• Journal of Korea Foundry Society
• /
• v.17 no.6
• /
• pp.585-591
• /
• 1997

Hyper-eutectic Al-17.5wt%Si alloy bars of 25 mm in diameter were produced by horizontal continuous casting process. Effect of both casting speed and primary Si refiner (AlCuP) on microstructure and mechanical properties of the alloy have been investigated. With increasing a weight fraction of AlCuP, the average primary Si size decreased down to $20 {\mu}m$. On the contrary, there was no notable changes of microstructure and primary Si size according to the casting speed in the experimental range of this study, indicating that the cooling rate should be increased to optimize and refine microstructure and primary Si size. The experimental results including hardness, tensile strength and wear resistance tests of the processed alloy bars showed a good possibility to develop the high performance wear resistant Al-Si alloy.

• Proceedings of the KSME Conference
• /
• 2004.11a
• /
• pp.1140-1145
• /
• 2004

Laser-induced incandescence (LII) is introduced as a valuable tool for the characterization of nanoparticles in flame environments. This technique is based on the heating of the particles by a short laser pulse and the subsequent detection of the thermal radiation. It has been applied successfully for the investigation of soot in different fields of application. The evaluation of the temporal decay of the laser-induced incandescence (LII) signal from soot particles is introduced as a technique to obtain two-dimensional distributions of particle sizes and is applied to a laminar diffusion flame. This novel approach to soot sizing exhibits several theoretical and technical advantages compared with the established combination of elastic scattering and LII, especially as it yields absolute sizes of primary particles without requiring calibration. With this technique a spatially resolved 2-D measurement of soot primary particle sizes is feasible in a combination process form the ratio of emission signals obtained at two delay times after a laser pulse, as the cooling behavior is characteristic of particle size.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.49 no.5
• /
• pp.292-296
• /
• 2023

Generally, if the size of a lip cancer defect exceeds 30% of the lower lip, a local flap or free flap is recommended. However, defects up to 50% of the lower lip in size have been reconstructed successfully by primary closure without a local flap or free flap. In one case, an 80-year-old male farmer who had smoked for more than 50 years presented with squamous cell carcinoma of the lower lip and underwent mass resection and supraomohyoid neck dissection. The defect accounted for almost 2/3 of the lower lip and was repaired by primary closure with V-shaped resection. Biopsy results confirmed pT2N0cM0 stage II disease with clear margins. In another case, a 68-year-old male also presented with squamous cell carcinoma of the lower lip and underwent mass resection. The defect accounted for about half the size of the lower lip but was repaired by primary closure with V-shaped resection. Both patients experienced no discomfort while eating or speaking and were satisfied with the cosmetic and functional outcomes with no evidence of recurrence. Thus, direct closure can be considered even in large lower lip cancers.

• Proceedings of the KSRS Conference
• /
• v.1
• /
• pp.406-408
• /
• 2006

Various geological thematic maps such as grain size or ground water level maps have been generated by interpolating sparsely sampled ground survey data. When there are sampled data at a limited number of locations, to use secondary information which is correlated to primary variable can help us to estimate the attribute values of the primary variable at unsampled locations. This paper applies two multivariate geostatistical algorithms to integrate remote sensing imagery with sparsely sampled ground survey data for spatial estimation of grain size: simple kriging with local means and kriging with an external drift. High-resolution IKONOS imagery which is well correlated with the grain size is used as secondary information. The algorithms are evaluated from a case study with grain size observations measured at 53 locations in the Baramarae beach of Anmyeondo, Korea. Cross validation based on a one-leave-out approach is used to compare the estimation performance of the two multivariate geostatistical algorithms with that of traditional ordinary kriging.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.29 no.9 s.240
• /
• pp.1022-1031
• /
• 2005

Temporal behavior of the laser induced incandescence (LII) signal is often used for soot particle sizing, which is possible because the cooling behavior of a laser heated particle is dependent on the particle size. In present study, LII signals of soot particles are modeled using two non-linear coupled differential equations deduced from the energy- and mass-balance of the process. The objective of this study is to obtain an appropriate calibration curve for determining primary particle size by comparing the gated signal ratio and double-exponential curve fitting methods. Not only the effects of laser fluence and gas temperature on the cooling behavior but also heat transfer mechanisms of heated soot particle have been investigated. The second-order exponential curve fitting showed better agreements with the LII signals than the gated signal ratio method which was based on the lust-order exponential curve fit. And the temporal decay rate of the LII signal and primary particle size showed nearly linear relationship, which was little dependent on the laser fluence. And it also could be reconfirmed that vaporization was dominant process of heat loss during first loons after laser pulse, then heat conduction played most important role while thermal radiation had little influence all the time.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.31 no.7 s.262
• /
• pp.596-603
• /
• 2007

