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        검색결과 415

        81.
        2019.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Tissue engineering has been rapidly developed in oral and maxillofacial reconstruction. Biocompatible scaffold from chemically composites seeded with stem cells is essential and several growth factors for bone formation and angiogenesis are also required. To overcome limited activity of new bone formation with scaffolds, several biomechanical stimulation methods on cells have been made to grow cells in scaffold. Several bioreactors have been developed for real tissue growth in culture laboratory. In addition to biological stimulants like BMP, growth factors and exogenous drugs, biomechanical stimulation technique has also been known as an effective method in cell differentiation. We developed our own bioreactor with tensile mechanical strains. Then we tested with it for detection of suitable biomechanical effect on the cell differentiation and proliferation. And we also compared the results with the effect of low intensity pulsed ultrasound (LIPUS). Mechanical strain group showed more rapid reaction with cell differentiation and proliferation than non-mechanical strain group. Mechanical strain groups stimulated with 0.5∼0.7Hz for 6 hours and 8 hours showed more active cell differentiation than the group with 0.5∼0.7Hz for 2.5 hours tensile strain stimulation. Group of LIPUS also showed more rapid reaction in cell differentiation and proliferation. LIPUS with 3MHz showed more cell reaction than the LIPUS group with 1MHz. Our results showed the positive effect on differentiation and proliferation of cell with mechanical tensile strain, LIPUS both.
        4,000원
        82.
        2019.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Nerve injury induced protein 1 (Ninjurin1) was originally described in neuroscience in which the expression of Ninjurin1 was regulated by Schwann cells and dorsal root ganglion neuronal cells of damaged nerve tissues. After the first discovery of Ninjurin1, the widespread expression of Ninjurin1 in adult and embryonic tissues have been observed including bone marrow, peripheral blood lymphocytes, thymus, and heart. Currently, the Ninjurin1 mediated positive regulation of pre-osteoclasts fusion and osteoclast development was reported. The bone homeostasis is dynamically balanced by bone-resorbing activity of osteoclast and bone-forming activity of osteoblast. Until now, the role of Ninjurin1 was never been described in osteoblastogenesis. Therefore, in this study, we have evaluated the expression and function of Ninjurin1 in osteoblast. The ample expression of Ninjurin1 was observed in bone marrow of mouse tibia sections but it was barely expressed in osteocytes. And also the expression levels of Ninjurin1 were gradually increased during osteoblast differentiation of calvarial pre-osteoblast, C2C12, and MC3T3-E1 cells. Importantly, the expression of Ninjurin1 was increased in the absence of osteogenic stimulus, BMP2, which suggests the cell density-dependent regulation of Ninjurin1. The controlled expression of Ninjurin1 by cell-density was evidently shown in not only pre-osteogenic osteoblast lineage cells but also in non-osteogenic cancer cells such as HeLa and A549 cells. In addition, the isoform-specific knockdown of Ninjurin1 remarkably reduced the alkaline phosphatase (ALP)-positive osteoblast differentiation. Thus, our results suggest a previously unappreciated mechanism of Ninjurin1 expression and also suggest its role on osteoblastogenesis.
        4,000원
        83.
        2019.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The vascular origin diseases occurring in the oral and maxillofacial region can be divided into hemangiomas and vascular malformation. They are rare and early lesions are not easy to diagnosis, so they may be misdiagnosed as clinicians, or the method and timing of treatment may be inappropriate. For 10 years, from August 2005 to August 2015, we analyzed the clinical records, diagnosis, treatment, and prognosis of 23 patients with hemangioma or vascular malformation confirmed by clinical, histopathological or radiological examination of maxillofacial lesions at department of oral and maxillofacial surgery, Pusan National University Hospital and Pusan National University Dental Hospital. Chief complants of patients were mainly swelling, mass, and spot-like lesion on various intraoral sites. Treatments were performed with excision, embolization, sclerotherapy, depending on each lesions condition. Arteriovenous malformation cases were more frequently recurred than other lesions. Prognosis of lesions were relatively good but close observation should be needed.
        4,000원
        84.
