• Structural Engineering and Mechanics
• /
• 제87권5호
• /
• pp.499-516
• /
• 2023

To defend against harmful gamma radiation, new types of materials for use in the construction of heavyweight concrete (HWC) are still needed to be developed. This research introduces new materials to be employed as a partial replacement for fine aggregate (FA) to manufacture high-performance heavyweight concrete (HPHWC). These materials include hematite, black sand, ilmenite, and magnetite, with substitution ratios of 50% and 100% of FA. In this research, the hardening and fresh characteristics of HPHWC were obtained. Concrete samples' Gamma-ray linear attenuation coefficient was evaluated utilizing a gamma source of Co-60 through the thicknesses of 2.5, 5, 7.5, 10, 12.5, and 15 cm. High temperatures were studied for HPHWC samples, which were exposed to up to 700℃ for two hours. Energy-dispersive x-rays and a scanning electron microscope carried out microstructure analyses. Magnetite as an FA attained the lowest compressive strength of 87.1 MPa, but the best radiation protection characteristics and the highest density of 3100 kg/m³ were achieved. After 28 days, the attenuation efficiency of concrete mixtures was increased by 6.5% when fine sand was replaced with black sand at a ratio of 50%. HPHWC, which contains hematite, black sand, ilmenite, and magnetite, is designed to reduce environmental and health dangers and be used in medicinal, military, and civil applications.

• Nuclear Engineering and Technology
• /
• 제55권6호
• /
• pp.2315-2324
• /
• 2023

Space nuclear reactors are becoming popular in deep space exploration owing to their advantages of high-power density and stability. Following the fourth-generation nuclear reactor technology, a conceptual design of the dual drum-controlled space molten salt reactor (D²-SMSR) is proposed. The reactor concept uses molten salt as fuel and heat pipes for cooling. A new reactivity control strategy that combines control drums and safety drums was adopted. Critical physical characteristics such as neutron energy spectrum, neutron flux distribution, power distribution and burnup depth were calculated. Flow and heat transfer characteristics such as natural convection, velocity and temperature distribution of the D²-SMSR under low gravity conditions were analyzed. The reactivity control effect of the dual-drums strategy was evaluated. Results showed that the D²-SMSR with a fast spectrum could operate for 10 years at the full power of 40 kWth. The D²-SMSR has a high heat transfer coefficient between molten salt and heat pipe, which means that the core has a good heat-exchange performance. The new reactivity control strategy can achieve shutdown with one safety drum or three control drums, ensuring high-security standards. The present study can provide a theoretical reference for the design of space nuclear reactors.

• Journal of Microbiology and Biotechnology
• /
• 제33권4호
• /
• pp.519-526
• /
• 2023

Panax ginseng is one of the most important herbal medicinal plants consumed as health functional food and can be fermented to achieve better efficacy. Lacticaseibacillus, one of the representative genera among lactic acid bacteria (LAB), has also been used as a probiotic material for health functional foods due to its beneficial effects on the human body. To achieve a synergistic effect by using these excellent dietary supplement ingredients together, a novel LAB strain was isolated from the root of 6-year-old ginseng. Through similarity analysis of 16S rRNAs and whole-genome sequences, the strain was confirmed as belonging to the genus Lacticaseibacillus and was named L. casei KGC1201. KGC1201 not only met all safety standards as food, but also showed excellent probiotic properties such as acid resistance, bile salt resistance, and intestinal adhesion. In particular, KGC1201 exhibited superior acid resistance through morphological observation identifying that the cell surface damage of KGC1201 was less than that of the L. casei type strain KCTC3109. Gene expression studies were conducted to elucidate the molecular mechanisms of KGC1201's acid resistance, and the expression of the glycosyltransferase gene was found to be significantly elevated under acidic conditions. Exopolysaccharides (EPSs) biosynthesized by glycosyltransferase were also increased in KGC1201 compared to KCTC3109, which may contribute to better protection of KGC1201 cells from strong acidity. Therefore, KGC1201, with its increased acid resistance through molecular mechanisms and excellent probiotic properties, can be used in health functional foods to provide greater benefit to overall human health and well-being.