As increasing interest for soot emission. etc in combustion systems, various studies are being carried out for the reduction and measurement techniques of soot. Especially, laser induced incandescence is the useful measurement technique which has distinguished spatial and temporal resolution for primary particle size, volume fraction and aggregated particle size etc. Time resolved laser induced incandescence is the technique for measuring primary particle size that is decided to solve the signal decay rate which is related to the cooling behavior of heated particle by pulsed laser. The cooling behavior of heated particle is able to represent the heat and mass transfer model which are involved constants of soot property for surround gas temperature on the our previous work. In this study, it is applied to the time-dependence thermodynamic properties for soot temperature instead of constants of soot property for surround gas temperature and compared two different model results.

• Proceedings of the KSR Conference
• /
• 2002.05a
• /
• pp.116-121
• /
• 2002

This primary study has some bounds md limits owing to the descriptive reviews but not detailed analyses. However, 1 tried to do the comparative analyses and case studies about location and size of rail station for future efficient use of spatial structure. Therefore, I reviewed the location of railway station and some design standards of railway station facilities by type (high speed rail, conventional rail and urban rail), and also, suggested future direction for rail station as the core of city development relating with urban structures and human settlement system reformation.

• Textile Coloration and Finishing
• /
• v.27 no.4
• /
• pp.245-260
• /
• 2015

The effect of salt milling process on the crystal size, morphology, and color characteristics of C.I. Pigment Red 57:1 was studied. The primitive morphology and color properties of the pigment after synthesis were studied in the former series work. The size and morphology of primary particles and the second aggregation features should be considered because they are very important to determine pigment quality. We compared the primary morphology of pigment particles before drying with the secondary aggregated morphology of pigment particles after drying and salt milling process. Morphological properties were investigated by particle size analysis, X-ray diffraction, and scanning electron microscopy and color measurement was carried out. Significant reduction in particle size as well as enhanced crystallite size after salt milling process was observed. This result might give a difference in color of the pigment, turning into brighter and more blue-toned red color. It was revealed that synthesis condition affect the morphology and color of the pigment even after milling. Increase in HCl concentration in the synthesis process enhanced crystal size and quality forming bluer-red pigments but an increase in $CaCl_2$ concentration resulted in more amorphous crystals forming darker-red pigments after salt milling.

• Korean Journal of Materials Research
• /
• v.29 no.4
• /
• pp.264-270
• /
• 2019

As a case study on aspect ratio behavior, Kaolin, zeolite, $TiO_2$, pozzolan and diatomaceous earth minerals are investigated using wet milling with 0.3 pai media. The grinding process using small media of 0.3 pai is suitable for current work processing applications. Primary particles with average particle size distribution D50, ${\sim}6{\mu}m$ are shifted to submicron size, D50 ${\sim}0.6{\mu}m$, after grinding. Grinding of particles is characterized by various size parameters such as sphericity as geometric shape, equivalent diameter, and average particle size distribution. Herein, we systematically provide an overview of factors affecting the primary particle size reduction. Energy consumption for grinding is determined using classical grinding laws, including Rittinger's and Kick's laws. Submicron size is obtained at maximum frictional shear stress. Alterations in properties of wettability, heat resistance, thermal conductivity, and adhesion increase with increasing particle surface area. In the comparison of the aspect ratio of the submicron powder, the air heat conductivity and the total heat release amount increase 68 % and 2 times, respectively.

• The Korean Journal of Applied Statistics
• /
• v.24 no.2
• /
• pp.393-400
• /
• 2011

In a large scale survey, cluster sampling design in which a set of observation units called clusters are selected is often used to satisfy practical restrictions on time and cost. Especially, a two stage cluster sampling design is preferred when a strong intra-class correlation exists among observation units. The sample Primary Sampling Unit(PSU) and Secondary Sampling Unit(SSU) size for a two stage cluster sample is determined by the survey cost and precision of the estimator calculated. For this study, we derive the optimal sample PSU and SSU size when the population SSU size across the PSU are di erent by extending the result obtained under the assumption that all PSU have the same number of SSU. The results on the sample size are then applied to the $4^{th}$ Korea Hospital Discharge results and is compared to the conventional method. We also propose the optimal sample SSU (discharged patients) size for the $7^{th}$ Korea Hospital Discharge Survey.