        2019.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        목적:Time-resolved 3-Dimensional Phase Contrast(이하 4D flow)는 혈류를 3차원 공간에서 시간에 따라 변화하는 혈류를 측정할 수 있다. 하지만 심장 박동, 호흡 동조 등의 문제로 인해 검사 시간이 길다는 단점이 있고 이로 인해 Signal to Noise Ratio(이하, SNR)가 낮아 영상 후처리 분석에 많은 어려움이 있다. 이와 같은 문제를 해결하기 위해 여러 논문에서 조영제를 넣는 것을 추천하고 있지만, 이에 따른 영향에 관한 연구는 미비한 실정이다. 따라서 본 연구에서는 조영제 농도에 따른 SNR 증가를 정량적으로 분석하고, 조영제에 의한 국소적 자기장 불균일이 Phase contrast에 어떠한 영향이 있는지 확인하고자 하였다. 대상 및 방법:본 연구는 Water Pump (DPW44-12 Water Pump, AC 220V Adapter)와 3D-printed stenosis model 을 이용하여 In vitro flow phantom system을 제작하였다. 제작한 phantom에 70kg 환자 기준 4.8L의 물을 순환시키면서 4D flow를 획득하였으며 조영제 Gd–DOTA (Gadoterate meglumine, Dotarem, Guerbet, France)를 1.75mmol, 3.5mmol, 4.75mmol, 7mmol/4.8L 희석하였다. 매개 변수로는 TR=10.6ms, NEX=1, FOV=200×200mm, voxel size= 1.5mm×1.5mm× 1.5mm, Temporal resolution=30, VENC=150cm/s이다. 이때, 조영제에 의한 SNR 증가와 Phase 의 변화를 관찰하기 위해 Flip Angle(FA)=5゚, 10゚, 15゚, 20゚로, TE=2.3ms, 4.6ms, 6.9ms, 9.2ms로 나누어 영상을 획득하였다. 결과:구간별 조영제에 의한 SNR 증가 비교결과, 0~1.75mmol 구간에서 FA 5°-116%, FA 10°-77%, FA 15°-65%, FA 20°-64%로 가장 큰 증가 폭을 보였으며 그 이후로는 완만하게 증가하다가 포화하는 경향을 보였다(p<0.01). Multi echo를 이용하여 각 조영제 농도별 Signal intensity를 TE=0ms일 때, 최고값 100%로 환산 후 non-linear square curve fitting 한 결과, R2* value는 0 mmol=0.0769, 1.75 mmol=0.0793, 3.5 mmol=0.0813, 4.75 mmol=0.0826, 그리고 7 mmol=0.0892로 각기 다른 값으로 측정되었다. 결론:4D flow MRI는 조영제 주입 시 SNR을 증가시킬 수 있으나 국소 자기장 불균일로 인한 Phase error를 발생시킬 수 있다. 그러므로 심장 박동, 호흡 동조 등의 문제로 인한 낮은 SNR을 보상하기 위해 소량의 조영제를 사용하는 것은 신호의 증가를 유도할 수 있으나 부정확한 Phase contrast를 발생시킬 수 있으므로 권고하지 않는다.
        4,000원
        85.
        2019.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Squamous odontogenic tumor (SOT) is a relatively rare, benign, small (rarely > 1.5 cm in diameter), but locally infiltrative and occasionally aggressive odontogenic epithelial lesion that appears to have harmatomous and neoplastic characteristics [1]. SOT is often asymptomatic, although it can present with mildly painful gingival swelling or tooth mobility. Radiographically, SOT is usually visualized as an irregularly or triangularly shaped unilocular radiolucency associated with the lateral roots of teeth. We report a case of the squamous odontogenic tumor occurring in a 60-year-old female in the right posterior maxilla with unusual radiographic and clinical appearances.
        4,000원
        87.
