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졸-겔법으로 제조한 ZrO_2·SiO_2계 결정화 유리의 결정화 및 파괴인성에 관한 연구
신대용,한상목,강위수 강원대학교 산업기술연구소 2000 産業技術硏究 Vol.20 No.A
Precursor gels with the composition of xZrO_2·(100-x)SiO_2 systems (x=10,20 and 30mol%) were prepared by the sol-gel method. Kinetic parameter, such as activation energy, Avrami's exponent, n, and dimensionality crystal growth value, m, have been simultaneously calculated from the DTA data using Kissinger and Matusita equations. The crystallite size dependence on tetragonal to monoclinic transformation of ZrO_2 was investigated using XRD, in relation to the fracture toughness. The crystallization of tetragonal ZrO_2 occurred through 3-dimensional diffusion controlled growth(n=m=2) and the activation energy for crystallization was calculated using Kissinger and Matusita equations, as about 310∼325±10kJ/mol. The growth of t-ZrO_2, in proportion to the cube of radius, increased with increasing heating temperature and heat-treatment time. It was suggested that the diffusion of Zr4+ions by Ostwald ripening was rate-limiting process for the growth of t-ZrO_2 crystallite size. The fracture toughness of xZrO_2·(100-x)SiO_2 systems glass ceramics increased with increasing crystallite size of t-ZrO_2. The fracture toughness of 30ZrO_2·70SiO_2 system glass ceramics heated at 1,100℃ for 5h was 4.84 MPam^1/2 at a critical crystaliite size of 40 nm.
박지은,정연재,박준범,김혜영,유영현,이광식,양원태,김도훈,김종민 한국발생생물학회 2019 발생과 생식 Vol.23 No.3
Type 2 diabetes mellitus (T2DM) is characterized by insulin resistance (IR). T2DM is correlated with obesity and most T2DM medications have been developed for enhancing insulin sensitivity. Silk protein fibroin (SPF) from spiders has been suggested as an attractive biomaterial for medical purposes. We generated transgenic rice (TR) expressing SPF and fed it to diabetic BKS.Cg-m+/+Leprdb mice to monitor the changes in blood glucose levels and adipose tissue proteins associated with energy metabolism and insulin signaling. In the present study, the adipocyte size in abdominal fat in TR-SPF-fed mice was remarkably smaller than that of the control. Whereas the adenosine monophosphate-activated protein kinase (AMPK)-activated protein kinase and insulin receptor substrate 1 (IRS1) protein levels were increased in abdominal adipose tissues after TR-SPF feeding, levels of six-transmembrane protein of prostate 2 (STAMP2) proteins decreased. Phosphorylation of AMPK at threonine 172 and IRS1 at serine 307 and tyrosine 632 were both increased in adipose tissues from TR-SPFfed mice. Increased expression and phosphorylation of IRS1 at both serine 307 and tyrosine 632 in adipose tissues indicated that adipocytes obtained from abdominal fat in TR-SPF-fed mice were more susceptible to insulin signaling than that of the control. STAMP2 protein levels decreased in adipose tissues from TR-SPF-fed mice, indicating that STAMP2 proteins were reducing adipocytes that were undergoing lipolysis. Taken together, this study showed that TR-SPF was effective in reducing blood glucose levels in diabetic mice and that concurrent lipolysis in abdominal adipocytes was associated with alterations of AMPK, IRS1, and STAMP2. Increased IRS1 expression and its phosphorylation by TR-SFP were considered to be particularly important in the induction of lipolysis in adipocytes, as well as in reducing blood glucose levels in this animal model.
Distributed Mobility Management Strategy with Pointer Forwarding Technique
Wie, Sunghong,Jang, Jaeshin The Korea Institute of Information and Commucation 2015 Journal of information and communication convergen Vol.13 No.4
With the dramatic increase in mobile traffic in recent years, some of the limitations of mobility management frameworks have magnified. The current centralized mobility management (CMM) strategy has various problems, such as a suboptimal routing path, low scalability, signaling overhead, and a single point of failure. To overcome these weaknesses in the CMM strategy, the Internet Engineering Task Force has been discussing distributed mobility management (DMM) strategies. The fundamental concept of a DMM strategy is to distribute the mobility anchors closer to the users. While the distribution of mobility anchors results in low-cost traffic delivery, it increases the signaling cost. To reduce this higher signaling cost, we propose a new DMM strategy applying the pointer forwarding technique. The proposed strategy keeps the existing tunnels and extends the traffic path as much as possible. In this paper, we analyze the performance of the pointer forwarding-DMM strategy and discuss its pros and cons.
