• Environmental and Resource Economics Review
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• v.28 no.3
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• pp.415-435
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• 2019

The purpose of this study is to analyze the returns to scale by estimating the bigeye tuna production function of Korean distant longline fisheries in WCFPC waters. In the analysis, number of crews, vessel tonnage, number of hooks, and bigeye tuna biomass are used as input variables and the catch amount of bigeye tuna is used as an output variable in the Cobb-Douglas production function. Prior to the function estimation, the biomass of bigeye tuna was estimated by the Bayesian state-space model. Results showed that the fixed effect model was selected based on the hausman test, and vessel tonnage, hooks, and biomass would have direct effects on the catch amount. In addition, it was shown that the bigeye tuna distant longline fisheries in WCFPC water would have increasing returns to scale.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.8
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• pp.403-410
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• 2016

During expressway construction it has been input a lot of material, but it does not manage to estimate quantitatively. In this study, the total material requirement for construction of expressway, which separated direct material requirement and indirect material requirement each section was quantified by combining life cycle assessment (LCA) and material flow analysis (MFA). In the direct material requirement, sand 2.27E + 04 ton/km, limestone 1.02E + 04 ton/km and gravel 4.47E + 03 ton/km were required, in the indirect material requirement, gravel 2.75E + 04 ton/km, iron 9.80E + 03 ton/km and coal 9.74E + 03 ton/km were required. Material such as sand, limestone which has high direct material requirement is require of excess input prevention from construction site, and material such as iron, rare metals(chrome, nickel) and coal which has high indirect material requirement is require additional studies of resource management.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2006.11a
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• pp.444-447
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• 2006

Construction managers need to pay a close attention to the resource utilization in order to deliver the construction project successfully. Construction scheduling is crucial for resource control in that it provides information when and how much to bring down work force to sites. In scheduling, activity duration is projected based on the productivity of historical data or the intuition of scheduler. This paper studies the opportunity of applying cost-based productivity for estimating activity duration. For cost-based productivity, the cost of resource is used as an input and the work quantities as an output. Out of historical data, regression model has been developed to understand the validity of applying cost-based productivity in projecting activity duration. The result of study will work as a prerequisite for implementing the environment of database-based construction scheduling.

• Environmental and Resource Economics Review
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• v.15 no.4
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• pp.673-692
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• 2006

In order to test for the dynamic optimality condition for the use of nonrenewable resource, it is necessary to estimate the shadow value of the resource in situ. In the previous literatures, a time series for in situ price has been derived either as the difference between marginal revenue and marginal cost or by differentiating with respect to the quantity of ore extracted the restricted cost function in which the quantity of ore is quasi-fixed. However, not only inconsistent estimates are likely to be generated due to the nonmalleability of capital, but the estimate of marginal revenue will be affected by market power. Since firms will likely fail to minimize the cost of the reproducible inputs subject to market prices under realistic circumstances where imperfect factor markets, strikes, or government regulations are present, the shadow in situ values obtained by estimating the restricted cost function can be biased. This paper provides a valid methodology for checking the dynamic optimality condition for a nonrenewable resource by using the input distance function. Our methodology has some advantages over previous ones: only data on quantities of inputs and outputs are required; nor is the maintained hypothesis of cost minimization required; adoption of linear programming enables us to circumvent autocorrelated errors problem caused by use of time series or panel data. The dynamic optimality condition for domestic coal mining does not hold for constant discount rates ranging from 2 to 20 percent over the period 1970~1993. The dynamic optimality condition also does not hold for variable rates ranging from fourth to four times the real interest rate.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2003.05a
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• pp.66-67
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• 2003

현재 우리나라는 어업 자원의 감소가 심각한 문제로 대두되고 있으며 일부 어종은 고갈될 위기에 처해 있다. 자원의 회복을 도모하면서 수산업을 지속적으로 발전시키기 위해서는 과학적인 자원 관리가 필요하다. 과학적인 자원 관리를 위해서는 현재 사용하고 있는 어구의 어획 노력량을 정량적으로 평가하고 그에 따른 어획노력량의 합리적인 투입 관리가 이루어져야 한다. (중략)

• Environmental and Resource Economics Review
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• v.13 no.1
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• pp.33-47
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• 2004

Even though the price of extracted but unprocessed coal has been available in Korea, the use of it as scarcity index would be inappropriate because of price subsidy. Following Halvorsen and Smith(1984), Kim and Lee(2002) derived estimates of the shadow price of unextracted coal by estimating the restricted cost function and differentiating with respect to the quantity of coal extracted. In Korea, however, due to the limited data the capital prices have been computed inconsistently case by case without relying on the robust formula like the Christensen-Jorgenson methodology used in US, which could result in biased estimators of the restricted cost function. In the paper the shadow prices of the resources in situ are obtained by measuring an input distance function defined by Shephard (1970), which requires only the data on the quantities of inputs and output. Empirical results for the Korean coal mining industry show that these shadow prices as a coal scarcity have increased fast by approximately three times in comparisons with those obtained by Kim and Lee.

