• Journal of Korean Society of Transportation
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• v.19 no.6
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• pp.89-102
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• 2001

Using a multiproduct translog cost function model, this paper examines the existence or absence of scale and scope economies in Seoul's urban bus industry. The Paper then conceptualizes that the bus firm produces three outputs (city, seat and local bus-kilometers) using low input factors(labor, capital, fuel and maintenance). Using 1996 annual observations for 81 Seoul's bus firms, the equation system consisting of a cost function and three input share equations is estimated with the nonlinear iterative Zellner method. The findings show that the cost function corresponding to a non-homothetic production technology with separability between local bus outputs and inputs adequately represents the structure of cost for Seoul's bus firms, and that the demand lot all input factors is quite inelastic with respect to their own price. On the other hand, nearly all firms experience mild overall economies or scale, but rather marked product-specific economies of scale with respect to all the three outputs. In addition, there appear to be substantial economies or scope associated with the joint production of city and seat bus services, while considerable diseconomies of scope associated with that of city and local bus services. These results indicate that the merger of smaller firms into larger firms with a fleet of approximately 200 buses would result in more cost-efficient bus services.

• Journal of Korean Society of Transportation
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• v.22 no.6
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• pp.159-173
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• 2004

Using a generalized translog multiproduct cost function model, this paper examines economies of scale and scope in the vertically-integrated Korean railway industry. The paper then conceptualizes that the Korea National Railroad (KNR) produces four outputs (passenger-kilometers, ton-kilometers of freight, average length of passenger trips, and average length of freight haul) using three input factors(labor, fuel and maintenance, and rolling stock and capital). Using time series data collected from the KNR's annual records for the years from 1977 to 2002, the simultaneous equation system consisting of a cost function and two input share equatins is estimated with the Zellner's iterative seemingly unrelated regression. The findings show that the cost function corresponding to a non-Cobb-Douglas, non-homothetic, and non-homogeneous production technology adequately represents the KNR's cost structure. On the other hand, the Korean railway industry experiences sizeable overall scale economies, which result from substantial product-specific scale economies associated with passenger-kilometers and freight ton-kilometers and from scope economies associated with their joint production. In addition, the magnitude of economies of scope is influenced largely by the ratio of passenger trips, and has increased over time as the former has increased while the latter has decreased.

• Journal of Korean Society of Forest Science
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• v.73 no.1
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• pp.70-75
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• 1986

The secular trend and seasonal variation of chestnut prices have been analyzed, and the production and price for the next two decades (1985-2004) have been forecasted by the derived equation model. The results of the study can be summarized as follows; 1) The chestnut prices went up at the rate of 10.95% per annum during 1965-1972, but, due to excessive supply of chestnuts, went down at the rate of 7.25% during 1973-1984. 2) In a year, the prices were lowest at the harvesting season, especially on October, and highest on July. Such a seasonal fluctuations of chestnut prices tend to be even with the passage of time, but the range of fluctuation is still wide. 3) It was forecasted under certain premises that the annual chestnut production will be increased by 99,000 tons in 1992, but the amount will fall rapidly to about 23,000 tons in 2004. The prices will be similar to the present level or have slightly upward Tendency until 1992, but this will be rapidly raised thereafter.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.5
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• pp.379-384
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• 2009

This study was carried out to understand the national and regional distribution of the biomass resources produced in Korea annually via establishing database (DB) and distribution maps of biomass resources data including as livestock manures, food wastes and agricultural by-product. The information of the annual production of each biomass resources was obtained from Ministry for Food, Agriculture, Forestry and Fisheries (MIFAFF), Ministry of Environment (MOE) and National Statistical Office (NSO). Based on biomass resources data, we established database architecture table about livestock manures and food wastes. The distribution maps for the total amount of manures produced from each livestock animal were built up in both national and regional scales and used for analysis of the space-based and time-based distribution of the manure resources. Distribution maps for food wastes and agricultural by-product were also produced, respectively. It was shown that the analysis through resource mapping can be used to identify the sources of collectable biomass feasibly determining suitable region for establishment of a biomass-energy production. The biomass distribution maps graphically provide the information regarding biomass resources to policy-makers, farmers, general users and it was expected to be utilized for policy-making of environmental-friendly agriculture and bio-energy.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.2
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• pp.168-174
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• 2021

