• 한국도로학회논문집
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• 제17권6호
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• pp.117-126
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• 2015

PURPOSES : This study prioritizes potential technology for establishing a safe work zone environment on roadways. We consider almost all conceivable technologies that enable mitigation of unexpected accidents for both road workers and drivers. METHODS : This study suggests a methodology to set the priority of potential technology for establishing a safe work zone environment by using the analytical hierarchy process (AHP). For this purpose, the AHP structure was first developed. Thereafter, a web-based survey was conducted to collect experts' opinions. Based on the survey results, weights associated with the relevant criteria of the developed structure were estimated. With the consistency index (CI) and consistency ratio (CR), we verified the estimated weights. In addition, a sensitivity analysis was performed to confirm whether the estimated weights were reliable. We finally proposed the priority for potential technology for establishing a safe work zone environment on roadways. RESULTS : In the first level, safety technology has the highest priority, and real-time information delivery for work zone, hazard warning for drivers, and temporal automated operation for traffic facilities were selected in the second level of hierarchy. CONCLUSIONS : The results imply that establishing the priority will be useful to establish a future road map for improving the work environment for road workers and drivers by employing appropriate protection facilities and developing safety systems.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 춘계학술대회 논문집
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• pp.63-67
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• 2001

Springback after drawing and trimming is regarded as one of the most influential factors during forming structural frames since the part dimensions have dominant effect on assembly quality at later stages. In this study, analytical results were obtained from a commercial FEM package for an outer rear frame of an automobile. In terms of springback and twist the effect of forming process is compared and discussed between open and closed-ends forming

• Journal of Construction Engineering and Project Management
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• 제5권2호
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• pp.35-43
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• 2015

Project Management Consultant (PMC) plays a vital role in the overall performance of any project. Selecting right PMC for right project is the most crucial challenge for any construction owner. Thus, PMC selection is one of the main decisions made by owners at the early phase of construction project. It is not easy for the project owner to select a competent PMC due to the fuzziness, imprecision, vagueness, incomplete and qualitative criteria of the decision. This paper presents a model for selecting PMC contractor using the Fuzzy Analytical Hierarchy Process (FAHP). And a fuzzy number based framework is proposed to be a viable method for PMC contractor selection. A case study to illustrate the application of the model is also presented in this paper.

• 분석과학
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• 제35권2호
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• pp.41-52
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• 2022

The leaching of nitrate from soil increases the concentration of elements, such as nitrogen, phosphorus, and potassium, in water, causing eutrophication. In this study, the feasibility of using clinoptilolite as an ion-exchange material to reduce nitrate leaching in soil was investigated. Soil samples were collected from three soil depths (0 - 30, 30 - 90, and 90 - 120 cm), and their sorption capacity was determined using batch experiments. The effects of contact time, initial concentration, adsorbent dosage, pH, and temperature on the removal of NO₃^- were investigated. The results showed that an initial concentration of 25 mg L^-1, a contact time of 120 min, an adsorbent dosage of 5.0 g/100 mL, a pH of 3, and a temperature of 30 ℃ are favorable conditions. The kinetic results corresponded well with a pseudo-second-order rate equation. Intra-particle diffusion also played a significant role in the initial stage of the adsorption process. Thermodynamic studies revealed that the adsorption process is spontaneous, random, and endothermic. The results suggest that a modification of clinoptilolite effectively reduces the leaching of nitrate in soil.

• Structural Engineering and Mechanics
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• 제70권5호
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• pp.525-534
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• 2019

An analytical research on buckling of simply supported thin plate with variable thickness under bi-axial compression is presented in this paper. Combining the perturbation technique, Fourier series expansion and Galerkin methods, the linear governing differential equation of the plate with arbitrary thickness variation under bi-axial compression is solved and the analytical expression of the critical buckling load is obtained. Based on that, numerical analysis is carried out for the plates with different thickness variation forms and aspect ratios under different bi-axial compressions. Four different thickness variation forms including linear, parabolic, stepped and trigonometric have been considered in this paper. The calculated critical buckling loads and buckling modes are presented and compared with the published results in the tables and figures. It shows that the analytical expressions derived by the theoretical method in this paper can be effectively used for buckling analysis of simply supported thin plates with arbitrary thickness variation, especially for the stepped thickness that used in engineering widely.

• 산업기술연구
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• 제19권
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• pp.391-402
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• 1999

The numerical model predicting the behaviours of submerged mound constructed by dredged material is developed in this paper. The model is based on the Bailard's sediment transport formula, Stokes' second-order wave theory and the sediment balance equation. Nonlinear partial differential equation which is the same form as convection-dispersion equation which represents change of bed section can be obtained by substituting sediment transport equation for equation of sediment conservation. By this process, the analytical solution by which the characteristic of the behaviours of submerged mound can be estimated is derived by probably combining the convention coefficient and the dispersion coefficient governing the behaviours of submerged mound and the probability density function representing the wave characteristics. The validity of the analytical solution is verified by comparing the analytical solution which is assumed to estimate the movement rate submerged mound by bed-load with the field data of the past and its characteristic is analyzed quantitatively by obtaining the mean of the dispersion coefficient representing the extent of the decrease rate of the submerged mound height.

