Recent Studies Conducted in Environmental Health Field in KMC : Behavioral Functional Tests and Genotoxicity Detection in Rats after Exposure to Low Density 1800MHz(CW)-RF

( Xi Nan Wu ),( Tian Ming Cheng ),( Ping Liu ) 한국환경보건학회(구-한국환경위생학회) 2004 Current Challenges and Advances in Environmental H Vol.- No.-

Effect of Template Removal on Synthesis of Organic-Inorganic Hybrid Mesoporous MCM-48

Ya Nan Zhao, San Xi Li,Chong Soo Han,San Xi Li 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.10

Post-synthesis is used to synthesize organic hybrid inorganic mesoporous sieves. In this method, the activity and structure of the base sieve are crucial to obtain the definable hybrid materials. The chemical and physical properties of the base can be largely changed either by the final step of its synthesizing processes, by template removal which is accomplished with the oxidative thermal decomposition (burning) method or by solvent extraction method. In this paper we compared two methods for the post-synthesis of organic hybrid MCM-48. When the template was extracted with HCl/alcohol mixture, the final product showed larger pore size, larger pore volume and better crystallinity compared to the case of the thermal decomposition. The reactivity of the surface silanol group of template free MCM-48 was also checked with an alkylsilylation reagent CH2=CHSi(OC2H5)3. Raman and 29Si NMR spectra of MCM-48 in the test reaction indicated that more of the organic group was grafted to the surface of the sample after the template was removed with the solvent extraction method. Direct synthesis of vinyl-MCM-48 was also investigated and its characteristics were compared with the case of post-synthesis. From the results, it was suggested that the structure and chemical reactivity can be maintained in the solvent extraction method and that organic grafting after the solvent extraction can be a good candidate to synthesize a definable hybrid porous material.

Assessment of the Severity of Coronavirus Disease: Quantitative Computed Tomography Parameters versus Semiquantitative Visual Score

Yin Xi,Min Xiangde,Nan Yan,Feng Zhaoyan,Li Basen,Cai Wei,Xi Xiaoqing,Wang Liang 대한영상의학회 2020 Korean Journal of Radiology Vol.21 No.8

Objective: To compare the accuracies of quantitative computed tomography (CT) parameters and semiquantitative visual score in evaluating clinical classification of severity of coronavirus disease (COVID-19). Materials and Methods: We retrospectively enrolled 187 patients with COVID-19 treated at Tongji Hospital of Tongji Medical College from February 15, 2020, to February 29, 2020. Demographic data, imaging characteristics, and clinical data were collected, and based on the clinical classification of severity, patients were divided into groups 1 (mild) and 2 (severe/ critical). A semiquantitative visual score was used to estimate the lesion extent. A three-dimensional slicer was used to precisely quantify the volume and CT value of the lung and lesions. Correlation coefficients of the quantitative CT parameters, semiquantitative visual score, and clinical classification were calculated using Spearman’s correlation. A receiver operating characteristic curve was used to compare the accuracies of quantitative and semi-quantitative methods. Results: There were 59 patients in group 1 and 128 patients in group 2. The mean age and sex distribution of the two groups were not significantly different. The lesions were primarily located in the subpleural area. Compared to group 1, group 2 had larger values for all volume-dependent parameters (p < 0.001). The percentage of lesions had the strongest correlation with disease severity with a correlation coefficient of 0.495. In comparison, the correlation coefficient of semiquantitative score was 0.349. To classify the severity of COVID-19, area under the curve of the percentage of lesions was the highest (0.807; 95% confidence interval, 0.744–0.861: p < 0.001) and that of the quantitative CT parameters was significantly higher than that of the semiquantitative visual score (p = 0.001). Conclusion: The classification accuracy of quantitative CT parameters was significantly superior to that of semiquantitative visual score in terms of evaluating the severity of COVID-19.

