• Structural Engineering and Mechanics
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• 제42권5호
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• pp.715-728
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• 2012

This paper deals with determining the fundamental frequency of tall buildings that consist of framed tube, shear core, belt truss and outrigger systems in which the framed tube and shear core vary in size along the height of the structure. The effect of belt truss and outrigger system is modeled as a concentrated rotational linear spring at the belt truss and outrigger system location. Many cantilevered tall structures can be treated as cantilevered beams with variable cross-section in free vibration analysis. In this paper, the continuous approach, in which a tall building is replaced by an idealized cantilever continuum representing the structural characteristics, is employed and by using energy method and Hamilton's variational principle, the governing equation for free vibration of tall building with variable distributed mass and stiffness is obtained. The general solution of governing equation is obtained by making appropriate selection for mass and stiffness distribution functions. By applying the separation of variables method for time and space, the governing partial differential equation of motion is reduced to an ordinary differential equation with variable coefficients with the assumption that the transverse displacement is harmonic. A power-series solution representing the mode shape function of tall building is used. Applying boundary conditions yields the boundary value problem; the frequency equation is established and solved through a numerical process to determine the natural frequencies. Computer program has been developed in Matlab (R2009b, Version 7.9.0.529, Mathworks Inc., California, USA). A numerical example has been solved to demonstrate the reliability of this method. The results of the proposed mathematical model give a good understanding of the structure's dynamic characteristics; it is easy to use, yet reasonably accurate and suitable for quick evaluations during the preliminary design stages.

• 한국환경교육학회지:환경교육
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• 제19권3호
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• pp.67-79
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• 2006

Education for Sustainable Development(ESD) is inclined to become popular topics in EE related debates, almost similar to populism, with declaration of UNESCO's Decade OF ESD (DESD). However we can't avoid that development in ESD practically means economic linear progress. Basically UN's declaration is to accomplish worldly task on human civilization, social & environmental problems, including ESSD. ESD is also important means for practicing ESSD, which has proved to be failure since Brutrant Report, owing to uncertain recognition of sustainability which should be something figured out by their surrounding circumstance or the conditions following its community culture, all same around the world. In this circumstance, we need certain identification on ESD globally recognized, no matter with the developing level of economy. But sustainability is usually managed or controlled by economically powered countries, by improving relatively under-development countries's economic conditions for equity. They believe under-development countries's env. problems can't be resolved without securing of economic equity. Under-development countries's economic equity can be come true ? even by another economic super powers. It really means just controlling or management by them. These all controlling process can't secure under-development countries's sustainability. Because it is not something just controlled, characterized as growing up by self-supporting system of ethnic or regional communities. So identification of sustainability in here is , not . Following its identification, we should discuss ESD, and furthermore for real ESD, there is powerful need to change it into ESE (Education for Sustainability & its Economy) to reflect this co-conceptional approach to ESD. And also we need to distinguish the educational contents boundaries among ESD and EE for this. Basically existing EE has been dealing with pollution-oriented or its related social comprehensive subjects, so it seems that EE is not familiar and harmony with ESD contents, however in alternative case I propose in this paper, changing into ESE, it could include almost all of ESD subjects, furthermore practically EE might be same with ESE.

• Safety and Health at Work
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• 제3권4호
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• pp.278-286
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• 2012

Objectives: Authors investigated the pattern of the rate of occupational injuries and illnesses (ROII) at the level of enterprises in order to build a network for exchange of experience and knowledge, which would contribute to workers' safety and health through safety climate of workplace. Methods: Occupational accidents were analyzed at the manufacturing work site unit. A two step clustering process for the past patterns regarding the ROII from 2001 to 2009 was investigated. The ROII patterns were categorized based on regression analysis and the patterns were further divided according to the subtle changes with Mahalanobis distance and Ward's linkage. Results: The first clustering of ROII through regression analysis showed 5 different functions; 29 work sites of the linear function, 50 sites of the quadratic function, 95 sites of the logarithm function, 62 sites of the exponential function, and 54 sites of the sine function. Fourteen clusters were created in the second clustering. There were 3 clusters in each function categorized in the first clustering except for sine function. Each cluster consisted of the work sites with similar ROII patterns, which had unique characteristics. Conclusion: The five different patterns of ROII suggest that tailored management activities should be applied to every work site. Based on these differences, the authors selected exemplary work sites and built a network to help the work sites to share information on safety climate and accident prevention measures. The causes of different patterns of ROII, building network and evaluation of this management model should be evaluated as future researches.

