• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.8
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• pp.681-688
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• 2021

This paper considers the trajectory and impact point dispersion analysis of the test launch vehicle (TLV). The analysis, which performed before and after its flight test on November 28, 2018, is described and verified by comparing with the flight test results. The six degree-offreedom (DOF) simulation is used to compute the dispersion of the trajectory, attitude, and impact point, where the launch vehicle performance variations and wind effects during the atmospheric phase are included. The impact area to guarantee the flight safety is determined using the results of the dispersion analysis. The flight test results confirm that the safe flight of TLV is performed within the predicted dispersion boundary.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.483-491
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• 2019

The aim of this study is to shed light on factors that influence securing of university research grants. For this purpose, this study emphasizes the role of management capability of industry-university cooperation foundation in securing research grants. We analyze whether the potential capabilities influence research grants using panel data from 194 universities during 2016 to 2018. The results obtained from the Driscoll & Kraay standard errors (DKSE) indicate that a number of variables including the portion of industry-university collaboration professors, academic performance of professors, and the number of paid researchers are positively associated with the amount of external research grant approved. However, the percentage of employees employed for less than two years is negatively related with securing external research grants. Once the dependent variable is measured by the total university research grants, the negative coefficient of employees with short-term career disappears. Instead, the percentage of employees who are in charge of research planning and management and the total number of employees involved in industry-university collaboration foundations are negatively related with the total university research grant amounts.

• Journal of Convergence for Information Technology
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• v.8 no.6
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• pp.135-142
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• 2018

In recent years, researches utilizing UAV for military purposes such as precision tracking and batting have been actively conducted. In order to track the preceding flight, there has been a previous research on estimating the attitude information of the flight such as roll, pitch, and yaw using images taken from the rear UAV. In this study, we propose a method to estimate the attitude information more precisely by applying the Kalman filter to the existing image processing technique. By applying the Kalman filter to the estimated attitude data using image processing, we could reduce the estimation error of the attitude angle significantly. Through the simulation experiments, it was confirmed that the estimation using the Kalman filter can estimate the posture information of the aircraft more accurately.

• Journal of Korea Port Economic Association
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• v.37 no.3
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• pp.1-17
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• 2021

Forecasting the daily volume of container is important in many aspects of port operation. In this article, we utilized a machine-learning algorithm based on decision tree to predict future container throughput of Busan port. Accurate volume forecasting improves operational efficiency and service levels by reducing costs and shipowner latency. We showed that our method is capable of accurately and reliably predicting container throughput in short-term(days). Forecasting accuracy was improved by more than 22% over time series methods(ARIMA). We also demonstrated that the current method is assumption-free and not prone to human bias. We expect that such method could be useful in a broad range of fields.

• Korean Journal of Culture and Social Issue
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• v.25 no.4
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• pp.305-323
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• 2019

The Satisfaction With Life Scale (SWLS) is the most widely used instrument to measure life satisfaction. This study examined the factor structure and measurement equivalence of SWLS across age and gender in Korea. A total of 936 data were analyzed, comprising 433 college students (195 males and 238 females) and 503 middle-aged adults (237 males and 266 females). The results are as follows. Firstly, the data supported a modified single-factor model with correlations between error variances of items 4 and 5. Therefore, items 4 and 5 reflecting the past were found to share a distinct meaning with other items. Secondly, SWLS showed full strict invariance by gender, but only showed partial strict invariance between college students and middle-aged adults. These results indicate that meaningful comparisons of SWLS scores across gender may be valid, but careful attention should be paid when comparing age groups.

• Journal of agricultural medicine and community health
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• v.36 no.2
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• pp.87-100
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• 2011

Objectives: This study aimed to identify factors associated with smoking relapse. Methods: The study sample was recruited among subjects who were enrolled in the smoking cessation clinic of a public health center and had succeeded in quitting smoking for at least six months. A total of 159 male subjects were followed via mail survey one year later. The independent variables in the analyses were socio-demographic characteristics, smoking history and behavior, receipt of smoking cessation aids, health behaviors and components of the health belief model (HBM). The dependent variable was smoking relapse assessed one year after quitting. Ordered logit regressions were used to identify factors associated with smoking relapse. Results: The relapse rate of the ex-smokers in our sample was 25.8%, and the occasional smoking rate was 17.0%. Univariate analyses revealed that only factors related to the HBM, such as perceived susceptibility to diseases (p<0.01), perceived severity of diseases (p<0.01), perceived health benefits of not smoking (p<0.01), perceived barriers to quitting smoking due to increasing stress and difficulty in social life (p<0.01), and self-efficacy (p<0.01) were associated with the likelihood of relapse for ex-smokers. Ordered logit analyses yielded two significant factors affecting the likelihood of relapse, the perceived barriers to quitting smoking and self-efficacy. Conclusions: Our results indicate that higher levels of barriers to quitting smoking and lower levels of self-efficacy were significantly related to risk of smoking relapse. These findings may be useful for identifying those at highest risk for relapse and choosing the optimal strategies for prevention of relapse for ex-smokers.