SDN-based Hybrid Distributed Mobility Management
Wie, Sunghong The Korea Institute of Information and Commucation 2019 Journal of information and communication convergen Vol.17 No.2
Distributed mobility management (DMM) does not use a centralized device. Its mobility functions are distributed among routers; therefore, the mobility services are not limited to the performance and reliability of specific mobility management equipment. The DMM scheme has been studied as a partially distributed architecture, which distributes only a packet delivery domain in combination with the software defined network (SDN) technology that separates the packet delivery and control areas. Particularly, a separated control area is advantageous in introducing a new service, thereby optimizing the network by recognizing the entire network situation and taking an optimal decision. The SDN-based mobility management scheme is studied as a method to optimize the packet delivery path whenever a mobile node moves; however, it results in excessive signaling processing cost. To reduce the high signaling cost, we propose a hybrid distributed mobility management method and analyze its performance mathematically.
Wie, Gyung-Ah,Cho, Yeong-Ah,Kang, Hyun-hee,Ryu, Kyoung-A,Yoo, Min-Kyoung,Kim, Young-A,Jung, Kyu-Won,Kim, Jeongseon,Lee, Joo-Hyuk,Joung, Hyojee Cambridge University Press 2014 The British journal of nutrition Vol.112 No.2
<P>Cancer is a leading cause of death, and the dietary pattern in Korea is changing rapidly from a traditional Korean diet to a Westernised diet. In the present study, we investigated the effects of dietary factors on cancer risk with a prospective cohort study. Among 26 815 individuals who participated in cancer screening examinations from September 2004 to December 2008, 8024 subjects who completed a self-administered questionnaire concerning demographic and lifestyle factors, and a 3 d food record were selected. As of September 2013, 387 cancer cases were identified from the National Cancer Registry System, and the remaining individuals were included in the control group. The hazard ratio (HR) of cancer for the subjects older than or equal to 50 years of age was higher (HR 1·80, 95 % CI 1·41, 2·31; <I>P</I>< 0·0001) than that for the other subjects. Red meat consumption, Na intake and obesity (BMI ≥ 25 kg/m<SUP>2</SUP>) were positively associated with overall cancer incidence in men (HR 1·41, 95 % CI 1·02, 1·94; <I>P</I>= 0·0382), gastric cancer (HR 2·34, 95 % CI 1·06, 5·19; <I>P</I>= 0·0365) and thyroid cancer (HR 1·56, 95 % CI 1·05, 2·31; <I>P</I>= 0·0270), respectively. Participants who had at least three dietary risk factors among the high intakes of red meat and Na, low intakes of vegetables and fruits, and obesity suggested by the World Cancer Research Fund/American Institute for Cancer Research at baseline tended to have a higher risk of cancer than the others (HR 1·26, 95 % CI 0·99, 1·60; <I>P</I>= 0·0653). In summary, high intakes of red meat and Na were significant risk factors of cancer among Koreans.</P>
Wie, Myung-Bok,Song, Dong-Keun,Kim, Yung-Hi The Korean Society of Pharmacognosy 1993 생약학회지 Vol.24 No.3
We investigated the effects of single administration of Korean earthworm(Lamnodrilus gotai Hatai) juice (KEJ) on blood pressure and spontaneous motor activity in spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats. We report that KEJ lowered blood pressure and spontaneous motor activity in SHR.
Validation of Free-Vortex Embedded CAA Method for Airfoil Vortex Interaction
Wie, Seong-Yong,Lee, Duck-Joo The Acoustical Society of Korea 2006 韓國音響學會誌 Vol.25 No.e2
Blade-vortex interaction (BVI) is one of the most important phenomena in rotor flow since it causes undesirable intense vibration and noise. Since three dimensional Euler or Navier-Stokes solutions to BVI require very high computational cost, BVI has been approximated by airfoil-vortex interaction (AVI) in chordwise planes. To describe more realistic situations with AVI, three dimensional vortex informations such as position, core size and strength are embedded artificially to Computational Aeroacoustics (CAA) calculation at each computational time step. To implement this requirement, in this paper, a technique called free vortex embedded method was used. And the solution by this method was compared with the solution by conventional method for interaction between freely convected vortex and airfoil. For the application to three dimensional free vortex embedded CAA, two dimensional free vortex embedded CAA method was validated in advance.