• Journal of the Korea institute for structural maintenance and inspection
• /
• v.21 no.4
• /
• pp.104-109
• /
• 2017

It is important to keep the distribution of the raw material mixture constant, in order to maximize the effect of the pre-mix type repair mortar, and it is also necessary to increase the performance of the mixer in order to minimize the deviation of the product. In this study, three kinds of mixer used in production sites were used to make repair mortar and the properties of each mortar were examined. As a result, it is confirmed to the difference in properties of pre-mix type repair mortar differ depending on the type of mixer, and the fluidized zone mixer showed relatively good results. In addition, it is preferable to set the mixing time to about 10 minutes to 15 minutes in order to ensure workability and optimum physical properties.

• Asian-Australasian Journal of Animal Sciences
• /
• v.15 no.12
• /
• pp.1754-1759
• /
• 2002

A study was carried out to investigate the nutritive value and utilization of hybrid sorghum and perennial grass species viz. setaria (Setaria anceps) and hybrid napier when intercropped with soybean by growing Jersey crossbred heifers. Fifteen growing crossbred heifers (Jersey${\times}$Red Sindhi) of between 7-10 months age and pre-trial average body weight of 49-50 kg were divided on the basis of weight in to three treatment groups viz. $T_1$-hybrid sorghum+soybean, $T_2$-setaria+soybean and $T_3$-hybrid napier+soybean in a completely randomized block design. Intercropped forages were harvested fresh, chaffed and mixed before they were offered to the heifers. Chemical composition of the herbage, dry matter intake (DMI), body weight gain and nutrient digestibility co-efficients were estimated. The herbage mixtures had crude protein (CP) content in the range of 11.87 to 13.86% and ether extract (EE) contents were 2.91 to 3.11%, respectively. The herbage mixtures were rich in minerals (ash). The gross energy (kcal/g DM) was higher in hybrid napier+soybean, while hybrid sorghum+soybean and setaria+soybean herbage mixtures had lower value for gross energy. The hybrid sorghum+soybean and setaria+soybean herbage mixtures had higher contents of NDF, ADF, cellulose, lignin and silica as compared to that of hybrid napier+soybean herbage mixture. The heifers fed hybrid napier+soybean herbage mixture had significantly (p<0.05) higher $DMI\;g/kg\;W^{0.75}$ ($97.41{\pm}4.34$) as compared to hybrid sorghum+soybean ($88.31{\pm}2.66$) and setaria+soybean ($79.29{\pm}1.06$) herbage mixtures. Nutrients digestibility, DCP percent, DCP intake and nitrogen balance were significantly (p<0.05) higher in the heifers fed on hybrid napier+soybean herbage mixture. There was a significant (p<0.05) difference among different herbage mixtures in TDN. The heifers on setaria+soybean herbage mixture had lower average body weight gain (g/day) than those on hybrid sorghum+soybean and hybrid napier+soybean herbage mixtures. Data obtained in this experiment demonstrated that herbage mixture of hybrid napier+soybean was better than hybrid sorghum+soybean and setaria+soybean herbage mixtures in the nutrition of growing heifers. It had highest nutritive value, better digestibility co-efficients which showed better growth rate and higher feed efficiency. In ranking, hybrid napier+soybean herbage mixture was better followed by hybrid sorghum+soybean and setaria+soybean in nutritive value in the parameters studied. For future wasteland development program in humid-sub tropics of Himachal Pradesh hybrid napier and its intercropping with soybean is recommended for general adoption because of its better adaptability and higher nutritive value.

