검색결과

검색조건
좁혀보기
검색필터
결과 내 재검색

간행물

    분야

      발행연도

      -

        검색결과 148

        1.
        2025.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, we investigated the effect of excess sodium (Na) in a NaMnO2 structure using one-step heat treatment at 900 °C followed by quenching in liquid nitrogen (N₂). According to the X-ray diffraction (XRD) analysis, there was a competition between the monoclinic and orthorhombic phases, and we found that there were two monoclinic phases with similar structural properties. Therefore, we focused on revealing the formation of two isostructures of the monoclinic phase triggered by Na ions. We found that the lattice parameters and β angle changed from 113° to 105° in the samples with increasing Na content. Structural analysis of the powders using the XRD data was conducted using Rietveld refinement, and the phase ratios for all samples were calculated. The sample with x = 1.3 showed a 95% α-phase. To understand the formation of the two isostructures, we performed Density functional theory (DFT) calculations to examine their band structure, stability, and formation energy. A structural analysis of the excess Na-doped samples was performed using common techniques, and it was found that excess Na caused the formation of a coating on the grains in the form of sodium oxide. To validate this prediction, we conducted inductively coupled plasma mass spectrometry (ICP-MS), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy coupled with energy dispersive X-ray (SEM–EDX) analyses using the basic properties of these techniques and their interactions with materials. In the second part of the study, we produced HC from locally sourced olive leaves and investigated their structural properties. The electrochemical properties of the electrode materials were examined using a half-cell configuration as electrodes with Na metal and a full-cell configuration using x = 1.3 cathode and HC anode. A direct-contact pre-sodiation strategy was used as the anode in the full-cell measurements. It was found that the full cells had initial capacity values of 150 mAh/g for the voltage range 1.5–4.3 V and 120 mAh/g for the voltage range 1.5–3.5 V.
        5,200원
        2.
        2025.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        이 연구에서는 저수온(0–4℃), 고수온(30–36℃), 저염분(5–15) 조건에서 돌비늘백합 (Mercenaria mercenaria)의 생존력과 생리 반응을 종합 평가하였다. 저수온에서 누적 폐사는 15% 미만(LT50: 53.1–85.1일)으로 우수했고, 고수온은 33캜 이상에서 급격한 폐사(LT50: 36℃ 기준 0.8일)를 보였다. 저염분에서는 염분 15 까지는 생존이 가능하나, 염분 10 이하에서는 폐사가 급증하였다(LT50: 14.1–15.7일). 극한 환경에서 면역 기능이 저하되고, 탄수화물 함량 감소 등 에너지 고갈 징후도 나타났다. 이 결과는 돌비늘백합이 국내 해역의 계절 변화에 충분히 적응할 수 있음을 시사하지만, 33℃ 이상과 염분 10 이하의 환경에서는 생존 관리가 필요함을 시사한다.
        4,000원
        5.
        2025.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Hard carbon's excellent performance and affordability made it an ideal anode material for sodium-ion batteries. However, hard carbons derived directly from lignin often exhibit poor performance. Optimizing the synthesis process presents a valuable strategy for enhancing performance. In this study, we optimize the synthesis process to minimize costs while integrating green chemistry principles to mitigate environmental impact. Sodium lignosulfonate-formaldehyde resin-derived hard carbon is produced using a simple, low-cost pyrolysis technique involving multiple temperature stages. This process enhances the material's structural stability and electrochemical performance. X-ray diffraction (XRD) and Raman spectroscopy analysis show that higher pyrolysis temperatures lead to a distinct peak, which improves electronic conductivity. In contrast, lower temperatures result in chaotic structural formations. