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Location estimation of autonomous driving robot and 3D tunnel mapping in underground mines using pattern matched LiDAR sequential images

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International Journal of Mining Science and Technology 2021年第5期31卷 779-788页

作者： Heonmoo Kim Yosoon choi Department of Energy Resources Engineering Pukyong National UniversityBusan 48513Republic of Korea

In this study,a machine vision-based pattern matching technique was applied to estimate the location of an autonomous driving robot and perform 3D tunnel mapping in an underground mine *** autonomous driving robot continuously detects the wall of the tunnel in the horizontal direction using the light detection and ranging(Li DAR)sensor and performs pattern matching by recognizing the shape of the tunnel *** proposed method was designed to measure the heading of the robot by fusion with the inertial measurement units sensor according to the pattern matching accuracy;it is combined with the encoder sensor to estimate the location of the *** addition,when the robot is driving,the vertical direction of the underground mine is scanned through the vertical Li DAR sensor and stacked to create a 3D map of the underground *** performance of the proposed method was superior to that of previous studies;the mean absolute error achieved was 0.08 m for the X-Y axes.A root mean square error of 0.05 m^(2)was achieved by comparing the tunnel section maps that were created by the autonomous driving robot to those of manual surveying.

关键词： Pattern matching Location estimation Autonomous driving robot 3D tunnel mapping Underground mine

Diagnosis of building energy consumption in the 2012 CBECS data using heterogeneous effect of energy variables:A recursive partitioning approach

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Building Simulation 2021年第6期14卷 1737-1755页

作者： Doowon choi Chul Kim Department of Industrial and Systems Engineering College of EngineeringTexas A&M UniversityCollege StationTX 77843USA Indoor Air Quality Research Center Korea Institute of Civil Engineering and Building TechnologyGoyang-Si10223R.O.Korea

Numerous previous literature has attempted to apply machine learning techniques to analyze relationships between energy variables in energy ***,most machine learning methods are primarily used for prediction through complicated learning processes at the expense of *** methods have difficulties in evaluating the effect of energy variables on energy consumption and especially capturing their heterogeneous ***,to identify the energy consumption of the heterogeneous relationships in actual buildings,this study applies the MOdel-Based recursive partitioning(MOB)algorithm to the 2012 CBECS survey data,which would offer representative information about actual commercial building characteristics and energy *** resultant tree-structured subgroups,the MOB tree reveals the heterogeneous effect of energy variables and mutual influences on building energy *** results of this study would provide insights for architects and engineers to develop energy conservative design and retrofit in *** buildings.

关键词： CBECS,commercial building decision tree analysis MOdel-Based recursive partitioning(MOB)algorithm recursive partitioning subgroup identification

Comparative simulation study of effects of eddy-topography interaction in the East/Japan Sea deep circulation

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Acta Oceanologica Sinica 2015年第7期34卷 1-18页

作者： choi Youngjin Center for Earth Information Science and Technology Japan Agency for Marine-Earth Science and Technology Geo System Research Corporation

In this study the structure and seasonal variations of deep mean circulation in the East/lapan Sea （E/S） were numerically simulated using a mid-resolution ocean general circulation model with two different parameterizations for the eddy-topography interaction （ETI）. The strong deep mean circulations observed in the EIS are well reproduced when using the ETI parameterizations. The seasonal variability in the EIS deep layer is shown by using ETI parameterization based on the potential vorticity approach, while it is not shown in the statistical dynamical parameterization. The driving mechanism of the strong deep mean currents in the E/S are discussed by investigating the effects of model grids and parameterizations. The deep mean circulation is more closely related to the baroclinic process and potential vorticity than it is to the wind driven circulation.