Research of Adaptive Fault-Tolerant Control based on T-S Fuzzy Model for EMB System

Yi-Nan Xi 호서대학교 공업기술연구소 2014 공업기술연구 논문집 Vol.33 No.1

In the electro mechanical brake (EMB) system, an improvement of the fault-tolerant control, like invalid protecticais of sensors and electric systems are the key problems to the development of electric vehicles. The adaptive fault-tolerant control in this paper is focus on the descriptor nonlinear system A^iich contains double time-delays and parameter uncertainties. In fault detection and estimatic»i, cxmstruct the controlled system model wliich contains multi-sensor, double time-delays and parameter uncertainties based on T-S fuzzy model, then design the observer to realize fault detection and estimation in real-time. In building the fault-tolerant control model, the first step is to choose an appropriate sliding surface, and combine the algorithm of sliding control with adaptive generic model control. Then apply the state observer to the designed sliding adaptive generic model, and build the decision model with dynamic fault reconfiguration. And the goal of this paper about the adaptive robust fault-tolerant control for the complex nonlinear controller system is achieved. Numerical SIMULINK simulation examples are given to illustrate the application and the effectiveness of the proposed design method.

70 年代前半期驻韩美军减撤问题与韩美关系变动

리난시(李南希)(Nan-Xi Li) 한중경제사회연구소 2024 한중경제사회연구 Vol.1 No.1

驻韩美军不仅是美国对韩安全保护的直接战略力量,是更是牵动和实时反映韩美同盟变 化的关键指标,这一现象在上世纪七十年代前半期有过集中体现。60 年代末,越南战争的愈发 胶着,国内反战运动的振起,经济走势低迷,美国正逐步深陷泥潭。尼克松上台之后,在亚洲 范围内实施收缩政策,驻韩美军撤军计划被提上日程。在多番艰苦协商之下,两万兵力从韩国 境内撤出。韩美之间也因此产生摩擦,出现同盟信任危机,韩美关系降至冰点。福特政府接任 后为消除韩方的安保危机感,保证朝鲜半岛的军事平衡,在重新评估后下令暂停驻韩美军撤军 计划。同时为提高韩国的自主国防能力,继续向韩国提供军事援助,援助方式也由此前的无偿 军事援助转变为对外军售和军事贷款。自此韩美关系相较上一任有较大缓和,韩国国防的现代 化进程也得以迅速推进。 The USFK is not only the direct strategic force of the United States to protect the security of South Korea, but also the key indicator that affects and reflects the changes of the South Korea-U.S. Alliance in real time. This phenomenon was particularly evident in the first half of the 1970s. By the late 1960s, as the Vietnam War intensified and domestic anti-war movements surged, coupled with economic downturns, the U.S. was gradually sinking into the mire. Subsequently, the Nixon administration implemented a policy of retrenchment in Asia and planned to withdraw U.S. troops stationed in Korea. After multiple consultations between Korea and the U.S., a force of 20,000 troops was withdrawn from Korean. This withdrawal caused a crisis of alliance trust between Korea and the U.S.,and relations between South Korea and the United States fell to the freezing point. However, the Ford administration, in an effort to alleviate South Korea's security concerns and ensure military balance on the Korean Peninsula, ordered a suspension of the withdrawal of U.S. troops stationed in South Korea after reassessing the situation. At the same time, to enhance South Korea's autonomous defense capability, the U.S. continued to provide military assistance to South Korea, transitioning from gratuitous military aid to foreign military sales and military loans. Since then, compared to the previous administration, there has been a significant easing of tensions in South Korea-U.S. relations, and the modernization process of South Korea's defense has also been rapidly advancing.

Recent Developments in the Effects of Different Dopants on the Structure and Property of Lithium Titanate Material

Xi-Yang Li,Qian-Lin Chen,Min Yang,Ya-Nan Li,Jing-Bo Ma 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.3

The lithium titanium spinel Li4Ti5O12 has attracted more and more attention as anode materials applied in lithium ion batteries. Li4Ti5O12 material has been found to be able to intercalate lithium ions without deformation of the lattice. However, compared with graphite and other anode materials, the low conductivity of Li4Ti5O12 restricts its charging and discharging rate. Doping is deemed to be a businesslike method to enhance ionic and electronic conductivity of Li4Ti5O12. This paper reviews the effects of Li4Ti5O12 with different doping ions on different crystal lattice states. And it has been found by a summary that the doping objective of doping ions at Li4Ti5O12 is also different. Moreover, the applications of ion doping in different fields of Li4Ti5O12 are prospected.