• Journal of Veterinary Clinics
• /
• v.36 no.1
• /
• pp.46-52
• /
• 2019

Pimobendan has inotropic and vasodilating effects on cardiovascular system, and pentoxifylline is known to decrease blood viscosity and improve blood flow to the heart. This study investigated the pharmacokinetics and pharmacodynamics following oral administration of pimobendan-pentoxifylline powder mixture in dogs. Eight healthy dogs were included and were divided into control (n = 4) and experimental (n = 4) groups. Vehicle powder and pimobendan-pentoxifylline powder mixture (pimobendane 0.25 mg/kg, pentoxifylline 15 mg/kg) were administrated orally to control and experimental groups, respectively. Plasma samples and measurement of echocardiographic indices were obtained for 24 hours following administration. Pimobendan and pentoxifylline concentrations were investigated using liquid chromatography-mass spectrometer (LC-MS) assay. The elimination half-life ($T_{1/2}$) were $2.65{\pm}1.42hours$ for pimobendan and $0.29{\pm}0.23hours$ for pentoxifylline. The time to reach maximum concentration ($T_{max}$) were $1.08{\pm}0.72hours$ for pimobendan and $0.29{\pm}0.14hours$ for pentoxifylline. The maximum blood concentration ($C_{max}$) were $2.83{\pm}1.50ng/mL$ for pimobendan and $1184.33{\pm}932.37ng/mL$ for pentoxifylline. Among echocardiographic indices, fractional shortening (FS), left ventricular internal diameter at end systole (LVIDs), and pre-ejection period (PEP) showed significant changes at 1-4 hours after the administration of pimobendan-pentoxifylline powder mixture. No adverse effects were observed during the investigation. This study demonstrates that pimobendan-pentoxifylline powder mixture can be used to control cardiovascular diseases in dogs.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.12 no.2
• /
• pp.45-53
• /
• 2004

An experimental study was carried out to obtain the fundamental data about the effects of radicals induced injection on premixture combustion. A constant volume combustor divided to the sub-chamber and the main chamber was used. The volume of the sub-chamber is set up to occupy less than 1.5％ of that of whole combustion chamber. Radial twelve narrow passage holes are arranged between the main chamber and the sub-chamber. The products including radicals generated by spark ignition in the sub-chamber will derive the simultaneous multi-point ignition in the main chamber. While the equivalence ratio of pre-mixture in the main chamber and the sub-chamber is uniform. We have examined the effects of the sub-chamber volume, the diameter of passage hole, and the equivalence ratio on the combustion characteristics by means of burning pressure measurement and flame visualization. In the case of radical ignition method(RI), the overall turning time including the ignition delay became very short and the maximum burning pressure was slightly increased in comparison with those of the conventional spark ignition method(SI), that is, single chamber combustion without the sub-chamber. The combustible lean limit by RI method is extended to more ER=0.25 than that by SI method. Therefore the decrease of every emission including NOx and the improvement of fuel consumption is anticipated due to lean burn.

• Transactions of the Korean hydrogen and new energy society
• /
• v.31 no.1
• /
• pp.49-56
• /
• 2020

Epoxy/carbon composite was used to prepare a bipolar plate for polymer electrolyte membrane fuel cell (PEMFC). Phenol novolac-type epoxy and diglycidyl ether of bisphenol A (DGEBA)-type epoxy mixture was used as a matrix and graphite powder, carbon fiber (CF) and graphite fiber (GF) were used as carbon materials. In order to improve the mechanical properties of the bipolar plate, surface-modified CF was incorporated into the epoxy/carbon composite. To determine the cure temperature of the epoxy mixture, differential scanning calorimetry (DSC) analysis was performed and the data were introduced to Kissinger equation in order to get reaction activation energy and pre-exponential factor. Tensile and flexural strength was obtained by using universal testing machine (UTM). The surface morphology of the fractured specimen and the interfacial morphology between epoxy matrix and CF or GF were observed by a scanning electron microscopy (SEM).

• Journal of Mechanical Science and Technology
• /
• v.18 no.9
• /
• pp.1623-1629
• /
• 2004

The objective of this study is the rapid bulk combustion of mixture in a constant volume chamber with a tiny sub-chamber. Some narrow passage holes were arranged to induce simultaneous multi-point ignition in the main chamber by jet of burned and unburned gases including radicals from the sub-chamber, and the equivalence ratios of pre-mixture in the main chamber and the sub-chamber were the same. The principal factors of the Radical Induced Auto-Ignition (RIAI) method are the diameter of the passage holes and the volume of sub-chamber. The relationship between the sub-chamber and diameter of passage hole was represented by the ratios of sub-chamber volume to passage hole volume. The ratios are non-dimensional coefficients for sub-chamber characteristics. As a result, the RIAI method reduced the combustion period, which expanded the lean limit in comparison with SI method.