关键词： East/Iapan Sea deep mean current seasonal variability ocean general circulation model eddy- topography interaction

Invariant operator theory for the single-photon energy in time-varying media

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Chinese Physics B 2010年第1期19卷 56-60页

作者： choi Jeong-Ryeol School of Electrical Engineering and Computer Science Kyungpook National University

After the birth of quantum mechanics, the notion in physics that the frequency of light is the only factor that determines the energy of a single photon has played a fundamental role. However, under the assumption that the theory of Lewis-Riesenfeld invariants is applicable in quantum optics, it is shown in the present work that this widely accepted notion is valid only for light described by a time-independent Hamiltonian, i.e., for light in media satisfying the conditions, ε（t） = ε（0）, u（t） = u（0）, and σ（t） = 0 simultaneously. The use of the Lewis Riesenfeld invariant operator method in quantum optics leads to a marvelous result： the energy of a single photon propagating through time-varying linear media exhibits nontrivial time dependence without a change of frequency.

关键词： single-photon energy invariant operator theory time-varying media

Cartesian Grid Method with Cut Cell in the Mold Filling Simulation

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Journal of Materials Science & Technology 2008年第3期24卷 379-382页

作者： Youngsim choi Junho Hong Hoyoung Hwang Jeongkil choi Center-for e-Design KITECH7-47-Songdo-DongYeonsu-Ku

In this paper, a Cartesian grid method with cut cell has been developed to simulate mold filling of casting process. Cut cells at the cast-mold interface are generated on the Cartesian grid. With the boundary cut cells, a special treatment is necessary. That is Cartesian grid method with cut cell. A simple shape was tested and the cut cell method was compared with the traditional one on Cartesian grids. And, a developed method was applied to the real casting product simulation. Cartesian grid system causes momentum loss and unsound fluid flow patterns because of inaccurate generation of meshes. These problems have been improved by using cut cell method.

关键词： Cartesian grids Cut cell Momentum loss

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皮革的可塑性 POLENE首尔专卖店

室内设计与装修 2025年第1期 90-95页

作者：无 Minwoo(Ian)Yang Sunho Shin Hyevin Park Yongjoon choi(摄影) 秋落(编译) WGNB 不详

继巴黎、纽约和东京之后,专注皮革设计的小众品牌Pol$ne于日前在韩国首尔开设首家品牌旗舰店,也是全球第4间专卖店。这个深受时尚迷和年轻一代欢迎的法国小众品牌,将店址选在逛街胜地之一的江南新沙洞,打造了两层的品牌旗舰店。除了延... 详细信息

继巴黎、纽约和东京之后,专注皮革设计的小众品牌Pol$ne于日前在韩国首尔开设首家品牌旗舰店,也是全球第4间专卖店。这个深受时尚迷和年轻一代欢迎的法国小众品牌,将店址选在逛街胜地之一的江南新沙洞,打造了两层的品牌旗舰店。除了延续品牌形象,引进品牌经典包款和人气新作,受到韩国打卡文化的影响,Pol$ne为首尔旗舰店精心规划出拍照空间,凡是走进店内的人,都会忍不住想要拿起手机留下回忆。

关键词：小众品牌旗舰店皮革品牌形象专卖店 Pol

Molecular dynamics study of water diffusion in an amphiphilic block copolymer with large difference in the blocks＇ glass transition temperatures

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Frontiers of Chemical Science and Engineering 2017年第3期11卷 440-447页

作者： Yang Zhou Phillip choi Department of Chemical and Materials Engineering University of Alberta Edmonton Edmonton AB T6G 1H9 Canada

Isothermal-isobaric molecular dynamics simu- lation was used to study the diffusion mechanism of water in polyurethane-block-poly（N-isopropyl acrylamide）（PU- block-PNIPAm） with a hydrophobic PU/hydrophilic PNIPAm mass ratio of 1.4 to 1 at 298 K and 450 K. Here, the experimental glass transition temperature （Tg） of PU is 243 K while that of PNIPAm is 383 K. Different amounts of water up to 15 wt-% were added to PU-block- PNIPAm. We were able to reproduce the specific volumes and glass transition temperatures （250 K and 390 K） of PU- block-PNIPAm. The computed self-diffusion coefficient of water increased exponentially with increasing water concentration at both temperatures （i.e., following the free volume model of Fujita）. It suggested that water diffusion in PU-block-PNIPAm depends only on its fractional free volume despite the free volume inhomo- geneity. It is noted that at 298 K, PU is rubbery while PNIPAm is glassy. Regardless of temperature, radial distribution functions showed that water formed clusters with sizes in the range of 0.2-0.4 nm in PU-block- PNIPAm. At low water concentrations, more clusters were found in the PU domain but at high water concentrations, more in the PNIPAm domain. It is believed that water molecules diffuse as clusters rather than as individual molecules.

