• Journal of Korea Foundry Society
• /
• v.24 no.6
• /
• pp.356-365
• /
• 2004

Mechanical properties and microstructures of the Ni-AI-Fe and Ni-AI-Fe-(B, Zr) alloys which containing $10{\sim}30at$.%Fe, 0.1at.%B and/or 0.1at.%Zr have been investigated. The experimental results showed that the microstructures of Ni25Al were changed from a single phase ${\gamma}$ to dual phase ${\gamma}$ and ${\beta}$ by addition of 27at.%Fe. Ni45Al, however, kept the single ${\beta}$ phase even though Fe was added upto 30at.%. The hardness of Ni25Al were increased from $H_RB$ 70 to $H_RC$ 39 by addition of 27at.%Fe. In the case of Ni45Al which have $H_RC$ 37, the hardness was decreased by lOat.%Fe addition, but increased with 30at.%Fe. The yield strength and ultimate compressive strength in the compressive test have showed a similar trend with the hardness change. The strain to fracture was 14% at maximum and achieved in Ni25Al-27at.%Fe and Ni25Al-27at.%Fe-0.1 at.%B alloys. The Ni45Al showed a relatively low strain to fracture as 4%. The impact absorption energy of Ni25Al increased from 0.74 kg-m to 1.81 kg-m by addition of 27at.%Fe. In case of Ni45Al, the addition of lOat.%Fe and lOat.%Fe with small amounts of Band Zr did not change significantly the impact absorption energy of 0.60 kg-m, whereas the addition of 30at.%Fe with small amounts of B and Zr increased it slightly. In fracture tests, both of two basic materials showed the same intergranular fracture but by adding Fe it changed to the cleavage fracture mode or co-existing of cleavage and intergranular fractures.

• Clean Technology
• /
• v.6 no.2
• /
• pp.93-99
• /
• 2000

Effect of amount of red mud and processing method on the tensile and impact properties of polymers were investigated when the red mud was added as a filler to polypropylene (PP), low density polyethylene (LDPE) and PP/LDPE blend. Especially in case of PP, increase in the tensile strength, elongation at break and absorbed energy was observed when extrusion was carried out more than two times. Tensile strength showed a very remarkable increase when master batch was used in comparison with simple multiple extrusion. In case of LDPE, 10% addition of red mud resulted in the increase of tensile modulus and impact strength, while 20% addition caused a decrease in the same properties. Addition of 5% EVA could reverse this trend. Addition of 20% red mud to PP/LDPE blend gave a decrease in impact strength but 5% EPR compatibilizer could improve the impact properties. Above results showed that the processing method is a very important factor in the utilization of red mud as a plastic fillers and master batch is one of the very effective way of red mud addition.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2002.05a
• /
• pp.82-85
• /
• 2002

A systematic investigation for process design in deep drawing is necessary for quality improvement of drawn cups. This study has been concentrated mainly on the influence of process design scheme on product qualities in cylindrical cup drawing. Three types of process design scheme were chosen in this study. That is, Case 1 is to finish drawing a cup of 50m in diameter in one stage, Case 2 and Case 3 are redrawing the drawn cups of 55, 65 mm in diameter to the final size respectively. Though experiments the maximum drawing force in two-stage cup drawing could be reduced up to 35% as compared with that of one-stage cup drawing. In addition, the Case 2 and Case 3 processes showed better product qualities than the Case 1 process when comparing distributions of thickness, hardness, dimensional accuracy.

• Communications of Mathematical Education
• /
• v.23 no.3
• /
• pp.707-734
• /
• 2009

The purpose of the study was to investigate how children understand addition and subtraction of fractions and how their understanding influences the solutions of fractional word problems. Twenty students from 4th to 6th grades were involved in the study. Children's understanding of operations with fractions was categorized into "joining", "combine" and "computational procedures (of fraction addition)" for additions, "taking away", "comparison" and "computational procedures (of fraction subtraction)" for subtractions. Most children understood additions as combining two distinct sets and subtractions as removing a subset from a given set. In addition, whether fractions had common denominators or not did not affect how they interpret operations with fractions. Some children understood the meanings for addition and subtraction of fractions as computational procedures of each operation without associating these operations with the particular situations (e.g. joining, taking away). More children understood addition and subtraction of fractions as a computational procedure when two fractions had different denominators. In case of addition, children's semantic structure of fractional addition did not influence how they solve the word problems. Furthermore, we could not find any common features among children with the same understanding of fractional addition while solving the fractional word problems. In case of subtraction, on the other hand, most children revealed a tendency to solve the word problems based on their semantic structure of the fractional subtraction. Children with the same understanding of fractional subtraction showed some commonalities while solving word problems in comparison to solving word problems involving addition of fractions. Particularly, some children who understood the meaning for addition and subtraction of fractions as computational procedures of each operation could not successfully solve the word problems with fractions compared to other children.