• International Journal of Naval Architecture and Ocean Engineering
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• 제3권4호
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• pp.274-285
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• 2011

The supercavitating vehicle is an underwater vehicle that is surrounded almost completely by a supercavity to reduce hydrodynamic drag substantially. Since the cruise speed of the vehicle is much higher than that of conventional submarines, the drag force is huge and a buckling may occur. The buckling phenomenon is analyzed in this study through static and dynamic approaches. Critical buckling load and pressure as well as buckling mode shapes are calculated using static buckling analysis and a stability map is obtained from dynamic buckling analysis. When the finite element method (FEM) is used for the buckling analysis, the solver requires a linear static solver and an eigenvalue solver. In this study, these two solvers are integrated and a consolidated buckling analysis module is constructed. Furthermore, Particle Swarm Optimization (PSO) algorithm is combined in the buckling analysis module to perform a design optimization computation of a simplified supercavitating vehicle. The simplified configuration includes cylindrical shell structure with three stiffeners. The target for the design optimization process is to minimize total weight while maintaining the given structure buckling-free.

• International Journal of Naval Architecture and Ocean Engineering
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• 제5권3호
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• pp.333-347
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• 2013

The present study numerically models the interaction between a regular wave and the roll motion of a rectangular floating structure. In order to simulate two-dimensional incompressible viscous two-phase flow in a numerical wave tank with the rectangular floating structure, the present study used the volume of fluid method based on the finite volume method. The sliding mesh technique is adopted to handle the motion of the rectangular floating structure induced by fluid-structure interaction. The effect of the wave period on the flow, roll motion and forces acting on the structure is examined by considering three different wave periods. The time variations of the wave height and the roll motion of the rectangular structure are in good agreement with experimental results for all wave periods. The present response amplitude operator is in good agreement with experimental results with the linear potential theory. The present numerical results effectively represent the entire process of vortex generation and evolution described by the experimental results. The longer wave period showed a different mechanism of the vortex evolution near each bottom corner of the structure compared to cases of shorter wave periods. In addition, the x-directional and z-directional forces acting on the structure are analyzed.

• 한국광학회지
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• 제20권4호
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• pp.241-248
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• 2009

액정 디스플레이에서 시야각 향상을 위해 사용하는 보상판과 편광판을 접합한 복합판의 광축 틀어짐 오차와 보상판의 $R_{in}$(in-plane retardation), $R_{th}$(out-of-plane retardation)를 동시에 결정하는 새로운 방법을 제시하였다. 보상판은 광축이 임의의 기울임각과 방위각을 갖는 o-판으로 하였으며, 확장된 존스 행렬법에 기반한 광학모델을 도입하여 복합판의 편광특성을 분석하였다. 입사각 0도와 50도에서 시료의 방위각을 360도 회전시키며 투과된 빛의 편광상태를 각각 계산한 후, 타원법의 모델링 분석기법을 적용하여 광축 틀어짐과 복합판의 기울임각과 방위각들을 역방계산하였다. 이 방법은 편광판과 보상판을 접합한 후에도 복합판의 성능평가를 할 수 있어 제조공정단계를 줄여 제조 원가를 절감하는데 기여할 수 있을 것으로 기대된다.

• Archives of Pharmacal Research
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• 제28권3호
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• pp.330-334
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• 2005

The effect of a new hepatoprotective agent, YH-439, on the hepatobiliary transport of a model organic cation (OC), TBuMA (tributylmethylammonium), was investigated. The area under the plasma concentration-time curve (AUC) from time zero to 4 h following iv administration of TBuMA (6.6 $\mu$mol/kg) was increased significantly when YH-439 in corn oil (300 mg/kg) was orally administered to rats 24 h prior to the experiment. Nevertheless, the cumulative biliary excretion of TBuMA remained unchanged. As a consequence, the apparent biliary clearance ($CL_b$) of TBuMA was decreased significantly as a result of YH-439 pretreatment, consistent with the fact that the in vivo excretion clearance of TBuMA across the canalicular membrane ($CL_{exc}$) was not changed by the pretreatment. The in vitro uptake of TBuMA into isolated hepatocytes was decreased by one half by the pretreatment, owing to a decrease in the apparent V$_{max}$ and $CL_{linear}$, but the $K_m$ for the process remained constant. Most interestingly, however, the sinusoidal uptake of glucose, a nutrient, into hepatocytes was not influenced by the pretreatment, suggesting the YH-439 pretreatment specifically impaired the sinusoidal uptake of OCs. Thus, the OC-specific inhibition of hepatic uptake, without influencing the uptake of glucose, a nutrient, appeared to be associated with the hepatoprotective activity of YH-439.

