• 대한기계학회논문집
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• 제10권3호
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• pp.427-431
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• 1986

3점 굽힘 시험편, 중앙균열 인장 시험편, 콤팩트 인장 시험편에 대한 J적분식을 하나의 일반화된 형태로 유도한다. 이 일반식은 Eftis와 Liebowitz에 의해 제안된 하중과 하중점 변위 사이의 관계와 Sumpter에 의한 탄성과 소성성분 J적분의 중첩개념을 이용함으로써 유도된다. 일반식에 포함된 .eta.계수를 위 3가지 시험편에 대해서 결정한다. 위 3가지 시험편에 대한 J적분의 최종식은 하중과 하중점 변위곡선 아래의 면적을 측정하지 않아도 되는 형태로 나타난다. 본 연구의 결과식은 Landes등에 의한 실험치와 비교하여 매우 잘 일치함을 보인다.

• 한국태양에너지학회 논문집
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• 제26권3호
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• pp.71-78
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• 2006

Thermodynamic irreversibility analysis of an air-to-water heat pump system is analyzed in this study. This analysis shows the distribution of irreversibilities(true losses in thermodynamic sense) through the system components and informs us of a potential improvements with the irreversibility factor decreases. The results show that the largest irreversibilities occur in the motor-compressor unit. The remaining irreversibilities are distributed relatively uniformly through the other parts including utilization system. The increase of performance can be attained through either the improvement of adiabatic efficiency of motor-compressor unit(${\eta}_{mc}$) or the reduction of temperature difference(${\Delta}T$). With the decrease of utilization temperature($T_u$) COPH also increases but the exergetic efficiency decreases. The increase of COPH of about 0.05 can be accomplished with 1K decrease of ${\Delta}T$ or $T_u$.

• Journal of applied mathematics & informatics
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• 제27권1_2호
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• pp.175-182
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• 2009

Microscopic imaging system often requires the algorithm to adjust location of camera lenses automatically in machine level. An effort to detect the best focal point is naturally interpreted as a mathematical inverse problem [1]. Following Wiener's point of view [2], we interpret the focus level of images as the quantified factor appeared in image degradation model: g = $f{\ast}H+{\eta}$, a standard mathematical model for understanding signal or image degradation process [3]. In this paper we propose a simple, very fast and robust method to compare the degradation parameters among the multiple images given by introducing outlier analysis of histogram.

• Structural Engineering and Mechanics
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• 제24권1호
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• pp.91-105
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• 2006

In this paper, post-earthquake capacity evaluation method of reinforced concrete buildings was studied. Substructure pseudo-dynamic test and static loading test of first story column in a four-story R/C building was carried out in order to investigate the validity of the evaluation method proposed in the Damage Assessment Guideline (JBDPA 2001). In pseudo-dynamic test, different levels of damage were induced in the specimens by pre-loading, and input levels of seismic motion, at which the specimens reached to the ultimate stage, were examined. From the experimental result, no significant difference in damage levels such as residual crack width between the specimens under static and pseudo-dynamic loading was found. It is shown that the seismic capacity reduction factors ${\eta}$ can provide a reasonable estimation of post-earthquake seismic capacity of R/C buildings suffered earthquakes.

• Bulletin of the Korean Chemical Society
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• 제31권1호
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• pp.125-132
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• 2010

Three organic sensitizers, JK-128, JK-129, and JK-130 containing quinoline unit are designed and synthesized. Under standard global AM 1.5 solar condition, the JK-130 sensitized solar cell gave a short circuit photocurrent density of 11.52 mA $cm^{-2}$, an open circuit voltage of 0.70 V, and a fill factor of 0.75, corresponding to an overall conversion efficiency of 6.07%. We found that the $\eta$ of JK-130 was higher than those of other two cells due to the higher photocurrent. The higher $J_{sc}$ value is attributed to the broad and intense absorption spectrum of JK-130.

• 자연과학논문집
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• 제14권2호
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• pp.115-131
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• 2004

The purpose of this study was to investigate the differences of sports involvement and consumer attitude on fashion advertisement using sports star models(CAATTM) according to demographics and to investigate the effect of sports involvement to CAATTM. The subjects selected for final analysis were 398 adults living in Daejeon. The statistics used for analysis included factor analysis, ANOVA, multiple range test, regression, $Cronbach'\alpha$, and frequency. The results were as follow: 1. Sports Involvement was divided Cognitive Sports Involvement(CSI) and Emotional Sports Involvement(ESI). The CSI and ESI were different according to sex. And CSI was different according to age, education level and marriage status. 2. CATTM was divided into three factors: Emotional Attitude(EA), Cogitive Attitude(CA), and Ethical Attitude(ETA). CA was different according to sex, age, income, and marriage status. 3. The sports involvement affected CAATTM. People who were high in CSI and ESI showed high attitude in EA and CA.

