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.
This study prepares highly porous carbon (c-fPI) for lithium-ion battery anode that starts from the synthesis of fluorinated polyimide (fPI) via a step polymerization, followed by carbonization. During the carbonization of fPI, the decomposition of fPI releases gases which are particularly from fluorine-containing moiety (–CF3) of fPI, creating well-defined microporous structure with small graphitic regions and a high specific surface area of 934.35 m2 g− 1. In particular, the graphitic region of c-fPI enables lithiation–delithiation processes and the high surface area can accommodate charges at electrolyte/electrode interface during charge–discharge, both of which contribute electrochemical performances. As a result, c-fPI shows high specific capacity of 248 mAh g− 1 at 25 mA g− 1, good rate-retention performance, and considerable cycle stability for at least 300 charge–discharge cycles. The concept of using a polymeric precursor (fPI), capable of forming considerable pores during carbonization is suitable for the use in various applications, particularly in energy storage systems, advancing materials science and energy technologies.
The demand for transportation is increasing due to the continuous generation of radioactive wastes. Especially, considering the geographical characteristics of Korea and the location characteristics of nuclear facilities, the demand for maritime transportation is expected to increase. If a sinking accident happens during maritime transportation, radioactive materials can be released into the ocean from radioactive waste transportation containers. Radioactive materials can spread through the ocean currents and have radiological effects on humans. The effect on humans is proportional to the concentration of radioactive materials in the ocean compartment. In order to calculate the concentration of radioactive materials that constantly flow along the ocean current, it is necessary to divide the wide ocean into appropriate compartments and express the transfer processes of radioactive materials between the compartments. Accordingly, this study analyzed various ocean transfer evaluation methodologies of overseas maritime transportation risk codes. MARINRAD, POSEIDON, and LAMER codes were selected to analyze the maritime transfer evaluation methodology. MARINRAD divided the ocean into two types of compartments that water and sediment compartments. And it was assumed that radionuclides are transfered from water to water or from water to sediment. Advection, diffusion, and sedimentation were established as transfer process for radionuclides between compartments. MARINRAD use transfer parameters to evaluate transer processes by advection, diffusion, and sedimentation. Transfer parameters were affected by flow rate, sedimentation rate, sediment porosity, and etc. POSEIDON also divided the ocean into two types that water and sediment compartment, each compartments was detaily divided into three vertical sub-compartment. Advection, diffusion, resuspension, sedimentation, and bioturbation were established as transport processes for radionuclides between compartments. POSEIDON also used transfer parameters for evaluating advection, diffusion, resuspension, sedimentation, and bioturbation. Transfer parameters were affected by suspended sediment rates, sedimentation rates, vertical diffusion coefficients, bioturbation factors, porosity, and etc. LAMER only considered the water compartment. It divided the water compartment into vertical detailed compartments. Diffusion, advection and sedimentation were established as the nuclide transfer processes between the compartments. To evaluated the transfer processes of nuclides for diffusion and advection, LAMER calculated the probability with generating random position vectors for radionuclides’ locations rather than deterministic methods such as MARINRAD’s transfer parameters or POSEIDON’s transfer rates to evaluate transfer processes. The results of this study can be used as a basis for developing radioactive materials’ ocean transfer evaluation model.
As nuclear power plants are operated in Korea, low and intermediate-level radioactive wastes and spent nuclear fuels are continuously generated. Due to the increase in the amount of radioactive waste generated, the demand for transportation of radioactive wastes in Korea is increasing. This can have radiological effect for public and worker, risk assessment for radioactive waste transportation should be preceded. Especially, if the radionuclides release in the ocean because of ship sinking accident, it can cause internal exposure by ingestion of aquatic foods. Thus, it is necessary to analyze process of internal exposure due to ingestion. The object of this study is to analyze internal exposure by ingestion of aquatic foods. In this study, we analyzed the process and the evaluation methodology of internal exposure caused by aquatic foods ingestion in MARINRAD, a risk assessment code for marine transport sinking accidents developed by the Sandia National Laboratory (SNL). To calculate the ingestion internal exposure dose, the ingestion concentrations of radionuclides caused by the food chain are calculated first. For this purpose, MARINRAD divide the food chain into three stages; prey, primary predator, and secondary predator. Marine species in each food chain are not specific but general to accommodate a wide variety of global consumer groups. The ingestion concentrations of radionuclides are expressed as an ingestion concentration factors. In the case of prey, the ingestion concentration factors apply the value derived from biological experiments. The predator's ingestion concentration factors are calculated by considering factors such as fraction of nuclide absorbed in gut, ingestion rate, etc. When calculating the ingestion internal exposure dose, the previously calculated ingestion concentration factor, consumption of aquatic food, and dose conversion factor for ingestion are considered. MARINRAD assume that humans consume all marine species presented in the food chain. Marine species consumption is assumed approximate and conservative values for generality. In the internal exposure evaluation by aquatic foods ingestion in this study, the ingestion concetration factor considering the food chain, the fraction of nuclide absorbed in predator’s gut, ingestion rate of predator, etc. were considered as influencing factors. In order to evaluate the risk of maritime transportation reflecting domestic characteristics, factors such as domestic food chains and ingestion rate should be considered. The result of this study can be used as basis for risk assessment for maritime transportation in Korea.
