• 한국측량학회지
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• 제6권2호
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• pp.19-27
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• 1988

정확하고도 신속한 수평위치해석의 조정기법들이 다양하게 그동안 연구, 개발되어 왔다. 보다 정밀한 E.D.M, electronic total station등과 같은 신측정장비의 개발은 각, 거리의 측정에 있어 종래의 측량 방식에 비해 많은 이점을 제공하고 있으므로 앞으로 각과 거리를 동시에 적용하여 조정하는 기법의 활용이 기대된다. 본 연구는 복합측지망을 구성하여 각, 거리, 방위각 및 기준점 좌표 등 weight factor의 변화에 따른 조합조정기법의 특성을 삼각, 삼변측중과 비교하여 고찰한 것이다. 각 기법의 표준오차를 다양하게 비교한 결과 복합 측지망에서도 타 기법에 비해 조합조정기법의 우월성 및 적용타당성이 입증되었다.

• Ocean and Polar Research
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• 제37권1호
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• pp.1-9
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• 2015

An approach based on the combined use of a 2D shallow water model and analytical 1D long wave run-up theory is proposed which facilitates the forecasting of tsunami run-up heights in a more rapid way, compared with the statistical or empirical run-up ratio method or resorting to complicated coastal inundation models. Its application is advantageous for long-term tsunami predictions based on the modeling of many prognostic tsunami scenarios. The modeling of the Chilean tsunami on February 27, 2010 has been performed, and the estimations of run-up heights are found to be in good agreement with available observations.

• 분석과학
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• 제8권4호
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• pp.829-834
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• 1995

Whole column coldtrapping(WCC) on a fused silica capillary (FSCC)combined with GC/MS analysis was evaluated for use in the investigation of volatile organic compounds(VOCs) in indoor air. Research had indicated that a temperature of $-80^{\circ}C$ is optimal for WCC. Samples were analyzed on a $50m{\times}0.2mm$ cross-linked 5% phenylmethylsilicone fused silica column. Liquid nitrogen was used as the coolant for the peak resolution significantly. The analysis can be performed quickly and conveniently. More than 112 of VOCs were determined in the samples from three typical indoor environment including: (1) a room which had just been decorated involving building materials and paints; (2)a kitchen used for Chinese cooking, and (3) a room had tobacco smoke. The method is could be readily applied to rapid sample screening for VOCs contamination surveys or initial investigations with its valid and simple sampling and analytical technique.

• 분석과학
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• 제13권2호
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• pp.158-165
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• 2000

배연탈황설비에서 생성된 석고 슬러리 및 석고의 순도와 불순물의 정량분석은 시운전중인 탈황설비의 성능시험시 최적의 탈황공정을 모색하는 데 유용한 자료를 제공할 뿐만 아니라 생성된 석고는 시멘트나 석고 보드 등으로 사용될 수 있으므로 품질관리의 측면에서도 매우 중요하다. 석고의 순도는 결합수분, 삼산황 및 칼슘이온의 농도를 측정한 다음 환산식에 의해서 gypsum($CaSO_4{\cdot}2H_2O$)의 형태로 변환할 수 있다. 성능시험시 시료의 수가 상당히 많으므로, 좀 더 간편하면서도 정확한 분석방법의 확립을 위해 여러가지 비교실험을 실시한 결과, 열분석을 통하여 결합수분을 측정하는 방법이 1시간 이내에 분석이 완료된다는 장점 외에 재현성 또한 아주 우수하였다. 그 외 실리카를 포함한 각종 석고의 불순물의 분석은 산으로 처리하는 방법과 융제를 사용한 용융법을 비교한 결과, 용융법이 훨씬 간편하고 정확한 결과를 나타내었다. 한편 소량의 탄산 마그네슘과 탄산 칼슘의 정량을 위해 사용되는 이산화탄소 측정장치의 트랩부분을 수정하여 이산화탄소 흡수제의 역류를 막도록 하였다. 열분석을 통한 결함수분 측정, 융제를 사용한 용융법 및 이산화탄소의 정량법으로 확립된 분석 방법을 통해 석고 슬러리 및 석고의 분석은 보다 짧은 시간내에 간편하면서도 정확하게 실시될 수 있음을 확인하였다.

• 한국산업보건학회지
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• 제10권1호
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• pp.126-146
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• 2000

To develop and evaluate formaldehyde measurement method using 2,4-dinitro-phenylhydrazine (2,4-DNPH) coated sampler and gas chromatography, laboratory test and field test were conducted. Results of this study are as follows. Limit of detection(LOD) of measurement methods, HPLC-UVD, GC-NPD and GC-FID, is $0.008{\mu}g/m{\ell}$ $0.060{\mu}g/m{\ell}$, $0.472{\mu}g/m{\ell}$ respectively. Coefficiency of measurement methods, HPLC-UVD, GC-NPD and GC-FID, is 0.008, 0.009, 0.020 respectively. Desorption efficiency of sep-pak xposure aldehyde sampler and sorbent sample tube is 1.05(range : 0.99 - 1.12), 1.02(range : 0.99 - 1.06) respectively. Samples of sorbent sample tube and sep-pak xposure aldehyde sampler turned out to be stored at refrigerator, according to storage test results. Measurement methods of HPLC-UVD, GC-NPD, GC-FID, according to results of precision for the combined sampling and analytical procedure, became acceptable to OSHA evaluation standard. Field test using exposure chamber met the NIOSH overall uncertainty recommendation(less than 25%). Overall uncertainty of Sepak-HPLC(UVD), Tube-GC(NPD), Tube-GC(FID) is 11.0% - 17.0%. Consequently gas chromatography(GC-NPD, GC-FID) and high performance liquid chromatography(EPA TO-11) using 2,4-DNPH coated sampler for formaldehyde measurement turned out to be suitable to measure personal formaldehyde exposure at workplaces.

