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        검색결과 4,540

        150.
        2023.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        In this study, a new type of composite material combined with carbonyl iron, a relatively strong ferromagnetic material, was prepared to overcome the current application limitations of Prussian blue, which is effective in removing radioactive cesium. The surface of the prepared composite was analyzed using SEM and XRD, and it was confirmed that nano-sized Prussian Blue was synthesized on the particle surface. In order to evaluate the cesium removal ability, 0.2 g of the composite prepared for raw cesium aquatic solution at a concentration of 5 μg was added and reacted, resulting in a cesium removal rate of 99.5 %. The complex follows Langmuir’s adsorption model and has a maximum adsorption amount (qe) of 79.3 mg/g. The Central Composite Design (CCD) of the Response Surface Method (RSM) was used to derive the optimal application conditions of the prepared composite. The optimal application conditions achieved using Response optimization appeared at a stirring speed of pH 7, 17.6 RPM. The composite manufactured through this research is a material that overcomes the Prussian Blue limit in powder form and is considered to be excellent economically and environmentally when applied to a cesium removal site.
        4,000원
        151.
        2023.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The Ti-6Al-4V lattice structure is widely used in the aerospace industry owing to its high specific strength, specific stiffness, and energy absorption. The quality, performance, and surface roughness of the additively manufactured parts are significantly dependent on various process parameters. Therefore, it is important to study process parameter optimization for relative density and surface roughness control. Here, the part density and surface roughness are examined according to the hatching space, laser power, and scan rotation during laser-powder bed fusion (LPBF), and the optimal process parameters for LPBF are investigated. It has high density and low surface roughness in the specific process parameter ranges of hatching space (0.06–0.12 mm), laser power (225–325 W), and scan rotation (15°). In addition, to investigate the compressive behavior of the lattice structure, a finite element analysis is performed based on the homogenization method. Finite element analysis using the homogenization method indicates that the number of elements decreases from 437,710 to 27 and the analysis time decreases from 3,360 to 9 s. In addition, to verify the reliability of this method, stress–strain data from the compression test and analysis are compared.
        4,000원
        152.
        2023.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Although the Ti–6Al–4V alloy has been used in the aircraft industry owing to its excellent mechanical properties and low density, the low formability of the alloy hinders broadening its applications. Recently, laser-powder bed fusion (L-PBF) has become a novel process for overcoming the limitations of the alloy (i.e., low formability), owing to the high degree of design freedom for the geometry of products having outstanding performance used in hightech applications. In this study, to investigate the effect of bulk shape on the microstructure and mechanical properties of L-PBFed Ti-6Al-4V alloys, two types of samples are fabricated using L-PBF: thick and thin samples. The thick sample exhibits lower strength and higher ductility than the thin sample owing to the larger grain size and lower residual dislocation density of the thick sample because of the heat input during the L-PBF process.
        4,000원
        153.
        2023.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Because magnets fabricated using Nd-Fe-B exhibit excellent magnetic properties, this novel material is used in various high-tech industries. However, because of the brittleness and low formability of Nd-Fe-B magnets, the design freedom of shapes for improving the performance is limited based on conventional tooling and postprocessing. Laserpowder bed fusion (L-PBF), the most famous additive manufacturing (AM) technique, has recently emerged as a novel process for producing geometrically complex shapes of Nd-Fe-B parts owing to its high precision and good spatial resolution. However, because of the repeated thermal shock applied to the materials during L-PBF, it is difficult to fabricate a dense Nd-Fe-B magnet. In this study, a high-density (>96%) Nd-Fe-B magnet is successfully fabricated by minimizing the thermal residual stress caused by substrate heating during L-PBF.
        4,000원
        154.
        2023.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To analyze the status and needs of the small- and medium-sized garment manufacturing industry in Busan, this study comprised an online survey of companies and interviews with 14 representatives of the 98 companies. The results are as follows: Approximately 34.7% of the garment manufacturers were located in Geumjeong-gu, Busan. The most common type of work was the contracting factory type. Daily production output was between 100pcs and 300pcs. Production materials comprised 42.9% woven and 24.8% knitted fabrics. Main products were menswear, uniforms, womenswear, casual wear, sports and leisure wear, protective clothes, and children’s clothing. The main clients were uniform companies, main factories, wholesale markets, online shopping malls and promotion companies, exporters, and department stores. As a result of a survey on industrial needs with company representatives, their satisfaction with company employees was 57.2%, and the most important factor when hiring employees was job-related competencies, among which the ability to understand the sewing process was the most necessary. In terms of computer software literacy, illustrations and pattern CAD/CAM are required. They thought industry-university cooperation is crucial for advantage for advantage research and product development, as it allows for the sharing knowledge, resources, and especially human resources. The greatest administrative issue were human resources and funding.