        2019.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: Spontaneous use of the upper extremities on the affected side of patients with stroke is a meaningful indicator of recovery and may vary by the age or dominant hand of patients. No prior study has reported changes in actual amount of use test (AAUT) and motor activity log (MAL)-28 according to age and handedness in healthy adults, and AAUT inter-rater reliability for assessment of healthy adults. Objects: This study aimed to (1) research the differences in AAUT and MAL-28 according to age and handedness in healthy adults, and (2) determine the inter-rater reliability of the AAUT. Methods: Seventy healthy adults participated in this study. The MAL-28 was assessed by dividing 61 subjects into young right-handed (n1=20), young left-handed (n2=21), and older right-handed (n3=20) groups. The AAUT was assessed by dividing 63 subjects into young right-handed (n1=25), young left-handed (n2=18), and older right-handed (n3=20) groups. Student’s t-test and the Wilcoxon signedrank test were used for statistical analysis. Results: The Amount of Use (AOU) scale values for each group showed no significant differences between age groups and handedness groups in the MAL-28 (p>.05). The AAUT AOU scale value showed significant differences regarding dominant handedness in the AAUT (p<.05), but no significant differences according to age (p>.05). (2) Inter-rater reliability of the AAUT was excellent, except few items (item 9, 11, and 12). Conclusion: Although both the MAL-28 and the AAUT measured how much participants used their dominant arms in healthy subjects, the AAUT only showed significantly higher dominant arm use in left hander than the right hander. In addition, the inter-rater reliability of the AAUT was excellent. Current results can be utilized as a basic information when clinicians develop rehabilitation strategies, and AAUT was shown to be a reliable evaluation tool for measurement of upper extremity use in Korean adults, based on the reliability demonstrated by this study.
        4,000원
        88.
        2019.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        59세 여자가 복부 통증을 주소로 내원하였다. 복부 전산화 단층촬영에서 담관 결석이 의심되는 병변이 발견되었다. 내시경역행담췌관조영술을 하는 중에 간디스토마 성충이 배출되었다. 대변과 혈청에서 간디스토마 충란과 항체가 각각 발견되어 간디스토마 감염증으로 진단하였다. 내시경 시술과 구충제를 복용 후 증상은 서서히 호전되었다. 환자는 간디스토마 비유행지역에 거주하였고 날 것이나 덜 익힌 민물생선을 섭취한 기왕력이 없었다. 대한민국은 간디스토마 유행지역에 속하며 사람들은 조리기구 등을 통한 간접 접촉을 통해서 감염될 수 있다. 그러므로 대한민국에서 담관 질환이 있는 환자들을 진료할 때 간디스토마 감염의 가능성을 고려하여야 한다. 우리는 문헌고찰과 함께 임상 증례를 보고한다.
        4,000원
        89.
        2019.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Odontogenic keratocyst (OKC), also known as keratocystic odontogenic tumor (KCOT), is an emerging odontogenic tumor originating from the dental lamina. It is an aggressive lesion with a squamous epithelium and a recurrence rate of 15-35%.1 Radiologically, there is a clear, smooth, or shell-like border showing a unilocular or multifocal, polycystic radiographic picture. Hard tissue formation in OKC is a very rare phenomenon and occurs in the form of dystrophic calcification, cartilaginous tissue or dentinoid.2 In this article, we report the case of OKC with calcification. OKC with radiopaque lesion is very rare, these are considered as dystrophic calcification, dentinoid formation, ossification. The incidence of dystrophic calcification in recurrent OKC is low, so it can be inferred that the recurrence rate of OKC with dystrophic calcification is lower than that of conventional OKC.
        4,000원
        90.
        2019.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: Mucoepidermoid carcinoma (MEC) is the most common malignant epithelial tumor of the salivary gland in the oral cavity. In South Korea, it occurs most frequently in the palate, retromolar area, floor of the mouth, buccal mucosa, and other areas of the oral cavity. MEC is rare in children and adolescents under 20 years of age, but it is the most common malignant salivary gland tumor in this group. Reconstructive surgery is often required due to cystic lesions or resection of malignancy in the oral cavity. Buccal fat pad (BFP) is a flap that is reliable and suitable for reconstructing oral defects because it has a low complication rate and small volume change over time. Case Presentation: We report the case of a 12-year-old female patient with low-grade MEC on light soft palate with no neck metastasis. After tumor resection the palatal mucosal defect was reconstructed with a BFP flap. Conclusion: The purpose of this article is to discuss the features and treatment methods of MEC that is rarely occurring in children, and the usefulness of BFP for reconstruction. Therefore, we will make a precise diagnosis and treatment as we examine the clinical feature and review the literature.
        4,000원
        91.
