• 한국환경과학회지
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• 제25권10호
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• pp.1433-1444
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• 2016

South Korea is a maritime nation, surrounded by water on three sides; hence, it is important to preserve in a sustainable manner. Most areas, especially those bordering the East Sea, have been suffering from severe coastal erosion. Information on the sediment yield of a river basin is an important requirement for water resources development and management. In Korea, data on suspended sediment yield are limited owing to a lack of logistic support for systematic sediment sampling activities. This paper presents an integrated approach to estimate the sediment yield for ungauged coastal basins by using a soil erosion model and a sediment delivery rate model in a geographic information system (GIS)-based platform. For applying the sediment yield model, a basin specific parameter was validated on the basis of field data, that, ranging from 0.6 to 1.2 for the 19 gauging stations. The calculated specific sediment yield ranged from 17 to $181t/km^2.yr$ in the various basin sizes of Korea. We obtained reasonable sediment yield values when comparing the measured data trends around the world with those in Korean basins.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권5호
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• pp.1414-1430
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• 2022

Due to the Internet of Things popularity, many agricultural data are collected by sensors automatically. The abundance of agricultural data makes precise prediction of rice yield possible. Because the climate factors have an essential effect on the rice yield, we considered the climate factors in the prediction model. Accordingly, this paper proposes a machine learning model for rice yield prediction in Taiwan, including the genetic algorithm and support vector regression model. The dataset of this study includes the meteorological data from the Central Weather Bureau and rice yield of Taiwan from 2003 to 2019. The experimental results show the performance of the proposed model is nearly 30% better than MARS, RF, ANN, and SVR models. The most important climate factors affecting the rice yield are the total sunshine hours, the number of rainfall days, and the temperature.The proposed model also offers three advantages: (a) the proposed model can be used in different geographical regions with high prediction accuracies; (b) the proposed model has a high explanatory ability because it could select the important climate factors which affect rice yield; (c) the proposed model is more suitable for predicting rice yield because it provides higher reliability and stability for predicting. The proposed model can assist the government in making sustainable agricultural policies.

• 자원ㆍ환경경제연구
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• 제9권2호
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• pp.285-309
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• 2000

One of the main issues in natural resource economics is estimating the amount of stock and the biological growth functions of renewable natural resources. Since the stock level is not directly observed the usual econometric approaches cannot be employed for this purpose. The maximum entropy approach has been suggested as a useful alternative to estimate the dynamic model of natural resource use. This study estimates the stock and the growth function of Korean anchovy using the data for yield and yield efforts. The results show that the current level of anchovy yield exceeds its maximum sustainable yield, which implies that the stock will decrease substantially over time.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2018년도 학술발표회
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• pp.106-106
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• 2018

Ecosystem service valuation is a crucial step for the sustainable management of watershed. In the context of various ecosystem services provided by watershed, this study, particularly deals with water yield computation in Bagmati Basin of Nepal. The water availability per population in Bagmati Basin is lowest compared to other basins in Nepal. Also, the rate of urbanization is rapidly growing over a decade. In this regard, the objectives of this study are 1) to compute the total water yield of the basin along with computation on a sub-watershed scale, and 2) Study the impacts of land use change on water yield based on CLUE-S model. For the study, Integrated Valuation of Environmental Services and Tradeoffs (InVEST), a popular model for ecosystem service assessment based on Budyko hydrological method is used to compute water yield. As well, CLUE-S model is used to study land use change, which is further related to study variation on water yield. The sub-watershed wise outcome of the study is expected to provide the guidelines for the effective and economic management of a watershed on a regional scale.

• 한국수산과학회지
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• 제34권4호
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• pp.359-364
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• 2001

복수어구에 의한 단일 어종 자원의 평가모델은 단일 어종에 대한 복수어구의 어획노력량이 다르므로 어업별 어획노력량을 하나의 노력단위로 표준화하여, Fox (1970)에 의한 잉여생산량모델에 적용함으로써, 최대지속적생산량, 최대경제적생산량 및 적정어획 노력량의 값을 추정하였다. 여기서는 참조기에 대한 대형기선저인 망쌍끌이어업과 근해안강망어업에 대해 적용하였고, 이 두 어업에 대한 경제성 분석을 통하여 순이익을 추정하였다. 참조기에 대한 어업별 순이익의 변동을 비교 분석한 결과 두 어업의 경제성은 근해안강망어업이 대형기선저인망쌍끌이어업 보다 더 나은 것으로 분석되었으며, 두 어업의 순이익을 같게 하기 위해서는 대형기 선저인망쌍끌이어업의 노력량을 현재보다 증가시키고 근해안강망 어업의 노력량은 낮춰야 한다.

