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        검색결과 114

        2.
        2025.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Jae Young Jung, Dong‑gun Kim, Sungkwon Jung, Sujin Kim, Jae‑yeong Kang, Yong‑seong Park, Hongbum Kim, Nam Dong Kim, Pil Kim
        With the increasing demand for flexible electronic devices, smaller and lighter flexible supercapacitors have gained significant research attention. Among the various materials, self-supporting reduced graphene oxide (rGO) paper has emerged as one of the most promising electrode materials for supercapacitors due to its low cost, high chemical/thermal stability, and excellent electrical conductivity. Nevertheless, a major drawback of rGO paper is the limited ion diffusion between stacked rGO layers, hindering the effective formation of electrochemical double-layer at the electrode/electrolyte interface. In this study, we prepared the rGO paper derived from ball-milled followed-by water oxidation process for reducing the sheet size. The smaller-sized rGO sheets facilitated ion transport between graphene layers, promoting efficient electric double-layer formation. Moreover, the increased presence of edge planes in ball-milled rGO sheets achieved high capacitance, further enhancing the performance of rGO as an electrode material. Notably, the 2-BMOX rGO paper obtained from ball-milling and wet-oxidized graphite exhibited a capacitance of 117.9 F/g in cyclic voltammetry (CV) and 128.6 F/g in galvanostatic charge–discharge (GCD) tests, approximately twice that of conventional rGO. Additionally, the capacitance retained 91% of its initial performance after 2,000 cycles, indicating excellent cycling stability.
        4,300원
        4.
        2025.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Dong Myung Kim, Ju Yeong Lee, Gyu-Seok Choi, Chunjoong Kim
        High nickel content Li(NixCoyMn1-x-y)O2 (NCM, x ≥ 0.9) cathode materials suffer from rapid capacity fading, a significant obstacle to their commercial application. To mitigate this issue, strategies such as doping and coating with various elements have been widely reported. In particular, multi-element doping has been explored as a potentially more effective alternative to single or dual element modification. Concurrently, the synthesis of high-entropy precursors via coprecipitation has gained significant attention. In this study, high nickel content precursors with nine components were synthesized by hydroxide coprecipitation under varying concentrations of ammonia that was employed as a chelating agent. The primary particle morphology of the precursors was found to be dependent on the ammonia concentration, which in turn influenced the physicochemical and electrochemical properties of the final cathode materials. At low ammonia concentration, the formation of secondary phases was detected. Notably, the cathode synthesized under high ammonia concentration exhibited excellent cycling stability, delivering a discharge capacity of 164.22 mAh/g after 100 cycles at 1 C, which corresponds to a capacity retention of approximately 91 % of its initial discharge capacity (180.50 mAh/g at 0.1 C).
        4,000원
        6.
        2025.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Dong Hwan Kim, Eugene Oh, Jaegeun Lee, Sehyun Kim
        The mass production of highly crystalline carbon nanotubes (CNTs) is highly demanded, yet achieving it remains challenging due to incomplete understanding of how synthetic parameters, except temperature, affect the crystallinity of CNTs. Notably, the choice of carbon precursor significantly influences CNT synthesis, but its impact on crystallinity remains unclear. Here, we employed a data analytics approach to examine the effect of carbon precursors on CNT crystallinity during their synthesis in a fluidized bed reactor. We compared ethylene, acetylene, and a mixture of these. Using Bayesian optimization (BO), we optimized synthesis conditions to maximize IG/ID of CNTs for each precursor. Key parameters considered were reaction temperature, precursor concentration, and hydrogen concentration. We conducted three separate BO processes to evaluate the effectiveness of each carbon precursor on CNT crystallinity. The results indicated no significant difference in IG/ID of CNTs among the carbon precursors. In addition, multiple linear regression analysis did not support a synergetic effect between acetylene and ethylene. Interestingly, contour plots demonstrated consistent relationships between synthesis parameters and IG/ID across different carbon precursors. This data analytics approach allowed us to successfully assess the impact of carbon precursors on the CNT crystallinity and analyze the relationship between synthesis parameters and CNT crystallinity.
        4,200원
        7.
        2023.08 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Dong Hun Han, Young Min Kim, Dan Bi Lee, Kyu Hwan Lee, Han-Seong Kim
        There are many types of foam molding methods. The most commonly used methods are the pressure foaming method, in which foam resin is mixed with a foaming agent at high temperature and high pressure, and the normal pressure foaming method, which foams at high temperature without pressure. The polymer resins used for foaming have different viscosities. For foaming under normal pressure, they need to be designed and analyzed for optimal foaming conditions, to obtain resins with low melt-viscosity or a narrow optimal viscosity range. This study investigated how changes in viscosity, molding temperature, and cross-link foaming conditions affected the characteristics of the molded foam, prepared by blending rubber polymer with biodegradable resin. The morphologies of cross sections and the cell structures of the normal pressure foam were investigated by SEM analysis. Properties were also studied according to cross-link/foaming conditions and torque. Also, the correlation between foaming characteristics was studied by analyzing tensile strength and elongation, which are mechanical properties of foaming composites.