According to the World Agricultural Productivity Report, the current annual average growth rate of agriculture is 1.63%, which is lower than 1.73% to support the world's 10 billion people, which is growing by 2050. The demand for food, feed, and bioenergy is not growing enough to continue to meet the demand, and it is predicting a future food shortage. The purpose of this study was to create a regional irrigation control model for the purpose of reducing the production cost of crops, increasing production, and improving quality, and presenting a model that can give advice to farmers who start farming in the region. The irrigation control modeling presented in this study means to represent the change of medium weight·supply liquid·drainage amount due to changes in the root zone environment according to the passage of time and climate in a graph model. For water control modeling, we collected data on the change in the amount of the root zone environment and the weight of the badge·supply amount·drainage amount from March to June in Nonsan, Buyeo, and Yesan regions in Chungnam Province through the measuring device of the Ministry of Environment in the root region. We set up the parameters for derivation and derived an irrigation control model that can confirm the change in weight·supply liquid·drainage amount over time through the parameters.

• Journal of Mushroom
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• v.18 no.4
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• pp.303-310
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• 2020

The cultivation of Sparassis crispa in the beginning of the 2000s in South Korea, and the cultivar 'Neowul' bred in the Chonbuk Agricultural Research and Extension Service were registered first in 2016. However, there is no manual for the cultivation of Sparassis crispa, and therefore, there remains a big difference in its harvest rate across farms. Herein, we aimed to study the primordium formation conditions of Sparassis crispa 'Neowul' according to the medium pH, medium moisture content, and inoculum volume of liquid spawn and develop a stable production technology. We found the annual yield per bottle relating to the cultivation period, harvest rate, and the weight of fruiting body to be the highest at 363.6 g in the area cultivated at pH 3.8. However, it is thought that cultivation by adjusting the pH to 3.9±1 would be necessary for stable production, considering that at pH 3.6, the yield sharply reduced to 189.5 g. Moreover, the culture period was shorter at pH 4.0 compared with that at pH3.8, and the cultivation period at pH 4.0 was the same as that at pH 3.8. No significant difference in the weight of the fruiting body at different conditions was recognized. Additionally, it is difficult to regulate the pH precisely in practical applications in the farms. It is thought that 341.8 g Sparassis crispa will be produced per bottle annually if the medium moisture content is adjusted to 65%, liquid spawn inoculum volume is equivalent to 4% of the medium volume, and the humidity in the culture room is set to below 50%.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.12
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• pp.963-969
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• 2021

The wind data measured from local meteorological masts is used to evaluate wind speed distribution and energy production in the specified site for wind farm However, wind data measured from meteorological masts often contain missing information or insufficient desired height or data length, making it difficult to perform wind turbine control and performance simulation. Therefore, long-term continuous wind data is very important to assess the annual energy production and the capacity factor for wind turbines or wind farms. In addition, if seasonal influences are distinct, such as on the Korean Peninsula, wind data with seasonal characteristics should be considered. This study presents methodologies for generating synthetic wind that take into account fluctuations in both wind speed and direction using the hidden Markov model, which is a statistical method. The wind data for statistical processing are measured at Maldo island in the Kokunnsan-gundo, Jeonbuk Province using the Automatic Weather System (AWS) of the Korea Meteorological Administration. The synthetic wind generated using the hidden Markov model will be validated by comparing statistical variables, wind energy density, seasonal mean speed, and prevailing wind direction with measurement data.

