• Journal of Korea Foundry Society
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• v.17 no.5
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• pp.502-509
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• 1997

The mechanical behavior and microstructural evolution in the ignition-proof Mg-Zn-Ca-Zr alloy produced by the semisolid squeeze casting are clarified and the mechanical properties are also compared with those of squeeze cast Mg-Zn-Ca-Zr alloy. The tensile strength and elongation increase slightly as the solid fraction depending on temperature decreases, while the 0.2% proof stress decreases. The size of primary crystal increases with increasing holding time. The tensile strength and 0.2% proof stress of the semi-solid squeeze cast Mg-Zn-Ca-Zr alloy decrease as the size of primary crystal increases, indicating the dependence of strength on the size of primary crystal. The elongation of the semi-solid squeeze cast Mg-Zn-Ca-Zr alloy is two times as large as the squeeze cast Mg-Zn-Ca-Zr alloy and the tensile strength is unchanged despite the growth of primary crystal, resulting from the refining of the melted ${\alpha}Mg$ phase and the brittle eutectic compound as well as the reduction of solidification shrinkage and porosities.

• Korean Journal of Materials Research
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• v.30 no.5
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• pp.223-230
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• 2020

As a case study on aspect ratio behavior, Kaolin, zeolite, TiO₂, pozzolan and diatomaceous earth minerals are investigated using wet milling with 0.3 mm 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, ~6 ㎛ are shifted to submicron size, D₅₀ ~0.6 ㎛ 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.

• Transactions of Materials Processing
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• v.14 no.4 s.76
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• pp.319-326
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• 2005

In this study, the nano-deformation behavior of semi-solid Al-Si alloy was investigated using a molecular dynamics simulation as a part of the research on the surface crack behavior in thixoformed automobile parts. The microstructure of the grain-size controlled Al-Si alloy consists of primary and eutectic regions. In eutectic regions the crack initiation begins with initial fracture of the eutectic silicon particles and inside other intermetallic phases. Nano-deformation characteristics in the eutectic and primary phase of the grain-size controlled Al-Si alloy were investigated through the molecular dynamics simulation. The primary phase was assumed to be single crystal aluminum. It was shown that the vacancy occurred at the zone where silicon molecules were.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.16 no.4
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• pp.390-395
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• 1994

The author evaluated the nasal asymmetry after primary operations in the patients with unilateral cleft lip using full face photographs. The results are as follows : 1. Nasal deviation angle is average 2.98+3.01 degree(ranged from 0 to 10 degree), significantly different from control group(p<0.05). 2. Nasal deviation angle is average 5.1% when inter-medial canthal distance is 100%, significantly different from control group(p<0.05). 3. Difference in nostril size between cleft and noncleft side is 2.1% when inter-medial canthal distance is 100%, significantly different from control group(p<0.05). 4. Nasal attractiveness analysis shows higher points in difference in nostril size, nasal deviation, nasal form in that order. 5. Nasal asymmetry after primary operations in the patients with unilateral cleft lip using full face photographs is related with Nasal deviation angle, Nasal deviation distance and Difference in nostril size between cleft and noncleft side.

• Transactions of Materials Processing
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• v.13 no.7
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• pp.608-613
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• 2004

Mechanical properties of hypereutectic Al-Si alloy are influenced by the size and distribution of primary Si. To investigate the effects of P addition and holding time, hypereutectic Al-Si alloys with various amount of P content were produced in the lab. Then, the size and distribution of primary Si were examined respectively. Mechanical properties of hardness, tensile strength and wear resistance were analyzed in conjunction with the microstructural variations in alloys.

• Korean Journal of Head & Neck Oncology
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• v.31 no.2
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• pp.16-20
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• 2015

Background and Objectives : In papillary thyroid carcinoma (PTC), multiplicity and central or lateral lymph node metastases significantly affect the recurrence. This study was carried out to evaluate the clinical and histological characteristics of PTC according to the tumor size. Materials and Method : Between January 1, 2009 and December 31, 2014, 12,269 PTC patients underwent thyroid surgery at the Thyroid Cancer Center, Gangnam Severance Hospital, Yonsei University College of Medicine, Korea. We analyzed pathologic findings and clinical features according to the size of tumor Results : The mean size of tumor was $0.89{\pm}0.70cm$. The Central and lateral compartment metastases were observed 64.7% and 37.6% on the range that the primary tumor size is 1cm. There was a significant association between the PTC primary tumor size and multiplicity and cervical neck metastasis (p<0.001). Conclusion : The PTC primary tumor size for prediction of multiplicity and neck node metastasis can be helpful in optimization of the surgical extent for each patient.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.2
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• pp.717-722
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• 2013