        4,000원
        9.
        2022.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Dong Hyun Han, Dong Bin Lee, Jae Hyeon Cho, Chung Hui Kim
        The slaughter of livestock is inevitably required to obtain meat products from livestock. Since slaughter means pain and death for animals, reducing the pain and distress of animals during slaughter is very important from a perspective of animal welfare based on the principle of respect for life. Generally, two stunning methods, CO2 stunning and electrical stunning, are used for slaughter. When the carotid arteries of the lungs are cut off for bleeding, the bronchial tubes are also severed. To determine the degree of blood inflow into the lungs through the severed bronchial tubes, the prevalence rates of pulmonary diseases and pulmonary congestion in slaughtered pigs were analyzed. In this study, the prevalence of pneumonia was 24.9% in Slaughterhouse A using the gas method, but it was decreased by about 10% to 15.7% and 12.6%, respectively, in Slaughterhouses B and C using the electric method. On the other hand, the prevalence of pulmonary congestion in Slaughterhouses A, B, and C was 4.24%, 14.10% and 16.40%, respectively. In other words, the prevalence of pulmonary congestion was higher by about 10% in the groups of pigs slaughtered by the electric method (Slaughterhouses B and C) than in the group of pigs slaughtered by the gas method (Slaughterhouse A). These results indicate that blood inflow into the pulmonary alveoli led to a diagnosis of pulmonary congestion instead of pneumonia in some pigs with pneumonia. In short, it was found that about 10% of pigs stunned by the electric method were not in a state of complete unconsciousness but in a partially conscious state during slaughter. It is suggested that slaughterhouses should be equipped with gas stunning equipment instead of applying the electric method due to lower costs.
        4,000원
        10.
        2021.12 구독 인증기관 무료, 개인회원 유료
        Dong Sun Park, Dasom Kim
        The 17th APEC Future Education Forum (AFEF) and the 19th International ALCoB Conference were held from 28 September (Tuesday) to 1 October (Friday) in a virtual manner. The annual forum and conference serve as an invaluable opportunity to discuss future directions of education and human resources development in the Asia-Pacific region. Since 2005, the forum and conference have served their role as the largest and longest thematic meeting in the APEC Human Resources Development Working Group (HRDWG). The 2021 forum and conference have gathered 780 participants from 20 APEC member economies, guest economies and international institutions. Under the theme “Strengthening lifelong competencies and skills development for individuals’ career, education, training, and life cycles”, the forum and conference reflected the current educational agenda from 21 APEC member economies and other international organizations such as G20, UNESCO. As a way forward, the forum and conference speakers recommend APEC to 1) consider individual and industrial needs for curriculum development, 2) expand lifelong learning policies and practices at both domestic and international level and 3) develop a public-private partnership to prepare its future talents with adequate competencies. This review explains the 17th AFEF and the 19th International ALCoB Conference background, summary and outcomes. The review also briefs on collective actions member economies can take as future steps to continue the forum and conference discussions.
        4,000원
        12.
        2020.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Dong Cheol Jang, Chan Xu, Si Hong Kim, Dae Hoon Kim, Jae Kyung Kim, Jae Yun Heo, Ngoc Thang Vu, Ki Young Choi, Il Seop Kim
        본 연구는 원통형 종이포트 토마토 육묘시 Diniconazole의 처리방법이 도장억제 및 근권발달에 미치는 영향을 검토하기 위하여 수행되었다. 그 결과, 엽면적, LAR, 초장, 충실도, 생체중, RGR 및 R/S 에서 시험구간 유의한 차이를 보였다. 동일한 농도를 처리했을 경우, 근권부와 지상부의 흡수도 차이로 인해 저면관수가 엽면살포에 비해 도장억제에 효과적이었다. 저면관수는 엽면시비의 10분의 1의 농도만으로도, 20~30%정도의 동일한 도장억제 효과를 얻을 수 있었다. 디니코나졸 처리에의한 근권부 반응이 흥미로웠는데, 저면관수시 총근장, 근권부피, 평균 근경 및 근단수가 증가하였다. 특히, 0.3mm 이하의 초미세근이 감소하고 0.3~0.6mm의 세근이 증가하였다. 따라서 원통형 종이포트 육묘시 저면관수를 하는 것이 기존 엽면시비에 비해 사용량이 적으면서도 도장억제 및 근권부 활착률을 높힐 수 있을 것으로 판단된다.