        4,800원
        158.
        2023.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Oysters are the most widely produced shellfish culture in Korea and 90% of their weight. Main component of oyster shell is CaCO3 and an appropriate calcination temperature was derived using thermo-gravimetric analysis. The difference in components for each calcination temperature was confirmed and the adsorbent was manufactured by activation. The oyster shell adsorbent surface area was 5.72m2/g with pores in the mesopore range. The adsorption amount was 37.44 mg/g. Therefore, the possibility of using oyster shell as an adsorbent was confirmed.
        4,000원
        159.
        2023.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        한국의 전통 과자인 유과는 거의 모든 공정이 수작업으로 제조되기 때문에 공정 중 작업자 및 작업도구 등에 의한 교차오염으로 인한 안전문제가 제기되고 있다. 본 연구에서는 유과 제조 공정 중 찹쌀의 불림 단계에서 증가된 미생물을 제어하기 위하여 항균 활성이 있는 용액 9가지 용액(40% 자몽종자 추출물, 100% 계피 추출물, 70% 에탄올, 100% 식초, 0.2% 차아염소산나트륨, 40% 초산나트륨, 40% 탄산수소나트륨, 40% 사과산, 40% 구연산)을 이용하여 Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, Salmonella typhimurium, Bacillus cereus에 대해 항균 효과를 비교 확인하였다. Disk diffusion법을 통해 40% 사과산과 구연산에서 높은 항균 효과를 확인할 수 있었고, 추가로 항균용액의 농도, 처리방법 및 시간을 최적화한 결과 1% 사과산-구연산을 10분 동안 처리 시 세균 5종을 모두 사멸시켜 높은 항균효과를 확인할 수 있었다. 불림단계의 찹쌀에 1% 사과산-구연산으로 정치 및 교반하면서 10분 동안 세척하였을 때 일반세균과 대장균군의 수가 각각 4.0 Log CFU/g와 5.0 Log CFU/g씩 감소하였다. 이상의 결과로 볼 때 1% 사과산-구연산으로 불린 찹쌀에 대해 침지와 교반으로 10분 동안 처리함으로써 전통 유과 제조과정 중 쌀의 불림단계에서 증가된 미생물을 효과적으로 저감화 할 수 있음을 확인하였다.
        4,000원
        160.
        2023.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        최근 글로벌 정치․경제 환경의 대전환으로 미국과 유럽 국가들은‘재산업화 전략’으로 제조업 회복을 추진하고 있고, 중국도 ‘중국제조 2025’를 통해 제조업의 질적 발전과 고도화에 집중하고 있다. 이러한 상황에서 본 연구는 외국인직접투자(Inward Foreign Direct Investment, IFDI)가 중국 제조업 고도화에 미치는 영향에 대해 실 증적 분석을 통해 검증해 보고자 하였다. 제조업 가운데 첨단기술 산업의 비중을 중국 제조업 고도화의 지표로 이용하여 2004년부터 2020년까지의 17개년도 중국 31개 성(省)별 패널데이터로 고정효과 모형과 FGLS 모형 을 활용하여 실증분석을 하였다. 분석 결과, 중국 전체와 중국의 동부, 중부, 동북 지역, 장강경제벨트는 IFDI가 중국 제조업 고도화에 긍정적인 영향을 미치는 것으로 나타났지만, 서부지역에 대해서는 영향을 미치지 않는 것 으로 나타났다. 이러한 결과를 통해 IFDI가 중국 제조업 고도화에 미치는 영향은 지역별로 다소 차이가 존재 하고 있음을 입증하였다. 분석 결과는 중국 정부의 IFDI를 통한 지역 균형 발전정책이 중부와 동북 지역에 대 해서는 효과적이었음을 알 수 있었던 반면 중국 서부지역에 대해서는 IFDI를 통한 첨단기술 산업 고도화의 정 책 목표와 전략을 수정할 필요가 있음을 시사한다. 한편 통제변수로 활용된 변수인 수출과 수입으로 측정된 개 방정도와 첨단기술에 대한 연구개발 투자는 제조업 고도화에 매우 긍정적인 영향을 미치는 것으로 일관되게 나 타나고 있다.
        5,500원