• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.4
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• pp.827-836
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• 2018

In this study, we developed a PC - based motorcycle simulator based on the development technology of a virtual patrol motorcycle training system. This simulator has been developed to be applied to a variety of fields such as driving training for beginners, driver factor research, and system development such as ABS, which can be seen in advanced models. The weight of the motorcycle operated by the patrol guards is more than 400Kg. There is a lot of risk due to the nature of work without prior practice. Therefore, we implemented a study on the untilization of physical stress and temporal pressure in emergency situations. In order to get a feeling that the motorcycle simulator is operating in real-life, it is important that the mutual reliable signal transmission and operation feel between the driver and the simulator. In order to achieve this, we developed a system that can apply the sub-systems of the actual vehicle to the motorcycle simulator in order to generate the same operation feeling as the actual vehicle. Based on these results, we have developed a method of generating a feedback queue.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.1 no.1
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• pp.91-100
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• 2000

In 1997 the recession of Korean economy brought about the bankruptcy of large corporations and the large size of non-Performing financial assets which led to IMF financial crisis. One of the major reasons for IMF financial crisis was poor loan management of domestic financial institutions . During the restructuring process of financial institutions since the IMF financial crisis, the importance of the loan management has been recognized. Especially. financial institutions' credit allocation had been concentrated on a few big conglomerates and their subsidies as well as some specific business areas. Hence, risk-diversifying portfolio effects were not reflected in any loan portfolios. The IMF financial crisis in 1997 has clearly showed that credit-risk management is essential not only for individuals' loan but also for portfolios consisting of various loans The main objective of this paper is to provide some suggestions on the direction for financial institutions in Korea to improve their loan portfolio management. Particularly, for the effective management of loan portfolios, this paper introduces quantitative credit-risk management schemes such as KMV models and CreditMetrics which are commonly used in financial institutions in advanced countries. Financial institutions in Korea should make their best efforts to establish a more scientific as well as quantitative loan portfolio management.

• Journal of Korean Society of Transportation
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• v.30 no.6
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• pp.71-80
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• 2012

This research suggested a real-time traffic signal control algorithm using individual vehicle travel times on an isolated signal intersection. To collect IDs and passing times from individual vehicles, space-based surveillance systems such as DSRC were adopted. This research developed models to estimate arrival flow rates, delays, and the change rate in delay, by using individual vehicle's travel time data. This real-time signal control algorithm could determine optimal traffic signal timings that minimize intersection delay, based on a linear programming. A micro simulation analysis using CORSIM and RUN TIME EXTENSION verified saturated intersection conditions, and determined the optimal traffic signal timings that minimize intersection delay. In addition, the performance of algorithm varying according to market penetration was examined. In spite of limited results from a specific scenario, this algorithm turned out to be effective as long as the probe rate exceeds 40 percent. Recently, space-based traffic surveillance systems are being installed by various projects, such as Hi-pass, Advanced Transportation Management System (ATMS) and Urban Transportation Information System (UTIS) in Korea. This research has an important significance in that the propose algorithm is a new methodology that accepts the space-based traffic surveillance system in real-time signal operations.

• Journal of Advanced Navigation Technology
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• v.17 no.5
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• pp.516-523
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• 2013

In this paper, The path loss model of Air Traffic Control(ATC) telecommunication radio channel has been studied at the Incheon International Airport(IIA) with the terminal with two antlers. We measured two frequencies among VHF/UHF channel bands. The transmitting site radiated the Continuous Wave(CW). The propagation measurement was taken using the moving vehicle equipped with receiver and antenna. The transmitting power, frequency and antenna height are the same as the current operating condition. The path loss exponent and intercept parameters were extracted by the basic path loss model and hata model. The path loss exponents at passager terminal areas were 3.32 and 3.10 respectively in 128.2 MHz and 269.1 MHz. The deviation of prediction error is 9.69 and 9.65. The new path loss equation at the terminal area was also developed using the derived path loss parameters. The new path loss was compared with other models. This result will be helpful for the ATC site selection and service quality evaluation.