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) image analyses reveal that the resulting material has a porous structure with unique chemical properties. Tested for 200 cycles at a current density of 50 mA g− 1, the materials exhibited specific capacities of 332.24 mAh g− 1, 180.3 mAh g− 1, and 105.6 mAh g− 1, respectively, for LSHC-1400, LSHC-1200, and LSHC-1000. The promising results can be attributed to the unique porous structure and inherent chemical properties of the lignosulfonate precursor, which enhance the transport and storage of sodium ions. This study highlights the critical role of the synthesis method in determining the sodium storage capacity of the carbon anode in sodium-ion batteries, encouraging further exploration and optimization in this area.
        4,000원
        6.
        2025.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        WC–Mo₂C–Co cemented carbides were fabricated to investigate the effects of Mo₂C addition on microstructure and mechanical properties. Dual hard-phase design using WC and Mo₂C was employed to optimize the balance between hardness and toughness. Spark plasma sintering (SPS) was conducted at various temperatures after ball milling, and 1300 °C for 5 min was identified as the optimized sintering condition, achieving complete densification and phase stability. The addition of Mo₂C refined the microstructure by suppressing abnormal WC grain growth through preferential dissolution of Mo₂C into the Co binder. Hardness increased up to 1769 Hv30 due to grain refinement and solid-solution strengthening, while promoted η-phase formation and reduced fracture toughness.The 27Mo₂C composition exhibited the most balanced combination of hardness and toughness. These results demonstrate that controlled Mo₂C addition enables dual hard-phase strengthening and microstructure optimization in WC–Mo₂C–Co carbides for advanced cutting and forming applications.
        4,000원
        8.
        2025.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Sialadenoma papilliferum is a rare benign salivary gland tumor, accounting for approximately 0.4–1.2% of all salivary gland neoplasms. It most commonly occurs in the hard palate, followed by the soft palate, buccal mucosa, upper lip, and, rarely, the esophagus. The condition is typically asymptomatic and is often discovered incidentally during routine oral examinations. We report the case of a 56-year-old man who presented with pain in the left hard palate and was referred to Kyungpook National University Dental Hospital. Enhanced CT revealed a 1.5-cm ovoid lesion in the left paramedian hard palate. Biopsy confirmed the diagnosis of sialadenoma papilliferum, and based on the radiological findings, surgical excision was performed under general anesthesia. The microscopic histopathological examination of the specimen (size: 1.0 x 0.7 cm) revealed papillary proliferation of stratified squamous epithelium with hyperkeratosis and underlying ductal structures lined by mucin-producing cells with mucinous material in the cystic spaces.
        4,000원
        10.
        2025.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Developing advanced anode materials is one of the effective strategies to enhance the electrochemical performance of sodiumion batteries (SIBs). Herein, inspired by the biological central nervous system structure, we report a facile and efficient strategy to fabricate the three-dimensional hierarchical neural network-like carbon architectures, where the glucose-derived hard carbon (HC) nanospheres are in situ assembled and embedded in carbon nanotube (CNT) network nanostructure (HC/CNT hybrid networks). The HC nanospheres with large carbon interlayer spacing help to decrease the diffusion length of sodium ions and the interconnected CNT networks enable the rapid electron transfer during charge/discharge process. Benefiting from these structure merits, the as-made HC/CNT hybrid networks can deliver a superior rate capacity of 162 mA h g− 1 at the current density of 5 A g− 1. Additionally, it exhibits excellent cycling performance with a capacity retention rate of 86.3% after 140 cycles. This work offers a promising candidate anode material for SIBs and a new prospect towards carbon-based composites design, simultaneously.
