• 대한금속재료학회지
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• 제46권7호
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• pp.412-419
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• 2008

Creep behavior of the squeeze infiltrated AS52 Mg matrix composites reinforced with 15 vol% of aluminum borate whiskers($Al_{18}B_4O_{33}w$) fabricated squeeze infiltration method was investigated. Microstructure of the composites was observed as uniformly distributed reinforcement in the matrix without any particular defects of casting pores etc.. Creep test was carried out at the temperature of 150 and $200^{\circ}C$ under the applied stress range of 60~120 MPa. The creep resistance of the composite was significantly improved comparing with the unreinforced AS52 Mg alloy. The creep behavior of composites might be interpreted with the substructure invariant model successfully for the composite. Threshold stress of the composite exist for the creep deformation of the composite. The analysis of the creep behavior of the composite with threshold stress indicated that creep deformation was controlled by the lattice diffusion process of AS52 Mg matrix at given effective stresses and temperatures. Activation energy was also calculated to check lattice diffusion controlled creep behavior of the composite.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.50-53
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• 2003

Carbon nannofiber reinforced Cu matrix composite has potential applications for electrically conducting materials having high strength and electrical conductivity. In this study, we have developed fabrication technology of the nanocomposites using a liquid pressing process. The process is to use the low pressure for infiltration of Cu melt into carbon nanofiber mat as the Cu melt is pressurized directly. The minimum pressure required for infiltration was calculated from force balance equation, permeability measurement and compaction behavior of carbon nanofiber. Also, the melting temperature and the holding time have been optimized.

• 한국세라믹학회지
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• 제43권8호
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• pp.509-514
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• 2006

In this study, chopped Hi-Nicalon SiC fiber Reinforced Porous Reaction Bonded SiC (RBSC) composites and it fabrication process were developed by using Si melt infiltration process. The porosity and average pore size in fabricated chopped SiC fiber reinforced porous RBSC composites were in the range of $30{\sim}40%$ and $40-90{\mu}m$, which mainly determined by the SiC powder size used as starting material and amount of residual Si in porous composites. The maximum flexural strength of chopped SiC fiber reinforced porous RBSC composite was as high as 80 MPa. The delayed fracture behavior was observed in chopped SiC fiber reinforced porous RBSC composites upon 3-point bending strength test.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 춘계학술발표대회 논문집
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• pp.250-253
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• 2004

Emphasis has been placed on thin plate fabrication of plain woven carbon fabric reinforced Al matrix composites using liquid pressing process. The composite has potential applications for PDP rear plate. The process is to use the low pressure for infiltration of Al melt into plain woven carbon fabric as the Al melt is pressurized directly. The minimum pressure required for the infiltration was calculated from force balance equation, permeability measurements and compaction behavior of carbon fiber. Also, the melting temperature and the holding time have been optimized. In order to measure coefficient of thermal expansion (CTE) of the composites, the thermal strain measurement using strain gage was performed and the thermal conductivity of the composites was measured using laser flash method. The constituent materials of the composite are PAN type carbon fibers as reinforcements and 6061 Al alloys as matrices.

• 한국농공학회논문집
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• 제56권2호
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• pp.59-64
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• 2014

In this study, the large scale test was performed to investigate the behavior of failure for the embankment and spillway transitional zone by overtopping. The pore water pressure, earth pressure, settlement and failure pattern of covering embankment with geotextile were compared and analyzed. The pore water pressure showed a small change in the spillway transition zone and core, indicating that the geotextile efficiently reinforced the embankment. The earth pressure decreased the infiltration of the pore water only in inclined cores type to secure local stability. The behavior of failure started from the bottom and gradually progressed upwards. After the intermediate overtopping period (100 min), width and depth of the seepage erosion were very small due to the effect of geotextile which delayed failure. Therefore, the reinforced method by geotxtile was a very effective method to respond to the emergency due to overtopping.

• 한국재료학회지
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• 제20권6호
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• pp.331-337
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• 2010

A highly porous Biphasic Calcium Phosphate (BCP) scaffold was fabricated by the sponge replica method with a microwave sintering technique. The BCP scaffold had interconnected pores ranging from $80\;{\mu}m$ to $1000\;{\mu}m$, which were similar to natural cancellous bone. To enhance the mechanical properties of the porous scaffold, infiltration of polycaprolactone (PCL) was employed. The microstructure of the BCP scaffold was optimized using various volume percentages of polymethylmethacrylate (PMMA) for the infiltration process. PCL successfully infiltrated into the hollow space of the strut formed after the removal of the polymer sponge throughout the degassing and high pressure steps. The microstructure and material properties of the BCP scaffold (i.e., pore size, morphology of infiltrated and coated PCL, compressive strength, and porosity) were evaluated. When a 30 vol% of PMMA was used, the PCL-BCP scaffold showed the highest compressive strength. The compressive strength values of the BCP and PCL-BCP scaffolds were approximately 1.3 and 2MPa, respectively. After the PCL infiltration process, the porosity of the PCL-BCP scaffold decreased slightly to 86%, whereas that of the BCP scaffold was 86%. The number of pores in the $10\;{\mu}m$ to $20\;{\mu}m$ rage, which represent the pore channel inside of the strut, significantly decreased. The in-vitro study confirmed that the PCL-infiltrated BCP scaffold showed comparable cell viability without any cytotoxic behavior.