• Economic and Environmental Geology
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• v.41 no.1
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• pp.133-144
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• 2008

The outputs from the fundamental research program of the Korea Institute of Geoscience and Mineral Resources (KIGAM) were analyzed using the research budget and manpower as input variables. The analysis was performed based on the research outputs of the past 3 years (FY2004 to 2006). More articles and patents came out in applied and development research areas among the geosciences fields. The statistical analysis indicates that each sub-field has different characteristics in research outputs. Research articles, patents, and research budget increase as the manpower increase. But research articles and patents do not always show positive relations to research budget.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.3
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• pp.253-259
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• 2021

Plastic wastes generated from household waste are separated by mixed discharge with foreign substances, and recycling is relatively low. In this study, the effect of the ratio and content of mixed plastic waste coarse aggregate(MPWCA)s and mixed plastic waste fine aggregate(MPWFA)s filled with blast furnace slag fine powder on the slump and compressive strength of concrete was evaluated experimentally. The MPWCAs were found to have a similar fineness modulus, but have a single particle size distribution with a smaller particle size compared to coarse aggregates. However, the MPWFAs were found to have a single particle size distribution with a larger fineness modulus and particle size compared to fine aggregates. Meanwhile, the effect of improving the density and filling pores by the blast furnace slag fine power was found to be greater in the MPWFA compared to the MPWCA. As the amount of the mixed plastic waste aggregate(MPWA)s increased, the slump and compressive strength of concrete decreased. In particular, the lower the slump and compressive strength of concrete was found to decrease the greater the amount of MPWFA than MPWCA when the amount of MPWA was the same. This is because of the entrapped air and voids formed under the angular- and ROD-shaped aggregates among the MPWFAs. On the other hand, the addition of the admixture and the increase in the unit amount of cement were found to be effective in improving the compressive strength of the concrete with MPWAs.

• Environmental and Resource Economics Review
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• v.8 no.1
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• pp.75-94
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• 1998

철강산업에 있어서 공해저감시설의 설치와 증 개축시 발생하는 제반 문제점과 함께 불완전한 시장과 제약된 경영여건하에서 각 기업들은 주어진 요소의 시장가격으로 생산비용 최소화의 실현과 더불어 합리적이며 효율적인 생산활동을 하고 있다고는 할 수 없다. 본 연구에서는 한국 철강산업을 대상으로 일반비용 함수 방식에 의한 계수검정을 실시하여 공해저감시설 또는 자본을 포함한 각 생산요소의 상대가격 효율성 달성 여부를 알아본다. 그리고 비효율성으로 인한 생산비용의 상승효과를 측정하고 공해저감자본의 실제 투입량과 적정수준과의 차이를 측정하여 공해저감자본에 대한 적정 투입률을 분석한다. 측정 결과, 상대가격의 비효율성으로 인하여 1982년부터 1994년까지의 기간 동안 철강산업의 생산비용이 연평균 약 13.6% 증가되었으며 공해저감자본은 적정수준에 비해 연평균 48.4% 적게 투입된 것으로 나타났다.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2004.05a
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• pp.53-58
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• 2004

동제련 공정중 고품질의 전기동을 효율적으로 생산하기 위해서는 Anode중에 적정량의 비소(As)가 필요하다. 그러나 Cu가 약30% 함유되어 있는 동정광에 함유된 비소는 Smelting Furnace 용련과정에서 비소 특성상 약 70%가 Offgas로 휘발되어 황산공장으로 유입 처리되고, 나머지 30%만 아노드(Anode)로 유입되므로 별도로 전련공정에서 발생된 Cu-Cement(비소 함유)를 정제로에 Recycle 하고 있으며, 부족시 추가로 비소 Source를 구입하여 정제로에 투입하고 있다. 이를 효과적으로 해결하기 위하여 현재 위탁처리를 하고있는 As가 함유된 폐수처리 2차 중화시 발생된 2차 Cake 60W.T/D중 30W.T/D를 기존 Converter Slag 건조용 Rotary Dryer를 이용하여 Converter Furnace에 Recycle 함으로써 전련 Anode에 필요한 비소를 공급하고, 또한 2차 Cake에 혼입되어 있는 CaO 활용으로 부재료 절감, 유가금속(Cu등) 회수등 및 2차 Cake 위탁처리비용을 절감하며, Cu-Cement는 Smelting Furnace에 투입하여 정제로 투입시 발생되는 문제점들을 동시에 해결코자 한다.