        2019.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        이 논문은 첫째, 明末 전후의 진보적인 儒者는 ‘治生’을 긍정적으로 바라보았고, 심지어 치생이 ‘財富의 분배(증여)’와 상반되는 것이 아니라 증여를 실천할 바탕이라고 인식했음을 밝힌다. 그리고 명말의 단편소설집『三言二拍』의 작가 ― 馮夢龍과 凌濛初는 그들의 저술 목적 이 敎化에 있고 通俗적 수단을 지향한다고 했는데, 이러한 의식 기저에는 ‘치생’ 욕구와 ‘증여’ 의식이 함께 교차함을 밝혔다. 둘째, 그러한 치생과 증여의 의식이 『삼언이박』에서 문학 적으로 형상화되어서 배려, 구원, 적선, 환원 등의 다양한 ‘증여’ 서사가 펼쳐짐을 밝힌다. 아울러 여러 ‘증여’ 서사를 지배하는 의식의 기저를 규명하여 재부의 축적과 재분배가 어떻게 문학적으로 담론되는지를 밝혔다.
        5,400원
        92.
        2019.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was planned to evaluate the efficacy of surgical treatment in stage 2 medication related osteonecrosis of jaw(MRONJ) patients. Retrospective analysis was performed about patients who were treated with medication related osteonecrosis of jaw from 2015 to 2017. 25 Patients were treated by a single surgeon at the Department of Oral Surgery, Dental Hospital, Pusan National University. The treatment methods they received were conservative or surgical. The results of treatment were classified as "fail" and "success" and the prognosis according to the treatment method was compared. Conservative treatment 14.29% (2 cases), sequestrectomy 64.29% (9 cases) and saucerization 21.43% (3 cases) were performed in the MRONJ group, and 2 treatment failures were encountered after conservative treatment and 1 after saucerization. Surgical treatment resulted in better outcomes in stage 2 MRONJ patients. Furthermore, treatments were deemed successful when surrounding necrotic bone containing sequestrum was reliably removed. Therefore, this study suggests that the treatment of "stage 2" MRONJ should actively consider surgical treatment.
        4,000원
        93.
        2019.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Autophagy is recently receiving the spotlight as the development strategy for promising anticancer drugs. In particular, the majority of anticancer drugs originating from natural products are known to induce autophagy. Saururus chinensis has been used for treating various inflammatory diseases. Recent research has revealed that the extract of Saururus chinensis possess cytotoxicity for various types of human cancer cells. However, the exact action mechanism of Saururus chinensis extract for oral squamous cell carcinoma (OSCC) has not been studied yet. Therefore, the authors of this research aim to study the effect of methanol extract of S. chinensis (MESC) on OSCC cells. To observe the cell proliferation inhibitory effect of MESC on HSC3 cells, the authors conducted the trypan blue exclusion assay. Also, the action mechanism of MESC was studied by conducting the cell cycle analysis, acidic vesicular organelle (AVO) staining and flow cytometry analysis, monodansylcadaverine (MDC) staining, propidium iodide staining, and Western blotting on MESC-treated HSC3 cells. When HSC3 cells were treated in MESC, the cell proliferation was suppressed in time-dependent and dose-dependent manners. Also, the number of sub-G1 arrested cells increased in a dose-dependent manner. MDC punctate and AVO puncta significantly increased respectively. Western blot analysis demonstrated the expression of autophagy-related proteins increased, but apoptotic proteins were not observed. Also, the pAkt protein was reduced, while the p-p38 protein and pERK protein increased. According to our results, MESC induced autophagy and accompanied changes in the cell cycle in HSC3 cells. Also, the alteration in Akt, ERK, and p38 pathways were confirmed. This result suggested the possibility of MESC as the new promising adjuvant for treating OSCC patients.