• Korean Journal of Remote Sensing
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• v.15 no.3
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• pp.227-238
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• 1999

In advance of launch, simulated radiances of the Ocean Scanning Multispectral Imager (OSMI) will be very useful to guess the real imagery of OSMI and to prepare for data processing of OSMI. The data processing system for OSMI which is one of sensors aboard Korea Multi-Purpose Satellite (KOMPSAT) scheduled for launch in 1999 is developed based on the SeaWiFS Data Analysis System (SeaDAS). Simulation of radiances requires information on the spectral band, orbital and scanning characteristics of the OSMI and KOMPSAT spacecraft. This paper also describes a method to create simulated radiances of the OSMI over the oceans. Our method for constructing a simulated OSMI imagery is to propagate a KOMPSAT orbit over a field of Coastal Zone Color Scanner (CZCS) pigment concentrations and to use the values and atmospheric components for calculation of total radiances. A modified Brouwer-Lyddane model with drag was used for the realistic orbit prediction, the CZCS pigment concentrations were used to compute water-leaving radiances, and a variety of radiative transfer models were used to calculate atmospheric contributions to total radiances detected by OSMI. Imagery of the simulated OSMI radiances for 412, 443, 490, 555, 765, 865nm was obtained. As expected, water-leaving radiances were only a small fraction (below 10%) of total radiances and sun glint contaminations were observed near the solar declination. Therefore, atmospheric correction is critical in the calculation of pigment concentration from total radiances. Because the imagery near the sun's glitter pattern is virtually useless and must be discarded, more advanced data collection planning will be required to succeed in the mission of OSMI which is consistent monitoring of global oceans during three year mission lifetime.

• Review of Culture and Economy
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• v.21 no.3
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• pp.59-88
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• 2018

This study examines demand of the Korean TV VOD using monthly aggregate data and time series analysis models. In particular, the impact of box office attendance, number of IPTV subscribers, income and price of substitutes on TV VOD market is analyzed. Data on TV VOD download during the period 2013 January to 2018 June are used for the empirical analysis. TV VOD demand shows lower level of seasonality than box office attendance and the share of monthly top1 movie in TV VOD platform is also lower than that of box office attendance. The relationship between a movie's holdback and box office performance does not seem consistent. The empirical result of ARDL model reveals that in the short-run box office attendance, number of IPTV subscribers and price of substitutes have significant impact on TV VOD demand. The result on the long-term relation shows that income is the only determinant of TV VOD demand. The impact of box office attendance on TV VOD is not shown to be robust both for the short-term and long-term.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.3
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• pp.116-126
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• 1993

The finite element method(FEM) has been commonly used for structural dynamic analysis. However, the direct global application of FEM to large complex structures such as ships and offshore structures requires considerable computational efforts, and remarkably more in structural dynamic optimization problems. Adoption of the component-mode synthesis method is an efficient means to overcome the above difficulty. Among three classes of the component-mode synthesis method, the free-interface mode method is recognized to have the advantages of better computational efficiency and easier implementation of substructures' experimental results, but the disadvantage of lower accuracy in analytical results. In this paper, an advanced method to improve the accuracy in the application of the free-interface mode method for the vibration analysis of large complex structures is presented. In order to compensate the truncation effect of the higher modes of substructures in the synthesis process, both residual inertia and stiffness effects are taken into account and a frequency shifting technique is introduced in the formulation of the residual compliance of substructures. The introduction of the frequency shrift ins not only excludes cumbersome manipulation of singular matrices for semi-definite substructural systems but gives more accurate results around the specified shifting frequency. Numerical examples of typical structural models including a ship-like two dimensional finite element model show that the analysis results based on the presented method are well competitive in accuracy with those obtained by the direst global FEM analysis for the frequencies which are lower than the highest one employed in the synthesis with remarkably higher computational efficiency and that the presented method is more efficient and accurate than the fixed-interface mode method.

