• 한국축산식품학회지
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• 제37권4호
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• pp.542-551
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• 2017

The quality characteristics of velvet antlers obtained from Formosan sambar deer (Cervus unicolor Swinhoi) (SDVA), harvested from 63 to 81 d during the velvet antler growth period, were evaluated by investigating the relationships between antioxidant levels; including content, activity, and content/activity ratios, and physical properties; including shear force values, color, and Ca content. The hardness of samples from base velvet antler sections increased, and that the color of these samples tended to become reddish-yellow (redder and more yellow), suggesting that the Ca content in the base section of the sample was not ossified yet. Samples from the upper sections of velvet antler showed higher superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) content (3.91 to 1.50 mg/mL, 2.53 to 0.90 mg/mL, and 3.95 to 1.58 mg/mL, respectively) than did samples from the middle and base sections (p<0.05). The activity and content/activity ratios of GPX measured in the upper section were also found to be significantly greater than in the middle and base sections (p<0.05). We further observed that the content and activity of GPX was significantly and negatively correlated with Ca content, shear force values, and the content/activity ratio of this antioxidant (p<0.01). The study findings may serve as a reference index for quality evaluations of velvet antlers of Formosan sambar deer in future.

• Structural Engineering and Mechanics
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• 제54권4호
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• pp.741-754
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• 2015

This study evaluates prediction models for three EDPs (engineering demand parameters) using data from three symmetrical structures with RC walls designed according to the currently enforced Romanian seismic design code P100-1/2013. The three analyzed EDPs are: the maximum interstorey drift, the maximum top displacement and the maximum shear force at the base of the RC walls. The strong ground motions used in this study consist of three pairs of recordings from the Vrancea intermediate-depth earthquakes of 1977, 1986 and 1990, as well as two other pairs of recordings from significant earthquakes in Turkey and Greece (Erzincan and Aigion). The five pairs of recordings are rotated in a clockwise direction and the values of the EDPs are recorded. Finally, the relation between various IMs (intensity measures) of the strong ground motion records and the EDPs is studied and two prediction models for EDPs are also evaluated using the analysis of residuals.

• 한국전산구조공학회논문집
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• 제22권1호
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• pp.105-115
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• 2009

휨거동을 하는 전단벽을 대상으로 동일한 총 단면적을 갖는 1개의 전단벽과 마찰형 감쇠기로 연결된 전단벽의 내진성능을 수치해석을 통해 비교하였다. KBC 2005 설계스펙트럼을 근거로 축소 조절한 7개의 지진파를 입력하중으로 마찰형 감쇠기가 설치된 전단벽의 평균응답을 분석하였다. 마찰형 감쇠기의 중요한 설계변수인 기준 마찰력인 슬립하중은 각층의 마찰형 감쇠기 위치에 생기는 수직방향 전단력의 총합의 5, 10, 20, 30, 60, 90%값으로 하여 슬립이 특정한 층에 편중되지 않도록 하였다. SeismoSturct 프로그램을 이용해 비선형시간이력 해석을 수행하여 밑면 전단력, 에너지 소산량, 1층 벽체곡률, 최상층변위 측면에서 마찰 감쇠기의 제진성능을 분석하였다. 기준마찰력의 30%이하 수준의 총 마찰력을 갖는 마찰 감쇠기가 우수한 제진성능을 보였다.

• Wind and Structures
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• 제18권4호
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• pp.391-422
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• 2014

The high frequency force balance (HFFB) technique provides convenient measurements of integrated forces on rigid building models in terms of base bending moments and torque and/or base shear forces. These base moments or forces are then used to approximately estimate the generalized forces of building fundamental modes with mode shape corrections. This paper presents an analysis framework for coupled dynamic response of tall buildings with HFFB technique. The empirical mode shape corrections for generalized forces with coupled mode shapes are validated using measurements of synchronous pressures on a square building surface from a wind tunnel. An alternative approach for estimating the mean and background response components directly using HFFB measurements without mode shape corrections is introduced with a discussion on higher mode contributions. The uncertainty in the mode shape corrections and its influence on predicted responses of buildings with both uncoupled and coupled modal shapes are examined. Furthermore, this paper presents a comparison of aerodynamic base moment spectra with available data sets for various tall building configurations. Finally, e-technology aspects in conjunction with HFFB technique such as web-based on-line analysis framework for buildings with uncoupled mode shapes used in NALD (NatHaz Aerodynamic Loads Database) is discussed, which facilitates the use of HFFB data for preliminary design stages of tall buildings subject to wind loads.

• 국제강구조저널
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• 제18권4호
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• pp.1373-1383
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• 2018

Experimental study was conducted to investigate the seismic behavior of roof joint. Eight full-scale specimens were tested considering the effects of axial force, joint height, hole shape of base plate and edge distance of concrete on the failure mode and resistance capacity of roof joint. With the increase of axial force, the hysteretic curves were fuller. The mechanical model of roof joint change from bending to shear. With the increase of joint height, the ultimate strength of roof joint decreased. If the hole shape of base plate changed from circle to loose, the slip behavior of roof joint appeared and the ultimate strength of roof joint decreased. The damage of edge concrete may occur if the edge distance of concrete was not big enough.

• 한국지진공학회논문집
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• 제5권4호
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• pp.9-16
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• 2001

본 연구의 목적은 지진에 의한 비보강 조적조의 거동을 평가하는 것이다. 효율적인 평가를 위하여 유사동적해석법을 사용하였다. 저층의 비보강 조적조에 대하여 지진하중에 의한 지반-구조물의 상호작용에 따른 영향을 평가하기 위하여 단단한 지반에 놓여진 구조물과 연약한 지반에 좋여진 구조물을 비교하였다. 그 결과 연약한 지반위에 놓인 구조물의 층 전단력과 밑면 전단력이 상대적으로 증가하는 것으로 나타났다. 또한 현재 사용되고 있는 내진기준에 주어진 약산식에 따라 해석을 수행할 경우 연약한 지반에 놓인 건물이 경우 전단력을 과소평가 할 수 있는 것으로 나타났다.

