• Transactions of the Korean Society of Automotive Engineers
• /
• v.12 no.6
• /
• pp.46-53
• /
• 2004

Heat release analysis is a very important method for understanding the combustion phenomena inside an engine cylinder. In this study, one-zone heat release analysis was used with the measured cylinder pressures of a HSDI(high speed direct injection) and IDI(indirect injection) diesel engines, Those have benefits of simple equation, fast speed, reliability. The objective of the study is to compare the combustion characteristics between a HSDI and an IDI. The result shoes that the maximum heat release rate of a HSDI is higher than that of an IDI because of long ignition delay period. The heat release curve of an IDI is more linear than that of a HSDI, thus is similiar to that of a SI engine. The combustion efficiency of a HSDI is higher than that of an IDI because of the smaller heat transfer loss of a HSDI. There is a suggestion here that an IDI engine has broad heat transfer area which include two combustion chambers, the connection passage of combustion chambers, etc.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.13 no.6
• /
• pp.21-30
• /
• 2005

Heat release analysis is a very importent method in understanding the combustion phenomena inside an engine cylinder. In this study, one-zone heat release analysis was used with the mesured cylinder pressures of an IDI(indirect injection), a HSDI(high speed direct injection) and a SI(spark ignition) engine. It has benefits of simple equation, fast speed, reliability. The object of the study is to compare the combustion characteristics among an IDI, a HSDI and SI engine. Result of analysis, the maximum heat release rate of a HSDI is higher than an IDI because of long ignition delay period. The heat release curve of a IDI is more linear than an HSDI, so the combustion characteristics of a IDI is similiar to that of an SI engine. There is a suggestion here that the combustion efficiency of a HSDI is highest of that of all engines because of the smallest heat transfer loss of all engines.

• Fire Science and Engineering
• /
• v.34 no.1
• /
• pp.18-25
• /
• 2020

In this study, the heat release rate of pipe insulation is analyzed by considering the installation status in accordance with the standards ISO 20632 and NFPA 274. The flame retardation rate was evaluated for six types of test samples: polyethylene foam covered with beaten silver (PE(S)), PE foam tapped (PE(N)), elastomeric closed cell thermal insulation (rubber), Japanese PE foam (PE(J)), Japanese polyurethane foam (PU(J)), and Japanese styro form (ST(J)) by EN 13501-1 and fire growth curve. The results show that PU(J), PE(J), and PE(N) were Class E and ultra-fast, NFPA 274 test standards for Class D and Fast, and PE(S) by ISO 20632 were Class C and Slow, and Rubber and ST(J) were Classes and Low. However, the changes in the time-averaged maximum heat release rate for each test standard (ISO 20632 and NFPA 274) to evaluate the flame retardation rate differed among identical materials. This means that the fundamental study is necessary to analyze the more accurate reasons.

• Carbon letters
• /
• v.11 no.2
• /
• pp.122-126
• /
• 2010

The alginate-based hydrogel was prepared as a pH-sensitive drug delivery system. To enhance the drug loading capacity, activated carbon was introduced as a drug absorbent. The iron oxide was incorporated into the alginate matrix for the magnetic transferring to the target organ. The activated carbon and iron-oxide were dispersed uniformly in the alginate hydrogel. The drug release from the alginate/activated carbon composite hydrogel was carried out in various pH conditions with vitamin B12 and Lactobacillus lamnosers as model drugs. The fast and sustainable release of drug was observed in the basic condition due to the pH-sensitive solubility of alginate. The novel drug delivery system having pH-sensitive release property and magnetic movement to target place was developed by using the alginate/activated carbon composite magnetic hydrogels.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.27 no.2
• /
• pp.312-316
• /
• 2013

Caffeine is a thermogenic agent that can be used in weight loss products. In order to achieve a sustained release of caffeine, silk fibroin (SF) film was uses as carrier. It has been shown that the loading method of caffeine into SF film affected the uniform distribution of caffeine in the SF film. When caffeine was added directly into SF solution, gelation has been occurred immediately and prevented the uniform distribution of caffeine. On the other hand, caffeine was dissolved in methanol in order to load the caffeine in SF film and crystallize the SF film at the same time. However, due to the fast evaporation of methanol, caffeine was recrystallized on the surface of SF film rather than penetrating into the film. Finally, caffeine was loaded into pre-crystallized SF film and uniform distribution of caffeine could be achieved. There was an initial burst of caffeine during the first 15 min, but after that a sustained release was achieved.

