원자력발전소(원전) 내부에 설치되어 있는 주요 기기는 원전의 안정적인 운영을 돕는 주요 2차 구조 물이다. 경주 지진, 포항 지진과 같은 강한 지진이 발생하였을 때, 원전 주요 기기의 손상은 원전의 안정한 정지에 문제를 초래할 수 있다. 따라서, 원전 주요 기기의 지진응답을 저감시키기 위한 연구가 필수적으로 요구된다. 이러한 배경 아래, 본 연구에서는 원전 주요 기기의 내진성능 향상을 위하여 동 흡진장치(Dynamic Absorber)를 활용하였다. 연구에서 사용된 동흡진장치는 스프링, 댐퍼, 및 질량체로 구성된다. 이러한 동흡진장치를 설계하기 위하여 기존에 제안된 방법론들을 활용하였으며, 각 방법론 들을 기반으로 설계된 동흡진장치의 지진응답 저감효과를 비교 및 분석하였다. 구체적으로, 진동대 시 험 결과를 바탕으로 유한요소 모델을 검증하였다. 또한, 이를 기반으로 기존 동흡진장치의 설계방법론 에 따른 원전 주요 기기의 지진응답 저감 효과를 비교 및 분석하였다. 결과적으로 각 방법론들은 원전 주요기기의 가속도, 변위, 응력 응답을 평균적으로 약 30% 정도 감소시키는 효과를 보였다.

Geopolymer, also known as alkali aluminum silicate, is used as a substitute for Portland cement, and it is also used as a binder because of its good adhesive properties and heat resistance. Since Davidovits developed Geopolymer matrix composites (GMCs) based on the binder properties of geopolymer, they have been utilized as flame exhaust ducts and aircraft fire protection materials. Geopolymer structures are formed through hydrolysis and dehydration reactions, and their physical properties can be influenced by reaction conditions such as concentration, reaction time, and temperature. The aim of this study is to examine the effects of silica size and aging time on the mechanical properties of composites. Commercial water glass and kaolin were used to synthesize geopolymers, and two types of silica powder were added to increase the silicon content. Using carbon fiber mats, a fiber-reinforced composite material was fabricated using the hand lay-up method. Spectroscopy was used to confirm polymerization, aging effects, and heat treatment, and composite materials were used to measure flexural strength. As a result, it was confirmed that the longer time aging and use of nano-sized silica particles were helpful in improving the mechanical properties of the geopolymer matrix composite.

This study aimed to determine the optimal planting density for sesame cultivation in a double cropping system after harvesting onion and garlic in the Muan region. It compared the growth, yield, disease susceptibility, and labor hours for two varieties of sesame (Landrace and Geonbaek sesame) at different planting densities. Plant height in the Landrace sesame showed no significant variation with different planting densities, whereas Geonbaek sesame increased in height with higher planting densities. Both cultivars increased the number of viable branches at lower densities. The stem diameter was thicker in Landrace sesame with decreasing planting density, while in the Geonbaek sesame, there was no significant difference in stem diameter regardless of planting density. The number of capsules per plant for the Landrace sesame increased with decreasing density, whereas Geonbaek sesame showed no significant difference. Yield for both cultivars was higher at greater densities. However, the late direct sowing time and shorter cultivation period significantly reduced the yield of sesame cultivated in a double cropping system compared to that of sesame grown in a single cropping system, due to the late direct sowing time and shorter cultivation period. There was no significant difference in disease occurrence based on planting density. Furthermore, although labor hours did not vary with planting density when comparing the labor hours required for cultivating the Landrace sesame and Geonbaek sesame, the latter needed less labor time. This study reveals the optimum planting distance and density for sesame cultivation as a double cropping after harvesting onion and garlic, providing invaluable data for establishing sesame double cropping cultivation techniques.