• Asian Pacific Journal of Cancer Prevention
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• 제17권4호
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• pp.1857-1859
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• 2016

Background: Hodgkin's lymphoma (formerly, Hodgkins disease) is a potentially curable malignancy with distinctive biological behavior and specific clinical characteristics. Limited information is available from developing countries for patients with classical Hodgkin's lymphoma (cHL). Therefore we reviewed the demographical and clinico-hematological profiles along with bone marrow infiltration patterns in adult patients presenting at Liaquat National Hospital and Medical College. Materials and Methods: In this cross sectional study, 62 adult (${\geq}15years$) patients with cHL were enrolled from January 2010 to December 2014. Results: The mean age was $29.7{\pm}13.8years$ with a median of 30 years. The male to female ratio was 2:1. B symptoms were present in 72.5% of patients and lymph node enlargement in 85.4%. The frequency of bone marrow infiltration in our cHL patients was found to be 27.4%, the pattern being predominantly focal followed by diffuse. The mean hemoglobin was $9.4{\pm}1.9g/dl$ with a mean MCV of $78.1{\pm}7.9fl$, a mean total leukocyte count of $10.9{\pm}20.6{\times}10^9/l$ and a mean platelet count of $241.6{\pm}150.1{\times}10^9/l$. Conclusions: Our analysis shows that clinico-pathological features of cHL in Pakistan are comparable to published data. Peripheral lymphodenopathy associated with B symptoms is the commonest presentation. Bone marrow involvement is more common in our setup as patients usually presented at an advanced stage of disease.

• 한국지반환경공학회 논문집
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• 제12권10호
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• pp.29-38
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• 2011

현행 사면 안정 해석 시 지하수위 결정방법은 강우에 의한 침투과정에 의한 불포화구간을 제대로 반영하고 있지 못하고 있다. 본 연구에서는 강우에 의한 지표면 상부침투에 의한 포화대 증가에 따른 사면의 안전율 변화를 실내모형실험을 통해 검증하고자 하였다. 강우침투로 인한 흙의 전단강도 저하를 정확히 파악하기 위해 실내 사면모형실험을 통해 함수비 변화를 측정하고, 이에 따른 강도정수의 변화를 파악하였다. 포화깊이 3.0m에서 4.5m로 변할 때 안전율이 가장 크게 변화되는 것을 알 수 있었으며, 이는 설계기준에서 제시한 지하수위 (-)3.0m은 다소 과소 설계된다는 것을 판단할 수 있다. 또한, 지표면 포화로 해석할 경우는 과다 설계되므로 사면의 설계 시 강우 침투에 관한 실험 및 해석이 필요함을 알 수 있다.

• Journal of Dental Anesthesia and Pain Medicine
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• 제23권3호
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• pp.135-141
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• 2023

Background: The limited studies on the effect of buffering on the clinical efficacy of articaine have reported controversial results. The purpose of this study was to clinically compare the pain of injection, anesthetic success, onset, and duration of pulpal anesthesia of buffered 4% articaine with epinephrine 1:100000 versus a non-buffered 4% articaine with epinephrine 1:100000 formulation for buccal infiltration of the mandibular first molar. Methods: Sixty-three volunteers were enrolled in the study. All volunteers received two injections consisting of a single mandibular first molar buccal infiltration with 1.8 ml of 4% articaine with epinephrine 1:100000 and 1.8 ml of 4% articaine with epinephrine 1:100000 buffered with 8.4% sodium bicarbonate. The infiltrations were applied in two separate appointments spaced at least one week apart. After injection of the anesthetic solution at the examined site, the first molar was pulp-tested every 2 min for the next 60 min. Results: Successful pulpal anesthesia was recorded in 69.8% of cases using non-buffered articaine solution and 76.2% of cases using buffered articaine solution, with no significant difference between the formulations (P = 0.219). The mean time of anesthesia onset for the volunteers with successful anesthetic outcome in both formulations (n = 43) was 6.6 ± 1.6 min for the non-buffered articaine solution and 4.5 ± 1.6 min for the buffered solution, which differed significantly (P = 0.001). In the same volunteers, the mean duration of pulpal anesthesia was 28.4 ± 7.1 min for non-buffered articaine solution and 30.2 ± 8.5 min for buffered articaine solution, with no significant difference between the formulations (P = 0.231). Considering the pain of injection, regardless of the anesthetic success, the mean values of VAS were 11.3 ± 8.2 mm for the non-buffered articaine solution and 7.8 ±6.5 mm for the buffered articaine solution, which differed significantly (P = 0.001 < 0.05). Conclusion: According to the present study, 4% articaine with epinephrine can benefit from buffering and provide better anesthetic behavior, with improved onset and less pain during injection.

• 동력기계공학회지
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• 제10권2호
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• pp.93-98
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• 2006

Metal matrix composites(MMCs) reinforced with ceramic particulates are receiving increasing attention because their high specific strength, low coefficient of thermal expansion and excellent wear resistance. Especially, Al-based composites(AMCs) have been widely applied for the aerospace and automotive industries. Such composites are mainly fabricated by the cast, powder metallurgy and infiltration process. In this study, SiC particulate reinforced Al-based composites were fabricated by thermal spray process and their wear behavior were investigated. Composites with different spray parameter were fabricated by using flame spray apparatus. Microstructure and wear behavior of the composites were observed by scanning electron microscope(SEM) and electron probe micro-analysis(EPMA).