        4,000원
        13.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Dong Gun Kim
        The Nannophya species in Korea was thought to consist of only Nannophya pygmaea. Previous studies on the species, including life history and development, conservation and restoration, habitat characteristics, genetic studies, distribution, behavior, and taxonomy have been conducted. However, a new Nannophya species, Nannophya koreana, was recently discovered in Korea. Moreover, this new species was found to inhabit both Korea and Japan. Thus, the previous studies should be reevaluated in relation to the new species, Nannophya koreana, and the latter should be treated as an endangered species worldwide given the current population instability.
        4,000원
        15.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Dong Gun Kim
        A catch basin sump is one major habitat for mosquito larvae, especially in urban areas. This study developed a device for mosquito control, specifically for the catch basin sump. It consists of a housing, is a little smaller than the catch basin sump, numerous floating materials, which the key component for mosquito control, and mesh nets. The small balls or pyramid-shaped floating materials inhibit mosquito enclosures and spawning by significantly decreasing the surface area of the water, which is essential for the mosquito life cycle. These floating materials were designed to keep the water flowing. The mesh nets were installed to prevent the outflow of floating materials. The efficiency of the floating materials was tested with 3 conditions (1, 2, 3 layers of floating materials) and a control group. The emergence of mosquito adults decreased by 20% in one-layer, and 70-80% in second and third layers. Therefore, this device is expected to certainly contribute to mosquito population control in the catch basin sump.
        3,000원
        16.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Dong Joon Park, Min Yoon, Byung Hwan Kang, Ho Gyun Kim
        The International Organization for Standardization (ISO) published ISO 9001 Quality Management System (QMS)-Requirements in 1987 and has revised four times since then. ISO 9001:2015 is the latest edition. This latest edition has two most noticeable changes. The first major change of new edition focuses on performance with an emphasis on Risk-Based Thinking (RBT) to enhance the process approach. The new edition consists of ten clauses whose first three clauses are largely same as older edition but risks are clearly stated and stressed in last seven clauses, emphasizing on Plan-Do-Check-Act cycle at all levels in the organization. The second major change is that the new edition has the same overall structure as other ISO management system standards known as High Level Structure (HLS) with Annex SL. The companies obtained the certificate of new ISO 9001:2015 QMS by September 15, 2018 in order to maintain as an ISO QMS registered firm. In this article we collected transition audit data from more than 100 companies that registered ISO 9001:2015 QMS for recent three years. We performed a statistical analysis to disclose the relationships between the characteristics of companies and the minor nonconformities found in ISO 9001:2015 requirements during transition audit processes. We also aim to interpret the findings and deduce the implications of the statistical results.
        4,200원
        17.
        2018.11 구독 인증기관·개인회원 무료
        Dong Eon Kim, Kyeong Yeob Kim, Eun Do Lee, Beom Sik Kim
        Until recently, there have been many researches about the freezing methods and several methods of cryopreservation. Hypothermic preservation has been used to complement the embryo freezing technology. There is a study to show the successful results for long-term hypothermic preservation. For that reason, FBS and BSA are commonly added to the culture medium to support embryo development. We investigated the effectiveness of hypothermic preservation method at 4℃ according to embryonic developmental stages for Hanwoo embryos and evaluated the effect of FBS and BSA on Hanwoo embryos as a supplemental reagent in hypothermic preservation medium after recovering preserved embryos from hypothermic preservation. The present study reported that survival and hatching rates of embryos at morula stage following storage at 4℃ is Day 7 group was significantly higher (p < 0.05) compared than those of other groups (p < 0.05). As a result, the survival and hatching rates of embryos at the blastocyst stage following storage at 4℃ result is showed that significantly higher (p < 0.05) survival rates than those of other groups an Day 6. The result showed that hatching rate at Day 6 and 7 were significantly lower (p < 0.05) compared with other groups. The result regarding the survival and hatching rates of bovine embryos following storage at 4℃ for 72 h in various concentrations of BSA are shown The results showed that survival rate of 1% BSA group was not significantly different (p < 0.05) compare with control (FBS) group. Also, the results showed that hatching rate of control (FBS) and 1% BSA were significantly different (p < 0.05) compared with other groups. In conclusion, our result demonstrated that the hypothermic preservation did not effect on the survival and hatching rates of embryos after recovering. In addition, the supplementation of BSA in preservation medium showed no difference in the embryo developmental competence after hypothermic preservation compared to FBS treatment. With that, BSA can be an alternative reagent for the hypothermic preservation medium as an energy source and pH buffer.
