• 대한의용생체공학회:의공학회지
• /
• 제31권4호
• /
• pp.321-327
• /
• 2010

Most of the ear shells of hearing aids are manufactured manually, and it is one of the reasons that the cost of the custom-made hearing aids can be increased. Thus it is required to manufacture the ready-made ear shell for the purpose of easy manufacturing and decrease in cost. In this study, we extract parameters in order to manufacture the ready-made ear shell for CIC type hearing aids and simulate to reconstruct the ear shell using the extracted parameters. To parameter extraction, we set up the eleven parameters for the ready-made ear shell based on anatomical characteristics of the ear canal, and we found values of the parameters from twenty-one impressions in their 20s and twelve impressions in their 60s using aperture detection and feature detection algorithms. Classifying the parameters by size, we also determine the parameters of ready-made ear shell into three types for people in their 20s and two types for people in their 60s. Each ready-made ear shell was simulated to reconstruct using figured parameters, and evaluated the rate of agreement with unused impressions for setting parameters. To evaluate the ready-made ear shell, we calculate the volume ratio and intersection between of the each impression and ready-made ear shell, and the intersection ratio using the intersection volume and ready-made ear shell volume. As a result, the volume ratio was about 70%, and volume match ratio was also up to 70%. It means that the ready-made ear shell we simulated is the significantly matched to impression.

• 한국주조공학회지
• /
• 제15권2호
• /
• pp.184-193
• /
• 1995

Effects of process parameters during thixocasting, such as solid volume fraction, mold temperature and extrusion ratio, on the mold filling behaviour and fluidity of Mg alloy(AZ91D) have been investigated. The semi-solid ingot held for 60 minutes at the semi-solid temperature range did not contain the equilibrium volume fraction of solid as expected from the phase diagram. Therefore, in order to obtain the desired solid fractions, and to suppress the exaggerated grain growth during heating, it was required to heat the ingot rapidly up to the temperature $10^{\circ}C$ higher than the semi-solid temperature suggested from the phase diagram for a specific volume fraction of solid. The experimental results show that mold filling behaviour and fluidity can be improved with the use of the higher mold temperature and the lower volume fraction of solid, but remain nearly unaffected by the change of extrusion ratio.

• 한국식품영양학회지
• /
• 제14권4호
• /
• pp.305-310
• /
• 2001

In order to study bread properties utilizing extracts of fume, mume bread was baked, adding 0, 0.5, 1.0. 1.5 and 2.0 brix of mume extract to wheat flour. The rheological properties, dough pH, dough volume, bread volume, bread color. bread texture and sensory evaluation were tested to examine bread properties baked adding extracts of mume. The results are as follows: The maximum viscosity measured by amylograph decreased gradually with increasing fume extract concentration, while the gelatinization temperature was going up. The development time measured by farinograph increased with use of mime extract, but stability time decreased. After the first fermentation, dough volume decreased greatly under pH 4.0, and there was same tendency in loaf volume. Lightness and redness of the crumb decreased but yellowness increased. Hardness and fracturability of mume bread were lower than control. In sensory evaluation, fume bread with 0.5 brix muse extract was evaluated as the best in taste, texture, flavor and overall acceptability.

• ALGAE
• /
• 제19권2호
• /
• pp.149-151
• /
• 2004

Freshwater algae make up a very important portion of the autotrophic component of the aquatic food web. Therefore, the study of freshwater algal structure and biomass is central to aquatic ecosystem studies. Due to variations in cell shape and size for each species (or taxon) and survey site, cell abundance (or cell numbers per chosen volume) often leads to misrepresentation of the true importance of some species because of the great differences in size of various algae. Thus, it is necessary to investigate the freshwater algal species of a site in order to calculate the cell volume. Although direct cell counting, species volume measurement, as well as biomass calculation are time-consuming and requiring specialists in taxonomy.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
• /
• pp.561-564
• /
• 2006

The tensile characteristics of four types GFRP (glass fiber reinforced polymer) reinforcing bars with different resin mix proportions and fiber volume fraction were analyzed experimentally. Four types of GFRP reinforcing bars containing approximately 66 or 70% fiber volume fraction with A or B rein mix proportions were considered in this test. All testing procedures including specimens preparation, set-up of test equipments and measuring devices were made according to the recommendations of CSA Standard S806-02. From the test results, it was found that GFRP reinforcing bars containing approximately 70% fiber volume fraction with A rein mix proportion showed the higher tensile strength than that of the others due to the higher fiber volume fraction and proper resin mix proportion.

• Journal of Welding and Joining
• /
• 제15권3호
• /
• pp.47-55
• /
• 1997

Dynamic characteristics of the short circuit mode are investigated using the Volume of Fluid (VOF) method. When the initial molten drop volume, contact area and wire feed rate are given, rate change of the molten bridge profiles, pressure and velocity distributions are predicted. The electromagnetic force with proper boundary conditions are included in the formulation to consider the effects of welding current. It is found that the molten metal is transferred to the weld pool mainly due to the pressure difference caused by the curvatures in the initial stage, and electromagnetic force becomes dominant factor in the final stage of short circuit transfer. Necking occurs at the contact position between the molten drop and weld pool, and the initial molten drop volume and welding current have significant effects on break-up time.