关键词： molecular dynamics simulation amphiphilic block copolymer free volume water diffusivity fujita model

Research trend of cascade heat pumps

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Science China(Technological Sciences) 2017年第11期60卷 1597-1615页

作者： BOAHEN Samuel choi JongMin Graduate School of Mechanical Engineering Hanbat National UniversityDaejeon 34158Korea Department of Mechanical Engineering Hanbat National UniversityDaejeon 34158Korea

Most commercial and industrial facilities require very low temperatures for refrigeration and high temperatures for space heating and hot water purposes. Single stage heat pumps have not been able to meet these temperature demands and have been characterized by low capacities and coefficient of performance(COP). Cascade heat pump has been developed to overcome the weaknesses of single stage heat pumps. This study reviews recent works done by researchers on cascade heat pumps for refrigeration, heating and hot water generation. Selection of suitable refrigerants to meet the pressure and temperature demands of each stage of the cascade heat pump has been discussed. Optimization of design parameters such as intermediate temperature(low stage condensing and high stage evaporating temperatures), and temperature difference in the cascade heat exchanger for optimum performance of the cascade heat pump has been reviewed. It was found that optimising each design parameter of the cascade heat pump is necessary for maximum system performance and this may improve the exergetic efficiency, especially of cascade refrigeration systems, by about 30.88%. Cascade heat pumps have wider range of application especially for artificial snow production, in the supermarkets,for natural gas liquefaction, in drying clothes and food and as heat recovery system. The performance of cascade heat pumps can be improved by 19% when coupled with other renewable energy sources for various real time applications. Also, there is the need for much research on refrigerant charge amount of cascade heat pumps, refrigerant-refrigerant heat exchangers to be used as cascade heat exchanger, cascade heat pumps for simultaneous cooling, heating and hot water generation and on the use of variable speed compressors and their control strategies in matching system capacity especially at part load conditions.

关键词： cascade heat pump low stage high stage optimization system performance refrigerant

Cofactor engineering in cyanobacteria to overcome imbalance between NADPH and NADH： A mini review

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Frontiers of Chemical Science and Engineering 2017年第1期11卷 66-71页

作者： Jongmoon Park Yunnam choi Department of Chemical Engineering Pohang University of Science and Technology Gyeongbuk 790-784 Korea School of Environmental Science and Engineering Pohang University of Science and Technology Gyeongbuk 790-784 Korea Division of Advanced Nuclear Engineering Pohang University of Science and Technology Gyeongbuk 790-784 Korea

Cyanobacteria can produce useful renewable fuels and high-value chemicals using sunlight and atmo- spheric carbon dioxide by photosynthesis. Genetic manip- ulation has increased the variety of chemicals that cyanobacteria can produce. However, their uniquely abundant NADPH-pool, in other words insufficient supply of NADH, tends to limit their production yields in case of utilizing NADH-dependent enzyme, which is quite common in heterotrophic microbes. To overcome this cofactor imbalance and enhance cyanobacterial fuel and chemical production, various approaches for cofactor engineering have been employed. In this review, we focus on three approaches：（1） utilization of NADPH- dependent enzymes, （2） increasing NADH production, and （3） changing cofactor specificity of NADH-dependent enzymes from NADH to NADPH.

关键词： NADH-dependent enzyme NADPH-depen-dent enzyme transhydrogenase site-directed mutagenesis,enzyme engineering