Background: Breast cancer is the most common cancer among women worldwide. The aim of this study was to investigate the relationship between tumor size and axillary lymph node involvement (ALNI) in patients with invasive lesions, to find the best candidates for a full axillary dissection. Additionally, we evaluated the association between tumor size and invasive behavior. The study was based on data from 789 patients with histopathologically proven invasive breast cancer diagnosed in Shohada University hospital in Tehran, Iran (1993-2009). Cinical and histopathological characteristics of tumors were collected. Patients were divided into 6 groups according to primary tumor size: group I ($0.1-{\leq}1cm$), II ($1.1-{\leq}2cm$), III ($2.1-{\leq}3cm$), IV ($3.1-{\leq}4cm$), V ($4.1-{\leq}5cm$) and VI (>5cm). The mean(${\pm}SD$) size of primary tumor at the time of diagnosis was $3.59{\pm}2.69$ cm that gradually declined during the course of study. There was a significant correlation between tumor size and ALNI (p<0.001). A significant positive correlation between primary tumor size and involvement of surrounding tissue was also found (p<0.001). The mean number of LNI in group VI was significantly higher than other groups (p<0.05). We observed more involvement of lymph nodes, blood vessels, skin and areola-nipple tissue with increase in tumor size. We found 15.3% overall incidence of ALNI in tumors ${\leq}2cm$, indicating the need for more investigation to omit full axillary lymph node dissection with an acceptable risk for tumors below this diameter. While in patients with tumors ${\geq}2cm$, 84.3% of them had nodal metastases, so the best management for this group would be a full ALND. Tumor size is a significant predictor of ALNM and involvement of surrounding tissue, so that an exact estimation of the size of primary tumor is necessary prior to surgery to make the best decision for management of patients with invasive breast cancer.

• Journal of Chest Surgery
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• v.26 no.3
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• pp.209-213
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• 1993

The pathogenesis of the primary spontaneous pneumothorax is the rupture of subpleural bleb or bullae and subsequent sudden collapse of the affected lung. Mostly, the bullae or blebs are present bilaterally, but detecting the number, size, and location of the causating foci by plain chest film is quite difficult . We have performed chest CT scans for detecting the bullous lesions in 33 cases of primary spontaneous pneumothorax, and compared the results with surgical findings.1. Seventy-four blebs were identified in the chest CT scan, and 100 blebs or bullae were detected surgically [ Sensitivity was 0.74 ].2. Diagnosis rate was 80% [40/50] at right upper lobe, 75.7% [28/37] at left upper lobe, 55.6% at right lower lobe, and 25.0% at left lower lobe, respectively.3. Blebs or bullae smaller than 1 cm of its diameter were detected by 57.1% [24/42] of sensitivity, and in the cases of size larger than 1 cm, it revealed 86.2% [50/58] of sensitivity respectively.4. Of the 45 cases, 7 cases were false negative [15.6%], most of these were ruptured or small size [< 0.5 cm]. 5. One case was false positive, which was irregular adhesion at the apex of the lung.6. We could detect blebs or bullae with preoperative CT scans in 84.4% [38/45] of total patients. In conclusion, chest CT scan is a very advantageous diagnostic tool for proper management and preventing recurrence of primary spontaneous pneumothorax patient.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.111-114
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• 2004

It is many devices to obtain the globular structure because the globularity of the structure is the key to the low apparent viscosity and also to good rheological properties. In this study, the morphology of the change of primary Al phase in A356 alloy by electro magnetic stirrer was investigated to obtain the globular structure. The parameters are the current, stirring time, pouring temperature individually. The greater current and longer stirring time was to get the finer the primary however in case of over the 80A of current and 60sec of stirring time, the primary Al was merged together and was increased. The effect of pouring temperature has an important effect on the size of primary phase. About the $675^{\circ}C$, the primary Al was very fined.

• Korean Journal of Materials Research
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• v.30 no.2
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• pp.51-56
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• 2020

In this study, three kinds of metal chills such as SS400, AC4CH and brass, with different thicknesses of 40 ~ 80 mm, were applied for low pressure casting of Al-Si alloy to control cooling rate. The microstructural characteristics with increasing cooling rate were represented using factors including D₁, D₂, size of primary α phases and shape factor and size of eutectic Si. The tensile properties were investigated and additionally analyzed based on the microstructural characteristics. As the cooling rate increased, D₁, D₂, and sizes of primary α phases and eutectic Si apparently decreased and the shape factor of eutectic Si increased to over 0.8. The ultimate tensile strength (UTS) and yield strength (YS) increased with decreasing D₁, D₂, and size of primary α phases, while elongation increased with decreasing size of eutectic Si and concurrently increasing shape factor of eutectic Si. This indicated that the primary α phases and eutectic Si in Al-Si alloy were refined with increasing cooling rate, resulting in improvement of UTS and YS without sacrificing elongation. After the tensile test, preferential deformation of primary α phases was observed in the Al-Si alloy produced at higher cooling rates of more than 0.1 K/s.