• Molecules and Cells
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• 제38권5호
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• pp.409-415
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• 2015

Low-barrier hydrogen bonds (LBHBs) have been proposed to have important influences on the enormous reaction rate increases achieved by many enzymes. ${\Delta}^5$-3-ketosteroi isomerase (KSI) catalyzes the allylic isomerization of ${\Delta}^5$-3-ketosteroid to its conjugated ${\Delta}^4$-isomers at a rate that approache the diffusion limit. Tyr14, a catalytic residue of KSI, has been hypothesized to form an LBHB with the oxyanion of a dienolate steroid intermediate generated during the catalysis. The unusual chemical shift of a proton at 16.8 ppm in the nuclear magnetic resonance spectrum has been attributed to an LBHB between Tyr14 $O{\eta}$ and C3-O of equilenin an intermediate analogue, in the active site of D38N KSI. This shift in the spectrum was not observed in Y30F/Y55F/D38N and Y30F/Y55F/Y115F/D38N mutant KSIs when each mutant was complexed with equilenin, suggesting that Tyr14 could not form LBHB with the intermediate analogue in these mutant KSIs. The crystal structure of Y30F/Y55F/Y115F/D38N-equilenin complex revealed that the distance between Tyr14 $O{\eta}$ and C3-O of the bound steroi was within a direct hydrogen bond. The conversion of LBHB to an ordinary hydrogen bond in the mutant KSI reduced the binding affinity for the steroid inhibitors by a factor of 8.1-11. In addition, the absence of LBHB reduced the catalytic activity by only a factor of 1.7-2. These results suggest that the amount of stabilization energy of the reaction intermediate provided by LBHB is small compared with that provided by an ordinary hydrogen bond in KSI.

• 대한화학회지
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• 제55권4호
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• pp.594-602
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• 2011

4[N-(furfural)amino]antipyrine semicarbazone(FFAAPS)와 질산 란탄(III)이 형성하는 배위화합물의 입체화학에 미치는 ${\alpha}$-, ${\beta}$- 및 ${\gamma}$-picolines의 영향을 연구하였다. 이들 배위화합물의 일반적 조성은 [Ln(FFAAPS)$(NO_3)_3$Pic] (Ln=La, Pr, Nd, Sm, Gd, Tb, Dy 또는 Ho 및 Pic=${\alpha}$-, ${\beta}$- or ${\gamma}$-picolines)이다. 모든 배위화합물은 원소분석, 분자량, 몰전기전도도, 자기수자율, 적외선 및 자외선 스펙트럼으로 특성을 조사하였다. 적외선 연구결과 FFAAPS는 N, N, O 주개를 갖는 중성 삼배위 리간드로 행동하는 반면, ${\alpha}$-, ${\beta}$- 또는 ${\gamma}$-picoline는 헤테로 N-원자를 통하여 란탄(III) 이온에 배위된다. 질산 음이온은 이들 화합물에서 이배위로 결합한다. 자외선 스펙트럼 결과로부터 전자구름 퍼짐 효과(${\beta}$), covalence factor($b^{1/2}$), Sinha parameter (${\delta}%$) 및 covalence angular overlap parameter(${\eta}$)를 계산하였다. 이들 착물의 열적성질을 열무게 분석법에 의해 연구하였다. 본 화합물에 있어서 란탄(III)의 배위수는 10으로 조사되었다. 기본 리간드인 FFAAPS와 착물의 항박테리아 선별조사 결과, 이들 착물은 중간 정도의 항박테리아 활성을 보였다.

• 대한기계학회논문집
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• 제19권4호
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• pp.929-940
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• 1995

The fatigue strength and fracture topography in the friction welded interface of high speed steel (HSS-Co) to SM55C carbon steel have been investigated through the fatigue test, SEM fractograph and EDS (energy dispersive spectrometer) analysis. Three kinds of specimens used in this research are the friction welded joints, HSS-Co and SM55C carbon steel with circumferential notch, saw notch and smooth, respectively. The notch sensitivity factor, .eta. of the friction welded joints is lower than that of the base materials, and that represents a superiority of the joint performance of FRW. Fracture topography of the FRW specimens with a notch showed a cleavage or brittle appearance, while that of the FRW smooth specimen appeared to be ductile. Furthermore, although fatigue crack likely initiated near the weld interface of the FRW smooth specimen, crack propagation continued into the HAZ of SM55C steel. Finally, fatigue fractures of the base materials were associated primarily with the inclusions located at the outer periphery of the specimen.

• 한국유체기계학회 논문집
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• 제10권2호
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• pp.32-40
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• 2007

The present study investigated local pressure drop in a rotating smooth square duct with turning region. The duct has a hydraulic diameter $(D_h)$ of 26.7mm and a divider wall of 6.0mm or $0.225D_h$. The distance between the tip of the divider and the outer wall of the duct is $1.0D_h$. The Reynolds number (Re) based on the hydraulic diameter is kept constant at 10,000, and the rotation number (Ro) is varied from 0.0 to 0.20. The pressure coefficient distribution $(C_p)$, the friction factor (f) and the thermal performance $({\eta})$ are presented on the leading, the trailing and the outer surfaces. It is found that the curvature of the $180^{\circ}-turn$ produces Dean vortices that cause the high pressure drop in the turning region. The duct rotation results in the pressure coefficient discrepancy between the leading and trailing surfaces. That is, the high pressure values appear on the trailing surface in the first-pass and on the leading and side surfaces in the second-pass. As the rotation number increases, the pressure discrepancy enlarges. In the fuming region, a pair of the Dean vortices in the stationary case transform into one large asymmetric vortex cell, and then the pressure drop characteristics also change.