Hyung Jin Kim

Small cell carcinoma of the larynx: imaging findings.

Small cell carcinoma of the larynx is an uncommon epithelial tumor, which is the most aggressive subtype of neuroendocrine carcinomas. Because of its nonspecific clinical and radiological manifestations, the diagnosis of small cell carcinoma of the larynx is essentially based on the light microscopic examination aided by electron microscopy or immunohistochemical staining. We report a case of supraglottic small cell carcinoma accompanied by large bilateral cervical lymph node metastasis ocurring in a 70-year-old man. On CT scans, no area of low attenuation indicating necrosis was demonstrated within such large metastatic lymph nodes. We suggest that small cell carcinoma of the larynx should be included in the diagnostic considerations when a laryngeal mass is accompanied by large cervical lymph nodes without necrosis shown by CT.

Hemiazygos continuation of a left inferior vena cava draining into the right atrium via persistent left superior vena cava: Demonstration by helical computed tomography

We report an unusual case of hemiazygos continuation of a left inferior vena cava draining into the right atrium via the persistent superior vena cava. Spiral computed tomography (CT) showed the course and the flow direction of this vena caval anomaly in a real-time manner, obviating conventional venography.

Effect of Load on the Abrasive Wear of Silica-Filled Epoxy Resin Composites

In the present study, the influences of load on the abrasive wear properties of silica-filled epoxy resin composites were investigated at ambient temperature. The friction coefficient, wear rate and specific wear rate against SiC abrasive paper were determined experimentally. The sliding wear tests of the materials demonstrated that the friction coefficient and the wear rate of silica filled epoxy composites were lower than those of the pure epoxy. The cumulative wear volume tended to increase nonlinearly with increase of sliding distance and depended on diameter of the silica particle for all these composites. The friction coefficient and wear rate were raised substantially with an increase in applied load.

Wear Characteristics of Particulate Reinforced Metal Matrix Composites Fabricated by a Pressureless Metal Infiltration Process

The effect of size and volume fraction of ceramic particles with sliding speed on the wear properties were investigated for metal matrix composites fabricated by a pressureless metal infiltration process. The particulate metal matrix composites exhibited about 5.5 - 6 times greater wear resistance compared with AC8A alloys at high sliding speed, and by increasing the particle size and decreasing the volume fraction the wear resistance improved. The wear resistance of the metal matrix composites and AC8A alloy represented different aspects: the wear loss of the AC8A alloy increased with sliding speed linearly, whereas, the metal matrix composites displayed more wear loss than the AC8A alloy in the slow-speed region. However, a transition point of wear loss was found in the middle-speed region, which shows the minimum wear loss. Furthermore, wear loss in the high-speed region exhibited almost the same value as the slow-speed region. In terms of wear mechanism, the metal matrix composites showed abrasive wear at a slow to high sliding speed generally. However, the AC8A alloy showed abrasive wear at low sliding speed and adhesive and melt wear at a high sliding speed.

Effects of Processing Parameters on the Mechanical Properties of SiCp/AC8A Composites by Pressureless Metal Infiltration Process

The effects of additional Mg content and the size of the reinforcement phase on the mechanical properties of 20 vol.% SiCp/AC8A composites fabricated by pressureless metal infiltration process were investigated. The hardness of SiCp/AC8A composites increased gradually with an increase in the additive Mg content, while the bending strength of SiCp/AC8A composites increased with an increase in additive Mg content up to 5%. However, this decreased when the level of additive Mg content was greater than 5%. The increase in hardness by additive Mg content is due to the formation of hard reaction products such as Mg2Si and AlN during the process, whereas the decrease in bending strength when Mg content was above 5% is due to the formation of coarse precipitates by excessive Mg reaction and an increase in the porosity level. The hardness and strength of the composites increased with a decrease in the size of SiC particles. It was found that the composites with smaller particles enhanced the interfacial bonding more than those with bigger particles from fractography of the composites.

Fatigue Crack Growth Properties of Friction Stir Welded Dissimilar Aluminum Alloys

The presence of a crack can increase the local stress or strain, which can cause inelastic deformation and significantly reduce the life of a component or structure. Therefore, in this study, the fatigue crack growth (FCG) behaviors of friction stir welded Al 2024-T3 and Al 7075-T6 specimens were examined, with fatigue cracks growing parallel to the dynamically recrystallized zone at variable ΔK values and an R ratio of 0.3. In addition, the FCG values of the base metal Al 2024-T3 and Al 7075-T6 were tested under the same conditions and parameters as comparative groups. The results showed that compared with the base metal Al 2024 specimen, which had the best fatigue property, the welded specimen had only 88% of the fatigue cycles.

Behavior of abrasive wear on counterpart roughness of glass fiber reinforcement polyurethane resin composites

The behavior of abrasive wear on counterpart roughness of glass fiber reinforcement polyurethane resin (GF/PUR) composites were investigated at ambient temperature by pin-on-disc friction test. The friction coefficient, cumulative wear volume and surface roughness of these materials against SiC abrasive paper were determined experimentally. The major failure mechanisms were lapping layers, ploughing, delamination, deformation of resin and cracking by scanning electric microscopy (SEM) photograph of the tested surface. As increasing the counterpart roughness the GF/PUR composites indicated higher friction coefficient. The surface roughness of the GF/PUR composites was increased as the sliding velocity was higher and the counterpart roughness was rougher in wear test.

Effect of the Size of the Reinforcement Phased on the Properties of Silica-Filled Composites

In this study, the mechanical properties of silica-filled epoxy resin composites with average silica particle diameter of 6-33m were investigated at ambient temperature and pin-ondisc friction test was conducted for this. Experimental results demonstrated that mechanical properties such as flexural strength, flexural modulus and critical stress intensity factor depend on average particle diameter. The flexural strength decrease with increase of particle size whereas the critical stress intensity factor increases with increases of particle size. Wear rates of silica-filled composites are below a half those of unfilled epoxy. Fracture surface analysis was discussed based on SEM examination.

Effect of Processing Parameters on the Fabrication of Al2O3p/Al Composites by In-Situ Reaction Process of Molten Al

The effects of processing parameters such as addition type and Mg content on the fabrication of Al2O3p/Al composites by in-situ reaction process of molten Al were investigated in terms of infiltration behavior of molten Al and the variation of the microstructure and hardness of the composites. It was ascertained that additional Mg content is the most important parameter for the infiltration of molten Al. Furthermore, increase in additional Mg content and processing temperature resulted in a high infiltration ratio of molten Al and a high hardness value of the composites. However, these caused a greater scatter of the hardness value of the composites due to the nonuniform dispersion of the reinforcement phase, which arose from an excessive reaction of Mg.

A Study on the Interlaminar Fracture Toughness of Hybrid Composites

This paper describes the effect of loading rate, specimen geometries and material properties for ModeⅠ and Mode Ⅱ interlaminar fracture toughness of hybrid composite by using double cantilever beam (DCB) and end notched flexure (ENF) specimen. In the range of loading rate 0.2~20mm/min, there is found to be no significant effect of loading rate with the value of critical energy release rate (Gc).The value of Gc for variation of initial crack length are nearly similar values when material properties are CF/CF and GF/GF, however, the value of Gc are highest with the increasing intial crack length at CF/GF. The SEM photographs show good fiber distribution and interfacial bonding of hybrid composites when the moulding is the CF/GF.