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As Cr-Mo-V steels have excellent mechanical and creep properties at elevated temperatures, they are extensively used in power plants. However, the steam turbine components are supposed to have suffered material degradation during long-term service at elevated tenperatures. Many efforts have been made to assess the safety and residual life of these components by means of non-destructive methods such as plastic replication, hardness and electric resistance techniques. Recently, a parameter correlating hardness changes during long-term heating to those during creep was introduced and it was named 'G parameter'. The electric resistivity as well as hardness are affected by damage accumulation, but there have been no efforts to correlate G parameter to resistivity changes. In this study, relationship between G parameter and changes in electric resistivity was investigated using artificially aged Cr-Mo-V steel. It is well understood that G parameter can be applied to electric resistance techmique.
Information of change of hardness values during applying load is needed often to control the quality of metal products efficiently, but the relation between applied stress and hardness has not been established. In this paper the theoretical relation between the rebound hardness and stress was examined briefly and the experiment was performed with some materials. Materials used in test were mild steel(SB41), 7-3 brass and copper, which were widely used in the commercial plants. Hardness was measured during stress applied using the Equo-Tip hardness tester as a kind of rebound hardness tester. Hardness values decreased as tensile stress increased, the decreasing rate was effected by the Young's modulus of each material, and the rebound hardness values showed linear relationship with the applied stress in elastic region.
타조는 주조류(走鳥類)에 속하는 동물로써 오래 전부터 아프리카에서 사육되어 온 아프리카 원산조(鳥)이다. 그러나 현재는 타조 사육이 부가가치가 높은 산업으로 많은 나라에서 각광을 받고 있다. 통계에 따르면 성타조의 키는 2.5m에 이르며 체중도 120㎏에 달하는 것으로 보고된 바 있다. 이 새는 시속 70㎞로 달릴수 있는 빠른 새이며 60∼70세까지 살 수 있고 마리수가 많은 상업적 사육여건에서도 20년이상을 산란할 수 있는 것으로 능력을 높이 평가받고 있다. 성성숙은 대개 암컷은 생후 약 20 개월 수컷은 약 28개월에 이루어지는 것으로 보고되어 있다. 암컷 한마리는 대개 1년 20∼120개의 알(평균 40개)을 산란하며 산란시기는 4∼9월까지로 되어 있다. 부화는 대개 42일이 필요하며 앞의 무게는 개당 1.4∼1.9㎏ 정도 되는 것으로 보고되어 있다(큰 것은 2.3㎏에 이른다고 한다). 1년에 암수 한쌍에서 생산될 수 있는 병아리는 대개 15∼20수 정도이다. 생산할 수 있는 고기 양은 생체중 100㎏당 30㎏ 또는 ¼정도로 보고 있다. 단 성타조 1마리가 1년 생산할 수 있는 깃털의 양은 400g이다. 그리고 타조는 특히 운동을 좋아하는 동물이어서 넓은 운동장이 필요하다. 타조 질병에 대한 연구는 아직도 많지 않아서 앞으로 이 분야 연구는 더 되어야 한다. The ostrich is a member of the ratite family and flightless birds. It is a native bird of Africa and raised there from olden times. However, ostrich farming is highly profitable industry in many country nowadays. Statistics showed that adult ostrich may attain a height of 2.5 meters, and a body weight of 120∼140㎏ (The biggest ones are close to 250㎏ body weight). This bird can run over 70㎞ per hour and these bird's lifespan is known to be 60∼70 years, with an estimated breeding life of over 20 years under the intensive commercial conditions. Osriches mature when hens and cock are around twenty months-old and 25 to 28 months-old, respectively. A hen can lay 20∼120 eggs (average 40 eggs) per year with the breeding season of April through September. The length of hatching is an verage of 42 days. The weight of egg is 1.4∼1.9㎏ (The biggest ones are up to 2.3㎏). Usually 15 to 20 chicks are hatched from a pair of adult ostrich per year. The quantity of meat which can be produced is about 30㎏ per 100㎏ live weight or quarter of body weight. It is reported that 450g of feathers can be harvested from one bird per year. Ostriches are exceptional animal which like to run in broad playgrounds. Little is still known about the diseases of ostriches but this will be an important area of future research.