• 대한기계학회논문집
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• 제18권8호
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• pp.2005-2015
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• 1994

An analytical method based on the upper bound approach for the cup-bar axisymmetric combined extrusion is presented to determine the deformation zones as well as extrusion load and deformed geometry in the early stage. A new kiematically admissible velocity field is derived by the appropriate transformation of the original velocity field and applying the flow function approach. The derived velocity field is directly related to the boundary function for the plastically deforming zones and the parameter controlling the flow direction to the forward part or backward part. Experiments are carred out with the annealed aluminum 2024 at room temperature for the various area reductions. The workhardening effect is considered in the formulation as a function of the height ratio between the deformed billet and the orighinal billet to calculate the extrusion pressures. The theoretical predictions for the extrusion loads and deformed configuration are in good agreement with the experimental results.

• Structural Engineering and Mechanics
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• 제17권2호
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• pp.187-201
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• 2004

A shaking table test on a three-story one-bay steel frame model with metallic yield dampers and their parallel connection with oil dampers is carried out to study the dynamic characteristics and seismic performance of the energy dissipation system. It is found from the test that the combined energy dissipation system has favorable reducing vibration effects on structural displacement, and the structural peak acceleration can not evidently be reduced under small intensity seismic excitations, but in most cases the vibration reduction effect is very good under large intensity seismic excitations. Test results also show that stiffness of the energy dissipation devices should match their damping. Dynamic analysis method and mechanics models of these two dampers are proposed. In the analysis method, the force-displacement relationship of the metallic yield damper is represented by an elastic perfectly plastic model, and the behavior of the oil damper is simulated by a velocity and displacement relative model in which the contributions of the oil damper to the damping force and stiffness of the system are considered. Validity of the analytical model and the method is verified through comparison between the results of the shaking table test and numerical analysis.

• 한국터널지하공간학회 논문집
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• 제18권3호
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• pp.273-282
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• 2016

본 연구에서는 기존에 제안된 8가지의 이론식과 3차원 수치해석으로 막장압을 산정하여 비교 검토하였다. 일반적으로 국내 쉴드TBM의 막장압 산정은 이론식과 경험에 따른 방법으로 검토되고 있는 실정이나 복잡한 지층조건, 특수한 지반조건을 통과하는 구간에 대해서는 수치해석을 병행하고 있다. 따라서 이론식으로 산정된 막장압과 수치해석 프로그램에서 산정되는 막장압의 상관관계를 확인하여 막장압의 신뢰성 있는 검토방법을 찾고자 하였다. 막장압 산정시 이론식과 수치해석 모두 사질토와 점성토 지반조건에서 동일하게 검토하였으며, 이론식은 기존에 제안된 식을 사용하였고 수치해석은 쉴드터널의 시공과정을 모사한 3차원 해석을 수행하였다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 추계학술발표회
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• pp.458-461
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• 2003

Solid-phase microextraction (SPME) and gas chromatography/headspace techniques(HS) and flame ionization detection (GC/FID) have been combined for determination of very polar compounds in water, including the widely used gasoline oxygenates and by-products. A relatively simple extraction method using a CAR/PDMS(75${\mu}{\textrm}{m}$) SPME fiber was optimized for the routine analysis of gasoline oxygenates and by-products in groundwater and reagent water. A sodium chloride concentration of 25%(w/w) combined with an extraction time of 20 min provided the greatest sensitivity while maintaining analytical efficiency Replicate analyses in fortified reagent and groundwater spiked with microgram per liter concentrations of gasoline oxygenates and by-products indicate quantitative and reproducible recovery of these and related oxygenate compounds. Method dynamic range was 50$\mu\textrm{g}$ L-1 to 3000$\mu\textrm{g}$ L-1 for gasoline oxygenates and by-products.

• Steel and Composite Structures
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• 제33권2호
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• pp.245-259
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• 2019

The present study aims to investigate the ultimate strength and geometric nonlinear behavior of composite plates containing initial imperfection subjected to combined end-shortening strain and lateral pressure loading by using a semi-analytical method. In this study, the first order shear deformation plate theory is considered with the assumption of large deflections. Regarding in-plane boundary conditions, two adjacent edges of the laminates are completely held while the two others can move straightly. The formulations are based on the concept of the principle of minimum potential energy and Newton-Raphson technique is employed to solve the nonlinear set of algebraic equations. In addition, Hashin failure criteria are selected to predict the failures. Further, two distinct models are assumed to reduce the mechanical properties of the failure location, complete ply degradation model, and ply region degradation model. Degrading the material properties is assumed to be instantaneous. Finally, laminates having a wide range of thicknesses and initial geometric imperfections with different intensities of pressure load are analyzed and discuss how the ultimate strength of the plates changes.