• 한국해양공학회지
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• 제24권2호
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• pp.25-33
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• 2010

Collision between vessels may lead to structural damage and penetration of hulls. The structural damage of a hull may eventually bring about global collapse of the hull girder and outflow of oil, which would contaminate seawater. Therefore, various regulations require the strength of a vessel after collision to satisfy given criteria, and owners usually request collision analyses to confirm the structural safety of their vessels. In the process of designing a vessel to satisfy the collision strength criteria, the strength has been assessed mostly by conducting collision analyses using numerical techniques, such as dynamic, non-linear, finite-element analysis. Design is an inherently iterative process during which many changes are necessary due to the endless needs for reinforcement and modification. Numerical techniques are not adequate for coping with a situation in which collision analysis is frequently required to provide the revised results that reflect the repetitive changes in designs. Numerical techniques require a lot of time and money to conduct in spite of recent improvements in computing power and in the productivity of modeling tools. Therefore, in this paper, an analytical technique is introduced and a collision problem is idealized and simplified using reasonable assumptions based on appropriate background. The technique was applied to an example of an actual FPSO and verified by comparing the results with results from the numerical technique. A good correlation was apparent between the results of the analytical and numerical techniques.

• Journal of Pharmaceutical Investigation
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• 제39권1호
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• pp.29-36
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• 2009

Since the quality of final products is significantly affected by the homogeneity of powder mixture, the powder blending process has been regarded as one of the critical pharmaceutical unit processes, especially for solid dosage forms. Accordingly, the monitoring to determine a blending process' end-point based on a faster and more accurate in-line/on-line analysis has attracted enormous attentions recently. Among various analytical tools, NIR (near-infrared) spectroscopy has been extensively studied for PAT (process analytical technology) system due to its many advantages. In this study, NIR spectroscopy was employed with an optical fiber probe for the in-line monitoring of fluid-bed blending process. The position of the probe, the ratio of binary powder mixture, the powder size differential and the back-flush period of the shaking bag were examined as principal process parameters. During the blending process of lactose and mannitol powders, NIR spectra were collected, corrected, calibrated and analyzed using MSC and PLS method, respectively. The probe position was optimized. A reasonable end-point was predicted as 1,500 seconds based on 5% RSD value. As a consequence, it was demonstrated that the blending process using a fluid-bed processor has several advantages over other methods, and the application of NIRS with an optical fiber probe as PAT system for a fluid-bed blending process could be high feasible.

• 분석과학
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• 제27권3호
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• pp.167-171
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• 2014

불화수소는 유리의 식각, 금속의 녹 제거 등 산업계에서 많이 사용되는 대표적인 무기산이며 노출 시 눈, 코, 목안을 강하게 자극하고, 흡입 시 폐렴, 폐수종 기관지염을 일으키는 대표적인 유독물질에 해당하는 화학물질로 구분되어 있다. 현행 폐기물공정시험기준에는 불소화합물에 대한 함량분석방법이 마련되어 있지 않아 최근 발생된 불화수소 누출사고로 발생된 불산에 오염된 농작물, 수목 등 가연성 폐기물의 신속하고 안전한 처리방법 마련에 어려움을 겪었다. 본 연구에서는 불화수소 누출사고로 발생된 가연성 폐기물(농작물, 수목 등) 중 불소 및 불소화합물의 함량분석방법 마련을 통해 폐기물의 불산 오염여부를 판단하고 적절한 폐기물 처리방법을 제시하고, 향후 이 방법을 폐기물 관리법상에 지정폐기물에 함유된 유해물질로 불소 및 불소화합물에 대한 항목 추가 시 폐기물공정시험기준으로 활용하고자 한다.

• 분석과학
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• 제5권4호
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• pp.359-366
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• 1992

본 논문은 마이크로 Raman 분광분석법을 이용하여 국부적 열산화 후 실리콘 표면에 유입되는 스트레스를 평가한 것이다. 국부적 열산화 후 실리콘 표면에 유입되는 스트레스는 실리콘 산화막과 active 영역의 경계 부분에서 최대치를 나타내었다. Active 영역의 크기가 작아질수록 스트레스량은 증가하며, 이는 스트레스가 active 영역의 크기에 의존함을 보여 주는 것이다. 또한, active 영역이 $0.45{\mu}m$인 세 가지 소자 분리 공정, A, B, moB를 평가한 결과 moB 공정의 스트레스 값이 가장 작았으며, 새부리 효과도 가장 작았다.