        4,000원
        94.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 2017년 4월부터 10월까지 북한강 수계 3개의 연속댐 (의암호 (UA), 청평호 (CP), 팔당호 (PD))의 미소생물 군집과 이취미 농도와 관계를 알아보기 위해 환경요인, 이취미 물질, 미소생물 군집 등을 조사하였다. 3개 저수지의 박테리아 군집은 주로 Actinobacteria와 Betaproteobacteria가 우점 분류군으로 나타났으며, 계절성은 나타나지 않았다. 식물플랑크톤 군집은 봄철, 규조류 및 은편모조류 여름철 남조류, 가을철 규조류 및 은편모조류 순서로 우점하는 계절성을 보였으며, 북한강 수계에서 출현한 남조류는 Dolichospermum spp., Microcystis aeruginosa, Pseudanabaena spp. 속이 우점 출현하였다. 북한강 수계에 출현한 미소생물 중 이취미 물질을 발생하는 분류군은 Actinobacteria와 남조 Anabaena, Pseudanabaena 속 등이며, 이취미 물질인 Geosmin과 2-MIB가 높게 나타났을 때, 높은 현존량으로 출현하였다. 미소생물과 이취미 물질의 상관관계는 Actinobacteria의 경우 2-MIB (r=0.491, p<0.01)와 유의한 상관성을 나타냈으며, 남조류의 경우 geosmin (r=0.381, p<0.05), 2-MIB (r=0.386, p<0.05)와 유의한 상관성을 나타냈다. 따라서, 북한강 수계에서 나타나는 이취미 물질은 Actinobacteria 및 남조류의 출현과 직접적인 관계가 있을 것으로 사료되며, 남조류 미출현 시 발생하는 높은 농도의 이취미 물질은 Actinobacteria가 생성하는 것으로 판단된다.
        4,300원
        95.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Natural products are vastly utilized as a source of chemotherapeutic agents for human cancers. Kochia scopraia is traditionally used for the cure of urological and dermatological diseases. Recently, methanol extract of Kochia scoparia (MEKS) has been shown to have anti-cancer activity to various human cancers. However, there is no report demonstrating the anti-cancer activity of MEKS in human mucoepidermoid carcinoma (MEC) cells. In this study, the authors studied the effects of MEKS on the cell proliferation and underlying mechanism in YD15 human MEC cells. MEKS decreased YD15 cell proliferation proven by trypan blue exclusion assay and induced apoptosis, evidenced by cell cycle analysis and western blotting. Autophagy induction by MEKS was verified by western blotting. In addition, MEKS regulated the expression of phosphorylated Akt, phosphorylated p38 and Nrf2 protein. This results can imply that MEKS might be a potential candidate for the treatment of human MEC cells.
        4,000원
        96.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The Hippo pathway was originally discovered in Drosophila by genetic screening and it has been shown to be conserved in various organisms including human. Until now, the essential roles of Hippo pathway in regulating cell proliferation, apoptosis, tumorigenesis, and organ size control is extensively studied. Currently, Mats1/2 (Mob1a/1b), one of the important components in Hippo pathway, mutant mice were generated which has abnormal phenotype such as resistance to apoptosis and spontaneous tumorigenesis. Of note, Mats1/2 mutant mice also showed dental malocclusion. Therefore, in this study, we have evaluated the bone phenotype of Mats1/2 mutant mice. Although the mRNA expressions of Mats1 or Mats2 were observed in both osteoclastogenesis and osteoblastogenesis, the increase of Mats1 level was most prominent during osteoblastogenesis. The RANKL-induced osteoclast differentiation from bone marrow-derived macrophages (BMMs) was unaltered upon Mats1/2 mutation; however, the osteoblast differentiation using calvarial pre-osteoblasts was significantly reduced in Mats1/2 mutant mice compare to that of wild type mice. In accordance with in vitro results, Mats1/2 mutant mice showed decreased bone volume as well as increased trabecular separation in μCT analyses. These results may provide novel prospect of the probable linkage between Hippo pathway and bone homeostasis.
        4,000원
        97.
        2018.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        V. vulnificus는 그람음성의 호염성균으로 감염 되었을 경우, 복통과 발열 등의 급성 위장염을 일으키며 만성질환자에게 급성 패혈증을 일으키는 매우 높은 치사율의 식중 독균이다. 식품 중에서 V. vulnificus를 분석하는 방법으로 는 TCBS agar와 같은 선택배지를 이용하는 방법과 PCR 을 이용한 방법이 있으나 온도, 염 및 pH 등과 같은 환경요인에 민감한 V. vulnificus의 특성을 고려하였을 때 정확한 균수 정량을 위한 정량분석법 확립의 필요성이 요구된 다. 본 연구에서는 배지 및 염 차이에 따른 V. vulnificus 생육 특성 차이에 대한 연구를 진행하였다. 그 결과, V. vulnificus 균수 정량분석에 APW 증균 배양을 이용한 MPNPCR 방법이 적합하였다. 본 연구에서 제시된 방법은 해수뿐만 아니라 어패류 등의 시료에서 V. vulnificus 균수 정 량분석에 유용하게 사용될 것으로 기대된다.
