• Journal of Advanced Navigation Technology
• /
• v.25 no.6
• /
• pp.441-449
• /
• 2021

With advances in autonomous vehicles, there is a growing demand for more accurate position estimation. Especially, this is a case for a moving robot for the indoor operation which necessitates the higher accuracy in position estimation when the robot is required to execute the task at a predestined location. Thus, a method for improving the position estimation which is applicable to both the fixed and the moving object is proposed. The proposed method exploits the initial position estimation from Bluetooth beacon signals as observation signals. Then, it estimates the gravitational acceleration applied to each axis in an inertial frame coordinate through computing roll and pitch angles and combining them with magnetometer measurements to compute yaw angle. Finally, it refines the control inputs for an object with motion dynamics by computing acceleration on each axis, which is used for improving the performance of Kalman filter. The experimental assessment of the proposed algorithm shows that it improves the position estimation accuracy in comparison to a conventional Kalman filter in terms of average error distance at both the fixed and moving states.

• Journal of Energy Engineering
• /
• v.22 no.4
• /
• pp.370-375
• /
• 2013

This paper attempts to estimate the city gas demand function in Korea over the period 1981-2012. As the city gas demand function provides us information on the pattern of consumer's city gas consumption, it can be usefully utilized in predicting the impact of policy variables such as city gas price and forecasting the demand for city gas. We apply lagged dependent variable model and ordinary least square method as a robust approach to estimating the parameters of the city gas demand function. The results show that short-run price and income elasticities of the city gas demand are estimated to be -0.522 and 0.874, respectively. They are statistically significant at the 1% level. The short-run price and income elasticities portray that demand for city gas is price- and income-inelastic. This implies that the city gas is indispensable goods to human-being's life, thus the city gas demand would not be promptly adjusted to responding to price and/or income change. However, long-run price and income elasticities reveal that the demand for city gas is price- and income-elastic in the long-run.

• Korean Journal of Agricultural Science
• /
• v.10 no.2
• /
• pp.393-405
• /
• 1983

The demand for livestock and poultry products including beef, pork, chicken, egg and milk whose income elasticities are relatively higher than other staple foods, has been increased significantly during the past two decades in response to the remarkable increase in per capita GNP. This trend will be continued during the fifth and the sixth five year economic development plan period beginning with 1982. The annual GNP growth rate will be 7.5% on the average during the next 10 years. It is greatly needed to estimate the demand for beef, pork, chicken egg and milk and to study the feasibilities of domestic production of livestock products for the formulation of adequate policies in order to equate the consumption and the production during the 1980s. So this study reviewed the possible changes in the food consumption patterns during the 1980s, estimated the demand for beef, pork, chicken, egg and milk by using empirical demand functions and finally made suggestions for the formulation of long term price stabilization policies for each livestock, poultry and dairy products through the equilibrium of the quantity of demand for and supply of the products. There are many factors affecting the demand for meats, but this study considered own price, prices of supplements and substitutes and per capita income as the independent variables in the demand equations. It was found that it's own price and income were most significantly affecting factors among others and the degree of substitution effects were remarkably different among the products. According to the meat demand derived in this study, per capita consumption of beef, pork and chicken in the base year 1982 was 11.2kg for total meat, 2.5kg beef, 6.0kg pork and 2.5kg chicken, 106 pieces egg, 15.1kg milk respectively, while those in 1991 were 19.3kg for total meat, 4.8kg beef, 9.6kg pork, 4.9kg chicken, 133pieces egg and 44.1kg milk. It is also predicted through this study that, when the level of production costs be maintained, the domestic production of pork and chicken will meet the demand for them during the fifth and sixth five year economic plan period. However, there will be chronic shortage of beef supply during the coming years. The annual import requirement will be 30,000tons to 40,000tons during the period. In order to stabilize the domestic livestock and poultry and dairy products market, the government should introduce measures to curb the increase in beef consumption by encouraging the consumption of pork and chicken. For this, the livestock production policy measures should be concentrated on : 1) the improvement of infrastructures of beef production by introducing advanced feeding and management technology, subsidies for the establishment of facilities and price support programs for farmers : 2) the development of dairy beef : 3) the reinforcement of the forecast systems for pork and chicken production and consumption.