• 약학회지
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• 제60권3호
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• pp.112-117
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• 2016

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the determination of caffeine in forensic aqueous sample. The centrifuged sample ($100{\mu}l$) was diluted 50-fold with distilled water. The diluted sample ($400{\mu}l$) was then diluted further with $200{\mu}l$ of 0.1% formic acid solution and $400{\mu}l$ of acetonitrile containing 500 ng of caffeine-(3-methyl-$^{13}C_3$) prior to LC-MS/MS analysis. The mobile phase was composed of 0.1% formic acid in distilled water (A) and acetonitrile (B). Chromatographic separation was performed by using a Zorbax SB-C18 ($100mm{\times}2.1mm$ i.d., $3.5{\mu}m$) column and caffeine was eluted within 1.1 min. Linear least-squares regression with a 1/x weighting factor was used to generate a calibration curve with the coefficients of determination ($r^2=0.9983$). The lower limit of quantification was $25ng/ml$ for the analyte. The process efficiency was 98.6~100.1%. Intra- and inter-day precisions were not more than 2.1% and 1.7%, while intra- and inter-day accuracies were ranged from -6.8 to 4.5%, respectively. The suitability of the method was examined by analyzing unknown forensic aqueous samples.

• Bulletin of the Korean Chemical Society
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• 제34권11호
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• pp.3199-3205
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• 2013

The inclusion behavior of sulfobutylether-${\beta}$-cyclodextrin (SBE-${\beta}$-CD) with perphenazine (PPH) was first studied by flow injection (FI)-chemiluminescence (CL) analysis with proposed $lg[(I_0-I_s)/I_s]=lgK_{P-CD}+nlg[C_{PPH}]$ model and molecular docking. Results showed that a 1:1 complex of SBE-${\beta}$-CD/PPH could online form, with the formation constant $K_{P-CD}$ of $2.57{\times}10^7Lmol^{-1}$ at 298 K. The thermodynamic parameters showed that the inclusion behavior of SBE-${\beta}$-CD/PPH was a spontaneous process by hydrophobic interaction. The molecular docking results revealed PPH entered into the larger cavity of SBE-${\beta}$-CD with two hydrogen bonds. Based on the linear relationship of the decrement of luminol/SBE-${\beta}$-CD/PPH CL intensity against the logarithm of PPH concentration ranging from 0.03 to 30.0 ng $mL^{-1}$, the present FI-CL analysis using luminol/SBE-${\beta}$-CD/PPH system was successfully applied to PPH determination in biological fluids and tablets with recoveries from 94.5 to 105.6% and RSDs less than 2.6% (n = 5).

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2011년도 정기 학술대회
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• pp.531-538
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• 2011

멤브레인형 LNG 탱크의 구조적 안전성을 확보하기 위해서는 슬로싱에 의한 작용 압력과 구조응답을 정확히 평가할 수 있어야 한다. 탱크 방열구조에 작용하는 슬로싱 충격하중은 매우 불규칙적이며 이로 인한 구조 응답 역시 유탄성 거동을 포함하는 매우 복잡한 물리 현상이기 때문에 최신의 이론적 실험적 접근 방법을 동원하더라도 정확한 평가가 어렵다. 본 연구에서는 실험이나 수치해석으로부터 얻어진 슬로싱 압력 시계열을 이용하여 탱크 방열 구조의 구조응답을 간편하게 해석할 수 있는 방안을 제안하였다. 이 간이 해석법은 기본적인 삼각형 impulse 형태의 충격 압력에 대한 구조응답을 시간영역에서 과도응답해석법으로 계산한 후, 이렇게 구해진 구조물의 삼각형 응답함수를 조합하여 임의 형상의 압력 시계열에 대한 구조 응답을 구하는 방식이다. 여러 가지 예제 해석을 통하여 제안된 해석법의 타당성을 검토하였고, 이를 이용하여 실제 모형실험에서 얻어진 압력시계열을 바탕으로 구조응답을 계산하고 그 결과를 고찰하였다.