• 아태비즈니스연구
• /
• 제13권4호
• /
• pp.151-161
• /
• 2022

Purpose - The purpose of this study is to redefine imperial cultural properties and pass on and provide the elegant value of imperial cultural properties with the Allen Collection's promotion to retrieve imperial cultural properties. Design/methodology/approach - This study was approached to deal with the essential interpretation of cultural improvement through discussion in the cultural science approach Findings - As a result of examining ways to revitalize tourism resources using Allen Collection, it is necessary to cultivate international manners and knowledge levels in strengthening imperial awareness through the establishment of imperial museums, enacting laws on standards for designation of imperial cultural assets, and promoting them. In addition, policy needs such as the development plan of the imperial cultural festival, re-establishment, application, reuse, re-establishment, and reproduction according to environmental changes, and technical support and monitoring systems for investigating and preserving imperial cultural assets are needed. Research implications or Originality - The study on the device imperial cultural assets as tour resources the cultural assets mate be not only preserved and inherited to the descendant but also useful in contemporary national emotion positively. for we could obtain wide national support and co-operation in the protection work of cultural assets. What makes our cultural assets leaved indifferent before destruction like this most of all, it is form indifference of the people, we must make an effort to meet with recognizing the value of useful cultural assets by mean of utilizing cultural assets as tour resources to inhibit more damage of destruction of cultural assets.

• 한국산업보건학회지
• /
• 제33권4호
• /
• pp.419-426
• /
• 2023

Objectives: This study aims to develop an Occupational Safety and Health (OSH) guide for the safe cleaning of contaminated machinery, equipment, and parts used in the electronics manufacturing process. Methods: A literature review, field investigations, and discussions were conducted. An initial draft of an OSH guide was developed and reviewed by experts with significant experience in maintenance work in the electronics manufacturing process in order to refine the guide. Results: Workers involved in cleaning processes with chemicals, solvents, and abrasive blasting can face exposure to a wide range of chemicals, abrasives, and noise. Identifying potential risks associated with each cleaning technique was an essential first step toward enhancing safety measures. The OSH guide comprises approximately eleven to twelve sections spanning 20-25 pages. It includes engineering and administrative protocols systematically organized to address the necessary actions before, during, and after cleaning tasks, depending on the technique. It is recommended that airline respirator masks be used in conjunction with an air purification system to ensure adherence to air quality standard "D" for atmosphere level. The use of an oil-free air compressor is advised, preferably a stationary model that does not rely on fuel sources like diesel. Conclusions: This OSH guide is designed to protect workers involved in maintenance activity in the electronics industry and aligns with global standards, such as those from the International Organization for Standardization (ISO) and Semiconductor Equipment and Material International, ensuring a higher level of safety and compliance.

• 한국산업보건학회지
• /
• 제34권2호
• /
• pp.125-133
• /
• 2024

Objectives: The aim of this study is to develop a comprehensive Occupational Safety and Health (OSH) guide for maintenance tasks in semiconductor processing, specifically focusing on etching, deposition, and ion implantation processes. Methods: The development of the OSH guide involved a literature review, consultations with industry experts, and field investigations. It concentrates on Maintenance Work (MW) operations in these specialized areas. Results: The result is a detailed OSH guide tailored to MW in etching, deposition, and ion implantation facilities within semiconductor processing. This guide is structured to assist maintenance workers through pre-, during and post-MW phases, ensuring easy comprehension and adherence to safety protocols. It highlights the necessity of safety and health measures throughout the MW process to protect personnel. The guide is enriched with real-life scenarios and visual aids, including cartoons and photographs, to aid in the understanding and implementation of safety and health principles. Conclusions: This OSH guide is designed to enhance the protection of workers engaged in maintenance activities in the electronics sector, particularly in semiconductor manufacturing. It aims to improve compliance with safety and health standards in these high-risk environments.

