Improvement of a block co-polymer (PS-b-PMMA)-masked silicon etch profile using a neutral beam.

Bottom-up block copolymer (BCP) lithography mediated by self-assembly of polystyrene (PS)/poly-methyl methacrylate (PMMA) is widely used as an alternative patterning method for various deep nanoscale devices, such as optical devices and transistors, replacing conventional top-down photolithography. However, the nanoscale BCP mask features formed on the substrates after direct self-assembly of BCP tend to be easily damaged during exposure to the following plasma processing. In this study, silicon masked with a nanoscale BCP mask (PS) was etched by irradiating with a Cl2/Ar neutral beam in addition to a Cl2/Ar ion beam, and the effect of a Cl2/Ar neutral beam instead of a Cl2/Ar ion beam on damage to the PS mask and the silicon etch characteristics of nanodevices was investigated.

Seropositivity among Korean Young Adults Approximately 2 Years after a Single-Dose Vaccination against Hepatitis A Virus.

We previously observed 80.7% seropositivity and a significant interaction between gender and hepatitis A virus (HAV) vaccine type (Havrix vs. Epaxal) on the seropositivity approximately 11 months after single-dose HAV vaccinations in Korean young adults.

Acute health effects of accidental chlorine gas exposure.

Objectives: This study was conducted to report the course of an accidental release of chlorine gas that occurred in a factory in Gumi-si, South Korea, on March 5, 2013. We describe the analysis results of 2 patients hospitalized because of chlorine-induced acute health problems, as well as the clinical features of 209 non-hospitalized patients.

Methods: We analyzed the medical records of the 2 hospitalized patients admitted to the hospital, as well as the medical records and self-report questionnaires of 209 non-hospitalized patients completed during outpatient treatment.

The immunogenicity of a single dose of hepatitis A virus vaccines (Havrix® and Epaxal®) in Korean young adults.

Purpose: Assessing the immunogenicity of a single dose of hepatitis A virus (HAV) vaccines is important because some people receive only a single dose. However, previous studies have shown variable results and have not examined the effects of demographic characteristics other than gender. This study was performed to examine the immunogenicity of a single dose of HAV vaccine according to the vaccine type and demographic characteristics in young adults.

Factors affecting the burden on caregivers of stroke survivors in South Korea.

Objective: To elucidate the factors related to the caregiver burden in stroke survivors in Seoul, Korea.

Design: Cross-sectional study.

Setting: Outpatient clinic of a university hospital in Korea.