• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.3
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• pp.53-64
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• 2013

The car-following model is one of core models in Advanced Vehicle & Highway Systems (AVHS). The car-following model has been developed in aspects such as human factor and reduction error rates. However, the consideration of safety depending on weather condition has not been completed yet. In this paper, therefore, changes of driving condition for car-following due to different road condition were dealt with, and optimal safety distance corresponding to road condition such as dry, wet and snowy were computed. The GMIT(GM Model with Instantaneous T) model was picked over for simulation of adaptive cruise control applied the suggested optimal safety distance. As the results, the 1.7 times longer safety distance was required for wet road condition than dry road condition, and the 5.6 times longer safety distance was required for snowy road condition.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.8 s.101
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• pp.945-953
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• 2005

The purpose of this paper is to develop a linear regression model for the sound quality index of vehicle Interior noise. For this, objective measurement data of the vehicles driving in acceleration was measured. On the basis of analysis, psychoacoustic parameters were extracted and subjective evaluation was performed by noise and vibration expert evaluators. For the subjective evaluation, the paired comparisons and the semantic differential methods were used to evaluate sound quality of vehicle interior noise. By the paired comparison which evaluate two pairs of vehicle interior noise, the preference was estimated. With the semantic differential and the factor analysis, it was evaluated words of two pairs which expressed appropriately the sense of evaluator about noise source. Therefore the characteristics of the sound qualify for the vehicle were differentiated. From the results of both the correlation analysis and the multiple factor regression analysis, the sound quality evaluation model for the sense of human hearing was derived and indexed.

• Korean Management Science Review
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• v.33 no.3
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• pp.31-51
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• 2016

The objective of the study is to propose the catch-up strategy of Hyundai Kia to become the globally leading company in the automobile industry. For this, we try to compare Hyundai Kia with three leading automobile companies: Toyota, VW, and GM by using the Generalized Double Diamond Model. As a result, we present three ways that Hyundai Kia can become a "First Mover." The three strategies are : 1) controlling increase of wage, raising productivity, and increasing R&D investment 2) increasing overseas investment of the small and medium sized automobile factories 3) pursuing the two tracks strategy of a public car and a prestige car more aggressively. This study is significant in the fact that it presents the catch-up strategy of Hyundai Kia in the automobile industry, of which the leaders can not be changed easily, by the Generalized Double Diamond Model approach.

• Proceedings of the KSRS Conference
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• v.1
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• pp.274-277
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• 2006

KARI is currently developing a geostationary ocean color imager (GOCI) for COMS. We report the progress in integrated optical modeling and analysis for stray light suppression and the end-to-end instrument performance verification including in-orbit calibration. The Sun is modeled as the emitting light source and the selected area around Korean peninsular as the observation target that scatters the sun light towards GOCI in orbit. The optical ray tracing employing active geometric scaling was then used for precise characterization of the spatial and radiometric performance at the instrument focal plane. The analysis results show positive reduction in the simulated stray light level with the design improvement including baffles. It also indicates that the ray traced in-orbit radiometric performances are effective tools for the independent assessment of more traditional linear and quadratic equation based estimation of water leaving radiance. The concept of integrated GOCI optical model and the computational method are presented.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.7
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• pp.317-323
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• 2001

We investigated the stability of cryocooler-cooled high-temperature superconducting (HTS) coils by using a computer program based on FEM. In this study, the current at which "thermal runaway" occurs, which depends on the relationship between the cooling power of the cryocooler and the heat generation in HTS coils, was adopted as a stability criterion of cryocooler operating HTS coils. It was shown that cryocooler-cooled HTS coil was stable in operating current above the critical current from the numerical analysis results by HTS model coil. And also, if we efficiently remove the heat generation from HTS coils by potimizing heat drain, the ramp-rate limitation can be mitigated because the effect of AC loss by the current rise was too small. Furthermore, in the case of pulsed operation; the HTS model coil is ramped from zero to the peak value in one second and back to zero current in one second, such as the operation of SMES device, the peak value of poerating current is 1.5-2 times greater than that of the thermal runaway current.

• Journal of Distribution Science
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• v.22 no.8
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• pp.65-76
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• 2024

Purpose: The study aims to recognize the relationship between big data analytics capabilities, big data analytics process, and perceived business performance from supply chain management to total customer satisfaction. Research design, data and methodology: The study followed a quantitative approach with a descriptive design. The data was collected from leading e-commerce companies in India using a structured questionnaire, and the data was coded and decoded using MS Excel, SPSS, and R language. It was further tested using Cronbach's alpha, KMO, and Bartlett's test for reliability and internal consistency. Results: The results showed that the big data analytics process acts as a robust mediator between big data analytics capabilities and perceived business performance. The 'direct, indirect and total effect of the model' and 'PLS-SEM model' showed that the big data analytics process directly impacts business performance. Conclusions: A complete indirect relationship exists between big data analytics capabilities and perceived business performance through the big data analytics process. The research contributesto e-commerce companies' understanding of the importance of big data analytics capabilities and processes.

• The Journal of Korean Academy of Prosthodontics
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• v.34 no.3
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• pp.415-430
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• 1996

The purpose of this study was to evaluate the stress distributions in the surrounding tissues of the teeth seated by indirect retainers in three different teeth of unilateral distal extension partial denture when the dislodging forces were applied on denture bases. Three dimensional photoelastic models were made. The teeth on which indirect retainers were seated were mandibular left lateral incisor (Model I), canine (Model II), and first premolar (Model III). The dislodging force with 860mg at $45^{\circ}$ angulation to occlusal plane was applied to each model. Three dimensional photoelastic stress analysis was done, and the records were diagramed and analysed. The results were as follows : The compressive stresses were shown the most on neck portions of buccal, mesial, and distal sides in all three models. Slight tensile stresses were shown on neck portions of lingual sides in all three models. The compressive stresses on buccal side were shown in strength in such order as model I, model II, and model III. The compressive stresses were shown on neck portion of mesial and distal sides of model I and mode II, with model I more than Model II. The compressive stresses were shown only on neck portion of mesial side on Model III. The general overall magnitude of compressive stresses were shown in strength in such order as Model I, Model II, and Model III.

