• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.5D
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• pp.527-532
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• 2012

Terrestrial LiDAR emerges as a main mapping technology for indoor 3D cadastre, cultural heritage conservation and, building management in that it provides fast, accurate, and reliable 3D data. In this paper, a new 3D modeling method consisting of segmentation stage and outline extraction stage is proposed to develop indoor 3D model from the terrestrial LiDAR. In the segmentation process, RANSAC and a refinement grid is used to identify points that belong to identical planar planes. In the outline tracing process, a tracing grid and a data conversion method are used to extract outlines of indoor 3D models. However, despite of an improvement of productivity, the proposed approach requires an optimization process to adjust parameters such as a threshold of the RANSAC and sizes of the refinement and outline extraction grids. Furthermore, it is required to model curvilinear and rounded shape of the indoor structures.

• Composites Research
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• v.28 no.6
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• pp.372-377
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• 2015

In this study, we analyzed process numerically when a bogie frame skin is manufactured by applying resin transfer molding process using composite material instead of steel. Processing time was compared based on the various thickness of bogie frame skin and the weight variation of a skin was also considered. As a result, RTM processing time decreases and the weight of a bogie reduces as the thickness of frame skin increases with the assumption that fiber volume is constant inside the skin. By considering these results as the information to estimate the production cost, trade-off between two fields, processing time and structural properties, can be performed in design optimization to produce bogie frame.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.6
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• pp.1911-1918
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• 2014

The increase of input resources, such as labor and equipment, in a construction project causes workspace interference between activities and it influences on the productivity and quality of construction activities. To solve this problem, many studies related to the workspace interference have been performed, however they verified the workspace concerning with only the geometric location of activities or generated the shape of workspace by a whole object concept not separated units of detailed operations. It is difficult for project manager to reasonably analyze the workspace conflict, because the size of workspace cannot reflect the characteristics of an activity and input time of a resource. This paper presents a methodology that can generate three-dimensional models in order to optimize the workspace shape and size by considering with the characteristics of each activity and input time of each resource. The suggested method can be used for the active BIM system that optimizes the workspace conflict without additional construction duration and for the searching algorithm of optimized moving path for construction equipment.

• The Journal of Korean Academy of Prosthodontics
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• v.29 no.1
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• pp.167-213
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• 1991

The successful replacement of missing teeth has been one driving aim behind the emergence of implant dentistry as both a technology and clinical vocation for over four decades. To date, a multitude of dental implant devices had been designed and utilized in the patient population. Most of these devices have been designed without support of the engineering criteria. The long-term success of any dental implant is dependent upon the optimization of stresses which occurs during oral function and parafunction. Although many studies have examined the biologic interactions between dental implants and living tissue, few studies have been reported on the biomechanical aspects of dental implants. The purpose of this study was to analyze the stress distribution of osseointegrated prosthesis on certain conditions, such as amount of load, location of load, length of fixtures, number of fixtures used, arch shape, bone quality, etc. Three dimentional finite element analysis was used for this study. FEM models were created using commercial software(Super SAP. for IBM 16 bit AT computer. All elements were 8-node brick, isoparametric. Mandible and prosthesis was modeled with 780 elements and 1074 nodes. The results were as follows : 1. In case of cantilever extension, there was a compressive stress at the base of the first implant and a tensile stress at the base of the second implant. 2. The stresses were linearly proportional to the amount of load. 3. The stresses were linearly proportional to the length of cantilever. 4. There was a stress concentration at the neck of the implant and bone under horizontal loads.

• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• v.5 no.1
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• pp.22-28
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• 2002

A New concept for the LNG-FPSO ship, with moonpool and bilge step in bottom, is proposed. This concept is investigated with regard to motion reduction and sloshing phenomena of the cargo and operation tanks. The principal dimensions of the ship are $L\timesb B\times D\times t(design)=270.0\times51.0\times32.32\times13.7(m)$, with a total cargo capacity of 161KT; a 98% loading condition is considered for this study. The moonpools and rectangular step at the bilge have been designed for the purpose of decreasing the motion within the tank. For the motion analysis, linearized three-dimensional diffraction theory, with the simplified boundary condition was used. The six-degree of freedom coupled motion responses were calculated for the LNG-FPSO ship. Viscous effects on the roll motion responses of a vessel were taken into account in this calculation program, using an empirical formula suggested by Himeno(1981). The case study for the moonpool size has been conducted using theoretical estimation and the experimental method. For the optimization of the moonpool size and effect of the bilge step, 9 cases of its size, both with and without bilge step, were involved in the study. no motion responses, especially roll motion, for the designed LNG-FPSO ships are much lower than those of other drill ships and shuttle tankers. The limit criterions are satisfied. To check the cargo tank and operation tank sizes, we performed a sloshing analysis in the irregular waves which focuses on the pressure distribution on the tank wall and the time history of pressure and free surface for No.2 and 5 tanks of LNG-FPSO with chamfers. Finally, optimum tank sire was estimated.