        4,000원
        12.
        2025.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study explores the development and characterization of hard carbon anodes for sodium-ion batteries produced from waste coffee grounds, synthesized at both 1000 °C and 1500 °C. Importantly, this work highlights the potential of using biomass-derived hard carbons as sustainable and effective material for anode for sodium-ion batteries, contributing to the advancement of energy storage systems with increasing global demands for environmentally friendly and cost-effective technologies. The research focuses on the electrochemical performance of these hard carbons, examining how different carbonization temperatures impact their structural and electrochemical properties. Utilizing advanced analytical methods, the structural changes correlating with temperature increase were identified, including modifications in carbon atom arrangements, which significantly influence the electrochemical behaviors of the hard carbons. Our research specifically focuses on how the structural differences affect the division of capacity contribution from sloping region (above 0.1 V) and plateau regions (below 0.1 V). Electrochemical test results revealed that hard carbon with higher degree of order and reduced microstructural defects, demonstrated improved capacity values. At the same time, the highly ordered hard carbon exhibits drastic capacity loss upon increasing of current densities. The results from this study not only advance our understanding of hard carbons but also open pathways for the future exploration of hard carbons for additional improvements.
        4,500원
        13.
        2024.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 세계적으로 기호용 대마초 사용이 비범죄화되는 나라가 늘어나고, 한국 에서도 대마초 사용의 합법화를 요구하는 현 상황에서 대마초 사용자들이 어떤 과정 을 통해 강성 마약으로 진입하는지를 분석한 사례 연구이다. 대마초 사용에서 강성 마 약으로 이전한 경험이 있는 마약류 중독자들의 대마초 사용 과정과 내용 그리고 강성 마약으로 이전하게 된 과정과 맥락 등을 규명하고, 이에 근거하여 대마초 사용자들이 강성 마약으로 진입하는 것을 차단하고자 하는 목적에서 수행되었다. 연구에 참여자 는 대마초 사용에서 강성마약류로 입문한 경험이 있는 13명으로 이들은 마약류 중독 에서 회복되어 단약을 유지하고 있는 회복자들이다. 자료수집은 연구 참여자를 1대1 심층 면담을 통해 이루어졌으며, 수집된 자료는 22개의 개별주제 압축하여 이를 9개 의 주제 범주로 구성하였다. 자료 분석의 분석 단위는 강성 마약 사용 계기와 강성 마약 사용의 강화 유지로 나 누어, 개인적 조건과 환경적 조건으로 제시하였다. 연구 결과, 강성 마약 사용 계기의 개인적 조건으로는 쾌락의 상승 욕구, 마약 사용 집단에서의 지위 향상, 마약 경각심 실종으로 나타났으며, 환경적 조건으로는 마약 시장의 덫에 빠짐, 치료 시스템의 부 재, 낙인에 대한 반동적 저항과 도피로 나타났다. 강성 마약 사용의 강화 유지의 개인 적 조건으로는 쾌락의 노예화, 체념의 학습과 내재화로 나타났으며, 환경적 조건에는 마약 사용과 밀매자의 이중 지위로 나타났다. 연구 결과에 근거하여 대마초 사용 사범 이 강성 마약으로 진입하지 않고 회복할 수 있도록 법무부 교정 차원에서 교정 처우와 중독 치료에 대해 구체적인 제언 하였다.
        8,400원
        14.
        2024.04 구독 인증기관·개인회원 무료
        지속적인 기후변화로 인해 매개 곤충을 통한 다양한 신종감염병이 국제적으로 확산되고 있으며, 발생빈도 또한 증가하는 추세이다. 이러한 매개질병을 관리하기 위해서는 질병을 매개하는 매개체에 대한 정보와 지속적 인 모니터링이 필요하다. 이 연구는 제3급 법정 감염병으로 지정된 중증열성혈소판감소증후근(Severe Fever with Thrombocytopenia Syndrome, SFTS) 및 라임병(Lyme disease) 등의 매개체로 알려져 있는 참진드기를 대상으로 충남 당진 일대에서 2018년부터 2023년까지 총 6년, 4월-11월의 기간동안 월 1회 4개의 환경(무덤, 산길, 잡목림, 초지)에서 드라이아이스 유인트랩을 사용하여 발생밀도를 조사하였다. 그 결과 2018년 16,996마리, 2019년 16,698마리, 2020년 6,417마리, 2021년 7,380마리, 2022년 3,451마리, 2023년 3,465마리로, 총 54,407마리가 채집되 었으며, 초지에서 가장 많이 채집되었다. 채집된 참진드기는 2속 3종으로 작은소피참진드기(Haemaphysalis longicornis), 개피참진드기(H. flava), 일본참진드기(Ixodes nipponensis)이며, 작은소피참진드기 (H. longicornis) 가 42,489마리(78.09%)로 높은 우점도를 보였으며, SFTS 보유 여부를 확인하기 위해 RNA 추출 및 Nested RT-PCR 단계를 걸쳐 전기영동을 수행하였으나 양성 검체는 0건으로 확인되었다. 이러한 연구 결과는 SFTS의 주요 매개 체인 참진드기 발생 양상 파악 및 매개 질병 관리 전략 수립에 기초 자료로서 활용될 수 있을 것으로 사료된다.