• Journal of Acupuncture Research
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• v.33 no.2
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• pp.21-34
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• 2016

Objectives : The aim of the present study is to examine the effect and mechanism of Erycibae Caulis and Corydalis Tuber Pharmacopuncture (ECP) on a mouse model with collagen induced rheumatoid arthritis (CIA). Methods : We evaluated the Aspartate aminotransferase (AST), Alanine aminotransferase (ALT), Creatinine, and the Blood urea nitrogen (BUN) of serum to examine the safety of this study. In vivo, we compared the results of the non-treated group, the normal saline pharmacopuncture treated control group, the indomethacin treated group and the ECP group. We evaluated rheumatoid arthritis manifestation and the Rheumatoid Arthritis Index (AI). Also, immune cells in blood affected by ECP were evaluated by calculating the level of white blood cells (WBC), neutrophil, lympocytes and monocytes. Next, the level of Immunoglobulin M (IgM), Immunoglobulin G (IgG), Interleukin (IL)-$1{\beta}$, IL-6, IL-17, Tumor Necrosis Factor (TNF)-${\alpha}$ and Granulocyte-macrophage Stimulating Factor (GM-CSF)in serum were measured. We examined the imaging of cartilage degeneration using micro CT-arthrography of the hind paw. Additionally, we examined the effects of reducing bone volume (BV) ratio and bone surface/bone volume (BS/BV) ratio with 3D Micro-CT. Finally, we did a histopathologic examination analysis. Results : The absence of liver and kidney toxicity was evident. In vivo, edema of the joints of the ECP group decreased greatly in macroscopic observation. AI measurement of the ECP group also decreased significantly compared to the control group. The level of WBC, neutrophil, lympocytes, and monocytes in the blood decreased but there was no statistical significance of this data. IgM of the ECP group decreased significantly compared to the control group. IL-$1{\beta}$, IL-6, TNF-${\alpha}$, and GM-CSF production of the ECP group decreased significantly compared to the control group. As a result of examining joint condition with 3D micro CT, deformation and destruction of the joint was shown to have decreased. Bone density of ECP group increased at a statistically significant level compared to the control group. Degree of joint inflammation of ECP group decreased significantly compared to the control group. After H&E and M-T staining, infiltration of immune cells, subsidence of the cartilage, damage to the synovial cells and joint erosion decreased. Conclusion : This study showed that ECP hindered the process of rheumatoid arthritis and protected joints and cartilage.

• Applied Chemistry for Engineering
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• v.25 no.3
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• pp.262-267
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• 2014

SAGD (steam assisted gravity drainage) process is the most commonly used in-situ technology for the recovery of bitumen from oil sand. It was investigated that the effects of different additives on bitumen recovery rate from oil sand in SAGD process among many possible mechanisms studied throughout the study. Bitumen recovery from thin layer oil sand reservoirs was simulated by using an experimental SAGD apparatus with scale of 150:1. To improve the simulation accuracy of thin layer oil reservoir, we have attached geological model (GM). Oil sand was simulated by using a mixture of extra heavy oil and glass beads with a diameter of 1.5 mm. $CO_2$ was used as an additive and the evolution of steam chambers were closely monitored, and the effects of $CO_2$ as an additive was investigated. Two types of injection methods were tested; continuous ($cCO_2$-SAGD) and sequential interruption ($sCO_2$-SAGD) $CO_2$ injection. For the $sCO_2$-SAGD experiment, it was observed that the recovery rates and CSOR were efficiently improved control experiment from 60.2% to 69.3% and 7.1 to 6.0, respectively, whereas $cCO_2$-SAGD experiment decreased from 60.2% to 57.6% and 7.1 to 7.3.

• Journal of Korean Society of Forest Science
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• v.110 no.3
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• pp.322-340
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• 2021

Due to climate change and its consequential spring temperature rise, flowering time of Robinia pseudoacacia has advanced and a simultaneous blooming phenomenon occurred in different regions in South Korea. These changes in flowering time became a major crisis in the domestic beekeeping industry and the demand for accurate prediction of flowering time for R. pseudoacacia is increasing. In this study, we developed and compared performance of four different models predicting flowering time of R. pseudoacacia for the entire country: a Single Model for the country (SM), Modified Single Model (MSM) using correction factors derived from SM, Group Model (GM) estimating parameters for each region, and Local Model (LM) estimating parameters for each site. To achieve this goal, the bloom date data observed at 26 points across the country for the past 12 years (2006-2017) and daily temperature data were used. As a result, bloom dates for the north central region, where spring temperature increase was more than two-fold higher than southern regions, have advanced and the differences compared with the southwest region decreased by 0.7098 days per year (p-value=0.0417). Model comparisons showed MSM and LM performed better than the other models, as shown by 24% and 15% lower RMSE than SM, respectively. Furthermore, validation with 16 additional sites for 4 years revealed co-krigging of LM showed better performance than expansion of MSM for the entire nation (RMSE: p-value=0.0118, Bias: p-value=0.0471). This study improved predictions of bloom dates for R. pseudoacacia and proposed methods for reliable expansion to the entire nation.