• 수산해양교육연구
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• 제18권1호
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• pp.19-30
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• 2006

For fishery stock assessment and optimum sustainable yield of anchovy in Korea, surplus production(SP) models and a maximum entropy(ME) model are employed in this paper. For determining appropriate models, five traditional SP models-Schaefer model, Schnute model, Walters and Hilborn model, Fox model, and Clarke, Yoshimoto and Pooley (CYP) model- are tested for effort and catch data of anchovy that occupies 7% in the total fisheries landings of Korea. Only CYP model of five SP models fits statistically significant at the 10% level. Estimated intrinsic growth rates are similar in both CYP and ME models, while environmental carrying capacity of the ME model is quite greater than that of the CYP model. In addition, the estimated maximum sustainable yield(MSY), 213,287 tons in the ME model is slightly higher than that of CYP model (198,364 tons). Biomass for MSY in the ME model, however, is calculated 651,000 tons which is considerably greater than that of the CYP model (322,881 tons). It is meaningful in that two models are compared for noting some implications about any significant difference of stock assessment and their potential strength and weakness.

• 한국환경과학회지
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• 제9권1호
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• pp.49-55
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• 2000

An EMERGY analysis of the main energy flows driving the economy of humans and life support systems consists of environmental energies, fuels, and imports, all expresses as solar emjoules. Total EMERGY use(720.0 E20 sej/yr) of the Nakdong River Basin is 96 per cent from imported sources, fuels and goods and services. EMERGY flows from the environment such as rain and geological uplift flux accounted for only 4 percent of total EMERGY use. Consequently, the ratio of outside investment to attracting natural resources was large, like other industrialized areas. EMERGY use per person in the Nakdong River Basin indicates a moderate EMERGY standard of living, even though the indigenous resources are very poor. Population of 6.66 million people in 1996 is already in excess of carrying capacity of the basin. Carrying capacity for steady state based on its renewable sources in only 0.226 million people. EMERGY yield ratio and environment loading ratio were 1.07 and 28.52, respectively. EMERGY sustainability index, a ratio of EMERGY yield ratio to environment loading ratio, is therefore less than one, which is indicative of highly developed consumer oriented economies. This study suggests that the economic structure of the Nakdong River Basin should be transformed from the present industrial structure to the social-economic structure based on an ecological-recycling concept for the sustainable use of the Nakdong River.

• 수산해양기술연구
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• 제52권4호
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• pp.394-402
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• 2016

In order to manage and rebuild fishery resources, the fishing effort should be controlled effectively. Especially in the setting up of the proper level of fishing efforts, economic standards as well as biological standards must be carefully considered to promote the sustainable and economically viable development of fisheries. This study aimed to analyze the optimal economic fishing effort ($E_{MEY}$) as the most economically efficient one for the Eastern Sea Danish seine fisheries. The results showed that the optimal economic fishing effort ($E_{MEY}$) of Eastern Sea Danish seine fisheries for blackfin flounder should be reduced by about 27%. That is, reducing fishing efforts up to the level of $E_{MEY}$ could lead to the reduction of fishing costs, thereby resulting in the increased fishing profits.

• 수산경영론집
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• 제33권2호
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• pp.75-98
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• 2002

As a contribution to developing fishery stock assessment, optimum sustainable yield and its international standards such as MSY, MEY, and dynamic MEY for six recommended fisheries are developed using bio-economic models. For selecting the appropriate model, five models - Schaefer, Schnute, Walters and Hilborn, Fox, and CY&P models are tested in effort and catch data of six species. Surprisingly all the models except the CY&P model failed to satisfy statistical standards such as goodness-of-fitness and reliability. Generally, the CY&P model holds good fitness and statistically significant level for all of six fisheries. However, the CY&P model for squid, where the intrinsic growth rate is high, could not explain MSY, MEY, and dynamic MEY appropriately. This study makes a contribution to develop the modified model for the intrinsic growth rate of 1. The reformulated model represents the results reasonably even though the estimated equation has not good fitness. Although most of the CY&P models appear to have good fits and validated results for some cases, these models also seem to be quite sensitive to parameters which means a more stable model should be developed and data should carefully be handled. In particular biological and technical interactions such as multispecies, predator prey relationship, age structure and mortality should be taken into account. In addition, economic factors and fishing efforts such as price, cost, technical change and a reasonable function of fishing input should simultaneously be considered.

• 수산해양교육연구
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• 제27권3호
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• pp.821-832
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• 2015

The aims of this study are to estimate the optimal vessel reduction scales and these direct economic effects of coastal and offshore fisheries in the Republic of Korea. To estimate respectively optimal fishing efforts of individual fishery by species in coastal and offshore fisheries, we adopted appropriate fishing power of each species published by National Fisheries Research and Development Institute and also considered biological and socio-economic factors such as the bycatch rate, the profit rate, the efficiency of resource use, the average age of fishing vessel, the intention of vessel reduction, and the annual changes in vessels by other factors. The direct economic effects of the optimal vessel reduction in coastal and offshore fisheries based on maximum sustainable yield and 2/3 maximum sustainable yield was calculated by a cost-benefit analysis. This study showed that optimal reduction numbers of vessels engaged in coastal and offshore fisheries were 4,431 and 374 vessels and the direct economic effects in coastal and offshore fisheries were about 371.7 and 569.4 billion won and these NPV and BCR were 111.7 billion won and 1.65 and 342.6 billion won and 4.97 respectively.