• Nuclear Engineering and Technology
• /
• 제56권7호
• /
• pp.2740-2747
• /
• 2024

The sintering process acquired ferromagnetic copper ferrite ceramic material with a small concentration of Ni ion at 1100 ℃ for 1 h. Previously, copper ferrite with Ni proportions powder was acquired by the wet chemical process according to the relation CuFe_2-xNi_xO₄ where x takes values 0.0, 0.015, 0.03, 0.04, and 0.05. The role of Ni ion in the copper ferrite structure was investigated by X-ray analysis, Scanning electron microscope, EDX analysis, and density measurements. The gamma-ray shielding properties for the fabricated CuFeNiO ceramics samples were evaluated using the Monte Carlo simulation method. The obtained results show an enhancement in the linear attenuation coefficient for the fabricated ceramics with increasing the insertions of Ni ions within the fabricated samples, where increasing the Ni ions concentration between 0 and 1.19 wt% increases the linear attenuation by between 1.581 and 1.771 cm^-1 (at 0.103 MeV), 0.304-0.338 cm^-1 (at 0.662 MeV), and 0.160-0.178 cm^-1 (at 2.506 MeV), respectively. Simultaneously, the radiation protection efficiency for a 1 cm thickness of the fabricated samples increased between 14.8 and 16.3% with increasing the Ni ions between 0 and 1.19 wt%. Although the Ni doping concentration does not exceed 1.5 wt% of the total composition of the fabricated ceramics, the shielding capacity of the fabricated ceramics was enhanced by more than 11%, along the studied energy interval. Therefore, the fabricated samples can be used in gamma-ray shielding applications.

• 한국전통조경학회지
• /
• 제33권4호
• /
• pp.148-165
• /
• 2015

1962년 제정된 문화재보호법은 지속적인 개정을 통해 급속한 경제성장 과정에서 문화재의 체계적인 보존 관리 및 활용에 그 역할을 다해왔다. 특히, 2000년에는 문화재 영향검토제도를 도입하고, 2006년에는 국가지정문화재 현상변경 허용기준 마련 지침을 제정하며 문화재 및 역사문화환경의 보존과 더불어 행정효율성 제고, 정주환경 개선에 상당한 기여를 하고 있다. 그러나, 문화재 가치에 대한 국민의식 향상과 문화유산을 활용한 지역 활성화의 필요성이 대두되는 동시에 문화재 가치 및 유형적 특성, 토지이용실태 등 주변 여건을 적의 반영하지 못하는 일부 허용기준을 적용함에 따라 주민 불편사항이 계속 제기되고 있어, 본 연구는 문화재의 핵심가치를 명확히 하고, 이를 반영한 문화재 유형별 현상변경 검토기준 마련을 목적으로 하였다. 이에 문화재보호법 및 관련 지침 매뉴얼, 각종 연구자료 등의 분석을 통해 물적 특성 및 본연의 가치를 적극적으로 보존 관리하기 위한 경관관리 중점지표를 설정하고, 현상변경 관점에서 문화재 유형분류체계를 재분류하여 현상변경 검토기준을 제시하였다. 이를 통해, 단기적으로는 문화재 가치 및 유형별 특성을 반영한 역사문화환경의 체계적 관리와 검토기준의 일관성을 확보하는 한편, 이를 적용한 허용기준의 조정을 통해 기준설정에 대한 대국민 이해도 증진을 도모함으로써 문화재 관리행정에 대한 만족도가 제고되길 기대한다.