기업의 혁신적이고 적극적인 성향 또는 활동인 기업가 지향성은 최근 국제경영 분야에서 중요하 게 연구되고 있다. 특히, 기업가 지향성은 기업의 학습 및 역량 개발을 촉진하고, 새로운 시장의 기 회를 인지하고 포착하며, 경쟁 기업들과의 차별화를 가능하게 한다는 점에서 성과에 긍정적인 영향 을 미친다는 주장이 있다. 일부 연구에서는 기업가 지향성이 오히려 성과에 유의미한 영향을 미치 지 않는다는 연구결과도 나타났다. 하지만, 기업가 지향성과 성과 간의 관계는 기업의 자원 및 역 량 등 내부적 환경에 따라 상의할 가능성이 크다. 본 연구에서는 기업의 내부적 요인으로서 흡수 역량이 기업가 지향성의 실행에 영향을 미치는 주요 요인으로 작용할 수 있다는 점을 고려해서 흡 수 역량의 두 가지 차원(잠재적 흡수 역량, 실현적 흡수 역량)이 기업가 지향성-수출 성과에 미치 는 영향을 실증적으로 분석하고자 한다. 한국 수출 기업들을 대상으로 기업가 지향성, 흡수 역량, 수출 성과에 대한 설문 조사를 실시하였다. 분석 결과, 기업가 지향성은 수출 성과에 긍정적인 영 향을 미치며, 기업의 실현된 흡수 역량이 높을수록 기업가 지향성의 긍정적인 영향은 강화되는 것 으로 나타났다. 이에, 본 연구는 기업가 지향성-수출 성과 간의 관계에 영향을 미치는 기업의 내부 적 요인을 검증함으로써 학문적 및 실무적 관점에서 의미 있는 시사점을 제공할 수 있을 것으로 기 대된다.
An 8-year-old, spayed female Maltese dog was presented with a one-month history of erythema, swelling and alopecia of periocular region with pruritus. The skin lesions were first detected at the age of three years, but this was the first time that symptoms had appeared in the eyes. Physical examination revealed markedly swollen and erythematous eyelids and conjunctiva including Meibomian glands. In addition, periocular alopecia and tears were identified. Slit lamp microscopy revealed erythema of conjunctiva and swelling of Meibomian glands. The Schirmer’s tear test was normal. Impression smear cytology of eyes revealed sterile neutrophils and corneal epithelial cells. There were no virus or bacterial infections in the eyes. On skin examination, generalized erythema was detected but there were no other skin lesions. A case of allergic blepharoconjunctivitis associated with canine atopic dermatitis was diagnosed based on history taking and skin examination. Treatment included cetirizine, cyclosporine, prednisolone and Forus eye drops®. The owner was instructed to wear an Elizabethan collar around his dog's neck at all times and restrict walking. And the diet was changed to hypoallergenic dog food. Medications and environmental restrictions significantly reduced erythema, edema and swelling of meibomian glands. Pruritus was also decreased. Six weeks later, the edema lesions of eyes disappeared.
최근 기업들의 해외시장진출이 활발해지면서 글로벌 시장에서의 신제품개발속도에 대한 관심이 높아지고 있다. 본 연구는 신제품개발속도를 글로벌 관점에서 살펴보고, 더 나아가 기업특성과 시장 환경 특성이 글로벌 시장에서의 신제품개발속도에 미치는 영향을 실증적으로 분석하고자 한다. 이를 위해 한국 제조업체들을 대상으로 신제품개발 및 제품 성과에 대한 설문조사를 실시하였다. 실증분석 결과, 기업 및 시장 환경 특성 중에서도 기업 규모, 제품특성, 시장불확실성이 글로벌 시장에서의 신제품개발속도에 유의미한 영향을 미치는 것으로 나타났다. 이에 본 연구는 글로벌적 관점에서 신제품개발속도에 영향을 미치는 요인들을 검증함으로써 학문적 및 실무적 관점에서 의미있는 시사점을 제공할 수 있을 것으로 기대된다.