• 한국지진공학회논문집
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• 제14권5호
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• pp.33-39
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• 2010

본 연구는 Modal Pushover Analysis(MPA)를 기반으로 비탄성 변위비(inelastic displacement ratio, $C_R$)와 붕괴 강도비(collapse strength ratio, $R_C$)를 이용한 간략한 Incremental Dynamic Analysis (IDA) 해석법을 제안해 냈다. 이 해석법은 선형 또는 비선형 동적해석 수행 없이 다자유도 시스템의 응답을 계산하기 때문에 간단하게 IDA곡선을 얻을 수 있다. 제안한 방법의 정확성은 6층, 9층, 20층의 철골 모멘트 골조를 대상으로 44개의 지진데이터를 사용하였으며 본 연구에서 제안하는 MPA를 이용한 $C_R-R_C$ IDA 해석결과와 비선형 동적해석 (Nonlinear Response History Analysis)을 통한 IDA 응답값, 그리고 각 주요모드의 비선형 동적해석을 통한 MPA-IDA 응답 값을 비교하여 타당성을 확인하였다. MPA를 이용한 $C_R-R_C$ IDA 해석법은 반복된 비선형 동적해석 과정이 없기 때문에 계산시 소요시간이 가장 작았으며 비교적 정확한 결과를 나타냈다.

• 한국해양공학회지
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• 제6권1호
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• pp.131-139
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• 1992

The understanding and appllication of fatigue crack propagation mechanism in variable amplitude loading is very important for life prediction of the air travel structures. Particularly, the retardation and arrest behavior of fatigue crack propagation by single tension overloading is essential to the understanding and appllication of fatigue crack propagation mechanism in variable amplitude loading. Numerous studies of the retardation behavior have been performed, however investigations of the arrest behavior have not been enough yet. As for the arrest behavior, Willenborg had reported that the overload shut-off ratio $[R_{so}=(K_{OL})/K_{max})_{crack arrest}]$ had been the material constant, but recently several investigators have reported that the overload shut-off ratio depends upon the stress ratio. In this study, authors have investigated the effect of stress ratio on the threshold overload shut-off ratio to generate arrest of fatigue crack growth in high tensile aluminum alloy 7075-T735 which have used in material for air travel structures, It has been $-0.4\leqqR\leqq0.4$ till now, the region of stress ratio investigated. The threshold overload shut-off ratio has decreased as stress ratio has increased in overall region of -$-0.4\leqqR\leqq0.4$ and the linearity has been seen in this material. Moreover, the experimental equation between $R_{so}$ and R has been made; The relation has been $R_{so}=-R+2.6$.

• Asian-Australasian Journal of Animal Sciences
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• 제25권3호
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• pp.325-334
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• 2012

The objective of this study was to determine the roughage to concentrate (R:C) ratio with rain tree pod meal (RPM) supplementation on in vitro fermentation using gas production technique. The experiment design was a 6${\times}$4 factorial arrangement in a CRD. Factor A was 6 levels of R:C ratio (100:0, 80:20, 60:40, 40:60, 20:80 and 0:100) and factor B was 4 levels of RPM (0, 4, 8 and 12 mg). It was found that gas kinetic, extent rate (c) was linearly increased (p<0.01) with an increasing level of concentrate while cumulative gas production (96 h) was higher in R:C of 40:60. In addition, interaction of R:C ratio and RPM level affected $NH_3-N$ and IVDMD and were highest in R:C of 0:100 with 0, 4 mg of RPM and 40:60 with 8 mg of RPM, respectively. Moreover, interaction of R:C ratio and RPM level significantly increased total volatile fatty acids and propionate concentration whereas lower acetate, acetate to propionate ratios and $CH_4$ production in R:C of 20:80 with 8 mg of RPM. Moreover, the two factors, R:C ratio and RPM level influenced the protozoal population and the percentage of methanogens in the total bacteria population. In addition, the use of real-time PCR found that a high level of concentrate in the diet remarkably decreased three cellulolytic bacteria numbers (F. succinogenes, R. flavefaciens and R. albus). Based on this study, it is suggested that the ratio of R:C at 40:60 and RPM level at 12 mg could improve ruminal fluid fermentation in terms of reducing fermentation losses, thus improving VFA profiles and ruminal ecology.