In ecosystems within limited resources, interspecific competition is inevitable, often leading to the competitive exclusion of inferior species. This study aims to provide foundational information for the conservation and restoration management of Microphysogobio rapidus by evaluating species’ ecological response to biological factors within its habitat. To understand this relationship, we collected food web organisms from site where M. rapidus coexist with Microphysogobio yaluensis, a specie ecologically similar to M. rapidus, and evaluated the trophic levels (TL), isotopic niche space (INS), and the overlap of INS among fishes within the habitat using stable isotope analysis. Our analysis revealed that the M. rapidus exhibited a higher TL than M. yaluensis, with TL of 2.6 and 2.4, respectively. M. yaluensis exhibited a broad INS, significantly influencing the feeding characteristics of most fish. Conversely, M. rapidus showed a narrow INS and asymmetric feeding relationships with other species, in habitats with high competition levels. This feeding characteristics of M. rapidus indicate that the increase in competitors sharing the similar resources lead to a decrease in available resources and, consequently, is expected to result in a decrease in their density.

해안지역은 육지와 물이 상호작용하는 독특한 특징이 있어 사람들이 자연환경을 육체적 및 정신적으로 향유하고 체험하도록 유도하며, 이는 문화생태계서비스(이하 문화서비스)를 형성한다. 문화서비스가 가장 많이 이루어지는 해안지역은 해수욕장이다. 본 연구 의 목적은 1) 해수욕장에서 얻는 문화서비스의 경제적 가치를 추정하고, 2) 편익이전법을 이용하여 가치를 전국 해수욕장으로 확장하는 것이다. 선행연구를 심층적으로 검토하여 문화서비스를 관광·휴양, 경관·심미, 교육, 유산, 영감 등 다섯 가지 범주로 나누었다. 관광·휴양, 경관·심미, 교육 서비스는 선택실험법을 통해 가치를 추정하였다. 선택실험법의 속성은 보전기금, 쓰레기, 수질, 바다 경관, 주변지역 경 관, 생물종다양성이며 11곳의 해수욕장 방문자를 대상으로 한 온라인 설문조사를 통해 자료를 수집하였다. 유산과 영감 서비스는 지출액 을 묻는 시장재화법으로 가치를 평가하였다. 도출한 가치는 전국의 257개 해수욕장으로 편익이전하여 평가하였다. 연구결과는 해수욕장 에 대한 연안침식과 개발에 따른 복원, 공공투자 여부와 투자 규모에 대한 정책 결정을 위한 근거로 활용될 수 있을 것이다.

분리막 기술은 해수담수화, 기체분리 등 산업용 분리 정제 공정을 비롯하여 우리 주변의 생활용품, 의료 및 헬스 케어 제품 등에서 쉽게 찾아볼 수 있다. 최근 지속가능한 친환경 분리막 제조 기술 또한 환경오염을 줄이기 위해 연구되고 있으며, 특히 polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS) 등 생분해성 소 재를 활용한 분리막 제조기술이 보고되어 왔다. 기존 분리막 소재와 마찬가지로 생분해성 고분자 소재들 또한 상분리 공정을 통해 다공성 분리막을 제조하는 연구가 이루어지고 있다. 본 총설을 통해 대표적인 생분해성 고분자인 PLA 기반의 상분리 공정을 활용한 분리막 제조 기술 개발 동향을 살펴보고 향후 연구 개발 및 적용 가능성에 대해 고찰해보고자 한다.

본 연구는 간호학생을 대상으로 뇌졸중 표준화 환자를 활용한 시뮬레이션기반 교육 경험을 심 층적으로 이해하고 이를 통해 경험의 본질을 파악하고자 함이다. 자료수집은 2023년 6월 25일부터 자료가 포화상태에 이르게 된 2023년 8월 25일까지 간호학생 10명을 대상으로 심층 개별 인터뷰를 통해 수집되었 고, Colaizzi가 제시한 현상학적 연구 분석 방법으로 분석되었다. 주요 인터뷰 질문은 “뇌졸중 표준화 환자 를 활용한 교육 경험은 당신에게 어떤 의미가 있었나요?”이었고, 수집된 데이터는 내용분석을 이용하여 분 석하였다. 연구결과, 총 7개의 의미있는 진술이 추출되었고, 도출된 주제모음은 ‘간호 교육적 차원’, ‘개인 적 차원’, ‘간호 직무적 차원’으로 나타났다. 이로써 뇌졸중 표준화 환자 활용은 간호학생들의 실무역량 습 득과 뇌졸중 환자간호에 대한 이해를 높였고, 표준화 환자 활용에 있어 긍정적인 요인강화와 제한된 요인 들을 파악하여 실무역량을 증진하기 위한 시뮬레이션기반 교육전략이 필요함을 알 수 있다.