• Journal of the Korean Ceramic Society
• /
• v.35 no.9
• /
• pp.953-957
• /
• 1998

The effects of catalysts and reactive conditions on the synthesis of aluminum alkoxides are investigated. HgCl2 and I2 as catalysts are used in the synthesis reaction for comparing to no addtion. The absorption peak in IR spectra according to Al-O-L bond of aluminum isopropoxide and aluminum sec-butoxide appear at near 1030cm-1 and 1060cm-1 respectively regardless of kinds of catalysts. The synthesis yield of alu-minum-isopropoxide was 90% in case of no catalyst addition and increased to all of 95% by addition of HgCl2 and I2 The synthesis yield of aluminum sec-butoxide is increased to 95% by addition of I2 catalyst com-paring to no addition.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2014.05a
• /
• pp.236-237
• /
• 2014

Recently, it changes to the frame construction in the wall type structure for the life span improvement of the apartment house of our country. The execution of the light panel increased while the execution of the frame construction increased. Therefore, the density and absorption ratio of the magnesium oxide matrix according to the wood flour amount of addition ratio property try to be analyze for the lightweight of the surface material of the light panel. The test result, the density has been declined as the addition ratio increase of the wood flour. In the case of the water absorption ratio, water absorption ratio has been increased as addition ratio increase of wood flour. However, wood flour addition ratio 15% determined the most appropriate when considering the density and water absorption ratio.

• Journal of Korea Foundry Society
• /
• v.8 no.4
• /
• pp.459-466
• /
• 1988

This study was carried out in the austempering temperature and time after Ni, Mo addition in purpose of modification of impact toughness of austempered ductile irons. Addition of alloy element and austempering treatment of $900^{\circ}C$ 60 minutes followed by $300^{\circ}C$, $350^{\circ}C$ and $400^{\circ}C$ for 60 minutes, in this case impact value was increased by ideal mixed structure. But impact value was decreased when holing time is 120minutes, this is attributed to segregation and carbide precipitation from high carbon austenite. Highest impact value was obtained by $350^{\circ}C$ (Mo-addition) and $400^{\circ}C$ (Ni-addition). This phenomena was caused by presence of remained austenite. At all austempering temperature,, Ni-added specimen showed higher impact values than that of Mo-added specimen. And hardness property was affected by austempering temperature and holding time rather than amounts of alloying element.

• Clinics in Shoulder and Elbow
• /
• v.17 no.4
• /
• pp.205-208
• /
• 2014

Sternoclavicular joint posterior dislocations are considered a very uncommon, and type of injury where if esophagus or airway injury occurs behind the clavicle, it poses a high risk to the patient. In addition, if epiphyseal fracture occurs as a result of the sternoclavicular joint posterior dislocation, surgical treatment is often required. However, in the absence of a complete ossification of the clavicle, it is difficult to differentiate between a simple dislocation and epiphyseal fracture-dislocation solely based on simple radiographs or computed tomography scans. In this case report, the authors present a case in which a sternoclavicular joint posterior dislocation was diagnosed in a 14-year-old male athlete. The case report discusses how the posterior dislocation without epiphyseal fracture was diagnosed using an ultrasound and subsequently treated with successful outcomes using manual reduction. The case report presents our findings along with discussion that includes a literature review of relevant research.

• Journal of Pharmacopuncture
• /
• v.24 no.2
• /
• pp.54-58
• /
• 2021

Objectives: The purpose of this study is to investigate the effects of aerobic exercise and acupuncture treatment in obese patients. Methods: The effects of exercise in obese patients receiving acupuncture therapy were investigated in this retrospective, case-controlled study in which subjects complying with exercise were enrolled in the case and non-compliers were enrolled in the control group. Results: There was a statically significant weight loss in both the study case group (94.39 ± 20.36; 88.91 ± 19.00; n = 22; p = 0.001) and the control group (103.18 ± 21.92; 99.56 ± 21.92; n = 34; p = 0.001) after 3 months. Weight loss occurred in all 22 patients in the case group. In the control group, while weight loss occurred in 27 of the 34 patients, weight gain occurred in three patients. Conclusion: In conclusion, the addition of modalities such as acupuncture, exercise and diet may provide effective improvement in weight control.

• Journal of Acupuncture Research
• /
• v.40 no.2
• /
• pp.97-110
• /
• 2023

This review aimed to examine and analyze trends of clinical research using case studies on facial spasms in Korean medicine. Seven web databases were searched for case studies on facial spasms using Korean and English search terms. Case studies were selected using the exclusion and inclusion criteria. Overall, 13 case studies were selected, analyzed, and classified according to the publication year and journal, study participants, cause, treatment methods, pattern identification, evaluation methods, improvement, and side effects. Case studies reporting on various treatment methods in Korean medicine, including acupuncture and pharmacopuncture for facial spasms, have been published since 2000. In addition, studies on new treatment methods in Korean medicine for facial spasm have been published. Combination therapy is the most common method used in Korean medicine-based case studies; therefore, future studies on single treatment are necessary. Most of the case studies on Korean medicine reported improved symptoms and patient satisfaction with the Korean medicine treatment method. No side effects were reported, except for facial swelling and bruising, indicating that Korean medicine treatment methods for facial spasm were safe and effective. Therefore, the Korean medicine treatment methods for facial spasm can be actively used in clinical practice and future research.