• Economic Analysis
• /
• v.25 no.1
• /
• pp.34-65
• /
• 2019

This paper investigates the effects on Korean exports of demand in developed economies, and how these effects have changed since the global financial crisis. As a measure of import demand, we use import intensity-adjusted demand to take into account heterogenous import intensities across components of aggregate demand. Our estimation of a dynamic panel regression model reveals that Korea's exports to the G7 countries were elastic with respect to the import demand of these countries until the global financial crisis, but have shifted to become inelastic since. Furthermore, we separately estimate the effects of the different components of the G7 countries' aggregate demand (private consumption, public consumption, investment and exports). The results show that the decrease in private consumption in the G7 countries during the crisis had a significant impact in causing the decline in Korea's exports to them, but that the increase in their public consumption since the crisis has had a significant effect on driving increased Korean exports to them. The effects of the G7 countries' exports on Korea's exports to them remain positive and significant during both the pre- and post-crisis periods. The effects of the G7 countries' investments on Korea's exports are also positive and significant, but the positive effect has weakened since the crisis. Our findings suggest that the overall effect of changes in the G7 countries' import demand on Korea's exports to them has weakened compared to the pre-crisis period.

• Earthquakes and Structures
• /
• v.12 no.3
• /
• pp.321-332
• /
• 2017

The reverse fault is a dangerous geological hazard faced by buried steel pipelines. Permanent ground deformation along the fault trace will induce large compressive strain leading to buckling failure of the pipe. A hybrid pipe-shell element based numerical model programed by INP code supported by ABAQUS solver was proposed in this study to explore the strain performance of buried X80 steel pipeline under reverse fault displacement. Accuracy of the numerical model was validated by previous full scale experimental results. Based on this model, parametric analysis was conducted to study the effects of four main kinds of parameters, e.g., pipe parameters, fault parameters, load parameter and soil property parameters, on the strain demand. Based on 2340 peak strain results of various combinations of design parameters, a semi-empirical model for strain demand prediction of X80 pipeline at reverse fault crossings was proposed. In general, reverse faults encountered by pipelines are involved in 3D oblique reverse faults, which can be considered as a combination of reverse fault and strike-slip fault. So a compressive strain demand estimation procedure for X80 pipeline crossing oblique-reverse faults was proposed by combining the presented semi-empirical model and the previous one for compression strike-slip fault (Liu 2016). Accuracy and efficiency of this proposed method was validated by fifteen design cases faced by the Second West to East Gas pipeline. The proposed method can be directly applied to the strain based design of X80 steel pipeline crossing oblique-reverse faults, with much higher efficiency than common numerical models.

• Korean Journal of Soil Science and Fertilizer
• /
• v.9 no.3
• /
• pp.201-210
• /
• 1976

Only 22.7% of total land area is arable land in Korea, it is anticipated that the increased land utilization of present arable land and enlargement of arable land through the reclamation of hillside and tidal land will be of great importance for the support of increased population in the future. Followings are the prediction of increased land utilization ratios, increased arable land through the reclamation of hillside and tidal land, and the increase] in fertilizer demand up to the year of 2000. 1. On the assumption that irrigation facilities, farm mechanization, and cropping systems would be improved remarkably by the year of 2000, the land utilization ratios of paddy land and upland are estimated to be 179% and 193% respectively. 2. Increments of fertilizer demand due to increased land utilization ratios, are estimated to be 2, 290 M/T in 1980, 70, 611 M/T in 1990, and 153, 619 M/T in 2000, when the amounts of fertilizers per unit area are fixed at present lrevels. 3. Increments of fertilizer demand due to the expansion of arable land through the reclamation of 516,330 ha of hillside land and 160,568 ha of tidal land, which are the present estimation of the reclaimable areas, are estimated as 32,960 M/T in 1980, 136,320 M/T in 1990, and 366,861 M/T in 2000. 4. Total increments of fertilizer demand due to the increased land utilization of arable land and the expansion of arable land through the reclamation of hillside and tidal lands in 2000's are estimated as 196,285 M/T for N, 147,351 M/T for $P_2O_5$, and 176,844 M/T for $K_2O$.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.11
• /
• pp.7781-7787
• /
• 2015

The purpose of This paper is to address the development on supply-demand outlook model of aqua-cultured korean Flatfish and introduces a projection of supply-demand and market prices during 2015-2017 using developed model. The supply-demand outlook model is composed as a partial equilibrium model of Korean Flat fish. Each equation in the model is estimated by the econometric techniques. A reviews of the demand-outlook model stability is also carried out by the references based on RMSPE. MAPE, and Theil's inequality coefficients. According to the reference of RMSPE, the error rates of the forecasting values of the aqua culture area, culturing quantity, production quantity, market price show less than 4%, The production quantity and farm price are predicted respectively to be 42,561MT and 10,191KW per kg in 2017.