• Journal of Radiation Protection and Research
• /
• 제41권1호
• /
• pp.41-47
• /
• 2016

연구배경: 세기조절방사선치료와 같이 고선량을 암조직에 정밀하게 전달할 수 있는 방사선 치료기술이 개발됨에 따라, 보다 정확한 선량평가 기술의 개발이 요구되고 있다. 본 연구에서는 선형가속기에서 발생된 광자선의 물질투과율 정보를 통해 간접유도방식으로 에너지스펙트럼을 예측할 수 있는 기술의 개발을 목적으로 한다. 재료 및 방법: 의료용 선형가속기를 사용한 측정과 몬테칼로 전산모사를 통해 감쇠물질의 두께에 따른 X-선의 투과율이 평가되었으며, 이와 더불어 단일에너지에 의한 이온함의 반응함수가 결정되었다. 최종적으로 Unfolding 방법을 사용하는 HEOROW 프로그램을 통해 고선량률의 치료용 선형가속기에서 발생된 광자선의 에너지스펙트럼이 유도되었다. 본 연구에서 실험을 위해 Elekta Synergy Flatform 선형가속기가 사용되었으며, 몬테칼로 방법을 사용하는 Geant4 전산모사 프로그램이 사용되었다. 결과 및 논의: 감쇠물질의 두께에 따른 X-선 투과율과 몬테칼로 전산모사를 통해 계산된 X-선 투과율의 비교 결과 0.43%의 평균제곱근오차가 확인된다. 물질투과정보를 통해 간접적으로 유도된 에너지스펙트럼은 몬테칼로 전산모사를 통해 직접적으로 계산된 에너지스펙트럼과 비교분석 되었으며, 피크위치 및 평균에너지의 오차가 각각 0.066 MeV와 0.03 MeV로 평가되었다. 하지만 보다 정확한 에너지스펙트럼을 예측하기 위해서는 다양한 감쇠물질의 사용과 에너지스펙트럼 유도프로그램의 정밀도 향상을 위한 추가적인 연구가 필요할 것으로 판단된다. 결론: 본 연구를 통해 확인된 물질투과율 기반의 에너지스펙트럼 측정 기술은 에너지가 높고 선량률이 높기 때문에 광자선을 직접적으로 측정하는 것이 제한적인 의료용 선형가속기에 적용될 수 있을 것으로 판단된다.

• Journal of Radiation Protection and Research
• /
• 제39권1호
• /
• pp.38-45
• /
• 2014

본 연구에서는 대덕 원자력부지에 위치한 원자력관계시설들에 의한 방사선환경의 안전성을 확인하기 위해, 기체상 및 액체상 유출물에 의한 주민선량평가를 수행하였다. 이를 위해 2010년부터 2012년까지의 3년간 대덕부지의 기상자료 및 환경으로 방출된 선원항 자료를 기반으로 하여 개인 최대피폭선량을 평가, 분석하였다. 기체상 유출물의 대기확산 인자 및 침적인자는 XOQDOQ 전산코드를 이용하여 계산하였다. 기체상과 액체상 방사성물질의 방출에 의한 최대개인선량(이하 개인선량)계산은 각각 ENDOS-G와 ENDOS-L 코드를 사용하였고, 원자력안전위원회 고시 제 2012-29에 제시된 부지당 연간기준치와 비교하였다. 최대피폭지점에서의 개인의 유효선량과 갑상선선량을 계산하였고, 이에 대한 피폭영향에 미치는 기여도를 분석하였다. 그 결과, 최대 피폭연령군은 소아로 평가되었으며 하나로 운영에 의한 영향이 90% 이상 지배적인 것으로 나타났다. 또한 기체상유출물에 의한 주요피폭경로는 섭취와 호흡에 의한 것이며, 유효선량에는 삼중수소가, 갑상선 등가선량에는 방사성옥소가 가장 영향을 많이 미치는 것으로 분석되었다. 선량평가시 기체상유출물이 90% 이상 기여하였고 액체상유출물에 의한 기여도는 상대적으로 낮은 것으로 나타났다. 결과적으로, 대덕부지의 원자력관계시설들에 의한 부지 내 개인선량은 최대 기준치의 3% 이내로 평가되어 환경에 미치는 영향이 매우 적은 것으로 확인되었다.