This study was performed to investigate antioxidant and anti-inflammatory activities of perilla(Perilla frutescens L.) seed, flower and leaf according to extraction condition. Perilla seed extracts(PSE), perilla flower extracts(PFE), perilla leaf extracts(PLE) was extracted by stirring extraction (STE, 25°C), shaking extraction (SHE, 80°C), and sonication assisted extraction(SAE, , 25°C) with 94% ethanol, 60% ethanol and distilled water, followed by analysis of total polyphenol and flavonoid and testing radical scavenging activities. The highest total polyphenol content (5.47, 9.36, 38.58 mg gallic acid equivalent/g), total flavonoid content(5.77, 8.62, 46.44 mg catechin equivalent/g), ABTS(10.68, 19.46, 63.56 mg trolox equivalent/g) and DPPH(6.51, 7.69, 79.73 mg trolox equivalent/g) radical scavenging activity of PSE, PFE and PLE was observed in the HWE with 60% ethanol,. Among the three extraction method, SHE provided the best results for yield, polyphenol, flavonoid content of perilla seed, flower, leaf in comparison to STE or SAE. SHE with 60% ethanol of perilla seed, flower, leaf more effectively inhibited secretion of nitric oxide(NO) and pro-inflammatory cytokine in RAW 264.7 macrophage exposed to LPS compared to other extraction solvent and method. Therefore, these extracts obtained from perilla seed, flower, leaf could be used antioxidant and anti-inflammatory ingredients in the food industry.

The theoretical capacity of silicon-based anode materials is more than 10 times higher than the capacity of graphite, so silicon can be used as an alternative to graphite anode materials. However, silicon has a much higher contraction and expansion rate due to lithiation of the anode material during the charge and discharge processes, compared to graphite anode materials, resulting in the pulverization of silicon particles during repeated charge and discharge. To compensate for the above issues, there is a growing interest in SiOx materials with a silica or carbon coating to minimize the expansion of the silicon. In this study, spherical silica (SiO2) was synthesized using TEOS as a starting material for the fabrication of such SiOx through heating in a reduction atmosphere. SiOx powder was produced by adding PVA as a carbon source and inducing the reduction of silica by the carbothermal reduction method. The ratio of TEOS to distilled water, the stirring time, and the amount of PVA added were adjusted to induce size and morphology, resulting in uniform nanosized spherical silica particles. For the reduction of the spherical monodisperse silica particles, a nitrogen gas atmosphere mixed with 5 % hydrogen was applied, and oxygen atoms in the silica were selectively removed by the carbothermal reduction method. The produced SiOx powder was characterized by FE-SEM to examine the morphology and size changes of the particles, and XPS and FT-IR were used to examine the x value (O/Si ratio) of the synthesized SiOx.

This study conducted an investigation into the effects of fruit type and cultivation practices (organic and conventional) on soil characteristics and soil arthropod communities within apple, blueberry, grape, peach, and pear orchards. The collection of soil arthropod communities was achieved through the utilization of pitfall traps, with concurrent measurements taken for soil moisture content, electrical conductivity, and temperature. The findings of this study unveiled substantial impacts attributed to fruit type and cultivation practices on soil characteristics. Specifically, within organic apple orchards, discernibly higher levels of soil moisture content, electrical conductivity, and temperature were observed when compared to their conventional counterparts. The investigation into soil arthropod communities yielded a total of 1,527 individuals, classified in to five phyla and 15 orders. The range of abundance, species richness, and diversity indices varied across conventional and organic orchards. Cultivation practices were found not to exert a significant influence on soil arthropod community characteristics. However, Non-metric Multidimensional Scaling (NMDS) analysis indicated a significant differentiation in soil arthropod community structure based on cultivation practices. This study underscores the importance of considering vegetation structure and environmental characteristics that may influence soil arthropod communities comprehensively when assessing the impact of cultivation practices on soil arthropods. Furthermore, it emphasizes the need to account for both the characteristics and structure of soil arthropod communities in understanding the implications of cultivation practices on these organisms.