• Herbal Formula Science
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• v.29 no.4
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• pp.239-252
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• 2021

Objectives : This study is to effect of improving muscle atrophy through water extract on the solid-phase fermentation extraction with Phellinus linteus of discarded Schisandra chinensis in an atorvastatin-induced atrophy C2C12 cell. Methods : C2C12 myoblast were differentiated into myotube by 2% horse serum medium for 6 days, and then treated solid-phase fermentation(S-P) extract at different concentrations for 24h. To investigate the effect of S-P extract on the induction of muscle atrophy and expression of atrophy-related genes and apoptosis in differentiated C2C12 myotubes using a GSH, ROS, real-time PCR, western blots analysis. Results : As a result of treatment with atorvastatin at concentrations of 5, 10, and 20 uM on the 6th day of differentiation in C2C12 myotube cells, it was confirmed that the cell morphology was damaged in a concentration-dependent manner, and the length and thickness of the myotube also decreased in a concentration-dependent manner. Treatment with S-P extract (50, 100 and 200 ㎍/㎖) increased of GSH and inhibited ROS in the atorvastatin-induced muscle atrophy cell model at a concentration that did not induce toxicity. In addition, it was confirmed that it has an effect on muscle reduction by inhibiting apoptosis of muscle cells as well as being involved in protein production and degradation of muscle cells. Conclusions : Atorvastatin-induced atrophy C2C12 cell, S-P extract activates related to differentiation/generation and proteolysis, and inhibits cell death of atrophy in C2C12 cell. Based on this, it is necessary to prove its effectiveness through animal models and human application test, but it is considered to be discarded Schisandra chinensis can present the potential for development as a recycling industrial material.

• Journal of Korean Society of Water and Wastewater
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• v.35 no.6
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• pp.417-424
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• 2021

Algal bloom is an ongoing issue in the management of freshwater systems for drinking water supply, and the chlorophyll-a concentration is commonly used to represent the status of algal bloom. Thus, the prediction of chlorophyll-a concentration is essential for the proper management of water quality. However, the chlorophyll-a concentration is affected by various water quality and environmental factors, so the prediction of its concentration is not an easy task. In recent years, many advanced machine learning algorithms have increasingly been used for the development of surrogate models to prediction the chlorophyll-a concentration in freshwater systems such as rivers or reservoirs. This study used a light gradient boosting machine(LightGBM), a gradient boosting decision tree algorithm, to develop an ensemble machine learning model to predict chlorophyll-a concentration. The field water quality data observed at Daecheong Lake, obtained from the real-time water information system in Korea, were used for the development of the model. The data include temperature, pH, electric conductivity, dissolved oxygen, total organic carbon, total nitrogen, total phosphorus, and chlorophyll-a. First, a LightGBM model was developed to predict the chlorophyll-a concentration by using the other seven items as independent input variables. Second, the time-lagged values of all the input variables were added as input variables to understand the effect of time lag of input variables on model performance. The time lag (i) ranges from 1 to 50 days. The model performance was evaluated using three indices, root mean squared error-observation standard deviation ration (RSR), Nash-Sutcliffe coefficient of efficiency (NSE) and mean absolute error (MAE). The model showed the best performance by adding a dataset with a one-day time lag (i=1) where RSR, NSE, and MAE were 0.359, 0.871 and 1.510, respectively. The improvement of model performance was observed when a dataset with a time lag up of about 15 days (i=15) was added.

• Land and Housing Review
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• v.12 no.2
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• pp.1-12
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• 2021

The purpose of this study is to provide implications for the demonstration and the spread of smart cities. For this, the European Lighthouse project, a well-known smart city initiative, is analyzed. This article investigates agendas, applied solutions, stakeholders and cooperation, and expansion strategies in the 18 Lighthouse projects implemented by the EIP-SCC Smart City Demonstration Project. Four implications are discussed for Korean smart city projects. First, in promoting smart cities, clear philosophies and principles should be established in response to global issues such as climate change. Second, smart cities should be understood as the approaches for problem-solving rather than simply applying advanced technology. Third, a business system should be established in a way to meet the needs of the actors participating in the smart city demonstration project. Finally, an evaluation framework should be established to verify the performance of the project. High-performing best-practice projects should be supported by articulating their standards for their lessons to be spread into other cities. The implications presented here can contribute to developing smart city models along with follow-up studies.