• Resources Recycling
• /
• v.28 no.3
• /
• pp.68-76
• /
• 2019

It is very necessary for the metal recycling industries and the researchers to understand the current status of demand and supply of non-ferrous metals and their scraps. Domestic demand and supply of non-ferrous metals and their scraps have been surveyed and reported on the journal of the Korean Institute of Resources Recycling since ten years before. However, it was confined to six major non-ferrous metals such as copper, aluminum, zinc, lead, nickel and magnesium because there are so many kind of non-ferrous metals. In this article also, demand and supply of these non-ferrous metals in addition tin during recent five years (2014 ~ 2018) in Korean markets were reviewed, and their recycling ratio of scraps were briefly estimated. The statistical data were mainly cited from the data issued by Korea Customs Service (KCS) and Korea Non-Ferrous Metal Association, and some fragmental published review articles from magazines and other technical reports.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2020.06a
• /
• pp.119-119
• /
• 2020

Globally, the demand for food and water resources are increasing rapidly with the growing concerns of meeting the projected population upsurge, specifically by 2050. The global population is projected to hit 9.8 billion in 2050 while the food demand is expected to increase by 77% from the 2007 base year. Moreover, the already scarce water resources, especially in the food-producing regions, expected to be significantly affected as food production already accounts for over 70% of the global water resources. However, the estimated food demand encapsulated the actual demand for both human consumption and animal feed in addition to the exuberant food waste at the consumption stage of the supply chain, notably in the developed countries. Managing the food consumption demand and food waste can have across-the-board benefits on water resources and other associated food production impacts. This study assessed the water-saving potentials through food waste in Korean households using the food waste data obtained from the direct weighing analysis. The household food waste collection and characterization were carried out during the summer (July), fall (September), and winter (December) seasons of 2019. The water footprint related to the food waste within Korean households was based on the water footprint concept, i.e. indirect water use. The results of our estimation showed that an average Korean household wasted 6.15 ± 4.36 kg daily, amounting to 12.53 ± 11.10 m3 of water resources associated with the waste. On the per capita basis, an average of 0.024 ± 0.017 kg/capita/day of food was wasted resulting to 0.049 ± 0.044 m3/capital/day of water resources wasted. The food waste types that accounted for the principal share in the water footprint were beef, soybean, rice and pork with values 30.7, 10.1, 9.6, and 7.5%, respectively. Considering that the production of meat and meat products are water intensive and the agricultural water use in Korea is largely for rice production, addressing the food waste of these two important agricultural products can be a hotspot for water saving potential in the country. This study therefore provides an insight to addressing the water scarcity in the country through reducing household food waste.

• Korean Circulation Journal
• /
• v.54 no.1
• /
• pp.1-12
• /
• 2024

Background and Objectives: The objective of this study was to estimate the supply and demand for cardiologists in Korea and provide evidence for healthcare policy to ensure a stable and adequate workforce for optimal cardiovascular disease management. Methods: Past trends of inflow and outflow of cardiologists were used to make crude projections, which were then adjusted based on demands of services to obtain final projections. Inflow of cardiologists was estimated using second-order polynomial regression and demand for cardiology care was estimated using linear regression. Results: There were 1,139 active cardiologists who were under the age of 65 in clinical practice in Korea. The estimated number of cardiologists from 2022 to 2040 showed that the number of cardiologists would peak at 1,344 in 2032 and gradually decrease thereafter. We also estimated an increase of 947,811 cases of heart-related procedures annually from 2023 to 2032. The number of heart-related procedures per cardiologist would increase 1.4 times from 12,964 in 2023 to 17,862 in 2032. The estimated number of emergency patients per cardiologist under 50 years old would almost double from 544 in 2022 to 987 in 2032. Conclusions: We expect significant shortage of cardiologists in Korea within the next 10 years. The number of emergency patients per cardiologist will increase by nearly 50%, leading to high individual workload for cardiologists. To prevent this imbalance between supply and demand, an organized and collective approach by the specialty of cardiology is imperative to produce a balanced workforce.