This study investigates the integration of astronomy-related topics in the Korean national science curricula spanning from 1945 to 2023. We analyze the placement and extent of astronomy content across different school levels. Astronomy contents in the science curricula have changed in response to social needs (e.g., practical knowledge required for agriculture and fishery) and advancement in astronomical research (e.g., the discovery of exoplanets and the suggestion of new cosmological parameters). Contents addressing the motions of celestial objects and stellar physical properties have remained relatively consistent. In the latest 2022 revised national curriculum, scheduled for implementation in 2024, several elements, such as coordinate systems, have been removed, while the inquiry activities using digital tools are emphasized. The incorporation of the cosmic perspectives in the national curriculum, as well as astronomy education within the context of education for sustainable development, remains limited even in the most recent curriculum. For future life revisions, the active participation of researchers is needed to reflect the latest astronomical research progress and scientific characteristics in the field of astronomy.

This study tested the effect on the toxicity of formaldehyde to select a shelter site due to formaldehyde leakage. As a result of the experiment, the range of ERPG-2 and 3 is between 2.2km and 9.6km, ASET is 6 minutes at 1km, 15 minutes at 3km, 22 minutes at 5km, and the lethality rate is 99.9% at 1km and 9% at 3km. In areas where refuge time is less than 15 minutes or the lethality rate is more than 2%, a shelter is installed. This is because if there are only a few evacuees, the evacuation time may take longer than the pre-movement time of 15 minutes or less specified in PD 7974-6:2004, and the lethality rate with the lowest number of deaths was calculated to be 2%. The shelter must be equipped with a hepa-filter, positive pressure equipment, air purifier, air respirator, goggles, chemical protective clothing type 4 and sufficient parking space must be secured to ensure the safety of evacuees.

Purpose: This study aims to not only understand the meaning and essence of patients’experiences visiting the Raphael Nanum Homeless Clinic but also explore what kind of healthcare programs they would like to have in the future by appraising patients’experiences in depth. Methods: This study employed a qualitative content analysis method. The data were collected from June 11, 2023, to June 25, 2023. A total of 17 patients who could provide detailed experiences of their visit to the Raphael Nanum homeless clinic participated in this study. We conducted a focus group interview with 6 patients and in-depth one-on-one interviews with the remaining 11 patients. Results: The qualitative content analysis result revealed five themes: “visiting a free clinic for various paths,” “positive experiences at the free clinic,” “negative experiences at the free clinic,” “dissatisfaction with the clinic site,” and “anticipation for the future of the free clinic.” Conclusion: To ensure the right to health and survival of marginalized populations in the future, it is necessary to establish comprehensive healthcare support measures, which include enhancing the facilities of the free clinic and expanding the range of available medical specialties.

In this study, the abnormal noise phenomenon generated intermittently in the shock absorber of the combat armored vehicle was approached from the side of the squeak joint to solve the phenomenon. In order to identify the cause of the noise, the factors causing friction in the shock absorber were checked from the viewpoint of problem product analysis, process, and design. As an improvement plan, by improving the non-lubricated section in the nitrogen chamber, the operating noise was reduced to a level lower than that of a general automobile engine along with the elimination of noise. Considering that this is a combat vehicle, it is judged that it has been improved so as not to affect the survivability and health of the crew during equipment operation. Through the improvement of this study, it is expected to prevent power loss and improve the emotional quality of our soldier.