• The Journal of Advanced Prosthodontics
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• 제1권3호
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• pp.129-135
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• 2009

STATEMENT OF PROBLEM. Zirconia-based restorations have the common technical complication of delamination, or porcelain chipping, from the zirconia core. Thus the shear bond strength between the zirconia core and the veneering porcelain requires investigation in order to facilitate the material's clinical use. PURPOSE. The purpose of this study was to evaluate the bonding strength of the porcelain veneer to the zirconia core and to other various metal alloys (high noble metal alloy and base metal alloy). MATERIAL AND METHODS. 15 rectangular ($4\times4\times9mm$) specimens each of zirconia (Cercon), base metal alloy (Tillite), high noble metal alloy (Degudent H) were fabricated for the shear bond strength test. The veneering porcelain recommended by the manufacturer for each type of material was fired to the core in thickness of 3mm. After firing, the specimens were embedded in the PTFE mold, placed on a mounting jig, and subjected to shear force in a universal testing machine. Load was applied at a crosshead speed of 0.5mm/min until fracture. The average shear strength (MPa) was analyzed with the oneway ANOVA and the Tukey's test ($\alpha$= .05). The fractured specimens were examined using SEM and EDX to determine the failure pattern. RESULTS. The mean shear strength ($\pm\;SD$) in MPa was 25.43 ($\pm\;3.12$) in the zirconia group, 35.87 ($\pm\;4.23$) in the base metal group, 38.00 ($\pm\;5.23$) in the high noble metal group. The ANOVA showed a significant difference among groups, and the Tukey' s test presented a significant difference between the zirconia group and the metal group. Microscopic examination showed that the failure primarily occurred near the interface with the residual veneering porcelain remaining on the core. CONCLUSION. There was a significant difference between the metal ceramic and zirconia ceramic group in shear bond strength. There was no significant difference between the base metal alloy and the high noble metal alloy.

• 펄프종이기술
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• 제33권3호
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• pp.9-17
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• 2001

The floc characteristics of base paper stock for coating by the retention aid system consisting of polyacrylamide (high molecular weight low charge density, HMLC) and PEI without and with anionic inorganic oxide (IO) were investigated under various shear conditions of MDDA (modified dynamic drainage analyzer). The floc size was increased with cationic electrolytes dosage whatever inorganic oxide is applied or not. The effect of inorganic oxide on the floc size showed the different result between PAM and PEI. The smaller floc was obtained by PAM without inorganic oxide, but larger floc was obtained by PAM with inorganic oxide. However, the effect of shear force was not observed. Floc formation index was decreased by the addition of cationic electrolytes with or without inorganic oxide. Floc formation index had better correlation format formation index than floc size. The relationships between wet web permeability and mat air permeability showed the significant linear correlation ($R^2$=0.97~0.98) for HML PAM and PEI. Floc formation index gave more useful information than the retention measurement when the performance of retention aids is evaluated at the laboratory before applying at the paper mill.

• Smart Structures and Systems
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• 제18권5호
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• pp.931-953
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• 2016

In this paper, the effects of mass eccentricity of superstructure as well as stiffness eccentricity of isolators on the amplification of seismic responses of base-isolated structures are investigated by using mathematical near-fault pulse models. Superstructures with 3, 6 and 9 stories and aspect ratios equal to 1, 2 and 3 are mounted on a reasonable variety of Triple Concave Friction Pendulum (TCFP) bearings considering different period and damping ratio. Three-dimensional linear superstructure mounted on nonlinear isolators are subjected to simplified pulses including fling step and forward directivity while various pulse period ($T_p$) and Peak Ground Velocity (PGV) amounts as two crucial parameters of these pulses are scrutinized. Maximum isolator displacement and base shear as well as peak superstructure acceleration and drift are selected as the main engineering demand parameters. The results indicate that the torsional intensification of different demand parameters caused by superstructure mass eccentricity is more significant than isolator stiffness eccentricity. The torsion due to mass eccentricity has intensified the base shear of asymmetric 6-story model 2.55 times comparing to symmetric one. In similar circumstances, the isolator displacement and roof acceleration are increased 49 and 116 percent respectively in the presence of mass eccentricity. Furthermore, it is demonstrated that torsional effects of mass eccentricity can force the drift to reach the allowable limit of ASCE 7 standard in the presence of forward directivity pulses.

• 한국공작기계학회논문집
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• 제16권6호
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• pp.29-36
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• 2007

The present study examined the mechanical properties of the friction welding of Ni-Cr-Mo to SM45C. Friction welding was conducted at welding conditions of 2,000 rpm, friction pressure of 100MPa, friction time of 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0 seconds, upset pressure of 150MPa, and upset time of 3.0 seconds. When the friction time was 1.6 seconds, the maximum tensile strength of the friction weld happened to be 1,020MPa, which is 120% of the base material's tensile strength(850MPa). At the same condition, the maximum shear strength was 438MPa, which is equivalent to 103% of the base material's shear strength(425MPa). At the same condition, the maximum vickers hardness was Hv490 at Ni-Cr-Mo nearby weld interface, which is higher Hv40 than condition of the friction time 0.8 seconds, and the maximum vickers hardness was Hv305 from weld interface of SM45C, which is higher Hv12 than condition of the friction time 0.8 seconds. The results of microstructure analysis show that the structures of two base materials have fined and rearranged along a column due to heating and axial force during friction, which has affected in raising hardness and tensile strength.