• 한국지반환경공학회 논문집
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• 제24권2호
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• pp.13-24
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• 2023

Tunnels may undergo a larger or a smaller response compared with the free-field soil. In the pseudo-static procedure, the response of the tunnel is most often characterized by a curve that relates the racking ratio (R) with the flexibility ratio (F), where R represents the ratio of the tunnel response with respect to the free-field vibration and F is the relative stiffness of the tunnel and the surrounding soil. A set of analytical and empirical curves that do not account for the depth and the aspect ratio of the tunnel are typically used in practice. In this study, a series of dynamic analyses are conducted to develop a set of F-R_m relations for use in a frame analysis method. R_m is defined as an adjusted R where the rocking mode of deformation is removed and only the racking deformation is extracted. The numerical model is validated against centrifuge test recordings. The influence of aspect ratio, buried depth of tunnel on results is investigated. The results show that R_m increases with the increase of the buried depth and the aspect ratio. The widely used F-R relations are highlighted to be different compared with the obtained results in this study. Therefore, the updated F-R_m relations with proposed equations are recommended to be used in practice design. The rocking response decreases with either the decrease of the difference of stiffness between surrounding soil and tunnel or the larger aspect ratio of the tunnel section.

• 한국방재학회 논문집
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• 제11권3호
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• pp.17-28
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• 2011

본 연구에서는 초단기 예측강우의 편의(bias) 보정을 목적으로 G/R 비의 실시간 예측에 칼만 필터를 적용하였다. 초단기 예측강우로는 MAPLE 예측강우를 사용하였고, 강우의 임계치와 누적시간에 따른 G/R 비의 특성변화를 검토하여 G/R 비 산정방법도 개선하였다. 이러한 분석을 내륙, 산악, 해안 지역에 각기 적용하여 지역적 차이가 비교될 수 있도록 하였다. 결과적으로 강우의 임계치와 누적시간의 고려를 통해 안정화된 G/R 비의 산정이 가능하였으며, 이를 이용함으로서 예측 G/R 비의 정확성이 보다 향상되었다. 예측 G/R 비로 보정된 초단기 예측강우의 정도는 지역별로 내륙지역이 가장 우수한 것으로 나타난 반면에 해안지역에서 제일 열악한 것으로 나타났다.

• Bulletin of the Korean Chemical Society
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• 제28권8호
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• pp.1317-1321
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• 2007

Arginine conjugated PAMAM dendrimer, PAMAM-R was modified with propylene oxide via hydroxylation of primary amines of arginine residues. About 49 amines were detected to be converted to amino alcohols by 1H NMR. The newly synthesized polymer, PAMAM-R-PO was able to completely retard pDNA from a charge ratio of 2. The average diameter of PAMAM-R-PO polyplex was found to be 242 nm at a charge ratio of 30. The Zeta-potential value of PAMAM-R-PO polyplex was able to reach 20-30 mV over a charge ratio of 10. PAMAM-R-PO indicated higher cell viability than unmodified PAMAM-R on HeLa and 293 cells because of its hydroxylated amines. Transfection experiments on 293 cells showed that the transfection efficiency of PAMAM-R-PO was found to be 1.5-1.9 times higher than that of PEI25kDa at a charge ratio of 30. The polymer eventually displayed about 2 times greater transfection efficiency than PAMAM-R at the same charge ratio in the absence of serum. Therefore, we concluded that the modification of primary amines of PAMAMR to amino alcohols gives positive effects such as reduced cytotoxicity and enhanced transfection efficiency on 293 cells for gene delivery potency of PAMAM-R.