        15.
        2024.04 구독 인증기관·개인회원 무료
        A tick survey was conducted to monitor ticks using tick traps attached dry ice method at each four sites in Ulju and Gimhae counties, Gyeongsangnam-do from April to November, 2023. Two species belonging to one genera were collected with tick traps. A total of 1,064 ticks were collected as Haemaphysalis longicornis (Trap Index; TI 11.0), Haemaphysalis flava (TI <0.1) in Ulju and A total of 843 ticks were collected as Haemaphysalis longicornis (Trap Index; TI 8.7), Haemaphysalis flava (TI 0.1) in Gimhae 2023. Haemaphysalis longicornis was the most frequently collected, representing 99.2% in Ulju, 98.9% in Gimhae. In the collection environments, a total number of 685, 268, 64, and 47 ticks were collected from a glassland, a copse, a mountain path, and a grave of Ulju a total number of 469, 216, 83, and 75 ticks were collected from a glassland, a copse, a Grave, and a mountain path of Gimhae respectively. In the results of the isolation of Severe Fever with Thrombocytopenia Syndrome (SFTS) from the ticks, no pathogens were detected from RNA of 101 pools (Ulju), 98 pools (Gimhae) of the ticks using a Polymerase Chain Reaction method in 2023.
        16.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        On the international political stage of the 21st century, the strategic rivalry between China and the United States is one of the most captivating focal points. As two major global powers, China and the United States, their competition and cooperation across multiple domains have profound implications for the global political and economic landscape. The historical evolution of Sino-U.S. relations provides us with key insights into the understanding of the current strategic rivalry. Within the realm of hard power, the economic and technological rivalry between China and the United States is intensifying, engendering notable frictions within areas such as economics and technology. These frictions reverberate through their interactions, influencing their positions and interests on the global stage. However, the role of soft power in the context of Sino-American relations cannot be understated. The United States has persistently exported its values of democracy and freedom, whereas China emphasizes the principles of peaceful development and shared prosperity. The strategic rivalry between China and the United States is an intricate, multifaceted issue that poses significant challenges. To effectively address this complexity, China must employ a comprehensive array of strategies and measures to ensure its enduring stability and sustained development in the ever-evolving global landscape.
        5,100원
        17.
        2023.10 구독 인증기관·개인회원 무료
        SFTS(Severe Fever with Thrombocytopenia Syndrome)는 참진드기에 의해 전파되며 한국에서는 제3급 법정 감 염병으로 지정되어 있다. SFTS 감염 시 치사율이 높은 편이며, 현재까지도 백신과 치료제가 없다. 이러한 참진드 기의 발생 및 분포 조사와 SFTS 감염 여부를 확인하기 위해 2023년 4월부터 8월까지 김천시와 군위군 4곳의 환경 (무덤, 산길, 잡목림, 초지)에서 Dry ice trap으로 채집을 진행하였다. 김천시에서는 총 1,444마리의 참진드기가 채집되었으며, 잡목림에서 571마리(39.5%)로 가장 많이 채집되었다. 군위군에서는 총 3,914마리가 채집되었으 며, 무덤에서 2,701마리(69.0%)로 가장 많이 채집되었다. 참진드기의 종별 분포를 조사한 결과, 외형 동정이 어려 운 유충을 제외하고 김천시에서는 Haemaphysalis longicornis가 1,160마리(99.3%)로 가장 많이 채집되었고, 군위 군에서는 Haemaphysalis longicornis가 1,414마리(98.6%)로 역시 가장 많이 채집되었다. 채집된 참진드기의 SFTS 보유 여부를 확인하기 위하여 Nested PCR을 이용해 조사한 결과, SFTS를 보유한 참진드기는 발견되지 않았다. 본 조사에서는 SFTS에 감염된 참진드기 개체가 발견되지 않았지만, SFTS에 감염된 환자가 2016년부터 매년 160명 이상 발생하고 있으므로 체계적인 감시와 조사가 필요할 것으로 생각된다.
        1 2 3 4 5