• Journal of Korean Society of Water and Wastewater
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• v.27 no.5
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• pp.555-560
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• 2013

A cost analysis method for pretreament processes of a large scale seawater desalination plant was considered using a cost estimation model, WaTER (Water Treatment Estimation Routine). This model is based on cost functions of U.S. EPA to conduct economic analysis of water treatment facilities. A virtual seawater desalination plant which has pretreatment production capacity of $100,000m^3$ per day was chosen as a model plant. Dual media filtration and microfiltration systems were compared as pretreatment process, and the following reverse osmosis process was modeled. As a result, microfiltration showed a price competitiveness in condition of operating with reverse osmosis process by reducing the loads of water treatment and membrane cleaning despite it's high annual cost.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.55 no.1
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• pp.1-6
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• 2019

The annual production of silver croaker (Argyrosomus argentatus) in Korean towed fishing gears has been increased in recent five years. In 2017, the annual production of silver croaker in metric ton was increased 99.2% compared to 2013. However, the research for silver croaker has been focused on ecology in Korea. There has not been enough research in terms of fishing gears. Therefore, the research for retention probability for towed gears was conducted on covered codend method from June, 2016 to July, 2018. During the experiments, the total catch of silver croaker was 1,563. The geometry of the experimental trawl gear was controlled by trawl monitoring system; net height was 3.3 m, distance of trawldoors was 59.8 m and distance of wing net was 17.3 m. The selection curve for silver croaker was estimated by a logit model. The analysis was applied with the confidence interval to reduce uncertainty of the estimation. The $l_{50}$ was 13.87 cm and its selection range was 2.71 cm. P-value was estimated at 0.99. The mesh size for silver croaker in towed gears needs to be adjusted by considering its minimum maturity length, stakeholder's interests and fisheries regulations.

• The Korean Journal of Ecology
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• v.24 no.1
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• pp.51-59
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• 2001

Estimation of the annual net production, nitrogen (N) and base cation (BC＝K, Mg, Ca) uptake by stocked forests in South Korea has been done with national statistical data of forestry from 1995 to 1999. The annual net production of stems and branches was about 1.8 ton DM ha/sup -1/ yr/sup -1/. The net productivity of deciduous forests was higher than that of coniferous forests. Total net production of the stocked forests from the whole stocked area of South Korea of 6.246×10/sup 6/ ha, was about 1.13×10/sup 7 ton DM/yr, and the total harvested biomass obtained from timber production data in 1999, was estimated about 6.1×105 ton DM/yr that was equivalent to 98 kg DM ha/sup -1/ yr/sup -1/f. Net growth uptake of N and BC were 350 mol ha/sup -1/ yr/sup -1/ and 296 mol ha/sup -1/ yr/sup -1/ respectively, and the content of N and BC contained in the harvested biomass were 20 mol ha/sup -1/ yr/sup -1/ and 16 mol ha/sup -1/ yr/sup -1/ respectively. Net uptake of N was higher than that of BC. Total net uptake of N and BC from growth and harvest by stocked forests in South Korea were 2.309×10/sup 9/ mol/yr and 1.953×10/sup 9 mol/yr respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.1
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• pp.121-126
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• 1998

This study is to examine the energy budget of Hexagrammos agrammus in the natural habitat, based on the von Bertalanffy's growth model using food consumption and growth data of the fish. The fish were collected at the coasts of Tongbaek Island in Pusan and Shinsu Island in Samchonpo, Korea. The standard energy budget model was adopted for this study and the model has the components of toed consumption (C), production (G), assimilation (A), absorption ($A_b$), catabolism (R), excreta (U) and feces (F). These components were expressed as mass unit, not as calorie unit as usual. Both the mass and the proportion of each component varied with age of the fish, The mass of annual excreta declined as the fish became older, while those of the other components increased with the age. The relationship between mean weight (W) and annual absorption ($A_b$) was a non-linear one with the equation of $A_b=4.592W^{0.666}$, while that between mean weight (W) and annual catabolism (R) was linear as R=0.007+0.567W. On the other hand, the annual food consumption (C) showed linear relations both with annual assimilation (A) and annual catabolism (R) as A= -7.026+0.061C and R=-20.749+0.048C, respectively.

• Journal of Ecology and Environment
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• v.33 no.1
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• pp.59-65
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• 2010