• Journal of Chest Surgery
• /
• 제47권4호
• /
• pp.358-366
• /
• 2014

Background: To improve sinus rhythm conversion, the Cox maze III procedure with narrow mazes (width: ${\leq}3.0cm$) was performed in combination with left atrial volume reduction. Methods: From October 2007 to April 2013, 87 patients with atrial fibrillation (paroxysmal in 3, persistent in 14, and permanent in 70) underwent the Cox maze procedure concomitant with another cardiac procedure. They were followed-up with serial electrocardiographic and echocardiographic studies. We used 24-hour Holter monitoring tests to evaluate postoperatively symptomatic patients. Results: At the mean follow-up time of 36.4 months, 81 patients (94.2%) had sinus rhythm and two were on anti-arrhythmic medication (one on a beta-blocker and the other on amiodarone). Five patients (5.8%) with postoperative recurrent and persistent atrial fibrillation never experienced sinus rhythm conversion; however, they did not require any medication for rate control. On postoperative echocardiography, the left atrial A waves were more frequently observed after concomitant mitral valve repair than after concomitant mitral valve replacement (82.4% vs. 40.4%, respectively; p<0.001). Conclusion: For the Cox maze procedure, narrow mazes and atrial volume reduction resulted in excellent sinus rhythm conversion without the preventive use of anti-arrhythmic drugs, and they did not affect the presence of the left atrial A waves on echocardiography.

• 대한기계학회논문집B
• /
• 제28권10호
• /
• pp.1172-1177
• /
• 2004

The emission control of automobile has been intensified as a part of the countermeasure to decrease air pollution in the world. As the cars with an alternative fuel starts to get into the spotlight, the cars with low emission has been introduced and exhaust gas regulation forced in this country. These days, LPG vehicles, which infrastructure of fuel was already built up, and CNG vehicles are recognized for alternative fuel cars in this country. In this study, the constant volume combustion chamber was manufactured and used for experiments to obtain the combustion characteristics of propane mixture. The combustion characteristics was analyzed, with the change of supply conditions of propane fuel. Inside the combustion chamber, the maximum temperature increase with the initial pressure is going up. The burning velocity also seems to have the same characteristic as the temperature. However, the heat flux do not change much according to the theoretical correct mixture but it changes with the various initial temperature of the combustion chamber.

• 열처리공학회지
• /
• 제15권6호
• /
• pp.272-278
• /
• 2002

The changes in damping capacity with volume fractions of thermal and deformation-induced ${\varepsilon}$ martensites were compared and analyzed in an Fe-23%-Mn alloy. The volume fraction of thermal ${\varepsilon}$ martensite increased with decreasing cooling temperature, whereas that of deformation-induced ${\varepsilon}$ martensite increased steeply up to 10%- of cold rolling and nearly saturated in further cold rolling. In the case of thermal ${\varepsilon}$ martensite, the damping capacity increased linearly with the increase in ${\varepsilon}$ martensite content. For the deformation-induced ${\varepsilon}$ martensite, however, the damping capacity increased continuously up to 70%- of ${\varepsilon}$ martensite, over which it decreased suddenly. TEM microstructures showed that the deterioration of damping capacity above 70%- of deformation-induced ${\varepsilon}$ martensite is ascribed to the introduction of perfect dislocations, which play a important role in inhibiting the movement of damping sources such as stacking fault boundaries inside ${\varepsilon}$ martensite, ${\varepsilon}$ martensite variant boundaries and ${\gamma}/{\varepsilon}$ interfaces.

• 한국식품영양과학회지
• /
• 제28권3호
• /
• pp.534-541
• /
• 1999

This study was undertaken to examine the effect of sea tangle and sea mustard on physiochemical and sensory characteristics of cakes and the possibility commercialization of these functional cakes. The moisture contents of cakes prepared with sea tangle and sea mustard were higher than those of control, and a positive correlation between water holding capacity(WHC) and moisture contents was observed(r=0.836). As addition level of sea tangle and sea mustard was increased, volume of cakes were decreased, whereas hardness was increased slightly and color became deep. Hardness was strongly correlated to the volume of cakes(r= 0.914). Visual observation by photomicrography showed that, as addition level of sea mustard and sea tangle was increased, formation of air cells were prohibited and thus volume of cakes was decreased. The microstructural observation by scanning electron microscopy(SEM) showed that air cells of cakes were well developed up to 5% addition of sea tangle powder. As a result of the sensory evaluation for the cakes prepared with sea tangle and sea mustard, no significant difference was observed between control and those addition levels up to 5%. Flavor was proved to be the most important factor in determining overall acceptability and hedonic hardness score was inversely correlated to the objective hardness value(r= 0.853).