• Nuclear Engineering and Technology
• /
• v.54 no.4
• /
• pp.1195-1205
• /
• 2022

Recent developments on spectral diffusion algorithms, i.e., algorithms which exploit the projection of the solution on the eigenfunctions of the Laplacian operator, demonstrated their effective applicability in fast transient conditions. Nevertheless, the numerical error introduced by these algorithms, together with the uncertainties associated with model parameters, may impact the reliability of the predictions on short-lived volatile fission product release from nuclear fuel. In this work, we provide an upper bound on the numerical error introduced by the presented spectral diffusion algorithm, in both constant and time-varying conditions, depending on the number of modes and on the time discretization. The definition of this upper bound allows introducing a methodology to a priori bound the numerical error on short-lived volatile fission product retention.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.33 no.1
• /
• pp.25-34
• /
• 2006

Fluoride released from dental restorative materials effectively declines the incidence and activity of dental caries and inhibits tooth demineralization. This study investigated the fluoride release and uptake characteristics of one composite resin $(Z-250^{TM})$ three glass ionomer-based restorative material ($Dyract^{(R)}$ AP, Fuji II $LC^{(R)}$, Fuji IX GP $Fast^{(R)}$) Forty discs(6mm diameter and 1mm height) were prepared for each material. Each disc was immersed in 5ml of distilled water within polyethylene vial and stored at $37^{\circ}C$. The distilled water was changed every 24 hours and the release of fluoride was measured for 31 days. At the end of this period, each specimen was subjected to one of four treatments : (A) no fluoride treatment (control), (B) application of a fluoride dentifrice (500ppm) for three minutes three times; (C) application of the 1.23% acidulated phosphate fluoride(APF) foam for one minute once, (D) the same regimen as (B), plus application of the APF foam for one minute once. Then, all samples were reassessed for an additional 7 days. For all samples, the greatest fluoride release was observed after the first day of the study but diminished with time. On the 7th day of the study, fluoride release level was stabilized. Fuji II $LC^{(R)}$ and Fuji IX GP $Fast^{(R)}$ released higher amount of fluoride than other materials ; however, no statistically significant difference was found from Fuji II $LC^{(R)}$ and Fuji IX GP $Fast^{(R)}$. The amount of fluoride of $Dyract^{(R)}$ AP, Fuji II $LC^{(R)}$ and Fuji IX GP $Fast^{(R)}$ was increased after fluoride treatment, and diminished with time.

• Proceedings of the Turfgrass Society of Korea Conference
• /
• 2005.04a
• /
• pp.26-27
• /
• 2005

• Korean Journal of Applied Biomechanics
• /
• v.14 no.3
• /
• pp.149-163
• /
• 2004

This study analyzed kinematic variables about the cross step, the delivery and the release for women's javelin athletics recorded over 50m in the 2004 Busan International Athletics Competition. It was used the Kwon3D Motion Analysis Package Ver. 3.1 Program(Kwon, 2000) for analysing the kinematic variables about the distance, the velocity, and the angle, then we had the results as follows; 1 In the Cross step phase, the COG velocity was low because their step length was short. To keep the CM velocity from the approach to the last cross over step contact, the athletes have to keep the longer step length within about 130% of the athletics' height. 2. In the Delivery phase, the athletics' COG height was gradually lower, and the deceleration of the COG was going up. As the same in the cross step, Therefore the athletes have to increase the step length within about 100% of their height, in order to increasing the COG velocity. And it was shown they have to make small angle of the elbow as possible from the right foot contact to the left foot contact in order to being the big acceleration of the upperarm at the release phase. 3. In the release phase, it was shown to being low position of the release point as the COG was low and then the release velocity of the upperarm was low. Specially when the shoulder lean lateral angle is big at the release phase, it was shown they have a excessive release angle. And, when it was shown the high rotation angle of the shoulder, the shoulder was opened forward bigger than the trunk was opened forward. So the transmission of velocity from the proximal segments was a fast change.

• Journal of Pharmaceutical Investigation
• /
• v.32 no.3
• /
• pp.199-207
• /
• 2002

In order to develop a sustained release formulation of bovine somatotropin (BST), which has been used to increase the body weight of oxen or the milk production of dairy cows, poly(D,L-lactide-co-glyceride)(PLGA) microspheres were made by W/O/W multiple emulsification method and solvent extraction method. Physical properties including particle size, drug entrapment, drug release, protein denaturation, and in vivo body weight increase in rats were characterized. The size of the microspheres was increased as the molecular weight of PLGA increased. When Span 65 and stearic acid during preparation were added, the size was decreased but the amount of surface protein was increased, resulting in a high loading efficiency, with fast release of BST from the microspheres. Aggregation or fragmentation of BST by SDS-PAGE during microsphere preparation and drug release study was not observed. Body weight of Sprague-Dawley's male rats was significantly increased after subcutaneous administrations of BST-loaded PLGA microspheres. There was a good correlation between in vivo weight gain and in vitro release rate of microspheres. PLGA microspheres with a high surface protein ratio could be a good candidate for the sustained delivery of BST.