• Journal of Korean Society for Atmospheric Environment
• /
• v.12 no.3
• /
• pp.269-278
• /
• 1996

Airborne suspended particulates were collected by an Andersen high volume air sampler in a traffic area of Seoul from September 1990 to August 1991. Origanic matter extracted from particulates, their fractions, namely acidic, basic, neutral and carcinogenic subfractions (PAHs, nitroarenes) in neutral fractions were assayed for mutagenicity on TA98, TA100 and TA98NR deficient Salmonella strains, use of the pre-incubation method. The relative contribution to total mutanenicity of organic matters was highest in neutral fraction and was lowest in basic fraction. Among subfractions, that of neutral fraction was higher nitroarenes subfraction compared to PAHs subfraction. While the carcinogenic effect of benzo[a]pyrene was calculated as 0.96 persons/million persons based on unit risk estimates by extrapolation method, life time excess cancer risk estimate of EOM, neutral, PAH fraction based on their mutagenicity was calculated as 52, 42, 3.8 persons/million persons, respectively. These findings indicate that the mutagenic hazard of the partciculate, air organic complex mixture, may be dependent upon the mutagen composition in the particulate and interactions each of them. Therfore, health risk from air organic complex mixtures based on mutagenicity might be useful indicator for evaluation of actual risk.

• 한국생물공학회:학술대회논문집
• /
• 2000.11a
• /
• pp.260-263
• /
• 2000

Membranes are widely used to separate target solute molecules such as proteins on the basis of their size in cell broth mixture to minimize the loss of target compounds. In this study, membrane separation system using ultrafilters of MWCO 100 K and 50 K, was operated for concentration and purification of microbial transglutaminase. Fermentation broth containing MTGase was prefiltered by using pore size 1.6 and $0.7\;{\mu}m$ pre-filter made of cellulose fiber and $0.45\;{\mu}m$ microfilter made of cellulose acetate. The prefiltered solution was concentrated by 100 K and 50 K ultrafilter. The final enzyme concentration was 1.29 units/ml and enzyme specific activity was 0.2 units/mg protein. This specific activity were 3.7 times higher than that of initial cell broth mixture. Membrane separation process of microfiltration and ultrafiltration was proved to be very economic, energy efficient and effective separation method used to concentrate MTGase.

• Journal of computational fluids engineering
• /
• v.17 no.1
• /
• pp.78-85
• /
• 2012

Cavitation causes a great deal of noise, damage to components, vibrations, and a loss of efficiency in devices, such as propellers, pump impellers, nozzles, injectors, torpedoes, etc., Thus, cavitating flow simulation is of practical importance for many engineering systems. In this study, a two-phase flow solver based on the homogeneous mixture model has been developed. The flow characteristics around an axisymmetric cylinder were calculated and then validated by comparing with the experimental results in the cavitation water tunnel at the Korea Ocean Research & Development Institute. The results show that this solver is highly suitable for simulating the cavitating flows. After the code validation, the cavity length with changes of water depth, angle of attack and velocity were obtained.. Cavitation inception was also calculated for various operational conditions.

• International Journal of Highway Engineering
• /
• v.16 no.4
• /
• pp.21-33
• /
• 2014

PURPOSES: The purpose of this study was to break away from the workforce method using cold-mix asphalt mixtures and has a constant quality and has develop repair materials of pre-production asphalt-precast types. METHODS: The selection of the repair material was determined as the results obtained through physical properties of materials and the field applicability. In case of repair materials, values obtained through Marshall stability test & the dynamic stability test & retained stability test as well as the site conditions was considered. In case of adhesive, test results were obtained through examination of the bond strength(tensile, shear) and the field applicability of the adhesive was examined through combined specimens to simulate field applications. RESULTS : According to the results of laboratory tests, in the case of repair materials, Marshall stability and dynamic stability, retained stability of cold-mix reaction type asphalt mixture is the highest. In the case of adhesive, two-component epoxy-urea has a very high bonding strength(tensile, shear) was most excellent. According to the results of field tests, when epoxy-urea was excellent workability. Also, the repair body through actual mock-up test did not occur large deformation and fracture after 12 months. CONCLUSIONS : A suitable repair material is cold-mix reaction type mixture of asphalt-precast, a suitable adhesive is a two-component epoxy-urea.