        3,000원
        98.
        2018.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        견과류 중에 있는 트리코테센계 곰팡이독소 오염도를 조사하기 위하여 LC-MS/MS를 이용한 정확성과 신뢰성을 동시에 확보할 수 있는 분석방법을 개발하였다. 견과류 중 트리코테센계 곰팡이 독소는 QuEChERS 추출 및 EMRLipid- dSPE 정제과정을 통하여 분석에 사용되었다. 검량선 작성을 위하여 트리코테센계 곰팡이독소 10종에 대하여 2.00~75.00 μg/kg의 범위로 혼합표준용액을 제조하여 실험 하였으며, 상관계수는 모두 0.998 이상으로 높은 직선성을 나타내었다. 분석방법의 검출한계는 0.41~3.57 μg/kg로 나타났으며, 정량한계는 1.23~10.82 μg/kg로 나타났다. 또한 트리코테센계 곰팡이 독소 10종에 대하여 각각 저, 중, 고 3가지 농도로 처리하여 회수율 실험을 수행한 결과 81.84~ 96.87%로 나타났다. 확립된 분석법으로 견과류 중 땅콩을 대상으로 오염도를 조사한 결과 1종에서 deoxynivalenol이 검출되었다. 이러한 결과를 바탕으로 확립된 시험법은 견과류 중 트리코테센계 곰팡이 독소 분석에 적합함을 확인 할 수 있었으며 견과류 중 트리코테센계 곰팡이 독소 검출 가능성을 확인한바 보다 다양한 종류의 견과류에 대한 모니터링 조사가 필요한 것으로 판단된다.
        4,000원
        99.
        2018.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 논문에서는 교육용 코딩퍼즐게임의 모델링에 대하여 분석하고 이를 바탕으로 유·아동에게 효과적인 형식의 코딩게임을 구현하며, 그 적합도를 평가한다. 시중에 출시된 여러 코딩퍼즐게임들의 핵심체계가 되는 학습개념, UI체계, 게임시스템의 특징과 문제점을 분석한 후, 이를 바탕으로 새로운 학습용 퍼즐게임을 개발한다. 개발된 게임의 학습개념, UI체계, 게임시스템을 소개하고, 개발된 게임을 실제로 적용한 어린이집 모의수업과 실습수업 진행과정에 대하여 기술한다. 실제로 게임을 실행하게 되는 아이들에게 있어서 적정 수준의 단계가 어느 정도인지를 판단하기 위해 개발된 게임에 대해서 어린이집 방과후 학습교사들의 평가로 개념의 시각화, 직관적 요소, 난이도 조절의 세 항목에 대하여 평가과정(각각 5점 만점)을 거쳤다. 그 결과로 개발된 게임은 직관적 요소에서 4.08점, 난이도 조절에서 3.72점, 개념의 시각화에서 3.44점을 나타내어 모두 보통 이상의 결과를 나타냈다. 개념의 시각화를 위해서는 개념 자체를 활용할 수 있는 포맷의 적용, 직관적 요소로 스테이지의 시작과 종료를 알리는 명확한 요소의 적용, 난이도 조절로는 연습문제 챕터의 적용이 주요한 것으로 나타났다.
        4,000원
        100.
        2018.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We perform density functional theory calculations to study the CO and O2 adsorption chemistry of Pt@X core@shell bimetallic nanoparticles (X = Pd, Rh, Ru, Au, or Ag). To prevent CO-poisoning of Pt nanoparticles, we introduce a Pt@X core-shell nanoparticle model that is composed of exposed surface sites of Pt and facets of X alloying element. We find that Pt@Pd, Pt@Rh, Pt@Ru, and Pt@Ag nanoparticles spatially bind CO and O2, separately, on Pt and X, respectively. Particularly, Pt@Ag nanoparticles show the most well-balanced CO and O2 binding energy values, which are required for facile CO oxidation. On the other hand, the O2 binding energies of Pt@Pd, Pt@Ru, and Pt@Rh nanoparticles are too strong to catalyze further CO oxidation because of the strong oxygen affinity of Pd, Ru, and Rh. The Au shell of Pt@Au nanoparticles preferentially bond CO rather than O2. From a catalysis design perspective, we believe that Pt@Ag is a better-performing Ptbased CO-tolerant CO oxidation catalyst.
        4,000원
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