Because seagrass production significantly contributes to the biodiversity and production of coastal and estuarine ecosystems, accurate estimation of seagrass productivity is a critical step toward understanding the ecological roles of seagrass in these ecosystems. To develop an accurate and effective method of measuring seagrass productivity, we estimated leaf productivity of eelgrass (Zostera marina) on the southern coast of Korea using three methods, the conventional leaf marking method, the elongation-mass method (Short '87 method), and the plastochrone method. In each season, shoots were pierced through the bundle sheath using a hypodermic needle and were collected after 2-4 weeks had elapsed to estimate their productivity. The leaf elongation and the leaf plastochrone intervals varied significantly among seasons. On an annual basis, the conventional leaf marking method showed the lowest leaf productivity estimates compared to the elongation-mass method and the plastochrone method, suggesting that the conventional leaf marking method underestimated leaf productivity as it ignored leaf maturation processes and new leaf growth within the sheath. Since the elongation-mass method considered leaf maturation processes, this method produced higher leaf productivity estimates than the conventional leaf marking method. On an annual basis, the plastochrone method produced the highest leaf productivity estimates. Below-ground productivity, which can be easily estimated using the plastochrone method, ranged between 3.29 and 5.73 (mg dry weight $shoot^{-1}\;day^{-1}$) and accounted for about 17.8% to 30.3% of total productivity. Because of the high contributions of below-ground productivity to total seagrass production, we suggest that the plastochrone method is an effective and simple technique for assessing both above- and below-ground productivities.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.6
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• pp.946-953
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• 2022

Using the management strategy evaluation methods and data on the Korea chub mackerel Scomber japonicus where the state-space logistic production model is used as the operation and the estimation model respectivley, we examined the effects of both Dorn's rule, α and the buffer value for ABC (allowable biological catch), which are used by the Korea fishery managers for decision rules. We set scenarios that have different pairs of buffer and α values, which include those currently used in the management in Korea. Under each sceanario, we projected the fish population biomass until year 2050, during which ABC is determined in each year with the decision rule. We used three kinds of performance measures: (i) whether the biomass in 2050 is overfished; (ii) the average of annual yields over the simulation period; and (iii) the variability of annual yields over the period. We found that the current practice (buffer=0.9, and α = 0.05) resulted in the best performance in terms of avoiding the "overfished" status. However, the current practice failed to reach the maximum average of the annual yields and led to larger uncertainty in the annual yields.

• Water for future
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• v.24 no.1
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• pp.63-71
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• 1991

This study represents the methodology for feasibility analysis of small hydro power plants. Cumulative density function of Weibull distribution and Thi-essen method were adopted to beside flow duration curve at candidate sites. The performance prediction model and construction cost estimation model for tunnel-type small hydro power plants were developed. Eight candidate sites existing on Han river selected and surveyed for actual sites reconnaissance. The performance characteristics and economical feasibility for these sites were analyzed by using developed models. As a result, it was found that the optimum design flowrates with the lowest unit generation cost for tunnel-type small hydro power plants were the flowrate concerning with between 20 % and 30 % of time ratio on the flow duration curve. Additionally, primary design specifications such as design flowrate, effective head, capacity, annual average load factor, annual electricity production were estimated and discussed for surveyed sites.

• 한국해양학회지
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• v.26 no.2
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• pp.108-116
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• 1991

A production model was constructed by combining the production rate and biomass of Sargassum confusum measured at monthly intervals on the coast of Ohori, Korea, to estimate the algal production for a given period. The production for a certain period, e.g., for a year (P/SUB yr/), was calculated from the equation: P/SUB yr/ = .int.P/SUB t/$.$B/SUB t/dt, where pl and Bl are the production rate and biomass at time t. P/SUB l/ was considered as a function of temperature and light. Photosynthesis-Irradiance curves obtained from the in situ experiments were applied for P/SUB l/ Temperature and light intensity can be expressed as periodic functions of time (T, L=f(t)). Diurnal values of water temperature and light intensity at 3 m depth where S. confusum mainly found were substituted into the equation of P/SUB l/. Simulations using our models show that temperature was one of the most sensitive factors operating on the primary production. Thirty percent decrease of light intensity by cloud cover was estimated to decrease the annual production by 5%.

• Ocean and Polar Research
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• v.43 no.2
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• pp.89-98
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• 2021

The seagrass habitats are a highly productive marine ecosystem which provides nursery ground and shelter for many fish and invertebrate species. Pholis nebulosa (Temminck & Schlegel, 1845) is one of the most abundant seagrass fishes in the coastal waters of Korea. The estimation of fish production is key for devising conservation measures and ensuring fish resources sustainability. A total 894 P. nebulosa ranging from 3.83 to 26.5 cm total length (TL) were collected monthly in 2006 with a small beam trawl in a seagrass bed of southern Korea. Growth parameters of P. nebulosa were estimated using the von Bertalanffy growth model, and production was estimated using a general equation which relates daily fish production to ash-free dry weight (AFDW), biomass, and water temperature. The von Bertalanffy's growth equation was estimated as: L_t = 28.3823(1-e^{-0.7835(t+0.9864)}). The densities, biomass, daily, annual production, and P/B ratio were 0.069±0.061/m^-2, 1.022±0.621 g/m², 0.005±0.004 g AFDW/m²/day, 1.676 g AFDW/m²/yr, and 1.641, respectively. Monthly variation in production of P. nebulosa peaked during March and April 2006 (0.0139 and 0.0111 g AFDW/m²/day), whereas the lowest value of 0.0005 g AFDW/m²/day was in December. Monthly change in production of P. nebulosa was positively correlated with biomass and condition factor. Our results will contribute to the conservation of seagrass ecosystems, which are still undisturbed in the study area.

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