Renal-Clearable Hollow Bismuth Subcarbonate Nanotubes for Tumor Targeted Computed Tomography Imaging and Chemoradiotherapy

Hu, Xi,Sun, Jihong,Li, Fangyuan,Li, Ruiqing,Wu, Jiahe,He, Jie,Wang, Nan,Liu, Jianan,Wang, Shuaifei,Zhou, Fei,Sun, Xiaolian,Kim, Dokyoon,Hyeon, Taeghwan,Ling, Daishun American Chemical Society 2018 Nano letters Vol.18 No.2

<P>Although metallic nanomaterials with high X-ray attenuation coefficients have been widely used as X-ray computed tomography (CT) contrast agents, their intrinsically poor biodegradability requires them to be cleared from the body to avoid any potential toxicity. On the other hand, extremely small-sized nanomaterials with outstanding renal clearance properties are not much effective for tumor targeting because of their too rapid clearance in vivo. To overcome this dilemma, here we report on the hollow bismuth subcarbonate nanotubes (BNTs) assembled from renal-clearable ultrasmall bismuth subcarbonate nanoclusters for tumor-targeted imaging and chemoradiotherapy. The BNTs could be targeted to tumors with high efficiency and exhibit a high CT contrast effect. Moreover, simultaneous radio- and chemotherapy using drug-loaded BNTs could significantly suppress tumor volumes, highlighting their potential application in CT imaging-guided therapy. Importantly, the elongated nanotubes could be disassembled into isolated small nanoclusters in the acidic tumor microenvironment, accelerating the payload release and kidney excretion. Such body clearable CT contrast agent with high imaging performance and multiple therapeutic functions shall have a substantial potential for biomedical applications.</P>

Effect of Aged Lubricating Oil on the Regeneration of Diesel Particulate Filters and Ash Physical Characteristics with Non-Thermal Plasma Technology

Zhao Nan,Cai Yi-xi,Shi Yunxi,Wang Weikai,Ni Sijia 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.5

The objective of this study was to evaluate the effects of lubricating oil age on the generation of diesel particulate filters (DPF) by non-thermal plasma (NTP) technology and to characterize the physical properties of ash. The regeneration status was evaluated by the concentration of regeneration products and regeneration temperature. The compositional and morphological characteristics of ash were analyzed by energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Compared with DPF@L-fresh, the internal regeneration temperature was reduced in DPF@L-age. The unit removal time of carbon was 39.23 min/g for DPF@L-fresh but was reduced to 34.87 min/g for DPF@L-age, which indicated that the efficiency of NTP regeneration increased. Shorter regeneration time and lower airflow resistance caused by NTP technology aided the formation of a unique chain-type ash with the structure of a hollow column. Several fine particles that had formed by the condensation of volatiles were distributed on the ash surface of the aged lubricant, and the ash clusters were loosely combined. TEM images revealed that ash was mostly composed of a crystal structure, that the ash dimension of aged lubricant decreased, and that the adhesion between ash particulates was weak.

A New Furfural Diglycoside and Other Carbohydrate Derivatives from Fermented Beverage of Prunus mume Fruit

Yan, Xi-Tao,Li, Wei,Sun, Ya-Nan,Yang, Seo Young,Song, Gyu Yong,Kim, Young Ho Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.7

Seismic fragility assessment of self-centering RC frame structures considering maximum and residual deformations

Lu-Xi Li,Hong-Nan Li,Chao Li 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.68 No.6

Residual deformation is a crucial index that should be paid special attention in the performance-based seismic analyses of reinforced concrete (RC) structures. Owing to their superior re-centering capacity under earthquake excitations, the post-tensioned self-centering (PTSC) RC frames have been proposed and developed for engineering application during the past few decades. This paper presents a comprehensive assessment on the seismic fragility of a PTSC frame by simultaneously considering maximum and residual deformations. Bivariate limit states are defined according to the pushover analyses for maximum deformations and empirical judgments for residual deformations. Incremental Dynamic Analyses (IDA) are conducted to derive the probability of exceeding predefined limit states at specific ground motion intensities. Seismic performance of the PTSC frame is compared with that of a conventional monolithic RC frame. The results show that, taking a synthetical consideration of maximum and residual deformations, the PTSC frame surpasses the monolithic frame in resisting most damage states, but is more vulnerable to ground motions with large intensities.