2호
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• pp.61-71
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• 2001

In furniture design, it is very important to choose adequate materials. Transparent materials provide expectations and reveals unique effects unlike others. As transparent materials, glass and acrylic have light and fresh impression from their transparency, and are frequently used in structuring neat space. Despite its good merits, glass is not able to satisfy designers desire in making various shape and structure. It has defect in manufacturing process because it requires professional, specialized studio. Compared to glass, acrylic has its merit in processing and stability, and also is very economical. Acrylic is easily used with woodworking tool. In addition, acrylic has unique texture. This study is on the attempt to apply acrylic to the furniture as artistic element.

• 한국의류학회지
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• 제26권11호
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• pp.1638-1648
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• 2002

In this study, we classified adjectives to represent the image of clothing materials as the fundamental process for evaluation of the images on various fabrics and reviewed hierarchy and evaluation dimensions regarding the image of clothing materials. The adjectives to express the image of clothing materials were extracted from Fashion Magazine and Fashion Trend Book The similarity among adjectives was measured by pair-wise comparison without showing fabrics. From the result of the cluster analysis, 87 adjectives were finally extracted through the integrated processing of the adjectives with similar meaning and a close distance. Through the cluster analysis, the hierarchy of the clothing material images was examined. The clothing material images were classified into 12 primary sub-clusters such as ‘feminine', ‘warm', ‘neat', ‘classical', ‘pastoral.' ‘casual', ‘modern'. ‘ambiguous', ‘primitive', masculine', ‘abundant', and ‘arranged'. The dimensions evaluating the clothing material images were also developed using the multi-dimensional scaling method. A 4-dimensions and 8-axes system was established, which is composed of ‘masculine-feminine', ‘new-old', ‘casual-classical', and ‘ambiguous-arranged' images.

• Carbon letters
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• 제15권1호
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• pp.67-70
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• 2014

In this work, nanocomposites of epoxy resin and chemically reduced graphene oxide (RGO) were prepared by thermal curing process. X-ray diffractions confirmed the microstructural properties of RGO. Differential scanning calorimetry was used to evaluate the curing behaviors of RGO/epoxy nanocomposites with different RGO loading amounts. We investigated the effect of RGO loading amounts on the mechanical properties of the epoxy nanocomposites. It was found that the presence of RGO improved both flexural strength and modulus of the epoxy nanocomposites till the RGO loading reached 0.4 wt%, and then decreased. The optimum loading achieved about 24.5 and 25.7% improvements, respectively, compared to the neat-epoxy composites. The observed mechanical reinforcement might be an enhancement of mechanical interlocking between the epoxy matrix and RGO due to the unique planar structures.