• Journal of the Korean Society of Radiology
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• v.17 no.1
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• pp.79-90
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• 2023

The study is to estimate the social costs of premature deaths due to nuclear power plant(NPP) accidents, by resorting to the contingent valuation method(CVM) which is used to estimate the value of a statistical life(VSL). The VSL estimate is about 3.55 billion won, which is multiplied by some 1.8 million premature deaths due to the accidents in world history of NPP, to get a maximum social cost of 1,952 trillion won. This estimate is equivalent to the 2022 real GDP of Korea. The annual average number of premature deaths and the resulting average social cost is 26,000 and 28 trillion won, respectively. The social cost of premature deaths due not only to accidents, but also the air pollutants from fired power plants(FPP) during 1987~2021 is estimated to be 26,919 trillion won. This is equivalent to 2021 US GDP, and is about 3,000 times higher than that for NPP of 9 trillion won. In 2021, the estimated social costs of FPP and NPP are 1,075 trillion won and 292 billion won, respectively. For South Korea, the study suggests to adapt an energy mix of increased share of electricity production for NPP relative to FPP, given that the 2050 carbon neutrality strategy of Korea is expected to lead to an increased share of renewable energy in electricity production. The study emphasizes accumulating the number of CVM-based VSL studies to ensure efficient energy policies.

• Economic and Environmental Geology
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• v.57 no.1
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• pp.83-91
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• 2024

According to the IEA (2022), global rechargeable battery demand is expected to reach 1.3 TWh in 2040. EV batteries will account for about 80% of this demand, and used EV batteries are expected to be discharged after 30 years. Used EV batteries can be recycled and reused to create new value. They can also resolve one of the most vulnerable parts of the battery supply chain: raw material insecurity. In this study, we analyzed the amount of used batteries generated by EV in Korea and their potential for reuse and recycling. As a result, it was estimated that the annual generation of used batteries for EV began to increase to more than 100,000 in '31 and expanded to 810,000 in '45. In addition, it was found that the market for recycling EV batteries in '45 could be expected to be equivalent to the production of 1 million batteries, and the market for reuse could be expected to be equivalent to the production of 36 Gwh of batteries. On the other hand, according to the plan standard disclosed by the recycling company, domestic used EV batteries can account for 11% of the domestic recycling processing capacity (pre-treatment) ('30). So it will be important to manage the import and export of used batteries in terms of securing raw materials.

• Korean Journal of Soil Science and Fertilizer
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• v.9 no.3
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• pp.149-163
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• 1976

In Korea, the ever-increasing population has become a serious problem and the decreasing of cultivated lard area per person has become a major concern. Therefore, today we are implementing a green revolution using miracle varieties which require more fertilizer. The increased use of fertilizer along with development and adoption of high yielding varieties is the key to carrying out this green revolution. Fertilizer consumption in Korea is mainly influenced by agricultural techniques, fertilizer prices and government policies for increasing food production. If there are no special change, such as a cataclysm or an exhaustion of resources, it is quite clear that the fertilizer demand will increase to the near maximum ceiling point of optimum levels for crops in the year 2000. Fertilizer demand is not the amount of fertilizer that will be used by the farmer, but the actual optimum amount of plant nutrients required for maximum production. In this report, two alternative strategies are consideded in forecasting the future feitilizer demands. Alternative I is projected by reviewing consumption amounts over the last 10 years (1966~75) in Korea. The annual rate of increase in fertilizer consumption for the last 10 years was approximately 8.7% (table 1). Plant nutrient consumption rates in later years have been more balanced, and also fertilizer consumption per total acreage is considerably higher in Korea than in other countries (table 11), consequently the rate of increase in the future is expected to decline. Looking at the long term projections, the average annual rate of increase is expected to be 7% for 1976~80, 2.5% for 1981~90, 1.5% for 1991~2000. Thus, total projected fertilizer demands are estimated at 1,208,000M/T by 1980, 1,547,000M/T by 1990, 1,795,000M/T by 2000 (table 16). Alternative II is based on projected optimum fertilizer levels for crops and on increased crop acreage. The government recommended fertilizer rate has increased by a factor of 0.99 to 5.49 over the past twelve years depending on the specific crops (table 4). Levels of fertilizer demand recommended by government (table 7) in 1976 are still low compared with actual optimum fertilizer demands for crops (table 5). Therefore, future incaeases in fertilizer usage are anticipated. Thus, total projected fertilizer demands are estimated at 1,229,000M/T by 1980, 1,493,000M/T by 1990 and 1,898,000M/T by 2000(table 16).