High-entropy alloys (HEAs) have been reported to have better properties than conventional materials; however, they are more expensive due to the high cost of their main components. Therefore, research is needed to reduce manufacturing costs. In this study, CoCrFeMnNi HEAs were prepared using metal injection molding (MIM), which is a powder metallurgy process that involves less material waste than machining process. Although the MIM-processed samples were in the face-centered cubic (FCC) phase, porosity remained after sintering at 1200°C, 1250°C, and 1275°C. In this study, the hot isostatic pressing (HIP) process, which considers both temperature (1150°C) and pressure (150 MPa), was adopted to improve the quality of the MIM samples. Although the hardness of the HIP-treated samples decreased slightly and the Mn composition was significantly reduced, the process effectively eliminated many pores that remained after the 1275°C MIM process. The HIP process can improve the quality of the alloy.

High-entropy alloys (HEAs) are attracting attention because of their excellent properties and functions; however, they are relatively expensive compared with commercial alloys. Therefore, various efforts have been made to reduce the cost of raw materials. In this study, MIM is attempted using coarse equiatomic CoCrFeMnNi HEA powders. The mixing ratio (powder:binder) for HEA feedstock preparation is explored using torque rheometer. The block-shaped green parts are fabricated through a metal injection molding process using feedstock. The thermal debinding conditions are explored by thermogravimetric analysis, and solvent and thermal debinding are performed. It is densified under various sintering conditions considering the melting point of the HEA. The final product, which contains a small amount of non-FCC phase, is manufactured at a sintering temperature of 1250oC.

Headache is one of most common chief complaints of pediatric patients in emergency departments (ED). In this study, the character, duration, strength and location of headaches, as well as the results of brain imaging studies, were recorded. Seventy-four children (34 boys, 40 girls) visiting the ED of major hospitals in Cheongju were enrolled from October 1, 2013 to September 30, 2014. Ages of the children ranged from 3 to 18 years, with the mean age being 13 years. Four of them (5.4%) had trauma-related headaches. There were 34 migraines (45.9%), 27 tension headaches (36.5%), 3 secondary headaches (4.1%), 2 seizure-related headaches (2.7%), 1 headache with hydrocephalus (1.4%), 1 concussion (1.4%), and 1 headache with subdural hematoma (1.4%). The highest number of patients, 31 (41.9%), had symptoms for less than two hours, while 11 pediatric patients (14.9%) had symptoms for 2-4 hours, and the third-largest group, 10 patients (13.5%), had symptoms between 24 and 72 hours. Twenty-nine patients (39.2%) had one headache per month, 20 patients (27.0%) had 1 to 14 headaches per month, and 4 patients (5.4%) had more than 15 headaches per month. Children with migraine took a nonsteroidal anti-inflammatory drugs (NSAID, 34 patients; 45.9%), acetaminophen (19 patients; 25.7%), and Topiramate (1 patient; 1.4%). Average strength of headache was 7.37 ± 1.79. There were 23 children (31.1%) with headaches in the parieto-temporal area, 16 children (21.6%) in the occipital area, 9 children (12.2%) in the frontal area, 4 children (5.4%) in the global area, and 6 children (8.1%) in an uncertain location. There were 31 children (41.9%) with pulsating headaches, 18 children (24.3%) with squeezing headaches, 5 children (6.8%) with stabbing headaches, and 11 children (14.9%) with headaches of an uncertain nature. Thus, we suspect children visiting the ED had severe headaches.

Guillain-Barre´ syndrome (GBS) is an acute inflammatory demyelinating polyneuropathy most commonly characterized by rapidly progressive, essentially symmetric weakness and areflexia. This study examined clinical symptoms of clinical variants of GBS through a cerebrospinal fluid (CSF) study, nerve conduction (NCV) study, treatment, and prognosis. There were 16 children with GBS who visited our hospital from January 2011 to December 2013. Guillen-Barre´-like syndromes with transient synovitis were noted in three children. Clinical variants of GBS with acute demyelinating encephalomyelitis were observed in one child. Previous infections were noted in 16 children with Guillen-Barre´-like syndrome. There were ascending infections in 16 cases. Fifteen children showed symmetric infections, and one showed asymmetric infection. In NCV, slow waves were noted in two cases. We treated using intravenous immunoglobulin (IVIG) in four cases, IVIG with steroid in two, cases and supportive care in 10 (62.5%) cases. Five children treated with IVIG and 10 with supportive care management were completely improved.Our study suggests that supportive care is effective as a treatment for clinical variants of GBS. Further study is necessary for more patients.