• 한국수자원학회논문집
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• 제42권8호
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• pp.659-671
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• 2009

본 연구에서는 레이더 강우량 자료의 편차보정에 사용되는 G/R비의 정확도를 향상시키기 위하여 fuzzy c-means 방법을 사용한 자료의 군집화를 적용하였다. 대상 레이더자료는 광덕산 레이더기지의 자료로서 유효범위 100km이내의 자료를 대상으로 지상관측망인 기상청의 AWS(Automatic Weather System) 지점에서 관측한 자료와의 비교를 통하여 G/R비를 구하였다. G/R비를 구하는데 있어서 전체 유효범위를 대상으로 동일한 방법을 사용한 경우와 레이더 자료의 군집화를 통해서 지형적인 효과를 고려한 경우를 비교하였으며, AWS 실측강우량과 G/R비를 통한 레이더 강우량 자료의 비교를 위하여 절대상대오차와 평균제곱근오차 등을 비교분석하였다. 그 결과 전체유효범위를 대상으로 동일하게 G/R비를 적용하여 구한 레이더 강우량에 비하여 군집분석을 이용하여 지형효과를 고려한 G/R비를 적용한 레이더 강우량의 오차가 더 적게 나타났다.

• 동의생리병리학회지
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• 제28권6호
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• pp.668-673
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• 2014

Cold and Heat pattern identification(CHPI) in traditional East Asian medicine(TEAM) is one of the major indicator to distinguish characteristics of disease and to determine treatment method. Basic parameters to determine CHPI include the pulse rate, respiration rate, and pulse power. Studies to associate physiological responses of human body by cold stress(CS) with CHPI in TEAM were rarely done so far. This study aims to explore the effects of cold stress on pulse signal via a feasibility study for three subjects and investigate some indices which can reflect autonomic nerve reaction(ANR). We measured radial pulse signals and respiration signal of the investigated subjects before the CS, during the CS which continues for 5 minutes, and immediately after the CS, respectively. Finally, we analyzed the pulse rate (P), respiration rate (R), pulse power, pulse depth, and pulse rate per respiration (P/R ratio). As a result, the P/R ratio showed a consistently decreasing tendency through the CS stimulation process, while other parameters behaved more complex and in subject-specific ways. It implies that, among candidate parameters, the P/R ratio is a simple but the most probable parameter that can be used as the ANR indicator. This result is also consistent with the theory in TEAM scripts, in which the P/R ratio is predicted to be a direct indicator for the CHPI. This pilot study shows that P/R ratio can be more appropriately associated with the ANR than heart rate or respiration rate alone. Extensive studies will be necessary to verify or confirm the P/R ratio as an appropriate and well defined parameter for ANR.

• 한국조명전기설비학회지:조명전기설비
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• 제1권2호
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• pp.57-61
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• 1987

원자력 산업에서 사용되고 있는 모든 재료의 특성은 방사선조사에 의한 손상효과로 변하게 된다. 본 연구에서는 저항과 콘덴서의 직.병렬회로에서의 방사선조사에 의한 전기적 특성이 여하히 변화되는가를 연구하였다. 연구결과 얻어진 주요 결론은 다음과 같다. 1. R-C 직렬회로에서 조사선량이 $10^6[r]$까지는 임피던스변화율이 증가되다가 그 이상의 조사선량에서는 포화상태에 이르게 되는데 포화상태에서의 증가율은 1.25[%]정도이었다. 2. R-C 직렬회로에서 조사선량이 $10^6[r]$ 까지는 증가변화율이 감소되다가 그 이상의 조사선량에서는 포화상태에 이르게 되는데 감소율은 0.5[%]정도이었다. 3. R-C 병렬회로에서는 방사선량이 $10^6[r]$까지는 임피던스변화율이 증가되다가 그 이상의 방사선량에서는 포화상태에 이르게 되는데 증가율은 0.5[%]정도이었다. 4. R-C 병렬회로에서는 방사선량이 $10^6[r]$까지는 감소되다가 그 이상의 방사선량에서는 포화상태에 이르게 되는데 감소율은 1.3[%]정도이었다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1028-1029
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• 2006

We have developed a self-aligned single isolation structure (SIS) and an asymmetric single isolation structure with an image reversal photoresist to increase the aperture ratio in a passive matrix organic light emitting display (PMOLED). Compared to the conventional structure, the fabrication process is reduced by about 17% and the aperture ratio is enlarged over 4%.