• International Journal of Highway Engineering
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• v.12 no.4
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• pp.93-100
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• 2010

Trip generation is the first step in the conventional four-step model and has great effects on overall demand forecasting, so accuracy really matters at this stage. A linear regression model is widely used as a current trip generation model for such plans as urban transportation and SOC facilities, assuming that the relationship between each socio-economic index and trip generation stays linear. But when rapid urban development or an urban planning structure has changed, socio-economic index data for trip estimation may be lacking to bring many errors in estimated trip. Hence, instead of assuming that a socio-economic index widely used for a general purpose, this study aims to develop a new trip generation model by type based on the market separation for the variables to reflect the characteristics of various zones. The study considered the various characteristics (land use, socio-economic) of zones to enhance the forecasting accuracy of a trip generation model, the first-step in forecasting transportation demands. For a market separation methodology to improve forecasting accuracy, data mining (CART) on the basis of trip generation was used along with a regression analysis. Findings of the study indicated as follows : First, the analysis of zone characteristics using the CART analysis showed that trip production was under the influence of socio-economic factors (men-women relative proportion, age group (22 to 29)), while trip attraction was affected by land use factors (the relative proportion of business facilities) and the socio-economic factor (the relative proportion of third industry workers). Second, model development by type showed as a result that trip generation coefficients revealed 0.977 to 0.987 (trip/person) for "production" 0.692 to 3.256 (trip/person) for "attraction", which brought the necessity for type classifications. Third, a measured verification was conducted, where "production" and "attraction" showed a higher suitability than the existing model. The trip generation model by type developed in this study, therefore, turned out to be superior to the existing one.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.3
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• pp.281-293
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• 2020

Recently, large and small fires have been happening more often in Korea. Fire is one of the most frequent disasters along with traffic accidents in korean cities, and this frequency is closely related to the land use and the type of facilities. Therefore, in this study, the significance of fires was analyzed by considering land use, facility types, human and social factors and using 10 years of fire data in Jinju city. Based on this, OLS (Ordinary Least Square) regression analysis, SLM (Spatial Lag Model) and SEM (Spatial Error Model) using space weights, were compared and analyzed considering the location of the fire and each factor, then a statistical model with high suitability was presented. As a result, LISA analysis of spatial distribution patterns of fires in Jinju city was conducted, and it was proved that the frequency of fires was high in the order as follow, central commercial area, industrial area and residential area. Multiple regression analysis was performed by integrating demographic, social, and physical variables. Therefore, the three models were compared and analyzed by applying spatial weighting to the derived factors. As a result of the significance test, the spatial error model was analyzed to be the most significant. The facilities that have the highest correlation with fire occurrence were second type neighborhood facilities, followed by detached house, first type neighborhood facilities, number of households, and sales facilities. The results of this study are expected to be used as significant data to identify factors and manage fire safety in urban areas. Also, through the analysis of the standard deviation ellipsoid, the distribution characteristics of each facility in the residential area, industrial area, and central commercial area among the use areas were analyzed. In, the second type neighborhood facility with the highest fire risk was concentrated in the center. The results of these studies are expected to be used as useful data for identifying factors and managing fire safety in urban areas.

• Geophysics and Geophysical Exploration
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• v.23 no.4
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• pp.243-252
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• 2020

To share an understanding of trajectory measurement in surveys using borehole, this tutorial summarizes the relevant mathematical principles of the borehole deviation survey based on coordinate transform. For uncased or open holes, calculations of the azimuth-deviation-tool face rotation using three-component accelerometer and magnetometer measurements are summarized. For the steel-cased holes, calculations are based on the time-derivative formula of the coordinate transform matrix; yaw-pitch-roll angles through time are mathematically determined by integrating the threecomponent angular velocity measurements from the gyroscope while also removing the Earth's rotation effect. Sensor and data fusion to increase the accuracy of borehole deviation survey is explained with an example of the method. These principles of borehole deviation surveys can be adapted for attitude estimation in air-borne surveys or for positioning in tunnels where global positioning system (GPS) signals cannot be accessed. Information on the optimization filter that must be incorporated in sensor fusion is introduced to help future research.

• Journal of radiological science and technology
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• v.37 no.4
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• pp.273-278
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• 2014

Bone density measurement use of diagnosis of osteoporosis and it is an important indicator for treatment as well as prevention. But errors in degree of precision of BMD can be occurred by status of patient, bone densitometer and radiological technologist. Therefore the author evaluated that how BMD changes according to the condition of the patient. As Lumbar region, which could lead to substantial effects on bone density by diverse factors such as the water, food, intentional bowels. We recognized a change of bone mineral density in accordance with the height of the water tank and in the presence or absence of the gas using the Aluminum Spine Phantom. We also figured out the influence of bone mineral density by increasing the water and food into a target on the volunteers. Measured bone mineral density through Aluminum Spine Phantom had statistically significant difference accordance with increasing the height of water tank(p=0.026). There was no significant difference in BMD according to the existence of the bowl gas(p=0.587). There was no significant difference in a study of six people targeted volunteers in the presence or absence of the food(p=0.812). And also there was no significant difference according to the existence of water(p=0.618). If it is not difficult to recognize the surround of bone in measuring BMD of lumbar bone, it is not the factor which has the great effect on bone mineral density whether the test is after endoscopic examination of large intestine and patient's fast or not.