For the accurate measurements of hardness in a material, it is necessary to have a thorough understanding of the effects of test variables on the accuracy of hardness value. For the rebound hardness test, major test variables are the radius of hammer ball tip, type of backing materials, size and roughness of the specimen. In this study, effects of these variables on Equo-Tip hardness value were investigated. Hardness measurements were carried out using WC balls with various sizes of worn-ot zone. The sample materials chosen for the experiments were commercial standard hardness blocks and SM45C steel bars subjected to either normalization or quench and temper treatments. As backing materials, aluminum, steel and rubber plates were used in all the experiments. Experimental results show that for the accurate measurements of Equo-tip hardness, it is necessary to use the hammer ball with a worn-out zone parameter of less than 0.23, and the recommended minimum thickness and width of the specimen are 25㎜ and 70㎜, respectively. Further for the surface preparation, the specimens need to be polished with an emery paper of No. 400 or finer, and for the backing matrials, it is recommended to use steels or rubbers.
<P>The bone morphogenetic protein (BMP) ligand Glass bottom boat (Gbb) acts as a retrograde growth signal at the Drosophila neuromuscular junction (NMJ). Endocytic regulation of presynaptic BMP receptors has been proposed to attenuate retrograde BMP signaling. However, it remains unknown whether the Gbb signal is also regulated by postsynaptic mechanisms. Here, we provide evidence that Drosophila Cdc42-interacting protein 4 (dCIP4) functions postsynaptically to inhibit synaptic growth. dCIP4 is localized postsynaptically at NMJs. dcip4 mutations lead to synaptic overgrowth and increased presynaptic phosphorylated mothers against decapentaplegic (Mad) levels, and these defects are rescued by muscle-specific expression of dCIP4. Biochemical and genetic analyses demonstrate that dCIP4 acts downstream of Cdc42 to activate the postsynaptic Wsp-Arp2/3 pathway. We also show that BMP signaling is necessary for synaptic overgrowth in larvae lacking postsynaptic dcip4 or wsp. Finally, dCIP4 and Wsp inhibit Gbb secretion. Thus, we propose that dCIP4 restrains synaptic growth by inhibiting postsynaptic Gbb secretion through the Wsp-Arp2/3 pathway.</P>
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본 연구의 목적은 교정환자에서 측두하악관절 원판 변위(disk displacement of TMJ)가 치열 및 안면부 비대칭과 관련이 있는가를 밝히는 것이다. 2000년 1월부터 2002년 4월까지 서울대학교병원 치과교정과에 내원한 환자 중 18∼39세 (평균 23.3세)인 여성 60명의 측두하악관절 자기공명영상(MRI)을 기초로 하여, 양측 TMJ가 모두 정상인 군 (21명), 우측 TMJ에만 원판 변위가 있는 군 (6명), 좌측 TMJ에만 원판 변위가 있는 군 (9명), 양측 TMJ에 모두 원판 변위가 있는 군 (24명)으로 나누고, 교정치료 전의 후전방 두부방사선계측사진과 교정진단모형을 계측하였다. 후전방 두부방사선계측사진의 분석에는 좌우 Latero-Orbitale(Lo)를 연결한 선분을 수평기준선으로 하고, 이 선분을 수직 이등분하는 직선을 수직기준선으로 하였다. 각 계측항목에 대해 일원배치분산분석(one-way ANOVA)과 후처치로서 다중비교분석(Bonferroni's multiple comparison test)을 시행하여, 다음과 같은 결과를 얻었다. 1. 교정진단모형에서 전치돌출도, 우측구치관계, 좌측구치관계가 각 군 사이에 유의한 차이를 보였다. 2. 후전방 두부방사선계측사진에서 하악제1대구치와 Ag의 수직적 위치의 좌우 차이가 각 군 사이에 유의한 차이를 보였다. 3. 측두하악관절 원판 변위가 편측에 존재하면, 이환측의 하악지 길이가 비이환측에 비해 짧았으며 좌우 Ag의 수직적 높이에도 차이를 보였다. 이상의 결과를 통하여, 측두하악관절 원판 변위의 편재와 치열 및 안면부 비대칭의 발현 양상은 관계가 있다고 판단된다. The purpose of this study was to determine whether there is an association between disk displacement of the Temporomandilbular Joint (TM) and dentofacia asymmetry in orthodontic patients. The subjects consisted of 60 female orthodontic oatients between the ages if 18 and 38 years(mean age 23.3 years) who had visited the Department of Orthodontics at Seoul National University Dental Hospital from January 2000 to April 2002. On the basis of magnetic resonance imaging (MRI) of their bilateral TMJs, the subjects were divided into four groups; bilateral normal group (twenty-onepersons); disk displacement of right TMJ group (six persons); disk displacement of left TMJ group (nine persons); and disk displacement of both TMJs group (twenty-four persons). Postero-anterior (PA) cephalograms and diagnostic models which had been taken before orthodontic treatment were measured. In the linear measurements, a line connections the right and left Latero-Orbitale (Lo) represented the horizontal reference line (H). The vertical reference line (V) was constructed as a line bisecting and running perpendicular to H. One-way analysis of variance (ANOVA) was used to test whether the mean values of measurements between groups were significantly different. In addition, Bonferroni's multiple comparison test was performed at a level of 0.05. The results were as follows : 1. In the diagnostic model analysis, right molar relationship, and left molar relationship were significantly different among the four groups. 2. In the PA cephalometric analysis, differences in the right and left vertical position of the lower first molar and Ag were significantly dissimilar among the four groups. 3. If the disk displacement of TMJ was present on one side, the ipsilateral ramus was shorter, resulting in asymmetry in the vertical position of Ag. This study indicated that dentofacial asymmetry might be related to the disk displacement of TMJ.