        18.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Dong Soo Choi, Sunghee Kim, Jaehwa Kim
        목적: 스마트 안경은 안경과 웨어러블 전자기기의 효과적인 융합을 잘 보여주는 어플리케이션이다. 스마 트 안경의 더 발전한 형태로, 전압에 의해 능동적으로 변색되는 안경의 제조도 가능할 것으로 기대된다. 따라서, 졸-겔 법에 의한 전기 변색 박막의 제조 과정에서 퍼콜레이션(percolation) 이론을 도입하여, 최적의 aging 조건을 찾아 전기 변색 코팅 박막 제조의 토대가 되고자 한다. 방법: 졸-겔 법을 이용하여 육 염화 텅스텐과 에탄올을 혼합하여 전기 변색 용액을 제조하였다. Aging에 따른 용액의 특성을 분석하고, ITO glass위에 전기 변색 박막을 코팅한 후, 리튬이온 기반 전해질을 이용하여 전기 변색 특성을 확인하였다. 결과: 졸-겔법으로 제조된 전기 변색 용액은 aging에 따라 텅스텐과 산소의 결합이 달라지며, 이것을 적 외선 분광법으로 분석하였다. WO3/ITO glass의 가시광선 전 영역의 광 투과도(시감 투과도)를 측정한 결과, aging에 따라 변색효율의 차이를 보였다. 또한, percolation이 충분히 진행되기 전 샘플의 경우, 광 투과도 가 착색 시 43.0 %, 탈색 시 63.6 %로 1.10의 가장 높은 광밀도를 보였다. 또한, aging이 충분히 진행된 후의 샘플은 착색 시 광 차단 효과가 좋은 결과값을 보였다. 결론: 졸-겔 법에 의해 제조된 변색 용액으로 전기 변색 유리를 제작하였을 때, 용액의 aging에 따라 광 학적 특성이 달라짐을 확인하였다. 긴 시간 aging하는 경우, 변색 효율을 가늠하는 광밀도가 감소하였다. 따라서, 변색효율이 좋은 렌즈가 필요한 경우, percolation 임계 점 이하의 aging 시간이 짧은 용액을 사용 하는 것이 좋으며, 진한 착색이 필요한 광학 샘플이 필요한 경우는 긴 시간 에이징한 용액으로 코팅막을 제 조하는 것이 좋을 것으로 판단된다. 이러한 코팅 박막에 대한 기초 조건의 연구가 향후 스마트 안경 등의 제작 시 참고가 될 것으로 기대된다.
        4,000원
        19.
        2018.04 구독 인증기관·개인회원 무료
        Kim Mi-Jeong, Lee Heejo, Ban Young-Gyu, Kim Dong Eon
        허리노린재과(Coreidae)에 속하는 Leptoglossus gonagra (가칭: 기장허리노린재)는 북미 원산으로 현재 아프리카, 오스트레일리아, 동남아시아 등 폭넓게 분포하고 있으며 다양한 채소와 과일을 가해하는 광식성 곤충으로 알려져 있다. 우리나라는 2016년 부산시 기장면의 호박 재배지에서 약충과 성충이 확인되었으나, 이듬해에는 현장조사에서 서식이 확인되지 않았다. 본 연구는 MaxEnt 모형과 세계적 위치 정보를 이용하여 L .gonagra의 서식 및 생존과 영향을 주는 환경요인 및 국내 서식 가능성을 확인하고자 하였다. 위치자료는 GBIF (Global Biodiversity Information Facility), DISCOVER LIFE 웹사이트에서 제공하고 있는 총 99지점을 이용하였고 환경변수로는 WorldClim의 생물기후 (bio)를 19개를 활용하였다. 예측 모델은 평균 AUC 값 0.928으로 높은 신뢰도를 보였으며, 등온성(bio3)과 가장 따뜻한 분기의 강수량(bio18), 기온의 계절성(bio4), 가장 습한 분기의 강수량(bio16) 순으로 기여도가 높았다. 고온다습 한 열대성 기후 지역에서 출현 가능성이 높게 나타났고, 우리나라에서는 매우 낮은 것으로 분석되었다.
        20.
        2017.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Dong Hun Lee, Jisu Choi, Young Se Oh, Yoong Ahm Kim, Kap Seung Yang, Ho Jin Ryu, Yong Jung Kim
        We demonstrated an effective way of preparing melt spinnable mesophase pitches via catalytic hydrogenation of petroleum residue (fluidized catalytic cracking-decant oil) and their subsequent thermal soaking. The mesophase pitches thus obtained were analyzed in terms of their viscosity, elemental composition, solubility, molecular weight, softening point and optical texture. We found that zeolite-induced catalytic hydrogenation under high hydrogen pressure contributed to a large variation in the properties of the pitches. As the hydrogen pressure increased, the C/H ratio decreased, and the solubility in n-hexane increased. The mesophase pitch with entirely anisotropic domains of flow texture exhibited good meltspinnability. The mesophase carbon fibers obtained from the catalytically hydrogenated petroleum residue showed moderate mechanical properties.
        4,000원
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