• Speech Sciences
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• v.5 no.1
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• pp.7-21
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• 1999

This paper proposes an improved training procedure in speech recognition based on the continuous density of the Hidden Markov Model (CDHMM). Of the three parameters (initial state distribution probability, state transition probability, output probability density function (p.d.f.) of state) governing the CDHMM model, we focus on the third parameter and propose an efficient algorithm that determines the p.d.f. of each state. It is known that the resulting CDHMM model converges to a local maximum point of parameter estimation via the iterative Expectation Maximization procedure. Specifically, we propose two independent algorithms that can be embedded in the segmental K -means training procedure by replacing relevant key steps; the adaptation of the number of mixture Gaussian p.d.f. and the initialization using the CDHMM parameters previously estimated. The proposed adaptation algorithm searches for the optimal number of mixture Gaussian humps to ensure that the p.d.f. is consistently re-estimated, enabling the model to converge toward the global maximum point. By applying an appropriate threshold value, which measures the amount of collective changes of weighted variances, the optimized number of mixture Gaussian branch is determined. The initialization algorithm essentially exploits the CDHMM parameters previously estimated and uses them as the basis for the current initial segmentation subroutine. It captures the trend of previous training history whereas the uniform segmentation decimates it. The recognition performance of the proposed adaptation procedures along with the suggested initialization is verified to be always better than that of existing training procedure using fixed number of mixture Gaussian p.d.f.

• Journal of Hydrogen and New Energy
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• v.21 no.3
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• pp.193-200
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• 2010

Anode off-gas of high temperature fuel cell still contains combustible components such as hydrogen, carbon monoxide and hydrocarbon. In this study, a catalytic combustor has been applied to the high temperature fuel cell so that the combustion of anode-off gas can be boosted up. Since the performance of catalytic combustor directly depends on the combustion catalyst, this study is designed to perform the experimental investigation on the combustion characteristics of the three commercial catalysts with a different composition. Screening tests with three catalysts are preceded before the performance examination since it is necessary to determine the most suitable catalyst for design configuration of the catalytic combustor. The performance analysis shows that methane conversion rate strongly depends on gas hourly space velocity (GHSV) as well as inlet gas temperature. Additionally, the GSHV optimization results show that the optimum GHSV will be in the range between 18,000 $hr^{-1}$ and 36,000 $hr^{-1}$. It is also shown that the minimum inlet temperature of catalytic reaction of methane is from $100^{\circ}C$ to $150^{\circ}C$.

• Korean Chemical Engineering Research
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• v.50 no.2
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• pp.264-269
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• 2012

Die slide injection marvelously reduces the cost and time in processing plastic products because they can simplify the conventional process through eliminating additional process. However, this process must resolve some defects like whitening, resin infiltration, blowhole, resin overflow, etc. In this study, the process parameters of the injection molding are optimized by using the finite element method and Taguchi method. The injection molding analysis is simulated by employing the Moldflow insight 2010 code and the 2nd injection is by adopting the Multi-stage injection code. The process parameters are optimized by using the $L_{16}$ orthogonal array and smaller-the-better characteristics of the Taguchi method that was used to produce an airtight container (coolant reservoir tank) from polypropylene (PP) plastic material.rodanwhile, the optimum values are confirmed to be similar in 95% confidence and 5% significance level through analysis of variance (ANOVA). rooreover, new products and old products were compared by mdasuring the dimensional accuracy, resulting in the improvement of dimensional stability more than 5%.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.7
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• pp.477-484
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• 2016

In a multi-effect solar distiller, a feeding rate of seawater to each effect should be decreased as the effect number is increased. In previous studies, the feed rate of seawater was not reduced evenly between the effects, which is unreasonable, since the thermal energy input of each effect decreases by the same amount. In this work, numerical analysis was carried out in order to elucidate this discrepancy. The results showed that the amount of distillates produced was almost the same for both evenly and unevenly reduced flow rates between the effects. Optimum feed rates of seawater with various energy inputs from exhaust gas heat exchanger were also obtained. The results showed that the optimum feed rate of the first effect increased linearly or reached a steady state depending on the heat flux.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.10
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• pp.941-946
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• 2010

This study aims to investigate the effects of soybean biodiesel fuel on exhaust emissions with regards to two combustion modes: conventional combustion(existence of PM-NOx trade-off behavior) and low temperature combustion(LTC) in a 1.7 L common rail direct injection diesel engine. As compared to conventional combustion, LTC was achieved by adopting a heavier exhaust gas recirculation and strategic injection parameter optimization. Two sets of fuels, i.e. ultra low sulfur diesel(ULSD) and 20% volumetric blends of soybean biodiesel with ULSD(B20) were used. Regardless of the fuel type, in LTC the simultaneous reduction of PM and NOx was observed and both levels were significantly lower than in case of conventional combustion. Under the given engine operating condition in the case of conventional combustion, B20 produced less PM and more NOx than ULSD. In the case of LTC combustion, B20 produced more PM and NOx than ULSD.