<P>This study investigated the relationship between calculated immature granulocyte (IG) counts and the severity of sepsis. Coagulation parameters, fibrinolytic indices, bacterial isolation rates in blood cultures, and mortality were observed in 237 patients with suspected sepsis. The difference in leukocyte subfractions (delta neutrophil index; DN) identified by a cytochemical myeloperoxidase reaction and by a nuclear lobularity assay was determined with a blood cell analyzer (ADVIA 120, Siemens, Inc.). DN was strongly correlated with manual IG counts (r = 0.75, p <0.05). Patients with high DN (>40%) averaged 40% lower in platelet count, 26% prolongation of prothrombin time (PT), and 35% diminution of antithrombin III (AT III) activity, vs those with low DN (5-20%). Overt disseminated intravascular coagulation was more prevalent as the DN increased, and reached a peak in patients with DN >40%. DN values were closely associated with PT (r = 0.35, p <0.05), AT III activity (r = -0.36, p <0.05), and platelet count (r = -0.27, p <0.05). Positive blood culture rate averaged 3.5-fold higher in patients with DN >40% vs the subgroup with low DN of 5-10%. The mortality rate of patients with DN >40% markedly exceeded the mortality rate of patients with DN of 5-10% (79% vs 15%, p <0.05). Thus, DN has implications for the severity of sepsis and may be valuable to assess the prognosis of patients with suspected sepsis.</P>
<P>This study proposes a new set-based design approach for preliminary engineering design that intrinsically contains various sources of uncertainties. The goal is to achieve design flexibility and robustness while capturing designer's preference. The proposed design approach includes three computational methods: (1) set representation method to specify the varying degree of desirability of a ranged set of design solutions and performance requirements, thereby enabling the manipulation of uncertain design solutions and requirements based on designer's preference structure; (2) set propagation method to obtain performance possibilities achievable by uncertain design solutions, thus exploring a broader design possibilities; (3) set narrowing method to generate a ranged set of feasible solutions (i.e., robust and flexible solution set) instead of single point solution that satisfies changing sets of performance requirements by eliminating infeasible and inferior subsets of solutions, thus allowing designs to be readily adapted to changing conditions. Finally, the proposed design approach is illustrated with a successful implementation of real industrial design problem (i.e., vehicle side-door structure design) in the simulation-based design environment.</P>
<P>Retrograde bone morphogenetic protein signaling mediated by the Glass bottom boat (Gbb) ligand modulates structural and functional synaptogenesis at the <I>Drosophila melanogaster</I> neuromuscular junction. However, the molecular mechanisms regulating postsynaptic Gbb release are poorly understood. In this study, we show that <I>Drosophila</I> Rich (dRich), a conserved Cdc42-selective guanosine triphosphatase–activating protein (GAP), inhibits the Cdc42–Wsp pathway to stimulate postsynaptic Gbb release. Loss of dRich causes synaptic undergrowth and strongly impairs neurotransmitter release. These presynaptic defects are rescued by targeted postsynaptic expression of wild-type dRich but not a GAP-deficient mutant. dRich inhibits the postsynaptic localization of the Cdc42 effector Wsp (<I>Drosophila</I> orthologue of mammalian Wiskott-Aldrich syndrome protein, WASp), and manifestation of synaptogenesis defects in <I>drich</I> mutants requires Wsp signaling. In addition, dRich regulates postsynaptic organization independently of Cdc42. Importantly, dRich increases Gbb release and elevates presynaptic phosphorylated Mad levels. We propose that dRich coordinates the Gbb-dependent modulation of synaptic growth and function with postsynaptic development.</P>